Login| Sign Up| Help| Contact|

Patent Searching and Data


Title:
CHARGING PUMP SYSTEM FOR SUPPLYING A WORKING FLUID TO BEARINGS IN A SUPERCRITICAL WORKING FLUID CIRCUIT
Document Type and Number:
WIPO Patent Application WO/2014/160257
Kind Code:
A1
Abstract:
Provided herein are a heat engine system and a method for generating energy, such as transforming thermal energy into mechanical energy and/or electrical energy. The heat engine system may have a single charging pump for efficiently implementing at least two independent tasks. The charging pump may be utilized to remove working fluid (e.g., CO2) from and/or to add working fluid into a working fluid circuit during inventory control of the working fluid. The charging pump may be utilized to transfer or otherwise deliver the working fluid as a cooling agent to bearings contained within a bearing housing of a system component during a startup process. The heat engine system may also have a mass control tank utilized with the charging pump and configured to receive, store, and distribute the working fluid.

Inventors:
VERMEERSCH, Michael Louis (2603 Buckeye Blvd, Ravenna, Ohio, 44266, US)
Application Number:
US2014/026173
Publication Date:
October 02, 2014
Filing Date:
March 13, 2014
Export Citation:
Click for automatic bibliography generation   Help
Assignee:
ECHOGEN POWER SYSTEMS, L.L.C. (365 Water Street, Akron, Ohio, 44308, US)
VERMEERSCH, Michael Louis (2603 Buckeye Blvd, Ravenna, Ohio, 44266, US)
International Classes:
F28D20/00; F28D17/00
Domestic Patent References:
WO2008121070A12008-10-09
WO2013028088A12013-02-28
Foreign References:
US20130036736A12013-02-14
US6571548B12003-06-03
US8281593B22012-10-09
US20120131920A12012-05-31
US4164848A1979-08-21
Other References:
See also references of EP 2972044A4
Attorney, Agent or Firm:
NOLTE, N. Alexander et al. (Edmonds & Nolte, PC10411 Westheimer Road,Suite 20, Houston Texas, 77042, US)
Download PDF:
Claims:
Claims:

1 . A heat engine system, comprising:

a working fluid circuit having a high pressure side and a low pressure side and being configured to flow a working fluid therethrough, wherein the working fluid comprises carbon dioxide and at least a portion of the working fluid is in a supercritical state;

a heat exchanger fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit, configured to be fluidly coupled to and in thermal communication with a heat source, and configured to transfer thermal energy from the heat source to the working fluid within the high pressure side;

an expander fluidly coupled to the working fluid circuit and disposed between the high pressure side and the low pressure side and configured to convert a pressure drop in the working fluid to mechanical energy;

a driveshaft coupled to the expander and configured to drive a device with the mechanical energy;

a system pump fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side of the working fluid circuit and configured to circulate the working fluid through the working fluid circuit;

a recuperator fluidly coupled to the working fluid circuit and operative to transfer thermal energy between the high pressure side and the low pressure side of the working fluid circuit; a cooler in thermal communication with the working fluid in the low pressure side of the working fluid circuit and configured to remove thermal energy from the working fluid in the low pressure side of the working fluid circuit; and

a mass management system fluidly coupled to the working fluid circuit and comprising: a mass control tank fluidly coupled to the low pressure side of the working fluid circuit and configured to receive the working fluid from the working fluid circuit; and

a charging pump fluidly coupled to the mass control tank and configured to transfer the working fluid from the mass control tank to:

the low pressure side of the working fluid circuit by an inventory supply line; and

a bearing housing substantially encompassing bearings contained within a system component.

2. The heat engine system of claim 1 , wherein the mass control tank comprises a cryogenic storage vessel.

3. The heat engine system of claim 2, wherein the cryogenic storage vessel has an internal pressure within a range from about 345 kPa to about 3447 kPa.

4. The heat engine system of claim 1 , further comprising an inventory return line fluidly coupled to and between the mass control tank and the low pressure side of the working fluid circuit downstream of the condenser.

5. The heat engine system of claim 4, wherein the inventory return line comprises at least one valve configured to control the flow of the working fluid from the low pressure side of the working fluid circuit to the mass control tank.

6. The heat engine system of claim 1 , wherein the inventory supply line is fluidly coupled to and between the charging pump and the low pressure side of the working fluid circuit upstream of the system pump.

7. The heat engine system of claim 6, wherein the inventory supply line comprises at least one valve configured to control the flow of the working fluid from the mass control tank, through the charging pump, and to the low pressure side of the working fluid circuit.

8. The heat engine system of claim 1 , further comprising a bearing gas supply line fluidly coupled to and between the charging pump and the bearing housing.

9. The heat engine system of claim 8, wherein the bearing gas supply line comprises at least one valve configured to control the flow of the working fluid from the mass control tank, through the charging pump, and to the bearing housing.

10. The heat engine system of claim 1 , wherein the system component comprises the system pump.

1 1 . The heat engine system of claim 10, wherein the system pump comprises a turbopump.

12. The heat engine system of claim 1 , wherein the system component comprises a turbopump, a turbocompressor, a turboalternator, a power generation system, or other turbo machinery.

13. The heat engine system of claim 1 , wherein the system component comprises a power generation system that comprises the expander, a power generator, and the bearing housing substantially encompassing the bearings.

14. The heat engine system of claim 13, wherein the power generation system further comprises a gearbox and the driveshaft coupled between the expander and the power generator.

15. The heat engine system of claim 1 , wherein the charging pump comprises an electric- motorized pump, a mechanical-motorized pump, or a variable frequency driven pump.

16. The heat engine system of claim 1 , further comprising a variable frequency drive coupled to the system pump and configured to control mass flow rate or temperature of the working fluid within the high pressure side of the working fluid circuit.

17. The heat engine system of claim 1 , further comprising a generator or an alternator coupled to the expander by the driveshaft and configured to convert the mechanical energy into electrical energy.

18. The heat engine system of claim 1 , further comprising a turbopump in the working fluid circuit, wherein the turbopump contains a pump portion coupled to the expander by the driveshaft and the pump portion is configured to be driven by the mechanical energy.

19. The heat engine system of claim 1 , further comprising a turbopump in the working fluid circuit, wherein the turbopump comprises a pump portion coupled to an expansion device.

20. The heat engine system of claim 19, wherein the pump portion of the turbopump is fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side of the working fluid circuit and configured to circulate the working fluid through the working fluid circuit.

21 . The heat engine system of claim 19, wherein the expansion device of the turbopump is fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side of the working fluid circuit and configured to drive the pump portion by mechanical energy generated by the expansion of the working fluid.

22. The heat engine system of claim 19, wherein the expansion device and the expander are both turbines.

23. A heat engine system, comprising:

a working fluid circuit having a high pressure side and a low pressure side and being configured to flow a working fluid therethrough, wherein the working fluid comprises carbon dioxide and at least a portion of the working fluid is in a supercritical state;

a heat exchanger fluidly coupled to and in thermal communication with the working fluid circuit within the high pressure side, configured to be fluidly coupled to and in thermal communication with a heat source, and configured to transfer thermal energy from the heat source to the working fluid within the high pressure side;

an expander fluidly coupled to the working fluid circuit and disposed between the high pressure side and the low pressure side and configured to convert a pressure drop in the working fluid to mechanical energy;

a driveshaft coupled to the expander and configured to drive a device with the mechanical energy;

a turbopump comprising a pump portion coupled to an expansion device, wherein the pump portion is fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side and configured to circulate the working fluid through the working fluid circuit, the expansion device is fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side and configured to drive the pump portion by mechanical energy generated by the expansion of the working fluid; and

a mass management system fluidly coupled to the working fluid circuit and comprising: a mass control tank fluidly coupled to the working fluid circuit and configured to receive, store, and deliver the working fluid; and

a charging pump fluidly coupled to the mass control tank and configured to transfer the working fluid from the mass control tank to:

the low pressure side of the working fluid circuit; and a bearing housing substantially encompassing bearings contained within the turbopump.

24. The heat engine system of claim 23, further comprising a recuperator fluidly coupled to the working fluid circuit and operative to transfer thermal energy between the high pressure side and the low pressure side of the working fluid circuit.

25. The heat engine system of claim 23, further comprising a cooler in thermal communication with the working fluid in the low pressure side of the working fluid circuit and configured to remove thermal energy from the working fluid in the low pressure side of the working fluid circuit.

26. A method for transforming energy with a heat engine system, comprising:

circulating a working fluid within a working fluid circuit by a system pump, wherein the working fluid circuit has a high pressure side and a low pressure side and at least a portion of the working fluid is in a supercritical state;

transferring thermal energy from a heat source to the working fluid by a heat exchanger fluidly coupled to and in thermal communication with the heat source and the high pressure side of the working fluid circuit;

flowing the working fluid into an expander and converting the thermal energy from the working fluid to mechanical energy of the expander;

flowing a portion of the working fluid from the low pressure side to a mass control tank fluidly coupled to the working fluid circuit and configured to receive, store, and deliver the working fluid;

flowing the working fluid from the mass control tank, through a charging pump, and to: a point within the low pressure side of the working fluid circuit upstream of the system pump; and

a bearing housing substantially encompassing bearings contained within a system component;

wherein the charging pump is fluidly coupled to and disposed downstream of the mass control tank, is fluidly coupled to and disposed upstream of the point within the low pressure side of the working fluid circuit, and is fluidly coupled to and disposed upstream of the bearing housing; and

flowing the working fluid over the bearings disposed within the bearing housing while cooling the bearings.

27. The method of claim 26, further comprising converting the mechanical energy into electrical energy by a power generator coupled to the expander.

28. The method of claim 26, further comprising adjusting at least one valve to control the rate of the working fluid flowing from the low pressure side of the working fluid circuit through an inventory return line to the mass control tank.

29. The method of claim 26, further comprising adjusting at least one valve to control the rate of the working fluid flowing from the charging pump through an inventory supply line to the point within the low pressure side of the working fluid circuit.

30. The method of claim 26, further comprising adjusting at least one valve to control the rate of the working fluid flowing from the charging pump through a bearing gas supply line to the bearing housing.

Description:
Charging Pump System for Supplying a Working Fluid to Bearings

in a Supercritical Working Fluid Circuit

Cross-Reference to Related Applications

[001] This application claims benefit of U .S. Prov. Appl. No. 61 /779,686, filed on March 13, 2013, the contents of which are hereby incorporated by reference to the extent not inconsistent with the present disclosure.

Background

[002] Waste heat is often created as a byproduct of industrial processes where flowing streams of high-temperature liquids, gases, or fluids must be exhausted into the environment or removed in some way in an effort to maintain the operating temperatures of the industrial process equipment. Some industrial processes utilize heat exchanger devices to capture and recycle waste heat back into the process via other process streams. However, the capturing and recycling of waste heat is generally infeasible by industrial processes that utilize high temperatures or have insufficient mass flow or other unfavorable conditions.

[003] Waste heat can be converted into useful energy by a variety of turbine generator or heat engine systems that employ thermodynamic methods, such as Rankine cycles. Rankine cycles and similar thermodynamic methods are typically steam-based processes that recover and utilize waste heat to generate steam for driving a turbine, turbo, or other expander connected to an electric generator, a pump, or other device.

[004] An organic Rankine cycle utilizes a lower boiling-point working fluid, instead of water, during a traditional Rankine cycle. Exemplary lower boiling-point working fluids include hydrocarbons, such as light hydrocarbons (e.g., propane or butane) and halogenated hydrocarbon, such as hydrochlorofluorocarbons (HCFCs) or hydrofluorocarbons (H FCs) (e.g., R245fa). More recently, in view of issues such as thermal instability, toxicity, flammability, and production cost of the lower boiling-point working fluids, some thermodynamic cycles have been modified to circulate no n- hydrocarbon working fluids, such as ammonia.

[005] The turbines or expanders utilized in a heat engine generally have journal-type or similar bearings at each end of the driveshaft in order to permit rotation. The bearings tend to become overheated and fail if not continuously cooled during turbine operation. A variety of cooling fluids, gases, and liquids have been used to cool the bearings disposed on the driveshaft within the heat engine. Generally, the cooling fluids that are exposed to the bearings while the driveshaft is spinning are a different type of fluid than the working fluid utilized by the heat engine. Exemplary cooling fluids include gaseous state fluids, such as nitrogen or argon, as well as liquid state fluids, such as synthetic or natural bearing or lubricant oils. Additional storage and recovery tanks, pumps, valves, and other equipment are required to contain and utilize the cooling fluids during turbine operation. Therefore, the heat engine having an independent cooling fluid system for the bearings has additional complexity and expense.

[006] Therefore, there is a need for a heat engine system and a method for generating mechanical energy and/or electrical energy that utilizes the working fluid to cool bearings, minimizes additional components relative to traditional cooling systems, and maximizes the efficiency of the heat engine system while transforming energy.

Summary

[007] Embodiments of the disclosure generally provide a heat engine system and a method for transforming energy, such as generating mechanical energy and/or electrical energy from thermal energy. Embodiments provide that the heat engine system may have a single charging pump for efficiently implementing at least two independent tasks. In one aspect, the charging pump may be utilized to remove working fluid (e.g., CO2) from and/or to add working fluid into a working fluid circuit during inventory control (mass management) of the working fluid. In another aspect, the charging pump may be utilized to transfer or otherwise deliver the working fluid - as a cooling agent - to bearings contained within a bearing housing of a system component during a startup process. The heat engine system may also have a mass control tank utilized with the charging pump and configured to receive , store, and distribute the working fluid .

[008] In one embodiment, a heat engine system is provided and contains a working fluid circuit having a high pressure side and a low pressure side and containing a working fluid. The working fluid generally contains carbon dioxide and at least a portion of the working fluid may be in a supercritical state. The heat engine system also contains at least one heat exchanger fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit, configured to be fluidly coupled to and in thermal communication with a heat source, and configured to transfer thermal energy from the heat source to the working fluid within the high pressure side. The heat engine system further contains an expander or turbine fluidly coupled to the working fluid circuit, disposed between the high and low pressure sides, and configured to convert a pressure drop in the working fluid to mechanical energy. The heat engine system also contains a driveshaft coupled to the expander and configured to drive a device with the mechanical energy. [009] The heat engine system further contains at least one system pump (e.g. , start pump or turbopump) fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side of the working fluid circuit and configured to circulate the working fluid through the working fluid circuit. In one example, the heat engine system contains a turbopump that has a pump portion coupled to a drive turbine or other an expansion device as well as a bearing housing that completely, substantially, or partially encompasses or otherwise encloses bearings. The pump portion may be fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side and may be configured to circulate the working fluid through the working fluid circuit. The drive turbine or expansion device may be fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side and configured to drive the pump portion by mechanical energy generated by the expansion of the working fluid.

[010] The heat engine system further contains at least one recuperator fluidly coupled to the working fluid circuit and operative to transfer thermal energy between the high pressure side and the low pressure side of the working fluid circuit. The heat engine system also contains a cooler in thermal communication with the working fluid in the low pressure side of the working fluid circuit and configured to remove thermal energy from the working fluid in the low pressure side of the working fluid circuit. In some examples, the cooler may be a condenser configured to control a temperature of the working fluid in the low pressure side of the working fluid circuit by transferring thermal energy from the working fluid in the low pressure side to a cooling loop outside of the working fluid circuit.

[011] The heat engine system also contains an inventory control system or a mass management system (MMS) fluidly coupled to the working fluid circuit. The MMS contains the mass control tank fluidly coupled to the low pressure side of the working fluid circuit and configured to receive, store, and distribute the working fluid. For example, the mass control tank may be configured to receive the working fluid from the working fluid circuit, store the working fluid, and subsequently distribute the working fluid into the working fluid circuit and/or at least one bearing housing. The MMS also contains a charging pump fluidly coupled to the mass control tank and configured to transfer the working fluid from the mass control tank to the low pressure side of the working fluid circuit by an inventory supply line . The charging pump may also be configured to transfer the working fluid from the mass control tank to the bearing housing that completely, substantially, or partially encompasses or otherwise encloses bearings contained within a system component (e.g. , turbomachinery). The charging pump may be an electric-motorized pump, a mechanical-motorized pump, a variable frequency driven pump, a turbopump, or another type of pump.

[012] The heat engine system further contains an inventory return line fluidly coupled to and between the mass control tank and the low pressure side of the working fluid circuit, such as downstream of the cooler or condenser. The inventory return line generally contains at least one valve, such as an inventory return valve, configured to control the flow of the working fluid from the low pressure side of the working fluid circuit to the mass control tank. The inventory supply line may be fluidly coupled to and between the charging pump and the low pressure side of the working fluid circuit upstream of the system pump. The inventory supply line generally contains at least one valve, such as an inventory supply valve, configured to control the flow of the working fluid from the mass control tank, through the charging pump, and to the low pressure side of the working fluid circuit. The heat engine system further contains a bearing gas supply line fluidly coupled to and between the charging pump and the bearing housing. The bearing gas supply line generally contains at least one valve, such as a bearing gas supply valve, configured to control the flow of the working fluid from the mass control tank, through the charging pump, and to the bearing housing.

[013] In various examples, the system component containing the bearings within the bearing housing may be a turbopump, a turbocompressor, a turboalternator, a power generation system, or other turbomachinery. In some examples, the system component may be the system pump, such as a turbopump containing a drive turbine and the bearing housing. In other examples, the system component may be a power generation system that contains a power turbine or other expander, a power generator, and the bearing housing that completely, substantially, or partially encompasses or otherwise encloses the bearings. The power generation system may further contain a gearbox and the driveshaft coupled between the power turbine and the power generator.

[014] In some examples, the mass control tank may be a cryogenic storage vessel. The cryogenic storage vessel may have an internal pressure within a range from about 10 psig (pounds per square inch gauge; approximately 69 kPa) to about 800 psig (approximately 5516 kPa), more narrowly within a range from about 50 psig (approximately 345 kPa) to about 500 psig (approximately 3447 kPa), more narrowly within a range from about about 100 psig (approximately 689 kPa) to about 450 psig (approximately 3103 kPa), and more narrowly within a range from about 200 psig (approximately 1379 kPa) to about 400 psig (approximately 2758 kPa), for example, about (approximately 2068 kPa). [015] In some examples, the heat engine system further contains a variable frequency drive coupled to the system pump and configured to control mass flow rate or temperature of the working fluid within the high pressure side of the working fluid circuit. In other examples, the heat engine system may also contain a generator or an alternator coupled to the expander by the driveshaft and configured to convert the mechanical energy into electrical energy. In one example, the system pump may be coupled to the expander by the driveshaft and configured to be driven by the mechanical energy for circulating the working fluid through the working fluid circuit. In another example, a pump portion may be coupled to the expander by the driveshaft to form a turbopump and the pump portion may be configured to be driven by the mechanical energy. In yet another example, an independent turbopump may be coupled to the working fluid circuit such that the turbopump contains a pump portion coupled to an expansion device, different than the system pump and the expander. In many examples, the expansion device and the expander are both turbines. Generally, the pump portion of the turbopump may be fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side of the working fluid circuit and may be configured to circulate the working fluid through the working fluid circuit. Also, the expansion device of the turbopump may be fluidly coupled to the working fluid circuit between the low pressure side and the high pressure side of the working fluid circuit and may be configured to drive the pump portion by mechanical energy generated by the expansion of the working fluid.

[016] In other embodiments described herein, a method for transforming energy with a heat engine system is provide and includes circulating a working fluid within a working fluid circuit by a system pump, wherein the working fluid circuit has a high pressure side and a low pressure side and at least a portion of the working fluid may be in a supercritical state. In many examples and during various periods of the generation or power cycle, the high pressure side of the working fluid circuit may contain the working fluid in a supercritical state while the low pressure side of the working fluid circuit may contain the working fluid in a subcritical state and/or a supercritical state. The method further includes transferring thermal energy from a heat source to the working fluid by a heat exchanger fluidly coupled to and in thermal communication with the heat source and the high pressure side of the working fluid circuit and flowing the working fluid into an expander and converting the thermal energy from the working fluid to mechanical energy of the expander. In some examples, the method includes converting the mechanical energy into electrical energy by a power generator coupled to the expander. [017] The method also includes transferring, passing, or otherwise flowing a portion of the working fluid from the low pressure side to a mass control tank fluidly coupled to the low pressure side of the working fluid circuit and configured to receive, store, and deliver the working fluid. The method further includes flowing or transferring working fluid from the mass control tank, through the charging pump, and to a point within the low pressure side of the working fluid circuit upstream of the system pump, as well as flowing or transferring the working fluid from the mass control tank, through the charging pump, and to at least one bearing housing that completely, substantially, or partially encompasses or otherwise encloses bearings contained within a system component. The bearings disposed within the bearing housing may be exposed to and cooled by the working fluid. Therefore, the charging pump may be fluidly coupled to and disposed downstream of the mass control tank, fluidly coupled to and upstream of the point within the low pressure side of the working fluid circuit, and fluidly coupled to and upstream of the bearing housing.

[018] In some embodiments, the method includes adjusting at least one valve, such as an inventory return valve, to control the rate of the working fluid flowing from the low pressure side of the working fluid circuit, through an inventory return line, to the mass control tank. In other embodiments, the method includes adjusting at least one valve, such as an inventory supply valve, to control the rate of the working fluid flowing from the charging pump, through an inventory supply line, to the point within the low pressure side of the working fluid circuit. In other embodiments, the method includes adjusting at least one valve, such as a bearing gas supply valve, to control the rate of the working fluid flowing from the charging pump, through a bearing gas supply line, to the bearing housing.

Brief Description of the Drawings

[019] The present disclosure is best understood from the following detailed description when read with the accompanying Figures. It is emphasized that, in accordance with the standard practice in the industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion.

[020] Figure 1 illustrates an exemplary heat engine system containing a mass control tank and a charging pump, according to one or more embodiments disclosed herein.

[021] Figure 2 illustrates another exemplary heat engine system containing a mass control tank and a charging pump, according to one or more embodiments disclosed herein. [022] Figure 3 is a flow chart illustrating a method for transforming energy with a heat engine system, according to one or more embodiments disclosed herein.

Detailed Description

[023] Embodiments of the disclosure generally provide a heat engine system and a method for generating energy, such as transforming thermal energy into mechanical energy and/or electrical energy. The heat engine system has a single charging pump for efficiently implementing at least two independent tasks. In one aspect, the charging pump may be utilized to conduct inventory control by removing working fluid (e.g., CO2) from and/or adding working fluid into a working fluid circuit of the heat engine system. In another aspect, the charging pump may be utilized during a startup process to transfer or otherwise deliver the working fluid - as a cooling agent - to bearings contained within a bearing housing of a system component (e.g., rotary equipment or turbo machinery) .

[024] A mass control tank (e.g. , cryogenic storage vessel) may be utilized for storing or otherwise containing the working fluid removed from the working fluid circuit, charged into the working fluid circuit, and/or delivered to the bearing housing. Generally, the mass control tank may be fluidly coupled to the working fluid circuit by an inventory return line, a fluid line may be fluidly coupled between the mass control tank and the charging pump, and the charging pump may be fluidly coupled to the working fluid circuit by an inventory supply line. At least one bearing gas supply line may be fluidly coupled to and disposed between the charging pump and the bearing housing. In one example, the bearings and the bearing housing are part of a turbopump that has a drive turbine coupled to a pump portion by a driveshaft. In another example, the bearings and the bearing housing are part of a power generation system that has a power turbine coupled to a power generator by a driveshaft. Since the working fluid may be utilized as the cooling fluid and the charging pump and the mass control tank are utilized for multi-tasks, additional pieces of traditional equipment or components (e.g ., storage vessels, pumps, and other) generally dedicated to managing a cooling media may be omitted from the heat engine system.

[025] The heat engine system and the method for transforming energy are configured to efficiently convert thermal energy of a heated stream (e.g. , a waste heat stream) into valuable mechanical energy and/or electrical energy. The heat engine system utilizes the working fluid in a supercritical state (e.g. , SC-CO2) and/or a subcritical state (e.g. , sub-CC>2) contained within the working fluid circuit for capturing or otherwise absorbing thermal energy of the waste heat stream with one or more heat exchangers. The thermal energy may be transformed to mechanical energy by a power turbine and subsequently transformed to electrical energy by a power generator coupled to the power turbine. The heat engine system contains several integrated sub-systems managed by a process control system for maximizing the efficiency of the heat engine system while generating mechanical energy and/or electrical energy.

[026] Figure 1 depicts an exemplary heat engine system 90, which may also be referred to as a thermal engine system, an electrical generation system, a waste heat or other heat recovery system, and/or a thermal to electrical energy system, as described in one of more embodiments herein. The heat engine system 90 contains a waste heat system 100 and a power generation system 220 coupled to and in thermal communication with each other via a working fluid circuit 202. The working fluid circuit 202 contains the working fluid (e.g. , SC-CO2) and has a high pressure side and a low pressure side. A heat source stream 1 10 flows through heat exchangers 120, 130, and/or 150 disposed within the waste heat system 100. Each of the heat exchangers 120, 130, and/or 150, independently, may be fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit 202, configured to be fluidly coupled to and in thermal communication with a heat source stream 1 10, and configured to transfer thermal energy from the heat source stream 1 10 to the working fluid within the high pressure side of the working fluid circuit 202. Thermal energy may be absorbed by the working fluid within the working fluid circuit 202 and converted to mechanical energy by flowing the heated working fluid through one or more expanders or turbines.

[027] The heat engine system 90 further contains several pumps, such as a turbopump 260 and a start pump 280, disposed within the working fluid circuit 202 and fluidly coupled between the low pressure side and the high pressure side of the working fluid circuit 202. The turbopump 260 and the start pump 280 may be configured to circulate and to pressurize the working fluid throughout the working fluid circuit 202. The turbopump 260 contains a pump portion 262 coupled with a drive turbine 264 and the start pump 280 contains a pump portion 282 and a motor-drive portion 284. In various examples, the start pump 280 may be an electric- motorized pump, a mechanical-motorized pump, or a variable frequency driven pump. The drive turbine 264 of the turbopump 260 may be fluidly coupled to the working fluid circuit 202 downstream of the heat exchanger 150 and the pump portion 262 of the turbopump 260 may be fluidly coupled to the working fluid circuit 202 upstream of the heat exchanger 120. In one example, the drive turbine 264 may be configured to receive and be powered by the working fluid passing through and absorbing thermal energy from the heat exchanger 150. The turbopump 260 may further contain a gearbox and/or a driveshaft 267 coupled between the drive turbine 264 and the pump portion 262. The turbopump 260 further contains a bearing housing 268 which substantially encompasses or encloses the bearings disposed within the turbopump 260.

[028] The heat engine system 90 further contains a power turbine 228 disposed between the high pressure side and the low pressure side of the working fluid circuit 202, fluidly coupled to and in thermal communication with the working fluid, and configured to convert thermal energy to mechanical energy by a pressure drop in the working fluid flowing between the high and the low pressure sides of the working fluid circuit 202. A power generator 240 may be coupled to the power turbine 228 and configured to convert the mechanical energy into electrical energy, a power outlet 242 electrically coupled to the power generator 240 and configured to transfer the electrical energy from the power generator 240 to an electrical grid 244. The power turbine 228 disposed within the power generation system 220 may be fluidly coupled to the working fluid circuit 202 downstream of the heat exchanger 120 and/or heat exchanger 130. In one example, the power turbine 228 may be configured to receive and be powered by the working fluid passing through and absorbing thermal energy from the heat exchanger 120 and/or heat exchanger 130. The power generation system 220 may further contain a gearbox 232 and a driveshaft 230 coupled between the power turbine 228 and the power generator 240. The power generation system 220 further contains a bearing housing 238 which substantially encompasses or encloses the bearings disposed within the power generation system 220.

[029] The heat engine system 90 further contains at least one recuperator, such as recuperators 216 and 218, fluidly coupled to the working fluid circuit and operative to transfer thermal energy between the high and low pressure sides of the working fluid circuit 202. In some examples, the recuperators 216 and 218 are configured to transfer the thermal energy from the low pressure side to the high pressure side. The heat engine system 90 further contains a cooler 274 in thermal communication with the working fluid contained in the low pressure side of the working fluid circuit 202 and configured to remove thermal energy from the working fluid in the low pressure side. In some examples, the cooler 274 may be a condenser configured to control a temperature of the working fluid in the low pressure side of the working fluid circuit 202 by transferring thermal energy from the working fluid in the low pressure side to a cooling loop outside of the working fluid circuit 202.

[030] In one or more embodiments, the heat engine system 90 further contains a mass control tank 286 and a charging pump 170 fluidly coupled to the working fluid circuit 202. The mass control tank 286 and the working fluid circuit 202 share the working fluid (e.g. , carbon dioxide) - such that the mass control tank 286 may receive, store, and disperse the working fluid during various operational steps of the heat engine system 90. In one embodiment, the charging pump 170 may be utilized to conduct inventory control by removing working fluid from the working fluid circuit 202, storing working fluid, and/or adding working fluid into the working fluid circuit 202. In another embodiment, the charging pump 170 may be utilized during a startup process to transfer or otherwise deliver the working fluid - as a cooling agent - from the mass control tank 286 to bearings contained within the bearing housing 268 of the turbopump 260, the bearing housing 238 of the power generation system 220, and/or other system components containing bearings (e.g. , rotary equipment or turbo machinery).

[031] Exemplary structures of the bearing housing 238 or 268 may completely or substantially encompass or enclose the bearings as well as all or part of turbines, generators, pumps, driveshafts, gearboxes, or other components shown or not shown for heat engine 90. The bearing housing 238 or 268 may completely or partially include structures, chambers, cases, housings, such as turbine housings, generator housings, driveshaft housings, driveshafts that contain bearings, gearbox housings, derivatives thereof, or combinations thereof. Figure 1 depicts the bearing housing 238 containing all or a portion of the power turbine 228, the power generator 240, the driveshaft 230, and the gearbox 232 of the power generation system 220. In some examples, the housing of the power turbine 228 is coupled to and/or forms a portion of the bearing housing 238. Similarly, the bearing housing 268 contains all or a portion of the drive turbine 264, the pump portion 262 , and the driveshaft 267 of the turbopump 260. In other examples, the housing of the drive turbine 264 and the housing of the pump portion 262 may be independently coupled to and/or form portions of the bearing housing 268.

[032] In one or more embodiments disclosed herein, at least one bearing gas supply line 196 may be fluidly coupled to and disposed between the charging pump 170 and at least one bearing housing (e.g. , bearing housing 238 or 268) substantially encompassing, enclosing, or otherwise surrounding the bearings of one or more system components. The bearing gas supply line 196 may have or otherwise split into multiple spurs or segments of fluid lines, such as bearing gas supply lines 196a and 196b, which each independently extends to a specified bearing housing 238 or 268, respectively, as illustrated in Figure 1 . In one example, the bearing gas supply line 196a may be fluidly coupled to and disposed between the charging pump 170 and the bearing housing 268 within the turbopump 260. In another example, the bearing gas supply line 196b may be fluidly coupled to and disposed between the charging pump 170 and the bearing housing 238 within the power generation system 220.

[033] Figure 1 further depicts a bearing gas supply valve 198a fluidly coupled to and disposed along the bearing gas supply line 196a. The bearing gas supply valve 198a may be utilized to control the flow of the working fluid from the charging pump 170 to the bearing housing 268 within the turbopump 260. Similarly, a bearing gas supply valve 198b may be fluidly coupled to and disposed along the bearing gas supply line 196b. The bearing gas supply valve 198b may be utilized to control the flow of the working fluid from the charging pump 170 to the bearing housing 238 within the power generation system 220.

[034] Figure 2 depicts an exemplary heat engine system 200 that contains a process system 210 and the power generation system 220 fluidly coupled to and in thermal communication with the waste heat system 100 via a working fluid circuit 202, as described in one of more embodiments herein. The heat engine system 200 may be referred to as a thermal engine system, an electrical generation system, a waste heat or other heat recovery system, and/or a thermal to electrical energy system, as described in one of more embodiments herein. The heat engine system 200 is generally configured to encompass one or more elements of a Rankine cycle, a derivative of a Rankine cycle, or another thermodynamic cycle for generating electrical energy from a wide range of thermal sources. The heat engine system 200 depicted in Figure 2 and the heat engine system 90 of Figure 1 share many common components. The heat engine system 200 generally contains the same components as well as additional components as the heat engine system 90. It should be noted that like numerals shown in the Figures and discussed herein represent like components throughout the multiple embodiments disclosed herein.

[035] In embodiments described herein, heat engine systems 90, 200 are provided and contain a working fluid circuit 202 having a high pressure side and a low pressure side and containing a working fluid. The working fluid may contain carbon dioxide and at least a portion of the working fluid may be in a supercritical state. The heat engine systems 90, 200 also contain at least one heat exchanger, such as heat exchangers 120, 130, and/or 150, fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit 202, configured to be fluidly coupled to and in thermal communication with a heat source 1 10, and configured to transfer thermal energy from the heat source 1 10 to the working fluid within the high pressure side. The heat engine systems 90, 200 further contain a power turbine 228 or other expander, fluidly coupled to the working fluid circuit 202 and disposed between the high pressure side and the low pressure side. The power turbine 228 may be configured to convert a pressure drop in the working fluid to mechanical energy. The heat engine systems 90, 200 also have the driveshaft 230 coupled to the power turbine 228 and configured to drive a device with the mechanical energy. Throughout various embodiments, the device may be an electrical generator or alternator, a pump or compressor, as well other type of equipment or components configured to receive and transform work (e.g. , the mechanical energy) into other useful energy.

[036] The heat engine systems 90, 200 may contain at least one system pump (e.g., a start pump 280, a turbopump 260, or both) fluidly coupled to the working fluid circuit 202 between the low pressure side and the high pressure side of the working fluid circuit 202 and configured to circulate the working fluid through the working fluid circuit 202. In another embodiment, the heat engine systems 90, 200 contain a turbopump 260 that has a pump portion 262 coupled to an expansion device or the drive turbine 264 as well as a bearing housing 268 that completely, substantially, or partially encompasses or otherwise encloses bearings. The pump portion 262 may be fluidly coupled to the working fluid circuit 202 between the low pressure side and the high pressure side and may be configured to circulate the working fluid through the working fluid circuit 202, the expansion device or the drive turbine 264 may be fluidly coupled to the working fluid circuit 202 between the low pressure side and the high pressure side and may be configured to drive the pump portion 262 by mechanical energy generated by the expansion of the working fluid.

[037] The heat engine systems 90, 200 further contain at least one recuperator, such as recuperators 216 and 218, fluidly coupled to the working fluid circuit 202 operative to transfer thermal energy between the high pressure side and the low pressure side of the working fluid circuit 202. The heat engine systems 90, 200 also contain the condenser 274 or other cooler in thermal communication with the working fluid in the low pressure side of the working fluid circuit 202 and configured to remove thermal energy from the working fluid in the low pressure side of the working fluid circuit 202. The cooler or the condenser 274 may be configured to control a temperature of the working fluid in the low pressure side of the working fluid circuit 202 by transferring thermal energy from the working fluid in the low pressure side to a cooling loop disposed outside of the working fluid circuit 202. The cooling loop may be fluidly coupled to the heat engine system 200 by a cooling fluid return 278a and a cooling fluid supply 278b, as depicted in Figure 2.

[038] The heat engine systems 90, 200 also contain a mass management system (MMS) 270 fluidly coupled to the working fluid circuit 202. The MMS 270 contains the mass control tank 286 fluidly coupled to the low pressure side of the working fluid circuit 202 and configured to receive, store, and deliver the working fluid. For example, the mass control tank 286 may be configured to receive the working fluid from the working fluid circuit 202, configured to store the working fluid for subsequent use, and configured to deliver the working fluid into the working fluid circuit 202. The MMS 270 also contains the charging pump 170 fluidly coupled to the mass control tank 286 and configured to transfer the working fluid from the mass control tank 286 to the low pressure side of the working fluid circuit 202 by an inventory supply line 182.

[039] The charging pump 170 may also be configured to transfer the working fluid from the mass control tank 286 to the bearing housings 238, 268 that completely, substantially, or partially encompasses or otherwise encloses bearings contained within a system component. The charging pump 170 may be an electric-motorized pump, a mechanical-motorized pump, a variable frequency driven pump, a turbopump, or another type of pump.

[040] The heat engine systems 90, 200 further contain an inventory return line 172 fluidly coupled to and between the mass control tank 286 and the low pressure side of the working fluid circuit 202, such as downstream of the condenser 274. As depicted in Figures 1 and 2, a fluid line 168 may be fluidly coupled with and extend from the outlet of the condenser 274 and the inventory return line 172 may be fluidly coupled and extend from the fluid line 168 to the mass control tank 286. The inventory return line 172 generally contains at least one valve, such as an inventory return valve 174, configured to control the flow of the working fluid being transferred from the low pressure side of the working fluid circuit 202 and to the mass control tank 286. An inventory line 176 may be fluidly coupled to and between the mass control tank 286 and the charging pump 170. The inventory line 176 may be configured transfer the working fluid contained within the mass control tank 286 to the charging pump 170. The inventory supply line 182 may be fluidly coupled to and between the charging pump 170 and the low pressure side of the working fluid circuit 202 upstream of one of more of the system pumps, such as the pump portion 282 of the start pump 280 and the pump portion 262 of the turbopump 260. As depicted in Figures 1 and 2, the fluid line 186 may be fluidly coupled with and disposed between a junction point of both the inventory supply line 182 and the fluid line 168 and extend to the pump portion 282 of the start pump 280 and/or the pump portion 262 of the turbopump 260. The inventory supply line 182 generally contains at least one valve, such as an inventory supply valve 184, configured to control the flow of the working fluid from the mass control tank 286, through the charging pump 170, and to the low pressure side of the working fluid circuit 202. [041] The heat engine systems 90, 200 further contain bearing gas supply lines 196, 196a, 196b fluidly coupled to and between the charging pump 170 and the bearing housing 238, 268. The bearing gas supply lines 196, 196a, 196b generally contains at least one valve, such as bearing gas supply valves 198a, 198b, configured to control the flow of the working fluid from the mass control tank 286, through the charging pump 170, and to the bearing housing 238, 268.

[042] In various examples, the system component may be a turbopump, a turbocompressor, a turboalternator, a power generation system, or other turbomachinery. In some examples, the system component may be the system pump, such as the turbopump 260 containing the bearing housing 268. In other examples, the system component may be the power generation system 220 that contains the expander or the power turbine 228, the power generator 240, and the bearing housing 238.

[043] In some examples, the mass control tank 286 may be a cryogenic storage vessel. The mass control tank 286 or the cryogenic storage vessel may have an internal pressure from about 10 psig (pounds per square inch gauge; approximately 69 kPa) to about 800 psig (approximately 5516 kPa), about 50 psig (approximately 345 kPa) to about 500 psig (approximately 3447 kPa), about 100 psig (approximately 689 kPa) to about 450 psig (approximately 3103 kPa), or about 200 psig (approximately 1379 kPa) to about 400 psig (approximately 2758 kPa). For example, the mass control tank 286 may have an internal pressure of about 300 psig (approximately 2068 kPa). Generally, during steady operation of the heat engine systems 90, 200, the high pressure side of the working fluid circuit 202 contains the working fluid in a supercritical state and the low pressure side of the working fluid circuit 202 contains the working fluid in a subcritical state.

[044] In some examples, the heat engine systems 90, 200 further contain a variable frequency drive coupled to the system pump and configured to control mass flow rate or temperature of the working fluid within the high pressure side of the working fluid circuit 202. In other examples, the heat engine systems 90, 200 may also contain a generator or an alternator, such as the power generator 240, coupled to the expander or the power turbine 228 by the driveshaft 230 and configured to convert the mechanical energy into electrical energy. In one example, the system pump may be coupled to the expander or the power turbine 228 by the driveshaft 230 and configured to be driven by the mechanical energy for circulating the working fluid through the working fluid circuit 202. In another example, another pump portion may be coupled to the expander or the power turbine 228 by the driveshaft 230 to form a turbopump and the pump portion may be configured to be driven by the mechanical energy. In yet another example, an independent turbopump, such as the turbopump 260, may be coupled to the working fluid circuit 202. The turbopump 260 may contain the pump portion 262 coupled to an expansion device, such as the drive turbine 264, different than the system pump, the expander, the power turbine 228. In many examples, the expansion device and the expander are both turbines, such as the drive turbine 264 and the power turbine 228, respectively. Generally, the pump portion 262 of the turbopump 260 may be fluidly coupled to the working fluid circuit 202 between the low pressure side and the high pressure side of the working fluid circuit 202 and may be configured to circulate the working fluid through the working fluid circuit 202. Also, the expansion device or the drive turbine 264 of the turbopump 260 may be fluidly coupled to the working fluid circuit 202 between the low pressure side and the high pressure side of the working fluid circuit 202 and may be configured to drive the pump portion 262 by mechanical energy generated by the expansion of the working fluid.

[045] In other embodiments described herein, as shown in Figure 3, a method 300 for transforming with the heat engine systems 90, 200 is provided and includes circulating a working fluid within the working fluid circuit 202 by a system pump (block 312), wherein the working fluid circuit 202 has a high pressure side and a low pressure side and at least a portion of the working fluid may be in a supercritical state. In many examples and during various periods of the generation or power cycle, the high pressure side of the working fluid circuit 202 may contain the working fluid in a supercritical state while the low pressure side of the working fluid circuit 202 may contain the working fluid in a subcritical state and/or a supercritical state. The method 300 further includes transferring thermal energy from the heat source 1 10 to the working fluid by the heat exchanger 120 fluidly coupled to and in thermal communication with the heat source 1 10 and the high pressure side of the working fluid circuit 202 (block 314) and flowing the working fluid into an expander and converting the thermal energy from the working fluid to mechanical energy of the expander or the power turbine 228 (block 316). In some examples, the method 300 may include converting the mechanical energy into electrical energy by a power generator 240 coupled to the expander or the power turbine 228.

[046] The illustrated method 300 also includes transferring, passing, or otherwise flowing a portion of the working fluid from the low pressure side to the mass control tank 286 fluidly coupled to the low pressure side of the working fluid circuit 202 and configured to receive, store, and deliver the working fluid (block 318). The method 300 further includes flowing or transferring the working fluid from the mass control tank 286, through the charging pump 170, and to a point within the low pressure side of the working fluid circuit 202 upstream of the system pump, as well as flowing or transferring the working fluid from the mass control tank 286, through the charging pump 170, and to a bearing housing 238, 268 that completely, substantially, or partially encompasses or otherwise encloses bearings contained within a system component (block 320). In one embodiment of the method 300, the bearings disposed within the bearing housing 238, 268 are exposed to and cooled by the working fluid when the working fluid is flowed over the bearings (block 322). Therefore, the charging pump 170 may be fluidly coupled to and disposed downstream of the mass control tank 286, fluidly coupled to and upstream of the point within the low pressure side of the working fluid circuit 202, and fluidly coupled to and upstream of the bearing housing 238, 268.

[047] In some embodiments, the method includes adjusting at least one valve, such as an inventory return valve 174, to control the rate of the working fluid flowing from the low pressure side of the working fluid circuit 202, through an inventory return line 172, to the mass control tank 286. In other embodiments, the method includes adjusting at least one valve, such as the inventory supply valve 184, to control the rate of the working fluid flowing from the charging pump 170, through the inventory supply line 182, to the point within the low pressure side of the working fluid circuit 202. In other embodiments, the method includes adjusting at least one valve, such as bearing gas supply valves 198a, 198b, to control the rate of the working fluid flowing from the charging pump 170, through a bearing gas supply line 196, 196a, 196b, to the bearing housing 238, 268.

[048] In one or more embodiments described herein, the heat engine system 200 for transforming thermal energy into mechanical energy and/or electrical energy provides the working fluid circuit 202 containing the working fluid and having a high pressure side and a low pressure side, wherein at least a portion of the working fluid contains carbon dioxide in a supercritical state. In many examples, the working fluid contains carbon dioxide and at least a portion of the carbon dioxide is in a supercritical state. The heat engine system 200 also has the heat exchanger 120 fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit 202, configured to be fluidly coupled to and in thermal communication with the heat source stream 1 10, and configured to transfer thermal energy from the heat source stream 1 10 to the working fluid within the working fluid circuit 202. The heat exchanger 120 may be fluidly coupled to the working fluid circuit 202 upstream of the power turbine 228 and downstream of the recuperator 216. [049] The heat engine system 200 further contains an expander or a power turbine 228 disposed between the high pressure side and the low pressure side of the working fluid circuit 202, fluidly coupled to and in thermal communication with the working fluid, and configured to convert thermal energy to mechanical energy by a pressure drop in the working fluid flowing between the high and the low pressure sides of the working fluid circuit 202. The heat engine system 200 also contains a power generator 240 coupled to the power turbine 228 and configured to convert the mechanical energy into electrical energy, a power outlet 242 electrically coupled to the power generator 240 and configured to transfer the electrical energy from the power generator 240 to the electrical grid 244.

[050] The heat engine system 200 further contains a turbopump 260 which has a drive turbine 264 and a pump portion 262. The pump portion 262 of the turbopump 260 may be fluidly coupled to the low pressure side of the working fluid circuit 202 by an inlet configured to receive the working fluid from the low pressure side of the working fluid circuit 202, fluidly coupled to the high pressure side of the working fluid circuit 202 by an outlet configured to release the working fluid into the high pressure side of the working fluid circuit 202, and configured to circulate the working fluid within the working fluid circuit 202. The drive turbine 264 of the turbopump 260 may be fluidly coupled to the high pressure side of the working fluid circuit 202 by an inlet configured to receive the working fluid from the high pressure side of the working fluid circuit 202, fluidly coupled to the low pressure side of the working fluid circuit 202 by an outlet configured to release the working fluid into the low pressure side of the working fluid circuit 202, and configured to rotate the pump portion 262 of the turbopump 260.

[051] In some embodiments, the heat engine system 200 further contains the heat exchanger 150 which is generally fluidly coupled to and in thermal communication with the heat source stream 1 10 and independently fluidly coupled to and in thermal communication with the high pressure side of the working fluid circuit 202, such that thermal energy may be transferred from the heat source stream 1 10 to the working fluid. The heat exchanger 150 may be fluidly coupled to the working fluid circuit 202 upstream of the outlet of the pump portion 262 of the turbopump 260 and downstream of the inlet of the drive turbine 264 of the turbopump 260. The turbopump throttle valve 263 may be fluidly coupled to the working fluid circuit 202 downstream of the heat exchanger 150 and upstream of the inlet of the drive turbine 264 of the turbopump 260. The working fluid containing the absorbed thermal energy flows from the heat exchanger 150 to the drive turbine 264 of the turbopump 260 via the turbopump throttle valve 263. Therefore, in some embodiments, the turbopump throttle valve 263 may be utilized to control the flowrate of the heated working fluid flowing from the heat exchanger 150 to the drive turbine 264 of the turbopump 260.

[052] In some embodiments, the recuperator 216 may be fluidly coupled to the working fluid circuit 202 and configured to transfer thermal energy from the working fluid within the low pressure side to the working fluid within the high pressure side of the working fluid circuit 202. In other embodiments, a recuperator 218 may be fluidly coupled to the working fluid circuit 202 downstream of the outlet of the pump portion 262 of the turbopump 260 and upstream of the heat exchanger 150 and configured to transfer thermal energy from the working fluid within the low pressure side to the working fluid within the high pressure side of the working fluid circuit 202.

[053] Figure 2 further depicts that the waste heat system 100 of the heat engine system 200 contains three heat exchangers (e.g. , the heat exchangers 120, 130, and 150) fluidly coupled to the high pressure side of the working fluid circuit 202 and in thermal communication with the heat source stream 1 10. Such thermal communication provides the transfer of thermal energy from the heat source stream 1 10 to the working fluid flowing throughout the working fluid circuit 202. In one or more embodiments disclosed herein, two, three, or more heat exchangers may be fluidly coupled to and in thermal communication with the working fluid circuit 202, such as a primary heat exchanger, a secondary heat exchanger, a tertiary heat exchanger, respectively the heat exchangers 120, 150, and 130, and/or an optional quaternary heat exchanger (not shown). For example, the heat exchanger 120 may be the primary heat exchanger fluidly coupled to the working fluid circuit 202 upstream of an inlet of the power turbine 228, the heat exchanger 150 may be the secondary heat exchanger fluidly coupled to the working fluid circuit 202 upstream of an inlet of the drive turbine 264 of the turbine pump 260, and the heat exchanger 130 may be the tertiary heat exchanger fluidly coupled to the working fluid circuit 202 upstream of an inlet of the heat exchanger 120.

[054] The waste heat system 100 also contains an inlet 104 for receiving the heat source stream 1 10 and an outlet 106 for passing the heat source stream 1 10 out of the waste heat system 100. The heat source stream 1 10 flows through and from the inlet 104, through the heat exchanger 120, through one or more additional heat exchangers, if fluidly coupled to the heat source stream 1 10, and to and through the outlet 106. In some examples, the heat source stream 1 10 flows through and from the inlet 104, through the heat exchangers 120, 150, and 130, respectively, and to and through the outlet 106. The heat source stream 1 10 may be routed to flow through the heat exchangers 120, 130, 150, and/or additional heat exchangers in other desired orders.

[055] The heat source stream 1 10 may be a waste heat stream such as, but not limited to, gas turbine exhaust stream, industrial process exhaust stream, or other combustion product exhaust streams, such as furnace or boiler exhaust streams. The heat source stream 1 10 may be at a temperature within a range from about 100°C to about 1 ,000°C, or greater than 1 ,000°C, and in some examples, within a range from about 200°C to about 800°C, more narrowly within a range from about 300°C to about 600°C. The heat source stream 1 10 may contain air, carbon dioxide, carbon monoxide, water or steam, nitrogen, oxygen, argon, derivatives thereof, or mixtures thereof. In some embodiments, the heat source stream 1 10 may derive thermal energy from renewable sources of thermal energy, such as solar or geothermal sources.

[056] In some embodiments, the types of working fluid that may be circulated, flowed, or otherwise utilized in the working fluid circuit 202 of the heat engine system 200 include carbon oxides, hydrocarbons, alcohols, ketones, halogenated hydrocarbons, ammonia, amines, aqueous, or combinations thereof. Exemplary working fluids that may be utilized in the heat engine system 200 include carbon dioxide, ammonia, methane, ethane, propane, butane, ethylene, propylene, butylene, acetylene, methanol, ethanol, acetone, methyl ethyl ketone, water, derivatives thereof, or mixtures thereof. Halogenated hydrocarbons may include hydrochlorofluorocarbons (HCFCs), hydrofluorocarbons (H FCs) (e.g. , 1 ,1 , 1 ,3,3- pentafluoropropane (R245fa)) , fluorocarbons, derivatives thereof, or mixtures thereof.

[057] In many embodiments described herein, the working fluid the working fluid circulated, flowed, or otherwise utilized in the working fluid circuit 202 of the heat engine system 200, and the other exemplary circuits disclosed herein, may be or may contain carbon dioxide (CO2) and mixtures containing carbon dioxide. Generally, at least a portion of the working fluid circuit 202 contains the working fluid in a supercritical state (e.g., SC-CO2). Carbon dioxide utilized as the working fluid or contained in the working fluid for power generation cycles has many advantages over other compounds typically used as working fluids, since carbon dioxide has the properties of being non-toxic and non-flammable and is also easily available and relatively inexpensive . Due in part to a relatively high working pressure of carbon dioxide, a carbon dioxide system may be much more compact than systems using other working fluids. The high density and volumetric heat capacity of carbon dioxide with respect to other working fluids makes carbon dioxide more "energy dense" meaning that the size of all system components can be considerably reduced without losing performance. It should be noted that use of the terms carbon dioxide (CO2), supercritical carbon dioxide (SC-CO2), or subcritical carbon dioxide (sub- C0 2 ) is not intended to be limited to carbon dioxide of any particular type, source, purity, or grade. For example, industrial grade carbon dioxide may be contained in and/or used as the working fluid without departing from the scope of the disclosure.

[058] In other exemplary embodiments, the working fluid in the working fluid circuit 202 may be a binary, ternary, or other working fluid blend. The working fluid blend or combination can be selected for the unique attributes possessed by the fluid combination within a heat recovery system, as described herein. For example, one such fluid combination includes a liquid absorbent and carbon dioxide mixture enabling the combined fluid to be pumped in a liquid state to high pressure with less energy input than required to compress carbon dioxide. In another exemplary embodiment, the working fluid may be a combination of carbon dioxide (e.g., sub- CO2 or SC-CO2) and one or more other miscible fluids or chemical compounds. In yet other exemplary embodiments, the working fluid may be a combination of carbon dioxide and propane, or carbon dioxide and ammonia, without departing from the scope of the disclosure.

[059] The working fluid circuit 202 generally has a high pressure side and a low pressure side and contains a working fluid circulated within the working fluid circuit 202. The use of the term "working fluid" is not intended to limit the state or phase of matter of the working fluid. For instance, the working fluid or portions of the working fluid may be in a liquid phase, a gas phase, a fluid phase, a subcritical state, a supercritical state, or any other phase or state at any one or more points within the working fluid circuit 202, the heat engine system 200, or thermodynamic cycle. In one or more embodiments, the working fluid is in a supercritical state over certain portions of the working fluid circuit 202 of the heat engine system 200 (e.g. , a high pressure side) and in a subcritical state over other portions of the working fluid circuit 202 of the heat engine system 200 (e.g. , a low pressure side) . Figure 2 depicts the high and low pressure sides of the working fluid circuit 202 of the heat engine system 200 by representing the high pressure side with " " and the low pressure side with " " - as described in one or more embodiments. In other embodiments, the entire thermodynamic cycle may be operated such that the working fluid is maintained in either a supercritical or subcritical state throughout the entire working fluid circuit 202 of the heat engine system 200.

[060] Generally, the high pressure side of the working fluid circuit 202 contains the working fluid (e.g. , sc-C0 2 ) at a pressure of about 15 MPa or greater, such as about 17 MPa or greater or about 20 MPa or greater. In some examples, the high pressure side of the working fluid circuit 202 may have a pressure within a range from about 15 MPa to about 30 MPa, more narrowly within a range from about 16 MPa to about 26 MPa , more narrowly within a range from about 17 MPa to about 25 MPa, and more narrowly within a range from about 17 MPa to about 24 MPa, such as about 23.3 MPa. In other examples, the high pressure side of the working fluid circuit 202 may have a pressure within a range from about 20 MPa to about 30 MPa, more narrowly within a range from about 21 MPa to about 25 MPa, and more narrowly within a range from about 22 MPa to about 24 MPa, such as about 23 MPa.

[061] The low pressure side of the working fluid circuit 202 contains the working fluid (e.g., CO2 or sub-CC>2) at a pressure of less than 15 MPa, such as about 12 M Pa or less or about 10 MPa or less. In some examples, the low pressure side of the working fluid circuit 202 may have a pressure within a range from about 4 MPa to about 14 MPa, more narrowly within a range from about 6 MPa to about 13 MPa, more narrowly within a range from about 8 MPa to about 12 MPa, and more narrowly within a range from about 10 MPa to about 1 1 MPa, such as about 10.3 MPa. In other examples, the low pressure side of the working fluid circuit 202 may have a pressure within a range from about 2 MPa to about 10 MPa, more narrowly within a range from about 4 MPa to about 8 MPa, and more narrowly within a range from about 5 MPa to about 7 MPa, such as about 6 M Pa.

[062] In some examples, the high pressure side of the working fluid circuit 202 may have a pressure within a range from about 17 MPa to about 23.5 MPa, and more narrowly within a range from about 23 MPa to about 23.3 MPa while the low pressure side of the working fluid circuit 202 may have a pressure within a range from about 8 MPa to about 1 1 MPa, and more narrowly within a range from about 1 0.3 MPa to about 1 1 MPa .

[063] The heat engine system 200 further contains the power turbine 228 disposed between the high pressure side and the low pressure side of the working fluid circuit 202, disposed downstream of the heat exchanger 120, and fluidly coupled to and in thermal communication with the working fluid . The power turbine 228 is configured to convert a pressure drop in the working fluid to mechanical energy whereby the absorbed thermal energy of the working fluid is transformed to mechanical energy of the power turbine 228. Therefore, the power turbine 228 is an expansion device or an expander capable of transforming a pressurized fluid into mechanical energy, generally, transforming high temperature and pressure fluid into mechanical energy, such as rotating a driveshaft.

[064] The power turbine 228 may contain or be a turbine, a turbo, an expander, or another device for receiving and expanding the working fluid discharged from the heat exchanger 1 20. The power turbine 228 may have an axial construction or radial construction and may be a single-staged device or a multi-staged device. Exemplary turbines that may be utilized in power turbine 228 include an expansion device, a geroler, a gerotor, a valve, other types of positive displacement devices such as a pressure swing, a turbine, a turbo, or any other device capable of transforming a pressure or pressure/enthalpy drop in a working fluid into mechanical energy. A variety of expanding devices are capable of working within the inventive system and achieving different performance properties that may be utilized as the power turbine 228.

[065] The power turbine 228 is generally coupled to the power generator 240 by the driveshaft 230. A gearbox 232 is generally disposed between the power turbine 228 and the power generator 240 and adjacent or encompassing the driveshaft 230. The driveshaft 230 may be a single piece or contain two or more pieces coupled together. In one example, a first segment of the driveshaft 230 extends from the power turbine 228 to the gearbox 232, a second segment of the driveshaft 230 extends from the gearbox 232 to the power generator 240, and multiple gears are disposed between and coupled to the two segments of the driveshaft 230 within the gearbox 232.

[066] In some configurations, the heat engine system 200 also provides for the delivery of a portion of the working fluid , seal gas, bearing gas, air, or other gas into a chamber or housing , such as bearing housing 238 of the power generator 240 for purposes of cooling one or more parts of the power turbine 228. In other configurations, the driveshaft 230 includes a seal assembly (not shown) designed to prevent or capture any working fluid leakage from the power turbine 228. Additionally, a working fluid recycle system may be implemented along with the seal assembly to recycle seal gas back into the working fluid circuit 202 of the heat engine system 200.

[067] The power generator 240 may be a generator, an alternator (e.g., permanent magnet alternator), or other device for generating electrical energy, such as transforming mechanical energy from the driveshaft 230 and the power turbine 228 to electrical energy. A power outlet 242 is electrically coupled to the power generator 240 and configured to transfer the generated electrical energy from the power generator 240 and to an electrical grid 244. The electrical grid 244 may be or include an electrical grid, an electrical bus (e.g. , plant bus) , power electronics, other electric circuits, or combinations thereof. The electrical grid 244 generally contains at least one alternating current bus, alternating current grid, alternating current circuit, or combinations thereof. In one example, the power generator 240 is a generator and is electrically and operably connected to the electrical grid 244 via the power outlet 242. In another example, the power generator 240 is an alternator and is electrically and operably connected to power electronics (not shown) via the power outlet 242. In another example, the power generator 240 is electrically connected to power electronics which are electrically connected to the power outlet 242.

[068] The power electronics may be configured to convert the electrical power into desirable forms of electricity by modifying electrical properties, such as voltage, current, or frequency. The power electronics may include converters or rectifiers, inverters, transformers, regulators, controllers, switches, resisters, storage devices, and other power electronic components and devices. In other embodiments, the power generator 240 may contain, be coupled with, or be other types of load receiving equipment, such as other types of electrical generation equipment, rotating equipment, a gearbox (e.g., gearbox 232), or other device configured to modify or convert the shaft work created by the power turbine 228. In one embodiment, the power generator 240 is in fluid communication with a cooling loop having a radiator and a pump for circulating a cooling fluid, such as water, thermal oils, and/or other suitable refrigerants. The cooling loop may be configured to regulate the temperature of the power generator 240 and power electronics by circulating the cooling fluid to draw away generated heat.

[069] The heat engine system 200 also provides for the delivery of a portion of the working fluid into a chamber or housing of the power turbine 228 for purposes of cooling one or more parts of the power turbine 228. In one embodiment, due to the potential need for dynamic pressure balancing within the power generator 240, the selection of the site within the heat engine system 200 from which to obtain a portion of the working fluid is critical because introduction of this portion of the working fluid into the power generator 240 should respect or not disturb the pressure balance and stability of the power generator 240 during operation. Therefore, the pressure of the working fluid delivered into the power generator 240 for purposes of cooling is the same or substantially the same as the pressure of the working fluid at an inlet of the power turbine 228. The working fluid is conditioned to be at a desired temperature and pressure prior to being introduced into the power turbine 228. A portion of the working fluid, such as the spent working fluid, exits the power turbine 228 at an outlet of the power turbine 228 and is directed to one or more heat exchangers or recuperators, such as recuperators 216 and 218. The recuperators 216 and 218 may be fluidly coupled to the working fluid circuit 202 in series with each other. The recuperators 216 and 218 are operative to transfer thermal energy between the high pressure side and the low pressure side of the working fluid circuit 202.

[070] In one embodiment, the recuperator 216 may be fluidly coupled to the low pressure side of the working fluid circuit 202, disposed downstream of a working fluid outlet on the power turbine 228, and disposed upstream of the recuperator 218 and/or the condenser 274. The recuperator 216 is configured to remove at least a portion of thermal energy from the working fluid discharged from the power turbine 228. In addition, the recuperator 216 is also fluidly coupled to the high pressure side of the working fluid circuit 202, disposed upstream of the heat exchanger 120 and/or a working fluid inlet on the power turbine 228, and disposed downstream of the heat exchanger 130. The recuperator 216 is configured to increase the amount of thermal energy in the working fluid prior to the working fluid is flowed into the heat exchanger 120 and/or the power turbine 228. Therefore, the recuperator 216 is operative to transfer thermal energy between the high pressure side and the low pressure side of the working fluid circuit 202. Generally, the recuperator 216 may be configured to transfer thermal energy from the low pressure side to the high pressure side of the working fluid circuit 202. In some examples, the recuperator 216 may be a heat exchanger configured to cool the low pressurized working fluid discharged or downstream of the power turbine 228 while heating the high pressurized working fluid entering into or upstream of the heat exchanger 120 and/or the power turbine 228.

[071] Similarly, in another embodiment, the recuperator 218 may be fluidly coupled to the low pressure side of the working fluid circuit 202, disposed downstream of a working fluid outlet on the power turbine 228 and/or the recuperator 216, and disposed upstream of the condenser 274. The recuperator 218 is configured to remove at least a portion of thermal energy from the working fluid discharged from the power turbine 228 and/or the recuperator 216. In addition, the recuperator 218 is also fluidly coupled to the high pressure side of the working fluid circuit 202, disposed upstream of the heat exchanger 150 and/or a working fluid inlet on a drive turbine 264 of turbopump 260, and disposed downstream of a working fluid outlet on a pump portion 262 of turbopump 260. The recuperator 218 is configured to increase the amount of thermal energy in the working fluid prior to the working fluid is flowed into the heat exchanger 150 and/or the drive turbine 264. Therefore, the recuperator 218 is operative to transfer thermal energy between the high pressure side and the low pressure side of the working fluid circuit 202. Generally, the recuperator 218 may be configured to transfer thermal energy from the low pressure side to the high pressure side of the working fluid circuit 202. In some examples, the recuperator 218 may be a heat exchanger configured to cool the low pressurized working fluid discharged or downstream of the power turbine 228 and/or the recuperator 216 while heating the high pressurized working fluid entering into or upstream of the heat exchanger 150 and/or the drive turbine 264. [072] A cooler or a condenser 274 may be fluidly coupled to and in thermal communication with the low pressure side of the working fluid circuit 202 and may be configured or operative to control a temperature of the working fluid in the low pressure side of the working fluid circuit 202. The condenser 274 may be disposed downstream of the recuperators 216 and 218 and upstream of the start pump 280 and the turbopump 260. The condenser 274 receives the cooled working fluid from the recuperator 218 and further cools and/or condenses the working fluid which may be recirculated throughout the working fluid circuit 202. In many examples, the condenser 274 is a cooler and may be configured to control a temperature of the working fluid in the low pressure side of the working fluid circuit 202 by transferring thermal energy from the working fluid in the low pressure side to a cooling loop or system outside of the working fluid circuit 202.

[073] A cooling media or fluid is generally utilized in the cooling loop or system by the condenser 274 for cooling the working fluid and removing thermal energy outside of the working fluid circuit 202. The cooling media or fluid flows through, over, or around while in thermal communication with the condenser 274. Thermal energy in the working fluid is transferred to the cooling fluid via the condenser 274. Therefore, the cooling fluid is in thermal communication with the working fluid circuit 202, but not fluidly coupled to the working fluid circuit 202. The condenser 274 may be fluidly coupled to the working fluid circuit 202 and independently fluidly coupled to the cooling fluid. The cooling fluid may contain one or multiple compounds and may be in one or multiple states of matter. The cooling fluid may be a media or fluid in a gaseous state, a liquid state, a subcritical state, a supercritical state, a suspension, a solution, derivatives thereof, or combinations thereof.

[074] In many examples, the condenser 274 is generally fluidly coupled to a cooling loop or system (not shown) that receives the cooling fluid from a cooling fluid return 278a and returns the warmed cooling fluid to the cooling loop or system via a cooling fluid supply 278b. The cooling fluid may be water, carbon dioxide, or other aqueous and/or organic fluids (e.g., alcohols and/or glycols), air or other gases, or various mixtures thereof that is maintained at a lower temperature than the temperature of the working fluid . In other examples, the cooling media or fluid contains air or another gas exposed to the condenser 274, such as an air steam blown by a motorized fan or blower. A filter 276 may be disposed along and in fluid communication with the cooling fluid line at a point downstream of the cooling fluid supply 278b and upstream of the condenser 274. In some examples, the filter 276 may be fluidly coupled to the cooling fluid line within the process system 210. [075] The heat engine system 200 further contains several pumps, such as a turbopump 260 and a start pump 280, disposed within the working fluid circuit 202 and fluidly coupled between the low pressure side and the high pressure side of the working fluid circuit 202. The turbopump 260 and the start pump 280 are operative to circulate the working fluid throughout the working fluid circuit 202. The start pump 280 is generally a motorized pump and may be utilized to initially pressurize and circulate the working fluid in the working fluid circuit 202. Once a predetermined pressure, temperature, and/or flowrate of the working fluid is obtained within the working fluid circuit 202, the start pump 280 may be taken off line, idled, or turned off and the turbopump 260 is utilize to circulate the working fluid during the electricity generation process. The working fluid enters each of the turbopump 260 and the start pump 280 from the low pressure side of the working fluid circuit 202 and exits each of the turbopump 260 and the start pump 280 from the high pressure side of the working fluid circuit 202.

[076] The start pump 280 may be a motorized pump, such as an electric-motorized pump, a mechanical-motorized pump, or other type of pump. Generally, the start pump 280 may be a variable frequency motorized drive pump and contains a pump portion 282 and a motor-drive portion 284. The motor-drive portion 284 of the start pump 280 contains a motor and a drive including a driveshaft and gears. In some examples, the motor-drive portion 284 has a variable frequency drive, such that the speed of the motor may be regulated by the drive. The pump portion 282 of the start pump 280 is driven by the motor-drive portion 284 coupled thereto. The pump portion 282 has an inlet for receiving the working fluid from the low pressure side of the working fluid circuit 202, such as from the condenser 274. The pump portion 282 has an outlet for releasing the working fluid into the high pressure side of the working fluid circuit 202.

[077] Valves 283 and 285 may be utilized to control the flow of the working fluid passing through the start pump 280. Valve 285 may be fluidly coupled to the low pressure side of the working fluid circuit 202 upstream of the pump portion 282 of the start pump 280 and may be utilized to control the flowrate of the working fluid entering the inlet of the pump portion 282. Valve 283 may be fluidly coupled to the high pressure side of the working fluid circuit 202 downstream of the pump portion 282 of the start pump 280 and may be utilized to control the flowrate of the working fluid exiting the outlet of the pump portion 282.

[078] The turbopump 260 is generally a turbo-drive pump or a turbine-drive pump and utilized to pressurize and circulate the working fluid throughout the working fluid circuit 202. The turbopump 260 contains a pump portion 262 and a drive turbine 264 coupled together by a driveshaft 267 and an optional gearbox (not shown). The drive turbine 264 is configured to rotate the pump portion 262 and the pump portion 262 is configured to circulate the working fluid within the working fluid circuit 202.

[079] The driveshaft 267 may be a single piece or contain two or more pieces coupled together. In one example, a first segment of the driveshaft 267 extends from the drive turbine 264 to the gearbox, a second segment of the driveshaft 230 extends from the gearbox to the pump portion 262, and multiple gears are disposed between and coupled to the two segments of the driveshaft 267 within the gearbox.

[080] The drive turbine 264 of the turbopump 260 is driven by heated working fluid, such as the working fluid flowing from the heat exchanger 150. The drive turbine 264 may be fluidly coupled to the high pressure side of the working fluid circuit 202 by an inlet configured to receive the working fluid from the high pressure side of the working fluid circuit 202, such as flowing from the heat exchanger 150. The drive turbine 264 may be fluidly coupled to the low pressure side of the working fluid circuit 202 by an outlet configured to release the working fluid into the low pressure side of the working fluid circuit 202.

[081] The pump portion 262 of the turbopump 260 is driven by the driveshaft 267 coupled to the drive turbine 264. The pump portion 262 of the turbopump 260 may be fluidly coupled to the low pressure side of the working fluid circuit 202 by an inlet configured to receive the working fluid from the low pressure side of the working fluid circuit 202. The inlet of the pump portion 262 is configured to receive the working fluid from the low pressure side of the working fluid circuit 202, such as from the condenser 274. Also, the pump portion 262 may be fluidly coupled to the high pressure side of the working fluid circuit 202 by an outlet configured to release the working fluid into the high pressure side of the working fluid circuit 202 and circulate the working fluid within the working fluid circuit 202.

[082] In one configuration, the working fluid released from the outlet on the drive turbine 264 is returned into the working fluid circuit 202 downstream of the recuperator 216 and upstream of the recuperator 218. In one or more embodiments, the turbopump 260, including piping and valves, is optionally disposed on a turbopump skid 266, as depicted in Figure 2. The turbopump skid 266 may be disposed on or adjacent to the main process skid 212.

[083] A bypass valve 265 is generally coupled between and in fluid communication with a fluid line extending from the inlet on the drive turbine 264 with a fluid line extending from the outlet on the drive turbine 264. The bypass valve 265 is generally opened to bypass the turbopump 260 while using the start pump 280 during the initial stages of generating electricity or mechanical power with the heat engine system 200. Once a predetermined pressure and temperature of the working fluid is obtained within the working fluid circuit 202, the bypass valve 265 is closed and the heated working fluid is flowed through the drive turbine 264 to start the turbopump 260.

[084] A turbopump throttle valve 263 may be coupled between and in fluid communication with a fluid line extending from the heat exchanger 150 to the inlet on the drive turbine 264 of the turbopump 260. The turbopump throttle valve 263 is configured to modulate the flow of the heated working fluid into the drive turbine 264 which in turn - may be utilized to adjust the flow of the working fluid throughout the working fluid circuit 202. Additionally, valve 293 may be utilize to provide back pressure for the drive turbine 264 of the turbopump 260 and valve 295 is generally an attemperator valve utilized by the turbopump 260.

[085] A control valve 261 may be disposed downstream of the outlet of the pump portion 262 of the turbopump 260 and the control valve 281 may be disposed downstream of the outlet of the pump portion 282 of the start pump 280. Control valves 261 and 281 are flow control safety valves and are generally utilized to regulate the directional flow or to prohibit backflow of the working fluid within the working fluid circuit 202. Control valve 261 may be configured to prevent the working fluid from flowing upstream towards or into the outlet of the pump portion 262 of the turbopump 260. Similarly, control valve 281 may be configured to prevent the working fluid from flowing upstream towards or into the outlet of the pump portion 282 of the start pump 280.

[086] The turbopump throttle valve 263 may be fluidly coupled to the working fluid circuit 202 upstream of the inlet of the drive turbine 264 of the turbopump 260 and configured to control a flow of the working fluid flowing into the drive turbine 264. The power turbine bypass valve 219 may be fluidly coupled to the power turbine bypass line 208 and configured to modulate, adjust, or otherwise control the working fluid flowing through the power turbine bypass line 208 for controlling the flowrate of the working fluid entering the power turbine 228.

[087] The power turbine bypass line 208 may be fluidly coupled to the working fluid circuit 202 at a point upstream of an inlet of the power turbine 228 and at a point downstream of an outlet of the power turbine 228. The power turbine bypass line 208 is configured to flow the working fluid around and avoid the power turbine 228 when the power turbine bypass valve 219 is in an opened position. The flowrate and the pressure of the working fluid flowing into the power turbine 228 may be reduced or stopped by adjusting the power turbine bypass valve 219 to the opened position. Alternatively, the flowrate and the pressure of the working fluid flowing into the power turbine 228 may be increased or started by adjusting the power turbine bypass valve 219 to the closed position due to the backpressure formed through the power turbine bypass line 208.

[088] The power turbine bypass valve 219 and the turbopump throttle valve 263 may be independently controlled by the process control system 204 that is communicably connected, wired and/or wirelessly, with the power turbine bypass valve 219, the turbopump throttle valve 263, and other parts of the heat engine system 200. The process control system 204 is operatively connected to the working fluid circuit 202 and a mass management system 270 and is enabled to monitor and control multiple process operation parameters of the heat engine system 200.

[089] In one or more embodiments, the working fluid circuit 202 provides a bypass flowpath for the start pump 280 via the fluid line 224 and a bypass valve 254, as well as a bypass flowpath for the turbopump 260 via the fluid line 226 and a bypass valve 256. One end of the fluid line 224 may be fluidly coupled to an outlet of the pump portion 282 of the start pump 280 and the other end of the fluid line 224 may be fluidly coupled to a fluid line 229. Similarly, one end of a fluid line 226 may be fluidly coupled to an outlet of the pump portion 262 of the turbopump 260 and the other end of the fluid line 226 is coupled to the fluid line 224. The fluid lines 224 and 226 merge together as a single line upstream of coupling to a fluid line 229. The fluid line 229 extends between and fluidly coupled to the recuperator 218 and the condenser 274. The bypass valve 254 may be disposed along the fluid line 224 and fluidly coupled between the low pressure side and the high pressure side of the working fluid circuit 202 when in a closed position. Similarly, the bypass valve 256 may be disposed along the fluid line 226 and fluidly coupled between the low pressure side and the high pressure side of the working fluid circuit 202 when in a closed position.

[090] Figure 2 further depicts a power turbine throttle valve 250 fluidly coupled to a bypass line 246 on the high pressure side of the working fluid circuit 202 and upstream of the heat exchanger 120, as disclosed by at least one embodiment described herein. The power turbine throttle valve 250 may be fluidly coupled to the bypass line 246 and configured to modulate, adjust, or otherwise control the working fluid flowing through the bypass line 246 for controlling a general coarse flowrate of the working fluid within the working fluid circuit 202. The bypass line 246 may be fluidly coupled to the working fluid circuit 202 at a point upstream of the valve 293 and at a point downstream of the pump portion 282 of the start pump 280 and/or the pump portion 262 of the turbopump 260. Additionally, a power turbine trim valve 252 may be fluidly coupled to a bypass line 248 on the high pressure side of the working fluid circuit 202 and upstream of the heat exchanger 150, as disclosed by another embodiment described herein. The power turbine trim valve 252 may be fluidly coupled to the bypass line 248 and configured to modulate, adjust, or otherwise control the working fluid flowing through the bypass line 248 for controlling a fine flowrate of the working fluid within the working fluid circuit 202. The bypass line 248 may be fluidly coupled to the bypass line 246 at a point upstream of the power turbine throttle valve 250 and at a point downstream of the power turbine throttle valve 250.

[091] The heat engine system 200 further contains a turbopump throttle valve 263 fluidly coupled to the working fluid circuit 202 upstream of the inlet of the drive turbine 264 of the turbopump 260 and configured to modulate a flow of the working fluid flowing into the drive turbine 264, a power turbine bypass line 208 fluidly coupled to the working fluid circuit 202 upstream of an inlet of the power turbine 228, fluidly coupled to the working fluid circuit 202 downstream of an outlet of the power turbine 228, and configured to flow the working fluid around and avoid the power turbine 228, a power turbine bypass valve 219 fluidly coupled to the power turbine bypass line 208 and configured to modulate a flow of the working fluid flowing through the power turbine bypass line 208 for controlling the flowrate of the working fluid entering the power turbine 228, and a process control system 204 operatively connected to the heat engine system 90, wherein the process control system 204 is configured to adjust the turbopump throttle valve 263 and the power turbine bypass valve 219.

[092] A bypass line 160 may be fluidly coupled to a fluid line 131 of the working fluid circuit 202 upstream of the heat exchangers 120, 130, and/or 150 by a bypass valve 162, as illustrated in Figure 2. The bypass valve 162 may be a solenoid valve, a hydraulic valve, an electric valve, a manual valve, or derivatives thereof. In many examples, the bypass valve 162 is a solenoid valve and configured to be controlled by the process control system 204.

[093] In one or more embodiments, the working fluid circuit 202 provides release valves 213a, 213b, 213c, and 213d, as well as release outlets 214a, 214b, 214c, and 214d, respectively in fluid communication with each other. Generally, the release valves 213a, 213b, 213c, and 213d remain closed during the electricity generation process, but may be configured to automatically open to release an over-pressure at a predetermined value within the working fluid. Once the working fluid flows through the valve 213a, 213b, 213c, or 213d, the working fluid is vented through the respective release outlet 214a, 214b, 214c, or 214d. The release outlets 214a, 214b, 214c, and 214d may provide passage of the working fluid into the ambient surrounding atmosphere. Alternatively, the release outlets 214a, 214b, 214c, and 214d may provide passage of the working fluid into a recycling or reclamation step that generally includes capturing, condensing, and storing the working fluid.

[094] The release valve 213a and the release outlet 214a are fluidly coupled to the working fluid circuit 202 at a point disposed between the heat exchanger 120 and the power turbine 228. The release valve 213b and the release outlet 214b are fluidly coupled to the working fluid circuit 202 at a point disposed between the heat exchanger 150 and the turbo portion 264 of the turbopump 260. The release valve 213c and the release outlet 214c are fluidly coupled to the working fluid circuit 202 via a bypass line that extends from a point between the valve 293 and the pump portion 262 of the turbopump 260 to a point on the fluid line 226 between the bypass valve 256 and the fluid line 229. The release valve 213d and the release outlet 214d are fluidly coupled to the working fluid circuit 202 at a point disposed between the recuperator 218 and the condenser 274.

[095] A computer system 206, as part of the process control system 204, may contain a multi- controller algorithm utilized to control the multiple valves, pumps, and sensors within the heat engine system 200. In one embodiment, the process control system 204 is enabled to move, adjust, manipulate, or otherwise control the inventory return valve 174 and/or the inventory supply valve 184 along with operating the charging pump 170 for mass management or inventory control of the working fluid within the working fluid circuit 202. In another embodiment, the process control system 204 is enabled to move, adjust, manipulate, or otherwise control the bearing gas supply valves 198a and 198b along with operating the charging pump 170 to flow the working fluid over and cool the bearings within the bearing housings 268 and 238. By controlling the flow of the working fluid, the process control system 204 is also operable to regulate the mass flows, temperatures, and/or pressures throughout the working fluid circuit 202.

[096] In some embodiments, the overall efficiency of the heat engine system 200 and the amount of power ultimately generated can be influenced by the use of a mass management system ("MMS") 270. The mass management system 270 may be utilized to control the charging pump 170 by regulating the amount of working fluid entering and/or exiting the heat engine system 200 at strategic locations in the working fluid circuit 202, such as the inventory return line 172, the inventory supply line 182, as well as at tie-in points, inlets/outlets, valves, or conduits throughout the heat engine system 200.

[097] In one embodiment, the mass management system 270 contains at least one storage vessel or tank, such as a mass control tank 286, configured to contain or otherwise store the working fluid therein. The mass control tank 286 may be fluidly coupled to the low pressure side of the working fluid circuit 202, may be configured to receive the working fluid from the working fluid circuit 202, and/or may be configured to distribute the working fluid into the working fluid circuit 202. The mass control tank 286 may be a storage tank/vessel, a cryogenic tank/vessel, a cryogenic storage tank/vessel, a fill tank/vessel, or other type of tank, vessel, or container fluidly coupled to the working fluid circuit 202.

[098] The mass control tank 286 may be fluidly coupled to the low pressure side of the working fluid circuit 202 via one or more fluid lines (e.g. , the inventory return/supply lines 172, 182) and valves (e.g. , the inventory return/supply valves 174, 184). The valves are moveable - as being partially opened, fully opened, and/or closed - to either remove working fluid from the working fluid circuit 202 or add working fluid to the working fluid circuit 202. Exemplary embodiments of the mass management system 270, and a range of variations thereof, are found in U .S. Appl. No. 13/278,705, filed October 21 , 201 1 , published as U .S. Pub. No. 2012- 0047892, and issued as 8,613, 195, the contents of which are incorporated herein by reference to the extent consistent with the present disclosure.

[099] In some embodiments, the mass control tank 286 may be configured as a localized storage tank for additional/supplemental working fluid that may be added to the heat engine system 90, 200 when desired in order to regulate the pressure or temperature of the working fluid within the working fluid circuit 202 or otherwise supplement escaped working fluid. By controlling the valves, the mass management system 270 adds and/or removes working fluid mass to/from the heat engine system 200 with or without the need of a pump, thereby reducing system cost, complexity, and maintenance.

[0100] Additional or supplemental working fluid may be added to the mass control tank 286, hence, added to the mass management system 270 and the working fluid circuit 202, from an external source, such as by a fluid fill system via at least one connection point or fluid fill port, such as a working fluid feed 288. Exemplary fluid fill systems are described and illustrated in U .S. Pat. No. 8,281 ,593, the contents of which are incorporated herein by reference to the extent consistent with the present disclosure. In some embodiments, an additional working fluid storage vessel (not shown) may be fluidly coupled to the mass control tank 286 and utilized to contain further supplemental working fluid. In some examples, the additional working fluid storage vessel may be fluidly coupled to the mass control tank 286 via the working fluid feed 288. [0101] In another embodiment described herein, seal gas may be supplied to components or devices contained within and/or utilized along with the heat engine system 200. One or multiple streams of seal gas may be derived from the working fluid within the working fluid circuit 202 and contain carbon dioxide in a gaseous, subcritical, or supercritical state. In some examples, the seal gas supply 298 is a connection point or valve that feeds into a seal gas system. A gas return 294 is generally coupled to a discharge, recapture, or return of seal gas and other gases. The gas return 294 provides a feed stream into the working fluid circuit 202 of recycled, recaptured, or otherwise returned gases - generally derived from the working fluid. The gas return may be fluidly coupled to the working fluid circuit 202 upstream of the condenser 274 and downstream of the recuperator 218.

[0102] The heat engine system 200 contains a process control system 204 communicably connected, wired and/or wirelessly, with numerous sets of sensors, valves, and pumps, in order to process the measured and reported temperatures, pressures, and mass flowrates of the working fluid at the designated points within the working fluid circuit 202. In response to these measured and/or reported parameters, the process control system 204 may be operable to selectively adjust the valves in accordance with a control program or algorithm, thereby maximizing operation of the heat engine system 200.

[0103] The process control system 204 may operate with the heat engine system 200 semi- passively with the aid of several sets of sensors. The first set of sensors is arranged at or adjacent the suction inlet of the turbopump 260 and the start pump 280 and the second set of sensors is arranged at or adjacent the outlet of the turbopump 260 and the start pump 280. The first and second sets of sensors monitor and report the pressure, temperature, mass flowrate, or other properties of the working fluid within the low and high pressure sides of the working fluid circuit 202 adjacent the turbopump 260 and the start pump 280. The third set of sensors may be arranged either inside or adjacent the mass control tank 286 of the mass management system 270 to measure and report the pressure, temperature, mass flowrate, or other properties of the working fluid within the mass control tank 286. Additionally, an instrument air supply (not shown) may be coupled to sensors, devices, or other instruments within the heat engine system 200 and/or the mass management system 270 that may utilized a gaseous source, such as nitrogen or air.

[0104] In some embodiments described herein, the waste heat system 100 is disposed on or in a waste heat skid 102 fluidly coupled to the working fluid circuit 202, as well as other portions, sub-systems, or devices of the heat engine system 200. The waste heat skid 102 may be fluidly coupled to a source of and an exhaust for the heat source stream 1 10, a main process skid 212, a power generation skid 222, and/or other portions, sub-systems, or devices of the heat engine system 200.

[0105] In one or more configurations, the waste heat system 100 disposed on or in the waste heat skid 102 generally contains inlets 122, 132, and 152 and outlets 124, 134, and 154 fluidly coupled to and in thermal communication with the working fluid within the working fluid circuit 202. The inlet 122 may be disposed upstream of the heat exchanger 120 and the outlet 124 is disposed downstream of the heat exchanger 120. The working fluid circuit 202 is configured to flow the working fluid from the inlet 122, through the heat exchanger 120, and to the outlet 124 while transferring thermal energy from the heat source stream 1 10 to the working fluid by the heat exchanger 120. The inlet 152 is disposed upstream of the heat exchanger 150 and the outlet 154 is disposed downstream of the heat exchanger 150. The working fluid circuit 202 is configured to flow the working fluid from the inlet 152, through the heat exchanger 150, and to the outlet 154 while transferring thermal energy from the heat source stream 1 10 to the working fluid by the heat exchanger 150. The inlet 132 is disposed upstream of the heat exchanger 130 and the outlet 134 is disposed downstream of the heat exchanger 130. The working fluid circuit 202 is configured to flow the working fluid from the inlet 132, through the heat exchanger 130, and to the outlet 134 while transferring thermal energy from the heat source stream 1 10 to the working fluid by the heat exchanger 130.

[0106] In one or more configurations, the power generation system 220 is disposed on or in the power generation skid 222 generally contains inlets 225a, 225b and an outlet 227 fluidly coupled to and in thermal communication with the working fluid within the working fluid circuit 202. The inlets 225a, 225b are upstream of the power turbine 228 within the high pressure side of the working fluid circuit 202 and are configured to receive the heated and high pressure working fluid. In some examples, the inlet 225a may be fluidly coupled to the outlet 124 of the waste heat system 100 and configured to receive the working fluid flowing from the heat exchanger 120 and the inlet 225b may be fluidly coupled to the outlet 241 of the process system 210 and configured to receive the working fluid flowing from the turbopump 260 and/or the start pump 280. The outlet 227 is disposed downstream of the power turbine 228 within the low pressure side of the working fluid circuit 202 and is configured to provide the low pressure working fluid. In some examples, the outlet 227 may be fluidly coupled to the inlet 239 of the process system 210 and configured to flow the working fluid to the recuperator 216. [0107] A filter 215a may be disposed along and in fluid communication with the fluid line at a point downstream of the heat exchanger 120 and upstream of the power turbine 228. In some examples, the filter 215a may be fluidly coupled to the working fluid circuit 202 between the outlet 124 of the waste heat system 100 and the inlet 225a of the process system 210.

[0108] The portion of the working fluid circuit 202 within the power generation system 220 is fed the working fluid by the inlets 225a and 225b. A stop valve 217 may be fluidly coupled to the working fluid circuit 202 between the inlet 225a and the power turbine 228. The stop valve 217 is configured to control the flow of heated working fluid flowing from the heat exchanger 120, through the inlet 225a, and into the power turbine 228 while in an opened position. Alternatively, the stop valve 217 may be configured to cease the flow of working fluid from entering into the power turbine 228 while in a closed position.

[0109] An attemperator valve 223 may be fluidly coupled to the working fluid circuit 202 between the inlet 225b and the stop valve 217 upstream of a point on the fluid line that intersects the incoming stream from the inlet 225a. The attemperator valve 223 is configured to control the flow of heated working fluid flowing from the start pump 280 and/or the turbopump 260, through the inlet 225b, and to a stop valve 217, the power turbine bypass valve 219, and/or the power turbine 228.

[0110] The power turbine bypass valve 219 may be fluidly coupled to a turbine bypass line that extends from a point of the working fluid circuit 202 upstream of the stop valve 217 and downstream of the power turbine 228. Therefore, the bypass line and the power turbine bypass valve 219 are configured to direct the working fluid around and avoid the power turbine 228. If the stop valve 217 is in a closed position, the power turbine bypass valve 219 may be configured to flow the working fluid around and avoid the power turbine 228 while in an opened position. In one embodiment, the power turbine bypass valve 219 may be utilized while warming up the working fluid during a startup operation of the electricity generating process. An outlet valve 221 may be fluidly coupled to the working fluid circuit 202 between the outlet on the power turbine 228 and the outlet 227 of the power generation system 220.

[0111] In one or more configurations, the process system 210 is disposed on or in the main process skid 212 generally contains inlets 235, 239, and 255 and outlets 231 , 237, 241 , 251 , and 253 fluidly coupled to and in thermal communication with the working fluid within the working fluid circuit 202. The inlet 235 is upstream of the recuperator 216 and the outlet 154 is downstream of the recuperator 216. The working fluid circuit 202 is configured to flow the working fluid from the inlet 235, through the recuperator 216, and to the outlet 237 while transferring thermal energy from the working fluid in the low pressure side of the working fluid circuit 202 to the working fluid in the high pressure side of the working fluid circuit 202 by the recuperator 216. The outlet 241 of the process system 210 is downstream of the turbopump 260 and/or the start pump 280, upstream of the power turbine 228, and configured to provide a flow of the high pressure working fluid to the power generation system 220, such as to the power turbine 228. The inlet 239 is upstream of the recuperator 216, downstream of the power turbine 228, and configured to receive the low pressure working fluid flowing from the power generation system 220, such as to the power turbine 228. The outlet 251 of the process system 210 is downstream of the recuperator 218, upstream of the heat exchanger 150, and configured to provide a flow of working fluid to the heat exchanger 150. The inlet 255 is downstream of the heat exchanger 150, upstream of the drive turbine 264 of the turbopump 260, and configured to provide the heated high pressure working fluid flowing from the heat exchanger 150 to the drive turbine 264 of the turbopump 260. The outlet 253 of the process system 210 is downstream of the pump portion 262 of the turbopump 260 and/or the pump portion 282 of the start pump 280, couples a bypass line disposed downstream of the heat exchanger 150 and upstream of the drive turbine 264 of the turbopump 260, and configured to provide a flow of working fluid to the drive turbine 264 of the turbopump 260.

[0112] Additionally, a filter 215c may be disposed along and in fluid communication with the fluid line at a point downstream of the heat exchanger 150 and upstream of the drive turbine 264 of the turbopump 260. In some examples, the filter 215c may be fluidly coupled to the working fluid circuit 202 between the outlet 154 of the waste heat system 100 and the inlet 255 of the process system 210.

[0113] In another embodiment described herein, as illustrated in Figure 2, the heat engine system 200 contains the process system 210 disposed on or in a main process skid 212, the power generation system 220 disposed on or in a power generation skid 222, the waste heat system 100 disposed on or in a waste heat skid 102. The working fluid circuit 202 extends throughout the inside, the outside, and between the main process skid 212, the power generation skid 222, the waste heat skid 102, as well as other systems and portions of the heat engine system 200. In some embodiments, the heat engine system 200 contains the bypass line 160 and the bypass valve 162 disposed between the waste heat skid 102 and the main process skid 212. A filter 215b may be disposed along and in fluid communication with the fluid line 135 at a point downstream of the heat exchanger 130 and upstream of the recuperator 216. In some examples, the filter 215b may be fluidly coupled to the working fluid circuit 202 between the outlet 134 of the waste heat system 100 and the inlet 235 of the process system 210.

[0114] It is to be understood that the present disclosure describes several exemplary embodiments for implementing different features, structures, or functions of the invention. Exemplary embodiments of components, arrangements, and configurations are described herein to simplify the present disclosure, however, these exemplary embodiments are provided merely as examples and are not intended to limit the scope of the disclosure. Additionally, the present disclosure may repeat reference numerals and/or letters in the various exemplary embodiments and across the Figures provided herein. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various exemplary embodiments and/or configurations discussed in the various Figures. Moreover, the formation of a first feature over or on a second feature in the present disclosure may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed interposing the first and second features, such that the first and second features may not be in direct contact. Finally, the exemplary embodiments described herein may be combined in any combination of ways, i.e. , any element from one exemplary embodiment may be used in any other exemplary embodiment without departing from the scope of the disclosure.

[0115] Additionally, certain terms are used throughout the written description and claims to refer to particular components. As one skilled in the art will appreciate, various entities may refer to the same component by different names, and as such, the naming convention for the elements described herein is not intended to limit the scope of the disclosure, unless otherwise specifically defined herein. Further, the naming convention used herein is not intended to distinguish between components that differ in name but not function. Further, in the written description and in the claims, the terms "including", "containing", and "comprising" are used in an open-ended fashion, and thus should be interpreted to mean "including, but not limited to". All numerical values in this disclosure may be exact or approximate values unless otherwise specifically stated. Accordingly, various embodiments of the disclosure may deviate from the numbers, values, and ranges disclosed herein without departing from the intended scope. Furthermore, as it is used in the claims or specification, the term "or" is intended to encompass both exclusive and inclusive cases, i.e. , "A or B" is intended to be synonymous with "at least one of A and B", unless otherwise expressly specified herein. [0116] The foregoing has outlined features of several embodiments so that those skilled in the art may better understand the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions and alterations herein without departing from the spirit and scope of the present disclosure.