TECHNICAL FIELD

Embodiments of the present invention relate to provision of thermal energy for industrial, commercial and domestic heat generation applications such as steam generation, hot air generation, hot water generation, process heaters, ovens and dryers (indirect and direct type) and more particularly to a system and a method for delivery of thermal energy using a fluid medium that leads to enhanced heat transfer and emission controls. BACKGROUND ART

Heat generated after combustion of fuel may be used for heating a process fluid or maybe used for some other application such as for steam generation, hot air generation, hot water generation, process heaters, ovens and indirect type dryers. In a very specific application, Hot Thermal Fluid Generator (TFH) is very common utility equipment in many of the industries. Hot thermal oil, as a process fluid, is generated in TFH to a temperature as per a process requirement. This heated thermal oil is pumped to the user exchanger where heat of the hot thermal fluid is utilised to heat a process fluid. As heat is transferred to process fluid, temperature of thermal oil reduces compared to a supply temperature of oil. This return thermal oil is again sent back to TFH where it is reheated to a required temperature and pumped back to heat the process fluid.

TFH is typically used for any temperature up to 330°C. Different grades of thermal oils are used based on the maximum required process temperature. TFH is generally used where requirement process temperature is more than 180°C because heating with other media like steam for such higher temperature application leads to increase in system pressure. Safe operation limit of system pressure is managed by using TFH even for 330°C process temperature. Based on availability of solid fuel at nearby areas, coal, coke, briquettes, bagasse, rice husk etc. are the main solid fuels used in TFH. Liquid and gases fuels like Diesel, Furnace Oil, Natural Gas and Naphtha are also used in TFH.

TFH is a type of furnace and comprises of two sections: radiant section and convective Section. The nomenclature is given based on the mode of heat transfer between flue gases generated due to combustion of fuel and the thermal oil. The fuel is fired in the furnace and generated flue gases are passed through radiant section and then in to convective section before exhausted to atmosphere. During the return flow, the thermal oil first enters the convective section followed by the radiant section and comes out of the TFH with the required temperature. Thermal Oil Pumps are integral parts of the system which maintain the required flow of the hot oil. The flue gases are vented to atmosphere through chimney by using blowers in all types of Thermal Oil Heaters except natural draft design.

There are various other application areas where transfer of thermal energy may be required. For example, in some of the hot water generators, process heaters and hot air generators etc. once through cycle for process fluids is utilized and process fluids are not re-circulated back to the heaters and either consumed or utilized in some other process. In another example, for applications of such as kilns, dryers and ovens etc., the fluid medium comes in direct contact with the process fluid or solids being heated. All the systems discussed above employ direct flame heating. Also, fluid medium being used to deliver thermal energy is expended, to the atmosphere, through the stack, after only a single pass, leading to wastage of heat energy and additionally of pollution of the atmosphere is increased. All this leads to excessive consumption of fuels.

Additionally, there are other deficiencies from which the above systems suffer, such as, but not limited to:

1 . Most of the systems are open flame systems where combustion is carried out at ambient pressure with air and combusted flue gas temperature is controlled with the help of excess air/ dilution air.

2. In open flame system, it is difficult to achieve maximum adiabatic flame temperature without multistage combustion arrangement. The gases coming out at adiabatic temperature levels are not normally used in present applications. Whenever multistage combustion is used, dilution air is added in it to bring down the temperature.

3. Sometimes fuel (Liquid & Gaseous) is coming at higher pressure which needs to depressurize before firing.

4. Flue gases generated at high temperatures and ambient pressure, after combustion, have low density which leads in requirement of higher heat transfer area.

5. Heat transfer is managed by keeping higher temperature difference between process fluid and flue gas. Flue gas temperature is very high than required process fluid temperature.

6. This high temperature ambient pressure flue gases sometimes create cold and hot spots which leads in uneven temperature in the process fluid.

7. In case of solid fuel firing systems, soot and scaling formation occurs on the heat transfer area.

8. Control of process fluid temperature at different turndown ratios becomes difficult.

9. Heat exchange area is divided into two sections, radiant and convective due to higher temperature difference between the process fluid and fluid medium.

10. The difference between required process fluid temperature and flue gas temperature at firing is high which leads in rise in film temperature causes degradation of the process fluid and scaling on the contact surface of conduits carrying the process fluid.

1 1 . Recovery of heat from generated flue gases is limited with process fluid temperature. Higher the process fluid temperature (inlet to exchanger) leads to high exhaust flue gas temperature leads in lower efficiency of heater

12. Due to use of excess air, temperature of flue gas gets diluted and leads in higher volumes of flue gas.

13. Limited efficiency leads to higher fuel consumption and increasing proportionate harmful emissions.

14. In case of forced draft design, additional combustion air pre-heater is used to minimise heat loss which will save some percentage of fuel consumption at the cost of higher CAPEX.

15. Present forced draft design has supporting systems like Fans and blowers to keep required flow and velocities of hot gases across heater, which requires large footprint and CAPEX.

16. Electrical consumption to run blowers is high which results in the higher operating costs.

17. Required substantial time for system stabilization during start-up condition

18. To reduce emissions, the systems like ESP, Scrubber, cyclone etc. are used which required more footprint and supporting to increase operating cost. 19. A chimney is required to vent the gases at certain level due to its temperature and hazardous emissions even after implementation of various measures used for removal of emissions.

20. In the systems which employ steam as the fluid medium are incapable of re-using the heat energy of the steam after a single pass, and most of energy of the used steam is expended through equipment such as condensers and various exchangers etc. leading to wastages of heat energy

In light of the discussion above, there is a need in the art for a system and a method for delivery of thermal energy, that do not suffer from above mentioned deficiencies.

OBJECT OF THE INVENTION

An object of the present invention is to provide a system and a method for delivery of thermal energy, where fuel is efficiently combusted at near adiabatic temperatures.

Another object of the invention is to implement the system and the method for delivery of thermal energy to applications involving once through process fluids, re-circulating thermal fluids and direct contact type heating of the process fluids and solids. Yet another object of the invention is to provide a system and a method for delivery of thermal energy, where a fluid medium, being used to deliver the thermal energy, is re-cycled.

Yet another object of the invention is to provide a system and a method for delivery of thermal energy, which enhances the rate of heat transfer between the fluid medium and the process fluids and solids. Yet another object of the invention is to provide a system and a method for delivery of thermal energy, which achieves delivery of the thermal energy with relatively negligible emissions.

SUMMARY OF THE PRESENT INVENTION

The present invention is described hereinafter by various embodiments.

This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. According to a first aspect of the present invention, there is provided a system for delivery of thermal energy, the system comprising a pre-heater, a combustion chamber connected downstream of the pre-heater, a fluid mixer connected downstream of the combustion chamber, a heat exchanger connected downstream of the fluid mixer and a surge vessel connected downstream of the heat exchanger, the surge vessel, the fluid mixer and the heat exchanger together forming a closed loop for a fluid medium to operate in. The pre-heater is configured to pre-heat one or more of a fuel and air. The combustion chamber is configured to receive one or more of the air and the fuel from the pre-heater, combust the fuel to generate heat energy in form of flue gases. The fluid mixer is configured to control physical and chemical parameters associated with the fluid medium, by receiving a pressure enhancing fluid and vaporizing the pressure enhancing fluid. The heat exchanger is configured to transfer at least a part of heat energy of the fluid medium to a process fluid. Also, the surge vessel is configured to receive the fluid medium from the heat exchanger and discharge the fluid medium to one or more of the fluid mixer and the pre-heater.

In accordance with an embodiment of the present invention, the fuel is one or more of gaseous fuels, liquid fuels, semi-solid fuels and solid fuels.

In accordance with an embodiment of the present invention, the system further comprises a flue gas booster connected downstream of the combustion chamber, wherein the flue gas booster is configured to pressurize the flue gases above atmospheric pressure.

In accordance with an embodiment of the present invention, the heat exchanger is designed to enable transfer of heat energy to more than one process fluids simultaneously.

In accordance with an embodiment of the present invention, the system further comprises a temperature sensor, a pressure sensor and a mass flow rate sensor provided along the closed loop, the temperature sensor, the pressure sensor and the mass flow rate sensor being connected to control devices.

In accordance with an embodiment of the present invention, the system further comprises a booster installed between the surge vessel and the fluid mixer, the booster being configured to pressurize the fluid medium, wherein pressurized fluid medium is used to atomize the pressure enhancing fluid at the time of introduction of the pressure enhancing fluid into the fluid mixer.

In accordance with an embodiment of the present invention, piping and equipment handling flue gases, is insulated to prevent heat transfer and the piping and the equipment include cooling systems to maintain operating temperatures.

In accordance with an embodiment of the present invention, the pressure enhancing fluid is a phase change fluid, supplied to the fluid mixer in liquefied form. In accordance with an embodiment of the present invention, the system further comprises additional filters upstream and/or downstream of the heat exchanger.

In accordance with an embodiment of the present invention, the system further comprises a cyclone and a separator downstream of the heat exchanger.

In accordance with an embodiment of the present invention, the system further comprises a heat storage device configured to store heat energy of the fluid medium using a high heat capacity material.

According to a second aspect of the present invention, there is provided a system for delivery of thermal energy, the system comprising a fluid mixer, a heat exchanger connected downstream of the fluid mixer, a surge vessel connected downstream of the heat exchanger, the surge vessel, the fluid mixer and the heat exchanger together forming a closed loop for a fluid medium to operate in, a pre-heater, a combustion chamber connected downstream of the pre-heater, a pressure enhancing chamber connected downstream of the combustion chamber, an external heater connected downstream of the pressure enhancing chamber and a second surge vessel connected downstream of the external heater, the combustion chamber, the pressure enhancing chamber, the external heater and the second surge vessel together forming a second closed loop for the flue gases to operate in. The pre- heater is configured to pre-heat one or more of a fuel and air. The combustion chamber is configured to receive the one or more of the air and the fuel from the pre-heater, combust the fuel to generate heat energy in form of flue gases. The pressure enhancing chamber is configured to receive one or more of a pressure enhancing fluid and a second pressure enhancing fluid and vaporize the one or more of the pressure enhancing fluid and the second pressure enhancing fluid, for increasing the pressure of the flue gases. The external heater is configured to transfer the heat energy of the flue gases to the fluid medium circulating in the closed loop. The fluid mixer is configured to control physical and chemical parameters associated with the fluid medium, by receiving the pressure enhancing fluid and vaporizing the pressure enhancing fluid. The heat exchanger is configured to transfer at least a part of heat energy of the fluid medium to a process fluid. The surge vessel is configured to receive the fluid medium from the heat exchanger and discharge the fluid medium to one or more of the fluid mixer and the pre-heater. Also, the second surge vessel is configured to receive excess flue gases from the second closed loop and discharge the excess flue gases to the pre-heater.

In accordance with an embodiment of the present invention, the system further comprises a heat storage device connected upstream of the heat exchanger is the closed loop and configured to store heat energy of the fluid medium using a high heat capacity material. In accordance with an embodiment of the present invention, the system further comprises additional filters upstream and/or downstream of the heat exchanger.

In accordance with an embodiment of the present invention, the system further comprises a cyclone and a separator downstream of the heat exchanger. According to a third aspect of the present invention, there is provided a system for heating steam as a process fluid, the system comprising a flow splitter, a steam booster and a water pre-heater connected downstream of the flow splitter, a heat exchanger downstream of the steam booster and a pressure booster connected downstream of the heat exchanger. The flow splitter is configured to divide a main stream of steam into a first stream of steam and a second stream of steam. The steam booster is configured to receive the first stream and pressurize the first stream. The heat exchanger is configured to heat the pressurized first stream leaving the steam booster. The water pre-heater is configured to receive the second stream and pre-heat a water stream being pumped from a water tank, using the second stream. Also, the pressure booster is configured to increase a pressure of the heated first stream leaving the heat exchanger, by mixing the pre-heated water stream in atomized form.

According to a fourth aspect of the present invention, there is provided a method for delivery of thermal energy, the method comprising steps of receiving one or more of air and a fuel from a pre-heater, in a combustion chamber, combusting the fuel to generate heat energy in form of flue gases, in the combustion chamber, transferring the heat energy to a fluid medium, controlling physical and chemical parameters associated with the fluid medium, in a fluid mixer, by receiving a pressure enhancing fluid and vaporizing the pressure enhancing fluid, transferring at least a part of heat energy of the fluid medium to a process fluid, in a heat exchanger, receiving the fluid medium from the heat exchanger, in a surge vessel and discharging the fluid medium to one or more of the fluid mixer and the pre-heater. The surge vessel, the fluid mixer and the heat exchanger together form a closed loop for the fluid medium to operate in.

In accordance with an embodiment of the present invention, the method further comprises a step of pressurizing the flue gases, using a flue gas booster, to raise pressure of the flue gases above the ambient pressure.

In accordance with an embodiment of the present invention, the physical and chemical parameters include pressure, temperature, turbulence, velocity, mass flow rate and boundary layer characteristics. In accordance with an embodiment of the present invention, the pressure enhancing fluid is atomized before being introduced into the fluid mixer, wherein a portion of the fluid medium is pressurized, the pressurized portion acting as an atomization fluid to atomize the pressure enhancing fluid. In accordance with an embodiment of the present invention, the pressure enhancing fluid is a phase change fluid, supplied to the fluid mixer in liquefied form.

In accordance with an embodiment of the present invention, the method further comprises a step of suspending combustion in the combustion chamber.

According to a fifth aspect of the present invention, there is provided a method for delivery of thermal energy, the method comprising steps of receiving the one or more of the air and the fuel from a pre-heater and combusting the fuel to generate heat energy in form of flue gases, in a combustion chamber, receiving one or more of a pressure enhancing fluid and a second pressure enhancing fluid, for increasing the pressure of the flue gases by vaporizing the one or more of the pressure enhancing fluid and the second pressure enhancing fluid, in a pressure enhancing chamber, transferring the heat energy of the flue gases to a fluid medium circulating in a closed loop, in an external heater, controlling physical and chemical parameters associated with the fluid medium, by receiving the pressure enhancing fluid and vaporizing the pressure enhancing fluid, in a fluid mixer, transferring at least a part of heat energy of the fluid medium to a process fluid, in a heat exchanger, receiving the fluid medium from the heat exchanger and discharging the fluid medium to one or more of the fluid mixer and the pre-heater, using a surge vessel and receiving the flue gases from a second closed loop and discharging excess flue gases to the pre-heater, using a second surge vessel. The surge vessel, the fluid mixer and the heat exchanger together form the closed loop for the fluid medium to operate in. Also, the combustion chamber, the pressure enhancing chamber, the external heater and the second surge vessel together form the second closed loop for the flue gases to operate in. In accordance with an embodiment of the present invention, the method further comprises a step of suspending combustion in the combustion chamber.

According to a sixth aspect of the present invention, there is provided a method for heating steam as a process fluid, the method comprising steps of dividing a main stream of steam into a first stream of steam and a second stream of steam, using a flow splitter, receiving the first stream and pressurizing the first stream, in a steam booster, heating the pressurized first stream leaving the steam booster, in a heat exchanger, receiving the second stream and preheating a water stream being pumped from a water tank, using the second stream, in a water pre-heater and increasing a pressure of the heated first stream leaving the heat exchanger, by mixing the pre-heated water stream in atomized form, using a pressure booster.

The system and the method for delivery of thermal energy offer a number of advantages, viz. 1 . Required Temperature with any differential temperature between inlet and outlet of heat exchanger can be achieved with the present invention.

2. System can be operated at any load with variable output of temperature and flow of process fluid.

3. Required temperature of process fluid is controlled with high precision and accordingly combustion also gets controlled. Mass flow and velocity of circulating fluid medium can be adjusted to control variations in temperature and flow. Intermittent firing can be possible in case of partial heat load on the system. Part load can be managed with proportionate reduction in the fuel consumption. The temperature difference between required temperature of process fluid and flue gas inlet to exchanger is maintained as minimum as possible to avoid rise in film temperature which leads to maintain the quality of the process fluid. Pressurised combustion system of the present invention will eliminate the use of induced draft and forced draft fans resulting in lower operating costs. The High-pressure circulating fluid medium used in the present invention and high velocity inside the heat exchanger will enhance the heat transfer rate and give benefit of reduced heat transfer area and compact design. Operating temperature of fluid medium of the present invention is ranging from 150°C to possible adiabatic combustion temperature. This can be much higher depending on the material constrains and application area. Excess air used at combustion level is very minimum. All types of fossil fuel and bio fuel with any form (Gas, Liquid, solid and Semi-solid) based design are possible to be used. Design of system with any combination of fuels is also possible.

13. The present invention is compatible for pipe in pipe type, shell and tube type, coil type etc. or any other type of heat exchangers as per application requirement where heat exchange takes place between fluid medium and process fluid.

14. Pressure enhancing fluid required in this system is minimal and almost up to 98% is recycled back to the system. The water formed in fuel combustion process is also recovered.

15. The efficient scrubbing system of this technology ensures negligible GHG emissions and particulate matter.

16. The clean and warm gases are exhausted to the atmosphere and do not require high stack arrangements or any other flue gas cleaning system.

17. Design of combustion chamber can be based on use of Ambient Air, Pure Oxygen or Oxygen Enriched Air to carry out oxidation of fuel. 18. The present invention can be used for retrofitting of existing furnaces with minimum modifications.

19. The present invention is suitable for O. I GCal equivalent output to any utility scale models.

20. Velocity and mass flow of circulating fluid is controllable automatically on real time basis to get optimum output as per the demand.

21 .The present invention is compatible for PLC based operation and offsite monitoring and troubleshooting

22. Skid mounted modular designs are also possible for ease of operation and flexibility.

23. Full load stable operations can be achieved in minutes after every startup and the present invention allows easy shut downs.

24. The efficient firing of the process cycle can be used in all types of process fired heaters, Utility Fired Heaters, Boilers, Hot Air Generators,

Hot Water Generators, Ovens, Dryers and any other application which require direct heat energy.

25. The present invention contributes to firing at near adiabatic temperatures and control of flue gas temperatures through mixing of liquid phase change materials thereby reducing the high temperature to manageable required temperatures and also concentrating the heat energy in the flue gases, by decreasing the volume through means of pressurization and increased velocities.

26. Steam, at pressures above ambient, and even in superheated conditions, may be re-cycled within the process loop with energy of the steam being boosted to enable its reuse in the process loop, with the implementation of the present invention.

27. Direct contact type heating is made possible for both open loop processes and closed loop processes, with the present invention. BRIEF DESCRIPTION OF DRAWINGS

So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may have been referred by examples, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawing illustrates only typical examples of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective examples.

These and other features, benefits, and advantages of the present invention will become apparent by reference to the following text figure, with like reference numbers referring to like structures across the views, wherein:

Fig. 1A illustrates a system for delivery of thermal energy, in accordance with an embodiment of the present invention;

Fig. 1 B illustrates a heat exchanger, in accordance with an embodiment of the present invention;

Fig. 1 C illustrates a closed loop for operation of a fluid medium, in accordance with an embodiment of the present invention;

Fig. 2 illustrates a method for delivery of thermal energy, in accordance with an embodiment of the present invention; Fig. 3A illustrates a control scheme for regulation of a mixture of air and fuel into a pre-heater in accordance with an embodiment of the present invention;

Fig. 3B illustrates an atomization scheme for atomization of a pressure enhancing fluid, in accordance with an embodiment of the present invention; Fig. 4 illustrates pre-heating arrangement for a process fluid, in accordance with an embodiment of the present invention;

Fig. 5 illustrates implementation of the system for delivery of thermal energy, in a closed process loop application, in accordance with an embodiment of the present invention;

Fig. 6 illustrates implementation of the system for delivery of thermal energy, for direct contact heating, in accordance with an embodiment of the present invention; Fig. 7A illustrates a system for delivery of thermal energy, in accordance with another embodiment of the present invention;

Fig. 7B illustrates a method for delivery of thermal energy, in accordance with another embodiment of the present invention;

Fig. 7C illustrates the system for delivery of thermal energy of Fig. 7A, in accordance with yet another embodiment of the present invention;

Fig. 8 illustrates the system for delivery of thermal energy of Fig. 1 A, in accordance with yet another embodiment of the present invention;

Fig. 9A illustrates a system for heating steam as a process fluid, in accordance with an embodiment of the present invention; Fig. 9B illustrates a method for heating steam as a process fluid, in accordance with an embodiment of the present invention;

Fig. 10 illustrates the system for delivery of thermal energy of Fig. 7A, in accordance with yet another embodiment of the present invention; and

Fig. 11 illustrates the system for delivery of thermal energy of Fig. 7A, in accordance with yet another embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the present invention is described herein by way of example using embodiments and illustrative drawings, those skilled in the art will recognize that the invention is not limited to the embodiments of drawing or drawings described and are not intended to represent the scale of the various components. Further, some components that may form a part of the invention may not be illustrated in certain figures, for ease of illustration, and such omissions do not limit the embodiments outlined in any way. It should be understood that the drawings and detailed description thereto are not intended to limit the invention to the particular form disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternatives falling within the scope of the present invention as defined by the appended claim. As used throughout this description, the word "may" is used in a permissive sense (i.e. meaning having the potential to), rather than the mandatory sense, (i.e. meaning must). Further, the words "a" or "an" mean "at least one" and the word "plurality" means "one or more" unless otherwise mentioned. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope. Language such as "including," "comprising," "having," "containing," or "involving," and variations thereof, is intended to be broad and encompass the subject matter listed thereafter, equivalents, and additional subject matter not recited, and is not intended to exclude other additives, components, integers or steps. Likewise, the term "comprising" is considered synonymous with the terms "including" or "containing" for applicable legal purposes. Any discussion of documents, acts, materials, devices, articles and the like are included in the specification solely for the purpose of providing a context for the present invention. It is not suggested or represented that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present invention.

In this disclosure, whenever a composition or an element or a group of elements is preceded with the transitional phrase "comprising", it is understood that we also contemplate the same composition, element or group of elements with transitional phrases "consisting of", "consisting", "selected from the group of consisting of, "including", or "is" preceding the recitation of the composition, element or group of elements and vice versa.

The present invention is described hereinafter by various embodiments with reference to the accompanying drawing, wherein reference numerals used in the accompanying drawing correspond to the like elements throughout the description. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiment set forth herein. Rather, the embodiment is provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art. In the following detailed description, numeric values and ranges are provided for various aspects of the implementations described. These values and ranges are to be treated as examples only and are not intended to limit the scope of the claims. In addition, a number of materials are identified as suitable for various facets of the implementations. These materials are to be treated as exemplary and are not intended to limit the scope of the invention.

Referring to the drawings, the invention will now be described in more detail. Figure 1A illustrates a system 100 for delivery of thermal energy in accordance with an embodiment of the present invention. As shown in figure 1 , the system 100 comprises a pre-heater 102. The pre-heater 102 is used to preheat one or more of the air and fuel entering into the combustion chamber 104. The pre-heating of the air and/or the fuel increases a thermal efficiency of the combustion process which may be orchestrated in the combustion chamber 104. The term air here encompasses air, oxygen enriched air or pure oxygen, as will be appreciated by a person skilled in the art. In various embodiments, the design of the combustion chamber 104 depends upon a number of factors, including, but not limited to, type of fuel (for example solid, semi-solid, liquid or gaseous) and fluid medium being used in the system 100. For example, the design of the combustion chamber 104 may vary depending upon whether air is the fluid medium or air and steam mixture is the fluid medium. There may be other variations in the design of the combustion chamber 104 depending upon the specific requirements of the system 100. For example, another factor in deciding a design of the combustion chamber 104 may be operating conditions and how or how many times firing is being achieved. Additionally, the combustion chamber 104 for combustion of solid fuels/solid waste may be designed for single stage combustion or multi-stage combustion. Further downstream of the combustion chamber 104 is an inline filtering system 105. The inline filtering system 105 is configured to remove any ash and particulate matters etc. from combustion products. This is highly desirable, especially in cases where air is the fluid medium and/or coal is used as the fuel. In various embodiments, the inline filtering system 105 may be provided within an assembly of the combustion chamber 104. Further downstream of the inline filtering system 105 there may also be provided a flue gas booster 107. The flue gas booster 107 may be required in scenarios where the flue gases generated in the combustion chamber are at ambient pressure, whereas it might be a requirement of the system 100 for the flue gases to be pressurized to a higher pressure than the ambient. In the context of this specification, a "booster" or a "pressure booster" is envisaged to include all kinds of pressure enhancing mechanisms working on fluids, such as compressors (centrifugal and positive displacement), fans and blowers etc. Further connected downstream of the inline filtering system 105 is a fluid mixer 106. The fluid mixer 106 is also configured to regulate chemical and physical parameters associated with a fluid medium in the system 100. In that manner it is envisaged that the fluid mixer 106 is further configured to receive a pressure enhancing fluid from an external source. In various embodiments, the pressure enhancing fluid is selected from a group consisting of liquefied Carbon-di-Oxide (CO2), de-mineralized water and or combinations thereof. The pressure enhancing fluid vaporizes on receiving heat from the flue gases. In that manner it is envisaged that the fluid medium is a mixture of flue gases received from the combustion chamber 104 and the vaporized pressure enhancing fluid received from the external source. The chemical and physical parameters include, but are not limited to, pressure, velocity, temperature, turbulence and boundary layer characteristics of the fluid medium. Further connected downstream of the fluid mixer 106 is a heat exchanger 108. Figure 1 B illustrates the heat exchanger 108 in accordance with an embodiment of the present invention. In various embodiments, the heat exchanger 108 may be one of, but not limited to, pipe in pipe, shell and tube, coil type and fin-tube etc. The heat exchanger 108 has a fluid medium inlet 1082 and a fluid medium outlet 1084 for receiving and discharging the fluid medium respectively. Additionally, the heat exchanger 108 has a process fluid inlet 112 and a process fluid outlet 114 for receiving and discharging a process fluid. The process fluid may pertain to a number of applications and industries. In various embodiments, the process fluid is selected from a group consisting of, but not limited to, oil, steam, air and combinations thereof. Additionally, the process fluid may be used for a number of applications such as steam generation, hot air generation, hot water generation, process heaters, ovens and indirect type dryers. Additionally, the heat exchanger 108 may be designed to enable transfer of heat energy to more than one process fluids simultaneously. For example, a second process fluid may be introduced through a second process fluid inlet 1121 and leave the heat exchanger through a second process fluid outlet 1141. Such designs are available in the art and may be used in implementation of the present invention. Further connected downstream of the heat exchanger 108 is a surge vessel 110. Further connected downstream of the surge vessel 110 are the fluid mixer 106 and the pre-heater 102. The surge vessel 110, the fluid mixture 106 and the heat exchanger 108 together form a closed loop 115 for the fluid medium to operate in.

Figure 1 C illustrates the closed loop 115 for operation of the fluid medium, in accordance with an embodiment of the present invention. As can be seen in figure 1 C additional sensors may be provided along a circulation route of the fluid medium. Such sensors include, but are not limited to, a temperature sensor 1152, a pressure sensor 1154 and a mass flow rate sensor 1156. Other sensors may also be included in the closed loop 115 for control of working of the system 100 as will be appreciated by a person skilled in the art. Additionally a booster 111 may be installed between the surge vessel 110 and the fluid mixer 106 configured to pressurize the fluid medium. The pressurized fluid medium may be used to atomize the pressure enhancing fluid at the time of introduction of the pressure enhancing fluid into the fluid mixer 106.

The surge vessel 110 may be connected to the fluid mixer 106 through a flow control valve 120. The surge vessel 110 is configured to receive excess fluid medium from the closed loop 115 and discharge the excess fluid medium to the fuel and pre-heater 102. The excess fluid medium may then be recovered or discharged to the atmosphere through a vent gas treatment system 130.

The vent gas treatment system 130 comprises a gas scrubber 132 and a purification system 134. The gas scrubber 132 is a pollution control device configured to remove harmful and undesirable pollutants that might be present in the vent gases coming out of system 100. The design of the gas scrubber 132 may vary depending upon the type and/or composition of the vent gases. For example, different scrubbers may be used for different vent gases such as air, air and steam mixture, air and ammonia mixture etc. or potential pollutants such as Oxides of Nitrogen (NOx), Sulphur Dioxide (SO2), Carbon Dioxide (CO2) or Water, as will be appreciated by a person skilled in the art. The gas scrubber 132 employs one or more scrubbing fluids to achieve scrubbing of the vent gases. One example of the scrubbing fluid is water.

The gas scrubber 132 is further connected with the purification system 134 configured to purify the one or more scrubbing fluids, after the use of the scrubbing fluids in the gas scrubber 132. The purified scrubbing fluids may in turn be used for various purposes inside the system 100. In various embodiments, the purification system 134 may act as the external source feeding the scrubbing fluid (more specifically water) as the pressure enhancing fluid.

It is further contemplated here that the system 100 may constitute an industrial plant and may be provided with other equipment essential for running of the industrial plant. Such equipment includes, but is not limited to, control devices such as enterprise servers, plant servers, PLC controllers, input/output devices and field devices such as sensors (pressure, temperature, speed etc), actuators (motors, pumps and valves etc.) and the like. These and other equipment may operate under supervision of an operator or automatically to aid in achieving objectives of this invention. Process controls are also achievable vide embedded systems of sensors and actuators controlled remotely and/or locally enabling advance services and support Internet of Things (ΙοΤ) and Distributed Control System (DCS) and any other enabling technology which can be contemplated to be applicable for this invention, existing at the date of filing or appearing in foreseeable future.

All piping and other equipment handling hot flue gases and combustion equipment will be suitably insulated and wherever the need is, a cooling system may be employed.

Figure 2 illustrates a method 200 for delivery of thermal energy, in accordance with an embodiment of the present invention. The method begins at step 210 by receiving one or more of air and a fuel from the pre-heater 102, in the combustion chamber 104. In case, the fuel is a liquid or gaseous fuel, a mixture of the air and the fuel are received from the pre-heater inside the combustion chamber 104. Alternately, in case of the fuel being a solid fuel, only pre-heated air is received in the combustion chamber 104.

Figure 3A illustrates a control scheme for regulation of the mixture of air and fuel into the pre-heater 102 in accordance with an embodiment 300 of the present invention. Here, a temperature sensor 302 is connected to the process fluid outlet 114. The temperature sensor 302 senses a temperature of the process fluid at the process fluid outlet 114. The sensed temperature value is transmitted to a regulator 304, by the temperature sensor 302. The regulator 304 then regulates the supply of the air and fuel from the pre-heater 102 to the combustion chamber 104.

At step 220, the fuel is combusted in the combustion chamber 104, to generate heat energy in form of flue gases. In one embodiment of the invention, the flue gases are transferred from the combustion chamber 104 to the fluid mixer 106 to be a part of the fluid medium. In various alternate embodiments, the flue gases generated in the combustion chamber 104 are filtered by the inline filtering system 105 to remove pollutants such as ash and particulate matter from the flue gases. Additionally, in one embodiment, the flue gas booster 107 pressurizes the flue gases to raise the pressure of the flue gases above the ambient pressure. Pressurizing of the flue gases increases the efficiency of heat transfer between the flue gases and the fluid medium. In various other embodiments, the fluid medium may not comprise flue gases generated in the combustion chamber 104.

At step 230, the heat energy is transferred to the fluid medium. The flue gases enter the fluid mixer 106 to become a part of the fluid medium, as shown in Figure 1. Here it is contemplated that in case of only a part of the heat energy is transferred between the flue gases and the fluid medium, the flue gases can be re-circulated as long as the flue gases have a higher temperature compared to the temperature of the fluid medium. As long as there is an adequate temperature difference between the temperature of the flue gases and the temperature of the fluid medium to enable sufficient heat transfer between the flue gases and the fluid medium, there will not be a need to add further heat to the flue gases, allowing combustion in the combustion chamber 104 to be temporarily suspended during that period.

At step 240, physical and chemical parameters associated with the fluid medium are controlled through the fluid mixer 106. The control may be achieved by the PLC controller receiving information from the temperature sensor 1152, the pressure sensor 1154, the mass flow rate 1156 and other such sensors. The physical and chemical parameters include but are not limited to pressure, temperature, turbulence, velocity, mass flow rate and boundary layer characteristics. For example, the pressure of the fluid medium may be increased by initially restricting the flow of the fluid medium to the heat exchanger 108. By pressurizing the fluid medium, more and more mass can be packed into the same volume of the fluid medium, thereby increasing capacity of the fluid medium to carry thermal energy. Increased capacity to carry thermal energy ensures that greater amount of heat can be transferred to the fluid medium without substantially increasing the temperature of the fluid medium as compared to technology present in the state of the art. This is particularly useful in applications which are known to be temperature sensitive. This also ensures efficient heat transfer to the fluid medium in embodiments where external heaters are employed to heat the fluid medium. Increasing velocity of the fluid medium has an advantage of increasing a rate of heat transfer. Similarly, increasing turbulence and disrupting boundary layer at a surface between the fluid medium and the process fluids also aid in increasing rate of heat transfer between the fluid medium and the process fluids.

Further, the pressure enhancing fluid is introduced into the fluid mixer 106 to enhance the pressure of the fluid medium. The pressure enhancing fluid introduced into the fluid mixer 106 vaporizes on receiving heat from the flue gases. In that manner, it is contemplated that the pressure of the pressure enhancing fluid may be kept higher than the pressure of the fluid medium in the closed loop 115. It is desired here that the pressure enhancing fluid be atomized before being introduced into the fluid mixer 106, for better mixing with the fluid medium.

Figure 3B illustrates an atomization scheme for atomization of the pressure enhancing fluid, in accordance with an embodiment of the present invention. The fluid medium is pressurized using the booster 111 and a portion of the pressurized fluid medium is used as an atomization fluid to atomize the pressure enhancing fluid, at the time of introduction of the pressure enhancing fluid into the fluid mixer 106. The atomization fluid may further be pressurized by a pressure increasing mechanism 306, such as a blower, compressor (centrifugal or positive displacement) and other such equivalent equipment. However, there may be applied many other atomizing schemes such using disk type, inline, accumulator type atomizers and any other equivalent scheme known in the art, as will be appreciated by a skilled artisan.

In various embodiments, the pressure enhancing fluid is a phase change fluid, supplied to the fluid mixer 106 in liquefied form. Further, the pressure enhancing fluid absorbs the heat energy of the fluid medium, to change from liquid phase to gaseous phase. It is further contemplated here, that to aid faster phase transformation of the pressure enhancing fluid, the pressure enhancing fluid is supplied to the fluid mixer 106 at a high temperature.

At step 250, at least a part of the heat energy of the fluid medium is transferred to the process fluid, in the heat exchanger 108. Here it is contemplated that in case of only part of the heat transfer between the fluid medium and the process fluid, the fluid medium can be re-circulated as long as the fluid medium has a higher temperature compared to the temperature of the process fluid. As long as there is an adequate temperature difference between the temperature of the fluid medium and the temperature of the process fluid to enable sufficient heat transfer between the fluid medium and the process fluid, there will not be a need to add further heat to the fluid medium, allowing combustion in the combustion chamber 104 to be temporarily suspended during that period. For this purpose, it is envisaged that the difference between the temperatures of the fluid medium and the process fluid are kept closer than what is practiced in the art, to minimize heat wastage. It will be appreciated by a person skilled in the art that the heat exchanger 108 design may vary as per the application of the system 100. Depending upon the application area, the heat exchanger 108 may be a single pass or a multi-pass heat exchanger. Further, it will be appreciated by a person skilled in the art, that the term process fluid encompasses both fluids being used in industrial applications as well as solids that my need to be heated or dried as per process requirements. At step 260, the fluid medium is received from the heat exchanger 108, in the surge vessel 110. The surge vessel 110 acts as a reservoir for the fluid medium and aids in management of portions of the fluid medium re-circulated in the closed loop 115 and discharged to the pre-heater 102.

At step 270, the fluid medium is discharged from the surge vessel 110 to one or more of the fluid mixer 106 and the pre-heater 102. For example, when the temperature of the process fluid at the process fluid outlet 114 is within a predetermined range, flow of the fluid medium from the surge vessel 110 is almost entirely to the fluid mixer 106 which is then again transferred from the fluid mixer 106 to the heat exchanger 108. In that manner in this scenario, the combustion in the combustion chamber 104 may be temporarily suspended thereby providing savings in fuel and energy.

However, when the temperature of the process fluid at the process fluid outlet 114 falls below the predetermined range, additional mass of the heated fluid medium is introduced from the combustion chamber 104 into the fluid mixer 106 and equivalent mass of the fluid medium is taken from the surge vessel 110 discharged to the pre-heater 102. Here the discharge of the fluid medium from the surge vessel 110 is facilitated by the pressure control valve 122 which opens automatically as the additional mass of the heated fluid medium is introduced into the closed loop 115. In various other embodiments, the equivalent mass of the fluid medium can be predetermined based on system parameters, and the pressure control valve 122 may be operated automatically to release the equivalent mass as per predetermined schemes. For example, the equivalent mass can be discharged for every cycle, or between a number of cycles or intermittently as per the design requirements of the invention. The discharged fluid medium may pre-heat the process fluid entering into the heat exchanger 108, in a process fluid pre-heater 402 as shown in figure 4. Additionally, the discharged fluid medium may also pre-heat the one or more of the fuel and the air in the pre-heater 102. In one embodiment of the invention, after exiting the pre-heater 102, the discharged fluid medium is recovered and fed back to the closed loop 115. For example, in the case of the fluid medium being hexane or toluene or other industrial oils, the discharged fluid medium is recovered from the pre-heater 102.

In another embodiment of the invention, the discharged fluid medium travels from the pre-heater 102 to the vent gas treatment system 130. For example, in case of the fluid medium being flue gases or CO2, the discharged fluid medium is transferred to the vent gas treatment system 130. The vent gas treatment system 130 treats the fluid medium, for removal of pollutants, before discharging the fluid medium to the atmosphere.

Figure 5 illustrates implementation of the system 100 in a closed process loop application, in accordance with an embodiment of the present invention. The process fluid pre-heater 402 may or may not be required in this scenario, depending upon thermal requirements of the process 510.

Figure 6 illustrates implementation of the system 100 for direct contact heating, in accordance with an embodiment of the present invention. In this scenario, additional filters 602 and 604 may be required upstream and downstream, respectively of the heat exchanger 108, as the fluid medium comes in direct contact with the solid charge/ process fluid. The upstream filter 602 may ensure that the fluid medium does not carry any contaminants to contaminate the solid charge or the process fluid; whereas the downstream filter 604 ensures that the fluid medium does not carry any particles of the solid charge or the process fluid into the surge vessel 110. Additionally, there may be provided a cyclone 606 and a separator 608 for condensable substances, at the fluid medium outlet 1084. This implementation is applicable for kilns, dryers (including spray dryers, batch dryers and continuous dryers), furnaces and ovens (continuous and batch ovens). The fluid medium will come in direct contact with process fluid or solids.

In case of pressurized fluid medium, the fluid medium is expanded over solids, creating turbulence and velocity. This will result in faster heat and mass transfer and enhance drying application. In case of dryer applications, the fluid medium, air, CO2 and other constituents may have affinity towards water or other fluids present in the process fluid/solid. This will aid in faster drying. Individual fluids or combination of above mentioned fluids can be used as direct contact heat source, either in pressurized and/or high velocity form to optimize drying process.

In case of rotary kiln furnaces of similar equipment, use of low volume, high density hot fluid medium can be used to expand with increased velocity, so that higher heat transfer rates can be achieved. Applications requiring high temperature, for example in steel, cement, glass, petrochemicals etc. can be done through direct or indirect contact heat exchangers or in combination of both. Phase change materials like liquid CO2, oils and water etc. can be used depending on its specific heat capacity, to optimize heat transfer, by partial or complete vaporization, into the fluid medium.

Figure 7A illustrates a system 700 for delivery of thermal energy in accordance with another embodiment of the present invention. Figure 7B illustrates a method 750 for delivery of thermal energy, in accordance with another embodiment of the present invention. As shown in Figures 7A and 7B, the flue gases generated in the combustion chamber 104 are not transferred to the fluid mixer 106 to become a part of the fluid medium. Instead, the fluid medium is heated by the flue gases through an external heater 714. In various embodiments, the external heater 714 may be a heat exchanger of one of, but not limited to, pipe in pipe, shell and tube, coil type and fin-tube type etc. The same argument may be applied to other heat exchangers used in the present invention for all other purposes enlisted in this specification.

This system 700 is particularly suitable in scenarios where solid fuels, such as coal, are used for combustion. Since the flue gases will possibly contain a large amount of ash content, it is not desirable to use the highly polluted flue gases as the part of the fluid medium. At step 752, the one or more of the air and the fuel from the pre-heater 102 are received in the combustion chamber 104 and the fuel is combusted to generate heat energy in form of the flue gases. A pressure enhancing chamber 710 is connected downstream of the combustion chamber 104.

At step 754, the pressure enhancing chamber 710 receives the pressure enhancing fluid, from the external source, for increasing the pressure of the flue gases. Further, a part of the flue gases may be pressurized by a second booster 708 and the pressurized flue gases may be used to atomize the pressure enhancing fluid during the introduction of the pressure enhancing fluid into the pressure enhancing chamber 710. The scheme for atomization used here may be drawn in parallel with the one depicted in figure 3B, with the difference being that here, the pressurized flue gases are being used as atomization fluid. Downstream of the pressure enhancing chamber 710 is connected the external heater 714.

At step 756, the external heater 714 transfers the heat energy of the flue gases to the fluid medium circulating in the closed loop 115. In such a case, the fluid medium may be a mixture of the pressure enhancing fluid and at least a first fluid, such as air or gaseous CO2, pumped into the closed loop 115. Downstream of the external heater 714 is connected a second surge vessel 716. Further, the combustion chamber 104 is connected downstream of the second surge vessel 716. The combustion chamber 104, the pressure enhancing chamber 710, the external heater 714 and the second surge vessel 716 together form a second closed loop 715 for the flue gases to operate in.

At step 758, the physical and the chemical parameters associated with the fluid medium are controlled in the fluid mixer 106, by receiving the pressure enhancing fluid and vaporizing the pressure enhancing fluid. The pressure enhancing fluid vaporizes on receiving heat from the fluid medium. At step 760, at least a part of heat energy of the fluid medium is transferred to a process fluid, in the heat exchanger 108.

At step 762, the surge vessel 110 receives the fluid medium from the heat exchanger 108 and discharges the fluid medium to one or more of the fluid mixer 106 and the pre-heater 102. At step 764, the second surge vessel 716 receives the flue gases from the second closed loop 715 and discharges excess flue gases to the pre-heater 102. The excess flue gases may pre-heat the one or more of the fuel and the air in the pre-heater 102. Additional inline filters 706 and 712 may be deployed in the second closed loop 715 to ensure sufficient removal of pollutants from the generated flue gases, in order to ensure that the equipment of the second closed loop 715 are able to maintain intended durability. Additional control valves 718 and pumps may also be deployed wherever required in the system 100. From the pre-heater 102, the excess flue gases may further be discharged to the atmosphere through the vent gas treatment system 130.

Figure 7C illustrates the system 700 for delivery of thermal energy in accordance with yet another embodiment of the present invention. Here a second pressure enhancing fluid is being introduced into the pressure enhancing chamber 710, instead of the pressure enhancing fluid fed to the fluid mixer 106. This is due to the fact that, the fluid medium may have a different composition from the flue gases generated in the combustion chamber 104. For example, the fluid medium may be CO2. In that scenario, a suitable choice for the pressure enhancing fluid would be liquefied CO2. However, a suitable choice for the second pressure enhancing fluid (for mixing with the flue gases) would rather be water.

Figure 8 illustrates the system 100 for delivery of thermal energy in accordance with yet another embodiment of the present invention. Here a heat storage device 802 has been provided. The heat storage device 802 stores heat energy of the fluid medium using a high heat capacity material. The embodiment 800 is applicable in a number of applications such as hot oil generator, hot water generator (re-circulation and once through), hot air generator (re-circulation and once through), district heating, space heating, steam generator/ boiler (once through and re-circulation), distillation columns, crude oil heaters, process heaters, reactor heating, cooking (ovens/stoves) for domestic, industrial and commercial applications and incinerators (solid, liquid and gaseous waste). Figure 9A illustrates a system 900 for heating steam as a process fluid.

Figure 9B illustrates a method 950 for heating steam as a process fluid. As shown in Figures 9A and 9B, low pressure and low temperature flow of a main stream of steam is being fed to a flow splitter 902.

At step 952, the flow splitter 902 divides the main stream of the steam into a first stream and a second stream. At step 954, the first stream is pressurized by a steam booster 904 and fed to the heat exchanger 108. At step 956, the pressurized first stream is heated in the heat exchanger 108 on receiving heat energy from the fluid medium. At step 958, the second stream is made to pass through a water pre-heater 912, where the second stream preheats a water stream being pumped from a tank 914. A portion of the first stream leaving the heat exchanger 108 at the process fluid outlet 114 is pressurized and the pressurized portion of the first stream is used to atomize the pre-heated water stream. The scheme for atomization used here may be drawn in parallel with the one depicted in figure 3B, with the difference being that here, pressurized first stream is being used as the atomization fluid.

At step 960, the atomized water stream is introduced to the first stream in a pressure booster 906, in order to increase a pressure of the first stream by mixing the pre-heated water stream in atomized form. Hence steam at high pressure and high temperature is obtained in the form of the first stream. High temperature and high pressure here could be of any value as per the requirements of the process. It will be appreciated by a person skilled in the art that multiple main streams may be fed to the flow splitter for heating and pressurizing by the system 100, in a similar manner as the main stream described above.

Figure 10 illustrates the system 700 for delivery of thermal energy in accordance with yet another embodiment of the present invention. Here again heat storage device 802 has been introduced downstream of the fluid mixer 106, in the embodiment of figure 7. Figure 11 illustrates the system 700 for delivery of thermal energy in accordance with yet another embodiment of the present invention. This figure illustrates implementation of direct contact heating to embodiment of figure 7.

Various modifications to these embodiments are apparent to those skilled in the art from the description. The principles associated with the various embodiments described herein may be applied to other embodiments. Therefore, the description is not intended to be limited to the embodiments but is to be providing broadest scope consistent with the principles and the novel and inventive features disclosed or suggested herein. Accordingly, the invention is anticipated to hold on to all other such alternatives, modifications, and variations that fall within the scope of the present invention.