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Title:
CRYOGENIC FLUID COMPRESSOR DRIVEN BY A GAS COMBUSTION ENGINE
Document Type and Number:
WIPO Patent Application WO/2019/086283
Kind Code:
A9
Abstract:
The invention provides a compressor unit for cryogenic applications comprising: at least one compressor for cryogenic applications for compressing a working fluid; a mechanically coupled to the at least one compressor; a combustion gas inlet fluidically coupled to the gas combustion engine for providing fuel to the motor; wherein the gas combustion engine is controlled to adjust compressor operation.

Inventors:
KNOCHE, Martin (Schonenwerdstr. 109, 8620 Wetzikon, 8620, CH)
Application Number:
EP2018/078858
Publication Date:
August 15, 2019
Filing Date:
October 22, 2018
Export Citation:
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Assignee:
LINDE AKTIENGESELLSCHAFT (Klosterhofstrasse 1, Munich, 80331, DE)
International Classes:
F04D7/00; F04B15/08; F04D23/00
Attorney, Agent or Firm:
RICHMOND, Sarah (The Preistley Centre, 10 Priestley Road the Surrey Research Park, Guildford Surrey GU2 7XY, GU2 7XY, GB)
Download PDF:
Claims:

Claims

1. A compressor unit for cryogenic applications comprising:

at least one compressor for cryogenic applications for compressing a working fluid;

a gas combustion engine mechanically coupled to the at least one compressor;

a combustion gas inlet fluidically coupled to the gas combustion engine for providing fuel to the motor;

wherein the gas combustion engine is controlled to adjust compressor operation.

2. The compressor unit according to claim 1, further comprising a controller configured to control the gas motor, thereby controlling the operation of the at least one compressor.

3. The compressor unit according to claim 1 or claim 2, further comprising an inlet line coupled to the combustion gas inlet, and a valve is provided in the inlet line;

wherein the flow through the valve is controlled so as to adjust the flow of combustibles into the motor.

4. The compressor unit according to any of the preceding claims, wherein the gas combustion engine and the compressor are aligned on the same axis.

5. The compressor unit according to any of the preceding claims, wherein the working fluid is helium, neon or hydrogen; and wherein the compressor is hermetically sealed in order to minimize loss of the working fluid

6. A cryogenic system for cryogenically cooling a working fluid comprising:

a compressor unit according to any of claims 1 to 3, and a cryogenic cold box;

a first flow line for conveying the working fluid from the coldbox to the compressor unit, and a second flow line for conveying compressed working fluid to the coldbox.

7. A cryogenic system according to claim 5, wherein the working fluid is helium, neon or hydrogen or a mixture thereof.

8. Method of compressing a cryogenic fluid comprising,

- feeding a working fluid into the compressor;

- providing a flow of a combustion fuel gas to a gas combustion engine which is mechanically coupled to a compressor for cryogenic applications;

- outputting the power generated by the engine to the compressor in order to compress the working fluid; and

- controlling the gas combustion engine in order to adjust the compressor operation.

9. The method according to claim 8, wherein the step of controlling the gas combustion engine comprises controlling one or more operational parameters of the engine

10. The method according to claim 8 or claim 9, wherein step of controlling the gas combustion engine comprises controlling the flow of fuel to the gas combustion engine.

1 1 . The method according to any of claims to 10, wherein the working fluid is helium, neon or hydrogen or a mixture thereof.

Description:
CRYOGENIC FLUID COMPRESSOR DRIVEN BY A GAS COMBUSTION ENGINE

Field of Invention

The present invention relates to compressor units for cryogenic applications.

Background of Invention

Compressor units for compressing low temperature fluids are known. In particular, compressor units for cryogenic applications, i.e. for compressing cryogenic fluids are known.

The term "cryogenic fluid" is understood in the following to refer to so-called deep cold fluids, in particular liquid hydrogen, liquid helium, liquefied natural gas, liquid nitrogen, liquid oxygen and other liquefied gases and possible mixtures thereof (Nelium)

Compressor units used in low-temperature, and cryogenic, applications are generally driven by electrical engines. This type of arrangement is shown in Figure la. The arrangement includes a compressor a, an electrical motor b, a cryogenic coldbox c and use/storage of the working fluid d, such as a cryogenic experiment or storage tank. Such units require large amounts of electricalenergy, which due to the continually rising unit price of electricity, means that they are costly to run. There are also cases, where the required electrical energy is not available at the required low voltage and an extra investment for a new transformer station would be required.

Further, the operation of such compressor units has to be controlled in order to adapt to different loads. This can be done by either a variation of the pressure ratio or varying the compressor speed. Generally, with an electrically driven compressor unit, the compressor speed is varied to provide part load operation with one or more frequency converters. This is shown in Figure la in which components similar to those in Figure la are given similar references and a frequency converter e’ is provided.

Embodiments of the invention seek to improve on the performance of existing compressors and solve some or all of the problems with known solutions.

Summary of Invention According to the first aspect of the present invention there is provided a compressor unit for cryogenic applications comprising: at least one compressor for cryogenic applications for compressing a working (refrigerant) fluid; a mechanically coupled to the at least one compressor; a combustion gas inlet fluidically coupled to the gas combustion engine for providing fuel to the motor; wherein the gas combustion engine is controlled to adjust compressor operation.

The compressor unit may comprise a controller configured to control the gas motor, thereby controlling the operation of the at least one compressor.

The controller may be configured to control to adjust the flow of combustion gas into the combustion engine. The controller may control the flow of combustibles to the gas inlet. The controller may be configured to control one or more operational parameters of the combustion engine. A sensor may also be provided in line to provide data to the controller. Further sensors may be provided in the combustion engine feeding operational data to the controller.

The compressor unit may comprise an inlet line coupled to the combustion gas inlet, and a valve is provided in the inlet line. The flow through the valve may be controlled so as to adjust the flow of combustibles into the motor.

The controller may be configured to control the combustion gas inlet valve.

The gas combustion engine and the compressor may be aligned on the same axis.

The working fluid may be helium, neon or hydrogen or a mixture thereof. The compressor may be hermetically sealed in order to minimize loss of the working fluid

The compressor may comprise a sealing arrangement for preventing internal backflow of light gases. The compressor may be a screw compressor. In a reciprocating compressor the sealing arrangement may be piston rings. The compressor may be provided with means for prevention of overheating, such as additional cooling systems and/or a reduced pressure ratio. The compressor may comprise a suction flange which permits a recycle operation. The compressor may be made from material which in use, can withstand low-temperature (or cryogenic temperature) operating fluid flow. An ionic liquid may be used to further improve the compressor performance with gases of low viscosity. According to a further aspect of the invention, there is provided A cryogenic system for cryogenically cooling a working fluid comprising: a compressor unit as described above, a cryogenic cold box; a first flow line for conveying the working fluid from the coldbox to the compressor unit, and a second flow line for conveying compressed working fluid to the coldbox.

The working (refrigerating) fluid may be helium, neon or hydrogen or a mixture thereof.

The combustion gas may be provided from a source of landfill gas. The combustion gas may be provided from a source of flare gas.

According to a further aspect of the invention, there is provided a method of compressing a cryogenic fluid comprising: feeding a working (refrigerant) fluid into the compressor; providing a flow of a combustion fuel to a gas combustion engine which is mechanically coupled to a compressor for cryogenic applications; outputting the power generated by the engine to the compressor in order to compress the working fluid; and controlling the gas combustion engine in order to adjust the compressor operation

The step of controlling the gas combustion engine may comprise controlling one or more operational parameters of the engine

The step of controlling the gas combustion engine may be performed by a controller. The method may comprise receiving input signals from the engine and/or the compressor.

The step of controlling the gas combustion engine may comprise controlling the flow of fuel to the gas combustion engine.

The working fluid may be helium, neon or hydrogen or a mixture of these.

The combustion gas may be provided from a source of landfill gas. The combustion gas may be provided from a source of flare gas.

The method may include feeding an exhaust flow from the engine for further use. Such use is generation of (high) pressure steam and/or heat, which may be combined with the heat removal of the compressor. The method may include providing the working fluid from a source of landfill gas. The method may include providing the working fluid from a source of flare gas. According to a further example, a steam or water turbine could also provide the required energy for the compressor in the compressor unit.

Whilst the invention has been described above, it extends to any inventive combination of features set out above or in the following description or drawings.

Brief Description of the Drawings

Figures la and lb show schematic representations of conventional compressor units;

Figure 2 is a schematic view of a compressor unit for cryogenic applications according to an embodiment of the invention; and

Figure 3 shows the compressor unit of figure 2 in a cryogenic cooling cycle.

Specific embodiments of the invention will now be described in detail by way of example only and with reference to the accompanying drawings in which:

Detailed description

FIG. 2 shows a compressor unit for cryogenic applications according to an embodiment of the invention. The compressor unit 1 comprises a gas combustion engine 30 (also referred to as a gas motor) and a compressor 10 and a controller 40. The unit includes flow lines 11 , 12, 31 , 32.

The compressor 10 is configured for cryogenic applications, i.e. for compressing a cryogenic working fluid. The compressor 10 is sealed to the atmosphere (hermetically sealed) in order not to lose any expensive working fluid. The working fluid may be helium, neon or hydrogen (for regulatory reasons, e.g. ATEX). The compressor 10 includes a flow path (not shown) from rotor(s) to stator(s). When a light gas (He / Ne / H2) is used as the working fluid, the compressor flow path is provided with a sealing arrangement in order to prevent internal backflow of the light gas. In a screw compressor, the sealing arrangement may be for example flooding. In a reciprocating compressor the sealing arrangement may be for example piston rings.

If the working fluid comprises a single atom gas (He / Ne), the compressor 10 is configured to prevent overheating during the required relatively high compression of the working fluid. Prevention of overheating may be achieved by additional cooling systems and/or a reduced pressure ratio . The compressor 10 is provided with a suction flange which permits a recycle operation. The compressor 10 is made from material which in use, can withstand low- temperature (or cryogenic temperature) operating fluid flow. In particular, when hydrogen is provided as a working fluid, the compressor 10 is made from a material which can withstand H2- embrittlement.

The combustion engine 30 is mechanically coupled 33 to the compressor 10. In this

embodiment, it can be seen that the combustion engine is aligned on the same axis A as the compressor 10. The mechanical coupling is typically with a feather key, which breaks upon overload to protect the engine. However, it will be appreciated that alternative configurations of the engine and the compressor can be realized and are included within the scope of this invention. A combustion gas is fed through line 31 into the combustion engine 30 and an exhaust gas is fed from the gas combustion engine 30 through line 32. Valve 3la and 32a are provided in the flow lines.

The controller 40 is configured so as to control the gas engine 30, thereby adjusting speed and/or performance of the compressor 10. The controller 40 is configured to control 41 the valve 3la so as to adjust the flow of combustion gas into the combustion engine 30. The controller 40 is configured to control 42 one or more operational parameters of the combustion engine 30. A sensor (not shown) may also be provided in line 31 to provide data. Further sensors may be provided in the combustion engine feeding operational data to the controller (not shown in the Figures).

It will be appreciated that valves may also be provided in the other flow lines 32, 11 and 12, and these other valves may be controlled by the controller.

Figure 3 shows the compressor unit 1 of figure 2 (indicated with a dashed line) within a cryogenic cooling cycle comprising a cryogenic coldbox 50 and a cryogenic fluid usage/storage 60, such as a cryogenic storage vessel or a cryogenic experiment. A working fluid flows from the coldbox 50 through line 1 1 into the compressor 10 to be compressed. A compressed working fluid flows from the compressor 10 through line 12 back in to the coldbox 50. A compressed cooled flow is directed through line 52 to be used or stored 50. A return flow can be fed through line 51 back into the coldbox 50.

The combustion gas fed into the combustion engine may come from any suitable source. For example, the combustion gas can be provided from a stored gas source or can be piped directly from a gas processing plant.

In a preferred embodiment, the combustion gas flow is a so-called“dump gas”. Waste deposits, such as land fill containing compostable mater and/or food waste generate gases during decomposition. The decomposition gasses include a significant amount of methane, and also carbon dioxide, sulfurous compounds (H2S) and other contaminants. This is referred to as landfill gas or dump gas. This landfill gas can be collected, particularly when the waste is covered (for example to prevent foul odours) then the developing gases are collected and typically contain a significant amount. Untreated landfill gas is unsuitable for the supply for the natural gas network, and is often flared or converted to electricity. Being a waste product, landfill gas is low cost, and therefore the implementation of a landfill gas combustion engine powered compressor unit is very economical.

In another preferred embodiment, the combustion gas flow is a so-called“flare gas”, which is a by-product from the processing of crude oils. Often the quantity of waste or flare gas obtained during the processing of crude oil is not large enough to be economically exploited and they were simply flared. However, in some parts of the world (such as in the EU), flaring of this waste gas is prohibited. Therefore, the waste gas (or flare gas) is used to produce energy, for example converted into electrical energy. Flare gas is available at very low cost, and therefore the implementation of a flare gas combustion engine powered compressor unit is very economical.

The exhaust gas flow 32 can be conveyed for further use, for example used for some or all of the following: (high pressure) steam generation, for heating applications i.e. heating of

commercial/residential buildings, greenhouses or fish ponds.

In another embodiment (not show), the combustion engine is also used to provide a mechanical drive for another application. The compressor unit of the invention can be operated with lower energy costs as compared to conventional arrangements. Further, the speed and performance of the compressor unit of the invention can be more easily and accurately controlled.

The invention has been described above with reference to one or more preferred embodiments. It will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.