Compression system and method with gas leak recovery and fuel cell

Abstract

The compression system (1) includes a compressor (3) with a sealing device including at least one gas seal (19; 61). A gas leakage recovery line (23) is adapted to recover process gas leakage from the at least one gas seal (19; 61). A fuel cell device (25) is fluidly coupled to the gas leakage recovery line (23). The fuel cell device (25) is adapted to process the gas leakage and generate power therefrom.

Description

[Technical field]

[0001] The present disclosure relates to compression systems for processing gases such as (but not exclusively) hydrogen. The embodiments disclosed herein relate specifically to compression systems with gas leakage recovery. [Background technology]

[0002] When gas is processed in a compressor, gas leakage through sealing devices cannot be completely avoided: a certain amount of process gas inevitably leaks through seals around the rotating shaft of a dynamic compressor (e.g., a centrifugal or axial compressor) or through seal packings located around the piston rod in a reciprocating compressor.

[0003] In some cases, gas leaks are captured and burned in a flare to prevent dispersion to the environment. This typically occurs when the process gas is a hydrocarbon such as methane. In some cases, gas leaks are captured and recirculated back to the compressor suction to prevent loss of valuable gas.

[0004] When the process gas is hydrogen, such as in a green ammonia production plant or refining process, hydrogen leaking past compressor seals is released into the atmosphere, since hydrogen does not have a negative impact on the environment. Although this does not raise concerns from an environmental impact perspective, releasing hydrogen into the atmosphere nevertheless represents a significant loss in terms of money and energy, considering the amount of power required to produce hydrogen from other fluids, for example from water by electrolysis. Summary of the Invention [Problem to be solved by the invention]

[0005] It would therefore be beneficial to provide a more efficient means for preventing or reducing the release of valuable process gases into the environment or their combustion in flares.

[0006] According to one aspect, disclosed herein is a compression system including a compressor with a sealing device including at least one gas seal, a gas leakage recovery line adapted to recover leakage of process gas from the at least one gas seal, and a fuel cell device fluidly coupled to the gas leakage recovery line and adapted to process the recovered leakage of process gas and generate power therefrom.

[0007] Hydrogen or other valuable process gas leaking from the seal is recovered and used as fuel in a fuel cell to generate power. The disclosed compression system is particularly advantageous when the process gas is hydrogen. In such cases, with current technology, hydrogen leaking from the compressor is released into the environment, but in the novel system disclosed herein, the hydrogen is used directly as fuel for a fuel cell device. Similar advantages are achieved when the leak contains an inert gas such as nitrogen, which is often used as a separation gas.

[0008] According to another aspect, a method of operating a gas compression system is disclosed herein, the method including compressing a process gas in a compressor having a sealing device, recovering leakage of the process gas from the sealing device, directing the recovered leakage of the process gas towards a fuel cell device, and generating power in the fuel cell device using the recovered leakage of the process gas.

[0009] Further features and embodiments of the systems and methods according to the present disclosure are set forth in the following description, with reference to the accompanying drawings, and in the appended claims. [Brief description of the drawings]

[0010] Reference will now be made briefly to the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic diagram of an embodiment of a system according to the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram of a further embodiment of a system according to the present disclosure. [Diagram 3] FIG. 3 is a schematic diagram of yet another embodiment of a system according to the present disclosure. [Figure 4] FIG. 4 shows a flow chart summarizing an embodiment of a method according to the present disclosure. [Diagram 5] FIG. 5 shows a flow chart summarizing an embodiment of a method according to the present disclosure. [Figure 6] FIG. 6 is a schematic diagram of yet another embodiment of a system according to the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Briefly, to improve the energy efficiency of the compression system, process gas leaking from the compressor seals is collected and used as is or after conversion in a fuel cell device to generate electricity. If the process gas contains hydrogen, the hydrogen can be used directly as fuel in the fuel cell. The chemical energy contained in the hydrogen is converted to thermal and electrical energy, which is made available to drive the compressor or is sent to a local utility or power grid. Valuable process gas, such as hydrogen, leaking from the compressor is used to generate useful electricity, thus improving the energy efficiency of the compression system.

[0012] Referring now to the drawings, Figure 1 shows a schematic diagram of a first compression system 1 according to the present disclosure. The system 1 includes at least one compressor 3 having a suction side 3A and a delivery side 3B. Process gas is supplied to the suction side 3A of the compressor 3 through an inlet line 5 and delivered from the delivery side 3B through an outlet line 7.

[0013] 1, the compressor 3 is a centrifugal compressor including a rotor having a rotatable shaft 9 and a number of impellers 11 rotating about an axis of rotation AA. The compressor 3 may be driven by a drive device 13, such as an electric motor. In other embodiments, the drive device 13 may be a gas turbine engine or a steam turbine.

[0014] The rotating shaft 9 is supported within the casing 15 by bearings 17. A sealing arrangement seals the rotating shaft to prevent or reduce leakage of process gas along the rotating shaft 9 to the bearings 17 and from there to the environment. In the embodiment of Figure 1, the sealing arrangement includes rotary seals 19 on both ends of the shaft 9. In some embodiments, the seals 19 can be dry gas seals that are supplied with a separation gas, e.g., nitrogen, through a separation gas supply line 21.

[0015] The seal 19 is fluidly coupled to a gas leakage collection line 23 adapted to collect process gas leaking from the seal 19. When separation gas is supplied to the seal 19, a mixture of the leaked process gas and separation gas is collected through the gas leakage collection line 23.

[0016] The gas leakage recovery line 23 fluidly couples the seal 19 to a fuel cell device 25 adapted to generate power using process gas leaked from the compressor 3. The fuel cell device 25 may include a scrubbing system 27 adapted to remove oil and / or other contaminants contained in the gas stream collected by the gas leakage recovery line 23 before it reaches the fuel cell 29. In some embodiments, a booster compressor 31 may be provided along the gas leakage recovery line 23 to deliver the collected gas leakage at the required pressure to the fuel cell 29. Reference number 33 indicates a driver for the booster compressor 31. In some embodiments, a control valve 34 along the gas leakage recovery line 23 may be used to close the gas leakage recovery line 23 as needed, for example when the fuel cell device 25 is unavailable. A gas leakage discharge line 36 fluidly coupled to a flare or vent 38 may be selectively opened by a control valve 40 when the fuel cell device 25 is unavailable.

[0017] The fuel cell 29 may include any type of fuel cell adapted to convert the chemical energy of a fuel and an oxidant into electricity through a pair of oxidation-reduction reactions. The fuel cell 29 may be selected based on the properties of the process gas and separation gas (if any) delivered to the fuel cell system 25 from the compressor 3.

[0018] Typically, the gas processed by compressor 3 comprises hydrogen and the separated gas comprises nitrogen. High temperature fuel cells, such as solid oxide fuel cells, may be used to generate electricity via the following reaction: Anode reaction 2H 2 +2O 2- →2H 2 O+4e - Cathodic reaction: O 2 +4e - →2O 2- Total reaction: 2H 2 +O 2 →2H 2 O

[0019] The oxidant may be oxygen or a gas mixture containing oxygen, such as air. Inert components contained in the inert separator gas (such as nitrogen) as well as air used as an oxidant source are present in the gas stream flowing through the fuel cell but do not interfere with the chemical reactions described above.

[0020] Depending on the composition and flow rate of the leak gas, as well as other parameters of the system, various fuel cells can be used in the fuel cell device 25. Non-limiting examples include the following types of fuel cells: metal hydride fuel cells, electrogalvanic fuel cells, direct formic acid fuel cells (DFAFC), zinc-air cells, microbial fuel cells, up-flow microbial fuel cells (UMFC), regenerative fuel cells, direct borohydride fuel cells, alkaline fuel cells, direct methanol fuel cells, reformed methanol fuel cells, direct ethanol fuel cells, proton exchange membrane fuel cells, redox fuel cells (RFC), phosphoric acid fuel cells, solid acid fuel cells, molten carbonate fuel cells, solid oxide fuel cells (TOFC), protonic ceramic fuel cells, direct carbon fuel cells, planar solid oxide fuel cells, enzymatic biofuel cells, and magnesium-air fuel cells.

[0021] In some embodiments, the fuel cell system 25 may be further improved by providing a heat exchanger 37 adapted to recover heat from the fuel cell 29 and deliver recovered thermal energy Q to a utility, indicated generally at 39.

[0022] In FIG. 1 , a single compressor 3 is shown in combination with the fuel cell device 25, however, it should be understood that multiple compressors 3 can be fluidly coupled to the fuel cell device 25 such that process gas leakage from multiple compressors is processed by the same fuel cell device 25 to generate electrical power.

[0023] Additionally, leakage gas collection systems may be placed in the modules to increase system availability and manage leakage flow variations due to seal wear.

[0024] The power generated by the fuel cell 29 is direct current voltage power and is intended to be converted to alternating current voltage power in a DC / AC converter 41. The direct current voltage power from the DC / AC converter may be used to directly power one or more electric motors of the compression system 1 or other auxiliary devices or utilities, and / or may be delivered to a power distribution grid 43 for distribution to other users.

[0025] In some embodiments, the compression system 1 can include a fuel gas integration line 45 adapted to supply an additional flow of process gas to the fuel cell device 25, for example, when the gas leakage collected by the gas leakage collection line 23 is insufficient to operate the fuel cell device 25. The fuel gas integration line 45 can be fluidly coupled, for example, to the inlet line 5, the outlet line 7, or an intermediate compressor stage of the compressor 3. In the schematic diagram of FIG. 1, the fuel gas integration line 45 is fluidly coupled to the inlet line 5 of the compressor 3.

[0026] A control valve 47 may be provided to control the flow rate of process gas supplied to the fuel cell system 25 through the fuel gas integration line 45. In some embodiments, the control valve 47 may be operatively coupled to a control unit 48, which is further operatively coupled to the control valves 34 and 40 described above.

[0027] The control unit 48 may be adapted to detect one or more parameters useful for controlling the amount of process gas required through the fuel gas integration line 45. For example, the control unit 48 may be operatively coupled to a flow meter 49 adapted to detect the flow rate of the leak of process gas collected through the gas leak recovery line 23 and configured to regulate the flow of additional process gas towards the fuel cell device 25. The control unit 48 may also be operatively coupled to the fuel cell device 25 and control its operation, such as by-passing the fuel cell device 25 by closing the control valve 34 and opening the control valve 40 in the event of a fuel cell being unavailable. This allows for continuous operation of the compression system 1 even if the fuel cell device 25 is temporarily shut down.

[0028] In some embodiments, the control unit 48 may also be operatively coupled to a current sensor 50 or to additional sensor devices that may be adapted to detect the amount of DC current generated by the fuel cell device 25, the voltage / current characteristic curve of the fuel cell device 25, or other parameters. In other embodiments, the current sensor 50 may be disposed on the AC current line and detect the AC current from the DC / AC converter.

[0029] Thus, the control unit 48 may be adapted to provide information / monitoring regarding the amount of power generated by the fuel cell device 35 and / or to issue a warning if the power generated by the fuel cell device 25 is higher than a threshold value. Since the amount of power generated by the fuel cell device 25 is a function of the gas leakage flow rate, high power values ​​may indicate failure or excessive wear of the sealing device. Monitoring and detection of seal wear / failure may be further managed by integrated control of the FC operating voltage / current characteristic curve versus expected seal leakage.

[0030] With continuing reference to Figure 1, reference is now made to Figure 2, which illustrates a further embodiment of a compression system 1 according to the present disclosure. The same reference numbers indicate the same or similar components or parts of the system, which will not be described again. The compression system 1 of Figure 2 differs from the compression system 1 of Figure 1 primarily in that the compressor 3 is a positive displacement compressor, such as a reciprocating compressor, rather than a dynamic (e.g., centrifugal) compressor.

[0031] The reciprocating compressor 1 of Figure 2 includes a cylinder 51 housing a piston 53 that reciprocates within the cylinder 51. The piston 53 is drivingly connected to a crankshaft 55 via a connecting rod 56, a crosshead 57 and a piston rod 59. A gas sealing device including a gas seal packing 61 seals the cylinder 51 and reduces process gas leaking from the reciprocating compressor.

[0032] The gas leakage recovery line 23 collects the process gas leaking through the gas seal packing 61 and delivers the recovered process gas leakage to the fuel cell device 25 .

[0033] In some embodiments, reciprocating compressor(s) and dynamic compressor(s) may be used in combination in the same compression system.

[0034] Fuel cells typically use hydrogen as the fuel gas, so the above-described arrangement is particularly beneficial when combined with a compression system where the process gas is hydrogen or a gas mixture containing hydrogen. Typically, a centrifugal hydrogen compressor may have a hydrogen leak rate of 0.5-5 kg / h through a rotating seal around the compressor shaft. Hydrogen leak rates in individual reciprocating compressors may range from 5-50 kg / h. Recovering hydrogen leakage may result in potential recoverable power in the range of 10-100 kWe for centrifugal compressors and 100-1000 kWe for reciprocating compressors.

[0035] As mentioned above, fuel cells typically use hydrogen as a fuel gas and therefore the combination of a fuel cell and a hydrogen compressor is particularly beneficial as process gas leaking from the compressor can be used directly as fuel gas in the fuel cell system.

[0036] However, fuel cells for recovering energy from leaking recovered process gas can also be used when the process gas cannot be used directly as fuel in the fuel cell device. In such a situation, the leaking process gas can be converted in a conversion unit into a usable fuel gas for the fuel cell device, in particular into a gas mixture containing hydrogen. In some embodiments, this conversion can be integrated into the fuel cell.

[0037] For example, if the process gas is methane (CH 4 If the leaking process gas is a hydrocarbon (CxHy) such as toluene, the leaking process gas may be at least partially converted to hydrogen by, for example, steam reforming, water / gas shift, partial oxidation, or any other suitable conversion process.

[0038] By way of example, Figure 3 shows a schematic diagram of an embodiment of a compression system 1 similar to the systems of Figure 1 or Figure 2. The same reference numbers indicate the same components and parts of the system of Figure 1, which will not be described again.

[0039] The system 1 of Figure 3 differs from the systems of Figures 1 and 2 mainly in that a conversion unit 71 is disposed along the gas leakage recovery line 23. The compressor 3 (shown in Figure 3 as a centrifugal compressor, but which may be a reciprocating compressor as shown in Figure 2) may process methane or another hydrocarbon or mixture of hydrocarbons. The conversion unit 71 is adapted to at least partially convert process gas leaking from the compressor 3 into hydrogen or a mixture containing hydrogen, or generally into a gas species adapted to be used as a fuel in the fuel cell device 25.

[0040] Fig. 4 shows a flow chart summarizing a method of operating the compression system 1 according to the present disclosure. The flow chart in Fig. 4 shows a method in which the recovered process gas leakage is directly used as fuel gas in a fuel cell device 25. The method includes the steps of compressing the process gas in a compressor (step 101), recovering the gas leakage from a sealing device of the compressor 3 (step 102), sending the recovered gas leakage to the fuel cell device 25 (step 103), and generating electrical energy from the gas leakage in the fuel cell device 25 (step 104).

[0041] Figure 5 shows a flow chart of a similar method in which the gas processed by the compressor 3 does not contain hydrogen and is at least partially converted to a gas stream containing hydrogen, and then the converted gas stream is delivered to a fuel cell device as a fuel gas. The method of Figure 5 includes the following steps: compressing the process gas in the compressor 3 (step 105), recovering the gas leakage from the sealing device of the compressor 3 (step 106), chemically converting at least a portion of the process gas leakage from the sealing device to a different gas species suitable as a fuel for the fuel cell device (step 107), delivering the converted gas leakage to the fuel cell device (step 108), and finally generating electrical energy from the converted gas leakage in the fuel cell device 25 (step 109). Generally speaking, any process gas that can be converted to hydrogen (especially any hydrocarbon) can be used to recover electrical power by adding a fuel processing system.

[0042] If a separation gas such as nitrogen is used in the compressor seals to maximize the efficiency of the fuel cell, a reduction of the separation gas in the hydrogen / separation gas recovered from the seals would be beneficial. In leakage from centrifugal compressors, the hydrogen content is usually in the range of 20-60%, while in reciprocating compressors, the proportion of hydrogen is about 95% or more, the rest being separation gas. To reduce the amount of separation gas in reciprocating compressors, it can be foreseen to control the pressure in the separation gas buffer system and to reduce the leakage of separation gas towards the crankcase. In centrifugal compressors, for example, abradable labyrinth seals can be used to minimize the leakage of separation gas.

[0043] With continued reference to Figures 1-5, a further embodiment of a system according to the present disclosure is shown in Figure 6. The same reference numbers have been used in Figure 6 to indicate the same or corresponding elements shown in Figures 1-3, which will not be described again in detail.

[0044] The embodiment of FIG. 6 includes a heat transfer system that removes waste heat generated by the fuel cell device 29 and uses the waste heat to provide cooling capacity that is utilized to improve the efficiency of compression and / or reduce the number of compression stages required and the cost, size, and complexity of the compression system.

[0045] In the embodiment of Figure 6, a heat transfer system 80 is provided that includes a heat exchanger 37 in combination with the fuel cell arrangement 29 for removing waste heat from the fuel cell arrangement 29. The heat exchanger 37 is fluidly coupled to a first heat transfer loop 81, which may include a circulation pump 83. The first heat transfer loop 81 is adapted to transfer waste heat recovered from the fuel cell arrangement 29 to an absorption refrigeration cycle, indicated generally at 85.

[0046] The cooling capacity of the absorption refrigeration cycle is used to increase the efficiency of the compressor 3. For example, the cooling capacity of the absorption refrigeration cycle 85 can be used to reduce the temperature of the process gas upstream of the compressor 3 so that the density of the process gas is increased. Alternatively, or in combination, this cooling capacity can be used in an intercooler, i.e. a heat exchanger that removes heat from the process gas between two successive compression steps.

[0047] FIG. 6 shows a compressor 3 including a first compression unit 3.1 and a second compression unit 3.2 arranged sequentially along the flow path of the process gas. The discharge side of the first compression unit 3.1 is fluidly coupled with the suction side of the second compression unit 3.2. The compressor 3 is only shown diagrammatically in FIG. 6 and can be any type of compressor suitable for a particular application, depending on the nature of the process gas, the flow rate, the compression ratio, etc. For example, the compressor 3 can be a dynamic compressor, such as a centrifugal compressor, or a positive displacement compressor, such as a reciprocating compressor. In FIG. 6, the compressor 3 is represented as including a first compression unit 3.1 and a second compression unit 3.2. The compressor 3 can be, for example, a centrifugal compressor having a first compressor section and a second compressor section housed in the same casing, the compressor section featuring a first compression unit and a second compression unit.

[0048] In other embodiments, compressor 3 may include separate compressors connected in series and representing a first compression unit and a second compression unit.

[0049] In another embodiment, the compressor 3 may be a reciprocating compressor including two stages in series characterized by a first compression unit and a second compression unit.

[0050] Regardless of the structure and nature of the compressor 3, an intercooler 87 is arranged between the first compression unit 3.1 and the second compression unit 3.2. The partially compressed process gas in the first compression unit 3.1 flows through the intercooler 87 before entering the second compression unit 3.2. Thus, the temperature of the partially compressed process gas is reduced and its density is increased before the next compression step.

[0051] In the embodiment of FIG. 6, the intercooler 87 comprises two sections arranged in series along a flow path: cooler 87.1 and cooler 87.2. The cooler 87.1 may be a gas / air cooler, or a gas / water cooler, etc., and may be configured to bring the temperature of the process gas close to the ambient temperature. The cooler 87.2 may be configured to bring the temperature of the process gas below the ambient temperature. The cooling medium in the cooler 87.2 may be the heat transfer fluid of a coolant circuit 90 including a second heat transfer loop 91 in which the coolant circulates. A circulation pump 93 may be provided to circulate the coolant in the second heat transfer loop 91. The second heat transfer loop 91 is adapted to remove heat from the partially compressed process gas and transfer this heat to the absorption refrigeration cycle 85.

[0052] Thus, in this embodiment, waste heat generated by the fuel cell device 29 is used to cool the process gas prior to and / or during compression of the process gas, increasing the efficiency of the compressor 3 and reducing the power required to drive the compressor 3. The compressor size and / or number of compressor stages may also be reduced.

[0053] 6, a single intercooler is provided between two compression units, but in other embodiments not shown, there may be more compression units and more intercoolers. One, some, or all of the intercoolers may be in heat exchange relationship with the absorption refrigeration cycle 85 via one or more heat transfer loops 91.

[0054] Exemplary embodiments are disclosed above and illustrated in the accompanying drawings. It will be understood by those skilled in the art that various modifications, omissions, and additions may be made to what is specifically disclosed herein without departing from the scope of the invention as defined in the following claims.

Claims

1. A compressor system (1), comprising: a compressor (3) equipped with a sealing device including at least one gas seal (19; 61); a gas leakage recovery line (23) adapted to recover leakage of process gas from said at least one gas seal (19; 61); and a fuel cell device (25) fluidly coupled to the gas leak recovery line (23), the fuel cell device (25) configured to treat the recovered process gas leak and to generate power from the process gas leak.

2. 2. The compression system (1) of claim 1, wherein the sealing device comprises a separation gas supply (21) configured to deliver separation gas into the sealing device, and the fuel cell device (25) is adapted to process a mixture including a leakage of recovered process gas and a leakage of separation gas from the sealing device.

3. 3. The compression system (1) according to claim 1 or 2, wherein, in use, the compressor (3) processes a hydrogen-containing process gas, and the hydrogen contained in the recovered process gas leak is directly used as fuel in the fuel cell device (25).

4. 3. The compression system (1) of claim 1 or 2, further comprising a conversion unit (71) adapted to convert at least a portion of the recovered process gas leakage into a gas species suitable as a fuel for the fuel cell device (25).

5. The compressor (3) is A dynamic compressor having a rotating shaft (9), said sealing device comprising at least one rotating gas seal (19) around said rotating shaft, and 5. The compression system (1) according to any one of claims 1 to 4, comprising at least one of: a reciprocating compressor having a reciprocating piston rod (59), the sealing device comprising a gas seal packing (61) around the piston rod.

6. The compression system (1) according to any one of the preceding claims, further comprising a control unit (48) adapted to detect a flow rate of a gas leak delivered to the fuel cell device.

7. The compression system (1) of any one of claims 1 to 6, further comprising a fuel gas integration line (45) adapted to deliver a controlled flow of process gas to said fuel cell device (25).

8. The compression system (1) according to any one of the preceding claims, further comprising a power detection unit adapted to detect the power generated by the fuel cell device.

9. The compression system (1) according to any one of the preceding claims, further comprising a heat exchanger (37) adapted to recover heat produced by the fuel cell device (25).

10. The compression system (1) according to any one of the preceding claims, further comprising a booster compressor (31) adapted to boost the pressure of the process gas leak upstream of the fuel cell device (25).

11. a cooler (87.2) arranged along the flow path of the process gas treated by the compressor (3); a heat transfer system (80) adapted to remove heat generated by said fuel cell device (29) and transfer said heat to an absorption refrigeration cycle (85); The compression system (1) according to any one of the preceding claims, wherein the absorption refrigeration cycle (85) is configured to cool the process gas flowing through the chiller (87.2).

12. 12. The compression system (1) of claim 11, further comprising a refrigerant circuit (90) adapted to circulate a refrigerant fluid in the cooler (87.2) and adapted to transfer heat removed from the process gas to the absorption refrigeration cycle (85), whereby, in use, heat is removed from the process gas by the absorption refrigeration cycle (85) through the refrigerant circuit (90).

13. 13. The compression system (1) according to claim 11 or 12, wherein the compressor (3) comprises at least a first compression unit (3.1) and a second compression unit (3.2) arranged in series, and the cooler (87.2) is arranged between a discharge side of the first compression unit (3.1) and a suction side of the second compression unit (3.2).

14. 14. The compression system (1) of claim 13, further comprising an additional cooler (87.2) arranged along the process gas flow path between the first compression unit (3.1) and the cooler (87.1).

15. A method of operating a gas compression system (1), said method comprising the steps of: - compressing a process gas in a compressor (3) equipped with a sealing device (19; 61), - collecting leakage of process gas from said sealing device (19; 61); directing the recovered process gas leak towards a fuel cell device (25); treating the recovered process gas leakage in the fuel cell device (25) and generating power from the process gas leakage.

16. The method of claim 15 , wherein the process gas contains hydrogen.

17. The next step, i.e. - delivering a separation gas to said sealing device (19; 61); - collecting the mixture of process gas and separation gas escaping from said sealing device (19; 61); The method of claim 15 or 16, further comprising the step of: flowing said mixture through said fuel cell device (25).

18. The method according to any one of claims 15 to 17, further comprising the step of converting at least a portion of the process gas leaking through the sealing device (19; 61) into a different gas species suitable as a fuel for the fuel cell device (25).

19. 20. The method of claim 18, wherein the process gas comprises a hydrocarbon and the step of converting the process gas comprises producing hydrogen from the hydrocarbon.

20. The next step, i.e. detecting an amount of leaking gas delivered to the fuel cell device (25); The method according to any one of claims 15 to 19, further comprising the step of diverting additional process gas from the compressor (1) or from a line fluidly coupled to the compressor and delivering the additional process gas to the fuel cell device (25).

21. The method of any one of claims 15 to 1620, further comprising recovering waste heat from the fuel cell device (25).

22. 22. The method of claim 21, further comprising using the recovered waste heat in an absorption refrigeration cycle (85) to thereby cool the process gas.

23. 23. The method according to claim 22, wherein the process gas is cooled in an intercooler (87) arranged between the first compression unit (3.1) and the second compression unit (3.2).

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