Fuel cell power generation system and fuel cell power generation method

Abstract

The present invention provides a fuel cell power generation system and a fuel cell power generation method, which belong to the field of fuel cell technology. The fuel cell power generation method comprises: supplying fuel gas to an anode; supplying an oxygen-containing gas to a cathode; and mixing a portion of the anode tail gas with the fuel gas to obtain a mixed gas, and supplying the mixed gas to the anode. Through the technical solution provided by the present invention, the gas path inside the fuel cell power generation system is adjusted, the tail gas generated by the stack can be fully recycled and utilized, and the operating efficiency of the fuel cell power generation system can also be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell power generation system and a control method thereof. Background Art

[0002] Existing fuel cells generate anode tail gas during operation. The anode tail gas contains components such as incompletely burned fuel gas and water vapor after the reaction. However, existing fuel cells do not fully recycle the anode tail gas. For example, the water vapor in the anode tail gas is discharged as waste water, which results in a very low fuel utilization rate of the fuel cell. In addition to the need to transport fuel gas and air to the fuel cell, it is also necessary to transport water vapor generated by other devices to the fuel cell. Summary of the invention

[0003] The purpose of the embodiments of the present invention is to provide a fuel cell power generation system and a control method thereof, so as to solve one or more of the above-mentioned technical problems.

[0004] In order to achieve the above-mentioned purpose, an embodiment of the present invention provides a fuel cell power generation method, which includes: supplying fuel gas to an anode; supplying oxygen-containing gas to a cathode; and mixing a portion of the anode tail gas with the fuel gas to obtain a mixed gas, and supplying the mixed gas to the anode.

[0005] Optionally, the circulation ratio of the anode tail gas is 0.3 to 2.2.

[0006] Optionally, the method further includes: exchanging heat between another part of the anode tail gas and the mixed gas, and supplying the mixed gas after the heat exchange to the anode.

[0007] Optionally, the method further comprises: combusting another part of the anode tail gas with the cathode tail gas to obtain a combustion tail gas.

[0008] Optionally, the method further comprises: exchanging heat between the combustion tail gas and the oxygen-containing gas, and supplying the oxygen-containing gas after the heat exchange to the cathode.

[0009] Optionally, the method further includes: obtaining water vapor using the combustion tail gas; and mixing the water vapor with the anode tail gas and the fuel gas to obtain the mixed gas, and supplying the mixed gas to the anode.

[0010] Optionally, the ratio of the amount of water vapor to the carbon flow rate of the fuel gas is 1 to 2:1.

[0011] Optionally, the method further includes: reforming the mixed gas, and supplying the reformed mixed gas to the anode.

[0012] Optionally, the operating temperature of the fuel cell is 500° C. to 900° C.; the operating pressure of the fuel cell is 0.05 MPa to 0.25 MPa.

[0013] On the other hand, an embodiment of the present invention provides a fuel cell power generation system, which includes: a fuel cell stack, including an anode and a cathode; a pumping device, used to mix the fuel gas and the anode tail gas of the anode into a mixed gas, and supply the mixed gas to the anode; and a regulating unit, connected to the pumping device, for adjusting the ratio of the fuel gas and the anode tail gas in the mixed gas.

[0014] Optionally, the fuel cell power generation system further includes: a first heat exchanger, disposed between the pumping device and the anode, for exchanging heat between another part of the anode tail gas and the mixed gas, and supplying the mixed gas after heat exchange to the anode.

[0015] Optionally, the fuel cell power generation system further includes: a burner connected to the first heat exchanger and the cathode, and used for burning another part of the anode tail gas with the cathode tail gas to obtain a combustion tail gas.

[0016] Optionally, a temperature-adjusting gas is passed through the burner, and the temperature-adjusting gas is used to adjust the temperature of the combustion exhaust gas.

[0017] Optionally, the fuel cell power generation system further includes: a second heat exchanger, disposed between the burner and the cathode, for exchanging heat between the combustion exhaust gas and the oxygen-containing gas, and supplying the oxygen-containing gas after heat exchange to the cathode.

[0018] Optionally, the fuel cell power generation system also includes: a waste heat recovery unit, arranged between the burner and the pumping device, for obtaining water vapor using the combustion exhaust gas and transporting the water vapor to the pumping device, the pumping device is used to mix the water vapor with the anode exhaust gas and the fuel gas to obtain the mixed gas, and supply the mixed gas to the anode.

[0019] Optionally, the fuel cell power generation system further includes: a reforming unit, disposed between the pumping device and the anode, for reforming the mixed gas and supplying the reformed mixed gas to the anode.

[0020] Optionally, the pumping device is an ejector pump.

[0021] Through the above technical solution, the gas path inside the fuel cell power generation system is adjusted, the exhaust gas generated by the fuel cell stack can be fully recovered and utilized, and the operating efficiency of the fuel cell power generation system can also be improved.

[0022] Other features and advantages of the embodiments of the present invention will be described in detail in the subsequent detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings are used to provide a further understanding of the embodiments of the present invention and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present invention, but do not constitute a limitation on the embodiments of the present invention. In the accompanying drawings:

[0024] Figure 1 is a schematic structural diagram of a fuel cell power generation system provided by an embodiment of the present invention;

[0025] Figure 2 It is a schematic flow chart of a fuel cell power generation method provided in an embodiment of the present invention.

[0026] Description of reference numerals:

[0027] 1 Priming pump 2 Regulating valve

[0028] 3 Reforming unit 4 First heat exchanger

[0029] 5 Anode 6 Cathode

[0030] 7 Burner 8 Second heat exchanger

[0031] 9 Waste heat recovery unit 10 Air delivery end

[0032] 11. Regulating valve DETAILED DESCRIPTION

[0033] The specific implementation of the embodiment of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the embodiment of the present invention, and is not used to limit the embodiment of the present invention.

[0034] First of all, it should be noted that the terms "first", "second", etc. in the embodiments of the present invention are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features, and when necessary, the effects that can be achieved by these technical features are basically the same.

[0035] The working process of an ordinary fuel cell is as follows: the fuel gas enters the anode of the fuel cell stack, and the air enters the cathode of the fuel cell stack. After the fuel gas reacts with the air, the anode exhaust gas generated is discharged from the fuel cell through the outlet end of the anode of the stack, and the air that has not completely reacted is discharged from the fuel cell through the outlet end of the cathode of the stack.

[0036] On this basis, the solution provided in the embodiment of the present invention improves the gas path in the fuel cell power generation system to improve the operating efficiency of the fuel cell power generation system.

[0037] Specifically, the fuel cell power generation system provided in the embodiment of the present invention is equipped with a pumping device and a regulating unit that are interconnected on the basis of a conventional structure.

[0038] The working process of the fuel cell power generation system provided by this embodiment of the present invention is as follows:

[0039] When the fuel cell power generation system is in the startup state, the regulating functions of the pumping device and the regulating unit are not enabled, the fuel gas directly enters the anode of the stack through the pumping device and the regulating unit, and the air also directly enters the cathode of the stack, and the fuel cell power generation system starts to work;

[0040] During the stable operation of the fuel cell power generation system, the anode tail gas discharged from the anode of the stack contains unreacted fuel gas and the temperature of the anode tail gas is relatively high. On this basis, the anode tail gas coming out of the anode is introduced into a pumping device, which mixes the fuel gas and the anode tail gas into a mixed gas and then supplies it to the anode.

[0041] In particular, while the fuel gas and the anode tail gas are mixed, the anode tail gas can also be used to increase the temperature of the fuel gas.

[0042] Considering that if all the anode tail gas is mixed with the fuel gas, the proportion of the fuel gas component in the mixed gas may be low, affecting the reaction efficiency in the fuel cell stack, it is possible to consider sending only part of the anode tail gas to the pumping device and the regulating unit. For example, the tail gas circulation ratio can be controlled by the regulating unit to be between 0.3 and 2.2, preferably between 0.5 and 2.

[0043] Except for the part of the anode exhaust gas that is sent to the pumping device, the remaining exhaust gas has a higher temperature. Therefore, an embodiment of the present invention also provides a fuel cell power generation system that can further utilize the remaining anode exhaust gas. The system can also set a first heat exchanger between the pumping device and the anode to use the remaining high-temperature anode exhaust gas and the mixed gas for heat exchange. The temperature of the mixed gas entering the anode can be further increased to improve its reaction efficiency in the fuel cell stack. The remaining anode exhaust gas after heat exchange can be discharged as exhaust gas.

[0044] In some optional embodiments, an exhaust gas treatment component may also be provided in the fuel cell power generation system.

[0045] Specifically, the remaining anode tail gas after heat exchange contains fuel gas for full reaction, so a burner connected to the first heat exchanger can be set in the fuel cell power generation system, and the remaining anode tail gas after heat exchange can be sent to the burner for combustion, and then the tail gas after the fuel gas combustion reaction is discharged.

[0046] The burner provided in this embodiment of the present invention uses high-temperature cathode air to assist combustion, so that the low calorific value anode tail gas can burn stably.

[0047] The combustion reaction inside the burner also requires oxygen, which can come from a separate supply pipeline or from cathode tail gas discharged from the cathode.

[0048] Furthermore, the exhaust gas temperature of the burner is relatively high, and the air entering the cathode also needs to be at a certain temperature to ensure the reaction efficiency in the stack. Therefore, in the optional embodiment of the present invention, it is also possible to consider setting a second heat exchanger connected to the burner in the fuel cell power generation system, and the exhaust gas discharged by the burner exchanges heat with the oxygen-containing gas to be transported to the cathode, and then the moderated oxygen-containing gas is supplied to the cathode. Such a structural setting can further improve the working efficiency of the fuel cell power generation system.

[0049] Considering that the exhaust gas temperature directly discharged from the burner is too high, which is not conducive to the subsequent exhaust gas treatment and heat exchange operations, the temperature adjustment process can be performed inside the burner, that is, the exhaust gas temperature discharged from the burner is within a controllable temperature range. Specifically, a temperature-adjusting gas can be introduced into the burner to adjust the temperature of the combustion exhaust gas.

[0050] The temperature range of the exhaust gas discharged from the burner can be set according to actual needs, and the exhaust gas temperature can be adjusted by adjusting the amount of temperature-regulating gas introduced into the burner.

[0051] Optionally, the temperature-adjusting gas may be supplied separately, or a portion of the temperature-adjusting gas may be extracted from the oxygen-containing gas supplied to the cathode and supplied to the burner for adjusting the temperature of the combustion exhaust gas.

[0052] For fuel cell power generation systems, adding water vapor to the gas entering the anode can keep the anode membrane moist to increase ionic conductivity.

[0053] Based on the technical solution provided in any embodiment of the present invention, when the fuel cell power generation system is in the startup condition, there is no water vapor in the fuel gas directly entering the anode and the anode tail gas discharged from the anode. Therefore, this embodiment of the present invention proposes that a separate water vapor circuit can be set up to transport the water vapor to a pumping device, and the pumping device mixes the water vapor, fuel gas and anode tail gas and transports them to the anode of the fuel cell stack.

[0054] For example, a preheat recovery unit can be provided, which can obtain water vapor using high-temperature tail gas. The high-temperature tail gas used to enable the preheat recovery unit to generate water vapor can be anode tail gas, cathode tail gas, or combustion tail gas discharged from a burner.

[0055] When the fuel cell power generation system is in a stable working state, the water vapor in the anode tail gas can meet the demand, and at this time, the preheating recovery unit is stopped to transport the water vapor generated by the high-temperature tail gas to the pumping device. In this embodiment, the anode tail gas can be fully utilized without adding water vapor, and there is no need to discharge waste water.

[0056] The fuel cell power generation system provided in this embodiment of the present invention introduces a pumping device when the fuel cell power generation system is in the startup state, which can not only improve the working efficiency of the fuel cell power generation system, but also effectively prevent carbon accumulation and blockage inside the pipeline and the pumping device based on the negative pressure principle. In addition, the heat of the anode tail gas, cathode tail gas and combustion tail gas can be fully recovered and utilized.

[0057] In the fuel cell power generation system provided by any of the above embodiments of the present invention, a reforming unit can also be provided according to demand to reform and transform the mixed gas mixed by the pumping device before transmitting it to the anode.

[0058] The specific function of the reforming unit provided in this embodiment depends on the specific type of fuel cell power generation system. For example, when the methane component in the fuel gas accounts for a large proportion, part of the methane can be catalytically reformed through the reforming unit to obtain hydrogen and reduce the emission rate of carbon dioxide.

[0059] Figure 1 Schematic diagram of the structure of the fuel cell power generation system provided by the embodiment of the present invention. Figure 1 The fuel cell power generation system provided by the embodiment of the present invention is described in detail. In this embodiment, an ejector pump is used as a pumping device, and a regulating valve is used as a regulating unit.

[0060] Specifically, the fuel gas enters the anode 5 through the ejector pump 1, the reforming unit 3 and the first heat exchanger 4. A portion of the anode tail gas generated by the anode 5 flows into the ejector pump 1 to generate a mixed gas and is then transported to the anode 5. The other portion flows into the heat exchanger 4 to exchange heat with the mixed gas. The anode tail gas after heat exchange flows into the burner 7 for combustion. The generated tail gas can be discharged directly or flow into the second heat exchanger 8 to exchange heat with the air and then be discharged. The air enters the cathode 6 through the air delivery end 10 and the second heat exchanger 8. The cathode tail gas discharged from the cathode 6 can enter the burner 7 to provide oxygen for the combustion treatment of the anode tail gas.

[0061] A bypass with a regulating valve 2 is provided at the ejector pump 1. Based on the negative pressure principle, the amount of fuel gas flowing into the ejector pump 1 is adjusted by adjusting the opening of the regulating valve 2 to achieve control of the anode tail gas circulation ratio.

[0062] A pipeline through which air can flow may be provided between the air delivery end 10 and the burner 7 , and a regulating valve 11 may be provided on the pipeline. The temperature of the combustion exhaust gas discharged from the burner 7 may be adjusted by adjusting the opening of the regulating valve 11 .

[0063] In the fuel cell power generation system provided in this embodiment, a waste heat recovery unit 9 can also be set between the ejector pump 1 and the second heat exchanger 8. When the fuel cell power generation system is in the initial startup condition, the high-temperature combustion exhaust gas discharged by the burner 7 can enter the waste heat recovery unit 9 after passing through the second heat exchanger 8, generate water vapor by heating, and send the water vapor to the ejector pump 1.

[0064] In the fuel cell power generation system provided in this embodiment of the present invention, fresh fuel gas and high-temperature anode exhaust gas are mixed through an ejector pump, and after reforming or conversion treatment, enter the fuel cell anode after heat exchange with the high-temperature anode exhaust gas; cathode air enters the fuel cell cathode after heat exchange with the combustion exhaust gas, and the exhaust gas coming out of the cathode directly enters the burner to assist combustion, thereby burning the low calorific value anode exhaust gas.

[0065] The operating temperature range of the fuel cell may be 500° C. to 900° C., preferably 600° C. to 800° C.; the operating pressure range of the fuel cell may be 0.05 MPa to 0.25 MPa, preferably 0.1 MPa to 0.2 MPa.

[0066] The ejector pump is provided with a regulating valve bypass for adjusting the circulation amount of high-temperature exhaust gas, and the exhaust gas circulation ratio is controlled within a range of 0.3 to 2.2, preferably within a range of 0.5-2.

[0067] The burner outlet temperature is controlled at about 700°C to 900°C by cold air, and can be cooled to about 100°C-300°C after heat exchange with the cathode inlet air, and then enters the waste heat recovery unit.

[0068] When the fuel cell power generation system is in the startup condition, water vapor generated by the waste heat of the combustion exhaust is added to the ejector pump to prevent carbon deposition and blockage. The amount of water vapor added is 1-2 times the carbon flow rate of the fresh fuel gas.

[0069] Figure 2 1 is a schematic flow chart of a fuel cell power generation method provided by an embodiment of the present invention, and the fuel cell power generation method shown in the figure is applicable to the fuel cell power generation system provided by any of the above embodiments of the present invention. Figure 2 As shown, the fuel cell power generation method provided in this embodiment includes steps S110 to S130.

[0070] In step S110 , fuel gas is supplied to the anode.

[0071] In step S120, an oxygen-containing gas is supplied to the cathode.

[0072] In step S130, a portion of the anode off-gas is mixed with the fuel gas to obtain a mixed gas, and the mixed gas is supplied to the anode.

[0073] Through the above technical solution, the incompletely burned fuel gas in the anode tail gas and the high temperature can be fully utilized, so this circulation method can effectively reduce the fuel cell tail gas emissions and improve the working efficiency of the fuel cell. In addition, since the anode tail gas contains water vapor, there is no need to provide an additional branch for supplying water vapor. This circulation method can also effectively prevent carbon deposition and blockage.

[0074] Wherein, the circulation ratio of the anode tail gas is 0.3 to 2.2, preferably in the range of 0.5 to 2.

[0075] In some optional embodiments, another part of the anode tail gas may be heat exchanged with the mixed gas, and the mixed gas after heat exchange is supplied to the anode.

[0076] In some optional embodiments, another part of the anode tail gas may be burned with the cathode tail gas to obtain the combustion tail gas.

[0077] In some optional embodiments, the combustion tail gas may be heat exchanged with the oxygen-containing gas, and the oxygen-containing gas after heat exchange is supplied to the cathode.

[0078] When the fuel cell is in the initial startup condition, since the anode exhaust gas temperature is relatively high but does not yet contain water vapor, water vapor can be added to the gas supplied to the anode in the following manner: using the combustion exhaust gas to obtain water vapor; and mixing the water vapor with the anode exhaust gas and the fuel gas to obtain the mixed gas, and supplying the mixed gas to the anode.

[0079] The ratio of the amount of water vapor to the carbon flow rate of the fuel gas is 1 to 2:1.

[0080] In some optional embodiments, the mixed gas can be reformed according to actual needs and fuel gas composition, and the reformed mixed gas is then supplied to the anode.

[0081] In some optional embodiments, the operating temperature of the fuel cell is 500° C. to 900° C., and the operating pressure of the fuel cell is 0.05 MPa to 0.25 MPa.

[0082] For the specific details and benefits of the fuel cell power generation method provided by the above embodiment of the present invention, please refer to the specific details and benefits of the fuel cell power generation system provided by the present invention, which will not be repeated here.

[0083] The technical solution provided by the present invention is now explained using a 20kW-class synthesis gas fuel cell power generation system.

[0084] In this fuel cell power generation system, 10Nm 3 / h of synthesis gas (62% H2, 37% CO) and tail gas (about 10Nm 3 / h) mixed preheated to about 400℃, after heat exchange with the anode tail gas to about 700℃, enter the solid oxide fuel cell anode reaction, the fuel utilization rate can reach 80%, the power generation power is 20kW, the anode outlet tail gas temperature is about 800℃, part of the circulation (10Nm 3 / h) and mix with fresh gas, the remaining part is heat exchanged with feed gas and enters the burner, the combustion tail gas temperature is controlled to be about 830℃, the tail gas is passed through cathode air (flow rate 200Nm 3 / h) and then dropped to about 150°C before being discharged; the cathode air temperature after heat exchange with the combustion exhaust gas is about 700°C and enters the fuel cell, and the exhaust gas temperature at the cathode outlet is about 800°C.

[0085] The optional implementation modes of the embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above implementation modes. Within the technical concept of the embodiments of the present invention, various simple modifications can be made to the technical scheme of the embodiments of the present invention, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

[0086] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the embodiments of the present invention will not further describe various possible combinations.

[0087] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0088] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A fuel cell power generation method, characterized in that: The method includes: supplying fuel gas to the anode; supplying an oxygen-containing gas to the cathode; and When the fuel cell is in a startup state, a portion of the anode tail gas, water vapor and the fuel gas are mixed to obtain a mixed gas, and the mixed gas is supplied to the anode, wherein the ratio of the amount of the water vapor to the carbon flow of the fuel gas is 1 to 2:1; When the fuel cell is in operation, a portion of the anode tail gas is mixed with the fuel gas to obtain a mixed gas, and the mixed gas is supplied to the anode, wherein the circulation ratio of the anode tail gas is 0.3 to 2.

2.

2. The method according to claim 1, characterized in that The method further comprises: Another part of the anode tail gas is heat exchanged with the mixed gas, and the mixed gas after heat exchange is supplied to the anode.

3. The method according to claim 1, characterized in that The method further comprises: Another part of the anode tail gas is burned with the cathode tail gas to obtain combustion tail gas.

4. The method according to claim 3, characterized in that The method further comprises: The combustion tail gas is heat exchanged with the oxygen-containing gas, and the oxygen-containing gas after heat exchange is supplied to the cathode.

5. The method according to claim 3, characterized in that: The method further comprises: The water vapor is obtained by utilizing the combustion tail gas.

6. The method according to any one of claims 1 to 5, characterized in that The method further comprises: The mixed gas is reformed, and the reformed mixed gas is supplied to the anode.

7. The method according to any one of claims 1 to 5, characterized in that The operating temperature of the fuel cell is 500°C to 900°C; The working pressure of the fuel cell is 0.05 MPa to 0.25 MPa.

8. A fuel cell power generation system, characterized in that: The fuel cell power generation system comprises: A battery stack, including an anode and a cathode; A pumping device, for mixing a part of the anode tail gas, water vapor and fuel gas to obtain a mixed gas when the fuel cell is in a startup condition, and supplying the mixed gas to the anode, wherein the ratio of the amount of water vapor to the carbon flow rate of the fuel gas is 1 to 2:1; and for mixing the fuel gas and the anode tail gas of the anode into a mixed gas when the fuel cell is in an operating condition, and supplying the mixed gas to the anode, wherein the circulation ratio of the anode tail gas is 0.3 to 2.2; and The regulating unit is connected to the pumping device and is used to adjust the ratio of the fuel gas and the anode tail gas in the mixed gas when the fuel cell is in an operating condition.

9. The fuel cell power generation system according to claim 8, characterized in that: The fuel cell power generation system further comprises: The first heat exchanger is arranged between the pumping device and the anode, and is used for exchanging heat between another part of the anode tail gas and the mixed gas, and supplying the mixed gas after heat exchange to the anode.

10. The fuel cell power generation system according to claim 9, characterized in that: The fuel cell power generation system further comprises: A burner is connected to the first heat exchanger and the cathode, and is used to burn another part of the anode tail gas with the cathode tail gas to obtain combustion tail gas.

11. The fuel cell power generation system according to claim 10, characterized in that: A temperature-adjusting gas is passed through the burner, and the temperature-adjusting gas is used to adjust the temperature of the combustion exhaust gas.

12. The fuel cell power generation system according to claim 10, characterized in that: The fuel cell power generation system further comprises: The second heat exchanger is arranged between the burner and the cathode, and is used for exchanging heat between the combustion tail gas and the oxygen-containing gas, and supplying the oxygen-containing gas after heat exchange to the cathode.

13. The fuel cell power generation system according to claim 10, characterized in that: The fuel cell power generation system further comprises: A waste heat recovery unit is arranged between the burner and the pumping device, and is used to obtain water vapor using the combustion exhaust gas and transport the water vapor to the pumping device.

14. The fuel cell power generation system according to any one of claims 8 to 13, characterized in that: The fuel cell power generation system further comprises: The reforming unit is disposed between the pumping device and the anode, and is used for reforming the mixed gas and supplying the reformed mixed gas to the anode.

15. The fuel cell power generation system according to any one of claims 8 to 13, characterized in that: The pumping device is an ejector pump.

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