Gas-liquid separator for separating at least one liquid component from a gaseous component

Abstract

The invention relates to a gas-liquid separator (2) for separating at least one liquid component, in particular H.sub.2O, from a gaseous component, in particular H.sub.2, the separator comprising at least one collecting tank (12) which is supplied with a medium, at least the liquid component of the medium being separated into the collecting tank (12), and the separated portion of the medium being discharged from the collecting tank (12) via a discharge valve (46). According to the invention, the gas-liquid separator (2) is integrated into a housing (11) of a recirculation pump (9).

Claims

1. A gas-liquid separator (2) of a fuel cell system (1) which comprises a recirculation pump (9), the gas-liquid separator (2) for separating at least one liquid component from a gaseous component with a collecting tank (12) which is supplied with a medium including H.sub.2 and H.sub.2O, wherein at least the liquid component of the medium is separated into the collecting tank (12), wherein the separated portion of the medium is discharged from the collecting tank (12) via a discharge valve (46), wherein the gas-liquid separator (2) is integrated into a housing (11) of the recirculation pump (9), and gas is returned from the collecting tank (12) via a suction connection (29) into an inflow channel (7) or an outflow channel (20) of the recirculation pump (9), wherein the liquid component of the medium comprises H.sub.2O and the gaseous component of the medium comprises H.sub.2, wherein the gas-liquid separator (2) has a separating edge (8), wherein one of the inflow channel (7) or the outflow channel (20) has a curvature (19) with a radius (17), and wherein the separating edge (8) is configured such that, when the medium is flowing through the curvature (19), the medium meets the separating edge (8) such that the separating edge (8) deflects the H.sub.2O into the collecting tank (12).

2. The gas-liquid separator (2) as claimed in claim 1, wherein the gas-liquid separator (2) is arranged downstream of a compressor chamber (26) of the recirculation pump (9).

3. The gas-liquid separator (2) as claimed in claim 2, wherein the gas-liquid separator (2) is in the region of an outlet (18).

4. The gas-liquid separator (2) as claimed in claim 1, wherein the gas-liquid separator (2) is arranged upstream of a compressor chamber (26) of the recirculation pump (9).

5. The gas-liquid separator (2) as claimed in claim 4, wherein the gas-liquid separator (2) is in the region of an inlet (16).

6. The gas-liquid separator (2) as claimed in claim 3, wherein the outflow channel (20) in a flow direction of the medium has a constriction (15) and then the curvature (19).

7. The gas-liquid separator (2) as claimed in claim 6, wherein the radius (17) is in the region of the separating edge (8).

8. The gas-liquid separator (2) as claimed in claim 5, wherein the inflow channel (7) in a flow direction of the medium has a constriction (21) and then the curvature (19).

9. The gas-liquid separator (2) as claimed in claim 8, wherein the radius (17) is in the region of the separating edge (8).

10. The gas-liquid separator (2) as claimed in claim 6, wherein the medium also includes N.sub.2, and wherein the medium is accelerated when flowing through the constriction (15) and the medium undergoes a deflection when flowing through the curvature (19), such that the H.sub.2O and the N.sub.2, because of their mass, undergo a greater deflection, and the H.sub.2, because of its mass, undergoes a lesser deflection.

11. The gas-liquid separator (2) as claimed in claim 10, wherein a proportion of the H.sub.2 is deflected into the collecting tank (12).

12. The gas-liquid separator (2) as claimed in claim 1, wherein the suction connection (29) has a choke element (14).

13. The gas-liquid separator (2) as claimed in claim 1, wherein a membrane chamber (25) is situated between the collecting tank (12) and the suction connection (29), wherein the membrane chamber (23) has a membrane insert (23).

14. The gas-liquid separator (2) as claimed in claim 13, wherein the membrane insert (25) is configured as a semipermeable membrane (34), and wherein the H.sub.2 can move through the membrane (34) while the H.sub.2O cannot move through the membrane (34) due to molecular sizes of the H.sub.2 and the H.sub.2O.

15. The gas-liquid separator (2) as claimed in claim 10, wherein the H.sub.2O and the N.sub.2 is separated from the medium by the gas-liquid separator (2) via a centrifugal principle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) An exemplary embodiment of the invention is described below in detail with reference to the attached drawing. The drawing shows:

(2) FIG. 1 a schematic depiction of a fuel cell system with a gas-liquid separator according to the invention, according to a first exemplary embodiment,

(3) FIG. 2 a schematic depiction of a gas-liquid separator according to the invention, according to a second exemplary embodiment,

(4) FIG. 3 a schematic depiction of a gas-liquid separator according to the invention, according to a third exemplary embodiment,

(5) FIG. 4 a schematic depiction of a gas-liquid separator according to the invention, according to a fourth exemplary embodiment.

DETAILED DESCRIPTION

(6) The illustration in FIG. 1 shows a fuel cell system 1 with a first exemplary embodiment of a gas-liquid separator 2 according to the invention, wherein in an exemplary embodiment, the gas-liquid separator 2 also separates the gaseous constituent N.sub.2 from the medium, in addition to the liquid constituent H.sub.2O, wherein in particular the gaseous constituent N.sub.2 has a higher mass than the constituent H.sub.2.

(7) FIG. 1 shows the fuel cell system 1 in which a recirculation pump 9 is shown with a gas-liquid separator 2, wherein the gas-liquid separator 2 is integrated in the housing 11 of the recirculation pump 9. Furthermore, it is evident that the fuel cell system 1 has a fuel cell 30 and an integrated jet pump 10. The recirculation pump 9 with gas-liquid separator 2, the integrated jet pump 10 and the fuel cell 30 are fluidically connected together by means of lines. The fuel cell 30 has an anode region 31 and a cathode region 32, and serves for energy generation, in particular in a vehicle, by means of a reaction of hydrogen (H.sub.2) and oxygen (O.sub.2). The energy may be produced in the form of electrical energy.

(8) The gas-liquid separator 2 according to the invention and/or the recirculation pump 9 is fluidically connected to the anode region 31 via a connecting line 4. A medium, which in particular is a recirculation medium from the anode region 31 of the fuel cell 30, is conducted to the recirculation pump 9 for recirculation. The recirculation medium consists almost completely of unused H.sub.2 which has not been consumed inside the fuel cell 30 for chemical or electrical reaction with oxygen, and the waste products H.sub.2O and N.sub.2 from the process of energy production inside the fuel cell 30. The medium flows in a flow direction II onto the anode side, through the connecting line 4, into an inlet 16 of the recirculation pump 9. The constituents H.sub.2O and N.sub.2 may alternatively be described as inactive gas portions, wherein the constituents cannot be used for energy production in the anode region 31 in the fuel cell 30. Thus the efficiency for complete operation of the fuel cell system 1 is reduced by the constituents H.sub.2O and N.sub.2 in the recirculation path, since if these components are not separated out by means of the gas-liquid separator 2, they must be conveyed through the entire anode path, in particular through the connecting line 4, an outflow line 5, the recirculation pump 9, the optional integrated jet pump 10 and an inflow line 3. Thus smaller masses and/or volumes of the constituent H.sub.2, which is necessary for energy production in the fuel cell 30, can be conveyed and/or recirculated.

(9) FIG. 1 furthermore shows that the medium flows via the inlet 16 in the flow direction II through a second constriction 21 into the inflow channel 7 of the recirculation pump 9. Because of the reducing diameter of the second constriction 21, the medium is accelerated before it flows through the inflow channel 7 into a compressor chamber 26 of the recirculation pump 9. The recirculation pump 9 inside the housing 11 has a compressor wheel 13, wherein the compressor wheel 13 is situated in the compression chamber 26, and wherein the compressor wheel 13 executes a rotation in a rotational direction 35. The rotation of the compressor wheel 13, on which blades 37 are arranged on the outer periphery, causes an acceleration and/or compression of the gaseous medium in the rotational direction 35 from the region of the inflow channel 7 to the region of an outflow channel 28 in the compressor chamber 26 of the recirculation pump 9. After acceleration and/or compression of the gaseous medium by the compressor wheel 37, the gaseous medium flows from the outflow channel 20 through a first constriction 15 into the region of a curvature 19, wherein the curvature 19 has a radius 17 and wherein a deflection and/or flow guidance of the gaseous medium takes place in the region of the curvature 19. When the medium flows through the curvature 19 in the flow direction II, the constituents H.sub.2O and N.sub.2 are separated from the medium by means of the centrifugal principle. On flowing through the first constriction 15, the medium is accelerated in the flow direction II, wherein when the medium then flows through the curvature 19, it undergoes a deflection in the flow direction II such that the constituents H.sub.2O and N.sub.2, because of their mass, undergo a greater deflection and the light constituent H.sub.2, because of its mass, undergoes a smaller deflection. The heavy constituents H.sub.2O and N.sub.2 here flow in a flow direction VI into a collecting tank 12 and are thus separated from the medium, wherein the medium—which consists almost completely of H.sub.2—flows on in a flow direction VII to an outlet 18 of the recirculation pump 9. The collecting tank 12 is arranged on the outer radius 17 of the curvature 19. It is however possible that, in the separating process, disadvantageously the constituent H.sub.2 also flows out into the collecting tank 12 with the H.sub.2O and N.sub.2. So that this H.sub.2 is not lost for the further energy production process in the fuel cell system 1, a return of H.sub.2 from the collecting tank 12 to the inflow channel 7 of the recirculation pump 9 via a suction connection 29 is provided.

(10) Furthermore, FIG. 1 shows that the collecting tank 12 in its lower region has a discharge valve 46, wherein the discharge valve 46 is connected to a sensor assembly 22. The sensor assembly 22 continuously detects the H.sub.2O and N.sub.2 proportion and in some cases the H.sub.2 proportion, and/or the pressure in the collecting tank 12, and as soon as a specific value relative to the concentration of the constituents H.sub.2O and N.sub.2 and/or a pressure is exceeded, the discharge valve 46 is actuated and the constituents H.sub.2O and N.sub.2 are discharged from and/or conducted out of the collecting tank 12, in particular the lower region, by means of the discharge valve 46. In a possible exemplary embodiment of the fuel cell system 1, the constituents H.sub.2O and N.sub.2 pass through the discharge valve 46 via an optional return line into an intake tract of the fuel cell system 1. From there, the constituents H.sub.2O and N.sub.2 flow on into the cathode region 32 of the fuel cell 30 through the intake tract. In an exemplary embodiment, a suction connection 29 is provided, by means of which H.sub.2 can be conducted back from the collecting tank 12 into the inflow channel 7 so that H.sub.2 is not conducted out of the fuel cell circuit.

(11) As evident from FIG. 1, the gas-liquid separator 2 according to the first exemplary embodiment is arranged downstream of the compressor chamber 26 of the recirculation pump 9 in a flow direction II, wherein the gas-liquid separator 2 is in particular situated in the region of the outlet 18.

(12) After the medium has flowed through the recirculation pump 9 and out through the outlet 18, the medium—which in particular now consists almost completely of H.sub.2—flows on in flow direction II via the outflow line 5 into the integrated jet pump 10. Inside the jet pump 10, a so-called jet pump effect takes place. For this, a gaseous propellant, in particular H.sub.2, flows through a tank line 33, for example from outside the jet pump 10, from a tank 27, in particular a high-pressure tank 27, into the jet pump 10. Furthermore, the recirculation medium is conveyed by the recirculation pump 9 into an intake region of the jet pump 10. The propellant is now introduced into the intake region under high pressure. The gaseous propellant flows in the flow direction II. The H.sub.2 flowing out of the high-pressure tank 27 into the intake region of the jet pump 10 and serving as a propellant has a pressure difference from the recirculation medium flowing into the intake region, wherein the propellant in particular has a higher pressure of at least 10 bar. In order for the jet pump effect to occur, the recirculation medium is conveyed with a low pressure and low mass flow into the intake region of the jet pump 10. The propellant flows into the intake region with the described pressure difference and a high speed, which in particular lies close to the speed of sound. Here, the propellant hits the recirculation medium which is already present in the intake region. Because of the high speed and/or pressure difference between the propellant and the recirculation medium, an internal friction and turbulence between the media are generated. This causes a shear stress in the boundary layer between the rapid propellant and the substantially slower recirculation medium. This stress causes a pulse transmission, wherein the recirculation medium is accelerated and carried along. The mixing takes place on the principle of conservation of momentum. The recirculation medium is accelerated in the flow direction II and a pressure fall occurs for the recirculation medium, whereby a suction effect takes place and further recirculation medium is conveyed from the region of the recirculation pump 9.

(13) After the recirculation medium has been accelerated in the jet pump 10 by the propellant and the two media have mixed, the new resulting medium—which in particular consists almost completely of H.sub.2—flows through the inflow line 3 to the fuel cell 30, in particular to the anode region 31.

(14) The diagrammatic depiction of the gas-liquid separator 2 according to a second exemplary embodiment in FIG. 2 shows that the outflow channel 20 has the separating edge 8 in the region of the curvature 19. When flowing through the curvature 19, the medium hits the separating edge 9, wherein the light constituent H.sub.2 is deflected in a flow direction VII to the outlet 18 and the constituents H.sub.2O and N.sub.2 are deflected in a flow direction VI to the collecting tank 12, wherein in particular a small part of the light constituent H.sub.2 may also be deflected into the collecting tank 12. The separating edge 8 has an advantageous effect on the separating process since it promotes a division of the medium, firstly into the heavy constituents H.sub.2O and N.sub.2 in a flow direction VII in the direction of the collecting tank 12, and secondly the light constituent H.sub.2 in a flow direction VII in the direction of the outlet 18. When flowing through the curvature 19, the medium hits the separating edge 8 which is arranged on the outer region of the curvature 19, in particular on the region on the outside of the curve. Furthermore, the separating edge 8 has a sharp and/or wedge-shaped region which supports the separation of the constituents H.sub.2O and N.sub.2 from the constituent H.sub.2, in particular by means of the centrifugal principle. When the medium flows through the curvature 19, a centrifugal force acts on its constituents, which in turn promotes a separation of the constituents H.sub.2O and N.sub.2 from the lighter constituent H.sub.2, in particular by means of the centrifugal principle.

(15) In addition, it is advantageous that the flow channel 20 tapers by means of the first constriction 19 in the flow direction II. In this way, the flow speed of the medium—which at this time still contains all constituents H.sub.2O, N.sub.2 and H.sub.2—can be increased, whereby the centrifugal force effect is increased and hence promotes separation. Here, furthermore it is also advantageous if the separating edge 8 is arranged in the outflow channel 20 in the region of the curvature 19 such that the separating edge 8 is situated at the lowest point of the outflow channel 20 and/or the curvature 19, and hence on the side facing the direction in which gravity is active. In this way, separation of the heavier constituents and lighter constituents by means of the centrifugal principle may be further supported by the effect of gravity and hence a more efficient separation achieved.

(16) The gas-liquid separator 2 according to a second exemplary embodiment here does not form a suction connection 29 between the collecting tank 12 and for example the inflow channel 7 of the recirculation pump 9. Thus a pressure fall between the outflow channel 20 and the inflow channel 7 may be avoided.

(17) FIG. 3 shows a diagrammatic depiction of the gas-liquid separator 2 according to a third exemplary embodiment. This shows that the suction connection 29 has a choke element 14. In addition, it shows that a membrane chamber 23 is situated in the region between the collecting tank 12 and the suction connection 29, wherein the membrane chamber 23 in particular has a membrane insert 25. The membrane insert 25 is formed as a semipermeable membrane 34, wherein the light constituent H.sub.2 of the medium can move through the membrane 34, while movement of the constituents H.sub.2O and N.sub.2 through the membrane 34 is not possible, in particular because of the molecular size. The suction connection 29 is here at least approximately at the highest point of the collecting tank 12 and hence on the side of the collecting tank 12 facing away from the direction in which gravity is active, while the discharge valve 46 is at the lowest point the collecting tank 12 and hence on the side of the collecting tank 12 facing the direction in which gravity is active. This may achieve the advantage that because of their high mass, the heavier constituents H.sub.2O and N.sub.2 in the collecting tank 12 flow rather in the direction of the discharge valve 46 and in so doing fill the volume of the collecting tank 12 facing the direction in which gravity is active. In contrast, because of its lighter mass, the lighter constituent H.sub.2 in the collecting tank 12 flows rather in the direction of the discharge valve 46 and in so doing fills the upper volume of the collecting tank 12 facing away from the direction in which gravity is active. This may achieve the advantage that, due to the layering of the constituents in the collecting tank 12, by using gravity it is ensured that a high proportion of the constituents H.sub.2O and N.sub.2 may be discharged through the discharge valve 46, while an outflow of H.sub.2 through the discharge valve 46 is almost completely prevented. Furthermore, by the layering of the constituents in the collecting tank 12 by using gravity, it is ensured that a high proportion of the constituent H.sub.2 can be returned through the suction connection 29 into the recirculation pump.

(18) The constituent H.sub.2 is here conducted in targeted fashion via the intake region 29 into the region of the inlet 16 and/or the inflow channel 7 which lies behind the region of the second constriction 21, wherein in particular a jet pump effect occurs in this region.

(19) FIG. 4 shows that in the flow direction II, the gas-liquid separator 2 is situated upstream of the compressor chamber 26 of the recirculation pump 9, in particular in the region of the inlet 16. The recirculation pump 9 has the inlet 16, the separating edge 8 and the collecting tank 12, wherein in the flow direction II, the inlet 16 firstly has a second constriction 21 and then the curvature 19 with the radius 17, in particular in the region of the separating edge 8. The medium is accelerated in flow direction II when flowing through the second constriction 21. Furthermore, when flowing through the curvature 19 in flow direction II, the medium undergoes a deflection such that the constituents H.sub.2O and N.sub.2, because of their mass, undergo a greater deflection and the light constituent H.sub.2, because of its mass, undergoes a lesser deflection. The constituents H.sub.2O and N.sub.2 and partially also H.sub.2 are deflected into the collecting tank 12 by means of the separating edge 8. The H.sub.2 is returned from the collecting tank 12 by the suction connection 29 into the outflow channel 20 of the recirculation pump 9.

(20) The invention is not restricted to the exemplary embodiments described and the aspects emphasized herein. Rather, a plurality of derivatives are possible within the scope given by the claims.