JP2009127560A - Pump and fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inhibit deterioration of not only a hydrogen pump itself, but also a member at a downstream side of the hydrogen pump, due to corrosive ion component in hydrogen off gas. <P>SOLUTION: The hydrogen pump 24 includes a casing 41 discharging the hydrogen off gas sucked into the same to an outside, and rotors 42, 43 provided in the casing 41 and movable for raising pressure of the hydrogen off gas. Inner surfaces 55, 56 of the casing 41 and an outer surface of the rotors 42, 43 are coated by ion-exchange resin on surfaces which may be touched by the hydrogen off gas, and the corrosive ion component is adsorbed by the ion-exchange resin. Unevenness (groove) is formed on an outer circumference surface of the rotors 42, 43 to enlarge surface area to be coated by the ion-exchange resin. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pump and a fuel cell system, and more particularly to a technology for preventing corrosion of a pump.

As a technique for preventing corrosion of a pump, for example, one disclosed in Patent Document 1 is known. This pump is a Roots-type vacuum pump, in which the outer peripheral surface of the rotor is coated with a protective film made of a fluororesin as a base material. By adopting such a configuration, the rotor is protected from the corrosive components of the etching gas (halogen gas such as a fluorine compound) used in the semiconductor manufacturing process.
JP 2001-12373 A

  However, in the case of this vacuum pump, the protective film coated on the rotor only avoids the influence of corrosive components on the rotor. For this reason, piping connected to the discharge side of the vacuum pump may react with corrosive components and corrode.

  Therefore, the pump of the present invention is intended to suppress deterioration due to corrosion-generated ion components in the gas as well as the pump itself, as well as members downstream of the pump. Another object of the fuel cell system of the present invention is to suppress the deterioration of the pump and its downstream members due to the gas that can be discharged from the fuel cell.

  In order to achieve the above object, a pump according to the present invention includes a casing from which gas sucked into the inside is discharged to the outside, and a pressurizing member that is provided in the casing and is movable for pressurizing the gas. At least one of the inner surface of the casing and the pressure increasing member is coated with an ion exchange resin on the surface that can be contacted with gas.

  According to the pump of the present invention, even if the gas sucked into the casing contains a corrosion-generated ion component, it can be adsorbed (removed) by the ion exchange resin. Thereby, deterioration of at least one of the inner surface of a casing and a pressure | voltage rise member can be suppressed. Further, since the corrosion-generated ion component is removed from the gas pumped out of the casing, for example, deterioration of pipes and other members provided on the downstream side of the pump can be suppressed.

  Preferably, both the inner surface of the casing and the pressure increasing member may be coated with an ion exchange resin on the surface that can be contacted with gas.

  Preferably, irregularities are formed on the surface coated with the ion exchange resin.

  By doing so, the surface area of the coating surface can be increased compared to a flat surface having no irregularities. Thereby, the total amount of ions adsorbed by the ion exchange resin can be increased, and the life of the pump can be extended.

  Preferably, the pressurizing member is a pair of roots-type rotors rotatably provided in the casing, and an outer surface of each rotor may be coated with an ion exchange resin.

  By doing so, the durability of the rotor of the Roots pump can be improved.

  More preferably, a groove is formed on the outer peripheral surface of at least one of the pair of rotors.

  By doing so, the surface area of the coating surface can be increased as compared with the flat outer peripheral surface, so that the total amount of ions adsorbed by the ion exchange resin can be increased.

  Preferably, grooves are formed on the outer peripheral surfaces of both of the pair of rotors so that the concave portions and the convex portions that are parallel to each other are repeated, and the concave portion of one rotor meshes with the convex portion of the other rotor. It may be configured to rotate while.

  More preferably, the concave portion and the convex portion may extend in a direction orthogonal to the axial direction of each rotor.

  According to this configuration, the concave portion and the convex portion extend in a direction along the rotation direction of the rotor. Thereby, for example, when the gas contains a liquid, the resistance of the liquid in the rotor can be reduced, and the efficiency of the pump can be increased.

  More preferably, a groove extending in a direction orthogonal to the axial direction of each rotor is formed on the inner surface of the casing so as to engage with the concave portion and the convex portion of each rotor.

  By doing so, for example, when the gas contains a liquid, the resistance of the liquid can be further reduced.

  More preferably, the inner surface of the casing is also coated with an ion exchange resin.

  By doing so, not only the outer surface of the rotor but also the inner surface of the casing is coated with the ion exchange resin, so that the life can be further extended.

  According to another preferable aspect of the present invention, the concave portion and the convex portion may extend in parallel to the axial direction of each rotor.

  According to this configuration, the concave portion and the convex portion extend in a direction orthogonal to the rotational direction of the rotor. Thereby, the pressure | voltage rise performance of gas can be improved compared with the case where a recessed part and a convex part extend in the direction along the rotation direction of a rotor, for example.

  In order to achieve the above object, a fuel cell system of the present invention includes the above-described pump of the present invention, a fuel cell, and a discharge path through which gas discharged from the fuel cell flows, and the pump is provided in the discharge path. It is

  According to the fuel cell system of the present invention, the corrosion-generated ion component that can be contained in the gas discharged from the fuel cell can be adsorbed by the pump, so that the pump corrosion caused by the corrosion-generated ion component can be suppressed. Of course, corrosion can also be suppressed in the downstream portion of the pump in the discharge path.

  Preferably, the discharge path is a flow path for circulating hydrogen gas in the fuel cell, and the pump may pump hydrogen gas to the fuel cell.

  Thereby, not only the corrosion of the pump but also the corrosion of the fuel cell can be suppressed.

  According to the above-described pump and fuel cell system of the present invention, deterioration due to corrosion-generated ion components in the gas can be suppressed.

  Hereinafter, an example in which a pump according to a preferred embodiment of the present invention is applied to a fuel cell system will be described with reference to the accompanying drawings.

<First Embodiment>
As shown in FIG. 1, the fuel cell system 1 includes a fuel cell 2, an oxidizing gas piping system 3, and a fuel gas piping system 4. The fuel cell system 1 can be mounted on a vehicle, but of course can be applied not only to the vehicle but also to various moving bodies (for example, ships, airplanes, robots, etc.) and stationary power sources.

  The fuel cell 2 has a stack structure in which a large number of single cells are stacked. The solid polymer electrolyte type single cell has an air electrode on one surface of the electrolyte membrane, a fuel electrode on the other surface, and a pair of separators so as to sandwich the air electrode and the fuel electrode from both sides. . As the electrolyte membrane, a fluorine-based membrane is generally used. An oxidizing gas is supplied to the oxidizing gas channel 2a of one separator, and a fuel gas is supplied to the fuel gas channel 2b of the other separator. The fuel cell 2 generates electric power by an electrochemical reaction between the supplied oxidizing gas and fuel gas. In addition, the fuel cell 2 generates heat and generates water on the air electrode side due to the electrochemical reaction. The temperature of the solid polymer electrolyte fuel cell 2 is approximately 60 to 80 ° C.

  The oxidizing gas piping system 3 has a supply path 11 and a discharge path 12. The compressor 14 is provided in the supply passage 11, takes in outside air as an oxidizing gas via the air cleaner 13, and pumps it to the oxidizing gas passage 2 a of the fuel cell 2. Moisture exchange is performed between the oxidizing gas fed under pressure and the oxidizing off-gas by the humidifier 15 and humidified appropriately. The oxidizing off gas is discharged from the oxidizing gas flow path 2a to the discharge path 12, and after passing through the air pressure regulating valve 16 and the humidifier 15, is finally exhausted into the atmosphere outside the system as exhaust gas through a muffler (not shown).

  The fuel gas piping system 4 supplies and discharges hydrogen gas as fuel gas to and from the fuel cell 2. The fuel gas piping system 4 includes a hydrogen supply source 21, a supply path 22, a circulation path 23, a hydrogen pump 24, and a purge path 25. The hydrogen gas flows out from the hydrogen supply source 21 to the supply path 22 by opening the main valve 26, and is supplied to the fuel gas flow path 2b through the regulator 27 and the shutoff valve 28. Thereafter, the hydrogen gas is discharged from the fuel gas passage 2b to the circulation passage 23 as hydrogen off gas. The hydrogen off-gas is pumped by a hydrogen pump 24 to a junction A between the circulation path 23 and the supply path 22, merges with the hydrogen gas, and is supplied to the fuel gas flow path 2b again. A part of the hydrogen off-gas is discharged from the circulation path 23 to the purge path 25 by appropriately opening the purge valve 33, and is discharged outside through a hydrogen diluter (not shown).

  In such a fuel cell system 1, water is generated by an electrochemical reaction in the fuel cell 2, and this generated water is discharged from the fuel cell 2 to the circulation path 23 together with hydrogen off gas. Moisture floating in the particulate state in the produced water and hydrogen off gas may include elution components eluted from components in the fuel cell 2 and piping elements such as the circulation path 23. As an elution component, for example, corrosion-generated ions such as fluorine ions eluted from a fluorine-based electrolyte membrane may be included. When the corrosion-generated ions are supplied to the fuel cell 2, the deterioration of the fuel cell 2 is promoted. For this reason, an ion exchanger may be provided in the circulation path 23 to prevent the corrosion-generated ions from being supplied again to the fuel cell 2 together with the hydrogen off gas. In the present embodiment, the structure of the hydrogen pump 24 is devised to further remove the corrosion-generated ions contained in the hydrogen off-gas and the generated water.

FIG. 2 is a cross-sectional view showing the main part of the hydrogen pump 24, and FIG. 3 is a perspective view showing the main part of the hydrogen pump 24.
The hydrogen pump 24 has a roots type and includes a casing 41 and a pair of rotors 42 and 43.

  The casing 41 is formed with an intake port 51, an exhaust port 52 and a rotor chamber 53, and the rotors 42 and 43 are accommodated in the rotor chamber 53. The intake port 51 and the exhaust port 52 are positioned so as to face each other with the rotor chamber 53 interposed therebetween, and both communicate with the rotor chamber 53. The hydrogen off-gas is sucked into the rotor chamber 53 from the intake port 51, moves between the rotors 42 and 43 and the inner surface of the rotor chamber 53, and is discharged from the exhaust port 52 to the outside.

  The inner surface of the casing 41 includes an inner surface 55 having a circular arc shape that faces the rotor 42, and an inner surface 56 having a circular arc shape that faces the rotor 43. Further, the inner surface of the casing 41 has an intake-side inner surface 57 and an exhaust-side inner surface 58 that are continuous with the inner surfaces 55 and 56. An intake port 51 is defined by the intake side inner surface 57, and an exhaust port 52 is defined by the exhaust side inner surface 58. A rotor chamber 53 is defined by the inner surface 55 and the inner surface 56, and a gap is set between the inner surface 55 and the rotor 42 so as not to interfere with each other. A gap is also set between the inner surface 56 and the rotor 43 so as not to interfere.

  The rotors 42 and 43 have an eyebrow shape as viewed from the front in FIG. 2 and are arranged in the rotor chamber 53 in a state where the phase is shifted by about 90 degrees. The rotors 42 and 43 are connected to the rotation shafts 61 and 62, respectively, and are configured to be rotatable in opposite directions. The output of the motor (not shown) is input to the rotating shaft 61, the rotor 42 rotates, and the rotational force of the rotating shaft 61 is transmitted to the rotating shaft 62 via the timing gear set, so that the rotor 43 rotates. Yes. That is, the rotor 42 functions as an input-side rotor, and the rotors 42 and 43 are synchronously rotated in opposite directions to increase the pressure of the hydrogen off gas. Ideally, a gap is formed between the pair of rotors 42 and 43, and the rotors 42 and 43 are designed to rotate without contact with each other.

  The inner surface of the casing 41 and the rotors 42 and 43 are coated with an ion exchange resin on the surface that can be contacted with hydrogen off gas. Specifically, the inner surfaces 55 and 56 of the casing 41 and the eyebrow-shaped outer peripheral surfaces of the rotors 42 and 43 are covered with an ion exchange membrane 71 that is coated with an ion exchange resin. The ion exchange resin is, for example, in the form of particles or fibers having a cation exchange resin and an anion exchange resin, and the ion exchange membrane 71 adsorbs the hydrogen off gas and corrosion-generated ions in the produced water by ion exchange.

  According to another embodiment, the intake side inner surface 57 of the casing 41 may be coated with an ion exchange resin. This is because the hydrogen-off gas also comes into contact with the intake-side inner surface 57. The exhaust side inner surface 58 may be coated similarly. Further, from the viewpoint of weight reduction and the like, the rotors 42 and 43 may have through holes formed on both sides of the rotary shafts 61 and 62, respectively. In this case, the inner peripheral surface defining the through holes In addition, an ion exchange resin may be coated. The through hole extends in the extending direction of the rotating shafts 61 and 62 (hereinafter referred to as “rotor axial direction”).

  Here, in this embodiment, in order to increase the surface area of the ion exchange membrane 71, the coating surface is devised as follows.

  First, a groove is formed on the outer peripheral surface of the rotor 42 so that a concave portion 81 and a convex portion 82 that are parallel to each other are repeated in the rotor axial direction. Similarly, a groove is formed on the outer peripheral surface of the rotor 43 such that a concave portion 91 and a convex portion 92 that are parallel to each other are repeated in the rotor axial direction. The concave portions 81 and 91 and the convex portions 82 and 92 all extend in a direction perpendicular to the rotor axial direction. In other words, the concave portion 81 and the convex portion 82 are formed along the outer circumferential surface of the rotor 42 along the rotational direction of the rotor 42, and the concave portion 91 and the convex portion 92 are formed along the rotational direction of the rotor 43. The outer peripheral surface of 43 is formed over the circumferential direction. The concave portion 81 meshes with the convex portion 92 in a non-contact manner, and the concave portion 91 meshes with the convex portion 91 in a non-contact manner, and the rotors 42 and 43 rotate while maintaining this state.

  Grooves are also formed on the inner surfaces 55 and 56 of the casing 41 corresponding to the rotors 42 and 43. Specifically, a convex portion 101 and a concave portion 102 are formed on the inner surface 55 so as to mesh with the concave portion 81 and the convex portion 82 of the rotor 42 in a non-contact manner. The inner surface 56 is formed with a convex portion 111 and a concave portion 112 so as to mesh with the concave portion 91 and the convex portion 92 of the rotor 43 in a non-contact manner. The convex portion 101 and the concave portion 102 are formed along the rotational direction of the rotor 42 from one end to the other end of the inner surface 55, and the convex portion 111 and the concave portion 112 are along the rotational direction of the rotor 43 from one end to the other end of the inner surface 56. Is formed. The cross-sectional shape of the concave portions 81, 91, 102, 112 and the convex portions 82, 92, 101, 111 is arbitrary, and is, for example, a triangle or a trapezoid.

  According to the hydrogen pump 24 of the present embodiment described above, since the ion exchange membrane 71 is coated on the inner surfaces 55 and 56 of the casing 41 and the rotors 42 and 43, corrosion generation contained in the sucked hydrogen off-gas and generated water. Ions can be adsorbed by the ion exchange membrane 71. Thereby, it can suppress that inner surface 55,56 and rotor 42,43 deteriorate by corrosion, and can suppress that the circulation path 23 and the fuel cell 2 of the downstream of the exhaust port 52 deteriorate by corrosion. Further, since the ion exchange resin is provided in the hydrogen pump 24 as the ion exchange membrane 71, the corrosion-generated ions can be adsorbed and removed without increasing the pressure loss of the hydrogen off gas in the hydrogen pump 24.

  Furthermore, since the irregularities are formed on the outer peripheral surfaces of the inner surfaces 55 and 56 and the rotors 42 and 43, the surface area of the ion exchange membrane 71 can be increased compared to the case where these are formed on a flat surface without irregularities. . Thereby, the total amount of adsorbed ions of the ion exchange membrane 71 can be increased, and the lifetime of the hydrogen pump 24 and its downstream members can be extended. Moreover, since the unevenness | corrugations formed in the outer peripheral surface of the inner surfaces 55 and 56 and the rotors 42 and 43 are formed along the rotation direction of the rotors 42 and 43, the resistance of the generated water in the hydrogen off-gas in the rotors 42 and 43 The compression efficiency of the hydrogen pump 24 can be increased.

Second Embodiment
Next, with reference to FIG.4 and FIG.5, it demonstrates centering around difference about the hydrogen pump 120 which concerns on 2nd Embodiment of this invention. The difference from the first embodiment is that the extending direction of the unevenness formed on the rotors 42 and 43 is changed. In addition, about the structure which is common in 1st Embodiment, the same code | symbol is attached | subjected and the description is abbreviate | omitted.

  The concave portion 131 and the convex portion 132 of the rotor 42 extend in parallel with each other in the rotor axial direction, and are formed on the outer circumferential surface so as to repeat alternately in the circumferential direction of the rotor 42. Similarly, the concave portion 141 and the convex portion 142 of the rotor 43 extend in parallel with each other in the rotor axial direction, and are formed on the outer peripheral surface so as to repeat alternately in the circumferential direction of the rotor 43.

  The concave portion 131 meshes with the convex portion 142 in a non-contact manner, and the concave portion 141 meshes with the convex portion 132 in a non-contact manner, and the rotors 42 and 43 rotate while maintaining this state. The cross-sectional shapes of the concave portions 131 and 141 and the convex portions 132 and 142 are arbitrary, and are triangular here. In this embodiment, the inner surface of the casing 41 is not formed with irregularities, and is a flat surface. The ion exchange membrane 71 is coated on the outer peripheral surfaces of the rotors 42 and 43 and the inner surface of the casing 41 (at least one of the inner surfaces 55 and 56, the intake side inner surface 57 and the exhaust side inner surface 58). In FIG. 4, the position of the ion exchange membrane 71 is intended to be shown, and the lead-out line 71 is deliberately made a dotted line.

  According to the present embodiment, as in the first embodiment, the corrosion-generated ions contained in the sucked-in hydrogen offgas and generated water can be adsorbed by the ion exchange membrane 71, and the hydrogen pump 24 and the downstream members thereof can be adsorbed. Life can be extended. Further, since the unevenness is formed on the outer peripheral surfaces of the rotors 42 and 43, the surface area of the ion exchange membrane 71 can be increased as compared with the case where these are formed on a flat surface without the unevenness.

  However, since the concave and convex portions are not formed on the inner surface of the casing 41, the total amount of adsorbed ions of the ion exchange membrane 71 is reduced as compared with the first embodiment. However, since the unevenness formed on the outer peripheral surfaces of the rotors 42 and 43 extends in a direction perpendicular to the rotation direction of the rotors 42 and 43, the unevenness extends in the direction along the rotation direction as in the first embodiment. Compared to the case, the boosting performance of hydrogen gas can be improved.

  The hydrogen pump 24 according to the first embodiment and the hydrogen pump 120 according to the second embodiment described above may be selected to be suitable for the fuel cell system 1 in consideration of the required boosting performance and the required life.

  The hydrogen pump 24 may be configured by a volume type other than the roots type. For example, as the hydrogen pump 24, a rotary type such as a vane type or a screw type may be used, or a reciprocating type may be used. In the case of the vane type, an ion exchange resin is coated on the surface of the vane that is a pressure increasing member, and irregularities are formed on the surface as in the first embodiment or the second embodiment in order to increase the surface area. In the case of the reciprocating type, the surface (end surface) of the piston that is the pressure increasing member may be coated in the same manner, and irregularities may be formed on the surface. Of course, the hydrogen pump 24 is not limited to a positive displacement type and may be a turbo type. In any case, it is preferable to coat the surface where the hydrogen off-gas can come into contact with the pressurizing member that moves to increase the pressure of the hydrogen off-gas.

  Further, although the hydrogen pump 24 has been described as an example, the structure of the present embodiment described above can be applied even to a pump that pumps a gas other than hydrogen gas. The pump structure of the present invention is useful for systems that handle gases containing corrosion-generating ions, such as systems in semiconductor manufacturing processes.

1 is a configuration diagram of a fuel cell system to which a pump according to a first embodiment of the present invention is applied. It is sectional drawing which shows the principal part of the pump which concerns on 1st Embodiment of this invention. It is a perspective view which shows the principal part of the pump which concerns on 1st Embodiment of this invention. It is a perspective view which shows the principal part of the pump which concerns on 2nd Embodiment of this invention. It is an enlarged view in VV of FIG.

Explanation of symbols

  1: Fuel cell system, 2: Fuel cell, 23: Circulation path, 24: Hydrogen pump, 41: Casing, 42, 43: Rotor, 51: Inlet, 52: Exhaust, 53: Rotor chamber, 55, 56: Inner surface, 71: Ion exchange membrane, 81, 91, 102, 112, 131, 141: Recess, 82, 92, 101, 111, 132, 142: Projection, 120: Hydrogen pump

Claims (12)

A casing from which the gas sucked inside is discharged to the outside;
A pump provided in the casing and movable for boosting the gas,
At least one of the inner surface of the casing and the pressure-increasing member is a pump in which an ion-exchange resin is coated on a surface that can contact the gas.   2. The pump according to claim 1, wherein both the inner surface of the casing and the pressure increasing member are coated with an ion exchange resin on a surface to which the gas can come into contact.   The pump according to claim 1 or 2, wherein irregularities are formed on the surface coated with the ion exchange resin. The booster member is a pair of roots-type rotors rotatably provided in the casing,
The pump according to claim 1, wherein the outer peripheral surface of each rotor is coated with the ion exchange resin.   The pump according to claim 4, wherein a groove is formed on an outer peripheral surface of at least one of the pair of rotors. Grooves are formed on the outer peripheral surface of each rotor so that concave portions and convex portions parallel to each other are repeated.
5. The pump according to claim 4, wherein the pair of rotors is configured to rotate while a concave portion of one rotor meshes with a convex portion of the other rotor.   The pump according to claim 6, wherein the concave portion and the convex portion extend in a direction orthogonal to the axial direction of each rotor.   The pump according to claim 7, wherein a groove extending in a direction orthogonal to the axial direction of each rotor is formed on an inner surface of the casing so as to engage with a concave portion and a convex portion of each rotor.   The pump according to claim 8, wherein the inner surface of the casing is coated with the ion exchange resin.   The pump according to claim 6, wherein the concave portion and the convex portion extend in parallel with the axial direction of each of the rotors. A pump according to any one of claims 1 to 10,
A fuel cell;
An exhaust path through which the gas discharged from the fuel cell flows,
A fuel cell system, wherein the pump is provided in the discharge path. The discharge path is a flow path for circulating hydrogen gas through the fuel cell,
The fuel cell system according to claim 11, wherein the pump pumps hydrogen gas to the fuel cell.

Images