JP2000319005A - Catalytic reaction device and fuel reforming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve starting-up performance by increasing the temp. rising rate of a catalyst without conflicting with the miniaturization of a device. SOLUTION: A pressure drop plate 43 having holes each having a smaller diameter than a gas passage of a selective oxidation catalyst layer 42 is provided for CO removing equipment for oxidizing and removing carbon monoxide in a reformed gas by passing the hydrogen-enriched reformed gas containing carbon monoxide through the selective oxidation catalyst layer 42. The pressure drop plate 43 is arranged in the downstream side 42A of the selective oxidation catalyst layer 42 to be in close contact. As the pressure drop plate 43, for example, a porous body formed by sintering SUS powder is applied.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalytic reaction apparatus for causing a reaction gas to flow through a catalyst layer to cause a catalytic reaction in the reaction gas. The present invention relates to a technique suitable for use in a reformer or a CO remover among components of a fuel reformer that generates a rich reformed gas.

[0002]

2. Description of the Related Art For example, a solid electrolyte type fuel cell system includes a fuel cell main body comprising a stack of cells in which a solid polymer electrolyte membrane is sandwiched between an anode and a cathode. A system that generates an electrochemical reaction by supplying hydrogen-rich reformed gas and air (oxygen) generated by the device,
In recent years, it has been used as a power source for driving automobiles.

[0003] This fuel reformer is composed of hydrocarbons (for example,
An evaporator that vaporizes a liquid raw fuel containing methanol and water to generate a raw fuel gas, and a reformer that generates a reformed gas containing hydrogen by passing the raw fuel gas generated by the evaporator through a reforming catalyst layer. The main components are a reformer and a CO remover that selectively removes carbon monoxide in the reformed gas by passing the reformed gas generated by the reformer through a selective oxidation catalyst layer.

[0004] Among them, in the catalytic reaction in the reformer, since it is necessary to generate hydrogen from the supplied raw fuel gas with high efficiency, improvement of the efficiency of the catalytic reaction has been a conventional problem. As means for that purpose, for example, JP-A-11-4
The technique disclosed in Japanese Patent No. 3305 is known. In this prior art, a plurality of perforated plates (rectifying plates) are provided upstream of a reforming catalyst layer.
Are arranged to make the flow velocity distribution in the catalyst honeycomb portion uniform.

[0005]

In the above-mentioned fuel reformer, the reformer is provided with a reforming catalyst layer and the CO remover is provided with a selective oxidation catalyst layer. If these catalyst layers are not heated until they reach the activation temperature, hydrogen generation and CO removal cannot be performed efficiently. The time required for this warm-up needs to be reduced as much as possible in consideration of the application of the fuel reformer to an automobile.

However, in the above-mentioned prior art, since the current plate is provided on the upstream side of the reforming catalyst layer, it is effective in making the flow velocity distribution uniform in the reforming catalyst layer. When warming up by passing the combustion gas through the reformer, there is a disadvantage that the flow straightening plate acts as a heat mass element to delay the activation of the catalyst, resulting in a longer start-up time.

That is, if a current plate is arranged upstream of the reforming catalyst layer, the heat of the combustion gas is consumed for heating the current plate before heating the catalyst, and this heat loss is reduced. Preventing early activation of the catalyst. Further, in the above-described prior art, since the current plate is arranged in a plurality of stages, heat loss is further increased, and miniaturization of the reformer and thus the fuel reforming apparatus is also difficult.

The present invention has been made in view of such circumstances, and an object of the present invention is to speed up the temperature rise of the catalyst without hindering downsizing of the device and to improve the startability. It is in.

[0009]

In order to achieve the above object, the present invention provides a catalyst layer (reforming catalyst layer, selective oxidation catalyst layer).
The reaction gas (raw fuel gas, reformed gas) is passed through the reaction gas to cause a catalytic reaction (reaction formula (1))
(4) A catalyst reaction device (reformer, CO remover) for causing a pressure drop plate having a hole smaller in diameter than a gas flow path of the catalyst layer, wherein the pressure drop plate is provided with the catalyst. Characterized by being located downstream of the layer,
This makes it possible to raise the temperature of the catalyst layer to the activation temperature as soon as possible, as well as to make the flow surface distribution of the gas to be reacted uniform, and also to exhibit a filter function to catch falling objects and the like from the catalyst layer. I do.

That is, since the pressure drop plate disposed downstream of the catalyst layer causes the gas flow in the apparatus to stall, the flow velocity distribution can be made uniform. In addition, since the pressure loss plate does not become a heat mass element with respect to the catalyst layer on the upstream side, heat loss at the time of cold start is suppressed, and the temperature rise of the catalyst layer is accelerated. In addition, since a fallen object or the like from the catalyst layer due to aging can be captured by the pressure drop plate, it is possible to prevent clogging and breakage of devices (the fuel cell body and valves) arranged on the downstream side. . Furthermore, these functions are more effectively exhibited if the pressure-loss plate is brought into close contact with the catalyst layer.

When the present invention is used in a reformer that generates a hydrogen-rich reformed gas to be supplied to a fuel cell body as a power generation fuel, the reformed gas is generated quickly and efficiently from the start. It becomes possible. When the present invention is used in a CO remover that selectively oxidizes and removes carbon monoxide contained in a hydrogen-rich reformed gas to be supplied to a fuel cell body as a power generation fuel, carbon monoxide is started. , It can be removed quickly and efficiently.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a fuel cell main body 10.
1 shows an overall configuration diagram of a fuel cell system including a fuel reforming apparatus 20 that generates a hydrogen-rich reformed gas supplied to the fuel cell main body 10 as power generation fuel.

The fuel reforming apparatus 20 includes an evaporator 21 for evaporating a mixed liquid of methanol (hydrocarbon) and water to generate a raw fuel gas, and for warming up the evaporator 21 and evaporating the mixed liquid. A combustor 22 for generating a combustion gas to be used;
A reformer 23 for passing the raw fuel gas through a reforming catalyst layer to generate a hydrogen-rich reformed gas; and selectively passing carbon monoxide in the reformed gas through the selective oxidation catalyst layer. The main constituent elements are a CO remover 24 for removing the CO 2 and a starting combustor 25 for generating a combustion gas used for warming up the reformer 23 and the CO remover 24.

The combustor 22 contains a combustion catalyst for maintaining a combustion state and an electric heater as an ignition source, and supplies a starting fuel (eg, methanol) and air to the inside of the combustor 22. A nozzle for feeding is installed. Further, the combustor 22 includes a reformed gas generated during the period from the start to the steady operation, and a gas containing unreacted hydrogen discharged from the fuel cell body 10 during the steady operation (hereinafter, these gases are referred to as off-gases). ) Is connected to the vessel as a fuel for combustion.

The starting combustor 25 has substantially the same configuration as the combustor 22. That is, a combustion catalyst for maintaining a combustion state and a glow plug as an ignition source are housed in the vessel, and a nozzle for supplying starting fuel (for example, methanol) and air is installed. Become.

The evaporator 21 is provided with a nozzle for supplying a liquid raw fuel comprising a mixture of methanol and water into the evaporator 21. The liquid raw fuel sprayed from the nozzle is vaporized by the combustion gas supplied from the combustor 22 into the device.

As shown in the enlarged sectional view of FIG. 2, the reformer 23 has a substantially cylindrical casing 31 and a donut shape in a plan view in which multiple stages are arranged in parallel (five stages in FIG. 2). The reforming catalyst layer 32 and the pressure loss plate 33 are main components. At the radial center of the casing 31, a manifold tube 34 is disposed along the axial direction, and the reforming catalyst layer 32 and the pressure loss plate 33 are externally inserted into the manifold tube 34.

The manifold pipe 34 is an introduction pipe for introducing the raw fuel gas exiting the evaporator 21 into the casing 31. The downstream end 34A is closed and the raw fuel gas supplied to the pipe is supplied to the manifold pipe 34. A bleed hole 35 for flowing out of the tube is formed. A bleed hole group in which the bleed holes 35 are arranged at intervals in the circumferential direction of the manifold tube 34 is positioned slightly upstream of the reforming catalyst layer 32 of each stage, so that the inlet of each stage is improved. The heat mass and the flow distribution are made uniform.

The reforming catalyst layer 32 has Ni, Ru, Rh, and Cu-Z on the surface of a honeycomb structure formed by extrusion or the like.
An n-type catalyst or the like is coated, and the holes of the honeycomb structure serve as gas passages through which the raw fuel gas passes. The pressure loss plate 33 is provided at the downstream end of each reforming catalyst layer 32 from the viewpoint of uniforming the flow velocity distribution by stagnating the gas flow in the casing 31, suppressing heat loss during warm-up operation and adding a filter function. 32A is fixed so as to be in close contact with the entire surface.

As the pressure loss plate 33, for example, a porous plate formed by sintering SUS powder is used. However, the pressure loss plate 33 is not limited to such a sintered body of metal powder, but may be a gas flow path, that is, a hole of a honeycomb structure. As long as the configuration has holes smaller in diameter than the portion, a perforated plate formed by drilling a plurality of holes in a metal plate or the like may be used.

When the pressure loss plate 33 is made of a sintered body, it is advantageous in the following points. That is, a thin pressure-loss plate 33 having a large number of fine holes can be formed, which does not hinder the downsizing of the reformer 23. In addition, as a result that finer contaminants in the gas can be reliably captured, the reliability of the fuel reformer 20 and, consequently, the overall fuel cell system is improved.

When the raw fuel gas exiting the evaporator 21 is supplied to the reformer 23, a hydrogen-rich reformed gas is generated by the following autothermal reforming reaction. CH3OH + H2O → 3H2 + CO2 (1) CH3OH + 2O2 → 2H2O + CO2 (2)

The reaction formula (1) is a reforming reaction using methanol and water, and the reaction produces hydrogen as a target. The reaction formula (2) is an oxidation reaction of methanol, and the heat required for the reaction formula (1), which is an endothermic reaction, is supplied by the heat of oxidation at the time of this oxidation reaction.

In the reformer 23, the reaction formula (1)
In addition to (2), a small amount of carbon monoxide is generated by the following methanol decomposition reaction which inevitably occurs. CH3OH → 2H2 + CO (3) The carbon monoxide poisons the Pt catalyst in the fuel cell body 10 to lower the power generation efficiency and shorten the battery life. Removed.

Between the reformer 23 and the CO remover 24, the reformed gas discharged from the reformer 23 is cooled to protect the selective oxidation catalyst in the CO remover 24 from thermal damage. An exchanger 26 is provided.

As shown in the enlarged sectional view of FIG. 3, the CO remover 24 has a substantially cylindrical casing 41, a selective oxidation catalyst layer 42 and a pressure loss plate 43 housed therein as main components. . When a mixture of the reformed gas and air cooled through the heat exchanger 26 is supplied to the CO remover 24, carbon monoxide contained in the reformed gas is removed by the following CO selective oxidation reaction. Is done. 2CO + O2 → 2CO2 (4)

The selective oxidation catalyst layer 42 is formed by coating a surface of a honeycomb structure formed by extrusion or the like with a catalyst such as a Pt or Ru-based catalyst. It has become. The pressure loss plate 43
For example, a porous plate formed in a disk shape by sintering SUS powder is used, and the pressure loss plate 43 is in close contact with the downstream end 42A of the selective oxidation catalyst layer 42 as in the case of the pressure loss plate 33. It is fixed to.

As described above, in the present embodiment, the reformer 23
The pressure loss plate 33 and the pressure loss plate 43 of the CO remover 24 have the same configuration except for the shape, and both have a uniform flow velocity distribution, suppress heat loss during warm-up operation, and have a filter function. Together with the downsizing of the device and the fuel reformer 20
Can contribute to the improvement of reliability.

A heat exchanger 27 is provided between the CO remover 24 and the fuel cell body 10. This heat exchanger 2
7 cools the reformed gas discharged from the CO remover 24 and heats the Pt catalyst in the fuel cell body 10 similarly to the heat exchanger 26 installed between the reformer 23 and the CO remover 24. It is installed to protect it from damage.

Next, the fuel reformer 20 according to the present embodiment
An operation example will be described. First, at the time of cold start, since the evaporator 21, the reformer 23, and the CO remover 24 need to be warmed up, methanol is sprayed into the combustor 22 and oxygen-rich air is supplied to burn the methanol. The combustion gas generated thereby is sent to the evaporator 21,
The evaporator 21 is warmed up. Similarly, methanol and air are also supplied to the starting combustor 25, the generated combustion gas is sent to the reformer 23, and the reformer 23 and the CO remover 24 arranged downstream thereof are warmed up.

At this time, the reformer 23 and the CO remover 2
In No. 4, since the pressure loss plates 33 and 43 are disposed downstream of the reforming catalyst layer 32 and the selective oxidation catalyst layer 42,
The combustion gas passes through the pressure loss plates 33 and 43 after passing through the catalyst layers 32 and 42. Thereby, the pressure loss plate 33,
There is no heat loss due to the thermal mass element 43, and the retained heat of the combustion gas efficiently heats the reforming catalyst layer 32 and the selective oxidation catalyst layer 42.

Further, the pressure loss plates 33 and 43 are connected to the reformer 23.
And the gas flow in the CO remover 24 is settled.
The distribution of the flow velocity plane of the combustion gas is made uniform as compared with the case where the pressure loss plates 33 and 43 are not provided at all. Thereby, the reforming catalyst layer 3
2 and the heating of the selective oxidation catalyst layer 42 are uniformized in a cross section orthogonal to the flow direction, and in combination with the suppression of the heat loss, the catalyst layers 32 and 42 reach the activation temperature early, and the startability is improved. It is planned.

When the reforming catalyst layer 32 of the reformer 23 and the selective oxidation catalyst layer 42 of the CO remover 24 deteriorate with time, catalyst separation may occur in the honeycomb structure.
In the present embodiment, the porous pressure loss plates 33 and 43 are formed.
Also function as a filter, so that the catalyst layers 32 and 42
Drops and the like from the gas trapped by the pressure loss plates 33 and 43 can be used to remove contaminants in the gas, thereby preventing clogging and breakage of devices and valves provided on the downstream side.

Then, the temperature of the evaporator 21 reaches a temperature at which the mixture of methanol and water can be vaporized, and the reformer 23 and the C
When the reforming catalyst layer 32 and the selective oxidation catalyst layer 42 in the O remover 24 reach the activation temperature, the methanol spray to the starting combustor 25 is stopped, and the mixed liquid of methanol and water is poured into the evaporator 21. Spray. Then, the evaporator 21
In the above, the mixed liquid is vaporized by the combustion gas from the combustor 22 to generate a raw fuel gas, and this raw fuel gas is supplied to the reformer 23.

The raw fuel gas flowing into the reformer 23 is diverted to each hole (gas flow path) of the honeycomb structure constituting the reforming catalyst layer 32 and flows downstream while contacting the reforming catalyst. In the meantime, a hydrogen-rich reformed gas is generated by the reaction formulas (1) and (2). At this time, since the gas flow stagnates due to the pressure loss plate 33 disposed downstream of each reforming catalyst layer 32, the flow velocity distribution is made uniform, and the reaction formula (1) proceeds with high efficiency.

The reformed gas generated in the reformer 23 is about 3
Because of the high temperature of 00 ° C., it is cooled to about 100 ° C. through the heat exchanger 26 before being sent to the CO remover 24. When the cooled reformed gas flows into the CO remover 24, the reformed gas is split into each hole (gas flow path) of the honeycomb structure constituting the selective oxidation catalyst layer 42, and comes into contact with the selective oxidation catalyst. While circulating downstream.

During this time, carbon monoxide is selectively removed from the reformed gas by the reaction formula (4). Also in the CO remover 24, the gas flow stagnates and the flow velocity surface distribution is made uniform by the pressure loss plate 43 disposed downstream of the selective oxidation catalyst layer 42, so that the reaction equation (4) can be performed with high efficiency. The progress is the same as in the case of the reformer 23.

The reformed gas from which CO has been removed by the CO remover 24 passes through a heat exchanger 27 from about 180 ° C. to about 8 ° C.
After being cooled to 0 ° C., it is sent to the fuel cell main body 10 and used for power generation. The off-gas containing unreacted hydrogen discharged from the fuel cell body 10 is returned to the combustor 22 through the off-gas pipe, and is reused as combustion fuel.

As described above, during the steady operation, the reformed gas is sent from the fuel reformer 20 to the fuel cell main body 10, but in the present embodiment, the reformer 23 and the C
By the filter function of the pressure loss plates 33 and 43 provided in the O remover 24, the reforming catalyst layer 32 and the selective oxidation catalyst layer 42
No falling objects or the like from flowing into the fuel cell main body 10.

[0040]

As is apparent from the above description, according to the present invention, the following effects can be obtained. (A) In the present invention, since the pressure loss plate having holes smaller in diameter than the gas flow path of the catalyst layer is arranged downstream of the catalyst layer, the flow velocity distribution of the gas to be reacted in the apparatus is made uniform. In addition to improving the reaction efficiency, the catalyst layer can be quickly raised to the activation temperature, the time required for warm-up is reduced, and the startability is improved. In addition, since the pressure drop plate also functions as a filter for catching a fallen object or the like from the catalyst layer, clogging or breakage of devices and valves provided on the downstream side can be prevented, and reliability is improved. Further, if the pressure loss plate is brought into close contact with the catalyst layer, these effects are effectively exhibited.

(B) When the present invention is used in a reformer that generates a hydrogen-rich reformed gas to be supplied to the fuel cell body as a power generation fuel, the reformed gas can be used at an early stage from start-up and with high efficiency. When used in a CO remover that selectively oxidizes and removes carbon monoxide contained in a hydrogen-rich reformed gas to be supplied as power generation fuel to the fuel cell body, Thus, carbon monoxide can be removed early and with high efficiency from the start, and a fuel reformer with good startability can be configured.

[Brief description of the drawings]

FIG. 1 shows a reformer and C according to an embodiment of the present invention.
FIG. 1 is an overall configuration diagram illustrating a fuel cell system including a fuel reforming apparatus including an O remover and a fuel cell body.

FIG. 2 is an enlarged sectional view of the reformer shown in FIG.

FIG. 3 is an enlarged sectional view of the CO remover shown in FIG.

[Explanation of symbols]

 23 reformer (catalyst reactor) 24 CO remover (catalyst reactor) 32 reforming catalyst layer (catalyst layer) 32A, 42A downstream end 33, 43 pressure drop plate 42 selective oxidation catalyst layer (catalyst layer)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Yoshihiro Nakanishi 1-4-1 Chuo, Wako-shi, Saitama Prefecture Inside Honda R & D Co., Ltd. (72) Jun Sakuma Inventor 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (reference) 4G040 EA02 EA06 EB23 EB46 5H027 AA06 BA01 BA09 BA16

Claims (3)

[Claims] Claims: 1. A reaction target gas is passed through a catalyst layer,
A catalytic reactor for causing a catalytic reaction in the gas to be reacted, comprising a pressure loss plate having a hole having a smaller diameter than a gas flow path of the catalyst layer, and the pressure loss plate is disposed downstream of the catalyst layer. A catalytic reactor characterized in that: 2. The catalytic reactor according to claim 1, wherein the pressure loss plate is in close contact with the catalyst layer. 3. A reformer for generating a hydrogen-rich reformed gas to be supplied to a fuel cell body as a power generation fuel, and CO removal for selectively oxidizing and removing carbon monoxide contained in the reformed gas. A fuel reformer comprising a reformer and at least one of the reformer and the CO remover,
A fuel reforming apparatus, comprising the catalytic reactor according to claim 1 or 2.