JP2002293503A - Reformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact reformer with high energy efficiency which generates high purity hydrogen by reforming hydrocarbon fuel, or alcoholic fuel. SOLUTION: The mixed gas (2) which is heated on the heating portion (4) is fed into the reforming portion (14) after equally distributing by the distribution pipe (8). The reformer has a structure which constitues one or two more reforming tubes (30) in parallel, in which reforming catalysts (12) are filed up. Hot reforming gas (18) after reforming is flushed around the reforming tubes and returned to a manifold (16).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reformer for providing high-purity hydrogen, and more particularly, to reforming of hydrocarbon fuels, alcohol fuels, etc. in the hydrogen fuel industry such as fuel cells. And a compact reformer with high energy efficiency for providing high-purity hydrogen.

[0002]

2. Description of the Related Art In recent years, interest in hydrogen has been increasing with the expectation that it will play an important role as a fuel in future energy systems. Among the energy systems using hydrogen, fuel cells have excellent characteristics such as high power generation efficiency, small generation of carbon dioxide, and no generation of harmful gases such as nitric oxide.

[0003] Hydrogen required for power generation by a fuel cell is mainly produced by a reforming reaction using a hydrocarbon fuel such as butane or propane, an alcohol fuel such as methanol as a starting material, and the like. However, since the hydrogen-rich reformed gas obtained by the reforming reaction contains a large amount of carbon monoxide (CO) as an impurity, it cannot be used for a fuel cell that requires high-purity hydrogen. This needs to be removed. This is because when CO is supplied to the fuel electrode of the fuel cell, it is competitively adsorbed with H2 at the catalytic active point of the fuel electrode, poisoning the electrode catalyst in the fuel cell, inhibiting the electrode reaction, and improving the power generation performance. This is because it causes a decrease.

Therefore, the reforming apparatus is provided with a CO removing section filled with a CO removing catalyst. In this section, a CO selective oxidation reaction (CO + 1 / 2O ₂ → CO ₂ ) and, if necessary, C
Generally, a mechanism for reducing the concentration of carbon monoxide by performing an O shift reaction (CO + H ₂ O → CO ₂ + H ₂ ) is provided.

In a reformer that generates a hydrogen-rich reformed gas by a reforming reaction from a hydrocarbon fuel, an alcohol fuel, or the like, heat is supplied to the reforming section because the reforming reaction proceeds endothermically. There is a need. Heat supply is also important to increase the reaction rate of the reforming reaction. Therefore, in many cases, the fuel gas, water, and air are heated by a heat source to a temperature suitable for the reforming reaction, and are then turned into high-temperature steam and then sent to the reforming section, or heated to such a temperature in the reforming section and reformed. Quality reaction will take place.

On the other hand, the C of the reformed gas generated in the reforming section
The reaction initiation temperature in the CO removal section, which is the catalyst layer mainly for reducing the O concentration, is 100 to 200 ° C. in the CO selective oxidation reaction.
In the CO shift reaction, the temperature is about 200 to 300 ° C. Further, since the CO selective oxidation reaction and the CO shift reaction are exothermic reactions, to promote the CO removal reaction,
It is necessary to prevent the temperature of the O removal catalyst from rising. Therefore, in the conventional reforming apparatus, the reforming section and the CO removing section are designed separately, or when they are integrally designed, the CO is removed from the reforming section.
A heat insulating material for preventing heat transfer to the removal and a mechanism for cooling the CO removal unit were required.

Hereinafter, a case of a methanol reformer using methanol as a fuel will be described more specifically.

In general, a methanol reformer is a methanol reformer.
(CH_ThreeOH) and water vapor (H_TwoO) is reacted by the catalyst
Then, methanol is reacted by the reaction of the following formulas (A) and (B).
(CH _ThreeOH) to reform hydrogen (H_TwoDevice for generating
It is.

CH ₃ OH = CO + 2H ₂ −21.7 Kcal (A) CH ₃ OH + H ₂ O = CO ₂ + 3H ₂ −11.9 Kcal (B) CH ₃ OH + 1 / 2O ₂ = CO ₂ + 2H ₂ +45.3 Kcal (C) CO + 1 / 2O ₂ = CO ₂ +67.6 Kcal (D) CO + H ₂ O = CO ₂ + H ₂ +9.8 Kcal (E) Here, (A), ( As is apparent from the formula B), since the reforming reaction of methanol is an endothermic reaction, it is necessary to add heat in order to increase the amount of generated hydrogen and increase the reaction rate, and to carry out the reforming reaction. Performing part (reforming part)
It is necessary to prevent heat radiation.

Therefore, in the conventional reforming apparatus, a combustion chamber is provided adjacently to heat the reforming section, fuel gas or the like heated by a heater in advance is fed into the reforming section, or (C) A method is used in which the reforming section is heated from the inside using the reaction (autothermal). The reforming section is provided with a heat retaining material or the like to prevent heat radiation to the outside.

On the other hand, the carbon monoxide generated by the reaction (A) poisons the electrode catalyst in the fuel cell as described above and inhibits the electrode reaction. It is necessary to remove this by performing a CO removal reaction represented by formulas (D) and (E). However, (D), (E)
Is an exothermic reaction, so if heat is transferred from the reforming section to the portion for removing carbon monoxide (CO removing section), the CO removing reaction does not proceed.

[0012]

Therefore, in a reforming apparatus in which a reforming section and a CO removing section are integrally formed, heat loss in the high-temperature reforming section is prevented and CO2 is removed from the reforming section.
There was a need to suppress heat transfer to the removal section.

Further, since the reforming catalyst is usually used after being filled in a cylindrical or rectangular catalyst container, when the output of the reformer increases, the flow path cross-sectional area of the catalyst container increases, In some cases, the distribution of the fuel gas flowing inside was uneven, and a sufficient reforming reaction was not performed.

Further, in a reforming unit structure in which one catalyst container is filled with a reforming catalyst, for example, when the catalyst is partially deteriorated as a result of being used in a state where the mixed gas flows unevenly, Also, it was necessary to replace the entire reforming section.

The present invention has been made to solve these various problems. That is, the present invention prevents the heat loss due to the release of heat from the reforming catalyst to the outside while raising the temperature of the reforming catalyst, and adjusts the cross-sectional area of the reforming tube in relation to the number of reforming tubes and the output to appropriately adjust the cross-sectional area. The mixed gas is made to flow uniformly in the reforming catalyst by making the area as large as possible, and preferably, the heat transfer from the reforming section to the CO removing section is suppressed, so
An object of the present invention is to provide a small-sized reformer capable of promoting a removal reaction and generating high-purity hydrogen gas.

[0016]

According to the present invention, there is provided a reformer for converting a mixed gas (2) comprising fuel gas, steam and air into hydrogen, wherein the reformer comprises A heating unit (4) for evaporating and heating the gas;
A distribution pipe (8) for uniformly distributing the heated mixed gas toward a plurality of branch ports (6) provided at one end, and a reforming catalyst (12) for performing a reforming reaction of the mixed gas are filled. A reforming section (14), a manifold (16) having the distribution pipe inside, and a CO removal catalyst (22) for performing a CO removal reaction of the reformed gas (18) reformed in the reforming section. A reformer, the manifold, and a casing (26) for accommodating the manifold and the CO remover, wherein the reformer has one end connected to the branch port and the other end connected thereto; Pipe for releasing reformed gas from the pipe (30)
And one or more reformers (32) arranged in parallel, and a return mechanism (34) for flowing the reformed gas through the outer periphery of the reforming tube and sending the reformed gas to the manifold. I do.

The mixed gas (2) evaporated and heated in the heating section (4) is distributed in a distribution pipe (8) and sent to one or more reforming pipes (30) to be reformed in the reforming pipe. Perform the reaction.
An orifice or a sintered plate is provided at the inlet of the distribution pipe to distribute the mixed gas to the reforming pipe. When the required amount of reformed gas is small, reduce the number of reforming tubes and use a reforming tube with a slightly smaller cross-sectional area. When the volume of the reforming tube is large, the number of reforming tubes is increased and the reforming tube whose cross-sectional area is slightly larger is used to make the distribution of the mixed gas in the cross section of the reforming tube uniform and the inside of the reforming tube The mixed gas can be evenly diffused. Thereby, the mixed gas and the reforming catalyst can be efficiently contacted to promote the reforming reaction.

Further, by discharging the high-temperature reformed gas through the outer periphery of the reforming tube to the manifold (16), it is possible to suppress the release of heat from the reforming tube to the outside.

Here, it is also preferable that the CO removing section (24) communicates with the manifold (16) and is located on the opposite side of the reforming section (14) across the manifold.

In the reforming apparatus of the present invention, a reforming section (14) that performs a reaction at a relatively high temperature and a CO removing section (24) that performs a reaction at a relatively low temperature are freely connected. Therefore, for example, by sandwiching the manifold, heat transfer from the reforming section to the CO removing section is prevented, and even when the reforming section and the CO removing section are integrally formed, the reformer can be downsized. Can be planned.

Here, the return mechanism (34) is provided between the adjacent reforming tubes (30) or between the reforming tubes and the casing (26) in the axial direction of the reforming tubes. It is also preferable that the reformed gas (18) is sent to the manifold through a reformed gas flow path (36) composed of a gap.

A gap formed between adjacent reforming pipes (30) or between the reforming pipe and the casing (26) is used as a reforming gas flow path (36), and a high-temperature reforming gas is used. (18) is flowed around the outer periphery of the reforming tube, and the manifold (16)
High-temperature reforming gas on the outer periphery of the reforming tube to efficiently suppress heat radiation from the reforming tube to the outside, and eliminate the need for special piping for sending reformed gas to the manifold. Can be simplified.

It is also preferable that the reforming tube (30) can be removed and replaced.

The reforming tube (3) filled with the reforming catalyst (12)
0) is unitized, so inspection and
Replacement is possible, and maintenance is also improved.

Further, a fuel trap section (38) for removing fuel gas in the reformed gas (18) may be provided between the manifold (16) and the CO removing section (24).

The manifold (16) and the CO removing unit (2)
4), the fuel trap which has not been reformed in the reforming section flows into the CO removing section, and the fuel gas is deposited on the CO removing catalyst.
Prevents the inhibition of the selective oxidation reaction and CO shift reaction, efficiently removes CO, prevents heat transfer from the reforming section (14) to the CO removing section, and furthermore, the reformed gas in the fuel trap section. The cooling of (18) can be performed.

Further, it is preferable that a supply pipe (42) for supplying oxygen, air or steam to the reformed gas (18) sent from the manifold (16) to the CO removing section (24) is provided.

Oxygen (air) or water vapor is supplied to the reformed gas (18), and the oxygen is supplied to the CO removal unit, whereby the CO selective oxidation reaction (CO + 1 / 2O ₂ → C) is performed.
O ₂ ) and oxygen and water vapor required for the CO shift reaction (CO + H ₂ O → CO ₂ + H ₂ ) can be sufficiently supplied, and at the same time, the reforming gas is cooled to suppress a rise in the temperature of the CO removing section. The CO removal reaction can be promoted.

Here, the CO removing section (24) is composed of one or more sections, and oxygen,
Supply pipes (42a, 42b,...) For supplying air or steam
..).

For example, the CO removing section is divided into two sections, and a supply pipe for supplying steam is provided before the preceding section filled with a catalyst suitable for the CO shift reaction, and a catalyst suitable for the CO selective oxidation reaction is provided. By providing a supply pipe for supplying oxygen in front of the compartment after the filling, CO2 can be more effectively reduced.
By performing the removal reaction, a reformed gas (purified gas) having higher hydrogen purity can be obtained.

[0031]

Preferred embodiments of the present invention will be described below with reference to the drawings. In addition, the same reference numerals are given to the common parts in the respective drawings, and the duplicate description will be omitted.

FIG. 1 is a schematic view showing an overall image of the reforming apparatus of the present invention, and FIG. 2 is a sectional view taken along line XX of FIG.

The present invention is a reformer for converting a mixed gas 2 composed of fuel gas, steam and air into hydrogen, which is intended to be mounted on an automobile or the like as a hydrogen supply source for a fuel cell. It is.

Hereinafter, the case where the reformer of the present invention is applied to the production of hydrogen using methanol, which is expected to stabilize the supply and reduce the price, will be described.

The reforming apparatus 10 of the present invention is roughly divided into a heating section 4, a reforming section 14, a manifold 16, a CO removing section 24, and a casing 26. The reforming unit 14, the manifold 16 and the CO removing unit 24 are integrally housed in a cubic casing 26, thereby forming the reforming apparatus main body 10a.

Here, a combustion fuel pipe (not shown) to which combustion fuel is supplied is connected to the heating section 4, and the heat generated when the combustion fuel is burned is used as a heat source to convert the mixed gas. Evaporation and heating are the same as in the prior art, and a detailed description of the heating unit 4 will be omitted.

The heating section 4 mixes methanol, water and air to form a mixed gas 2, which is evaporated to about 200 ° C.
The temperature is raised to a degree and sent to the distribution pipe 8 communicating with the reformer main body 10a. The distribution pipe 8 branches inside the manifold 16 of the reformer main body 10a, and each branch is provided with an orifice (not shown) in its path so that an equal amount of the mixed gas 2 is distributed. . All of the branch ports 6 located at the ends of the branched distribution pipes 8 communicate with the reformer 32.

The reformer 32 is formed by connecting the cylindrical reformer tube 30 to 9
It is arranged in three rows and three rows in parallel. One end of each reforming pipe 30 communicates with the branch port 6 of the distribution pipe 8, and the other end is opened in the casing 26. Here, individual reforming tubes 30
Can be removed and replaced.

The upstream of each reforming tube is filled with the partial oxidation catalyst 28 for performing the reaction (C), and the middle and downstream sides are filled with the reforming catalyst 12 for performing the reforming reaction. Have been.

A reformed gas passage 36 is formed between the adjacent reforming tubes 30 and between the reforming tube and the casing 26. The reformed gas passage 36 has a gap in the axial direction of the reforming tube. It leads to manifold 16.

The high-temperature mixed gas 2 sent from the heating unit 4 to the distribution pipe 8 is distributed equally as shown by an arrow a, and then goes to each branch port 6 located at the end of the distribution pipe 8 branched. Flowing. Each branch port 6 is joined to the reforming pipe 30 in an airtight state, and the mixed gas 2 flows into each reforming pipe 30 from each branch port 6 and moves through the reforming pipe 30. The mixed gas 2 raises the temperature to a temperature suitable for the reforming reaction by performing a partial oxidation reaction on the upstream side of the reforming tube 30 and heats the reforming catalyst 12, and contacts the reforming catalyst on the middle and downstream sides. In this manner, a reforming reaction is performed to generate a hydrogen-rich reformed gas (autothermal method).

Here, by uniformly distributing and sending the high-temperature mixed gas 2 to each reforming tube 30 having an appropriate cross-sectional area, one catalyst container is filled with the same amount of reforming catalyst and mixed therein. As compared with the case where gas is supplied, unevenness of the mixed gas flow in the reforming catalyst is suppressed, and the reforming reaction can be performed efficiently.

The reformed gas 18 having passed through the reforming tube 30 and having undergone the reforming reaction escapes from the end of the reforming tube and changes its direction by 180 ° as shown by the arrow b in FIG. Gas flow path 3
6 and moves to the manifold 16 communicating with the reformed gas flow path 36.

Here, the mixed gas flowing through the reforming catalyst undergoes a reforming reaction as an endothermic reaction, and after a certain temperature drop, becomes a reformed gas and escapes from the end of the reforming tube, but still has a high temperature. By flowing the reformed gas 18 through the reformed gas flow path 36 while contacting the outer periphery of the reforming tube 30, heat radiation from the reforming catalyst 12 to the outside can be suppressed. Therefore, it is not necessary to adopt a special heat retaining structure in the reforming section 14.

The manifold 16 collects the reformed gas sent from each reformed gas passage, and spreads over the entire cross-sectional surface of the paper in the casing 26 shown in FIG.
In order to isolate between the CO removal unit 24 and a CO removal unit 24 described later, the unit also plays a role of preventing heat transfer from the reformed body 32 to the CO removal unit 24.

Between the manifold 16 and the CO removing unit 24, a fuel trap unit 38 for removing the fuel gas that has not been reformed in the reforming unit 14 is provided, and the fuel trap unit 38 collected in the manifold 16 is provided. Unreacted fuel gas in the raw gas 18 is captured by the fuel trap section. This fuel trap portion is adjacent to the manifold 16 and has a passage port 46 communicating with the manifold at the lower end thereof, and like the manifold, extends over the entire cross-sectional direction of the paper in the casing 26 shown in FIG. Unreacted fuel gas in the reformed gas is removed while the reformed gas moves upward from below the fuel trap section 38. The removed fuel gas is discharged to the outside from a waste pipe (not shown), and is discarded or reused as fuel for combustion in a heating unit. Here, the fuel trap section 38 also plays a role of isolating the reformed body 32 and the CO removing section 24.

The reformed gas 18 that has passed through the fuel trap section 38 is fed to the fuel trap section 3 above the fuel trap section.
8 flows into a narrow space 48 provided adjacent to the space 8. The supply pipe 42 for supplying air or oxygen from the outside to the narrow space 48
The reformed gas 18 passing through the fuel trap 38 and the air or oxygen supplied from the supply pipe 42a are mixed in this narrow space. Thereby, the reformed gas 1
At the same time, the oxygen required for the later-described CO selective oxidation reaction is supplied.

The narrow space 48 is connected to the CO removing section 24 below the narrow space 48, and the reformed gas 18 mixed with air or the like.
Flows into the CO removal unit from here. As shown in the figure, the CO removing unit 24 is divided into two sections, a front section and a rear section, and a supply pipe 42b for supplying air or oxygen from the outside is introduced between the front section and the rear section. ing. The CO removal section is divided, air or oxygen is supplied before each section, CO removal reaction is performed in multiple stages, and the temperature rise near the upstream of the CO removal catalyst where the CO removal reaction mainly progresses is dispersed to remove CO. By suppressing a partial excessive rise in temperature of the catalyst, a CO removal reaction that is an exothermic reaction can be efficiently performed.

The first and second stages are filled with a catalyst (for example, Ru or the like) which is optimal for the selective oxidation reaction of CO.

Cooling pipes 52a and 52b for cooling the catalyst by circulating, for example, cold water or air from the outside are introduced into the upstream of the front and rear sections. This is a reaction in which the CO selective oxidation reaction generates a large amount of heat (CO + 1 / 2O ₂ = CO ₂ +67.6 Kca).
1) This is for cooling the upstream portion of the CO removal catalyst in which this reaction mainly proceeds to promote the above reaction to the right.

The reformed gas 18 from which the carbon monoxide has been sufficiently removed by performing the CO selective oxidation reaction in the CO removing section 24 becomes a purified gas 54 and a purified gas outlet 56 provided below the latter part.
It then flows out and is supplied to the hydrogen electrode (anode: not shown) of the fuel cell.

It should be noted that the present invention is not limited to the above-described embodiments, but can be variously modified without departing from the gist of the present invention.

[0053]

As described above, according to the reforming apparatus of the present invention, the gas mixture flowing through the reforming catalyst is uniformly distributed through one or more reforming tubes having an appropriate cross-sectional area. The reforming reaction can be sufficiently performed by eliminating the bias and efficiently bringing the mixed gas into contact with the reforming catalyst. Also,
By flowing a high-temperature reforming gas around the reforming tube, heat radiation from the reforming catalyst to the outside can be suppressed, and by preventing heat loss, a reforming reaction, which is an endothermic reaction, can be promoted. More preferably, the purification gas is prevented by interposing a manifold or the like between the reforming section and the CO removing section to prevent heat transfer from the reforming section to the CO removing section and promoting the CO removing reaction which is an exothermic reaction. The concentration of carbon monoxide therein can be sufficiently reduced, and the reformer can be reduced in size.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a structure of a reformer according to one embodiment.

FIG. 2 is a view taken in the direction of arrows XX in FIG.

[Explanation of symbols]

 2 mixed gas 4 heating section 6 branch port 8 minute pipe 10 reformer 10a reformer main body 12 reforming catalyst 14 reforming section 16 manifold 18 reformed gas 22 CO removal catalyst 24 CO removal section 24a front section 24b rear section 26 Casing 28 Partial oxidation catalyst 30 Reforming pipe 32 Reforming body 34 Recirculation mechanism 36 Reformed gas flow path 38 Fuel trap part 42, 42a, 42b Supply pipe 46 Passage port 48 Narrow space 52a, 52b Cooling pipe 54 Purified gas 56 Purification Gas outlet

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01M 8/06 H01M 8/06 A (72) Inventor Katsumi Takahashi 1 Ishikawajima, Shinnakahara-cho, Isogo-ku, Yokohama-shi, Kanagawa Harima Heavy Industries, Ltd. Machinery and Plant Development Center F-term (reference) 4G040 EA02 EA03 EA06 EB03 EB12 EB31 EB46 4G140 EA02 EA03 EA06 EB03 EB12 EB31 EB46 5H027 AA02 BA01 BA17

Claims (7)

[Claims] 1. A reformer for converting a mixed gas (2) consisting of fuel gas, water vapor and air into hydrogen, wherein the reformer comprises: a heating section (4) for evaporating and heating the mixed gas; Distribution pipe (8) for evenly distributing the mixed gas to a plurality of branch ports (6) provided at one end
A reforming section (14) filled with a reforming catalyst (12) for performing a reforming reaction of the mixed gas; a manifold (16) having the distribution pipe inside; A CO removing unit (24) filled with a CO removing catalyst (22) for performing a CO removing reaction of the reformed gas (18), and a casing (26) containing the reforming unit, the manifold and the CO removing unit. A reforming unit (32) in which one or more reforming tubes (30) each having one end connected to the branch port and releasing the reforming gas from the other end are arranged in one or in parallel. A return mechanism (3) for flowing the reformed gas through the outer periphery of the reforming tube and sending the reformed gas to the manifold.
4). 2. The CO removal section (24) is in communication with the manifold (16) and is located on the opposite side of the manifold from the reforming section (14). The reforming apparatus according to item 1. 3. The recirculation mechanism (34) is provided between the adjacent reforming tubes (30) or between the reforming tubes and the casing (26) in the axial direction of the reforming tubes. The reformed gas (1) is passed through a reformed gas flow path (36) comprising a gap.
The reformer according to claim 1 or 2, wherein 8) is sent to the manifold. 4. The reforming apparatus according to claim 1, wherein the reforming pipe is removable and can be replaced. 5. The manifold (16) and the CO
The reformer according to any one of claims 1 to 4, wherein a fuel trap (38) for removing fuel gas in the reformed gas (18) is provided between the reformer and the remover (24). . 6. The method according to claim 1, wherein said manifold (16) and said C
Oxygen is added to the reformed gas (18) sent to the O removal unit (24).
6. The reformer according to claim 1, further comprising a supply pipe for supplying air or steam. 7. The CO removing section (24) is composed of one or more sections, and supply pipes (42a, 42b,...) For supplying oxygen, air or water vapor upstream of each section.
The reformer according to claim 6, further comprising: ().