JPH07187601A - Reactor for methanol reforming - Google Patents

Abstract

(57) [Summary] [Structure] In a methanol reforming reactor for reacting a mixed vapor of methanol and water in the presence of a catalyst, the height of the methanol reforming catalyst is set to one side of a vertical spiral heat exchanger. -80% is filled to pass a mixed vapor of methanol and water, and a heating fluid is passed to the other side. [Effect] Since the temperature distribution of the catalyst layer is uniform and the temperature drop is small when heated in the space, the catalyst is effectively used, and since the high temperature part is eliminated, the amount of carbon monoxide produced is reduced. The catalyst life is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a methanol reforming reactor for producing hydrogen gas by efficiently reacting methanol and water with a small apparatus.

[0002]

2. Description of the Related Art Hydrogen gas has been used in many industrial fields such as reforming and desulfurization in the petroleum refining industry, various kinds of synthesis in the chemical industry, hydrogenation, etc., and recently, the electronic industry, food industry, With the addition of new fields such as fuel cells, the fields of use are increasing. In the production of hydrogen gas using methanol as a raw material, recently, since it is easy to transport and store the raw material methanol, and the reaction is easily performed at a relatively low temperature, it has recently become adjacent to a hydrogen consuming device. Installation of a methanol reformer and unmanned operation are being considered. A multi-tube heat exchanger is usually used in this methanol reforming reactor, and a method of filling the inside of the reaction tube with a catalyst and heating from outside with combustion gas, heat transfer oil, steam, etc. is adopted. However, in order to carry out the reaction efficiently with a device as small as possible, for example, JP-A-61-286204 and JP-A-62
-160134, JP-A-63-166701 and the like describe the use of a plate heat exchanger, and JP-A-63-252.
No. 01 describes the use of a spiral heat exchanger.

[0003]

Problems to be Solved by the Invention The methanol reforming reaction is represented by the following reaction formula, and in addition to the main reaction of formula (1), (2)
The reverse shift reaction of the formula occurs, the produced hydrogen is consumed and carbon monoxide is a by-product. Therefore, the methanol reforming reactor has the following characteristics. CH ₃ OH + H ₂ O = CO ₂ + 2H ₂ (1) CO ₂ + H ₂ = CO + H ₂ O (2) It is necessary to raise the reaction temperature in order to increase the decomposition rate of methanol. In order to reduce the amount of carbon monoxide that is difficult to separate from the reformed gas, keep the reaction temperature as low as possible and
It is desirable to increase the molar ratio of methanol. From the viewpoint of energy efficiency of the reactor, it is required to keep the water / methanol molar ratio as close to the theoretical amount as possible and to keep the decomposition rate of methanol high. Generally, a copper-based catalyst is used as the catalyst, but in order to keep the catalyst life long, it is desirable to keep the reaction temperature as low as possible. Therefore, a catalyst having a high activity at a relatively low temperature has been developed, and the most advantageous reaction temperature has been selected from the above contradictory conditions.

In a multi-tube heat exchanger generally used in a reactor for reforming methanol, an endothermic reaction according to the formula (1) occurs rapidly at the inlet of the catalyst layer, which is a gas phase reaction. Is a heat transfer rate-determining factor, so that a temperature drop of about 10 to 60 ° C. usually occurs at the inlet of the catalyst layer with respect to the inlet temperature of the reaction tube. Due to this decrease in temperature, the catalyst at the inlet cannot be used effectively, and at the same time, there is a risk that moisture in the supply gas will condense and damage the catalyst. It is generally done to raise. However, increasing the temperature at the inlet of the reaction tube increases the temperature of the entire catalyst layer. Therefore, as described above, the amount of carbon monoxide produced increases due to the reaction of equation (2), and the yield of hydrogen decreases. And the shortening of the catalyst life.

[0005]

Means for Solving the Problems As a result of diligent studies on the methanol reforming reactor having the above-mentioned problems, the present inventors have used a reactor of a vertical spiral heat exchanger and have a space above the catalyst packing part. If the section is installed, the gas supplied to the catalyst layer is heated in this space, the temperature decrease at the catalyst layer inlet is reduced, and the methanol reforming catalyst is effectively used. The present invention has been accomplished by finding that the amount of carbon oxide produced is reduced.

That is, according to the present invention, in a methanol reforming reactor for reacting a mixed vapor of methanol and water in the presence of a catalyst, a methanol reforming catalyst having a height of 20 to 80 is provided on one side of a vertical spiral heat exchanger. % To allow a mixed vapor of methanol and water to pass through, and a heating fluid to pass through to the other side.

In the present invention, in order to effectively heat the catalyst layer inlet gas, it is desirable to fill the space in the upper portion of the catalyst filling portion with a filling material. The molar ratio of water to methanol in the methanol reforming reaction is usually in the range of 1 to 5, and the space velocity of these mixed vapors relative to the catalyst is 10
It is ⁰ to 15000 hr ^-1 . The reaction temperature is usually 20
The pressure is in the range of 0 to 350 ° C, and the pressure is normal pressure to 30 kg / cm ^2.
G.

The spiral heat exchanger used in the reactor for reforming methanol of the present invention has a structure as shown in, for example, FIG. 1 (elevation view) and FIG. 2 (plan view). First, the reaction gas heating fluid is supplied from the flow path 1 in FIG.
Through which the reaction gas in the catalyst layer and the space above it is heated, and discharged from the flow path 6. On the other hand, the mixed vapor of methanol and water supplied to the reactor is supplied to the flow path 7 in FIG. 2 and heated in the space 8 in FIG. 1, and then the methanol reforming reaction is performed in the catalyst layer 9.
Although the temperature of the reaction gas decreases due to this reforming reaction, it is then heated in the space 10 and enters the catalyst layer 11. The reaction gas is sequentially heated in the space 12, the reforming reaction in the catalyst layer 13, and the heating and reforming reactions are repeated, and the reaction gas is discharged from the flow path 14.

In the present invention, the amount of the catalyst filled in the catalyst filled portion is 20 to 80%, preferably 30 to 70%, and more preferably 40 to 50% with respect to the total volume of the catalyst filled portion. It is desirable to fill a space such as a metal sphere or a Raschig ring in the space above the catalyst filling portion in order to improve heat transfer efficiency. If the catalyst is 40 to 50%,
Since the catalyst can be filled by removing the upper cover, the catalyst can be easily replaced.

The heating fluid for the reaction gas is not particularly limited, but a heat transfer oil (such as Dawtham), combustion gas, and heating steam are generally used. In the present invention, since the temperature of the heating fluid can be lowered as compared with the conventional case, the pressure of the heating steam can be lowered. Further, in the present invention, since the temperature distribution of the catalyst layer is made uniform, the catalyst can be effectively used, so that the catalyst amount can be significantly reduced, and the CO generation amount can be reduced. The catalyst life is extended.

[0011]

EXAMPLES Next, the present invention will be described more specifically by way of examples. However, the present invention is not limited to this embodiment.

Example 1 50% of the height of each layer on one side of the heat exchange part of the spiral heat exchanger (six spirals 6 layers, outer diameter 0.5 m, width 0.5 m) shown in FIGS. 1 and 2 was filled with a copper catalyst. Then, a mixed vapor of methanol and water (molar ratio 1: 2) 90 Nm ³ / H was added at a pressure of 15
Hydrogen was produced by supplying kg / cm ² G at a temperature of 240 ° C. and then supplying a heat transfer oil (Dawtham) as a heating fluid to the other side at 260 ° C. The temperature distribution of the heating fluid (heat medium) and the catalyst layer is shown in FIG. The decomposition rate of methanol was 99.0%, and the CO concentration in the produced gas was 0.6%.

Comparative Example 1 In the spiral heat exchanger of Example 1, one side of the heat exchange section of the reactor having a width of 0.25 m in order to obtain an equal amount of catalyst,
The same catalyst was filled to a height of 100%, and a mixed vapor of methanol and water (molar ratio 1: 2) 90 Nm ³ / H was added at a pressure of 15
Hydrogen was produced by supplying kg / cm ² G and a temperature of 260 ° C., and supplying a heat transfer oil (Dawtham) as a heating fluid to the other side at 280 ° C. The temperature distributions of the heating fluid (heat medium) and the catalyst layer are shown in FIG. The decomposition rate of methanol was 99.0%, and the CO concentration in the produced gas was 0.6%.

[0014]

As shown in the examples, in the methanol reforming reactor of the present invention, the temperature distribution of the catalyst layer is uniform, and the temperature drop is small due to the heating in the space, so the catalyst is effectively used. Therefore, the temperature of the heating fluid can be lowered. This makes it possible to use lower pressure steam or a lower temperature heat source as the heating fluid. Further, since the high temperature portion is eliminated, the production amount of carbon monoxide is reduced and the catalyst life is improved. Further, the amount of catalyst can be greatly reduced by the methanol reforming reactor of the present invention, and the catalyst can be easily charged. Therefore, the methanol reforming reactor of the present invention is an industrially extremely advantageous device.

[Brief description of drawings]

Figure 1: Elevation

FIG. 2 is a plan view showing an example of the structure of the methanol reforming reactor of the present invention.

FIG. 3 shows temperature distributions of a heating fluid (heating medium) and a catalyst layer in Example 1.

FIG. 4 shows temperature distributions of a heating fluid (heating medium) and a catalyst layer in Comparative Example 1.

[Explanation of symbols]

 1 Heating fluid (heat medium) inlet 2-5 Heating fluid (heat medium) passage 6 Heating fluid (heat medium) outlet 7 Raw material gas (mixed vapor of methanol and water) inlet 8,10,12 Space portion 9, 11,13 Catalyst filling part (catalyst layer) 14 Reactant gas outlet

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] January 7, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

Example 1 50% of the height of each layer on one side of the heat exchange part of the spiral heat exchanger (six spirals 6 layers, outer diameter 0.5 m, width 0.5 m) shown in FIGS. 1 and 2 was filled with a copper catalyst. Then, a mixed vapor of methanol and water (molar ratio 1: 2) 90 Nm ³ / H was added at a pressure of 15
Hydrogen was produced by supplying kg / cm ² G at a temperature of 240 ° C. and then supplying a heat transfer oil (Dawtham) as a heating fluid to the other side at 260 ° C. The temperature distribution of the heating fluid (heat medium) and the catalyst layer is shown in FIG. The decomposition rate of methanol was 99.0%, and the CO concentration in the produced gas was 0.3%.

Claims (2)

[Claims] 1. A methanol reforming reactor for reacting a mixed vapor of methanol and water in the presence of a catalyst, wherein the methanol reforming catalyst is provided at a height of 20 on one side of a heat exchange section of a vertical spiral heat exchanger. A reactor for methanol reforming, which is filled up to 80% to allow a mixed vapor of methanol and water to pass therethrough and to pass a heating fluid to the other side of the heat exchange section. 2. The reactor for reforming methanol according to claim 1, wherein the catalyst for reforming methanol is filled with a filler for heat transfer.