JP2803266B2 - Methanol reforming reactor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an improvement in a methanol reforming reaction apparatus for producing a reformed gas containing hydrogen as a main component by a steam reforming (reforming) reaction of methanol.

(Prior art) A method for producing a reformed gas mainly composed of hydrogen using methanol as a raw material is easy to transport and store the raw material methanol, and the reforming reaction can be easily performed at a relatively low temperature. Since hydrogen gas of desired quality can be produced very easily, it has been adopted not only in the chemical industry, but also in new industries such as the electronics industry, food industry, and fuel cell power generation. Have been.

The mixed vapor of methanol and water undergoes a methanol decomposition reaction and a CO denaturation reaction by a catalyst in the reforming reactor to become a reformed gas containing hydrogen as a main component.

CH ₃ OH CO + 2H ₂ -23.5kcal / mole CO + H ₂ OCO ₂ + H ₂ + 8.7kcal / mole CH ₃ OH + H ₂ OCO ₂ + 3H ₂ -14.8kcal / mole Methanol reforming (decomposition) is an endothermic reaction In some cases, the amount of heat required for the reforming reaction must be supplied by a method of externally heating the reaction tube filled with the catalyst. Generally, the supply of the heat of reaction, that is, the heating of the reaction tube, is performed by a hot oil flowing outside the catalyst tube. The heating method using heat transfer oil has the characteristics that the overall heat transfer coefficient is large, the reactor can be designed compact, and the control of the reaction temperature is extremely easy. Has been put to practical use. However, in addition to the reactor and reactor, additional equipment such as a heat transfer oil boiler and heat transfer pump is required.
There is a drawback that the reforming reactor becomes considerably complicated and expensive.

If a combustion gas generator is incorporated into the reforming reactor (tube) as an integrated device and the catalyst tube is designed to be heated directly by the combustion gas without using a heating medium oil, the heating medium oil boiler Since there is no need for ancillary equipment such as the above, the reforming reaction device becomes extremely simple, and various proposals have already been made as a fuel reforming device for a fuel cell, an on-board reforming device for a methanol fueled vehicle, etc. Kosho 54-23683
No., JP-A-62-70202, JP-A-62-260701, JP-A-62
3-138301, JP-A-63-138306, etc.). However, the heating of the catalyst tube by the combustion gas has an extremely small overall heat transfer coefficient of 1/10 or less as compared with the case of using the heat transfer oil, and the heat transfer efficiency,
In addition, a combustion gas having higher heat is required in terms of load followability. When the temperature of the combustion gas as the heat medium is increased, a catalyst having more excellent heat resistance is required. Proposals for heat-resistant catalysts containing a noble metal such as platinum as an active ingredient have already been made, but have the disadvantage that they are extremely expensive and that there are many by-products (CO gas).

On the other hand, copper-based catalysts, which have already been awarded as methanol reforming catalysts, are highly active at low temperatures, have few by-products, have a long catalyst life, and are inexpensive, making them ideal as industrial catalysts. However, it has features and characteristics such as low heat resistance. As a countermeasure, for example, a reactor filled with catalysts having different heat resistances (300 ° C, 520 ° C) is arranged in series (Japanese Patent Publication No. 57-42678), or a large amount of secondary air is mixed with high-temperature combustion gas. Using low-temperature combustion gas (380 ° C.) obtained as a heating catalyst (JP-A-60-246201)
No.) has been proposed.

[Problems to be solved by the invention]

In the above method, the catalyst life is prolonged and the operability is improved, but the reformer becomes complicated and the downsizing is difficult due to the use of two reactors. Is expected to be considerably improved,
Since a large amount of secondary air is required, the required power is large, and it is presumed that it is extremely difficult to obtain inexpensive hydrogen gas.

In general, from the viewpoints of pollution prevention and energy saving, kerosene and / or methanol and / or a hydrogen purifier (PS) are used as fuel for a combustion gas generator.
A) Purge gas is used. However, in general,
Usually, at the time of startup, the composition of the combustion gas is different because the purge gas cannot be used, and the heat transfer coefficient outside the tube changes.
In addition, when the load fluctuates, the heat transfer coefficient inside and outside the pipe changes, so it is difficult to control the temperature distribution of the catalyst layer within the optimum operating temperature range of the reforming catalyst, and to maximize the performance of the reforming catalyst. There is a drawback that it cannot be demonstrated.

[Means for solving the problem]

The inventor has conducted extensive studies on the modification and arrangement of the components of the methanol reformer using combustion gas as a heat medium, and on the relationship between these components and the overall heat transfer coefficient. As a result, the raw material evaporator was replaced with the raw material evaporator ( 1) and a raw material evaporator (2), and the raw material evaporator and the reforming reactor are configured as a plurality of vertical tube groups, and the raw material evaporators (1), A raw material superheater, a reforming reactor, and a raw material evaporator (2) were installed. First, a high-temperature combustion gas was used as a heat source for the raw material evaporator (1) and a raw material superheater, and then the temperature dropped. Each device is arranged so that the medium-temperature combustion gas is used as a heat source of the reforming reactor, and finally, the low-temperature combustion gas whose temperature is further reduced is used as a heat source of the raw material evaporator (2). The temperature of the catalyst layer of the reforming reactor, in other words, the reaction The temperature distribution of the catalyst layer can be extremely easily and precisely adjusted by changing the distribution and supply ratio of the raw material methanol-water mixture to the raw material evaporator (1) and the raw material evaporator (2). It has been found that the temperature can be controlled within a predetermined temperature range. The present inventor has made intensive studies on the basis of this finding and completed the present invention.

Hereinafter, the present invention will be described more specifically based on a basic configuration diagram. FIG. 1 and FIG. 2 are basic structural diagrams of a methanol reforming reaction device according to the present invention, and are specific examples of preferred embodiments.

A raw material methanol-water mixture supplied from a raw material storage tank (omitted in FIG. 1) through a metering pump (omitted in FIG. 1) and a flow path 12 is supplied to a flow path 13 and a flow path Branched and split into 14. The raw material methanol-water mixture branched and divided into the flow path 14 is guided to the raw material evaporator (1) 2 through the flow control valve A and the mixed solution header (1) 3, and is heated by the high-temperature combustion gas. It is heated and evaporated and vaporized, and is led to the raw material mixed gas inlet header 8 via the raw material gas header (1) 4 and the raw material gas superheater 5. On the other hand, the raw material methanol-water mixed liquid branched and divided into the flow path 13 is guided to the raw material evaporator (2) 9 via the mixed liquid header (2) 10, and heat is supplied to the reforming reaction tube group. Is heated and evaporated and vaporized by the low-temperature combustion gas that has been subjected to the heat treatment, is led to the raw material gas header (1) 4 through the raw material gas header (2) 11, and a part of the raw material is superheated through the flow control valve B. Into the superheated gas from the vessel 5. Raw material gas header (1) 4
The raw material gas mixed in step (1) is led to the raw material superheater 5 and is heated by the high-temperature fuel gas to become a superheated gas. The superheated gas is combined with or mixed with the raw material gas from the flow control valve B, or is adjusted and controlled to the optimum temperature range for the reforming reaction without being combined and mixed, and is reformed through the raw material mixed gas inlet header 8. The reaction gas is led to the reaction tube 6 to cause a reforming reaction to become a reaction product gas.

The reaction product gas generated by the reforming reaction is taken out as a reaction product gas through the reaction gas outlet header 7 and the flow path 18 and sent to the next step to be purified or used as it is.

As described above, the high-temperature combustion gas generated by the combustion gas generator 1 is first vaporized and vaporized in a raw material methanol-water mixture in a raw material evaporator (1) 2 and then in a raw material superheater 5. Is heated to become a medium-temperature combustion gas and is led to the reforming reaction tube group 6. The medium-temperature combustion gas overheats the reforming reaction tube group to give reaction heat, and becomes a low-temperature combustion gas. The low-temperature combustion gas passes through the passage 15 and is fed to the raw material evaporator
After being supplied to 9 and giving the remaining amount of heat as latent heat of vaporization of the raw material methanol-water mixture, it is discharged from the flow passage 16 into the atmosphere.

When practicing the present invention, as illustrated in FIGS. 1 and 2, the raw material evaporator (1), the raw material superheater, and the reforming reaction tube are placed inside the same concentric cylindrical container. A raw material evaporator (1) and a raw material superheater are arranged, a reforming reaction tube is arranged outside the raw material evaporator (1), and a partition wall 17 is provided between the raw material evaporator (1) and the reforming reaction tube so as to be isolated and improved. It is preferable to prevent direct contact of the high-temperature combustion gas to the quality reaction tube and to regulate the flow path of the combustion gas so that a temperature gradient is clearly provided in the flow direction of the combustion gas. Further, the raw material evaporator (2) may be installed in the same cylindrical container as the reforming reaction tube and the like, but it is easier and simpler to install it in a separate cylindrical container.

When carrying out the present invention, the combustion gas generator 1 is generally arranged at the upper part in a concentric cylindrical container from the viewpoint of ease of maintenance, as illustrated in FIG. Therefore, usually, the flow direction of the combustion gas is as follows. First, after flowing through the inner cylinder from the bottom to the top and applying heat to the raw material evaporator (1) and the raw material superheater to reach a medium temperature, the reforming reaction tube group section Although it is designed to flow from the top to the bottom, it is not necessarily limited to this, and the order of the flow direction of the combustion gas may be reversed by arranging the combustion gas generator at the lower part if desired. In addition, the flow directions of the combustion gas and the reaction gas in the reforming reaction tube group are generally preferably co-current from the viewpoint of the reforming reaction rate, that is, the heat absorption rate, but depending on the heat resistance performance of the catalyst, the flow is countercurrent. It may be optional.

The raw material evaporator (1) and the reforming reaction tube are located at predetermined positions on a concentric circle in a concentric vessel, and the raw material superheater is located around a combustion gas generator above the raw material evaporator (1). It is preferable to arrange spirally in the combustion gas flow path. It is preferable to install the raw material evaporator (2) in a cylindrical container separate from the reforming reaction tube because it is easy to manufacture, simple and convenient.

Hereinafter, a preferred example in which the embodiment of the present invention is implemented using the reforming reaction apparatus shown in FIG. 1 will be described. The embodiments illustrated below are merely for specifically describing the effects of the present invention, and do not limit the technical scope of the present invention.

Embodiment 1 Hereinafter, the present invention will be described in more detail with reference to an embodiment implemented using the reformer shown in FIG. In the following examples, after adding alumina sol to a coprecipitate prepared by a coprecipitation method using copper nitrate and zinc nitrate as raw materials and calcining 3.0
Copper-zinc-aluminum-based catalyst formed into a cylindrical shape of φ × 3.0 mm (catalyst composition atomic ratio Cu: Zn: Al = 1.00: 0.75: 0.2
5, refer to Example 1 of JP-A-59-189937), and replace each of the two reforming reaction tubes (48 tubes) with a nominal diameter of B1 / 4 inch and a length of 2.4 m.
And an activated methanol reforming catalyst which was activated by reducing the catalyst with hydrogen gas according to a conventional method.

The first embodiment is a case where only kerosene is used as fuel for the combustion gas generator 1, and assumes a cold start of the device. First, after the inside of the device was replaced with hydrogen gas, the combustion gas generator 1 was ignited according to a conventional method. About 30 minutes after the apparatus is gradually warmed, the temperature of the reforming catalyst layer becomes 230 to 250 ° C., and the temperature of the reformed gas outlet header 8 becomes 25
The temperature reached 0 ° C.

Here, the fuel flow rate was set to 0.9 kg / h, and the raw material methanol-water mixed liquid supply pump (omitted in FIG. 1) was started to start the raw material methanol-water mixed liquid (mixed molar ratio).
CH ₃ OH: H ₂ O = 1.0: 1.5) is divided and divided into a preheater (omitted in FIG. 1; preheat temperature 100 ° C.), a flow path 13 and a flow path 14 via a flow path 12. And the raw material evaporator (2) 9 via the mixed liquid header (2) 10
The reforming reaction was started by supplying (flow rate 10.0 kg / h) to the raw material evaporator (1) 2 via the flow control valve A and the mixed liquid header (1) 3.

Then, while maintaining the gas pressure (reforming reaction pressure) of the reforming reaction system at 10 at in a conventional manner, gradually increase the fuel flow rate and the raw material methanol-water mixed liquid flow rate to increase the raw material methanol-water mixed liquid flow rate. Was set to 23.6 kg / h. During this time, the wall temperature of the reforming reaction tube should not exceed 360 ° C.
Also, the flow control valves A,
Preparation and control of the flow rate control valve B and the fuel flow rate were performed.

In this way, about 55 minutes after the supply of the raw material methanol-water mixture was started, the operation state of the apparatus became a steady state, and a reformed gas of 41 Nm ³ / h was generated every hour.

Subsequently, the reforming reaction experiment was continued for 36 hours while maintaining the steady state, and the results (average values) shown in Tables 1 and 2 were obtained. The evaporation rate (average value) of the raw material evaporator (1) and the raw material evaporator (2) in this experiment was 12: 1, and the methanol conversion rate (average value) was 99%. The fuel consumption (average value) is 1.9 kg / h, and the temperature distribution of the reforming reactor catalyst layer is 230-259 ° C in the length direction of the catalyst layer.
The fluctuation range was substantially constant at 10 to 20 ° C. In addition,
Heat loss from the cylindrical wall of the reforming reactor is approximately 670 kca
l / h.

Example 2 Example 2 is a case in which a purge gas from a hydrogen gas purification device (pressure swing adsorption purification method) and kerosene are used in combination as fuel for the combustion gas generator 1, and it is assumed that the device is in normal normal operation. It was done.

In Example 1, a purge gas from a hydrogen gas purifier and kerosene were used in combination as the fuel for the combustion gas generator 1 instead of kerosene alone, and the raw material methanol-water mixture flow rate was 59.0%.
A continuous reforming reaction for 72 hours was carried out in the same manner as in Example 1 except that the gas was changed to kg / h, and the reformed gas of 100 Nm ³ / h per hour and the results shown in Tables 3 and 4 were obtained. The result (average value) was obtained. In this experiment, the evaporation rate (average value) of the raw material evaporator (1) and the raw material evaporator (2) was 4.3: 1, and the methanol conversion rate (average value) was 98%. The fuel consumption (average value) is 34 Nm ³ / h for purge gas and 1.3 kg / h for kerosene.
The temperature distribution of the reforming reactor catalyst layer was 230 to 266 ° C. in the longitudinal direction of the catalyst layer, and the fluctuation range was substantially constant at 10 to 20 ° C. The heat loss from the cylindrical wall surface of the reforming reactor was approximately 1,680 kcal / h.

Comparative Example 1 In Example 2, the shut-off valve C of the flow path 13 was closed, and the vaporization / evaporation of the raw material methanol-water mixture was performed in the raw material evaporator (1).
The reforming reaction was carried out in the same manner as in Example 2 except that the reforming reaction was carried out only in Example 2. As a result, the combustion gas temperature at the inlet of the reforming reaction tube 6 was lowered to 680 ° C., and the methanol conversion (average value) However, the value was extremely low at 81.2%.

〔effect〕

According to the present invention, the control of the reforming reaction temperature is carried out by using a raw material evaporator (1) of a methanol-water mixed liquid as a raw material, and
Since it can be carried out by changing the distribution ratio to the raw material evaporator (2), the structure of the reforming reactor becomes extremely simple, and as a result, the operation is easy and the equipment An on-site hydrogen gas generator that is easy to maintain and inspect.

[Brief description of the drawings]

1 and 2 show an embodiment of a methanol reforming reaction device according to the present invention. FIG. 1 is a sectional view of the methanol reforming reaction device, and FIG. 2 is aa of FIG. It is a line sectional view. 1: Combustion gas generator, 2: Raw material evaporator (1), 3: Mixed liquid header (1) 4: Raw material gas header (1), 5: Raw gas superheater, 6: Reforming reaction tube, 7: Reaction Gas outlet header, 8: Source gas inlet header, 9: Source evaporator (2), 10: Mixed liquid header (2), 11: Source gas header (2), 17: Partition wall, A: Flow control valve, B: Flow control valve C: Shut-off valve

Claims (1)

(57) [Claims] 1. A raw material evaporator (1), a raw material superheater, a reforming reaction in a methanol reforming reaction apparatus in which a mixed vapor of methanol and water is reacted with a combustion gas in the presence of a catalyst in the flow direction of the combustion gas. A vessel and a raw material evaporator (2) are sequentially arranged, and a raw material evaporator (1) and a raw material evaporator (2)
A methanol reforming reaction apparatus characterized in that a reforming reaction temperature is controlled by controlling / changing a distribution / feed ratio of a raw material methanol-water mixture to a reactor.