JPH03199102A - Reforming device for methanol - Google Patents

Abstract

PURPOSE:To facilitate operation and the maintenance and inspection of device and equipment at the time of reforming a methanol-water mixed vapor in the presence of a catalyst with a combustion gas by controlling the reforming temp. with the control of the temp. of the reheated combustion gas. CONSTITUTION:The preheated raw material of a methanol-water liq. mixture is introduced into a raw material evaporator 2 through a passage 13 and a liq. mixture header 3, heated by a high temp. combustion gas, vaporized, passed through a raw gas header 4 and separated into a passage 14 and a passage 15. The raw gas in the passage 14 is introduced into a raw gas superheater 5, heated by the combustion reheated to an optimum temp. by a combustion gas generator 10 and superheated. The superheated gas is joined to the raw gas from the passage 15 and a flow control valve A and mixed or the superheated gas is adjusted to an optimum temp. for the reforming reaction without being joined or mixed and introduced into a reforming reaction tube 6 through a raw gas mixture inlet header 7 to cause a reforming reaction, and the gaseous reaction product is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application 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.

[Conventional technology]

The method for producing reformed gas, which uses methanol as a raw material and whose main component is hydrogen, is extremely simple, as the raw material methanol is easy to transport and store, and the reforming reaction is easily carried out at a relatively low temperature. Since it is possible to produce hydrogen gas of desired quality, it has come to be adopted not only in the chemical industry, but also in new industrial fields such as the electronics industry, the food industry, and fuel cell power generation.

The mixed vapor of methanol and water undergoes a methanol decomposition reaction and a CO modification reaction by a catalyst in a reforming reactor, and becomes a reformed gas containing hydrogen as a main component.

CH30H+H20# CO2+ 3H214,8kc
The reforming (decomposition) reaction of al/mole methanol is an endothermic reaction, and the amount of heat required for the reforming reaction must be supplied by heating the reaction tube filled with the catalyst from the outside. In general, the heat of reaction is supplied, ie, the reaction tube is heated, by means of heat transfer 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 compactly, and the reaction temperature is extremely easy to control.
It has been put into practical use as an industrial device. However, the reactor
In addition to the reactor, it requires incidental equipment such as a heat medium oil boiler and a heat medium circulation pump, which has the drawback that the reforming reaction apparatus is quite complex and expensive.

If the combustion gas generator is integrated into the reforming reactor (tube) and designed to heat the catalyst tube directly with the combustion gas without using heat transfer oil, it will become a heat transfer oil boiler. Because it is an extremely simple reforming reaction device that does not require any incidental equipment such as 54-236
No. 83, JP-A-62-70202, JP-A-62260
No. 701, JP-A-63-138301, JP-A-63-
138306 etc.). However, when heating the catalyst tube with combustion gas, the overall heat transfer coefficient is 1 compared to when heating oil is used.
/10 or less, which requires higher temperature combustion gas in terms of heat transfer efficiency and load followability. Increasing the temperature of combustion gas, which is a heating medium, requires a catalyst with better heat resistance. Proposals have already been made regarding heat-resistant catalysts containing noble metals such as platinum as an active ingredient, but these have drawbacks such as being extremely expensive and producing many side reaction products (CO gas).

On the other hand, copper-based catalysts, which have already been praised as methanol reforming catalysts, are highly active at low temperatures and produce few side reaction products.
It has a long catalyst life and is inexpensive, making it ideal as an industrial catalyst, but it has the characteristic of low heat resistance. As a countermeasure against this, for example, there is a method (Japanese Patent Publication No. 57-42678) of arranging reactors filled with catalysts with different heat resistance (300°C, 520°C) in series;
A method in which low-temperature combustion gas (380°C) obtained by mixing a large amount of secondary air with high-temperature combustion gas is used as a heating medium (JP-A-6
No. 0-246201) etc. have been proposed.

[Problem that the invention seeks to solve]

Method (2) above extends the catalyst life and improves operability, but the reformer is complicated because it requires two reactors, making it difficult to make it compact. Although it is expected that the followability will be considerably improved, since a large amount of secondary air is required, the required power will be large, and it is presumed that it will be extremely difficult to obtain inexpensive hydrogen gas.

Generally, from the viewpoint of pollution prevention and energy saving, kerosene and/or methanol are used as fuel for combustion gas generators, and hydrogen purifiers m! (
PSA) purge gas is used. but,
Generally, since purge gas is not available during startup, the composition of the combustion gas changes, and the heat transfer coefficient outside the tube changes. In addition, when the load fluctuates, the heat transfer coefficient inside and outside the tube changes, making it difficult to control the temperature distribution of the catalyst layer within the optimum operating temperature range of the reforming catalyst. There is a drawback in that it cannot be used to its full potential.

[Means for solving problems]

The inventor conducted intensive studies on the structure and arrangement of the components of a methanol reformer that uses combustion gas as a heat medium, and the relationship between them and the overall heat transfer coefficient. It is divided into a device (1) and a combustion gas generating device (2), and further includes a raw material evaporator, and
The reforming reactor is configured as a group of multiple vertical tubes, and the raw material evaporator, combustion gas generator (2), raw material superheater, reforming reactor, and raw material preheater are installed in the order of the flow direction of the combustion gas. First, the high-temperature combustion gas is used as a heat source for the raw material evaporator, and then the lowered temperature of the medium-temperature combustion gas is reheated to an appropriate temperature in the combustion gas generator (2) and then used in the reforming reactor. In addition to using it as a heat source, the reforming reaction temperature is controlled by controlling the reheating temperature of the combustion gas, and finally, the low-temperature combustion gas whose temperature has further decreased is used as a heat source for the raw material preheater. By controlling and adjusting the temperature of the catalyst layer of the reforming reactor, in other words, the reaction temperature, the temperature of the combustion gas that is the heat source of the reforming reactor (tube), the reforming reaction can be carried out extremely easily and with high precision. It has been discovered that the temperature, that is, the temperature distribution of the catalyst layer, can be controlled and adjusted within a predetermined temperature range.Based on this knowledge, the present inventors have completed extensive improvement research.

Hereinafter, the present invention will be explained in more detail based on process diagrams. FIG. 1 is a process diagram of a methanol reforming reactor according to the present invention, and FIG. 2 is a basic configuration diagram according to an embodiment of the present invention, as well as a specific example of a preferred embodiment.

The raw material methanol-water mixture supplied from the raw material storage tank (omitted in FIG. 1) through the metering pump (not shown in FIG. 1) and the flow path 12 is led to the raw material preheater 9. It is heated by the low-temperature combustion gas that has finished supplying heat to the reforming reaction tube group and is preheated to 140°C. The preheated raw material methanol-water mixture is led to the raw material evaporator 2 via the flow path 13 and the mixed liquid header 3, where it is heated by high-temperature combustion gas, evaporates and vaporizes, and passes through the raw material gas header 4 to the raw material evaporator 2. It is branched and divided into a path 14 and a flow path 15. The raw material gas branched into the flow path 14 is guided to the raw material gas superheater 5 and heated by the combustion gas reheated to an optimum temperature by the combustion gas generator (200) to become superheated gas. Route 15, by merging and mixing with the raw material gas from the flow rate control valve ^, or without merging and mixing,
The temperature is adjusted and controlled to be optimal for the reforming reaction, and the raw material mixed gas is guided through the inlet header 7 to the reforming reaction tube 6 where a reforming reaction occurs and becomes a reaction product gas.

The reaction product gas produced by the reforming reaction is taken out as a reaction product gas through the reaction gas outlet header 8 and the flow path 16, and sent to the next step for purification, or used as it is as appropriate.

The high-temperature combustion gas generated in the combustion gas generator (1) 1 first evaporates and vaporizes the raw material methanol-water mixture in the raw material evaporator 2, and then reaches a predetermined temperature in the combustion gas generator (2) 10. The raw material gas is reheated and reaches the raw material superheater 5, where the raw material gas is superheated and becomes medium-temperature combustion gas, which is guided to the reforming reactor 6. The medium-temperature combustion gas heats the reforming reaction tube group to give reaction heat and becomes low-temperature combustion gas, and is led to the raw material preheater 9 where the remaining heat is used as the sensible heat of the raw material methanol-water mixture. After that, it is discharged into the atmosphere from the flow path 18.

When carrying out the present invention, raw material methanol and water may be uniformly mixed in a predetermined ratio in a raw material storage tank in advance, or they may be stored separately and used in a flow path 12 according to a conventional method. They may be mixed uniformly at a predetermined ratio within the range.

In addition, as illustrated in Fig. 2, a combustion gas generator (1
) 1 and the raw material evaporator 2 are placed in the same concentric cylindrical container, with the combustion gas generator (1) l on the inside and the raw material evaporator 2 on the outside.
are arranged as a plurality of tube groups, and a partition wall 11 is provided between the combustion gas generator (1) and the raw material evaporator to isolate them,
It is preferable to prevent direct contact of high-temperature combustion gas to the group of raw material evaporation tubes and to clearly regulate the flow direction of combustion gas.

In addition, the combustion gas generator (2) 10 and the raw material superheater 5 are
Preferably, it is provided in the combustion gas flow path 17.

In addition, the reforming reaction tube 6 and the raw material preheater 9 are separated from the raw material evaporator 2 in the same concentric cylindrical container, with the reforming reaction tube 6 inside as a plurality of reaction tube groups and the outside. Raw material preheater 9
At the same time, a partition wall 11 is installed between the reforming reaction tube and the raw material preheater to regulate the flow path of the combustion gas, thereby creating a clear temperature gradient in the flow direction of the combustion gas. It is preferable to provide one.

When carrying out the present invention, the combustion gas generating device 1 is generally placed in the upper part of a concentric cylindrical container from the viewpoint of ease of maintenance, as illustrated in FIG. Therefore,
Normally, the flow direction of the combustion gas is such that it first flows through the inner cylinder from top to bottom to equalize the combustion gas temperature, then reaches the raw material evaporator and flows from the bottom to the top through the raw material evaporation tube group. Although the design is not limited thereto, if desired, the combustion gas generating device may be placed at the bottom and the flow direction of the combustion gases may be reversed.

In addition, the flow direction of the combustion gas and raw material gas (reactant gas in the reforming reactor, that is, the group of reforming reaction tubes is determined by the reforming reaction rate,
In other words, from the viewpoint of heat absorption rate, cocurrent flow is generally preferred, but countercurrent flow may be used depending on the heat resistance performance of the reforming catalyst used, and is optional. Note that the flow direction of the raw material methanol-water mixture in the raw material preheater is preferably countercurrent to the combustion gas.

Hereinafter, a preferred embodiment of the present invention will be described in which the reforming reaction apparatus shown in FIG. 2 is used. In addition,
The examples illustrated below are merely for concretely explaining the effects of the present invention, and are not intended to limit the technical scope of the present invention.

Example 1 The present invention will be explained in more detail with reference to an example carried out using the reformer shown in FIG. 2. In the following examples, alumina sol was added to a coprecipitate prepared by a coprecipitation method using copper nitrate and zinc nitrate as raw materials, and the mixture was calcined.
φX3. Copper-zinc-aluminum catalyst formed into a cylindrical shape of Qmm [catalyst composition atomic ratio Cu:Zn:A1=1.0
0:0.75:0.25, see Example 1 of JP-A No. 59-189937] were added to each reforming reaction tube (48 tubes) with a nominal diameter Bl 1/4 inch and a length of 2.4 m. Fill it with
An activated methanol reforming catalyst was used, which was activated by reducing the catalyst with hydrogen gas according to a conventional method.

Example 1 is a case in which only kerosene is used as the fuel for the combustion gas generator (l>1), and it is assumed that the device is started cold. First, after replacing the inside of the device with hydrogen gas, The combustion gas generator (1) 1 was ignited according to a conventional method.The device was gradually warmed up and after about 30 minutes, the temperature of the reforming catalyst layer reached 230-260°C, and the temperature of the reformed gas outlet header 7 increased. became 260℃.

Here, the fuel flow rate of the combustion gas generator (1) ■ is 0.9
kg/h, and further, the combustion gas generator (2) 10
After igniting the raw material methanol-water mixture supply pump (omitted in Figure 2), the raw material methanol-water mixture (mixed molar ratio CH, OH: H20.1.0
:1.5) was supplied to the raw material evaporator 2 via the flow path 12, the raw material preheater 9, the flow path 13, and the mixed liquid header 3 (flow rate: 10.0 kg/h), and was vaporized. The raw material methanol-water mixed gas vaporized here is branched and divided into a flow path 14 and a flow path 15, and then joins together again and is led to the reforming reactor 6 via the mixed gas header 8 and reformed. The quality reaction started.

Next, while maintaining the gas pressure in the reforming reaction system (reforming reaction pressure) at 1 Oata according to a conventional method, the fuel flow rate is gradually increased.
Then, the flow rate of the raw methanol-water mixture was increased to set the flow rate of the raw methanol-water mixture to 23.6 kg/h. During this time, the temperature distribution of the catalyst layer is controlled so that the tube wall temperature of the reforming reaction tube does not exceed 360°C, and the temperature of the raw methanol-water mixed gas in the mixed gas header 8 becomes 230°C. The flow control valve ^, the flow control valve B1, and the fuel flow rate were adjusted and controlled so that the width of the flow rate was the minimum value.

In this way, approximately 55 minutes after the start of supply of the raw material methanol-water mixture, the operating condition of the device reached a steady state, and the flow rate of 40.5 Nm'/h (
(average value) of the reformed gas was obtained.

Subsequently, the reforming reaction experiment was continued for 36 hours while maintaining a steady state, and the results (average values) shown in Tables 1 and 2 were obtained. The methanol conversion rate (average value) in this experiment was 9
At 9%, the fuel consumption (average value) is 1.2 kg/h for combustion gas generator (1), and 1.2 kg/h for combustion gas generator (2).
At 0.7 kg/h, the temperature distribution of the reforming reactor catalyst layer is
The temperature was 230 to 260°C in the longitudinal direction of the catalyst layer, and the fluctuation range was substantially constant at 10 to 20°C. Furthermore, the heat loss from the cylindrical wall of the reforming reactor is 670kc.
It was al/h.

[Below empty white]

Table 1 Temperature of each device and combustion gas Table 2 Gas Composition Example 2 In Example 2, purge gas from a hydrogen gas purification device (pressure swing adsorption purification method) was used as fuel for combustion gas generator (1) 1. This assumes the use of kerosene in conjunction with normal steady operation of the device.

In Example 1, the purge gas from the hydrogen gas purification device was used instead of kerosene as the fuel for the combustion gas generator (1) 1 (kerosene was also used as an auxiliary fuel if necessary), and the raw material methanol-water mixture was used. Liquid flow rate: 59.0 kg
72 in the same manner as in Example 1 except that /h was changed.
Continuing the continuous reforming reaction for hours, using reformed gas at 1100 N'/h per hour, the results shown in Tables 3 and 4 (average values)
I got it. Methanol conversion rate in this experiment (average value>9
It was 7%. Also, the fuel consumption of the combustion gas generator (1)! (Steady state, average value) is purge gas 34 Nrn
3/h, and kerosene 0.0 kg/h.

In addition, the fuel consumption (steady state, average value) of the combustion gas generator (2) was 1.5 kg/h of kerosene.

The temperature distribution of the reforming reactor catalyst layer is 230 to 263 degrees Celsius in the length direction of the catalyst layer, and the fluctuation range is 10 to 20 degrees Celsius.
remained essentially constant. Note that the heat loss from the cylindrical wall surface of the reforming reactor was 1.680 kcal/h.

Comparative Example 1 In Example 2, when the same operation as in Example 2 was performed using only the combustion gas generator (1) without using the combustion gas generator (2), the methanol conversion rate (average value) was The value was extremely low at 80.9%.

〔effect〕

According to the present invention, the temperature of the reforming reaction catalyst layer can be controlled by controlling the temperature of the combustion gas, and more specifically, the temperature of the combustion gas generator (
2) can be carried out by controlling the amount of fuel supplied to This is an easy on-site hydrogen gas generator.

[Brief explanation of drawings]

FIG. 1 is a process diagram of the methanol reforming reactor of the present invention, FIG. 2 and FIG. 3 show an embodiment of the methanol reforming reactor of the present invention, and FIG. A cross-sectional view of the reforming reactor, FIG. 3 is a cross-sectional view taken along line a-a in FIG. 2. 1: Combustion gas generator (1), 2: Raw material evaporator, 3: Mixed liquid header Figure 2 Raw material gas header Raw material gas superheater, Reforming reaction tube, Raw material gas inlet header Reaction gas outlet header Raw material preheater, Combustion Gas generator (2), bulkhead, flow control valve, flow control valve

Claims (1)

[Claims] In a methanol reforming reactor in which a mixed vapor of methanol and water is reacted with combustion gas in the presence of a catalyst, a raw material evaporator, a combustion gas generator ( 2) A methanol reforming reaction apparatus in which a raw material superheater, a reforming reactor, and a raw material preheater are arranged in sequence, and the reforming reaction temperature is controlled by controlling the reheating temperature of combustion gas.