JPH0779959B2 - Multi-tube reactor - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a multi-tubular reactor, and more specifically, a raw material reaction gas is passed through a plurality of reaction tubes and the outside of the reaction tubes is heated with a heating gas or the like. The present invention relates to a multi-tubular reactor in which a raw material reaction gas is reacted and discharged.

[Prior Art] Conventionally, in this kind of multi-tube reactor, the pipes are arranged so that the flow rate to each reaction tube is a constant flow rate, and the flow rate and the reaction temperature are often left to the user. .

However, in this case, the operating temperature of each reaction tube (reaction tube surface temperature, catalyst layer temperature) becomes non-uniform, and the temperature difference between the high reaction tube and the low reaction tube becomes large. For example, in the case of reforming methane gas and steam into hydrogen and carbon dioxide in a multi-tube reactor for a fuel cell, if the gas flow rate and the reaction temperature are controlled, the desired operating temperature of 800 to 850 ° C The temperature difference between the high temperature reaction tube and the low temperature reaction tube exceeded 100 ° C. Therefore, a reaction tube having a high reaction temperature has a bad influence on the life of the reaction tube, and a reaction tube having a low reaction temperature has an effect of lowering the overall reaction conversion rate.

Therefore, the temperature distribution in the reaction tube can be made uniform (Japanese Patent Laid-Open No. 59
-92018), an attempt to control the reaction temperature of each reaction tube to be uniform (JP-A-60-210503, JP-A-60-210504).
No.) has been made.

[Problems to be Solved by the Invention] However, these prior arts are not always perfect in terms of economy and reaction temperature control performance of the entire reactor.

For example, Japanese Patent Application Laid-Open No. 59-92018 discloses a technique in which each reaction tube is connected in series to make the temperature distribution in the radial direction in the reaction tube uniform. However, this is because the reaction temperature of each reaction tube gradually rises according to the flow of gas, which is useful for downsizing the equipment, etc., but the reaction temperature is made uniform over the entire reaction tubes equipped. Not something to do.

Further, in JP-A-60-210503, the interior of the reforming furnace as a multi-tubular reactor is partitioned into a plurality of burners,
A reformer for controlling the burner fuel for each partition to make the reaction temperature uniform is disclosed. However, this complicates the structure of the reforming furnace and is disadvantageous in terms of structure and cost. That is, since the number of burners increases, the instrumentation cost rapidly increases, and if it is sought, one reforming furnace is prepared for each reaction tube, which is uneconomical.

Further, JP-A-60-210504 discloses a reformer in which a control valve is installed at the gas inlet of each reaction tube and the reaction gas flow rate is controlled according to the reaction temperature of each reaction tube to make the temperature uniform. There is. However, this has a drawback that the stable state varies depending on the condition at the time of starting the control in the control procedure. That is, in this reformer, first, the heating amount by the combustion gas is adjusted based on the result of comparison between the predetermined limit temperature and the average temperature of the temperature measured for each reaction tube by the temperature measuring element, and the average value is adjusted. The amount of gas flowing into each reaction tube is controlled based on the result of comparing the temperature and the measured temperature in each reaction tube separately. Therefore, the opening of the control valve of each reaction tube is adjusted so as to approach the average temperature, so it may settle down at a low opening, and with one of them, the control valve is fully opened. Not necessarily. That is, there is a problem in that the processing efficiency does not reach the point where the performance of the apparatus is fully utilized when the apparatus is operating, and the processing efficiency settles down to an appropriate processing efficiency.

An object of the present invention is to solve the above-mentioned problems in the conventional type.
In the multi-tube reactor, the reaction temperature of each reaction tube can be kept constant and the processing efficiency of the equipment can be sufficiently improved by a simple improvement that does not have a complicated structure and is cost effective. To provide.

[Means and Actions for Solving Problems] To achieve the above object, the present invention introduces a raw material reaction gas into a plurality of reaction tubes and heats the outside of the reaction tubes to react the raw material reaction gas. In a multi-tubular reactor in which the reaction gas or the reaction tube group is divided into groups, a control valve for adjusting the gas flow rate is provided at the inlet side or the outlet side of the reaction gas and selected from the reaction tube group. A predetermined reaction tube is used as a representative reaction tube, and the reaction temperature of each reaction tube or a group of reaction tubes is detected separately, and the reaction temperature detected by the detection means is the reaction temperature of the representative reaction tube. And a means for controlling the opening of the control valve and the heating amount of the reaction tube so that at least one valve opening of the control valve is fully opened.

Further, in order to achieve the same object as the above, the second invention is a multi-tube system in which a raw material reaction gas is introduced into a plurality of reaction tubes and the outside of the reaction tubes is heated to cause the raw material reaction gas to react and flow out. In the reactor, one reaction tube provided with a manual valve for manually adjusting the gas flow rate on the inlet side or the outlet side of the reaction gas is used as a typical reaction tube, and each reaction tube other than the typical reaction tube is a reaction tube. Alternatively, a control valve for adjusting the gas flow rate at the inlet side or outlet side of the reaction gas for each group of reaction tubes is provided, and a means for individually detecting the reaction temperature in each reaction tube or group of reaction tubes is provided. And a means for controlling the opening degree of the control valve and the heating amount of the reaction tube so that the reaction temperature detected by the detection means becomes the same as the reaction temperature of the representative reaction tube.

Hereinafter, the present invention will be described in detail with reference to the drawings. In addition, here, a multitubular reactor provided with one manual valve, which is the second invention, will be mainly described.

FIG. 1 is an instrumentation system diagram around a furnace of a multitubular reactor according to a second invention.

In the figure, the raw material methane gas and steam introduced into the reactor 1 pass through the catalyst layers 3 in the plurality of reaction tubes 2 and are reformed there, and the control valves 6 or the manual valves 7 are supplied from the outflow pipes 4 and 5. Is derived through. Reference numeral 8 is a burner for heating the outside of the reaction tube 2. The combustion exhaust gas is discharged from the pipe 9. The temperature of the catalyst layer 3 is measured by the thermometer 10, and the data is input to the reaction tube temperature control circuit 11. The reaction tube temperature control circuit 11 controls the temperature of each reaction tube 2 and the manual valve 7
Is compared with the temperature of a reaction tube provided with a typical reaction tube, and each control valve 7 is adjusted so that they match. Reference numeral 12 is a reaction temperature control controller that operates a fuel gas by comparing the temperature of a typical reaction tube with a reaction temperature set value. That is, the reaction temperature control controller 12 compares the temperature of a typical reaction tube with a preset reaction temperature set value, and adjusts the opening degree of the valve 13 so that they match.

Therefore, once the opening of the manual valve 7 is determined, the openings of the other control valves are also determined, and the reaction temperature of each reaction tube becomes the same as the reaction temperature of the typical reaction tube and settles down. This allows any one of the valves to be fully opened by manually changing the manual valve 7.

In addition, each controller such as each control valve 7 and reaction temperature control controller 12
Use as a PID controller.

FIG. 2 is a diagram schematically showing the apparatus shown in FIG.
The number of reaction tubes and the number of valves are different from those in FIG. 1 for convenience, and here, 19 reaction tubes are arranged in parallel. In addition, a control valve is provided by grouping three tubes except for the central representative reaction tube.

In Fig. 2, the PV value (T _P ) of the reaction temperature control controller using the combustion gas as the manipulated variable is the reaction temperature T _{O of the} central reaction tube.
However, it is desirable that the average temperature of all reaction tubes and the average temperature of the maximum temperature of each block (here, 6 blocks) can be selected.

In the above-mentioned multi-tube reactor, by manually changing the opening of the manual valve, the valve opening of the other control valve and the combustion gas control valve is changed to make the reaction temperature uniform. However, it is convenient if this manual valve is also used as a control adjustment valve and PID control is performed so that any one of the adjustment valves is fully opened.
Invention).

[Explanation of Examples] Next, the present invention will be specifically described with reference to Examples.

First, in a reforming furnace with seven reaction tubes, a control valve provided at the outlet of each reaction tube was used to control the temperature of a representative reaction tube in the center as a set value for temperature control. The tube temperatures are as shown in the table below.

Here, the methane concentration of the reaction product gas was 0.83% (DRY), and reached the planned 0.87% (DRY). In addition, fuel gas consumption was also reduced by about 2.5%.

Comparative Example As a comparative example, when a reforming reaction was similarly performed without restricting the flow rate at the inlet and outlet of each reaction tube in a reforming furnace with seven reaction tubes,
The temperature of each reaction tube became non-uniform, as shown in the following table.

Here, when the temperature rise was stopped because the wall temperature of the reaction tube at the maximum temperature was close to the design temperature, the methane concentration of the reaction product gas was 0.98% (DRY) and did not reach the planned 0.87% (DRY). It was

[Effects of the Invention] As described above, according to the present invention, in the multi-tubular reactor, a control valve is provided at the inlet or outlet side of each reaction tube so that one of them is controlled to be fully opened, Alternatively, a manual valve is provided in one reaction tube, and the reaction temperature of the representative reaction tube is controlled so that the reaction temperature of the other reaction tube matches, so that the following effects are obtained.

The reaction temperature of each reaction tube can be made uniform without having a complicated structure.

Thereby, the reaction temperature can be raised to the maximum temperature allowed by the reaction tube. This contributes to the improvement of thermal efficiency and the processing efficiency.

Control of a typical reaction tube can be performed to minimize the pressure loss of the reforming system. Therefore, when used in a fuel cell or the like, the efficiency of the power generation system can be improved.

The life of each reaction tube becomes uniform and the cost is reduced.

Burnout of the heated reaction tube can be prevented, and safety is improved.

[Brief description of drawings]

FIG. 1 is a diagram of an instrumentation system around a furnace of a multitubular reactor according to the present invention, and FIG. 2 is a diagram schematically showing the apparatus of FIG. 1: Reactor, 2: Reaction tube, 3: Catalyst layer, 6: Control valve, 7: Manual valve,
8: Burner, 10: Thermometer, 11: Reaction tube temperature control circuit.

Claims (4)

[Claims] 1. A raw material reaction gas is introduced into a plurality of reaction tubes,
In a multi-tube reactor in which the outside of the reaction tube is heated to react the raw material reaction gas and flow out, the gas flow rate is adjusted to the inlet side or the outlet side of the reaction gas for each reaction tube or group of reaction tubes. And a means for individually detecting the reaction temperature in each of the reaction tubes or the group of reaction tubes, the predetermined reaction tube selected from the group of reaction tubes being a representative reaction tube. In order to make the reaction temperature detected in 1. the same as the reaction temperature of the representative reaction tube, and further to open at least one valve opening of the control valve fully, the opening of the control valve and the heating of the reaction tube. A multi-tubular reactor comprising means for controlling the amount. 2. The multi-tube reactor according to claim 1, wherein the reaction temperature of the representative reaction tube is controlled to a preset value designated from the outside in advance. 3. A raw material reaction gas is introduced into a plurality of reaction tubes,
In a multi-tube reactor for heating the outside of the reaction tube to react the raw material reaction gas and let it flow out, one reaction tube provided with a manual valve for manually adjusting the gas flow rate at the inlet side or the outlet side of the reaction gas is provided. As a typical reaction tube,
For reaction tubes other than the representative reaction tubes, a control valve for adjusting the gas flow rate is provided at the inlet side or the outlet side of the reaction gas for each reaction tube or group of divided reaction tubes, and each reaction tube or group is divided. Means for individually detecting the reaction temperature in the reaction tube group, and the opening of the control valve and the heating amount of the reaction tube so that the reaction temperature detected by the detection means is the same as the reaction temperature of the representative reaction tube. A multitubular reactor characterized by comprising means for controlling. 4. The multitubular reactor according to claim 3, wherein the reaction temperature of the representative reaction tube is controlled to a preset value designated from the outside in advance.