JPS63141638A - Multitubular reactor - Google Patents

Abstract

PURPOSE:To uniformize the reaction temp. of each reaction pipe by selecting a specific reaction pipe as a representative reaction pipe selected from a group of reaction pipes and providing a means, etc., which separately detects the temp. of each reaction pipe or of a group of reaction pipes. CONSTITUTION:The temp. of catalyst layer 3 is measured with a thermometer 10 and the data is inputted to a reaction pipe temp. control circuit 11, which compares the temp. of each reaction pipe 2 with the temp. of the reaction pipe provided with a manual valve 7, that is, the representative reaction pipe, and controls the control valve 6 of each reaction pipe. A reaction temp. control valve 12 compares the temp. of the representative reaction pipe with the set value of reaction temp. and controls the opening rate of a valve 13 so that both valves coincide. Consequently, by fixing the opening valve is fixed, and the reaction temp. of each reaction pipe is converged to the reaction temp. of the representative reaction pipe.

Description

[Detailed Description of the Invention] [Field to which the noise pertains] 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 tube 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 type of multitubular reactor, the piping was arranged so that the flow rate to each reaction tube was constant, and the flow rate and reaction temperature were often left to chance. .

However, in this case, the operating temperature (reaction tube surface temperature, catalyst layer temperature) of each reaction tube becomes non-uniform, and the temperature difference between the high reaction tube and the low temperature reaction tube becomes large.

For example, when reforming methane gas and water vapor into hydrogen and carbon dioxide in a multitubular reactor for fuel cells, if the gas flow rate and reaction temperature are left as they are, the desired operating temperature will be 8.
The temperature difference between the high-temperature reaction tube and the low-temperature reaction tube exceeded 100 t:00 to 850°C. Therefore,
A reaction tube with a high reaction temperature has a negative effect on the life of the reaction tube, and a reaction tube with a low reaction temperature has the effect of lowering the overall reaction conversion rate.

Therefore, we tried to make the temperature distribution inside the reaction tube uniform (Japanese Unexamined Patent Publication No. 5
9-92018), attempts have been made to control the reaction temperature of each reaction tube to be uniform (Japanese Patent Application Laid-open Nos. 60-210503 and 60-210504).

[Problems to be Solved by the Invention] However, these prior art techniques cannot necessarily be said to be perfect in terms of economy and reaction temperature control performance of the reactor as a whole.

For example, Japanese Patent Laid-Open No. 59-92018 discloses a technique for connecting reaction tubes in series to equalize the temperature distribution in the radial direction within the reaction tubes. However, this method causes the reaction temperature of each reaction tube to rise sequentially according to the gas flow, and although this is useful for downsizing the device, it is difficult to make the reaction temperature uniform across multiple reaction tubes. It's not something you do.

Furthermore, in JP-A No. 60-210503, a reforming device is disclosed in which the interior of a reforming furnace as a multi-tubular reactor is divided into multiple partitions, a burner is installed in each partition, and the burner fuel is controlled for each partition to equalize the reaction temperature. is disclosed. but,
This complicates the structure of the reforming furnace, resulting in disadvantages in terms of structure and cost. That is, since the number of burners increases, the instrumentation cost increases rapidly, and in the end, one reforming furnace is required for each reaction tube, which is uneconomical.

Furthermore, JP-A No. 60-210504 discloses a reformer in which a control valve is installed at the gas inlet of each reaction tube to control the reaction gas flow rate according to the reaction temperature of each reaction tube and to equalize the temperature. There is. However, this has the disadvantage that the stable state in the control procedure varies depending on the conditions at the time the control is started. That is, in this reformer, first, the amount of heating by the combustion gas is adjusted based on the result of comparing the predetermined limit temperature with the average temperature measured for each reaction tube by the temperature measuring element, and then The amount of gas flowing into each reaction tube is controlled based on the results of comparing the temperature with the temperature measured in each reaction tube. Therefore, the opening degree of the control valve of each reaction tube is adjusted so that it approaches the average temperature, so each may settle at a low opening degree, and even if one of the control valves is fully open 100%. Not necessarily.

In other words, when the device is operating, the processing efficiency increases the device performance by 10%.
There was a problem in that the processing efficiency did not reach the point where 0% utilization was achieved, but instead settled on an appropriate processing efficiency determined by the course of events.

The purpose of the present invention is to solve the above-mentioned problems in the conventional type.
A multi-tubular reactor that can maintain a constant reaction temperature in each reaction tube with a simple modification that is cost-effective without a complicated structure, and can sufficiently increase the IA filling efficiency of the device. It's about providing the equipment.

[Means and effects for solving the problems] In order 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 tube to react the raw material reaction gas. In a multi-tubular reactor in which the reaction gas is forced out, each reaction tube or group of reaction tubes is provided with a control valve for adjusting the gas flow rate on the inlet side or outlet side of the reaction gas. a means for individually detecting the reaction temperature in each of the reaction tubes or grouped reaction tubes, with a predetermined reaction tube as a representative reaction tube; The method further includes means for controlling the opening degree of the regulating valve and the amount of heating of the reaction tube so that the opening degree of at least one of the regulating valves becomes fully open.

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

Hereinafter, the present invention will be explained in detail using the drawings.

In addition, here, mainly the second invention, which is a multi-tubular reactor equipped with one manual valve, will be explained.

FIG. 1 is a diagram of the instrumentation system around the furnace of the multi-tubular reactor according to the second invention.

In the figure, meth, which is a raw material introduced into reactor 1,
The gas and steam pass through catalyst beds 3 in a plurality of reaction tubes 2, are reformed there, and are led out through outlet tubes 4.5 via control valves 6 or manual valves 7. 8 is a burner for heating the outside of the reaction tube 2. Combustion exhaust gas is discharged through pipe 9. The temperature of the catalyst layer 3 is measured by a thermometer 10, and the data is input to a reaction tube temperature control circuit 11.

The reaction tube temperature control circuit 11 compares the temperature of each of these reaction tubes 2 with the temperature of a reaction tube in which a manual valve 7 is installed, that is, a typical reaction tube, and adjusts each control valve 7 so that they match. Adjust. 12 is a reaction temperature control regulator that compares the temperature of a typical reaction tube with a reaction temperature set value and controls the fuel gas. That is, the reaction temperature control regulator 12 compares the temperature of a typical reaction tube with a preset reaction temperature value, and adjusts the opening degree of the valve 13 so that they match.

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

Note that each of the control valves 7 and each of the reaction temperature control regulators 12 is a PID controller.

FIG. 2 is a diagram schematically representing the apparatus of FIG. 1.

Note that 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, the tubes other than the central representative reaction tube are grouped into three groups and equipped with control valves.

In Fig. 2, the reaction temperature T0 of the center reaction tube is used as is as the pv value (TP) of the reaction temperature control regulator that uses combustion gas as the manipulated variable, but the average temperature of all reaction tubes and the It is desirable to also be able to select the average temperature of the highest temperatures of each block (in this case, 6 blocks).

In addition, in the multi-tubular reactor shown above, by manually changing the opening degree of the manual valve, the valve opening degrees of other control valves and combustion gas control valves will change, and the reaction temperature will be made uniform. However, it is convenient to use this manual valve as a control adjustment valve and perform PID control so that one of the adjustment valves is fully open (first invention).

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

First, in a reforming furnace with seven reaction tubes, the temperature of a representative reaction tube in the center was controlled as the temperature control set value using a control valve installed at the outlet of each reaction tube. The temperature of the tube was as shown in the table below.

Here, the methane concentration of the reaction product gas is 0.83% (DR
Y), reaching 0.87% (DRY) of the planned rate. Fuel gas consumption also decreased by approximately 2.5%.

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

At this point, the temperature of the wall of the reaction tube at the highest temperature approached the design temperature, so the temperature increase was stopped, and the methane concentration of the reaction product gas was 0.98% (DRY), which was 0.8% as planned.
It did not reach 7% (DRY).

[Effects of the Invention] As explained above, according to the present invention, in a multi-tubular reactor, a control valve is provided on the inlet or outlet side of each reaction tube and controlled so that one of the reaction tubes is fully open; One reaction tube is equipped with a manual valve and the reaction temperature of the other reaction tubes is controlled to match the reaction temperature of that representative reaction tube, resulting in the following effects.

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

(2) Thereby, the reaction temperature can be raised to the maximum temperature allowed by the reaction tube. This contributes to improved thermal efficiency and improved processing efficiency.

(2) Typical reaction tubes can be controlled to minimize pressure drop in the reforming system. Therefore, when used in a fuel cell or the like, the efficiency of the power generation system can be increased.

■The lifespan of each reaction tube is uniform, reducing costs.

■ Burnout of heated reaction tubes can be prevented, improving safety.

[Brief explanation of the drawing]

FIG. 1 is a diagram of the instrumentation system around the furnace of a multi-tubular reactor according to the present invention, and FIG. 2 is a diagram schematically showing the apparatus of FIG. 1. 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 (1)

[Scope of Claims] 1. In a multitubular reactor in which a raw material reaction gas is introduced into a plurality of reaction tubes, the outside of the reaction tube is heated to cause the raw material reaction gas to react, and then flows out, each reaction tube or group is divided. A control valve for adjusting the gas flow rate is provided on the inlet side or outlet side of the reaction gas for each group of reaction tubes, and a predetermined reaction tube selected from the group of reaction tubes is used as a representative reaction tube, and each of the reaction tubes or means for individually detecting reaction temperatures in the grouped reaction tubes, and at least one valve of the control valves so that the reaction temperature detected by the detection means is the same as the reaction temperature of the representative reaction tubes A multi-tubular reactor comprising means for controlling the opening degree of the control valve and the heating amount of the reaction tube so that the opening degree is fully opened. 2. The multitubular reactor according to claim 1, wherein the reaction temperature of the representative reaction tube is controlled to a preset value specified from the outside. 3. In a multi-tubular reactor where a raw material reaction gas is introduced into a plurality of reaction tubes and the outside of the reaction tube is heated to cause the raw material reaction gas to react and flow out, the gas flow rate is controlled at the inlet or outlet side of the reaction gas. A typical reaction tube is one equipped with a manually adjusted manual valve;
For reaction tubes other than the representative reaction tubes, a control valve for adjusting the gas flow rate is provided on the inlet side or outlet side of the reaction gas for each reaction tube or group of reaction tubes, and for each reaction tube or grouped group. a means for individually detecting the reaction temperature in each group of reaction tubes; and an opening degree of the control valve and an amount of heating 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 multi-tubular 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 specified from the outside.