JPS63218244A - Multi-tubular reactor for synthesizing methanol - Google Patents

Abstract

PURPOSE:To make the wall of reaction tube and tube-plate thin, by separating an upper tube-plate from a reactor, combining a lower tube-plate with the reactor to cut off gas flow and to support tubes and then connecting an lower- end of center tube with a nozzle of water inlet. CONSTITUTION:Unreacted gas to be raw gas is introduced to the outside of the reaction tube 1 from a gas inlet nozzle 12 provided on a drum above the lower tube-plate 5 and pre-heated by reaction heat generated in the tube while rising. Then said gas is introduced to a catalyst layer 3 in the reaction tube 1 through a gap between the upper tube-plate 4 and the drum or a gas passage 14 and flows down. The methanol synthesis is advanced while said gas flows down in the catalyst layer 3 and then the reaction product is recovered from the gas outlet nozzle 13 below the reaction tube 1. In the titled reactor, the reaction tube 1 and the lower tube-plate 5 are made to thin and lightweight, and the heat of reaction is effectively removed by unreacted gas and evaporating water in the center tube.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a multitubular reactor for methanol synthesis.

[Conventional technology]

A granular solid catalyst is filled in a plurality of reaction tubes, and a pressurized mixed gas containing hydrogen, -carbon oxide, and carbon dioxide as significant substances is brought into contact with the catalyst to produce 2 H, + C! O-+
0M30H・・−・−・(1)AH7+CO,→C
Pressurized water under saturated conditions at a temperature lower than the appropriate reaction temperature is placed on the outer surface of the reaction tube to cause a catalytic reaction of HlOH + H2O (2), (1)
, the heat generated along with the reaction of equation (2) ((1), (2)
) is an exothermic reaction) is converted into latent heat of vaporization of water by heat transfer through the tube wall of the reaction tube, and a reactor that attempts to maintain the catalytic reaction temperature within the appropriate condition range is disclosed in Japanese Patent Publication No. 56-22854.
It is stated in the No.

The above reactor will be explained with reference to FIG. A plurality of reaction tubes 1 located vertically are fixed to upper and lower tube sheets 4 and 5, and the reaction tubes 1 are filled with granular catalyst 3, and the upper and lower tube sheets 4.50
A water-inlet nozzle lv6 and an air-water outlet nozzle/'v7 are provided in the intermediate body to flow saturated pressurized water to the outside of the reaction tube 1, while preheated unreacted gas is introduced from the gas-inlet nozzle A/12 to carry out the reaction. The catalyst layer in the pipe 1 is allowed to flow down to perform methanol synthesis, and the reaction-completed gas is recovered from the gas outlet A'13. The reaction heat associated with methanol synthesis is generated by evaporating saturated pressurized water, taking out the steam containing steam from the steam outlet Ronoz/I/7, separating the steam in the steam/steam outlet 15, and then adding pressurized water as necessary to evaporate it again. Water is circulated to the reactor through the water inlet nozzle 6.

In addition, the patent application No. 59-08005 proposed by the inventors of the present application
Reactor No. 3 is a reactor that is further improved from this, in which a central tube is placed in the center of the reaction tube, and unreacted gas at a temperature lower than the appropriate reaction temperature is caused to flow through the central tube to cause the wall of the central tube to flow. The heat exchanger functions as a heat transfer tube, that is, a heat exchanger, and the heat exchanger for adjusting the temperature distribution of the catalyst layer and preheating unreacted gas is omitted.

The appropriate reaction temperature range for the copper-based catalyst used in methanol synthesis is 220 to 280°C, and if the temperature exceeds 300°C, the catalyst will be deactivated and the concentration of undesirable side reaction products will increase.

Therefore, the pressure of the water located on the outer surface of the reaction tube is about 40 atm (saturation temperature 249° C.) due to the difference between its saturation temperature and the temperature required for heat transfer. On the other hand, the gas pressure inside the reaction tube is
Although it is controlled by factors such as gas composition, space velocity, and compressor power cost, conditions of 60 to 150 atm are generally adopted.

Although it depends on the operating method, the gas inside the reaction tube and the water outside the reaction tube are externally pressured by different external pressure systems (compressor, pump), so the pressure inside the reaction tube is 1100 at and the pressure on the water side is 1.
The ATM condition is also acceptable at the start of operation.

In other words, the pressure difference between the inside and outside of the tube during steady operation cannot be used in designing the strength of the tube sheet and the tube, and it is necessary to design the strength to withstand pressures of 60 to 150 atm. Therefore, the tube,
Both the tube and sheet are thicker and the weight of the reactor increases. This is one of the constraints for large blunts.

[Problem that the invention seeks to solve]

The present invention solves the above problems and provides a multi-tubular reaction system for methanol synthesis that makes it possible to reduce the thickness of the tube wall and tube plate of the reaction tube by extremely reducing the gas pressure inside and outside the reaction tube. It is an attempt to provide a vessel.

[Means for solving problems]

In the present invention, a plurality of reaction tubes located vertically are fixed to upper and lower tube plates, a center tube is placed in the center of the reaction tubes, and a granular catalyst is filled in an annular space formed by the reaction tubes and the center tube. In the reactor for methanol synthesis, the upper tube sheet is separated from the reactor, the lower tube sheet is connected to the reactor so as to block the flow of gas to support the reaction tube, and the lower end of the central tube is connected to water. Connect the inlet nozzle and the air/water outlet nozzle at the upper end, and connect the unreacted gas inlet nozzle slightly above the lower tube plate.
In addition, a reaction completion gas outlet μ is provided below the lower tube plate to allow saturated pressurized water to rise inside the central tube, and unreacted gas to rise outside the reaction tube and descend through the catalyst layer inside the reaction tube. This is a multitubular reactor for methanol synthesis, which is characterized by the following features.

[Effect]

FIG. 2 is an explanatory diagram of a multi-tubular reactor which is one specific example of the present invention.

A central tube 2 is placed in the center of a plurality of vertical reaction tubes 1,
The annular spaces of the two tubes are filled with granular catalyst 3. reaction tube 1
are fixed to the upper tube sheet 4 and the lower tube sheet 5, but the upper tube sheet 4 has a gas passage 14 separated from the reactor shell.

On the other hand, the lower tube plate 5 is supported on a support attached to the body, and gas does not flow before and after the lower tube plate 5. Saturated pressurized water is supplied from the water-containing nozzle lv6 and the water header 8 through the connecting pipe 1o into the central pipe 2, receives reaction heat outside the central pipe 2, and evaporates into steam and water. Air and water header 9 through pipe 11, air and water output Ronoz/I/7
It is then discharged and sent to a steam/water drum 15 to separate the water vapor. The saturated pressurized water separated in the air-water drum 15 is replenished as necessary and circulated again to the water tank A/6 of the reactor. On the other hand, the unreacted gas, which is the raw material gas, is introduced to the outside of the reaction tube 1 through a gas-containing nozzle/l/12 provided in the body above the lower tube plate 5, and while rising, it is preheated by the reaction heat inside the tube. The gas passes through the gas passage 14 in the gap between the upper tube plate 4 and the shell, is introduced into the catalyst layer 3 in the reaction tube 1, and flows downward. While flowing down this catalyst layer 3, methanol synthesis proceeds and is recovered from the gas output nozzle 13 located below the reactor. Note that a buckle plate may be provided to control the gas flow outside the reaction tube 1.

By adopting such an equipment configuration, a one-through system is formed between the outside of the reaction tube where unreacted gas is introduced and the inside of the reaction tube where methanol synthesis proceeds, and the pressure difference inside and outside the reaction tube is reduced due to the gas flow. Although there is some pressure loss, it is extremely small. Therefore, the thickness of the reaction tube may be thin;
The pressure load on the lower tube sheet is also small, and the strength can be determined by considering the load due to the weight of the upper tube sheet, reaction tube, and catalyst.

Since the upper tube sheet is not connected to the shell, even if a temperature difference occurs between the reaction tube and the shell, there is no problem of thermal expansion difference, ie, thermal stress.

The reaction heat can be effectively removed by transferring it to both the water in the central tube and the gas outside the reaction tube through the tube wall, thereby maintaining the contact reaction temperature within a range of appropriate conditions.

This temperature adjustment can be easily carried out by setting the space velocity, water pressure, gas composition (for example, Co/H ratio), and gas pressure to appropriate conditions.

〔Effect of the invention〕

By adopting the above structure, the present invention makes it possible to preheat the raw material gas within the reactor, minimizes the pressure inside and outside the reaction tube, makes the reaction tube and lower tube sheet thinner, and makes it lightweight. The reaction heat can be effectively cooled by the evaporation of unreacted gas outside the reaction tube and water in the central tube. Furthermore, thermal expansion of the reaction tube does not affect the tube sheet.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a multi-tubular reactor which is a specific example of the present invention, and FIG. 2 is an explanatory diagram of a conventional multi-tubular reactor.

Claims (1)

[Claims] For methanol synthesis, multiple reaction tubes located vertically are fixed to upper and lower tube plates, a center tube is placed in the center of the reaction tubes, and a granular catalyst is filled in the annular space formed by the reaction tubes and the center tube. In the reactor, the upper tube sheet is separated from the reactor, the lower tube sheet is coupled to the reactor to block gas flow to support the reaction tube, and the lower end of the center tube is connected to a water inlet nozzle; In addition, the upper ends of the same are connected to the steam and water outlet nozzles, and an unreacted gas inlet nozzle is installed slightly above the lower tube sheet, and a reaction-completed gas outlet nozzle is installed below the lower tube sheet to supply saturated pressurized water. A multitubular reactor for methanol synthesis, characterized in that the interior of the central tube is raised, unreacted gas is caused to rise outside the reaction tube, and descend through a catalyst layer inside the reaction tube.