A low-temperature methanation reactor and its working process

Abstract

The invention discloses a low temperature methanation reactor and a working process.The methanation reactor mainly comprises a reactor quench gas chamber, a reactor tube pass, a shell pass and a product gas collection chamber; a quench gas sleeve is arranged in a quench gas tube nest, different flows of quench gas enters the quench gas tube nest from the quench gas chamber and overflows by small ventilation holes in the outer wall of the quench gas tube nest, the quench gas is mixed with high temperature reaction gas in a tube nest for heat exchange, the change of the bed temperature of the methanation reactor is synergistically controlled, reaction product gas is collected into the product gas collection chamber and exhausted by the product exhaust port; at the same time, a lot of heat exhausted by methanation reaction is moved away rapidly and circularly by boiler water of the reactor pass, and the bed layer temperature of the reactor is kept under lower temperature for operation; the operating temperature is lower, the methanation catalyst can be well protected, the catalyst can be prevented from high temperature carbon deposition, and the catalytic efficiency and the heat utilization ratio are high.

Description

technical field [0001] The invention belongs to the technical field of natural gas, in particular to a low-temperature methanation reactor for coal-to-natural gas and a working process. Background technique [0002] The methanation reaction is a strongly exothermic reaction, and every 1% of CO methanation reaction can produce an adiabatic temperature rise of 74°C, and every 1% of CO 2 The methanation reaction can produce an adiabatic temperature rise of 60°C, so the temperature rise of the reactor must be strictly controlled during the methanation reaction process, and a large amount of heat released during the reaction process must be removed quickly to prevent deactivation and sintering of the catalyst under high temperature conditions. [0003] Most of the existing methanation technologies adopt multiple adiabatic fixed beds connected in series, so that the methanation reaction can be carried out step by step in each adiabatic reactor. Multiple cycles with a cycle ratio ...

AI Technical Summary

Problems solved by technology

[0003] Most of the existing methanation technologies adopt multiple adiabatic fixed beds connected in series, so that the methanation reaction can be carried out step by step in each adiabatic reactor. Multiple cycles with a cycle ratio of not less than 5 reduce the volume percentage of CO in each section from 25% to 2%-3%; at the same time, the whole process needs to use multiple heat exchangers to remove the heat released by the reaction; these not only improve Increased equipment investment, but also increased energy consumption

In order to solve the problem of heat transfer, Chinese patent CN204247177 proposes an adiabatic isothermal methanation reactor, which includes setting an adiabatic catalyst layer above the tubes, with the purpose of rapidly increasing the activation temperature of the methanation reaction. The heat released by the reaction is removed by the circulating water at the shell side, which reduces the hot spot temperature of the methanation reaction to a certain extent. However, in view of the large heat release of the methanation reaction, it is difficult for ordinary tube and tube reactors to adapt to such a large thermal stress. , the same Chinese patent CN102827657 adopts multiple isothermal reactors to carry out methanation reaction, there are also potential safety hazards such as large heat release in reaction and large thermal stress in the reactor, and the inside of the reactor is easy to leak and cause danger; the tube of the tube reactor The catalyst is loaded in the process, and the boiler water located in the shell of the reactor with a large heat capacity is continuously evaporated and condensed in a cycle process, which quickly removes the heat released by the reaction, effectively inhibits the sharp rise of the hot spot temperature of the reaction bed, and avoids high temperature of the catalyst. Carbon deposition improves the operability of the system; however, compared with the methanation reaction with large heat release, the connection between the tube side and the shell side in the tube-and-tube reactor is more complicated, and it is easy to produce tube-side and shell-side connections under the condition of large thermal stress. The breakage between the tube sheets will cause safety hazards such as dangerous gas leakage, so it is difficult to realize the industrial scale-up of the reactor

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