No cycle methanation system

Abstract

The invention discloses a circulation-free methanation system which comprises a gas distribution methanation stage and a supplementation methanation stage, wherein in the gas distribution methanation stage, 1 to 3 stages of serially connected high-temperature reactors are adopted; in the supplementation methanation stage, 2 to 3 stages of serially connected low and medium-temperature reactors are adopted; the final-stage reactor in the gas distribution methanation stage is connected in series with the head-stage reactor in the supplementation methanation stage; technical gas discharged by the former stage of the reactor is used as part of or all the synthesized gas of the next stage of the reactor; technical gas discharged by the final-stage reactor is subjected to cooling separation to obtain a final methane product. The technical system is simple, and the reaction is steady, safe and reliable; the running cost and the manufacturing cost are low.

Description

technical field [0001] The invention relates to methanation reaction technology, in particular to a cycle-free methanation system. Background technique [0002] The methanation reaction is CO, CO 2 and H 2 A strong exothermic reaction at a certain temperature (a strong exothermic reaction usually refers to a reaction with an enthalpy greater than 200kJ / mol), under the usual synthesis gas composition, each percent of CO methanation can produce 74 ° C adiabatic Temperature rise, per percent CO 2 Methanation can produce an adiabatic temperature rise of 60°C. Limited by the operating temperature range of the catalyst, the current industrial methanation generally has a temperature resistance of 650-750°C. Therefore, how to effectively control the reaction exotherm and quickly remove heat to maintain the normal operation of the reaction is the focus of large-scale methanation process research and development. At present, most methanation units at home and abroad use a cyclic ...

AI Technical Summary

Problems solved by technology

The cyclic methanation process has at least the following disadvantages: (1) Due to the increase of the feed flow rate of the reactor, the reaction driving force decreases, and the catalyst loading will increase significantly

(2) It is necessary to use a circulating gas compressor, which is difficult to manufacture and requires high investment

(3) Using circulation to control the temperature of the methanation reaction, there is a possibility of overheating

But the high-temperature reactor in the prior art also has at least the following disadvantages: (1) the refractory lining of the existing high-temperature reactor usually has a considerable thickness, which makes the overall volume of the existing high-temperature reactor larger, which is unfavorable for installation , Disassembly

(2) After being subjected to equipment vibration and / or drastic temperature changes, the refractory lining of the existing high-temperature reactor is prone to damage such as cracking and falling off; once the refractory lining is damaged, the strong exothermic reaction will directly damage the high-temperature reactor shell, which may lead to safety accidents

(3) The strong exothermic reaction makes the outlet temperature of the high temperature reactor too high, so the follow-up production equipment used with the high temperature reactor (for example: the outlet pipe of the high temperature reactor, the waste heat boiler for heat recovery, etc.) High temperature resistance, which brings difficulties to the selection and processing of production equipment in the subsequent process, and also increases investment and operating costs

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