Syngas CO combined conversion method and apparatus

Abstract

The invention discloses a syngas CO combined conversion method. According to the method, CO in the syngas is successively subjected to water-cooling heat-exchange conversion and gas-cooling heat-exchange conversion; the low-temperature syngas is firstly subjected to heat exchange with a reaction gas in the process of gas-cooling heat-exchange conversion, then is subjected to water-cooling heat-exchange conversion reaction along with generation of a byproduct steam is generated, and then is subjected to gas-cooling heat-exchange conversion for deep conversion reaction; the reaction gas after being subjected to deep conversion reaction is subjected to heat recovery and condensate-liquid recovery and then is sent to a subsequent workshop section for processing; and one part of the water-cooling heat-exchange conversion byproduct steam is mixed with the syngas and the mixture is subjected to water-cooling heat-exchange conversion, or all of the steam are sent out. The invention also discloses an apparatus applied to the above syngas CO combined conversion method. The method and the apparatus can realize continuous reaction heat discharge in the reaction process, continuously transfers the reaction heat and maintains the reaction to be performed at a low temperature, equipment is less, investment is low, and the reaction-heat byproduct medium-pressure steam satisfies demands of conversion reaction, reduces or eliminates externally-supplied steam and realizes outward delivery.

Description

technical field [0001] The invention relates to the technical field of chemical engineering, in particular to a synthesis gas CO combined conversion method and device. Background technique [0002] In the crude synthesis gas produced by various raw materials and methods, the CO content is generally higher than the content required for the production of various chemical products. The CO in the gas needs to be as low as <10ppm, so a large amount of CO needs to be converted into H according to the requirements of the production product 2 , so that it fits the syngas H 2 , CO ratio requirements, for example, the hydrogen-to-carbon ratio of synthetic methanol is about 2, and the hydrogen-to-carbon ratio of synthetic methane to natural gas is 3, and the CO conversion reaction is as follows: CO+H 2 O(steam)=H 2 +CO 2 +Q. This is a reversible exothermic reaction, and the released heat of reaction increases the reaction temperature, reduces the equilibrium conversion rate of ...

AI Technical Summary

Problems solved by technology

The water-air ratio is high, and an anti-sulfurization reaction will occur: MoS 2 +2H 2 O=MoO 2 +2H 2 S, to deactivate the cobalt molybdenum catalyst, and second, if the water vapor content is too high, the steam below the dew point temperature will condense into a liquid state, reducing the strength of the catalyst and pulverizing

The low water-gas ratio is not conducive to improving the conversion rate of CO, and secondly, methanation reaction will occur at high temperature: CO+3H 2 =CH 4 +H 2 O, this strong exothermic reaction is easy to burn out the catalyst. For the production of ammonia and methanol from syngas, the generated CH 4 It is the inert gas that consumes a large amount of useful CO and H in vain 2 Therefore, the multi-stage adiabatic transformation has the disadvantages of long process, many equipments, high energy consumption and large investment

[0005] For this reason, an isothermal shift technology has been developed in recent years. For example, the isothermal low-temperature CO shift reactor (CN101721956) is mainly equipped with multiple suspended replacement hot water pipes. After reaching the steam drum, it enters the inverted U-shaped tube in the shift reactor to absorb the reaction heat, raise the steam temperature, and then mixes with unreacted gas into the catalyst layer for shift reaction. This technology has been successfully implemented in industrial equipment and achieved comparative The above-mentioned multiple adiabatic reactors have a better effect of series conversion, but the reactor structure of this technology is complex, the heat exchange effect is not strong, the catalyst loading and unloading is inconvenient, and the reaction temperature is high, and the corresponding equilibrium constant decreases. For ammonia synthesis gas For low CO content requirements, it is necessary to increase the amount of catalyst and increase the water-gas ratio

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