Powdered coal gasification matched gas-cooling shift cascade isothermal shift technology for preparing synthetic gas, and isothermal shift furnace

Abstract

The invention relates to a powdered coal gasification matched gas-cooling shift cascade isothermal shift technology for preparing synthetic gas, and an isothermal shift furnace. The technology comprises the following steps: raw gas from a powdered coal gasification device undergoes liquid separation, heat exchange and toxin removal, and then is divided into three streams, the second stream of obtained purified gas is fed into a gas-cooled shift furnace and undergoes a shift reaction, and the third stream of the purified gas is fed into the isothermal shift furnace and undergoes the shift reaction; a first shift gas discharged from the air-cooled shift furnace undergoes heat exchange by taking medium-pressure saturated steam as a heat taking medium of the air-cooled shift furnace, then is mixed with the third stream of the purified gas, and finally enters the isothermal shift furnace; and a second shift gas discharged from the isothermal shift furnace undergoes heat recovery by taking boiler water as a heat taking medium of the isothermal shift furnace, and then is mixed with the first stream of the purified gas to obtain crude synthetic gas, and the crude synthetic gas further undergoes heat recovery, and then is sent to the downstream.

Description

technical field [0001] The invention relates to a CO shift process and equipment, in particular to an air-cooled shift series isothermal shift process for producing synthesis gas and an isothermal shift furnace supporting pulverized coal gasification. Background technique [0002] my country is a country that lacks oil, gas, and coal. The characteristics of resources determine that coal is the main source of energy and chemical raw materials in my country. Coal gasification is an important method for chemical processing of coal, and it is the key to realize the clean utilization of coal. With pulverized coal as raw material gasification technology (such as Dongfang furnace), the CO content of the crude gas produced by this type of gasification technology is as high as 60v%~80v% (dry basis), and the water gas mole is 0.5~1.0. [0003] The carbon monoxide conversion process is an indispensable part of modern coal chemical technology, and it plays a role in linking the previou...

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Problems solved by technology

[0004] The transformation reaction is an exothermic reaction. The traditional transformation process mostly adopts the method of "multi-stage adiabatic reaction + indirect heat recovery" to set up the process. This process has long process, many equipment, large investment, high energy consumption, large system pressure drop, catalyst A series of problems such as short lifespan

[0005] The isothermal shift technology developed in recent years has been applied in various coal gasification processes. It has attracted people's attention because of its technical advantages such as short process flow and easy control of the depth of shift reaction. However, this technology also has the following shortcomings: the current isothermal shift process In this process, whether it is an adiabatic shift series isothermal shift process, an isothermal shift series adiabatic shift process, or a double isothermal shift furnace series process, the shift gas passes through all the shift furnaces in full volume, resulting in a large equipment size and high cost for the shift furnace ;Secondly, some isothermal shift processes can only by-produce saturated steam, but cannot produce superheated steam, and the quality of steam is low

[0006] (1) For example, "Adiabatic Series Isothermal Transformation Process for High Concentration CO Feedstock Gas" disclosed in the Chinese invention patent application with application number 201410439881.7, the process flow is set as: adiabatic + isothermal transformation process, adiabatic + isothermal + Although the adiabatic shift process solves the overheating problem of steam, when this process is used for crude gas with high CO concentration, the adiabatic shift furnace has the risk of overheating

[0007] (2) As disclosed in the Chinese invention patent application with the application number of 201210185731.9 "A water-shift heat conversion process for energy-saving and deep conversion of high-grade by-product steam", the process flow is set as: double isothermal conversion furnace series process, adiabatic + Isothermal shift process, adiabatic + isothermal + adiabatic shift process, all three processes can only produce saturated steam, and the adiabatic shift furnace is installed in front of the isothermal shift furnace. When this process is used for crude gas with high CO concentration, the adiabatic shift furnace has overtemperature risks of

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