Method and system for preparing synthesis gas by graded utilization of low-rank coal

Abstract

The invention provides a method for preparing synthesis gas by graded utilization of low-rank coal. According to the method, low-rank coal is sequentially treated through a drying process and a gasification reduction process to obtain upgraded coal and an oil-gas mixture, the oil-gas mixture is treated through a purification process to obtain mixed gas containing CO, H2 and hydrocarbons, and the mixed gas is treated through a separation process to obtain first synthesis gas containing H2 and CO and gas containing hydrocarbons; the hydrocarbon-containing gas is subjected to a reforming conversion process to produce second synthesis gas comprising CO and H2; the upgraded coal reacts with H2O and O2 to prepare third synthesis gas containing CO and H2; and the first synthesis gas, the second synthesis gas and the third synthesis gas are mixed to obtain the synthesis gas. According to the method and the system disclosed by the invention, volatile components and fixed carbon in low-rank coalare retained in the forms of CO and H2 to the greatest extent in multiple ways, the yield of the synthesis gas is high, and the low-rank coal is fully and effectively utilized.

Description

technical field [0001] The invention relates to the technical field of clean utilization of coal substances, in particular to a method and a system for preparing synthetic gas by graded utilization of low-rank coal. Background technique [0002] More than half of my country's proven coal reserves are low-rank coals, and the volatile matter contained in them is equivalent to 100 billion tons of oil and gas resources. Low-rank coal mainly has the material characteristics of high moisture and high volatility. When burning, the flame is long and smokey, and the degree of coalification is low. Typical coal types are lignite and long-flame coal. my country is rich in coal and lacks oil and gas. How to efficiently utilize low-rank coal has become a major issue in today's clean coal technology. However, whether it is combustion power generation or modern coal chemical utilization, the efficiency of comprehensive utilization is extremely low because of its three characteristics of h...

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Problems solved by technology

Due to CO 2 It cannot be combusted and is an ineffective gas, which reduces the energy density of the crude gas; and the crude gas contains a large amount of CH 4 hydrocarbons, reducing CO and H in syngas 2 content, the calorific value of crude gas is reduced, and it cannot be used as a primary raw material for chemical synthesis. In addition to returning to the furnace for combustion, the mixed gas produced by pyrolysis has no other economic value, and the utilization rate of coal raw materials is low; in addition, because part of the coal is mixed with Combustion of oxygen to produce CO 2 , leading to less amount of upgraded coal, and finally the amount of synthesis gas produced by upgrading coal is very small, which greatly wastes the effective resources in low-rank coal, and there is no relevant integrated equipment that can be used Continuous gas production from low-rank coal can also be used for continuous large-scale production

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