System and process for producing natural gas through combined supply of coal and coke-oven gas

Abstract

The invention belongs to the technical field of energy and chemical engineering, and discloses a system and a process for producing natural gas through combined supply of coal and coke-oven gas. The system comprises a gasifying unit, an acidic gas removing unit, a methanation unit and a coke-oven gas purifying unit, wherein the gasifying unit is sequentially connected with the acidic gas removing unit; the coke-oven gas purifying unit is connected in parallel with the acidic gas removing unit and then is connected to the methanation unit. According to the process, raw coal is treated by the gasifying unit to generate rough synthesis gas; the rough synthesis gas is purified to remove sulfide and CO2 and generate clean synthesis gas; rough coke-oven gas is separated through the coke-oven gas purifying unit to obtain clean coke-oven gas; the coke-oven gas and the clean synthesis gas are mixed in ratio; the mixed gas is subjected to methanation by the methanation unit to generate natural gas. According to the system and the process, a water-coal conversion unit is saved; CO2 is recycled into the gasifying furnace to react again; meanwhile, the coke-oven gas replaces part of coal, so that the emission of CO2 and sewage in the gasifying process can be reduced, and the energy efficiency in the process is increased by not less than 8%.

Description

technical field [0001] The invention belongs to the technical field of energy and chemical industry, and in particular relates to a system and a process for producing natural gas through combined supply of coal and coke oven gas. Background technique [0002] China's resource endowment is characterized by "rich coal, poor oil, and little gas", and it is a country that uses coal as its main energy source. Although the proportion of natural gas consumption in basic energy consumption is still less than 5%, the consumption of natural gas is gradually increasing. The average growth rate of natural gas consumption in the past 10 years is 16%, of which the natural gas consumption in 2012 was 129.5 billion m 3 , an increase of 9.9% over 2011. During the "Twelfth Five-Year Plan" period, the proportion of natural gas in the basic energy consumption structure will increase from the current 4.4% to 7.5%. By 2015, my country's natural gas demand is expected to reach more than 250 bill...

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Problems solved by technology

[0004] Although the current coal-to-natural gas process has the advantages of mature technology and low production cost, there are still some shortcomings: First, since the coal gasification process in my country's coal-to-natural gas process mainly adopts Lurgi coal gasification technology, this coal gas Chemical technology will produce a large amount of phenolic wastewater, which is very difficult to treat and often has a certain impact on the surrounding environment

China's annual output of coke oven gas is about 35 billion standard cubic meters, however, except for 20% being directly burned as fuel, most of the coke oven gas is directly discharged into the atmosphere, wasting a lot of resources

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