Method of combined production of methanol and liquefied natural gas in coking plant

Abstract

The invention belongs to the technical field of comprehensive coke-oven gas utilization, and particularly relates to a method of combined production of methanol and liquefied natural gas (LNG) in a coking plant. Coke-oven gas is subjected to temperature swing adsorption (TSA), desulphurization, vacuum pressure swing adsorption (VPSA), and other purifying treatment, and is subjected to cryogenic liquidation separation to obtain a liquefied natural gas (LNG) product. The main component of the non-liquefied part is (CO+H2), and is adopted as methanol synthesis gas used for producing methanol, wherein the insufficient carbon component based on the H2is supplied by continuous oxygen-rich gas production from chopped coke having a size of 7-24 mm by a normal-pressure gasifier. The method achieves direct utilization of CH4 that is one of the main components of the coke-oven gas, the (CO+H2) are directly used for methanol synthesis, and the insufficient carbon source is supplied by a normal-pressure gasifier adopting the chopped coke produced by the coking plant as a gas production raw material, and therefore intermolecular conversion and other main energy-consumption sections and high-investment devices are reduced, the whole process is simplified, the comprehensive energy consumption for producing the methanol and the liquefied natural gas (LNG) is low, the whole economic benefit of coking enterprises is increased, and the investment is saved.

Description

technical field [0001] The invention belongs to the technical field of comprehensive utilization of coke oven gas, in particular to a method for co-producing methanol and liquefied natural gas (LNG) in a coking plant. Background technique [0002] my country is a large country of coke production, and a large amount of coke oven gas is produced by-product in the coke production process. Large-scale coking plants, especially independent coking plants, must be equipped with feasible and effective coke oven gas comprehensive utilization devices. The composition of coke oven gas is relatively complex and unstable. Generally, the low calorific value of the purified coke oven gas is 17580-18420kJ / m 3 , the density is 0.45~0.48kg / m 3 , the main characteristics of the components are more hydrogen and less carbon. According to the volume fraction, CH in coke oven gas 4 Nearly 25%, CO, CO 2 、CH 4 , CnHm total about 40%, H 2 Can be as high as 60%. [0003] According to the composi...

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Problems solved by technology

[0010] The problems of this process are: in order to increase the methanol production, most of the coke oven gas needs to be converted into methanol synthesis gas. First, the coke oven gas needs to be converted into methanol synthesis gas through the conversion process. The requirements are high, and there is no "molecular economy"; the second is that the conversion section needs pure oxygen, and a large-scale air separation unit needs to be built, which greatly increases the investment. segment investment accounts for about 1 / 3 of the entire fixed asset investment

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