A system and method for producing natural gas by low-temperature dry distillation of coal gas and co-producing hydrogen

Abstract

A system and method for low-temperature dry distillation of coal gas to produce natural gas and co-production of hydrogen, including a low-temperature dry distillation polygeneration unit, a water washing purification unit, a hydrogenation unit, a fine desulfurization unit, a pre-reformation unit, a methanation unit, and a pressure swing adsorption unit. In series, the low-rank coal sent by the coal preparation system is pretreated through the low-temperature dry distillation polygeneration unit, further purified through the water washing and purification unit, and all unsaturated hydrocarbons in the gas are converted into corresponding saturated hydrocarbons through the hydrogenation unit. Convert organic sulfur into H2S; reduce the content of H2S in the feed gas to <0.1ppm through the fine desulfurization unit; through the pre-reforming process, convert all the higher hydrocarbons above C2 in the low-temperature dry distillation gas into methane, which improves the utilization of carbon High efficiency; parallel co-production of hydrogen, which solves the need for high-purity hydrogen in the reduction of methanation catalysts and pre-reforming catalysts; realizes high-efficiency graded utilization of low-rank coals, with simple process flow and strong operability.

Description

technical field [0001] The invention belongs to the technical field of natural gas production, in particular to a system for producing natural gas by low-temperature dry distillation coal gas and co-producing hydrogen. Background technique [0002] my country's national energy conditions are "rich in coal, short of oil, and low in gas". Coal consumption accounts for more than 70% of primary energy consumption, and the end-use of coal is still dominated by traditional combustion, resulting in coal containing The precious chemicals cannot be effectively utilized, and the direct combustion of coal, especially low-rank coal, has a low calorific value, which not only wastes resources, but also causes serious environmental pollution. The graded utilization technology increases the added value of coal, increases the calorific value of coal, and reduces pollutant emissions. [0003] As an efficient, safe and clean fossil energy, the proportion of natural gas in global energy consumpt...

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Problems solved by technology

[0004] The methane content in the coal gas produced by the low-temperature dry distillation of coal is low, and the gas calorific value is low. The process cost of purifying methane directly from the coal gas is high, and the energy utilization rate is low, which is not conducive to industrial scale-up. Contains a lot of H 2 , CO and high-grade hydrocarbons and other valuable resources, directly passing the analytical gas into the boiler for combustion will lose the added value of coal and cause waste of resources, and it does not conform to the clean utilization route of coal

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