Method for recovering and purifying hydrogen from semi-coke tail gas

Abstract

The invention discloses a method for recovering and purifying hydrogen from semi-coke tail gas. The semi-coke tail gas enters a two-stage pressure swing adsorption hydrogen purification device under lower pressure after being subjected to the processes of purification, first compression, desulfurization and the like, the first-stage pressure swing adsorption device is regenerated by using a flushing method to remove most of CO2 and C2 + in the semi-coke tail gas, meanwhile, part of N2, CO, CH4 and other impurity gases are removed, purified gas mainly containing H2 and N2 is obtained, the purified gas is subjected to secondary compression boosting and enters a second-section pressure swing adsorption device under the high pressure, and the product hydrogen with the H2 purity larger than or equal to 99% is obtained. The hydrogen in the semi-coke tail gas is recovered and purified through the two sections of pressure swing adsorption devices, most impurity gas is removed through the first section of pressure swing adsorption device under the conditions of no vacuum pump and low pressure, then the hydrogen is compressed and boosted to enter the second section of pressure swing adsorption device, and the method has the advantages of being high in hydrogen yield, low in energy consumption and especially remarkable in economic benefit.

Description

technical field [0001] The invention belongs to the field of coal chemical industry, in particular to the field of cleaning and comprehensive utilization of semi-coke tail gas, and specifically relates to a method for recovering and purifying hydrogen from semi-coke tail gas. Background technique [0002] Semi-coke tail gas is a by-product produced in the process of semi-coke production, and the annual production of semi-coke tail gas in my country exceeds 20 billion Nm 3 . Its main composition is shown in Table 1: [0003] Table 1 Main composition of semi-coke tail gas [0004] [0005] Because the semi-coke tail gas contains a large amount of impurities such as tar, benzene, naphthalene, phenol, dust, sulfide, ammonia, and heavy metals, it is very difficult to recycle. 2 , CO, CH 4 and other useful chemical resources, but there is no good way to recycle them. Often, the semi-coke tail gas can only be used as fuel for the initial combustion and utilization. This kind...

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Problems solved by technology

[0017] Chinese Patent No. CN 103275777 A discloses "a method for preparing hydrogen and liquefied natural gas from raw coal gas in carbonization furnace", and CN 108117047 A discloses "low-pressure sulfur-resistant transformation and proprietary adsorbent de-inerting technology for hydrogen production from raw coal gas", CN107758615 A discloses "a method for producing hydrogen from raw coal gas with low energy consumption and high yield", and CN 108609582 A discloses "a process for producing hydrogen from raw coal gas". Although these patents also use a two-stage pressure swing adsorption method to purify hydrogen , but the first-stage PSA and the second-stage PSA are not organically combined, so it is often necessary to use a vacuum pump for evacuation and regeneration in the first-stage PSA, which consumes a lot of energy and has a low removal rate of impurity gases , the total yield of hydrogen is also low

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