Process for co-preparing hydrogen and LNG from raw gas

Abstract

The invention discloses a process for co-preparing hydrogen and LNG from raw gas. The process sequentially comprises a decoking step, a primary pressurization cooling liquid separation step, a secondary pressurization step, a pretreatment step, a tertiary pressurization step, a deoxidation conversion step, a desulfurization step, a wet decarburization step, a methane concentration step, a hydrogen purification step and an LNG preparation step. According to the process, LNG is also prepared while hydrogen is prepared, so that effective components in the raw coke oven gas are fully utilized, and the waste of energy sources is reduced; besides, the raw coke oven gas is pressurized basically through three times of compression in different stages before CO conversion, so that the energy consumption of the whole process is reduced; in addition, impurities in the raw coke oven gas subjected to CO conversion are removed by adopting a vacuumizing pressure transformation system I and a vacuumizing pressure transformation system II to obtain product hydrogen with the purity as high as 99.9%, and the recovery rate of the hydrogen can reach 89% or above; and desorbed gas rich in methane is adsorbed and desorbed from the vacuum-pumping variable-pressure system 1 to be used for preparing LNG.

Description

technical field [0001] The invention relates to the technical field of raw gas treatment, in particular to a process for producing hydrogen from raw gas and co-producing LNG. Background technique [0002] Raw coal gas, also known as crude gas and coke oven gas, is unpurified gas produced by low-temperature dry distillation of coal. Its main components are shown in the following table: [0003] composition Raw gas (mol%) O 2 0.5～1.0 N 2 20～45 H 2 10～30 CO 10～20 CO 2 10～20 CH 4 5～10 cH 0.5～2 water saturated water [0004] In addition to the ingredients in the above table, raw coal gas also contains a small amount of tar, benzene, naphthalene, hydrogen sulfide, organic sulfur, HCN, NH 3 and other impurities. The content of impurities in common raw coal gas is shown in the table below: [0005] [0006] [0007] According to the different coal quality and treatment process, the components of r...

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Problems solved by technology

[0011](1) The technical solution recorded in the patent document "Application No.: 201810320196.0, Patent Name: A Process for Producing Hydrogen from Raw Coal Gas" can only Hydrogen is raised, other components of raw gas are wasted

[0012](2) Patent document "Application number: 201810042063.1, patent title: A method for producing hydrogen and LNG from coke oven gas" and application number: 201510850839.9, patent The title is: A process for producing metallurgical reduction gas and co-production of liquefied natural gas by using coke oven gas. Separating hydrogen and methane, the hydrogen pressure obtained will be very low. Generally, the hydrogen pressure is 1 / 4 of the intake pressure, so the hydrogen needs to be compressed again later, and the energy consumption of the device will be greatly increased.

[0013](3) Due to the low pressure of raw coal gas, generally only a few kilopascals and complex impurity content, it needs to be pressurized to a certain pressure before subsequent treatment, but according to the current situation According to technical records, compression energy consumption is relatively large during operation

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