A method for hydrogenation of medium and low temperature coal tar

Abstract

The present invention relates to a medium and low-temperature coal tar hydrogenation process. The hydrogenation process comprises: S1, mixing medium and low temperature coal tar, and performing primary filtration, three-stage demineralization, secondary filtration and dehydration on the obtained raw material; S2, mixing the raw material oil after dehydration with hydrogen, and feeding the mixture sequentially into a reactor NO.1, a reactor NO.2 and a reactor NO.3, and feeding the mixture into a thermal high-pressure separator during hydrorefining process; S3, feeding gas separated from the thermal high-pressure separator into a cold high-pressure separator, and feeding the separated liquid into a thermal low-pressure separator; feeding the liquid separated from the cold high-pressure separator into a cold low-pressure separator, and feeding the obtained liquid after separation into a distillation column; extracting a naphtha component from the top of the distillation column and a diesel oil component from the middle of the distillation column; and S4, feeding tail oil in the bottom of the distillation column into a reactor NO.4 and a reactor NO.5 for hydrocracking, and then feeding the tail oil into the thermal high-pressure separator. By adopting the lightening process in the present invention, the oil yield and cracking level can be better controlled.

Description

technical field [0001] The invention relates to a method for hydrogenation of medium-low temperature coal tar, which belongs to the technical field of coal chemical industry. Background technique [0002] Coal tar is a liquid product in the process of coal gasification, coke production, semi-coke (semi-coke) production and low-rank coal processing and upgrading. Coal tar raw materials generally contain more impurities such as water, coal powder, chlorides, sulfides, oxides, polyenes, and alkali metals. According to different production methods, the following four tars can be obtained: high-temperature coal tar, referred to as high-temperature tar ( 900°C-1000°C); medium-temperature vertical furnace coal tar, referred to as medium-temperature coal tar (700°C-900°C); low-temperature, medium-temperature generator coal tar, referred to as medium-low temperature coal tar (600°C-800°C); low-temperature pyrolysis Coal tar, referred to as low-temperature tar (450°C-650°C). [0003...

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Problems solved by technology

Although the above methods have all realized the hydrogenation catalysis of the whole fraction of coal tar, there are still some defects: such as the catalyst has a short service life and low activity; the reaction device is complicated and the investment is large; there is no high-temperature coal tar, and frequent shutdowns are required for maintenance; Especially in the process described in CN101781577A, the fresh water consumption in the hydrogenation process is very large; the oil product refined from the first stage is separated by heat and low pressure, and the liquid is dehydrated, and partly returns to the raw material for recycling, and partly goes to the second stage cracking reaction, and the refining stage has a return cycle line, indicating that the effect of the catalyst is not ideal, and correspondingly, the size of the equipment and the amount of the catalyst need to be increased. The increase in the circulation rate will also reduce the service life of the catalyst, increase the energy consumption of the operation, and cause waste of resources; and the refined part of the process Entering the second-stage cracking reaction, the oil contains qualified product oil less than 330°C, and enters the second-stage cracking reaction without cutting and separation, resulting in part of the qualified product oil being cracked to generate gas, reducing oil yield, increasing hydrogen consumption, and increasing Operating costs

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