Comparison and Analysis of Refinery Dry Gas Properties

Refinery dry gas refers to various tail gases produced by the crude oil processing process，Including catalytic cracking dry gas, coking dry gas, catalytic reforming gas, thermal cracking gas, high-pressure hydrocracking tail gas, etc.The composition of various refinery dry gases varies greatly.

Hydrocracked dry gas, hydrofinished dry gas and reformed dry gas are substantially free of organic sulfur and olefins.The content of hydrogen sulfide after wet desulfurization is generally less than 20μg·g-1, which is a good raw material for hydrogen production.The content of olefins and organic sulfur in coking dry gas and catalytic cracking dry gas is relatively high.It must be hydrotreated to reduce the olefin and sulfur content before it can be used as a raw material for a hydrogen production unit.

Coking gas is the gaseous product of the residual oil after vacuum distillation of crude oil under normal pressure and high temperature thermal cracking, polymerization and coking reactions.Therefore, the content of olefins and organic sulfur is higher.In the past, the rich gas discharged from the coking unit was boosted by the compressor and then absorbed by diesel oil.The light gasoline components above C5 are recovered, and the components that are not condensed and absorbed are called coking dry gas.Coking dry gas contains certain olefins, which must be hydrotreated to reduce the content of olefins below 1v% to meet the requirements of conversion catalysts.Secondly, the content of organic sulfur in coking dry gas is relatively high, and the form of sulfur is relatively complex.Therefore, a desulfurization technology that can completely remove organic sulfur must be adopted to meet the requirements of the conversion catalyst for the total sulfur content to be less than 0.5 μg·g-1.

FCC dry gas is the main by-product gas in refineries.Since catalytic cracking is a cracking reaction under the action of a catalyst, compared with coking dry gas, its olefin content is higher (generally 10~15v%), and it also contains some oxygen, which are undesirable as raw materials for hydrogen production. of.If the oxygen content in the feed gas is high, it will have an adverse effect on the hydrogenation catalyst and consume a large amount of hydrogen in it. Usually, O2≯2v% in the feed gas should be controlled.

Coking dry gas and catalytic dry gas have been paid more and more attention as cheap raw materials for hydrogen production. Domestic hydrogen production units use coking dry gas and/or catalytic dry gas from refineries as raw materials for hydrogen production, and have successfully launched full coking and/or catalytic dry gas. Or catalytic dry gas hydrogen production process.

It can be seen that refinery dry gas, including coking dry gas, catalytic cracking dry gas, hydrogenation dry gas and reforming dry gas, will gradually become one of the main sources of raw materials for hydrogen production units.