Method of recovering methanol from acidic gas in Rectisol unit

Abstract

The application discloses a method of recovering methanol from acidic gas in a Rectisol unit. The recovery process aims to the methanol in the acidic gas in the Rectisol unit, wherein wastewater fromthe bottom of a tail gas washing column is employed to wash the acidic gas, thus selectively absorbing methanol under low pressure at normal temperature to recover the methanol. The method not only increases recovery rate of methanol and reduces cost, but also reduces consumption of cooling capacity of the unit and avoids accumulation of impurities, such as hydrocarbons, organo-sulfur and the like.

Description

technical field [0001] The application relates to a method for recovering methanol in the acid gas of a low-temperature methanol washing device, which belongs to the technical field of gas purification. Background technique [0002] The low-temperature methanol washing process is a physical absorption gas purification process, which uses low-temperature methanol as a solvent to remove acid gases in the raw gas. Low-temperature methanol washing purification process can remove H in raw gas 2 S, COS, RSH, CO 2 , HCN, NH 3 , NO, paraffin, aromatic hydrocarbon, crude gas oil and other components, and can be dehydrated to make the gas completely dry, and the absorbed useful components can be recovered in the process of methanol regeneration; at the same time, this process has a high degree of purification, It has the characteristics of good absorption selectivity and low energy consumption, and methanol as an absorbent is cheap and easy to obtain, and its chemical stability and...

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Problems solved by technology

[0005] However, such a process has the problem of high energy consumption, mainly due to the high cooling capacity required for acid gas cooling, accounting for about 5% of the system cooling capacity, and in processes with high sulfur content in raw gas, this proportion Can reach more than 10%

In addition, this process can meet high-temperature gasification processes such as coal-water slurry gasification and pulverized coal gasification, but when supporting low-temperature gasification processes such as crushed coal gasification and catalytic gasification, due to the complicated side reactions in low-temperature gasification processes, It will produce more impurities such as light hydrocarbons and organic sulfur. Although these impurities can be removed in the low-temperature methanol washing device, when the methanol rich liquid that absorbs these impurities is regenerated, part of the methanol in the acid gas is also recovered. Hydrocarbons or organic sulfur impurities similar to the boiling point of methanol are also brought into the system with the condensation of methanol, which not only increases the energy consumption of the entire low-temperature methanol washing device, but also makes the quality of methanol worse due to the accumulation of impurities, thus affecting the absorption effect. Resulting in failure to meet purification targets

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