Low-temperature methanol washing technology capable of efficiently recycling pressure energy and cold energy

Abstract

The invention belongs to the technical field of energy and chemical industry, and discloses a low-temperature methanol washing technology capable of efficiently recycling pressure energy and cold energy. In the technology, methanol-rich liquid extracted from the side line and the bottom of a medium-pressure flash tower enters a CO2 regeneration tower after being throttled and depressurized; the technology is adjusted to be that the methanol-rich liquid firstly enters a newly added hydraulic turbine to do work through expansion so as to reduce temperature and pressure, further enters a newly added low-temperature cycle fluid heat exchanger to recycle low temperature cold energy, and then enters the CO2 regeneration tower; and heat exchange between the poorest methanol of a thermal regeneration tower and the methanol-rich liquid at the bottom of the CO2 regeneration tower is adjusted to be that the poorest methanol firstly enters a newly added pre-cooler to cool, the methanol-rich liquid at the bottom of the CO2 regeneration tower has been subjected to heat exchange of a methanol cycle cooler firstly enters the newly added low temperature cycle fluid heat exchanger to recycle low temperature cold energy, and then the poorest methanol exchanges heat with the methanol-rich liquid via a methanol-rich and methanol-poor heat exchanger. The technology provided by the invention can significantly recycle work and cold energy, and has significant economic benefits.

Description

technical field [0001] The invention belongs to the technical field of energy and chemical industry, and in particular relates to a low-temperature methanol washing process for efficient recovery and utilization of pressure energy and cold energy. Background technique [0002] Low temperature methanol washing is a gas purification process developed by Germany's Linde Company and Lutchi Company in the 1950s. It uses low-temperature methanol as the absorption solvent to remove the acidic components in the raw gas, so it is widely used in synthetic ammonia, natural gas desulfurization and urban gas purification and other industries. In the ammonia synthesis industry, the crude gas from the (coal) gas production unit is first converted into CO to the maximum extent by the carbon monoxide shift reaction of the shift unit 2 to produce H-rich 2 The shift gas (in which the molar concentration of CO is ≯ 0.4%), and then the shift gas is washed with low-temperature methanol, and the...

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Problems solved by technology

Among them, the absorption tower adopts low-temperature and high-pressure operation to enhance the adsorption effect, and the regeneration tower adopts low-pressure operation because it needs to desorb the acid gas from the rich liquid in a boiling state. There is a phenomenon of decompression during the circulation to the lean liquid, such as the side line and bottom of the medium pressure flash tower are rich in CO 2 and CO 2 / H 2 Methanol in S decompresses into CO 2 Regeneration tower, resulting in loss of pressure energy

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