Energy-saving one-step rectisol method

Abstract

An energy-saving one-step rectisol method belongs to the technical field of gas purification. The method is characterized in that two or three desulfuration segments of an absorption tower employ a sulfur-free semi-lean solution for absorption; intersegment coolers are adopted; the desulfuration segments can remove sulfide and approximately 50-60% of CO2 from virgin gas simultaneously; only one decarbonization segment of the absorption tower is adopted; a lean solution is used at the top of the tower, and the sulfur-free semi-lean solution is added; flash steam is absorbed by a sulfur-containing semi-lean solution in the medium-pressure flash evaporation process; after most of CO2 in the flash steam is absorbed, the solution is delivered to a lower tower of an H2S concentrating tower for gas stripping; a sulfur-free methanol solution gas stripping tower is additionally adopted and divided into one or two segments; solutions at the segments are heated appropriately before entering the tower; and the sulfur-free semi-lean solution is delivered to the absorption tower after the gas stripping. The energy-saving one-step rectisol method has the effects and benefits that the number of plates of the absorption tower is reduced by about 20%, the tower diameter is shortened, the circulation volume of a methanol lean solution is reduced, the regeneration load of a rich solution is also reduced, the energy consumption of a device is saved by about 30%, and the device investment is saved.

Description

technical field [0001] The invention belongs to the technical field of gas purification, and relates to a method for removing and recovering acid gas. Background technique [0002] The low-temperature methanol washing process (Rectisol) is a physical absorption gas purification process jointly developed by the German Linde company and Lurgi company in the 1950s. This process uses low-temperature methanol as a solvent to remove raw material gas acid gas in. 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...

AI Technical Summary

Problems solved by technology

Since the amount of washing liquid can account for 40% of the sulfur-containing methanol after flash evaporation, the proportion is relatively large, and the washing liquid CO 2 The concentration of the components is lower, and after confluence, the CO in the sulfur-containing methanol solution is reduced 2 concentration, which in turn affects the passage of sulfur-containing methanol through CO 2 The low temperature obtained by desorption increases the temperature of the lean liquid after heat exchange, which eventually leads to an increase in the amount of lean liquid in the absorption tower and an increase in energy consumption of the system

Images