A method for adsorption, extraction, separation and purification of high alkynes in crude acetylene gas

Abstract

The invention discloses an adsorptive extraction separating and purifying method for high alkyne in raw acetylene gas. The adsorptive extraction separating and purifying method comprises the followingsteps: the raw acetylene gas in which the content of the high alkyne exceeds 40 to 200ppm is sequentially subjected to working procedures of adsorptive enrichment, extraction desorption and extracting agent regeneration, wherein in the working procedure of the adsorptive enrichment, the high alkyne in the raw acetylene gas is used as adsorbate which is adsorbed by an adsorbent, and acetylene as anon-adsorptive component is separated and purified; the content of the high alkyne in an acetylene product is smaller than 20ppm; in the working procedure of extraction desorption, the residual highalkyne adsorbed in a dead space of the adsorbent and an adsorption tower is dissolved out and enters the working procedure of extraction regeneration, so that the high alkyne is recovered, and a regenerated extracting agent is treated and then returns to the working procedure of extraction desorption for recycling. According to an adsorption-extraction desorption process, the problems of no compliance of purity of the acetylene product (overproof content of the high alkyne), high solvent consumption, secondary pollution, high energy consumption and difficulty in temperature swing adsorption and desorption in an existing method are solved.

Description

technical field [0001] The invention belongs to the technical field of chemical separation and purification, and more specifically relates to a method for adsorption, extraction, separation and purification of high alkynes in crude acetylene gas. Background technique [0002] Acetylene is one of the important raw materials of petrochemical industry. Some products must be produced from acetylene, and ethylene is difficult to replace. For example, the important monomers of plastics and resins are vinyl chloride, vinyl ether, acrylate, vinyl acetate, 1,4- Butanediol, vinyl acetate, synthetic rubber monomer butadiene, 2-chlorobutadiene, isoprene, synthetic fiber monomer acrylonitrile, hexamethylenediamine, and organic chemical products and solvents acetaldehyde, acetic acid, ethyl anhydride, acetone, tetrachloroethane, etc. Since acetylene is a flammable, explosive and unstable compound, the encounter of alumina, copper compounds, iron compounds, activated carbon and other subs...

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Problems solved by technology

However, there are many problems in this temperature swing adsorption (TSA) adsorption and desorption cycle operation. First, there is a risk of explosion caused by local accumulation or concentration of high alkynes in the adsorption and desorption cycle operation. Second, desorption regeneration requires a heat carrier. Adsorption is completed instantaneously, but desorption matching steps are difficult to achieve; third, the desorption heating temperature is around 100-200°C, and high temperature will also cause explosion hazards in the acetylene system; fourth, at room temperature, acetylene and homokyne The adsorption separation coefficient is relatively small, and there is a serious co-adsorption phenomenon, which leads to serious waste of acetylene and low adsorption efficiency; There is a danger of catalytic decomposition and implosion of acetylene and its higher alkynes, especially in the working conditions of higher temperature or higher pressure

Therefore, silica gel or molecular sieves with relatively high silica-aluminum ratio are generally used, which are easy to adsorb, but difficult to regenerate. For example, a higher desorption temperature is required, 200~250°C; sixth, due to frequent temperature changes, the adsorbent is subjected to excessive temperature stress. , so that the service life of the adsorbent is greatly reduced

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