Nitrogen closed-loop cyclic regeneration type propylene dehydration method and device

Abstract

The invention discloses a nitrogen closed-loop cyclic regeneration type propylene dehydration method. According to the method, on the basis of the traditional propylene dehydration process flow, three devices, namely, a nitrogen cooler, a nitrogen demister and a nitrogen filter, are additionally arranged among the nitrogen discharge pipelines of a first adsorption / regeneration tower, a second adsorption / regeneration tower and the nitrogen inlet pipeline of a nitrogen fan and are serially connected end to end through a pipeline, so that the original nitrogen open-loop molecular sieve regeneration process is updated to a nitrogen closed-loop cyclic molecular sieve regeneration process. According to the invention, with the adoption of the nitrogen closed-loop cyclic molecular sieve regeneration process which is isolated from the outside and free from air entrainment, the destructive effect of CO2 in air on the adsorption aperture of a molecular sieve is prevented, and the service life of the molecular sieve is prolonged; the recovered monomer propylene is not contacted with air, so that dangers are eliminated; and nitrogen is cyclically utilized, so that energy is saved.

Description

technical field [0001] The invention relates to the technical field of removing trace water in propylene in a polypropylene device, in particular to a nitrogen closed-circuit cycle regeneration type propylene dehydration method. Background technique [0002] In the polypropylene industrial plant, the monomer propylene contains H 2 O, S, O 2 , As, CO and other impurities, these impurities affect the activity of the catalyst in the polymerization reaction and reduce the isotacticity of the polypropylene product. Therefore, the monomer propylene needs to be purified before the polymerization reaction to remove H 2 O, S, O 2 , As, CO and other impurities, where H 2 O content is an important indicator to measure the purity of monomer propylene. In the polypropylene industrial plant, when the H in the monomer propylene 2 When the O content ≥ 20ppm, the polymerization reaction is significantly affected, when the H 2 When the O content is ≥100ppm, the polymerization reaction ...

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Problems solved by technology

[0005] ①The molecular sieve is regenerated by using nitrogen to open the circuit. While taking out the molecular sieve to absorb moisture, it also takes out a small amount of free monomeric propylene and a small amount of molecular sieve powder remaining on the surface of the molecular sieve. Combustion and explosion, dangerous

[0006] ②Using nitrogen open circuit to regenerate molecular sieves not only makes air have the opportunity to mix into nitrogen, but the O in the air 2 It has a destructive effect on the adsorption pore size of molecular sieves, and a large amount of nitrogen gas is exhausted, causing great waste and energy consumption

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