A scraped rectification tower for refining adiponitrile and adiponitrile refining process

Abstract

The invention provides a scraper rectifying column and process for refining adiponitrile. The scraper rectifying column comprises a column body and a liquid blanking pipe, as well as a scraper evaporator, a material circulating hole, a liquid phase outlet and a circulating pump, wherein the tower body internally comprises a filler layer and a plate type layer; the scraper evaporator is mounted at the outer part of the column body in a sealing manner and below the last column plate of the plate type layer; the material circulating hole is formed in the plate type layer and outside the column body; the liquid phase outlet connected with the material circulating hole through the circulating pump is formed in the bottom part of the tower body. The scraper rectifying column and process for refining adiponitrile have the beneficial effects that a special column structure is adopted, adiponitrile is separated from other dissolved foreign matters by adopting a crystal separation method, and thus the adiponitrile product can be recovered to the maximum while high-purity adiponitrile products are obtained, the problem of coking and blocking at the bottom part of a traditional rectifying column can be effectively solved, the purity of the product is improved, and the adiponitrile products can be recovered to the maximum.

Description

technical field [0001] The invention belongs to the technical field of chemical production process equipment, and in particular relates to a scraped rectification tower for refining adiponitrile and a process for refining adiponitrile. Background technique [0002] The existing rectification tower used in the production of adiponitrile includes a tower body with several layers of trays in the tower body, a product outlet on the top of the tower body, a raw material inlet in the middle and upper part of the tower body, and a tower body above the raw material inlet. There is a reflux inlet, a material circulation heating outlet and a material circulation heating inlet at the bottom of the tower, and a heavy component discharge outlet at the bottom of the tower, between the first tray (that is, the bottom tray) and the second tray of the tower body There is a recirculating heavy component inlet between them. The disadvantage is that during production, part of the material at t...

AI Technical Summary

Problems solved by technology

The disadvantage is that during production, part of the material at the bottom of the tower is sent to the first tray for circulation. Due to the change of the material composition of the first tray, the heavy component increases, resulting in the occurrence of heavy components on the upper trays. Changes, which eventually lead to an increase in the content of heavy components in the overhead distillate and poor product quality

[0003] In the production process of adiponitrile, the separation and purification of adiponitrile is mostly carried out by rectification, but the operation of the adiponitrile refining tower is very difficult, and the bottom material of the adiponitrile refining tower is easy to coke, and the additives in the product are crystallized Blocking the heat exchanger at the bottom of the tower affects the normal production process

The existing coupling system of thin-film evaporation and rectification system for heat-sensitive materials has no circulating pump at the bottom of the rectification tower. If it is not operated properly, it will still cause coking of the bottom material and precipitation of solid substances. The traditional evaporation method is one-time evaporation. , and the evaporation area is limited, so that the evaporation of the material is not complete, and the rectification rate is low; after the gas-liquid separation treatment, mist entrainment will still occur, and the separation degree will be affected

like figure 1 As shown, adiponitrile is refined using the traditional process, wherein the components at the bottom of No. 1 rectification tower 1 need to be strictly controlled, otherwise the impurities dissolved in adiponitrile will block the bottom of the tower due to improper operation, resulting in shutdown; The components at the bottom of distillation tower 2 need to be strictly controlled, and a certain amount of adiponitrile must be contained in the bottom of No. 2 rectification tower 2 to ensure that the bottom of No. Nitrile waste

Images