Modified technique for refined unit in acrylic acid production device

Abstract

The invention discloses an improved process for a refining unit in an acrylic acid production device. Acrylic acid gas generated by a second acrylic acid reactor is cooled in a reactant cooler and is absorbed in an absorption tower; liquid on the lower part enters a light component fractionating tower; azeotropic distillation is carried out to water, acetic acid and acrylic acid; toluene is used as azeotrope former. The improved process is characterized in that: in the reactant cooler, circulating wastewater on the bottom of a stripping tower is adopted for cooling inside a shell side; the temperature of a tube side reactant outlet of the reactant cooler is 65-70 DEG C; a gas-liquid separation tank is provided additionally; an absorption tower bottom cooler is canceled; the overhead reflux ratio of the light component fractionating tower is 6.5-7.0; a wastewater stripping tower is provided. The improved process has the advantages that: for a 140, 000 ton / year acrylic acid device, 12, 000, 000 yuan of operation cost, 6, 400, 000 tons of circulating water, 120, 000 tons of steam and 26, 000 tons of desalted water can be saved each year; the improved process can reduce the discharge amount of acrylic acid waste gas and wastewater, is adapted to the industrial policy of China about saving energy and reducing emission, and has remarkable economic benefit as well as obvious social benefit.

Description

technical field [0001] The invention relates to an improved process for a refining unit in an acrylic acid production device. Background technique [0002] Acrylic acid is produced by the two-step oxidation of propylene. After the reaction gas is cooled by a cooler, it needs to be absorbed with water in an acrylic acid absorption tower to form a crude acrylic acid solution containing 59% (wt) acrylic acid. Therefore, a large amount of water needs to be consumed. In the refining process of acrylic acid, the organic matter and water in the crude acrylic acid solution need to be separated through three towers to obtain acrylic acid products containing more than 99.50% (wt). A large amount of waste water containing organic matter (0.8t waste water / 1t acrylic acid) is produced in the refining process. [0003] In the existing acrylic acid production technology, take the 140,000 tons / year acrylic acid plant as an example. The acrylic acid gas generated by the second acrylic acid...

AI Technical Summary

Problems solved by technology

Since the boiling points of water, acetic acid, and acrylic acid are relatively close, the purification of acrylic acid by conventional rectification requires a large amount of steam, and conventional rectification requires a high temperature in the tower, which intensifies the tendency of self-polymerization of acrylic acid and affects the long-term stability of the device. run

In terms of environmental protection, it is not allowed to be directly discharged as waste water. Therefore, all current processes adopt thermal incineration or catalytic incineration for treatment, but the treatment cost is expensive and the operation is difficult.

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