Compression heat pump rectification method and system for acetic acid concentration

Abstract

The invention discloses a compression heat pump rectification method for acetic acid concentration. The method comprises the following steps: an acetic acid solution is fed from the middle of a rectification tower, and the rectification tower performs rectification and concentration of the acetic acid solution; a part of a tower kettle liquid, as a tower bottom product, of the rectification toweris discharged from the rectification tower, and the other part of the tower kettle liquid enters a tower bottom re-boiler from the rectification tower; a tower top gas of the rectification tower enters a compressor, a steam compressed and heated by the compressor directly enters the tower bottom re-boiler, the tower kettle liquid entering the re-boiler is heated, the steam is condensed, and the heated tower kettle liquid is returned to the tower kettle; and a condensed liquid after condensation of the steam enters a backflow tank, a part of the condensed liquid, as a tower top product, is discharged from the backflow tank, and the other part of the condensed liquid, as a backflow liquid, is returned to the tower top of the rectification tower from the backflow tank. The invention also discloses a compression heat pump rectification system for acetic acid concentration. After adopting the above technical solution, the purpose of saving energy consumption at a relatively low cost is achieved.

Description

technical field [0001] The invention relates to a rectification technology for acetic acid concentration. Background technique [0002] Acetic acid is an important solvent. In the process of producing terephthalic acid by oxidation of p-xylene, acetic acid is usually used as a reaction solvent. The oxidation reaction of p-xylene will produce a large amount of water, resulting in the dilution of the acetic acid solvent. In order to maintain the acetic acid concentration in the acetic acid aqueous solution, the method of rectification is usually adopted to concentrate the acetic acid. [0003] Under normal pressure, the boiling point of acetic acid is 118°C, and the boiling point of water is 100°C. The relative volatility of acetic acid-water system is not large, and acetic acid has a strong association effect. High reflux ratio, high energy consumption. In order to save energy, azeotropic distillation is used in some processes to separate acetic acid and water, and the ent...

AI Technical Summary

Problems solved by technology

Although azeotropic distillation can reduce energy consumption, the price of acetate-type entrainer is high and it is a flammable medium, which increases the additional cost of separation

There are also some processes that use multi-effect pump rectification or multi-effect heat pump rectification, but these two methods will lead to a substantial increase in equipment investment

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