PX oxidizing reactor for producing terephthalic acid

Abstract

A PX oxidation reactor for producing terephthalic acid comprises a reactor housing; the reactor housing is can-shaped, the ratio of height to diameter is 2.8 to 5, and the bottom of the reactor housing is provided with a distributed inlet duct and a spiral-flow type inlet duct; the distributed inlet duct comprises an upper air flow distribution tube and a middle air flow distribution tube, and theair flow distribution tubes are in the shape of circular rings; the number of spiral-flow inlet tubes is multiple, and the tubes are uniformly arranged surrounding the reactor wall. A combined air inlet gyration device used in the invention pushes the fluid at the bottom of the reactor by proper amount of air so that the reactor conducts rotary motion; the air has good dispersion and uniform distribution, and the material remains in normal suspended state; and the ratio of height to diameter between a high temperature reactor and a low temperature reactor is used, thereby avoiding non-uniformdistribution existing in the low temperature reactor with big ratio of height to diameter and also being better than the high temperature reactor in the aspect of low power consumption.

Description

technical field [0001] The invention relates to the field of chemical equipment, in particular to a PX oxidation reactor for producing terephthalic acid. Background technique [0002] At present, the production process of purified terephthalic acid (PTA) is: a mixture of raw material p-xylene (PX) and solvent acetic acid (HAC), in the presence of a catalyst, with oxygen in the air at a certain temperature and pressure The oxidation reaction is carried out to generate crude terephthalic acid (CTA), and the CTA is further refined to finally generate purified terephthalic acid (PTA). [0003] The PX oxidation reactor is the key equipment in this process, and different process oxidation reactors have different structural forms. From the enhanced mass transfer process, the reactor structure can be divided into two types: the first type is a non-stirred bubble column reactor; the second type is a tank reactor with agitator. The oxidation reaction of these two structural forms Th...

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Problems solved by technology

[0004] At present, the high temperature oxidation process is mainly used in the international production of PTA. The high temperature oxidation process has a fast reaction rate. It is advisable to use a stirred tank to enhance mass transfer and heat transfer. The production capacity per unit volume is high, the CTA crystal particle size is large, and the allowable water content in the reaction slurry High, only the tail gas condenser without additional dehydration equipment can meet the water content control requirements, the disadvantage is that the consumption of PX and HAC is high, the cost of the agitator and compressor is high, and the equipment manufacturing is difficult; compared with the medium temperature oxidation process Equipment requirements and PX and HAC consumption are relatively moderate, and the reactor can use a simple-structured bubble column instead of a stirred tank. The equipment investment and maintenance costs are low, and the energy consumption is low. The separation of CTA and mother liquor treatment is easier than the low-temperature process. The technical and economic indicators of this process are also close to or slightly better than those of the high-temperature oxidation process; while the low-temperature oxidation process uses a non-stirred bubble column to meet the mass transfer requirements, and the consumption of PX and HAC is low. The disadvantage is that the reaction slurry is required The water content in the feed is low, and an auxiliary dehydration device needs to be added. At the same time, the impurity content is high, the slurry must be post-oxidized, the crystal particle size is small, and the residue is large. It is only suitable for the preparation of medium-purity terephthalic acid (MTA or QTA). Suitable for the production of PTA

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