Method for filtering, washing and separating crude terephthalic acid by using oxidizing unit of fine terephthalic acid device

Abstract

The invention relates to a method for filtering, washing and separating crude terephthalic acid by using an oxidizing unit of a fine terephthalic acid device. In the method, the aim of removing acetic acid is fulfilled by crudely filtering a crude terephthalic acid suspension and replacing acetic acid in the terephthalic acid by alternatively and repeatedly washing the crude terephthalic acid in sequence with fresh water. In the method, an integrated equipment-press filter is adopted to replace multiple sets of equipment including a vacuum centrifuge, a drier, a washing tower and a powder tank in the conventional process device, so that the equipment quantity is reduced, the flow is shortened, the process operability is enhanced, and a process for separating acetic acid from the crude terephthalic acid can be implemented in one press filter.

Description

technical field [0001] The invention proposes an integrated method of "filtering, washing and separating" crude terephthalic acid in an oxidation unit of a purified terephthalic acid plant, and relates to the technical field of energy saving and consumption reduction in the oxidation unit of a purified terephthalic acid plant. Background technique [0002] In the oxidation unit of the existing PTA industrial plant, the "filtration, washing, and separation" process of crude terephthalic acid adopts the traditional "centrifuge filtration or vacuum filtration-steam rotary drying-air flow conveying-tank beating" process technology, process flow block diagram see figure 1 . [0003] In the oxidation unit of the PTA industrial plant, a large amount of acetic acid is contained in the crude terephthalic acid suspension after the reaction. The process method is: first use a centrifuge or vacuum filter to coarsely filter the crude terephthalic acid suspension, and the filtered crude...

AI Technical Summary

Problems solved by technology

[0005] ① Long process flow and many redundant operations

[0006] The "filtration, washing, and separation" processes of the crude terephthalic acid suspension need to be completed in multiple sets of equipment such as "centrifuges, dryers, washing towers, and powder tanks", and transfer pumps, fans, etc. are required between the equipments. Auxiliary equipment and matching pipelines, pipe fittings, valves, etc. have a long process flow and many redundant operations, which are prone to leakage of filtrate (acetic acid), which is harmful to personal safety and corrosive to equipment and plant floors.

[0007] ②There are many moving equipment and the failure rate is high

[0008] The vacuum centrifuge used for crude terephthalic acid suspension is a high-speed equipment with a high failure rate, which cannot guarantee long-term operation of the equipment and easily affects normal production; the filtered crude terephthalic acid filter cake is highly viscous and needs to be cleaned Or replace the filter element of the vacuum centrifuge; in industrial installations, in order to ensure normal production, the vacuum centrifuge adopts the method of one opening and one standby

[0009] ③The equipment is bulky and consumes a lot of energy

[0010] The crude terephthalic acid filter cake filtered by the vacuum centrifuge still contains a large amount of acetic acid, which needs to be removed by heating and evaporating with a dryer, and the dryer uses The most popular is the steam tube rotary cylinder dryer. This dryer is not only bulky, but also requires a large amount of steam and high energy consumption to evaporate a large amount of acetic acid in the crude terephthalic acid filter cake.

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