Integral process for washing and filtering terephthalic acid and water recovery

Abstract

The invention discloses an integral process for washing and filtering terephthalic acid and water recovery, comprising the steps of: pumping a PTA suspension from a PTA slurry tank by a pressure filter to a filter unit chamber with a surface filtrate tube of a rotary drum connected with a control joint; after filtering, collecting the mother liquid in a mother liquid collecting tank; then overflowing in high position to a mother liquid flash drum in which 0.008-0.020MPa (A) vacuum is generated; generating clean steam at 5-60 DEG C by flashing the mother liquid, and at the same time generating 0.008-0.20MPa (A) vacuum in an air cooler so that the clean steam at 5-60 DEG C is condensed to clean water in the air cooler. The recycled clean water can be used as primary and secondary washing water of the pressure filter so as to save water and reduce consumption.

Description

technical field [0001] The invention relates to a "filtering and washing" process of terephthalic acid (PTA) suspension and a "water recovery after filtering and washing" process. Background technique [0002] In the oxidation unit and refining unit of the existing terephthalic acid industrial plant, the three processes of "filtration, washing and pre-drying" of the terephthalic acid (PTA) suspension adopt the traditional "centrifuge filtration, tank washing, Vacuum centrifuge filtration" process technology, the disadvantages of this process technology are: [0003] ① Long process flow and many redundant operations [0004] The "filtration, washing, and pre-drying" of the terephthalic acid suspension are completed in three equipments: "pressure centrifuge, washing tank, and centrifuge", and auxiliary equipment such as transfer pumps and matching pipelines are required between the equipment , pipe fittings, valves, etc., the control process is long, and there are many redun...

AI Technical Summary

Problems solved by technology

[0003] ① Long process flow and many redundant operations

[0004] The "filtration, washing, and pre-drying" of the terephthalic acid suspension are completed in three equipments: "pressure centrifuge, washing tank, and centrifuge", and auxiliary equipment such as transfer pumps and matching pipelines are required between the equipment , pipe fittings, valves, etc., the control process is long, and there are many redundant operations, which is prone to filtrate leakage, which is harmful to personal safety and corrosive to equipment and plant floors.

[0005] ②The equipment is bulky and consumes a lot of energy

Since the washing is operated under normal pressure, the equipment volume of the primary washing tank and the secondary washing tank is large, the amount of process water required for washing is large, and the energy consumption is high, which leads to an increase in the load of the subsequent centrifuge

[0007] ③There are many moving equipment and the failure rate is high

[0008] The pressure centrifuge used to filter the terephthalic acid suspension and the centrifuge used to extrude (pre-dry) the terephthalic acid suspension are high-speed dynamic equipment, and the failure rate of the equipment is high, and the long-term cycle cannot be guaranteed. operation, it is easy to affect the normal production; the terephthalic acid filter cake is highly viscous, and the filter element of the centrifuge needs to be cleaned or replaced; Way

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