Ethylene glycol recovery device of polyester wastewater recovery system and ethylene glycol recovery method

Abstract

The invention relates to an ethylene glycol recovery device of a polyester wastewater recovery system. The ethylene glycol recovery device of the polyester wastewater recovery system is characterized by comprising a primary-effect heater (1), a primary-effect gas-liquid separator (2), a secondary-effect heater (3), a secondary-effect gas-liquid separator (4), a tertiary-effect heater (5), a tertiary-effect gas-liquid separator (6), a first-stage condenser (7), a second-stage condenser (8), a heat exchanger (10) and an ethylene glycol rectifying tower (11). The ethylene glycol recovery device of the polyester wastewater recovery system has the advantages of being low in energy consumption, high in product quality and good in equipment use stability.

Description

technical field [0001] The invention relates to an ethylene glycol recovery device and an ethylene glycol recovery method of a polyester wastewater recovery system. Background technique [0002] Domestic enterprises in the production of polyester (PET) generally adopt the direct esterification method using terephthalic acid and ethylene glycol as raw materials, and the concentration of COD in the wastewater discharged during the production process of the esterification process is about 18000-40000 mg / L between. The main organic pollutants in wastewater are ethylene glycol, acetaldehyde and heterocyclic organic compounds, among which acetaldehyde, a volatile component, accounts for about 50% of the total organic pollutants. At present, the international and domestic traditional technology is to use the air stripping method to treat the esterification wastewater, and the waste gas after the air stripping is sent to the combustion furnace for incineration, which can save part...

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Problems solved by technology

[0004] 1. High energy consumption: the monoethylene glycol distillation tower is calculated with a feed rate of 3.5T / h, and the demand for heat transfer oil is 1800KW / h (temperature is about 180°C, flow rate is 140m 3 / h), high energy consumption

[0005] 2. The quality of the recovered ethylene glycol product is poor: the temperature of the heat transfer oil used for heat exchange is relatively high. During this process, some organic substances such as ethylene glycol and heterocycles will undergo chemical reactions under high temperature, causing the ethylene glycol to start to turn yellow. , ethylene glycol product color value (b value) > 6, the recovery effect becomes poor, and the recovered ethylene glycol has an impact on the stability of polyester production

[0006] 3. Great impact on the equipment: Due to the high heating temperature of the heat transfer oil, ethylene glycol and other organic substances tend to form polymers with high viscosity at high temperatures, which adhere to the tower packing. After the equipment has been running for a period of time, it needs to be cleaned and the device must be shut down. , bringing instability to the system

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