External circulation multi-effect evaporator for titanium dioxide waste acid

Abstract

The invention relates to an external circulation multi-effect evaporator for titanium dioxide waste acid. The titanium dioxide waste acid is pressed into a tube pass of a single-effect heater, and the waste acid flows in a plurality of tube passes back and forth and is subjected to heat exchange with steam in a shell pass of the single-effect heater; the waste acid is heated and is conveyed into a single-effect flash evaporation crystallization tank through a waste acid outlet pipe of the single-effect heater; in a vacuum environment in the tank, the waste acid is sprayed by a nozzle to form mist to suddenly cause flash evaporation; a lot of moisture in the waste acid is evaporated to form water steam and the titanium dioxide waste acid is concentrated; the concentration of the waste acid is improved and the temperature is reduced, so that one part of ferrous sulfate is separated out; supernatant liquor is conveyed into a tube pass of a double-effect heater through a single-effect acid conveying pump, and reaches the last effect according to the flow; finally, water steam in a last-effect flash evaporation crystallization tank enters a water spraying vacuum pump and the water steam is condensed; then the last-effect flash evaporation crystallization tank is vacuumized, and the concentrated titanium dioxide waste acid is discharged from a concentrated acid outlet pipe of the last-effect flash evaporation crystallization tank. The external circulation multi-effect evaporator for the titanium dioxide waste acid has the advantages of low energy consumption of a technical process, simple and convenient process, effectiveness, low possibility of blocking equipment, safety and reliability in operation and the like.

Description

Technical field [0001] The invention relates to a liquid concentration operation process in the chemical industry field, in particular to an external circulation multi-effect evaporator of titanium white waste acid. Background technique [0002] In the chemical industry, there are many liquid raw materials and semi-finished products that need to be concentrated and processed into products; in order to meet environmental protection requirements, the concentration treatment of waste acid and waste liquid generally adopts the operation process of steam heating and evaporation. [0003] For example, in the production of titanium dioxide by the sulfuric acid method, the most difficult to solve is the effective reuse of waste acid, because the waste acid with an acid concentration of about 20% accounts for 70% of the treated waste. The concentrated and impurity removal treatment of waste acid is reused Or reuse has always been a serious problem that is lingering and unacceptable in the i...

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Problems solved by technology

[0006] However, the above literature still failed to find a multi-effect evaporator with low energy consumption, simple treatment method, and suitable for small and medium-sized sulfuric acid titanium dioxide enterprises.

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