An Outflow Tube Type Falling Film Evaporator

Abstract

The invention relates to an external flow pipe type falling film evaporation device. The falling film evaporation device mainly comprises a shell, a heat exchange pipe unit, a liquid distributor and a demister, wherein the liquid distributor is connected with a circulating black liquid inlet; the heat exchange pipe unit comprises a steam inlet header pipe, an inner branch steam box pipe nest, an outer communicated steam box pipe nest and a heat exchange pipe nest, wherein the steam inlet header pipe is horizontally and fixedly arranged at the lower part inside the shell; the end of the steam inlet header pipe, outside the shell, is a heated steam inlet; the upper part of the steam inlet header pipe is communicated with the vertical inner branch steam box pipe nest; each vertical inner branch steam box pipe is provided with one end of the transverse heat exchange pipe nest; the other end of the heat exchange pipe nest is jointly connected to outer communicated steam box pipes; the bottom ends of multiple outer communicated steam box pipes are jointly connected to a condensed water header pipe; heat exchange pipe unit support pieces are used for fixation among the inner branch steam box pipes, the outer communicated steam box pipes and the shell; a secondary steam outlet is formed in the top of the shell; a circulating black liquid outlet is formed in the bottom of the shell. By virtue of the pipe type falling film evaporation device, the safe and stable operation of an evaporation station is effectively ensured and the production cost is lowered.

Description

technical field [0001] The invention relates to an alkali recovery technology in the field of straw pulp papermaking, in particular to an outflow tube type falling film evaporation device. Background technique [0002] The paper industry is one of the important basic industries in our country, and it is also one of the main industries that seriously pollute the water environment in our country. In the world, paper industry wastewater is an important source of pollution, which has attracted widespread attention. The problem of paper industry wastewater pollution has become a key factor restricting the survival and development of many paper companies. In recent decades, domestic and foreign technologies for the treatment of papermaking wastewater, especially papermaking black liquor, have been continuously developed. The most common and efficient method is to use evaporation technology to concentrate papermaking black liquor, recycle chemicals, and reduce environmental polluti...

AI Technical Summary

Problems solved by technology

[0005] At present, the evaporators used in pulp and paper mills internationally and domestically are mainly falling film evaporators, including plate falling film evaporators and internal flow tube falling film evaporators, but there are some problems in the equipment structure or operating conditions: plate falling film evaporators The heating element of the film evaporator is a poorly stressed structural part. When evaporating high-concentration black liquor, due to the high viscosity of high-concentration black liquor, it often needs to operate under high temperature and high pressure conditions. At this time, the welded part is easy to crack, affecting production, and the heating element is not easy to replace and repair after damage; the black liquor scale of the internal flow tube falling film evaporator is on the inner surface of the heat exchange tube, which is ring-shaped scale, which is more solid and hard to fall off. When the scale is serious, it needs to be shut down to remove Scale, reducing production efficiency

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