Chemi-mechanical pulping high-concentration filtrate treatment method

Abstract

The invention relates to a chemi-mechanical pulping high-concentration filtrate treatment method. The method comprises the following steps: 1, feeding high-concentration filtrate generated by a chemi-mechanical pulping production line into a chemical pulp hot water tank, adding washing water, and performing mixing; 2, pumping out a mixed solution of the high-concentration filtrate and the washingwater in the chemical pulping hot water tank, feeding the mixed solution into a drum-type vacuum pulp washer, and filtering the obtained pulp layer; 3, feeding a mixed solution of the high-concentration filtrate obtained by filtering the pulp layer in the drum-type vacuum pulp washer and the washing water into a black liquor tank for temporary storage; 4, pumping out the solution in the black liquor tank, mechanically filtering the solution, feeding the filtered solution into the evaporation section of an alkali recovery workshop, and carrying out evaporation concentrating through a multi-effect evaporator; and 5, feeding the evaporated and concentrated solution meeting process requirements into an alkali recovery boiler, combusting the solution, feeding the obtained melt into a green liquor tank, and performing causticization treatment to recover the alkali liquor. Most fine fibers can be removed, the scaling phenomenon of an alkali recovery evaporator is effectively reduced, the evaporation efficiency is improved, and energy consumption is reduced.

Description

technical field [0001] The invention belongs to the field of chemical-mechanical pulp high-concentration filtrate treatment, in particular to a chemical-mechanical pulp high-concentration filtrate treatment method. Background technique [0002] At present, the high-concentration filtrate produced by the chemical-mechanical pulp production line has the characteristics of high temperature (about 80°C) and high COD content (generally 15000-20000ppm). It is not only difficult to operate and costly to treat wastewater through anaerobic or aerobic methods. ; Therefore, some enterprises now use the method of evaporating and concentrating at the evaporation station and then sending alkali to recover and incinerate the high-concentration filtrate of chemical-mechanical pulp. However, there are still certain problems, because the high-concentration filtrate of chemical-mechanical pulp contains a large number of fine fibers. After the evaporator contacts the filtrate, it is easy to be ...

AI Technical Summary

Problems solved by technology

[0002] At present, the high-concentration filtrate produced by the chemical-mechanical pulp production line has the characteristics of high temperature (about 80°C) and high COD content (generally 15000-20000ppm). It is not only difficult to operate and costly to treat wastewater through anaerobic or aerobic methods. Therefore, some enterprises now use the method of evaporating and concentrating at the evaporation station and then sending alkali to recover and incinerate the high-concentration filtrate of chemical-mechanical pulp. However, there are still certain problems, because the high-concentration filtrate of chemical-mechanical pulp contains a lot of fine fibers. After the evaporator contacts the filtrate, it is easy to be covered and scaled by fibers, forming a thermal insulation layer and reducing the evaporation efficiency, resulting in higher processing costs

Disposal of substandard wastewater discharge will cause a series of environmental problems

Images