Failure Analysis And Process Optimization Of Mechanical Pulp Waste Evaporation Recovery System

In this paper, the process of alkali recovery evaporation system eucalyptus chemical mechanical Pulp wastewater of a large factory in Guangxi was site investigation analyzed and studied. Chemical mechanical pulp wastewater has the characteristics with low concentration and high pollution load. With the general approach is difficult to achieve, the pulp and paper industry pollution emission standards (GB3544-2008) requirements. Use the evaporation system can meet emission requirement from (GB3544-2008). But knowing that plugging problems of alkali recovery evaporation system during operation has often been plagued by enterprises. Now enterprises only take the measures of regular boiled and mechanical chemical pickling to alleviate evaporation problem. While evaporation efficiency improved, but failed to completely resolve plugging of evaporator.This paper in-depth studied on the problem of evaporation system easy to plugging. Plugging of tank mainly due to excessive fiber content of dilute black liquor. Black liquor from mechanical that the average fiber content of up 112.9ppm, Much higher than the diluted black liquor evaporation system into an average fiber content requirements lower than the design value 50ppm’s.To resolved plugging problems, it is necessary to reduce the fiber content of dilute black liquor, evaporation system to optimize the design process, add pressure black liquor filtering machine and dilute black liquor clarifying tank on evaporation system technology. Using non-silicon hydrogen peroxide bleaching stabilizer substitute sodium silicate in the pulp and mechanical pulp bleaching process and add scale inhibitors and defamers to forced circulation effect to IV effect, timely and effective suppression of black liquor tank blistering prevent fouling.After evaporation system optimized design process average mechanical pulp fiber content processing dilute black liquor will drop to 33.83PPM, the fiber content of dilute black liquor comply to evaporators design requirements, can reduce the efficiency of irrigation and prevent fouling plugging problems. Meet at a concentration of 1.5%-2.0% after mechanical pulp waste through the evaporator concentrate concentration reached 45%, and then after a forced circulation evaporator concentration of more than 65%, in line with the recovery boiler combustion requirements. After evaporation system optimized before optimization consumes less than 54000 tons of steam one year, the annual festival running costs 3.83 million RMB, have a good social and economic benefits.