Plate-type down-film evaporator descaling method

Abstract

A method for descaling a plate-type falling-film evaporator belongs to the technical field of pulping and papermaking. The method is to completely soak the heat-exchange plate of the plate-type falling-film evaporator with white liquor containing NaOH concentration of 70-90g / L at first. 0.1-0.15MPa, temperature 110-130℃, soda boiling for 6-10 hours to make the fiber scale soft; then use a high-pressure water gun with a pressure of 400-500kg / cm2 to remove the fiber scale on the surface of the heat exchange plate. It can efficiently and thoroughly remove the fiber scale accumulated on the heat exchange plate. Compared with the traditional method, the descaling period of this method is extended from one month to three months, and the descaling time can be shortened by half each time. The descaling is thorough, and the efficiency of the plate falling film evaporator is greatly improved, thereby improving the production capacity of the equipment. .

Description

technical field [0001] The invention relates to a descaling method for a plate type falling film evaporator in the pulp and paper industry, in particular to a method for removing fiber scale on the surface of a heat exchange plate in the plate type falling film evaporator. Background technique [0002] At present, in the alkaline pulping and papermaking industry, the combustion method is generally used to recover the alkali in the black liquor produced in the pulping process to solve its environmental pollution problem, and the plate falling film evaporator is the main method for the evaporation and concentration of black liquor. However, due to the problem of a certain amount of fiber in the black liquor itself, the plate type falling film evaporator usually runs for about a month, and the surface of the heat exchange plate is relatively serious with fiber scale, and it is very hard and firm, so that it cannot achieve normal heat exchange. effect, which seriously affects th...

AI Technical Summary

Problems solved by technology

[0002] At present, in the alkaline pulping and papermaking industry, the combustion method is generally used to recover the alkali in the black liquor produced in the pulping process to solve its environmental pollution problem, and the plate falling film evaporator is the main method for the evaporation and concentration of black liquor. However, due to the problem of a certain amount of fiber in the black liquor itself, the plate type falling film evaporator usually runs for about a month, and the surface of the heat exchange plate is relatively serious with fiber scale, and it is very hard and firm, so that it cannot achieve normal heat exchange. effect, which seriously affects the evaporation efficiency. After the above problems occur, it is usually treated by washing with water, directly using a high-pressure water gun or pickling.

[0003] In the above treatment methods, washing with water and directly using high-pressure water guns not only takes a long time to stop, but also cannot effectively remove the fiber scale on the surface of the heat exchange plate, and will also lead to continuous accumulation of scale, resulting in the actual production capacity of the plate falling film evaporator. Gradually reduce, using pickling method to remove the fibrous scale on the surface of the heat exchange plate, not only requires high technical content, but also requires a professional descaling team, and the equipment of the plate falling film evaporator itself is seriously corroded, causing equipment damage