Application and Development of Defoamer in Paper Industry
As an important basic raw material industry, the pulp and paper industry occupies an important position in the national economy. The normal operation of the pulp and paper process will directly affect the economic profits of the pulp and paper industry.
Foam is a very important problem in pulp and paper production. Improper control of foam in the production process will seriously affect the implementation of pulp and paper process conditions and the normal operation of equipment, leading to reduced product output and quality. In the pulping process, the production and existence of foam will seriously hinder the normal process of pulp washing, screening, bleaching and beating. In the papermaking process, the foam problem has a greater impact on the implementation of the process conditions of the pulp flow and dewatering molding sections, and has a direct impact on the paper quality.
The most direct and effective measure to control foam is to add appropriate defoamer for papermaking.
At present, there are two main methods to control foam in pulp and paper industry: physical method and chemical method.
1. The physical method is to improve the permeability of gas at both ends of the bubble liquid film to promote the drainage of the bubble film, so that the foam attenuation factor is greater than the stability factor, thus reducing the number of foam. It mainly includes placing baffle or filter screen, high-speed centrifugation, steam, pressurization and decompression, etc.
2. Chemical method includes chemical reaction method and adding papermaking pulp defoamer method. The chemical reaction method is to reduce the concentration of foaming agent in the foaming system through the chemical reaction between the added specific reagent and the foaming agent, so as to promote the foam to burst; Adding papemaking defoamers can achieve the purpose of defoaming by changing the local surface tension of bubbles.
The bursting process of foam after adding defoamer
Although the physical method is environmentally friendly and reusable, it can only remove the surface foam in a short time, which is difficult to eliminate a large number of fine foam. It is greatly affected by environmental factors, and will also increase the equipment investment and maintenance costs of paper enterprises. The chemical reaction method needs to determine the composition of the defoamer for papermaking before practical application, and the insoluble substances produced by the added reagents and foaming agents will harm the equipment.
Production practice has proved that using papermaking pulp defoamer to control foam is the most economical and effective measure. This method does not need to change the original production process, nor does it need a lot of equipment investment and maintenance costs. It has ideal effect and is easy to operate. Papemaking defoamers has been widely used in the pulp and paper industry. With the continuous expansion of the pulp and paper industry market, the market for related chemical additives will continue to develop. The global paper mill is changing from acidic paper making to alkaline paper making, and alkaline paper making is operated under closed water circulation system, which will increase the use of antifoam and promote the development of paper making antifoam market.
