Prospects for adapting best available techniques in pulp and paper production to the conditions of domestic enterprises

Abstract

In the process of obtaining cellulose with a low Kappa number, the main focus is on extended delignification at the cooking stage, which improves the yield of unbleached cellulose. However, despite the installation of flushing presses to enhance flushing, the problem of low selectivity of single-stage oxygen-base bleaching remains unresolved. Studies show that deep delignification can be achieved under certain humidity conditions and prior air removal, which minimizes diffusion resistance. The kinetics of mass transfer processes and chemical reactions plays a key role in the production of cellulose, where a combination of high selectivity of delignification and minimization of environmental impact is required. The efficiency of the processes of silicification and bleaching depends on the rate of mass transfer of reagents and their interaction with the inner surface of the fibers. A two-stage LCC with a controlled dosage of an alkaline reagent allows you to maintain a low reaction rate and a high degree of utilization of the exposed surface. However, the introduction of new technologies, such as modified cooking and two-stage chemical reaction, faces problems associated with an increase in the capacity of production flows and the accumulation of dissolved substances. This leads to a deterioration in the quality of the pulp and an increase in the toxicity of wastewater. As a result, adapting new technologies to the conditions of domestic enterprises remains a difficult task requiring further research and process optimization. The reasons preventing the introduction of the best available technologies at domestic CBP enterprises are considered.