Papermaking and pulping method capable of obtaining black liquor at high concentration

Abstract

The invention provides a papermaking and pulping method capable of obtaining black liquor at high concentration. In a digester, the inlet direction of a solid phase raw material is reverse to that of a concentrated alkali solution; at least two concentrated alkali solution distributors with different heights are arranged in the digester; a heating device is arranged on the outer side or the innerside of the digester; the evaporative condensate water which is produced in the concentration process of the black liquor is used as water for dilution of the concentrated alkali solution; slurry is washed by the reverse flow of fresh water and the slurry; the liquor ratio in the digester is adjusted to be (3-5):1; and the effective alkali concentration gradient is 90 to 6g / L. A countercurrent continuous digestion process is adopted; different residence time of solid and liquid phases in a digestion process is reasonably adjusted; the reasonable liquor ratio is guaranteed, the effective alkali content in the back liquor is controlled; the slurry is subjected to countercurrent washing by using fresh make-up water and high-temperature condensate water which is generated in the concentrationprocess of the back liquor, so the amount of water used in the digestion process can be reduced by 70 to 80 percent; the solid content of the back liquor can reach over 20 percent; and the power consumption of black liquor concentration is reduced by over 50 percent.

Description

technical field [0001] The invention relates to a papermaking and pulping method capable of obtaining high-concentration black liquor, and belongs to the interdisciplinary technical field of biomass energy and papermaking and pulping. Background technique [0002] The paper industry is well-known as a major water resource consumer and water polluter. The key to the problem is that the black liquor in pulping wastewater is difficult to biodegrade. In particular, the wood pulp black liquor concentration, incineration power generation, and alkali recovery treatment processes imitated to control straw pulp black liquor pollution are still not perfect and need further improvement. Among them, the concentration process requires a lot of energy consumption, which consumes the meager profits of the straw pulp pulping process, and also greatly increases the cost of the straw pulp production process, making it gradually lose its commercial competitiveness. Ultimately, most straw pulp...

AI Technical Summary

Problems solved by technology

[0006] The present invention aims at the problem that the solid-liquid phase residence time is the same in the cooking process of the existing intermittent or continuous alkaline pulping process, and the concentration of the black liquor discharged during the cooking process is low, and provides a black liquor by-product that can be conveniently obtained with a higher concentration, A papermaking pulping method that effectively reduces energy consumption in the subsequent black liquor concentration process and obtains high-concentration black liquor

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