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Washing and solvent recycling method for paper pulp obtained through organic solvent method

An organic solvent and recovery method technology, applied in the field of pulp and paper making, can solve the problems of difficulty in solvent recovery and complicated pulp washing process, and achieve the effects of reducing energy consumption, reducing trouble, and simplifying the washing process

Active Publication Date: 2016-06-15
QILU UNIV OF TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Aiming at the problems of complicated washing process and difficult solvent recovery of pulp obtained by solvent cooking, the present invention provides a simple and feasible washing method, which can separate solid pulp fibers, soluble substances in waste liquid, and cooking reaction medium (solvent) one by one out, and then achieve pulp washing and solvent recovery

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] The bamboo is used as raw material, and 85% formic acid is used as the reaction medium for cooking. The mass ratio of the reaction medium to the raw material is 7:1. It is cooked at a temperature of 140°C in a closed pressure-resistant reactor, and the reaction is 120min. Filtration to obtain extruded cooking waste and unwashed wet pulp.

[0029] Using formic acid as the organic solvent ①, the pulp is washed for the first time at a temperature of 90°C, and the pulp is fully washed in the form of multi-stage countercurrent to obtain the washing waste liquid ①, which is mixed with the extruded cooking waste liquid above, Then evaporate and concentrate at 50°C under a negative pressure of 0.1MPpa to obtain a residue rich in organic matter and a condensate, the condensate is formic acid, which can be directly used as a reaction medium for pulping. The pulp after the first washing is washed for the second time with methanol as the organic solvent ② at 50°C, and the pulp is f...

Embodiment 2

[0031] Using wheat straw as raw material, cooking with 60% ethanol as the reaction medium, the mass ratio of reaction medium to raw material is 8:1, cooking in a closed pressure-resistant reactor at a temperature of 200°C, and reacting for 120min to obtain the cooked product after pressure filtration , to obtain extruded waste liquor and unwashed wet pulp.

[0032] Using ethanol as an organic solvent, the pulp is washed at a temperature of 70° C., and the pulp is fully washed in the form of multi-stage countercurrent to obtain washing waste liquid. The washing waste liquid is mixed with the above extruded waste liquid, fully evaporated and concentrated at 78°C to obtain a residue and condensate rich in organic matter, and the washed pulp is evaporated and dried under reduced pressure at 40°C to obtain dried pulp and condensate liquid, all the condensed liquids are mixed, rectified and separated to recover ethanol.

Embodiment 3

[0034] Bagasse is used as raw material, and 70% acetone is used as reaction medium for cooking. The mass ratio of reaction medium to raw material is 6:1. It is cooked in a closed pressure-resistant reactor at 160°C for 120 minutes, and the cooked product is obtained by pressure filtration. Squeeze waste liquor and unwashed wet pulp are obtained.

[0035] Using acetone as an organic solvent, the pulp is washed at a temperature of 56° C., and the pulp is fully washed in the form of multi-stage countercurrent to obtain washing waste liquid. The washing waste liquid is mixed with the above extruded waste liquid, fully evaporated and concentrated at 50°C to obtain a residue and condensate rich in organic matter, and the washed pulp is evaporated and dried under reduced pressure at 40°C to obtain dried pulp and condensate liquid, all the condensed liquids are mixed, rectified and separated to recover acetone.

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Abstract

The invention relates to a washing and solvent recycling method for paper pulp obtained through an organic solvent method.The method comprises the following steps that paper pulp obtained by pulping through the organic solvent method is washed with one or more organic solvents, then the organic solvents in the paper pulp are evaporated out through evaporation drying, dry paper pulp is obtained, and organic solvent steam is recycled through condensation.The method is suitable for washing paper pulp obtained through the organic solvent method, the organic solvents are used in the whole washing process, involvement of water is avoided, clean dry paper pulp is directly obtained through evaporation drying after washing, and the washing process of paper pulp is simplified.According to the method, due to the fact that water involvement is avoided in the whole process, energy consumption in organic solvent recycling is reduced due to the low boiling point of the organic solvents when the organic solvents are separated and recycled; in addition, azeotrope is not generated, and the trouble brought by azeotropy on organic solvent recycling is saved.

Description

technical field [0001] The invention relates to a method for washing and solvent recovery of pulp obtained by solvent cooking. The method can separate solid pulp fibers, soluble substances in waste liquid, and solvent used for cooking one by one, thereby realizing pulp washing and solvent recovery. Pulp and paper technology field. Background technique [0002] Pulping and papermaking is a traditional industry. Pulping is the process of obtaining cellulose pulp by removing most of the lignin and part of the hemicellulose in the plant material. The plant material is chemically pulped to obtain pulp and waste liquid, which contains waste The liquid pulp is washed to obtain clean pulp, and then bleached to obtain white pulp, which is further paper-made to obtain paper or cardboard. [0003] The method of chemical pulping can be divided into two categories, one is to cook pulp by using chemicals such as acid, alkali and salt, such as caustic soda method, sulfate method and sulfi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C9/02D21C11/00
CPCD21C9/02D21C11/00
Inventor 王兆江秦梦华张永超
Owner QILU UNIV OF TECH
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