SU1033609A1 - Method for preparing sulfate cellulose for chemical processing - Google Patents

Abstract

A method of producing sulfate pulp for chemical processing by preliminarily hydrolyzing cellulose-containing raw material with a hydrolyzing agent and subsequent sulphate cooking, characterized in that, in order to reduce the amount of heat and fresh water, while preserving the quality of the hloma, the quality of the hous- ture of the hous- ture, and the quality of the hous- tures, the pre- ventures, the quality of the hloma, the quality of the hous- ture, and the quality of the hous- ture, the temperature of the hous- ture, the pre-quality, hous- mat, and the quality of the hous- ture, the pre-quality hous- ing material, the prematurity, the quality of the hlo, the quality of the houma, the quality of the hloma, the quality of the hlo, the quality of the hou, the quality of the houmaline, the h. from bleaching with chlorine-containing compounds in an acidic medium with a content of active chlorine in it of 10-100 mg / l.

Description

WITH

The invention relates to methods for producing sulphate pulp for chemical processing and can be used in the pulp and paper industry. A known method for producing sulphate viscose pulp by acid prehydrolysis of raw wood and subsequent sulphate cooking. The hydrolysis is carried out with dilute solutions of mineral acids with a concentration of 0.5-1 at 100-1iOc. Due to the high acidity of the hydrolyzing solution, prehydrolysis is carried out at low temperatures and therefore lower consumption of heat for prehydrolysis 1. The disadvantage of this method is the need to carry out a diffusion washing of chips, since the acid inside the chips after hydrolysis during the subsequent sulphate cooking neutralizes the cooking liquor penetrating into the chips, which causes its uneven penetration. In addition, due to the different effects on the apparatus of sour and sulphate cooking liquor, it is necessary to conduct the process in two apparatuses for prehydrolysis and cooking. The closest to the invention in its technical essence is a method for producing sulphate pulp for chemical processing by pre-hydrolysis of cellulose-containing raw material with a hydrolyzing agent and subsequent sulphate cooking. Prehydrolysis is carried out with water at 160-170 ° C 2 J. A disadvantage of the known method is the need to heat fresh water, which usually arrives at a temperature of 20 ° C, and the aqueous prehydrolysis is carried out at high temperatures, therefore the heat consumption for heating water during prehydrolysis is significant and amounts to 70-80% of the total heat consumption for prehydrolysis and sulphate cooking. In addition, during periodic boiling with prehydrolysis, after the blowing in the boiler circulation system, a certain amount of black liquor remains, which leads to a slowdown in the prehydrolysis rate and the need to increase the temperature or duration of the process. The method causes significant contamination of the environment. The aim of the invention is to reduce environmental pollution and reduce the consumption of heat and fresh water, while maintaining the quality indicators of pulp. The goal is achieved by the fact that according to the method of producing sulphate pulp for chemical processing by pre-hydrolysis of cellulose-containing raw material with a hydrolyzing agent and subsequent sulphate cooking, the filtrate from cellulose bleaching with chlorine-containing compounds in an acidic medium with an active chlorine content of 10-100 is used as a hydrolyzing agent . The acidity of the filtrates accelerates prehydrolysis. With an increase in the temperature of the filtrates, the heat consumption for prehydrolysis is increased, and the active chlorine contained in the filtrates has a slight oxidizing effect on the lignin, which facilitates the subsequent sulphate cooking. Example 1. 500 g of absolutely dry pine chips are subjected to preliminary hydrolysis in an autoclave with a capacity of 5 liters of fresh water with a pH of 7.8, hydromodule k: at. Temperature rise from 20. to 80 ° C is carried out in 20 minutes a. from 80 to 90 minutes, after 9.0 minutes at 170 ° C, blowing is carried out to a pressure of 1 atm. for 10 minutes and then the selection of the hydrolyzate. 1Depu is poured with white liquor at the rate of 18.5 active alkali (Nc) 20) to absolutely dry non-hydrolyzed chips, after which the temperature in the autoclave is raised to 90 minutes. The pulping process is carried out for 85 minutes at 170, the field of which is blown to O atm. and select the liquor “The welded pulp is washed with hot water. Yeast was grown on the hydrolyzate obtained during prehydrolysis (LK-22 culture; Example 2. 550 g of absolutely dry pine chips are subjected to preliminary hydrolysis by filtrate from cellulose bleaching stages with chlorine-containing compounds with pH 2, 100 mg / l residual chlorine content. Prehydrolysis and sulphate cooking was carried out in a similar way as described in example 1. On the RIDrolizate obtained during the prehydrolysis, drokhoii were grown (culture G-22).

Example 3. 550 g of absolutely dry pine chips are prehydrolyzed with a filtrate with a pH of 5.5 with a residual chlorine content of 10 mg / l. Prehydrolysis and sulphate cooking are produced in a similar way as described in Example 1..

Yeast was grown on the hydrolyzate obtained during the prehydrolysis (culture ZH-22K. The quality indicators are given in the table.

96,196,696.1 125123110.

0 4380370

12,910,511,0

6.7 10.3 7.2

Table continuation

Output yeast, 5 iJI, 3,7 zhey from PB,%

Yeast yield from initial sy3, 38 ", 3 3.15 pb,%

Protein content in yeast56, 0 52.1 5.0 zh,% The use of excess filters from the pulp bleaching stages on Prehydrolysis allows to obtain high-quality cord cellulose while also saving heat. Secondary heat from pulping is used for fresh water for prehydrolysis, can be used to heat water in the bleaching plant, which will reduce steam consumption for pulp production.

The proposed method allows to reduce environmental pollution. .

Claims (1)

METHOD FOR PRODUCING SULPHATE CELLULOSE FOR CHEMICAL PROCESSING by preliminary hydrolysis of cellulose-containing raw materials with a hydrolyzing agent and subsequent sulfate cooking, characterized in that, in order to reduce environmental pollution and reduce heat and fresh water consumption while maintaining the quality parameters of cellulose, they use hydrolysis as a hydrolysis agent bleaching with chlorine compounds in an acidic medium with an active chlorine content of 10-100 mg / l. GO GO> 1 1033609. 1