SU996578A1 - Method of producing cellulose for chemical processing - Google Patents

Description

The invention relates to pulp and paper industry and can be used in the manufacture of pulp for chemical processing. A known method for the production of cellulose for chemical processing, the slugging of precursors in the preliminary hydrolysis of the initial CJ slow-extracting agent and the sulphate cooking of pre-hydrolyzed cellulose-containing pulp. Direct hydrolysis is carried out at 165-170 ° C; either water or an aqueous acid solution is used as the hydrolysacadeg reagent. After the preliminary hydrolysis, the whole free-flowing pre-hydrolyzate is removed from the injecting boiler from sulphate cooking liquor 1. However, the honest method is not sufficient, high quality indicators of the target product and the efficiency of incomplete selection of the prehydrolyzate increase the consumption of cooking agent for sulphate cooking and reduce the efficiency eat yeast. The purpose of the invention is to improve the quality indicators of the target product and process efficiency. The goal is achieved in that according to the method of producing cellulose for chemical processing, including preliminary hydrolysis of cellulose-containing raw material at 165172 ° C, selection of prehydrolyzate and sulphate cooking at elevated temperature and pressure, before sulphate cooking, prehydrolyzed cellulose-containing raw material is treated with water at 80-150 0 The water ratio is 1.5: 1 - 3.5: 1. The method is carried out as follows. The initial cellulose-containing raw material is hydrolyzed with hydrolyzedum reagent at 1651720s. After the preliminary hydrolysis of the cellulose-containing raw material is carried out, the prehydrolyzate is sampled and hot water at a temperature of 40-80 ° C is pumped into the cooking vessel (Shy reactor, and then the pre-hydrolyzed cellulose-containing raw material is treated by water for 5-30 min and hydronic unit 1, 5 - 3 ,.

Then a liquid is taken after this treatment, which is used either for the preliminary hydrolysis in full or partial volume, or sent to a yeast shop for processing.

The treatment can be carried out both in intermittent and continuous boilers.

The processed prehydrolyzed cellulose-containing raw material is subjected to sulphate cooking.

Compared with the known method, the treatment of pre-hydrated cellulose-containing raw material with water in the proposed method increases the volume of yeast due to the additional removal of the pre-hydrolyzate with washing liquid (by 25-20%), increasing the content of reducing substances (PB) and reducing the consumption of alkali for cooking (approximately Hci 10 % of total consumption).

Example 1. Pine wood is used for cooking. The conditions of preliminary water hydroly are as follows: hydronic module 4: 1 ;. a rise of 70-170 120 min; stand at 170 ° - 70 min. After the completion of the pre-hydrolysis, the hydrolysis is removed and the pre-hydrolyzed cellulose-containing raw material is treated with water before sulphate cooking. Then the liquid is removed and pouring liquor with a 30% sulfin content is poured. Hydraulic module 4: 1. Consumption of active alkali 18% in units NajO by weight of absolutely dry wood. Impregnation at 135 ° - 30 minutes, rise 135170 ° - 60 minutes, 100 min. The data presented in the table, with experience 1 - a known method; Experiment 2 - treatment with water at a water ratio of 1.5: 1 for 15 minutes at 80 ° C; Test 3 — Treatment with water for 20 minutes at 80 ° C. Experience 4 Treatment with water for 30 minutes.

The data presented in Table. 1 show that carrying out the process according to the proposed method allows improving the quality indicators of pulp.

In the same series of experiments, an additional removal of redundant substances pB from the boiler, which is provided by the proposed method, is determined; it is 28%.

Example 2. The conditions of pre-water hydrolysis and sulphate cooking are the same as in Example 1. The difference lies in the consumption of alkali for cooking. In the proposed method, the alkali consumption is 17%, instead of 19 in the known method. The mode of treatment with water lasting 10 minutes at 120 ° C, gi.Cromodule 2: 1.

The results obtained on the effect of water treatment on alkali consumption during cooking are presented in Table. 2

The data presented in table. 2 show that the treatment of the cellulose-containing raw material with water makes it possible to reduce the consumption of alkali for cooking by 2% by weight of absolutely dry wood.

Example 3. Preliminary water hydrolysis and cooking are carried out according to the following mode: the hydraulic module is 4: 1, the rise of 70-172 ° is 120 minutes; stand at 170 ° - 80 min.

This is followed by the descent of the prehydrolyzate and the treatment of the prehydrolyzed raw material with water at a hydraulic ratio of 3.5: 1.

Processing temperature 110 and for 30 and 20 minutes, respectively

After the treatment, the liquid is removed and the cooking liquor with a 30% sulfur content is pumped into the boiler. Sulfate cooking: hydronic 4: 1. Consumption of active alkali 16.5% in units NagO by weight of absolutely dry wood. Impregnation at 130 ° - 30 min. Rise 130-170 ° 60 min. Stopping at 170 ° - 90 min. The results of the experiment are presented in table. 3

Example 4. Conditions for pre-hydrolysis and sulphate cooking are the same as in example 3.

The mode of processing the pre-hydrolyzed raw material with water: a hydromodule of 2.5: 1, a temperature of 140 and 150 ° С with a duration of 10 and 5 minutes, respectively.

The results are presented in Table. four.

Example 5. A series of experiments was carried out using an aqueous solution of SO for preliminary hydrolysis. Consumption S0.2 0.05, 0.1 and 8 wt.% Absolutely dry wood. The temperature of the preliminary hydrolysis, the rise time of 70-165 ° - 105 min, stand at 165 -45 min, GM 1: 4.

The pre-hydrolyzed feedstock is treated with water for 10, 20 and 30 minutes at 1OO ° C. Alkali consumption for cooking is 22% in units. NajO by weight of absolutely dry wood. The remaining conditions of cooking are similar as in Example 1. The results are presented in Table. five.

The data table. 5 indicate that the proposed method is also effective when carrying out preliminary hydrolysis with an aqueous solution of SOg.

Example 6. In experimental semi-industrial conditions, the production of cord pulp is carried out according to the proposed method. The raw material used is wood chips from the production noToka of the cord plant, which has the following average fractional composition,%:

Normal fraction 77.3 Large fraction 5.99 Fine fraction 14.1 Sawdust2,6

Average data on the mode and quality of unbleached pulp obtained are presented in Table. 6

The data in Table 6 shows that according to the proposed method, high quality unbleached cord is obtained, the removal of reducing substances is increased by 2B%, and the alkali consumption for cooking is reduced.

Therefore, the proposed method allows to improve the quality indicators of cellulose and the efficiency of the process.

Table 1

Viscosity 1% copper ammonium cellulose solution, mPa-s

Mass fraction of ash cellulose,%

The stiffness of the pulp, p.

The viscosity of 1% copper-ammonia solution of cellulose, mPasMass fraction of alpha-cellulose,%

45.8 44.0 43.0 95.6 95.3 95.2

table 2

86

28.3 95.0

.Table

eleven

996578 T a b faces b

Claims (1)

Claim A method of producing cellulose for chemical processing, including preliminary hydrolysis of cellulose-containing raw materials at 165-172 ° C, selection of a prehydrolyzate and sulphate cooking at elevated temperature and pressure, characterized in that * in order to improve the quality of venous parameters of the target product and process efficiency, before sulphate by cooking, processing is carried out; of a pre-hydrolyzed cellulose-containing raw material at 80-150 ° C and a water module of 1.5: 1-3.5: 1.