SU1507890A1 - Method of producing pulp - Google Patents

Abstract

The invention relates to the pulp and paper industry, in particular, to methods for producing pulp, and allows an increase in the content of α-cellulose and the yield of the target product. Alkaline cooking is carried out with a two-stage supply of cooking reagent, in the first stage, 30-40% of the total amount is fed, and the rest of the cooking reagent is fed to the cooking when the temperature reaches 145-155 ° C. After cooking, cold and hot pulping is carried out.

Description

The invention relates to the pulp and paper industry, in particular to methods for producing cellulose.

The purpose of the invention is to increase the content of a-cellulose and the yield of the target product.

The proposed method for producing cellulose from hardwood is as follows.

Example I. Alkaline pulping of hardwood (a mixture consisting of 50% birch, 50% aspen) is carried out in a 5 l laboratory autoclave with adjustable electrical heating and a forced circulation system. Cooking mode: temperature rise from 80 ° С to 135 ° С for 110 minutes, impregnation at 135 С for 40 minutes, temperature rise up to 170 ° С for 60 minutes, stand at 170 ° С for 120 minutes. Hydraulic module 1: 4. The total consumption of active shell 19% (in units. Na2O). 30-60% of the total amount of silk is poured into the autoclave after loading the sheeps, and the remaining amount of 70-40% is injected into the CT; I-raising the temperature at 145-1554 with preliminary selection of the equivalent volume of black liquor to preserve the hydromodule. Due to the fact that optima. The narrow interval of the introduction temperature of the cooking agent at the second stage of cooking is small and the possibility of carrying out the process with its boundary values is obvious, the choice of process parameters should be carried out at 150 ° (2. After cooking, the pulp is washed, sorted on sieves and its quality indicators and yield are determined. After cooking, cold and hot pulping is carried out.

Cold refining mode: alkali concentration 40 g / l (units). temperature 20 ° C, time 60 min, mass concentration 8%.

The mode of hot beating: the concentration of shelkio is 2 g / l (unit of NaOH), the temperature is 90 ° C, the time is 120 min, the mass concentration is 8%.

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For comparison, cooking is carried out without redistributing the alkali.

The results of the experiments are presented in table. one.

From tab. 1 it follows that the redistribution of alkali during alkaline cooking makes it possible to increase the content of a-cellulose by 0.8-1.8%, and the yield of cellulose by 1.0-1.7% compared with the known method. The optimal ratio of alkali, re-results are presented in table.- 2.

The results show that the redistribution of alkali at 135 ° C does not allow an increase in the content of a-cellulose in hardwood pulp for chemical processing as compared with the known method. At 170 ° C, along with an increase in the content of a-cellulose, its hardness increases.

So the best effect is

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limited during cooking, is pre-lignification, cellulose-40-40 refining: 60-70% of the total consumption. Threat and increase its output is achieved. Using less than 30% of the total time of introduction of alkali in the second stage of the amount of alkali in the first stage of cooking at 150 ° C. At the same time, the content of a-cellulose is inexpedient due to its complete half in comparison with the known method of consumption and sedimentation of those liberated in plants increases by 1.8% while simultaneously thieving hemicelluloses and lignin. With a distribution increase in yield by 1.8%. dividing the alkali by cooking 60:40 increases the rigidity of the cellulose and reduces the content of a-cellulose.

Thus, the optimum ratio of alkali, redistributed at different stages of alkaline cooking, when producing cellulose for chemical processing, is in the range of 30-40: 60-70% of the total consumption).

Example 2. Alkaline pulping of hardwood was carried out under conditions similar to those indicated in example 1, with a total consumption of alkali of 19% (unit Na2O) and redistribution of 40:60. The alkali introduction temperature is changed in the second cooking stage.

Claims (1)

Invention Formula The method of producing pulp from sheet wood by alkaline cooking in the presence of cooking reagent, cold and hot refining, characterized in that, in order to increase the content of a-cellulose and the yield of the target iro-dukta, - by supplying the cooking reagent at the first stage, 30-40% of the total amount is supplied at the first stage, and the remaining part of the cooking reagent is fed to the cooking when reaching 145-155 ° C. The results are presented in table .- 2. The results show that the redistribution of alkali at 135 ° C does not allow an increase in the content of a-cellulose in hardwood pulp for chemical processing as compared with the known method. At 170 ° C, along with an increase in the content of a-cellulose, its hardness increases. So the best effect is ..1.HG.1T1, vfL /, liCirl, / U -Hiajrirl C-H A .. w, J T lignification, cellulose trimming and increase in its yield are achieved during the introduction of alkali in the second stage at 150 ° C. At the same time, the content of α-cellulose increases by 1.8% compared with the known method, while simultaneously increasing the yield by 1.8%. lignification, cellulose trimming and increase in its yield are achieved during the introduction of alkali in the second stage at 150 ° C. At the same time, the content of a-cellulose, as compared with the known method, increases by 1.8% while increasing the yield by 1.8%. Invention Formula The method of producing pulp from leaf wood by alkaline cooking in the presence of cooking reagent, cold and hot refining, characterized in that, in order to increase the content of a-cellulose and the yield of the target product from the duct, the alkaline cooking is carried out by feeding the cooking reagent, in the first stage, 30-40% of the total amount is fed, and the remaining part of the cooking reagent is fed to the cooking when it reaches 145-155 ° C. Table 1 78, 5 89.3 48.9 49.9 362 430 90.2 91.0 and , -ABOUT 13.02 16.7 94, 4 95.0 348 465 7, 7, 5 312,427. 93.7 95.0 90.6 50.5 584 90.4 96.7 55.9 583 91.2 1.55 3.72 13.64 13.64 7.75 8.06 95.6 583 95.2 694 52.3 615 94.7 Overall yield,% 50.2 Noprovoc content,% Delignification degree, p. E, 80, 6 Viscosity, mPz 469 Content, -cellulose,% 90.2 Table 2 50.3 1.4 96.1 643 91.2