SU1583505A1 - Method of producing fibrous semiproduct - Google Patents

Abstract

The invention relates to the pulp and paper industry, in particular to methods for producing a fibrous semi-finished product, and allows for an increase in the yield and quality indicators of the semi-finished product and process intensification. After loading the digester, the lid of the boiler is closed with chips and an alkaline mixture in the amount of 0.1-2.0% is fed to the absolutely dry wood through the steam compactor, while heating steam is supplied to the lower part of the digester at a rate of at least 5 tons / h. This treatment is carried out for 10-30 minutes after which the overflow liquor is pumped into the upper fittings of the digester (the cooked sulfite cooked liquor after the brewing process up to 105-110 ° C) of another digester and the impregnation is completed by pumping the cooking acid following the supply of the overflow liquor. 3 tab., 3 Il.

Description

The invention relates to the pulp and paper industry, in particular to methods for producing a fibrous semi-finished product,

The purpose of the invention is to increase the yield and quality indicators of the semifinished product and intensify the process.

The method is carried out as follows.

After loading the digester, the lid of the boiler is closed with chips and an alkaline mixture, for example KOH + NaOH or # 2CO3 + NaOH, or ammonia water + NaOH, is fed into the boiler in an amount of 0.1-2.0% to absolutely dry (a. C.) wood, simultaneously in the lower part of the digester serves heating steam with a flow rate of at least 5 tons / h. This treatment is carried out for 10-30 minutes, after which the overflow liquor is pumped into the upper fittings of the digester (sulfate digestion cooking liquor after the welding process to 105-110 ° C) from the other digester and the impregnation is completed by pumping the cooking acid after feeding bypass liquor. The flow of steam through the lower part of the digester during the injection of bypass liquor and cooking acid is not stopped. Then, cooking is carried out according to the known technological mode by welding chips up to 105 ° C, standing at 105 ° C, raising the cooking temperature to 130-135 ° C, standing at the final temperature, conducting the final gas blow,

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displacing liquor and washing or blowing welded pulp from the cooking furnace; the ammoniacal mixture is 0.1-2% by weight of a.s. wood, for the liquor liquor 10-30% of the volume of injected acid for cooking,

Table 1 presents the results of industrial experiments on the mode of sulphite cooking and two-stage cooking by a known method, as well as the results of industrial cooking using the proposed method.

From Table 1, it follows that the yield of the proposed pulp is slightly higher and amounts to 56%. The results of poor penetration of wood are much better than by a known method, the dirtiness is slightly higher, the whiteness is at the level, the mechanical indicators for breaking length and for the number of double kinks are also at the level of the known method and somewhat higher.

In tab. 2 shows the mode of cooking by the known and proposed methods.

As follows from Table 2, the turnover of the digester according to the proposed method is 8 hours and 15 minutes, while by a known method it is 10 hours, i.e. there is an intensification of the cooking process as a result of the effective impregnation of the chips with the bypass liquor and cooking acid, as well as the pretreatment of the chips with an ammonia-alkaline mixture. The method was tested in laboratory and factory conditions on digester boilers with a volume of 320 m3 of the KVCi - 320 grade in the production of sulphite pulp on a mixed ammonium-calcium base.

In tab. 3 shows the main indicators of pulp after cooking.

PRI me R 1. After the digester is loaded, the ammonia-alkaline mixture is poured into the boiler at a 1: 1 ratio of ammonia-water and alkaline NaOH solution into the boiler after the gasket is pressed into the boiler. The concentration of ammonia water in ammonia is 24%, the concentration of alkaline solution in NaOH is 2%. After the bay ammonium-alkaline solution in an amount of 0.1% by weight of a.s. wood, the boiler lid is closed and steam is supplied to the lower part of the digester at a rate of not more than 5 tons / h after 10 minutes, 50 m of bypass liquor is pumped into the upper part of the digester, i.e. waste va-. liquid solution taken from another digester. After pumping the bypass lye, the cooking acid in the amount of 150-180 m3 is pumped into the upper part of the digester with a volume of 320 m: Steam during the injection of the bypass lye and acids continue to be supplied at a rate of 5 tons / h. By

at the end of the injection of the cooking sulphite kispota with the strength of 5–9% no SOa with the content of calcium or ethylene base 1.0–1.3%, the flow rate is added to the boiler

i cutting steam and brewing up to I05-110 ° C for 60 minutes, then standing at 110 ° C for 90 minutes, raising the temperature in the boiler to 140-144 ° C for 100 minutes, standing at 140 ° C for 30 min, blow off

0 gas for 85 minutes, blowing or washing the mass out of the boiler for 25 minutes. All listed operations for cooking mode are presented in Table. 2 and are unchanged in the following examples.

5 After cooking, the main indicators of cellulose; pulp yield from wood 54%, hardness 80.0 p.u., lack of penetration 3.5%, impurity 9000 sor / m2, whiteness, 58% white, bursting length 7280 m, kink

0 1600 bp, the amount of PB in the liquor is 2.9%, the turnover of the digester is 8 hours and 15 minutes.

EXAMPLE 2. After the digester is loaded, the ammonia-alkaline mixture is poured into a boiler with a three: 1 ratio of ammonia-water and an alkaline solution of 1: 1. The concentration of ammonia water mixed with alkali ammonia, 23%, the concentration of alkaline

0 solution of 20% NaOH,

After the bay ammonium-alkaline solution in an amount of 0.1% by weight of a.s. wood, the lid of the digester is closed and in the lower part of the digester serves

5 pairs at a rate of 5 t / h, after 10 minutes, 50 m of bypass liquor is pumped into the upper part of the digester, then cooking acid is fed. Steam to the lower part of the boiler continues to be supplied at a rate of 5 t / h and

0 The impregnation of the chips is carried out during the injection of the bypass liquor and cooking acid, as if in a fluidized bed.

At the end of the injection of cooking sulfite acid with a strength of 5-9% SOA and

5 with a calcium, ammonium or sodium base content of 1.0-1.3%, heating steam consumption is added to the boiler and cooking is carried out according to the procedure specified in example 1. After cooking, the main indicators of cellulose are determined: 56% wood pulp yield, rigidity 85 p.u., lack of penetration of 2.2%, impurity 9200 sor / m2, whiteness 59% white, bursting length 7300 m, kink 1700 bhp, amount of PB 2.7%, turnover of boiling boiler 8 h 15 min.

PRI me R 3. After loading the boiler, ammonium-alkaline mixture is poured into the boiler at a ratio of ammonia-water and alkaline solution of NaOH 2: 1. Ammonia Water Concentration Ammonia

24%, alkaline solution of 2% NaOH, consumption of ammonium-alkaline solution 0.1% by weight a, c. wood After closing the lid, steam is supplied to the lower part of the digester at a rate of 5 t / h, after 10 minutes from the start of steam supply, 50 m3 of overflow liquor and cooking sulphite acid are fed to the upper part of the boiler. Next are cooking in the usual way. After cooking, the main indicators of cellulose were determined: cellulose yield 56%, hardness 86 pu, lack of penetration 3.8%, dirt 9800 litter / m2, white whiteness 50%, bursting length 7000 m, kink 1300 ppm , the amount of PB in the liquor is 2.4%, the turnover of the digester is 8 h 15 min.

Example 4 The method is carried out as in Example 1, but a solution of soda in a volume ratio of Na2COa: NH40H both 1: 1 and 0.1: 1 and 1: 0.1 is used in a mixture with ammonia water, those. in various volume ratios. Alkaline mixture consumption by weight a.s. wood is 0.1-2%. After pouring these solutions into the lower part of the digester, steam is supplied at a rate of 5 t / h and after 10 minutes from the beginning of the steam supply, bypass liquor is fed into the upper part of the digester from another digester in an amount of 50 m, and then the digester is pumped acid to the top of the boiler. Next are cooking in a known mode. After cooking, the main indicators of cellulose are determined.

From example 4, it was found that the use of a mixture of two alkaline solutions in a different volume ratio practically does not affect the main indicators of cellulose, which, after determining, on average, make: cellulose yield 55%, hardness 75 p.e., incomplete 2.5%, impurity 8900 sor. / m2, whiteness 62.0% white, bursting length 7500 m, kink 2100 ppm, the amount of PB in the liquor 2.7%, the turn of the digester 8 h 15 min.

PRI me R 5. After the boiler is loaded, the alkaline mixture consisting of ammonia water and sodium alkali is poured in chips in a volume ratio of 1: 0.1. Alkaline mixture consumption by weight a.s. wood take 2%. Concentration of ammonia water for ammonia 23%, alkaline solution of 2% NaOH. After filling the alkaline mixture, steam is supplied at a rate of 5 t / h, after 10 minutes from the start of steam supply, bypass liquor from another digester is supplied to the upper part of the digester in an amount 50 m, and then pumped cooking acid. Next are cooking in a known mode. After cooking, the main indicators of cellulose are determined: pulp yield

57%, rigidity 90 p.e., lack of penetration 2.5%, weed 8000 sor / m2, whiteness 60% white, breaking length 7500 m, break 1800 rf, amount of PB in liquor 2.5% , turn of the digester 8 h 15 min.

PRI me R 6. After the digester is loaded, the ammonia-alkaline mixture is poured into the boiler at a ratio of ammonia-water and alkaline NaOH solution 1: 1 through a steam sealer. The concentration of ammonia water in ammonia is 23%, alkaline solution of 2% NaOH. The consumption of ammonium-alkaline solution of 2.5% by weight of a.c, wood. All other operations are performed.

5 as in examples 1-5. After cooking, the main indicators of cellulose were determined: cellulose yield 54.8%, hardness 95 p.u., lack of penetration 4.0%, resistance to 9800 litter / m2, whiteness 57%, breaking length of 8000 m, kink

0 2100 bp, the amount of PB in liquor is 2.7%, the turnover of the digester is 10 hours and 15 minutes.

The increase in the consumption of ammonium-alkaline solution over 2% leads to a significant increase in the turnover of the cooking

5 boiler and reduce its performance,

those. ammonium-alkali mixture consumption in 2%

to AS wood is the highest limit.

PRI me R 7. After loading the cooking

In the boiler, ammonium-alkaline mixture is poured into the boiler through the steam compactor at a ratio of ammonia-water and alkaline 1: 1 NaOH solution. Concentration of ammonia water 24%, alkaline solution 20% NaOH. The consumption of ammonium-alkaline solution5 raO, 07% by weight of a.s. wood All other operations in this example are performed similarly to examples 1-5. After cooking, the main indicators of cellulose were determined: cellulose yield 51.6%, stiffness 100 pu, incomplete penetration 10%, impurity 9900 sor / m2, white whiteness 50%, bursting length 6500 m, kink 1300 ppm ., the amount of PB in liquor is 2.85%, the turnover of the digester is 8 h 15 min. Reducing the consumption of ammonia-alkaline mixture on vyrku below 0.1% by weight of a.s. wood leads to a deterioration in the quality and mechanical parameters of cellulose, as well as to a decrease in the yield of cellulose from wood, which determines

0 the lower level of consumption of ammonia-alkaline mixture for cooking. Reducing the consumption of ammonium-alkaline mixture below 0.1% does not allow to achieve the objective of the invention in terms of pulp yield and in terms of quality and mechanical pulp indicators.

PRI me R 8. After the digester is loaded, the ammonia-alkaline mixture is poured into the boiler at a 1: 1 ratio of ammonia-water and alkaline NaOH into the boiler after the digester is loaded. The concentration of ammonia water is 24%, alkaline solution of 10% NaOH. The consumption of ammonium-alkaline mixture of 1.5% by weight.with. After closing the lid of the digester, steam is supplied to the lower part of the boiler at a rate of 5 t / h, after 10 minutes from the start of steam supply, its supply to the boiler is stopped and boiling acid and the bypass liquor are pumped into the lower part of the digester and then cook normal mode. After cooking, the main indicators of cellulose and the duration of cooking were determined: the yield of cellulose was 52.0%, the rigidity was 90 p.u. 1400 bp, the amount of PB in the liquor is 3.0%, the turnover of the digester is 10 hours and 20 minutes. The increase in boiler turnover by 2 hours and 5 minutes compared to Example 1 was due to an increase in the brewing time, i.e. raising the temperature in the boiler to 105-110 ° С for 1 h 5 min and increasing the stopping time at the final temperature up to 1 h. Increasing the stand for 1 h at the final temperature is caused by incomplete heating of the pulp, i.e. high hardness of cellulose.

Thus, the exclusion of the operation of supplying the bypass lye and cooking acid through the upper part of the boiler and feeding them to the lower part of the boiler leads to a decrease in the yield of pulp from the wood and to an increase in the cooking time.

PRI me R 9. After the digester is loaded, the ammonia-alkaline mixture is poured into the boiler at a ratio of ammonia-water and an alkaline solution of 0.1: 1. The concentration of ammonia water is 24%, alkaline solution of 10% NaOH. The consumption of ammonium-alkaline mixture of 0.8% by weight.with. wood After the alkaline mixture is poured, steam is supplied to the lower part of the boiler at a rate of 5 t / h, after 10 minutes from the start of steam supply its supply to the boiler is stopped and 50 m bypass liquor is pumped into the upper part of the digester, then boiling acid is pumped into the lower part of the boiler with a base content of 1.0-1.3% and a strength of 5-9% for SU2. Again, steam is given to the boiler and cooking is carried out further according to the usual mode described in example 1. After cooking, the main indicators of cellulose and the duration of cooking are determined: the yield of cellulose from wood is 57%, nonproductor 8.5%, kink 1500 ppm, whiteness, 52% white, hardness 110 pu, litter, 11,200 litter / m2, bursting length 7500 m, RV content in liquor 2.3%, turnover of the digester 8 h 15 min. This example shows that the elimination of the supply of cooking acid in the upper zone

before cooking, the boiler deteriorates the quality indicators of pulp due to incomplete heating and generally reduces the yield of good pulp, pulp is obtained with increased hardness of 110 bp, which leads to waste of chemicals on subsequent bleaching stages during further processing of pulp.

An example. After the digester is loaded, the ammonium-alkaline mixture is poured into the boiler at a volume ratio of ammonia water and an alkaline solution of 0.05: 1 and 1: 0.05. The concentration of ammonia water is 24%, alkaline solution of 10% NaOH. The consumption of ammonium-alkaline mixture of 2% by weight of a.c, wood. After the bay of alkaline mixture, steam is supplied to the lower part of the cooking cup with a consumption of 5 t / h,

10 minutes after the start of steam supply, 50 m of bypass liquor and 150-180 m of sulphite cooking acid are pumped into the upper part of the digester, then steam is added to heat the contents of the digester and cook by steps similar to Example 1. After boiling, the main indicators are determined cellulose: pulp yield from wood 56.0%, lack of penetration 4.5%, kink 1600 and 1200 bp,

whiteness is 61 and 52% white, hardness of 105 and 120 p.u., dirtiness of 20,000 and 12,000 sor / m 2, breaking length of 7,200 and 6,300 m, RV content in liquor 2.5%, turnover of the digester 8 h 15 min. Cooking according to example 10 shows that going beyond the volume ratio of a mixture of two alkaline solutions of 0.1: 1 and 1: 0.1 leads to a deterioration in the quality indicators of cellulose: the whiteness decreases to 52% white, the mechanical indicators of cellulose fall, the fracture It is 1200 ppb, which is lower than unbleached pulp, there is an increase in the weediness of the pulp, an increase in the lack of penetration and stiffness of the pulp.

Claims (1)

The invention The method of obtaining the fibrous semi-finished product by steaming wood 0 chips, impregnating it with chemicals, heating impregnated chips and subsequent sulphite cooking, characterized in that, in order to increase the yield and quality indicators of the semi-finished product and intensify the process, the impregnation of chips is first carried out with a mixture of two alkaline solutions in a volume ratio of 0.1. .1.0: 1.0 ... 0.1 and in the amount of 0.1-2.0% by weight of wood, then bypass liquor and cooking acid, with all the permeate chemicals being fed to the upper part of the digester and simultaneously heating the chips with steam supplied to the bottom the boiler. Table 1 table 2