SU520430A1 - Pulp Production Method - Google Patents

Description

The invention relates to a technology for the production of pulp, widely used in the production of synthetic fibers and various types of paper. A known method for the production of cellulose by pre-steaming, impregnation of wood chips with a solution of caustic soda at an excess pressure of up to 6-15 MPa, followed by removal of the impregnating solution and boiling by the sulfite method at a temperature of up to 150 ° C. : The disadvantages of this method are the use of expensive caustic soda, the use of sulfuric acid solutions of very high concentration and rather large. cooking duration The resulting cellulose loea usually contains incomplete penetration. ; In order to reduce the cooking time, reduce the lack of penetration, improve the quality of the target product in terms of increasing its resistance to punching and tearing, soda solution is used as the impregnating solution and cooking is carried out at a temperature of 175 ° C. The method consists in the following: Cellulose-containing raw materials are steamed at a temperature of 1OO-105 C, impregnated with an excess pressure of 3-1 O atm with Na jCOj solution, the impregnating solution is removed and cooked with a sulphite cooking solution at temperatures of J 145-175 C. Sulfite acid may be used as a sulphite cooking liquor on any | base (or without a base), containing 3-lO% SOg, .. The process is carried out periodically or continuously in cooking boilers of the Kamur type or in L1Oi other continuous cooking plant pulp . The use of piacTBOpa Co., 2a for the preliminary impregnation of crushed race of the raw material due to its low alkalinity and buffer properties, creates more dangerous conditions for the condensation of lignin during the early stages of boiling than with application, and allows for impregnation and injection sulfite acid in a short period of time to raise the cooking temperature to the final one. The solution penetrates

to the deepest slieev vegetable raw materials:

w - - - I

The rate of penetration of 5ug into crushed vegetable raw materials is, as is known, rather high. Increasing the temperature of sulphite boiling to 160 ° C, even if the j jars in the digester are steamed and the vegetable material is impregnated with a solution

NCLaCOx I leads to a reduction in the turnover of the digester 1.5-2 times. Therefore, the production of cellulose can be increased in 1, S- |

2 times on the existing equipment without significant investment;

The cooking process, when used in impregnation with a solution of NueGOj, can be carried out continuously.

With a high ability to grind, the physicomechanical properties of cellulose after soda-sulphite pulping increase and are close to the properties of sulphate pulp, (see Table 1).

Table

A direct comparison of the physicomechanical properties of soda-sulphite pulps with alkaline-sulphite pulps is difficult .: 40 Alkaline sulphite pulps have low resistance to punching and tearing, which cannot be said about soda-sulphite pulps (see Table 1). | The yield of cel pitch1 after soda-sulphite- / 4v boiling is easily controlled. The increase in the amount of alcohol introduced during the process is constant, while the content of base is unchanged.

nova in sulphite acid, or, on the contrary, an increase in the base content in sulphite acid with a constant amount of Ntt, CO, introduced during impregnation, leads to a significant increase in consumption. For an example in the table. 2. The results of soda-sulphite cooking of spruce wood with humidity of 30% are shown (cooking was carried out; under the same conditions at a temperature of 160 ° C, the standing time was not 160 ° C for 1 hour and 15 minutes).

Claims (2)

Table 2 The cost of Na bases when using NttjCOj is 2.3 times less than in the case of using NttOH at the same equivalent costs. Example 1. In a 2.5-liter autoclave with electric heating load 300 g of air-dry chips spruce. For 15 minutes, the chips are treated with steam at a temperature of 100-105 ° C. Then, 165 O ml of a solution with a concentration of 2.5% is pumped into the autoclave and a pressure of 10.0 MPa is created with nitrogen, which is maintained for 15 minutes. Blow out to 5 MPa, take away the entire flowing NcXgCO5 solution, pour sulfite acid of O composition, 1% and 6.0% of the whole SOj into the autoclave. Pressurized with 10 O, 0 ATM and the autoclave is held in this state for 15 minutes. Then the temperature in the autoclave is raised to 16 ° C in 2 to 5 minutes (maximum pressure U at), and the autoclave is held at this temperature for 4O minutes. The resulting cellulose is easily divided into fibers that are light, do not contain incomplete fusion. Output 52.2% of the weight of absolutely dry wood, hardness 145 b. Example 2. In a 2.5-liter autoclave with electromotive evomous, ZOO g Tyuyuzdushno-dry chips ate. For 15 minutes, the chips are treated with steam at a temperature of 1OO-1O5 C. Then, 165 O ml of N0.2.03 solution is drawn into the autoclave. Continuation of the table. 2 centered 2.5% in units liIO, j, 0 and nitrogen create a pressure of 1O atom, which is maintained for 15 minutes. Blowing up to 5 MPa is carried out, the whole flowing N and CO solution is taken away, and sulfite acid with the composition of 0.1% 6 O% of the whole SO is poured into the autoclave. Nitrogen is pressurized with 10 ati, and auto clave is held in this state for 15 min. I Then, in 25 minutes, the temperature in the autoclave | is raised to 160 ° C (maximum pressure of 1O pressure), and the autoclave is released at the same time: at this temperature for; h40m The pulp obtained is light, does not contain incomplete penetration, has a yield of 45.4% by weight of absolutely dry wood, a hardness of 45 B; copper – ammonia; the pulp capacity of this cellulose is 6O1 MP (1% solution). Formula of the invention The method of obtaining cellulose by steaming, impregnating the raw cellulose-containing raw material with an alkaline solution at a pressure of up to Yu Ati, followed by removing the impregnating solution and boiling when heated with a sulphite cooking solution, so that By reducing the cooking time, reducing the lack of penetration and improving the quality of the target product, as an impregnating solution; use soda solution and cooking is carried out at a temperature of up to 175 C.