SU1617073A1 - Method of obtaining cellulose - Google Patents

Abstract

This invention relates to pulping technology and allows for an improvement in the quality of pulp while reducing the costs of heat and chemicals. Wood chips are treated (cooked) with cooking liquor, which is used as a permeate with a maximum mol.m. 30000-50000, obtained by membrane separation of treated sulphite liquor or post-yeast mash. 2 tab.

Description

This invention relates to a technology for the production of pulp fibrous semi-finished products and can be used in the pulp and paper industry in the manufacture of sulphite pulp.

The aim of the invention is to improve the quality of pulp while reducing the costs of heat and chemicals.

According to the proposed method, when processing (cooking) wood chips, permeate with a maximum mol.m. is used as a sulfite cooking solution on a soluble basis. 30000-50000, derived from membrane separation of spent sulphite liquor or post-yeast brew.

The method is carried out as follows.

The spent sulphite liquor or post-yeast brew from the usual

sulphite cooking of any degree of selection is sent to the membrane unit. | The fraction passing through the membranes (permeate) contains substances with a maximum mol. M. 30000-50000; another fraction — not passing through membranes (retant) —contains in its composition lignosulfonates with a mol.m. more than 50,000.

The first fraction (permeate), purified from cooking compounds that inhibit high-molecular compounds, is fully used to prepare the cooking solution by filling with soluble base up to 0.5-1.1 seconds; following saturation with sulfurous gas; In the absorber up to 6.0-8.2 total; SP2. After that, the resulting solution is fed to the digester for sulphite cooking. The second fraction of the liquor, containing the concentrated high molecular weight organic substances, is directed either to the dopariva (L

WITH

sz:

one

about

Garden

31

ing and burning, or to receive | valuable chemical products. I The invention is illustrated by the following examples.

j Example Processing (cooking) spruce wood trailers is carried out in a 1 liter autoclave. Size of the flail: length 2C-25 mm, thickness 2-3 mm Content, all that is in the cooking liquid for all variants is 1%, the content of the bound is 80–0.9. Liquid

iodule, 1: 5. Cooking temperature 135 C.

In a battery autoclave, boiling is carried out according to the prototype method and boiling: a solution based on a sulphite liquor permeate containing substances of mol.m. 30,000 or more, 50,000 or less, 60,000 or less (control experience). The above perioids are obtained by applying different membranes, the cut-off limits of molecular weight of the composition of the HLNF are 30,000, 50,000 and 60,000. Cooking

low costs of bleaching agents, to intensify the process at the expense of less cooking time, reduce sulfur consumption by 6.5 kg, and soda consumption by 23j03 kg per 1 ton of air-dry pulp, reduce steam consumption for evaporation by 0.75 tons / ton of pulp and reduce fresh water consumption to

2, k m

per ton of pulp.

Example 3: Conduct a series of brews using a batch boiler, operating and using ten times the used liquor after first passing it through the cleaning membranes. Cooking mode - for example 1.

The results of cooking are presented in table. 2

 follows from the table. 2, even ten times the use of spent sulphite liquor for cooking after preliminary separation on the membranes of high molecular weight lignosulfo

The solution is prepared on one hundred percent per-25 nats with a maximum mol.m. more

i-ieaTe without addition of fresh acid. I Experimental data are presented in tgabl. 1 (columns t-6).

As Example 1 shows, the use of permeate with higher molecular weight substances (m, m more than 50,000);} causes the cooking process, and when separating less high molecular weight substances (mol. M. Less than 30,000), the process of ultrafiltration decreases significantly. This is due to the smaller pore size of the membranes used in this case. I P m and e R 2. Cooking is carried out according to the procedure described in Example 1, Zo as a cooking solution using permeate from a yeast razhek, ultrafiltration of which is sold on an UPM-50000 membrane. Data Presented and Table. 1 (column 7).

As follows from the table. 1, the proposed method makes it possible to obtain a better quality, better lumen, namely, lighter, with a lower content of leproven and lignin, which requires more

thirty

35

40

45

50,000 does not impair the quality of the pulp obtained, while on the basis of the prototype it is noted that it is impractical to use the spent liquor more than four times due to the darkening of the pulp, slowing down of cooking and the growth of reducing substances in the liquors.

Claims (1)

Invention Formula A method of producing pulp by treating sulphite wood chips with a cooking solution on a soluble base, characterized in that, in order to improve the quality of cellulose while reducing the costs of heat and chemicals, permeate is used with sulphite cooking solution with max. 50,000 obtained by membrane separation from a worked sulphite liquor or a post-yeast mash. 0 five 0 five 50,000 does not impair the quality of the pulp produced, while the prototype method notes that it is not advisable to use spent liquor more than four times due to the darkening of the pulp, slowing down of cooking and growth of reducing substances in the liquors. Invention Formula The method for producing cellulose by treating wood chips with a sulphite cooking solution on a soluble base, characterized in that, in order to improve the quality of the pulp while reducing the costs of heat and chemicals, permeate with a maximum mol.m. as a result of membrane separation of spent sulphite liquor or post-yeast mash. Maximum clipped molecular weight Content of associated SOj, in cooking solution,% Content of total SOg in cooking solution, Cooking temperature, С Cooking time, h-min Liquid module Fresh soda consumption for cooking, kg / ton of pulp Sulfur consumption for cooking, kg / ton of pulp Steam consumption for residue, t / t pulp Yield pulp,% Leakage,% Content of lignin in cellulose,% Table 1 30,000 50QQG 60,000 50,000 0.9 7.0 135 5-15 1: 5 51.9 89.1 0.23 5.3 0.2 4.8 0.9 7.0 135 5-30 1: 5 51.9 89.1 55.6 1.1 5.9, 0.9 7.0 135 5-25 1: 5 61.2 78.6 5.9 0.8 6.0 Table 2