Alkaline process and system for producing pulp

A technology of pulp and cooking method, which is applied in the system field of implementing the method, can solve the problems of impossible high HS concentration, cannot use cellulose for AQ, and does not show convenience, etc., and achieves improved evaporation equipment and improved pulp. Yield and demand reduction effect

Inactive Publication Date: 2007-11-07
METSO PAPER INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In addition, yields can also be improved by polysulfide treatment, which has not shown ease of implementation in industrial processes
In addition, the use of anthraquinones will be accompanied by the following problems: the use of AQ will involve additional costs, on the other hand, due to its toxicity, AQ cannot be used in all cellulose production
This method enables a certain increase in the H2S concentration in the impregnation section and at the beginning of the cooking stage, however, since most of the alkali is consumed in the impregnation section, it is preferable to use it without adding a considerable amount of alkali to the cooking section. The black liquor in the self-digesting section is unlikely to have a high concentration of HS
This in turn will significantly reduce the yield

Method used

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  • Alkaline process and system for producing pulp
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  • Alkaline process and system for producing pulp

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0047] Pulp was cooked in the laboratory from eucalyptus chips under state-of-the-art conditions whereby the temperature in the first step of impregnation was 110°C (duration 45 minutes) and the temperature in the second step was 120°C (15 minutes) . The cooking temperature was maintained at 152° C. for 120 minutes to obtain a cellulose pulp with a kappa number of 17, which indicates the degree of delignification of the cellulose pulp. The cooking liquor used was conventional in terms of its HS and dry solids content. The H factor, which expresses the ratio of temperature to cooking time, is about 460. The pulp yield obtained from the chips was 53.7% based on the amount of chips used.

Embodiment 2

[0049] Using the same material, by circulating and concentrating the steeping liquid in multiple cookings, the following conditions corresponding to the present invention are established: the duration of the steeping is as in Example 1, the steeping temperature is 130° C., and the same as the cooking conditions in Example 1 In comparison, the dissolved dry solid components and HS concentrations were about twice as high. Cooking at a temperature of 149° C. for 100 minutes resulted in almost the same degree of delignification (Kappa number 18), which corresponds to an H factor of 230, which is half that of Example 1. The yield of cellulose pulp was 54.5% based on the amount of wood chips used.

Brief description of the drawings

[0050] Figure 1 schematically shows a preferred embodiment of the invention.

[0051] Figure 2 shows a preferred embodiment of the invention with a separate impregnation vessel.

[0052] Figure 3 shows a preferred embodiment of the invention wherein ...

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PUM

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Abstract

A process and an apparatus for producing pulp from lignocellulosic material by an alkaline cooking process, in which process preheated chips are treated in an impregnation stage with impregnation liquor, which is taken from the impregnation stage, and concentrated to obtain both a high inorganic and organic dry solid content. The temperature is higher than in the heating of the chips and in the removal of air, and sufficient to enable the finishing of the reactions in the impregnation stage before the cooking stage. The majority of the alkali is added to the impregnation stage. In the cooking stage alkali is added to enable the delignification to be performed to a desired degree, and at the end of the cook black liquor is added to regulate the liquid-to-wood ratio. The process can be applied both to a continuous cook and to a batch cook.

Description

[0001] Technical Field of the Invention [0002] The invention relates to an alkaline process for the preparation of pulp according to the preamble of claim 1 and to a system for carrying out said process. Background of the invention [0003] The purpose of chemical pulping is to remove lignin so that the fibers can be separated with less mechanical effort. Among the chemical pulping processes, the alkaline cooking process, especially kraft pulp or kraft cooking process, is the most important in the production of chemical cellulose pulp as it provides stronger paper fibers than pulp obtained by other commercial pulping processes. dominant in. Lignocellulosic material, usually chipped, is processed with the aid of a cooking liquor in batch or continuous digesters. [0004] The active components in the aqueous solution of kraft cooking liquor are hydroxide (OH) and hydrogen sulfide ion (HS). Delignification occurs mainly through the action of OH ions, but the HS content also ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C1/06D21C1/00D21C3/24D21CD21C1/02D21C3/02D21C3/22
CPCD21C1/06D21C1/02D21C3/022D21C3/222D21C3/24
Inventor 拉斯·赫尼斯尼米安蒂·图米尼恩图莫·尼凯尼恩拉米·兰皮尼恩
Owner METSO PAPER INC
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