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Method and system for semi-chemical pulping

A technology of semi-chemical pulp and cooking vessel, which is applied in the field of semi-chemical pulp and system, and can solve the problems of uneconomical operation and side effects of pulp yield

Inactive Publication Date: 2009-03-18
ANDRITZ AG
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the higher pH at the start of cooking may have adverse effects on pulp yield and may make the operation uneconomical since white liquor is more expensive to produce than green liquor

Method used

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  • Method and system for semi-chemical pulping
  • Method and system for semi-chemical pulping

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Embodiment Construction

[0014] In one aspect, certain embodiments of the invention generally involve increasing the pH at the end of cooking. This keeps the extraction sieve clean for a longer period of time. The pH can be raised by adding white liquor or NaOH (or any other base) at the end of the cook through the loop and / or base pipe.

[0015] The pH of the cooking liquor (eg lignin-containing black liquor) at the end of cooking should be 10 or higher, preferably between 10-13, most preferably between 10-12.

[0016] According to some embodiments of the invention, the pH at or near the extraction screen may be increased compared to the pH of the liquid above the extraction screen. This in turn increases the solubility of lignin at or near the extraction screen.

[0017] In certain embodiments, the pH level of the liquid at or near the extraction screen in the vessel undergoing semi-chemical slurrying is increased. In certain embodiments, this increases the solubility of the lignin and also reduc...

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Abstract

Provided is a method and an apparatus for minimizing adherence of lignin to an extraction screen in a semi-chemical pulping process. The method and apparatus generally relate to supplying white liquor and NaOH to as to increase the pH of cooking liquor at or near an extraction screen.

Description

[0001] cross application [0001] This application claims priority to US Provisional Application 60 / 954,446, filed August 7, 2007, which is hereby incorporated by reference in its entirety. technical field [0002] In general, the present invention relates to methods and systems for producing semi-chemical pulp from lignocellulosic material. Background technique [0003] Semichemical pulping methods are known. See, eg, US Patent 4,229,251 to Temler; US Patent 4,073,678 to Hammond et al. with include Semichemical pulping processes have different requirements and different operating conditions than Cooking's pulping process, such as those disclosed in US Patent 5,489,363 to Marcoccia et al. [0004] In the manufacture of semi-chemical pulp (pulp with a yield in the range of 65-85%, typical for the production of corrugated media used in box making), several different chemicals can be used such as NaOH, NaOH, 2 CO 3 、Na 2 SO 3 , kraft paper white liquor or kraft paper gr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C7/00D21C3/02
CPCD21C3/00D21C7/00
Inventor C·贝蒂尔·斯特龙伯格
Owner ANDRITZ AG
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