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A method of replacing sodium losses in a pulp mill, a method of producing bleached cellulosic pulp, and a system

A technology for pulping and white liquor, which is applied in the post-processing of cellulose pulp, the regeneration of pulping liquid, and pulp bleaching, etc., which can solve the problems of difficulty in reducing and controlling

Pending Publication Date: 2021-10-01
芬宝公司 +1
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Removal of chemicals containing S, K, and Cl from chemical cycles often results in simultaneous Na loss and has proven to be more difficult to reduce and control

Method used

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  • A method of replacing sodium losses in a pulp mill, a method of producing bleached cellulosic pulp, and a system

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Embodiment Construction

[0039] definition

[0040] In this context, the term "white liquor" refers to the 2 S as an alkaline cooking medium for the main delignification chemicals.

[0041] As used herein, the term "black liquor" includes spent white liquor containing dissolved organic dry solids, water and dissolved inorganic dry solids.

[0042] In this context, the term "non-process elements" NPE includes elements not essential to the kraft pulping process (eg Fe, Mn, Al, P, K, Cl). Potassium (K) and chlorine (Cl) are also generally considered NPEs, although they can participate in the process.

[0043] In this context, the term "D0 stage" refers to the first ClO 2 The bleaching step, "D1 stage" refers to the second ClO2 bleaching step.

[0044]In this context, the term "EO stage" refers to a bleaching step (alkaline extraction) in which oxygen and NaOH are used but no peroxide is used.

[0045] In this context, the term "EOP stage" refers to a bleaching step (alkali extraction) in which oxyge...

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Abstract

According to an example aspect of the present invention, there is provided a method of replacing with sodium make-up chemicals sodium losses caused by outflows in a pulp mill which employs a kraft process for producing cellulosic pulp, wherein the pulp mill includes a unit for conversion of sulfurous compounds, which is fed with sulfurous substances of the kraft process to convert said sulfurous substances into oxidized sulfurous compounds, said method comprising using sodium sulfate possibly together with other sodium salts as the main make-up chemical, to achieve an essentially sodium hydroxide free feed of sodium make-up chemicals, and at least a part of the sulfur contained in the sodium sulfate make-up chemical being used for producing oxidized sulfurous compounds in said unit for conversion of sulfurous compounds.

Description

technical field [0001] The present invention relates to controlling the sodium / sulfur balance in a pulp mill. In particular, the present invention relates to the treatment of sodium losses in pulp mills producing kraft pulp. Background technique [0002] Pulp mill and pulping steps [0003] Pulp mills produce pulp from wood chips. The resulting pulp can be subsequently used in paper or board manufacture. [0004] A typical pulp mill is a combination of many different units and operations for the actual production of pulp as well as for the production of valuable side streams. [0005] The first step of the pulping process is the cooking of wood chips in a digester at high temperature in an alkaline environment (main delignification step). The cooking liquid is mainly composed of NaOH and Na 2 S composition. During this delignification step, the fibers are released and lignin is extracted. The white liquor turns into black liquor, which is dark brown. [0006] The nex...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C11/00D21C9/10
CPCD21C11/0035D21C11/0064D21C9/10Y02P40/40D21C11/00D21C11/0014D21C9/142D21C11/0057D21C11/0078
Inventor 阿里·波卡维利-佩卡·特沃拉
Owner 芬宝公司