Method for treating liquid flows at a chemical pulp mill

A pulping plant, liquid flow technology, applied in the regeneration of pulping liquid, washing/replacing pulp treatment liquid, pulping with inorganic alkali, etc.

Active Publication Date: 2010-03-31
ANDRITZ AG
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Therefore, the introduction of chloride compounds into the chemical cycle will not be a problem when combined with efficient chloride removal from the process at the recovery boiler, but the only criterion for the water circulating at the pulp mill will be the amount of organic compounds and their detrimental effects on the process

Method used

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  • Method for treating liquid flows at a chemical pulp mill
  • Method for treating liquid flows at a chemical pulp mill

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0155] Tests on eucalyptus pulp

[0156] The laboratory study used oxygen delignified eucalyptus pulp (kappa number 11.7, viscosity 1079 mL / g, ISO brightness 61.9%). The pulp was centrifuged to a consistency of 32%. The pulp was then diluted to bleach strength with clean water or treated water (effluent from chemical pulp mill after treatment in activated sludge plant) so that the chemical D0 concentration was 10%. The amount of effluent in the effluent dilution test is 5.7m 3 / adt pulp.

[0157] The EP stage was carried out in the atmospheric phase with a retention time of 75 minutes at a concentration of 10%. The D1 stage was carried out in polyethylene bags with a retention time of 75 minutes at a concentration of 10%.

[0158] The test results are presented in Table 1. Based on them, it was noted that the bleaching rate of the pulp was the same for both liquors.

[0159] Table 1

[0160]

D-EP-D

D-EP-D

dilution liquid

clean water

disch...

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PUM

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Abstract

The present invention relates to a method for treating liquid flows at a chemical pulp mill comprising at least an alkaline cooking process for producing pulp, brown stock treatment with essentially closed liquid cycles, a pulp bleaching plant using ECF-bleaching, a chemical recovery plant comprising a chemical recovery boiler, and effluent purification. Chloride-containing bleaching plant effluents are led to the effluent purification, where they are treated in order to decrease the organic matter content thereof. At least 20 % of the purified effluent is returned to a pulp mill process and purified effluent is used in a last washing stage included in brown stock treatment. In the brown stock treatment the liquid flow is passed counter-currently to evaporation, wherefrom it is led for treatment to a recovery boiler process, wherein a separation process for chlorides is arranged for controlling the chloride level of the liquor cycle.

Description

technical field [0001] The invention relates to a method for the treatment of liquid streams in a chemical pulp mill comprising at least an alkaline cooking process for the production of pulp, brown stock treatment with a substantially closed liquid cycle, bleached using ECF Pulp bleaching plants, chemical recovery plants including chemical recovery boilers, and sewage purification. Background technique [0002] During the past few years, the size of pulp mills has increased substantially, as today a pulp mill producing 1 million tons / a is the standard size, and it seems that the increase in pulp mill size will not stop. While pulp mills are increasing in size, pulp mills are being built in areas and environments with very strict environmental protection regulations. For example, the amount of water used in pulp mills is strictly limited. A small reduction in the amount of water used by the pulp mill per tonne of pulp due to an increase in the size of the pulp mill will in...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): D21C9/14D21C11/00
CPCD21C9/02D21C9/14D21C9/10D21C11/0021D21C3/02D21C9/12D21C11/0028D21C11/00
Inventor 雅纳·韦赫马奥拉维·皮卡佩卡·特沃拉
Owner ANDRITZ AG
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