Method and apparatus for the integrated cleaning of a paper-pulp processing plant

Abstract

A method for the integrated cleaning of a paper-pulp processing plant including one or more high density cleaners comprising the steps of supplying the rejected flow (10) from one of the high density cleaners to a screening centrifugal separator (11); screening out contaminants in the separator (11) using a screen hole size of less than 3.5 mm; thickening any fibrous material accepted by the separator (11) and returning same to stock being processed in the processing plant; and recovering liquid (B) from any material (A) rejected by the separator (11) prior to disposing of the material. The invention further comprises an apparatus for performing the method.

Description

BACKGROUND OF THE INVENTION[0001]This application claims priority from European Application 08155077, filed Apr. 24, 2008.[0002]The present invention relates to a method and apparatus for the integrated cleaning of a paper-pulp processing plant used primarily, but not exclusively, for the production of corrugated paper and cardboard. The invention is particularly concerned with the cleaning of a plant used for processing paper-pulp produced from recycled paper and cardboard.[0003]In order to make paper, an aqueous suspension containing cellulosic fibres, and optional fillers and additives, is fed through pumps, screens and cleaners, which subject the stock to high shear forces. The resulting pulp is fed into a headbox which ejects the suspension onto a forming wire. Water is drained from the suspension through the forming wire so that a wet web of paper is formed on the wire, and the web is further dewatered and dried in the drying section of the paper machine. Drainage and retentio...

AI Technical Summary

Benefits of technology

[0007]It is an additional object of the present invention to reduce the liquid content of any unwanted material in order that it can be readily disposed of, for example, by dumping or incineration.

Problems solved by technology

The presence of these anionic colloids has an adverse effect on the paper production process.

This interferes with the production process in a negative way.

Firstly, it decreases the quality of the paper produced, for example by producing holes, dark spots and a reduction in the mechanical resistance of the paper.

Secondly, it neutralizes any cationic additives used within the process so that they are rendered less effective, which requires greater quantities of these additives to be added than would otherwise be the case.

Thirdly, the accumulation of the anionic colloids in the process machinery also results in more frequent breakdowns of this machinery, for example caused by obstructive sediment that also tends to cause the accumulation of dirt.

It also generally impedes the flow of the pulp through the machinery itself.

Ultimately, all of these factors have an adverse effect on the quality of the resulting paper.

Overall, therefore, the efficiency of the process is reduced which leads to increased costs.

However, when the cellulosic fibres have been produced from recycled paper and cardboard this often causes the unwanted anionic colloidal material to be reintroduced into the stock.

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