Process arrangement in the short circulation of a paper machine

a technology of paper machine and short circulation, applied in the wet end of the machine, papermaking, textiles and papermaking, etc., can solve the problems of short circulation and air saturated, and achieve the effect of reducing the energy needed for pumping and increasing the back pressur

Inactive Publication Date: 2005-08-11
VALMET TECH INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0008] An object of the invention is to make it possible to maintain a higher back pressure than heretofore in the short circulation of a closed former, which enables a substantial reduction in the energy needed for pumping in the short circulation.

Problems solved by technology

However, thick stock may bring air with it to the short circulation, which air is apt to remain circulating in the process, so that the short circulation may, in the course of time, become saturated with air.

Method used

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  • Process arrangement in the short circulation of a paper machine
  • Process arrangement in the short circulation of a paper machine
  • Process arrangement in the short circulation of a paper machine

Examples

Experimental program
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Embodiment Construction

[0017]FIG. 1 shows a short circulation process arrangement for a closed former in which pulp suspension or wire water is not in contact with the ambient air at any stage. The parts of the process outlined with broken lines are not necessary in the process arrangement in accordance with the invention.

[0018] Thick stock M to be passed to a paper machine is conducted, possibly through a screening stage 20, so as to be mixed with wire water F0 flowing in a dilution duct 17 on the suction side of a feed pump 10. The dilution of the stock is accomplished as pipe dilution without a separate wire pit. The feed pump 10 pumps a diluted pulp suspension F1 into a headbox 11. A pulp suspension jet J is passed from the headbox 11 between walls 12 provided as continuations of a slice opening into a forming gap defined by two wires 13 and 14 such that between the headbox 11 and first dewatering boxes 15, 16 of a forming section the pulp suspension jet does not come into any contact with the ambien...

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Abstract

A process arrangement in the short circulation of a paper machine comprises a feed pump (10), a headbox (11), means (12) for passing a pulp suspension jet (J) in a closed space from the headbox (11) into a forming gap defined by two wires (13, 14), dewatering elements (15, 16) placed against the wires (13, 14) a dilution duct (17) for passing wire water from the dewatering elements (15, 16) to stock dilution, and an outlet duct (18) for passing excess wire water out of the short circulation. The dilution duct (17) and the outlet duct (18) are in flow communication, and the outlet duct (18) has means (19, 22) for keeping the pressure in the dilution duct (17) even. For controlling the pressure in the short circulation of a closed former, excess wire water is passed out through a tank (19) provided with an overflow or other control.

Description

CROSS REFERENCES TO RELATED APPLICATIONS [0001] This is a U.S. national stage application of International application No. PCT / FI03 / 00327, filed Apr. 25, 2003, the disclosure of which is incorporated by reference herein, which claims priority on Finnish Application No. 20020826, Filed May 2, 2002. STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT [0002] Not applicable. BACKGROUND OF THE INVENTION [0003] The invention relates to a process arrangement in the short circulation of a paper machine comprising a feed pump, a headbox, means for passing a pulp suspension jet in a closed space from the headbox into a forming gap defined by two wires, dewatering elements placed against the wires, a dilution duct for passing wire water from the dewatering elements to stock dilution, and an outlet duct for passing excess wire water out of the short circulation, which dilution duct and outlet duct are in flow communication with each other. [0004] The inv...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D21F1/66D21F9/00
CPCD21F9/003D21F1/66
Inventor HIETANIEMI, MATTI
Owner VALMET TECH INC
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