Flow box with two deflectors

Details Flow box with two deflectors Flow box with two deflectors

1983-01-20

1985-06-11

Bashore, S. Leon

Paper making and fiber liberation

Apparatus

Running or indefinite length product forming and/or treating...

162343, D21F 102, D21F 104

Patent

active

045226873

DESCRIPTION:

BRIEF SUMMARY
This invention relates to flow boxes or headboxes for feeding stock to form a web in the manufacture of paper or board material.
In the manufacture of paper the pulp or stock is forced under pressure through a distribution chamber from which it is carried by a series of pipes to an explosion chamber, into a slice chamber and out of a slice opening at rates of between about 400 and 2500 liters/minute/meter width of opening. The slice opening has a width corresponding to the width of the web of paper to be formed. The stock usually contains 0.6% to 2% solid fibres and unless the solids content is evenly dispersed in the stock as it leaves the slice openings variations in the basic weight of the web of paper in the cross-machine direction can occur.
The explosion chamber is a critical part of the flow box. As indicated by the name the stock is subjected to a sudden drop in pressure as it enters the explosion chamber sometimes together with impingement on a baffle plate therein to effect thorough mixing of the stock as a result of the turbulence created.
Nevertheless it has been found that basic weight variations in the cross-machine direction still occur. Evidence of these is visible particularly when the paper is wound into reels at the end of the paper making machine by virtue of undulations in the axial direction of the wound reel. Careful analysis of the cross direction weight profile of finished web has shown that prominent weight streaks occur at intervals associated with the spacing of the pipes connecting the distribution chamber to the explosion chamber.
According to the present invention there is provided a flow box for a paper making machine comprising an explosion chamber having a base wall, a top wall and two side walls, an outlet at the bottom of one of the side walls adjacent the base wall communicating with a slice chamber extending parallel to the base wall and a plurality of inlet pipes connecting the explosion chamber to a distribution chamber, the inlet pipes communicating with two rows of openings in the top wall of the explosion chamber and having an axial direction directed towards the base wall, a first deflector having an upper surface and a lower surface, the upper surface extending across the axial direction of the pipes of a first row of openings to form a divergent passage with the top wall in the direction of the second row of openings, and terminating at a distal edge outside of the axial direction of the pipes of the second row of openings, a second deflector extending from the other of said side walls across the axial direction of the pipes of the second row of openings, the second deflector having an upper surface forming a convergent flow passage with at least a part of the lower surface of the first deflector.
A flow of stock emerges from the first row of openings and is deflected by the first deflector towards a flow of stock emerging from the second row of openings. Combined with the sudden expansion of the stock leaving the pipes the stock is intimately mixed thereby and then flows through the convergent passage formed between the first and second deflector before entering the slice chamber.
Preferably the distal edge of the first deflector is between 10 and 30 mm below the top wall of the chamber. This dimension is a function of the angle that the upper surface of the first deflector makes with the top wall of the explosion chamber and hence the direction of the deflected flow of the stock from the first row of pipes towards the flow of stock from the second row of pipes.
The minimum dimension of the convergent passage between the lower surface of the first deflector and the upper surface of the second deflector is preferably between 5 and 15 mm. This dimension has been found to be important in affecting the flow of stock from the explosion chamber to the slice chamber.
Preferably the maximum dimension of the convergent passage is between 10 mm and 30 mm.
The upper surface of the second deflector can be inclined towards the first row of openings over that portion thereo

REFERENCES:
patent: 3236725 (1966-02-01), Goldsmith
patent: 3565758 (1971-02-01), Higgins et al.

Affiliated with

Also associated with

Rating

Flow box with two deflectors does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Flow box with two deflectors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Flow box with two deflectors will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1181599