Drying and gas or vapor contact with solids – Apparatus – Sheet – web – or strand
Patent
1998-06-18
2000-07-25
Bennett, Henry
Drying and gas or vapor contact with solids
Apparatus
Sheet, web, or strand
34629, F26B 900
Patent
active
060923040
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The subject invention relates to a blow box intended to be used in a plant for drying a material web, such as a web of papermaking pulp being advanced through said plant, said blow box having an elongate, essentially right-angled parallelepipedon shape including an essentially horizontal upper box wall and being intended to be placed, jointly with a plurality of identical blow boxes, below the material web for the purpose of holding the material web floating, i.e. suspended in the air in a well-defined stable position above the upper blow box wall by means of air streams that are being blown out of the box while simultaneously drying the material web, said blow box being designed to be placed below the material web in a manner ensuring that the longitudinal centre line of the upper box wall extends transversely of the direction of advancement of the web, the upper wall of said blow box being formed with a plurality of essentially circular nozzle orifices, and with a plurality of so-called eyelid perforations, each one of said perforations consisting of a slit extending in parallel with said centre line and of a depression formed in the upper box wall adjacent the slit, at one side of the latter, said eyelid perforations being arranged in two rows extending in parallel with and on either side of the centre line, said nozzle orifices being arranged in rows, likewise extending in parallel with and on either side of said centre line, the eyelid perforations in one row being so displaced in the longitudinal direction of the blow box relatively to the eyelid perforations of the other row that the eyelid perforations of both rows together form a zigzag pattern, the eyelid perforations of both rows being directed in such a manner as to cause air to exit essentially in parallel with the upper box wall, towards said centre line, and essentially perpendicularly thereto, and the nozzle orifices being directed in such a manner as to cause air to exit essentially at right angles to the upper box wall.
SUMMARY AND OBJECTS OF THE INVENTION
The purpose of the subject invention is to provide a blow box of the kind outlined in the aforegoing and designed to provide improved heat transfer and thus improved drying efficiency compared with prior-art blow boxes of this kind, and also provide an increased floating height or higher level of suspension of the material web in the air, this being achieved under equal air efficiency and web fixation conditions.
This purpose is achieved in accordance with the invention with the aid of a blow box of the kind defined in the introduction and characterised in that the slits of the eyelid perforations in both rows are equally spaced from said centre line, that said centre line intersects the depressions of the eyelid perforations in both rows, that the nozzle orifices are arranged in respectively a first and a second pair of rows, the two rows of each pair being positioned on either side of and spaced equally from said centre line, that the distance of the rows of the first pair to said centre line is smaller than the distance of the rows of the second pair to said line, that for each eyelid perforation there is a corresponding nozzle orifice in the row of the first pair of nozzle orifices that is positioned on the same side of said centre line as a slit of the associated eyelid perforation, and also a corresponding nozzle orifice in the row of the second pair that is positioned on the opposite side of said centre line, each eyelid perforation and its two corresponding nozzle orifices being essentially in alignment in the crosswise direction of the blow box, and in that the upper box wall has a shallow continuous arcuate shape across its entire width.
In accordance with a preferred embodiment the height of the arc H representing the arcuate shape of the upper box wall is related to the degree of perforation P as follows: H=k.multidot.P-5.88, wherein k is a constant which is between 6.2 and 6.9 when H is denoted in mm and P in %.
The product of the distance l.sub.2
REFERENCES:
patent: 3982327 (1976-09-01), Kurie et al.
patent: 4719708 (1988-01-01), Karlsson et al.
patent: 5471766 (1995-12-01), Heikkila et al.
patent: 5946819 (1999-09-01), Reimer et al.
Berndt Kaltin, "More Capacity in Less Space with Flakt New Compact Pulp Dryer", Sweden.
Jorgen G. Hedenhag, "New Applications for Flakt Paper Dryers", Connecticut, Jan. 1976.
Halldin Claes
Karlsson Ingemar
Nilsson Lars
Sigvant Roger
ABB Flakt AB
Bennett Henry
Drake Malik N.
LandOfFree
Blow box for use in a plant for drying a material web does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Blow box for use in a plant for drying a material web, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Blow box for use in a plant for drying a material web will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1328293