Paper making and fiber liberation – Processes and products – Running or indefinite length work forming and/or treating...
Patent
1991-11-07
1993-05-18
Hastings, Karen M.
Paper making and fiber liberation
Processes and products
Running or indefinite length work forming and/or treating...
34 23, 34155, 162290, D21F 700
Patent
active
052118134
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a steam shower.
Steam showers are much used in the manufacturing of paper. They are used to apply steam to a paper sheet passing beneath. The application of steam is to increase the temperature of the sheet to facilitate the removal of the water from the sheet, that is to facilitate its drying to form the paper, principally by decreasing the viscosity of the water in the sheet to facilitate drainage. In other applications the shower is used to improve and control the mixture and other sheet property profiles of the web by the addition of heat and water.
A product available under the trade mark Calendizer from Devron-Hercules Inc. is an example of a steam shower normally used prior to the calendaring of the paper. It is designed to operate on a paper or board machine to improve sheet surface properties. It is designed for steam flow rates in the range 0.02 to 0.04 tonnes of steam per tonne of paper going on to the reel of the papermaking machine. The maximum steam pressure to the shower is 15 psig.
A typical problem with the equipment operating at the above temperatures and pressures is the dripping of condensate on to the sheet. With a shower positioned directly above the sheet the problem is severe and difficult to overcome. The dripping of condensate on to the sheet has an undesirable effect on the sheet.
The present invention seeks to provide an apparatus that avoids the problem of condensate drip.
Accordingly, the present invention is a steam shower to supply steam to a web passing beneath and comprising:
a main supply header;
a preheat chamber enclosing said header;
means to proportion steam flow between the preheat chamber and the main supply header;
at lest two chambers to receive steam in sequence from said main supply header;
means dividing the at least two chambers into compartments along the length of the shower;
a plurality of profiling valves to control flow from the main supply header to the first chamber; and
outlets in the last of the at least two chambers through which steam passes to the web.
When the incoming steam is wet it is preferred that there be three chambers to receive steam in sequence from the main supply header. It is also preferred to have means to increase the surface area within the second chamber to trap condensate.
In a further preferred aspect there is a fourth chamber, beneath the second chamber. A passageway between the second and fourth chambers allows condensate to pass from the second to the fourth chamber. Typically, the fourth chamber is common to all compartments of the second chamber, that is it is not divided into compartments along the length of the shower.
A fifth chamber is desirably provided adjacent the outlets of the third chamber and receives a direct steam supply. It is particularly preferred that the fifth chamber and the preheat chamber are both adjacent to each other and to the outlets of the third chamber whereby steam leaving the outlets is heated by contact with the exterior of the fifth chamber in particular but also of the preheat chamber.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is illustrated in the drawings, in which:
FIG. 1 is side elevation of a steam shower according to the present invention;
FIG. 2 is sectional end elevation;
FIG. 2a is a detail of the steam shower; and
FIG. 3 is an end elevation.
The drawings show a steam shower able to supply steam to a web (not shown) passing beneath it and comprising, as shown particularly in FIG. 2, a main supply header 10. There is a preheat chamber 12 enclosing in the header 10 and an additional compartment 14, containing insulation, is positioned around a substantial part of the exterior of the preheat chamber 12. As shown in FIG. 1 there is a main steam pipe 16 for steam controlled by a main valve 18 and feeding steam to the preheat chamber 12. The apparatus includes a valve 20 to proportion steam flow between the pipe 16 and a branch pipe 22 that feeds the main supply header 10. There is a first chamber 24, second chamber 25 and a third chamber 26 enclosed by
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Sawley David J.
Woodman Warren
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