Heating – With work cooling structure – Cooling liquid contacts work
Patent
1991-01-17
1994-02-22
Yuen, Henry C.
Heating
With work cooling structure
Cooling liquid contacts work
110171, 432246, F27D 1502, F25D 1702
Patent
active
052882276
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The invention concerns a method for cooling ceramics, especially ceramic tiles produced in roller kilns, and the relative plant, or rather a completely new procedure for cooling glazed or unglazed ceramics, such as ceramic tiles in the initial heat treatment following the dryer and in kilns; the cooling system is also to be covered by a patent application.
BACKGROUND OF THE PRIOR ART
Current technology involves the cooling of ceramics using air conveyed by electric blowers into the cooling sections, which especially in kilns require expensive structures, stretching for many meters: this involves high plant construction and operating costs, in addition to the extensive space requirements and high capital investment, without considering the emission into the atmosphere of hot air at about 150.degree. C. from the kiln.
There is considerable scope for improvement of this state of the art in relation to the possibility of eliminating the problems mentioned without damaging the product or impairing its quality.
From the above consideration there derives the need to solve the technical problem of identifying a new method providing a largescale reduction in the construction and operating costs of the cooling plant for ceramic products leaving the high-temperature pretreatment chamber and/or leaving the firing chamber, or in any heated state after which cooling is required: i.e. for any type of ceramic plant to which the new method is applicable.
This method must be suitable for application both to new kilns and to those already in operation, with structural modifications in the case of the latter.
The present invention solves the above technical problem by adopting a method involving passing the hot ceramic articles through water, by immersion, and/or in jets, and/or sprayed, and/or nebulized and/or in the form of steam: the latter case is especially suitable for the areas with highest temperature, obtaining all or part of the steam required from the steam generated by water-cooling in lower-temperature zones. When very hard water is used, and in all cases concerning glazes on which calcium salts deposited by the cooling water would be noticeable, the method envisages cooling from beneath only, i.e. on the rear of the tile, without the projection of any water which might reach the upper surface which has been glazed or is destined for decoration in any way.
The plant implementing the method includes at least one booth, preferably subdivided into one or more cooling stations: with upper and lower spray nozzles spraying out water, with upper and lower packs of disks revolving at high speed and projecting water by centrifugal force, by immersion, providing steam, or mixed. The steam generated by the water cooling process is removed by fans, while excess water is recycled.
In all cases the heat may be recycled using heat exchangers. When cooling is on the underside of the tile only, in order to prevent the deposit of calcium salts on the face intended to remain in view, the system incorporates idle or power-driven sponge transversal rollers provided with water from the inside or picking up water from below, which wet the tiles from underneath the conveyor belt line.
In the case of cooling from temperatures significantly above 150.degree. C., since the tiles are to be conveyed on rollers, said rollers will be hollow and given radial holes to sprinkle the underside of the row of tiles with water supplied to the rollers themselves under a slight pressure.
In an exemplary application of the method constructed for a roller kiln already installed for production of 10,000 m.sup.2 /day of glazed and unglazed tiles, with a weight of approximately 13 kg/m.sup.2, with feed speed approximately 5 m/min., the system comprises a booth with water cooling successfully provided by means of two rows of nozzles arranged above and below the tile route, with a field of 0.5 m for each nozzle, forming a sprinkling zone 1 m in length. The booth, in stainless steel which may be replaced by plastics in the l
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patent: 4431406 (1984-02-01), Weiss
patent: 4444556 (1984-04-01), Andersson
patent: 4960056 (1990-10-01), Pillsbury
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