US3348318A

US3348318A - Drying equipment

Info

Publication number: US3348318A
Application number: US488898A
Authority: US
Inventors: Norlyng Kristian Himmelstrup
Original assignee: BING AND GRONDAHLS PORCELLAENSFABRIK AS
Current assignee: BING AND GRONDAHLS PORCELLAENSFABRIK AS
Priority date: 1964-09-23
Filing date: 1965-09-21
Publication date: 1967-10-24
Anticipated expiration: 1984-10-24
Also published as: NL6512230A; DE1927987U; AT260090B; DK120989B; GB1099950A; CH439118A; BE670048A; DE1604774A1

Description

3957 K. H. NO'RLYNG 3,

DRYING EQUIPMENT Filed Sept. 21, 1965 2 Sheets-$heet 1 INVEN TOR. Km siian Hl'mme/s-L wqp Nor/ 07 Gilt 1957 K. H. NORLYNG DRYING EQUIPMENT 2 Sheets-Sheet 2 Filed Sept. 21, 1965:

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United States Patent 3,348,318 DRYING EQUIPMENT Kristian Himmelstrup Norlyng, Copenhagen, Denmark,

assignor to Aktieselskahet Bing & Grondahls Porcellaenslabrik (Porcelainfabrikerne Bing & Grondahl 0g Nor-den A/S), Copenhagen, Denmark Filed Sept. 21, 1965, Ser. No. 488,898 Claims priority, application Denmark, Sept. 23, 1964, 4,671/64 3 Claims. (Cl. 34105) This invention is concerned with a method and an equipment for the predrying of ceramic bodies by means of hot air, preferably moderately heated air, and has for its object to describe a method and an equipment by which it is possible to obtain a rapid and effective predrying without the risk that such rapid drying should cause disadvantages, such as deformation or cracking of the ceramic bodies.

Drying equipments of this kind are used for instance in the porcelain industry where pre-shaped soft plastic bodies have to be pre-dried and where a rapid pre-drying is of the greatest importance due to the fact that thereby it is possible to obtain that the normally used plaster moulds will be ready for re-use relatively quickly. It has to be mentioned that the predrying necessarily must take place while the bodies are supported on these moulds.

After the termination of the predrying the pre-dried bodies may be removed from the plaster mould and the drying process may be continued in any convenient manner.

By the previously known drying equipments it has not been possible to accelerate the pre-drying without the risk of a considerable cracking of the ceramic bodies. It has now been proved that these disadvantages might be avoided by a drying equipment which for each object to be dried has a nozzle aggregate with a number of elongated tube-shaped nozzles extending from the bottom of an air pressured chamber, the nozzles being positioned substantially mutually parallel and in such a manner that the stream of air formed by all the nozzles together will have a sectional shape which is substantially the same as a plane vertical projection of the body and coinciding therewith. It has further been proved that the most favor able drying conditions are obtained when the openings of the nozzles and the air pressure are adapted in such a manner that the drying air is leaving the nozzles with a velocity of at least 10, preferably 15-20 meter per second, or even more.

The invention shall further be explained in connection with the drawing showing in FIGURE 1 a side view of a drying equipment in accordance with the invention, the casing being partly cut away in order to show the interior arrangements and FIGURE 2 showing a side view and partial vertical cross-section of a nozzle aggregate from such equipment.

In FIG. 1 is shown a drying equipment consisting of a casing 1 surrounding a transportating system by which a chain 2 running over wheels 3 is carrying a number of swing carriers 4 each carrying a plaster mould 5. It will be observed that on each of the plaster moulds carried by the swing carrier on the left hand and the upper part of the chain a plate or saucer 6 is placed. The casing is provided with an opening 7 through which the saucers might be romevd from the mould and consequently the swing carriers on the right hand part of the chain has no saucers placed thereon. The removing of the saucers and the replacement of the moulds with other moulds on which plates or saucers are placed, do not belong to the invention and is therefore not further described.

At the horizontal parts of the chains there are in the casing provided a number of nozzle aggregate 8 and such a nozzle aggregate is shown in FIG. 2 in a larger scale and shall be further explained below.

In FIG. 2 is shown a part of a supporting plate 9, of a swing carrier and on this supporting plate is shown a plaster mould 5 on which again a saucer 6 is placed. Above this saucer the nozzle aggregate 8 is positioned and it consists of a flat air chamber 10 having an air supply tube 11 for moderately preheated drying air under a certain pressure. A number of elongated tube-shaped air nozzles 12 are attached to the bottom of said chamber so that the dlying air might be let through these nozzles against the plate 6 and thereby cause an accelerated predrying. The elongated nozzles 6 are intended for imposing to the air a considerable velocity and simultaneously allow the drying air which has already contacted the upward surface of the plate 6 to escape upwardly between the nozzles 12. The number of nozzles, the distribution thereof, the distance between adjacent nozzles, the diameter of each nozzle as well as the velocity of the air, may be varied in regard to the size and shape of the object to be dried. The nozzle aggregate may also be used in different manners. It is, for instance, possible to move the object to be dried stepwise so that in a certain period it is standing coaxially with one aggregate and during the next step it will stand below another aggregate. It is also possible to let the moulds with the objects move continuously when simultaneously the nozzle aggregate is adapted to follow the moulds along a considerable distance of the movement of the moulds. Further, the mould as well as the nozzle aggregate could be stationary during the whole predrying period thus remaining in their mutual coaxial position.

By the use of such an equipment the total air stream is concentrated against the object and the air reflected from the object will not-as it is usual with the previously known equipments-in any respect distort the streams of air directed against the objects as the air can pass upward-s between the tube-shaped nozzles and therefrom escape in the space around the nozzle aggregates where there is no real beam of air and where the air consequently in a relatively big space may pass to a sucking place very smoothly and without influence of any kind of the concentrated air beams coming from each of the nozzle aggregates.

In this connection it should be mentioned that the rapid drying is only obtainable by means of a stream of air with a considerable velocity due to the fact that during this first phase of the drying process it is not possible to use a drying air with a very high temperature. Consequently a rather big amount of air with a moderate heating has to be used.

The big number of nozzles will of course cause a drying in spots but the spots will be placed so close to one another that they are merging during the continuation of the drying process so that for instance a saucer or a plate will obtain very uniform drying conditions. The tensions which are caused during the drying process due to the shrinkage of the object will be distributed with very small tension gradients notwithstanding the rather rapid drying. As soon as the drying air has released its contents of heat and has absorbed an amount of moisture it may easily escape upwardly between the elongated nozzle tubes without effecting in any undesired manner the drying air which is blown downwards from the nozzles.

The cross-section of the aggregate should approximately be of the same size as the body to be dried and this body should also be positioned coaxially with the aggregate in order to avoid any loss of energy to drying air which is not utilized. Simultaneously the air will then have the best possibilities for getting away without doing any harm.

What is claimed is:

1. An apparatus for drying ceramic bodies as they are transported along a horizontal path, said apparatus comprising a casing extending above said path and containing at least one air pressure chamber and air outlet means; a nozzle aggregate for each ceramic body to be dried, each aggregate comprising a plurality of elongated parallel noules extending downwardly from said chamber to the vicinity of said path, and means to supply air to said chamber at a predetermined pressure so that it passes through said nozzles, contacts the surfaces of said bodies, and is then reflected upwardly therefrom, said nozzles being spaced apart sufficiently to allow the reflected gases to flow therethrough towards said air outlet means, the spacing between the discharge end of said nozzles and said ceramic body being such that the refiected gas will not impinge on the discharge from the nozzles.

2. An apparatus as claimed in claim 1, further comprising a conveyor on which said bodies are supported, said conveyor being adapted for stepwise conveyance of the bodies, each step corresponding to the distance between adjacent nozzle aggregates.

3. An apparatus as claimed in claim 1, wherein said air outlet means are formed in the spaces between said nozzle aggregates.

References Cited Duff et a1. 34-105 KENNETH W. SPRAGUE, Primary Examiner.

Claims

1. AN APPARATUS FOR DRYING CERAMIC BODIES AS THEY ARE TRANSPORTED ALONG A HORIZONTAL PATH, SAID APPARATUS COMPRISING A CASING EXTENDING ABOVE SAID PATH AND CONTAINING AT LEAST ONE AIR PRESSURE CHAMBER AND AIR OUTLET MEANS; A NOZZLE AGGREGATE FOR EACH CERAMIC BODY TO BE DRIED; EACH AGGREGATE COMPRISING A PLURALITY OF ELONGATED PARALLEL NOZZLES EXTENDING DOWNWARDLY FROM SAID CHAMBER TO THE VICINITY OF SAID PATH, AND MEANS TO SUPPLY AIR TO SAID CHAMBER AT A PREDETERMINED PRESSURE SO THAT IT PASSES THROUGH SAID NOZZLES, CONTACT THE SURFACES OF SAID BODIES, AND IS THEN REFLECTED UPWARDLY THEREFROM, SAID NOZZLES BEING SPACED APART SUFFICIENTLY TO ALLOW THE REFLECTED GASES TO FLOW THERETHROUGH TOWARDS SAID AIR OUTLET MEANS, THE SPACING BETWEEN THE DISCHARGE END OF SAID NOZZLES AND SAID CERAMIC BODY BEING SUCH THAT THE REFLECTED GAS WILL NOT IMPRINGE ON THE DISHCHARGE FROM THE NOZZLES.