ARRANGEMENT FOR CLEANING SURFACES OF A WOOL CHAMBER IN THE MANUFACTURE OF MINERAL WOOL

Abstract: The invention relates to an arrangement for cleaning a wool chamber in the manufacture of mineral wool. In the manufacture of mineral wool a binder is added to the stream of fibers (1) which is deflected towards the wool chamber and said binder deposits itself in fine droplets on the fibers. The binder-loaded fibers which touch against the walls and roof of the wool chamber adhere to them because the binder hardens upon contact with the hot surfaces. Gradually a hard deposit of binder and fibers is formed upon the walls. According to the invention cleaning of the walls is substantially simplified by means of making the walls (6, 9) and/or the roof of a double-walled construction, perforating the inner walls (6) and applying a reduced pressure in the cavity (7) between the walls and holding a detachable lining (8) against the inner walls by means of suction. When said detachable lining has become coated with deposits of binder and fibers to a certain thickness production is halted and the reduced pressure is broken off, whereon the detachable lining together with the deposits falls off and a new detachable lining or linings (8) respectively are applied to the perforated walls (6).

Description: Arrangement for Cleaning Surfaces of a Wool Chamber in the Manufacture of Mineral Wool The invention relates to an arrangement for cleaning the inner surfaces of a wool chamber for the manufacture of mineral wool in accordance with the preamble to the ac¬ companying Claim 1. In the manufacture of mineral wool a melt of mineral raw material is caused to run to a fibrillation unit. This can consist of a series of rapidly rotating cylinders on which the melt runs down over the peripheral surfaces and is thrown out by these and stretched during the formation of fibres. A directed stream of gas deflects the fibres into the wool chamber and deposits them on a collecting organ, which can consist of a perforated conveyor belt or one or more perforated drums. The fibrillation unit can alternatively consist of a rapid¬ ly rotating centrifugal receptacle with a perforated peri¬ pheral surface. The melt runs down into the centrifugal re¬ ceptacle and is thrown out through the holes and converted to fibre. A stream of gas deflects the fibres to the wool chamber and deposits them on the collecting organ. A thermosetting binder is added to the stream of fibres in the wool chamber so that the fibres shall fasten to each other to form a mat of mineral wool. The addition of the binder is the cause of a troublesome problem. The binder deposits itself as small sticky drops on the fibres and wads of wool with the consequence that the fibres and wads of wool which touch against the walls of the wool chamber easily fasten to the walls as a result of the adhesive action of the binder. The binder hardens rapidly in the hot environment in the wool chamber and the material fastened on the walls forms a rapidly growing hard coating. This coating must be removed before it becomes too thick, which means that about once a week the machines must be stopped for the sheet-steel walls to be scraped clean. The cleaning is a difficult and time-consuming task. Hitherto attempts have been made to reduce or eliminate this problem by bolting on a replaceable lining of mineral wool. When the surface is scraped clean the board of min¬ eral wool- splits readily and the outer layer comes off to¬ gether with the deposits. When the boards have been reduced to a certain thickness they must be replaced. Linings consisting of teflon sheets attached to the walls of the wool chamber by screws, clamps and other fastening elements have also been used. The task of cleaning is eas¬ ier, but these sheets too must be replaced regularly by new ones. It is also known for the walls of the wool chamber to be made movable, so that during their movement from one side of the chamber to the other they are cleaned while outside the region of the wool chamber. According to the published EP Application No. 194,605 an attempt is made to overcome the deposit problem by water- cooling the walls of the wool chamber. Owing to the lower temperature of the walls the drops of binder do not harden on contact with the walls but instead come off and end up on the receiving conveyor. The object of the present invention is to simplify the cleaning and to avoid the use of water in contact with the walls of the wool chamber, which involves problems e.g. from the point of view of corrosion. This has been achieved by creating an arrangement of which the principal characteristics are apparent from Claim 1. The walls of the wool chamber have accordingly been made into a double construction in known fashion and the inner surface of the walls has been perforated. Within said double construction a reduced pressure has been arranged with the aid of which a heat-resistant detachable lining is held fast against the inner wall by suction. When the lining has become coated with so much mineral wool that it is necessary to carry out cleaning, this is done simply by interrupting the reduced pressure in the double walls, af¬ ter which the lining comes off and can be readily gathered up. New lining can be simply applied in place after the re¬ duced pressure has been re-applied. The detachable lining is suitably of metal and can be alu¬ minium foil or thin sheet metal. Teflon is also a suitable lining material. The detachable lining can also be a dense heat-resistant cloth which possibly is coated with teflon or aluminium. The lining is suitably cut into pieces which are fitted to the shape of the walls of the wool chamber. It is then a simple matter to put the lining in place. The reduced pressure is appropriately achieved by means of a suction fan when the lining is flexible and the pressure reduction does not need to be so great. When the lining is of stiffer material, e.g. thin sheet metal, a vacuum pump is used. Preferably there should be a separate suction fan or vacuum pump respectively for the roof area of the wool chamber and one for each wall. The pressure reduction in the walls should be considerably greater than that which normally prevails in the wool cham¬ ber, which is approx. 50 - 200 mm water column. The pres¬ sure reduction in the walls should therefore be preferably at least 500 mm water column. ' It is also advantageous to divide the double-skinned roof and wall constructions into smaller sections and furnish them with safety systems which guarantee that the reduced pressure is maintained in the other sections even if the perforated lining is damaged or comes loose in some part of the wall or roof. The shape and pattern of the perforation can vary. The holes can be circular, oval or rectanglar and the pattern of the holes can be chosen freely. The size of the holes shall not be greater than that used on the receiving con¬ veyor of the wool chamber. Namely if some part of the de¬ tachable lining of the walls of the wool chamber is miss¬ ing, some of the fibres from the stream of fibres will be drawn against the exposed holes and cover them. If the holes were too large the fibres would be sucked through the holes and a continuous leakage of fibres would occur. A combined hole area amounting to 20 - 60 % of the total area is suitable. When fibre manufacture is in progress binder-coated fibres are continuously deposited on the lining-covered walls of the wool chamber. When the deposit has reached a certain thickness production is halted and the reduced pressure in the walls of the wool chamber is broken off, whereon the detachable lining immediately comes off and falls down to the bottom of the wool chamber, from " where it can readily be gathered up. The reduced pressure is then reconnected and clean lining sucked onto the walls of the wool chamber, after which production can be resumed. The lining should be changed about as often as the walls of the chamber are scraped clean today, i.e. about once a week. Compared with scraping clean, exchange of the detachable lining is con¬ siderably faster and simpler. In the following the invention is described in greater de¬ tail with reference to the accompanying figures; which il- lustrate two advantageous embodiments of the arrangement according to the invention and in which Figure 1 shows a vertical cross-section of the arrangement according to the invention applied to a wool chamber for the manufacture of glass fibre and Figure 2 shows a vertical cross-section of the arrangement according to the invention applied to a wool chamber for the manufacture of mineral wool. In the figures the reference number 1 denotes the stream of glass fibres or mineral fibres respectively, the number 2 the collected fibre mat, the number 3 the receiving con¬ veyor on which the mat is formed. The number 4 denotes a suction box beneath the receiving conveyor and the number 5 an outlet for the stream of gas which is sucked out. The outlet is connected to a fan which is not shown. The num¬ ber 6 denotes the inner perforated wall in the double wall constructions, the number 7 the cavity space in said con¬ structions, the number 8 the detachable lining which is held against the inner wall by suction and the number 9 the unperforated outer wall in the wall construction. The number 10 denotes a spacing piece in the double wall and the number 11 denotes an air oulet to the suction fans. In the embodiment according to Figure 1 the glass melt is thrown out through the holes in the fibrillation unit and converted to fibres. A first gas stream stretches out the glass fibres 1 and subsequent directed gas streams guide the possibly oscillating fibre streams 1L and 1R (instan¬ taneously the left and the right) towards the wool chamber and the receiving conveyor 3 on which the fibre mat 2 is formed. The addition of binder is not shown in the figure. The vertical walls are constructed as double walls 6, 9 with a cavity 7 between them. The inner walls 6 are per- forated and a detachable lining material 8 is held against them by suction. Particularly in the lower parts of the wool chamber the outermost layer of the fibre streams comes into contact with the walls of the wool chamber and fastens to the lining 8 on the inner walls. When the de¬ posit on the lining 8 has reached a certain value the de¬ tachable lining is replaced in the way described previous¬ ly * The suction pressure is conducted through the outlet 11 which is connected to suction fans which are not shown. In the embodiment according to Figure 2 the mineral melt runs down onto a fibrillation unit consisting of rapidly rotating cylinders and strikes the peripheral surface of the first cylinder, from where the melt is thrown onto the peripheral surface of the next cylinder and simultaneously drawn out into fibres. A gas jet defects the fibre stream 1 against the upwards inclined receiving conveyor 3. The reduced pressure in suction box 4 draws the fibre stream towards the receiving conveyor which transports the fibre mat 2 formed to the following stage of production. The roof is of double construction and consists of an outer jacket 9 and a perforated inner surface 6, against which the detach¬ able lining 8 is held fast by suction. The reduced pressure is achieved in the same manner as in the preceding case. The side walls which are not shown are also of double con¬ struction and furnished with a lining in the same manner as in the wool chamber according to Figure 1. The outlet 11 can be furnished with non-return valves which prevent the ingress of air during momentary disturbances in the vacuum system. The double walls can be divided into sec¬ tions and furnished with a safety system which guarantees that the reduced pressure is maintained in the other sec¬ tions even if some part of the detachable lining is damaged or comes off. The spacing piece 10 has been introduced into the double walls to prevent the walls being collapsing as a consequence of the reduced pressure. The suction fan, not shown, which creates the reduced pres¬ sure can be a suction fan or a vacuum pump. The choice of type depends on how great a reduction of pressure is needed in order to overcome the reduced pressure in the wool cham¬ ber and to hold the detachable lining in place. The pres¬ sure reduction in the wall constructions should be appreci¬ ably greater than the pressure reduction in the wool chamber since the latter affects the entire surface, i.e. the entire lining, whereas the pressure reduction in the walls affects only the perforated part, i.e. 20 - 50 % of the surface. As noted earlier the reduction of pressure in the wool chamber is normally between 50 and 200 mm water column, so that the reduction in pressure in the wall constructions should pre¬ ferably be at least 500 mm water column. Flexible foil material is suitably held in place by suction fans and stiffer material by vacuum pumps. Alternatively one can contemplate facilitating cleaning of the wool chamber walls by means of applying an excess pres¬ sure in the double wall construction and producing a fluid- izing layer adjacent to the inner wall, thus creating a re¬ pellent effect on the inner wall and thereby preventing loose fibres from depositing themselves on the inner wall.

Claims: Claims 1. An arrangement for cleaning the inner surfaces in a wool chamber for manufacture of mineral wool, said wool chamber consisting of a space enclosed by side walls, floor and roof, and including a fibrillation unit in the inlet end from which the fibres formed (1) are deflected with the aid of gas jets towards a receiving conveyor (3) and deposited thereon, -in which arrangement the roof and/ or walls of the wool chamber consist of perforated double constructions (6, 9), characterized in that the inner surface/surfaces (6) of the double constructions are per¬ forated and that a reduced pressure acting in the cavity space (7) is arranged to hold a thin, heat-resistant de¬ tachable lining . (8) against said perforated surface/sur¬ faces by means of suction. 2. An arrangement according to Claim 1 , characterized in that said double roof and/or wall constructions (6, 9) each have their own pressure-reducing device. 3. An arrangment according to Claim 1 or 2, characterized in that said double roof and/or wall constructions (6, 9) are divided into smaller sections with safety system which guarantees reduced pressure in the other sections in the event of disturbances in one or more sections. 4. An arrangement acording to any of Claims 1-3, charac¬ terized in that the holes of said perforation (8) con¬ stitute altogether approx. 20-60 % of the total area of the detachable lining. 5. An arrangement according to Claim 4, characterized in that the hole size of said perforation is less than or equal to the hole size of the perforation on the receiving conveyor (3) . 6. An arrangement according to any of the preceding claims, characterized in that said detachable lining (8) consists of separate pieces which are fitted to the shape of the roof and walls respectively. 7. An arrangement according to any of the preceding claims, characterized in that said detachable lining is metal, for example an aluminium foil or thin sheet metal, teflon or a dense heat-resistant cloth.

Inventors: NURMI TOM EMIL EDGAR, NURMI, TOM, EMIL, EDGAR
Applicants: PARTEK AB, OY PARTEK AB
Application year: 1988
Main classification: C03B37
IPC codes: C03B37, D04H1