Glass manufacturing – Processes – Fining or homogenizing molten glass
Patent
1998-01-12
2000-04-11
Silverman, Stanley S.
Glass manufacturing
Processes
Fining or homogenizing molten glass
65 19, 651347, 65335, 65347, C03B 518, C03B 1908, C03B 514, C03B 300
Patent
active
060475668
DESCRIPTION:
BRIEF SUMMARY
This application is the national phase of international application PCT/EP96/01267 filed Mar. 22, 1996 which designates the U.S.
The present invention concerns a method for melting recycled silicate starting materials wherein heat for melting the silicate substances is generated while supplying fuel and combustion air, and furthermore concerns a device for carrying out this method.
For the production of mineral wool products, melting silicate starting materials is a basic prerequisite. Herein there is a need for also using mineral wool waste as recycled starting materials.
Supplying recycled starting materials or silicate waste materials, respectively, into the combustion chamber presents problems particularly where pressure above atmospheric exists inside the combustion chamber. This is, for example, the case with a combustion chamber in the form of a cyclone as known from the generic document DE 43 25 726 A. If the starting material to be introduced is present e.g. in the form of fine particles or has a high surface/mass ratio, then the weight force of the starting material particles will not be sufficient to overcome the lift force resulting from the positive pressure, in the absence of which the starting material particles might be charged in the manner of a bulk material by pouring into the combustion chamber. If, now, the starting material were injected rectilinearly into the combustion chamber by means of an accelerated transport flow, although it would be possible to thereby improve penetrating ability of the starting material into the combustion chamber, this would considerably reduce the dwelling time of the starting material inside the combustion chamber owing to the high flow velocity, with the result that the starting material cannot be melted satisfactorily any more.
In the case where recycled silicate starting materials or silicate waste materials, respectively, are to be melted, organic impurities of the recycled starting material and waste products adhering to it, respectively, which e.g. result from binding agent or remainders of lamination, must concurrently be oxidised besides melting the starting material. This requires a long dwelling time of the recycled starting material inside the combustion chamber. Following their formation, the combustion products must moreover not be remixed with the obtained pure silicate molten material. During such a melting process performed in a suitable combustion chamber, more pressure builds up on top of the inherently present pressure above atmospheric mentioned above because the originally solid impurities are present in the form of gaseous combustion products following their combustion, bringing about an increase of their volume. This increases the difficulties of introducing the starting materials into the combustion chamber, i.e. particularly when the surface/mass ratio is relatively high.
Accordingly, it is the object of the present invention to impart sufficient penetrating ability into the combustion chamber to the recycled starting material or silicate waste materials, resp., in order to enable complete melting of the recycled starting material on the one hand, and--given the case achieve--complete combustion of the waste products and respective impurities adhering to the recycled starting material on the other hand in order to produce a molten silicate material that is sufficiently pure for producing new mineral wool products.
When a rotating transport flow comprising helical flow filaments of transport air and recycled starting material or silicate waste materials, respectively, into a combustion chamber in the direction of the helix axis, this results in the advantage of the starting material having a large amount of kinetic energy and thus good ability of penetrating into the combustion chamber while exhibiting only a relatively small velocity component in the direction of the helix axis. The starting material, owing to its movement along helical trajectories, thus experiences a considerably longer dwelling time inside the combustion chambe
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Fleckenstein Hermann
Siegler Markus
Isover Saint-Gobain
Ruller Jacqueline A.
Silverman Stanley S.
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