GB1310603A - Control of the termperature of glass melts - Google Patents

Abstract

1310603 Regulating glass melt temperatures; heat pipes HERMANN HEYE 20 March 1970 [3 April 1969] 13729/70 Headings F4B and F4U [Also in Division C1] The temperature of a glass melt during passage from a melting tank to a gob delivery ring of a feeder head is controlled by fitting the feeder head with a heat pipe, i.e. a closed heat transfer system which comprises a hollow chamber containing a capillary structure holding a heat transfer medium and which incorporates a closed space within which the heat transfer medium can flow when vaporized, as when one part of the melt is hotter than the rest, the vaporized medium flowing away from the hotter region to condense in another region and the capillary structure returns the condensed medium to the region of vaporization. As shown in Figs. 12 and 15 the gob feeder head 168 is provided with a heat pipe 197 in the feeder orifice 183, the pipe 197 consisting of inner and outer cylindrical walls 198, 199 joined to form a closed annulus, the internal surfaces of which are covered by a continuous capillary structure 200 holding the heat transfer medium. The wall 198 adjacent the glass melt will act as the vaporizing region and wall 199 as a condenser region. The feeder head 168 further includes ring shaped heat pipes 177 to 180, pipe 180 on base 191 of the feeder having a relatively narrow opening facing the forehearth 167 and pipes 177 to 179 being semicircular with arms extending parallel to the sides of the forehearth 167. The forehearth 167 may also be provided with heat pipes (173), 174 and (175) below the surface 170 of the glass melt. The structure in the forehearth may include metal plates, one on the base of the forehearth and the other raised in the melt, each traversed by a network of heat pipes. As shown in Figs. 20 and 21, the gob delivery rings 230 and 250 are provided with heat pipes 236 and 252. The single gob delivery ring 250 has the heat pipe 252 surrounding its housing wall 251 and being itself surrounded by a temperature control device 254 with control medium passing through its hollow interior 255. The double gob ring 230 comprises a ceramic housing 235 forming two orifices 231, 232 and the pipe 236 is a dish-shaped structure covering all the internal surface of the ring 230. Temperature controls may be provided, as on the left hand side where a channel 238 is provided through which control medium may flow or on the right hand side where the structure 236 rests on spacer lugs 240 forming hollow chambers 241 through which molten glass may flow as in the direction 242 and leaving through a vent 245 in the crown of the structure 236 over the central boss 247 of housing 235. As shown in Fig. 8 the forehearth 105 is provided with longitudinal heat pipes 117, (118), (119) in the melt 111 having upturned ends 121 passing through the cover-plate 110 and surrounded by a sheath 123, which can be filled with molten glass, and a temperature control device 125 through which air or like control medium can flow. U-shaped heat pipes 130 to 134 are located along the forehearth and extend to different depths in the melt. Temperature control devices can be provided on that part of the pipes extending outside the forehearth. In the melting tank and refining tank, the molten glass can be similarly homogenized by providing a series of heat pipes and as shown in Figs. 4 and 6, two heat pipe systems 75 and 76 may be used, each comprising a lattice of pipes 80, 81, 82 which may be in contact with each other or be fitted with connecting blocks 85, one of which is shown at 95 in Fig. 6, in which the heat pipes 80, 81, 82 are sealingly connected to a housing 97 covered internally by a capillary structure 98 which is connected to the capillary structures 99, 100, 101 of the pipes 80, 81, 82 respectively, whereby the flow of the heat transfer medium in the pipes is facilitated. All heat pipes in contact with the glass melt may be covered or coated with a ceramic where there is danger of oxides of the metals used colouring the glass. The temperature ranges of different glasses are very variable such as for lead glasses from 1100-1300‹ C. and for Zr glasses from 1300-1650‹ C. The materials for the pipe casing and the capillary structure with the heat transfer medium used therewith, are as follows: Ti-Zr-Mo with Li; W with Li; W with Ag-suitable for high melting point glasses; Ta with Li; Mo with Na; W with Na; Nb (99%)-Zr with Li. The capillary structure may be wire mesh with or without an annular gap around the mesh.