Thermal treatment of glass in a fluidized bed

A method of operating a fluidised bed for use in the processing of articles which are immersed in the bed, comprising immersing the articles in a part of a gas-fluidised bed of particulate material which is maintained in a quiescent uniformly expanded state of particulate fluidisation, regulating the temperature of the fluidised bed by heat exchange within the bed with the particulate material of a localised region of the bed away from the part in which the articles are immersed, and, between immersion of successive articles in the bed, engendering agitation within said localised region of the bed to enhance said heat exchange while maintaining said quiescent state of fluidisation of the part of the bed in which the articles are immersed.

A method of thermally treating a glass article, comprising immersing the article in a part of a gas-fluidised bed of particulate material which is maintained in a quiescent uniformly expanded state of particulate fluidisation, regulating the temperature of the fluidised bed by heat exchange with the particulate material in a localised region of the fluidised bed away from the part in which the articles are immersed, and, between immersion of successive articles in the bed, agitating said localised region of the fluidised bed to enhance said heat exchange while maintaning said quiescent state of fluidisation of the part of the bed in which the articles are immersed.

A method of thermally toughening a succession of hot glass sheets, comprising immersing the sheets in a part of a gas-fluidised bed of particulate material which is maintained in a quiescent uniformly expanded state of particulate fluidisation, circulating cooling fluid through an enclosed path in heat exchange relationship with a localised region of the fluidised bed away from the part in which the hot glass sheets are immersed, and, between immersion of successive glass sheets in the bed, engendering agitation within said localised region of the bed to enhance said heat exchange while maintaining said quiescent state of fluidisation of the part of the bed in which the sheets are immersed.

A method of thermally toughening a succession of hot glass sheets, comprising immersing the sheets in a gas-fluidised bed of particulate material which is maintained in a quiescent uniformly expanded state of particulate fluidisation, circulating cooling fluid through an enclosed path in heat exchange relationship with the fluidised material by circulating cooling fluid through an enclosed path at the periphery of the fluidised bed away from the central part of the bed in which the hot glass sheets are immersed, and, between immersion of successive glass sheets in the bed, engendering agitation within the bed to enhance said heat exchange by maintaining a quiescent state of fluidisation of the central part of the bed while causing localised agitation of the particulate material in the region of the enclosed path.

A method of thermally treating a glass article, comprising immersing the article in a gas-fluidised bed of particulate material which is maintained in a quiescent uniformly expanded state of particulate fluidisation, regulating the temperature of the fluidised bed by heat exchange with the particulate material at least in a localised region of the fluidised bed, and, between immersion of successive articles in the bed, agitating the fluidised bed at least in that region to enhance said heat exchange, and wherein said heat exchange with the particulate material includes extracting heat from the top of the fluidised bed by circulating cooling fluid through an enclosed path in heat exchange relationship with the whole of the top of the bed, and the agitation of the fluidised bed includes causing localised agitation of material to effect an increased rapidity of particule movement and particle mixing at the top of the bed to enhance heat exchange while maintaining said quiescent state of fluidisation in the lower part of the bed.

A method for the thermal treatment of a succession of glass articles, comprising the steps of:

• immersing each article in a part of a gas-fluidised bed of particulate material which is maintained in a quiescent uniformly expanded state of particulate fluidisation while each article is immersed;
• regulating the temperature of the fluidised bed by heat exchange with the particulate material in a localised region of the fluidised bed away from the part in which the articles are immersed;
• and agitating the fluidised bed in said localised region during the intervals between immersion of successive articles while maintaining the quiescent state of fluidisation of the part of the bed in which the articles are immersed, to enhance said heat exchange between the immersion of successive articles.

Apparatus for thermally treating a glass article, comprising a tank for containing a fluidised bed of particulate material, gas supply means at the bottom of the tank for maintaining a quiescent uniformly expanded state of particulate fluidisation of the bed, heat exchange means located in the tank, and agitator means mounted in the tank adjacent the heat exchange means for maintaining localised agitation in the particulate material contacting the heat exchange means.