Fluidized bed

Claim 1

A fluidized bed comprising a container having a porous base and containing a mass of refractory particles, conduit means below said porous base for supplying to the underside thereof a non-combustible fluidizing medium whereby said medium can flow, when the bed is in use, through the porous base and into the mass of refractory particles, the layer of refractory particles immediately adjacent to said porous base being formed of denser and/or larger particles than the remainder of said refractory particles so that the particles of said layer do not become fluidized when said fluidizing medium is applied thereto, and further conduit means in said container disposed above and spaced from said porous base for introducing into the container a gaseous medium for use in establishing combustion for heating said mass of refractory particles.

Claim 8

A method of heat treating articles by immersing them in a fluidized bed comprising a container having a porous base and containing a mass of refractory particles, comprising the steps of: (a) arranging a layer of the refractory particles adjacent the porous base, such layer being of denser and/or larger particles than the remainder of said mass so as to remain unfluidized during use, the remainder of said mass of particles being fluidizable; (b) supplying a gaseous fluidizing medium to the underside of said porous base and allowing said medium to flow therethrough and into said mass of refractory particles at a selected velocity as will leave said layer of denser and/or larger particles unfluidized while forming a fluidized layer thereabove from said remainder of the mass of refractory particles: (c) maintaining the temperature of the fluidized layer of refractory particles at a selected elevated temperature with said porous base being thermally shielded from said fluidized layer by said unfluidized layer of denser and/or larger particles.

Claim 9

A method of heat treating articles by immersing them in a fluidized bed comprising a container having a porous base and containing a mass of refractory particles, comprising the steps of: (a) arranging a layer of the refractory particles adjacent the porous base, such layer being of denser and/or larger particles than the remainder of said mass so as to remain unfluidized during use, the remainder of said mass of particles being fluidizable; (b) supplying a gaseous fluidizing medium to the underside of said porous base and allowing said medium to flow therethrough and into said mass of refractory particles at a selected velocity as will leave said layer of denser and/or larger particles unfluidized while forming a fluidized layer thereabove from said remainder of the mass of refractory particles: (c) maintaining the temperature of the fluidized layer of refractory particles at a selected elevated temperature with said porous base being thermally shielded from said fluidized layer by said unfluidized layer of denser and/or larger particles.

Claim 11

A method of heat treating articles by immersiny them in a fluidized bed including a container having a base subject to thermal damage by way of which a flow of gaseous fluidizing medium can be supplied to the interior of said container and said container having therein a mass of refractory particles, comprising the steps of: (a) arranging a layer of the refractory particles adjacent the base, such layer being of denser and/or larger particles than the remainder of the particles of said mass so as to remain unfluidized during use, the remainder of the particles of said mass being lighter and/or smaller than the particles of said layer; (b) supplying said gaseous medium to said base such that a flow of said fluidizing medium. is emitted therefrom and flows upwardly through said mass of refractory particles at a selected velocity such that said layer of denser and/or larger particles remains essentially unfluidized while a fluidized layer is formed thereabove from said remainder of the particles of said mass; (c) maintaining the temperature of the fluidized layer or refractory particles at a selected elevated temperature with said base being thermally shielded from said fluidized layer by said unfluidized layer of denser and/or larger particles.

Claim 12

A method of heat treating articles by immersiny them in a fluidized bed including a container having a base subject to thermal damage by way of which a flow of gaseous fluidizing medium can be supplied to the interior of said container and said container having therein a mass of refractory particles, comprising the steps of: (a) arranging a layer of the refractory particles adjacent the base, such layer being of denser and/or larger particles than the remainder of the particles of said mass so as to remain unfluidized during use, the remainder of the particles of said mass being lighter and/or smaller than the particles of said layer; (b) supplying said gaseous medium to said base such that a flow of said fluidizing medium. is emitted therefrom and flows upwardly through said mass of refractory particles at a selected velocity such that said layer of denser and/or larger particles remains essentially unfluidized while a fluidized layer is formed thereabove from said remainder of the particles of said mass; (c) maintaining the temperature of the fluidized layer or refractory particles at a selected elevated temperature with said base being thermally shielded from said fluidized layer by said unfluidized layer of denser and/or larger particles.