Heating elements, assemblies comprising several of these elements, furnaces constructed by means of said elements or assemblies, and preheating method for said furnaces

Claim 2

Resistor heating element of oxidation-resistant refractory material for a furnace, comprising two arms connected at one end by a common part, said arms being in the form of elongated parallel strips, having narrow facing sides along their longest dimension, the other ends of said arms being free and shaped so that they can be suspended and adapted to be supplied with electric current, the thickness of said arms as well as the distance which separates them decreasing from the free ends in the direction of the common part.

Claim 3

Heating element according to claim 1, wherein the two arms are parallel to a plane and bent at the same level in the same sense with respect to said plane along an angle not exceeding 165*, the free ends of the two arms having two plane surfaces substantially parallel between themselves and substantially perpendicular to the general direction of said longest dimension.

Claim 4

Heating element according to claim 1, wherein the thickness of said common part of the two arms is greater than the least value of their thickness.

Claim 5

Heating element assembly, comprising n superposed rows of m heating elements as claimed in claim 1 and m-1 support elements of a first type, the constituent arms of a given heating element resting on two neighboring and distinct support elements, said arms supporting in their turn two neighboring support elements of the row situated immediately above, all the arms which are in contact with the corresponding superposed support elements being adapted to be at the same potential on application of electric current, the outer arms of the heating elements situated at the end of a given row also being supported respectively on a support element of a second type of width half that of the others, the said second type support elements being constructed of a material compatible with that of the heating elements at the temperature of operation of the latter.

Claim 6

Heating element assembly, comprising n superposed rows of m heating elements as claimed in claim 1 and m-1 support elements of a first type, the constituent arms of a given heating element resting on two neighboring and distinct support elements, said arms supporting in their turn two neighboring support elements of the row situated immediately above, all the arms which are in contact with the corresponding superposed support elements being adapted to be at the same potential on application of electric current, the outer arms of the heating elements situated at the end of a given row also being supported respectively on a support element of a second type of width half that of the others, the said second type support elements being separated from the latter by platinum shims.

Claim 7

Heating element assembly, comprising n superposed rows of m heating elements as claimed in claim 1 and m-1 support elements of a first type, the constituent arms of a given heating element resting on two neighboring and distinct support elements, said arms supporting in their turn two neighboring support elements of the row situated immediately above, all the arms which are in contact with the corresponding superposed support elements being adapted to be at tHe same potential on application of electric current, the outer arms of the heating elements situated at the end of a given row also being supported respectively on a support element of a second type of width half that of the others, the said second type support elements being constructed for operation at very high temperature of the same material as the heating elements.

Claim 8

Heating element assembly according to claim 4, comprising heat-insulating means supported on the free ends of said elements.

Claim 9

Heating element assembly according to claim 4, wherein, for operation of the furnace at a temperature of the order of 1800*-1900*C, the support elements form a single bar of refractory material such as alumina, platinum plates being interposed between the single bar and the heating elements.

Claim 10

Furnace comprising an assembly of a plurality of heating elements according to claim 1, each element resting by its two arms on separate neighboring supports, constructed of a material compatible with that of the heating elements at the temperature of operation of the latter, heat-insulating means being provided to protect the said elements and supports.

Claim 11

Furnace comprising a plurality of assemblies according to claim 7, said assemblies being juxtaposed to form a downwardly open tunnel, closed overhead by heat insulating means.

Claim 12

Furnace comprising an assembly according to claim 8, defining a downwardly open tunnel, closed overhead by heat insulating means.