A chamber (1) for hardening building materials comprises sheet metal elements which are insulated from one another and are built on a base plate (5) and which form walls (2) and a ceiling (3). The chamber can be manufactured and operated inexpensively and is suitable both as a curing chamber for concrete blocks and for building materials cured with CO.sub.2. To this end, it is proposed that the walls (2) and/or ceiling (3) consist of self-supporting, double-walled sheet metal elements (4) connected to one another in an essentially gas-tight manner, and that the double-walled sheet metal elements (4) of the supply and/or discharge and distribution a gaseous hardening medium from outside the chamber (1) into its interior.

A hearth for a metallurgical furnace, in particular for a blast furnace, the hearth including a wall lining and a bottom lining of refractory material for containing a molten metal bath, the bottom lining including a lower region and an upper region that is arranged to cover the top of the lower region and that is built of ceramic elements, the ceramic elements of the upper region being made of microporous ceramic material including a granular phase made of a silico-aluminous high alumina content granular material and a binding phase for binding grains of said granular material, said microporous ceramic material having thus an maintaining permanently a thermal conductivity lower than 7 W/m.° K.

A high-temperature containment structure includes a roof assembly including at least one layer of refractory material that includes a first layer of refractory material, a plurality of sidewalls, a plurality of pockets disposed in the first layer of ceramic refractory material, each pocket including a retainer that is spaced apart from sides of the pocket by gaps when the roof assembly is at room temperature, an upper plate disposed above the first layer of refractory material, and a first plurality of suspension rods that pass through first holes in the at least one layer of refractory material and the upper plate, wherein the plurality of suspension rods mechanically couple the retainers to the upper plate to retain the at least one layer of refractory material. The structure can use materials with different thermal expansion rates without cracking at elevated temperatures.

A furnace structure includes a roof assembly of at least one layer of refractory material, and a metal plate that covers the at least one layer of refractory material and is configured to dissipate heat from the furnace structure; a plurality of sidewalls fixed to the roof, each of the sidewalls comprising refractory material at an interior surface and a metal wall plate at an outer surface; and a plurality of infrared emitters disposed in an opening in at least one of the refractory material of the sidewalls or the refractory material of the roof.

A furnace structure includes a roof assembly of at least one layer of refractory material, and a metal plate that covers the at least one layer of refractory material and is configured to dissipate heat from the furnace structure; a plurality of sidewalls fixed to the roof, each of the sidewalls comprising refractory material at an interior surface and a metal wall plate at an outer surface; and a plurality of infrared emitters disposed in an opening in at least one of the refractory material of the sidewalls or the refractory material of the roof.

A furnace containment structure includes a roof assembly including at least one layer of refractory material that includes a first layer of refractory material, a plurality of sidewalls, a plurality of pockets disposed in the first layer of ceramic refractory material, each pocket including a retainer that is spaced apart from sides of the pocket by gaps when the roof assembly is at room temperature, an upper plate disposed above the first layer of refractory material, and a first plurality of suspension rods that pass through first holes in the at least one layer of refractory material and the upper plate, wherein the plurality of suspension rods mechanically couple the retainers to the upper plate to retain the at least one layer of refractory material. The structure can use materials with different thermal expansion rates without cracking at elevated temperatures.

Flue gas entry into the tunnel(s) of a furnace is controlled by openings through the entry ports. A furnace tunnel assembly system uses interlocking refractory blocks to form a longitudinal wall of a flue gas flow channel in a firebox. Plugs in some of the ports inhibit flue gas entry from the firebox to the flow channel, and flow passages in some of the ports allow the flue gas to enter the flow channel from the firebox. The flow passages can be provided as inserts having orifices of varying diameter and a profile matching the ports in which they are placed. Matching the flow conductivity (or cross-sectional flow area) and pressure drop through the individual ports to the desired mass flow, the flue gas flow can be distributed evenly, or as otherwise desired, into different ports, intervals, and/or regions of the tunnel.

Flue gas entry into the tunnel(s) of a furnace is controlled by varying the flow conductivity or size of the individual or groups of openings through the entry ports. The openings can be provided either as gaps between adjacent blocks, or through bores of varying diameter, or as inserts having orifices of varying diameter and a profile matching the ports in which they are placed. Matching the flow conductivity (or cross-sectional flow area) and pressure drop through the individual ports to the desired mass flow, the flue gas flow can be distributed evenly, or as otherwise desired, into different ports, intervals, and/or regions of the tunnel.

To enable a carbonized material production kiln to be maintained in a simple manner when an exposed surface on a side wall of the kiln is cracked, to prevent the kiln from easily cracking by heat to thereby prolong the life of the kiln itself, and to increase heat retention efficiency to thereby increase carbonization efficiency even during periods of cold temperatures such as the winter season. The carbonized material production kiln is formed by stacking cubic concrete blocks each having no reinforcing iron so that recombination of up to six faces of each cubic concrete block becomes possible, wherein a heat storage/retention member such as stones is filled in an exhaust space formed between a kiln floor iron plate and a kiln bottom so as to store heat, thereby preventing a decrease in carbonization efficiency even at cold temperatures.

Flue gas entry into the tunnel(s) of a furnace is controlled by varying the flow conductivity or size of the individual or groups of openings through the entry ports. The openings can be provided either as gaps between adjacent blocks, or through bores of varying diameter, or as inserts having orifices of varying diameter and a profile matching the ports in which they are placed. Matching the flow conductivity (or cross-sectional flow area) and pressure drop through the individual ports to the desired mass flow, the flue gas flow can be distributed evenly, or as otherwise desired, into different ports, intervals, and/or regions of the tunnel.