Abstract: Apparatus and operating methods are provided for controlled atmosphere furnace systems. In one possible embodiment, hydrogen is injected from a hydrogen source to an enclosure. The hydrogen is circulated within the enclosure from a gas inlet to a gas outlet. A temperature is raised within the enclosure to a predetermined threshold. Hydrogen is pumped from the gas outlet to the gas inlet with an electrochemical hydrogen pump. The electrochemical hydrogen pump has a first electrode in fluid communication with the gas outlet, and a second electrode in fluid communication with the gas inlet. An electrical potential is provided between the first and second electrodes, wherein the first electrode has a higher electrical potential with respect to zero than the second electrode. Various methods, features and system configurations are discussed.

Abstract: The invention relates to a method for annealing or hardening of a metal or an alloy in a controlled furnace atmosphere, wherein said furnace atmosphere is a hydrogen-free atmosphere comprising nitrogen and carbon monoxide.

Abstract: A to-be-burned object including a metal Si component or SiC or Si3N4 can be burned in such a manner that vaporized SiO can be safely exhausted without causing SiO attached to a wall of a furnace or an inner face of an exhaust duct. An exhaust method of a continuous furnace for continuously burning a to-be-burned object containing a metal Si component or highly-fire-resistant SiC or Si3N4 includes steps of 1) exhausting in-furnace gas including SiO vaporized during a burning process. An exhaust duct 2 used for this exhaust is provided at an upper part of a side wall 12 of the furnace having a higher temperature (1300 degrees C. or more) than a concentration temperature of SiO vaporized during a burning process. 2) oxidizing the exhausted SiO at the outside of the furnace to detoxify SiO. The in-furnace gas exhausted by the exhaust duct 2 is guided to an exhaust pipe 3 connected to an outlet of the exhaust duct 2 at the outside of the furnace. This exhaust pipe 3 includes oxygen supply holes 31a and 31b.

Abstract: This invention is directed to a method for carrying out combustion in a furnace having porous walls with a large surface area in a combustion zone in which a low velocity oxidant stream is injected through at least one oxidant injection side of the porous walls into the combustion zone, a fuel stream through at least fuel injection side directed toward the oxidant injection side and mixing the low velocity oxidant and fuel stream to create a flame with reduced flame temperature.

Abstract: A parts container for minimizing oxidation of heat-treated parts during transfer in an oxygen-containing environment. The container includes: a heat-resistant vessel having an interior space and including oppositely positioned first and second apertures; a heat-resistant, porous support element fluidly connected to the first aperture to provide a bottom to for the vessel; and a disposed in the interior space a plurality of fluidizable granular solids and at least one heat-treatment part. The fluidizable granular solids provide a transient protective environment for the parts after heat treatment thereby minimizing exposure of the parts to oxygen in the surrounding environment. Additional embodiments and methods of use are also described.

Abstract: This invention is directed to a method for carrying out combustion in a furnace having porous walls with a large surface area comprising providing a combustion zone containing an atmosphere of furnace gases. A low velocity oxidant stream is injected through at least one oxidant injection side of the porous walls into the combustion zone and mixing furnace gases with the oxidant stream in a mixing zone within the combustion zone to produce an oxidant mixture. A fuel stream is injected through at least one fuel injection side adjacent to the oxidant injection side in the combustion zone. The oxidant mixture is mixed with the fuel stream to create a fuel-oxidant mixture.

Abstract: A closed-loop control system controls introduction of either water or hydrogen into a furnace region where a part is subjected to an elevated temperature to accomplish a heat treatment process. The heat treatment process causes the part to participate in reduction and/or oxidation reactions which remain in balance at the elevated temperature so long as a hydrogen/water ratio set point is maintained. The system includes an oxygen probe in communication with the furnace region for providing (i) an oxygen output indicative of sensed oxygen concentration within furnace region, and (ii) a temperature output indicative of temperature therein. A controller determines from the oxygen output and temperature output, a measured ratio of hydrogen to water within the furnace region and compares the measured ratio with the hydrogen/water ratio set point, and provides a correction signal output in accordance with a determined difference between the measured ratio and the ratio set point.

Abstract: A direct-fired furnace wherein a charge-proximal stratum is established between the charge and combustion gases emanating from one or more or burners oriented above the charge, wherein the charge-proximal stratum has a different oxidative effect upon the charge than does the combustion gases.

Abstract: Aluminum or aluminum alloys are brazed in the presence of a non-corrosive flux using a low-cost, substantially dry nitrogen atmosphere produced by a non-cryogenic air separation technique such as a pressure swing adsorption (PSA) or a selective permeation (membrane). The use of a substantially dry, non-cryogenically produced nitrogen atmosphere brazed aluminum or aluminum alloy components with consistent good brazed joint quality and appearance while utilizing low loading of the flux.

Abstract: A system for use in sensing the oxygen content of an industrial furnace gas typically containing hydrocarbons or hydrogen is disclosed. The system utilizes a conventional automotive EGR oxygen sensor probe positioned in an especially configured housing employing downstream flow regulating means in combination with an orificing plate in the housing to provide uniform distribution of the endothermic gas at a low temperature about the sensor to insure accurate sensor readings with minimal carbon deposition. The electrical contacts at the oxygen sensor's inner and outer electrolyte surfaces are periodically switched to an electrical power supply to cause current to flow through and heat the electrolyte to elevated temperatures while air is flowed over the electrolyte's surfaces to achieve burn out of any carbon deposits and restore the life of the oxygen sensor probe.

Abstract: A method for circulating a gas in an autoclave which comprises a pressure container (A) having a wind tunnel (7) in which moldable materials (1) are placed and the gas is circulated by a blow fan (33), the pressure container (A) being sealably closed by a door, the layers of each of the materials (1) are compressed, heated, adhered together, and set in the pressure container (A) producing swirling of the gas coming out of an outer duct formed between the inner face Aa of the pressure container (A) and the wind tunnel (7) by guide blades (H), diverting the gas at the inner face (2a) of the door (2), and directing the diverted gas to flow through the inside (7b) of the wind tunnel (7) with the swirl. The apparatus for circulating gas has guide blades (H) for swirling the gas going out of the outer duct (7a) provided in the outer duct, whereby the gas is diverted at the inner face (2a) of the door (2), and is directed to flow through the inside (7b) of the wind tunnel (7) with the swirl.

Abstract: A test oven wherein heated air having a predetermined temperature is supplied and the oxygen concentration in the supplied air is controlled. The test oven has a test oven body having an air supply port and an air discharge port, a blower connected to the air supply port for blowing air thereinto, an oxygen concentration detector connected to the test oven body, an oxygen concentration setting control unit connected to the oxygen concentration detecting detector and including an oxygen concentration setter for setting a desired level of oxygen, and an oxygen concentration controller constantly comparing a reference output level generated on the basis of a concentration level set in advance in the oxygen concentration setter with an output level outputted from the oxygen concentration detector and for controling the actual output level to a set level, and at least one oxygen concentration adjusting device.

Abstract: A method and apparatus for vacuum purging bell type furnaces is provided. A vacuum shell unit is provided which is removably emplacible over the inner cover of the furnce and has a vacuum tight seal to the base. A vacuum is pulled both within the inner cover and within the vacuum shell to remove the ambient gas. Nitrogen is then introduced into the inner cover and within the vacuum shell. The vacuum shell is then removed and purging continues within the inner cover either with nitrogen or other desired atmosphere gas, and finally furnace is emplaced over the inner cover to heat treat the work in a conventional manner.

Abstract: Reversing the flow of conventional furnace/retort systems prevents damaging exhaust gases from entering the furnace while still maintaining a gas flow through the retort. The gases exit the retort into a treatment system; preventing contamination of any apparatus and the escape of any hazardous gases.

Abstract: The present invention provides a method and apparatus for controlling the fluid flow bias of continuous, multiple zone processes having gas or vapor comprising atmospheres that are in immediate access to each other. Active control of the fluid flow bias in at least one process zone or control of the overall process fluid flow bias is achieved by applying force to at least one of the zones of the process in a manner which enables such control. A physical or chemical property or a change thereof in at least one process atmosphere is monitored and an appropriate amount of force is applied in response to the monitored property. The monitored property is related to the furnace flow bias by an algorithm, so that the flow bias can be controlled by controlling the at least one chemical or physical property monitored.

Abstract: A vapor processing system which has a vessel for containing a processing vapor generated by heating electronic fluid contained within the vessel. A selected saturated vapor zone level is devined for work product delivered to the vapor zone by generating a signal representative of the actual temperature at one of a plurality of spaced locations within the vessel, generating a signal representative of the desired temperature at the selected location for a saturated vapor zone having a level selected for the work product being conveyed to the saturated vapor zone, and comparing the signals representative of the actual and desired temperatures at the selected location and for varying the output of the heater to change the actual sensed temperature to the desired temperature so that the actual saturated vapor zone level will conform to the desired saturated vapor zone level.

Abstract: An apparatus for heat treating a work item includes a cover member and a base member on which the cover member is supported. A work space is defined between the base member and the cover member for receiving at least one work item which is positioned therein. A seal member is located between the base member and the cover member for sealing the work space against the entry and exit of gas. A valving system is provided for regulating the entrance and exit of a gas to and from the work space. The valving system is in fluid communication with the work space and includes a relief valve member for allowing the exhaust of the gas from the work space when gas pressure therein exceeds a predetermined limit.

Abstract: A method of operating a controlled atmosphere furnace. To prevent the entry of oxygen into the controlled atmosphere in the chamber of the furnace, which has a furnace door for the receipt and removal of parts by means of a feeding and removal device, the device is designed to seal a vestibule located immediately in front of the furnace door when the device approaches the furnace door. The oxygen-containing ambient air thus trapped in the vestibule is then removed therefrom. The furnace door is opened, and the feeding and removal device, while still sealing the vestibule from the ambient air, then moves into the furnace chamber for feeding or removing the part which is to be heat treated.

Abstract: In a process of heating and cooling charges in batch-process industrial furnaces, particularly in a process of cooling coils of steel wire or strip steel in bell-type annealing furnaces, the charge is heated and cooled in contact with circulated protective gas. The cooling time is shortened and the power input to the circulating fan is reduced by changing the composition of the protective gas so as to decrease the specific gravity of the protective gas just before the beginning of the cooling period and/or during the cooling period.

Abstract: The volume of atmosphere needed to inhibit the ingress of ambient oxygen into the furnace chamber (3) of a continuous heat treatment furnace (1) can be reduced by introducing a gas containing free oxygen (e.g. air) into the entrance section (2) and/or exit section (4) adjacent the roof thereof. Thus a relatively inexpensive gas may often be used in combination with an expensive atmosphere thereby significantly reducing overall process cost. Continuous heat treatment furnaces can readily be converted to perform the method by simply inserting adjacent the roof of the entrance and/or exit section a tube (3) having a slot and/or a plurality of downwardly facing holes (9) and connecting the tube to a supply of the requisite gas. The invention is applicable to both double open ended furnaces and continuous furnaces in which the exit section is filled with a liquid, e.g. oil or molten salt. In these latter cases the gas is introduced in the entrance section (2).

Abstract: A continuous heat treatment furnace has an entrance, a preheat zone, a thermal treatment zone, a cooling zone and an exit. Curtains are provided at the entrance and exit respectively. Nitrogen and hydrogen (or other reducing gas) are supplied to the furnace to create a non-oxidizing or reducing atmosphere in the thermal treatment and cooling zones. Elongate workpieces such as tubes are advanced through the furnace and thereby heat treated (e.g. annealed). As the workpieces pass through the curtains so the tendency for air to leak into the furnace is increased. To counteract this tendency, position sensing plates are adapted to actuate a signal generator controlling a valve which in turn controls flow of e.g. nitrogen to the furnace. The arrangement is such that the flow of nitrogen to the furnace is increased wherever a workpiece is sensed, thereby enabling the essentially reducing or non-oxidizing character of the atmosphere to be sustained.

Abstract: A cantilever diffusion tube apparatus includes a quartz cantilever tube having a support end clamped to a laterally movable carriage mechanism and an outer end portion containing a plurality of spaced semiconductor wafers. The cantilever tube is coaxially aligned with a diffusion tube of a diffusion furnace. The support end of the cantilever tube is sealed by a door plate through which a gas tube extends. The wafers are loaded into the cantilever tube through a window opening. The carriage then moves the cantilever tube and wafers therein into the diffusion tube. Reactant gases are caused to flow into the cantilever tube, between the heated wafers therein, and out of the cantilever tube. Then purging gas is caused to flow through the cantilever tube and wafers therein.

Abstract: An improved semiconductor wafer handling system completely eliminates the need for boats, sleds, paddles, wheeled carriers, etc., customarily employed in transporting wafers during heat processing through the use of a plurality of rigid, polished cantilevered rods having a multiplicity of spaced slots for cooperatively holding wafers in an upright position. The system provides a means for achieving higher production yields of such semiconductor elements by generating fewer contaminating particles and through less exposure to ambient environment.

Abstract: A process for reducing the oxygen content of the atmosphere in a heat treatment furnace for ceramic materials to a prescribed value comprises measuring the O.sub.2 content of the furnace atmosphere at the point in the furnace to be affected and introducing fuel gas into the furnace as a function of the measurement result in such quantities that the desired oxygen content is attained. Also described is a furnace design suitable for carrying out this process.

Abstract: For producing uneven coloring on firing plate-like ceramic material such as tiles or flags in a kiln, more specially a roller kiln, made up of preheating, firing and cooling zones, and through whose oxidizing atmosphere in the firing zone the material to be fired is moved in a single layer without burning tools for supporting it, in or at the end of the firing zone, in a screened-off part of the kiln, the material to be fired is acted upon by a partly reducing atmosphere. In this respect the material to be fired may be passed at this position through a reducing zone and then through a pulsating oxidation zone. It is however possible as well for the material to be fired to be moved through a reducing zone and then purposefully acted upon by blowing with a strongly oxidizing gas. A further possible way of undertaking the process is such that in or at the end of the firing zone the material to be fired is moved in a pulsating reducing zone.

Abstract: A heat treat furnace wherein the furnace top and side walls are each defined by an outer, gas-tight metallic structural wall, an intermediate perforate metal plate generally parallel to and coextensive with the exterior wall to define a plenum chamber therebetween, and an inner layer of non-metallic, gas permeable insulation, preferably a blanket insulation of appreciable thickness. The gaseous atmosphere of the furnace is injected into the plenum chambers defined between the exterior walls and the perforate plates, and the atmosphere passes through the insulation layer into the interior of the furnace. The inward flow of atmospheric gas (1) replenishes the atmosphere in the furnace, (2) preheats the atmosphere, and (3) reduces any heat loss through the wall structure.

Abstract: A condensation soldering facility (10) comprised of a housing (12) having a divider member (22) therein which separates the housing into a drying chamber (24) in an upper section and a soldering chamber (26) in a lower section. A transfer member (76) is pivotably mounted within the drying chamber (24) to receive articles (112--112) to be soldered through an access door (71) in the top of the drying chamber (24) and arcuately transfer the articles through an access door (44) in the divider member (22) to solder the articles in the soldering chamber (26).

Abstract: The characteristic feature of the herein disclosed method resides in that it involves a zone control over temperature and humidity of articles being treated within the space of a tunnel chamber, the articles being blown with an air agent having a temperature of 40.degree.-100.degree. C. prior to the step of temperature increase whereas in the zone of said temperature increase the articles are treated with a steam-air mixture for a period of 1-6 hours, the temperatures and humidity of the mixture being gradually increased to their permissible values corresponding to the given type of articles being treated; in so doing the articles in the isothermal curing zone are affected for a period of 2-6 hours with a heat-carrying agent having a temperature of 60.degree.-95.degree. C. and a relative humidity close to 100% while in the cooling zone the articles are blown with a cooling agent having a relative humidity of 35-90% for a period of 0.3-1.5 hours.

Abstract: A method of operating a continuous heat treatment furnace for metal strip coils includes steps of enclosing them in muffles in the furnace supplied with an atmosphere gas containing a combustible gas such as hydrogen and feeding the muffles into and through the furnace having therein heating, soaking and cooling zones. According to the disclosed method, at least part of the heating and soaking zones is heated by direct firing heating with a fluid fuel with excess air and combustible gas leaked from the muffles into the furnace is burnt in the furnace with the aid of the excess air. Combustible gas leaked from the muffles into the cooling zone is diluted with air forced into the cooling zone to make the combustible gas incombustible and thereafter to exhaust it out of the furnace, thereby eliminating ignition means for the combustible gas in the furnace and particular precaution for preventing an ignition failure.

Abstract: Apparatus is described that is particularly adapted for suppressing fume generated in the flow of molten metal through the runner system of a blast furnace cast house. Burners adapted for combusting fuel and air are disposed at longitudinally spaced locations along the runner system. Fuel and air in predetermined amounts are discharged from the burners to create flame and disperse it along the axis of the runners. The flame operates to consume ambient air in the combustion process thereby to starve the region over the metal streams of oxygen that would otherwise combine with metal vapors to create fume-producing metallic oxides.

Abstract: A method of operating a continuous ceramic kiln having a decarbonization zone characterized in that oxygen or oxygen enriched air is added to the decarbonization zone to maintain the average oxygen concentration in the decarbonization zone at or about a predetermined level. The predetermined level need only be adjusted for different throughputs and need not be adjusted for moderate changes in the amount of organic matter in the clay.

Abstract: A continuous electric tunnel furnace includes a tunnel through which articles to be fired are passed in a direction of feed. The tunnel has a length portion constituting a sintering zone. Nitrogen is introduced into the tunnel at the outlet thereof. The nitrogen stream is oriented against the direction of feed. There is further provided a gate projecting from the tunnel roof into the tunnel in the sintering zone in an orientation transverse to the direction of feed. The gate has opposite lateral bounding edges which are spaced from respective side walls of the tunnel.

Abstract: A hole through each of opposed walls of a combustion chamber of a glass melting apparatus and piping interconnect the chamber atmosphere to an oxygen analyzer. A sample of the chamber atmosphere is continuously moved through each of the holes and piping to the analyzer by the biasing action of the positive pressure differential between the chamber atmosphere and the ambient atmosphere.

Abstract: The rate of calcining carbonaceous material in a rotary kiln is increased by introducing oxygen into the inlet of air fans mounted on the kiln. The introduction of oxygen is effected during a predetermined portion of each kiln revolution and is effective to enrich the oxygen content of air supplied to the kiln to approximately 23-25% oxygen. By so enriching the interior kiln atmosphere during calcining of material such as petroleum coke, greater temperatures are obtained than will be obtained by the use of air alone thereby accelerating the evolution and combustion of volatile materials during calcination. The accelerated evolution and combustion of such volatiles enables the rate at which carbonaceous materials can be calcined in a kiln of a predetermined length to be increased.

Abstract: In the manufacture of clay or refractory ware containing oxidizable material, stacks of the ware are passed through a tunnel kiln and a flow of air passed over the stacks. Fuel burners are operated to provide the necessary stages for firing the ware. These stages include an oxidation stage in which residual oxidizable material is oxidized. Gas containing more oxygen than air (i.e. commercially pure oxygen or oxygen-enriched air) is introduced into the region of the kiln where the oxidation takes place. The oxygen-rich gas is caused to penetrate at least one stack for the time being in the oxidation region so as to increase the concentration of oxygen throughout the individual items of ware within said stack. It is thus possible to oxidize all the residual oxidizable material. At least 50% of such oxidation is typically confined to a temperature range of 100.degree. C. The heat thereby released assists in the firing of the ware.

Abstract: A method and apparatus for condensation heating. Articles to be heated are conveyed into a heating chamber which is filled with vapors of a fluid having a relatively high boiling point. When the vapors contact the article to be heated they condense thereon and transfer the latent heat of vaporization, thus heating the object. Vapors escaping from the heating chamber are trapped by flows of carrier gas at the inlet and outlet of the heating chamber. The carrier gas, which is thus partially saturated with vapor, is channeled into a gas/vapor separator wherein the vapor is extracted and recycled back to the heating chamber.

Abstract: The present invention is an improved apparatus and method for directly heat treating articles in a sealed treatment chamber of the heat treatment furnace. A burner means fires into a precombustion chamber which is connected in communication with the treatment chamber. Combustion is completed in the precombustion chamber and the products of combustion are fed into the treatment chamber. Additional treatment gas such as an endothermic gas is fed directly into the furnace treatment chamber.

Abstract: A process and apparatus are disclosed for controlling losses in volatile working fluid systems. In accordance with the process, the object upon which a work operation is to be effected is sequentially moved from a first sealable chamber to a second such chamber and back to the first chamber. While in the second chamber the object is exposed to a working fluid vapor which elevates the temperature of the object to a level near the boiling point of the working fluid. Thereafter, while still in the second chamber, a substantial portion of the working fluid is drained from the object such that the sensible heat acquired by the object upon its elevation of temperature is sufficient to evaporate working fluid remaining on the object upon its removal to the first chamber. Upon removal of the object to the first chamber the object is thoroughly dried through control of the partial pressure of the working fluid vapor contained within the first chamber atmosphere.

Abstract: A high efficiency system and method for supplying heat energy to a combustible effluent producing primary process, such as to a paint drying oven, in which the output of an incinerator-heater is controlled in order to be matched to the heat energy requirements of the process. At the same time, the incinerator burner temperature is sufficiently high to incinerate the combustible effluent developed by the primary process. Effluent laden air is circulated from the process site through a preheat heat exchanger into which is transferred a portion of the heat of the incinerated air prior to entry into the incinerator chamber. The incinerated air is recirculated to the process site in order to provide the heat energy requirements of the drying oven or other process. A proportion of the incinerated air is vented to an exhaust stack via an air-to-air heat exchanger which preheats incoming fresh air circulated to the process site to make up the vented flow of incinerated air.

Abstract: Individual charges of silicon steel are passed through a tunnel type furnace provided with charge and discharge vestibules. The annealing takes place in a hydrogen atmosphere and the vestibules are purged with nitrogen and then with hydrogen. The hydrogen used for purging is taken from the hydrogen in the annealing atmosphere and additional new hydrogen is added to the annealing atmosphere at the same time to maintain the pressure constant.

Abstract: An electric kiln for firing ceramic ware in a reducing atmosphere has a substantially sealed chamber with electrical-resistance heating elements. A compartment is provided within the kiln for selectively introducing a reducing agent into the chamber. According to the method, the temperature within the chamber is raised to a predetermined level by energizing the heating elements. Upon attainment of the desired temperature level, a selected quantity of the reducing agent is introduced into the chamber for producing a reducing atmosphere during the maturing of the ceramic ware. As the temperature is raised to a level at which the heating elements would be damaged, a substantially neutral atomsphere is maintained in the chamber. Aslo during cooling, a reducing atmosphere is possible for further reduction of the ware and glazes thereon.

Abstract: The cooking process comprises the steps of providing a food treatment chamber equipped with a vapor pervious conveyor; preparing a moving stream of a process vapor at a temperature having a lower range of between 165.degree. F. to 212.degree. F.; circulating the stream along the conveyor; injecting water vapor into the moving stream of process vapor and supplying heat to the moving stream to control the temperature and moisture content of the process vapor; placing the food product in discrete pieces upon the conveyor; and moving the product continuously in its original position on the conveyor through the treatment chamber.

Abstract: Method and apparatus for feeding an oxidant such as air and/or a fuel rich gas within the confines of a substantially air tight enclosure employed in the heat treatment of volatile containing materials which are deposited on the floor of a rotary hearth mounted within the enclosure. A larger number of air and/or fuel rich gas inlet ports are provided in the roof of the enclosure at the outer periphery thereof than at the central or intermediate areas of the enclosure to thus provide a more oxidizing atmosphere at the outer peripheral area of the enclosure than at the central and intermediate areas of the enclosure. The oxidant is admitted into the furnace enclosure through concentrically arranged rows of inlet openings formed in the roof of the enclosure.

Abstract: A scrap preheating system of the type employing a conveyor upon which the scrap is placed, an elongate burner hood surrounding the conveyor and burners within the hood which direct flames upon the scrap. The side walls of the burner hood include an elongate exhaust chamber and side wall ports between the exhaust chamber and the interior of the hood. An exhaust fan induces a negative pressure under the hood through the exhaust chambers which pulls the unburned hydrocarbons from under the hood through the side wall ports into the exhaust chamber. Additionally, air is drawn upwardly between the conveyor and side walls of the hood and through the side wall ports into the exhaust chambers wherein combustion is completed and pollution reduced. The length of hood and burner array exceeds the length of scrap material on the conveyor. The conveyor is periodically jogged during the preheating cycle to slightly advance and mix the scrap and only those burners positioned above the scrap are operated as it advances.

Abstract: Carbon fibers are produced by continuously heat-treating acrylonitrile fibers up to the crystal collapse starting temperature of said fibers while maintaining said fibers under a fixed length or tension in an oxidizing atmosphere, then sufficiently thermally stabilizing fibers by further subsequently continuously heat-treating them in a temperature range gradually elevated up to a fixed temperature in a range of from a temperature about 20.degree. C lower than the deterioration starting temperature of said fibers to a temperature about 20.degree. C higher than said deterioration starting temperature in an oxidizing atmosphere. The thus sufficiently thermally stabilized fibers are treated with a reducing liquid and subsequently carbonized or graphitized in a non-oxidizing atmosphere or under a vacuum.

Abstract: A process for continuous annealing silicon containing sheet steel whereby furnace roll pickup marks are eliminated, said process involving the use of furnace rolls having a silica peripheral surface and maintaining an annealing atmosphere containing hydrogen to water at a ratio of at least 5:1.

Abstract: A system for controlling the operation of a multiple hearth furnace over a diverse range of operating conditions at a minimum level of energy consumption. Relatively low temperature gases are controllably recirculated from the drying zone to the combustion zone of the furnace, and/or gases are controllably discharged from the combustion zone and/or drying zone to regulate drying zone temperature, combustion zone temperature and the quantity of excess air required to provide optimum furnace operating conditions. The system is particularly useful for controlling the incineration in a multiple hearth furnace of sludge from waste water treatment plants.

Abstract: A heated furnace for sintering structures of uranium oxide containing composition being introduced to the furnace. The furnace receives an atmosphere comprising a mixture of hydrogen and carbon dioxide as initially introduced to the furnace, and this mixture reacts in the furnace to give the presence of water vapor and carbon monoxide.