Abstract: Provided is a carbon-fiber-precursor acrylic fiber bundle which can smoothly pass through a flame-resistance impartation step and a carbonization step. The carbon-fiber-precursor acrylic fiber bundle has a high-density part as a portion thereof, wherein the high-density part satisfies the following requirements (A) and (B). Requirement A: The high-density part has a maximum fiber density ?max of 1.33 g/cm3 or higher. Requirement B: The portion extending between an intermediate-density point and a maximum-density-region arrival point has an increase in fiber density of 1.3×10?2 g/cm3 or less per 10 mm of the fiber bundle length. The term “intermediate-density point” means the site which has a density ?m that is intermediate between the fiber density ?o of the non-high-density part and the maximum fiber density ?max. The term “maximum-density-region arrival point” means the site Pr at which the increase in fiber density per 10 mm of the fiber bundle length becomes 1.

Abstract: A sintering furnace with a first zone, in particular a burn-off zone, and a second zone, in particular a sintering zone, and also a transitional zone arranged between the first zone and the second zone. The sintering furnace has at least one transporting mechanism for transporting bodies to be sintered on a transporting area. With this transporting mechanism, the bodies to be sintered can be transported from the first zone and through the transitional zone to the second zone. The sintering furnace also has at least one gas removal device with at least one gas removal device opening. Here, the gas removal device opening is at least partially arranged in the region of the transitional zone. Furthermore, a method by access of which gases can be removed from a sintering furnace is claimed.

Abstract: A method for firing raw ceramic blanks in a furnace includes the steps of guiding trains of blanks running parallel to one another along a longitudinal furnace section having a firing zone, wherein the trains are moved in opposite directions during one movement operation, and the furnace is loaded using blanks to be moved in a first direction. A furnace for firing raw ceramic blanks having a plurality of trains which are arranged parallel to one another and can move along a longitudinal furnace section, so trains comprising a plurality of furnace bogies on which the blanks are to be arranged, wherein the furnace section has a firing zone, and wherein the trains are moved in opposite directions, and the furnace is at a first end of the furnace section for loading the blanks to be moved in a first direction into the furnace.

Abstract: In order to increase energy efficiency in an industrial furnace (1) operated by heating gas and protective gas for thermally treating materials, a first burner (3.1) is actuated for heating with priority over a second burner (3.2), the second burner (3.2) is engaged additionally and operated when the output from the first burner (3.1) falls below the level necessary to heat the industrial furnace (1) up to a temperature setpoint, and the second burner (3.2) is switched off when the temperature setpoint has been reached.

Abstract: A method and system for selecting dental constructions using translucent materials that match an individual's preexisting tooth appearance uses a set of reference templates. The reference templates are constructed from layers of various translucent dental materials positioned on bases constructed from actual or simulated tooth structures. The layers of translucent materials have a thickness that varies in increments that correspond to the likely thicknesses of the materials when used in dental constructions. A reference table is created based upon color measurements of each of the reference templates. A color measurement of the individual's preexisting teeth is then compared to the reference table to determine which particular dental construction will most closely match the individuals preexisting teeth.

Abstract: A fired heater is adapted for increasing the output of a plant where the furnace capacity is considerably improved without corresponding increase in the pressure drop. The described technique utilizes a parallel thermal path in contrast to the conventional series thermal path for heating a hydrocarbon fluid. The fluid is divided into at least two paths where the fluid in the first path is heated primarily by radiation heat transfer mechanism and the fluid in the second path is heated primarily by convection heat transfer mechanism. The at least two fluid streams may then be combined to continue with other desired processing of the fluid.

Abstract: In furnaces for producing high purity fused silica glass boules, glass particles have a tendency to build-up adjacent the burner hole rim. It was discovered that unburned furnace gases containing silica particles where re-circulated in the furnace close to the burner hole rim and reacted with the oxygen of infiltrated air adjacent the burner hole, and thus deposited such particles in the form of a glassy build-up about the rim of the burner hole. In order to eliminate the source of oxygen adjacent the burner hole rim, a curtain of an inert gas is caused to flow through the burner hole between the sidewalls of the burner hole and the flame of the burner. Accordingly, the curtain of inert gas inhibits the combustion of the unburned hydrogen and carbon monoxide furnace gases adjacent the exit rim of the burner hole and thereby minimizes glass build-up about the burner hole rim.

Abstract: An oxygen enrichment system is provided which uses the existing air/fuel burners of a regenerative furnace to distribute additional oxygen to the burners for increased efficiency, and reduced nitrous oxide emissions. The centrally positioned cooling air lances in the burners of a regenerative furnace are modified to deliver oxygen when the burners are firing for oxygen enrichment. During the burmer firing cycle, oxygen is delivered from an oxygen supply through the oxygen lance to provide a central oxygen jet. The fuel is delivered concentrically around the oxygen jet. During the non-firing cycle of the burner, cooling air or other cooling fluid is delivered from the cooling air supply through the oxygen jet for cooling the offside of the furnace.

Abstract: The operation of a combustible atmosphere furnace is controlled by monitoring the temperature of the combustible atmosphere, and the rate-of-change thereof. The measured rate-of-change is compared to a previously determined safe rate-of-change so as to anticipate and discourage incipient internal ignition.

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: A method and apparatus for heating semiconductor wafers characterized by the release of preheated nitrogen into an oven to considerably reduce heating time for the wafers. The oven is evacuated prior to the release of the preheated nitrogen.

Abstract: The method relates to the hardening of form substances made of building materials and containing binding agents in a pressure chamber of an autoclave to which is conveyed a gaseous heating medium, the temperature of which is increased during a heating-up phase up to a given upper limit value. During a holding phase, the temperature is maintained at least until a given equalization temperature is reached on the inside of the form substances. Subsequently, during a cooling-down phase, the temperature is reduced by reducing the pressure to the expulsion temperature. Porous light building materials in a conventional process would absorb a high amount of water through the condensation of water resulting from steam having been conveyed into the autoclave for the purpose of hardening.

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: Method and apparatus for the regulation of the flow of fuel gas in the fuel gas supply duct of a heating wall of a coke oven to assure uniform heat distribution in the oven are provided. The regulating means consists of a thin plate having a similar shape to that of a fuel gas supply duct for insertion therein. Pivotally attached to and extending perpendicularly from the outer face of the plate are twin parallel control rods with gage marks inscribed thereon. To effect the regulation of fuel gas flow, the regulating means is inserted into the fuel gas supply duct at an appropriate location and the flow rate is adjusted by pivoting the plate by the manipulation of the adjusting rods.

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: 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 furnace (100) is provided which aids in the reduction of polysilicon and quartz contaminants during polysilicon deposition on monocrystalline wafers. The wafers are heated for polysilicon deposition within the interior of a quartz tube (102) which is mounted so that the interior sidewalls are vertical and the tube opening is at the top of the furnace. A quartz boat (104) is adapted for carrying the wafers in a spaced apart relationship with a quartz rod (144) maintaining the wafers within the boat when it is suspended vertically from an elevator bar (128). The elevator bar moves the quartz boat vertically into the interior of the quartz tube (102) for heating without contact between the quartz boat and sidewalls of the quartz tube. The level of contamination is therefore less and the yield of certain integrated circuits much improved.

Abstract: A process for firing ceramic bodies, in particular tiles, is disclosed, consisting in conveying the ceramic bodies through an elongated heat treatment chamber, both main faces thereof being freely exposed to heat transmission, simultaneously heating said bodies and the chamber walls by means of a heating fluid, generally combustion gases, the temperature of the portions of the chamber walls which are in view of the ceramic bodies not being higher than that of the heating fluid and controlling the flow of the heating fluid so that its actual volume flow rate, measured axially of the chamber and at the point thereof where the chamber temperature is 900.degree. C., is comprised between 4500 and 12,000, and preferably between 6000 and 10,000 cu.m. per sq.m. of transverse cross-section. Preferably the surface rate of travel of the tiles, when tiles are fired, is comprised between 22 and 30 sq.m. of tile per hour and per linear meter of inner perimeter of the chamber, for 4.5 mm.

Abstract: This disclosure relates to a distinctive construction and method of operating a furnace or oven for controlled atmosphere service whereby substantial savings in heating power or energy are realized. The furnace or oven includes a combination of refractory and insulating materials arranged in a given sequence with respect to their relative gas permeabilities, and at least two gases of discernably different weights are strategically supplied to the furnace or oven at particular locations therein.

Abstract: A process is described for treating metals in a furnace by indirect heating techniques, e.g., by using a radiant tube heater, wherein the gas used for heating is passed out of the furnace, treated in a known manner, and passed back into the furnace to serve as the source for the treating atmosphere or as a carrier gas. Carburization of metals can be carried out by this method which results in a savings in fuel and overall operational expense.

Abstract: Flow control valves are mounted with corresponding axial rows of nozzles about the periphery of a rotary kiln. A metering cylinder is mounted on the kiln and rotates therewith. A piston member is moveable in the metering cylinder in alternately opposite directions to deliver a predetermined measured volume of a liquid hydrocarbon such as fuel oil from said cylinder equally in each direction of movement of said piston member. A first hydraulic circuit interconnects each of said liquid flow control valves with a liquid fuel supply and with one end of said metering cylinder on one side of said piston member, and a second hydraulic circuit interconnects each of said liquid flow control valves with an opposite end of said metering cylinder on an opposite side of said piston member and with a plurality of nozzles in the row of nozzles corresponding to the given flow control valve.

Abstract: An improved atmosphere circulation system involving the use of aspirators for inducing turbulence of pressurized atmosphere within a vessel promotes temperature uniformity within the vessel and, for a given degree of temperature uniformity, reduces energy consumption.

Abstract: A system for heating a furnace having a heating chamber defined by furnace walls is provided with a plurality of individual burner assemblies mounted on a furnace wall to direct heating gas streams into the heating chamber, each of the burner assemblies including a diffusion chamber, a burner arranged to direct products of combustion through the diffusion chamber into a furnace heating chamber and means for directing the flow of diffusion gases into the diffusion chamber to admix with the burner products of combustion so that the gas stream entering the furnace heating chamber has a greater mass velocity than the burner products of combustion, there being provided a diffusion gas supply means connected to the heating chamber of the furnace for delivering hot gases from the furnace heating chamber to the diffusion chambers of each of the burner assemblies.

Abstract: A method and apparatus is disclosed for the cooling of a lime shaft furnace for the calcining of limestone and which is operable with a combustible fuel. In shaft chambers of the shaft furnace, a hollow beam is provided to convey combustible fuel into the shaft chamber. Associated with the hollow beam is a cooling unit for cooling walls of the beam. A closed circuit cooling liquid system connects with the cooling unit so as to maintain a flow of a cooling liquid through the cooling unit. The cooling liquid has a boiling point of greater than 100.degree. C. This cooling liquid is continuously recooled by a heat exchanger.

Abstract: A shell gas burner is provided to preheat a kiln wherein the burner can be also used for process axial air and has provisions for retracting the burner for protection from high heat source or extending the burner for ease of replacement.

Abstract: Device for removing carbonizable residues includes a closed furnace heatable to low-level carbonization temperature, the furnace having an outlet for carbonization gases formed therein, means for burning off carbonization gases from carbonizable residues and utilizing the heat of combustion therefrom for heating the furnace, the means comprising a burner and a combustion chamber connected to the burner and forming part of a hot gas circulatory system, the hot gas circulatory system also including a container wherein the furnace is disposed so as to be heatable by hot gas circulating through the hot gas circulatory system, a carbonization gas return line connecting the furnace and the combustion chamber for returning to the combustion chamber carbonization gases formed in the furnace, and an inert gas line communicating with the interior of the furnace for supplying inert gas thereto.

Abstract: Method for maintaining preheating equipment used for heating coal at a temperature within a temperature range normally used for heating said coal in said equipment which comprises introducing into said equipment a heat-absorbing liquid at a rate sufficient to maintain said equipment within said temperature range. Typically, the heat-absorbing liquid is an aqueous solution, preferably water, and said temperature range for preheating said coal is from 250.degree. to 700.degree. F.

Abstract: In the calcination of petroleum coke in a rotary kiln, procedure wherein air is controllably supplied internally of the kiln to burn the removed volatiles, as by selection or adjustment of the amount of such air and of the speed of coke travel down the kiln, so that all or nearly all of the heat for calcining the coke is provided by such combustion, and so that a suitably high temperature is reached for effective calcination at an efficiently large feed rate of coke, a special feature being to maintain a significantly long travel time of the coke from a region of intense calcining activity to the product discharge end of the kiln. High production rates, of coke calcined well and uniformly, are economically attained, with ease of control and with unusual stability of kiln operation.