Abstract: An improved air delivery system is provided for an impingement food preparation oven including a plurality of air ducts disposed in a cooking chamber, a plenum connected to the air ducts, and a scoop-type fan disposed in a backwall opening of the plenum to provide a flow of heated air smoothly and uniformly through the plenum into the air ducts. The fan device includes a plurality of tear-drop shaped blades, wherein each blade has a leading edge portion that tapers to a point in the direction of rotation and a trailing row portion at a given pitch angle for forcibly moving the flow of air in an axial direction toward the plenum front wall. The plenum front wall has a plurality of openings connected to the duct members, and a centrally disposed conical surface projecting outwardly toward the fan so that the axially directed flow of heated air from the fan is smoothly and uniformly directed by the conical surface the plurality of air ducts so as to provide a uniform cooking temperature in the cooking chamber.

Abstract: An improved ingot pusher furnace having a base carrying a plurality of laterally slidable shoes with upper surfaces smoothly tapering into said base. A pair of side walls is connected to said base with a top wall connected to said side walls to define a heating enclosure. A pair of end walls are connected to the base, side walls and top walls, each of the end walls having a vestibule, including a pair of double doors therein. A baffle assembly is movably connected to the top wall to be held in spaced proximity from an ingot to be heated.

Abstract: A roller conveyor furnace (12) is disclosed as including at least one gas jet pump (24) for providing forced convection heating of glass sheets during conveyance on rolls (22) of the furnace conveyor (20). A source (26) of compressed gas located externally of the furnace is communicated with the gas jet pump to supply a primary gas flow thereto and induce an amplified extent of a secondary gas flow in order to provide a combined flow of heated gas that produces the forced convection heating. Upper and lower arrays (70,72) of the gas jet pumps are disclosed as being usable separately or in cooperation with each other in one embodiment to maintain temperature uniformity and glass shet planarity. Each array includes an associated conduit support (74,76) that mounts the gas jet pumps thereof in a spaced relationship transverse to the direction of conveyance either above or below the conveyor rolls.

Abstract: The ceramic roller-hearth kiln is divided into three zones, of which the first and last are utilized for the initial heating and the cooling of the material respectively, and the central zone, which is provided with combustion means and utilized for high-temperature firing, comprises a conduit for the forced counter-current suction of the gaseous products of combustion between said second and said first zone, from said conduit there branching two ducts for the feed and recovery of part of the hot gas to and from the first zone; the cooling zone being constituted by three successive sections comprising, respectively, direct cooling by blowing air on to the material, cooling by induction and cooling by forced ventilation, the hot air recovered from said cooling zones being fed to the head of the kiln, to flow into said forced suction conduit.

Abstract: The process treats a continuous stream of containers of solid material effecting melting or heating of the material within the package. The dwell time within the process is minimized while at the same time the maximum temperature achieved by any of the material is held within an allowable maximum.

Abstract: A paint bake oven (10) including an outer insulated housing (12), the outer insulated housing having an inner wall surface (14). An inner housing (16) is disposed within the outer housing (12) and has an outer wall surface (18) spaced from the inner wall surface (14) to define a gas flow channel (20) therebetween. The inner housing (16) has an inner product passageway (22). A gas supply plenum (46) is disposed above the inner housings for supplying a gas flow to the gas flow channel (20). A gas exhaust passageway (38) exhausts gas from the product passageway (22). The oven (10) is characterized by including a manifold wall (28) for directing the gas flow along a flow path from the gas supply plenum (46) downwardly along the inner wall surface (20) of the outer housing (12) and then upwardly over the outer surface (18) of the inner housing (16) to uniformly distribute the gas flow over the inner housing (16).

Abstract: Manufacturing of carbon bodies by heating blanks containing pyrolizable substances in a chamber over in which volatile pyrolysis products are formed and decomposed and thermal energy is generated by combustion of fluid fuels inside the chamber. Below a chamber temperature of 600.degree. C. the fuel is burned by supplying a stoichiometric amount of air, and above a chamber temperature of 600.degree. C. an additional quantity of air is blown into the chamber through nozzles.

Abstract: An oven for preparing food comprising an enclosure having a conveyor received therethrough for conveying food to be prepared through the enclosure. Positioned within the enclosure and about the conveyor portion therein are duct devices for impinging heated air against the food product, a plenum adapted to the duct devices for supplying heated air to the duct devices, and an impeller assembly for recirculating the air within the enclosure for reheating and subsequent passage to the plenum and duct devices. A heating source is provided within a heating chamber on the opposite side of the plenum from the duct devices, and control components are provided for regulating the temperature of the heat source. The impeller assembly and the plenum are unique in that air drawn from the heating chamber by the impeller assembly is axially and radially urged into the plenum for substantially uniform distribution to the duct devices communicating with the plenum.

Abstract: A conveyorized, electrically heated oven provides controlled top and bottom heating for pizza or other food products. Cooking is accomplished in two ways. The top of the food is cooked with heated air circulated within the oven, while the bottom of the food is heated by electric heating elements located between live conveyor rolls. Heated air within the oven is recirculated. In the preferred embodiment of the invention, two parallel conveyor lines are provided, with controls to permit use of one or both lines. Because of the heat recirculation system, the oven does not require a heat vent and energy consumption is reduced.

Abstract: A method and apparatus for automatically controlling a carbon bake furnace to thereby reduce uniformly baked anodes is disclosed. In its method aspects, the invention contemplates the use of flue and pit temperatures to produce a control signal to operate a valve for varying the air fuel mixture of a burner associated with said valve. In its apparatus aspects, the invention utilizes a plurality of infrared detectors to measure the pit and flue temperatures. The signals produced by these sensors are fed to a computer which produces a control signal for operating a valve associated with at least one of a plurality of burners which is to have its air/fuel ratio adjusted to thus adjust the temperature in the pit heated by the selected burner to a desired target temperature.

Abstract: A fruit dryer comprising a roller conveyor passing through an elongate drying chamber is disclosed. An air plenum having a plurality of transverse nozzle openings is disposed above the conveyor and directs a series of curtain-like air streams on the fruit below. The major portion of the air within the dryer is recycled by a fan while a smaller portion of said air is exhausted by a second fan. A heater heats both the recycled air and fresh air introduced as make-up for the exhausted air. A means is provided to rotate the individual rollers of the roller conveyor as the conveyor is advanced in order to expose all sides of the fruit to the air streams.

Abstract: Flat articles, in particular printed circuit boards, coated with a curable material, repose at their edges upon two belt conveyors which are positioned at an inclination. By means of these belt or band conveyors, the printed circuit boards are fed, in a predetermined conveying direction, below a heating device containing at least one hot air infeed device. The surface or face of the printed circuit board confronting such hot air infeed device is therefore subjected to the action of the hot or heated air, resulting in curing or hardening of the applied material layer. At the opposite side of the printed circuit board, facing away from the hot air infeed device, there is arranged a collecting tube or pipe which extends in the conveying direction. This collecting tube is provided with outlet openings for cooling air. Hence, the lower face of the printed circuit board has applied thereto the cooling air.

Abstract: A roller tunnel kiln for firing a drying refractory material advanced along the refractory rotatable rollers includes an upper section comprising a prefiring zone, a firing zone, a first forced cooling zone, a natural cooling zone and a second forced cooling zone. Parallel to the upper section along the length thereof a drying zone is arranged provided with refractory rotatable rollers for advancing movement of the material to be dried. A distributional tunnel is mounted parallel to the drying zone and is connected with the prekiln zone or with the forced cooling zone so that hot gases mixed with cool ambient air are directed into the distributing tunnel provided with openings communicating the latter with the drying zone. The hot gases at drying temperatures are further directed into drying tunnel in the direction opposite to that of the material to be dried.

Abstract: A method of producing carbon fiber by making infusible and carbonizing pitch fiber which is obtained by melt-spinning petroleum-tar pitch or coal-tar pitch, and a method of making pitch fiber infusible in an air atmosphere containing NO.sub.2, at an elevated temperature by introducing a cross-sectionally U-shaped tray with pitch fiber suspended from bars placed across an upper portion thereof into an infusible material producing furnace having gas exchanging chambers in the inlet portion and outlet portion thereof as well as at least two gas circulating means each of which comprises a combination of a blower or a fan and a heat exchanger, and retaining said tray in said furnace.

Abstract: During the process in which a metal strip is moved in a floating condition, the metal strip is first heated, and thereafter cooled and annealed. In heating the metal strip, the metal strip is heated so that a central portion widthwise thereof is increased in temperature more than that of both edges widthwise thereof. The metal strip is heated in a manner as described whereby a great thermal stress is not introduced in the metal strip and consequently, there is less possibility to produce wrinkles in the metal strip.

Abstract: The present invention relates to a method of and an apparatus for controlling the combustibility of volatile hydrocarbons and particulate matter in an exhaust gas stream driven off from a carbon product being baked in a furnace. In a prebaking stage, the carbon product is heat treated in a temperature range of 300.degree. C. to 600.degree. C. in order to drive off the volatile hydrocarbons and particulate matter and form the exhaust gas stream. The exhaust gas stream is heated to a temperature of at least 900.degree. C. and at least one heat transfer medium is force-drafted and mixed into the exhaust gas stream so that the stream contains at least approximately 6% oxygen. The volatile hydrocarbons and particulate matter in the exhaust gas stream are combusted into non-polluting compounds having an opacity less than 40% for exhaustion from the furnace into the outside atmosphere.

Abstract: A kiln includes a hollow elongated housing which has an inlet and an outlet spaced from each other defining between them the interior of the housing designed to receive through the inlet the items to be treated. The housing includes a number of sections operative for treating the items as they gradually pass through the sections towards the outlet with different respective treating regimes. The sections downstream of the housing are interconnected with the section upstream of the housing so as to recover the heated gas from the downstream sections and supply the same into the upstream section in predetermined quantities and at a predetermined temperature.

Abstract: A continuous flow heating oven of the industrial type used for the heating of ingots, sheet material and the like, which may be of light metal or light metal alloy, includes a burner fired with a liquid or gaseous fuel disposed within a heating chamber. The material to be heated is placed within the oven with the convection air currents generated from the burners directed thereon, with the hot combustion gases produced by the flames. In addition, the exhaust gases are compressed and directed back onto the object to be heated interspersing with the convection air currents originally generated to increase the efficiency of heating the material.

Abstract: A heating apparatus having doors mounted on the inlet and outlet of a furnace body to cover them and at least one additional door disposed in an intermediate portion of the furnace body to divide it into compartment furnace chambers forming a preheating chamber, a heating chamber and/or a warmth-keeping chamber, from the inlet side to the outlet side. A hot air circulating device is disposed in each of the compartment furnace chambers in a manner such that areas close to each door are much heated. When a material to be heated is charged from the preheating chamber, outer air is shut off from the heating chamber, and when the material to be heated is delivered into the heating chamber, outer air is shut off from the preheating chamber. When the material is shifted from the heating chamber to the warmth-keeping chamber or is discharged to the outside from the warmth-keeping chamber, outer air is shut off in the same manner as above.

Abstract: A tunnel oven of elongated configuration and having at least one movable carriage therein for transporting ceramic products to be baked through the tunnel, is provided with a reversible blower operative to generate a stream of gas having reciprocating movement which passes through the tunnel in a direction opposite to the direction of movement of the carriage. The opposing sides of the tunnel are provided with inwardly extending projections and intervening recesses which give the overall tunnel a zig-zag or wave configuration; and fire stations are located adjacent the various projections or recesses for heating the reciprocating stream of gas and for producing cross currents which cause the stream to flow along a generally sinuous path through the tunnel in a flow direction opposite to the direction of movement of the carriage.

Abstract: A variable air flow oven is disclosed in which a variable air directing control means delivers varying amounts of heated air under various positive pressures in an alternating pattern to jet orifices in opposite side walls of the oven in an inverse ratio. Hot air jets from opposite sides of the oven meet at a region of common velocity in the processing chamber to produce a turbulent mixing of the hot air in a vertical plane. The turbulent heated air travels from one side of the oven to the other substantially throughout a heating period under the controlled operation of a motor driven mechanical linkage arrangement to assure even baking, cooking or drying of the products being processed through the entire processing chamber in the oven. The system operates at a positive pressure at all times, so that the main supply of heated air flows through one side duct and a smaller volume of heated air flows through the opposite side.

Abstract: An apparatus and a process for conveying articles on an elongated rail formed with a plurality of ports therein, which are disposed in communication with a plenum connected to a supply of pressurized fluid for discharge through said ports for supporting and conveying an article along said rail on a cushion of fluid. In accordance with one embodiment of the invention, each of the ports incorporates an apertured disc incorporating deflection means thereon for controlling the quantity and fluid flow pattern discharged from each port. In accordance with another embodiment of the invention, the apparatus is of a modular construction comprising individual sections, each comprising a rail enclosed within a housing including duct work for recovering a controlled proportion of the fluid discharged from the rail and effecting a recirculation thereof through the fluid supply means for reuse.

Abstract: In a process for low particle sterilization of temperature resistant containers (glass bottles), the containers are continuously sterilized by radiant heat in a continuous heating furnace and then cooled by highly purified filtered air. One essential factor for obtaining the freedom from particles is the provision of a non-turbulent stream of highly purified air maintained in the continuous heating furnace in a direction parallel and opposite to the direction of movement of the containers.

Abstract: A machine for drying textile materials, which comprises a casing, electrically driven means for feeding the textile material through the casing, electrically driven means for circulating hot gas within the casing, a gas turbine engine, an alternator driven by the gas turbine engine and providing electrical power for said feeding and circulating means and trunking for feeding the exhaust gas of the gas turbine engine into the interior of the casing.

Abstract: A furnace for heat treating vertically depending sheet material moving through an enclosed heating chamber, the furnace having entrance and exit openings in opposed end walls and a slot in the roof extending between the openings. The depending sheet material moves through the heating chamber suspended from a trolley supported above the slot, which trolley has hanger rods projecting through the slot. The entrance and exit openings are closed by doors, and an air curtain directed across the slot provides a pressure barrier which, together with the doors, prevents the flow of heated gases from and within the heating chamber.

Abstract: A tunnel kiln for use in rebaking carbonaceous moldings impregnated with tar, pitch or the like, consisting of a preheating zone, a baking zone and a cooling zone, which comprises providing arch shafts in the kiln ceiling, providing a plurality of gas recirculating devices communicating with said arch shafts and heating gas blow-in holes of the lower portion of side wall in the preheating zone and the baking zone, and further providing, above the heating gas passages or combustion chambers mounted on a number of connected kiln cars, muffles consisting of receiving plate, bottom plate, holder, cover having in its upper surface a number of tar gas discharge openings, and seal, which muffles accommodating said moldings to be rebaked.

Abstract: A billet is transported through an improved furnace by convention means and is heated in the furnace by an external burner unit in which fuel and air are combusted together and then injected at a high velocity into a semi-cylindrical chamber of the furnace tangentially to the billet so as to create a hot vortex of gases circulating around the billet along the length of the furnace. The temperature of the hot gas vortex within the furnace is sensed by means of a thermocouple placed close to the billet surface but not in contact with it so as to sense the temperature of the billet as a function of the temperature of the circulating gas. The temperature of the injected gas is thereby controlled to heat the billet to a desired temperature and then maintain it at that temperature.

Abstract: Apparatus for heating elements broken up in small pieces wherein the pieces are loaded into baskets with solid vertical walls and perforated or porous bases, and are pushed in a continuous line into a tunnel to there introduce a hot gas which passes vertically through each basket and its contents. A principal application is the preheating of products feeding a smelting or resmelting furnace, and in this case the hot gases used are fumes from the furnace.

Abstract: An apparatus for heating materials such as aluminum billets to a temperature suitable for extrusion is disclosed. The apparatus has at least two zones arranged in tandem, a preheat zone and one or more primary heating zones. Every zone has inner and outer chambers. The outer chamber is supplied with high temperature gas at a pressure in excess of that of the inner chamber. The chambers are separated by baffles which define narrow slot-like aspirating throats through which secondary gases from a secondary source are jetted after entraining high temperature gases from the primary chamber. The secondary gases are at a lower temperature to provide efficient impingement of the gases on a target such as a billet with the primary gases providing the principle heat source. The apparatus is of the closed type utilizing rapid recycling of gases for efficient use of thermal energy.

Abstract: A furnace for heating one or more bodies in which heated gas is introduced into the furnace chamber through one or more injectors and are conveyed to the bodies in a manner involving appreciable resistance to gas flow. In a preferred arrangement a continuous metal strip is conveyed through the furnace on a gaseous support cushion, the gas being introduced into the furnace under pressure through injectors which communicate with the lower portion of the furnace. The injectors generate a substantial recirculation of gas within the furnace.

Abstract: A tunnel-furnace is cooled by circulating air between two metal walls forming a jacket and is provided with a ported or permeable hearth extending along its entire length. The articles to be heated or baked in the furnace are supported therein on an air cushion formed with the heated air providing from the cooling jacket and supplied through the ported hearth.

Abstract: A tunnel furnace composed of individual sections for the heat treatment of articles which are transported through said tunnel on an air permeable belt whereby each section is separated by shields into a main heating space and a pair of flanking outer spaces in communication with the heating space at the top thereof and below said belt, and circulation fans are disposed within the furnace for circulating air in a continuous path upwards through the conveyor belt and then downwards through the outer spaces. A heater is disposed in each outer space comprising a burner and a pipe elbow section for conducting the flame and the combustion gases, the elbow section having an S-shaped configuration so that the combustion gases flow upward during a portion of their travel within the elbow section terminating in a mouth exposed to the circulating air flow.

Abstract: This disclosure relates to glass annealing lehrs in which glass ware is supported on an endless conveyor to convey it through a closed tunnel consisting of separately controllable temperature zones which expose the ware to a glass annealing temperature gradient produced and maintained by gaseous fuel burners and electrical heaters employed separately or jointly, depending upon the availability of the fuel or electrical energy. In accordance with the invention, circulating fans are positioned at both sides of each lehr section, and air inlet ducts are provided for admitting controlled amounts of ambient air to the inlet of each fan.

Abstract: An apparatus for heating materials such as aluminum billets to a temperature suitable for extrusion is disclosed. The apparatus has at least two zones arranged in tandem, a preheat zone and one or more primary heating zones. Every zone has inner and outer chambers. The outer chamber is supplied with high temperature gas at a pressure in excess of that of the inner chamber. The chambers are separated by baffles which define narrow slot-like aspirating throats through which secondary gases from a secondary source are jetted after entraining high temperature gases from the primary chamber. The secondary gases are at a lower temperature to provide efficient impingement of the gases on a target such as a billet with the primary gases providing the principle heat source. The apparatus is of the closed type utilizing rapid recycling of gases for efficient use of thermal energy.

Abstract: Burners of an oven are operated to satisfy heat loads changeable between a high load and substantially smaller loads. At least under the smaller loads the burners are cyclically controlled in a cycle of time periods T-1 and T-2. During the periods T-1 the burners are steadily regulated to maintain a uniform temperature in the oven. For periods T-2 the burners are periodically controlled to admit one of two selected magnitudes of fuel flow to the oven. At least under the smallest loads the latter magnitudes are periodically controlled to be zero or close to zero.

Abstract: A furnace for treating glass sheet material and the like in a glass tempering system. The furnace includes an upper glass treating zone and a lower gas treating and distributing zone for homogenizing gases of different temperatures to minimize exposure of the sheet being treated in the treating zone to uneven temperatures. Diametrically opposed inlets and outlets are provided in the side walls controlled by doors, and a slot in the top wall extends between the inlets and outlets to permit movement of a material carrier through the furnace. A pressure chamber communicates with the slot to cool conveyor elements at the top of the furnace, and also to provide a pressure barrier resisting the escape of gases from the furnace through the slots. Air curtains impinge on the tops of the doors in their closed positions to reduce leakage at the top of the doors.

Abstract: A furnace for heat treating glass sheet material including a circular enclosure having top, bottom and side walls of refractory material. Inlet and outlet openings are formed in the side walls. The side walls have an outer insulating layer and an inner layer of material having a low coefficient of thermal expansion, the inner layer having spaced end portions projecting beyond the outer layers and the periphery of the side walls to define said inlet and outlet openings. Each opening is controlled by doors, and each door includes an elongated support bar with a plurality of blocks of refractory material supported on the bar in end-to-end relationship. The blocks are adjustably secured to the bar to accommodate irregularities in the openings.