Abstract: A thermal processing furnace, comprising: a generally bell jar-shaped outer reaction tube having a central axis; and an open-ended inner reaction tube for accommodating a wafer boat holding a plurality of substrates, which inner reaction tube is substantially coaxially disposed within the outer reaction tube, thereby defining a gas passage between an outer wall of the inner reaction tube and an inner wall of the outer reaction tube, wherein at least one of the outer wall of the inner reaction tube and the inner wall of the outer reaction tube is provided with a flow deflector that protrudes radially from the respective wall into the gas passage.

Abstract: The invention relates to a ring furnace (1) having a longitudinal axis and comprising elongated bays (10), a plurality of hollow partitions (3, 3?) arranged within the casing of each bay so as to be parallel to the longitudinal axis, a first end transverse wall (41) located at a first end of each bay (10), a second end transverse wall (42) located at a second end of each bay (10) and possibly one or more intermediate transverse walls (43) located between the first and second ends. The hollow partitions and transverse walls define baking pits (2) within the bays (10) for stacking carbonaceous articles therein. The baking pits have a length Lp and a width Wp, said length Lp being at least 15 times greater than said width Wp.

Abstract: An oven protection system for a thermo-forming machine having a source of heat for heating a workpiece. The oven protection system includes a barrier that is movable from a stored position to a deployed position between the source of heat and the workpiece in response to a predetermined condition.

Abstract: A temperature changing apparatus including a chamber defining a cavity is configured to receive a food product therein. A radially exhausting fan disposed in the cavity circulates air in the cavity over the food product. An air deflector disrupts the air radially exhausted from the fan.

Abstract: A carbon baking furnace having spaced-apart, hollow flue walls defining a soaking pit therebetween. Each of the flue walls is formed of refractory bricks and has a pit face facing the pit and a flue face facing an inner flue gas passage. A coating is provided on the pit face of the flue walls. The coating increases the emissivity value of the pit face, wherein the emissivity value of the pit face is greater than the emissivity value of the flue face.

Abstract: A burner protection shield is provided at a distance and in an area below a burner lance that is used in a rotary kiln for the production of cement clinker. Such a mechanism enhances the useful lifetime of the burner lance.

Abstract: A glass feeder comprises an enclosed chamber through which molten glass can pass, and passing through each side wall into the chamber at least one burner comprising first and second burner head means for combusting oxidant and fuel within said chamber so as to generate flames which extend in axially opposite directions along each side wall, adjacent and parallel to the side walls and adjacent the surface of the molten glass.

Abstract: The invention relates to an arrangement and method for heating gases in a gas circulation duct in connection with continuously operated sintering. In the sintering furnace, hot gas is fed in from above the belt in order to sinter the material located on the belt, and part of the gas circulation duct is formed as a burning zone, a burner ring, where the gas is heated. The burner ring comprises at least one burner unit directed inwardly from the circumference of the gas circulation duct.

Abstract: A heating furnace of convection type is provided for improving rising characteristics at an operation start-up time to stabilize conditions within the heating furnace in a shorter time and maintaining a uniform temperature in the furnace. The heating furnace comprises a conveyer unit for supporting an article to be heated and conveying the article through a heating chamber of a furnace body having an article inlet and outlet, a heating source provided in at least one of side and top portions of the furnace body such that the heating source is exposed to the interior of the heating chamber, an exhaust port formed in a lower portion of the heating chamber at a position displaced a predetermined distance from the heating source in the longitudinal direction of the furnace, the exhaust port being positioned below a lower end of the heated article, and an air inlet port associated with the heating source and provided below the exhaust port.

Abstract: A method for preheating a permeable, thermoformable material having first and second sides includes supplying heated fluid to a fluid distribution system; regulating flow of the fluid such that fluid having a first temperature flows at a first velocity, and fluid having a second temperature less than the first temperature flows at a second velocity greater than the first velocity; introducing the fluid onto the first side of the material; and developing a suction on the second side of the material sufficient to draw the fluid through the material thereby convectively heating the material; wherein the flow of the fluid is regulated so as to transfer substantially uniform energy flux to the material.

Abstract: This invention concerns a boiler fitted with a burner suitable for wall heaters or built-in kitchen heaters in which a mantle-shaped heat exchanger made of pipe elements connected in parallel and/or series divides the boiler chamber into a combustion chamber and an exhaust chamber. The heat exchanger has openings for hot flue gases distributed over its mantle. The burner head disposed in the combustion chamber is suitable for burning oil and has a flame tube with an axial flame opening and a flame baffle element disposed at a distance from the flame opening which is constructed so that the flame is diverted into the space between the flame tube and the heat exchanger. In addition, a fire chamber mantle can be disposed between the heat exchanger and the flame tube to protect the heat exchanger from direct contact with the flame.

Abstract: A block assembly for a lehr includes a plurality of blocks extending longitudinally, each of the blocks having a seal surface for mating and overlapping with an adjacent one of the blocks.

Abstract: The furnace for baking carbonaceous blocks comprises, along the longitudinal X direction of the furnace, a series of sections, each section comprising, in the transverse Y direction, hollow walls (3) through which a heating gas flow comprising combustion gas or a cooling air flow circulates, alternating with pits containing carbonaceous blocks to be baked, each of the said hollow walls (3) in a section being in communication with a wall in an upstream section and/or a wall in a downstream section, so as to form a conduit through which the said gas flow circulates, each of the said walls of a section comprising two vertical lateral partitions (38) in the X-Z plane, and elements in the transverse Y direction for deflecting the said gas flow passing through the said wall and maintaining a constant spacing between the said lateral partitions (38), and characterized in that each wall (3) comprises a means of maintaining, over at least one third of the length L of said wall, a gas flow of rate D uniformly distribut

Abstract: A heating device including a first exothermic member disposed below a subject to be heated for preventing heat radiation from the subject while heating the subject from below, a second exothermic member disposed above the subject for preventing heat radiation from the subject while heating the subject from above, and a base or sandwiching and supporting body for bearing the subject sandwiched between the first exothermic member and the second exothermic member while securing a space under the first exothermic member. The heating device is convenient to carry about and capable of easily heating a food or the like without rapidly generating a great amount of heat.

Abstract: A convection braze furnace for brazing aluminum heat exchangers in an inert gas rich atmosphere includes entrance and exit vestibules forming atmosphere barriers of suspended stainless steel strips. The interior of the braze furnace is divided into multiple zones for progressively heating the heat exchangers to a brazing temperature and then cooling the heat exchangers in the final zone. An impeller circulates the heated intent gas atmosphere within each zone to accelerate heat transfer. A chain type conveyor supports the heat exchangers as they are moved through the braze furnace. An isolated return tube surrounds the lower return side of the conveyor chain as it passes through the braze furnace. The braze furnace housing is comprised of inner and outer shells having an inert gas pressurized interstitial cavity therebetween. The inner shell includes a plurality of expansion strips having generally ellipsoidal corner expansion joints.

Abstract: A curing apparatus used in manufacturing semiconductor devices including high-temperature gas chamber and heating chamber communicated with slits formed in a partition plate installed between the two chambers. Gas diffusion plates are installed in the gas chamber at right angles against the flow of gas so that the diffused and uniform high-temperature gas passes through slits and blown onto workpieces placed directly beneath the slits.

Abstract: A vapor reflow type soldering apparatus with an upper supply hole of vapor for heating the upper surface of an article to be processed, the position of which is displaced to the downstream side along a direction of delivery with respect to that of a lower supply hole of vapor for heating the lower surface of the article, so that the temperature of the upper surface of the article to be processed can be raised more moderately than that of the lower surface thereof.

Abstract: A thermoforming oven for the convection heating of a continuous web of a thermoplastic foam or film material which is being advanced through the oven towards a thermoformer. Moreover, there is disclosed to a method for the improved and more uniform convective heating of a thermoplastic foam or film material which is advanced through a thermoforming oven. A countercurrent flow of a gaseous heating medium is regulated and directed so as to impart the greatest degree of uniformity of temperature thereto during heating and blow-up to the thermoplastic material being advanced in an intermittent manner through the convective oven.

Abstract: A heating furnace comprises a horizontal body portion, a source of heat located at an intermediate portion of the body portion for forming hot gas which circulates in the body portion by natural convection, a gas discharge port formed in the wall of the body portion, a gas collecting hood connected to the lower end of an exhaust cylinder, and a horizontal conveyor for conveying an article to be heated through the furnace. The opposite ends of the body portion act as the inlet and outlet ports as well as gas discharge ports. In one embodiment, upper half portions of the inlet and outlet ports are covered by shielding plates. In another embodiment the opposite ends of the body portion are inclined downwardly to form the inlet and outlet ports near or below the bottom surface of the furnace. In still another modification, air curtains are formed at the inlet and outlet ports.

Abstract: A device for transferring a food piece from an upper conveyor to a lower conveyor in an oven includes a slide having a first curved sheet with a continuous transfer surface for guiding a food piece between upper and lower conveyors while reversing the direction of and inverting the food piece. The slide includes a second curved sheet which together with the first curved sheet forms a unitary structure with an insulating layer between the first and second curved sheets. The slide is supported by track followers on a pair of parallel tracks. Also supported on the tracks is a heat shield separating the slide from outside the oven, the heat shield being connected to the slide by the track followers. The slide and heat shield are simultaneously displaceable along the tracks between a transfer position wherein the slide is intermediate to the upper and lower belts for transferring articles between the belts, and a position wherein access is provided to the slide from outside the oven.

Abstract: A food preparation apparatus including a cooking chamber having a pair of openings in two opposite facing walls thereof. A conveyor extends through the side wall openings and the chamber for conveying a food product through the chamber. First and second pairs of impingement finger ducts are provided for forming a plurality of columnated air jets and for impinging the jets against discreet points of a food product supported on the conveyor. A first one of each of said pairs of ducts is disposed above the conveyor and a second one of each of said pairs of finger ducts is disposed below the conveyor. First and second plenums, each of which has a fan respectively associated therewith, supply air to the finger ducts. One or more baffles in each of the plenums guides and streamlines the air as it flows out of the plenums and through the finger ducts. A single burner is associated with the plenums for simultaneously supplying heat energy to both plenums.

Abstract: Assembly for pulsatory combustion comprising a combustion chamber, a horn and an exchanger part, made through drawing and welding of two half-shells, the separation plate being secured to the inside of the chamber in a recess provided for this purpose such an assembly being applied to domestic heating.

Abstract: An improved exhaust port plug is provided for use in a baking furnace for the baking of anodes for use in an electrolytic reduction cell. The improved exhaust port plug comprises a cylindrical metal shell having a diameter approximating the diameter of the port, a cover member on the shell having a dimension exceeding the diameter of the port, a gasket means on the underside of the cover member surrounding the shell and adapted to sealingly engage an external portion of the furnace, a mat of packed ceramic fibers within the shell, and retaining means to retain the mat of ceramic fibers within the metal shell.

Abstract: In order to be able to heat the charging material (3) of a charging material preheater (1) in a more uniform fashion and to higher temperatures, while enjoying short flow paths, the charging material preheater (1) is in the form of a container (2) having a bottom opening (4) which can be closed by an axially displaceable hollow cylinder (13), the interior of the container is subdivided by a grid (6) which falls away in an inclined configuration towards the bottom opening (4), into a receiving space (7) for the charging material and a free lower annular space (8) into which opens an opening (9) for the heating gas, and the hollow cylinder (13) is incorporated into the flow path, by way of gas orifices (16, 17). In addition the heating gases are passed through the charging material (3) alternately in opposite directions.

Abstract: A vapor tank for processing a product by heating the same through exposure to vapor serving as a heat transfer medium. The vapor tank includes at least one partition wall separating a vapor chamber filled with vapor and a heating chamber for processing the product by heating the same for supplying a sufficient saturated vapor to the product. The partition wall is formed with openings for allowing the saturated vapor to be injected therethrough from the vapor chamber into the heating chamber where the product is enveloped by the saturated vapor. The vapor tank is provided with a recovery device for recovering the vapor flowing out of the tank through an inlet and an outlet for introducing and discharging the product into and out of the tank with a high degree of vapor recovering efficiency and with a minimum loss of energy. The vapor tank is also provided with a mechanism for externally supplying air currents to prevent the vapor from flowing out of the tank through the inlet and the outlet.

Abstract: A tunnel dryer and method for drying unfired bricks or similar objects in which the tunnel comprises exhaust means for exhausting heated gases within the tunnel, partition means disposed in the drying space of the tunnel consisting of at least one vertically adjustable partition positioned upstream of the exhaust means, and means for positioning the vertically adjustable partition at an intermediate level within the drying space of the tunnel to define an effective drying zone for the unfired bricks.

Abstract: A non-oxidizing firing furnace for ceramic articles, which comprises a furnace chamber filled with a non-oxidizing gas, a conveyor mechanism provided on the floor portion of the furnace chamber and adapted to move the ceramic articles oppositely to a direction in which the non-oxidizing gas is flown through the furnace chamber for firing the ceramic articles; and at least one partition wall with the surface being composed of molybdenum which partition wall is provided at the ceiling portion of the furnace chamber to define a low temperature zone on the inlet side for the ceramic articles and a high temperature zone.

Abstract: The invention relates to an apparatus for equalizing the temperature of conveyor rolls in a glass-tempering furnace, said furnace comprising a thermally insulated housing (1) confining a heating chamber (8), conveyor rolls (4), extending horizontally between the side walls of chamber (8) and lying one after the other in the lengthwise direction of the chamber, heating resistors (5 and 6) in the chamber above and below the array of conveyor rolls, as well as means for driving the conveyor rolls unidirectionally during a first cycle and reciprocally during a second cycle. Since the reciprocating movement means that a glass sheet remains longer in contact with the midsection rolls, these rolls cool more rapidly. In order to equalize the temperature of the rolls, the end sections of the furnace are provided with screen plates (7) mounted between heating resistors (6) below the array of conveyor rolls and the rolls (4) themselves.

Abstract: In a continuous heating furnace, particularly in a preheating chamber thereof, forced heat convections of an atmosphere gas are produced to heat articles rapidly. The convections which circulate transversely to a longitudinal axis of the furnace, retard an axial flow of the atmosphere gas. This retardation is lassened by having the convections flown portionally as branch streams toward an intake opening of the furnace by means of novel baffle plate or vane means which are provided in the preheating chamber so as to be outside a moving path of articles through the chamber and within circulating paths of convections.

Abstract: A kiln producing a uniform temperature distribution within the kiln heating chamber and enabling maximum use of heating chamber volume. The heat source is provided by a high-velocity flow of heating gas, which is introduced into the heating chamber through an orifice in a chamber wall. A deflector plate is positioned proximate to, and spaced apart from, the chamber wall so as to overlie the orifice in the path of the high-velocity flow. The dimensions and spacing of the deflector plate may be chosen so as to produce a flow of heat gas primarily parallel to the adjacent wall of the heating chamber and so that the parallel flow will maintain its substantial integrity along the wall much beyond the extremities of the deflector plate. Appropriately positioned gas-entrance ports with associated deflector plates in the kiln are found to produce a uniform temperature distribution without the sacrifice of otherwise usable heating chamber volume.

Abstract: Apparatus and method for substantially blocking the "line-of-sight" between a radiant section of a furnace and a convection section positioned above the radiant section, while at the same time permitting flue gases from the radiant section to travel substantially freely through the shield. The shield may be composed of a plurality of staggered bodies. In a preferred embodiment the bodies are staggered plates, composed of insulating material. The staggered plates are supported by hangers that are hung from convection tubes in the convection section. In another embodiment the staggered bodies are tubes or rods.

Abstract: The present invention includes a heat insulation wall which is formed in a closed plane configuration, such as a circle, and which has first and second pairs of apertures formed therein to accommodate cooling (inert) gases which are introduced into the heat chamber defined by said insulation wall. The cooling gases pass into the heat chamber and out of the heat chamber through the first and second pairs of apertures to cool a workpiece which has been heat treated. The pairs of apertures lie (in pairs) opposite one another on the periphery of the heat insulation wall. Outside of the heat insulation wall, lying opposite the first pair of apertures, is located a heat reflecting member and opposite the second pair of apertures, outside of the heat insulation wall, there is located a heat reflecting baffle. Accordingly when the heat chamber is operating in a heat treating mode any heat which passes through an aperture or a pair of apertures is reflected back through said apertures into the heat chamber.

Abstract: The present invention provides, among other things, a plenum which is formed around the hot zone chamber of a vacuum furnace and which has a common wall with the hot zone chamber. The present arrangement includes having a plurality of apertures formed in the common wall and a plurality of baffles, or deflecting means, secured to the common wall within the chamber of the plenum. The baffles, or deflecting means, are formed to be angular with respect to the common wall and each deflecting means is disposed and formed to deflect gas (in all likelihood, inert gas), passing through the plenum, into and through an associated aperture and thereby into the hot zone chamber. By using the baffles, the inert gas, which is fed into the hot zone chamber from the plenum, is so fed with improved and significant uniformity.

Abstract: An improved cooking oven having two flat surfaces covered by an enclosure. One of the flat surfaces serves as a base on which the enclosure rests and on which both fuel to be burned and food to be cooked are placed. The second of the flat surfaces, which is substantially parallel to and positioned above the flat surface that acts as the base, serves as a baffle to control the flow of combustion products from the burning fuel through the enclosure and as an additional cooking surface. Three openings in the wall of the enclosure are provided; two of which are used for passage of food and fuel therethrough. The third opening serves as a flue and provides a path through which combustion products from the burning fuel escape from the oven.

Abstract: A gas flows through a pipe employed for intensive heat and material transfer, wherein the pipe has a length equal to 0.5 to 100 meters. The pipe features a gas inlet and two gas outlets. A solid body charge interacting with the gas flow enters at an inlet position in the pipe, passes a plurality of baffles which reduce the cross section in the pipe, and emerges from the pipe at the end position. Together with the surface of the solid body charge, the baffles form gaps of 3-50 mm which reduce the boundary layer of gas on the charge limiting the heat or material transfer. Between each pair of neighboring baffles are chambers in which the gas rotates and thus strikes the charge repeatedly. As a result the efficiency of material and heat transfer is further improved. With this countercurrent system the solid body can take up and release heat during its passage through the pipe and can take up or release material according to the character of the gas flowing in the inlet.

Abstract: A high pressure steam condensation soldering facility (10) is described. The facility (10) incorporates a chamber (12) having a centrally located heat processing zone (45) into which high pressure steam is injected to reflow solder on articles (43) therein. A baffle (41) having a conical top portion (51) with a plurality of apertures (52) therein permits controlled amounts of the steam to pass therethrough while redirecting a portion of the steam along the wall (16) of the chamber (12) to interpose a shield of steam between the wall and uniformly heated processing zone (45).

Abstract: Device and process for operation of open baking furnaces, in particular such ring-type furnaces for manufacturing anodes for the aluminum electrolytic process, are such that for each so called fire the sealing chamber and/or chamber in the cooling zone can be saved in that the flue gas exhaust manifold is not situated on the headwall but instead on the flue and/or the opening of that headwall on which the last fresh air supply manifold is situated is closed off by a sliding baffle. Openings corresponding in cross section to that of the connected part of the flue gas exhaust manifold are provided in the region of the flues.The advantage of the process lies in the greater flexibility in furnace operation, which results either in an increase in production or an increase in product quality.

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: An apparatus for controlling the ventilation effect on material dried in a tunnel drying plant, through which goods in the form of architectural ceramic structures, such as of bricks or tiles, to be dried and placed in layers, are moved in counter-current relation to an air current. The tunnel drying plant is designed with doors at the goods inlet and outlet ends. At the goods outlet end there is a pipe connection for blowing air under gage pressure into the plant, while at the goods inlet end and the top part of the tunnel drying plant there is an aspiration opening with an aspiration pipe connection. In the free cross-section of the flow tunnel drying plant, near the roof, there are air guiding bodies, which may be moved backwards and forwards in the length direction of the plant using cars on rails. These air guiding bodies are hollow and have a streamlined form.

Abstract: A furnace (10) has a preheater zone (12) into which exhaust gases of a combustion chamber (14) are recycled for preheating of articles passing through the furnace. The exhaust gases are supplied to the preheater zone (12) through jet pipes (18) which create a turbulent flow about the articles in the furnace (10). The exhaust gases are withdrawn by a fan (30) which is disposed in a duct (34) adjacent to the furnace entrance (13). To prevent the introduction of ambient air into the furnace (10), a pressure chamber (56), which is maintained at an elevated pressure relative to the ambient air, is provided within the preheater zone (12), with the chamber (56) pressurized by gases supplied by the jet pipes (18). A sealing arrangement defined by the pressure chamber (56) and the articles passing through the furnace prevents the introduction of cool air through the preheater zone (12).

Abstract: A heating furnace, suitable for use in a continuous steel slab heating furnace, wherein slabs are heated by fuel combustion flames. Heat transfer converters each made of a heat-resistant material are disposed downstream of the flow of the combustion flames, more particularly, in the preheating zone of the furnace. These converters are heated through convection heat transfer from a high temperature and high speed flow of the combustion flames.

Abstract: A heating furnace, suitable for use in a continuous steel slab heating furnace, wherein slabs are heated by fuel combustion flames. Heat transfer converters each made of a heat-resistant material are disposed downstream of the flow of the combustion flames, more particularly, in the preheating zone of the furnace. These converters are heated through convection heat transfer from a high temperature and high speed flow of the combustion flames.

Abstract: An apparatus is disclosed for processing products aligned on a tape. In the present embodiment, the products are shown to be heat recoverable sleeves which are conveyed to a control station for insertion of a terminal. The work is then released from the control station and allowed to pass across a heater which recovers the sleeve about the terminal. To accomplish the above, a drive having a friction coupling and a positive coupling are employed to convey the work through the apparatus. A conditioned atmosphere process apparatus is employed for the heating of the sleeves and a controlled product feed apparatus controls the feeding of the work to the control station.

Abstract: A heating furnace, suitable for use in a continuous steel slab heating furnace, wherein slabs are heated by fuel combustion flames. Heat transfer converters each made of a heat-resistant material are disposed within and in the flow of the combustion flames. These converters are heated through convection heat transfer from a high temperature and high speed flow of the combustion flames.

Abstract: A regeneration equipment for spent activated carbon comprises a regeneration reactor provided vertically through a vertical heating furnace and an integrated body of a longitudinal series of numerous spiral elements fixedly provided almost throughout the length of said regeneration reactor. Steam ducts are provided so that they are inserted in said regeneration reactor at about the middle portion thereof. On the outside surface of the wall of said regeneration reactor, fixedly provided are exhaust chambers, each of which communicates at its bottom portion with the inside of said regeneration reactor through exhaust holes provided in the wall of said reactor, and is filled with heat-resisting balls piled up in three layers so that the balls in the top and bottom layers are larger in diameter than said exhaust holes and those in the middle layer are similar in diameter to activated carbon particles.

Abstract: A vacuum electric furnace is disclosed for operation with a hostile environment therein which may be above the melting temperature of most metals, other than refractory metals, with apparatus in the furnace for advancing the work, the advancing apparatus being a walking beam with provisions for protecting the exposed portions of the walking beam by the use of graphite and with work supporting buttons of molybdenum to prevent the work from reacting with the graphite at high temperatures, and with separation and shielding of portions of the walking beam from the hot zone and with liquid cooling of the shielded portions.

Abstract: Apparatus for pulling a ribbon shaped crystal from a melt of the same downwardly through a shaping guide having a "V" shaped longitudinal trough for containing the melt. The inner wall of the trough is a die set having a longitudinal slit at the apex of the "V".

Abstract: An industrial oven having a housing defining a work chamber into which products to be treated by the oven may be placed includes a duct system communicating with a blower wheel mounted in the work chamber for communicating air blown by the wheel to the work chamber. The industrial oven further includes the improvement of a blower scroll consisting of a plurality of plates mounted about the blower wheel in an involute configuration. The blower plates define a plurality of outlets for uniformly directing air from the wheel to the duct system.

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.