Abstract: Heat transfer systems and methods are provided. In one example, a heat exchanger apparatus includes: an enclosure defining an interior; an induction coil within the interior; and a plurality of conductive tubes within the induction coil for heating a salt material in the plurality of conductive tubes using a current induced by the induction coil.

Abstract: An induction furnace includes a melting induction coil for inductively heating a pair of susceptors for melting particulate material falling freely in a free fall zone between the susceptors. A feeder having a rotatable hollow shaft with fingers extending therefrom breaks up the material, which falls onto a vibrating dispersion plate and then into the free fall zone. A preheating induction coil inductively heats a susceptor which radiates heat to particulate material moving over the dispersion plate. An adjustable gap between the feeder and dispersion plate controls material flow. A funnel collects falling molten material and directs it through a nozzle into a mold. Induction coils control melting within the funnel. One induction coil heats the nozzle and may be controlled to allow the nozzle to cool sufficiently to form a solid plug in the nozzle whereby molten material pools above the plug.

Abstract: A pusher furnace includes furnace sections having respective susceptors, a slide rail extending through the furnace sections for sliding pusher plates thereon and an alignment assembly for aligning the susceptors and slide rails of adjacent furnace sections. A support structure spaces the susceptors from insulation therebelow to protect the insulation from degradation from contact with the susceptors. The susceptors are slidably mounted on the support structure to accommodate thermal expansion and shrinkage of the susceptor. The upstream end of the slide rails have beveled upper edges to help prevent the pusher plates from catching thereon. The upstream ends are also laterally tapered to reduce the degree of force encountered should a pusher plate catch thereon. Adjacent insulation members have expansion joints filled with a refractory felt. The susceptors slidably and sealingly engage exhaust ports to allow for thermal expansion and shrinkage of the susceptor without damaging the exhaust port.

Abstract: A continuous- or intermittent-melt induction furnace useful for heating and/or melting semi-conductor or other materials includes an induction coil, a susceptor switchable between open and closed electric circuit modes, and a crucible. The susceptor is inductively or resistively heated in the closed circuit mode and transfers heat to material in the melting cavity to make it susceptible to inductive heating. The susceptor is then switched to the open circuit mode and the susceptible material is directly inductively heated to melt remaining solid material. A cone-shaped flow guide in the melting cavity improves molten material flow to improve the ability to draw small-particle material into the melt and increase crucible life due to improved heat uniformity. A trap passage communicating with the melting cavity and an exit opening in the crucible allows the flow of material through the exit opening to be controlled by pressure differentials on either side of the trap passage.

Abstract: Systems and methods are presented for producing shot from molten material, in which two or more sprays of inert gas, such as an upper or primary spray followed by one or more lower or secondary sprays, are used to break apart large molten droplets into shot as the molten material is dropped from a crucible orifice. The upper or primary gas feed in one application acts to initially break the stream or droplets into initial droplets of a lesser size or to flatten the droplets, with the second spray then breaking up the intermediate droplets into yet smaller shot particles to be cooled and collected.

Abstract: A compression system for an inductively heated pusher furnace controls movement of susceptors during thermal contraction thereof. The system includes a plurality of furnace sections each having a susceptor wherein each susceptor abuts an adjacent susceptor and wherein the susceptors include first and last susceptors. A compression plate abuts the first susceptor to apply force thereon toward the last susceptor to keep the susceptors in abutment with each other during contraction of the susceptors during cooling thereof. An actuator for moving the compression plate is preferably automatically controlled by a computerized control system. The susceptors together form a tunnel through which pusher plates travel and have overlapping joints which seal against the escape of gasses and allow for a degree of susceptor contraction without forming a gap therebetween even in the absence of compression of the susceptors.

Abstract: A pusher plate for use in a pusher furnace includes a shaped guidance groove in its lower surface which preferably has a bow-tie shape with a narrower central section and wider ends proximate the leading and trailing faces of the plate. The groove receives therein a guide rail which is disposed intermediate a pair of slide rails upon which the plate slides. The shape of the groove allows the plate a small amount of lateral rotation to minimize jamming during travel. Adjacent plates pivot upon contact with each other to automatically adjust their orientation during travel through the furnace. The leading and trailing faces of the plates thus contact one another over a larger surface area to reduce damage to the plates by reducing the pressure therebetween.

Abstract: An induction furnace includes a melting induction coil for inductively heating a pair of susceptors for melting particulate material falling freely in a free fall zone between the susceptors. A feeder having a rotatable hollow shaft with fingers extending therefrom breaks up the material, which falls onto a vibrating dispersion plate and then into the free fall zone. A preheating induction coil inductively heats a susceptor which radiates heat to particulate material moving over the dispersion plate. An adjustable gap between the feeder and dispersion plate controls material flow. A funnel collects falling molten material and directs it through a nozzle into a mold. Induction coils control melting within the funnel. One induction coil heats the nozzle and may be controlled to allow the nozzle to cool sufficiently to form a solid plug in the nozzle whereby molten material pools above the plug.

Abstract: Systems and methods are presented for producing shot from molten material, in which two or more sprays of inert gas, such as an upper or primary spray followed by one or more lower or secondary sprays, are used to break apart large molten droplets into shot as the molten material is dropped from a crucible orifice. The upper or primary gas feed in one application acts to initially break the stream or droplets into initial droplets of a lesser size or to flatten the droplets, with the second spray then breaking up the intermediate droplets into yet smaller shot particles to be cooled and collected.

Abstract: A pusher furnace includes a pusher assembly having first and second coordinated pushers for pushing load supports with loads to be heated thereon to provide continuous downstream movement of the load supports through a furnace section. A removal assembly includes a first removal mechanism which removes the load supports from the furnace section and a second removal mechanism which removes the loads from the first removal mechanism to facilitate the continuous downstream movement. The first removal mechanism preferably includes a parallelogram-type four-bar linkage for lifting the load supports and lowering them onto the second removal mechanism. Entry and exit plenums are connected to respective ends of the furnace section to provide a controlled atmosphere within the furnace section. The pusher and removal assemblies are timed with opening and closing of various gates of the plenums to maintain the controlled atmosphere.

Abstract: An induction furnace includes an induction coil, an electrically non-conductive crucible having an inner diameter disposed within the induction coil, and an electrically conductive member disposed below the crucible and having an outer diameter which is further from the induction coil than is the inner diameter of the crucible. Due to the non-conductive nature of material disposed within the crucible at lower temperatures, the induction coil initially inductively heats the conductive member, which transfers heat to the material to melt a portion of the material. Once the material is susceptible to inductive heating (usually upon melting) the susceptible material is inductively heated by the induction coil. During the process, inductive heating of the material greatly increases as inductive heating of the conductive member greatly decreases due to low resistivity of the molten material and due to the molten material being closer to the coil than is the conductive member.

Abstract: A continuous- or intermittent-melt induction furnace useful for heating and/or melting semi-conductor or other materials includes an induction coil, a susceptor switchable between open and closed electric circuit modes, and a crucible. The susceptor is inductively or resistively heated in the closed circuit mode and transfers heat to material in the melting cavity to make it susceptible to inductive heating. The susceptor is then switched to the open circuit mode and the susceptible material is directly inductively heated to melt remaining solid material. A cone-shaped flow guide in the melting cavity improves molten material flow to improve the ability to draw small-particle material into the melt and increase crucible life due to improved heat uniformity. A trap passage communicating with the melting cavity and an exit opening in the crucible allows the flow of material through the exit opening to be controlled by pressure differentials on either side of the trap passage.

Abstract: A method and apparatus for accelerated cooling of a furnace such as a furnace containing a susceptor. Cooling gases are split whereby a first percentage are provided to cool the furnace while a second percentage are provided to assist in cooling the heated cooling gases after cooling the furnace, whereby the percentages are changed throughout the process. The system further provides for unique cooling flow arrangement in the furnace which promotes maximum heat transfer through swirling.