# US 10,371,445 B1 · Passive thermal control of microwave furnace components > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,371,445 B1 - Document ID: US10371445B1 - Status: Granted - Kind: B1 - Application number: 15/351,710 - Filed: 2016-11-15 - Granted: 2019-08-06 - Earliest claimed: 2016-11-15 - Assignees: Consolidated Nuclear Security, LLC - Applicants: Consolidated Nuclear Security, LLC - Inventors: Edward B. Ripley - Web page: https://patentgrep.com/patent/US10371445B1 ## CPC - F27B 14/06: heated electrically, e.g. induction crucible furnaces with or without any other source of heat (F27B14/04 takes precedence) - F27B 14/10: Crucibles - F27B 14/20: Arrangement of controlling, monitoring, alarm or like devices - H05B 6/6491: {combined with the use of susceptors (H05B6/80 and subgroups takes precedence)} - H05B 6/80: Apparatus for specific applications (stoves or ranges F24C7/02) - F27D 2099/0028: {Microwave heating} - F27B: FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS - H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL - F27D: DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE ## Abstract A microwave furnace includes a microwave casket having an inner surface forming an internal cavity. A heatable body, formed at least in part of a microwave susceptor material, is located in the internal cavity of the casket and heats in response to a microwave field. A thermal control system is provided, which includes a fluid flow path extending through the casket and has an inlet and an outlet formed in the microwave casket. A portion of the fluid flow path is adjacent the heatable body. The thermal control system flows a thermal transfer fluid through the fluid flow path via the inlet to absorb heat from the heatable body and to transfer the absorbed heat along the fluid flow path until the thermal transfer fluid exits the fluid flow path via the outlet. ## Claims ### Claim 1 A microwave furnace comprising: a microwave casket having an inner surface forming an internal cavity, the microwave casket formed at least in part of a microwave transparent material; a heatable body having an internal surface and an external surface disposed in the internal cavity of the casket configured for receiving a metal charge, the heatable body formed at least in part of a microwave susceptor material operable to heat in response to a microwave field for transferring the heat to the metal charge; and a thermal control system including a fluid flow path disposed between the inner surface of the microwave casket and the external surface of the heatable body, the fluid flow path fluidly connected at a first end to an inlet formed in the microwave casket and at a second end to an outlet formed in the microwave casket, the thermal control system operable to flow a thermal transfer fluid through the fluid flow path via the inlet to absorb heat from the heatable body and to transfer the absorbed heat along the fluid flow path until the thermal transfer fluid exits the fluid flow path via the outlet. ### Claim 2 (depends on 1) The microwave furnace of claim 1 further comprising: a microwave chamber wall forming an enclosed microwave chamber, wherein the microwave casket and heatable body are disposed within the microwave chamber; a fluid supply for supplying the thermal transfer fluid to the microwave chamber; a first fluid pipe located outside of the microwave chamber having an end attached to the fluid supply and an opposite end in fluid communication with the microwave chamber, the first fluid pipe operable to carry the thermal transfer fluid from the fluid supply to the microwave chamber; and a second fluid pipe located outside of the microwave chamber and having an end in fluid communication with the microwave chamber and a fluid exhaust located at an opposite end of the second fluid pipe, the second fluid pipe operable to carry at least a portion of the thermal transfer fluid away from the microwave chamber, wherein, in response to a pressure differential between pressure inside the microwave chamber and pressure outside of the microwave chamber created by opening the first fluid pipe and the second fluid pipe, the thermal transfer fluid provided by the fluid supply via the first fluid pipe flows into the casket, flows along the flow path, flows out of the casket, and flows out of the microwave chamber via the second pipe. ### Claim 3 (depends on 2) The microwave furnace of claim 2 further comprising a pump disposed within the microwave chamber proximate the inlet of the flow path configured to intake and then propel thermal transfer fluid located within the microwave chamber through the flow path and to cause at least a portion of the fluid exiting the flow path to be re-circulated within the microwave chamber back to the pump and then propelled through the flow path. ### Claim 4 (depends on 2) The microwave furnace of claim 2, wherein the opposite end of the second fluid pipe is connected to the fluid supply such that fluid flowing through the flow path and exiting the microwave chamber via the second fluid pipe re-circulates back to the fluid supply, the microwave furnace further comprising a pump disposed in at least one of the first and second fluid pipes operable to cause the thermal transfer fluid to be propelled away from the fluid supply and into the microwave chamber via the first pipe, along the flow path, and out of the chamber and back to the fluid supply via the second pipe. ### Claim 5 (depends on 1) The microwave furnace of claim 1 wherein the fluid flow path is positioned between the microwave casket and the heatable body such that heat absorbed from a first portion of the heatable body by the thermal transfer fluid is used to heat a second portion of the heatable body as the thermal transfer fluid flows along the fluid flow path. ### Claim 6 (depends on 5) The microwave furnace of claim 5 wherein the first portion of the heatable body is formed of a first material that has a first susceptance level and wherein the second portion of the heatable body is formed of a second material that has a second susceptance level that is different from the first susceptance level. ### Claim 7 (depends on 1) The microwave furnace of claim 1 wherein the heatable body comprises a crucible and a mold. ### Claim 8 (depends on 1) The microwave furnace of claim 1 wherein the inlet is disposed in a top plate of the casket above the heatable body and wherein the outlet is disposed in a bottom plate of the casket below the heatable body. ### Claim 9 (depends on 1) The microwave furnace of claim 1 wherein the outlet is disposed in a top plate of the casket above the heatable body and wherein the inlet is disposed in a bottom plate of the casket below the heatable body. ### Claim 10 (depends on 1) The microwave furnace of claim 1 wherein the heatable body is placed on top of a base plate of the casket and wherein the fluid flow path comprises a fluid directing structure configured for directing the transfer fluid flowing across a surface of the base plate beneath at least a portion of the heatable body. ### Claim 11 (depends on 10) The microwave furnace of claim 10 wherein the fluid directing structure is selected from the group consisting of: one or more channels formed in the base plate and one or more ridges formed on the base plate. ### Claim 12 (depends on 10) The microwave furnace of claim 10 wherein the fluid directing structure extends radially outwards from a center of the base plate located directly beneath the heatable body. ### Claim 13 (depends on 1) The microwave furnace of claim 1 wherein the fluid flow path comprises a void space disposed between the inner surface of the microwave casket and the external surface of the heatable body. ### Claim 14 (depends on 1) The microwave furnace of claim 1 further comprising: a microwave chamber wall forming an enclosed microwave chamber, wherein the microwave casket and heatable body are disposed within the microwave chamber; a pump disposed within the microwave chamber proximate the inlet of the flow path configured to intake and then propel thermal transfer fluid located within the microwave chamber through the flow path and to cause at least a portion of the fluid exiting the flow path to be re-circulated within the microwave chamber back to the pump and then propelled through the flow path. ### Claim 15 A method of thermal control of microwave furnace components, the method comprising the steps of: providing a microwave casket having an inner surface forming an internal cavity, the microwave casket formed at least in part of a microwave transparent material; providing a heatable body having an internal surface and an external surface in the internal cavity of the casket configured for receiving a metal charge, the heatable body formed at least in part of a microwave susceptor material operable to heat in response to a microwave field; providing a thermal control system including a fluid flow path disposed between the inner surface of the microwave casket and the external surface of the heatable body, the fluid flow path fluidly connected at a first end to an inlet formed in the microwave casket and at a second end to an outlet formed in the microwave casket; positioning the metal charge in the heatable body; generating a microwave field to heat the microwave susceptor material of the heatable body for transferring heat to the metal charge; and introducing a thermal transfer fluid into the fluid flow path via the inlet, the thermal transfer fluid being operable to flow through the fluid flow path to absorb heat from the heatable body and to transfer the absorbed heat along the fluid flow path until the thermal transfer fluid exits the fluid flow path via the outlet. ### Claim 16 (depends on 15) The method of claim 15 further comprising the steps of: providing a microwave chamber wall forming an enclosed microwave chamber, the microwave casket and heatable body being disposed within the microwave chamber, and wherein the thermal control system further includes: a fluid supply for supplying the thermal transfer fluid to the microwave chamber, a first fluid pipe located outside of the microwave chamber having an end attached to the fluid supply and an opposite end in fluid communication with the microwave chamber, the first fluid pipe operable to carry the thermal transfer fluid from the fluid supply to the microwave chamber, and a second fluid pipe located outside of the microwave chamber and having an end in fluid communication with the microwave chamber and a fluid exhaust located at an opposite end of the second fluid pipe, the second fluid pipe operable to carry the thermal transfer fluid away from the microwave chamber, and in response to a pressure differential between pressure inside the microwave chamber and pressure outside the microwave chamber caused by opening the first fluid pipe and the second fluid pipe, carrying the thermal transfer fluid from the fluid supply to the microwave chamber via the first fluid pipe such that the thermal transfer fluid flows into the casket, flows along the flow path, and flows out of the microwave chamber via the second fluid pipe. ### Claim 17 (depends on 16) The method of claim 16 further comprising the steps of: providing a pump within the microwave chamber proximate the inlet of the flow path; intaking and then propelling thermal transfer fluid located within the microwave chamber through the flow path with the pump; and re-circulating at least a portion of the fluid exiting the flow path within the microwave chamber by intaking and then propelling the at least a portion through the flow path with the pump. ### Claim 18 (depends on 16) The method of claim 16 further wherein the opposite end of the second fluid pipe is connected to the fluid supply such that the thermal transfer fluid flowing through the flow path and exiting the microwave chamber via the second fluid pipe re-circulates back to the fluid supply, and the method further comprising the steps of: providing a pump disposed in at least one of the first and second fluid pipes, wherein the pump propels the thermal transfer fluid away from the fluid supply and into the microwave chamber via the first pipe, along the flow path, and out of the chamber and back to the fluid supply via the second pipe. ### Claim 19 (depends on 15) The method of claim 15 wherein heat absorbed heat from a first portion of the heatable body is transferred to and heats a second portion of the heatable body as the thermal transfer fluid flows along the fluid flow path. ### Claim 20 (depends on 19) The method of claim 19 wherein the first portion of the heatable body is formed of a first material that has a first susceptance level and wherein the second portion of the heatable body is formed of a second material that has a second susceptance level that is different from the first susceptance level. ### Claim 21 (depends on 15) The method of claim 15 wherein the heatable body comprises a crucible and a mold. ### Claim 22 (depends on 15) The method of claim 15 wherein the heatable body is placed on top of a base plate of the casket and wherein the fluid flow path comprises a fluid directing structure configured for directing transfer fluid flowing across a surface of the base plate beneath at least a portion of the heatable body. ### Claim 23 (depends on 22) The method of claim 22 wherein the fluid directing structure is selected from the group consisting of: one or more channels formed in the base plate and one or more ridges formed on the base plate. ### Claim 24 (depends on 15) The method of claim 15 wherein the inlet is disposed in a top plate of the casket above the heatable body and wherein the outlet is disposed in a bottom plate of the casket below the heatable body. ### Claim 25 (depends on 15) The method of claim 15 wherein the outlet is disposed in a top plate of the casket above the heatable body and wherein the inlet is disposed in a bottom plate of the casket below the heatable body. ### Claim 26 (depends on 15) The method of claim 15 further comprising the steps of: providing a microwave chamber wall to form an enclosed microwave chamber, wherein the microwave casket and heatable body are disposed within the microwave chamber; providing a pump within the microwave chamber proximate the inlet of the flow path; intaking and then propelling thermal transfer fluid located within the microwave chamber through the flow path with the pump; and re-circulating at least a portion of the fluid exiting the flow path within the microwave chamber by intaking and then propelling the at least a portion through the flow path with the pump. ### Claim 27 (depends on 1) The microwave furnace of claim 1 wherein the thermal control system includes a pump for recirculating at least a portion of the thermal transfer fluid exiting the fluid flow path back through the fluid flow path and a vent for releasing off-gases out of the thermal control system. ### Claim 28 A microwave furnace comprising: a microwave casket having an inner surface forming an internal cavity, the microwave casket formed at least in part of a microwave transparent material; a heatable body disposed in the internal cavity of the casket having a crucible and a mold each formed at least in part of a microwave susceptor material such that the crucible is operable to heat in response to a microwave field to form molten metal from a metal charge positioned within the crucible and the mold is operable to heat in response to the microwave field for maintaining heat to the molten metal as the molten metal flows to the mold from the crucible; and a thermal control system including a fluid flow path disposed between the microwave casket and the heatable body along an exterior surface of both the crucible and the mold, the thermal control system operable to flow a thermal transfer fluid through the fluid flow path in at least one of a first direction to absorb heat from the crucible and transfer the absorbed heat along the fluid flow path to the mold and a second direction to absorb heat from the mold and transfer the absorbed heat along the fluid flow path to the crucible. ### Claim 29 (depends on 28) The microwave furnace of claim 28 wherein the crucible is formed at least in part of a first microwave susceptor material that has a first susceptance level and the mold is formed at least in part of a second microwave susceptor material that has a second susceptance level that is different from the first susceptance level. ### Claim 30 (depends on 28) The microwave furnace of claim 28 wherein the thermal control system is operable to selectively flow the thermal transfer fluid in both the first direction and the second direction.