초록 ▼

An explosion proof forced air electric heater is designed to supply heat to hazardous areas where the atmosphere contains readily combustible gases, vapors or dust particles. The heater employs an air mover which forces air through a metal heat sink with strategically placed electric heating element

An explosion proof forced air electric heater is designed to supply heat to hazardous areas where the atmosphere contains readily combustible gases, vapors or dust particles. The heater employs an air mover which forces air through a metal heat sink with strategically placed electric heating elements. The terminal ends of the heating elements extend into a sealed and encapsulated explosion proof containment chamber which is connected to a centralized explosion proof enclosure. The explosion proof enclosure contains the control features and the electrical connections of the heater along with external accessories. The heating cycle is controlled via an electronic control circuit. The electronic circuit controls the process heating temperature, air mover operation, heating element operation, temperature measuring device operation, and monitors the total operation time of the heating elements while providing process failure feed back to the operator.

대표청구항 ▼

1. An electric forced air heater particularly adapted to heat air in a hazardous area, comprising: a rectangular sheet metal cabinet having at least one intake opening through which air may be drawn and at least one exhaust opening through which heated air may be discharged;at least one explosion pr

1. An electric forced air heater particularly adapted to heat air in a hazardous area, comprising: a rectangular sheet metal cabinet having at least one intake opening through which air may be drawn and at least one exhaust opening through which heated air may be discharged;at least one explosion proof electric motor driven axial air mover for drawing air axially through at least one intake opening and discharging heated air axially through said at least one exhaust opening;at least one heat exchanger vertically mounted within said sheet metal cabinet to heat air drawn through said at least one intake opening, each of said at least one heat exchanger being formed of heat conducting metal tubes and fins having electric heating elements, an operating temperature monitoring device, and a predetermined hi limit temperature monitoring device inserted therein;said heat exchanger having electrical wires passing through a metal formed explosion proof expansion conduit union “C”, entering a metal formed explosion proof enclosure box, said metal formed explosion proof enclosure box housing potential explosion causing devices;said at least one explosion proof electric motor having said electrical wires passing through a metal formed explosion proof expansion conduit union “A”, passing through a metal formed explosion proof junction box and passing through a metal formed explosion proof expansion conduit union “B”, entering said metal formed explosion proof enclosure box;a multitude of louvers mounted to said sheet metal cabinet and positioned horizontally across said exhaust opening to direct discharged air. 2. Said at least one heat exchanger as claimed in claim 1 further comprising: headers press fit on said metal tubes, said headers flanked by header ends and covered with a header cover, forming an internal void, said internal void containing the electric heating element fastening terminals, said electric heating elements and said electric heating element fastening terminals connected via a bus bar embedded in an encapsulation compound, said encapsulation compound once cured, providing a protective hazardous area barrier. 3. Said encapsulation compound of claim 2 being of an electric insulating and heat conductive compound. 4. At least one heat exchanger as claimed in claim 2 exhibiting a cooler area in the center of said at least one heat exchanger, where axial airflow is limited from said axial air mover, said cooler area created by the use of a cooler heating source in the said cooler area within said electric heating elements. 5. Said operating temperature monitoring device as claimed in claim 1 monitoring the operating temperature of said at least one heat exchanger. 6. Said predetermined hi limit temperature monitoring device as claimed in claim 1 monitoring the predetermined hi limit shutdown temperature of said at least one heat exchanger. 7. Said metal formed explosion proof enclosure box as claimed in claim 1 further comprising: an electronic control circuit monitoring and controlling:pre programmed heating cycles, said at least one explosion proof electric motor, said electric heating elements, operating temperature of said at least one heat exchanger, said predetermined hi limit temperature of said at least one heat exchanger, the operating time of said electric heating elements, a predetermined hi limit internal temperature, the triggering of safety mechanisms, and relaying of said safety mechanisms events;a solid state relay controlling said at least one explosion proof electric motor;a solid state relay controlling said electric heating elements;an electric motor current transformer device monitoring the current of said at least one explosion proof electric motor;an electric heating element current transformer device monitoring the current of said electric heating elements;an enclosure internal predetermined hi limit temperature monitoring device, monitoring said predetermined hi limit internal temperature of said metal formed explosion proof enclosure box;an audible beeping device relaying said safety mechanisms events;a visual illumination device relaying said safety mechanisms events;a communications port communicating with said electronic control circuit;a thermostatic switch connection provision;a switch selecting either an “automatic on” or “continuous on” mode to provide controllability of said at least one explosion proof electric motor;an integral disconnect switch to disconnect power to all above said components. 8. The solid state relay of claim 7 can also be substituted for an electrical mechanical relay. 9. The communications port of claim 7 further comprising: communication between the end user and said electronic control circuit;remotely operating of said electric forced air heater;a computer interface for uploading heating cycle software and testing of said heating cycle software. 10. Said preprogrammed heating cycles of claim 7 further comprising: a heating cycle wherein said electronic control circuit receives a demand for heat signal, momentarily switching said solid state relay and engaging said at least one explosion proof electric motor with said axial air mover to determine the working condition of said at least one explosion proof electric motor, by transmitting a signal from said electric motor current transformer device to said electronic control circuit, wherein said at least one explosion proof electric motor is continuously monitored by said electric motor current transformer device through transmitting a signal to said electronic control circuit;said electronic control circuit, engaging said electric heating elements within said at least one heat exchanger by switching said solid state relay to start a preheat cycle, wherein said at least one heat exchanger is continuously monitored by said electric heating element current transformer device by transmitting a signal to said electronic control circuit;said operating temperature monitoring device which monitors the operating temperature of said electric heating elements within said at least one heat exchanger until a predetermined preheat temperature, wherein said at least one explosion proof electric motor of said axial air mover is engaged by switching said solid state relay, forcing cool air through said electric heating elements within said at least one heat exchanger and pushing heated air into the atmosphere until the demand for heat has been met and said electronic control circuit disengages said solid state relay, disengaging the power leading to said electric heating elements within said at least one heat exchanger, allowing said at least one explosion proof electric motor to remain engaged and said axial air mover operating until said at least one heat exchanger has cooled to a predetermined set temperature, as monitored by said temperature monitoring device, completing said heating cycle. 11. Said heating cycle as claimed in claim 10 including an elevated ambient temperature scenario comprising: an oscillating cycle occurring during said elevated ambient temperature scenario which triggers said at least one heat exchanger to reach said predetermined hi limit temperature and shutdown prior to reaching the demanded ambient temperature, wherein said electronic control circuit automatically triggers said oscillating cycle, where the said at least one heat exchanger temperature cycles between a predetermined upper and lower temperature limit, monitored by said operating temperature monitoring device until said demanded temperature has been met, completing said heating cycle. 12. The electronic control circuit of claim 7 wherein said safety mechanisms provide a safety shutdown of said electric forced air heater by disengaging the power leading to said at least one explosion proof electric motor and said electric heating elements, when triggered by an event comprising: an automatic shutdown when said electronic control circuit does not register a predetermined electrical current value from said electric motor current transformer device prior to said preheat cycle of said at least one heat exchanger due to failure of said at least one explosion proof electric motor, said electric motor current transformer device, or said solid state relay;an automatic shutdown when said electronic control circuit does not register a predetermined electric current from said electric motor current transformer device of said at least one heat exchanger during said heat cycle due to failure of said at least one explosion proof electric motor, said electric motor current transformer device, or said solid state relay;an automatic shut down when said electronic control circuit does not register a predetermined electrical current from said electric heating element current transformer device due to failure of said electric heating element, said electric heating element current transformer device, or said solid state relay;an automatic shutdown when said electronic control circuit does not register a signal from said operating temperature monitoring device due to failure of said operating temperature monitoring device;an automatic shutdown when said electronic control circuit does not register a signal from said predetermined hi limit safety temperature monitoring device due to failure of said predetermined hi limit safety temperature monitoring device;an automatic shutdown when said electronic control circuit registers a signal from said predetermined hi limit safety temperature monitoring device indicating said at least one heat exchanger has met said predetermined hi limit temperature and is overheating;an automatic shutdown when said electronic control circuit does not register a signal from said enclosure internal predetermined hi limit temperature monitoring device due to failure of said enclosure internal predetermined hi limit safety temperature monitoring device;an automatic shutdown when said electronic control circuit registers a signal from said enclosure internal predetermined hi limit safety temperature monitoring device indicating said metal formed explosion proof enclosure box has met said enclosure internal predetermined hi limit temperature and is overheating. 13. The electronic control circuit of claim 7 wherein said safety mechanisms elicit the relaying of an audible or visual signal to the operator by providing a predetermined sequenced beep from said audible beeping device, or a predetermined blinking sequence from said visual illumination device. 14. Said switch of claim 7 wherein the switch handle is mounted on the outside of said metal formed explosion proof enclosure box and the switching mechanism is mounted on the inside of said metal formed explosion proof enclosure box. 15. Said switch of claim 7 wherein said “automatic on” selection mode signals said at least one explosion proof electric motor with said axial air mover to operate according to said preprogrammed heating cycles. 16. Said switch of claim 7 wherein said “continuous on” selection mode signals said at least one explosion proof electric motor with said axial air mover to operate continuously, strictly providing air movement as part of a cooling cycle. 17. Said integral disconnect switch of claim 7 wherein the integral disconnect switch handle is mounted on the outside of said metal formed explosion proof enclosure box and the switching mechanism is mounted on the inside of said metal formed explosion proof enclosure box. 18. Said metal formed explosion proof junction box of claim 1 further comprising an optional thermostatic switch. 19. The axial air mover of claim 1 wherein said axial air mover can be substituted with any type of air mover. 20. Said metal formed explosion proof expansion conduit unions “A”, “B” and “C” of claim 1 wherein said metal formed explosion proof expansion conduit unions comprise: an inner and outer conduit telescoping on an axial plane, allowing for close tolerance fit, forming an explosion proof conduit.