US 5,443,795 AGranted

Explosion proof microwave heated solvent extraction apparatus

AssigneeCEM Corporation

InventorRobert N. Revesz

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Abstract

An explosion proof microwave heated solvent extraction apparatus or system for extracting organic materials includes a pressure resistant microwave transmissive extraction container, which is preferably of reinforced polyetherimide lined with fluoropolymer, in a microwave radiation heated chamber, with a device for controlling a microwave radiation generator, such as a magnetron, in response to the presence of any solvent vapor in a collection container for rupture diaphragm discharged material from an extraction container or in exhaust gas from the chamber. The presence of the solvent in the collection container or exhaust gas is preferably detected by a semiconductor gas sensor which decreases its electrical resistance in the presence of solvent vapors, thereby increasing its voltage and thus controlling operation of the magnetron, turning it off when solvent vapor (and a potentially explosive gas mixture) is present. Also described are other explosion prevention systems, including a fluoropolymer sheet covering a chamber ceiling and ceiling light, and a process for safely extracting organic materials, utilizing the described apparatus.

Claims9

Dependent claims

An explosion proof microwave heated solvent extraction apparatus which comprises a source of microwave radiation, a walled chamber into which such microwave radiation is directed from said source, an outlet from said chamber through which gas can be withdrawn, a microwave transmissive extraction container in said chamber, adapted to contain, under pressure, liquid solvent extraction medium and material to be extracted by said solvent medium, safety rupture means associated with said extraction container, which rupture means ruptures when pressure in the container is above a predetermined safe limit and thereby releases solvent vapor from said container, a collection container in said chamber, into which collection container said released solvent vapor and any entrained liquid solvent, any entrained material to be extracted and any extracted material are directed and in which they are collected, gas exhausting means for removing gas from said chamber through said chamber outlet, which gas exhausting means also exhausts gas from the collection container, a solvent vapor detector for detecting a presence of solvent vapor in gas exiting said collection container and passing through said chamber outlet, which solvent vapor detector is located in the path of gas being removed from said chamber and controls operation of the source of microwave radiation by turning said source off when solvent vapor is detected by it, and a gas flow rate detector, which is located in the path of gas being removed from said chamber and controls operation of the source of microwave radiation by turning said source of radiation off when gas flow is halted.

Dependencies are inferred from the claim text.