Cem Corporation

David A Barclay

William Edward Jennings

Joseph Joshua Lambert

David L Herman

Edward Earl King

Ali Regimand

Gary Roger Greene

Wyatt Hargett, Jr

Dennis Palmer Manchester

A venting cap is disclosed for pressure vessels for microwave-assisted chemistry. The venting cap includes a flexible circular cover for closing the mouth of a reaction vessel, a flexible annular wall depending from the circular cover, and a flexible annular ring at the bottom of the annular wall and parallel to the circular cover for positioning the cap on a reaction vessel. At least one indentation in the circular cover minimizes distortion when any contents of a reaction vessel exert pressure against the cap, and at least one opening in the annular wall provides a ventilation path through the cap when gas pressure in a reaction vessel flexes the cap sufficiently to partially disengage at least a portion of the cap from the mouth of the reaction vessel.

Pressure stepped microwave assisted digestion

An instrument and method for high pressure microwave assisted chemistry are disclosed. The method includes the steps of applying microwave radiation to a sample in a sealed vessel while measuring the temperature of the sample and measuring the pressure generated inside the vessel and until the measured pressure reaches a designated set point, opening the vessel to release gases until the pressure inside the vessel reaches a lower designated set point, closing the vessel, and repeating the steps of opening the vessel at designated pressure set points and closing the vessel at designated pressure set points to the sample until the sample reaction reaches a designated high temperature. The designated set points can controllably differ from one another as the reaction proceeds. Microwave energy can be applied continuously or intermittently during the opening and closing steps. The apparatus includes a microwave cavity, a microwave transparent pressure resistant reaction vessel in the cavity, a cap on the reaction vessel, a pressure sensor for measuring pressure in the vessel, a temperature sensor, and means for opening and closing the cap at predetermined pressure set points measured by the pressure sensor to release pressure from the vessel.

A method of conducting microwave-assisted high pressure high temperature chemistry is disclosed. The method includes the steps of digesting a sample in a strong acid at a temperature of at least 200&#xb0; C. in a pressure resistant vessel that includes a lid while exerting a defined force against the lid in order to maintain gases under pressure in the vessel; directing gas under excess pressure from the vessel into a circumferential passage defined by the vessel and its pressure resistant lid; and directing the gas from the circumferential passage outwardly from the lid while preventing gas from flowing outwardly over the edge of the vessel.

High temperature high pressure vessel for microwave assisted chemistry

A vessel assembly is disclosed for high pressure high temperature chemistry. The vessel assembly includes a cylindrical vessel and a cylindrical vessel seal cover. The vessel and the seal cover have respective surfaces that, when engaged, define a circumferential interior passage between the vessel and the seal cover. A pressure release opening in the seal cover is in fluid communication with the circumferential passage. A retaining ring surrounds the vessel and the seal cover at the position where the vessel and the seal cover meet to maintain an outer circumferential engagement between the seal cover and the vessel when pressure forces gases in the vessel to flow into the circumferential passage and then outwardly from the pressure release opening.

A method of microwave assisted chemistry is disclosed in which power can be supplied more continuously at preferred power levels to more precisely control or moderate a chemical reaction. The method comprises measuring the duty cycle required to maintain a measured selected parameter of a sample at a predetermined set point while the sample is being exposed to microwave radiation at a first predetermined power level; and moderating the duty cycle and the applied microwave power to increase the on time of the duty cycle while applying power at a second predetermined power level that is sufficient to maintain the sample at the set point using the moderated duty cycle. A corresponding device for microwave assisted chemistry is also disclosed and comprises a cavity for receiving a sample, a waveguide connected to the cavity, a source of microwave radiation connected to the waveguide, and a switching power supply for driving the source of microwave radiation.

Use of continuously variable power in microwave assisted chemistry

A method and apparatus are disclosed for analyzing the aggregate content of asphalt-aggregate compositions. The method includes placing a preheated, preweighed container carrying a sample of an asphalt-aggregate composition into a preheated furnace with the preheated furnace being warmer than the preheated sample, continuing to heat the furnace while drawing air through the furnace at a rate that avoids impeding the heating of the furnace or the sample until the sample in the container reaches its combustion temperature and the combustion of the sample becomes exothermic, initiating a second draw of air around rather than through the furnace to moderate the exterior temperature of the furnace, accelerating the draw through the furnace to increase the rate of combustion of the exothermic reaction, and reweighing the container and sample after combustion is complete. The apparatus includes a furnace, a housing around the furnace, a furnace exhaust in communication with the furnace, a housing exhaust in communication with the housing, means for drawing an airflow though the furnace and into the furnace exhaust, means for drawing a separate airflow though the housing and into the housing exhaust, and a junction between the exhausts that forms a common exhaust from the housing and the furnace.

Microwave apparatus and method for analysis of asphalt-aggregate compositions

A method and apparatus are disclosed for analyzing asphalt-aggregate compositions. The method includes directing sufficient microwave radiation from a microwave source to a sample of an asphalt-aggregate composition to ignite the asphalt in the composition and to thereafter entirely combust the asphalt in the sample. The apparatus includes a source of microwave radiation, a cavity in communication with the microwave source, a sample holder in the cavity for holding a sample of an asphalt-aggregate composition during exposure to microwaves from the source, thermal insulation between the sample holder and the remainder of the cavity, and means for minimizing or eliminating any undesired combustion products generated by the burning asphalt.

A method for microwave assisted chemical processes is disclosed that comprises applying sufficient microwave radiation to a temperature-monitored mixture of reagents, with at least one of the reagents being thermally responsive to electromagnetic radiation in the microwave range, and based on the monitored temperature, to maintain the added reagents at or closely about a predetermined temperature while substantially avoiding thermal dilution (or before substantial thermal dilution can occur) that otherwise would have been caused by the addition of the reagents to one another.

Microwave assisted chemical processes

A microwave processing system is disclosed. The system is particularly useful for concurrently controlling a plurality of chemical reactions from a single microwave source. The system comprises a source that produces electromagnetic radiation in the microwave range; a waveguide in communication with the source and into which the source propagates microwave radiation; a resonator in communication with the waveguide; and an adjustable dynamic moderating device between the waveguide and the resonator for moderating the wave energy passing from the waveguide to the resonator without substantially changing the propagated mode in the waveguide.

Growing community of inventors

Charlotte, NC, United States of America

David A Barclay