Title: Microwave plasma monitoring system for the elemental composition analysis of high temperature process streams

Abstract

Microwave-induced plasma for continuous, real time trace element monitoring under harsh and variable conditions. The sensor includes a source of high power microwave energy and a shorted waveguide made of a microwave conductive, high temperature capability refractory material communicating with the source of the microwave energy to generate a plasma. The high power waveguide is constructed to be robust in a hot, hostile environment. It includes an aperture for the passage of gases to be analyzed and a spectrometer is connected to receive light from the plasma. Provision is made for real time in situ calibration. The spectrometer disperses the light, which is then analyzed by a computer. The sensor is capable of making continuous, real time quantitative measurements of desired elements, such as the heavy metals lead and mercury. The invention may be incorporated into a high temperature process device and implemented in situ for example, such as with a DC graphite electrode plasma arc furnace. The invention further provides a system for the elemental analysis of process streams by removing particulate and/or droplet samples therefrom and entraining such samples in the gas flow which passes through the plasma flame. Introduction of and entraining samples in the gas flowmore » may be facilitated by a suction pump, regulating gas flow, gravity or combinations thereof. « less

Inventors:

Woskov, Paul P ^[1]; Cohn, Daniel R ^[2]; Titus, Charles H ^[3]; Surma, Jeffrey E ^[4]

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+ Show Inventor Affiliations

1. Bedford, MA
2. Chestnuthill, MA
3. Newtown Square, PA
4. Kennewick, WA

Issue Date:

1997-01-01

Research Org.:

Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

OSTI Identifier:

871157

Patent Number(s):

5671045

Assignee:

Masachusetts Institute of Technology (Cambridge, MA)

Patent Classifications (CPCs):

G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES

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G - PHYSICS G01 - MEASURING G01N - INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES

G01N21/73 - using plasma burners or torches

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DOE Contract Number:  

AC06-76RL01830

Resource Type:

Patent

Country of Publication:

United States

Language:

English

Subject:

microwave; plasma; monitoring; elemental; composition; analysis; temperature; process; streams; microwave-induced; continuous; time; trace; element; harsh; variable; conditions; sensor; source; power; energy; shorted; waveguide; conductive; capability; refractory; material; communicating; generate; constructed; robust; hot; hostile; environment; aperture; passage; gases; analyzed; spectrometer; connected; receive; light; provision; situ; calibration; disperses; computer; capable; quantitative; measurements; desired; elements; heavy; metals; lead; mercury; incorporated; device; implemented; example; dc; graphite; electrode; furnace; provides; removing; particulate; droplet; samples; therefrom; entraining; gas; flow; passes; flame; introduction; facilitated; suction; pump; regulating; gravity; combinations; removing particulate; process streams; plasma monitoring; trace element; heavy metal; refractory material; process stream; gas flow; microwave energy; heavy metals; microwave plasma; wave energy; hostile environment; temperature process; receive light; power microwave; spectrometer disperses; quantitative measurements; situ calibration; shorted waveguide; quantitative measure; composition analysis; microwave-induced plasma; elemental composition; variable conditions; time trace; element monitoring; quantitative measurement; electrode plasma; /356/333/