Method and apparatus for monitoring particulate mass concentration of emissions from stationary sources

• US 4,229,653 A
• Filed: 03/30/1979
• Issued: 10/21/1980
• Est. Priority Date: 03/30/1979
• Status: Expired due to Term

• Current Assignee: SRI International, Inc.
• Original Assignee: SRI International, Inc.
• Inventors: Uthe, Edward E.
• Primary Examiner(s): Willis, Davis L.
• Application Number:
  US06/025,732
• Time in Patent Office: 571 Days
• Field of Search: 250/339, 250/340, 250/341, 250/343
• US Class Current: 250/338.1
• CPC Class Codes: G01N 21/534 by measuring transmission alone, i.e. determining opacity

Abstract

Method and apparatus for monitoring particulate mass concentration of emissions, such as fly ash, from a stationary source are disclosed which employ a single-wavelength infrared transmissometer. Emissions from a source, such as a fossil fueled power plant, generally contain particles of known material of a wide range of sizes. Often the particle size distribution varies during emission. In accordance with the present invention a single-wavelength transmissometer is employed which operates at a wavelength at which the extinction-to-mass concentration ratio as a function of particle size is substantially constant. Consequently, the transmissometer output provides a measure of the mass concentration of particulate material emitted from the source independent of the size of the particles. Logarithmic amplification of the transmissometer detector output provides a direct measure of the mass concentration.

Claims

1. A system for use in monitoring mass concentration of a stream of particulate material for which the particle size distribution may vary, said system comprising,

a source of electromagnetic radiation for directing a beam of radiation through the particulate stream,

radiation receiver means for measuring radiation from said radiation source transmitted through said particulate stream,

said radiation source being operated at substantially a single wavelength at which the extinction coefficient-to-mass concentration ratio of the particulate material stream is substantially independent of variations in particle size for the range of particle sizes in the stream whereby the output from the receiver means provides a measure of mass concentration of the particulate material stream.

2. A system as defined in claim 1 wherein said particulate material stream comprises particulate pollutants and said radiation source and receiver means operate at an appropriate infrared energy wavelength.

3. A system as defined in claim 1 wherein said radiation receiver means has a logarithmic response characteristic.

4. A system for use in monitoring mass concentration of a stream of particulate material for which the particle size distribution may vary, said particulate material stream comprising particulate pollution ranging in particle size up to a maximum of approximately 10 μ

m, said system comprising,

a source of electromagnetic radiation for directing a beam of radiation through the particulate stream,

radiation receiver means for measuring radiation from said radiation source transmitted through said particulate stream,

said radiation source being operated at substantially a single wavelength at which the extinction coefficient-to-mass concentration ratio of the particulate material stream is substantially independent of variations in particle size for the range of particle sizes in the stream whereby the output from the receiver means provides a measure of mass concentration of the particulate material stream, said radiation source and receiver means operating between 3 and 4 μ

m.

5. A system as defined in claim 4 wherein said receiver means includes a pyroelectric detector.

6. A system for use in monitoring mass concentration of a stream of particulate material for which the particle size distribution may vary, said system comprising,

a source of electromagnetic radiation comprising a helium-neon laser operating at a wavelength of substantially 3.39 μ

m for directing a beam of radiation through the particulate stream,

radiation receiver means for measuring radiation from said radiation source transmitted through said particulate stream,

said radiation source being operated at substantially a single wavelength at which the extinction coefficient-to-mass concentration ratio of the particulate material stream is substantially independent of variations in particle size for the range of particle sizes in the stream whereby the output from the receiver means provides a measure of mass concentration of the particulate material stream.

7. A method of measuring mass concentration of particulate material carried by a gaseous medium flowing through a conduit wherein the particulate material is of particle size distribution that can vary, said method comprising,

employing radiant energy source and radiant energy detector means to obtain a measure of radiant energy transmission through said particle-containing gaseous medium,

operating said radiant energy source and detector means at a single wavelength at which the extinction coefficient-to-mass concentration ratio is substantailly insensitive to particle size changes within the range of particle sizes flowing through the conduit whereby the measure of radiant energy transmitted provides a measure of mass concentration of particles independent of variations of particle sizes during said flow.

8. A method as defined in claim 7 wherein said radiant energy source and detector means are operated at a single infrared wavelength.

9. A method of measuring mass concentration of pollutant particulate material carried by a gaseous medium flowing through a conduit wherein the particulate material is of particle size distribution that can vary, said method comprising,

employing radiant energy source and radiant energy detector means to obtain a measure of radiant energy transmission through said particle-containing gaseous medium,

operating said radiant energy source and detector means at a single infrared wavelength between approximately 3 to 4 μ

m at which the extinction coefficient-to-mass concentration ratio is substantially insensitive to particle size changes within the range of particle sizes flowing through the conduit whereby the measure of radiant energy transmitted provides a measure of mass concentration of particles independent of variations of particle sizes during said flow.

10. A method as defined in claim 9 wherein the radiant energy source employed comprises a helium-neon laser operating at a wavelength of substantially 3.39 μ

m.