US5069551A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus of measuring unburned carbon in fly ash
Assignee: Iowa State University Research Foundation Inc
•
Filing: 1989-11-24
•
Granted: 1991-12-03
•
Expires: 2009-11-24
Abstract
Abstract A method and apparatus are shown to measure unburned carbon particles in the exhaust of a combustor. Photoacoustic absorption spectrometry is employed to measure the presence of the unburned carbon. Especially helpful in these measurements is a vertically elongated photoacoustic cell in which high flow velocities are maintained to prevent particles from settling. These measurements are useful in determining the efficiency of coal-fired combustors.
Inventors
- 👤 Robert C. Brown
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 01:44
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/1702; G01N2021/1706; G01N21/01; G01N21/03; G01N21/05
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
82 words
A method for detecting loading of unburned carbon particles in the exhaust of coal-fired combustors using photoacoustic absorption spectroscopy to detect said unburned carbon, said method comprising: generating an excitation beam; directing said beam at said exhaust; generating photoacoustic signals by heat given off said particles in said exhaust when said beam contacts said particles; said signal detecting unburned carbon particles about 10 microns in diameter or larger; detecting photoacoustic signals generated; and determining carbon loading as a function of said signal.
Claim 2
Independent Claim
82 words
A method for detecting loading of unburned carbon particles in the exhaust of coal-fired combustors using photoacoustic absorption spectroscopy to detect said unburned carbon, said method comprising: generating an excitation beam; directing said beam at said exhaust; generating photoacoustic signals by heat given off said particles in said exhaust when said beam contacts said particles; said signal detecting unburned carbon particles about 10 microns in diameter or larger; detecting photoacoustic signals generated; and determining carbon loading as a function of said signal.
Claim 3
Independent Claim
97 words
A method for detecting loading of unburned carbon particles in the exhaust of coal-fired combustors using photoacoustic absorption spectroscopy to detect said unburned carbon, said method comprising; generating an excitation beam within a vertically elongated photoacoustic cell; directing said beam at said exhaust; said exhaust maintained at a fluctuation velocity in said cell at about 0.15 meters per second to about 0.4 meters per second; generating photoacoustic signals by heat given off said particles in said exhaust when said beam contacts said particles; detecting photoacoustic signals generated; and determining carbon loading as a function of said signal.
Claim 4
Independent Claim
97 words
A method for detecting loading of unburned carbon particles in the exhaust of coal-fired combustors using photoacoustic absorption spectroscopy to detect said unburned carbon, said method comprising; generating an excitation beam within a vertically elongated photoacoustic cell; directing said beam at said exhaust; said exhaust maintained at a fluctuation velocity in said cell at about 0.15 meters per second to about 0.4 meters per second; generating photoacoustic signals by heat given off said particles in said exhaust when said beam contacts said particles; detecting photoacoustic signals generated; and determining carbon loading as a function of said signal.
Claim 5
Dependent Claim
31 words
The method of claim 2 wherein an opening is provided into said photoacoustic cell to introduce gas to prevent said unburned carbon particles in said exhaust from settling within said cell.
Claim 6
Dependent Claim
55 words
An improvement in a photoacoustic cell to measure photoacoustic absorption spectroscopy, said improvement comprising: a vertically elongated cell for measuring unburned carbon particles in exhaust of coal-fired combustors; and means to maintain said exhaust of said combustors entering said cell at a velocity of about 0.15 meters per second to about 0.4 meters per second.
Claim 7
Dependent Claim
55 words
An improvement in a photoacoustic cell to measure photoacoustic absorption spectroscopy, said improvement comprising: a vertically elongated cell for measuring unburned carbon particles in exhaust of coal-fired combustors; and means to maintain said exhaust of said combustors entering said cell at a velocity of about 0.15 meters per second to about 0.4 meters per second.
Claim 8
Dependent Claim
35 words
The cell of claim 4 wherein an opening is provided in said cell and means to allow entrance of a gas through said opening to prevent settling of said unburned carbon particles from said exhaust.
Claim 9
Dependent Claim
34 words
The cell of claim 4 further comprising a means to determine mass loading of said unburned carbon particles as a function of the acoustic signal produced by said unburned carbon particles in said cell.
Claim 10
Independent Claim
105 words
A method for detecting loading of unburned carbon particles greater than 0.1 microns in diameter in the exhaust of coal-fired combustors using photoacoustic absorption spectroscopy to detect said unburned carbon, said method comprising: generating an excitation beam; directing said beam at said exhaust; generating photoacoustic signals by heat given off said particles in said exhaust when said beam contacts said particles said photoacoustic signals being calibrated to provide standard measurement; said signal detecting unburned carbon particles greater than 0.1 microns in diameter; detecting photoacoustic signals generated; and, comparing said signal to said standard measurements; and to determine carbon loading as a function of said signal.
Claim 11
Independent Claim
105 words
A method for detecting loading of unburned carbon particles greater than 0.1 microns in diameter in the exhaust of coal-fired combustors using photoacoustic absorption spectroscopy to detect said unburned carbon, said method comprising: generating an excitation beam; directing said beam at said exhaust; generating photoacoustic signals by heat given off said particles in said exhaust when said beam contacts said particles said photoacoustic signals being calibrated to provide standard measurement; said signal detecting unburned carbon particles greater than 0.1 microns in diameter; detecting photoacoustic signals generated; and, comparing said signal to said standard measurements; and to determine carbon loading as a function of said signal.
References Cited (Backward Citations)
US572A
Cited
US3614230A
Cited
US4436428A
Cited
US4303343A
Cited
US4516858A
Cited
US4740086A
Cited
US4622845A
Cited
US4722602A
Cited
US4808828A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-12-02 | 1995-06-03 | 1995-12-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-12-02 | 1999-06-03 | 1999-12-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-12-02 | 2003-06-03 | 2003-12-03 | $7700.00 | Window Closed / Lapsed |