US3743430A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light transmission monitor
Assignee: Shell USA Inc
•
Filing: 1971-11-12
•
Granted: 1973-07-03
•
Expires: 1991-11-12
Abstract
Abstract An opacity monitor for measuring the light transmissibility of gases in a furnace stack wherein a collimated light source is directed through the stack, a pair of photocells disposed to measure respectively the intensity of the source and the intensity of the light after it passes through the stack, the two measurements being balanced for normal conditions and the ratio of the two measurements being used as an indication of the opacity of the stack gas.
Inventors
- 👤 W Riggs
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 00:11
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/47; G01N21/49; G01N21/53; G01N21/534
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
156 words
An opacity monitor for monitoring the opacity of a gas flowing through a furnace stack comprising: a collimated light source disposed to direct a narrow beam of light across said stack; a first photocell detector disposed to measure the light transmitted across said stack and produce a first electrical signal related thereto, said first detector having sufficient surface area to intercept substantially all of the light transmitted across said stack; a second photocell detector disposed to measure the intensity of said light source before it passes through said stack and supply a second electrical signal related thereto, said second detector having sufficient surface area to intercept substantially all of the light directed towards said second detector; and circuit means including a pair of balanced amplifiers coupled to both said first and second photocell detectors, said amplifiers including means for individually adjusting their gain whereby the combined output of the amplifiers may be balanced under normal conditions.
Claim 2
Dependent Claim
156 words
An opacity monitor for monitoring the opacity of a gas flowing through a furnace stack comprising: a collimated light source disposed to direct a narrow beam of light across said stack; a first photocell detector disposed to measure the light transmitted across said stack and produce a first electrical signal related thereto, said first detector having sufficient surface area to intercept substantially all of the light transmitted across said stack; a second photocell detector disposed to measure the intensity of said light source before it passes through said stack and supply a second electrical signal related thereto, said second detector having sufficient surface area to intercept substantially all of the light directed towards said second detector; and circuit means including a pair of balanced amplifiers coupled to both said first and second photocell detectors, said amplifiers including means for individually adjusting their gain whereby the combined output of the amplifiers may be balanced under normal conditions.
Claim 3
Dependent Claim
22 words
The monitor of claim 1 and wherein said circuit means includes a dividing circuit for determining the ratio of said amplifier signals.
Claim 4
Dependent Claim
20 words
The monitor of claim 1 wherein said light source is a helium-neon laser source and said photocell detectors silicon photodiodes.
Claim 5
Dependent Claim
52 words
The monitor of claim 3 wherein said light source is directed across said stack and strikes said first silicon photodiode and a tilted window is disposed in the path of said light source to deflect a portion of said light onto said second silicon photodiode before the light passes through said stack.
Claim 6
Dependent Claim
19 words
The monitor of claim 4 wherein a purge means is provided for maintaining said window free of foreign deposits.
References Cited (Backward Citations)
US2878388A
Cited
US3528749A
Cited
US3447370A
Cited
US3526460A
Cited
US3664752A
Cited
US3645634A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-07-02 | 1977-01-01 | 1977-07-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-02 | 1981-01-01 | 1981-07-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-02 | 1985-01-01 | 1985-07-03 | $7700.00 | Window Closed / Lapsed |