US4245573A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Air heater corrosion prevention
Assignee: Chemed Corp
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Filing: 1978-12-22
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Granted: 1981-01-20
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Expires: 1998-12-22
Abstract
Abstract An additive, e. g., MgO.Mg silicate, is injected into the flue gas stream of a coal-or oil-fired furnace, at 2300-1700 deg. F., thereby reducing accumulation of sulfuric acid on the air heater inlet and outlet.
Inventors
- 👤 Shyam N. S. Dixit
- 👤 Douglas I. Bain
- 👤 David A. Carter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:11
CPC Classifications
C; C23; C23F; C23F15/00; B; B01; B01D; B01D53/00; B01D53/34; B01D53/46; B01D53/48; B01D53/50; B01D53/508; C10; C10L; C10L10/00; C10L10/04; F; F23; F23J; F23J15/00
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
79 words
Method of reducing corrosion of metal surfaces in an air heater in an industrial or utility fossil fuel furnace comprising injecting an additive into the furnace at a temperature in the range of 2300°-1700° F. at a rate of 0.05-10 lbs. additive/ton of fuel burned; the additive being essentially free of free alumina and consisting essentially of a combination of magnesium oxide and magnesium silicate in a weight ratio of from 2 to 1:1 of magnesia to magnesium silicate.
Claim 2
Dependent Claim
79 words
Method of reducing corrosion of metal surfaces in an air heater in an industrial or utility fossil fuel furnace comprising injecting an additive into the furnace at a temperature in the range of 2300°-1700° F. at a rate of 0.05-10 lbs. additive/ton of fuel burned; the additive being essentially free of free alumina and consisting essentially of a combination of magnesium oxide and magnesium silicate in a weight ratio of from 2 to 1:1 of magnesia to magnesium silicate.
Claim 3
Dependent Claim
15 words
Method according to claim 1 in which the temperature is 2200 to 2000 deg. F.
Claim 4
Dependent Claim
14 words
Method according to claim 2 in which the temperature is about 2200 deg. F.
Claim 5
Dependent Claim
21 words
Method according to claim 1 where the additive feed is at a rate of 0.5 to 1.5 lbs./ton of fuel burned.
Claim 6
Dependent Claim
13 words
Method according to claim 1 in which the magnesia:magnesium silicate ratio is 1.5:1.
Claim 7
Dependent Claim
11 words
Method according to claim 4 where the magnesia:magnesium silicate is 1.5:1.
Claim 8
Dependent Claim
11 words
Method according to claim 4 where the magnesium silicate is talc.
Claim 9
Dependent Claim
17 words
Method according to claim 1 in which the ratio is 1:1 and the magnesium silicate is talc.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1984-01-20 | 1984-07-21 | 1985-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-01-20 | 1988-07-21 | 1989-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-01-20 | 1992-07-21 | 1993-01-20 | $7700.00 | Window Closed / Lapsed |