US4352747A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method to lower fly-ash resistivity
Assignee: WR Grace and Co Conn
•
Filing: 1979-03-30
•
Granted: 1982-10-05
•
Expires: 1999-03-30
Abstract
Abstract A mixture of an alkyl amine, e.g., tri-n-propylamine and an SO3-containing acid, preferably, sulfamic acid is injected into the flue gas stream of a coal-fired utility boiler to reduce the electrical resistivity of the fly-ash particles and to increase their mean particle size, thereby improving their recovery by electrostatic precipitation or by mechanical separation, with consequent reduction in stack emissions.
Inventors
- 👤 Richard L. Every
- 👤 Franklin D. Lewandowski
- 👤 Jerome F. Lech
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 09:33
CPC Classifications
B; B01; B01D; B01D51/00; B01D51/02; B03; B03C; B03C3/00; B03C3/01; B03C3/013
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
140 words
In the addition of an additive of amine and a member of the group consisting of sulfuric or sulfamic acid and ammonium salts thereof to a coal fired utility boiler having heat exchangers and fly-ash collectors, the improvement comprising making the addition in the zone between the heat exchangers and the fly-ash collectors at a temperature of about 300°-500° F. thereby reducing electrical resistivity of the fly-ash particles and increasing their mean particle size without fouling heat exchange surfaces with the additive; the additive being added at the rate of about 0.05 to 0.70 pounds, active basis, per short ton of coal burned; and the amine having the formula: ##STR2## in which R 1 , R 2 , and R 3 are each independently selected from the group consisting of H and alkyl, in which alkyl has about 1-8 carbons.
Claim 2
Dependent Claim
140 words
In the addition of an additive of amine and a member of the group consisting of sulfuric or sulfamic acid and ammonium salts thereof to a coal fired utility boiler having heat exchangers and fly-ash collectors, the improvement comprising making the addition in the zone between the heat exchangers and the fly-ash collectors at a temperature of about 300°-500° F. thereby reducing electrical resistivity of the fly-ash particles and increasing their mean particle size without fouling heat exchange surfaces with the additive; the additive being added at the rate of about 0.05 to 0.70 pounds, active basis, per short ton of coal burned; and the amine having the formula: ##STR2## in which R 1 , R 2 , and R 3 are each independently selected from the group consisting of H and alkyl, in which alkyl has about 1-8 carbons.
Claim 3
Dependent Claim
13 words
Method according to claim 1 in which the temperature is about 400°-450° F.
Claim 4
Dependent Claim
24 words
Method according to claim 1 in which the additive is an aqueous solution of about equal parts by weight of tri-n-propylamine and sulfamic acid.
Claim 5
Dependent Claim
23 words
Method according to claim 3 in which the additive consists essentially of 88 parts water, 6 parts tri-n-propylamine, and 6 parts sulfamic acid.
Claim 6
Dependent Claim
21 words
Method according to claim 1 in which the weight ratio of (amine plus acid):coal is about 0.05 to 0.70 pounds:short ton.
Claim 7
Dependent Claim
14 words
Method according to claim 5 in which the ratio is about 0.10 to 0.30:1.
Claim 8
Dependent Claim
26 words
Method according to claim 6 in which the amine is tri-n-propylamine, the acid is sulfamic acid, and the (amine plus acid):coal ratio is 0.26 pounds:short ton.
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) | 1985-10-04 | 1986-04-05 | 1986-10-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-10-04 | 1990-04-05 | 1990-10-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-10-04 | 1994-04-05 | 1994-10-05 | $7700.00 | Window Closed / Lapsed |