Patent US3690636A successfully refreshed from Google Patents.
US3690636A
Expired / Lapsed
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Recuperative furnaces
Assignee: United States Steel Corp
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Filing: 1970-12-03
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Granted: 1972-09-12
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Expires: 1990-12-03
Abstract
Abstract Recuperative furnaces, such as soaking pits, have recuperators formed of sets of ceramic tiles arranged end to end with aligned holes in each set of tiles forming one series of passages for the flue gas and openings between the sets of tiles forming a second series of passages for the air to be heated. The heated air from the recuperator is directed through an air tunnel to an entry or burner port where it is mixed with coke oven gas or other fuel. Combustion is completed in the combustion or heating chamber which also receives the ingots to be heated. The burnt gases pass from the chamber through a flue gas port to the recuperator. It is impossible to maintain a gas tight connection between the tile. To prevent air leakage into the flue gas passages and increase fuel efficiency and production the entry port area is made at least approximately 75 percent (preferably 100 percent) of the cross sectional area of the air tunnel and the flue port area is made at least approximately 75 percent (preferably 100 percent) of the total cross sectional area of the flue gas passages in the recuperator.
Inventors
- 👤 Robert A Shannon
- 👤 Charles A Waters
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 10:28
CPC Classifications
F; F28; F28F; F28F21/00; F28F21/04; C; C21; C21B; C21B9/00; C21B9/02; C21B9/06
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
150 words
In a furnace having a combustion chamber, a recuperator formed of seTs of ceramic tiles arranged end to end with aligned holes in each set of tiles forming one series of passages and openings between the sets of tiles forming a second series of passages, an entry port to said combustion chamber for receiving air from said recuperators and fuel, means for delivering air to one end of one of said series of passages, an air tunnel connecting the other end of said air passages to said entry port, and a flue gas port for receiving burnt gases from said combustion chamber and delivering it to the other of said passages; the improvement comprising an entry port area at least approximately 75 percent of the area of said air tunnel, and a flue gas port area at least approximately 75 percent of the total area of said flue gas passages.
Claim 2
Dependent Claim
150 words
In a furnace having a combustion chamber, a recuperator formed of seTs of ceramic tiles arranged end to end with aligned holes in each set of tiles forming one series of passages and openings between the sets of tiles forming a second series of passages, an entry port to said combustion chamber for receiving air from said recuperators and fuel, means for delivering air to one end of one of said series of passages, an air tunnel connecting the other end of said air passages to said entry port, and a flue gas port for receiving burnt gases from said combustion chamber and delivering it to the other of said passages; the improvement comprising an entry port area at least approximately 75 percent of the area of said air tunnel, and a flue gas port area at least approximately 75 percent of the total area of said flue gas passages.
Claim 3
Dependent Claim
35 words
A furnace according to claim 1 in which the pressure drop from the air passages to the flue gas passages at the chamber end of the recuperator is a maximum of 0.025 inches of water.
Claim 4
Dependent Claim
44 words
A furnace according to claim 1 in which the entry port area is at least as great as the area of said air tunnel and the flue gas port area is at least as great as the total area of said flue gas passages.
Claim 5
Dependent Claim
36 words
A furnace according to claim 3 in which the pressure drop from the air passages to the flue gas passages at the chamber end of the recuperator is a maximum of approximately 0.025 inches of water.
Claim 6
Dependent Claim
36 words
A furnace according to claim 3 in which the pressure drop from the air passages to the flue gas passages at the chamber end of the recuperator is a maximum of approximately 0.015 inches of water.
Claim 7
Dependent Claim
77 words
A furnace according to claim 1 in which the combustion chamber is a pit for receiving steel ingots, said entry port extends downwardly from said pit, said flue gas port is in two sections one in each of two opposed side walls of said pit, said recuperator is in two sections one connected to each of said gas port sections and said air tunnel is in two sections one extending between each recuperator and said entry port.
Claim 8
Dependent Claim
36 words
A furnace according to claim 6 in which the pressure dee from the air passages to the flue gas passages at the chamber end of the recuperator is a maximum of approximately 0.025 inches of water.
Claim 9
Dependent Claim
37 words
A furnace according to claim 7 including a vertical pipe below and in vertical alignment with said entry port, and means on the top of said pipe for directing gas outwardly at an angle from the vertical.
Claim 10
Dependent Claim
44 words
A furnace according to claim 8 in which the entry port area is at least as great as the area of said air tunnel and the flue gas port area is at least as great as the total area of said flue gas passages.
Claim 11
Dependent Claim
36 words
A furnace according to claim 9 in which the pressure drop from the air passages to the flue gas passages at the chamber end of the recuperator is a maximum of approximately 0.015 inches of water.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-09-12 | 1976-03-13 | 1976-09-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-09-12 | 1980-03-13 | 1980-09-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-09-12 | 1984-03-13 | 1984-09-12 | $7700.00 | Window Closed / Lapsed |