US4367686A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for operating a coal dust furnace and a furnace for carrying out the method
Assignee: Steag GmbH
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Filing: 1981-03-25
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Granted: 1983-01-11
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Expires: 2001-03-25
Abstract
Abstract A method for operating a coal dust furnace comprises blowing into the furnace a mixture of combustion air and combustion coal dust having a specified range of grain sizes, the range of grain sizes having an upper limiting grain size, and, for reducing the temperature of the flame, also blowing into the furnace additional temperature reducing coal dust, the range of grain sizes of the additional coal dust lying essentially above the specified upper limiting grain size, this temperature reducing coal dust subsequently being burnt in additional areas of the furnace. The two types of coal dust are blown into the furnace in concentric streams each surrounded by an annular stream of its associated combustion air. If the combustion coal dust is the central stream, then its combustion air is fed in a swirling stream.
Inventors
- 👤 Fritz Adrian
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 17:09
CPC Classifications
F; F23; F23C; F23C6/00; F23C6/04; F23C6/045; F23C6/047; F23D; F23D1/00; F23C2201/00; F23C2201/30; F23C2201/301
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
134 words
A method for operating a coal dust furnace with reduced formation of nitrogen oxides, comprising the steps of: blowing into the furnace a mixture of air and combustion coal dust having a specified range of grain sizes, the range of grain sizes having an upper limiting grain size, blowing into the furnace a swirling stream of combustion air surrounding said mixture; blowing into the furnace a mixture of combustion air and temperature reducing coal dust surrounding said swirling stream of combustion air, the range of grain sizes of the additional coal dust lying essentially above said upper limiting grain size; blowing into the furnace a non-swirling stream of combustion air surrounding said mixture of air and temperature reducing coal dust, and burning said temperature reducing coal dust in an afterburning area of the furnace.
Claim 2
Independent Claim
134 words
A method for operating a coal dust furnace with reduced formation of nitrogen oxides, comprising the steps of: blowing into the furnace a mixture of air and combustion coal dust having a specified range of grain sizes, the range of grain sizes having an upper limiting grain size, blowing into the furnace a swirling stream of combustion air surrounding said mixture; blowing into the furnace a mixture of combustion air and temperature reducing coal dust surrounding said swirling stream of combustion air, the range of grain sizes of the additional coal dust lying essentially above said upper limiting grain size; blowing into the furnace a non-swirling stream of combustion air surrounding said mixture of air and temperature reducing coal dust, and burning said temperature reducing coal dust in an afterburning area of the furnace.
Claim 3
Dependent Claim
42 words
A method according to claim 1, wherein the combustion coat dust is blown into the furnace with a near stoichiometric amount of combustion air, and wherein additional air is blown into the furnace for the afterburning of the temperature reducing coal dust.
Claim 4
Dependent Claim
30 words
A method according to claim 2, wherein the additional air for the afterburning of the temperature reducing coal dust is also blown into the furnace in a near stoichiometric amount.
Claim 5
Independent Claim
142 words
A method for operating a coal dust furnace with reduced formation of nitrogen oxides, comprising the steps of: blowing into the furnace a mixture of air and temperature reducing coal dust, blowing into the furnace a non-swirling stream of combustion air surrounding said mixture of air and temperature reducing coal dust, blowing into the furnace a mixture of air and combustion coal dust having a specified range of grain sizes, the range of grain sizes having an upper limiting grain size and the mixture surrounding said non-swirling stream of combustion air, blowing into the furnace a stream of combustion air surrounding said mixture of air and combustion coal dust, the range of grain sizes of the temperature reducing coal dust lying essentially above said upper limiting grain size and burning said temperature reducing coal dust in an afterburning area of the furnace.
Claim 6
Independent Claim
142 words
A method for operating a coal dust furnace with reduced formation of nitrogen oxides, comprising the steps of: blowing into the furnace a mixture of air and temperature reducing coal dust, blowing into the furnace a non-swirling stream of combustion air surrounding said mixture of air and temperature reducing coal dust, blowing into the furnace a mixture of air and combustion coal dust having a specified range of grain sizes, the range of grain sizes having an upper limiting grain size and the mixture surrounding said non-swirling stream of combustion air, blowing into the furnace a stream of combustion air surrounding said mixture of air and combustion coal dust, the range of grain sizes of the temperature reducing coal dust lying essentially above said upper limiting grain size and burning said temperature reducing coal dust in an afterburning area of the furnace.
Claim 7
Dependent Claim
42 words
A method according to claim 4, wherein the combustion coal dust is blown into the furnace with a near stoichiometric amount of combustion air, and wherein additional air is blown into the furnace for the afterburning of the temperature reducing coal dust.
Claim 8
Dependent Claim
30 words
A method according to claim 5, wherein the additional air for the afterburning of the temperature reducing coal dust is also blown into the furnace in a near stoichiometric amount.
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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) | 1986-01-10 | 1986-07-12 | 1987-01-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-01-10 | 1990-07-12 | 1991-01-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-01-10 | 1994-07-12 | 1995-01-11 | $7700.00 | Window Closed / Lapsed |