US4223640A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fuel firing
Assignee: McDermott Technology Inc
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Filing: 1978-12-21
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Granted: 1980-09-23
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Expires: 1998-12-21
Abstract
Abstract An apparatus and method to permit the burning of high and varying moisture content fuels without requiring supplemental fuel (oil or gas) firing. The invention provides in-situ drying of the high and varying moisture content fuels by modulating the temperature of the combustion air entering the furnace (11) of the vapor generator (10). The variable flow paths taken by the air and flue gas are functions of the moisture content of the fuel being fired. The flue gas may be selectively by-passed around an economizer (20) for direct introduction into a first air heater (30). The gas is then passed through a precipitator (34) and a second air heater (40). Combustion air is passed through the second air heater (40) and may be then apportioned between the first air heater (30) and a by-pass (60) around the air heater (40) before introduction into the furnace (11).
Inventors
- 👤 Robert S. Rochford
- 👤 Robert S. Leckonby
- 👤 Ronald C. Lutwen
- 👤 Gerald A. Cymny
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 07:15
CPC Classifications
F; F23; F23L; F23L15/00; F22; F22B; F22B31/00; F22B31/08; Y; Y02; Y02E; Y02E20/00; Y02E20/34
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
188 words
In combination with a vapor generator having a furnace for burning fuels of varying moisture content, an apparatus for preheating air required for combustion and comprising conduit means defining an air and a flue gas flow path to and from the furnace, respectively, and economizer disposed in the gas flow path for preheating feedwater for the vapor generator, spaced first and second air heaters disposed downstream gas flow-wise of the economizer and communicating with the air and gas flow paths to heat the air through indirect heat exchange with the gas, the second air heater being disposed upstream air flow-wise and downstream gas flow-wise of the first air heater, means for regulating the air temperature including conduit means defining an air flow path by-passing the first air heater and a gas flow path by-passing the economizer, damper means for apportioning the flow of air between the first air heater and the by-pass air flow path and damper means for apportioning the flow of gas between the economizer and the by-pass gas flow path in response to changes in flue gas temperature resulting from changes in fuel moisture content.
Claim 2
Dependent Claim
188 words
In combination with a vapor generator having a furnace for burning fuels of varying moisture content, an apparatus for preheating air required for combustion and comprising conduit means defining an air and a flue gas flow path to and from the furnace, respectively, and economizer disposed in the gas flow path for preheating feedwater for the vapor generator, spaced first and second air heaters disposed downstream gas flow-wise of the economizer and communicating with the air and gas flow paths to heat the air through indirect heat exchange with the gas, the second air heater being disposed upstream air flow-wise and downstream gas flow-wise of the first air heater, means for regulating the air temperature including conduit means defining an air flow path by-passing the first air heater and a gas flow path by-passing the economizer, damper means for apportioning the flow of air between the first air heater and the by-pass air flow path and damper means for apportioning the flow of gas between the economizer and the by-pass gas flow path in response to changes in flue gas temperature resulting from changes in fuel moisture content.
Claim 3
Dependent Claim
34 words
The combination according to claim 1 wherein the air temperature regulating means includes a temperature sensing device extending into the furnace for detecting flue gas temperture changes resulting from changes in fuel moisture content.
Claim 4
Dependent Claim
23 words
The combination according to claim 1 including an electrostatic precipitator communicating with the gas flow path intermediate said first and second air heaters.
Claim 5
Dependent Claim
49 words
The combination according to claim 3 wherein the apparatus includes conduit means defining a feedwater flow path by-passing the economizer and valve means for apportioning the flow of feedwater between the economizer and the by-pass feedwater flow path to maintain the precipitator outlet gas temperature above a predetermined value.
Claim 6
Dependent Claim
54 words
The combination according to claim 4 wherein a temperature sensing means disposed downstream gas flow-wise of the precipitator regulates both the quantity of the flue gas by-passing the economizer and the quantity of the boiler feedwater by-passing the economizer to maintain the temperature of the flue gas exiting the precipitator above a predetermined value.
Claim 7
Dependent Claim
26 words
The combination according to claim 1 including a steam coil air heater disposed in the air flow path upstream air flow-wise of said second air heater.
Claim 8
Dependent Claim
16 words
The combination according to claim 1 wherein the first air heater is a tubular air heater.
Claim 9
Dependent Claim
16 words
The combination according to claim 1 wherein the second air heater is a regenerative air heater.
Claim 10
Independent Claim
144 words
A method for burning fuels of varying moisture content, and including a vapor generator furnace, an economizer for preheating feedwater for the vapor generator through indirect heat exhange with flue gas, spaced first and second air heaters for preheating combustion air in indirect heat exchange with flue gas, and conduit means for by-passing flue gas around the economizer and combustion air around the first air heater, which comprises the steps of: (a) detecting changes in flue gas temperature resulting from changes in fuel moisture content, (b) increasing the flue gas portion by-passing the economizer and decreasing the combustion air portion by-passing the first air heater in response to an increase in fuel moisture content, and (c) decreasing the flue gas portion by-passing the economizer and increasing the combustion air portion by-passing the first air heater in response to a decrease in fuel moisture content.
Claim 11
Independent Claim
144 words
A method for burning fuels of varying moisture content, and including a vapor generator furnace, an economizer for preheating feedwater for the vapor generator through indirect heat exhange with flue gas, spaced first and second air heaters for preheating combustion air in indirect heat exchange with flue gas, and conduit means for by-passing flue gas around the economizer and combustion air around the first air heater, which comprises the steps of: (a) detecting changes in flue gas temperature resulting from changes in fuel moisture content, (b) increasing the flue gas portion by-passing the economizer and decreasing the combustion air portion by-passing the first air heater in response to an increase in fuel moisture content, and (c) decreasing the flue gas portion by-passing the economizer and increasing the combustion air portion by-passing the first air heater in response to a decrease in fuel moisture content.
Claim 12
Dependent Claim
66 words
The method according to claim 9 and including an electrostatic precipitator disposed between the first and second air heaters for cleaning flue gas, conduit means for by-passing feedwater around the economizer, and comprising the steps of: (a) monitoring the precipitator gas outlet temperature, and (b) increasing the feedwater and flue gas portions by-passing the economizer to maintain the precipitator gas outlet temperature above a predetermined value.
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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) | 1983-09-23 | 1984-03-24 | 1984-09-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-09-23 | 1988-03-24 | 1988-09-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-09-23 | 1992-03-24 | 1992-09-23 | $7700.00 | Window Closed / Lapsed |