US3818872A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Economizer bypass for increased furnace wall protection
Assignee: Combustion Engineering Inc
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Filing: 1973-06-29
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Granted: 1974-06-25
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Expires: 1993-06-29
Abstract
Abstract An arrangement for protecting, at low loads, the furnace walls of a once-through steam generator system, having a recirculation loop, by increasing the mass flow of the working fluid flowing through the furnace wall tubes. A bypass for incoming feedwater is provided around the economizer allowing a lower temperature fluid to be delivered to and mixed with the fluid from the recirculation loop lowering the temperature of the fluid mixture. This results in a decrease in the specific volume of the mixed fluids; and since the recirculating pumps in the recirculation loop supply almost the same volumetric flow under all loads to the furnace wall tubes, the lower specific volume of the mixed fluid delivered to the pumps will yield a greater mass fluid flow to the furnace walls. The increased mass flow in turn results in improved heat transfer characteristics within the furnace walls thus reducing the likelihood of furnace wall damage due to overheating.
Inventors
- 👤 W Clayton
- 👤 W Schuetzenduebel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:02
CPC Classifications
F; F22; F22B; F22B29/00; F22B29/06; F22B29/12; F22D; F22D1/00; F22D1/02
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
247 words
In a once-through steam generator system comprising a furnace with fuel being burned therein establishing the flow of combustion gases therefrom, furnace wall tubes lining the walls of said furnace for radiant heat absorption from the burning fuel within said furnace, heat exchange means in the flow of combustion gases, a first conduit for conveying incoming working fluid into said heat exchange means, a control valve in said first conduit for controlling the flow of incoming working fluid, a second conduit for conveying said working fluid to said furnace wall tubes from within said heat exchange means, a third conduit for conveying the working fluid from said furnace wall tubes after passage therethrough, a fourth conduit providing a recirculation path for the working medium from said third conduit to said second conduit and pump means for recirculating at least a portion of the working fluid through said fourth conduit; an arrangement for protecting said furnace wall tubes comprising: bypass means for selectively bypassing at least a portion of the incoming working fluid around said heat exchange means so that said working fluid enters said furnace walls without being heated in said heat exchange means, said bypass means comprising a fifth conduit connected between said first conduit and said second conduit, a selectively operable valve means in said fifth conduit for regulating the flow therein, said pump means being located in said second conduit downstream of the connection of said fourth and fifth conduits with said second conduit.
Claim 2
Dependent Claim
247 words
In a once-through steam generator system comprising a furnace with fuel being burned therein establishing the flow of combustion gases therefrom, furnace wall tubes lining the walls of said furnace for radiant heat absorption from the burning fuel within said furnace, heat exchange means in the flow of combustion gases, a first conduit for conveying incoming working fluid into said heat exchange means, a control valve in said first conduit for controlling the flow of incoming working fluid, a second conduit for conveying said working fluid to said furnace wall tubes from within said heat exchange means, a third conduit for conveying the working fluid from said furnace wall tubes after passage therethrough, a fourth conduit providing a recirculation path for the working medium from said third conduit to said second conduit and pump means for recirculating at least a portion of the working fluid through said fourth conduit; an arrangement for protecting said furnace wall tubes comprising: bypass means for selectively bypassing at least a portion of the incoming working fluid around said heat exchange means so that said working fluid enters said furnace walls without being heated in said heat exchange means, said bypass means comprising a fifth conduit connected between said first conduit and said second conduit, a selectively operable valve means in said fifth conduit for regulating the flow therein, said pump means being located in said second conduit downstream of the connection of said fourth and fifth conduits with said second conduit.
Claim 3
Dependent Claim
23 words
The arrangement of claim 1 wherein said selectively operable valve means is located so as to be in parallel with said control valve.
Claim 4
Dependent Claim
40 words
The arrangement of claim 1 wherein automatic control means are provided to control said selectively operable valve means of said bypass means, said automatic control means responsive to a condition of the working fluid as it enters said furnace walls.
Claim 5
Dependent Claim
124 words
The arrangement of claim 3 wherein said automatic control means comprise a temperature sensing means sensing the temperature of the working fluid entering said furnace wall tubes, said means located downstream of the junction of said fourth conduit with said second conduit and said fifth conduit with said second conduit and upstream of said pump means, controller means receiving a signal from said temperature sensing means indicating temperature of the working fluid, said controller means also receiving a Set Point signal indicating the desired working fluid operating temperature, said controller means operative in response to the difference between said received signal to control the regulative position of said selectively operable valve means over at least a portion of the steam generator operating load range.
Claim 6
Independent Claim
143 words
A method of operating a once-through steam generator system having a furnace, furnace wall tubes lining the walls of the furnace for radiant heat absorption, and an economizer, the steps comprising: establishing a through-flow of incoming working fluid through said economizer and said furnace wall tubes, recirculating a portion of the flow from the outlet of the furnace wall tubes to the entrance of the furnace wall tubes, mixing the recirculated flow and the through-flow upstream of the furnace walls and downstream of the economizer, firing fuel in said furnace thereby increasing the temperature of the mixed working fluid passing through said furnace wall tubes, bypassing at least a portion of the incoming working fluid through-flow around said economizer, regulating said bypassed portion so that the amount of flow bypassed around said economizer is substantial at low loads and discontinued at high loads.
Claim 7
Independent Claim
143 words
A method of operating a once-through steam generator system having a furnace, furnace wall tubes lining the walls of the furnace for radiant heat absorption, and an economizer, the steps comprising: establishing a through-flow of incoming working fluid through said economizer and said furnace wall tubes, recirculating a portion of the flow from the outlet of the furnace wall tubes to the entrance of the furnace wall tubes, mixing the recirculated flow and the through-flow upstream of the furnace walls and downstream of the economizer, firing fuel in said furnace thereby increasing the temperature of the mixed working fluid passing through said furnace wall tubes, bypassing at least a portion of the incoming working fluid through-flow around said economizer, regulating said bypassed portion so that the amount of flow bypassed around said economizer is substantial at low loads and discontinued at high loads.
Claim 8
Dependent Claim
94 words
The method of claim 5 wherein the step of regulating said bypassed portion comprises the steps: sensing the temperature of the mixed working fluid flow as it enters the furnace walL tubes, comparing the sensed temperature to an optimum desired temperature, controlling the bypassed flow portion during load operation up to 30 percent of full load according to the difference between the sensed temperature and the desired temperature so that the flow around said economizer may be increased, and discontinuing said bypassed flow portion during operating load conditions above 30 percent of full load.
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) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |