US3607117A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Black liquor recovery boiler combustion and safety control system
Assignee: Rust Engineering Co
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Filing: 1969-07-28
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Granted: 1971-09-21
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Expires: 1989-07-28
Abstract
Abstract Recovery boiler operation is initiated by a control system responsive to selected preliminary conditions in the boiler. Once the boiler is in operation, a combustion system controls the total amount of air, black liquor, primary fuel and secondary fuel supplied to the recovery boiler to reduce explosion hazards. Actual primary and secondary fuel flow rates are added and a fuel-air demand signal is generated in proportion to the amount of air required to fully combust both fuels. A black liquor demand signal is added to the fuel-air demand signal to produce a total air demand signal which is compared to the actual rate of flow of combustion air to the boiler. A forced draft controller signal indicative of any difference between the total air demand and the actual airflow is applied to a circuit for controlling a forced draft fan to adjust the total airflow delivered to the boiler, which air is divided into primary air supplied to the reduction zone of the boiler and secondary air supplied to the oxidation zone. The flow of primary air to the reduction zone is automatically controlled in response to black liquor and primary fuel flow rates. The flow of secondary air to the combustion zone is selected automatically in response to the rate of flow of primary air. In the event certain boiler operation safety limits are exceeded, safety circuitry overrides the combustion system to initiate safety procedures which return the boiler operation to normal or shut down the boiler.
Inventors
- 👤 James Marlin Shaw
- 👤 Roy Roger Herbst
- 👤 Fred Endsley Fuller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 03:29
CPC Classifications
F; F23; F23G; F23G7/00; F23G7/04; D; D21; D21C; D21C11/00; D21C11/12; F23G5/00; F23G5/50; Y; Y10; Y10S; Y10S423/00; Y10S423/03
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
43 words
A unit according to claim 1 for recovering chemicals from black liquor, said unit further including: means responsive to a reduction of the air flow supplied by said air supply means for interrupting operation of said black liquor and auxiliary fuel supply means.
Claim 2
Dependent Claim
58 words
A unit according to claim 1 for recovering chemicals from black liquor, said unit further including: means responsive to a reduction of the airflow in said other conduits for interrupting the supply of auxiliary fuel from said auxiliary fuel supply means to prevent fuel from entering said chamber in the absence of sufficient air to combust the fuel.
Claim 3
Dependent Claim
88 words
A unit for recovering chemicals from black liquor, as recited in claim 1, in which said unit also comprises, means including a conduit for supplying auxiliary fuel to said first zone, and which further comprises: means in said last recited conduit for generating a fourth signal indicative of said auxiliary fuel being supplied to the first zone; said third signal generated by the summing means being the summation of said first, second, and fourth signals, and said flow control means being responsive to said first and fourth signals.
Claim 4
Dependent Claim
276 words
In a chemical process unit for burning black liquor to recover chemicals, said unit including a chamber having a reduction zone and an oxidation zone, means for feeding black liquor into said chamber means for burning auxiliary fuel in said oxidation zone, and means including a main input line, a first conduit to said reduction zone and a second conduit to said oxidation zone for supplying air to said chamber, the improvement in said unit which comprises: means for generating a signal indicative of black liquor demand; means for comparing said demand signal to the actual flow of black liquor into said chamber to regulate said black liquor feeding means; means in said main input line for generating a signal indicative of the total air supplied to said chamber; means responsive to said black liquor demand signal and the actual flow rate of auxiliary fuel for generating an air demand signal indicative of the total amount of air necessary to completely combust said black liquor and auxiliary fuel; means for comparing said total air signal to said air demand signal to regulate said air supply means; air flow control means responsive to said black liquor demand signal for supplying through said first conduit a first portion of said total air to said reducing zone to partially combust the black liquor in said zone; and means responsive to said air flow control means for continuously supplying the remainder of said total air through said second conduit to said oxidation zone to completely combust both said black liquor and any auxiliary fuel, said remainder beinG supplied to said oxidation zone even though no auxiliary fuel is being burned.
Claim 5
Dependent Claim
68 words
A chemical process unit according to claim 5 in which: said auxiliary fuel burning means includes a plurality of auxiliary fuel burners each having a wind box for supplying air to said oxidation zone; and means are provided for response to a decrease in the air flow in one of said wind boxes for interrupting the operation of the burner associated with said one of said wind boxes.
Claim 6
Dependent Claim
337 words
A unit for burning black liquor to recover chemicals and produce heat, said unit including a combustion chamber having a reduction zone and an oxidation zone, means for supplying primary fuel to said reduction zone, means for supplying secondary fuel to said oxidation zone, means for feeding black liquor into said chamber, and means for supplying air for combustion of the black liquor and the primary and secondary fuels, the improvement in said unit which comprises: means for producing a black liquor demand signal indicative of desired black liquor flow; means for comparing said black liquor demand signal to a signal indicative of actual black liquor flow to control said black liquor supply means; means for adding said black liquor demand signal and first and second signals indicative of the actual primary fuel flow and the actual secondary fuel flow to produce a total air demand signal; air-sensing means responsive to the total actual air flow to said chamber for producing an actual airflow signal; first means for comparing said total air demand signal and said actual airflow signal to generate a signal for controlling said air-feeding means to supply total air in excess of that required to completely burn both said fuels and said black liquor; means for summing said black liquor demand signal and said first primary fuel signal to produce a primary air demand signal indicative of the air required to completely combust said primary fuel and to partially combust said black liquor; second means for comparing a primary air signal indicative of actual primary airflow to said primary air demand signal to produce a primary air control signal; means responsive to said primary air control signal for distributing to said reduction zone air to completely combust said primary fuel and partially combust said black liquor; and means responsive to said primary air control signal for controlling the air flow to said oxidation zone to provide excess air in said oxidation zone to completely burn said primary and secondary fuels and said black liquor.
Claim 7
Dependent Claim
109 words
A unit according to claim 7, in which: said means for supplying primary fuel includes a primary fuel header and a plurality of separate primary fuel burners connected to said header; said means for supplying air includes a primary air manifold and a wind box for each of said primary fuel burners; means are provided for sensing the air flow in said primary manifold, said sensing means being effective to generate an override signal in response to reduced airflow in said primary manifold; and means are provided for response to said override signal for interrupting the flow of fuel from said primary fuel header to said primary fuel burners.
Claim 8
Dependent Claim
74 words
A unit according to claim 8, in which: said means for supplying secondary fuel includes a secondary fuel header and a plurality of secondary fuel burners connected to said secondary fuel header; and means are provided responsive to an interruption in the air flow from said air supply means for interrupting the flow of fuel in both said primary and secondary fuel headers and for discontinuing the operation of said black liquor feeding means.
Claim 9
Dependent Claim
144 words
A unit according to claim 7 in which; said means for supplying primary fuel includes at least one primary fuel burner which receives fuel from said primary fuel supply means; said means for supplying secondary fuel includes at least one secondary fuel burner which receives fuel from Said secondary fuel supply means; said first and second signals are generated in response to the respective flow of primary and secondary fuel in said primary and secondary burners; said air supply means includes a fan having an outlet duct spaced from said combustion chamber; said air-sensing means is responsive to the air flow in said outlet duct for producing said actual air flow signal; and means are provided for delaying said actual airflow signal prior to application thereof to said first comparing means to synchronize said actual air flow signal with said total air demand signal.
Claim 10
Independent Claim
421 words
A system for controlling combustion in a black liquor recovery unit wherein black liquor is burned to recover chemicals therefrom and to generate heat for producing steam and wherein primary fuel is burned for burning down a smelt bed and secondary fuel is burned for increasing the heat output of the unit, the unit including a combustion chamber having a reduction zone, an oxidation zone and a bottom for receiving the smelt bed, the unit further including a primary fuel burner adjacent said reduction zone, a secondary fuel burner adjacent said oxidation zone, a primary duct for supplying primary air to said primary burner, at least one additional duct for supplying air to said secondary burner and to said chamber, a fan for supplying combustion air to said primary and additional ducts and means for feeding black liquor to said chamber; said system comprising: means for measuring the flow of primary fuel to said primary burner to generate a first signal; means for measuring the flow of secondary fuel to said secondary burner to generate a second signal; means for generating a third signal in response to black liquor flow; means responsive to said first, second and third signals for generating a fourth signal indicative of the total air demand of said unit; means responsive to the total flow of air supplied by said fan for generating a fifth signal; means responsive to said fourth and fifth signals for controlling said fan to provide a total airflow sufficient to satisfy the total air demand; means responsive to said first and third signals for generating a sixth signal indicative of the amount of primary air required to fully combust the primary fuel and to partially combust the black liquor; means responsive to the primary airflow in said primary duct for generating a seventh signal indicative of actual primary air flow; comparison means responsive to said sixth and seventh signals for controlling the flow of primary air in said primary duct to provide the primary air required; means responsive to said comparison means for regulating the flow of air to said additional duct so that sufficient air is supplied to said secondary burner and said oxidation zone of said chamber for completely burning the secondary fuel and the black liquor; means for producing an eighth signal indicative of the black liquor demand of said unit; and black liquor control means responsive to said third and eighth signals for regulating said feeding means to supply the desired amount of black liquor to said chamber.
Claim 11
Dependent Claim
73 words
A combustion and safety system in accordance with claim 11, in which; means are provided responsive to an interruption in the operation of said fan for generating a safety control signal; and safety means are provided responsive to said safety control signal for turning off said primary and secondary fuel burners, said safety means being effective to override said black liquor control means for stopping the flow of black liquor to said chamber.
Claim 12
Dependent Claim
87 words
A combustion control system according to claim 11, in which: said means for generating said fifth signal measures total air flow at a selected location spaced from said chamber; said means for generating said first and second signal measure fuel flow rates adjacent the respective primary and secondary fuel burners; and means are provided for delaying said fifth signal to synchronize said fourth and fifth signals so that the total air flow measurement will correspond in time to the measurement of the primary and secondary fuel flow.
References Cited (Backward Citations)
US2143820A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-20 | 1975-03-22 | 1975-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-20 | 1979-03-22 | 1979-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-20 | 1983-03-22 | 1983-09-21 | $7700.00 | Window Closed / Lapsed |