US3243116A - Combustion control by means of smoke density - Google Patents

Combustion control by means of smoke density Download PDF

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Publication number
US3243116A
US3243116A US288001A US28800163A US3243116A US 3243116 A US3243116 A US 3243116A US 288001 A US288001 A US 288001A US 28800163 A US28800163 A US 28800163A US 3243116 A US3243116 A US 3243116A
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United States
Prior art keywords
signal
fuel
smoke
flow
controller
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Expired - Lifetime
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US288001A
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English (en)
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Jacob S Dijt
Hoeksema Haje
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Shell USA Inc
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Shell Oil Co
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/003—Systems for controlling combustion using detectors sensitive to combustion gas properties
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/18—Systems for controlling combustion using detectors sensitive to rate of flow of air or fuel

Definitions

  • the invention relates to a method and apparatus for automatic control of the combination process in a heating or an' evaporation apparatus. More particularly, this invention relates to a method and apparatus wherein signals arising from the measured values of the fuel flow or of the air flow or of both of them, of one or more variables of the heated or evaporated medium, and of the smoke in the combustion gases are utilized to adjust the fuel-air ratio to a value which results in the most economical operation of the system to produce a desired result.
  • A-second system utilizing a signal derived from the smoke in the combustion gases is shown in commonly assigned United States patent application Serial No. 134,396, filed 'August 28, 1961, now Patent No. 3,184,686.
  • the signal for the control of the fuel flow is derived from the measured temperature or pressure of the heated or evaporated medium while the air flow is controlled by an optimizing controller, likewise under the influence of the signal derived from the measured temperature or pressure of the heated or evaporated medium.
  • an optimizing controller Whenever the smoke density in the combustion gases rises above a certain predetermined value a signal indicating this fact is supplied to the optimizing controller which then varies the air flow.
  • the optimizing controller causes the air flow to increase and decrease continually, so that the system is constantly oscillating relative to the desired value.
  • the above objects of this invention are achieved by controlling the ratio of the fuel flow to the air flow by signals derived from the measured values of at leastone of these flows and of the smoke in the combustion gases.
  • the control of, for instance, the air flow under the infiuenceof a signal derived from the fuel fiow willeven if the latter varies rapidly-provide for an immediate rough adaptation of the air't-o the fuelflow, while after that the signal from the smoke density meter regulates the fuel/air ratio in such a way that'a high combustion efliciency is reached with little smoke formation.
  • the fuel flow in turn is controlled by a variable of the medium which has been heated in the system. This variable may for example be the temperature of a heated liquid, the steam pressure of an evaporated substance or any-other variable property of a heated medium which can be directly related to the amount of heat applied to the medium.
  • FIGURE 1 is a schematic diagram of a heating system controlled according to the invention wherein the air flow is controlled by signals proportional to the fuel flow and the smoke in the combustion gases;
  • FIGURE 2 is a schematic diagram of a heating system controlled by a modification of the invention in which the air flow is controlled by signals proportional to the fuel flow, the air flow and the smoke in the combustion gases;
  • FIGURE 3 is a schematic diagram of a heating system controlled by a further modification of the invention wherein the air flow is controlled by signals proportional to a variable of the heated medium, the air fiow and the smoke in the combustion gases.
  • FIGURE 1 there is shown a furnace 1 containing a pipe system 2 through which a liquid to be heated is continuously flowing.
  • the liquid in pipe system 2 is continuously heated by means of a burner 3 which is supplied by fuel through a pipe or conduit 4.
  • Air for combustion is supplied to the burner 3 via a pipe or conduit 5.
  • the combustion gases escape from the furnace through a flue or stack 6.
  • the quantity of fuel supplied to the burner 3 via pipe 4 is controlled by a control valve 7 having a valve operator 8 which positions the control valve 7 in accordance with a signal proportional to a desired parameter or variable of the output from the furnace 1.
  • the derived variable is the temperature of heated liquid flowing in the pipe system 2. It is understood, however, that in other applications, other variables may be measured, e.g., in a steam boiler, the desired output variable would be the steam pressure.
  • a transducer 9 is suitably connected in the output side of the pipe system 2.
  • the transducer 9 produces a signal proportional to the temperature of the liquid in the pipe system 2 and supplies the signal to one input of a conventional controller 10.
  • a variable external signal 11 which is preset, e.g., manually, to a value proportional to the desired temperature for the liquid in the pipe system 2.
  • the controller 10 compares the two input signals and produces an output signal proportional to the difference between the two input signals.
  • the output signal from the controller 10 is then applied to the valve operator 8 which then further opens or further closes the valve 7 according to whether the signal proportional to the temperature of the heated liquid is less than or greater than the preset external signal. Should the two input signals to the controller 10 be equal, then the output signal from the controller 10 will leave the valve 7 in its present position.
  • a control valve 12 having a valve operator 13 is inserted in the air supply pipe 5.
  • the valve operator 13 adjusts the valve 12 in response to both the flow of fuel in pipe 4 and the density of smoke in the combustion gases.
  • a flow meter 14 In order to measure the flow of the fuel in pipe 4, a flow meter 14, or other suit-able device which produces a signal proportional to flow, e.g., a pressure gage, is iiiserted in the fuel supply pipe 4.
  • the output signal from the flow meter 14 is supplied to one input of a combining circuit 15 which may, for example, be an adding or a multiplying circuit.
  • a signal related to the quantity of smoke in the combustion gases is supplied to the second input of the combining circuit 15.
  • the signal related to the quantity of smoke in the combustion gases is measured by means of a smoke density meter 16 which is suitably connected to the furnace stack 6.
  • the signal from the smoke density meter 16 which is proportional to the density or quantity of smoke in the combustion gases, is supplied as one input to a controller 17 which preferably is of the type which will integrate the signals from the smoke density meter over a short period of time.
  • the controller 17 compares the smoke density signal to a preset external signal 18 and produces an output signal proportional to the ditference.
  • the output signal from ti t: Controller 17 is then 4 f applied as the second input to the combining circuit 15 where it is combined with the fuel flow signal and then applied to the control valve operator 13 which then adjusts the control valve 12 to the optimum fuel-air ratio.
  • the external signal 18 should be set at such a value that the air flow will be adjusted to produce no smoke in the combustion gases, there is a risk when trying to adjust the system to this condition of the air flow control becoming adjusted to an excess of air.
  • the signal 18 is preferably set at a value such that the controller 17 adjusts the air flow so that the desired amount of smoke formation is a small value other than zero.
  • FIGURE 2 there is shown a second modification of a control system according to the invention.
  • reference numbers which are the same as those in FIGURE 1 denote like parts.
  • the liquid in the pipe system 2 is heated in the furnace 1 and the fuel flow is adjusted in response to a signal proportional to the temperature of the heated liquid from the transducer 9 via the controller 10, control valve operator 8 and control valve 7.
  • a signal proportional to the air flow is used in addition to the signals proportional to the fuel flow and the quantity of smoke in the combustion gases.
  • a flow meter 21, or other suitable flow measuring device is inserted in the fuel supply pipe 5.
  • the signals from the fuel flow meter 14 and the air flow meter 21 are then supplied to a ratio controller 22 which determines the fuel-air ratio, compares the ratio to a set point value corresponding to the desired fuel-air ratio, and supplies an out-put signal proportional to the difference between the actual fuel-air ratio and the set point value.
  • the output signal from the ratio controller 22 is then applied to valve operator 13 which then further opens or further closes control valve 12 depending on whether the actual fuel-air ratio is greater than or less than the set point value.
  • a signal related to the amount of smoke in the combustion gases is supplied to the ratio controller 22 via the smoke density meter 16 and the controller 17.
  • the signal from the controller 17 varies the set point value of the ratio controller 22 and thereby further adjusts the air flow to a value which will result in the smoke formation being reduced to the desired quantity.
  • FIGURE 3 there is shown still a further embodiment of a control system of the invention wherein reference numbers which are the same as those of FIGURES l and 2 denote like parts.
  • the fuel flow in the fuel supply pipe 4 is controlled not only by the variation of the temperature of the liquid in the pipe system 2 but is also responsive to a signal proportional to the fuel flow.
  • the signal from the fuel flow meter 14 is supplied to one input of a conventional controller 25 which compares the signal from the fuel flow meter 14 with a signal related to the temperature of the liquid in the pipe system 2.
  • the signal related to the tempera ture of the heated liquid in pipe system 2 is supplied via transducer 9 and controller 10.
  • the controller 25 will immediately produce an output signal which causes the control valve operator 8 to either further close or further open the control valve 7 an amount proportional to the output signal.
  • the fuel flow is instantly corrected for pressure variations in the fuel supply pipe 4 and thus eliminates any time lag in the re sponse of the system due to the time it takes for changes in the fuel flow rate to show up as temperature variations of the heated liquid. In this Way it is possible to maintain the value of the fuel flow at the desired value with respect to the temperature of the heated liquid, regardless of any pressure variations in the fuel supply pipe 4.
  • the output signal from the air flow meter 21 is supplied to one input of a conventional controller 26, the output of whch controls the air flow in the air supply pipe 5 via control valve operator 13 and control valve 12.
  • the second input signal to the controller 26 is supplied from the multiplier 27 wherein the signal related to the temperature of the heated liquid, which is supplied via the transducer 9 and controller 10, and the signal related to the smoke in the combustion gases, which is supplied via smoke density meter 16 and controller 17 as previously explained, are multiplied together.
  • Apparatus for controlling the combustion process in a heating system comprising: a burner; a fuel supply line and an air supply line connected to said burner; means connected in said fuel supply line for producing a signal proportional to the flow of said fuel; means for measuring the smoke in the combustion gases from said burner and producing a signal related thereto; first controller means for comparing said smoke signal with a first external signal having a preset value and producing an error signal proportional to the diiference; means for combining said signal proportional to the fuel flow and the error signal from said first controller means; means responsive to the output signal from said combining means for varying the flow in said air supply line; means for measuring a variable of the medium heated in the system and producing an output signal proportional thereto; second controller means for comparing the signal proportional to a variable of the medium heated in the system to a second external signal having a preset value and producing an error signal proportional to the difference; and, means responsive to the output signal from said second controller means for varying the flow in said fuel supply line.
  • the method of optimizing the fuel-air ratio in a heating system wherein the fuel flow rate and the air flow rate may be varied consisting of: measuring a variable of the medium heated in the system; comparing said measured value of the variable with a first preset external signal to produce a first difference signal; utilizing said first difference signal to control the fuel flow rate; measuring the density of the smoke in the combustion gases; comparing the measured value of the smoke density to a second preset external signal to produce a second difference signal; measuring the fuel flow rate and producing an output signal proportional thereto; combining said second difference signal and said signal proportional to the fuel flow rate to produce a combined output signal; and controlling the air flow rate in accordance with said combined output signal.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Regulation And Control Of Combustion (AREA)
US288001A 1962-06-21 1963-06-14 Combustion control by means of smoke density Expired - Lifetime US3243116A (en)

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3503553A (en) * 1967-11-13 1970-03-31 Hays Corp Fuel metering combustion control system with automatic oxygen compensation
US3592574A (en) * 1967-11-06 1971-07-13 Kurt Zenkner Fuel burner with fuel feed control means responsive to air and fuel flow
DE1751299B1 (de) * 1968-05-06 1971-10-07 Askania Gmbh Einrichtung zur verbrennungsregelung an dampfkesseln
US3796550A (en) * 1972-04-20 1974-03-12 T Hall Air scrubber apparatus with incinerator
JPS5284858A (en) * 1975-12-15 1977-07-14 Uop Inc Method of and apparatus for controlling burninggup of waste gas
US4235171A (en) * 1978-12-21 1980-11-25 Chevron Research Company Natural draft combustion zone optimizing method and apparatus
US4253404A (en) * 1980-03-03 1981-03-03 Chevron Research Company Natural draft combustion zone optimizing method and apparatus
US4270470A (en) * 1979-04-27 1981-06-02 Barnett William O Combustion system and method for burning fuel with a variable heating value
US4332206A (en) * 1980-05-09 1982-06-01 The Boeing Company Afterburner for combustion of starved-air combustor fuel gas containing suspended solid fuel and fly ash
EP0168700A1 (de) * 1984-07-02 1986-01-22 Deutsches Zentrum für Luft- und Raumfahrt e.V. Regelungsverfahren für Dampferzeuger
EP0181783A1 (en) * 1984-11-14 1986-05-21 The Babcock & Wilcox Company Methods of controlling combustion in process heaters
US9217654B2 (en) * 2010-09-15 2015-12-22 General Electric Company Submetering hydrocarbon fueled water heaters with energy manager systems
US11428407B2 (en) * 2018-09-26 2022-08-30 Cowles Operating Company Combustion air proving apparatus with burner cut-off capability and method of performing the same

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB307536A (enrdf_load_stackoverflow) *
DE627448C (de) * 1933-12-28 1936-03-16 Askania Werke A G Vormals Cent Einrichtung zur selbsttaetigen Regelung der Verbrennungsluftzufuhr zu Rostfeuerungsanlagen mit mechanischer Brennstoffzufuhr
US2196700A (en) * 1940-04-09 Fire control for steam plant
US2412739A (en) * 1943-05-07 1946-12-17 Askania Regulator Co Apparatus for steam generator control
US3049300A (en) * 1960-04-07 1962-08-14 Bailey Meter Co Combustion control for a furnace fired with fuels having different oxygenexcess air characteristics

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB307536A (enrdf_load_stackoverflow) *
US2196700A (en) * 1940-04-09 Fire control for steam plant
DE627448C (de) * 1933-12-28 1936-03-16 Askania Werke A G Vormals Cent Einrichtung zur selbsttaetigen Regelung der Verbrennungsluftzufuhr zu Rostfeuerungsanlagen mit mechanischer Brennstoffzufuhr
US2412739A (en) * 1943-05-07 1946-12-17 Askania Regulator Co Apparatus for steam generator control
US3049300A (en) * 1960-04-07 1962-08-14 Bailey Meter Co Combustion control for a furnace fired with fuels having different oxygenexcess air characteristics

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3592574A (en) * 1967-11-06 1971-07-13 Kurt Zenkner Fuel burner with fuel feed control means responsive to air and fuel flow
US3503553A (en) * 1967-11-13 1970-03-31 Hays Corp Fuel metering combustion control system with automatic oxygen compensation
DE1751299B1 (de) * 1968-05-06 1971-10-07 Askania Gmbh Einrichtung zur verbrennungsregelung an dampfkesseln
US3796550A (en) * 1972-04-20 1974-03-12 T Hall Air scrubber apparatus with incinerator
JPS5284858A (en) * 1975-12-15 1977-07-14 Uop Inc Method of and apparatus for controlling burninggup of waste gas
US4038032A (en) * 1975-12-15 1977-07-26 Uop Inc. Method and means for controlling the incineration of waste
US4235171A (en) * 1978-12-21 1980-11-25 Chevron Research Company Natural draft combustion zone optimizing method and apparatus
US4270470A (en) * 1979-04-27 1981-06-02 Barnett William O Combustion system and method for burning fuel with a variable heating value
US4253404A (en) * 1980-03-03 1981-03-03 Chevron Research Company Natural draft combustion zone optimizing method and apparatus
US4332206A (en) * 1980-05-09 1982-06-01 The Boeing Company Afterburner for combustion of starved-air combustor fuel gas containing suspended solid fuel and fly ash
EP0168700A1 (de) * 1984-07-02 1986-01-22 Deutsches Zentrum für Luft- und Raumfahrt e.V. Regelungsverfahren für Dampferzeuger
US4655392A (en) * 1984-07-02 1987-04-07 Deutsche Forschungs- Und Versuchsanstalt Fur Luft- Und Raumfahrt E.V. Steam-generator control method
EP0181783A1 (en) * 1984-11-14 1986-05-21 The Babcock & Wilcox Company Methods of controlling combustion in process heaters
US9217654B2 (en) * 2010-09-15 2015-12-22 General Electric Company Submetering hydrocarbon fueled water heaters with energy manager systems
US11428407B2 (en) * 2018-09-26 2022-08-30 Cowles Operating Company Combustion air proving apparatus with burner cut-off capability and method of performing the same
US11879640B2 (en) 2018-09-26 2024-01-23 Cowles Operating Company Combustion air proving apparatus with burner cut-off capability and method of performing the same

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