Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N1/00—Regulating fuel supply
  • F23N1/02—Regulating fuel supply conjointly with air supply
  • F23N1/022—Regulating fuel supply conjointly with air supply using electronic means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N1/00—Regulating fuel supply
  • F23N1/08—Regulating fuel supply conjointly with another medium, e.g. boiler water
  • F23N1/10—Regulating fuel supply conjointly with another medium, e.g. boiler water and with air supply or draught
  • F23N1/102—Regulating fuel supply conjointly with another medium, e.g. boiler water and with air supply or draught using electronic means
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2225/00—Measuring
  • F23N2225/08—Measuring temperature
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2235/00—Valves, nozzles or pumps
  • F23N2235/02—Air or combustion gas valves or dampers
  • F23N2235/06—Air or combustion gas valves or dampers at the air intake
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
  • F23N—REGULATING OR CONTROLLING COMBUSTION
  • F23N2235/00—Valves, nozzles or pumps
  • F23N2235/12—Fuel valves

Definitions

• This invention relates broadly to furnaces, boilers, incinerators, and like equipment wherein fuel is burned.
• this invention relates to combustion equipment which regulates the flow of combustion air and fuel in response to a signal generated from a condition of a process. Still more particularly, this invention relates to combustion equipment which will provide a fuel- lean mixture of combustion components as process con ⁇ ditions modify the demand for process heating.
• the efficient control of combustion relates to the efficient control of the fuel and combustion oxi- dant, usually air. Efficient control of combustion is essential in the power industry, chemical industry, and various other process industries.
• the amount of heat furnished by the combustion process depends upon the amount of heat needed by the operation requiring the heat, whether for the generation of power, or for the chemical process, or for an oil refinery process. In addition, the amount of heat needed will continually vary, thus requiring continual control of the combustion.
• the relative ef ⁇ ficiency of the combustion process may be accomplished by the use of elaborate control systems, such as computers, various kinds of automatic valves, and electronic controls.
• the primary object of this invention is to provide a method and apparatus for controlling combustion in a process which is efficient, easy to operate, and economical. Another object of this invention is to provide a method and apparatus for controlling combustion in a process which will require only a minimum number of control components in order to regulate the combustion effectively. Still another object of this invention is to provide a method and apparatus for controlling com ⁇ bustion in a process in which fuel and combustion air are easily regulated for more efficient energy consumption. Still another object of this invention is to provide a method and apparatus for maintaining close control of the combustion in a process.
• Another object of this invention is to provide a method and apparatus which can be easily adjusted to regulate a combustion temperature.
• Still another object of this invention is to provide a method and apparatus to modify quickly and efficiently the ratio of air to fuel of a combustion system.
• This invention describes a greatly simplified and efficient method and apparatus for combustion control by eliminating many sophisticated and high ⁇ ly technical controlling devices commonly shown in other combustion control systems.
• this invention reduces the number of control devices which the operator must understand and closely ob ⁇ serve. Consequently, the risk of accident caused by inattention of the operator is greatly reduced. Further, this invention provides for a more efficient combustion control system by assuring a fuel-lean combustion during a change in combustion requirements.
• the method and apparatus of this invention in ⁇ clude generating a signal from a condition of a process stream and adapting that signal to acuate various fuel and combustion oxidant control com ⁇ ponents.
• the type of signal generated includes an electrical, or electronic, signal.
• the condition of the process stream from which the signal is gen ⁇ erated is preferably a temperature of the process, or the pressure of a boiler.
• a temperature-re ⁇ sponsive device measures a temperature of the process and emits an electrical signal which may be either an increasing voltage signal or a decreasing voltage signal.
• the signal is communicated in parallel to a signal restrictive member, such as a resistance, or, more particularly, such as a variable resistance or potentiometer; to a first electro-responsive device, such as a first electronic relay; and to a second electro-responsive device, such as a second elec- tronic relay.
• a signal restrictive member such as a resistance, or, more particularly, such as a variable resistance or potentiometer
• a first electro-responsive device such as a first electronic relay
• a second electro-responsive device such as a second elec- tronic relay.
• the first electro-responsive device is adapted to respond to a signal of a first characterization
• the second electro-responsive device is adapted to respond to a signal of a second characterization.
• the signal restrictive member is further adapt ⁇ able to communicate a signal to a signal collecting device, such as a capacitance
• the signal col ⁇ lecting device is adaptable to provide a signal of a first characterization and a signal of a second characterization.
• the signal collecting device is adaptable to communicate in parallel with the first electro-re ⁇ sponsive device and with the second electro-respon ⁇ sive device.
• the first signal electro-responsive device is further adaptable to communicate with an air control device which is adaptable to control a flow of combustion air in response to a signal from the first electro-responsive device.
• the second electro-responsive device is further adaptable to communicate with a fuel control device which is adaptable to control a flow of fuel in response to a signal from the second electro-respon ⁇ sive device.
• the invention teaches a method and apparatus for controlling combustion in which fuel-lean com ⁇ bustion is provided during an interval in which the firing rate is changing. For example, when the process system demands more heat, the flow of com ⁇ bustion air is increased prior to an increase in . the flow of fuel, thereby maintaining a fuel-lean mixture during the interval of change. Or, when the process system requires the heat to be reduced, the flow of fuel is decreased prior to a decrease in the flow of combustion air, thereby maintaining a fuel-lean mixture during this interval of change.
• the signal is communicated to a series resistor and a variable R-C ramping network. Voltage com ⁇ parators are utilized to compare the instantaneous input signal to the output of the ramp network.
• These voltage comparators control solid state switches which connect two (2) signals to the ap ⁇ intestinalte output amplifier.
• the output amplifiers control the signals to the final AIR/FUEL control devices so that during a signal change there will always be a fuel-lean mixture.
• the fuel control signal amplifier receives the instant signal direct with the combustion air control amplifier receiving the ramping signal.
• the fuel control signal am ⁇ plifier receives the ramping signal and the com ⁇ bustion air control amplifier receives the instan ⁇ taneous signal.
• a fuel flow control valve and an air flow control valve, or damper react in parallel, in proportion to the signal generated by the temperature controller.
• a fuel flow control valve and an air flow control valve maintain a given ratio of fuel to oxidant as they move in response to the signal generated by the temperature controller.
• O PI s. w ⁇ p ° signal is within the range of four (4) to twenty (20) milliamperes.
• a potentiometer used in this manner which I also refer to as a ratio controller can serve to: compensate for changes in the heating value of the fuel being utilized;
• FIGURE 1 is a schematic drawing of a typical process heating system.
• FIGURE 2 is a diagrammatic drawing of a com ⁇ bustion control system according to this invention.
• FIGURE 3 is a schematic drawing of a combustion control system according to this invention.
• FIGURE 4 is a diagrammatic drawing of an alternate embodiment of a combustion control system according to this invention.
• FIGURE 5 is a schematic drawing of an alter ⁇ nate embodiment of a combustion control system ac ⁇ cording to this invention.
• FIGURE 6 is a schematic drawing of a combus ⁇ tion control system according to this invention including a ratio control device.
• FIGURE 1 describes a typical combustion and heating system for a conventional process industry, which, in its basic arrangement, comprises a fur- nace or heater 10, generally, having a process in ⁇ let stream 12 entering therein, a typical heating coil 14, a process outlet stream 16, and a burner 18 fired by a fuel line 20 and air supplied as through opening 22.
• line 24 provides communication between process outlet stream 16 and a temperature controller 26.
• Temperature controller 26 may be one of any conventional devices for measuring temperature and providing a signal to other equipment in response to that temperature.
• temperature controller 26 measures a temperature of the process stream and provides a signal through lines 28, 30, 32, and 34, in parallel to a first relay 36, a potentiometer 38, and a second relay 40.
• First relay 36 is adapted to respond to an in ⁇ creasing voltage signal in lines 28 and 30.
• Relay 36 then transmits a signal through line 42 to an air flow control device 44, which, in this e bodi- ment of my invention, further communicates a signal through line 45 to an air control device 46, generally, which operates, through connection 48, louvers 50, positioned in air duct 52, to regulate the amount of combustion air.
• Second relay 40 is adapted to respond to a decreasing voltage signal in lines 28 and 34. Relay 40 then transmits a signal through line 54 to a fuel control device 56, generally, which further transmits a signal through line 57 to fuel control valve 58, which operates to control the amount of fuel trans- mitted to burner 18.
• Potentiometer 38 is, of course, an adjustable resistance, and, as such, may be adjusted to provide a selected potential through line 60 to condenser 62 which is adapted to transmit a delayed signal through lines 64, 66, and 68, to first relay 36 and second relay 40.
• an increasing potential signal from temp ⁇ erature controller 26 through lines 28 and 32 will cause a delayed potential to develop on condenser 62 and result in a delayed potential drop between relay 36 and condenser 62 and between relay 40 and conden ⁇ ser 62.
• relay 36 The reaction of relay 36 to an increasing po ⁇ tential signal from temperature controller 26 will cause relay 36 to actuate air flow control device 44 and air control device 46 as explained above, assuring a flow of air to burner 18 before a flow of fuel begins.
• Relay 40 will not react to the increasing po- tential through line 34 but will react to the de ⁇ layed increasing potential through line 68.
• relay 40 will actuate fuel control de ⁇ vice 56 and fuel control valve 58 to permit a flow of fuel to burner 18 after a flow of air has begun.
• a signal of decreasing potential from temper ⁇ ature controller 26 through line 34 will actuate relay 40 to cause relay 40 to actuate fuel control device 56 in a manner to close fuel control valve 58, shutting off the flow of fuel before the flow of air is shut off.
• Relay 36 will not react to a signal of de ⁇ creasing potential from temperature controller 26 through line 30, but will react to a delayed signal of decreasing potential through condenser 62, line 64, and line 66, to actuate air flow control device 44 to operate air control device 46 to shut off the supply of air to burner 18 after the flow of fuel to burner 18 has stopped.
• FIGURE 2 provides a simple outline of a typical process industry embodiment of my invention.
• temperature controller 26 measures a temperature of the process stream and provides a milliampere' signal through lines 28 and 29 and resistor 31.
• Potentiometer 38 and capacitor 62 form a ramp signal.
• Switches 33 and 35 and voltage comparators 37 and 39 receive an instantaneous signal through line 30 and a ramp sig ⁇ nal through line 32.
• An output amplifier 41 is con ⁇ nected between switch 35 and air flow control device 44, and an output amplifier 43 is connected between switch 33 and fuel control device 56.
• Voltage comparator 39 is set to switch line 30 to amplifier 41 through switch 35 when the signal on line 30 is greater than the signal on line 32.
• Voltage comparator 39 is set to switch line 32 through switch 35 to amplifier 41 when the signal on line 32 is greater than line 30.
• Amplifier 41 transmits a signal through 42 to air flow control device 44 as exemplified by current converter 44 which further communicates a signal through 45 to air control de ⁇ vice 46 which operates, through connection 48, louvers 50, positioned in air duct 52 to regulate the amount of combustion air.
• Voltage comparator 37 is set to switch line 30 to amplifier 43 through switch 33 when the signal on line 30 is less than the signal on line 32.
• Volt- age comparator 37 is set to switch line 32 to ampli ⁇ bomb 43 through switch 35 when the signal on line 32 is less than the signal on line 30.
• Amplifier 43 transmits a signal through 54 to fuel control device 56 as exemplified by current converter 56 which further communicates a signal through 57 to fuel control valve 58.
• Potentiometer 38 in conjunction with capaci ⁇ tor 62 are used to determine the ramp signal.
• a signal increase from the temperature con- troller 26 through line 28 will create an increase in voltage across resistor 31.
• This instantaneous voltage is fed to the ramp control 38 and 62 and through line 30 to comparators 37 and 39.
• the sig ⁇ nal on line 30 is greater than on line 32, therefore line 30 is switched to amplifier 41 by comparator 39 and switch 35, the ramp voltage on line 32 is switched to amplifier 43 by comparator 37 and switch 33.
• an increased signal from the temperature controller will cause the air signal to increase immediately with the fuel signal ramping up to its desired point.
• a decrease in the temperature con ⁇ trol signal will cause the opposite to occur, i.e., the fuel signal will drop immediately and the air signal will ramp down to its desired point.
• a potentiometer 82 connected with amplifier 43 and line 54, as it would be suitably placed for modifying the signal to fuel control device 56.

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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)

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ID=22168454

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• 1982
  • 1982-12-13 WO PCT/US1982/001753 patent/WO1984002403A1/en unknown
  • 1982-12-13 EP EP83900386A patent/EP0128141A1/de not_active Withdrawn

Non-Patent Citations (1)

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