EP0083479A1 - Klappensteuereinrichtung für eine Heizeinrichtung mit natürlichem Zug - Google Patents

Klappensteuereinrichtung für eine Heizeinrichtung mit natürlichem Zug Download PDF

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Publication number
EP0083479A1
EP0083479A1 EP82306586A EP82306586A EP0083479A1 EP 0083479 A1 EP0083479 A1 EP 0083479A1 EP 82306586 A EP82306586 A EP 82306586A EP 82306586 A EP82306586 A EP 82306586A EP 0083479 A1 EP0083479 A1 EP 0083479A1
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EP
European Patent Office
Prior art keywords
damper
signal
heater
stack
oxygen
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP82306586A
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English (en)
French (fr)
Inventor
James H. Sun
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Atlantic Richfield Co
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Atlantic Richfield Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Atlantic Richfield Co filed Critical Atlantic Richfield Co
Publication of EP0083479A1 publication Critical patent/EP0083479A1/de
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • F23N5/006—Systems for controlling combustion using detectors sensitive to combustion gas properties the detector being sensitive to oxygen
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2223/00—Signal processing; Details thereof
    • F23N2223/08—Microprocessor; Microcomputer
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2225/00—Measuring
    • F23N2225/02—Measuring filling height in burners
    • 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
    • F23N2235/04—Air or combustion gas valves or dampers in stacks
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N2237/00—Controlling
    • F23N2237/08—Controlling two or more different types of fuel simultaneously

Definitions

  • the invention relates to apparatus for minimising fuel consumption in a refinery furnace by maintaining the oxygen content at a low level under operating constraints, and more particularly relates to apparatus for controlling stack oxygen content and heater draft in relation to operator input of targetted excess stack oxygen and targetted heater draft. More, particularly, the present invention relates to a controller having standardised elements and to a controller which is easy to implement, operate and maintain for natural draft heaters having complicated arrangements of heater barrels and dampers.
  • the air supply rate within a natural draft process heater is controlled by adjusting the position of a stack damper.
  • dampers were set by hand.
  • automatic controls for dampers have been suggested and applied.
  • apparatus for controlling the air supplied to the furnace, close to the requirement for combustion in order to minimise heat loss to flue gas.
  • Such apparatus have included large scale analog or digital calculating machines which utilise values of measured variables for automatically adjusting the air supplied to the furnace.
  • the automatic control of the damper was based on flue gas oxygen content or was based on heater draft measurement, but not on both.
  • the related application provides a highly welcomed simplified system.
  • This system adds a feedforward feature to the control to respond to fuel changes.
  • the simplified system utilises a single heater barrel having a single damper.
  • the system herein described improves upon the system of the related application by providing a simplified system for a process heater having complicated arrangements of plural heater barrels.
  • the improved system is constructed to permit the heater to remain in operation even when one or more of the critical instruments measuring a combustion variable is out of service. Further, the system makes use of control by both excess oxygen and heater draft measurement.
  • An object of the invention is to provide a simplified controller for controlling the oxygen level in a combustion furnace in order to improve combustion efficiency.
  • a further object of this invention is to provide a controller which satisfies draft requirements and responds to fuel changes promptly to avoid fuel rich conditions.
  • a further object of the invention is to provide a controller which is applicable to a multi-barrel heater as well as a single barrel heater.
  • a further object of the invention is to provide a controller that can stay on control even if one of its critical input measurement instruments is out of service.
  • a stack damper controller for receiving operator input of a targetted combustion variable and for adjusting the position of the stack damper according to the target value.
  • the controller includes a control logic module for each barrel of the heater. Each module includes several control loops.
  • a refinery furnace or heater 11 receive. fuel and control signals for performing a refinery heating process in which combustion is performed in the heater.
  • the oxygen level necessary to perform the combustion is controlled according to the position of a stack damper 15 which is arranged in the top of the stack of the heater and is rotatable for changing air passage through the stack. Damper 15 is rotated under control of a damper positioner or actuator 17 which mechanically controls the position of damper 15.
  • a controller 21 is responsive to the operating conditions of heater 11 and to manual instructions of the operator, for controlling actuator 17 to change the position of damper 15.
  • the position of damper 15 is automatically regulated by controller 21 for (1) controlling the oxygen supply in the stack close to the oxygen requirement for combustion, in order to achieve a minimum fuel consumption level in the heater and (2) controlling the heater draft at a level required by heater operation.
  • Controller 21 generates a control output signal to actuator 17 to control the damper position.
  • An operator input device 27 permits the operator to transmit to controller 21 an oxygen target level indicative of a desired excess oxygen level above the oxygen combustion requirement, to be maintained in the stack.
  • Device 27 also permits the operator to provide a draft target level to controller 21.
  • the draft target level is of a desired draft through the heater combustion chamber.
  • Controller 21 receives the target data and responsively controls the damper in order to establish the stack oxygen content and draft in conformance with the target values.
  • Monitoring transducers are located within the heater and associated fuel and combustion control apparatus, for generating electrical analog signals indicative of the value of individual condition variables.
  • the analog signals are transmitted to controller 21 along a plurality of leads 30.
  • Controller 21 responds to signals developed along leads 30 and responsively controls the damper position.
  • controller 21 is constructed from a micro-computer which controls the overall system processing and management of controller 21.
  • the microcomputer based controller performs a number of tasks which may be summarised as follows:
  • controller 21 controls the position of damper 15 by two sources of control: (1) a feedback control, represented by a control block 37, and (2) a feedforward control, represented by a control block 39.
  • the controller utilises feedback control 37 when positioning the damper responsive to the target data at 33.
  • a conventional oxygen analyser (not shown) is located in the stack and monitors the excess oxygen level in the flue gas resulting from the combustion. When the measured excess oxygen level deviates from the target data, a damper position value at 35 may be generated by the controller and an output signal is responsively transmitted to actuator 17 to compensate for the deviation.
  • a conventional draft monitoring device is located in the combustion chamber and monitors the draft in the heater.
  • the heater draft is a negative pressure.
  • a damper position value at 35 may be generated by the controller.
  • a consolidated damper position is determined from the values generated from the draft control and oxygen control. The value representing the more open position of the damper is chosen. The output processing block 36 then generates the output signal representing the chosen damper position.
  • the controller utilises feedforward control 39 when positioning the damper in anticipation of an increased need for combustion air, responsive to detecting a demand for increased combustion.
  • the analog signals on leads 30 will carry information of an increased demand in combustion, and controller 21 will respond accordingly, generating an anticipated damper position at 35, for appropriately adjusting the damper.
  • transducers 29 which monitor the system variables may include conventional flow transmitters which monitor flow rate and generate signals related thereto, conventional position sensors for monitoring the positions of damper 15, a conventional excess oxygen analyser for monitoring excess oxygen level, a conventional draft sensor for monitoring heater draft.
  • Signal processing control 31 processes the signals developed along leads 30 for generating signal data in a form usable by controller 21. Initially the analog signals developed along leads 30 are converted to a digital signal by an analog-to-digital converter (not shown). After the analog signals are converted to digital signals, the digital signals are stored in memory in the form of digital data.
  • Operator input device 27 effectively inputs target values to the controller via manually operable switches 43, 45. Operation of switches 43, 45 respectively increment or decrement a number visually displayed on visual displays 47, 49 of the input device. As the operator moves either of switches 43, 45 to an upward mode or to a downward mode, the displayed value in respective displays 47, 49 increments or decrements according to the mode to which the switch is moved. When a display reaches a number desired by the operator, the operator discontinues actuation of the switch. Input device 27 then develops binary data signals representative of the values displayed on displays 47, 49 for transmission to controller 21.
  • an Enter Target button 51 located on input device 27 is manually actuable by the operator for effectively entering the values displayed on displays 47, 49 into controller 21.
  • the Enter Target button generates an interrupt signal to controller 21 for signalling the controller that the binary data signals representative of the values displayed in displays 47, 49 should be read from input device 27 and stored in memory at 33 as new target values.
  • Input device 27 includes an AUTOMATIC pushbutton switch 55 and a MANUAL pushbutton switch 57 for placing the system in an automatic or a manual mode.
  • Controller 21 monitors the status of switches 55, 57. With switch 55 actuated, the controller performs its automatic function of controlling the damper position using feedforward control 39 and feedback control 37; with switch 57 actuated, the controller discontinues controlling the damper by the feedforward and feedback controls and instead controls the damper by manual data at 34 entered by the operator via input device 27.
  • Switches 55, 57 may be lighted when pressed, for displaying whether the controller is in its manual or automatic mode.
  • Input device 27 includes a pair of manually operable pushbuttons 56,58. When actuated, pushbuttons 56,58 change the manual data at 34 in order to open or close the damper.
  • the operator views visual display devices 60,62 during operation of pushbuttons 56,58.
  • Display device 60 is controlled by controller 21 in order to display to the operator a visual indication of the monitored position of damper 15.
  • Display device 62 displays the target damper position as input by the pushbuttons 56,58.
  • Figure 2A illustrates a single barrel, single stack damper heater 63. As shown, fuel oil and fuel gas feed the single barrel and the combustion chamber draft and oxygen content of the stack are monitored.
  • Figure 2B illustrates a dual barrel, single stack damper heater 65. As shown, the same fuel oil line 67 and fuel gas line 68 feed both barrels 69,71 of the heater. Draft for each barrel is monitored at 73,'/5, as well as oxygen content for each barrel at 77,79. A single stack damper 81 is positioned for controlling combustion efficiency.
  • FIG. 2C illustrates a triple barrel, triple stack damper heater 83 having three barrels 85,87,89.
  • the same fuel oil line 91 feeds two of the three barrels, 85,89.
  • Fuel oil line 93 feeds barrel 87.
  • the same fuel gas line 95 feeds barrels 85,89, a fuel gas line 97 feeds barrel 87. Draft for each barrel is monitored at 99,101,103, as well as oxygen for each barrel at 105,107,109.
  • Three dampers 111,113,115 are positioned for controlling combustion efficiency.
  • the single barrel, single damper heater of Figure 2A is the same as that of Figure 1 and is controlled by a single controller as shown in Figure 1.
  • the dual barrel, single stack damper heater of Figure 2B may be controlled by two controllers; however, the control output signals from the two controllers are consolidated into a single output signal to control the common damper.
  • the number of separate microprocessors used may be one or two.
  • the triple barrel, triple damper heater 83 of Figure 2C utilises three (3) controllers as shown in Figure 3. Controllers 117,118 and 119 are utilised instead of a single controller. Controllers 118,119 monitor the combustion conditions associated with barrels 85, 89 and responsively position dampers 111,115. Controller 117 monitors the combustion conditions associated with barrel 87 and responsively controls damper 113. As illustrated, three damper actuators S are utilised for the three dampers.
  • controller 21 includes a feedforward control and a feedback control. Also, a damper position control responds to the feedforward and feedback control for positioning the damper. These controlling functions are developed by a set of control logic utilised to do the following:
  • a logic module is utilised for each barrel within the heater arrangement and an adapter logic block is utilised to handle the interaction between barrels.
  • a logic module is shown as having four (4) control loops: a fuel loop 121, an oxygen loop 123, a draft loop 125 and a damper loop 127.
  • Fuel loop 121 forms the feedforward control 39 ( Figure 1); whereas oxygen loop 123 and draft loop 125 form the feedback control 37.
  • Damper loop 127 forms the damper position control 35.
  • Fuel loop 121 receives the monitored fuel oil rate at 129 and the monitored fuel gas rate at 131, which have been retrieved by the signal data processing section 31 ( Figure 1) as previously described.
  • a pair of multiplication logic blocks 133, 135 multiply the rate inputs by a fuel oil heating value and a fuel gas heating value.
  • the oil heating value is received at input 137 of multiplier 133 and the gas heating value is received at input 139 of multiplier 135.
  • Instruments are available which will monitor such heating values with time. Such monitoring devices transmit condition signals to signal data processing block 31 ( Figure 1).
  • fixed constants could be used where the fuel oil heating value and fuel gas heating value do not vary with time.
  • the heating values are in terms of BTU content per unit volume of fuel.
  • the output data at nodes 141,143 of multipliers 133,135 is BTU.
  • An adder block 145 receives the respective outputs from multipliers 133,135 in order to generate a total BTU value along output 147.
  • a logic block 149 monitors the total BTU output to determine whether an increase in BTU is occurring. Block 149 compares the present BTU value with a previously monitored BTU.
  • block 149 determines that there is not an increase in BTU, no change in damper position is requested from the fuel loop. Exit is made at 151 for repeating the fuel loop to monitor when an increase in BTU occurs.
  • a ratio block 152 determines the amount of change to be made to the damper.
  • Ratio block 152 uses a ratio factor of the change of damper required for each unit of change of BTU.
  • the amount of change in BTU (which is calculated at logic block 149) is multiplied by the ratio factor at ratio block 152.
  • the resultant calculated change in damper position is sent to the damper loop at 153. This value is the feedforward request which asks the damper for more oxygen based on anticipated need due to increase in fuel.
  • Oxygen loop 123 includes an arithmetic logic block 154 which receives an input at 155 of the oxygen set point.
  • the oxygen set point is entered by the operator from device 27 ( Figure 1) and then is stored in target data block 33, as previously described.
  • Stack oxygen is received at input 157 of logic block 154.
  • Logic block 154 performs an algorithm using the oxygen set point and stack oxygen data in order to generate an output at 159 of a change in damper position. The algorithm determines how much of a change in the damper position is necessary in order to bring the stack oxygen equal to the oxygen set point.
  • the algorithm is a conventional proportional-integral 2-mode formula.
  • Draft loop 125 includes an arithmetic block 161 which receives an input at 162 of the draft set point.
  • the draft set point is entered by the operator from device 27 ( Figure 1) and then is stored in target data block 33, as previously described. Draft is received at input 163 of logic block 161.
  • Logic block 161 performs an algorithm using the draft set point and stack draft data in order to generate an output at 164 of a change in damper position. The algorithm determines how much of a change in the damper position is necessary in order to bring the draft equal to the draft set point.
  • the algorithm is a conventional, 2-mode (proportional-integral) formula.
  • Block 165 selects the one of the two outputs 159,164 which requires a more open position of the damper.
  • the passage of the more open damper position is sent to the damper loop at 167. This value is the feedback request which asks the damper for more or less damper opening in order to meet the draft or oxygen set point requested by the operator.
  • Damper loop 127 receives the feedforward input of damper position from fuel loop 121 and the feedback input of damper position from oxygen loop 123. The two inputs are summed at logic block 169, generating a change in damper position which is utilised to generate a control output signal to actuator 17, as described above. Any one of or combination of the three loops (fuel, draft and oxygen) can be withdrawn from control by putting it on manual mode. This capability of graceful degrading provides maximum service under instrument failure condition, and is useful in isolating problem areas.
  • input device 27 includes a manual mode selector having three pushbutton switches 172,174 and 176 associated with oxygen loop 123, draft loop 125 and fuel loop 121, respectively.
  • the switches 172,174 and 176 are represented in Figure 4.
  • a switch 172-176 When a switch 172-176 is open (pushbutton depressed), the associated control loop drops out.
  • selector 165 passes the draft request to the damper loop.
  • the logic module of Figure 4 is utilised for each heater barrel of various heater arrangements.
  • the dual barrel heater of Figure 2B requires two logic modules and therefore, two controllers.
  • a pair of logic modules 171,173 are utilised for the dual barrel heater.
  • Module 171 includes a fuel loop 175, an oxygen loop 177, a draft loop 179 and a damper loop 181.
  • Module 173 also includes a fuel loop 189, an oxygen loop 183, a draft loop 185 and a damper loop 187.
  • Each module responds to each barrel as if they have separate identities.
  • This modular concept allows a standardised logic to be used repeatedly for various heater arrangements. Since there is only one damper in the dual barrel heater of Figure 2B, an adapter loop 191 receives the two damper position signals from the two modules and forms a single damper position signal.
  • Adapter 191 is shown in more detail in Figure 6 as including a select logic 193.
  • Logic 193 receives the two damper position signals from the damper loops 181, 187, and outputs the one damper position signal which requests the more open damper position.
  • the triple barrel heater of Figure 2C requires three logic modules. As shown in Figure 7, three modules 195,197,199 are utilised. As shown, each module includes the four different loops: fuel, oxygen, draft and damper. In the triple barrel heater, the movement of central damper 113 affects the oxygen level at the other two dampers 111,115. In order to supervise this effect, an adapter loop 201 is utilised. The adapter loop compensates for the influence of damper 113 onto barrels 85,89 by moving dampers 111,115 in an opposite direction of the movement of damper 113.
  • adapter loop 201 generates a compensation signal at 211 to the damper loops of barrels 85,89.
  • the compensation signal is generated in accordance with the changing position of the central damper of barrel 113.
  • the changing position of the central damper 113 is inverted by an inverter 203.
  • the damper position of the central barrel is then multiplied by a ratio K at multiplier 205.
  • Ratio K is the degree of change on damper 113 affecting dampers 111,115.
  • the output at 207 then is the change in dampers 111,115 which is required due to the change made in the position of damper 113.
  • This compensating change signal at 207 is sent to the damper loops of barrels 85,89 and is received by logic block 169 ( Figure 4).
  • the compensating change signal is added to the change in the dampers 111,115 required by the draft, oxygen and fuel loop of its respective module.
  • the resultant outputs control the two dampers 111,115.

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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)
  • Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
EP82306586A 1981-12-31 1982-12-09 Klappensteuereinrichtung für eine Heizeinrichtung mit natürlichem Zug Withdrawn EP0083479A1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US33616081A 1981-12-31 1981-12-31
US336160 1994-12-29

Publications (1)

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EP0083479A1 true EP0083479A1 (de) 1983-07-13

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EP82306586A Withdrawn EP0083479A1 (de) 1981-12-31 1982-12-09 Klappensteuereinrichtung für eine Heizeinrichtung mit natürlichem Zug

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EP (1) EP0083479A1 (de)
JP (1) JPS58120023A (de)
CA (1) CA1192793A (de)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0156958A1 (de) * 1984-03-21 1985-10-09 Hartmann & Braun Aktiengesellschaft Regelverfahren für die Verbrennungsluftmenge einer Feuerungseinrichtung
US5190454A (en) * 1991-07-15 1993-03-02 Cmi Corporation Electronic combustion control system
DE10007418A1 (de) * 2000-02-18 2001-09-06 Fujitsu Siemens Computers Gmbh Einschubrahmen für ein Festplattenspeicherlaufwerk
CN114459033A (zh) * 2022-01-28 2022-05-10 佛山仙湖实验室 基于富氧及氢气助燃的氨燃烧控制系统

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3369749A (en) * 1967-02-17 1968-02-20 Exxon Research Engineering Co Low excess air operation of multipleburner residual-fuel-fired furnaces
DE2745459A1 (de) * 1976-12-14 1978-06-15 Measurex Corp Einrichtung zur steuerung des verbrennungswirkungsgrades
US4097218A (en) * 1976-11-09 1978-06-27 Mobil Oil Corporation Means and method for controlling excess air inflow
EP0030736A2 (de) * 1979-12-17 1981-06-24 SERVO-Instrument in Deutschland Alleinvertrieb der BEAB-Regulatoren GmbH & Co KG Regelvorrichtung für die Verbrennungsluftmenge einer Feuerstätte
US4330261A (en) * 1979-09-17 1982-05-18 Atlantic Richfield Company Heater damper controller

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3369749A (en) * 1967-02-17 1968-02-20 Exxon Research Engineering Co Low excess air operation of multipleburner residual-fuel-fired furnaces
US4097218A (en) * 1976-11-09 1978-06-27 Mobil Oil Corporation Means and method for controlling excess air inflow
DE2745459A1 (de) * 1976-12-14 1978-06-15 Measurex Corp Einrichtung zur steuerung des verbrennungswirkungsgrades
US4330261A (en) * 1979-09-17 1982-05-18 Atlantic Richfield Company Heater damper controller
EP0030736A2 (de) * 1979-12-17 1981-06-24 SERVO-Instrument in Deutschland Alleinvertrieb der BEAB-Regulatoren GmbH & Co KG Regelvorrichtung für die Verbrennungsluftmenge einer Feuerstätte

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
ADVANCES IN INSTRUMENTATION, vol. 35, part 2, 1980, pages 63-73, Research Triangle Park, North Carolina (USA); *
CONTROL AND INSTRUMENTATION, vol. 10, no. 9, October 1978, pages 71-72, London (GB); *
OIL & GAS JOURNAL, vol. 79, no. 38, September 1981, pages 134-138, Tulsa, Oklahoma (USA); *

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0156958A1 (de) * 1984-03-21 1985-10-09 Hartmann & Braun Aktiengesellschaft Regelverfahren für die Verbrennungsluftmenge einer Feuerungseinrichtung
US5190454A (en) * 1991-07-15 1993-03-02 Cmi Corporation Electronic combustion control system
DE10007418A1 (de) * 2000-02-18 2001-09-06 Fujitsu Siemens Computers Gmbh Einschubrahmen für ein Festplattenspeicherlaufwerk
DE10007418B4 (de) * 2000-02-18 2005-12-15 Fujitsu Siemens Computers Gmbh Einschubrahmen für ein Festplattenspeicherlaufwerk
CN114459033A (zh) * 2022-01-28 2022-05-10 佛山仙湖实验室 基于富氧及氢气助燃的氨燃烧控制系统

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Publication number Publication date
CA1192793A (en) 1985-09-03
JPS58120023A (ja) 1983-07-16

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