US3556496A - Furnace profile temperature controller with ancillary signal producing means to maintain furnace at optimal temperature control levels and to minimize adverse effect of upsets - Google Patents

Furnace profile temperature controller with ancillary signal producing means to maintain furnace at optimal temperature control levels and to minimize adverse effect of upsets Download PDF

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Publication number
US3556496A
US3556496A US839449A US3556496DA US3556496A US 3556496 A US3556496 A US 3556496A US 839449 A US839449 A US 839449A US 3556496D A US3556496D A US 3556496DA US 3556496 A US3556496 A US 3556496A
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set point
furnace
process variable
transmitter
loops
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US839449A
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Ernest Hucke
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Honeywell Inc
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Honeywell Inc
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27B—FURNACES, KILNS, OVENS OR RETORTS IN GENERAL; OPEN SINTERING OR LIKE APPARATUS
    • F27B7/00—Rotary-drum furnaces, i.e. horizontal or slightly inclined
    • F27B7/20—Details, accessories or equipment specially adapted for rotary-drum furnaces
    • F27B7/42—Arrangement of controlling, monitoring, alarm or like devices

Definitions

  • FURNACE PROFILE TEMPERATURE CONTROLLER ANCILLARY SIGNAL ABSTRACT A temperature-measuring control apparatus PRODUCING MEANS TO MAINTAIN FURNACE AT havmg opposing anc1llary set point ad ustmg loop circuits for OPTIMAL TEMPERATURE CONTROL LEVELS 1 AND To MINIMIZE ADVERSE EFFECT OF UPSETS regulating the heat requ1red to convert a granular material, for 10 Cl 4 D example: a cement mix into quality clinker which control aprawmg paratus is responsive to changes taking place in the overall [52] US. Cl i.
  • the cement mix is then introduced into a preheating zone and a heating zone that is located at the right end of a tilted gravity fed-rotating kiln so that it will be heated to a prescribed temperature by hot gases that are passed through the kiln.
  • the cement mix is then moved by gravity and the rotation of the kiln into a calcining zone where the mix is heated by the hot gases to a temperature which is below the melting temperature of the mix. In this zone, the mix is formed into certain desired chemical compounds.
  • the cement mix is then moved in a similar manner to thatjust described into the burning zone of the kiln, a zone into which the flame of a burner is introduced so that an end product formed of a hard chemical mixture known as clinker is produced.
  • FIG. 1 is a view showing the set point process variable apparatus associated with the respective zones of a kiln being employed to produce an error adjusting ancillary signal whose values are used to algebraically modify a master set point signal that is being transmitted to a master controller and how a calcining zone temperature transmitting circuit shown in dotted line form can be substituted for the master set point transmitter.
  • FIG. 2 shows how the resistant values of each of the potentiometers in the process variable-set point loop circuits can be adjusted by a separate mechanical means in place of the single mechanical means employed to simultaneously adjust the resistance of the process variable and set point loops to the same resistance value.
  • FIG. 3 shows a converter which can be employed in the circuit shown in FIG. 1 to convert a DC input signal into a milliamp DC signal and
  • FIG. 4 shows the values that the potentiometer associated with the process variable and set point loops will be in to obtain a zero ancillary set point signal.
  • FIG. 1 a control apparatus 10 for making optimum use of the heat required to convert a granular cement mix or other similar material 12 into a material such as a clinker 14 having a preselected density and hardness prior to, during and after a furnace upset.
  • This control apparatus 10 employs a master indicating controller 16 that receives a process variable signal by way of a conductive electrical connection 18 from any primary flowsensing element such as from any differential pressure to current transducer 20 having conduits 22, 24 connected to opposite sides of an orifice plate 26 that is located in a conduit 28 that supplies fuel from a source, not shown, to a burner 30.
  • a master indicating controller 16 that receives a process variable signal by way of a conductive electrical connection 18 from any primary flowsensing element such as from any differential pressure to current transducer 20 having conduits 22, 24 connected to opposite sides of an orifice plate 26 that is located in a conduit 28 that supplies fuel from a source, not shown, to a burner 30.
  • the control apparatus 10 also employs a set point indicating transmitter 32.
  • the master set point transmitter 32 is connected to an AC power supply 34 and has two conductors 36, 38 connected across a resistance 40 and an electrical conductive transmission line 42, 44. These lines 42, 44 are in turn connected by way of a voltage to current transducer 46, an electric-transmitting line 48 to transmit the set point signal, the burning zone temperature transmitter 50, the electrical transmission line 52 to the master controller 16.
  • thermocouple to current transducer 64 which in turn has a pair of electrical leads 66, 68 connected to a protecting well enclosed thermocouple 70 that is employed to sense the temperature of the right end or preheating zone 72 of the furnace 74.
  • the electrical circuit for thermocouple to current transducer 64, its thermocouple 70 may be of the type disclosed in detail in the Edward T. E. Hurd lll L'S. Pat. application. Ser. No. 670,822.1iled Sept. 8, l967.
  • the other end of the conductors is connected to a process variable vertical scale indicator 76 for indicating the mag nitude of the temperature of the preheating zone 72.
  • the manually adjusted set point electrical loop circuit 78 having a current flowing in the direction of the arrow 80 is shown with its conductors 82 to 84 connected at one end to a manually adjustable vertical scale set point indicator 86 and at its other ends to the master signal transmission line 44.
  • the indicator 86 in turn receives alternating current power conductors 87, 88 from a suitable AC power supply source 89.
  • the wiper 90 and resistance 92 form the potentiometer 94 in the process variable electrical loop 54 and the wiper 96 and resistance 98 form a potentiometer 100 in the manually adjustable set point electrical loop 78.
  • the wipers 90, 96 can as shown, have a connection 104 for manually moving each of them jointly along their respective resistances 92, 98, to increase or decrease the resistance in the process variable and set point loop circuits 54, 78, by rotation of the knob 106.
  • the switch 108 is initially kept in a closed position during the initial heating up stages of a kiln and until a manual adjustment of the set point adjustment wheel 110 of the master set point transmitter 32 has been established which retains the flame heat being added to the furnace at a value that will produce a good quality clinker 14.
  • This clinker 14 is formed just prior to the time it is passed out the left burning zone end of the rotary furnace or kiln 74, as this kiln is rotatably driven by a conventional electric motor 112 and reduction drive 114.
  • the vertical scale type process variable indicator 76 will indicate the temperature that is present in the preheat zone of the furnace 74.
  • the manually adjustable set point adjusting knob 116 is moved to an ancillary set point control-indicating position that matches the value that is shown on the process variable indicator 76.
  • the switch 108 is then opened and since the instantaneous setting of the process variable and set point indicators 76, 86 at that time are equal the opposing loop circuits 54, 78 will be of the same magnitude so that no change in the set point signal being transmitted by the master set point transmitter through leads 42, 44, will occur due to the electrical output of these loops 54, 78.
  • thermocouple 70 After the switch 108 has been opened the thermocouple 70 then senses a cooling off of the cement mix entering the preheating zone due to, for example, an upset such as an abnormal increase in the cement mix that is fed into the furnace 74 by the conveyor 118.
  • the value of current being sent through the process variable loop 54 will thus be changed from the value of the current passing through the electrically opposing set point loop 78 and an ancillary error signal will be introduced that will change the magnitude of the set point signal being transmitted by the master set point transmitter 32 by way of the conductors 42, 44, 48, transmitter 50 to the master controller 16.
  • This action will thereby cause the set point of the master controller 16 to change the set point 110 and an error signal which is representative of the differences in magnitude of its process variable and set point signals to be sent to the motorized valve 16 to allow, for example, more fuel to be sent to the furnace to heat the increase in cement mix flowing into the right end of the furnace 74.
  • thermocouple leads 132 and the thermocouple to current transducer 134 are similar to the previously described parts 70, 68 and 64.
  • a pair of leads 136, 138, are shown connecting the transducer 134 with associated slip rings 140, 142 that are in turn fixedly mounted by insulating support members, not shown, on the outer surface of the kiln 74.
  • the output signal produced by the transducer 134 in response to the temperature sensed by the thermocouple is taken from the slip rings 140, 142, by means of brushes 144, 146, and electrical leads 148, 150.
  • a voltage to current converter 152 Part way between the opposite ends of the leads 148, 150, there is shown a voltage to current converter 152 whose circuit is shown in HO. 3 as comprising a source of current 153, a transistor 154 and a resistor 156. This voltage to current converter compares the input voltage signal against the reference bias voltage applied to a complementary connected transistor amplifier. The magnitude of the input voltage will affect the conduction of the transistor circuit and produce a proportional output current.
  • the set point loop 122 has an indicator 158 that is connected to an AC source 160 by way of conductors 162, 164, similar to the previously described set point indicator 86, its AC source 89 and conductors 87, 88.
  • Resistors 166, 168, wipers 170, 172, conductor 174, manual connection 176, its associated knob 178 and switch 180 function in the same manner as that previously described under the description of the opposing circuits 54, 78.
  • a suitable position of the wiper 90 of the process variable potentiometer 94 and the wiper 96 of the set point poten tiometer 100 shown in FIGS. 1 or 2 that is found to produce a good quality clinker may be, for example, 100 ohms resistance indicated in the first column of the chart shown in FIG. 4 with settings on the manual resistance values from the joint or in dividual settings of the wipers 170, 172 at the second men tioned control station. In this way greater importance can be given to a particular control station in the determination of the total overall corrective ancillary error signal that is introduced by that particular selective one of several control stations.
  • an automatic set point master controller 194 shown in dotted line form can take the place of the manually adjusted master set point transmitter 32.
  • this automatic set point master controller 194 is connected to a suitable power source, for example AC source 34, and receives a signal whose magnitude varies in accordance with changes in temperature of the calcining zone as sensed by the thermocouple 196.
  • the thermocouple 196 has a pair of leads 198 connected to a thermocouple to current transducer 200 which may be similar to the previously described parts 130, 132, 134.
  • a pair of leads, 202, 204 are shown in dotted line form connecting the transducer 200 with associated slip rings 202, 204 that are in turn fixedly mounted by insulating support members, not shown, on the outer surface of the kiln 74.
  • the output signal produced by the transducer 200 in response to the temperature sensed by the thermocouple 196 is taken from the slip rings 202, 204 by means of brushes 206, 208 and electrical leads 210, 212.
  • the pair of conductors 214, 216 are shown connecting the automatic set point master controller 194 to opposite sides of the resistance 40 in transmission conductor 42.
  • a radiation pyrometer 218 which may be of the'type disclosed in the T. R. Harrison U.S.Pat. No. 2,357,193 is employed to take a measurement of a temperature representative of the clinker 14 being fed through the burning zone of the kiln 74 and to send a signal proportional to this temperature by way of electrical transmission line 220 to a millivolt to current transducer 222.
  • the circuit employed in the millivolt to current transducer 222 is similar to that disclosed in the Edward T. E. Hurd III U.S. Pat. application, Ser. No. 670,822, filed Sept. 8, I967.
  • the current flowing from the transducer 222 is transmitted by a suitable conductor means 224 to a single mode transmitter 50 as a process variable (P.V.) input signal. 7
  • the controlling transmitter 50 receives the set point signal flowing into it by way of conductor 48 compares the aforementioned process variable with this set point signal and produces and transmits an error signal, or signal representative of the difference between the magnitude of process varia ble (P.V.) and set point (S.P.) signal that it receives as a set point input signal by way of the conductor 52 to the master three mode controller l6.
  • P.V. process varia ble
  • S.P. set point
  • the master controller 16 in turn electrically compares the input process variable signal (P.V.) it receives from the differential pressure to current transducer20 by way of conductor l8 with the previously mentioned error signal in the form of a set point signal (S.P.) and produces and transmits another error signal equal to the difference in the two input signals by way of the conductor 226 to a motorized valve 228.
  • the signal applied to the motorized valve 228 in the aforementioned manner will regulate the flow of the fuel that is allowed to pass through conduit at 28 to the burner 30 to a desired value that will continue to produce a good quality clinker 14.
  • circuitry employed for the manually adjusted vertical scale set point indicators 86, 158; the vertical scale process variable indicators 76, 124; the manually adjusted set point master transmitter 32; the automatically adjusted set point-transmitting controller 194; the single mode-transmitting controller 50 and the three mode master-indicating controller 16 is covered by the circuitry shown in the Newbold U.S. Pat. No. 3,081,425, filed Aug. 28, 1959 and its associated reissued U.S. Pat. No. 26,516.
  • the wipers 90, 96, 170 and/or 172 can be jointly or individually manually adjusted to other resistance values, for example 50 ohms or 150 ohms, to obtain a lower or higher range of ancillary DC voltage value that can be introduced into the transmission lines 42, 44. This may be desirable to correct for any undesired heating or cooling of the material 12 as it passes through the furnace because it is of a different quality and quantity to the material just described.
  • resistance values lower than the 50 ohm values or higher than the 150 ohm values can be used where an application requires a different range in ancillary signal than that described supra and shown on the drawings to correct the temperature condition of the material 12 passing through any particular portion of the furnace so that preliminary desirable steps will be taken to obtain a good quality clinker before the material 12 reaches the burning zone of the furnace 74.
  • the joint or individual settings of the wipers 90, 96 of the first mentioned S.P.-P.V. control station shown on the right side of FIG. 1 can be set at different potential and the master set point transmitter 32 that is required to obtain this quality clinker may be found to be the 12 milliamps value shown in the second column chart shown in FIG. 4.
  • the set point-adjusting knob 116 in FIG. 1 is the process variable value on indicator 76 is 4. 8. l2, 16, or 20 milliamps.
  • a control apparatus to optimize the heat required to convert a granular material passing through a multizone furnace into a material having a preselected density and hardness prior to, during, and after a furnace upset occurs comprising the combination of a master controller, a means operable to transmit a process variable signal to the controller whose magnitude is proportional to the rate of fuel being supplied by way of a final control means through the final-end zone of the furnace, a transmitter operably connected to transmit a preselected set point signal to the controller and at least one pair of electrical current opposing set point process variable loops forming an ancillary signal-producing circuit operably connected with the transmitter to algebraically alter the magnitude of the set point signal that is being transmitted by the transmitter to the controller in accordance with temperature changes taking place in any other different zone of the furnace and the final control means being operably connected with the controller to regulate the rate of fuel flowing into the furnace in accordance with the difference in magnitude of the combined set point and process variable signals.
  • control apparatus defined in claim I wherein a pair of said opposing set point process variable loops are associated with two heating zones of the furnace which precede the final end zone of the furnace, said apparatus being operably connected with the transmitter to alter the magnitude of the set point signal being transmitted by thetransmitter in accordance with the temperature of the-last two mentioned zones and wherein the granular material is a cement mix and the end product produced by the furnace is clinker.
  • each of said pair of opposing set point process variable loops are electrically connected to one another by means of a potentiometer, and a mechanical means is operably connected to said potentiometers to provide the same simultaneous joint resistance adjustment of each potentiometer.
  • each of said pair of opposing set point processvariable loops are electrically connected to one another by means of a poten' tiometer and a mechanical means is operably connected to said potentiometers to provide a separate resistance adjust ment of each potentiometer.
  • each of the process variable loops are connected to an associated process variable indicator and each of the set point loops are connected to an associated manually adjusted set point indicator
  • separate switches are employed to electrically cut off each of the set point loops with the transmitter
  • manual adjusting means is employed to line out the value of the set point indicator with the value on the process variable indicator while the switch is in a closed position and means to open the switch and connect each of the set point loops with the transmitter after the value of their set point indicator has been manually lined out with the value of the process variable indicator and a resulting zero ancillary error signal is being produced by each of said process variable set point loops.
  • each of said pair of opposing set point process variable loops are electrically connected to one another by means of a potentiometer and a mechanical means is operably connected to said potentiometers to provide a separate resistance adjustment of each potentiometer and wherein an adjustment of the mechanical means associated with one pair of potentiometers associated with one of the pairs of loops that is different from the adjustment of the mechanical means connected with another pair of potentiometers associated with a different pair of process variable set point loops will provide a selective means by which one of said set point process variable loops is given greater importance in the roll it plays in producing the overall ancillary error signal that is produced by the sum of these pairs of loops.
  • thermocouple to current-transducing means associated with the preheating zone of the furnace is operably connected to said process variable loop forming a portion of the ancillary signal-producing circuit to supply an electrical error signal proportional to the temperature of the preheating zone thereto.
  • a second transmitter operably connected with a primary temperaturesensing element in a burning zone of the furnace is employed to form a second process variable signal-producing circuit operably connected to the first mentioned transmitter to alter the magnitude of the set point signal produced thereby in accordance with temperature changes taking place in the burning zone.
  • a pair of said opposing set point process variable loops are as sociated with the preheating and calcining zones of the furnace and are operably connected with the transmitter to alter the magnitude of the set point signal being transmitted by the transmitter in accordance with the temperature of the respective preheating and calcining zones andwherein the granular material is cement mix and the end product produced by the furnace is clinker.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Temperature (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)
  • Muffle Furnaces And Rotary Kilns (AREA)
  • Furnace Details (AREA)
  • Waste-Gas Treatment And Other Accessory Devices For Furnaces (AREA)
US839449A 1969-07-07 1969-07-07 Furnace profile temperature controller with ancillary signal producing means to maintain furnace at optimal temperature control levels and to minimize adverse effect of upsets Expired - Lifetime US3556496A (en)

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US (1) US3556496A (enrdf_load_stackoverflow)
CA (1) CA935900A (enrdf_load_stackoverflow)
DE (1) DE2032844A1 (enrdf_load_stackoverflow)
GB (1) GB1266099A (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3751215A (en) * 1972-06-12 1973-08-07 Honeywell Inc Deviation proportional analog pulse controlling apparatus
US4157017A (en) * 1973-03-30 1979-06-05 Betty Jane Reid Continuous preparation of soft, melt-resistant, frozen confection
US4759033A (en) * 1987-07-01 1988-07-19 Weyerhaeuser Company Temperature measurement of hot mineral product by induced fluorescence
US4762425A (en) * 1987-10-15 1988-08-09 Parthasarathy Shakkottai System for temperature profile measurement in large furnances and kilns and method therefor
US5426279A (en) * 1993-06-21 1995-06-20 Dasgupta; Sankar Heating rate regulator

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3220085A1 (de) * 1982-05-28 1983-12-01 Klöckner-Humboldt-Deutz AG, 5000 Köln Verfahren und vorrichtung zur regelung des brennprozesses einer zementbrennanlage
CN105135867A (zh) * 2015-09-02 2015-12-09 郑州鼎力新能源技术有限公司 一种适用于烘干滚筒的新型燃烧炉
CN112050626B (zh) * 2019-06-05 2022-10-04 中冶长天国际工程有限责任公司 一种通过优化调整燃料量和风量控制还原回转窑温度的方法

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3366374A (en) * 1965-11-23 1968-01-30 Leeds & Northrup Co Method and apparatus for control of rotary kiln exit gas conditions
US3381946A (en) * 1966-06-07 1968-05-07 Leeds & Northrup Co Method and apparatus for the optimization of kiln cooler control

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3366374A (en) * 1965-11-23 1968-01-30 Leeds & Northrup Co Method and apparatus for control of rotary kiln exit gas conditions
US3381946A (en) * 1966-06-07 1968-05-07 Leeds & Northrup Co Method and apparatus for the optimization of kiln cooler control

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3751215A (en) * 1972-06-12 1973-08-07 Honeywell Inc Deviation proportional analog pulse controlling apparatus
US4157017A (en) * 1973-03-30 1979-06-05 Betty Jane Reid Continuous preparation of soft, melt-resistant, frozen confection
US4759033A (en) * 1987-07-01 1988-07-19 Weyerhaeuser Company Temperature measurement of hot mineral product by induced fluorescence
WO1989000282A1 (en) * 1987-07-01 1989-01-12 Weyerhaeuser Company Temperature measurement of hot mineral product by induced fluorescence
US4762425A (en) * 1987-10-15 1988-08-09 Parthasarathy Shakkottai System for temperature profile measurement in large furnances and kilns and method therefor
US5426279A (en) * 1993-06-21 1995-06-20 Dasgupta; Sankar Heating rate regulator

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GB1266099A (enrdf_load_stackoverflow) 1972-03-08
CA935900A (en) 1973-10-23
DE2032844A1 (de) 1971-02-04

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