JP2005308310A - Furnace temperature control method and device for heating furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize the control of furnace temperature with a simple means, capable of obtaining a proper heating temperature to solve a problem in a heating furnace where a heated object is heated while being moved on a hearth, that a heating process is kept in an nonconstant state when a carrying-in-and-out volume and carrying-in intervals of a heating material are widely fluctuated, which causes the wide fluctuation of the heating temperature. <P>SOLUTION: A measurement unit 26 for measuring a sheath temperature of a heated object moving passage is mounted at an inlet side of a heating zone independently of a furnace atmospheric temperature measuring unit 15 of the heating furnace 10, a furnace temperature for control Tg is calculated on the basis of a formula : Tg=T<SB>1</SB>(1-α)+T<SB>2</SB>×α (α is weighting coefficient determined on the basis of combustion load) based on a measured value T<SB>1</SB>of the atmospheric temperature measuring unit 15 and a measured value T<SB>2</SB>of the sheath temperature measuring unit 26, and the combustion is controlled on the basis of the furnace temperature for control Tg. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a furnace temperature control method and apparatus for a heating furnace. More specifically, in an industrial heating furnace having a large combustion load fluctuation, the control furnace temperature corresponding to the combustion load fluctuation is calculated to appropriately heat the heating material. The present invention relates to a furnace temperature control method and apparatus for a heating furnace that can be performed.

  In a normal heating furnace, the furnace temperature measured at one place in the combustion control zone is used as the representative furnace temperature, or the furnace temperature measured at a plurality of places is averaged or weighted average to obtain the representative furnace temperature. Based on this, combustion control and temperature control are performed. Further, there is a case where an arbitrary set value is selected from the furnace instrumentation device to obtain the representative furnace temperature.

  However, in any case, the conventional control cannot be said to calculate the representative furnace temperature sufficiently reflecting the load fluctuation.

  In the case of a heating furnace with a large furnace volume and a large combustion load fluctuation range, the gas flow in the furnace is biased at the minimum combustion, and the difference in furnace temperature between the vicinity of the thermometer for measuring the furnace temperature and the vicinity of the heating material increases. There is a case. In particular, in the case of a furnace in which the burner is disposed only at a position above the heating material, for example, the combustion gas flows along the ceiling, so that the difference in the upper and lower temperatures in the furnace becomes large.

  When the material to be heated enters the heating zone in the furnace in an empty furnace state, the furnace temperature on the heating zone entry side rapidly decreases. The conventional representative furnace temperature cannot detect this drop, and until the heating material affects the furnace temperature control thermometer, the actual heating furnace temperature will be significantly different from the furnace temperature to be set. It has become. Such temperature control generates a region where heating is insufficient or unstable.

  However, if the furnace temperature is controlled using the heating zone inlet side temperature, overheating may occur on the heating zone outlet side.

  When measuring the temperature of the steel material being heated using a radiation thermometer, the temperature of at least two furnace wall portions that have a radiation effect on the steel material at the temperature measurement position is measured, and this temperature measurement value is measured on the surface of the steel material. There is a technique for correcting the temperature measurement value of the radiation thermometer by calculating the degree of influence of the entire furnace on the radiation temperature measurement of the steel material surface temperature as a primary combination of radiation (see, for example, Patent Document 1).

  This technique corrects the influence of radiation from the furnace wall of a radiation thermometer that measures the surface temperature of steel. This technology takes into account that the temperature distribution in the furnace is not uniform, measures the furnace wall temperature at at least two locations, calculates the degree of influence on radiation temperature measurement as a primary combination of radiation given to the steel surface, and calculates the radiation temperature It corrects the temperature measurement value of the meter. Although this technique is an excellent technique, it cannot provide proper control in an unsteady state.

  In addition, two holes are provided in the furnace wall, a heated object is measured from one opening with a radiation thermometer, a thermometer is projected from the other opening, the ambient temperature in the furnace is measured, and the radiation temperature is measured. There is also a technique for correcting the temperature of the heated object by correcting the output signal of the meter with the output signal of the thermometer that measures the furnace atmosphere temperature (see, for example, Patent Document 2).

  In this technique, since the radiant energy radiated from the furnace wall reflects the object and enters the radiation thermometer, it is difficult to accurately measure the surface temperature of the object. This technique can correct the surface temperature of an object in a steady-state heating furnace, but the measurement accuracy is unclear in an unsteady state.

Moreover, in the above prior art, although the surface temperature of the material to be heated is used as a control factor, the furnace atmosphere temperature may be used as an index for temperature control.
Japanese Patent Laid-Open No. 57-10424 (page 1-2, FIG. 1) JP 61-292528 A (page 2-3, FIG. 1)

  In a heating furnace with a small load fluctuation, an appropriate heating temperature of the heating material can be achieved by using a temperature at a certain position such as the atmosphere in the furnace as an index.

  However, in a heating furnace having a large load fluctuation, for example, when the amount of the heating material carried in and out and the carry-in interval fluctuate greatly, the heating process becomes unsteady and the heating temperature fluctuates greatly.

  An object of the present invention is to realize dynamic furnace temperature control capable of obtaining an appropriate heating temperature in such a case by simple means.

  The present invention is a technique devised to achieve the above-described problems. That is, the present invention relates to a furnace that heats a heated object while moving it on the hearth, and separately measures the hearth temperature in the vicinity of the heating object moving path on the heating zone entry side, separately from the furnace atmosphere temperature measuring device. Heating characterized by providing a temperature measuring device, calculating a control furnace temperature from the measured value of the ambient temperature measuring device and the measured value of the hearth temperature measuring device, and performing combustion control based on the control furnace temperature This is a furnace temperature control method for a furnace.

  It is preferable that the control furnace temperature is calculated by the following equation.

Tg = T ₁ (1−α) + T ₂ · α
However, Tg: Control furnace temperature T ₁ : Atmospheric temperature measuring device indication value T ₂ : Hearth temperature measuring device indication value α: Weighting coefficient determined by combustion load The apparatus of the present invention for suitably carrying out the above-described method of the present invention In a heating furnace that heats a heated object while moving on the hearth, a furnace atmosphere temperature measuring device, a hearth temperature measuring device provided near the heating object moving path, the atmosphere temperature measuring device, and the hearth temperature measuring device And a combustion controller that performs combustion control based on the output of the arithmetic device, and a combustion output device that outputs the combustion output to the burner by the output of the combustion controller. This is a furnace temperature control device for a heating furnace.

  In a heating furnace with a large load fluctuation, for example, when the amount of the carry-in / out of the heating material and the interval greatly fluctuate, the heating process becomes unsteady and the heating temperature fluctuates greatly.

  According to the present invention, furnace temperature control capable of obtaining an appropriate heating temperature in such a case can be realized by simple means.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a flow sheet showing a furnace temperature control method of a heating furnace according to an embodiment of the present invention.

  The heating furnace 10 loads the heating object 30 from the heating zone inlet 11 and advances the heating object 30 on the furnace floor 16 in the traveling direction indicated by the arrow 12. The heated object 30 is heated by the frame 14 of the burner 13. The burner 13 is controlled by a combustion output device 25. Conventionally, combustion output control is performed by the measured temperature of the furnace atmosphere temperature measuring device 15.

  In the present invention, in the heating furnace 10 that heats the heating object 30 while moving on the hearth 16, separately from the furnace atmosphere temperature measuring device 15, the hearth temperature near the heating object moving path on the heating zone entrance side is measured. A hearth temperature measuring device 26 is provided. The measured value of the atmospheric temperature measuring device 15 and the measured value of the hearth temperature measuring device 26 are input to the control device 20, the control furnace temperature is calculated, and combustion control is performed based on the control furnace temperature.

  The measured values of the atmospheric temperature measuring device 15 and the hearth temperature measuring device 26 are input to the arithmetic unit 22 via the amplifier 21. The arithmetic unit 22 calculates the control furnace temperature by the following equation, for example.

Tg = T ₁ (1−α) + T ₂ · α
However, Tg: Control furnace temperature T ₁ : Atmospheric temperature measuring device indication value T ₂ : Hearth temperature measuring device indication value α: Weighting coefficient determined by combustion load Here, the weighting coefficient α determined by combustion load is the heating furnace concerned It is a coefficient determined by specific characteristics, heating object conditions, heating temperature, direct heating history, and other factors, and can be determined by learning test operation data.

FIG. 2 is a graph showing an example. When the combustion load is small, α = 1 as shown by the curve 41, that is, the control furnace temperature Tg is dominated by the measured value (T ₂ ) of the hearth temperature measuring device 26, and when the combustion load becomes large, the curve As indicated by 42, α rapidly becomes 0, and the indicated value (T ₁ ) of the ambient temperature measuring instrument 15 becomes dominant. In these intermediate unsteady states, as indicated by the curve 40, the value changes according to the combustion load.

  The control furnace temperature calculated by the calculation device 22 is output to the temperature control device 23. The temperature control device 23 provides appropriate combustion control information to the combustion control device 24 according to the control furnace temperature, and the combustion control device 24 performs combustion. The output device 25 is controlled.

  As shown in FIG. 1, the furnace temperature control device 20 of the present invention is used in a heating furnace that heats a heated object while moving on the hearth, and is provided in the furnace ambient temperature measuring device 15 and in the vicinity of the heated object moving path. A hearth temperature measuring device 26, a computing device 22 that calculates a representative furnace temperature from the measured values of the ambient temperature measuring device 15 and the hearth temperature measuring device 26, and a combustion control device 24 that performs combustion control based on the output of the computing device 22. And a combustion output device 25 that outputs the combustion output to the burner according to the output of the combustion control device 24.

It is a flow sheet of an example. It is a graph which shows an example of the weighting coefficient of an Example.

Explanation of symbols

10 Heating furnace 11 Heating zone inlet 12 Traveling direction (arrow)
DESCRIPTION OF SYMBOLS 13 Burner 14 Frame 15 Ambient temperature measuring device 16 Hearth 20 Control device 21 Amplifier 22 Arithmetic device 23 Temperature control device 24 Combustion control device 25 Combustion output device 26 Hearth temperature measuring device 30 Heating object 40 Weighting coefficient curve 41 Curve ( Horizontal part)
42 Curve (vertical part)

Claims (3)

  In a heating furnace that heats a heated object while moving on the hearth, a hearth temperature measuring device that measures the hearth temperature near the heating object moving path on the heating zone entry side is provided separately from the furnace atmosphere temperature measuring device, A furnace temperature control method for a heating furnace, characterized in that a control furnace temperature is calculated from a measured value of the ambient temperature measuring instrument and a measured value of a hearth temperature measuring instrument, and combustion control is performed based on the control furnace temperature. . The furnace temperature control method for a heating furnace according to claim 1, wherein the control furnace temperature is calculated by the following equation.
Tg = T ₁ (1−α) + T ₂ · α
However, Tg: Control furnace temperature T ₁ : Atmospheric temperature measuring device indicated value T ₂ : Hearth temperature measuring device indicated value α: Weighting coefficient determined by combustion load   In a heating furnace that heats a heated object while moving on the hearth, a furnace atmosphere temperature measuring device, a hearth temperature measuring device provided near the heating object moving path, the atmosphere temperature measuring device, and the hearth temperature measuring device An arithmetic device that calculates a representative furnace temperature from the measured value, a combustion controller that performs combustion control based on the output of the arithmetic device, and a combustion output device that outputs the combustion output to the burner by the output of the combustion controller A furnace temperature control device for a heating furnace.

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