JPS5935212A - Temperature controller for furnace with plural heating areas - Google Patents

Abstract

PURPOSE:To heat a body to be heated uniformly without providing any center wall among heating areas by controlling the heating temperature of a heating device while considering temperature interference among the heating areas previously. CONSTITUTION:Temperature signals from temperature sensors 16, 18, and 20 provided in the heating areas A-C respectively are supplied to temperature regulators 60, 68, and 70 provided in the heating areas. Then, the temperature regulators output control signals mT1-mT3 which eliminate deviations from a preset command value. Those control signals are supplied to computing elements 78, 80, and 82 as cross arithmetic means provided in the heating areas respectively. Then, the respective computing elements output operation signals m1- m3 indicating manupilated variables corresponding to the heating areas on the respective control signals and the degree of temperature interference among the respective heating areas, controlling burners 22, 24, and 26 provided in the respective heating areas. Thus, the body to be heated is heated uniformly without providing any partition wall among the heating areas.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for uniformly heating objects within the heating zones without providing partition walls between the heating zones in a furnace having a plurality of heating zones that are adjacent to each other and have temperature interference. The present invention relates to a temperature control device that controls the temperature to the desired temperature.

In order to heat all the objects in the heating furnace to a uniform temperature, the inside of the heating furnace is divided into multiple heating zones that are in contact with each other, and the temperature in each heating zone is independently controlled to the target temperature. things are being done. However, in order to obtain high temperature control accuracy in such cases, it is necessary to reduce mutual interference between the heating zones, so partition walls must be provided between the heating zones, which complicates the structure of the heating furnace. Another disadvantage was that the heating furnace was expensive.

The present invention has been made against the background of the above-mentioned circumstances, and its object is to provide a partition wall between the heating zones in a furnace having a plurality of adjacent heating zones that interfere with each other in temperature. It is an object of the present invention to provide a temperature control device Mk that heats an object to be heated to a uniform temperature without any heating.

In order to achieve all of these objectives, the temperature control device of the present invention includes: (1) a plurality of temperature sensors that are provided in each of the plurality of heating regions and output all temperature signals representing the temperature of the heating region; (2) (8) A plurality of heating devices provided in each of the plurality of heating zones and arranged between the heating zones; (8) comparing a predetermined target temperature with the temperature of each heating zone represented by the temperature signal; adjusting means for calculating the deviation and outputting a control signal corresponding to each of the heating areas so that the deviation becomes zero; and adjusting each control signal based on the degree of temperature interference between the heating areas. an arithmetic and control device that causes the heating device to heat each of the heating regions according to the operating signals;
It is characterized by containing.

In this way, the heating device for heating each heating zone can respond not only to the control signal corresponding to the heating zone, but also to the control signals corresponding to other heating zones and the degree of temperature interference between the heating zones. It is operated by the operation signal calculated based on the
Even in a furnace that does not have partition walls between heating zones and has relatively large temperature interference, the object to be heated can be heated extremely uniformly. In other words, while conventionally the temperature of each heating zone was controlled independently by minimizing the temperature interference between the heating zones, the temperature control device of the present invention controls the temperature based on the degree of temperature interference between the heating zones. Then, based on the control signal corresponding to the heating area and the control signal corresponding to the other heating area that affects the heating area, the manipulated variable 5- for the heating area is calculated, and the operation amount for the heating area is calculated. Since the heating area is heated by the heating device in response to an operation signal that takes into account mutual temperature interference, extremely high temperature control accuracy can be obtained.

According to another aspect of the present invention, the arithmetic and control device outputs a control signal corresponding to a heating area other than a predetermined heating area of the heating area among the control signals outputted by the adjusting means. The present invention is characterized in that it further comprises an updating means for holding the information for a predetermined period of time and periodically updating the information at intervals of the predetermined period.

In this way, the temperature of the predetermined heating area is continuously controlled by the operation signal that is continuously changed by the adjusting means and the cross calculation means, and the temperature of the other heating area is periodically controlled by the updating means. Since the temperature is controlled according to the operation signal calculated based on the updated control signal, the temperature control system becomes more stable and higher temperature control characteristics can be obtained.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below based on the drawings.

6- In FIG. 1, the object to be heated 12 arranged in the group 10 is conveyed by rollers 14, and the object to be heated 12 is transported perpendicularly to the feeding direction of the object to be heated 12. Thermocouples 16, 18 as temperature sensors are installed in the direction, that is, in the width direction of the furnace 10.
20. And burners 22, 24, 26 as heating devices are attached. Therefore, in class 10, burner 2
A first heating area A is mainly heated by the burner 24 and the temperature is detected by the thermocouple 16; a second heating area B is mainly heated by the burner 24 and the temperature is detected by the thermocouple 18; A third heating zone C whose temperature is detected by the pair 20 is the furnace 1
00 It is formed without providing partition walls in the width direction. Therefore, these heating areas A, B, and O exert a certain temperature interference with each other.

Such a furnace 10 is equipped with a control device shown in FIG. That is, the gas pipe 28 is connected to the burners 22, 24, 26 via the control valves 80, 82.84, respectively, and the air pipe 36 is connected to the air control valves 88, 40.4.
They are connected to each other via 2i.

Orifices 44 and 46, which are flow rate sensors, are arranged in the base pipes of the gas piping 28 and the air piping 860. From the orifice 44, a gas flow signal GF representing the total flow rate of fuel gas is sent to the gas flow rate indicator 48. At the same time, it is also supplied to a flow rate regulator 52 via a multiplier 50. The multiplier 50 is supplied with a correction signal 8A from a setting device 54 or an 02 meter 56 installed in the flue of the furnace 10, and the multiplier 50 multiplies the correction signal 8A by the gas flow signal OF. Flow rate controller 52 is supplied. Also, orifice 46
The air flow rate signal AF is supplied to the flow rate controller 52, and the flow rate controller 52 determines the air flow rate relative to the gas flow rate so that a predetermined air-fuel ratio is obtained, and represents the air flow rate. Flow rate command signal OFF corrector 58t-
60.62.64.

On the other hand, from the thermocouples 16, 18, 20, the first heating area A,
Temperature signal T representing the temperature of the second heating area B and the third heating area C
1. T2. TB is a temperature controller 66. as a regulating means.
68.70 through voltage/current converters 72, 74.76, respectively. Temperature control 1i66.68,
Each target temperature is set in advance in 70, and the deviation between the target temperature and the actual temperature of each heating area A, B, and O is calculated, and based on the deviation, the deviation is determined to be zero. Control signals mTl, m'l'2゜mT3 so that
is output from the temperature controller 66,68,70. The target temperatures set for each of the temperature controllers 66, 68, and 70 are generally a common temperature or different temperatures close to the common temperature that take into account the characteristics of the heating zones A, B, and C.

Those control signals mTl, mT2 . mT8 is each heating area A
, B, and O, respectively. Temperature control 1
Contacts 84 of the sampler device are inserted in series on the input and output sides of i68 and 70, respectively, and are periodically closed for about 1 second at predetermined time intervals (on the order of tens of seconds). Control signals m from temperature controllers 68 and 70
T2゜9-mT3 is periodically output to the hold circuit 85.85. The hold circuits 85, 85 have a control signal mT2. rnT3 is held for a predetermined time interval, and a new control signal mT2. mT
3 is supplied, the control signal held in the hold circuits 85.85 is updated to a new control signal mTJmT3. That is, the contact point 8 of the sump and ring device
4 and hold circuits 85 and 85 form updating means.

Arithmetic units 78, 80.82 each control signal mTl, m
T2. Based on mT8 and the degree of temperature interference between heating zones A, B, and C, operation signals ml, m2 . m3 with limiters 86, 88, 9 (l
via the characteristic converter 92,94,96 and the aforementioned multiplier 6
0, 62.64, respectively. In addition, limiter 86.8
8.90 is for cutting fuel at a flow rate below a certain level in order to avoid unstable combustion in the burners 22, 24, and 26.

10- Here, the temperatures of each heating zone A, B, and C of the furnace 10 are TI, T
2. T8, and each heating area A, B.

In order to control the temperature of ml, m2, . m
8, the interference linear heating model equations (1), (2), and (8) as shown in the following equations are obtained.

However, as a', bt b't Ct'' in the above equation is a numerical value that is larger than zero and smaller than 1, indicating the degree of interference between the heating areas A, B, and O, and is determined experimentally for each heating model. This is determined by the following.

Then, the above heating model equations (1), (2), (8)
Based on the control signals mT l, mT2 . mT 8 and operation signals Himl, m2. The non-interference control equation representing the relationship m31i: is derived as follows.

I'll go.

The computing units 78, 80.82 calculate the operation signals ml, m2 according to the non-interference control equations (4), (5), and (6), respectively.
It is configured to calculate ゜m3.

The characteristic converters 92, 94, 96 are gas control valves 80,
Based on the relationship between the valve opening degrees of 82 and 84 and the flow rate, the operation signals ml, m2. The operation signals ml and m2°m3f are respectively converted so that mJ3 and the gas flow rate have a linear relationship. The signal output from the characteristic converter 92°94.96 is converted to the current/pneumatic converter 98, 100, 102'fr:
via which gas regulating valves 80, 82, and 34 are respectively supplied.

The multipliers 60, 62, 64 convert the flow rate command signal OF outputted from the flow rate controller 52 into operation signals ml, m2, .
m3 and the result is transmitted to characteristic converters 104, 106,
108 and current/pneumatic converters 110, 112, 114, respectively, to air regulating valves 88, 40, 42.

That is, in each heating area A, B, O, the gas control valve 80,
Air at a fixed ratio to the fuel flowed by the air control valve 88, 40.42 is caused to flow by the air control valve 88, 40. It represents the ratio (air-fuel ratio). Note that the characteristic converters 104, 106, 108 are configured similarly to the characteristic converters 92, 94, 96 described above, and the multiplier 6
The output signal from 0.62.64 and the air flow rate are arranged to have a linear relationship.

In the control device configured as described above, each heating area A
, B, O, the operation signal m1.
m2. m3 is not only the control signal for the heating area but also the control signal for other heating areas and the heating area A.

Since it is determined from the degree of temperature interference between B and O, for example, the operation signal m1 for heating area A is not only the control signal mTl for controlling the temperature of heating area A, but also the control signal mTl for controlling the temperature of heating area A. Control signals mT2, m for areas B, O
Coefficients derived from the degree of temperature interference between T3 and the heating regions (A1 to A3 in (4), (5), and (6); Bl to B8, C
1 to cB), so heating areas A, B
(Extremely suitable temperature control characteristics can be obtained without providing a partition wall between the three.)

That is, instead of providing partition walls to lower the degree of mutual interference between heating areas A, B, and O, the existence of mutual interference is taken into account in advance,
Control signals for other heating zones are used to control the temperature of the heating zone.

Moreover, the control signal mTl corresponding to the heating area A is continuously changed, and the control signals mT2.mT3 corresponding to the heating area B (3) are held for a predetermined period and periodically updated. Therefore, the temperature control system can be stabilized with a simple configuration, and more desirable and highly accurate temperature control characteristics can be obtained.

According to the inventor's experiments, the results shown in Table 1 were obtained. That is, as shown in FIG. 8, the common target temperature at time 0 seconds is set to 50%, and at time 1000 seconds the common target temperature is set to 50%. Each heating region A shown by the broken line, solid line, and dashed-dotted line when the target temperature of the temperature controller 66 is set to 70% and disturbance is applied.
, B, O with a predetermined degree of interference of 0.8 or 0.
．． 5 and each heating area A.

B, Oi When the temperature is controlled independently (hereinafter referred to as single) and in the control system shown in Fig. 2, operation is performed using the above-mentioned non-interference control calculation formulas (4), (5), (6)'e. In the case where temperature control is performed by determining the amount (hereinafter referred to as cross), the controllability' (judging by I-temperature amplitude) at predetermined times (1000 seconds and 2000 seconds later) is observed by simulation. When the degree of interference is 0.8, the contact 84 is not opened or closed and the control iimT2.
Even when mT3 was continuously changed, as shown in the two examples at the top of Table 1, the cross case was more stable than the single case. Furthermore, even when the sampling device is operated, as shown in Figure 4, when the update cycle changes from 15 seconds to 30 seconds, the single case becomes significantly unstable, while the cross case becomes unstable. It is stable.

Further, when the degree of interference to is set to 5, as shown in FIG. 5, the cross case is much more stable than the single case even if the update cycle changes. Incidentally, the degree of interference in an actual furnace generally does not exceed 0.5 at most. Further, although the vertical axis in FIG. 8 is expressed in %, it can be replaced with an appropriate temperature range.

Although one embodiment of the present invention has been described above, the present invention can also be applied to other aspects.

For example, in the above-mentioned embodiment, the heating area is divided in the width direction within the heating furnace 10, but it may be divided in the direction of movement of the object to be heated 12. Moreover, it goes without saying that the object to be heated 12 does not have to be integral over each heating area, and may be partially divided.

Heating zones A and B formed within the heating furnace 10.

C has 8 zones, but the number of zones may be changed to 2 or 4 or more as appropriate. In such a case, there is no problem even if there are two or more heating regions in which the control signal is continuously output from the humidity controller to the computing unit.

In the embodiments described above, a burner was used as the heating device, but other heating means such as a heater may also be used.

The adjusting means, the RIS calculation means, and the updating means in the above-mentioned embodiments perform the functions of each means. However, the above-mentioned is only one embodiment of the present invention, and the present invention does not depart from the spirit thereof. Various changes may be made without departing from the above.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a heating furnace equipped with an embodiment of the present invention. FIG. 2 is a diagram showing the temperature control system provided in FIG. 1. FIG. 8 is a diagram showing an example of the transient response characteristics of the temperature control system shown in FIG. 2. Figures 4 and 5 are diagrams showing the relationship between the temperature amplitude after a predetermined time and the sampling period in the transient response, comparing the single case and the cross case. 0.8, Figure 5 shows the condition of 18 - 0.5, respectively. 10: Furnace 12: Heated object 16.18,2
0: Thermocouple (temperature sensor) 22. 24, 26: Burner (
Heating device) 66, 68, 70: Temperature controller (control means)
78.80.82: Arithmetic unit (cross computing means) Applicant
Daido Steel Co., Ltd. 19- Figure 1 Figure 4 Sampling period T (+) Figure 5 Sampling time 1! T (seconds)

Claims (2)

[Claims] (1) In a furnace having a plurality of heating zones that are adjacent to each other and have temperature interference, a temperature control device that controls a heated object in the heating zone to a uniform temperature, the temperature control device being provided in each of the plurality of heating zones. , a plurality of temperature sensors that output temperature signals representing the temperature of the heating regions; a plurality of heating devices that are respectively provided in the plurality of heating regions and heat the heating regions; a predetermined target temperature and the temperature. an adjusting means for comparing the temperatures of the respective heating regions represented by the signals to calculate a deviation therebetween and outputting a control signal corresponding to each of the heating regions so that the deviation becomes zero; The heating device is provided with a cross calculation means for calculating an operation signal representing an operation amount corresponding to the heating area based on the control signal and the degree of temperature interference between the heating areas, A temperature control device for a furnace having a plurality of heating zones, characterized in that the device includes a calculation control device that heats each of the heating zones. (2) In a furnace having a plurality of heating zones that are in instant contact with each other and have temperature interference, a temperature control device that heats the object to be heated in the heating zone to a uniform temperature, the temperature control device being provided in each of the plurality of heating zones. , a plurality of temperature sensors that output temperature signals representing the temperature of the heating regions; a plurality of heating devices that are respectively provided in the plurality of heating regions and heat the heating regions; a predetermined target temperature and the temperature. an adjusting means that compares the temperature of each heating area represented by the signal and calculates a deviation thereof, and outputs a control signal corresponding to each of the heating area so that the deviation becomes zero; an updating means for holding a control signal corresponding to a heating area other than the predetermined heating area for a predetermined period of time and periodically updating it at intervals of the predetermined period; a control signal updated by the updating means; cross calculation means for respectively calculating an operation signal representing an operation mk corresponding to each heating area based on a control signal corresponding to the predetermined heating area and a degree of temperature interference between the heating areas; A temperature control device for a furnace equipped with a plurality of heating zones, characterized in that the device includes an arithmetic and control device that heats each of the heating zones according to the operation signal.