JPS6217479Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a control device for a heating furnace.

As shown in Fig. 1, a conventional temperature control device for a heating furnace detects the combustion of a burner c that heats a metal material b moving inside a heating furnace a using a temperature detector d that detects the temperature inside the furnace. The fuel flow rate is controlled by adjusting the fuel flow rate via the control valve f based on an output signal based on the difference between the temperature set at the temperature controller e and the temperature set on the temperature controller e. In the figure, g indicates a flowmeter, and h indicates the furnace bottom.

However, due to changes in the dimensions of material b and the production amount (material charging amount) of material b, the temperature inside heating furnace a is
The curves i, j, and k shown in the figure change, and therefore, unlike the conventional method, the combustion of burner c is determined based only on the detected temperature of temperature sensor d installed in the vicinity of burner c, for example. However, in the case where the control is performed, there are the following problems.

(b) When the furnace temperature is set to curve i in Figure 2, if the temperature changes as shown by curves j or k, the furnace bottom h temperature will become higher than necessary, resulting in a large loss in fuel consumption. was coming.

(b) Since it is based on the detection of only one control zone, the temperature distribution in the furnace will change as it happens, and especially if overheating as shown in curve k occurs during low-temperature heating of material b, In some cases, the quality deteriorated and it became unusable.

(c) In order to prevent the above-mentioned deterioration conditions, skilled workers often manually adjust the burner c, but this requires a lot of manpower for maintenance.

(d) The temperature near the furnace tail h had increased, and heat loss due to heat radiation from the furnace body had also increased.

The present invention was made to solve the problems of the conventional device described above, and includes a plurality of temperature detectors arranged at a required interval on the same axis as the flame jet direction of the burner in the heating furnace, and A comparator is provided to compare the detected temperatures from each of the temperature detectors, and a maximum temperature signal from the comparator controls a flow rate controller via a temperature controller and a ratio setting device to adjust the fuel flow rate to the burner. A control device for a heating furnace, characterized in that a circuit is provided for controlling the signal from the temperature controller in the ratio setting device based on a temperature difference signal from the expected temperature from the comparator. This is related.

Embodiments of the present invention will be described below with reference to the drawings.

Figure 3 shows an example of the present invention.
On the same axis as the flame ejection direction of burner 2 installed in
A plurality of temperature detectors 3, 4, and 5 are provided at appropriate intervals. Fig. 3 shows the case where the burner is installed in three places, for example, 3 is from the inner wall of the burner 2 mounting part 6 of the heating furnace 1.
The position 5 shall be within about 1 m, the position 5 shall be within the length of the flame of burner 2 (approximately 1.5 to 8 m) + 1 m, and 4 shall be the required intermediate position between 3 and 5.

Further, a comparator 7 connected to the temperature detectors 3, 4, 5 is provided, and output signals 8, 9 from the comparator 7 are provided.
A flow rate controller 1 adjusts a flow rate control valve 12 via a temperature controller 10 and a ratio setting device 11 based on
The system is configured to perform the following control. 14 in the figure is the bottom of the furnace.
15 indicates a metal material.

The metal material 15 charged into the heating furnace 1 from the furnace tail 14 side is heated to a target temperature by the burner 2 while being moved as shown by the arrow in FIG. At this time, the temperature of the material 15 is lower as it is closer to the bottom of the furnace 14 (on the charging side), so the temperature inside the furnace is generally the same as curve 1 in FIG.
6 (temperature curve set to minimize fuel consumption).

The temperature inside the furnace is detected by temperature detectors 3, 4, and 5 and input to a comparator 7. Among the input signals, the higher temperature signal 8 from the temperature detector 3 or 5 is sent to the ratio setter 11 via the temperature controller 10, and further sent to the flow rate controller 13, which controls the flow rate control valve 1.
2. Opening control is performed.

Although the above circuit does not yet take into account the temperature distribution within the furnace, the present invention performs control in consideration of the temperature distribution within the furnace as follows.

That is, in the comparator 7, when the temperatures detected by the temperature detectors 3, 4, and 5 are respectively, the temperature is compared with the assumed curve 16 based on the temperature as shown in FIG. Temperature difference - = Curve ₁ where the temperature is higher by Δt ₂ than Δt 1
6', the temperature difference signal 9 is sent to the ratio setting device 11. Accordingly, the temperature difference signal 9 causes the ratio setter 11 to throttle down the output signal from the temperature controller 10, thereby controlling the signal sent to the flow rate controller 13 to be correspondingly smaller, thereby reducing the output signal of the flow rate control valve 12. The opening degree is narrowed accordingly, and the fuel flow rate to the burner 2 is reduced.

At this time, when the output signal of the flow rate controller 13 is Iout and the input signal of the flow rate control valve 12 is Iin, Iin=Iout×K, 0K1. This constant K is determined by the amount of Δt ₂ in the comparator 7.

By doing so, it is possible to control the temperature pattern in the furnace above the flame ejection direction of the burner 2 so that it approaches the expected value.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and that the number of temperature detectors can be changed in various ways as long as it is two or more, the installation position of the temperature detector can be changed in various ways, and other improvements can be made. Of course, various changes may be made without departing from the gist of the invention.

According to the heating furnace control device of the present invention described above,
A circuit is provided that includes a plurality of temperature detectors and a comparator that compares the temperatures, and also controls the flow rate of fuel to the burner based on the maximum temperature signal. By providing a circuit that narrows down the temperature signal, the following excellent effects can be achieved.

(i) If the dimensions of the metal material change, especially the width,
Unlike conventional one-point detection control, unnecessary overheating of the bottom temperature of the furnace can be prevented and fuel consumption can be reduced.

(ii) Even if the heating production amount of the material changes significantly, especially if the amount of material after the temperature sensor 3 suddenly decreases, the fluctuation in fuel consumption is reduced by the function of the throttle circuit, Stable heating operation can be achieved.

(iii) Overheating can be prevented with respect to the set furnace temperature, and the quality and yield of low-temperature materials can be improved.

(iv) Automatic control is ensured and no manual adjustment of the burner is required.

(v) Small fluctuations in furnace temperature reduce heat loss from the furnace body.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional heating furnace control device, FIG. 2 is an explanatory diagram of the furnace temperature in FIG. 1, FIG. 3 is an explanatory diagram showing an embodiment of the control device of the present invention, and FIG. The figure is an explanatory diagram of the furnace temperature in FIG. 3, and FIG. 5 is an explanatory diagram showing the principle of temperature difference detection in a comparator. 1 is a heating furnace, 2 is a burner, 3, 4, 5 is a temperature detector, 7 is a comparator, 8 is a maximum temperature signal, 9 is a temperature difference signal, 10 is a temperature controller, 11 is a ratio setter,
12 is a flow control valve, and 13 is a flow controller.

Claims (1)

[Scope of utility model registration request] A plurality of temperature detectors are provided at required intervals on the same axis as the flame jet direction of the burner in the heating furnace, and a comparator is provided to compare the detected temperatures from each of the temperature detectors, and the comparator A circuit is provided which controls a flow rate controller via a temperature controller and a ratio setter to adjust the fuel flow rate to the burner based on the maximum temperature signal from the comparator, and a temperature difference signal from the expected temperature from the comparator. A heating furnace control device, characterized in that the ratio setting device is provided with a circuit that throttles a signal from the temperature controller.