JPS6293315A - Method for controlling temperature of annular continuous heat treating furnace - Google Patents

Abstract

PURPOSE:To accurately control furnace temp., by detecting temp. in an inner cover, inputting the signal to fuel controller through communication bus to adjust flow rates of fuel and combustion air. CONSTITUTION:Temp. in the inner cover 2 is detected by a thermocouple 4 and the temp. signal is inputted to fuel controller through communication bus via meter mounting cart moving along fixed furnace. At first, a temp. indicating controller 10 calculates the difference between the detected temp. and a prescribed temp. to output the result to a fuel flow re indicating controller 11 and output it to a combustion air flow rate indicating controller 13 via an air ratio setting device 12. The controller 11 controls fuel flow rate flowing to a burner 7 through a flow rate adjusting valve 15, based on the difference between a prescribed value from the controller 10 and the detected flow rate of an orifice plate 14. The controller 13 controls combustion air flow rate through a flow rate adjuster 17 based on the difference between prescribed value of the device 12 and the detected flow rate of an orifice plate 16. In this way, temp. of a coil 3 in the cover 2 can be controlled at the desired value.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a temperature control method in an annular continuous heat treatment furnace.

(Prior art) An annular continuous heat treatment furnace, in particular a heat treatment furnace in which an inner cover and a strip coil are mounted on a running carriage, and the strip coil is annealed while the running carriage runs inside a fixed annular furnace, is disclosed in, for example, Japanese Patent Publication No. This method is known as shown in Japanese Patent Application Laid-open No. 51-1111311 and Japanese Patent Application Laid-Open No. 57-711128.

The present invention relates to a temperature control method in such a heat treatment furnace, but the conventional temperature control method was as shown in FIG. That is, the ambient temperature of the fixed furnace 1 is input to the temperature indicating controller 10 through the temperature converter 9 using the thermocouple 8 attached to the ceiling wall (or side wall) of the fixed furnace 1 as a detection end. The temperature indicating controller IO calculates the difference between the set temperature and the detected temperature and outputs it to the fuel flow rate indicating controller 11, and also outputs it to the combustion air flow rate indicating controller 13 via the air ratio setting device 12. The fuel flow rate indicator controller 11 uses the output of the temperature indicator controller IO as a set value, calculates the difference between the output and the flow rate detected by the orifice plate 14, and drives the flow rate control valve 15, so that the fuel flow rate flowing into the burner 7 is equal to the set value. control so that The combustion chamber air flow rate indicating controller 13 uses the output from the air ratio setting device 12 as a set value, calculates the difference between the output from the flow rate detected by the orifice plate 16, and drives the flow rate control valve 17, thereby adjusting the amount of combustion air flowing into the burner 7. Control is performed so that the flow f door is at the set value.

(Problems to be Solved by the Invention) In the above temperature control method, the temperature detection position is near the furnace wall of the fixed furnace 1 and is away from the position of the coil 3 in the inner cover 2, so the actual coil temperature is quite different. Therefore, in order to detect the temperature near the coil, a thermocouple 4 is installed inside the inner cover 2, the temperature inside the inner cover 2 is monitored by a temperature indicator 6 through a temperature converter 5, and the temperature and the thermocouple 8 are detected. When the difference between the temperature and the ambient temperature of the fixed furnace is large, the setting value of the temperature indicating controller 10 is corrected. However, even in this case, the thermocouple 4 moves within the annular furnace together with the inner cover 2 and coil 3 as the traveling carriage moves, so even if the set value of the temperature indicating controller 10 is to be corrected, it is not automatically corrected. This is difficult to do, and in the past, workers had to manually correct the settings.

In such manual setting correction, monitoring the temperature inside the inner cover 2 using the temperature indicator 6 is complicated, and the setting correction itself has to be intermittent.

SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a temperature control method that directly uses a detected temperature value inside an inner cover to control combustion.

(Means for Solving the Problems) The method of the present invention for this purpose is based on a continuous heat treatment furnace in which the strip coil is annealed while the traveling carriage carrying the inner cover and the strip coil is moved through the annular fixed furnace. In the control method, a temperature detection end is installed inside the inner cover to detect the temperature inside the inner cover, and the detected temperature signal is sent to a fixed installation via an instrument-equipped vehicle that moves along a fixed furnace in synchronization with a traveling trolley. This is a temperature control method for an annular continuous heat treatment furnace configured to control the flow rate of fuel and combustion air according to the difference between the detected temperature inside the inner cover and the target temperature by inputting the input to the combustion control device via the communication bus. be.

(Examples and effects) The present invention will be explained in detail below based on illustrated embodiments.

FIG. 1 is a diagram showing the overall configuration of an apparatus in an embodiment of the present invention. In the figure, the same reference numerals as in the t54 diagram indicate the same equipment, etc. In this embodiment, the inner cover 2
Temperature input converter 1 with thermocouple 4 installed inside as the detection end
8. Input the temperature inside the inner cover to the temperature indicating controller 10 via the communication control device 18. Temperature indicating controller 10
calculates the difference between the set temperature and the detected temperature and outputs it to the fuel flow rate indicator controller 11, and also outputs it to the combustion air flow rate indicator controller 13 via the air ratio setting device 12. The fuel liquid level indicator controller 11 calculates the difference between the output of the temperature indicator controller 10 as a set value and the flow rate detected by the orifice spray (orifice spray) 14, and drives the flow rate control valve 15 to control the fuel flow rate flowing to the burner 7. Control so that the set value is achieved.

The combustion air flow rate indicating controller 13 uses the output from the air ratio setting device 12 as a set value, calculates the difference between the output from the air ratio setting device 12 and the flow rate detected by the orifice spray (1B), drives the flow rate control valve 17, and controls the combustion air flowing into the burner 7. Control the flow rate to the set value. In this way, the temperature inside the inner cover, that is, the temperature of the coil 3, is controlled to a desired temperature.

Fig. 2 is a diagram showing the instrumentation system in the embodiment of Fig. 1, and shows the controllers, etc. of Fig. 1 and their connections in the form of a digital controller and communication bus in the field of instrumentation technology. It is something. Each controller etc. 10-13
is connected to a communication control device, and from the communication control device to a communication bus 21.22 via a connector 23. Temperature detection inside the inner cover is performed for all inner covers in the fixed furnace 1, and a temperature input converter 1 is provided for each of an appropriate number m (for example, 8) inner covers.
8 is input. Temperature input converter 18 is communication control device 1
Communication bus 21-1 from 9-2 via connector 23-1
．． 22-1.

Further, the communication bus 21.22 is a circular communication bus 21-2.
.

22-2 through connectors 23-2. The communication bus 21-1.22-1 is a circular communication bus 21-2.
22-2 through connectors 23-3. Since the communication buses 2+-1 and 22-1 move with the movement of the inner cover, they are attached to and detached from the circular communication buses 2+-2 and 22-2 using the detachable connector 23-3 to continue communication.

The communication buses 21.22 and 21-1.22-1 and 2+-2, 22-2 are two-pronged, and normally one communication bus is used for communication, while the other communication bus is used for communication. This allows communication to continue without delay when the communication bus breaks down or when switching connectors.

FIG. 3 is a plan view showing the arrangement of the fixed-side controller, etc. and the movable-side controller, etc. of FIG. 1. 24 is a fixedly installed driver's cab, and a panel (or housing) 25 has a controller etc. 10.
~13 are installed. 26 is a vehicle equipped with instruments that rotates and moves in synchronization with the movement of the traveling cart, and a panel (or housing) 27 has a temperature input converter and a communication control device 19-
2 is installed.

This instrument-equipped vehicle 2G rotates 3600 times along the fixed furnace, so the panel (or housing) inside the instrument-equipped vehicle 2θ
The communication buses 21-1 and 22-1 extending from 27 are also rotated 360 degrees, and the circular communication bus 2]-
If the communication bus 21-1, 22-2 is fixedly connected to only one place, the communication bus 21-1, 22-1 will be twisted, leading to disconnection. For this reason, in this embodiment, the circular communication bus 21-2, 22-2 is divided into six equal parts in the circumferential direction, a connector is provided for each Boo, and the instrument-equipped vehicle 26 is moved approximately 60 degrees from the position indicated by the solid line and When the vehicle reaches the position indicated by the dotted line, disconnect the communication bus 21-1.22-1 of the instrument vehicle 26 from the connector 23-31 of the circular communication bus 21-2. Closer connector 23-
Reconnect to 32.

At this time, when the connection of the negative connector is being switched, communication is continued through the other connector, which is why duplication of the communication bus is necessary.

In this way, if the connectors are reconnected every time the instrument-equipped vehicle moves by 60 degrees, communication can be continued without disconnection of the communication buses 21-1, 22-1.

(Effects of the Invention) Since the temperature control method of the present invention has the following configuration, it has much better accuracy than the conventional method of controlling based on the temperature detected by a one-digit thermocouple installed in the furnace. coil heating,
Soaking temperature can be controlled. Table 1 is a table showing an example of the effects of the method of the present invention, and shows the difference between the target temperature and the actual temperature during heating and soaking of the coil.

Table 1 As is clear from Table 1, according to the method of the present invention, the deviation of the coil temperature from the target temperature during heating and soaking is 1/2 that of the conventional method.
~175, and the control accuracy is significantly improved compared to the conventional method.

[Brief explanation of drawings]

Figures 1 to 3 are diagrams showing the device configuration in an embodiment of the present invention. Figure 1 is a diagram showing the overall configuration, Figure 2 is a diagram showing an instrumentation system, and Figure 3 is a diagram showing a controller, etc. FIG. 4 is a diagram showing the arrangement, and FIG. 4 is a diagram showing the device configuration in a conventional method. l...fixed furnace, 2, 2-1...inner cover,
3... Coil, 4, 4-1... Thermocouple, 5...
Temperature converter, 10... Temperature indicating controller, 11... Fuel flow rate indicating controller, 12... Air ratio setting device, 13...
・Combustion air flow rate indicator controller, 1st...Temperature input converter, 19.19-1.19-2...Communication control device, 20
...Temperature indicator, 21.21-1.21-2.22°22-1.22-2...Communication bus, 23.23-1.
23-2.23-31.23-32...Connector, 2
4... Driver's cab, 25... Panel (housing), 26...
・Vehicle with instrument, 27... (casing).

Claims (1)

[Claims] In a temperature control method in a continuous heat treatment furnace in which the strip coil is annealed while a running cart carrying the inner cover and the strip coil is run inside a fixed annular furnace, a temperature detection end is installed inside the inner cover. Detects the temperature of the inner cover, and inputs the detected temperature signal to the fixedly installed combustion control device via the communication bus via an instrument equipped vehicle that moves along the fixed furnace in synchronization with the traveling trolley, and detects the temperature inside the inner cover. A temperature control method for an annular continuous heat treatment furnace configured to control the flow rate of fuel and combustion air according to the difference between temperature and target temperature.