SU785631A1 - System for automatic control of heat condition of heating furnace - Google Patents

Description

The invention relates to the automatic regulation of thermal objects and can be used in metallurgy and mechanical engineering.

A well-known combustion control system with feedback on the quality of fuel combustion is the optical density of the exhaust gases. The system includes a flue gas optical density sensor, a temperature controller and an actuator on the fuel pipe [1].

A device for controlling the combustion process is known, consisting of a temperature sensor, an indicator of the accuracy of the process, and a regulator controlling the supply of the oxidizing agent to the combustion zone [2].

Also known is a system for automatically controlling the thermal mode of a heating furnace, consisting of an adjustable parameter sensor connected to the first adder, a fuel regulator, fuel and air flow sensors connected to the inputs of the second adder, the output of which is connected to an air regulator and a correction device [3 ].

However, the known devices do not provide the maintenance of the combustion process 30 at a predetermined level, since not only the air entering through the pipeline but also the air entering the working space from the atmosphere due to suction through leaks of the furnace body, loading and unloading windows is involved in the combustion. time of relevant operations. The quality also depends on the heating temperature in the recuperators of the combustion air, air humidity, the order in which workpieces are placed in the workspace, changes in the calorific value of fuel, etc.

During the heating of the metal, significant (20-50% or more) air leaks through the leak of the heat exchanger are possible. Moreover, leaks can be inconsistent, random in nature. Under these conditions, unsatisfactory combustion of the fuel will be observed, which leads to a decrease in the thermal power of the furnace and excessive consumption of fuel.

The purpose of the invention is to increase the efficiency of the furnace.

To achieve this, a furnace process sensor is introduced into a system containing a sensor of an adjustable parameter, for example, a temperature connected to the first adder, a fuel regulator, fuel and air flow sensors connected to the inputs of the second adder, the output of which is connected to the air regulator, and a correction device connected to the correction device, the first output of which is connected to the second input of the air regulator, and the second output Through the limit switch of the actuator of the air supply with rvym input fuel regulator, the second '' input connected to the output of the first adder. The limit switch is closed in the extreme open position of the actuator air supply.

The drawing shows the proposed * 5 proposed system for automatically controlling the thermal regime of a heating furnace.

The system contains an adjustable parameter sensor, for example, a thermocouple 1, a temperature setter 2, a first adder 3, a fuel regulator 4, an actuator 5 of a fuel supply control valve 6, fuel and air flow sensors 7 and 8, a second adder 9, a ratio adjuster 10, a regulator 11 air, actuator 12 of the control valve 13 air supply, limit switch 14¼ sensor 15 of the firing process, correction device 16, the regulator 17 of the firing process mode.

In the case of steady state, the signals of the thermocouple 1 and the temperature setpoint 2 are equal. At the output of totalizer 3, the signal is zero. Accordingly, at the output of the fuel regulator 4, the signal is also equal to zero, and the actuator 5 is in a certain position, providing a constant 4Q fuel consumption.

The sum of the signals of the sensors 7 and 8 of the fuel and air consumption at the output of the adder 9 corresponds to the value · of the setpoint ratio 10 and at the output of the air regulator 11, the signal is zero. The actuator 12 is stationary, providing a constant flow of air.

The signal of the sensor 15 of the firing process corresponds to the value of the signal of the setter 17. At the outputs of the correction device 16, the signal is zero.

If, under the influence of external disturbances, the furnace process has changed, the signal of the sensor 15 will not correspond to the value of the signal of the setter 17 and the signal appears at the outputs of the correction device 16;

If the combustion air 60 is sufficient to compensate for the disturbance, the air supply control valve 13 is not fully open, and the limit switch 14 of its actuator 12 is open. 65

The correction signal is supplied to the second input of the air regulator 11, at the output of which a control signal appears, under the influence of which the actuator 12 rotates the control valve 13, changing the air flow. When the disturbance is compensated, the output of the correction device 16, the signal becomes equal to zero.

If the air losses in the recuperator are so large that with a fully open control valve 13 the incoming air is not enough to stabilize the combustion process, the correction signal is fed to the air regulator and through the closed limit switch 14 to the first input of the fuel regulator 4, at the output of which a signal appears the action of which the actuator 5 rotates the control valve 6, reducing fuel consumption to stabilize the combustion process.

The use of correction for the flow of the combustion process distinguishes the proposed system of automatic regulation of the thermal regime of the heating furnace from the specified prototype, since it has the ability to compensate for disturbances arising in the process of fuel combustion. by 1% and fuel consumption will decrease by 5%.

Claims (3)

1. US patent 3861855, cl. F 23 p 5/08, 1966. 2. Authors certificate of the USSR 409057 cl. F 23 p 5/00, .1970. 3. USSR author's certificate I 446718 cl. F 23 p 5/00, 1972 (prototype). -15 g