JPH05329399A - Electric charge control device of electric dust collector - Google Patents

Abstract

PURPOSE:To ensure that an operating output is automatically changed and an optimal dust collection efficiency is constantly obtained in response to a change in flue dust by providing a hunting detection circuit and a voltage control logic circuit, and enabling an operation to be stable at the highest applied voltage below the level where a hunting phenomenon generates. CONSTITUTION:This electric charge control device consists of a hunting detection circuit 1 detecting a hunting phenomenon with two different types of detection circuits 6, 7 and capable of selecting an optimal circuit in accordance with the status of a plant based on parameters, and a voltage control circuit 2 which generates an adjustment signal for outputting to an operating output 10d based on the parameters which are previously set by a signal obtained from the hunting detection circuit 1. A constant operating output is boosted until the hunting phenomenon is detected, and if a change in the adhesive state of flue smoke is detected, the constant operating output is lowered from a point of time when the hunting phenomenon is detected. Thus, it is possible to ensure a stable electric charge to an electric dust collector under the supply of the highest voltage below the level of occurrence of the hunting phenomenon, and control the dust collection to the highest efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge control device for an electrostatic precipitator, which removes dust and the like from flue gas generated in plant processes of general industries.

[0002]

2. Description of the Related Art Conventionally, charge control of a power supply device for an electrostatic precipitator has been performed by manually operating the voltage obtained by a voltage detector through a voltage input unit and the voltage to be applied by a target setting device in advance. To set the target load voltage value,
The PID adjustment calculation is executed using the D control parameter, the obtained adjustment signal is compared with the output feedback value of the power supply device by the comparison circuit, and the power supply device is loaded via the operation output unit to match the target value. A configuration for controlling the above is widely adopted.

At this time, it is necessary to change the voltage to be applied depending on the state of the exhaust gas, the state of dust, and the state of adhesion of the electrode dust, and it is always necessary to manually set the target value.

[0004]

By the way, in the above charge control, since the target value changes depending on the state of the exhaust gas, the state of dust, and the state of adhesion of the electrode dust, the response of the process to the control system naturally changes. Come on. Moreover, since the adhered state is reduced, arc discharge is generated between the discharge electrode and the dust collecting electrode. This results in a hunting phenomenon that enters the printed voltage input section, disturbs the PID adjustment calculation, affects the operation output, and causes the power supply device to repeatedly transmit and cut power, which causes the hunting phenomenon to further increase and the efficiency of electrostatic collection to deteriorate. is there.

The present invention has been made in view of the above circumstances, and a charge control device for an electrostatic precipitator that automatically changes the operation output and always achieves optimum dust collection efficiency in accordance with changes in dust and the like of exhaust smoke. The purpose is to provide.

[0006]

According to the present invention, a voltage detector for measuring an applied voltage applied between a discharge electrode and a collector electrode of an electrostatic precipitator and a rate of change of the applied voltage with time are calculated. The first hunting detection circuit that considers hunting when the abnormal change rate exceeding the predetermined change rate set value continues for a predetermined time set value or more, and the maximum applied voltage measured at each predetermined sampling time. A second hunting detection circuit that considers hunting when the difference between the value and the minimum value exceeds a predetermined set difference voltage, and an output circuit of the first hunting detection circuit and an output circuit of the second hunting detection circuit. Selective parameter circuit to switch between and use, the operation output unit to operate the output voltage control of the power supply device that supplies the applied voltage up and down stepwise at predetermined time intervals, and the up and down operation with the power supply device. When a hunting signal is received from the operation output feedback input section that inputs the feedback value of the operation output and the hunting signal from the selection parameter circuit, the feedback value from the operation output feedback input section is compared with the applied voltage to control the output voltage of the power supply device. And a first voltage control logic circuit that outputs a lowering operation signal that gradually lowers each of the predetermined time and a feedback value from the operation output feedback input unit when the hunting signal is not received from the selection parameter circuit. A second voltage control logic circuit that compares the applied voltage and outputs a raising operation signal that raises the output voltage control of the power supply device stepwise at predetermined times, and applies the highest voltage below the occurrence of a hunting phenomenon. This is a charge control device for an electrostatic precipitator that enables stable operation with voltage.

[0007]

In the charging control device for the electrostatic precipitator according to the present invention, the applied voltage applied between the discharge electrode and the collecting electrode of the electrostatic precipitator is measured, the rate of change of the applied voltage with time is calculated, and the predetermined value is determined in advance. If the abnormal rate of change that exceeds the change rate set value continues for a predetermined time set value or more, it is considered as hunting, and the difference between the maximum value and the minimum value of the applied voltage measured at each predetermined sampling time is set in advance. If the set differential voltage is exceeded, it is regarded as hunting, and the output circuit of the first hunting detection circuit and the output circuit of the second hunting detection circuit are switched and used to control the output voltage of the power supply device that supplies the applied voltage. When the hunting signal is received from the selected parameter circuit by inputting the feedback value of the operation output that was operated up and down by the power supply device The feedback value from the operation output feedback input section is compared with the applied voltage, and the lowering operation signal for gradually lowering the output voltage control of the power supply device at every predetermined time is output, and the hunting signal is received from the selection parameter circuit. If not, compare the feedback value from the operation output feedback input section with the applied voltage,
A raising operation signal for gradually increasing the output voltage control of the power supply device at predetermined time intervals is output to enable stable operation at the highest applied voltage below the occurrence of the hunting phenomenon.

[0008]

EXAMPLE An example of the present invention will be described below. In FIG. 1, 5 is a voltage detector that measures an applied voltage V applied between the discharge electrode K and the collector electrode P of the electrostatic precipitator 3, and 6 is a rate of change of the applied voltage V with time, which is calculated in advance. A hunting detection circuit that considers hunting when an abnormal change rate exceeding a predetermined change rate set value continues for a predetermined time set value or more, and 7 is a maximum value of an applied voltage V measured at each predetermined sampling time. A hunting detection circuit that considers hunting when the difference between the minimum values exceeds a predetermined set difference voltage, and 8 is a selection parameter circuit that is used by switching between the output circuit of the hunting detection circuit 6 and the output circuit of the hunting detection circuit 7. Reference numeral 10d is an operation output unit for operating the output voltage control of the power supply device 9 for supplying the applied voltage V stepwise up and down at predetermined time intervals, and 10c is an operation output operated up and down by the power supply device 9. When the operation output feedback input unit 10a for inputting the feedback value receives the hunting signal from the selection parameter circuit 8, the operation output feedback input unit 10c compares the feedback value from the operation output feedback input unit 10c with the applied voltage V and outputs the output of the power supply device 9. When the voltage control logic circuit 10b that outputs a lowering operation signal for gradually lowering the voltage control at predetermined time intervals does not receive a hunting signal from the selection parameter circuit 8, a feedback from the operation output feedback input unit 10c. Value and applied voltage V
Is a voltage control logic circuit that outputs a raising operation signal for gradually increasing the output voltage control of the power supply device at predetermined time intervals, and in the charge control of the electrostatic precipitator 3,
When the applied voltage between the discharge electrode K and the dust collecting electrode P of the smoke exhaust equipment is too high, when the power supply device for the charge control device repeats power transmission / interruption due to the occurrence of arc discharge, the hunting phenomenon of this repetitive operation is caused. A charge control device for an electrostatic precipitator, which is equipped with two types of detection circuits for detection and a voltage control circuit for changing a manipulated variable by a certain amount depending on the presence or absence of a hunting phenomenon.

That is, paying attention to the occurrence of a hunting phenomenon in the charge control for an electric dust collector that collects dust from flue gas, the hunting phenomenon is detected by two types of detection circuits, and the parameters for calculation are used according to the situation of the plant. A hunting detection circuit that can select an optimum circuit, and a signal obtained from this hunting detection circuit, a configuration including a voltage control circuit that obtains an adjustment signal for outputting to an operation output with a preset control parameter, When the attached state of smoke emission changes, the operation output is increased by a certain amount until the hunting phenomenon is detected, and the operation output is reduced by a certain amount from the time when the hunting phenomenon is detected. On the other hand, it is possible to secure stable charging of the electrostatic precipitator and control the dust collection with high efficiency.

Details of the voltage control circuit will be described with reference to FIG. When the hunting phenomenon is detected in the voltage V input from the voltage input unit, the target value SV is lowered by a fixed amount X (set by a parameter) and the operation output MV is gradually lowered to lower the load voltage and to re-establish the hunting phenomenon. Detection is performed, and the operation output MV is gradually reduced until the hunting phenomenon is not detected for a certain period of time t1. If the predetermined time t1 is not detected, the target voltage SV is increased by a constant amount Y (set by a parameter) to gradually increase the operation output MV to increase the load voltage, and the highest voltage is applied when the hunting phenomenon occurs or less. It is a voltage control circuit that can.

In the conventional method, the applied voltage from the electrostatic precipitator is detected by the voltage detector, read through the voltage input section, and based on the deviation from the target value set by the manual operation, the PID adjustment calculation is performed. Although the charge control method is one in which the calculated value and the current value read from the operation output feedback input section are compared and used as the operation output from the operation output section, the point different from the conventional example of the present invention is that the PID That is, it has the functions of the hunting detection circuits A and B and the voltage control circuit 2 without using the adjustment calculation method.

Next, the operation of the apparatus configured as described above will be described. The voltage detector 5 detects the applied voltage V applied from the electrostatic precipitator 3, and the hunting detection circuit detects the presence or absence of hunting according to preset parameters. There are two hunting detection circuits. The hunting detection circuit 6 compares the rate of change of the voltage with a set parameter, detects a change larger than the set value, and considers this as hunting when the change rate abnormality continues for a set time or longer. Is. The hunting detection circuit 7 is a circuit that detects the maximum value and the minimum value of the voltage sampled during the set time, and if the difference exceeds the set value, it is considered as hunting. In either case, the hunting level of the voltage to be detected can be set by setting the parameter. Further, the detection circuit is switched and used by the selection parameter circuit 8 according to the occurrence of hunting.

In the voltage control circuit 10, when the hunting detection circuits 6 and 7 detect hunting, the operation output feedback value VP from the power supply device 9 is compared with the current load voltage, and the operation output MV is kept constant. The X lowering hunting phenomenon is gradually lowered until the set time t1 is no longer detected. Further, when the set time t1 hunting is not detected, the operation output MV is increased by a constant amount Y, so that stable charging can be secured by the highest voltage below the occurrence of the hunting phenomenon and high efficiency control of dust collection can be performed.

FIG. 3 is a detailed diagram of the hunting detection circuit, and FIG. 4 is a detailed explanatory diagram of the voltage control circuit.

[0015]

As described above, according to the present invention, optimal control response can be obtained even if the state of adherence of dust or the like in the flue gas changes, and consequently the highly efficient operating state of dust collection can be maintained. You can

[Brief description of drawings]

FIG. 1 is a configuration diagram of a charge control device showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an operation effect of FIG.

FIG. 3 is a diagram illustrating a configuration of a hunting detection circuit.

FIG. 4 is a diagram illustrating a configuration of a voltage control circuit.

[Explanation of symbols]

 6, 7 Hunting detection circuit 8 Selection parameter circuit 10 Voltage control logic circuit 10c Operation output feedback input section 10d Operation output section

Claims (1)

[Claims] 1. A voltage detector for measuring an applied voltage applied between a discharge electrode and a collector electrode of an electrostatic precipitator, and a rate of change of the applied voltage over time is calculated, and a predetermined rate of change rate setting value is set. The first hunting detection circuit that considers hunting when the abnormal change rate that exceeds the predetermined time continues for a predetermined time or more, and the difference between the maximum value and the minimum value of the applied voltage measured at each predetermined sampling time. Selection that switches between the second hunting detection circuit, which considers it as hunting when the voltage exceeds a predetermined set difference voltage, and the output circuit of the first hunting detection circuit and the output circuit of the second hunting detection circuit. A parameter circuit, an operation output section for operating the output voltage control of the power supply device for supplying the applied voltage up and down stepwise at predetermined time intervals, and an operation output operated up and down by the power supply device. When a hunting signal is received from the operation output feedback input section for inputting the feedback value of the selection parameter circuit, the feedback value from the operation output feedback input section is compared with the applied voltage, and the output of the power supply device is output. A first voltage control logic circuit that outputs a lowering operation signal that gradually lowers the voltage control at predetermined time intervals, and from the operation output feedback input unit when a hunting signal is not received from the selection parameter circuit. And a second voltage control logic circuit for comparing the feedback value of the power supply device with the applied voltage and outputting a raising operation signal for stepwise raising the output voltage control of the power supply device at a predetermined time. A charge control device for an electrostatic precipitator that enables stable operation at the highest applied voltage below the generation level.