JP2007044615A - Method for operating electrostatic precipitator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for operating an electrostatic precipitator which can efficiently operate a thyristor cooling fan so as to radiate heat generated from a thyristor element in a control panel of the elecrostatic precipitator. <P>SOLUTION: The start and stop of the thyristor cooling fan 23 are respectively linked with the start and stop of an electric charging device charging to the discharge electrode 21 of the electrostatic precipitator 12. By this operating method, the thyristor cooling fan 23 can be stopped when heat is not generated from the thyristor element 20 due to the stop of the electric charging device. Thus, wear of bearings for the motor of the thyristor cooling fan 23 is reduced, a periodical exchange cycle of the thyristor cooling fan 23 is lengthened, and the cost of maintenance is reduced. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for operating an electrostatic precipitator that efficiently operates a thyristor cooling fan in order to dissipate heat generated from a thyristor element in a control panel of the electrostatic precipitator.

  In conventional thermal power plants and waste incinerators, the electrostatic precipitator is installed in the immediate vicinity of downstream equipment such as boilers and incinerators, and the control panel is installed in the electrical room of the facility where the precipitator is installed. . In a charging device for an electrostatic precipitator, a main circuit switch, a thyristor element, a current transformer, and a control device are provided on a control panel, and a high-voltage transformer / rectifier is provided near the electrostatic precipitator. And as operation | movement of a charging device, a low voltage commercial power supply is supplied to a high voltage transformer rectifier via a main circuit switch and a thyristor element, is boosted from a low voltage to an extra high voltage, and then converted to a DC extra high voltage. The DC extra high voltage is supplied to the electrostatic precipitator via the DC reactor, the supply electric circuit, the far electric section switch and the high voltage current detector (for example, refer to Patent Document 1).

In a conventional pulse power supply device for an electrostatic precipitator, a high-voltage pulse is generated by a DC high-voltage power supply, a choke coil, a capacitor, a thyristor element that is a switching element, an inductance, and a transformer. The high-voltage pulse is converted into a DC high-voltage power source through a rectifier on the secondary side of the transformer and charged in the electric dust collector. Note that a diode is connected in antiparallel to the thyristor element, and is conductively protected when the polarity of the voltage applied to the thyristor element is reversed by a resonance action (see, for example, Patent Document 2).
JP 7-39784 A (page 3-4, FIG. 1) Japanese Patent Laid-Open No. 10-76182 (page 2-3, FIG. 1)

  As described above, in a thermal power plant, a garbage incineration plant, and the like, an electric dust collector is used to burn fuel and dust and remove dust from generated smoke. In order to operate the electric dust collector, a high voltage is applied between the discharge electrode and the dust collecting electrode. At this time, in the charging device of the electrostatic precipitator, the AC voltage from the low-voltage commercial power supply is adjusted through the main circuit switch and the thyristor element, and supplied to the high-voltage transformer rectifier. In this conversion operation, heat is generated from the thyristor element, and the thyristor element in the control panel becomes high temperature. Therefore, a thyristor cooling fan is disposed in the vicinity of the thyristor element to radiate heat generated from the thyristor element.

  However, in a conventional charging device for an electrostatic precipitator, the thyristor cooling fan is always in operation, and is not interlocked with the start and stop of the thyristor element in the charging device. For example, when a thermal power plant is stopped for a long period such as a weekend stop, the thyristor element is stopped, but only the thyristor cooling fan is operating. For this reason, there is a problem that the motor bearing of the thyristor cooling fan is worn more than necessary, resulting in maintenance costs such as replacement work and power costs.

  In the operation method of the electrostatic precipitator of the present invention, the electric dust collector is started and stopped by charging from a charging device that transforms and rectifies an AC voltage from a power source. In the operation method of the dust collector, the thyristor cooling fan that is disposed in the vicinity of the thyristor element that adjusts the AC voltage and cools the thyristor element is activated in conjunction with an activation signal of the charging device. To do. Therefore, in the present invention, the thyristor cooling fan is efficiently started, thereby extending the life of the thyristor cooling fan and reducing the maintenance cost.

  Moreover, in the operation method of the electric dust collector of the present invention, the activation signal of the charging device is a signal transmitted by remote automatic operation from a distance or a signal transmitted by automatic operation directly in the electric dust collector electric room. It is characterized by being. Therefore, in the present invention, the thyristor cooling fan is efficiently activated even when the charging device is activated by remote automatic operation or directly by automatic operation.

  In the electric dust collector operation method of the present invention, the thyristor cooling fan is stopped in conjunction with a stop signal of the charging device during operation. Therefore, in the present invention, the extra operation of the thyristor cooling fan is reduced by stopping the thyristor cooling fan in conjunction with the stopping of the charging device. And the maintenance cost of the thyristor cooling fan is reduced.

  In the electric dust collector operation method of the present invention, the thyristor cooling fan receives the stop signal and stops after a lapse of a desired time. Therefore, in the present invention, after the charging device is stopped, the thyristor cooling fan is operated for a certain period of time, thereby preventing thermal destruction of the thyristor element.

  Further, in the operation method of the electric dust collector of the present invention, the charging device stop signal is a signal transmitted by remote automatic operation from a distance, a signal transmitted by automatic operation at the time of emergency stop of the charging device, or It is a signal transmitted by an automatic operation directly in an electric dust collector electrical room. Therefore, in the present invention, when the charging device is stopped by remote automatic operation, when the charging device is urgently stopped due to a failure or the like, or when it is directly operated by automatic operation, the thyristor cooling fan is stopped. Linked to the stop.

  In the present invention, the thyristor cooling fan operates efficiently in conjunction with the start and stop of the charging device that charges the electrostatic precipitator. For example, when the thermal power plant is stopped for a long period such as a weekend stoppage, the excessive operation of the thyristor cooling fan is reduced. This operating method extends the life of the thyristor cooling fan and reduces maintenance costs.

  In the present invention, the thyristor cooling fan is efficiently started in conjunction with a start signal and a stop signal for the charging device by remote automatic operation or a start signal and a stop signal for the charging device by direct automatic operation. With this operation method, the activation of the thyristor cooling fan is reliably linked to the activation of the charging device.

  In the present invention, the charging device is stopped and the thyristor cooling fan is stopped after a predetermined time has elapsed. With this operation method, the thyristor element that has become high temperature with the operation of the charging device is cooled for a certain period of time, thereby preventing thermal destruction of the thyristor element.

  Further, in the present invention, when the charging device is stopped urgently due to a failure of the charging device, the thyristor cooling fan is also stopped. With this operation method, the thyristor cooling fan can be stopped even in the event of an emergency stop of the charging device. Further, it is possible to extend the life of the thyristor cooling fan and reduce maintenance costs.

  Below, the operation method of the electrostatic precipitator which is one embodiment of this invention is demonstrated in detail with reference to FIGS. 1-4 with a thermal power plant as an example. FIG. 1 is a schematic diagram of a thermal power plant in the present embodiment. FIG. 2 is a schematic diagram for explaining an arrangement state of the electrostatic precipitator according to the present embodiment as viewed from above. FIG. 3 is a schematic diagram for explaining an arrangement state of the electrostatic precipitator and the charging device in the present embodiment. FIG. 4 is a flowchart for explaining a control circuit for instructing start and stop of the thyristor cooling fan in the present embodiment.

  As shown in FIG. 1, the thermal power plant 1 of the present embodiment mainly includes a turbine 2, a generator 3, a condenser 4, a condensate pump 5, a deaerator 6, a boiler feed pump 7, a boiler 8, It comprises a denitration device 9, an air preheater 10, a forced air blower 11, an electric dust collector 12, and a chimney 13.

  The turbine 2 is a steam turbine. Deaerated water (pure water) circulates in a circulation pipe that is piped in the boiler 8, and high-temperature and high-pressure superheated steam is generated. The high-temperature and high-pressure superheated steam flows into the turbine 2 via the pipe indicated by the alternate long and short dash line. In the turbine 2, the high-temperature and high-pressure superheated steam expands into low-temperature and low-pressure steam, so that the turbine 2 is rotationally driven. Then, the thermal energy of the steam is converted into mechanical energy (rotational energy).

  The generator 3 is configured to be connected to the turbine 2. The generator 3 includes a rotor and a stator. The rotor is composed of a rotating shaft and a rotor coil (field winding), and the stator is composed of a stator core and a stator coil. The rotating shaft of the turbine 2 and the rotating shaft of the rotor of the generator 3 are coaxially connected. With this structure, the generator 3 is driven by the mechanical energy obtained by the turbine 2, and the generator 3 generates electricity. That is, mechanical energy is converted into electric energy by the generator 3.

  The condenser 4 is connected to the turbine 2 and cools the exhaust steam from the turbine 2 with cooling water to create condensed condensate. As the condenser 4, an injection-type condenser that directly injects cooling water into exhaust steam and produces condensed condensate by direct contact heat exchange, and condensate condensate by cooling the exhaust steam with cooling water through a cooling pipe. There is a surface-cooled condenser to make. For example, in a surface-cooled condenser, an aluminum brass tube or a titanium tube having excellent corrosion resistance is used as a cooling tube. Moreover, in the condenser 4, in order to improve the thermal efficiency of the turbine 2, the exhaust pressure is kept low, that is, kept in a high vacuum state.

  The condensate pump 5 draws the condensate from the condensate pool of the condenser 4 and sends it out to the piping indicated by the two-dot chain line. And since the condensate pumped out from the condensate pump is used as boiler feed water, it is sent to the deaerator 6.

  The deaerator 6 includes, for example, an upper deaeration chamber and a lower deaeration tank. A deaeration chamber is a site | part which removes the dissolved gas dissolved in condensate or feed water. The deaeration tank is a tank for storing deaerated water deaerated in the deaeration chamber.

  The boiler feed pump 7 raises the pressure of the deaerated water deaerated by the deaerator 6 and feeds the deaerated water to the boiler 8 via a pipe indicated by a two-dot chain line.

  The boiler 8 is a once-through boiler, for example, and includes a furnace, an evaporator, a superheater, a reheater, and the like. In the furnace, the chemical heat of the fuel is returned to heat by combustion. And the flue gas (combustion gas) that exits the furnace transfers heat to the superheater and reheater provided at the rear of the furnace to produce superheated steam. In the superheater, saturated steam generated in the evaporator of the furnace is converted into superheated steam, and the superheated steam flows into the turbine 2. In the reheater, the steam that has worked in the turbine 2 and is in a state close to wet steam is converted into superheated steam again, and the superheated steam flows into the turbine 2.

  The denitration device 9 sprays ammonia to the flue gas and decomposes harmful nitrogen oxides contained in the flue gas into harmless nitrogen and water by the action of the catalyst.

  The air preheater 10 heats air necessary for burning fuel in the boiler 8 by heat exchange with flue gas. The heat efficiency of the boiler plant can be increased by collecting the waste heat of the flue gas that has undergone heat exchange with a superheater, reheater, etc., in the combustion air.

  The forced air blower 11 supplies combustion air into the furnace with the forced air flow of the forced fan, and improves the combustion efficiency in the boiler 8 while maintaining the furnace pressure at atmospheric pressure or higher.

  The electric dust collector 12 includes a discharge electrode, a dust collecting electrode, a charging device, and the like. The discharge electrode is a cathode of the electrostatic precipitator 12 for generating corona discharge. The discharge electrode is composed of, for example, a plate having a wire or a protrusion. The dust collecting electrode is an anode of the electric dust collector 12 for collecting dust facing the discharge electrode. As the dust collecting electrode, for example, a flat electrode is used in order to uniformly collect dust charged to a negative polarity by corona discharge in a wide area. The charging device applies a high voltage for corona discharge or dust collection electric field formation between the discharge electrode and the dust collection electrode.

  The chimney 13 secures ventilation and diffuses smoke efficiently. In addition, the continuous line which shows the flow of the flue gas from the boiler 8 to the chimney 13 is a flue.

  As shown in FIG. 2, for example, two electrostatic precipitators 12 are paired in the flue 14 to block the flue gas flow path, and a total of four are installed. An inlet 15 of each electrostatic precipitator 12 is arranged in the flue 14 on the furnace side, and the exhaust gas flows into the electrostatic precipitator 12 from the inlet 15. As described above, the dust in the flue gas is collected on the dust collecting electrode using the discharge electrode and the dust collecting electrode of the electric dust collector 12. And the flue gas which became clean gas flows out into the flue 14 from the exit 16 of the electrostatic precipitator 12 arrange | positioned at the chimney 13 side.

  As shown in FIG. 3, the charging device that charges the electrostatic precipitator 12 mainly includes a high-voltage transformer rectifier 17, a high-voltage ground switch board 18, a high-voltage bus duct 19, and a thyristor element 20.

  The high-voltage transformer rectifier 17 converts an AC voltage from a low-voltage commercial power source (hereinafter referred to as a power source) to a DC high voltage (rated value) that is charged between the discharge electrode 21 and the dust collecting electrode 22 in the electric dust collector 12. It is a device that rectifies and transforms.

  The high-voltage ground switch board 18 is installed between the high-voltage transformer rectifier 17 and the discharge electrode 21. When the discharge electrode 21 is inspected or an abnormality occurs in the high-voltage grounding switchboard 18, the normal charging path (from the high-voltage transformer rectifier 17 to the discharge electrode 21) is inspected / abnormal path (grounding). A switch for switching from the discharge electrode 21) to the discharge electrode 21) is provided.

  The high-voltage bus duct 19 has a bus line enclosed by a power supply surrounded by a duct, and a DC high voltage (rated value) obtained by converting an AC voltage from the power supply is transmitted to the bus line. As shown in the figure, when a single electrostatic precipitator 12 is used alone, the high-voltage grounding switchboards 18 arranged in the front and rear are connected by a high-pressure bus duct 19 with respect to the traveling direction of the smoke. . As shown in FIG. 2, when two electrostatic precipitators 12 are used in a pair, the space between the front row and rear row high-voltage grounding switchboards 18 with respect to the direction of smoke movement is used. The case where it connects with the high voltage bus duct 19 may be sufficient.

  The thyristor element 20 rectifies the AC voltage from the power source by starting at a desired phase when transmitting the AC voltage from the power source to the high voltage transformer rectifier 17. Due to this rectifying operation, heat is generated from the thyristor element 20, and the thyristor element 20 itself becomes high temperature. Therefore, a thyristor cooling fan 23 is installed in the vicinity of the thyristor element 20 to radiate heat generated from the thyristor element 20.

  The thyristor cooling fan 23 is provided with a control circuit 24 that controls the start and stop of the thyristor cooling fan 23. The start and stop of the thyristor cooling fan 23 is controlled by the control circuit 24 and can be started and stopped in accordance with the operating state of the thyristor element 20.

  As shown in FIG. 4, the thyristor cooling fan 23 is started and stopped by remote automatic operation in a thermal power plant central control room (hereinafter referred to as a central control room) or direct automatic operation in an electric dust collector electric room. Can be performed. The symbol □ shown in the figure is an AND circuit, the symbol ◯ is an OR circuit, and the symbol with × in □ is a NOT circuit.

  First, step 1 to step 4 will be described. In the case of remote control from the central control room, when the operator presses a button for selecting the central control room as the operation place (step 1), a signal A is generated. Further, when a charge start signal is issued from the central control room automation device to the electrostatic precipitator 12 (step 2), a signal A is emitted. In the AND circuit 31, when the signal A is generated from both steps, the signal A is generated.

  On the other hand, in the case of direct automatic operation in the electric dust collector electric chamber, when the operator presses a button for selecting the electric dust collector electric chamber as the operation place (step 3), a signal A is generated. When the operator depresses the charge start button for the electrostatic precipitator 12 directly in the electric precipitator electric chamber (step 4), a signal A is generated. The AND circuit 32 generates the signal A when the signal A is generated from both steps.

  In the OR circuit 33, when the AND circuit 31 or the AND circuit 32 generates the signal A in step 1 and step 2, the signal A is generated.

  Next, step 5 to step 9 will be described. When the operator turns on the breaker of the main power supply circuit of the charging device that charges the electrostatic precipitator 12 (step 5), a signal A is emitted.

  When the voltage drops below the low voltage set during charging of the electrostatic precipitator 12 (step 6), the NOT circuit 34 issues a signal B.

  Further, when various abnormalities occur in the charging device during charging of the electrostatic precipitator 12 (step 7), a signal B is emitted from the NOT circuit 35.

  Further, when the operator depresses the charge stop button for the electrostatic precipitator 12 directly in the electrostatic precipitator electric chamber during charging of the electrostatic precipitator 12 (step 8), a signal B is emitted. .

  Further, when a charge stop signal is issued from the central control room automation device to the electric dust collector 12 during charging of the electric dust collector 12 (step 9), a signal B is emitted.

  The AND circuit 38 generates the signal A when all the signals A are generated from step 5 to step 9.

  Finally, in the AND circuit 39, when the OR circuit 33 and the AND circuit 38 generate the signal A in steps 1 to 9, the signal A is generated. In this case, the control circuit 24 activates the thyristor cooling fan 23 (step 10).

  On the other hand, in the AND circuit 39, when the OR circuit 33 or the AND circuit 38 generates the signal B, the signal B is generated. In this case, a signal A is issued from the NOT circuit 40, and the control circuit 24 stops the thyristor cooling fan 23 after a predetermined time has passed through the timer circuit 41 (step 11).

  As described above, when the charging device is activated by remote control of the central control room automation device, the thyristor cooling fan 23 is activated. On the other hand, when the charging device is stopped by remote control of the central control room automation device, the thyristor cooling fan 23 is stopped after a predetermined time has elapsed. The same applies to direct automatic operation in the electric dust collector electric room.

  In the present embodiment, the start and stop of the thyristor cooling fan 23 is interlocked with the start and stop of the charging device that charges the electrostatic precipitator 12. With this operation method, the thyristor cooling fan 23 can be operated in accordance with the timing at which heat is generated from the thyristor element 20. For example, when the thermal power plant 1 is stopped for a long period such as a weekend stoppage, no smoke is generated and the electric dust collector 12 is also stopped. In this case, there is no problem even if the thyristor cooling fan 23 is stopped without generating heat from the thyristor element 20 due to the stopping of the charging device.

  That is, when the thyristor cooling fan 23 operates efficiently, the wear amount of the motor bearing of the thyristor cooling fan 23 can be significantly reduced. As a result, the replacement cycle of the thyristor cooling fan 23 is extended by, for example, about three times the conventional replacement cycle. Further, maintenance costs such as replacement of parts in the thyristor cooling fan 23 can be reduced. Moreover, the power cost of the thermal power plant 1 can also be reduced.

  Further, in the present embodiment, when the charging device fails and an emergency stop occurs, such as when the voltage from the charging device drops below a set value while the charging device is in operation, the thyristor cooling fan 23 is operated for a certain period of time. Stop later. As a result, when the charging device fails, the thyristor cooling fan 23 is also stopped in conjunction with it, so that excessive operation of the thyristor cooling fan 23 can be reduced.

  In the present embodiment, when the charging device is stopped from the operating state in step 6 to step 9, the timer circuit 41 stops the thyristor cooling fan 23 after a predetermined time has elapsed. With this operation method, the thyristor cooling fan 23 stops after the heat of the thyristor element 20 itself has been reduced to some extent. And even when the thyristor cooling fan 23 stops in conjunction with the stopping of the charging device, the thyristor element 20 can be prevented from being destroyed by heat.

  In the present embodiment, the operation method of the electrostatic precipitator has been described using a thermal power plant. However, the present invention is not limited to this case. For example, a similar effect can be obtained when an electrostatic precipitator and a thyristor cooling fan are disposed in an industrial waste incineration facility, a factory or a building duct. In addition, various modifications can be made without departing from the scope of the present invention.

It is the schematic for demonstrating the thermal power plant in embodiment of this invention. It is the schematic for demonstrating the arrangement | positioning condition which looked at the electrostatic precipitator in embodiment of this invention from the upper surface. It is the schematic for demonstrating the arrangement | positioning condition of the electrostatic precipitator and charging device in embodiment of this invention. It is a flowchart for demonstrating the control circuit which instruct | indicates starting and a stop of the thyristor cooling fan in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Thermal power plant 2 Turbine 3 Generator 4 Condenser 5 Condensate pump 6 Deaerator 7 Water supply pump 8 Boiler 9 Denitration device 10 Air preheater 11 Pushing fan 12 Electric dust collector 13 Chimney 17 High voltage transformer rectifier 18 High pressure Ground switch board 19 Extra high bus duct 20 Thyristor element 21 Discharge electrode 22 Dust collecting electrode 23 Thyristor cooling fan 24 Control circuit

Claims (5)

In the operation method of the electrostatic precipitator that starts and stops by charging from the charging device that transforms and rectifies the AC voltage from the power source,
A method of operating an electrostatic precipitator, characterized in that a thyristor cooling fan that is disposed in the vicinity of the thyristor element that adjusts the AC voltage and that cools the thyristor element is activated in conjunction with an activation signal of the charging device. . 2. The electric device according to claim 1, wherein the activation signal of the charging device is a signal transmitted by remote automatic operation from a distance or a signal transmitted by automatic operation directly in an electric dust collector electric room. How to operate the dust collector. The operation method of the electrostatic precipitator according to claim 1, wherein the thyristor cooling fan is stopped in conjunction with a stop signal of the charging device during operation. The method of claim 3, wherein the thyristor cooling fan receives the stop signal and stops after a lapse of a desired time. The charging device stop signal is a signal transmitted by remote automatic operation from a distance, a signal transmitted by automatic operation at the time of emergency stop of the charging device, or a direct automatic operation in the electric dust collector electrical room. It is a signal, The operating method of the electrostatic precipitator of Claim 3 or Claim 4 characterized by the above-mentioned.

Images