JP2013188705A - Dilution water amount control apparatus and dilution water amount control method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dilution water amount control apparatus and a dilution water amount control method, capable of deciding a dilution water amount of desulfurized filtrate simply and accurately.SOLUTION: A dilution water amount control apparatus 223 includes: a boron concentration-measuring sensor 224 that intermittently measures the boron concentration of boron contained in desulfurized filtrate of a desulfurization apparatus; an input section 225 that accepts an input of boron concentration; and a controller 227 that calculates the difference between the boron concentration measured by the boron concentration-measuring sensor 224 and the boron concentration accepted by the input section 225, corrects the boron concentration measured by the boron concentration-measuring sensor 224 based on the calculated difference, and decides the dilution amount of the desulfurized filtrate based on the corrected boron concentration.

Description

  The present invention relates to a dilution water amount management apparatus and a dilution water amount management method.

  As a method for burning coal in a coal-fired power generation system, there is a pulverized coal combustion method in which particles obtained by finely pulverizing coal are blown into a combustion furnace and burned.

  By the way, coal contains a trace amount of harmful elements such as sulfur compounds, nitrogen compounds, and boron in addition to carbon (hereinafter, the harmful elements are referred to as “toxic trace elements”). For this reason, when pulverized coal is burned with the combustion boiler provided in the coal thermal power generation system, sulfur oxide is generated from the sulfur compound contained in the pulverized coal. Therefore, in the coal thermal power generation system, sulfur oxides are removed by a desulfurization device provided downstream of the combustion boiler to prevent the release of sulfur oxides to the atmosphere.

On the other hand, harmful trace elements are contained in coal ash produced by the combustion of pulverized coal, and also exist as solids or gases in the exhaust gas.
Most of the harmful trace element compounds present as solids in the exhaust gas are treated together with coal ash in a dust collector. On the other hand, some harmful trace element compounds present as gases in the exhaust gas may be dissolved in the desulfurized filtrate discharged from the desulfurization apparatus.

  The desulfurized filtrate is sent to a wastewater treatment facility for treatment, and then discharged as treated water from a discharge outlet to a general river or sea area. In order to comply with laws and regulations such as the Water Pollution Control Law, the content of harmful trace elements in the treated water must not exceed a predetermined reference value. For example, Patent Document 1 discloses a method of removing boron, which is a kind of harmful trace element, as an insoluble precipitate using slaked lime or aluminum sulfate.

JP-A-10-225682

  However, when treating a large amount of desulfurized filtrate containing boron, a large amount of slaked lime or aluminum sulfate is used to remove boron, which is a kind of harmful trace element, using the method disclosed in Patent Document 1. Processing cost problems arise.

  Therefore, before the harmful trace elements flow into the wastewater treatment facility, the desulfurized filtrate may be diluted to reduce the concentration of the harmful trace elements. For example, the boron concentration of boron contained in the desulfurized filtrate is intermittently measured using a sensor, the amount of dilution water is determined based on this measurement value, the boron concentration is measured accurately, and this measurement value is There is a method for determining the amount of dilution water based on this. However, in such a method, an error occurs in the boron concentration measured by the sensor, and the value may differ from the actual boron concentration. On the other hand, when measuring the boron concentration with high accuracy, the measurement interval becomes longer than the case of intermittent measurement using a sensor due to the problem of processing cost.

  An object of the present invention is to provide a dilution water amount management device and a dilution water amount management method that can determine the dilution water amount of a desulfurized filtrate simply and with high accuracy.

  A dilution water amount management device according to the present invention includes a boron concentration measurement unit that intermittently measures boron concentration of boron contained in a desulfurization filtrate of a desulfurization device, a boron concentration reception unit that receives input of the boron concentration, and the boron Based on the difference calculated by the difference calculating unit that calculates the difference between the boron concentration measured by the concentration measuring unit and the boron concentration received by the boron concentration receiving unit, the boron concentration measurement A correction value determining unit for determining a correction value for the boron concentration measured by the unit, and correcting the boron concentration measured by the boron concentration measuring unit based on the correction value determined by the correction value determining unit, A dilution amount determination unit that determines the dilution amount of the desulfurized filtrate based on the corrected boron concentration.

  Further, the dilution water amount management device according to the present invention is a storage control unit that associates and stores the storage unit, the boron concentration measured by the boron concentration measurement unit, and the time when the boron concentration is measured in the storage unit. The boron concentration receiving unit receives the boron concentration and the collection time of the desulfurized filtrate used for the measurement of the boron concentration, and the difference calculating unit is configured such that the boron concentration receiving unit receives the boron concentration. And receiving the input of the sampling time, the boron concentration associated with the time closest to the sampling time is extracted from the storage unit, and the boron concentration received by the boron concentration receiving unit, It is preferable to calculate the difference from the extracted boron concentration.

  The dilution water amount management method according to the present invention is a dilution water amount management method in which the dilution water amount management device determines the dilution water amount of the desulfurization filtrate, and intermittently measures the boron concentration of boron contained in the desulfurization filtrate of the desulfurization device. Measuring step, receiving step for receiving the input of the boron concentration, difference calculating step for calculating the difference between the boron concentration measured in the measuring step and the boron concentration received in the receiving step, and the difference calculation Based on the difference calculated in the step, a correction value determination step for determining a correction value for the boron concentration measured in the measurement step, and a boron concentration measured in the measurement step are determined in the correction value determination step. Correct based on the corrected value, and determine the dilution amount of the desulfurized filtrate based on the corrected boron concentration. Containing a dilute amount determining step.

  According to the present invention, the amount of diluted water of the desulfurized filtrate can be determined easily and with high accuracy.

It is a lineblock diagram showing the outline of the thermal power generation system which is one embodiment of the present invention. It is a block diagram which shows the function outline | summary of a dilution water amount management apparatus. It is a flowchart which shows the flow of a boron concentration management process.

Hereinafter, embodiments of the present invention will be described.
FIG. 1 is a configuration diagram showing an outline of a thermal power generation system 1 according to an embodiment of the present invention.

A thermal power generation system 1 shown in FIG. 1 is mainly used in a thermal power plant, and generates electric power by rotating a turbine with steam generated by burning coal.
In this thermal power generation system 1, exhaust gas is generated by burning coal. This exhaust gas contains coal ash such as clinker ash and fly ash produced by burning coal. The thermal power generation system 1 collects coal ash contained in the exhaust gas.

  As shown in FIG. 1, the thermal power generation system 1 includes a coal bunker 20, a pulverized coal machine 30, a combustion boiler 40, an exhaust passage (flue) 50, a denitration device 60, an air preheater 70, and ventilation. Machine 75, heat recovery gas heater 80, electrostatic precipitator 90, induction fan 210, desulfurizer 220, reheating gas heater 240, desulfurizer fan 250, and chimney 260.

The coal bunker 20 stores coal supplied from a coal silo (not shown) by a coal transportation facility.
The pulverized coal machine 30 pulverizes the coal supplied from the coal bunker 20 via the coal feeder 25 to a fine particle size to generate pulverized coal. The pulverized coal machine 30 supplies the generated pulverized coal to the combustion boiler 40.

  The combustion boiler 40 mixes and burns the pulverized coal supplied from the pulverized coal machine 30 with the forcedly supplied air to generate steam. Steam generated in the combustion boiler 40 is supplied to a turbine (not shown) via a main steam pipe (not shown). Thereby, a turbine rotates with steam and electric power generation is performed. Here, when pulverized coal burns, coal ash such as clinker ash and fly ash is generated and exhaust gas is generated. As will be described later, fly ash is collected by the electrostatic precipitator 90.

The exhaust passage 50 is provided on the downstream side of the combustion boiler 40 and introduces exhaust gas generated in the combustion boiler 40 into the denitration device 60.
The denitration device 60 removes nitrogen oxides in the exhaust gas. Specifically, the denitration device 60 injects ammonia gas as a reducing agent into the exhaust gas at a relatively high temperature (300 ° C. to 400 ° C.), and converts nitrogen oxides in the exhaust gas into harmless nitrogen by the action of the denitration catalyst. Nitrogen oxides in exhaust gas are removed by a method that decomposes into water vapor (dry ammonia catalytic reduction method).

  The air preheater 70 includes a heat exchange element inside. This heat exchange element performs heat exchange between the exhaust gas from which nitrogen oxides have been removed by the denitration device 60 and the combustion air supplied to the combustion boiler 40.

The ventilator 75 pumps and supplies the combustion air heat-exchanged by the air preheater 70 to the combustion boiler 40.
The heat recovery gas heater 80 performs heat recovery of the exhaust gas heat-exchanged by the air preheater 70 and introduces the exhaust gas after heat recovery into the electric dust collector 90.

  The electric dust collector 90 collects coal ash such as clinker ash and fly ash in the exhaust gas with an electrode. The fly ash collected by the electrostatic precipitator 90 is discharged to a raw powder silo 95 that stores fly ash via a hopper, a pressure transporter, etc. (all not shown).

The induction fan 210 introduces the exhaust gas that has passed through the electrostatic precipitator 90 into the desulfurizer 220.
The desulfurizer 220 purifies the desulfurized gypsum slurry by spraying a mixed liquid of limestone and water on the exhaust gas to absorb the sulfur oxide contained in the exhaust gas into the mixed liquid. The desulfurizer 220 generates desulfurized gypsum by dehydrating the desulfurized gypsum slurry. The produced desulfurized gypsum is introduced into a desulfurized gypsum recovery device (not shown).
Further, the desulfurization device 220 discharges the desulfurized filtrate generated by the dehydration process to the drainage channel 222.

  The drainage channel 222 is provided with a boron concentration measurement sensor 224. This boron concentration measurement sensor 224 constitutes a diluted water amount management device 223 described later, and measures the boron concentration of the desulfurized filtrate flowing through the drainage channel 222 intermittently (for example, every 5 minutes). Here, the boron concentration measurement sensor 224 outputs the measured boron concentration to the control unit of the dilution water amount management device 223. Hereinafter, the boron concentration measured by the boron concentration measurement sensor 224 is referred to as a first boron concentration.

FIG. 2 is a block diagram showing a functional outline of the diluted water amount management device 223.
The diluted water amount management device 223 is a computer, and includes a boron concentration measurement sensor 224, an input unit 225, a storage unit 226, a control unit 227, a communication device, a display device, an HDD (Hard Disk Drive), and a bus connecting them. ing.

  The input unit 225 is configured by, for example, a mouse or a keyboard. The input unit 225 functions as a boron concentration receiving unit, and receives an input of a measurement value of the boron concentration of the desulfurized filtrate in the drainage channel 222 and a time when the desulfurized filtrate to be measured is collected. The input unit 225 outputs the received measurement value and time of the boron concentration to the control unit 227. Here, the measured value of the boron concentration received by the input unit 225 is more accurate than the measured value of the first boron concentration measured by the boron concentration measurement sensor 224. The measurement of the boron concentration received by the input unit 225 is performed, for example, every predetermined time (2 days). Hereinafter, the boron concentration received by the input unit 225 is referred to as a second boron concentration.

  The storage unit 226 includes a RAM and a ROM, and stores the first boron concentration measured by the boron concentration measurement sensor 224.

  The control unit 227 is configured by a CPU or the like, and implements various functions in cooperation with the above-described hardware by appropriately reading and executing various programs stored in the storage unit 226. The control unit 227 functions as a storage control unit, a difference calculation unit, a correction value determination unit, and a dilution amount determination unit.

  Specifically, the control unit 227 stores the first boron concentration measured by the boron concentration measurement sensor 224 and the measurement time in the storage unit 226 in association with each other.

The control unit 227 calculates a difference between the first boron concentration measured by the boron concentration measurement sensor 224 and the second boron concentration received by the input unit 225.
That is, the control unit 227 refers to the storage unit 226 in response to the input unit 225 receiving the second boron concentration and the time when the desulfurized filtrate is collected, and is closest to the time when the desulfurized filtrate is collected. The first boron concentration associated with the measurement time is extracted. Subsequently, the control unit 227 calculates a difference between the second boron concentration received by the input unit 225 and the extracted first boron concentration.

The controller 227 determines a correction value for the first boron concentration measured by the boron concentration measurement sensor 224 based on the calculated difference.
For example, the control unit 227 calculates a ratio between the calculated difference and the extracted first boron concentration to determine a correction value. For example, if the extracted first boron concentration is 1 and the accepted second boron concentration is 1.2, the difference is 0.2. In this case, the control unit 227 calculates the ratio between the calculated difference and the first boron concentration measured by the boron concentration measurement sensor 224 as 0.2. Then, the control unit 227 determines the correction value as a value (1.2) that increases the first boron concentration by the calculated ratio.

  The control unit 227 causes the storage unit 226 to store the determined correction value. Here, when a correction value is newly determined, the control unit 227 deletes the past correction value and stores only the new correction value.

  The control unit 227 corrects the first boron concentration measured by the boron concentration measurement sensor 224 based on the correction value stored in the storage unit 226. For example, the control unit 227 corrects the first boron concentration measured by the boron concentration measurement sensor 224 by multiplying the correction value stored in the storage unit 226.

  Subsequently, the control unit 227 determines the dilution amount of the desulfurization filtrate based on the corrected first boron concentration, and dilutes the desulfurization filtrate in the drainage channel 222 with the determined amount of dilution water. For example, when a dilution channel is connected to the drainage channel 222 and a sluice that adjusts the amount of water is provided in the dilution channel, the control unit 227 opens the sluice according to the determined amount of dilution water. The dilution water is caused to flow into the drainage channel 222.

Returning to FIG. The desulfurization gypsum recovery device 230 recovers the desulfurization gypsum generated by the desulfurization device 220.
The reheating gas heater 240 heats the exhaust gas from which the sulfur oxide has been removed by the desulfurization apparatus 220.
The desulfurization ventilator 250 introduces the exhaust gas heated by the reheating gas heater 240 into the chimney 260. The heated exhaust gas is efficiently discharged from the chimney 260 by the chimney effect.

  Next, a flow of processing for determining the dilution water amount executed by the dilution water amount management device 223 will be described. FIG. 3 is a flowchart showing the flow of processing for determining the amount of dilution water according to the present embodiment.

  In step S <b> 1, the control unit 227 determines whether or not the second boron concentration is received by the input unit 225. When this determination is YES, the control unit 227 moves the process to step S2, and when this determination is NO, the control unit 227 moves the process to step S4.

In step S <b> 2, the control unit 227 calculates a difference between the first boron concentration measured by the boron concentration measurement sensor 224 and the second boron concentration received by the input unit 225.
In step S3, the control unit 227 determines a correction value based on the difference calculated in step S2. Then, the control unit 227 causes the storage unit 226 to store the determined correction value.

  In step S <b> 4, the control unit 227 acquires a measurement value of the first boron concentration measured by the boron concentration measurement sensor 224. The control unit 227 associates the measured first boron concentration with the time when the first boron concentration was measured (acquired time), and causes the storage unit 226 to store the first boron concentration.

In step S5, the control unit 227 corrects the first boron concentration acquired in step S4 based on the correction value stored in the storage unit 226 in step S3.
In step S6, the control unit 227 determines the amount of dilution water based on the first boron concentration corrected in step S5.

  In step S7, the control unit 227 determines whether an end operation has been performed. When this determination is YES, the control unit 227 ends the process of this flowchart, and when this determination is NO, the control unit 227 moves the process to step S1.

  As described above, according to the present embodiment, the diluted water amount management device 223 intermittently measures the boron concentration of boron contained in the desulfurized filtrate of the desulfurization device 220 by the boron concentration measurement sensor 224, and the boron concentration by the input unit 225. And the control unit 227 calculates the difference between the boron concentration measured by the boron concentration measurement sensor 224 (first boron concentration) and the boron concentration received by the input unit 225 (second boron concentration). . The diluted water amount management device 223 determines the correction value of the first boron concentration measured by the boron concentration measurement sensor 224 based on the calculated difference by the control unit 227, and the measurement is performed by the boron concentration measurement sensor 224. The first boron concentration is corrected based on the determined correction value. The dilution water amount management device 223 determines the dilution amount of the desulfurized filtrate based on the corrected first boron concentration by the control unit 227.

  By doing in this way, the dilution water amount management device 223 is calculated based on the difference between the first boron concentration intermittently measured by the boron concentration measurement sensor 224 and the second boron concentration received by the input unit 225. The correction value can be corrected using the correction value. Therefore, even if there is an error in the first boron concentration measured by the boron concentration measurement sensor 224, the diluted water amount management device 223 is based on the correction value obtained from the difference from the second boron concentration received by the input unit 225. Therefore, the accuracy can be improved. Therefore, the diluted water amount management device 223 can determine the diluted water amount of the desulfurized filtrate easily and with high accuracy.

  Further, the dilution water amount management device 223 causes the control unit 227 to associate the first boron concentration measured by the boron concentration measurement sensor 224 with the time when the first boron concentration is measured, and store it in the storage unit 226. The input unit 225 receives the second boron concentration and the collection time of the desulfurized filtrate used for the measurement of the second boron concentration. The dilution water amount management device 223 is associated with the time closest to the collection time from the storage unit 226 in response to the input of the second boron concentration and the collection time by the control unit 227. The first boron concentration is extracted, and the difference between the second boron concentration received by the input unit 225 and the extracted first boron concentration is calculated.

  By doing in this way, the dilution water amount management apparatus 223 uses the two boron concentrations measured from the desulfurized filtrate at the same time when calculating the difference based on the second boron concentration received by the input unit 225. Therefore, the difference can be calculated accurately.

  The embodiment of the present invention has been described above, but the present invention is not limited to the present embodiment, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.

  In the present embodiment, when the correction value is newly determined, the control unit 227 deletes the past correction value and stores only the new correction value. However, the present invention is not limited to this. The control unit 227 may store the determined correction value and the time when the correction value is determined in association with each other, and perform correction using the correction value corresponding to the latest time.

220 Desulfurization device 222 Drainage channel 223 Dilution water amount management device 224 Boron concentration measurement sensor 225 Input unit 226 Storage unit 227 Control unit

Claims (3)

A boron concentration measurement unit that intermittently measures the boron concentration of boron contained in the desulfurization filtrate of the desulfurization apparatus;
A boron concentration receiving unit for receiving an input of the boron concentration;
A difference calculating unit for calculating a difference between the boron concentration measured by the boron concentration measuring unit and the boron concentration received by the boron concentration receiving unit;
A correction value determining unit that determines a correction value of the boron concentration measured by the boron concentration measuring unit based on the difference calculated by the difference calculating unit;
A dilution amount that corrects the boron concentration measured by the boron concentration measurement unit based on the correction value determined by the correction value determination unit and determines the dilution amount of the desulfurized filtrate based on the corrected boron concentration A decision unit;
A dilution water amount management device comprising: A storage unit;
A storage control unit that associates the boron concentration measured by the boron concentration measurement unit with the time at which the boron concentration was measured and stores it in the storage unit;
The boron concentration receiving unit receives the boron concentration and the collection time of the desulfurized filtrate used for the measurement of the boron concentration,
The difference calculating unit extracts, from the storage unit, a boron concentration associated with a time closest to the sampling time in response to the boron concentration receiving unit receiving an input of the boron concentration and the sampling time. And calculating the difference between the boron concentration received by the boron concentration receiving unit and the extracted boron concentration.
The dilution water amount management apparatus according to claim 1. The dilution water amount management device is a dilution water amount management method in which the dilution water amount of the desulfurized filtrate is determined,
A measurement step for intermittently measuring the boron concentration of boron contained in the desulfurization filtrate of the desulfurization apparatus;
A reception step for receiving an input of the boron concentration;
A difference calculating step for calculating a difference between the boron concentration measured in the measuring step and the boron concentration received in the receiving step;
A correction value determination step for determining a correction value of the boron concentration measured by the measurement step based on the difference calculated by the difference calculation step;
A dilution amount determination step for correcting the boron concentration measured in the measurement step based on the correction value determined in the correction value determination step, and determining the dilution amount of the desulfurized filtrate based on the corrected boron concentration; ,
A method for managing the amount of diluted water.

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