JP2013103181A - Water quality controlling method and water quality controlling apparatus of boiler water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water quality controlling method and a water quality controlling apparatus of boiler water by means of which water quality of the boiler water can be maintained within a range of a control standard value even when boiler feed water contains sodium.SOLUTION: The water quality controlling apparatus 2 measures phosphoric acid concentration and an Na/POmolar ratio in the boiler water and based on this measurement result, calculates sodium concentration CNa in the boiler feed water. Further based on this sodium concentration CNa, the water quality controlling apparatus 2 calculates phosphoric acid concentration TCPOin the boiler water necessary for making the Na/POmolar ratio in the boiler water an objective control value. The water quality controlling apparatus 2 further calculates an injection amount SDr [mL/h] of a low molar ratio boiler compound being a boiler compound in which an Na/POmolar ratio corresponding to the calculated phosphoric acid concentration TCPOis lower than the objective control value of the Na/POmolar ratio in the boiler water. The water quality controlling apparatus 2 then injects low molar ratio boiler compound to the boiler water at a calculated injection amount SDr.

Description

  The present invention relates to a technique for maintaining the quality of water in a boiler can within a predetermined control reference value by injecting an appropriate amount of a medicine containing sodium and phosphoric acid.

  Conventionally, in a boiler that heats supplied water to generate steam, mixed water of steam condensate (condensate) and makeup water sent from the boiler to the steam equipment is supplied to the boiler as feed water. This water supply is stored in the boiler can and circulates in the water pipe in the boiler to generate steam. The water in this boiler can (canned water) causes corrosion and scaler adhesion in the boiler, so the water quality of the boiler can is preliminarily injected by injecting a cleansing agent containing sodium, phosphoric acid, etc. It is maintained within the range of the defined management reference value (see Patent Document 1).

Patent Document 1 discloses a sodium salt-type phosphate cleansing agent, trisodium phosphate, phosphorous, for adjusting pH for preventing corrosion in a boiler and preventing scale adhesion due to mixing of hardness components. A technique for injecting a liquid cleansing agent using disodium oxyhydrogen and sodium hydroxide is disclosed.
On the other hand, after the cleansing agent is injected into the boiler can water, the blow control is performed in order to discharge the hardness component changed into a floating substance by the injected cleansing agent out of the system. By this blow control, the cleaning agent component in the boiler can water is also discharged out of the system. For this reason, conventionally, the injection amount of the canning agent has been determined based on the idea of compensating for the amount discharged by blow.

JP 2007-181797 A

In the water quality management of boiler can water using the above-described conventional method for determining the injection amount, the phosphoric acid concentration in the boiler can water is lower than the control lower limit value, and the sodium and phosphoric acid in the boiler can water It was confirmed that a situation in which the molar ratio of the can water Na / PO ₄ molar ratio exceeded the control upper limit value occurred. And it discovered that this cause was a sodium contained in boiler feed water.
Therefore, the present invention was made paying attention to such an unsolved problem of the conventional technology, and even when the boiler feed water contains sodium, the water quality of the boiler can water is within the range of the management reference value. It aims at providing the water quality management method and water quality management apparatus of boiler can water which can be maintained in the inside.

[Mode 1] In order to achieve the above object, the water quality control method for boiler can water according to mode 1 is a method in which a chemical containing sodium and phosphoric acid is injected into boiler can water, which is water existing in the boiler can body. And adjusting the can water Na / PO ₄ molar ratio, which is the molar ratio of sodium and phosphoric acid contained in the boiler can water, to a predetermined target management value, A boiler water quality management method for maintaining water quality within a predetermined management reference value range, wherein a chemical to be injected into the boiler water is a molar ratio of sodium and phosphoric acid contained in the chemical. sodium in drug Na / PO ₄ molar ratio as low molar ratio drug lower molar ratio than the target control value, to measure the concentration of sodium contained in the boiler feed water is water to be supplied to the boiler can body A concentration measuring step, based on the sodium concentration of the boiler feedwater measured in the sodium concentration measuring step, the injection amount of the low molar ratio medicament for the boiler water Na / PO ₄ molar ratio and the target control value A medicine injection amount calculating step to calculate, and a medicine injection step of injecting the low molar ratio medicine into the boiler can water at the injection amount calculated in the medicine injection amount calculating step.

That is, based on the sodium concentration in the boiler feed water, the injection amount of the low molar ratio drug having the can water Na / PO ₄ molar ratio as the target control value is calculated, and the drug Na / PO ₄ molar ratio is calculated by the calculated injection amount. A low molar ratio drug lower than the target control value was injected. As a result, the Na / PO ₄ molar ratio in the boiler can water can be adjusted to the target control value due to the sodium in the feed water, and the PH, phosphoric acid concentration and Na / PO ₄ mole in the boiler can water can be adjusted. It becomes possible to maintain the ratio within the range of the management reference value.
Here, in the sodium concentration measurement step, the sodium concentration in the boiler feed water may be directly measured with a measuring instrument or the like, or may be obtained by analysis, for example, phosphoric acid concentration in boiler can water, measuring the boiler water Na / PO ₄ molar ratio, etc., may be calculated based on the measured result.

[Mode 2] Furthermore, the boiler water quality management method according to mode 2 is different from the configuration of mode 1 in that in the sodium concentration measurement step, the current concentration BCPO of phosphoric acid contained in the boiler can water _4, the measured value of the current can water Na / PO ₄ molar ratio, the drug Na / PO ₄ molar ratio of the low molar ratio drug, the molar mass of sodium WNa, and the molarity of phosphoric acid The water quality management method for boiler can water according to claim 1, wherein the concentration CNa of sodium contained in the water supply is calculated based on the mass WPO ₄ according to the following equation (1).
CNa = BCPO ₄ × (measured value of can water Na / PO ₄ molar ratio−drug Na / PO ₄ molar ratio) / (WPO ₄ / WNa) (1)
As a result, it is possible to appropriately measure the sodium concentration in the current boiler feed water, and the same effect as in the first aspect can be obtained.

[Form 3] Furthermore, the water quality management method for boiler can water described in Form 3 is the chemical injection amount calculating step for the configuration of Form 1 or 2,
Sodium concentration CNa measured in the sodium concentration measurement step, drug Na / PO ₄ molar ratio of the low molar ratio drug, target control value, molar mass WNa of sodium, and phosphoric acid Based on the molar mass of WPO ₄ , the phosphoric acid concentration TCPO ₄ in the boiler can water necessary for setting the can water Na / PO ₄ molar ratio as the target control value is calculated according to the following formula (2). A first calculation step;
Based on the phosphoric acid concentration TCPO ₄ calculated in the first calculating step, the boiler concentration factor Bem, and the proportion PR of phosphoric acid in the low molar ratio drug, the phosphoric acid concentration according to the following formula (3) A second calculation step of calculating a low molar ratio drug concentration CDr in the boiler feed water corresponding to TCPO ₄ ;
Based on the low molar ratio drug concentration CDr calculated in the second calculation step, the boiler feed water supply amount WS, and the low molar ratio drug dilution rate P, the low molar ratio drug is calculated according to the following formula (4). The boiler water quality management method according to claim 1, further comprising a third calculation step of calculating an injection amount SDr of the molar ratio drug.

TCPO ₄ = CNa × (WPO ₄ / WNa) / (target control value−drug Na / PO ₄ molar ratio) (2)
CDr = (TCPO ₄ / Bem) / PR (3)
SDr = WS × CDr × P (4)
This makes it possible to calculate an appropriate low molar ratio injection amount for setting the can water Na / PO ₄ molar ratio in the boiler can water to the target control value, and obtaining the same effect as in the first aspect. Can do.

[Mode 4] On the other hand, in order to achieve the above object, the water quality management device of mode 4 injects a drug containing sodium and phosphoric acid into boiler can water, which is water existing in the boiler can body, By adjusting the can water Na / PO ₄ molar ratio, which is the molar ratio of sodium and phosphoric acid contained in the boiler can water, to a predetermined target control value, the water quality of the boiler can water is determined in advance. A water quality management device for maintaining the drug within the range of the control standard value, wherein the drug has a drug Na / PO ₄ molar ratio, which is a molar ratio of sodium and phosphoric acid contained in the drug, from the target management value. A low molar ratio drug with a low molar ratio, and a sodium concentration measuring unit that measures the concentration of sodium contained in boiler feed water, which is water supplied to the boiler can body, and before the measurement by the sodium concentration measuring unit Based on the sodium concentration of the boiler feedwater, and chemical feeding, chemical dosing amount calculation unit for calculating an injection amount of the low molar ratio medicament for the boiler water Na / PO ₄ molar ratio of the boiler brine and the target control value, A drug injection unit that injects the low molar ratio drug into the boiler can water at an injection amount calculated by the drug injection amount calculation unit.

In such a configuration, when the sodium concentration in the boiler feed water is measured by the sodium concentration measurement unit, the Na / PO _{4 in the} boiler can water is based on the sodium concentration in the boiler feed water by the chemical injection amount calculation unit. The injection amount of the low molar ratio drug for setting the molar ratio as the target management value is calculated. And a low molar ratio chemical | medical agent is inject | poured into a boiler can water by the calculated injection quantity by the chemical | medical agent injection | pouring part.

As a result, the Na / PO ₄ molar ratio in the boiler can water can be adjusted to the target control value due to the sodium in the feed water, and the PH, phosphoric acid concentration and Na / PO ₄ mole in the boiler can water can be adjusted. It becomes possible to maintain the ratio within the range of the management reference value.
Here, the sodium concentration measuring unit may be configured to directly measure the sodium concentration in the boiler feed water, or may be determined by analysis. For example, the phosphoric acid concentration in the boiler can water, measured PO ₄ molar ratio, etc., may be calculated based on the measured result.

According to the water quality management method or the water quality management apparatus for boiler can water according to the present invention, it is possible to suppress an increase in the Na / PO ₄ molar ratio in boiler can water due to sodium in boiler feed water. As a result, the Na / PO ₄ molar ratio in the boiler can water can be maintained within the range of the control reference value, and the pH and the phosphoric acid concentration in the boiler can water can also be maintained within the control reference value range. The effect of being able to be obtained. Moreover, since it becomes possible to manage with appropriate water quality, the amount of thinning of the boiler tube can be reduced, and the effect of reducing the repair cost of the boiler tube can be obtained.

It is a figure showing typically one embodiment of the boiler equipment concerning the present invention. It is a block diagram which shows the structure of a water quality management apparatus. It is a flowchart which shows an example of the process sequence of a chemical injection control process. (A) and (b) is a diagram showing PH boiler brine before and after change of boiler cleaning chemicals, boiler compound, concentration phosphoric acid, an example of a boiler water Na / PO ₄ molar ratio, (c), the low molar ratios PH, phosphoric acid concentration of the boiler brine before and after change of the injection amount of Kiyoshikan agent is a diagram illustrating an example of a boiler water Na / PO ₄ molar ratio. It is a figure which shows the operating conditions of each boiler used for the test. (A)-(c) is a figure which shows the test result at the time of inject | pouring a low molar ratio cleansing agent with the same chemical injection amount control method as the water quality management apparatus 2 with respect to each boiler used for the test.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1-4 is a figure which shows embodiment of the water quality management method and water quality management apparatus of boiler can water which concern on this invention.
(Constitution)
First, the structure of the boiler equipment to which the water quality management apparatus according to the present invention is applied will be described with reference to FIG. FIG. 1 is a diagram schematically showing an embodiment of a boiler facility according to the present invention.
As shown in FIG. 1, a boiler facility 100 includes a boiler device 1 that heats supply water and generates high-pressure steam, a water quality management device 2 that manages the quality of water present in the boiler can, and a low-pressure turbine 3. The condensing device 4, the deionized water device 5, and the deaeration device 6 are configured.

The low-pressure turbine 3 expands the high-pressure steam generated in the boiler device 1 in the turbine to convert it into low-pressure steam, discharges a part of the converted low-pressure steam outside the system (such as a factory), and the rest as a condensing device Drain to 4.
The condensing device 4 cools and condenses the low-pressure steam from the low-pressure turbine 3, and discharges this condensate to the deaeration device 6.
The pure water device 5 purifies pure water by subjecting raw water (tap water, industrial water, groundwater, etc.) to filtration and ion exchange, and discharges the pure water to the deaeration device 6.

The deaeration device 6 heats the mixed water from the condensing device 4 and the pure water from the pure water device 5 to separate and remove the dissolved gas contained in the mixed water. Then, mixed water from which dissolved gas is separated and removed (hereinafter referred to as boiler feed water) is supplied to the boiler apparatus 1.
The boiler device 1 includes a water pipe 11, a combustion chamber 12, a steam drum 13, and a water drum 14.
The water pipe 11 is disposed across the heating section of the combustion chamber 12 and circulates water between the water drum 14 and the steam drum 13. The combustion chamber 12 generates heat by burning fuel such as oil or gas, and heats water circulating in the water pipe 11. The steam drum 13 takes out the steam generated by this heating. The water drum 14 stores boiler feed water supplied via the deaeration device 6.

The boiler device 1 circulates the water stored in the water drum 14 through the water pipe 11 by a pump (not shown) or the like, and burns fuel in the combustion chamber 12. The heat generated by the combustion of the fuel heats the water circulating in the water pipe 11 to generate high-pressure steam. Then, the generated high-pressure steam is taken out from the steam drum 13.
In the present embodiment, the water pipe 11, the steam drum 13, and the water drum 14 constitute a boiler can body. In the present embodiment, the boiler device 1 periodically blows and discharges impurities (hardness component) contained in water in the boiler can (hereinafter referred to as boiler can water) out of the system.

The water quality management device 2 injects a cleansing agent into the boiler can water in the boiler can body, and maintains the water quality of the boiler can water within a predetermined management reference value range.
Here, the cleansing agent is a chemical agent that reacts with Ca, Mg, SiO ₂ which are hardness components in the boiler can water, and changes these into floating substances. Ca, Mg, and SiO _{2 that} have become floating substances are discharged out of the system by blowing. That is, the cleansing agent has a function of preventing the scale from adhering to the boiler body and a function of preventing the corrosion of the water pipe 11 by adjusting the PH of the boiler can water.

On the other hand, it is important to control the water quality of boiler can water because of the influence of corrosion and scale adhesion. Therefore, water quality management is performed with emphasis on the concentration of PH and phosphoric acid (PO ₄ ). Yes.
The inventors of the present invention have so far used a can with a molar ratio of sodium (Na) to phosphoric acid (PO ₄ ) (hereinafter referred to as a drug Na / PO ₄ molar ratio) of “3” (Na ₃ PO ₄ ) has been used. In addition, until now, the injection of the canning agent has been performed by the injection amount obtained by the following equation (5) from the idea of supplementing the chemicals discharged by continuous blow.
Injection amount [g / h] of the canning agent = necessary phosphoric acid concentration [mg / L] × blow amount [t / h] × 100 / ratio of phosphoric acid in the canning agent [%] (5)

Then, the inventors of the present invention have found that when a cleansing agent having a drug Na / PO ₄ molar ratio of “3” is injected by the injection method based on the drug injection amount obtained according to the above equation (5), It was confirmed that the acid concentration deviated from the range of the control standard value. In addition, it was also confirmed that the molar ratio of Na to PO ₄ contained in boiler can water (hereinafter referred to as can water Na / PO ₄ molar ratio) deviates from the range of the control standard value. In addition, the present inventors have found that the cause of these problems is that Na contained in the boiler feed water becomes free alkali and increases the pH of the boiler can water, and increases the can water Na / PO ₄ molar ratio. I found out.
Incidentally, JIS management reference value defined in (Japanese Industrial Standards) is, PH is 9.0 to 10.0, the concentration of phosphoric acid 2 to 6 [ppm], boiler water Na / PO ₄ molar ratio of 3. 0 or less.

From the above, the present inventors first introduced a canning agent to be injected, whose drug Na / PO ₄ molar ratio is lower than the target management value (for example, 2.8 to 3.0) (hereinafter, Changed to a low molar ratio canning agent). The target management value is set to a value within the management reference value range. Next, the Na concentration in the boiler feed water is obtained, and based on this Na concentration, the phosphoric acid concentration necessary for setting the can water Na / PO ₄ molar ratio as the target management value for such a low molar ratio cleansing can. The injection amount was calculated.

Next, based on FIG. 2, the detailed structure of the water quality management apparatus 2 is demonstrated. FIG. 2 is a block diagram showing the configuration of the water quality management device.
As shown in FIG. 2, the water quality management device 2 includes a can water component measurement unit 20, a sodium concentration calculation unit 21, a target phosphoric acid concentration calculation unit 22, a drug concentration calculation unit 23, and a chemical injection amount calculation unit 24. The medicine injection control unit 25, the infusion pump 26, and the medicine tank 27 are configured.

The can water component measuring unit 20 collects a predetermined amount of boiler can water in the boiler can. Then, a reagent or the like is added to the collected boiler can water, and the PO ₄ concentration BTPO ₄ in the current boiler can water is measured. In addition, the current can water Na / PO ₄ molar ratio is measured from the collected boiler can water. Further, the can water component measurement unit 20 outputs these measurement results to the sodium concentration calculation unit 21.

The sodium concentration calculation unit 21 includes a measurement result from the can water component measurement unit 20, a low molar ratio drug Na / PO ₄ molar ratio stored in advance in a memory (not shown), a molar mass WNa of Na, based on the molar mass WPO ₄ of PO _4, according to the following equation (6), calculates the Na concentration CNa of the boiler feedwater.
CNa [ppm] = BTPO ₄ [ppm] × (canned water Na / PO ₄ molar ratio−drug Na / PO ₄ molar ratio) / (WPO ₄ / WNa) (6)
In the above formula (6), WNa is “23” and WPO ₄ is “95”, so “WPO ₄ /WNa=95/23≈4.13”. In the present embodiment, it is assumed that “4.13” is set in advance as “WPO ₄ / WNa” in the information of the above equation (6) stored in a memory (not shown).

The sodium concentration calculation unit 21 outputs the Na concentration CNa in the boiler feed water calculated according to the above equation (6) to the target phosphoric acid concentration calculation unit 22.
The target phosphoric acid concentration calculating unit 22 performs target management of the Na concentration CNa from the sodium concentration calculating unit 21 and the drug Na / PO ₄ molar ratio and the canned water Na / PO ₄ molar ratio stored in advance in a memory (not shown). Based on the value (for example, 2.8 to 3.0), WNa, and WPO ₄ , the target phosphoric acid concentration TCPO ₄ is calculated according to the following equation (7).
TCPO ₄ [ppm] = CNa [ppm] × (WPO ₄ / WNa) / (target control value−drug Na / PO ₄ molar ratio) (7)

The target phosphoric acid concentration calculation unit 22 outputs the target phosphoric acid concentration TCPO ₄ calculated according to the above equation (7) to the drug concentration calculation unit 23. In the present embodiment, it is assumed that “4.13” is set in advance as “WPO ₄ / WNa” in the information of the above equation (7) stored in a memory (not shown).
The drug concentration calculation unit 23 includes the target phosphate concentration TCPO ₄ from the target phosphate concentration calculation unit 22, the continuous blow amount Brq [L / h] of the boiler device 1 stored in advance in a memory (not shown), and boiler water supply. Based on the amount WS [L / h] and the ratio PR of phosphoric acid in the low molar ratio drug, the drug concentration CDr in the boiler feed water is calculated according to the following equation (4).
CDr [ppm] = {TCPO ₄ [ppm] / (WS / Brq [L / h])} / PR
... (8)

In the above equation (4), the result of dividing the boiler water supply amount WS by the continuous blow amount Brq (WS / Brq [L / h]) is the boiler concentration factor Bem. Further, TCPO ₄ [ppm] / (WS / Brq [L / h]) in the above formula ( ₄ ) is necessary to make the phosphoric acid concentration in the boiler can water the TCPO ₄ obtained by the above formula (7). It becomes the phosphoric acid concentration in the boiler feed water.

The drug concentration calculation unit 23 outputs the drug concentration CDr in the boiler feed water calculated according to the above equation (8) to the drug injection amount calculation unit 24.
The chemical injection amount calculation unit 24 is based on the chemical concentration CDr from the chemical concentration calculation unit 23, the boiler water supply amount WS [L / h] and the chemical dilution rate P [times] stored in advance in a memory (not shown). In accordance with the following equation (9), the injection amount SDr of the low molar ratio cleansing agent necessary for setting the can water Na / PO ₄ molar ratio as its target control value is calculated.
SDr [mL / h] = WS [L / h] × CDr [ppm] × P [times] (9)

The chemical injection amount calculation unit 24 outputs the injection amount SDr of the low molar ratio cleansing agent calculated according to the above formula (9) to the chemical injection control unit 25.
In addition, information on the drug Na / PO ₄ molar ratio, information on the target control value of the can water Na / PO ₄ molar ratio, information on the ratio PR of phosphoric acid in the low molar ratio drug, and information on the drug dilution rate P Information stored in a memory in advance can be used. In addition, information on the continuous blow amount Brq [L / h] and the boiler water supply amount WS [L / h] is stored in advance in the memory as information input from an existing flow rate measuring device, the control unit of the boiler device 1 or the like. The thing which memorize | stored beforehand in the memory etc. which the information input by the thing or equipment manager can be used.

The chemical injection control unit 25 generates a drive signal for the injection pump 26 based on the injection amount SDr from the chemical injection amount calculation unit 24, and supplies the generated drive signal to the drive unit of the injection pump.
The infusion pump 26 is an electric pump, and by driving an electric motor based on a drive signal from the drug injection control unit 25, the low molar ratio canning agent stored in the medicine tank 27 is inhaled, and the inhaled low Inject the molar ratio can into the boiler can. At this time, a low molar ratio cleansing agent is injected into the boiler can at an injection amount SDr [mL / h] corresponding to the drive signal. In the present embodiment, the injection pump 26 injects a low molar ratio cleansing agent through boiler feed water. That is, the low molar ratio cleansing agent is injected into the boiler can water through the water supply path of the boiler water supply.

  Although not shown, the water quality management device 2 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and a ROM (Read Only Memory) in which a dedicated program is stored. By executing a dedicated program, the functions of the above-described units are achieved. Here, each of the above functions of the water quality management device 2 includes a function that fulfills the function only by a dedicated program, a function that controls the hardware by the dedicated program, and performs the function.

Next, based on FIG. 3, the process procedure of the chemical injection control process which is a process which controls injection | pouring of the low molar ratio canning agent in the water quality management apparatus 2 is demonstrated. FIG. 3 is a flowchart illustrating an example of a processing procedure of the chemical injection control process.
When the chemical injection control process is executed by the CPU, first, the process proceeds to step S100 as shown in FIG.
In step S100, the can water component measurement unit 20 determines whether or not a chemical injection command has been issued. If it is determined that there has been a chemical injection command (Yes), the process proceeds to step S102, and if not, No) repeats the determination process until there is a chemical injection command.

When the process proceeds to step S102, the can water component measurement unit 20 measures the phosphoric acid concentration in the boiler can water, outputs the measured phosphoric acid concentration BCPO ₄ to the sodium concentration calculation unit 21, and proceeds to step S104. .
In step S104, the can water component measuring unit 20 measures the can water Na / PO ₄ molar ratio in the boiler can water, and outputs the measured can water Na / PO ₄ molar ratio to the sodium concentration calculating unit 21. The process proceeds to S106.

In step S106, in the sodium concentration calculation unit 21, the phosphoric acid concentration BCPO ₄ and the can water Na / PO ₄ molar ratio from the can water component measurement unit 20, and the drug Na / read out from a memory (RAM or ROM) not shown. Based on the PO ₄ molar ratio, the sodium concentration CNa in the boiler feed water is calculated according to the above equation (6). Then, the calculated sodium concentration CNa is output to the target phosphoric acid concentration calculation unit 22, and the process proceeds to step S108.

In step S108, the target phosphoric acid concentration calculation unit 22 uses the sodium concentration CNa in the boiler feed water and the target management values of the chemical Na / PO ₄ molar ratio and the canned water Na / PO ₄ molar ratio read from the memory (not shown). Based on the above, the target phosphoric acid concentration TCPO ₄ is calculated according to the above equation (7). Then, the calculated target phosphoric acid concentration TCPO ₄ is output to the drug concentration calculating unit 23, and the process proceeds to step S110.

In step S110, the drug concentration calculation unit 23 uses the target phosphoric acid concentration TCPO ₄ , the continuous blow amount Brq read from a memory (not shown), the boiler water supply amount WS, and the ratio PR of phosphoric acid in the low molar ratio drug. According to the above equation (8), the concentration CDr of the low molar ratio cleansing agent in the boiler feed water is calculated. Then, the calculated concentration CDr of the low molar ratio cleansing agent in the boiler feed water is output to the chemical injection amount calculation unit 24, and the process proceeds to step S112.

In step S112, in the chemical injection amount calculation unit 24, the concentration CDr of the low molar ratio cleaning agent in the boiler feed water, the boiler water supply amount WS and the dilution ratio P of the low molar ratio cleaning agent read from the memory (not shown), In accordance with the above formula (9), the injection amount SDr of the low molar ratio cleansing agent for maintaining the target control value of the can water Na / PO ₄ molar ratio is calculated. Then, the calculated injection amount SDr is output to the medicine injection control unit 25, and the process proceeds to step S114.

In step S114, the drug injection control unit 25 generates a drive signal for the injection pump 26 based on the injection amount SDr [mL / h] of the low molar ratio cleansing agent, and outputs the generated drive signal to the injection pump 26. The process proceeds to step S100.
As a result, the infusion pump 26 inhales the low molar ratio cleansing agent diluted at the dilution rate P stored in the medicine tank 27 so that the infusion amount SDr [mL / h] is obtained in accordance with the drive signal. Then, the inhaled low molar ratio cleansing agent is injected into the boiler can water in the boiler can.

(Operation)
Next, based on FIG. 4, operation | movement of the water quality management apparatus 2 of this embodiment is demonstrated, comparing with the injection method of the conventional cleaning agent. 4 (a) and 4 (b) are diagrams showing an example of the boiler can water pH, phosphoric acid concentration, and can water Na / PO ₄ molar ratio before and after the change of the cleaning agent, and FIG. PH boiler brine before and after change of the injection amount of the can material, the concentration of phosphoric acid is a diagram showing an example of a boiler water Na / PO ₄ molar ratio.

Conventionally, as a cleansing agent, a cleansing agent having a chemical Na / PO ₄ molar ratio of “3” (Na ₃ PO ₄ ) (hereinafter referred to as a molar ratio 3 cleansing agent) has been used. Below, the reaction formula with the hardness component of the molar ratio 3 cleansing agent is shown.
10Ca (HCO ₃ ) ₂ + 6Na ₃ PO ₄ + 2NaOH → [Ca ₃ (PO ₄ ) ₂ ] ₃ Ca (OH) ₂ + 10Na ₂ CO ₃ + 10CO ₂ + 10H ₂ O (10)
MgCl ₂ + 2NaOH → Mg (OH) ₂ + 2NaCl (11)
MgCl ₂ + SiO ₂ + 2NaOH → MgSiO ₃ + 2NaCl + H ₂ O (12)
SiO ₂ + 2NaOH → Na ₂ SiO ₃ + H ₂ O (13)

Moreover, conventionally, the amount of injection of 3 cans in a molar ratio has been calculated according to the above equation (5) in consideration of replenishing the amount of the missing cans by continuous blowing. In the example of FIG. 4, a 3 ratio molar can is actually injected into the No. 3, No. 4, No. 5 and No. 7 boilers. In FIGS. 4A and 4C, the left vertical axis indicates PH, the right vertical axis indicates Na / PO ₄ molar ratio, and the horizontal axis indicates phosphoric acid concentration [ppm].

As shown in FIGS. 4 (a) and 4 (b), when the can amount calculated in this way was injected into each boiler can with a molar ratio of 3 cans, the can water Na / PO ₄ molar ratio was the maximum. It became “5”, and exceeded the range of the control standard value (3.0 or less) for all boilers. In addition, as shown in FIGS. 4 (a) and 4 (b), the phosphoric acid concentration was below the control lower limit (2.0) in three boilers excluding the No. 7 boiler. Moreover, although PH showed the high value in all, it was in the range of the management reference value.

Next, a low molar ratio cleansing agent having a chemical Na / PO ₄ molar ratio of “2” (Na ₂ HPO ₄ ) (hereinafter referred to as a molar ratio 2 cleansing can) is used as the low molar ratio cleansing agent. In the same manner as in the prior art, the injection amount of the molar canister 2 was calculated according to the above formula (5).
And, when the injection amount calculated in this way was injected into each boiler can with a molar ratio of 2 cans, as shown in FIGS. 4 (a) and 4 (b), three boilers excluding the No. 5 boiler were used. The molar ratio of canned water Na / PO ₄ was lower than that in the case of using a can with 3 molar ratio. However, the phosphoric acid concentration was still below the control lower limit value except for the No. 7 boiler, and the can water Na / PO ₄ molar ratio exceeded the control standard value range in all the boilers.

The present inventors have found that the cause of the increase in the can water Na / PO ₄ molar ratio and the insufficient phosphoric acid concentration is due to Na in the boiler feed water. Therefore, in this embodiment, in addition to the use of a can with a molar ratio of 2 in addition to the idea of replenishing the amount discharged by continuous blow, the molar ratio of 2 is also taken into account in the Na concentration in the boiler feed water. The injection amount of the cleansing agent was calculated.

First, the water quality management device 2 determines the boiler water in the can water component measurement unit 20 in response to a chemical injection command inputted at the timing determined after a power-on or a preset schedule (Yes in S100). Collect a predetermined amount. Further, the current phosphoric acid concentration BTPO ₄ [ppm] in the boiler can water is measured with respect to the collected can water using a reagent or the like (S102). Subsequently, the current can water Na / PO ₄ molar ratio is measured (S104). Then, the can water component measuring unit 20 outputs these measurement results to the sodium concentration calculating unit 21.

For example, an antimonyl potassium tartrate solution and an ammonium molybdate solution are added to the collected boiler can water, and the reaction solution is reduced with an ascorbic acid solution. Since the reaction solution exhibits a blue color due to this reduction, the intensity of the blue color is quantified with an absorptiometer. Since the intensity of blue is proportional to the ion concentration of phosphoric acid, the phosphoric acid concentration can be quantified. Moreover, Na concentration in boiler can water is measured, for example with a sodium concentration meter. Then, the current can water Na / PO ₄ molar ratio is calculated from the current phosphoric acid concentration and Na concentration in the boiler can water.

When the current phosphoric acid concentration BTPO ₄ and the current can water Na / PO ₄ molar ratio are input from the can water component measuring unit 20, the sodium concentration calculating unit 21 receives the drug Na / Read PO ₄ molar ratio (eg, 2.0) information. Then, using the current phosphoric acid concentration BTPO ₄ , the current can water Na / PO ₄ molar ratio, and the chemical Na / PO ₄ molar ratio, the Na concentration CNa [ppm] in the boiler feed water is obtained from the above equation (2). Is calculated (S106). The sodium concentration calculation unit 21 outputs the calculated Na concentration CNa to the target phosphoric acid concentration calculation unit 22.

When the Na concentration CNa is input from the sodium concentration calculation unit 21, the target phosphoric acid concentration calculation unit 22 has a molar ratio of 2 chemicals Na / PO ₄ molar ratio and can water Na / PO ₄ molar ratio from the memory. Target management value (here, 3.0) is read out. Then, a Na concentration CNa, and drugs Na / PO ₄ molar ratio, using a target control value "3.0", from the above equation (7), the target control value of the boiler water Na / PO ₄ molar ratio "3 .0 ", the phosphoric acid concentration TCPO ₄ [ppm] in the boiler feed water is calculated (S108). The target phosphoric acid concentration calculator 22 outputs the calculated phosphoric acid concentration TCPO ₄ to the drug concentration calculator 23.

When the phosphoric acid concentration TCPO ₄ is input from the target phosphoric acid concentration calculating unit 22, the chemical concentration calculating unit 23 receives information on the continuous blow amount Brq [L / h] from the memory and the boiler water supply amount WS [L / h]. And information on the ratio PR of phosphoric acid in the low molar ratio drug are read out. Then, using the phosphoric acid concentration TCPO ₄ , the continuous blow amount Brq, the boiler feed water amount WS, and the ratio PR of phosphoric acid in the low molar ratio chemical, the phosphoric acid in the boiler feed water is obtained from the above equation (8). The concentration CDr [ppm] of the molar ratio 2 cleansing agent in the boiler feed water necessary for setting the concentration to the calculated phosphoric acid concentration TCPO ₄ is calculated (S110). The drug concentration calculation unit 23 outputs the calculated molar ratio CDr concentration CDr to the drug injection amount calculation unit 24.

When the concentration CDr of the molar ratio 2 canning agent is input from the drug concentration calculating unit 23, the chemical injection amount calculating unit 24 sets the chemical dilution rate P of the molar ratio 2 canning agent stored in the drug tank 27 from the memory. Information and boiler water supply amount WS information are read out. Then, using the concentration CDr, the chemical dilution rate P, and the boiler feed water WS, it is necessary to set the can water Na / PO ₄ molar ratio in the boiler can water as the target management value from the above equation (9). In addition, the injection amount SDr [mL / h] of the molar ratio 2 cleansing agent is calculated (S112). The chemical injection amount calculation unit 24 outputs the calculated injection amount SDr of the molar ratio 2 cleansing agent to the chemical injection control unit 25.

  When the injection amount SDr is input from the chemical injection amount calculation unit 24, the chemical injection control unit 25 generates a drive signal for driving the electric motor of the injection pump 26 based on the injection amount SDr. This drive signal is a signal for driving the electric motor so as to inject the molar ratio 2 cleansing agent stored in the medicine tank 27 into the boiler can of the boiler apparatus 1 at the injection amount SDr [mL / h]. . The medicinal injection control unit 25 outputs the generated drive signal to the infusion pump 26.

The infusion pump 26 drives the electric motor in accordance with the drive signal from the medicine injection control unit 25 and operates the electric pump. As a result, the molar ratio 2 cleansing agent stored in the medicine tank 27 is inhaled, and the inhaled cleansing agent is injected into the boiler can at an injection amount SDr [mL / h].
As a result, as shown in FIG. 4 (c), the injection amount before the change (injection amount obtained by the above equation (5)) was such that the phosphoric acid concentration was out of the management reference value range. After changing the amount to the above-mentioned SDr, all boilers came within the range of 2.0 to 6.0 which is the control standard value. In addition, the boiler Na / PO ₄ molar ratio of all the boilers was 3.0 or less, which is the management standard value.

As described above, the water quality management device 2 according to the present embodiment uses, as a canning agent, a canning agent (low molarity) in which the chemical Na / PO ₄ molar ratio of the canning agent is lower than the target management value. Specific canning agent). The quality management system 2 of the present embodiment includes a measurement value BTPO ₄ phosphate concentration of the current boiler cans water, the measured value of the current boiler water Na / PO ₄ molar ratio, the low molar HiKiyoshi cans agent The Na concentration CNa in the boiler feed water is calculated based on the chemical Na / PO ₄ molar ratio. Further, based on the chemical Na / PO ₄ molar ratio of the CNa and the low molar ratio cleansing agent and the target control value, phosphorus in the boiler feed water necessary for setting the can water Na / PO ₄ molar ratio as the target control value. The acid concentration TCPO ₄ is calculated. Further, based on the phosphoric acid concentration TCPO ₄ , the continuous blow amount Brq, the boiler feed water amount WS, and the ratio PR of phosphoric acid in the low molar ratio chemical, the phosphoric acid concentration in the boiler feed water is set to TCPO _4. Calculate the concentration CDr of the low molar ratio cleansing agent in the required boiler feed water. Based on the concentration CDr, the chemical dilution rate P, and the boiler feed water WS, the injection of the low molar ratio cleansing agent necessary for setting the can water Na / PO ₄ molar ratio in the boiler can water as the target control value. The amount SDr was calculated.

In this way, the low molar ratio cleansing agent is used, and the injection amount of the low molar ratio cleansing agent is calculated in consideration of the Na concentration in the boiler feed water, so the boiler feed water contains Na. Even in such a case, it is possible to maintain the PH, the phosphoric acid concentration and the can water Na / PO ₄ molar ratio in the boiler can water within the predetermined control reference value range.

Here, the can water component measuring unit 20 and the sodium concentration calculating unit 21 constitute a sodium concentration measuring unit. The target phosphoric acid concentration calculation unit 22, the drug concentration calculation unit 23, and the chemical injection amount calculation unit 24 constitute a chemical injection amount calculation unit. The medicine injection control unit 25 and the injection pump 26 constitute a drug injection unit.
Steps S100 to S106 constitute a sodium concentration measurement step. Steps S108 to S112 constitute a chemical injection amount calculating step. Step S114 constitutes a medicine injection step.

(Modification)
In the above embodiment, the example in which the target management value of the can water Na / PO ₄ molar ratio is set to “3.0” has been described. However, the present invention is not limited thereto, and may be within a predetermined management reference value range. For example, another value may be set.
In the above embodiment, the sodium concentration calculator 21 calculates the Na concentration in the boiler feed water based on the measured value of the phosphoric acid concentration in the boiler can water and the measured value of the Na / PO ₄ molar ratio in the above formula (5). However, the present invention is not limited to this configuration. For example, other configurations such as a configuration in which Na concentration in boiler feed water is directly measured with a sodium concentration meter or the like and a configuration obtained by component analysis of boiler feed water may be employed.

In the above embodiment, although Na / PO ₄ molar ratio as low molar HiKiyoshi cans agent has been described an example of using a Kiyoshikan agent "2" is not limited to this configuration. As long as the molar ratio is lower than the target control value, it is possible to employ a structure in which a different ratio of the canister is used.
In the above embodiment, the boiler water component measurement unit 20, a configuration for measuring the current phosphate concentration and brine Na / PO ₄ molar ratio of the boiler can water automatically, not limited to this configuration. At least a part of these measurements is performed manually, and manually input values of the measurement results are stored in the memory. And the sodium concentration calculation part 21 is good also as another structure, such as setting it as the structure which calculates Na density | concentration in boiler feed water using the information of the measurement result memorize | stored in this memory.

The above embodiments are preferable specific examples of the present invention, and various technically preferable limitations are given. However, the scope of the present invention is described in particular in the above description to limit the present invention. As long as there is no, it is not restricted to these forms. In the drawings used in the above description, for convenience of illustration, the vertical and horizontal scales of members or parts are schematic views different from actual ones.
Further, the present invention is not limited to the above-described 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.

  Next, based on FIGS. 5-6, Example 1 using the chemical injection amount control method similar to the water quality management apparatus 2 of the said embodiment is demonstrated. FIG. 5 is a diagram showing operating conditions of No. 3, No. 4, No. 5, and No. 7 boilers used in the test. 6 (a) to 6 (c) show a case where a low molar ratio cleansing agent is injected with an injection amount SDr obtained by the same chemical injection amount control method as the water quality management device 2 for each boiler used in the test. It is a figure which shows a test result.

In FIG. 5, the water supply amount and the continuous blow amount are measured values in each boiler, and the boiler concentration ratio is obtained by dividing the measured value of the water supply amount in each boiler by the measured value of the continuous boiler amount. Further, current - phosphoric acid concentration of the can in water, currently -Na / PO ₄ molar ratio, phosphoric acid concentration BTPO ₄ of the current boiler can water measured in the boiler water component measurement unit 20 of the embodiment, current can Water Na / PO ₄ molar ratio. Further, the Na / PO ₄ molar ratio in the canning agent is the drug Na / PO ₄ molar ratio of the low molar ratio canning agent in the above embodiment. The low molar HiKiyoshi Kanzai in the Examples, agents Na / PO ₄ molar ratio of Kiyoshikan agent "2.0". Further, in FIG. 5, the target -Na / PO ₄ molar ratio is the target control value of the boiler water Na / PO ₄ molar ratio in the above embodiment. The ratio PR of phosphoric acid in the low molar ratio drug is “0.27 (27 [%])”.

For example, in the case of No. 3 boiler, as shown in FIG. 5, the present condition—the phosphoric acid concentration in the can water is “2.60 [ppm]”, the present condition—the Na / PO ₄ molar ratio is “3.63”, The Na / PO ₄ molar ratio in the can is “2.00”. The molar mass ratio between Na and PO_ {4} is “WPO ₄ /WNa≈4.13”.
Therefore, from the formula (6) of the above embodiment, the Na concentration CNa in the boiler feed water is “CNa = 2.60 × (3.63−2.00) /4.13≈1.026 (1.03) [Ppm] ".

Furthermore, phosphoric acid concentration TCPO ₄ boiler cans water required to the boiler water Na / PO ₄ molar ratio to the target -Na / PO ₄ molar ratio, the equation (7) in the above embodiment, "TCPO ₄ = 1.026 × 4.13 / (3.00−2.00) = 4.24 [ppm] ”.
Still further, the phosphoric acid concentration in the boiler feed water is “TCPO ₄ [ppm] / (WS) in part of the formula (8) of the above embodiment, using the boiler concentration factor 130 [times] of the No. 3 boiler in FIG. / Brq [L / h]) ”,“ 4.24 / 130≈0.0326 [ppm] ”. Then, the phosphoric acid concentration in the boiler feed water divided by the phosphoric acid ratio PR “0.27” contained in the low molar ratio drug is obtained by dividing the phosphoric acid concentration in the boiler can water by TCPO ₄ (phosphorus in the boiler feed water). This is the concentration CDr of the boiler with a molar ratio of 2 in the boiler feed water necessary to make the acid concentration “0.0326 [ppm]”). That is, “CDr = 0.0326 / 0.27≈0.121 [ppm]”.

  As shown in FIG. 5, since the chemical dilution rate P “22 [times]” of the No. 3 boiler and the boiler water supply amount WS “65 [t / h]” are known, these are the moles in the boiler water supply. From the concentration CDr “0.121 [ppm]” of the ratio 2 cleansing agent, the injection amount SDr of the molar ratio 2 cleansing agent is expressed by “SDr = 65 × 0.121 ×” from the formula (9) of the above embodiment. 22≈173 [mL / h] ”.

The No. 4, No. 5 and No. 7 boilers can similarly calculate the injection amount SDr.
As a result of conducting a test for injecting a can with a molar ratio of 2 into each boiler with the injection amount SDr thus calculated, the test results shown in FIGS. 6A to 6C were obtained.
As shown in FIG. 6 (a), the PH of each boiler was higher than when the molar ratio 3 cleansing agent was changed to the molar ratio 2 cleansing agent. A value in a range between a certain 9.0 and a management upper limit of 10.0 was maintained. In FIG. 6A, the horizontal axis indicates the measurement date, and the vertical axis indicates PH.

  In addition, as shown in FIG. 6 (b), the phosphoric acid concentration of each boiler is changed to a molar ratio of 2 cans, especially for No. 3, 4 and 5 boilers. It can be seen that there is a significant increase compared to just doing. All the boilers had values in the range between the management lower limit of 2.0 and the management upper limit of 6.0. In FIG. 6B, the horizontal axis indicates the measurement date, and the vertical axis indicates the phosphoric acid concentration.

Further, as shown in FIG. 6 (c), the boiler water Na / PO ₄ molar ratio of each boiler is significantly larger than that in the case where the molar ratio of 3 cans is changed to the molar ratio of 2 All boilers were below the management standard value of 3.0. In FIG. 6C, the horizontal axis represents the measurement date, and the vertical axis represents the can water Na / PO ₄ molar ratio.
In the test of this example, the Na / PO ₄ molar ratio of the low molar ratio cleansing agent was set to “2.0”, but the cleaning agent of “2.0 to 2.5” may be used. By calculating the injection amount in the same manner as “2.0”, it was confirmed that the PH, phosphoric acid concentration, and Na / PO ₄ molar ratio in the boiler can water could be maintained within the range of the control standard value.

As was found in above embodiment, as Kiyoshikan, agents Na / PO ₄ molar ratio using low molar HiKiyoshi cans agent lower molar ratio than the target control value of the boiler water Na / PO ₄ molar ratio The injection amount of the low molar ratio cleansing agent is calculated by the method of calculating the chemical injection amount using the same formulas (6) to (9) as in the above embodiment. By injecting a low molar ratio cleansing agent into the boiler can at this injection amount, even when Na is contained in the boiler feed water, the PH, phosphoric acid concentration and Na / PO ₄ molar ratio in the boiler can water are reduced. , Can be kept within the range of management reference value.

DESCRIPTION OF SYMBOLS 100 Boiler equipment 1 Boiler apparatus 2 Water quality management apparatus 3 Low pressure turbine 4 Condensation apparatus 5 Pure water apparatus 6 Deaeration apparatus 20 Can water component measurement part 21 Sodium concentration calculation part 22 Target phosphoric acid concentration calculation part 23 Drug concentration calculation part 24 Drug Injection amount calculation unit 25 Chemical injection control unit 26 Infusion pump 27 Drug tank

Claims (4)

A chemical containing sodium and phosphoric acid is injected into boiler can water, which is water existing in the boiler can body, and can water Na / PO ₄ which is a molar ratio of sodium and phosphoric acid contained in the boiler can water. A boiler water quality management method for maintaining the water quality of the boiler can water within a predetermined management reference value by adjusting the molar ratio to a predetermined target management value,
The drug to be injected into the boiler can water is a low molar ratio drug whose drug Na / PO ₄ molar ratio, which is the molar ratio of sodium and phosphoric acid contained in the drug, is lower than the target control value,
A sodium concentration measurement step for measuring the concentration of sodium contained in boiler feed water, which is water supplied into the boiler can body;
Based on the sodium concentration in the boiler feed water measured in the sodium concentration measuring step, the chemical injection amount for calculating the injection amount of the low molar ratio medicine for setting the can water Na / PO ₄ molar ratio as the target management value A calculation step;
A chemical injection step of injecting the low molar ratio chemical into the boiler can water at the injection amount calculated in the chemical injection amount calculating step. In the sodium concentration measurement step, the current measurement value of phosphoric acid concentration BCPO ₄ contained in the boiler can water, the current measurement value of the can water Na / PO ₄ molar ratio, and the low molar ratio drug Based on the chemical Na / PO ₄ molar ratio, the molar mass WNa of sodium, and the molar mass WPO _{4 of} phosphoric acid, the concentration CNa of sodium contained in the water supply is calculated according to the following equation (1). The water quality management method for boiler can water according to claim 1.
CNa = BCPO ₄ × (measured value of can water Na / PO ₄ molar ratio−drug Na / PO ₄ molar ratio) / (WPO ₄ / WNa) (1) The chemical injection amount calculating step includes:
Sodium concentration CNa measured in the sodium concentration measurement step, drug Na / PO ₄ molar ratio of the low molar ratio drug, target control value, molar mass WNa of sodium, and phosphoric acid Based on the molar mass of WPO ₄ , the phosphoric acid concentration TCPO ₄ in the boiler can water necessary for setting the can water Na / PO ₄ molar ratio as the target control value is calculated according to the following formula (2). A first calculation step;
Based on the phosphoric acid concentration TCPO ₄ calculated in the first calculating step, the boiler concentration factor Bem, and the proportion PR of phosphoric acid in the low molar ratio drug, the phosphoric acid concentration according to the following formula (3) A second calculation step of calculating a low molar ratio drug concentration CDr in the boiler feed water corresponding to TCPO ₄ ;
Based on the low molar ratio drug concentration CDr calculated in the second calculation step, the boiler feed water supply amount WS, and the low molar ratio drug dilution rate P, the low molar ratio drug is calculated according to the following formula (4). The boiler water quality management method according to claim 1, further comprising a third calculation step of calculating an injection amount SDr of the molar ratio drug.
TCPO ₄ = CNa × (WPO ₄ / WNa) / (target control value−drug Na / PO ₄ molar ratio) (2)
CDr = (TCPO ₄ / Bem) / PR (3)
SDr = WS × CDr × P (4) A chemical containing sodium and phosphoric acid is injected into boiler can water, which is water existing in the boiler can body, and can water Na / PO ₄ which is a molar ratio of sodium and phosphoric acid contained in the boiler can water. A water quality management device that maintains the water quality of the boiler can water within a range of a predetermined management reference value by adjusting the molar ratio to be a predetermined target management value,
The drug is a low molar ratio drug whose drug Na / PO ₄ molar ratio, which is the molar ratio of sodium and phosphoric acid contained in the drug, is lower than the target control value,
A sodium concentration measuring unit that measures the concentration of sodium contained in boiler feed water that is water supplied to the boiler can body;
Based on the sodium concentration in the boiler feed water measured by the sodium concentration measuring unit, the injection amount of the low molar ratio drug for setting the boiler can water Na / PO ₄ molar ratio as the target control value A medicinal dosage calculation unit to calculate,
A water quality management apparatus comprising: a drug injection unit that injects the low molar ratio drug into the boiler can water with an injection amount calculated by the drug injection amount calculation unit.

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