JP5896859B2 - Boiler water silica concentration estimating device, silica concentration adjusting device, silica concentration estimating method, and silica concentration adjusting method - Google Patents

Description

  The present invention relates to a boiler water silica concentration estimating device, a silica concentration adjusting device, a silica concentration estimating method, and a silica concentration for estimating and adjusting the silica concentration of circulating boiler water such as a drum boiler for thermal power generation and a ship boiler. It relates to the adjustment method.

  For example, silica contained in the boiler water of a drum boiler for thermal power generation has a control value because it causes a scale adhering to the inner peripheral surface of the pipe, and is managed so as not to exceed this control value. (For example, refer to Patent Document 1).

  The measurement of the silica concentration of boiler water is performed with respect to the sample water extracted from boiler water using the silica densitometer installed in the sampling rack provided accompanying the boiler. And when the silica concentration of boiler water exceeds predetermined control value, it is adjusted so that the silica concentration of boiler water may be decreased by carrying out blowing of boiler water and supplying pure water.

JP-A-9-126408

  However, the silica densitometer as described above is very expensive and requires periodic reagent replenishment and calibration. Therefore, initial introduction costs and maintenance costs are high, and the cost of boiler operation is high. It has become.

  The present invention has been made in view of such circumstances, and its object is to reduce the initial introduction cost and maintenance cost of a boiler plant having a circulation line that returns steam generated in the boiler to water and returns it to the boiler. An object of the present invention is to provide a silica concentration estimation device, a silica concentration adjustment device, a silica concentration estimation method, and a silica concentration adjustment method.

In order to solve the above problems, the present invention provides the following means.
That is, the boiler water silica concentration estimation apparatus according to the present invention is a boiler water silica concentration estimation apparatus in a boiler plant comprising a boiler and a circulation line that returns steam generated in the boiler to water. A boiler water thermometer that measures the temperature in the boiler, a pressure gauge in the boiler that measures the pressure in the boiler, a first flow meter that measures the boiler feed rate, and a silica concentration storage unit that stores the silica concentration in the boiler water And silica solubility calculating means for calculating silica solubility in steam from the temperature in the boiler and the pressure in the boiler, and the silica concentration stored in the silica concentration storage unit is greater than the silica solubility. Is larger than the silica concentration, the difference between the silica concentration and the silica solubility, the boiler feed rate, and the amount of water held by the boiler. By adding the silica concentration increment is calculated, and updates the silica concentration stored in the silica concentration storage unit.

  According to the said structure, since it is not necessary to install the silica concentration meter for always measuring the silica concentration of boiler water, the initial introduction expense of a boiler plant and a maintenance expense can be reduced.

In the boiler water silica concentration estimation apparatus, the silica solubility calculating means is obtained by regression analysis based on a database storing correlations between silica solubility in steam, pressure in the boiler, and temperature in the boiler. The silica solubility is calculated using a calculation formula.
According to the above configuration, the silica solubility can be calculated more easily.

  A boiler water silica concentration adjusting device according to the present invention includes any one of the above boiler water silica concentration estimating devices, blow means for blowing boiler water from the boiler, and the amount of boiler blow water blown by the blow means. A second flow meter to be measured, a pure water device for supplying water to the circulation line, a silica concentration meter for measuring a silica concentration of feed water that is a silica concentration of pure water supplied from the pure water device, and blowing boiler water A control device, wherein the control device calculates the silica concentration from the silica concentration by the difference between the silica concentration and the feed water silica concentration, the boiler blow water amount, and the total water holding amount of the boiler and the circulation line. The silica concentration stored in the silica concentration storage unit is updated by subtracting the decrease.

  According to the above configuration, the initial introduction cost and maintenance cost of the boiler plant can be reduced, and the silica concentration of the boiler water can be kept below the boiler water blow management value.

  Moreover, the silica concentration estimation method for boiler water according to the present invention is a method for estimating silica concentration in boiler water in a boiler plant comprising a boiler and a circulation line for returning steam generated in the boiler to water. Steam from the step of measuring the temperature in the boiler and the pressure in the boiler, the step of measuring the boiler feed water rate, the step of storing the silica concentration of the boiler water, the temperature in the boiler and the pressure in the boiler Calculating the silica solubility therein, and when the stored silica concentration is greater than the silica solubility, the silica concentration, the difference between the silica concentration and the silica solubility, the boiler feed rate, and the By adding the silica concentration increase calculated by the amount of water held in the boiler, the silica concentration stored in the silica concentration storage unit is calculated. And new to step, characterized in that it comprises a.

  In the method for estimating the silica concentration of boiler water, the silica solubility is calculated by regression analysis based on a database storing the correlation of silica solubility in steam, pressure in the boiler, and temperature in the boiler. Is preferably calculated by

  The boiler water silica concentration adjusting method according to the present invention includes a step of estimating the silica concentration using any one of the above boiler water silica concentration estimation methods, a step of setting a predetermined boiler water blow management value, A step of blowing boiler water when the silica concentration estimated by the silica concentration estimation method is larger than a predetermined boiler water blow management value; a step of measuring an amount of boiler blow water blown from the boiler; and the circulation line The step of supplying water to the water, the step of measuring the silica concentration of the feed water that is the silica concentration of the feed water supplied to the circulation line, and the difference between the silica concentration and the feed silica concentration from the silica concentration, the amount of boiler blow water, and By subtracting the silica concentration decrease calculated by the total water content of the boiler and the circulation line, Characterized in that it comprises a step of updating the silica concentration stored in the density storage unit.

  According to the present invention, since it is not necessary to install a silica concentration meter for constantly measuring the silica concentration of boiler water, the initial introduction cost and maintenance cost of the boiler plant can be reduced.

It is a schematic system diagram of the combined cycle power plant to which the boiler water silica concentration adjusting device of the embodiment of the present invention is applied. It is a flowchart which shows the process sequence by the silica concentration adjustment apparatus of boiler water. It is a graph which shows the correlation of the solubility to saturation and superheated steam of silica, temperature, and pressure.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a schematic system diagram of a combined cycle power plant 2 (boiler plant) to which the silica concentration estimation device 1 and the silica concentration adjustment device 39 of the present embodiment are applied.
As shown in FIG. 1, the combined cycle power plant 2 of the present embodiment is configured to drive the generator 5 with the rotational driving force of the gas turbine 3 and the steam turbine 4 to generate power. An exhaust heat recovery boiler 7 (HRSG, hereinafter referred to as a boiler) is connected to the exhaust outlet of the gas turbine 3.

  The gas turbine 3 includes a compressor 24 that compresses combustion air, a combustor 25 that burns a mixture of compressed high-pressure air and fuel, and supplies high-temperature and high-pressure combustion gas, and a turbine 26. Yes.

  The boiler 7 and the steam turbine 4 are connected by a steam line 10, and steam generated in the boiler 7 is configured to flow into the steam turbine 4 through the steam line 10. The steam turbine 4 is provided with a condenser 12, and the steam after being driven by expansion work by the steam turbine 4 is discharged to the condenser 12 to condense and condense. . The condenser 12 is provided with a hot well 13 for collecting condensate.

The hot well 13 and the boiler 7 are connected by a water supply line 14. On this water supply line 14, a water supply pump 15 and a boiler water supply speed F [m ³ / h] which is a speed of water supply flowing through the water supply line 14 are provided. A first flow meter 22 for measurement is provided.

The boiler 7 is provided with blow means 23 for discharging boiler water. The blow means 23 has a blow line 27 and a blow valve 29 that is provided on the blow line 27 and controls the discharge of the blow water. A blow water amount F _B on the downstream side of the blow valve 29 is provided. A second flow meter 30 for measuring [m ³ / h] is provided. The blow valve 29 can be opened and closed in accordance with a command signal from the control device 9.

  Further, the boiler 7 is provided with a boiler pressure gauge 32 for measuring the pressure P [MPa] in the boiler and a boiler water thermometer 33 for measuring the temperature Tp [° C.] in the boiler. The first flow meter 22, the boiler internal pressure gauge 32, and the boiler water thermometer 33 are connected to the silica concentration update unit 40 of the silica concentration estimation device 1 by, for example, a cable, and an output signal is transmitted to the silica concentration update unit 40. It is configured to be.

  Further, pure water is supplied to the hot well 13 from a pure water device 16 via a pure water supply line 17. The pure water device 16 is a device that generates pure water, and a pure water tank 18 that stores the pure water generated by the pure water device 16 is provided on the pure water supply line 17.

On the pure water supply line 17, between the pure water device 16 and the pure water tank 18, a supply silica concentration S _W [g / m ³ ], which is a silica concentration of pure water supplied from the pure water device 16. The silica concentration meter 20 is provided. The silica concentration meter 20 is connected to the control device 9 by a cable, for example, and is configured to transmit an output signal to the control device 9.

  Further, a water supply valve 21 for controlling the inflow of pure water is provided on the pure water supply line 17 and between the pure water tank 18 and the hot well 13. The water supply valve 21 can be opened and closed in accordance with a command signal from the control device 9.

  A path through which the boiler water circulates again through the boiler 7, the steam turbine 4, the condenser 12 and the boiler 7 by the feed water pump 15 is referred to as a circulation line 34. The boiler 7 of the present embodiment adjusts the silica concentration by blowing the boiler water by the blowing means 23 and replenishing the water lost by the blowing to the circulation line 34 by the water supply means 11.

Boiler water blow for adjusting the silica concentration of the boiler water is carried out by the controller 9 having a silica concentration adjusting device 39, the silica concentration S _B of the boiler water, the silica concentration storage portion 41 of the silica concentration estimating apparatus 1 And is updated by the silica concentration updating unit 40. Further, the silica concentration updating unit 40 includes silica solubility calculating means 42 for calculating the silica solubility S _O [g / m ³ ].
And the control apparatus 9 can refer and update the silica concentration updated by the silica concentration update part 40 and memorize | stored in the silica concentration memory | storage part 41 at any time.

The silica concentration estimation device 1 includes a boiler water thermometer 33, a boiler pressure gauge 32, a first flow meter 22, and a silica concentration update unit 40, and estimates the silica concentration by a process described later. .
Further, the silica concentration update unit 40 includes a silica concentration storage unit 41 and a silica solubility calculation means 42, and the measured values obtained by the boiler water thermometer 33, the boiler pressure gauge 32, and the first flow meter 22 The silica concentration stored in the silica concentration storage unit 41 is updated using the silica solubility calculated by the silica solubility calculating means 42.
In FIG. 1, the silica concentration update unit 40 is illustrated as a device provided separately from the control device 9, but the silica concentration update unit 40 may be incorporated in the control device 9.

  The silica concentration adjusting device 39 is an adjusting device included in the control device 9, and includes the silica concentration estimating device 1, the blow means 23, the second flow meter 30, the pure water device 16, and the silica concentration meter 20. It has and adjusts a silica density | concentration by the process mentioned later.

  Next, the operation of the silica concentration adjusting device 39 of this embodiment will be described. FIG. 2 is a flowchart showing a processing procedure for adjusting the boiler water silica concentration while estimating the boiler water silica concentration. The silica concentration estimation apparatus 1 and the silica concentration adjustment apparatus 39 perform the process of FIG. 2 while the combined cycle power plant 2 is operating.

First, a fixed value is input to the storage unit of the control device 9 by the operator (fixed value input step S1). In the fixed value input step S < _b > 1, the boiler retained water amount V _B [m ³ ] and the retained water amount V _P [m ³ ] other than the boiler are input to a predetermined storage unit of the control device 9 by the operator. These boilers held water volume _{V B,} and held water volume _{V P} of the non-boiler is design value, these sum to fleet water in the circulation line _{34 (V B + V P)} [m 3].

Further, as the calculation frequency of the silica concentration S _B by the operator, the calculation time interval [Delta] T [h] is input to the storage unit of the control device 9. That is, the estimation processing or adjustment process silica concentration S _B is performed for each [Delta] T. The operator is determined by a regression calculation to be described later, to determine the coefficients of the equations necessary to calculate the silica solubility S _O into steam.

Further, the boiler water blow management value S _C [g / m ³ ] is input to the storage unit of the control device 9 by the operator. The boiler water blow control value _{S C} is a numerical value which is determined in JIS B 8223 "quality of feed water and boiler water of the boiler water (2006)."

Here, a method of creating a calculation formula for silica solubility S 2 _O in steam will be described.
The calculation formula of the silica solubility S _O into steam, boiler water temperature Tp, from boiler pressure P, a calculation formula for calculating the silica solubility S _O, the saturated superheated steam silica shown in FIG. 3 A graph of the solubility of water, that is, a correlation between silica solubility in steam, pressure in the boiler, and temperature in the boiler is created based on a stored database.

The calculation formula uses regression analysis,
S _O = a + b × Tp + c × P
It is expressed by a multiple regression equation of the form In this multiple regression equation, the boiler water temperature Tp and the boiler internal pressure P are explanatory variables, and the silica solubility _S0 is an objective variable (dependent variable).
The coefficients a and b can be obtained by a predetermined regression analysis tool.
In the present embodiment, regression analysis was performed using the analysis data of 7 points shown in the following table from the graph of the solubility of silica in saturated / superheated steam shown in FIG.

By the regression analysis, the calculation formula of the silica solubility S _O corresponding to the graph of FIG. 3 is shown in the following calculation formula (1).
S _O = −14.318 + 0.0177798 × Tp + 1.3912 × P
(1)

Next, the operator sets an initial value S _B0 [g / m ³ ] of silica concentration in the boiler water (silica concentration initial value setting step S2). Here, the silica concentration of boiler water is measured by manual analysis, and this analysis value is set as the initial value S _B0 of the silica concentration in boiler water.

Next, the control device 9 sets the silica concentration S _{B of} the boiler water and the silica concentration Si [g / m ³ ] of the boiler feed water, and this value is stored in the silica concentration storage unit 41 of the silica concentration update unit 40. (Silica concentration setting step S3). Here, the initial value S _B0 boiler water silica concentration is set at a fixed value input step S1 is set as a boiler water silica concentration S _B and boiler feed water in the silica concentration Si.
And the silica concentration estimation apparatus 1 acquires the measured value of the boiler water temperature Tp and the boiler internal pressure P (temperature pressure acquisition process S4).

Next, the silica concentration estimating apparatus 1 calculates the silica solubility S 2 _O using the silica solubility calculating means 42 (silica solubility calculating step S5). That is, the silica solubility _SO is calculated by inputting the boiler water temperature Tp and the boiler pressure P acquired in the temperature / pressure acquisition step S4 into the calculation formula (1).

Next, the silica concentration estimating apparatus 1 compares the value of the silica solubility S _O calculated in silica solubility calculating step S5, the silica concentration S _B stored in the silica concentration storage unit 41 in the silica concentration setting process S3 (Silica solubility comparison step S6).

Here, if the silica solubility S _O to the steam is greater than the silica concentration S _B, since the silica concentration S _B of the boiler water does not change, integration of the silica concentration S _B of the boiler water is not performed.
Accordingly, the silica concentration S _B and the boiler feed water silica concentration Si are not changed, and it is determined whether or not to end the calculation in the calculation end determination step S14, and is normally set in the fixed value input step S1. After waiting until the calculation time interval ΔT [h] elapses, the process returns to the temperature / pressure acquisition step S4. The silica concentration estimating apparatus 1 acquires the boiler water temperature Tp and the boiler internal pressure P, to recalculate the silica solubility S _O.

On the other hand, if the silica solubility S _O is equal to or less than the concentration of silica S _B, since the silica silica vapor has not been dissolved remain in the boiler water, so that the silica concentration S _B of the boiler water is increased. That is, it is necessary to correct the silica concentration S _B.

Silica concentration adjusting device 39, as a preliminary step of correcting the silica concentration S _B of boiler water, to calculate the concentration of silica increment ^{_{ΔS B [g / m 3]}} ( the silica concentration increase calculation step S7). Silica concentration increment [Delta] S _B is calculated by the following equation (2).

Then, the silica concentration adjusting device 39, based on the silica concentration increment [Delta] S _B calculated in silica concentration increase calculation step S7, the calculated silica concentrations S _B of the boiler water. That is, the value obtained by adding the silica concentration increment [Delta] S _B to the silica concentration S _B, compared with Boiraburo control value S _C (Boiraburo control value comparing step S8).

Here, silica concentration S _B of the boiler water is the case was less than Boiraburo control value S _C, the boiler water silica concentration S _B,
S _B = S _B + ΔS _B
And the boiler feed water silica concentration Si,
S _i = S _O
And Then, it is determined whether or not to end the calculation in the calculation end determination step S14 described later. Usually, after waiting until the calculation time interval ΔT elapses, the process returns to the temperature and pressure acquisition step S4, and the silica solubility calculating means. 42 obtains the boiler water temperature Tp and the boiler internal pressure P, to recalculate the silica solubility S _O.

Then, the silica concentration adjusting device 39, the silica concentration S _B of the boiler water, to implement Boiraburo if larger than Boiraburo management value S _C (Boiraburo exemplary step S9). The silica concentration adjusting device 39 acquires the amount F _B [m ³ / h] of blow water discharged by boiler blowing using the second flow meter 30 (boiler blow water amount measurement step S10).
Then, the hot well level meter 43 detects a decrease in hot well water level due to boiler blow, and pure water equal to the blow water amount is supplied from the pure water device 16 by level control.

That is, the boiler water silica concentration S _B is, if exceeded Boiraburo control value S _C, the boiler water is diluted by the pure water is fed into the circulation line 34 with the boiler water is discharged, the boiler water silica concentration S _B is configured to hold the following values Boiraburo management value S _C.

Since the decrease the concentration of the silica concentration S _B by supplementation Boiraburo and pure water, the silica concentration adjusting device 39 performs recalculation of the silica concentration S _B (the silica concentration recalculation step S11).
Here, silica concentration decrease [Delta] S _B is calculated by the following equation (3).

That is, the silica concentration S _B after blowing is recalculated by the following equation (4).

Moreover, since the boiler feedwater silica concentration Si can be regarded as equal to the silica concentration S _B,
Si = S _B
(Boiler feed water silica concentration setting step S12).

  In the silica concentration recalculation step S <b> 11, instead of recalculating the silica concentration, the silica concentration may be acquired by manual analysis and input to the silica concentration estimation apparatus 1.

  Then, in the calculation end determination step S13, it is determined whether to end the calculation. Normally, when the operation of the boiler 7 is continued, the process returns to the temperature and pressure acquisition step S4 after waiting until the calculation time interval ΔT elapses without ending the calculation.

Next, the operation of the boiler water silica concentration adjusting device 39 of the above embodiment will be described.
It activates the combined cycle power generation plant 2, a predetermined stage during the boiler water operation, the operator, the silica concentration S _B of boiler water obtained by manual analysis, input to the storage unit of the control device 9.

Silica concentration estimating apparatus 1 compares the silica concentration S _B and silica solubility S _O, if the silica concentration S _B falls below the silica solubility S _O holds without changing the stored value of silica concentration S _B .
On the other hand, the silica concentration adjusting device 39, when the silica concentration S _B is greater than the silica solubility S _O corrects silica concentration S _B by the silica concentration S _B integrating the silica concentration increment [Delta] S _B. Then, the silica concentration adjusting device 39 compares the corrected silica concentration S _B and boiler water blow control value S _C, if the silica concentration S _B is greater than the boiler water blow control value S _C is blown and Make water supply. If carrying out the blow, according to equation (4), and resets the initial value of silica concentration S _B.

According to the embodiment, since the silica concentration S _B of the boiler water is calculated boiler water temperature Tp, silica solubility S _O calculated by the boiler internal pressure _P, and the boiler feed rate F, the silica concentration of the boiler water there is no need to provide a silica concentration meter 20 for measuring the S _B. That is, it is possible to estimate the concentration of silica S _B only existing equipment. Thereby, the initial cost for installing the silica concentration meter 20 and the maintenance cost such as the cost for measuring the silica concentration using the silica concentration meter 20 can be reduced.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, in the embodiment described above, the silica concentration estimating device 1 and the silica concentration adjusting device are applied to the combined cycle power plant 2. However, the silica concentration estimating device 1 and the silica concentration adjusting device may be applied to a thermal power plant in which the gas turbine 3 is omitted. However, the present invention may be applied to a marine boiler.

DESCRIPTION OF SYMBOLS 1 ... Silica density | concentration estimation apparatus 2 ... Combined cycle power plant 7 ... Boiler 9 ... Control apparatus 11 ... Water supply means 12 ... Condenser 14 ... Water supply line 16 ... Pure water apparatus 17 ... Pure water supply line 18 ... Pure water tank 20 ... Silica concentration meter 21 ... Water supply valve 22 ... First flow meter 23 ... Blow means 27 ... Blow line 29 ... Blow valve 30 ... Second flow meter 32 ... Boiler pressure gauge 33 ... Boiler water thermometer 34 ... Circulation line 39 ... Silica Concentration adjusting device 41 ... Silica concentration storage unit 42 ... Silica solubility calculating means 43 ... Hot well level meter

Claims (6)

In a boiler water silica concentration estimating device in a boiler plant comprising a boiler and a circulation line for returning steam generated in the boiler to water.
A boiler water thermometer for measuring the temperature in the boiler;
A pressure gauge in the boiler that measures the pressure in the boiler;
A first flow meter for measuring the boiler feed rate;
A silica concentration storage unit for storing the silica concentration of boiler water;
Silica solubility calculating means for calculating silica solubility in steam from the temperature in the boiler and the pressure in the boiler, and
When the silica concentration stored in the silica concentration storage unit is greater than the silica solubility, the silica concentration depends on the difference between the silica concentration and the silica solubility, the boiler feed rate, and the amount of water retained in the boiler. A silica concentration estimation apparatus for boiler water, wherein the silica concentration stored in the silica concentration storage unit is updated by adding the calculated silica concentration increase.   The silica solubility calculating means calculates silica solubility using a calculation formula obtained by regression analysis based on a database storing correlations between silica solubility in steam, pressure in the boiler, and temperature in the boiler. The boiler water silica concentration estimating apparatus according to claim 1, wherein The boiler water silica concentration estimating device according to claim 1 or 2,
Blow means for blowing boiler water from the boiler;
A second flow meter for measuring the amount of boiler blow water blown by the blowing means;
A pure water device for supplying water to the circulation line;
A silica concentration meter for measuring a silica concentration of feed water that is a silica concentration of pure water supplied from the pure water device;
A control device for blowing boiler water,
The control device subtracts from the silica concentration a difference between the silica concentration and the feed water silica concentration, the amount of boiler blow water, and a decrease in silica concentration calculated by the total amount of water held in the boiler and the circulation line. The silica concentration adjusting device for boiler water, wherein the silica concentration stored in the silica concentration storage unit is updated. In a boiler water silica concentration estimation method in a boiler plant comprising a boiler and a circulation line for returning steam generated in the boiler to water and returning to the boiler,
Measuring the temperature in the boiler and the pressure in the boiler;
Measuring the boiler feed rate,
Memorizing the silica concentration of boiler water;
Calculating silica solubility in steam from the temperature in the boiler and the pressure in the boiler;
When the stored silica concentration is greater than the silica solubility, the silica concentration is calculated by the difference between the silica concentration and the silica solubility, the boiler feed rate, and the amount of water retained in the boiler. A method for estimating the silica concentration of boiler water, comprising: adding a minute to update a stored silica concentration.   The silica solubility is calculated by a calculation formula obtained by regression analysis based on a database storing correlations between silica solubility in steam, pressure in the boiler, and temperature in the boiler. Item 5. The method for estimating the silica concentration of boiler water according to Item 4. A step of estimating the silica concentration using the boiler water silica concentration estimation method according to claim 4 or 5,
Setting a predetermined boiler water blow management value;
Blowing the boiler water when the silica concentration estimated by the silica concentration estimating method is larger than a predetermined boiler water blow management value;
Measuring the amount of boiler blow water blown from the boiler;
Supplying water to the circulation line;
Measuring a feed water silica concentration which is a silica concentration of feed water supplied to the circulation line;
The silica concentration memory is obtained by subtracting from the silica concentration a difference between the silica concentration and the feed water silica concentration, the boiler blow water amount, and a silica concentration decrease calculated by the total retained water amount of the boiler and the circulation line. And a step of updating the silica concentration stored in the section.

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