JP2018173217A - Air preheater pressure difference rise prediction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air preheater pressure difference rise prediction device capable of surely performing long-term prediction of necessity of maintenance of an air preheater.SOLUTION: An air preheater pressure difference rise prediction device includes a first pressure difference rise prediction portion 11 for predicting a first pressure difference rise by clogging progress prediction in a prediction target month, a second pressure difference rise prediction portion 12 for predicting a second pressure difference rise by gas flow change in accompany with air temperature change in the prediction target month, and a pressure difference prediction portion 13 for predicting pressure difference ΔPof an air preheater in the prediction target month on the basis of the first and second pressure difference rise predicted by the first and second pressure difference rise prediction portions 11, 12. The pressure difference rise prediction portion 11 includes a clogging progress prediction portion 11a for calculating a product of a clogging coefficient a and a predicted leakage ammonia concentration ybefore the prediction target month by one month, and a first pressure difference rise value calculation portion 11b for calculating a first pressure difference rise value by determining the sum of the products obtained by the clogging progress prediction portion 11a by one or several month unit to the prediction target month.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an air preheater differential pressure increase prediction device suitable for monitoring the blockage of an air preheater (AH) used in a boiler ventilation system of a thermal power plant.

  As shown in FIG. 3, a boiler ventilation system 110 of a thermal power plant includes a boiler 111 connected to a generator turbine (not shown), a denitration device 112 connected to the boiler 111, a boiler 111, and a denitration device 112. The connected air preheater 113, the gas / heater heat recovery device 114 connected to the air preheater 113 (hereinafter referred to as “GGH heat recovery device 114”), and the GGH heat recovery device 114 are connected. The electric dust collector (EP) 115, the desulfurizer 117 connected via the electric dust collector 115 and the induction fan (IDF) 116, and the gas / gas heater connected to the desulfurizer 117 A heater 118 (hereinafter referred to as “GGH reheater 118”), a chimney 120 connected to the GGH reheater 118 via a desulfurization ventilator (BUF) 119, and a combustion The air through the air preheater 113 and a forced draft fan (FDF) 121 for feeding the boiler 111.

  The exhaust gas discharged from the boiler 111 is subjected to heat exchange with combustion air supplied to the boiler 111 by the air preheater 113 after nitrogen oxides and the like are removed by the denitration device 112. The exhaust gas whose heat has been recovered by the air preheater 113 is further recovered by the GGH heat recovery device 114 and then sent to the electric dust collector 115. The exhaust gas sent to the electric dust collector 115 is sent to the desulfurization device 117 via the induction fan 116 and detoxified after the dust contained therein is collected. The exhaust gas detoxified by the desulfurization device 117 is reheated by the GGH reheater 118 and then released from the chimney 120 to the atmosphere.

  Here, in order to remove nitrogen oxides contained in the exhaust gas of the boiler 111, ammonia is injected by the denitration device 112. When unreacted ammonia (hereinafter referred to as “leak ammonia”) is generated, sulfur in the exhaust gas is emitted. The oxide reacts to produce acidic ammonium sulfate.

  Since this acidic ammonium sulfate adheres to the heat transfer surface of the air preheater 113 and deposits dust in the exhaust gas, the air preheater 113 is blocked, and the output of the generator must be suppressed to operate. It becomes. Therefore, regular maintenance is required once a year, but the maintenance opportunity is limited to a large-scale inspection period in which the power plant is stopped for several months.

  In order to determine whether or not the air preheater 113 needs to be maintained, it is necessary to predict how much the differential pressure (pressure difference between the exhaust gas inlet and the exhaust gas outlet of the air preheater 113) will increase by the next maintenance opportunity. It becomes.

Therefore, conventionally, how much the differential pressure increases due to a change in the gas flow rate accompanying a change in temperature is calculated, and a decision such as washing with water is made based on the obtained differential pressure.
That is, as shown by the prediction formula (2) in FIG. 2B, the average differential pressure ΔP ₀ [kPa] (hereinafter referred to as “reference monthly average differential pressure ΔP ₀ ”) in the reference month (the month following the maintenance execution month). ) And the average value T ₀ [K] (hereinafter referred to as “reference month gas temperature average value T ₀ ”) of the AH inlet gas temperature and the AH outlet gas temperature in the reference month (hereinafter referred to as “reference month gas temperature average value T ₀ ”). Predicted value T _n [K] of average value of AH inlet gas temperature and AH outlet gas temperature of the month after month (defined as n ≧ 1) (hereinafter, “predicted target gas temperature average value T _n ”) The value divided by (= T ₀ / T _n ) and the predicted value of predicted IDF gas flow rate Q _n [sccm] (hereinafter referred to as “predicted target IDF gas predicted flow rate Q _n ”). ) Is referred to as “reference month IDF gas flow rate Q ₀ ” below the reference month IDF gas flow rate Q ₀ [sccm]. . ) Is used to predict the differential pressure ΔP _n of the prediction target month using a prediction formula represented by the product of the square of the value divided by () (= (Q _n / Q ₀ ) ² ).

  In addition, in the following Patent Document 1, the applicant of the present application discloses an air side differential pressure that is a differential pressure between an air supply port and an air discharge port of an air preheater and an exhaust gas that is a differential pressure between an exhaust gas supply port and an exhaust gas discharge port. The side differential pressure is memorized, the air side differential pressure rise prediction line and the exhaust gas side differential pressure rise prediction line are created using the stored past air side differential pressure and exhaust gas side differential pressure, and the current cross-sectional area of the air preheater is created. And the air preheater management apparatus which judged the necessity of maintenance by calculating the obstruction | occlusion rate of an air preheater based on initial stage cross-sectional area is proposed.

JP 2010-196949 A

  However, the conventional prediction formula (2) focuses only on how much the differential pressure increases due to the change in the gas flow rate due to the temperature change, and does not take into account the clogging progress prediction of the air preheater 113. As shown in FIG. 2 (c), a short-term future (about 3 months) with little progress of clogging can be roughly predicted, but a long-term prediction (about 1 year) has an effect of clogging progress. Large, large deviation from the actual differential pressure (see “Conventional predicted value” indicated by “X” and “Measured value” indicated by “X”), and judgment of necessity of maintenance is not possible because accurate prediction cannot be made. There is a problem in that unnecessary maintenance costs may occur and the generator output cannot be secured.

  An object of the present invention is to provide an air preheater differential pressure increase prediction device and an air preheater management device capable of accurately performing long-term prediction of whether or not maintenance of an air preheater is necessary.

The air preheater differential pressure increase predicting apparatus of the present invention can increase the differential pressure, which is the pressure difference between the exhaust gas inlet and the exhaust gas outlet of the air preheater (113) used in the boiler ventilation system (110), from the reference month. Or an air preheater differential pressure increase prediction device (10) for predicting the blockage of the air preheater in units of several months, wherein the first differential pressure increase due to the clogging progress prediction in the prediction target month A first differential pressure increase prediction unit (11) for prediction, and a second differential pressure increase prediction unit (11) for predicting a second differential pressure increase due to a change in gas flow rate accompanying a change in temperature in the prediction target month ( 12) and the differential pressure (ΔP _n ) of the air preheater in the prediction target month based on the first and second differential pressure increases predicted by the first and second differential pressure increase prediction units. A differential pressure prediction unit (13) for prediction It is characterized in.
Here, a denitration device (112) is provided between the boiler (111) and the air preheater, and the first differential pressure increase prediction unit is configured to determine a predetermined clogging coefficient (a) and the prediction target month. The clogging progress prediction unit (11a) for calculating the product of the predicted leaked ammonia concentration (y _i ) at the outlet of the denitration apparatus one month before the denitration apparatus, and the unit in one or several months until the prediction target month You may provide the 1st differential pressure | voltage rise value calculation part (11b) for calculating | requiring the said 1st differential pressure | voltage rise value by calculating | requiring the sum of the said product calculated | required by the clogging progress prediction part.
An induction ventilator (116) is provided downstream of the air preheater, and the second differential pressure increase prediction unit is an average value of the inlet gas temperature and the outlet gas temperature of the air preheater in the reference month. Gas obtained by dividing the reference monthly gas temperature average value (T ₀ ) by the predicted target month gas temperature predicted average value (T _n ) that is the predicted average value of the inlet gas temperature and the outlet gas temperature of the air preheater in the predicted target month. A gas temperature ratio calculation unit (12a) for calculating a temperature ratio (T ₀ / T _n ), and a prediction target month IDF gas predicted flow rate (Q _n ) that is a predicted gas flow rate of the induction fan in the prediction target month Of the target gas flow rate ((Q _n / Q ₀ ) ² ) that is the square of the value obtained by dividing the gas flow rate by the reference month IDF gas flow rate (Q ₀ ) that is the gas flow rate of the induction fan in the reference month A gas flow ratio calculation unit (12b) for The obtained in the air mean difference standard monthly average differential pressure is pressure of the preheater ([Delta] P ₀₎ and the gas temperature ratio the gas temperature ratio determined by the arithmetic unit in the serial base month and the gas flow ratio calculating section You may provide the 2nd differential pressure | voltage rise value calculation part (12c) for multiplying the prediction object monthly gas flow rate ratio and calculating the said 2nd differential pressure | voltage rise value.
Connected to an external terminal device (20), the clogging coefficient, the predicted leak ammonia concentration, the reference monthly average differential pressure, the reference monthly gas temperature average value, the prediction target monthly gas temperature predicted average value, the reference The monthly IDF gas flow rate and the prediction target month IDF gas predicted flow rate may be input from the terminal device.
The prediction target month may be one month or every several months from the reference month.
The reference month may be a month following a maintenance execution month of the air preheater.
A warning means for comparing the differential pressure predicted by the differential pressure prediction unit with a predetermined maintenance required differential pressure and issuing a warning based on the comparison result may be further provided.

The air preheater differential pressure increase prediction device of the present invention has the following effects.
(1) Long-term prediction of whether or not the air preheater needs to be maintained can be accurately performed.
(2) It is possible to avoid unnecessary maintenance of the air preheater.
(3) Since the necessity of maintenance can be determined at an early stage, a maintenance plan for the air preheater can be made earlier than before.

It is a figure for demonstrating the air preheater differential pressure rise prediction apparatus 10 by one Example of this invention, It is a figure for demonstrating the comparison with the prediction formula of this invention, and the conventional prediction formula, (a) is a figure which shows the prediction formula of this invention, (b) is a figure which shows the conventional prediction formula. (C) is a graph which shows an example of a measured value, a predicted value of the present invention, and a conventional predicted value. It is a figure for demonstrating the boiler ventilation system 110 of a thermal power plant.

  The above objective was realized by predicting the differential pressure of the air preheater in consideration of clogging progress prediction.

Embodiments of an air preheater differential pressure increase prediction apparatus according to the present invention will be described below with reference to the drawings.
The air preheater differential pressure increase prediction apparatus of the present invention is characterized by predicting the differential pressure increase of the air preheater 113 (see FIG. 3) using the prediction formula (1) shown in FIG.

  For this reason, the air preheater differential pressure increase prediction device 10 (hereinafter referred to as “AH differential pressure increase prediction device 10”) according to an embodiment of the present invention, as shown in FIG. Pressure rise prediction units 11 and 12 and a differential pressure prediction unit 13 are provided.

Here, the first differential pressure increase prediction unit 11 includes the clogging coefficient a input from the terminal device 20 connected to the AH differential pressure increase prediction device 10 and the predicted leak ammonia concentration y _i one month before the prediction target month. Based on (i = 0 to n-1), the first differential pressure increase due to the prediction of clogging progress from the month following the reference month to 12 months after the reference month is predicted every month, and clogging progresses A prediction unit 11a and a first differential pressure increase value calculation unit 11b are provided.

The clogging progress prediction 11a is for calculating the product (= ay _i ) of the clogging coefficient a and the predicted leakage ammonia concentration y _i (i = 0 to n−1) one month before the prediction target month.
As shown in the first term of the prediction formula (1) in FIG. 2A, the first differential pressure increase value calculation unit 11b calculates the sum of products obtained by the clogging progress prediction unit 11a up to the prediction target month. This is for calculating the first differential pressure increase value.

The clogging coefficient a has a predetermined value, for example, 0.012 [kPa / ppm].
In addition, as for the predicted leak ammonia concentration y _i in each prediction target month, it has been empirically known that the leak ammonia concentration increases substantially in proportion to the deterioration of the catalyst of the denitration device 112 (see FIG. 3). A value predicted with reference to a graph representing a linear expression of the relationship between the deterioration of the catalyst and the leaked ammonia concentration prepared based on the past data is used.

The second differential pressure rise prediction unit 12 receives the reference monthly average differential pressure ΔP ₀ , the reference month gas temperature average value T ₀ , the prediction target month gas temperature predicted average value T _n , and the reference month IDF gas input from the terminal device 20. Based on the flow rate Q ₀ and the prediction target month IDF gas predicted flow rate Q _n , the second differential pressure increase due to the gas flow rate change due to the temperature change from the month following the reference month to the 12th month after the reference month is performed as in the conventional prediction method. This is for prediction (see prediction formulas (1) and (2) shown in FIGS. 2A and 2B), and the second difference between the gas temperature ratio calculation unit 12a and the gas flow rate ratio calculation unit 12b. And a pressure increase value calculation unit 12c.

The gas temperature ratio calculation unit 12a is for calculating a gas temperature ratio T ₀ / T _n obtained by dividing the reference month gas temperature average value T ₀ by the prediction target month gas temperature predicted average value T _n .
The gas flow rate ratio calculation unit 12b calculates the square of the value obtained by dividing the prediction target month IDF gas predicted flow rate Q _n by the reference month IDF gas flow rate Q ₀ (= (Q _n / Q ₀ ) ² ) (hereinafter “prediction target month”). This is referred to as “gas flow ratio”.
The second differential pressure increase value calculation unit 12c calculates the reference monthly average differential pressure ΔP ₀ , the gas temperature ratio T ₀ / T _n obtained by the gas temperature ratio calculation unit 12a, and the prediction obtained by the gas flow rate calculation unit 12b. This is for calculating the second differential pressure increase value by multiplying the target monthly gas flow rate ratio (= (Q _n / Q ₀ ) ² ).

For the reference monthly average differential pressure ΔP ₀ , the reference month gas temperature average value T _0, and the reference month IDF gas flow rate Q ₀ , values actually measured in the reference month are used.
For the prediction target month gas temperature prediction average value T _n and the prediction target month IDF gas prediction flow rate Q _n , values predicted based on past actual measurement data and the like in the prediction target month are used.

The differential pressure prediction unit 13 adds the first and second differential pressure increase values calculated by the first and second differential pressure increase prediction units 11 and 12, and adds a prediction target month (from the month following the reference month to the reference month). This is for predicting the differential pressure ΔP _n (n = 1 to 12) of the air preheater 113 in each month up to 12 months later.
The differential pressure prediction unit 13 outputs predicted differential pressure data indicating the predicted differential pressure ΔP _n to the terminal device 20.

Thereby, the administrator uses the terminal device 20 as shown in FIG. 2C to set the vertical axis as the differential pressure ΔP _n based on the predicted differential pressure data input from the differential pressure predicting unit 13, and to determine the elapsed months. By creating a graph with the horizontal axis and adding a broken line indicating “maintenance differential pressure” to the created graph, it is possible to easily grasp whether the air preheater 113 needs to be maintained.
In addition, since the AH differential pressure increase prediction device 10 according to the present embodiment takes into account the clogging progress prediction of the air preheater 113, long-term prediction can be performed accurately (in actual values indicated by ◯ and □). It is possible to quickly determine whether or not the air preheater 113 needs to be maintained.

The differential pressure ΔP _n predicted by the differential pressure predicting unit 13 is compared with the maintenance required differential pressure, and a warning unit for issuing a warning based on the comparison result is further provided, for example, FIG. ) When the differential pressure ΔPn 11 months after the reference date is _equal to or higher than the required maintenance differential pressure, a warning “11 months later is the air preheater maintenance time” is issued to the terminal device 20. Also good.

Moreover, although the differential pressure | voltage rise of the air preheater 113 was estimated per month from the reference | standard month, you may estimate per several months.
In the case of prediction in units of m months, the clogging coefficient a is, for example, 0.012 × m [kPa / ppm].

Furthermore, the differential pressure increase of the air preheater 113 may be predicted every day from the reference month, and the differential pressure increase of the air preheater 113 in the prediction target month may be predicted.
In this case, the clogging coefficient a is, for example, 0.0004 [kPa / ppm].

10 AH differential pressure increase prediction device 11 first differential pressure increase prediction unit 11a clogging progress prediction unit 11b first differential pressure increase value calculation unit 12 second differential pressure increase prediction unit 12a gas temperature ratio calculation unit 12b gas flow rate ratio Calculation unit 12c Second differential pressure increase value calculation unit 13 Differential pressure prediction unit 110 Boiler ventilation system 111 Boiler 112 Denitration device 113 Air preheater 114 GGH heat recovery device 115 Electric dust collector 116 Induction ventilator 117 Desulfurization device 118 GGH Reheater 119 Desulfurization ventilator 120 Chimney 121 Push-in ventilator a Clogging factor y _i Prediction leak ammonia concentration ΔP _n differential pressure ΔP ₀ standard monthly average differential pressure T ₀ standard monthly gas temperature average T _n target monthly gas temperature predicted average Value Q ₀ Base month IDF gas flow rate Q _n Forecast target month IDF gas predicted flow rate

Claims (8)

An increase in the differential pressure, which is the pressure difference between the exhaust gas inlet and the exhaust gas outlet of the air preheater (113) used in the boiler ventilation system (110), is predicted in units of one or several months from the reference month, and the air preheater An air preheater differential pressure increase prediction device (10) for monitoring a blockage state,
A first differential pressure increase prediction unit (11) for predicting a first differential pressure increase due to clogging progress prediction in the prediction target month;
A second differential pressure increase prediction unit (12) for predicting a second differential pressure increase due to a gas flow rate change accompanying a temperature change in the prediction target month;
For predicting the differential pressure (ΔP _n ) of the air preheater in the prediction target month based on the first and second differential pressure increases predicted by the first and second differential pressure increase prediction units. A differential pressure prediction unit (13);
An air preheater differential pressure rise prediction apparatus, comprising: A denitration device (112) is provided between the boiler (111) and the air preheater,
The first differential pressure rise prediction unit is
A clogging progress prediction unit (11a) for calculating a product of a predetermined clogging coefficient (a) and a predicted leakage ammonia concentration (y _i ) at the outlet of the denitration device one month before the prediction target month;
A first differential pressure increase value calculation unit for calculating the first differential pressure increase value by calculating the sum of the products determined by the clogging progress prediction unit in units of one or several months until the prediction target month (11b)
The air preheater differential pressure rise prediction apparatus according to claim 1, wherein: An induction fan (116) is provided downstream of the air preheater,
The second differential pressure rise prediction unit
A reference month gas temperature average value (T ₀ ), which is an average value of the inlet gas temperature and the outlet gas temperature of the air preheater in the reference month, is calculated as an inlet gas temperature and an outlet gas temperature of the air preheater in the prediction target month. A gas temperature ratio calculation unit (12a) for calculating a gas temperature ratio (T ₀ / T _n ) divided by a prediction target monthly gas temperature predicted average value (T _n ) that is a predicted average value;
The prediction target month IDF gas predicted flow rate (Q _n ) that is the predicted gas flow rate of the induction fan in the prediction target month is the reference month IDF gas flow rate (Q ₀ ) that is the gas flow rate of the induction fan in the reference month. A gas flow ratio calculation unit (12b) for calculating a prediction target gas flow ratio ((Q _n / Q ₀ ) ² ) that is the square of the divided value;
The reference monthly average differential pressure (ΔP ₀ ), which is the average differential pressure of the air preheater in the reference month, the gas temperature ratio determined by the gas temperature ratio calculation unit, and the gas flow rate ratio calculation unit A second differential pressure increase value calculation unit (12c) for calculating the second differential pressure increase value by multiplying by the prediction target monthly gas flow rate ratio;
The air preheater differential pressure rise prediction apparatus according to claim 1 or 2, characterized in that Connected to an external terminal device (20),
The clogging coefficient, the predicted leak ammonia concentration, the reference monthly average differential pressure, the reference month gas temperature average value, the prediction target month gas temperature predicted average value, the reference month IDF gas flow rate, and the prediction target month IDF gas predicted flow rate Is input from the terminal device,
The air preheater differential pressure rise prediction apparatus according to claim 3, wherein:   5. The air preheater differential pressure increase prediction according to claim 2, wherein a value predicted based on deterioration of the catalyst of the denitration device is used as the predicted leaked ammonia concentration in the prediction target month. apparatus.   6. The air preheater differential pressure increase prediction device according to claim 1, wherein the prediction target month is a month every one month or every several months from the reference month.   The air preheater differential pressure increase prediction device according to any one of claims 1 to 6, wherein the reference month is a month following a maintenance execution month of the air preheater.   The apparatus further comprises warning means for comparing the differential pressure predicted by the differential pressure prediction unit with a predetermined maintenance required differential pressure and issuing a warning based on the comparison result. Item 8. The air preheater differential pressure increase prediction device according to any one of Items 1 to 7.

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