JP2018204872A - Method and apparatus for determining property and falling of ash adhering to boiler facility - Google Patents

Abstract

To accurately grasp the property and falling possibility of ash adhering to a boiler facility without stopping the operation of a boiler.SOLUTION: A method for determining the property and falling of ash adhering to a boiler facility comprises: a step (S1) of acquiring time-series data of a heat absorbing amount of the boiler facility over a predetermined time; a step (S4) of performing Fourier transformation on the acquired time-series data of the heat absorbing amount; a step (5) of extracting a cycle having high-intensity peak in the time-series data subjected to the Fourier transformation; and a step (S8) of determining that the cycle having the peak is a cycle of ash falling off from the boiler facility.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a ash property / drop-off determination method and an ash property / drop-off determination device attached to boiler equipment.

In a boiler of a thermal power plant that uses coal as fuel, it is known that ash adheres to the surface of boiler facilities such as a superheater, a reheater, a economizer, and a furnace and lowers power generation efficiency. In addition, if the attached ash does not fall off for a long time, the ash becomes a large lump, and when it falls off, a disaster may occur or the furnace bottom may be damaged.
In order to evaluate the impact and risk of ash adhesion on such boiler facilities, it is necessary to grasp the properties of the ash adhering and the ease of dropping off. When evaluating the nature of the attached ash and the ease of dropping off, (1) a method of collecting and evaluating the attached ash after stopping the boiler operation, (2) discharged from the furnace bottom A method for collecting and evaluating ash, (3) A camera installed in the boiler, and a method for evaluating based on images and images captured by the camera, (4) A strain gauge is installed on the suspension pipe of the superheater, (5) A method of evaluating based on the measurement result (for example, refer to Patent Documents 1 and 2), (5) A method for evaluating based on the measurement result ) A method of calculating and evaluating the degree of contamination from the design effective area of the furnace and the current effective area of the furnace (for example, see Patent Document 3) is used.

Japanese Utility Model Publication No. 3-104625 JP-A-9-250708 JP-A-8-75137

  However, in the method (1), it is necessary to stop the operation of the boiler in order to evaluate the properties of ash and the ease of dropping off, resulting in a large economic loss. In the method (2), there is a risk of collecting ash that has fallen several days ago, and it is not possible to accurately grasp the current properties and ease of ash removal. Also, depending on the boiler structure, it may be difficult to collect the bottom ash. In the method (3), only ash existing within the range that can be imaged by the camera can be evaluated. In the method of (4) above, only the weight of the superheater / reheater attached to the suspension pipe can be measured, and it is not possible to measure a portion that is not a suspended structure. In the above method (5), only the amount of adhering ash is estimated, and it is not possible to grasp the properties of ash and the ease of dropping off. In the above method (6), the degree of contamination of the current superheater is merely calculated, and the property of ash and the ease of dropping off are not evaluated.

  Therefore, the present invention has been made in view of the above problems, and it is possible to accurately grasp the properties of ash attached to the boiler equipment and the ease of dropping without stopping the operation of the boiler. It is an object of the present invention to provide a ash property / drop-off determination method and an ash property / drop-off determination device attached to equipment.

  In order to solve the above-mentioned problems, the present invention is a method for determining the properties and dropout of ash adhering to boiler equipment, the step of obtaining time series data of the amount of heat collected from the boiler equipment over a predetermined time, and the obtained amount of collected heat Fourier transforming the time-series data, extracting a period having an intensity peak in the Fourier-transformed time-series data, and determining the period having the peak as a period in which ash drops from the boiler equipment It is characterized by having.

  Further, before the Fourier transform, multiplying the time series data of the amount of heat collected by a window function to align the start and end of the time series data to the same value, and the time series multiplied by the window function It is preferable to have a step of creating a time series data for Fourier transform by connecting a plurality of data.

  The step of extracting the period having the intensity peak includes calculating the difference between the average intensity of the start point and the end point of the predetermined section of the Fourier-transformed time-series data and the maximum intensity in the predetermined section; Preferably, when the calculated intensity difference is greater than or equal to a predetermined value, the maximum intensity is determined as an intensity peak in the Fourier-transformed time series data.

  In order to solve the above-mentioned problems, the present invention is an apparatus for determining the properties and dropout of ash adhering to boiler equipment, a data analysis unit for Fourier-transforming time series data of the amount of heat collected from the boiler equipment over a predetermined time, and the data A peak extraction unit that extracts a cycle having an intensity peak in time-series data Fourier-transformed by the analysis unit, and a cycle having the peak extracted by the peak extraction unit is determined as a cycle in which ash drops from the boiler equipment And a property / drop-off period determination unit.

  In addition, a preprocessing unit that multiplies the time series data of the heat collection amount by a window function to align the start and end of the time series data to the same value, and a plurality of the time series data processed by the preprocessing unit are connected. And an analysis data creation unit for creating time-series data for Fourier transform.

  In addition, the peak extraction unit includes an intensity difference calculation unit that calculates a difference between an average intensity of a start point and an end point of a predetermined section of Fourier-transformed time series data and a maximum intensity in the predetermined section, and the intensity difference calculation And a peak determination unit that determines that the maximum intensity is an intensity peak in the Fourier-transformed time-series data when the difference in intensity calculated by the unit is equal to or greater than a predetermined value.

  According to the present invention, it is possible to accurately grasp the properties of the attached ash and the ease of dropping off without stopping the operation of the boiler.

It is a block diagram of the ash property / drop-off determination device. It is a graph which shows the time series data of the amount of heat collection. (A) is a figure explaining the data when a window function is multiplied with the time series data shown in FIG. 2, (b) is a figure which shows the data which connected the data which multiplied the window function in multiple numbers. . It is a flowchart of the ash property / drop-off determination method. It is the graph which carried out the Fourier-transform of the time series data of FIG.3 (b). (A) depicts an envelope in the graph of FIG. 5, and (b) is a diagram for explaining a peak difference calculation method. (A) is a schematic diagram explaining the state before and after ash dropping off when there is a lot of ash adhering to the boiler equipment, and (b) is before and after ash dropping off when there is little ash adhering to the boiler equipment. It is a schematic diagram explaining the state. (A) is a graph obtained by Fourier transforming the time series data of the amount of heat collected before periodic inspection in the boiler (before cleaning the furnace), and (b) is the time series data of the amount of heat collected after periodic inspection in the boiler. It is the converted graph. It is the graph which carried out the Fourier-transform of the time series data of the amount of heat recovery after several days have passed since stopping the driving | operation of a boiler, and restarting. (A) shows the intensity difference of the peak (first) when the time series data of the amount of heat collected is Fourier transformed before the periodic inspection, the data after the periodic inspection, and the data after the boiler operation is stopped for several days. It is a comparison. (B) compares the intensity difference of a peak (2nd) similarly. (A) is a graph showing the time series data of the amount of heat collected when the amount of heat collected is constant, and (b) is a graph obtained by Fourier transforming the time series data of (a). (A) is a graph showing the time series data of the amount of heat collected when the amount of collected heat gradually decreases, and (b) is a graph obtained by Fourier transforming the time series data of (a).

  A preferred embodiment of the present invention will be described with reference to the drawings. In addition, embodiment shown below is one illustration and can take a various form in the scope of the present invention. The ash property / drop-off determination device is provided, for example, in a boiler control panel of a thermal power plant that uses coal as fuel, and is installed in boiler equipment (eg, superheater, reheater, economizer, furnace, etc.). The ease of dropping off the attached ash, that is, the time interval at which the attached ash falls to the furnace bottom is determined.

<Ashes / dropping judgment device for ash>
As shown in FIG. 1, an ash property / dropout determination device (hereinafter referred to as a property / dropout determination device) 100 includes a data acquisition unit 1, a preprocessing unit 2, an analysis data creation unit 3, and a data analysis unit 4. A peak extraction unit 5, a property / drop-off period determination unit 6, and a storage unit 7.
As shown in FIG. 2, the data acquisition unit 1 acquires time-series data on the amount of heat collected from at least one component of the boiler equipment. The data acquisition unit 1 may acquire time-series data created externally, or the data acquisition unit 1 itself may generate time-series data of the amount of heat collected.
The preprocessing unit 2 multiplies the time series data of the amount of heat collected acquired by the data acquisition unit 1 with a window function as shown in FIG. 3A, and aligns the start and end of the time series data to the same value. .
The analysis data creation unit 3 connects a plurality of time series data processed by the preprocessing unit 2 to create time series data for Fourier transform as shown in FIG.
The data analysis unit 4 performs Fourier transform on the time series data created by the analysis data creation unit 3.

The peak extraction unit 5 extracts a period having an intensity peak in the time series data Fourier-transformed by the data analysis unit 4. Here, the peak extraction unit 5 includes an intensity difference calculation unit 51 and a peak determination unit 52.
The intensity difference calculation unit 51 calculates the difference between the average intensity of the start point and the end point of the predetermined section of the time series data subjected to Fourier transform and the maximum intensity in the predetermined section. When the intensity difference calculated by the intensity difference calculation unit 51 is greater than or equal to a predetermined value, the peak determination unit 52 determines that the maximum intensity is an intensity peak in the time series data subjected to Fourier transform.
The property / drop-off period determination unit 6 determines that the cycle having the peak extracted by the peak extraction unit 5 is a cycle in which ash drops from the boiler equipment.
The storage unit 7 stores various data such as data acquired by the data acquisition unit 1, time series data multiplied by a window function, time series data subjected to Fourier transform, a processing program, and the like.

<Ashes / deletion method of ash>
Hereinafter, the property / drop-off determination method of the ash attached to the heat exchange part of the boiler will be described with reference to the flowchart shown in FIG. In the following embodiment, it is determined whether the ash attached to the superheater is easily removed. In addition to the superheater, as long as it constitutes boiler equipment, the ease of dropping off the ash attached to any constituent part may be determined, and the following method can be applied.
As shown in FIG. 4, the data acquisition unit 1 acquires time-series data of the amount of heat collected by the superheater at a predetermined time set in advance (step S1). Here, the time for acquiring the data and the pitch for acquiring the data can be arbitrarily set. The obtained time series data of the amount of collected heat is shown in a graph as shown in FIG. In addition, the time series data of the amount of heat collected was collected from the period when a single coal type was used with the power generation amount and the burner used being constant.

Next, as shown in FIG. 3A, the pre-processing unit 2 multiplies the acquired time series data of the amount of collected heat by a window function (Hanning function) in which the start and end values are 0, thereby obtaining a time series. The beginning and end of the data are set to 0 (step S2). This is based on the assumption that the limited time series data continues indefinitely, but the next step Fourier transform is performed, but as shown in FIG. When a plurality of series data are connected, the data is not continuous, so the analysis accuracy is lowered. Therefore, in order to improve the analysis accuracy of the data by Fourier transform, the time series data is continuously connected by multiplying the window function by the time series data.
Next, as shown in FIG. 3B, the analysis data creation unit 3 creates a time series data for Fourier transform by connecting a plurality of time series data multiplied by the window function (step S3).

  Next, the data analysis unit 4 performs a Fourier transform on the time series data created in step S3 (step S4). Here, when the ash adhering to the superheater repeatedly adheres and falls off, the magnitude of the intensity can be extracted for each period by Fourier transforming the time series data, and the period with the higher intensity is collected. This is because the change in the amount of heat is large, that is, it can be considered as a cycle in which ash falls off the surface of the superheater. When the time series data shown in FIG. 3B is Fourier transformed, a graph as shown in FIG. 5 is obtained.

Next, the peak extraction unit 5 extracts a period having an intensity peak in the time-series data subjected to Fourier transform (step S5).
In step S5, the peak is extracted by drawing an envelope on the graph shown in FIG. 5, as shown in FIG.
Next, as shown in FIG. 6B, the intensity difference calculation unit 51 calculates the average value of the intensity of the minimum period t1 and the intensity of the maximum period t2 within the predetermined period width, and the maximum value in the section. The difference from the intensity value is calculated (step S6). The peak determination unit 52 determines whether or not the calculated intensity difference is greater than or equal to a predetermined value set in advance (step S7). In step S7, when the peak determination unit 52 determines that the calculated intensity difference is greater than or equal to a predetermined value set in advance (step S7: YES), the peak determination unit 52 determines the maximum intensity value as the intensity value. It determines with a peak and the property and drop-off period determination part 6 determines the period t which has the peak as a period when ash drops from a superheater (step S8). On the other hand, when the peak determination unit 52 determines in step S7 that the calculated difference in intensity is less than a predetermined value set in advance (step S7: NO), the peak determination unit 52 sets the maximum intensity value. The period which has is not determined to be a peak, and the property / drop-off period determination unit 6 does not determine that the ash is dropped from the superheater (step S9). This completes the ash property / drop-off determination.
The presence or absence of a peak has a great meaning in judging the properties of ash, but the peak intensity is considered to have little physical meaning. For example, as shown in FIG. 7A, when the ash A is originally attached to the boiler facility B, when the ash A is dropped, the fluctuation of the heat recovery amount is considered to be small. On the other hand, as shown in FIG. 7B, when the ash A is originally attached to the boiler equipment B in a small amount, it is considered that the fluctuation of the heat recovery amount is large when the ash A is dropped. The peak intensity is expected to vary depending on the initial ash deposition. When the ash properties are hard, it is assumed that the ash removal cycle is slow, and when the ash properties are soft, the ash removal cycle is fast. Therefore, it seems that the period t having a peak varies depending on the properties of ash.
By the above method, it is possible to know the cycle of ash dropping from the superheater, and it is possible to grasp the properties of the ash, such as hardness and softness.

<Verification results>
Next, the verification result about the ash property / dropping determination by the ash property / dropping determination device and the ash property / dropping determination method will be described.
FIG. 8A is a graph obtained by Fourier-transforming time series data of the amount of heat collected before regular inspection (before cleaning the furnace) in the boiler, and FIG. 8B is the amount of heat collected after periodic inspection in the boiler. It is the graph which carried out the Fourier-transform of the time series data.
As can be seen from FIG. 8A, in the graph before the periodic inspection, the period having the intensity peak cannot be confirmed. This is probably because the difference in strength is small, that is, the change in the amount of heat collected is small, and as a cause thereof, a lot of ash adheres to the surface of the superheater and does not fall off.
On the other hand, as can be seen from FIG. 8B, the periods t3 and t3 ′ having intensity peaks can be confirmed in the graph after the periodic inspection. This is because the difference in strength is large, that is, the change in the amount of heat collected is large, and it is considered that the ash attached to the surface of the superheater has fallen off.

FIG. 9 is a graph obtained by Fourier-transforming time series data of the amount of heat collected after several days have passed since the operation of the boiler was stopped and restarted.
As can be seen from FIG. 9, when the boiler is stopped, the superheater expands and contracts due to a heat change, and the attached ash falls off the surface of the superheater. This means that the inside of the furnace is cleaned during periodic inspections, and the inside of the furnace is not cleaned after a few days of stoppage. However, a certain amount of ash falls off the superheater due to expansion and contraction of the superheater. For this reason, it is considered that the change in the amount of collected heat becomes large, and such intensity peaks appear at periods t4 and t4 ′. That is, even if the operation of the boiler is stopped for several days and then restarted, it is considered that a certain effect can be expected.

Fig. 10 compares the intensity difference of the maximum peak when Fourier-transforming the time series data of the amount of heat collected with data before periodic inspection, data after periodic inspection, and data after boiler operation has been stopped for several days. is there. (A) was compared for the first peak intensity difference, and (b) was compared for the second peak intensity difference.
As can be seen from FIG. 10, the strength difference after the periodic inspection and the strength difference after the boiler operation is stopped for several days are larger than the strength difference before the periodic inspection, and the dropout of ash is remarkable. You can see that it appears.

FIG. 11A shows data created on the assumption that the amount of heat collected is constant as a comparative example with respect to FIGS. 3 and 5, and FIG. 11B shows the data shown in FIG. It is the time series data which carried out the Fourier transform of the time series data.
As can be seen from FIG. 11 (b), the time-series data after Fourier transform does not have any intensity peak, and it is considered that no ash is removed.

FIG. 12A shows data created on the assumption that the amount of heat collected gradually decreases as a comparative example with respect to FIGS. 3 and 5, and FIG. ) Time-series data obtained by Fourier transform.
As can be seen from FIG. 12B, the time-series data after Fourier transform does not have any intensity peak, and it is considered that ash is not dropped.

As described above, by performing Fourier transform on the time series data of the amount of heat collected, it is possible to extract a period with a high intensity having a peak. Therefore, by considering this period as a period in which ash drops from the superheater, Without stopping the operation, it is possible to accurately grasp the current ash properties (ease of falling off from the superheater surface) attached to the superheater.
Thereby, the influence and risk evaluation of ash adhesion with respect to boiler equipment can be performed, and the fall of the power generation efficiency by the shutdown of a boiler can be prevented. In addition, it is possible to evaluate the ash that is currently attached to the superheater, not the ash that has fallen to the furnace bottom. In addition, it is possible to ascertain the properties of ash, not the amount of ash, while eliminating the need for equipment such as strain gauges and cameras. For example, using the operation data measured in the boiler management room, Ease of falling off (softness) can be estimated in real time, and it is also possible to control the operation of the boiler by adjusting the amount of additive mixed with coal and the type of coal to be burned according to the properties of ash Become. Moreover, since no camera is used, the observation range of ash is not limited. Moreover, the cleaning time in the boiler can be accurately determined according to the properties of the ash.
In addition, since the time series data is multiplied by the window function before the Fourier transformation of the time series data, continuous time series data can be created, and the accuracy of the Fourier transformation can be further improved.
In addition, when extracting a peak, a peak is determined only when it has an intensity difference greater than a preset value compared to the surrounding data. Instead, the intensity peak can be determined quantitatively.

The present invention is not limited to the above embodiment. For example, it is not always necessary to multiply the acquired time series data by a window function. If multiple time series data are connected, the time series is not multiplied by the window function. Data can be Fourier transformed. Further, the window function is not limited to the Hanning function, and other window functions (Gauss function, Hamming function, Tukey function, Blackman function, etc.) may be used.
Further, when extracting the peak by the intensity difference calculation unit 51, a predetermined value is used when calculating the difference between the average intensity of the start point and the end point of the predetermined section of the Fourier-transformed time series data and the maximum intensity in the predetermined section. The section setting can be changed freely.
Further, when the intensity difference calculated by the intensity difference calculation unit 51 is equal to or greater than a predetermined value, the peak determination unit 52 determines that the maximum intensity is the intensity peak in the time-series data subjected to Fourier transform. Settings can be changed freely.

DESCRIPTION OF SYMBOLS 1 Data acquisition part 2 Pre-processing part 3 Analysis data creation part 4 Data analysis part 5 Peak extraction part 6 Property / drop-off period determination part 7 Storage part 100 Ash property / drop-off determination apparatus

Claims (6)

Obtaining time series data of the amount of heat collected by the boiler equipment over a predetermined time;
Fourier transforming the acquired time series data of the amount of collected heat;
Extracting a period having a peak of intensity in Fourier-transformed time-series data;
Determining a cycle having the peak as a cycle in which ash drops from the boiler facility;
A method for determining the ash property / dropping off of ash attached to boiler equipment. Before the Fourier transform, multiplying the time series data of the amount of heat collected by a window function to align the start and end of the time series data to the same value;
Creating a time series data for Fourier transform by connecting a plurality of the time series data multiplied by the window function;
The ash property / drop-off determination method for ash attached to the boiler equipment according to claim 1, wherein: Extracting a period having the intensity peak,
Calculating the difference between the average intensity of the start point and end point of the predetermined section of the time series data subjected to Fourier transform and the maximum intensity in the predetermined section;
When the calculated intensity difference is equal to or greater than a predetermined value, determining the maximum intensity as an intensity peak in the Fourier-transformed time series data; and
The ash property / drop-off determination method for ash adhering to the boiler equipment according to claim 1 or 2. A data analysis unit that Fourier-transforms time-series data of the amount of heat collected from the boiler equipment over a predetermined period of time;
A peak extraction unit for extracting a period having a peak of intensity in the time series data Fourier-transformed by the data analysis unit;
A property / decrease period determination unit for determining a period having the peak extracted by the peak extraction unit as a period in which ash is removed from the boiler facility;
A ash property / dropping judgment device attached to boiler equipment. A preprocessing unit that multiplies the time series data of the heat collection amount by a window function to align the start and end of the time series data to the same value;
An analysis data creation unit that creates time series data for Fourier transform by connecting a plurality of the time series data processed by the preprocessing unit,
The ash property / drop-off determination device attached to the boiler equipment according to claim 4. The peak extraction unit
An intensity difference calculator that calculates the difference between the average intensity of the start point and end point of the predetermined section of the time series data subjected to Fourier transform and the maximum intensity in the predetermined section;
A peak determination unit that determines the maximum intensity as an intensity peak in the Fourier-transformed time-series data when the intensity difference calculated by the intensity difference calculation unit is equal to or greater than a predetermined value;
The ash property / drop-off determination device attached to the boiler equipment according to claim 4 or 5.

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