JP6926689B2 - Method for determining the property / dropout of ash adhering to boiler equipment and device for determining the property / dropout of ash - Google Patents

Description

The present invention relates to a method for determining the property / dropout of ash adhering to boiler equipment and a device for determining the property / dropout of ash.

It is known that ash adheres to the surface of boiler equipment such as superheaters, reheaters, economizers, and furnaces in the boilers of coal-fueled thermal power plants, reducing power generation efficiency. In addition, if the adhering ash elapses for a long time without falling off, the ash becomes a large lump, and when it falls off after that, a disaster may occur or the furnace bottom may be damaged.
In order to evaluate the impact of ash adhesion and risk assessment on such boiler equipment, it is necessary to understand the properties of the attached ash and the ease with which it can fall off. When evaluating the properties of the attached ash and the ease with which it falls off, (1) a method of stopping the operation of the boiler and collecting and evaluating the attached ash, and (2) discharging from the bottom of the furnace. A method of collecting ash and evaluating it, (3) installing a camera in the boiler and evaluating based on the images and images taken by the camera, (4) installing a strain gauge on the suspension pipe of the superheater, A method of evaluation based on the detected strain amount, (5) a method of installing a temperature or heat measuring device in a boiler and evaluating based on the measurement result (see, for example, Patent Documents 1 and 2), (6). ) A method of calculating and evaluating the degree of contamination from the area of the effective furnace in design and the area of the current effective furnace (see, for example, Patent Document 3) is used.

Jikkenhei 3-104625 Japanese Unexamined Patent Publication No. 9-250708 Japanese Unexamined Patent Publication No. 8-75137

However, in the method (1) above, it is necessary to stop the operation of the boiler in order to evaluate the properties of the ash and the easiness of falling off, which causes a large economic loss. With the method (2) above, there is a risk that the ash that has fallen off several days ago may be collected, and it is not possible to accurately grasp the current properties of the ash and the ease with which it falls off. In addition, depending on the structure of the boiler, it may be difficult to collect ash from the bottom of the furnace. With the method (3) above, only the ash existing within the range that can be imaged by the camera can be evaluated. With the method (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 part that is not a suspension structure. The method (5) above only estimates the amount of attached ash, and cannot grasp the properties of the ash and the ease with which it falls off. The method (6) above only calculates the degree of contamination of the current superheater, and does not evaluate the properties of the ash and the ease with which it falls off.

Therefore, the present invention has been made in view of the above problems, and it is possible to accurately grasp the properties of the ash adhering to the boiler equipment and the easiness of falling off without stopping the operation of the boiler. It is an object of the present invention to provide a method for determining the property / dropout of ash adhering to equipment and a device for determining the property / dropout of ash.

In order to solve the above problems, the present invention is a method for determining the properties and shedding of ash adhering to the boiler equipment, in which a step of acquiring time-series data of the heat collection amount of the boiler equipment over a predetermined time and the acquired heat collection amount are obtained. Steps of Fourier transforming the time-series data of And, characterized by having.

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

Further, the step of extracting the period having the peak of the intensity includes the step of calculating the difference between the average of the intensities 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. When the difference in the calculated intensities is equal to or greater than a predetermined value, it is preferable to have a step of determining the maximum intensity as the peak of the intensity in the Fourier transformed time series data.

In order to solve the above problems, the present invention is a data analysis unit for determining the properties and shedding of ash adhering to the boiler equipment, and a data analysis unit that Fourier-converts the time-series data of the heat collection amount of the boiler equipment over a predetermined time, and the data. The peak extraction unit that extracts the period having the intensity peak in the time series data Fourier transformed by the analysis unit and the period having the peak extracted by the peak extraction unit are determined to be the period in which the ash falls off from the boiler equipment. It is characterized in that it is provided with a property / dropout cycle determination unit.

Further, 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 with the same value, and a plurality of the time series data processed by the preprocessing unit are connected. It is preferable to provide an analysis data creation unit for creating time series data for Fourier transform.

Further, the peak extraction unit includes an intensity difference calculation unit that calculates the difference between the average of the intensities 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, and the intensity difference calculation unit. It is preferable to include a peak determination unit for determining the maximum intensity as the peak of the intensity 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 easiness of falling off without stopping the operation of the boiler.

It is a block diagram of the property / dropout determination device of ash. It is a graph which shows the time series data of the amount of heat collection. (A) is a diagram for explaining data when the time series data shown in FIG. 2 is multiplied by a window function, and (b) is a diagram showing data obtained by connecting a plurality of data obtained by multiplying the time series data shown in FIG. .. It is a flowchart of the property / dropout determination method of ash. It is a graph which Fourier transformed the time series data of FIG. 3 (b). (A) is a graph in which an envelope is drawn in FIG. 5, and (b) is a diagram for explaining a method of calculating a peak difference. (A) is a schematic diagram for explaining the state before and after the ash falls off when there is a large amount of ash adhering to the boiler equipment, and (b) is a schematic diagram explaining the state before and after the ash falls off when there is little ash adhering to the boiler equipment. It is a schematic diagram explaining the state of. (A) is a graph obtained by Fourier transforming the time-series data of the heat collection amount before the periodic inspection in the boiler (before cleaning the inside of the furnace), and (b) is a Fourier transform of the time-series data of the heat collection amount after the periodic inspection in the boiler. It is a converted graph. This is a graph obtained by Fourier transforming the time-series data of the amount of heat collected after several days have passed since the operation of the boiler was stopped and restarted. (A) shows the intensity difference of the peak (first) when the time series data of the amount of heat collected is Fourier transformed, the data 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) is a comparison of the intensity differences of the peak (second) in the same manner. (A) is a graph showing the time series data of the heat collection amount when the heat collection amount 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 heat collection amount when the heat collection amount 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. The embodiment shown below is an example, and various forms can be taken within the scope of the present invention. An ash property / dropout determination device is provided, for example, in the control panel of a boiler of a thermal power plant that uses coal as fuel, and is used in boiler equipment (for example, a superheater, a reheater, an economizer, a furnace, etc.). It determines the ease with which the attached ash falls off, that is, how often the attached ash falls to the bottom of the furnace.

<Ashes property / dropout judgment device>
As shown in FIG. 1, the ash property / dropout determination device (hereinafter referred to as 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 / dropout cycle determination unit 6, and a storage unit 7 are provided.
As shown in FIG. 2, the data acquisition unit 1 acquires time-series data of the amount of heat collected in at least one component of the boiler equipment. The data acquisition unit 1 may acquire externally created time-series data, or the data acquisition unit 1 itself may create time-series data of the amount of heat collected.
The preprocessing unit 2 multiplies the time-series data of the amount of heat collected by the data acquisition unit 1 by a window function as shown in FIG. 3A to align the start and end of the time-series data with 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. 3 (b).
The data analysis unit 4 Fourier transforms 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 of the intensities 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. 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 peak of the intensity in the Fourier-transformed time series data.
The property / dropout cycle determination unit 6 determines that the cycle having the peak extracted by the peak extraction unit 5 is the cycle in which the ash falls off 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 obtained by Fourier transform, a processing program, and the like.

<Method of determining ash properties / dropout>
Hereinafter, a method for determining the properties and shedding of ash adhering to the heat exchange portion of the boiler will be described with reference to the flowchart shown in FIG. In the following form, the ease with which the ash adhering to the superheater falls off is determined. Further, the easiness of ash adhering to any component portion may be determined as long as it constitutes a boiler facility, not limited to a superheater, 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 time series data of the acquired heat collection amount is shown in FIG. 2 in a graph. 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 amount of power generation and the burner used constant.

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

Next, the data analysis unit 4 Fourier transforms 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 cycle by Fourier transforming the time series data, and the larger the cycle, the more the ash is collected. This is because the change in calorific value is large, that is, it can be considered as a cycle in which ash falls off from 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 Fourier-transformed time-series data (step S5).
In step S5, the extraction of the peak draws an envelope on the graph shown in FIG. 5, as shown in FIG. 6 (a).
Next, as shown in FIG. 6B, the intensity difference calculation unit 51 has the average value of the intensity of the minimum period t1 and the intensity of the maximum period t2 within a 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 difference in intensity is equal to or greater than a preset predetermined value (step S7). In step S7, when the peak determination unit 52 determines that the calculated difference in intensity is equal to or greater than a preset predetermined value (step S7: YES), the peak determination unit 52 determines the maximum intensity value of the intensity. The peak is determined, and the property / dropout cycle determination unit 6 determines the cycle t having the peak as the cycle in which the ash falls off from the superheater (step S8). On the other hand, in step S7, when the peak determination unit 52 determines that the calculated intensity difference is less than a preset predetermined value (step S7: NO), the peak determination unit 52 determines the maximum intensity value. The period of possession is not determined to be the peak, and the property / dropout cycle determination unit 6 does not determine the cycle of ash falling off from the superheater (step S9). This completes the determination of ash properties and shedding.
The presence or absence of a peak has a great significance in determining the properties of ash, but the peak intensity is considered to have little physical meaning. For example, as shown in FIG. 7A, when a large amount of ash A is originally attached to the boiler equipment B, it is considered that the fluctuation of the heat collection amount is small when the ash A falls off. On the other hand, as shown in FIG. 7B, when the ash A originally adheres to the boiler equipment B in a small amount, it is considered that the amount of heat collected fluctuates greatly when the ash A falls off. The peak intensity is expected to vary depending on the amount of initial ash adhered. When the ash is hard, the ash shedding cycle is slow, and when the ash is soft, the ash shedding cycle is fast. Therefore, the period t having a peak seems to fluctuate depending on the properties of the ash.
By the above method, the cycle in which the ash falls off from the superheater can be known, and the properties such as hardness and softness of the ash can be grasped.

<Verification result>
Next, the verification results of the ash property / dropout determination device by the ash property / dropout determination device and the ash property / dropout determination method will be described.
FIG. 8A is a Fourier transform graph of the time-series data of the amount of heat collected before the periodic inspection in the boiler (before cleaning the inside of the furnace), and FIG. 8B is the amount of heat collected after the periodic inspection in the boiler. It is a graph obtained by Fourier transforming the time series data of.
As can be seen from FIG. 8A, the period having the intensity peak cannot be confirmed in the graph before the periodic inspection. It is considered that this is because the difference in strength is small, that is, the change in the amount of heat collected is small, and the cause is that a large amount 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, in the graph after the periodic inspection, the periods t3 and t3'having the intensity peak can be confirmed. It is considered that this is because the difference in strength is large, that is, the change in the amount of heat collected is large, and the cause is that the ash adhering to the surface of the superheater has fallen off.

FIG. 9 is a graph obtained by Fourier transforming the 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 the heat change, and the attached ash falls off from the surface of the superheater. This is because the inside of the furnace is cleaned during regular inspections, and the inside of the furnace is not cleaned when it is stopped for several days, but some ash falls off from the superheater due to the expansion and contraction of the superheater. Therefore, it is considered that the change in the amount of heat collection becomes large and such a peak of intensity appears in the cycles t4 and t4'. That is, it is considered that a certain effect can be expected even when the operation of the boiler is stopped for several days and then restarted.

FIG. 10 compares the intensity difference of the maximum peak when the time series data of the heat collection amount is Fourier transformed with the data before the periodic inspection, the data after the periodic inspection, and the data after the boiler operation is stopped for several days. be. (A) was compared with respect to the first peak intensity difference, and (b) was compared with respect to the second peak intensity difference.
As can be seen from FIG. 10, the strength difference after the periodic inspection and the strength difference after stopping the operation of the boiler for several days are larger than the strength difference before the periodic inspection, and the ash fall off is remarkable. You can see that it appears.

FIG. 11 (a) 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. 11 (b) shows FIG. 11 (a). It is the time series data obtained by Fourier transforming the time series data of.
As can be seen from FIG. 11B, it is considered that there is no intensity peak in the time series data after the Fourier transform and there is no ash shedding.

FIG. 12 (a) 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. 12 (b) shows FIG. 12 (a). ) Is a time-series data obtained by Fourier transforming the time-series data.
As can be seen from FIG. 12B, it is considered that the time series data after the Fourier transform has no intensity peak and no ash shedding.

As described above, by Fourier transforming the time-series data of the amount of heat collection, it is possible to extract a period with a large intensity with a peak. Therefore, by considering this period as the period in which the ash falls off the superheater, the boiler It is possible to accurately grasp the properties of the current ash adhering to the superheater (easiness of falling off from the surface of the superheater) without stopping the operation of the superheater.
As a result, it is possible to evaluate the influence of ash adhesion on the boiler equipment and the risk, and it is possible to prevent a decrease in power generation efficiency due to the shutdown of the boiler. In addition, it will be possible to evaluate the ash currently attached to the superheater instead of the ash that has fallen to the bottom of the furnace. In addition, since it is possible to grasp the properties of ash rather than the amount of ash adhering without the need for equipment such as strain gauges and cameras, for example, the operation data measured in the boiler control room can be used to determine the ash. It is possible to estimate the ease of falling off (softness) in real time, and it is also possible to control the operation of the boiler by adjusting the amount of additives to be mixed with coal and the type of coal to be burned according to the properties of the ash. Become. Moreover, since the camera is not used, the ash observation range is not limited. In addition, the timing of cleaning the inside of the boiler can be accurately determined according to the properties of the ash.
Further, since the time series data is multiplied by the window function before the Fourier transform of the time series data, continuous time series data can be created and the accuracy of the Fourier transform can be further improved.
In addition, when extracting the peak, the peak is determined only when the intensity difference is larger than the preset value compared to the surrounding data, so that the person qualitatively determines the intensity peak by looking at the graph. Instead of doing so, the intensity peak can be determined quantitatively.

The present invention is not limited to the above-described embodiment. For example, it is not always necessary to multiply the acquired time series data by the window function, and if the time series data is continuous when multiple time series data are connected, the time series is not multiplied by the window function. The data can be Fourier transformed. Further, the window function is not limited to the Hanning function, and other window functions (Gaussian function, Humming function, Tukey function, Blackman function, etc.) may be used.
Further, when extracting the peak by the intensity difference calculation unit 51, 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 is determined. The section setting can be changed freely.
Further, when the difference in intensity 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 peak of the intensity in the time series data obtained by Fourier transform. The settings can be changed freely.

1 Data acquisition unit 2 Preprocessing unit 3 Analysis data creation unit 4 Data analysis unit 5 Peak extraction unit 6 Property / dropout cycle judgment unit 7 Storage unit 100 Ash property / dropout judgment device

Claims (6)

Steps to acquire time-series data of heat collection amount of boiler equipment over a predetermined time,
A step of Fourier transforming the acquired time-series data of the amount of heat collection,
Steps to extract the period with the intensity peak in the Fourier transformed time series data,
The step of determining the cycle having the peak as the cycle in which the ash falls off from the boiler equipment, and
A method for determining the properties and shedding of ash adhering to boiler equipment, which is characterized by having. Before performing the Fourier transform, a step of multiplying the time-series data of the heat collection amount by a window function to align the start and end of the time-series data with the same value.
A step of creating time series data for Fourier transform by connecting a plurality of the time series data obtained by multiplying the window functions, and
The method for determining the properties and shedding of ash adhering to the boiler equipment according to claim 1, wherein the ash has. The step of extracting the period having the intensity peak is
A step of calculating the difference between the average intensity of the start point and the end point of a predetermined section of Fourier-transformed time series data and the maximum intensity in the predetermined section, and
When the difference in the calculated intensities is equal to or greater than a predetermined value, the step of determining the maximum intensity as the peak of the intensity in the Fourier transformed time series data, and
The method for determining the properties and shedding of ash adhering to the boiler equipment according to claim 1 or 2, wherein the ash has. A data analysis unit that Fourier transforms the time-series data of the heat collection amount of the boiler equipment over a predetermined time,
A peak extraction unit that extracts a period having an intensity peak in the time series data Fourier transformed by the data analysis unit, and a peak extraction unit.
A property / dropout cycle determination unit that determines that the cycle having the peak extracted by the peak extraction unit is the cycle in which the ash falls off from the boiler equipment.
A device for determining the properties and shedding of ash adhering to boiler equipment. A pre-processing 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 with 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, and
The ash property / dropout determination device according to claim 4, wherein the ash adheres to the boiler equipment. The peak extraction unit
An intensity difference calculation unit that calculates the difference between the average intensity of the start and end points of a predetermined section of Fourier-transformed time-series data and the maximum intensity within the predetermined section.
When the difference in intensity calculated by the intensity difference calculation unit is equal to or greater than a predetermined value, the peak determination unit determines that the maximum intensity is the peak of the intensity in the Fourier transformed time series data.
The ash property / dropout determination device according to claim 4 or 5, wherein the ash adheres to the boiler equipment.

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