JP2002022686A - Method for evaluating damage and stain of high temperature heat transfer part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide various data necessary for the stable operation of machinery by monitoring the material damage or stain state of a heat transfer part held under a heat flux condition and a high temperature condition one-line. SOLUTION: One or more temperature sensor 1 is attached to the heat transfer part 6, and the output of one or more temperature sensor attached to the heat transfer part 6 and the quantities of state necessary for the thermal analysis and material analysis of the machinery, for example, pressure, a flow rate, the temperatures of an operation fluid at the inlet and outlet of the machinery or the like are continuously measured at the same time and these data are taken in an arithmetic memory device to be processed. In this case, the temperature of the heat transfer part 6 damaged by the fluctuation of temperature generated by a heat flux change and receiving material dynamical damage under a high temperature condition is measured under a temperature condition including a high temperature condition and the heat transfer analysis of the heat transfer part 6 is performed from the temperature measured value and the temporally changing heat flux condition of the heat transfer part 6 and material dynamical damage such as fatique, creep or the like or a stain is calculated from the analyzed temperature behavior.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diagnosis of deterioration of a high-temperature heat transfer section such as a boiler or a heat exchanger, which receives a heat flux which changes with time and which is in a high temperature state and in which it is difficult to install a special sensor. The present invention relates to a high-temperature heat transfer portion damage / dirt evaluation method which provides a quantitative judgment guide for material exchange and dirt removal suitable for use in dirt diagnosis. More specifically, the present invention relates to an improved method for quantitatively evaluating, predicting, and displaying damage / dirt conditions online under heat flux conditions that change with operation.

[0002]

2. Description of the Related Art In a heat exchanger used in a large number of industries, a large temperature difference occurs in a heat transfer portion used for transferring heat between a high-temperature heat source and a low-temperature heat source. Material mechanical damage such as creep damage and fatigue damage in a heat transfer portion where temperature changes are repeated may occur. Further, in such a heat transfer section, there is a case where impurities in the working fluid are deposited and deposited on the heat transfer section to cause heat transfer inhibition or flow inhibition.

For example, superheaters and boilers in thermal power plants are:
Due to the heat (heat flux) from the high-temperature combustion gas and flame, the material itself becomes high temperature, and the above-mentioned material mechanical damage is severe,
Also, slight dirt adhering to the heat transfer section greatly raises the material temperature.

A technique for measuring and evaluating such mechanical damage and dirt damage is described in, for example, Japanese Patent Application Laid-Open No. 9-324.
Japanese Patent Application Laid-Open No. 9-1900 discloses a technique for measuring fatigue and creep in a plant piping.
No. 12294 discloses a heat exchanger contamination evaluation technique and the like.

[0005]

However, since superheaters and boilers of a thermal power plant are subjected to high heat flux conditions and high temperature conditions, conventionally, it is necessary to directly measure or evaluate damage and dirt during plant operation. Then, the temperature is greatly disturbed, and the measurement part is complicatedly deformed due to heat.
It was difficult to measure and evaluate in real time.

[0006] Therefore, regarding such damage or dirt on the high-temperature heat transfer section, generally, when the equipment or the plant is stopped, the target equipment is opened, a visual inspection, a sampling inspection of the material, and the like are performed. Usually, the degree of material damage is grasped and the state of contamination is checked by such means.

[0007] Therefore, when the operation period of the plant is long, for example, one year to two years, there is a problem that it is impossible to evaluate the internal state during the long operation. In other words, although it is possible to grasp the degree of material damage and check the contamination state from the results of various inspections performed at the time of stoppage, there is no method for evaluating the damage or contamination state during operation, and various operation modes are assumed. There is a problem that various inspection results at such intervals cannot be used for the evaluation of future device integrity.

[0008] In the technology described in the above-mentioned publication, all necessary information collection is performed in the non-heating unit.
In other words, a technique that requires the installation of a complicated sensor for damage measurement, such as that disclosed in Japanese Patent Application Laid-Open No. 9-324900, may be burned or deteriorated in a very short time when applied to a high-temperature part, and may suffer from heat flux. It cannot be applied to Further, since the technique of Japanese Patent Application Laid-Open No. 9-112294 cannot directly measure the heat transfer section, the state of contamination of the heating section is also indirectly measured from the temperature change of the non-heating section. In other words, in-situ measurement / evaluation techniques for high-temperature heat transfer sections that require the most damage and dirt evaluations have not been realized.

[0009] In addition, the fact that the damage and dirt condition of the equipment cannot be grasped in real time in accordance with the operating condition is due to the fact that the end of the life from the viewpoint of material mechanics or the dirt tolerance value generally defined as the equipment operation standard is early. This causes many cost increases, such as the necessity of exchanging materials and cleaning the heat transfer portion.

In view of the above, the present invention monitors on-line the material damage and dirt condition of the high-temperature heat transfer section under the heat flux condition,
At the same time, the purpose of the present invention is to provide a high-temperature heat transfer part damage / fouling evaluation method capable of predicting a past damage state / fouling prediction and a future damage progressing state / fouling state and providing various information necessary for stable operation of the equipment. .

[0011]

In order to achieve the above object, according to the method for evaluating damage / dirt of a high-temperature heat transfer section according to the present invention, the heat transfer section is attached to one or more temperature sensors or heat transfer sections attached to the heat transfer section. The output of one or more temperature sensors and the state quantities required for thermal and material analysis of the equipment, such as pressure, flow rate, working fluid temperature at the equipment inlet and outlet, are measured simultaneously and continuously. Is loaded into an arithmetic storage device and processed.

[0012] Based on this technology, a first aspect of the present invention is a method for evaluating damage / dirt of a high-temperature heat transfer section, which evaluates and monitors damage / dirt of a heat transfer section which is damaged by temperature fluctuation caused by a change in heat flux. The heat flux analysis of the heat transfer section is performed based on the measured values obtained when the temperature of the heat transfer section is measured by the temperature sensor under conditions including high temperature conditions, and the time-varying temperature and plant data of the heat transfer section. And heat transfer analysis to determine material mechanical damage such as fatigue and creep or dirt from the analyzed temperature behavior, and display the damage amount or degree of dirt online.

[0013] This makes it possible to evaluate the damage and dirt of the heat transfer section in real time according to the operating conditions, which can be evaluated only intermittently in the past, and at the same time damages under various assumed conditions. From the prediction of the state and the contamination state, a long-term maintenance plan of the equipment becomes possible.

Therefore, the operator and the maintenance manager can evaluate the in-situ damage of the high-temperature heat transfer section which changes with the change of the operating condition without waiting for the various inspections at the time of the next equipment stop and the analysis results. The necessity of material replacement can be immediately determined. In addition, the operator and maintenance manager can evaluate the contamination of the high-temperature heat transfer section, which could not be monitored conventionally, without waiting for the various inspections and the analysis results at the time of the next equipment stoppage. It is possible to immediately judge the influence evaluation, the necessity of cleaning dirt in advance, and the like.

The invention according to claim 2 is a function of predicting and displaying a damage / dirt state received in the past from a past operation state,
Equipped with at least one of the function of predicting and displaying the future damage / dirt condition from the predicted operation status and the function of displaying the optimal maintenance guideline based on some prepared operation patterns. The heat transfer analysis of the heat part is performed, and the cleaning time of the heat transfer part dirt or the material replacement time is determined online based on the material mechanical damage or dirt obtained from the analyzed temperature behavior.

According to this, the operator and the maintenance manager can quantitatively predict the damage and dirt condition of the high-temperature heat transfer section in the past, and quantitatively determine the damage and dirt condition in various future operation modes. Since it is possible to predict the operation plan, it is possible to quantitatively evaluate the operation plan creation and the maintenance plan creation from the viewpoint of the equipment life.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The configuration of the present invention will be described below in detail based on an example of an embodiment shown in the drawings.

1 to 9 show one embodiment of the present invention. The damage / dirt evaluation method of the high-temperature heat transfer part of the present invention
A temperature sensor (temperature measurement sensor) 1 attached to the high-temperature heat transfer section 6 as a dirt sensor or a temperature sensor 1 already attached for another purpose, and converting the sensor signal into a digital signal for input to an arithmetic processing unit. An A / D converter 2, a storage device for calculating a damage / dirt state based on storage of a temperature measurement value and a temperature measurement value and simultaneously predicting a damage / dirt state, and an output of a calculation result or a calculation storage device 3 And an input / output unit 4 for operating. The device operation control device (system) 5 is a device already installed for device operation, and device state quantity data necessary for damage / dirt evaluation is collected from the device operation control device 5.

As the temperature sensor 1, a known temperature detector or detection method such as a thermocouple, a thermistor, or a radiation thermometer is used. In this case, in the high-temperature heat transfer section 6, various temperature measuring methods as shown in FIG. The A / D converter 2 is a known converter of 12 bits or 16 bits. As the arithmetic storage device 3, a known computer including a storage device and a central processing unit is generally used. As the input / output unit 4, a well-known input / output device such as a keyboard, a CRT, and a plotter is used.

First, the instantaneous equipment state data and temperature sensor data are transferred via the A / D converter 2 to the arithmetic storage device 3.
Is captured and recorded. Then, the damage / dirt state evaluation / prediction program processes the device state data and the temperature sensor data on the central processing unit, analyzes the current damage state / dirt state, and outputs it to a display or output device. Further, if there is a data input from the input / output unit 4, a predicted value of the damage / dirt state is displayed or output to an output device.

Next, data processing contents will be described with reference to a flowchart of a damage / dirt evaluation / prediction program of the damage / dirt evaluation processing method shown in FIG.

First, the temperature data and the equipment state data are read (step 1), and these data are subjected to a heat transfer state evaluation under an instantaneous condition (step 2), and a detailed temperature analysis of the high-temperature heat transfer section 6 is performed.

For example, in the case of a boiler evaporator of a thermal power plant, the heat flux Q and the temperature T of each part are obtained from the measured temperature values as follows.

(Equation 1)

(Equation 2)

(Equation 3) The obtained heat transfer state analysis data is stored as a part of the time-varying data together with the data sampled by the system in the past (step 4). Further, the temperature data and the device state data are stored in a temperature / device state database (step 2).

Next, based on the result of the temperature analysis of the heat transfer section 6, the instantaneous creep damage of the material and the fatigue damage are determined from the past (several seconds to several minutes before) time-dependent temperature change (step 5). Here, the creep damage is obtained by the method shown in FIG. 3 from the heat flux, the inner surface of the tube, the average of the wall of the tube, and the temperature of the outer surface of the tube based on the actually measured temperature data and the operating data measured simultaneously. In addition, using a creep damage evaluation index such as Larson Miller parameter generally used for creep fatigue damage evaluation,

(Equation 4)

(Equation 5)

(Equation 6) Is obtained as the creep damage amount dc. This technique is a known technique.

In the damage analysis, a damage evaluation analysis using a finite element method or the like is performed in advance as shown in FIG. 12 based on the above-described heat transfer state analysis data, and the relationship between the temperature change amount and the damage is obtained. deep. Further, the relationship between the strain as shown in FIG. 4 and the amount of temperature change of the heat transfer section 6 is separately obtained, and the calculation method shown in FIG.
As shown in the following, the amount of damage d
f is required.

(Equation 7)

(Equation 8) These are made into a database as damage analysis data (step 6). In addition, we analyze the changes in damage state by comparing the results of creep and fatigue damage analysis in the past several hours to several years with the current values. Further, the dirt change state is analyzed (step 7), and a database is created (step 8).

Next, by comparing the past equipment state data and temperature sensor data with the temperature analysis result of the heat transfer section 6, and comparing the current equipment state data and temperature data with the heat transfer section temperature analysis result, The temperature change state is analyzed (step 9). FIG. 6 shows an example of the analysis result of the temperature change state of the heat transfer section. The change in contamination is quantified as the temperature change amount from the heat flux data obtained from the heat transfer analysis result and the temperature analysis result described above.

Next, the initial value of the dirty state and the initial value of the damaged state are predicted from the past device state data, and based on the initial values, the current damaged state and the dirty state are calculated as quantitative values and output. (Step 10). FIG. 7 shows an example of the damage state evaluation result, and FIG. 8 shows an example of the contamination state evaluation result.

Further, after the past creep damage / fatigue damage analysis (step 11), if the prediction conditions are input (step 12), the future damage state and dirt state are predicted and output (step 13, step 13). 14). FIG. 9 shows an example of the damage state prediction result.

Here, specific predictions (past and future) are performed as shown in FIG. First, a temperature distribution (Td = f (p, L, t)) as a basis for obtaining the current damage amount is formed into a function under a load, a position to be examined, and an elapsed time. Next, an amount of temperature rise (dT) due to the growth of the heat transfer surface contamination obtained from FIG. 23 is obtained. From this temperature rise, an initial state, that is, a time of zero contamination, is assumed, a temperature distribution at that time is obtained, and the value is set as an initial value. The prediction of the past damage amount can be obtained by calculating the temperature change from the initial value to the present and simultaneously with the damage calculation, and calculating the damage integral amount. To predict the future damage amount, damage integration may be performed for the future by the same procedure.

Therefore, the evaluation method of the present embodiment predicts and displays the damage / dirt state received in the past from the past operation state, and predicts and displays the future damage / dirt state from the predicted operation state. Any function of displaying the optimum maintenance guideline based on the function or some prepared operation patterns can be exhibited. Thereby, the heat transfer section 6
It is possible to determine the cleaning time of the heat transfer portion dirt or the material replacement time on-line based on the material mechanical damage or dirt obtained from the analyzed temperature behavior.

As described above, according to the high-temperature heat transfer section damage / dirt evaluation method of this embodiment, online damage evaluation and dirt evaluation of the high-temperature heat transfer section 6 which were not possible in the past, further damage prediction, Prediction is possible, and by using a plurality of temperature sensors 1 at the same time, it is possible to predict in advance damage / dirt states depending on parts of the device. For this reason, the driver and the maintenance manager can perform in-situ damage evaluation of the high-temperature heat transfer section 6 that changes with a change in the operation status without waiting for various inspections and analysis results at the time of the next equipment stoppage. The need for material replacement can be determined immediately. The driver,
The maintenance manager can evaluate the contamination of the high-temperature heat transfer section 6, which could not be monitored conventionally, without waiting for the various inspections at the time of the next equipment stop and the analysis results, and can evaluate the influence of the monitoring target equipment on the entire plant, The necessity of prior dirt cleaning can be immediately determined.

The above embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited thereto, and various modifications can be made without departing from the gist of the present invention.

[0033]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The above-described method for evaluating the damage and contamination of a high-temperature heat transfer section is useful for, for example, evaluating cumulative creep damage of a plant as a guide for chemical cleaning intervals. In other words, the chemical cleaning applied to the boiler evaporator tubes of a thermal power plant is carried out in order to prevent the overheating phenomenon of the evaporator tubes due to the growing scale adhering to the inner surface of the boiler evaporator tubes, and requires a lot of cost. However, if the interval of chemical cleaning can be extended from the viewpoint of maintaining equipment reliability, the cost reduction effect will be great.

Therefore, in this embodiment, first, the boiler metal thermometer data is continuously collected, the maximum pipe temperature and the average temperature are calculated, and then the respective creep damages are obtained and accumulated.
Furthermore, from the scale generation rate data, the amount of temperature rise and the amount of cumulative creep damage several years ahead were predicted, and the optimal chemical cleaning interval was determined. In this case, it is possible to prolong the chemical cleaning interval by positively evaluating the small creep damage in the low temperature range and incorporating it into the time.

Therefore, an experiment and a study were conducted for the purpose of confirming the possibility of constructing the system as described above. In this experiment, the temperature behavior of the metal of the evaporator tube in the normal combustion state with coal was investigated. As a result, it was found that the metal temperature did not always show a high temperature, but was dispersed in various temperature zones due to the fire extinguishing of the burner, the attachment and detachment of ash, and the like.

Here, when the conventional chemical cleaning timing determination method is used, an expression histogram for each temperature zone of the metal temperature of the side wall showing a short chemical cleaning interval is as shown in FIG. As can be seen from the figure, the temperature at which a short chemical cleaning interval occurs appears at 5% of all metal temperatures.
The frequency is as follows. On the other hand, the expression histogram for each temperature zone of the metal thermometer on the same side wall under the 100% load condition is as shown in FIG. The temperature at which the chemical cleaning interval is short is 545 ° C. or higher, but the temperature at 545 ° C. or higher has an expression ratio of about 20%, which means that the temperature is 525 ° C. on average.

As described above, the metal temperature used in the current chemical cleaning timing determination method can be determined to have been determined with a considerable margin, and all the temperatures indicated by the evaporation tubes can be more reasonably evaluated. If possible, the chemical cleaning interval can be extended.

Next, a study on damage to the evaporating tube was conducted.
The following is an example of study on thermal fatigue.

As a material mechanics study on thermal fatigue based on the flow shown in FIG. 12, an unsteady heat conduction analysis and a thermal stress analysis by the finite element method are performed based on the metal temperature data of the actual machine. Water-cooled wall tube thermal fatigue damage was evaluated.

A) Analysis of Temperature Data of Water-Cooled Wall Tube In order to determine the analysis conditions, the metal temperature data of the vaporized tube subjected to continuous measurement were arranged mainly from the viewpoint of quantitative evaluation of a sudden change in temperature. FIG. 14 shows an occurrence count histogram, and FIG.
Figure 10 shows the results of the study on the behavior of the sudden change phenomenon. The study was based on a two-month tally. A sudden change temperature of 50 ° C or less is excluded from the study. A sudden change temperature of 100 ° C or more is about 10%,
From the viewpoint of sudden change speed, the continuous measurement sampling interval is 3
Despite the restrictions of the minute, it became clear that the larger the temperature difference that suddenly changes, the faster the change speed.

B) Analysis by the Finite Element Method The finite element method analysis uses a three-dimensional model capable of expressing a local heat flux change shown in FIG. Based on the above, thermal stress analysis was performed in the order of elasto-plastic deformation. FIG. 17 shows the analysis conditions. FIG. 18 shows an example of the results of the transient heat conduction analysis and the results of the thermal stress analysis. FIG. 19 shows the results of the finite element analysis and the determination of the thermal fatigue analysis conditions. The furnace-side crown top section was increased to about 3.3 ° C / 10,000 kca with the increase of heat flux.
It can be seen that the temperature increases by 1 / m ² h (approximately 0.79 ° C./10,000 kJ / m ² h), and that the plastic deformation starts when the temperature of the tube surface increases by approximately 100 degC. In addition,
Outside the furnace, there is no temperature rise associated with the increase in heat flux.

FIG. 4 shows the relationship between the metal temperature and the equivalent strain due to the analyzed plastic deformation. It can be seen that the plastic equivalent strain has a linear correlation with the temperature rise.

From these facts, it is clear that the equivalent strain can be calculated by calculating the temperature rise in the region of 490 ° C. or higher, and that the fatigue life of the material can be estimated by the integrated evaluation of the equivalent strain. Was.

C) Thermal Fatigue Damage Evaluation Results FIG. 5 shows the relationship between the plastic strain range and the number of repetitions of failure for STBA 24 necessary for calculating thermal fatigue damage. In calculating the cumulative damage amount, a relational expression between the plastic strain range and the number of repeated failures in the figure was used.

FIG. 20 shows the results of the fatigue damage evaluation of each part of the water-cooled wall pipe obtained based on the result of the frequency analysis of the sudden change in the metal temperature of the actual machine. The figure shows several points that are severe in terms of thermal stress, but the largest fatigue damage amount was 0.0185 at the center of the right side wall. FIG. 21 shows the thermal fatigue damage evaluation procedure performed this time. By using the procedures described above, cumulative damage evaluation can be performed online from metal temperature data.

[0046]

As is clear from the above description, according to the method for evaluating the damage and dirt on the high-temperature heat transfer section according to the first aspect, the damage evaluation and the dirt evaluation of the high-temperature heat transfer section online, the damage prediction, and the contamination Prediction becomes possible. In addition, by using a plurality of temperature sensors at the same time, different damage / dirt states can be predicted in advance depending on the parts of the device, so that it is possible to select an inspection point to be stopped properly beforehand. As a result, not only the reliability of the device is improved, but also a severely damaged or stained portion can be specified, so that the test period can be shortened and the number of test samples can be reduced, which can be reflected in cost reduction. In particular, it is more and more effective in a high-temperature heat transfer section that is severely damaged and difficult to constantly monitor.

According to the method for evaluating the damage and dirt on the high-temperature heat transfer section according to the second aspect, the driver and the maintenance manager can quantitatively predict the damage and dirt condition of the high-temperature heat transfer section in the past.
In addition, since damage / dirt states in various future operation modes can be quantitatively predicted, it is possible to quantitatively evaluate operation plan creation, maintenance plan creation, and the like from the viewpoint of equipment life.

[Brief description of the drawings]

FIG. 1 is a diagram showing one configuration example of a method for evaluating damage / dirt of a high-temperature heat transfer section of the present invention.

FIGS. 2A and 2B are diagrams showing examples of temperature measurement of a heat transfer section, wherein FIG. 2A shows a cordal thermometer, FIG.
(C) The case where the radiation thermometer formula is used is shown.

FIG. 3 is a processing program flowchart for evaluating and predicting a damaged state and a dirt state.

FIG. 4 Strain and temperature change of heat transfer section (water temperature of metal wall pipe)
FIG. 4 is a diagram showing an example of the relationship with the following.

FIG. 5 is a diagram illustrating an example of a relationship between a strain and a fracture relational expression.

FIG. 6 is a diagram showing an example of a heat transfer surface temperature change state analysis result.

FIG. 7 is a diagram showing an example of damage state evaluation using the present method.

FIG. 8 is a diagram showing an example of a dirt condition evaluation using the present method.

FIG. 9 is a diagram showing an example of a damage state prediction using the present method.

FIG. 10 is a diagram showing a metal temperature histogram.

FIG. 11 is a diagram showing a temperature histogram at 500 MW.

FIG. 12 is a flowchart showing the concept of thermal fatigue damage evaluation.

FIG. 13 is a flowchart of a fatigue damage calculation.

FIG. 14 is a diagram showing an occurrence count histogram for each metal temperature change width.

FIG. 15 is a diagram showing a metal temperature / heat flux change behavior.
(A) Achieved temperature and sudden change temperature difference, (b) Heat flux and sudden change temperature difference, (c) Rapid change temperature and temperature change speed, (d) Heat flux before and after change are shown, respectively.

FIG. 16 is a diagram showing a thermal stress analysis model.

FIG. 17 is a table showing a list of thermal stress analysis conditions.

FIG. 18 is a diagram showing an example of a thermal stress analysis result.

FIG. 19 is a table showing a list of thermal stress analysis results.

FIG. 20 is a table showing evaluation results of thermal fatigue damage of a water-cooled wall tube.

FIG. 21 is a diagram showing a procedure for evaluating thermal fatigue damage.

FIG. 22 is a schematic diagram showing the concept of creep damage prediction.

FIG. 23 is a diagram showing a correspondence between a metal temperature change after selection processing and various phenomena, where (A) shows a case of 100% load condition;
(B) is a case of a 50% load condition.

[Explanation of symbols]

 Reference Signs List 1 temperature sensor 2 A / D converter 3 operation storage device 4 input / output unit 5 equipment operation control device 6 heat transfer unit

Continued on front page F term (reference) 2F056 CA08 CA15 CA18 EM05 2G040 AA05 AA08 AB08 AB10 BA08 BA15 BA28 CA02 CA10 CA12 CA23 CB02 DA03 DA05 DA06 DA13 DA15 EA08 GA05 GA07 GA08 HA02 HA16 ZA05

Claims (2)

[Claims] 1. A method for evaluating damage and dirt on a high-temperature heat transfer section for evaluating and monitoring damage and dirt on a heat transfer section damaged by temperature fluctuations caused by a change in heat flux, wherein the heat transfer section is controlled by a temperature sensor. The measured value when measuring the temperature under conditions including high temperature conditions, and the time-varying temperature of the heat transfer section
Perform heat flux analysis and heat transfer analysis of the heat transfer section from plant data, find material mechanical damage or dirt such as fatigue and creep from the analyzed temperature behavior, and display the damage amount or degree of dirt online. A method for evaluating damage and dirt on a high-temperature heat transfer section characterized by the following. 2. Damage received in the past from past operating conditions
Among the functions to predict and display the dirt condition, the function to predict and display the future damage and dirt condition from the predicted operation status in the future, and the function to display the optimal maintenance guideline based on some prepared operation patterns Equipped with at least one of the functions, the heat transfer analysis of the heat transfer section is performed, and based on the material mechanical damage or dirt determined from the analyzed temperature behavior, the cleaning time of the heat transfer section dirt or the material replacement time is determined online. The high-temperature heat-transfer part damage according to claim 1, which is determined.
Dirt evaluation method.