JP3458271B2 - Heat transfer tube remaining life evaluation device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention calculates and evaluates the remaining life of a heat transfer tube used in a superheater or reheater of a boiler of a thermal power plant, from the scale thickness in the tube, internal stress, etc. The present invention relates to a heat transfer tube residual life evaluation device.

[0002]

2. Description of the Related Art For example, as for tubes in a furnace of a boiler of a thermal power generation facility, many of them are renewed at a relatively early stage from the viewpoint of wall thinning. The heat transfer tube that composes the joint tube is made of ferritic heat-resistant steel, Cr-Mo, and is designed under relatively strict temperature conditions, and is used for a relatively long period of time. However, on the inner surface of the heat transfer tube of this type of boiler, steam oxidation scale is generally generated in proportion to the operating temperature and time, and steam oxidation scale is generated along with the outer surface corrosion of the tube. Increases with the thickness of the scale, and due to an increase in stress generated by internal pressure and deterioration of material, aged deterioration damage such as creep damage occurs. Therefore, in order to use the boiler soundly, it is necessary to accurately diagnose the remaining life of the heat transfer tube. Therefore, in the past, a test piece was made from a pipe extracted from an actual machine, a destructive test was performed in a laboratory, or a microstructure was observed by a microscope to measure creep damage, etc. to diagnose the remaining life of the pipe. .

[0003]

However, such a sampling inspection from an actual machine only evaluates the remaining life of a small number of pipes, and it is usually a few times for superheaters and reheaters. Hundreds of heat transfer tubes are provided, but there is a large difference in metal temperature depending on the connection position of each heat transfer tube to be connected, and there is considerable variation in the material deterioration and amount of wall thinning that occur in each heat transfer tube. Therefore, there is a problem that the remaining life of the entire heat transfer tube cannot be accurately determined by the destructive test for some tubes.

Therefore, conventionally, a method of evaluating the remaining life of this type of heat transfer tube by a so-called scale method has been proposed (for example, Japanese Patent Laid-Open No. 6-331622). To evaluate the remaining life of the heat transfer tube by this scale method, measure the thickness of the steam oxidation scale in the tube using an ultrasonic oscillation measuring device,
The generation of steam oxidation scale is a thermal activation process, and the logarithm of its thickness and the temperature / time parameter can be represented by a straight line. From this temperature / time parameter, the metal temperature is calculated, and from the internal pressure of the pipe, etc. The stress acting on the pipe is calculated, and the remaining life of the heat transfer pipe is calculated from the database of metal temperature, stress and creep rupture strength.

However, in the conventional method of evaluating the remaining life by the scale method of this kind, it is difficult to prepare a database of creep rupture strength by actual equipment, so that the operating state of the heat transfer tube is created in the laboratory and steam oxidation is performed. Although it will be necessary to measure the secular change in the thickness of the scale, there is a problem that it is difficult to collect long-term data of several hundreds of thousands of hours, and it is difficult to construct an actually usable system.

[0006] Further, there is no conventional remaining life evaluation apparatus based on the scale method capable of displaying the remaining life of the entire tube group at once, and the extent to which the heat transfer tube at any position can be determined only by looking at the calculated remaining life. There was a problem that it was difficult to quickly grasp if the remaining life of the

The present invention has been made in view of the above points, and it is possible to accurately calculate the remaining life of a heat transfer tube and to accurately and quickly grasp the remaining life of a large number of heat transfer tubes. An object of the present invention is to provide a device for evaluating the remaining life of a heat transfer tube.

[0008]

In order to achieve the above object, the remaining life evaluation apparatus according to claim 1 of the present invention, as shown in the configuration diagram of FIG. 1, injects ultrasonic waves from the outer peripheral surface of the heat transfer tube. Then, the scale thickness / tube thickness measuring means 10 for measuring the scale thickness and the tube wall thickness of the heat transfer tube by measuring the reflected wave
And a stress calculating means 20 for calculating an internal pressure stress from the pipe wall thickness measured by the scale thickness / tube wall thickness measuring means 10, the inner pressure of the heat transfer tube, and the outer diameter of the tube, and the metal previously measured in the heat transfer tube of the actual machine. The relational expression of the steam oxidation rate constant is obtained and stored from the data of temperature, scale thickness, and operating time, and the metal temperature of the heat transfer tube is calculated from the operating time and scale thickness of the heat transfer tube to be evaluated with the relational expression. A metal temperature calculating means 30 for calculating, and a storage means 25 for storing the scale thickness and the creep rupture strength measured in advance for the heat transfer tube of the actual machine as the creep rupture strength data for each scale thickness corresponding to the internal pressure stress of the heat transfer tube. A creep rupture strength is calculated using the measured scale thickness, the creep rupture strength data for each scale thickness written in the storage means 25, and the internal pressure stress. Fracture strength calculation means 40, and remaining life time calculation means for calculating the remaining life time of the heat transfer tube using the creep rupture strength calculated by the creep rupture strength calculation means 40 and the metal temperature calculated by the metal temperature calculation means 30. 45, the thinning rate is calculated from the elapsed operating time of the heat transfer tube and the decrease in the tubular thickness, and the internal pressure stress of the tubular wall thickness that decreases according to the thinning rate is calculated for each unit operating time. Using the remaining life time calculating means 45, the remaining life time at the time of thinning is calculated, the life consumption rate per unit operating time is calculated, and the life consumption rate is accumulated to calculate the cumulative life consumption rate. And a remaining life calculation means 50 for setting the cumulative value of the unit operating time when the cumulative life consumption rate exceeds 1 as the remaining life time of the heat transfer tube.

[0009]

In the residual life evaluation apparatus having the above-described structure, the scale thickness and the creep rupture strength of the heat transfer tube of the actual machine are measured in advance, and the storage means 25 stores the creep rupture strength data for each scale thickness corresponding to the internal pressure stress of the heat transfer tube. Remember. Further, the relational expression of the steam oxidation rate constant is obtained from the data of the metal temperature, the scale thickness, and the operation time which are measured in advance in the heat transfer tube of the actual machine, and the relational expression is stored.

With respect to the heat transfer tube to be evaluated, the scale thickness and tube wall thickness measuring means 10 injects an ultrasonic wave from the outer peripheral surface of the tube and measures the reflected wave to determine the scale thickness and the tube wall thickness of the heat transfer tube. Measure the thickness. Then, the stress calculating unit 20 calculates the internal pressure stress from the pipe wall thickness measured by the scale thickness / pipe wall thickness measuring unit 10, the internal pressure of the heat transfer pipe, and the pipe outer diameter. Further, the metal temperature calculating means 30 uses the relational expression of the steam oxidation rate constant to calculate the metal temperature of the heat transfer tube from the operating time of the heat transfer tube and the scale thickness.

Further, the creep rupture strength calculating means 40
Calculates the creep rupture strength using the measured scale thickness, the creep rupture strength data for each scale thickness written in the storage means 25, and the internal pressure stress, and the remaining life time calculation means 45 calculates the creep rupture strength calculation means 40. The remaining life time of the heat transfer tube is calculated by using the creep rupture strength calculated by and the metal temperature calculated by the metal temperature calculating means 30. Then, the remaining life calculation means 50 obtains the wall-thickness reduction rate from the elapsed operating time of the heat transfer tube and the decrease in the wall-thickness, and calculates the internal pressure stress of the tube wall-thickness that decreases according to the wall-thickness reduction per unit operating time. Then, the internal pressure stress and the remaining life time calculating means 45 are used to calculate the remaining life time at the time of thinning, and the life consumption rate per unit operating time is calculated. The remaining life calculation means 50 calculates the internal pressure stress, the remaining life time, and the life consumption rate each time a unit operation time elapses, and accumulates the life consumption rate to calculate a cumulative life consumption rate. Then, the cumulative value of the unit operation time when the cumulative life consumption rate exceeds 1 becomes the remaining life time of the heat transfer tube.

In this way, regarding the heat transfer tube of the actual machine,
The scale thickness and creep rupture strength were measured and stored as creep rupture strength data for each scale thickness corresponding to the internal pressure stress of the heat transfer tube, and the metal temperature, scale thickness, and operating time measured in the same heat transfer tube were also stored. The relational expression of the steam oxidation rate constant is calculated from the data in Table 1 and stored, and the remaining life of the heat transfer tube is calculated using these data as an arithmetic expression etc. The life can be accurately calculated.

Further, the remaining life calculation means calculates the internal pressure stress, the remaining life time, and the life consumption rate each time a unit operation time elapses, and accumulates the life consumption rates to calculate a cumulative life consumption rate, Since the cumulative value of the unit operating time when the cumulative life consumption rate exceeds 1 is used as the remaining life of the heat transfer tube, the wall thickness of the heat transfer tube decreases as the operation time elapses, and the internal pressure stress increases accordingly. It is possible to accurately calculate the remaining life according to the change of.

Further, as in the second aspect of the present invention, the remaining life distribution graph display means is provided, and the remaining life time calculated by the remaining life calculation means is calculated for the plurality of heat transfer tubes used in the superheater or the reheater. If it is configured so that it is displayed as a graph for the row or the number of stages of a plurality of heat transfer tubes, even if a large number of heat transfer tubes are arranged in rows or steps, the actual heat transfer or reheater It is possible to quickly grasp the relationship between the position of the heat pipe and the remaining life.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a configuration diagram of the remaining life evaluation apparatus. 1 is an ultrasonic oscillation measuring device, for example, 2
The probe 2 that oscillates an ultrasonic wave having a frequency of about 0 MHz and detects a reflected wave thereof is provided. This ultrasonic oscillation measuring device 1
At the time of measurement, the ultrasonic wave is oscillated and output from the probe 2 applied to the outer peripheral surface of the heat transfer tube 3, and the reflected wave of the ultrasonic wave reflected from the base material layer and the scale layer of the heat transfer tube 3 is detected. The wall thickness and scale thickness of the pipe 3 are measured from the reflected wave level, and the measured data is output. FIG. 3 shows a waveform diagram of the reflected wave, in which the horizontal axis represents time and the vertical axis represents the wave detection level. In the waveform diagram, TH corresponds to the thickness of the base metal of the tube (tube thickness), S corresponds to the scale thickness, and from the sound velocity of the ultrasonic wave traveling in the scale and the time width of its horizontal axis, The scale thickness S is calculated and output as measurement data.

As shown in FIG. 7, the heat transfer tube 3 to be measured is a tube connected to the outlet port 4 of the superheater or the reheater, and each heat transfer tube 3 has a row number ( For example, 1 to 74) and the number of stages (for example, A to J) are attached, and the measurement data of these pipes are identified by attaching the pipe row number and the number of stages.

Reference numeral 5 denotes an arithmetic processing device composed of a personal computer or the like, which takes in the measurement data of the pipe wall thickness TH and the scale thickness S from the ultrasonic oscillation measuring device 1 and inputs them using a keyboard or the like. The stress σ is calculated from the inner pressure of the heat transfer tube 3, the outer diameter of the tube, and the wall thickness measurement data, and the operating time H, the scale thickness S, and the pre-stored case thickness S, metal temperature T, and operating time H are calculated. The metal temperature T of the heat transfer tube 3 is calculated from the relational expression. Further, the arithmetic processing unit 5 determines the remaining life evaluation curve of FIG. 6 from the previously stored creep rupture strength data for each scale thickness, the internal pressure stress σ, and the scale thickness S, and calculates the metal temperature T and the remaining life evaluation curve. It is used to calculate the remaining life of the heat transfer tube 3. The remaining life is calculated for all heat transfer tubes of the superheater or reheater,
A graph showing the distribution of the remaining life with respect to the tube row or the number of stages of the heat transfer tubes is created and displayed on the display 6 such as a CRT or a liquid crystal display.

By the way, it has been found that the steam oxidation scale produced in the heat transfer tube 3 exhibits a parabolic growth behavior at a constant temperature, and its oxidation rate constant k _p is k _p = d ² / t · ..... Expressed by the formula (1). Where d is the amount of wall thinning of the pipe base metal (c
m) and t are time (seconds).

Further, the relational expression between the amount of wall thinning d, the time and the temperature T during the scale formation, that is, the metal temperature T (° K) is, from the experimental value, Logk _p = 1000a / T + b (2) When the amount of thickness reduction d (cm) is converted to the scale thickness S (μm) and the time t (second) is replaced with the time t (hour), d ² / t = ((S / 2. 1) × 10 ⁻⁴ ) ² / (t × 3600) ··· (3), the equation for the temperature T during scale generation is obtained from Equation (2) as Log (((S / 2.1) × 10 ⁻⁴ ) ) ² / (t × 3600)) = 1000a / T + b (4) Therefore, T (° K) = a / (c-2LogS + Logt) (5) Here, a, b, and c are constants determined by various conditions.

Therefore, in order to determine the constants a, b and c, the metal temperature T of a plurality of heat transfer tubes used in the superheater and reheater of the boiler which is actually in operation is measured, and A part of these heat transfer tubes is pulled out, and their scale thickness S is measured by cross-section observation, and the metal temperature T
A large number of data on the scale thickness S and the operating time H were collected.

Then, the steam oxidation rate constant Logk is calculated using the following equation (6) obtained from the above equations (1) to (4).
_p was calculated and Logk _p = (S / 2.1) × 10 ⁻⁴ ) ² / (t × 3600) (6) These steam oxidation rate constants Logk _p were calculated as shown in FIG. The reciprocal of (1000 / (T + 273)) was plotted on a graph with the horizontal axis taken to obtain a straight line Y on these plots.

When this straight line Y is formulated, Logk _p = −d × (1000 / (T + 273)) − e (7) where d and e are constants, and the above equation (3) And formula (7)
From Log (((S / 2.1) × 10 ⁻⁴ ) ² / (t × 3600)) = −d × (1000 / (T + 273)) − e ... (8) Becomes Then, from the above formula (8), T (° C.) + 273 = d / (f−2LogS + LogH) (9) scale thickness S, metal temperature T ° C., operating time H (h
An equation showing the relationship of r) was obtained. Here, f is a constant.

In the above equation (9), a graph in which the metal temperature T ° C. is changed, for example, from n ₁ ° C. to n ₁₀ ° C., is a graph with the horizontal axis representing the operating time t and the vertical axis representing the scale thickness S. 5, the curve data of this graph, that is, the data indicating the relationship between the scale thickness S, the metal temperature T ° C., and the operating time H, is stored in the storage unit of the processing unit 5 as an arithmetic expression. Or in advance as table data or the like.

Further, data of creep rupture strength (Larson Miller parameter: LM value) according to the scale thickness is stored in the storage unit of the arithmetic processing unit 5 in advance. This creep rupture strength (LM value) data was obtained by actually extracting a part of the actual equipment and new material of the heat transfer tube in the boiler superheater and reheater used for a long period of time, and measuring their scale thickness. Is measured by observing a cross section, and a creep rupture test is performed to collect the rupture test values. The creep rupture strength (LM value) of the creep rupture test is shown in FIG. Scale thickness S
It becomes a straight line corresponding to (140 μm to 800 μm), and is expressed by the equation: LM = f (S, σ) ... (10).

The straight line data of the creep rupture strength (LM value) according to the scale thickness S is stored in advance in the storage unit of the arithmetic processing unit 5 as an arithmetic expression or table data. If the scale thickness is other than a straight line, it is calculated by proportional interpolation.

On the other hand, the stress σ due to the internal pressure of the heat transfer tube 3 is stored in advance by using the tube wall thickness TH measured by the ultrasonic oscillation measuring device 1, the tube outer diameter D _O input from a keyboard or the like, and the internal pressure P. σ = (P / 100) × (D _o /2TH−0.5) ... (11)

By the way, there are variations in the material properties of the heat transfer tube, and it is conceivable that the variations in the material properties affect the estimation and evaluation of the remaining life. Therefore, when the creep rupture strength (LM value) is actually estimated and evaluated from the scale thickness S and the stress σ using the graph data of FIG. 6, the concept of the safety factor for the rupture stress σ is introduced and selectable. By multiplying the internal pressure stress σ by multiple safety factors α (for example, 100% 80% 67%), make an evaluation line of creep rupture strength (LM value) as shown by the broken line in the graph of Fig. 6, and actually Uses this evaluation line to obtain the creep rupture strength (LM value) with respect to the scale thickness S and the stress σ. That is, the evaluation stress σ _O used in the actual calculation is calculated from the equation σ _O = σ / α.

The relationship between the creep rupture strength (LM value), the metal temperature T, and the remaining life time of the pipe is expressed by the following formula: LM = (T + 273) × (g + Logφ) × 10 ⁻³ (12) To be done. Here, g is a constant and φ is the remaining life time of the tube.

The creep rupture strength (LM
Value) and the metal temperature T are substituted to calculate the remaining life time φ of the pipe, but with the decrease in the pipe wall thickness due to long-term operation,
Since the internal pressure stress increases, it is necessary to correct the creep rupture strength (LM value) downward based on the reduced pipe wall thickness according to long-term operation.

Therefore, since the initial wall thickness of the heat transfer tube 3 when a new material is known is known, the wall thickness reduction rate β is calculated from the tube wall thickness TH during the operating time H.
(Fig. 9), and a certain unit operating time (for example,
1000 hours) At every Δt, the creep rupture strength (LM value) is calculated based on the increase in stress due to the decrease in pipe wall thickness, and the LM value is corrected downward, and the LM value and the reduced pipe wall thickness Using the increased stress σ _i , the remaining life time φ _{i at} that time is calculated for each unit time.

Further, the ratio of the remaining life time φ _i to the unit time Δt is the life consumption rate ψ _i, and ψ _i = Δt /
It is calculated from the formula of φ _i . At the same time, the unit time Δt (1000 hours) is accumulated as the elapsed time, and every time the unit time Δt is added, that is, every time the unit time Δt is added to the operating time H, the life consumption rate ψ _i is calculated and accumulated. Cumulative life consumption rate Σ
Calculate ψ _i . Then, when the cumulative life consumption rate Σψ _i exceeds 1, it is determined that the life has ended, and finally the cumulative value of the elapsed time immediately before that, that is, the unit time Δt is the remaining life time Φ of the heat transfer tube 3. _i-1 .

The calculation of the remaining life time Φ _i-1 is carried out for all the input heat transfer tubes, and the remaining life is plotted for each row of tubes as a graph of the remaining life for the row of tubes or the remaining life for the number of tubes. Is displayed as a graph on the display 6.

Next, the specific operation of the remaining life evaluation device will be described.
This will be described with reference to the flowcharts of FIGS.

First, the measurement data of the heat transfer tube 3 collected by the ultrasonic oscillation measuring device 1, that is, the tube thickness TH and the scale thickness S, is read and written in each data sheet (step 100). Data indicating the position of the heat transfer tube 3 (the number of tube rows and the number of stages) is attached to each data, and the total number of tube rows and the number of all stages of the heat transfer tube 3 are input to the arithmetic processing device 5 from a keyboard or the like. Next, in step 110, the operation time H of the heat transfer tube 3 up to now is input from a keyboard or the like.

Then, in the next step 120, the metal temperature T of each heat transfer tube 3 is calculated. This metal temperature T
Is calculated from the above equation (9) using the operating time H and the scale thickness S. That is, since the curve of the metal temperature T is shown on the graph of the operating time H and the scale thickness S as shown in FIG. 5, the curve of the metal temperature T is determined from the operating time H and the scale thickness S (corresponding When there is no curve at the position of the operating time H and the scale thickness S, the metal temperature T is calculated.

Next, at step 130, the internal pressure P (kg / cm ² ) of the heat transfer tube 3 actually used and the tube outer diameter D _O (mm) are input from a keyboard or the like. And step 140
Then, the stress σ due to the internal pressure of the heat transfer tube 3, the tube wall thickness TH measured by the ultrasonic oscillation measuring device 1, the input tube outer diameter D _O ,
It is calculated from the above equation (11) using the internal pressure P.

Next, in step 150, the safety factor α (for example, 100% 80% 67%) is input, and the Larson-Miller parameter (LM value) which becomes the creep rupture strength from the scale thickness S, stress σ, and safety factor α. Is calculated using the data of the formula shown in the graph of FIG. The safety factor α is used by multiplying the internal pressure stress σ, and the evaluation stress σ _O (kg / mm ² ) is σ _O = σ /
The evaluation stress σ _O calculated from the expression of α is moved to the lower side of the solid line corresponding to the internal pressure stress σ by multiplying the safety factor as shown by the broken line in FIG. If there is no straight line corresponding to the scale thickness S, proportional interpolation is performed to calculate the Larson-Miller parameter (evaluation LM value) corresponding to the evaluation stress σ _O and the scale thickness S.

Next, at step 160, the above equation (10) is obtained.
By substituting the evaluation LM value and the metal temperature T into, the remaining life time φ ₀ of the tube is calculated. Then, the unit operating time Δt is added to the operating time H to obtain the reduced wall thickness TH _i at the time of the operating time (H + Δt), and the internal pressure stress σ _i is obtained from the pipe thickness TH _i. Similarly, the Larson Miller parameter (LM value), which is the creep rupture strength, is calculated from the scale thickness S, the internal pressure stress σ _i , and the safety coefficient α by using the formula of the graph in FIG. 6 or the table data,
The remaining life time φ _i of the pipe after the unit operation time Δt has elapsed is calculated. Then, from this remaining life time φ _i , the life consumption rate ψ
calculates a _i, we obtain the cumulative lifetime consumption rate Shigumapusai _i, remaining life time of the cumulative value of the clogging previous unit time Δt at which the cumulative lifetime consumption rate Shigumapusai _i exceeds 1 the heat transfer tubes 3 [Phi _i- Calculated as ₁ .

That is, as shown in the detailed flow chart of FIG. 9, first, at step 200, the pipe wall thickness TH _i after the lapse of the operating time Δt is calculated using the thickness reduction ratio β, and then at step 210. , As described above, the changed internal pressure stress σ _i
Is calculated from the above equation (11) using the changed pipe wall thickness TH _i , pipe outer diameter D _O , and internal pressure P. Next, step 22
At 0, the Larson-Miller parameter (L is the creep rupture strength based on the scale thickness S, internal pressure stress σ _i , and safety factor α).
The M value) is calculated using the graph data of FIG. 6 in the same manner as above.

Then, in step 230, the unit time is
Remaining life time of the pipe after a lapse of Δt _i And calculate the next
At step 240, the remaining life time φ with respect to the unit time Δt
_i Lifetime consumption rate ψ_i Is ψ_i = Δt / φ_i of
Calculated from the formula and accumulated, cumulative life consumption rate Σψ_i To
Ask. Next, in step 250, this cumulative life consumption rate is
Σψ_i If it exceeds 1, it is judged whether it exceeds 1.
If so, the process proceeds to step 260, and the operating time H
_i Unit operating time Δt is added to _{i + 1} When
Then, the process returns to step 200 again, and the operating time H_{i + 1} When elapsed
Pipe wall thickness TH_{i + 1}Is calculated using the metal loss rate β as above.
Put out.

Further, similarly to the above, the stress σ _{i + 1} is calculated, the remaining life time φ _{i + 1} is calculated, and the life consumption rate ψ _{i + 1} is calculated. Then, similarly to the above, in step 250, it is determined whether or not the cumulative life consumption rate Σψ _{i + 1} exceeds 1, and when it does not exceed 1, the process proceeds to step 260 again,
The unit operating time Δt is added to the operating time H _{i + 1} to obtain the operating time H _{i + 2} .

As described above, by repeating the above steps 200 to 260, the operating time H passes by the unit operating time Δt, the pipe wall thickness TH gradually decreases, and the stress σ gradually increases. The life consumption rate ψ gradually increases. When the cumulative life consumption rate Σψ _i exceeds 1, the process proceeds from step 250 to step 270, and when the cumulative life consumption rate Σψ _i exceeds 1, that is, the cumulative value ΣH _i- of the previous unit time Δt. ₁ is the remaining life of the heat transfer tube 3 Φ
Calculated as _i-1 .

The calculation of the remaining life time Φ _i-1 of the heat transfer tubes 3 as described above is performed for all the measured and input heat transfer tubes 3, and is a graph of the remaining life with respect to the row of tubes for each stage number of tubes, or Is displayed as a graph of the remaining life with respect to the number of stages of tubes for each tube row as shown in FIG. In this way, by displaying the graph as a graph of the remaining life time with respect to the tube row or the number of stages of the tube, in the superheater or reheater, for example, according to the connection position of the heat transfer tube used by connecting to the outlet header. It is easy to understand the tendency for the remaining life of the tubes to change, and to quickly and accurately grasp the remaining life of many heat transfer tubes,
It can be used for lean tube replacement.

[0044]

According to the remaining life evaluation apparatus of the present invention, the heat transfer tube to be evaluated is measured by using the data such as the creep rupture strength and the arithmetic expression prepared in advance based on the data collected in the heat transfer tube of the actual machine. Since the remaining life is calculated by using the data of the pipe wall thickness and the scale thickness, it is possible to accurately calculate the remaining life of the heat transfer pipe of the actual superheater or reheater. In addition, internal pressure stress,
The creep rupture strength, remaining life time, and life consumption rate are calculated, and the cumulative value of unit operating time when the cumulative life consumption rate, which is the cumulative value of the life consumption rate, exceeds 1, is defined as the remaining life time of the heat transfer tube. Therefore, it is possible to calculate the accurate remaining life due to the increase of the internal pressure stress according to the pipe wall thickness that decreases with the passage of the operating time.

[Brief description of drawings]

FIG. 1 is a configuration diagram of the present invention.

FIG. 2 is a configuration diagram of a remaining life evaluation apparatus showing an embodiment of the present invention.

FIG. 3 is a waveform diagram of a measurement reflected wave of the ultrasonic oscillation measuring device.

FIG. 4 is a graph showing the relationship between metal temperature and steam oxidation rate constant.

FIG. 5 is a graph showing the relationship between scale thickness, metal temperature, and operating time.

FIG. 6 Scale thickness, stress, creep rupture strength (LM
It is a graph which shows the relationship of (value).

FIG. 7A is a plan view of the outlet of the superheater, and FIG. 7B is an enlarged sectional view thereof.

FIG. 8 is a flowchart showing the operation of the remaining life evaluation apparatus.

FIG. 9 is a flowchart of remaining life calculation processing.

FIG. 10 is a graph output diagram of the remaining life evaluation apparatus.

[Explanation of symbols]

1-Ultrasonic oscillation measuring device 2-probe 3- Heat transfer tube 5-Processing device 6-Display

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) G01N 33/20 G01M 19/00 G01N 29/10

Claims (2)

(57) [Claims] 1. Scale thickness / tube wall thickness measuring means for measuring the scale thickness and tube wall thickness of the heat transfer tube by injecting ultrasonic waves from the outer peripheral surface of the heat transfer tube and measuring the reflected wave thereof. Thickness / tube wall thickness, stress calculation means to calculate internal pressure stress from heat transfer tube inner pressure and tube outer diameter, metal temperature and scale thickness previously measured in heat transfer tube of actual machine , And the relational expression of the steam oxidation rate constant is obtained from the data of the operating time and stored, and the metal temperature calculation is performed to calculate the metal temperature of the heat transfer tube from the operating time and the scale thickness of the heat transfer tube to be evaluated with the relational expression. Means for storing scale thickness and creep rupture strength measured in advance for a heat transfer tube of an actual machine as creep rupture strength data for each scale thickness corresponding to internal pressure stress of the heat transfer tube; Creep rupture strength calculation means for calculating creep rupture strength using the measured scale thickness, scale rupture strength data by scale thickness written in the storage means, and internal pressure stress, and creep rupture strength calculated by the creep rupture strength calculation means The remaining life time calculating means for calculating the remaining life time of the heat transfer tube using the strength and the metal temperature calculated by the metal temperature calculating means, and the thinning rate from the elapsed operating time of the heat transfer tube and the decrease in the tube wall thickness. Obtained, calculate the internal pressure stress of the pipe wall thickness that decreases according to the wall thinning rate for each unit operating time, and calculate the remaining life time at the time of thinning using the internal pressure stress and the remaining life time calculation means. Calculating the life consumption rate per unit operating time, calculating the cumulative life consumption rate by accumulating the life consumption rates, and calculating the cumulative value of the unit operating time when the cumulative life consumption rate exceeds 1 No no no Residual life evaluating apparatus of the heat transfer tube for the remaining life calculating means for the life time, further comprising a said. 2. A remaining life in which the remaining life time calculated by the remaining life calculation means for a plurality of heat transfer tubes used in a superheater or a reheater is displayed as a graph with respect to the number of rows or stages of the plurality of heat transfer tubes. 2. The heat transfer tube residual life evaluation device according to claim 1, further comprising distribution graph display means.