JP4906561B2 - In-pipe deposit diagnosis method - Google Patents

Description

  The present invention relates to an in-pipe deposit diagnosis method for diagnosing the status of deposits attached to a tube.

  "Non-destructive inspection", Vol. 51, No. 51, published in October 2002, pages 632 to 636 [Non-Patent Document 1] includes "a coking diagnostic apparatus for a heating furnace tube using acoustic emission". Under the title of “development”, a conventional technique for diagnosing the state of coking attached to the inside of a furnace tube using an acoustic emission method is disclosed. In this prior art, an acoustic emission signal is incident from one location of the heating furnace tube to be diagnosed, and an acoustic emission signal is received at one location separated in the longitudinal direction of the heating furnace tube, and the received acoustic emission is received. The signal attenuation state is acquired as data. And in this prior art, the data of the decay state of the acoustic emission signal acquired in advance by applying the same acoustic emission method to a new furnace tube without coking is used as the reference data and measured. By comparing with the data, the adhesion situation of caulking is diagnosed and evaluated.

In addition, Idemitsu Engineering Co., Ltd.'s website, http://www.idemitsu.co.jp/eng/product/drplant/composition/calking.html, is entitled As an example of the diagnostic method used, a technique for measuring the thickness of coking by measuring the dose of radiation passing through the furnace tube by the radiation transmission density method is introduced.
"Non-destructive inspection", Vol. 51, No. 10, pages 632 to 636 http://www.idemitsu.co.jp/eng/product/drplant/composition/calking.html

  In the conventional diagnosis method described in Non-Patent Document 1, the acoustic emission method is performed on the heating furnace tube in which coke as a reference for comparison is not attached, and the decay state data of the acoustic emission signal is obtained. Have to get. However, this standard method should be used because no reference data can be obtained if a new tube without the same material and coking of the same size as the furnace tube to be diagnosed is not available. There is a problem that can not be. In addition, if the relationship between the incident position of the acoustic emission signal and the receiving position when the reference data is acquired cannot be accurately reproduced for the heating furnace tube to be diagnosed, there is a problem that accurate diagnosis and evaluation cannot be performed. appear. In addition, since the acoustic emission signal is attenuated by process fluid and sludge remaining in the pipe during periodic inspections of the plant, there is also a problem that it is impossible to distinguish the residual in the pipe from coking. .

  Moreover, in the conventional method of diagnosing using a diagnostic method using radiation as a diagnostic method using radiation, the radiation must be moved sequentially along the heating furnace tube to measure the radiation transmitted dose, In order to diagnose one heating furnace tube, there is a problem that a great deal of cost and time must be spent.

  An object of the present invention is to provide an in-pipe deposit diagnostic method capable of diagnosing the status of deposits in a pipe using an acoustic emission method without preparing reference data in advance.

  In addition to the above object, another object of the present invention is to provide an in-pipe deposit diagnosis capable of diagnosing the status of the deposit in the tube even when a residue other than the deposit to be diagnosed remains in the tube. It is to provide a method.

  In addition to the above-mentioned purpose, only the pipes that require detailed diagnosis can be used to diagnose the coking situation in the furnace tube in a much shorter period of time by applying a diagnostic method using radiation. An object of the present invention is to provide a method for diagnosing deposits in a tube.

  The present invention is directed to an in-pipe deposit diagnosis method for diagnosing the status of deposits attached to a tube. The pipe to be diagnosed by the present invention includes a pipe in which various deposits adhere to the inner wall, typically a heating furnace pipe in which coking adheres. In the method of the present invention, first, a plurality of acoustic emission sensors are arranged so as to form a sensor array at a predetermined angular interval in the circumferential direction on the outer periphery of a diagnosis region to be diagnosed of a pipe. Here, the diagnostic region is a virtual annular region having a width dimension capable of completely arranging the acoustic emission sensor. In the present invention, the signal incident pulser is arranged on the outer periphery of the diagnostic region so as to be positioned in the sensor array. The plurality of acoustic emission sensors and signal incident pulsers constituting the sensor array need only be arranged at intervals in the circumferential direction, and need not be arranged on a straight line.

  After installing a plurality of acoustic emission sensors and a signal incident pulser under such conditions, an acoustic emission signal is incident on the diagnostic region from the signal incident pulser. From the output of multiple acoustic emission sensors, the attenuation rate of the acoustic emission signal between the signal incident pulser and the adjacent acoustic emission sensor, and between the two adjacent acoustic emission sensors in the circumferential direction Calculate the decay rate of the acoustic emission signal at. Here, the attenuation rate refers to, for example, the acoustic emission signal measured on the downstream side in the denominator of the amplitude of the acoustic emission signal, the acoustic emission energy, and the signal duration on the upstream side of the path through which the acoustic emission signal propagates. It is the ratio of the signal strength obtained by calculating the emission signal amplitude, acoustic emission energy, and signal duration in the numerator. Therefore, the attenuation factor at the position of the signal incident pulser is “1”, and the attenuation factor approaches “0” as the distance from the signal incident pulser increases.

  In the present invention, the attenuation rate of the acoustic emission signal in a certain length range of the tube (which may be either a certain length range in the circumferential direction of the tube or a length range in the longitudinal direction of the tube) is within the length range. Due to the fact that the inventor found that there is a negative correlation with the product value represented by the product of the thickness of the deposit attached to the inner wall and the length dimension of the length range, It has been devised. That is, the inventor has found that there is a relationship between the product value and the attenuation rate that the product value decreases as the attenuation rate increases and the product value increases as the attenuation rate decreases. The inventor also shows that this relationship (trend) does not change even if the various deposits including caulking, the various tube materials, the tube dimensions are different, or the incident position of the acoustic emission signal is different. Confirmed by. This relationship also exists in the circumferential direction of the tube and in the longitudinal direction of the tube. Therefore, if the relationship and the length dimension of the length range are known in advance, the thickness of the deposit in the length range can be estimated based on the attenuation rate. In this estimation, it is not always necessary to estimate the thickness of the deposit as an absolute value, and it is sufficient that the change in thickness and the level of thickness can be estimated as relative values. In the present invention, by calculating the above-described attenuation rate from the outputs of a plurality of acoustic emission sensors arranged at predetermined angular intervals in the circumferential direction of the tube, the reference data for the tube to be diagnosed is not used. The change in the thickness of the deposit in the circumferential direction can be estimated. As a result, it is possible to diagnose the state of the deposit based on this estimation.

  In order to facilitate estimation, the distance between a plurality of acoustic emission sensors in the sensor array and the distance between two acoustic emission sensors adjacent to the signal incident pulser are the same. It is preferable to use a distance. If it does in this way, when estimating the thickness of a deposit | attachment based on the calculated subtraction rate, thickness can be estimated easily. This estimation result of the thickness can be regarded as an average thickness of the deposit within the length range.

  Further, a plurality of acoustic emission sensors and signal incident pulsers in the sensor array may be attached to the diagnosis region in a state where they are attached to a common attachment jig. In this way, since a plurality of acoustic emission sensors can always be mounted on the pipe under the same conditions, the occurrence of calculation errors based on mounting errors can be reduced.

  In the present invention, diagnosis can be performed not only in the circumferential direction of the tube but also in the longitudinal direction of the tube by performing the following. First, a plurality of acoustic emission sensors are arranged so as to form a first sensor array at a predetermined angular interval in the circumferential direction on the outer periphery of the first diagnosis region to be diagnosed of the pipe. A signal incident pulser is arranged on the outer periphery of the diagnostic region so as to be located in the first sensor array. Further, a plurality of acoustic sensors are formed so as to form a second sensor array at a predetermined angular interval in the circumferential direction on the outer periphery of the second diagnostic region at a predetermined distance from the first sensor array in the longitudinal direction of the tube.・ Install emission sensors. After doing so, an acoustic emission signal is incident on the diagnostic region from the signal incident pulser. Then, from the outputs of the plurality of acoustic emission sensors constituting the first sensor array, the attenuation rate of the acoustic emission signal between the signal emission pulser and the adjacent acoustic emission sensor is adjacent to the circumferential direction. Calculates the attenuation rate of the acoustic emission signal between the two acoustic emission sensors. Further, the attenuation of the acoustic emission signal between the signal incident pulser and the plurality of acoustic emission sensors constituting the second sensor row is determined from the outputs of the plurality of acoustic emission sensors constituting the second sensor row. Calculate the rate. Thereafter, in the first sensor array, on the assumption that there is a negative correlation between the distance between the two acoustic emission sensors and the product value of the thickness of the deposit between them and the attenuation factor, A change in thickness in the circumferential direction of the deposit in the first diagnostic region is estimated from the attenuation rate. Similarly, the change in the thickness of the deposit in the longitudinal direction between the first diagnostic region and the second diagnostic region is estimated from the attenuation rate in the second sensor array. As a result, it is possible to diagnose the state of deposits adhering to the inside of the tube between the first diagnosis region and the second diagnosis region. The change in the thickness in the longitudinal direction is considered to be the average thickness of the deposit along the imaginary line connecting the signal incident pulser and the acoustic emission sensor through the outer peripheral surface of the pipe with the shortest distance. be able to. The number of signal incident pulsars provided in the first diagnosis area is set to a plurality and spaced at appropriate intervals in the circumferential direction, and an acoustic emission signal is individually incident from each signal incident pulsar. It is also possible to perform estimation for a plurality of times with different values, and estimate the change in the thickness of the deposit in the longitudinal direction from the plurality of estimations.

  In order to facilitate the calculation, the distance between the plurality of acoustic emission sensors in the first sensor array and the distance between the two acoustic emission sensors adjacent to the signal incident pulser Is preferably a constant distance. Also, it is preferable that the distance between the plurality of acoustic emission sensors in the second sensor array is the same as the fixed distance.

  Also in this case, the plurality of acoustic emission sensors and the signal incident pulser in the first sensor array are mounted on the first diagnostic region in a state where they are mounted on a common mounting jig. The plurality of acoustic emission sensors in the second sensor array are preferably attached to the second diagnostic region in a state where they are attached to a common attachment jig. This facilitates mounting and positioning of the signal incident pulser and the acoustic emission sensor.

  The present invention can be used for diagnosing deposits adhering to the inside of various pipes, and is particularly suitable for diagnosing coking formed in a heating furnace pipe. In the diagnosis of a heating furnace tube, radiation such as a radiation transmission density method or a radiation transmission test method using an imaging plate is applied to the tube only when the condition of coking in the heating furnace tube satisfies a predetermined risk condition. It is preferable to make a detailed diagnosis of the coking situation using the diagnostic method utilized. In this way, it is only necessary to make a detailed diagnosis of the coking situation using a radiation-based diagnostic method only for tubes that really need a detailed diagnosis. When a typical diagnosis result is output, the number of times of diagnosis by the radiation transmission density method can be minimized.

  According to the present invention, it is assumed that there is a negative correlation between the distance between two acoustic emission sensors and the product value of the thickness of the deposit between them and the attenuation rate. Since the change in the thickness of the deposit is estimated by estimating the thickness of the deposit based on the signal attenuation rate, there is an advantage that the status of the deposit in the pipe can be diagnosed without using the reference data. is there.

  Further, according to the present invention, the acoustic emission method is used to perform the diagnosis first, so that only when the condition of coking in the heating furnace tube satisfies the predetermined risk condition, the radiation transmission density method is used for the final diagnosis. If an accurate diagnosis result is obtained, there is an advantage that the number of times of diagnosis by the radiation transmission density method can be minimized.

  Embodiments of the in-pipe deposit diagnostic method of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows how the present invention is used to distinguish caulking and residue (process fluid, sludge) adhering to the inside of a heating furnace tube 1 disposed in a heating furnace, and to determine the inside of a predetermined region of the heating furnace pipe 1. It is a figure used in order to demonstrate the example in the case of diagnosing what kind of situation the coking has adhered along both the circumferential direction and the longitudinal direction in FIG. FIG. 1 shows a state in which only a part extending in the horizontal direction is cut out in a long heating furnace tube 1 extending continuously. In FIG. 1, the downward direction on the paper surface is the downward direction in which gravity acts on the earth. FIG. 2 is a schematic illustration of a specific arrangement state of the signal incident pulser 2 and a plurality of acoustic emission sensors 31 to 37 actually arranged around the heating furnace tube 1 with some exaggerated. FIG. Note that in FIG. 2, the purpose is to show the positional relationship and the attachment state, and therefore all parts that are not actually visible are drawn with solid lines.

  In this embodiment, for signal incidence, the first sensor array 4 is formed at a predetermined angular interval in the circumferential direction on the outer periphery of the first diagnosis region R1 to be diagnosed of the heating furnace tube 1. The pulsar 2 and the three acoustic emission sensors 31 to 33 are arranged at a certain angular interval (with an angular interval of 90 degrees) in the circumferential direction of the heating furnace tube. 1, the signal incident pulser 2 and the acoustic emission sensors 31 to 37 are indicated by arrows. Further, the second sensor row 5 is formed at a predetermined angular interval in the circumferential direction on the outer periphery on the second diagnostic region R2 that is separated from the first sensor row 4 in the longitudinal direction of the heating furnace tube. As shown, four acoustic emission sensors 34 to 37 are arranged. Here, the first and second diagnostic regions R1 and R2 are virtual annular regions having a width dimension capable of completely disposing the acoustic emission sensor. In the present embodiment, a region between the first diagnostic region R1 and the second diagnostic region R2 is also a diagnostic region. The length dimension between the practical first diagnosis region R1 and the second diagnosis region R2 is 200 mm to 5000 mm.

  In this example, in the first sensor row 4, the three acoustic emission sensors 31 to 33 and the signal incident pulser 2 are attached to a common attachment jig 6, and the first diagnostic region It is attached to R1. Further, the four acoustic emission sensors 34 to 37 in the second sensor array 5 are also attached to the second diagnostic region R2 in a state of being attached to the common attachment jig 7. The mounting jigs 6 and 7 have any structure as long as the acoustic emission sensor and the signal incident pulser can be firmly fixed to the heating furnace tube 1 by one mounting operation. Also good.

The signal incident pulser 2 and the acoustic emission sensors 31 to 37 attached to the attachment jigs 6 and 7, respectively, project the waveguide rod 8 on the outer surface of the heating furnace tube 1 and enter the acoustic emission signal. It is a commercial product of the type that receives and receives.

  In the present embodiment, the signal incident pulser 2 is arranged on the outer periphery of the diagnostic region so as to be located in the first sensor row 4. It should be noted that the three acoustic emission sensors 31 to 33 and the signal incident pulser 2 constituting the first sensor array 4 need only be arranged at intervals in the circumferential direction of the heating furnace tube 1 and are completely linear. There is no need to line up. That is, these parts may be arranged in a zigzag shape or a zigzag shape. As shown in FIG. 3, in the present embodiment, the first sensor array 4 and the second sensor array 5 are handled as constituting one probe device 9. The signal incident pulser 2 outputs an acoustic emission signal in response to a command from the signal processing device 10, and the acoustic emission sensors 31 to 37 transmit the received acoustic emission signal to the signal processing device 10. The signal processing device 10 performs a calculation described later based on the received attenuated acoustic emission signal, and outputs the calculation result to the diagnosis device 11.

  When diagnosis is performed by the method of the present embodiment, an acoustic emission signal is incident on the first diagnosis region R1 from the signal incident pulser 2 based on a command from the signal processing device 10. From the outputs of the three acoustic emission sensors 31 to 33 constituting the first sensor array 4, the signal processing apparatus 10 is connected between the acoustic emission sensors 31 and 33 adjacent to the signal incident pulser 2. Decay rate of acoustic emission signal and attenuation of acoustic emission signal between two acoustic emission sensors adjacent in the circumferential direction (between acoustic emission sensors 31 and 32, between acoustic emission sensors 32 and 33) Calculate the rate.

  Here, the attenuation rate is, for example, the amplitude of the acoustic emission signal (for example, the acoustic emission signal itself output from the signal incident pulser 2), the acoustic emission energy, the upstream side of the path through which the acoustic emission signal propagates. A signal obtained by computing the amplitude of an acoustic emission signal, the acoustic emission energy, and the signal duration in the numerator, measured on the downstream side (for example, the acoustic emission sensor 31 or 33) in the denominator of the signal duration It is the ratio of strength. Accordingly, the attenuation factor at the position of the waveguide rod 8 of the signal incident pulser 2 is “1”, and the attenuation factor approaches “0” as the distance from the signal incident pulser increases.

  Further, the signal processing apparatus 10 uses the outputs of the four acoustic emission sensors 34 to 37 constituting the second sensor array 5 to generate four acoustic emission sensors constituting the signal incident pulser 2 and the second sensor array. The attenuation rate of the acoustic emission signal between each of the sensors 34 to 37 is calculated. In this case, the output of the signal incident pulser 2 is placed in the denominator, and the signals received by the acoustic emission sensors 34 to 37 are placed in the numerator.

  The inventor determines that the attenuation rate of the acoustic emission signal in a certain length range of the tube (either a certain length range in the circumferential direction of the tube or a length range in the longitudinal direction of the tube) is the inner wall of the length range. There is a negative correlation between the product value represented by the product of the thickness of the deposit adhering to the length and the length dimension of the length range (this value is also referred to as cumulative caulking thickness in this specification). I found out. FIG. 4 is a graph showing measurement results obtained by attaching an object corresponding to caulking to a test tube used as a heating furnace tube and changing the thickness and the amount of adhesion. Although the same test was performed on pipes having different diameters and materials, it was found that although the measured values were different, the same negative correlation as that shown in the graph shown in FIG. 4 was obtained. That is, there is a relationship between the product value (cumulative caulking thickness accumulation) and the attenuation rate, the larger the attenuation rate, the smaller the product value, and the smaller the attenuation rate, the larger the product value. This relationship does not change even if the kinds of various deposits including caulking are different, the tube material and dimensions are different, and the incident position of the acoustic emission signal is different. Therefore, if this relationship and the length dimension of the above-mentioned length range (distance between the two acoustic emission sensors) are known in advance, the attachment in the length range is based on the attenuation rate. The thickness of the kimono can be estimated. That is, if the attenuation rate is α, the product value [thickness of deposit (coking thickness) T × distance L between sensors] is V, and the distance between sensors is L, the following relational expression is established between them: To establish.

(V + L) = a × (α) ^−b + c
In the above formula, a, b, and c are constants. These constants vary depending on the properties of the deposit. Actually, if the tube to be diagnosed is a heating furnace tube, since coking adheres inside, a constant value suitable for coking is used. These constants can be obtained in advance. If these constants are determined, the thickness of the deposit can be estimated as a quantitative value from the above relational expression. If it is assumed that the above relational expression is established, even if it is an unknown deposit, the presence and thickness of the deposit can be relatively evaluated by using an appropriate constant.

  The estimation of the thickness dimension is an estimation of the average thickness of the deposit within the length range. And what is necessary is just to be able to presume as a thickness level (relative value) rather than a concrete thickness dimension. For example, when nothing is attached and 0 is set and the radius of the pipe is set to -10, if the thickness between them is divided into 10 stages, the thickness is estimated to be -1 or -3. The relative value of being in the range. In this case, if the value of the radius is determined, the 10-step relative value can be converted into the thickness dimension itself, so that it is of course possible to provide a quantitative display instead of the 10-step display. .

  On the premise of such a correlation, the signal arithmetic device 10 includes three acoustic emission units included in the first sensor array 4 arranged at an angular interval of 90 degrees in the circumferential direction of the heating furnace tube 1. The first diagnosis is performed without using the reference data by calculating the above-described attenuation rate based on the acoustic emission signal received by the sensors 31 to 33 and the acoustic emission signal output from the signal incident pulser 2. The change in the circumferential direction of the thickness of the deposit adhered inside the region R1 is estimated.

  Similarly, from the outputs of the four acoustic emission sensors 34 to 37 constituting the second sensor row 5, the acoustic emission sensors 34 to 37 constituting the signal incident pulser 2 and the second sensor row 4 are obtained. 37, the attenuation rate of the acoustic emission signal is calculated. In the diagnostic apparatus 11 of FIG. 3, under the assumption that there is a negative correlation between the distance between the two acoustic emission sensors and the product value of the thickness of the deposit between them and the attenuation rate, A change in thickness in the longitudinal direction of the heating furnace tube of coking between the first diagnosis region R1 and the second diagnosis region R2 is estimated from the attenuation rate in the second sensor array 5. And a diagnostic device diagnoses the condition of the deposit | attachment adhering in a heating furnace pipe | tube by these estimations.

  FIG. 5A shows the positional relationship between the signal incident pulser 2 and the eleven acoustic emission sensors 3a to 3k for explaining an example of an actual diagnosis method, and the direction of attenuation of the acoustic emission signal. FIG. 5B is a graph showing an example of the estimation result. The signal incident pulser 2 and the eleven acoustic emission sensors 3a to 3k are arranged at an angular interval of 30 degrees in the circumferential direction. The direction of the arrow shown in FIG. 5A indicates the direction in which the acoustic emission signal incident on the furnace tube 1 from the signal incident pulser 2 propagates. In this case, between the two adjacent acoustic emission sensors such as the attenuation rate between the signal incident pulser 2 and the acoustic emission sensor 3a and the attenuation rate between the acoustic emission sensors 3a and 3b. Twelve subtraction rates are calculated as the attenuation rate of the acoustic emission signal. These calculation rates are estimated from the relationship between the calculation rate as shown in FIG. 4 and the accumulated caulking thickness as the level of the caulking thickness between the sensors. FIG. 5B is a diagram showing the estimation result. In FIG. 5B, the thickness level calculated based on the attenuation rate between the signal incident pulser 2 and the sensor 3a is displayed as the coking thickness ranging from the 0 degree position to 330 degrees. And the caulking thickness between 330 and 300 degrees is shown at 300 degrees, the caulking thickness between 300 and 270 degrees is shown at 270 degrees, and between 270 and 240 degrees The caulking thickness of 240 degrees is indicated at a position of 240 degrees, the thickness of caulking between 240 degrees and 210 degrees is indicated at a position of 210 degrees, and the thickness of caulking between 210 degrees and 180 degrees is indicated at a position of 180 degrees. It was shown to. The reverse route is shown in the same way. In FIG. 5 (B), since the thickness dimension level at each angular position is connected by a line, by looking at the diagram of FIG. 5 (B), the change in the circumferential direction of the caulking pipe attached to the inside of the pipe Diagnose the situation. Note that in the acoustic emission sensor arranged directly behind the signal incident pulser 2, the propagation path is the same distance in the clockwise direction and the counterclockwise direction, so that the detection accuracy is lowered. Therefore, in order to further improve the accuracy, it is preferable to perform the evaluation a plurality of times by changing the incident point of the incident signal a plurality of times in the circumferential direction of the tube.

  In this embodiment, the acoustic emission sensors 34 to 37 arranged in the second sensor array 5 receive the acoustic emission signals incident from the signal incident pulser 2 arranged in the first diagnosis region R1. From the signal attenuation rate, the change in the thickness of the deposit in the longitudinal direction between the first diagnostic region R1 and the second diagnostic region R2 is estimated. As a result, it is possible to diagnose the state of deposits adhering to the inside of the tube between the first diagnostic region R1 and the second diagnostic region R2. The change in the thickness of the deposit in the longitudinal direction is the average of deposits at locations along a virtual line connecting the signal incident pulser 2 and the acoustic emission sensors 34 to 37 through the outer peripheral surface of the tube with the shortest distance. Can be seen as a typical thickness. The number of signal incident pulsers 2 provided in the first diagnosis region R1 is set to be plural and arranged at an appropriate interval in the circumferential direction, and an acoustic emission signal is individually incident from each signal incident pulser 2. Alternatively, estimation may be performed a plurality of times while changing the incident position, and a change in the thickness of the deposit in the longitudinal direction may be estimated from the plurality of estimations.

  The acoustic emission signal incident from the signal incident pulser 2 arranged in the first diagnostic region R1 is attenuated until it reaches a plurality of acoustic emission sensors arranged in the second diagnostic region R2. The relationship between the product value (cumulative thickness of caulking) and the attenuation factor shown in FIG. 4 is established both in the circumferential direction of the tube and in the longitudinal direction of the tube. Therefore, it is possible to know the state of change in coking thickness in the longitudinal direction between the first diagnostic region R1 and the second diagnostic region R2 calculated in the same manner as described above based on the attenuation rate. FIG. 6 is a diagram conceptually showing an estimated state of coking in the longitudinal direction inside the tube when the position of the signal incident pulser 2 is changed. In FIG. 6, the central area is the position of the signal incident pulser. The arrow directed to the diagnosis region R2 has acoustic emission sensors arranged at 0, 120, and 240 degrees in the diagnosis region R2, and signals are incident at 0, 120, and 240 degrees in the diagnosis region R1. The signal path (path for obtaining the average thickness of coking) when the signal is incident by sequentially moving the pulsar is shown. The arrow toward the diagnosis region R1 has acoustic emission sensors arranged at 0, 120, and 240 degrees in the diagnosis region R1, and signals are incident at 0, 120, and 240 degrees in the diagnosis region R2. The signal path (path for obtaining the average thickness of coking) when the signal is incident by sequentially moving the pulsar is shown. And the dimension display of the center area | region has shown the average thickness dimension of the chalking in the path | route shown by the arrow. For example, a thick arrow heading from a numerical value of 1.0 mm to the diagnostic region R2 is an acoustic signal that is input from a signal incident pulser disposed at a 0 degree position in the diagnostic region R1 and is disposed at a 0 degree position in the diagnostic region R2. When a signal is received by the emission sensor, the average value of the caulking thickness estimated in the path is shown. Similarly, a thick arrow from the third numerical value 1.0 mm from the top to 120 degrees in the diagnostic region R2, a thick arrow from the second numerical value 2.2 mm from the bottom of the central region to 240 degrees in the diagnostic region R2, When a signal is incident from a signal incident pulser disposed at a position of 120 degrees or 240 degrees in the diagnosis region R1, and the signal is received by an acoustic emission sensor disposed at a position of 120 degrees or 240 degrees in the diagnosis region R2. The average value of the caulking thickness estimated in the route is shown. In addition, one slanted thin arrow pointing from the numerical value of 1.5 mm in the central area to 120 degrees in the diagnostic area R2 makes a signal incident from a signal incident pulser arranged at a position of 0 degrees in the diagnostic area R1. When the signal is received by the acoustic emission sensor disposed at the position of 120 degrees R2, the average value of the caulking thickness estimated in the path between them is 1.5 mm. In addition, one slanted thin arrow heading from a value of 2.5 mm in the central area to 120 degrees in the diagnostic area R2 enters a signal from a signal incident pulser arranged at a position of 240 degrees in the diagnostic area R1, and the diagnostic area R2 When the signal is received by the acoustic emission sensor arranged at a position of 120 degrees, the average value of the thickness of the caulking estimated in the path between them is 2.2 mm. One oblique thin arrow heading from the central area value of 2.5 mm to 240 degrees in the diagnosis area R2 enters a signal from a signal incident pulser arranged at a position of 120 degrees in the diagnosis area R1, and the diagnosis area R2 When the signal is received by the acoustic emission sensor arranged at a position of 240 degrees, the average value of the caulking thickness estimated in the path between them is 2.5 mm. The interpretation of other arrows is the same.

  Diagnosis by the method of the present invention may be made visually by humans from the graphs shown in FIGS. 5B and 6, or may be diagnosed using a computer. By combining the evaluation in the circumferential direction shown in FIG. 5B and the evaluation in the longitudinal direction shown in FIG. 6, the determination accuracy of the adhesion state of the caulking in the longitudinal direction can be made high. Note that the graphs illustrated in FIGS. 5B and 6 are examples, and the display mode is arbitrary, and is not limited to the display mode of the present embodiment. In the present embodiment, risk conditions are set in advance, and if this risk condition is exceeded, the state of coking using a diagnostic method using radiation, such as a known radiation transmission density method, for the heating furnace tube Diagnose in detail. In this way, only the tube that really needs detailed diagnosis needs to be diagnosed in detail using the diagnostic method using radiation, so the diagnostic method using radiation is used. Thus, when a final diagnosis result is obtained, the number of diagnoses by a diagnostic method using radiation can be minimized. In the radiation transmission density method, a radiation source and a radiation detection sensor are arranged with a tube to be diagnosed in between, and a state inside the tube is diagnosed by a change in the radiation transmission density. In the radiation transmission test method using an imaging plate, an imaging plate is placed behind the tube, a radiation source is placed at a distance of about 600 mm in front of the tube, and the inside of the tube is placed on the imaging plate using the same principle as X-rays. Make a diagnosis by copying. The diagnostic method using radiation requires a special technique for handling radiation, and the diagnostic apparatus becomes expensive. Therefore, it is preferable to reduce the number of diagnoses as much as possible. In this embodiment, the entire length of the tube is diagnosed by the acoustic emission method. And since the diagnostic method using radiation is performed only on the tube diagnosed that the amount of internal coking exceeds the dangerous amount (predetermined risk condition is satisfied), The number of times the diagnostic method used can be greatly reduced. In addition, this dangerous condition can be defined as the case where the maximum dimension of the thickness of the deposit exceeds a predetermined level, for example.

  7A, 7 </ b> B, and 7 </ b> C, whether the caulking AM <b> 1 or sludge AM <b> 3 is adhered to the inside of the pipe or the process according to the diagnostic method of the present embodiment. A case where it is determined whether or not the fluid AM2 remains will be described. As shown in FIG. 7A, the position where the coking AM1 is formed is determined by the positional relationship with the flame F. That is, coking grows on the flame side. Further, the liquid process fluid AM2 and the sludge AM3 are accumulated at the bottom of the inside of the pipe by the action of gravity. Therefore, by looking at the estimation result shown in FIG. 5B, it is possible to determine whether or not the deposit is caulking from the position of the deposit growing inside the pipe. If it is determined that the deposit is the liquid process fluid AM2 or the sludge AM3, it is determined whether the deposit is the liquid process fluid AM2 or the sludge from the estimated thickness change pattern shown in FIG. It can be determined whether it is AM3. That is, in the case of the liquid process fluid AM2, the thickness is reduced on both sides in the circumferential direction, and the thickness is maximized at the center. On the other hand, in the case of the sludge AM3, no distinct feature appears in the change in thickness as in the case of the liquid process fluid AM2. Therefore, when a change in thickness other than the characteristic seen in the liquid process fluid AM2 is seen in the estimation result shown in FIG. 5B, it can be determined that the sludge is present.

  In the above embodiment, one signal incident pulser 2 is arranged in the first sensor array 4, but a plurality of units are provided at predetermined intervals such as 90 degree intervals and 180 degree intervals. A signal incident pulser may be arranged, and an acoustic emission signal may be sequentially incident on each signal incident pulser to obtain a plurality of data, and diagnosis may be performed based on the plurality of data. In addition, a signal incident pulser may be arranged in the second sensor array 5 to obtain data on the deposits in the circumferential direction in the second diagnosis region R2 to perform diagnosis.

  Moreover, in said embodiment, an acoustic emission sensor is arrange | positioned in two diagnostic area | regions R1 and R2 spaced apart in the longitudinal direction of the heating furnace tube 1, and it is about the whole area | region between two diagnostic areas. Although a diagnosis is performed, a sensor array including a signal incident pulser may be arranged in one diagnostic region so that only the state of the internal deposits along the circumferential direction in that region may be diagnosed. Of course.

  Further, a plurality of acoustic emission sensors and signal incident pulsers in the sensor array may be attached to the diagnosis region in a state where they are attached to a common attachment jig. In this way, since a plurality of acoustic emission sensors can always be mounted on the pipe under the same conditions, the occurrence of calculation errors based on mounting errors can be reduced.

  In order to facilitate the calculation, in the above embodiment, the distance between the acoustic emission sensors 31 to 33 in the first sensor array 4 and the two acoustic sensors adjacent to the signal incident pulser 2 are used. The distance between the emission sensors 31 and 33 is a fixed angle range (fixed distance), and the distance between the acoustic emission sensors 34 to 37 in the second sensor array 5 is also the first sensor. It is the same as the fixed angle range (fixed distance) in the row 4. Of course, the distance between the sensors may be different.

By using the present invention, the caulking and the residue (process fluid, sludge) adhering to the inside of the heating furnace tube arranged in the heating furnace are distinguished, and the circumferential direction and the longitudinal direction inside the predetermined region of the heating furnace pipe It is a figure used in order to explain the example in the case of diagnosing what kind of situation coking has adhered along both these directions. It is the figure which exaggerated one part and showed in simulation the specific arrangement | positioning state of the signal incident pulser actually arrange | positioned around a heating furnace pipe | tube, and several acoustic emission sensors. It is a figure which shows the structure of the apparatus used when enforcing the method of this invention. It is a graph which shows the relationship between the measured attenuation factor and accumulation of coking thickness by making the thing equivalent to coking adhere inside the pipe | tube for a test used as a heating furnace pipe | tube, and changing the thickness and adhesion amount variously. (A) is a figure which shows the positional relationship of the signal incident pulser for demonstrating an example of an actual diagnostic method, and several acoustic emission sensors, and the direction of attenuation | damping of an acoustic emission signal, (B) FIG. 4 is a graph showing estimation results. It is a figure which shows an example of the graph which can be utilized for the diagnosis of the change of the thickness of the coking in the longitudinal direction of a pipe | tube. (A), (B), and (C) indicate whether coking is adhered to the inside of the pipe, whether process fluid remains, or sludge is adhered to the inside of the pipe by the diagnostic method of the present embodiment. It is a figure used in order to explain the case where it judges.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating furnace tube 2 Signal incident pulser 31-37 Acoustic emission sensor 4 1st sensor row 5 2nd sensor row 6, 7 Mounting jig 8 Waveguide rod

Claims (8)

An in-pipe deposit diagnosis method for diagnosing the status of deposits in a tube
A plurality of acoustic emission sensors are arranged so as to form a sensor array at a predetermined angular interval in the circumferential direction on the outer periphery of the diagnostic region to be diagnosed of the pipe,
One or more signal incident pulsers are arranged on the outer periphery of the diagnostic region so as to be located in the sensor row,
An acoustic emission signal is incident on the diagnostic region from the signal incident pulser,
From the outputs of the plurality of acoustic emission sensors, the attenuation rate of the acoustic emission signal between the signal emission pulser and the adjacent acoustic emission sensor, and the two acoustic Calculate the decay rate of the acoustic emission signal between the emission sensor and
Based on the assumption that there is a negative correlation between the distance between the two acoustic emission sensors and the product of the thickness of the deposit between them and the attenuation rate, the diagnosis is made based on the attenuation rate. An in-pipe deposit diagnostic method characterized by diagnosing the status of the deposit attached to the pipe by estimating a change in thickness in the circumferential direction of the deposit in a region.   2. The distance between the plurality of acoustic emission sensors in the sensor array and the distance between the two acoustic emission sensors adjacent to the signal incident pulser are the same distance. 2. The method for diagnosing in-pipe deposits according to 1.   The plurality of acoustic emission sensors and the signal incident pulser in the sensor array are attached to the diagnostic region in a state of being attached to a common attachment jig. 3. The method for diagnosing in-pipe deposits according to 1 or 2. An in-pipe deposit diagnosis method for diagnosing the status of deposits in a tube
Arranging a plurality of acoustic emission sensors so as to form a first sensor array at a predetermined angular interval in the circumferential direction on the outer periphery of the first diagnosis region to be diagnosed of the pipe;
A signal incident pulser is arranged on the outer periphery of the diagnostic region so as to be located in the first sensor row,
A plurality of second sensor rows are formed at predetermined angular intervals in the circumferential direction on the outer periphery of the second diagnostic region at a predetermined distance from the first sensor row in the longitudinal direction of the tube. The acoustic emission sensor of
An acoustic emission signal is incident on the diagnostic region from the signal incident pulser,
From the outputs of the plurality of acoustic emission sensors constituting the first sensor array, the attenuation rate of the acoustic emission signal between the signal emission pulser and the adjacent acoustic emission sensor, and the circumference Calculate the attenuation rate of the acoustic emission signal between two acoustic emission sensors adjacent in the direction,
From the outputs of the plurality of acoustic emission sensors constituting the second sensor array, an acoustic sensor between the signal incident pulser and the plurality of acoustic emission sensors constituting the second sensor array is provided. Calculate the attenuation rate of the emission signal,
On the assumption that there is a negative correlation between the distance between the two acoustic emission sensors and the product value of the thickness of the deposit between them and the attenuation factor, the first sensor array A change in thickness in the circumferential direction of the deposit in the first diagnostic region is estimated from the attenuation factor in the first diagnostic region, and the first diagnostic region and the second diagnosis are estimated from the attenuation factor in the second sensor row. A method for diagnosing an in-pipe deposit, characterized by diagnosing the state of the deposit attached to the tube by estimating a change in thickness of the deposit in the longitudinal direction between the regions. The distance between the plurality of acoustic emission sensors in the first sensor array and the distance between the two acoustic emission sensors adjacent to the signal incident pulser are constant distances. ,
The in-pipe deposit diagnostic method according to claim 2, wherein a distance between the plurality of acoustic emission sensors in the second sensor array is the fixed distance. In the first sensor row, the plurality of acoustic emission sensors and the signal incident pulser are attached to a common attachment jig and attached to the first diagnostic region,
6. The plurality of acoustic emission sensors in the second sensor row are attached to the second diagnostic region in a state where the plurality of acoustic emission sensors are attached to a common attachment jig. 2. The method for diagnosing in-pipe deposits according to 1. An in-pipe deposit diagnosis method for diagnosing the state of coking attached to the furnace tube,
A plurality of acoustic emission sensors are arranged so as to form a sensor array at a predetermined angular interval in the circumferential direction on the outer periphery of the diagnostic region to be diagnosed of the heating furnace tube,
A signal incident pulser is arranged on the outer periphery of the diagnostic region so as to be located in the sensor row,
An acoustic emission signal is incident on the first diagnostic area from the signal incident pulser,
From the outputs of the plurality of acoustic emission sensors, the attenuation rate of the acoustic emission signal between the signal emission pulser and the adjacent acoustic emission sensor, and the two acoustic Calculate the decay rate of the acoustic emission between the emission sensor and
Based on the assumption that there is a negative correlation between the distance between the two acoustic emission sensors and the product of the thickness of the deposit between them and the attenuation rate, the diagnosis is made based on the attenuation rate. By estimating the change in thickness in the circumferential direction of the coking in a region, diagnose the state of the coking attached to the pipe,
Only when the coking situation in the furnace tube satisfies a predetermined risk condition, the caulking situation is diagnosed in detail by a diagnostic method using radiation on the pipe. Diagnosis method. An in-pipe deposit diagnosis method for diagnosing the state of coking attached to the furnace tube,
A plurality of acoustic emission sensors are arranged so as to form a first sensor array at a predetermined angular interval in the circumferential direction on the outer periphery of the first diagnostic region to be diagnosed of the furnace tube,
A signal incident pulser is arranged on the outer periphery of the first diagnostic region so as to be located in the first sensor row,
A plurality of second sensor rows are formed at predetermined angular intervals in the circumferential direction on the outer periphery of the second diagnostic region at a predetermined distance from the first sensor row in the longitudinal direction of the tube. The acoustic emission sensor of
An acoustic emission signal is incident on the first diagnostic area from the signal incident pulser,
From the outputs of the plurality of acoustic emission sensors constituting the first sensor array, the attenuation rate of the acoustic emission signal between the signal emission pulser and the adjacent acoustic emission sensor, and the circumference Calculate the attenuation rate of the acoustic emission signal between two acoustic emission sensors adjacent in the direction,
From the outputs of the plurality of acoustic emission sensors constituting the second sensor array, an acoustic sensor between the signal incident pulser and the plurality of acoustic emission sensors constituting the second sensor array is provided. Calculate the attenuation rate of the emission signal,
On the assumption that there is a negative correlation between the distance between the two acoustic emission sensors and the product value of the thickness of the deposit between them and the attenuation factor, the first sensor array A change in thickness in the circumferential direction of the coking in the first diagnostic region is estimated from the attenuation factor in the first diagnostic region, and the first diagnostic region and the second diagnostic region are estimated from the attenuation factor in the second sensor array. By estimating the change in thickness in the longitudinal direction of the coking between and the diagnosis of the state of the deposits adhering in the furnace tube,
Only when the coking situation in the furnace tube satisfies a predetermined risk condition, the caulking situation is diagnosed in detail by a diagnostic method using radiation on the pipe. Diagnosis method.

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