JP6840026B2 - Heat exchanger abnormality diagnosis method, abnormality diagnosis system, and its control device - Google Patents

Description

The present invention evaluates the heat balance of the heat exchanger provided in the plant in various plants such as industrial, chemical and power generation equipped with the heat exchanger, and diagnoses the presence or absence of abnormality in the heat exchanger. The present invention relates to an abnormality diagnosis method, an abnormality diagnosis system, and a control device thereof.

A heat exchanger is a device that transports heat energy by heat transfer between two types of fluids (heat mediums), and a pipe through which one fluid flows into a flow path such as a pipe or duct through which the other fluid flows. To install. As a result, the fluid on the low temperature side is heated, the liquid is evaporated and converted into vapor, and conversely, the hot fluid is cooled, and the vapor is condensed and converted into liquid. There are different types of heat exchangers, such as plate type, tube type, and regenerative type, and the arrangement of fluid piping differs depending on the type. Generally, when designing a heat exchanger, an appropriate model is selected in consideration of various conditions such as the amount of heat to be transferred, the temperature, pressure, flow velocity and phase (liquid, gas) of the fluid to be exchanged.

In a heat exchanger, when the amount of heat transferred by the heat exchanger is large, it is necessary to design a large contact area (called a heat transfer area) between the pipes flowing through each fluid. Further, the heat exchanger that handles gas needs to be designed to have a larger contact area than the heat exchanger between liquids. This is because the heat capacity per unit volume of gas is smaller than that of liquid. In a heat exchanger that has a large amount of heat transfer and handles gas, one heat exchanger reaches a scale of several tens of meters, and a pipe through which a fluid flows is arranged so as to bend to secure a contact area. Therefore, in heat exchangers that handle high-temperature combustion gas and superheated steam, there is a risk of deformation and rupture due to creep, and thinning of piping due to wear and corrosion. This is because it is installed under thermally severe conditions for high temperature and high pressure fields and piping materials, the combustion gas may contain dust and corrosive components, and the flow velocity of the combustion gas and superheated steam is locally high. Due to the fact that it may become.

As described above, ensuring the heat transfer performance and reliability of the heat exchanger having a large and complicated shape is indispensable for the stable operation of the entire plant. Therefore, there is a demand for a technique for not only evaluating the heat transfer performance of the heat exchanger but also detecting damage to the piping of the heat exchanger at an early stage.

For example, in Patent Document 1, a plurality of heat exchangers that superheat water and steam are installed in series in the flow path of the combustion exhaust gas, and the heat transfer characteristics of each heat exchanger are individually calculated by a one-dimensional model calculation. The method for diagnosing heat exchanger abnormalities is described in which the calculation results are compared with the measured data, and the difference between the two is monitored to detect the abnormality of the heat exchanger.

Further, Patent Document 2 describes an abnormality diagnosis method for accelerating the detection of an abnormality in a plant by monitoring the transition of the correlation of a plurality of parameters measured in the plant and comparing it with a database accumulating past operation histories. There is. In addition, for the correlation diagnosed as abnormal, a step of extracting the abnormal phenomenon registered in the database in advance in association with the contribution of the related parameters is provided, and the abnormality diagnosis method for identifying the abnormal phenomenon is also described. ..

Japanese Patent No. 3690992 Japanese Unexamined Patent Publication No. 2017-0627030

In the present invention, the heat transfer performance of the heat exchanger is conventionally improved in various plants such as industry, chemicals, and power generation that handle large heat exchangers with complicated piping shapes and systems by using actual measurement data with a limited number of measurement points. The purpose is to construct a heat exchanger abnormality diagnosis system that can evaluate the damage with high accuracy, detect damage to pipes, etc. at a minor stage, and identify the location and cause of the damage at an early stage. For this purpose, one heat exchanger is divided into a plurality of blocks, and the heat transfer performance (that is, the amount of heat absorption) of each block is evaluated.

The problem to be solved by the present invention is to use actual measurement data such as temperature, flow rate (or flow velocity), and pressure measured at a limited number of points to balance not only the entire heat exchanger but also the individual heat balance of each block. Is to evaluate. In existing plants, it may be limited to the minimum measurement points required for operation, and it is assumed that the actual measurement data (temperature, flow rate, pressure, etc.) required to evaluate the heat balance of each block are not available. Will be done. Therefore, it is necessary to estimate the insufficient actual measurement data.

In addition, the main causes of damage to the heat exchanger piping include creep due to overheating, wear due to collision of particles contained in the combustion gas, and corrosion due to sulfur and alkaline components (for example, Na, K, Cl, etc.). .. Of these, for creep due to overheating of the pipe, the heat history of the pipe material can be evaluated by estimating the surface temperature of the pipe of the block in the above-mentioned evaluation of the heat balance. It is necessary to incorporate the step of evaluating the thermal history of the pipe and the step of evaluating the remaining life of the pipe material from the viewpoint of creep due to overheating into the above-mentioned heat exchanger abnormality diagnosis system.

In relation to the above-mentioned problems to be solved by the present invention, Patent Document 1 evaluates the overall heat transfer characteristics of one heat exchanger by calculation, compares the calculation results with the actually measured data, and differs between the two. The abnormality diagnosis method to monitor is described. However, the concept of dividing the heat exchanger itself into a plurality of blocks is not described, and the purpose is to diagnose the presence or absence of an abnormality in the entire heat exchanger.

Further, Patent Document 2 describes an abnormality diagnosis method for accelerating the detection of an abnormality in a plant by monitoring the transition of the correlation of a plurality of parameters measured in the plant and comparing it with a database accumulating past operation history, and diagnosing the abnormality. An abnormality diagnosis method for identifying an abnormality phenomenon from the contribution of parameters related to the obtained correlation is also described. However, the concept of inferring the insufficient measured data, the concept of identifying the abnormal site, and the concept of diagnosing the remaining life of the material are not mentioned. Therefore, it is considered that the present patent document is an invention whose main purpose is to prevent the recurrence of past accident cases, only by comparing the measured data with the operation history accumulated in the past.

As described above, in Patent Document 1 and Patent Document 2, a complicated and large-sized device such as a heat exchanger is divided into a plurality of blocks, and the performance such as heat balance is evaluated with high accuracy to prevent pipe damage and the like. There is no mention of the concept of detecting anomalies at a minor stage and identifying the location of the anomaly and its cause at an early stage. In addition, the concept of estimating the insufficient measured data and the concept of predicting the occurrence of abnormalities by diagnosing the remaining life of the material are not mentioned.

From the above, in the present invention, "a method for diagnosing an abnormality in a heat exchanger that exchanges heat between heat media, and using sensors installed in each part of the heat exchanger. Based on the data of, the heat absorption amount of the heat medium in the heat exchanger is obtained, the heat exchanger is divided into a plurality of blocks, the heat absorption amount of the heat medium is obtained in each block unit, and the heat exchanger and each block unit are obtained. This is a method for diagnosing abnormalities in heat exchangers, which is characterized by evaluating the amount of heat absorption of the heat exchanger using a reference value. "

Further, the present invention relates to "the temperature of the heat medium at the inlet of the heat exchanger, the temperature of the heat medium at the outlet of the heat exchanger or the metal temperature of the flow pipe of the heat medium, and the flow rate of the heat medium or the system in which the heat medium circulates. In this case, the amount of heat absorbed by the entire heat exchanger is determined using the flow rate of the replenished heat medium, and for each block in which the heat exchanger is divided, the temperature of the heat medium at the block inlet, the temperature of the heat medium at the block outlet, or heat. The heat absorption amount of each block is calculated using the metal temperature of the medium flow pipe and the flow rate of the heat medium or the flow rate of the replenished heat medium in the case of a system in which the heat medium circulates. A method for diagnosing abnormalities in heat exchangers, which comprises evaluating the amount of heat absorption using a reference value. "

Further, the present invention is "an abnormality diagnosis system of a heat exchanger composed of a data acquisition unit for capturing actual measurement data from various sensors installed in a heat exchanger to be monitored and a computer, and the computer inputs. It is composed of a unit, an output unit, a calculation unit, and a storage unit as main components. It obtains input information input by an operator or the like in the input unit, displays it on the screen in the output unit, and displays various programs and various data in the storage unit. The calculation unit has a data input processing function using a data acquisition unit that captures actual measurement data from various sensors installed in the heat exchanger to be monitored, and heat exchange based on the input information from the input unit. Evaluate the block division processing function that divides the structure of the vessel into blocks, the heat transfer performance evaluation diagnostic processing function of the entire heat exchanger that evaluates the heat transfer performance of the entire heat exchanger, and the heat transfer performance of each divided block. A heat exchanger abnormality diagnosis system characterized by including a block heat transfer performance evaluation diagnosis processing function. "

Further, the present invention is "a heat exchanger control device that controls a heat exchanger using information from a heat exchanger abnormality diagnosis system, and the heat exchanger control device is a heat exchanger abnormality diagnosis. Based on the abnormality diagnosis signal that is the guideline given by the system, various valves of each part of the heat exchanger are operated, and in the abnormality diagnosis system of the heat exchanger, the remaining life of the piping of any block of the heat exchanger is short. When a command is issued to reduce the temperature of the high-temperature side fluid flowing into the block, various valves are operated in order to reduce the temperature of the high-temperature side fluid flowing into the block. The control device for the heat exchanger. "

According to the present invention, it is possible not only to prevent the recurrence of abnormal events that have occurred in the past, but also to detect equipment abnormalities caused by various assumed abnormal events, and to identify the location of occurrence and its factors at an early stage.

According to the embodiment of the present invention, a device having a large and complicated system such as a heat exchanger provided in various plants such as industrial, chemical and power generation is divided into a plurality of blocks, and a device such as a heat absorption amount is obtained. By evaluating the performance of each block, it is possible not only to detect equipment abnormalities such as pipe damage at a minor stage, but also to identify the location of the abnormality and its cause at an early stage. If the actual measurement data is insufficient in evaluating the device performance for each block, it can be estimated from other data.

Further, according to the embodiment of the present invention, the metal temperature of the fluid pipe in the block can be estimated from the heat absorption amount evaluated for each block, and the change of the metal temperature with time can be monitored. By evaluating the thermal history of the piping material, for example, it is possible to evaluate the remaining life of the piping material from the viewpoint of creep due to overheating, and to predict an abnormal event that is expected due to deformation or rupture due to creep.

The figure which shows an example of the system and the measurement point of a tube type heat exchanger. The front view of the heat transfer tube group on the outlet side of the heat medium flowing through the tube heat exchanger of FIG. 1. The figure which shows an example of the temperature measurement point on the outlet side of the heat exchanger divided into four blocks. The figure which shows an example of the temperature distribution for each block of a heat exchanger. The figure which shows an example of the time-dependent change of the heat absorption amount of the whole heat exchanger and each block. The figure which shows an example of the temperature measurement point on the outlet side of the heat exchanger divided into 6 blocks. The figure which shows an example of the temperature distribution for each block of a heat exchanger using the measured data and the estimated value. The figure which shows an example of the time-dependent change of the heat absorption amount of the whole heat exchanger and each block using the measured data and the estimated value. The figure which shows an example of the database which diagnoses the life of a piping material. The figure which shows an example of the monitor display screen of the control device of the plant which implemented the abnormality diagnosis system of the heat exchanger of this invention.

Hereinafter, the abnormality diagnosis method, the abnormality diagnosis system, and the control device for the heat exchanger of the present invention will be described based on the illustrated examples.

In the first embodiment, the basic concept of the abnormality diagnosis method of the heat exchanger according to the present invention will be described.

FIG. 1 shows an example of a system and measurement points of a tube heat exchanger as an example of a heat exchanger. Further, FIG. 2 is a front view of a group of heat transfer tubes on the outlet side of the heat medium flowing through the tube heat exchanger shown in FIG. 1, and shows an example of a measurement point for temperature monitoring on the outlet side.

In FIG. 1, the heat medium 2 flows into the duct 1 of the heat exchanger 100 at a high temperature, and the heat medium 3 circulating in the heat transfer tube 5 is heated to a high temperature. The heat medium 2 whose sensible heat has decreased flows out from the duct 1 and flows into the equipment on the downstream side. The temperature of the heat medium 2 is monitored at two locations before and after the heat transfer tube 5. The upstream temperature T _f1-in is measured by the thermometer 11 of the heat medium 2 at the duct inlet, and the downstream temperature T _f1-out is measured by the thermometer 12 of the heat medium 2 at the duct outlet. Although not shown in this figure, the measurement points related to the pressure, flow rate, and composition of the heat medium 2 can use the data measured by the measuring instrument installed on the upstream side of the heat exchanger 100, or the measuring instrument can be installed in the duct 1. It is good to install and acquire data. If the temperature and flow rate of the heat medium 2 at the entrance and exit of the duct 1 and the amount of heat radiated from the duct 1 are known, the amount of heat transfer to the heat medium 3 in the entire heat exchanger 100 can be obtained.

Here, the heat medium 2 flowing in the duct 1 is disturbed, or the temperature of the heat medium 2 near the wall surface is lowered due to the influence of heat radiation to the outside of the duct 1. The temperature distribution of is often non-uniform. Further, impurities contained in the heat medium 2 (for example, particles, scales, recondensed volatile inorganic substances, etc.) may locally adhere to, grow, or peel off from the heat transfer tube 5, and the heat medium 2 to the heat medium 3 The amount of heat transfer also fluctuates irregularly. Further, the heat medium 3 may also contain impurities (for example, foreign matter, particles, scale, etc.), and it branches into many systems to reduce the diameter and becomes a flow path resistance in the heat transfer tube 5 having a complicated piping shape. If the flow rate of the heat medium 3 decreases, it is possible that the heat transfer tube 5 at that location will locally heat up.

From the above, it is important not only to grasp the heat transfer performance of the heat exchanger 100, but also to monitor the presence or absence of an abnormality, detect the abnormality at an early stage, and identify the location where the abnormality occurs in the entire plant including the heat exchanger 100. It is indispensable for stable operation, repair period and cost reduction.

Therefore, it is indispensable to measure the pressure, temperature (gas temperature, steam temperature) and flow rate of the heat medium 3 flowing through the heat transfer tube 5 and evaluate and monitor the heat absorption amount of the heat medium 3 in the heat exchanger 100. The amount of heat absorbed by the entire heat exchanger 100 is obtained from the following actually measured data installed in the header pipe 4 on the inlet side of the heat medium 3 and the header pipe 6 on the outlet side of the heat medium 3.
_-Pressure P f2 measured by the pressure gauge 7 of the heat medium 3 in the inlet header piping
_-Flow rate measured by the flow meter 8 of the heat medium 3 in the header pipe on the inlet side Q f2: (If flow rate measurement is difficult, it may be obtained from other measured data such as flow velocity and differential pressure. Further, the heat medium 2 circulates. In the case of a system that does, the flow rate, temperature, and pressure of the heat medium 2 supplied to the system may be required.)
-Temperature measured by the thermometer 9 of the heat medium 3 in the header piping on the inlet side T _{f2-in
-The temperature T f2-out} measured by the thermometer 10 of the heat medium 3 in the header piping on the outlet side.
Further, in the heat transfer tube 5 near the outlet side header pipe 6 of the heat medium 3, a plurality of metal thermometers 13 to 16 of the heat transfer tube of the heat medium 3 as shown in FIG. 2 are installed, and each of them has a metal temperature _TM1. ~ _TM4 may be measured, and efforts are being made to detect the presence or absence of abnormalities by detecting a local increase or decrease in temperature. Although not shown in this embodiment, it is obvious that it is desirable to measure the fluid temperature of the heat medium 3 flowing through the heat transfer tube if possible. In the present invention, by utilizing these existing metal temperature T _M1 through T _M4, the heat transfer tube 5 which branches into multiple lines is divided into a plurality of blocks, evaluating the heat absorption amount of the heat medium 3 of each block and Monitor. As a result, the abnormality of the heat transfer tube 5 is detected at an early stage from the change in the amount of heat absorption for each block.

3, as an example of division into blocks of Figure 2, in order to take advantage of metal temperature T _M1 through T _M4 measured at metal temperature gauge 13 to 16 of the existing four places, and measurement point when divided into four blocks Shows the positional relationship of. The representative temperature of the heat medium 3 flowing through each of the heat transfer tube 5 of the block 1-4, obtained by heat transfer calculation based on than the thermal conductivity calculated metal temperature T _M1 through T _M4 above. Incidentally metal temperature T _M1 through T _M4 is outside the duct 1 of the heat exchanger 100, and often installed in the outer surface of the heat transfer tube 6. In this case, the representative temperature of the heat medium 3 is theoretically higher than the metal temperature of the block.

4 shows an example of the distribution of the instantaneous value of the representative temperature of the heating medium 3 obtained in heat transfer calculations from metal temperature T _{M1 through T M4,} and these metal temperature of each block divided in Fig. According to FIG. 4, representative temperature of the metal temperature T _{M1, T M4,} and the heat medium 3 obtained in heat transfer calculated from these metal temperature in the block 1,4 in the side of the duct 1 of the heat exchanger 100, It tends to be lower than the representative temperature of the metal temperature _{T M2,} T _M3, and the heat medium 3 obtained in heat transfer calculated from these metal temperature in the block 2 and 3 of the central portion of the duct 1 of the heat exchanger 100. Also as shown in FIG. 3, since the metal thermometer 13-16 of 4 points show the case that is located outside of the duct 1 of the heat exchanger 100, metal temperature _T M1 _{through T M4} is the heat transfer tube The case where the temperature becomes lower than the representative temperature of the heat medium 3 inside 6 is shown.

In Figure 4, a further metal temperature T _{M1 through T M4,} and serving as a reference standard temperature of these metal temperature in order to determine the presence or absence of abnormality of the representative temperature of the heating medium 3 obtained in heat transfer calculations (critical temperature) The following two indicators are listed. One reference temperature as an index is a temperature T _f2-out measured by the thermometer 10 of the heat medium 2 at the outlet side header pipe, the lower limit of the metal temperature T _M1 through T _M4 of each one of the other blocks Value (normal).

By comparison with these indexes, if the representative temperature of the heat medium 3 of each block _{is higher than the temperature T f2-out} measured by the thermometer 10, the heat transfer tube 5 of the block is exposed to a high temperature field. Therefore, it is possible to predict and evaluate the possibility that the remaining life of the heat transfer tube 5 is shortened due to creep rupture due to heat.

On the other hand, metal temperature T _M1 through T _M4 of each block, if the lower limit value of the normal for each or the heat transfer tube, decrease in heat absorption by the deposits grow into the heat transfer tube 5 of the block, It is conceivable that the heat absorption amount is reduced due to the heat medium 3 leaking to the outside (for example, in the duct 1) due to the damage of 5. For the former growth of deposits, it is effective to inject compressed gas at high speed (such as soot blow) to remove the deposits, or to give vibration or impact with a knocker or the like. For the latter leakage of the heat medium 3, it is necessary to detect the leakage at an early stage, stop the plant, repair the leaked part, or replace the heat transfer tube.

In FIG. 4, the heat transfer tube 5 is divided into a plurality of blocks, and the temperature of the heat medium 3 or the metal temperature of each block is described together with an index as a reference for determining the presence or absence of an abnormality. Is described from the viewpoint of evaluating and monitoring the amount of heat absorbed in the heat exchanger. FIG. 5 describes an example of time-dependent changes in the amount of heat absorbed in the entire heat exchanger and each block, together with an index used as a reference for determining the presence or absence of an abnormality. The reference index is the normal lower limit for the entire heat exchanger and each block.

In order to improve the detection accuracy of the above-mentioned abnormal signs and the assumed events for these signs, it is important to grasp the evaluation result of the heat absorption amount as shown in FIG. 5 as a change with time. The heat absorption of the entire heat exchanger is used to evaluate the heat transfer characteristics of the heat exchanger according to the operating conditions of the plant, and to monitor and evaluate the finish of the heat exchanger. For this reason, it is advisable to display the lower limit value at the normal time determined from the past operation results and use it as a judgment index.

Furthermore, the change over time in the amount of heat absorbed for each block is also displayed. In this embodiment, the representative temperature of the heat medium 3 for each block is obtained by heat transfer calculation from the measured value of the metal temperature, but there is no actual measurement data of the flow rate of the heat medium 3 for each block. .. In this embodiment, the piping of the heat medium 3 is supplied and recovered in a header manner. In such a system, first, assuming that the flow rates of the heat media 3 flowing through the heat transfer tubes 5 are all the same, the flow rate per one is obtained, and the heat of each block is multiplied by the number of the heat transfer tubes 5 of each block. It is good to estimate the flow rate of the medium 3. It is preferable to display the change with time of the heat absorption amount of each block obtained by such a procedure, and also display the lower limit value at the normal time determined from the past operation results as a judgment index for diagnosing the presence or absence of abnormality. Blocks the presence or absence of abnormalities in the heat transfer tube 5 of the heat exchanger 100 in such a way that the heat absorption amount tends to increase and is higher than other blocks, or the heat absorption amount tends to decrease and is lower than the above lower limit value. It can be diagnosed for each.

In addition, when describing the temperature of the heat medium 3 or the metal temperature together with the index used as a reference for determining the presence or absence of abnormality in FIGS. 4 and 5, these indexes depend on the past operation results and the heat load. Should be set variably. Therefore, it is advisable to prepare a database for index setting and determine the index while referring to it sequentially. The table in the database is configured by storing the temperature or heat absorption amount in the past operation results for each heat load for the heat exchanger and its block. Further, in this table, it is preferable that the amount and components of solids (ash, etc.) contained in the heat medium 2 are also stored as reference information. As for the temperature or heat absorption amount in the past operation results for each heat load, the value diagnosed as normal operation is stored, and the index used as a reference for determining the presence or absence of abnormality is the upper limit and lower limit of the normal range. The value is set as appropriate.

By applying the heat exchanger abnormality diagnosis method according to the present invention described above, equipment abnormalities such as pipe damage of heat exchangers of large and complicated systems provided in various plants such as industry, chemistry and power generation can be minor. It is possible not only to detect at various stages, but also to identify the location of the abnormality at an early stage and estimate the cause of the abnormality.

In the first embodiment, the method for diagnosing an abnormality of the heat exchanger will be described on the premise that when the heat exchanger is divided into a plurality of blocks, the temperature can be measured in each block (the measuring instrument is installed). However, in general, the block may be divided so as to include a block whose temperature cannot be measured. In the second embodiment, a case where a block whose temperature cannot be measured is included will be described.

FIG. 6 shows an example of the temperature measurement points on the outlet side when the heat exchanger is divided into six blocks. Further, FIG. 7 shows an example of the distribution of the metal temperature for each block and the representative temperature of the heat medium 3. FIG. 8 shows an example of the change over time in the amount of heat absorbed. The first embodiment is the case where the heat exchanger is divided into four blocks, while the second embodiment is the case where the same heat exchanger is divided into six blocks. A part different from the first embodiment will be described.

First, the temperature measurement points of the outlet temperature for each block will be described with reference to FIG. Block 1, Block 3, Block 4, the block 6, the metal thermometers 13-16 of the heat transfer tube of the heat medium 3 is placed, which measures the metal temperature _T M1 _{through T M4,} respectively. On the other hand, the metal thermometer of the heat transfer tube of the heat medium 3 is not installed in the blocks 2 and 5. Therefore, in order to evaluate the metal temperature of each block, it is necessary to estimate the metal temperature of the blocks 2 and 5.

In the abnormality diagnosis method of the second embodiment, in order to estimate the metal temperature of the insufficient blocks 2 and 5, first, the total amount of heat absorption of the blocks 2 and 5 is estimated. As this estimation method, it is preferable to reduce the heat absorption amount of the other blocks (block 1, block 3, block 4, block 6) for which the measured data are collected from the heat absorption amount of the entire heat exchanger. Next, for the estimation of the heat absorption amount of each of the block 2 and the block 5, for example, it is preferable to use an approximate expression formulated by interpolation or extrapolation from the distribution of the heat absorption amount of the other blocks. Using the heat absorption amounts of blocks 2 and 5 obtained by such estimation, the flow rate of the heat medium 3 flowing through each block obtained by the method described in Example 1 and the thermometer of the heat medium 3 in the inlet side header pipe. If the measured temperature T _f2-in is taken as the inflow temperature of the heat medium 3, the temperature of the heat medium 3 at each block outlet can be estimated.

In these estimates, it is preferable to use FIG. 7 showing the temperature distribution of the heat medium 3 at the outlet of each block and FIG. 8 showing the change over time in the amount of heat absorbed. In FIG. 7, the temperature of the heat medium 3 of the block 2 and the metal temperature are obtained by interposition as intermediate values of the temperature of the heat medium 3 of the block 1, the temperature of the metal temperature and the temperature of the heat medium 3 of the block 3, and the metal temperature. The temperature of the heat medium 3 of the block 5 and the metal temperature were obtained by interposition as intermediate values between the temperature of the heat medium 3 of the block 4, the temperature of the metal temperature and the temperature of the heat medium 3 of the block 6, and the metal temperature. is there. Further, in FIG. 8, the time transition of the heat absorption amount of the blocks 2 and 5 obtained by estimation is shown by a dotted line together with an index as a reference thereof.

In this embodiment, the case where the sensor to be measured is not installed has been described as the case where the measured data is insufficient, but it is preferable to estimate by the same method when the installed sensor itself has an instrument abnormality.

It is also possible to estimate the maximum value of the metal temperature of the heat transfer tube in the block from the amount of heat absorbed evaluated for each block. It is also possible to evaluate the thermal history from the change over time of the metal temperature, and evaluate the remaining life of the piping material from the viewpoint of creep due to overheating as shown in FIG. 9, for example. Note that FIG. 9 shows the relationship between the stress for each temperature (vertical axis) and the breaking time (horizontal axis), and the metal temperature for each block obtained in Examples 1 and 2 is the past stress in the block (vertical axis). It is possible to estimate the fracture time until the metal in the block breaks in relation to the mechanical stress during manufacturing and the thermal stress during operation).

As described above, by applying the abnormality diagnosis system using the heat exchanger diagnostic method of the present invention, the piping damage of the heat exchanger of a large and complicated system provided in various plants such as industrial, chemical and power generation is damaged. It is possible not only to detect equipment abnormalities such as those at a minor stage, but also to identify the location of the abnormality at an early stage and estimate the cause of the abnormality.

In particular, if the number of block divisions is increased by estimating the insufficient measured data, the resolution at the time of abnormality detection can be increased. Further, by evaluating the heat history of the heat transfer tube in the block estimated from the heat absorption amount of each block, it is possible to evaluate the remaining life of the piping material from the viewpoint of creep due to overheating, for example. Preventive maintenance of equipment is also possible by predicting abnormal events such as deformation and rupture due to creep.

In the third embodiment, the configuration of the output unit, which is an indispensable element for constructing the abnormality diagnosis system using the abnormality diagnosis method of the heat exchanger of the present invention, will be described. The output unit described here is the screen of the monitor, and the operator judges the display content displayed on the monitor screen, operates from the input unit and reflects it on the monitor screen, or contributes to various judgments in the abnormality diagnosis system. It is intended for use as a monitor. Here, it will be described that various state quantities such as the metal temperature, the temperature of the heat medium 3, and the heat absorption amount obtained for each block are displayed on the monitor screen.

FIG. 10 shows an example of a monitor screen for monitoring the performance of the heat exchanger and the presence or absence of an abnormality in the control device of the plant equipped with the heat exchanger abnormality diagnosis system described in the first and second embodiments.

In the monitor screen display example of FIG. 10, six types of display screen examples are shown on the left, right, center, and top and bottom. Of these, the upper three screens and the lower center display example are described in Examples 1 and 2. Since it has already been done, the explanation of the displayed contents is omitted.

In the screen example at the lower left of FIG. 10, the diagnosis result of the heat exchanger is written in characters. For example, the operation status of each heat medium, the evaluation status of the heat absorption amount for each block, the soundness of the heat transfer tube, the comprehensive evaluation and the contents of future operational proposals are visualized and displayed. In the screen example at the lower right of FIG. 10, real-time data, accumulated data, the result of diagnosing the remaining life of the heat transfer tube, and the like are displayed in a tabular format in comparison. These display screens can be displayed as a single screen or can be displayed while writing multiple screens together, and the content to be conveyed to the user at that time is the heat exchanger body, internal state, and so on. It is advisable to devise so that it is displayed as appropriate in a format that can be comprehensively grasped together with various evaluation results.

For example, on the screen for monitoring the performance of the heat exchanger and the presence or absence of abnormalities, the system of the heat exchanger (upper left in FIG. 10), the schematic diagram of the measurement points (upper center in FIG. 10), and the blocks divided in the heat exchanger are displayed. It is good to show. Measured data such as pressure, temperature, flow velocity (or flow velocity) measured at the above measurement points, and data obtained by estimation of data at locations where measurement is not possible due to non-installation of measuring equipment or failure of measuring equipment, etc. It is better to show it as a list.

Further, it is effective to obtain the heat absorption amount of the entire heat exchanger and each block based on the data obtained by these actual measurements and estimates, and show the change over time (upper right of FIG. 10). By grasping the change in the amount of heat absorption for each block, the tendency of deterioration of heat transfer performance due to abnormal events such as growth of deposits on the heat transfer tube and damage to the heat transfer tube can be detected at an early stage, and the block in which the abnormal event occurs. To identify. By detecting the abnormality at a minor stage and identifying the location where the abnormality occurred, the repair cost of the heat exchanger can be reduced and the operating rate of the plant can be improved.

In addition, in order to improve the detection accuracy of abnormal events such as growth of deposits on the heat transfer tube and damage to the heat transfer tube, it is preferable to utilize the past operation data extracted from the operation history database. Therefore, on the screen for monitoring the performance of the heat exchanger and the presence or absence of abnormality (lower left of FIG. 10), it is preferable to clearly indicate the measured and estimated data and the normal range with similar operating conditions extracted from the operation history database. It is advisable to compare the actual values extracted from the operation history database with the data obtained by real-time actual measurement and estimation, and display the diagnosis result of normal or abnormal.

Further, in order to prevent damage to the heat transfer tube, it is effective to diagnose the remaining life of the heat transfer tube. Measures to protect the heat transfer tube of the heat transfer tube by extracting the block with high risk of damage of the heat transfer tube from the remaining life of the heat transfer tube diagnosed by comparing with the piping material database of the heat transfer tube and the above data and the remaining life. It is advisable to display the proposal on the screen (lower right of FIG. 10). By equalizing the remaining life of the heat transfer tubes in each block and stopping the plant before the heat transfer tubes are damaged, that is, before an abnormality occurs in the heat exchanger, secondary damage caused by the heat transfer tube damage is also prevented. Further, in this embodiment, assuming creep breakage due to overheating, an example of the diagnosis result (lower left in FIG. 10) with reference to the piping material database of the heat transfer tube for time, stress and temperature as shown in FIG. 9 is shown. However, a database of materials for other hypothetical events such as corrosion and wear should also be used as needed.

In this way, on the monitor screen of the heat exchanger abnormality diagnosis system, the system and measurement points of the heat exchanger, the data measured at the measurement points, the points where the measurement equipment is not installed or the measurement equipment is defective, and the measurement is insufficient. Data estimated from measurement data, data obtained by actual measurement and estimation when the operating conditions extracted from the operation history database are similar, remaining life of the heat transfer tube diagnosed by comparing with the heat transfer tube piping material database, and the above data And a block with a high risk of damage to the heat transfer tube can be extracted from the remaining life, and a countermeasure plan for protecting the heat transfer tube of this extracted block can be displayed.

As described above, by comparing the real-time operation data with the normal data accumulated in the operation history database, the abnormality of the heat exchanger can be detected at an early stage, and the location where the abnormality occurs can be specified in block units. In addition, by collating the time-dependent changes in real-time operation data with the piping material database and diagnosing it as the remaining life of the piping material, the risk of abnormal occurrence such as damage to the piping material is reduced, and the cause of the abnormality is identified. It also provides a plant control system that enables it. In this embodiment, an abnormality diagnosis system for a heat exchanger and a control device of a plant equipped with this system have been shown, but other equipment that handles heat (for example, a combustion furnace, a reactor, a heater, and agitation) has been shown. It can also be applied to tanks, etc.).

As described above, in the first and second embodiments, the concept of the heat exchanger abnormality diagnosis method according to the present invention will be described, and in the third embodiment, the monitor screen which is a main element in the heat exchanger abnormality diagnosis system according to the present invention. The display of is explained. On the other hand, in the fourth embodiment, a specific configuration example of the abnormality diagnosis system of the heat exchanger will be described.

The heat exchanger abnormality diagnosis system consists of a data input unit for inputting actual measurement data from various sensors installed in the heat exchanger to be monitored, and a computer. A computer is composed of an input unit, an output unit, a calculation unit, and a storage unit as main components, and the input unit and the output unit form a human interface.

The input unit is composed of input means such as a keyboard, a touch panel, and a tracker, and when an operator or the like operates the input means, input information from the operator is appropriately given to the computer. The force unit is the monitor described in the third embodiment, and can display the contents as shown in FIG. The storage unit is a concept including a program storage unit that stores various programs executed by the arithmetic unit, a data storage unit that stores various data at the intermediate stage or the end of various processes in the arithmetic unit, and various databases. .. The various databases include a reference temperature (limit temperature) that serves as a reference for determining the presence or absence of an abnormality in the representative temperature of the heat medium 3.

The arithmetic unit appropriately obtains input information by an operator or the like from the input unit, reads out the corresponding program from the program storage unit, and executes various processes according to the program contents. Various processes include reference and storage of a data storage unit and various databases, and formation of a monitor screen of an output unit. In the following, the processing content of the arithmetic unit will be described as a processing function.

Of the multiple processing functions in the arithmetic unit, the first to be executed is the data input processing function using the data input unit that inputs the measured data from various sensors installed in the heat exchanger to be monitored. .. In the data input processing function, generally, actual measurement data from various sensors is automatically input at predetermined intervals, processed appropriately, and stored in various databases. The data input at this time is the actual side data from the sensors (7-16) of each part of the heat exchanger illustrated in FIGS. 1 and 2.

The next processing function executed in the arithmetic unit is the block division processing function. In the block division process, for example, the structure of the heat exchangers of FIGS. 1 and 2 is illustrated on the monitor screen based on the input information of the input unit (for example, the operator's instruction), and the block division process is performed for the operator on the monitor screen. It is executed by prompting. After the block division process, it is preferable to display the screens of FIGS. 3 and 6. The above data input processing function and block division processing function are preprocessing functions of the diagnostic processing described below, and the diagnostic processing is substantially performed by the following functions.

The first diagnostic process is a heat transfer performance evaluation diagnostic process function for the entire heat exchanger, which is a step of evaluating the heat transfer performance (that is, the amount of heat absorption) of the entire heat exchanger. Since this specific content has already been explained in Example 1 and the like, the explanation here is omitted, but in order to evaluate the heat absorption amount of the entire heat exchanger, the following three types of actual measurement data are used. Use. It is indispensable to acquire actual measurement data for at least one of these two types of fluids that serve as heat media. It is assumed that these data are secured by the data input unit and stored in a database or the like.
_{-Fluid temperature T f2-in at} the inlet of the heat exchanger
-Fluid temperature at the outlet of the heat exchanger T _f2-out or the metal temperature of the pipe through which the fluid flows at the outlet of the heat exchanger-Total flow rate of the fluid flowing through the heat exchanger Q _f2 or the replenishment flow rate of the fluid (fluid) In the case of a system configuration in which
The next diagnostic process is a block heat transfer performance evaluation diagnostic process function, which is a step of evaluating the heat transfer performance of each block. Here, in addition to the heat transfer performance (that is, the amount of heat absorption) of the entire heat exchanger, one heat exchanger is divided into a plurality of blocks, and a step of evaluating the heat transfer performance of each block is provided. At this stage, the block division processing function described above has already been executed.

The block heat transfer performance evaluation diagnostic processing function determines whether or not the actual measurement data in all the blocks exists as the measurement data as a result of the division by the block division processing function. When the actual measurement data in the block exists as the measurement data, the heat transfer performance (that is, the heat absorption amount) in the block is determined in the same manner as the heat transfer performance (that is, the heat absorption amount) of the entire heat exchanger is obtained. Ask. This specific content has already been described in Example 1 and the like, but in order to divide one heat exchanger into a plurality of blocks and evaluate the amount of heat absorption for each block, the above-mentioned heat exchanger as a whole Similar to the evaluation, the following three types of actual measurement data are used. It is indispensable to acquire actual measurement data for at least one of the two types of heat medium fluids.
-The temperature of the fluid at the inlet of each block-The temperature of the fluid at the outlet of each block or the metal temperature of the pipe through which the fluid flows at the outlet of each block-The total flow rate of the fluid flowing through each block or the replenishment flow rate of the fluid (when the fluid circulates) ).

In evaluating the heat transfer performance of each block, if there is a block that lacks actual measurement data such as temperature, flow rate (or flow velocity), pressure, etc., it is estimated using the actual measurement data of other blocks. Executes an unknown block data estimation processing function. As a case where the measured data is insufficient, it is preferable to include not only the case where the sensor to be measured is not installed but also the case where the installed sensor itself has an instrument abnormality.

Further, as a method of estimating the insufficient actual measurement data in the unknown block data estimation processing function, first, the heat absorption amount of the block is estimated. As a method of estimating the heat absorption amount of the block, for example, a method of subtracting the heat absorption amount of another block from the heat absorption amount of the entire heat exchanger, a method of interpolating or extrapolating the heat absorption amount of a neighboring block, etc. Use. Using the estimated heat absorption amount of the block, the insufficient measured data is estimated as an inverse problem.

Further, a metal temperature estimation processing function, which is a step of estimating the metal temperature of the fluid pipe in the block as an inverse problem from the heat absorption amount of each block, is provided.

In addition, the monitor screen is formed by the monitor screen formation processing function. An example of the monitor screen formed by the monitor screen forming processing function is as shown in FIG. 10, but what is important in evaluating the heat transfer performance is not just a trend, but the presence or absence of an abnormality in the representative temperature of the heat medium 3. By displaying the comparison with the reference temperature (limit temperature), which is the reference for determining the temperature, the operator can clearly recognize the current situation. For this reason, the monitor screen formation processing function refers to the database. The corresponding reference temperature (limit temperature) is extracted and displayed on the monitor screen. This makes it possible for the operator to evaluate the thermal history of the piping material by monitoring the change over time of the metal temperature, and to evaluate the remaining life of the piping material from the viewpoint of creep due to overheating, for example.

The fifth embodiment describes the heat exchanger control device that controls the heat exchanger based on the guideline given by the abnormality diagnosis system of the heat exchanger of the fourth embodiment.

The control device of the heat exchanger operates various valves of each part of the heat exchanger based on the abnormality diagnosis signal which is a guideline given by the abnormality diagnosis system of the heat exchanger. Various valves are control valves and on-off valves for controlling the flow rate of the heat medium, pressure and temperature. The abnormality diagnosis signal is a signal indicating that the amount of heat absorbed or the metal temperature is excessively large or excessively small with respect to the reference value, and the continuation of this state destabilizes the operation of the heat exchanger and further. It is a signal that predicts that the operation cannot be continued.

In the heat exchanger abnormality diagnosis system, heat exchange is performed when it is diagnosed that the remaining life of the piping of any block of the heat exchanger is short and a command is issued to reduce the temperature of the fluid on the high temperature side flowing into the block. In response to this, the control device of the vessel operates various valves in order to reduce the temperature of the fluid on the high temperature side flowing into the block.

A heat exchanger equipped with a plurality of heat exchangers in series, and when it is diagnosed that the remaining life of the piping of any of the blocks is short, the control device of the heat exchanger exchanges heat on the upstream side of the block. By shortening the interval between blows injected into the vessel to reduce dirt on the piping and increasing the amount of heat absorbed by the heat exchanger on the upstream side, the temperature of the fluid on the high temperature side flowing into the block is reduced.

Further, the control device of the heat exchanger reduces the heat load of the plant or shuts down the plant before the piping material through which the heat medium flows is deformed or ruptured by creep due to overheating.

The abnormality diagnosis system of the present invention can be applied to equipment in which a high-temperature fluid flows inside, such as a heat exchanger, a combustion furnace, and a reactor, in various plants such as industry, chemistry, and power generation equipped with a heat exchanger. Is.

1: Duct 2: Heat medium 1, 3: Heat medium 2, 4: Inlet side header piping of heat medium 2, 5: Heat transfer tube,
6: Outlet side header piping of heat medium 2, 7: Pressure of heat medium 2 in inlet header piping, 8: Flow rate of heat medium 2 in inlet side header piping, 9: Thermometer of heat medium 2 in inlet side header piping, 10: Thermometer of heat medium 2 at outlet side header piping, 11: Thermometer of heat medium 1 at duct inlet, 12: Thermometer of heat medium 1 at duct outlet, 13: Metal thermometer of heat transfer tube of heat medium 2 1,
14: Metal thermometer 2 of the heat transfer tube of the heat medium 2, 15: Metal thermometer 3 of the heat transfer tube of the heat medium 2.
16: Metal thermometer of heat transfer tube of heat medium 2, 100: Heat exchanger

Claims (14)

It is a heat exchanger abnormality diagnosis method for diagnosing an abnormality in a heat exchanger that exchanges heat between heat media.
Based on the data from the sensors installed in each part of the heat exchanger, the amount of heat absorption of the heat medium in the heat exchanger is obtained, the heat exchanger is divided into a plurality of blocks, and the heat absorption of the heat medium is performed in each block unit. A method for diagnosing an abnormality in a heat exchanger, which comprises determining the amount and evaluating the amount of heat absorbed by the heat exchanger and each block using a reference value. The temperature of the heat medium at the inlet of the heat exchanger, the temperature of the heat medium at the outlet of the heat exchanger or the metal temperature of the flow pipe of the heat medium, and the flow rate of the heat medium or the replenished heat in the case of a system in which the heat medium circulates. Use the flow rate of the medium to determine the amount of heat absorbed by the entire heat exchanger.
For each block in which the heat exchanger is divided, the temperature of the heat medium at the inlet of the block, the temperature of the heat medium at the outlet of the block or the metal temperature of the flow pipe of the heat medium, and the flow rate of the heat medium or the system in which the heat medium circulates. In that case, the amount of heat absorbed by each block is calculated using the flow rate of the replenished heat medium.
A method for diagnosing an abnormality of a heat exchanger, which comprises evaluating the heat absorption amount of the heat exchanger and each block unit using a reference value. The method for diagnosing an abnormality in a heat exchanger according to claim 2.
When the actual measurement data such as the temperature, flow rate, or flow velocity of the heat medium for evaluating the heat absorption amount is insufficient for each of the plurality of blocks divided by the heat recovery unit, the actual measurement data of the other blocks is used. A method for diagnosing abnormalities in heat exchangers, which is characterized by estimating insufficient data in blocks. The method for diagnosing an abnormality in a heat exchanger according to claim 3.
The heat exchanger is characterized in that the heat absorption amount of the block for which the actual measurement data is insufficient is estimated by subtracting the total heat absorption amount of the block for which the actual measurement data is prepared from the heat absorption amount of the entire heat exchanger. Abnormality diagnosis method. The method for diagnosing an abnormality in a heat exchanger according to claim 3.
The heat absorption is estimated from the heat absorption of the entire heat exchanger by interpolating or extrapolating the distribution of the heat absorption of the block for which the actual measurement data is available, and estimating the heat absorption of the block for which the actual measurement data is insufficient. How to diagnose abnormalities in the exchanger. The method for diagnosing an abnormality of a heat exchanger according to any one of claims 2 to 5.
A method for diagnosing abnormalities in a heat exchanger, characterized in that the distribution of heat absorption amount for each block divided by the heat recovery unit is compared with the distribution at normal times, and the presence or absence of an abnormality in the equipment is diagnosed for each block. The method for diagnosing an abnormality of a heat exchanger according to any one of claims 2 to 6.
From the amount of heat absorbed by each block divided by the heat recovery unit, the maximum value of the metal temperature of the pipe through which the heat medium flows in each block is estimated, and the heat history of the pipe material is evaluated from the change over time of this metal temperature. A method for diagnosing abnormalities in a heat exchanger, which comprises evaluating the remaining life of this piping material. It is a heat exchanger abnormality diagnosis system consisting of a data acquisition unit that captures actual measurement data from various sensors installed in a heat exchanger that exchanges heat between heat media and a computer.
A computer is composed of an input unit, an output unit, a calculation unit, and a storage unit as main components.
The input information input by the operator etc. is obtained in the input unit, displayed on the screen in the output unit, and various programs and various data are stored in the storage unit.
The calculation unit is based on a data input processing function using a data acquisition unit that takes in actual measurement data from various sensors installed in a heat exchanger that exchanges heat between heat media, and input information from the input unit. The block division processing function that divides the structure of the heat exchanger into blocks, and the heat absorption amount of the heat medium in the entire heat exchanger are obtained, and the heat absorption amount in the entire heat exchanger is evaluated using the reference value. Block heat transfer performance evaluation diagnosis that obtains the heat absorption performance of the entire exchanger and the heat absorption amount of the heat medium for each divided block, and evaluates the heat absorption amount for each divided block using the reference value. An abnormality diagnosis system for heat exchangers, which is characterized by including a processing function. The heat exchanger abnormality diagnosis system according to claim 8.
When evaluating the heat transfer performance of each block, the calculation unit has an unknown block data estimation processing function that estimates using actual measurement data such as other blocks when there is a block for which actual measurement data is insufficient. An abnormality diagnosis system for heat exchangers. The heat exchanger abnormality diagnosis system according to claim 9.
The unknown block data estimation processing function is a heat exchanger abnormality diagnosis system characterized in that the insufficient data of blocks is estimated using the measured data of the heat exchanger and the divided blocks. The heat exchanger abnormality diagnosis system according to any one of claims 8 to 10.
Wherein the output section, the heat absorption amount of the whole heat exchanger, and divided heat absorption amount of each block, the fault diagnosis system of the heat exchanger, characterized in that the screen display with these reference values. A heat exchanger control device that controls a heat exchanger by using information from the heat exchanger abnormality diagnosis system according to any one of claims 8 to 11.
The control device of the heat exchanger operates various valves of each part of the heat exchanger based on the abnormality diagnosis signal which is a guideline given by the abnormality diagnosis system of the heat exchanger, and also heats in the abnormality diagnosis system of the heat exchanger. When it is diagnosed that the remaining life of the piping of one of the blocks of the exchanger is short and a command is issued to reduce the temperature of the fluid on the high temperature side flowing into the block, the fluid on the high temperature side flowing into the block receives this command. A heat exchanger control device characterized by operating various valves to reduce the temperature of the heat exchanger. The control device for the heat exchanger according to claim 12.
A heat exchanger is a heat exchanger equipped with a plurality of heat exchangers in series, and when it is diagnosed that the remaining life of the piping of any of the blocks is short, it is injected into the heat exchanger on the upstream side of the block. The heat is characterized by reducing the temperature of the fluid on the high temperature side flowing into the block by shortening the interval between blows to reduce dirt on the piping and increasing the amount of heat absorption of the heat exchanger on the upstream side. Exchange controller. The control device for the heat exchanger according to claim 12.
A control device for a heat exchanger, characterized in that the heat load of the plant is reduced or the plant is stopped before the piping material through which the heat medium flows is deformed or broken by creep due to overheating.

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