JP2016113967A - Maintenance planning system of plant equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a maintenance planning system capable of determining an optimum maintenance timing to minimize the total cost of a cumulative value of fuel costs and maintenance cost for equipment maintenance.SOLUTION: A maintenance planning system includes an equipment efficiency calculation portion 12 for calculating equipment efficiency of equipment constituting a plant, a fuel cost calculation portion 13 determining fuel costs of the equipment on the basis of equipment efficiency, a function calculation portion 17 for determining increase tendency of the fuel costs by fitting time-series data of the fuel cost to a function, a cumulative loss calculation portion 16 for determining a cumulative value of the fuel costs, and an optimum maintenance calculation portion 18 to determine the maintenance timing to minimize the total cost of the cumulative value of the fuel cost and the maintenance cost to improve the equipment efficiency.SELECTED DRAWING: Figure 1

Description

  The present invention analyzes the efficiency of plant components and considers the increase in fuel cost due to the decrease in efficiency and the maintenance cost for improving the efficiency of the device. The present invention relates to a maintenance planning system and method for plant equipment.

  The efficiency of equipment constituting a power plant, for example, a gas turbine of a thermal power plant, decreases with time due to blade damage and dirt adhesion. When the efficiency decreases, the fuel is excessively consumed and the operation cost increases. Therefore, in order to suppress an increase in operating cost, blade replacement is performed for damage and cleaning is performed for dirt, and operation is continued while restoring efficiency. However, since these maintenance operations are performed by disassembling the gas turbine, it is necessary to stop the operation of the plant for a certain period of time, and the maintenance costs are also high. In particular, when parts such as wings need to be replaced, in addition to the maintenance work costs, there is also a purchase cost for the parts.

  Against this background, it is not a good idea to frequently perform maintenance on plant equipment, and the total cost is minimized in view of both the increase in operating cost due to the decrease in efficiency and the maintenance cost for improving efficiency. It is effective in terms of cost reduction to implement at the time.

  As an example of a system for drafting a maintenance plan for minimizing operation and maintenance costs, Patent Document 1 describes a method of presenting a cleaning time for reducing the total cost for a cleaning operation of a compressor of a gas turbine. Yes. In this apparatus, the compressor efficiency is calculated, the cumulative value of the loss cost due to the absence of cleaning is obtained, and the optimum cleaning time is determined by comparing the cumulative loss cost with the cost required for cleaning. In this document, it is preferable that the time when the accumulated loss cost becomes equal to the cleaning cost is determined as the cleaning time.

JP2005-133583

  In the method described in Patent Document 1, it is determined that the optimum cleaning time is determined by comparing the accumulated loss cost and the cleaning cost. However, as a specific method for comparing and determining, a time point when both the costs coincide with each other is determined. Only the optimal method is presented. However, if the trend of decreasing efficiency is not linear and decreases more rapidly or conversely, the total cost is not necessarily minimized when the accumulated loss cost and the cleaning cost match. Absent. If the efficiency decreases rapidly, cleaning is performed at an earlier time than when the two costs coincide and the frequency of maintenance is increased to minimize the cost. On the other hand, if the cost decreases gradually, cleaning is performed at a time later than the time when the two costs coincide with each other, and the maintenance frequency is reduced to minimize the cost.

  As described above, according to the conventional technique, it has not been possible to determine the maintenance time based on the increasing tendency of the fuel cost due to the decrease in efficiency of the plant component equipment.

  Therefore, in order to solve the above-described problems, the present invention provides an equipment efficiency computing unit that computes equipment efficiency of equipment constituting a plant, a fuel cost computing unit that calculates a fuel cost of the equipment based on the equipment efficiency, and the fuel A function calculation unit that obtains an increase tendency of the fuel cost by fitting time-series data of costs to a function, an accumulated loss calculation unit that obtains an accumulated value of the fuel cost, and the fuel based on the increase tendency of the fuel cost There is provided a maintenance planning system for plant equipment, comprising an optimum maintenance calculation unit for obtaining a maintenance time that minimizes a cumulative cost and a maintenance cost for improving the equipment efficiency.

  According to the present invention, by taking into account the increasing tendency of fuel costs due to the decrease in the efficiency of plant component equipment, the optimal maintenance time that minimizes the total cost of the cumulative fuel cost and the maintenance cost due to equipment maintenance can be set. Can be judged.

It is a figure which shows the structure of the maintenance plan system of the plant apparatus which is an Example of this invention. It is a figure which shows the time-dependent change of correction | amendment compressor efficiency. It is a figure which shows the time-dependent change of the fuel cost increase amount by efficiency fall. It is a figure which shows the time-dependent change of the accumulated loss cost by efficiency fall. It is a figure explaining the logic for determining the optimal date of a maintenance. It is a figure which shows the relationship of the total amount required for the total cost and the loss amount by the fuel cost increase accompanying efficiency degradation, and the maintenance. It is a figure which shows the function fitting to the fuel cost increase amount. It is a figure which shows the method of determining the optimal maintenance day from accumulated loss cost. It is a figure which shows the example of a display screen of a system. It is a figure which shows the presentation method in case there exist a some maintenance method. It is a figure which shows the structure of a combined power generation plant.

  A preferred embodiment of a maintenance planning system for plant equipment according to the present invention will be described. The following description is merely an example of implementation and is not intended to limit the invention itself to the following specific contents.

  FIG. 1 is a diagram showing a plant equipment maintenance planning system according to an embodiment of the present invention. Reference numeral 1 denotes a maintenance planning system. Reference numeral 2 denotes a plant to be a maintenance plan. Reference numeral 3 denotes an input / output device that inputs data necessary for system processing and outputs system processing results. The input / output device also includes a display device, and the processing result can be displayed to the operator.

  In the system of the present embodiment, a thermal power combined power plant (so-called C / C plant) will be described as an example of the plant 2. FIG. 11 is a diagram illustrating a device configuration of the C / C plant. 21 is a gas turbine, 22 is a compressor constituting the gas turbine, 23 is a combustor, and 24 is an expander. In the gas turbine 21, the compressor 22 takes in air and compresses it, then the combustor 23 takes in compressed air and fuel to generate combustion gas, and the expander 24 takes in the combustion gas to obtain power. The output of the gas turbine is the difference between the power output from the expander 24 and the power used by the compressor 22. Reference numeral 25 denotes an exhaust heat recovery boiler. The exhaust heat recovery boiler 25 generates high temperature steam using high temperature exhaust gas from the gas turbine. 26 is a steam turbine. Power is obtained by taking in the high-temperature steam generated in the exhaust heat recovery boiler 25. 27 is a condenser. The steam is condensed into water by taking in the exhaust of the steam turbine 26 and exchanging heat with the cooling water. Reference numeral 28 denotes a generator. Electric power is generated using the outputs of the gas turbine 21 and the steam turbine 26.

  In the present embodiment, the processing will be described below by taking the compressor 22 of the gas turbine as an example of the device for determining the optimal implementation date for performing maintenance.

  With reference to FIG. 1, the structure of the maintenance plan system 1 of the plant apparatus which becomes this invention is shown. In this system, a process value database 11, a plant model database 14, a fuel cost database 15, and a maintenance cost database 19 are stored in a storage medium including a hard disk, a database unit 4, a device efficiency calculation unit 12, and a fuel cost calculation unit 13. The cumulative loss calculation unit 16, the function calculation unit 17, and the optimum maintenance calculation unit 18 are mainly configured by the calculation unit 5 that performs calculation processing by a processor such as a CPU (Central Processing Unit). In addition, the database unit 4 and the calculation unit 5 perform communication processing by wire or wireless. Each configuration will be described below.

  The process value database 11 captures measurement data from the plant 2 and stores it in the database. The equipment efficiency calculation unit 12 extracts data from the process value database, and calculates the efficiency of equipment constituting the plant. As described above, in this embodiment, the compressor is the target device. The following equation is used as means for calculating the efficiency η of the compressor.

  Here, Pin and Pout are compressor inlet and outlet pressures, Tin and Tout are compressor inlet and outlet temperatures, and κ is a specific heat ratio of air.

  The equipment efficiency calculation unit 12 takes in the measured values of the temperature and pressure of the compressor from the process value database 11 and calculates the compressor efficiency by Equation 1. However, the value of the compressor efficiency obtained by Equation 1 is affected by atmospheric conditions and operating conditions in addition to the deterioration status of the equipment. This is because the mass flow rate of air taken in by the compressor changes. The density of air varies depending on the atmospheric temperature, and also varies depending on the opening degree of IGV (Inlet Guide Vane). In the system according to the present embodiment, it is important to more accurately determine the deterioration state of the device. For this reason, the correction efficiency for eliminating the dependence of the atmospheric temperature and the IGV opening is performed on the value of the compressor efficiency obtained in Equation 1 to calculate the corrected compressor efficiency as shown below.

  The corrected compressor efficiency is calculated by taking the difference between the atmospheric temperature correction coefficient and the IGV opening correction coefficient from the compressor efficiency. Here, the relationship between the air flow rate and the IGV opening relative to the compressor efficiency is created in advance using test data at the time of design or operation data of the actual machine.

  FIG. 2 is a graph showing the change over time of the correction compressor efficiency. When maintenance such as cleaning is not performed, the efficiency gradually decreases as shown in the figure. The device efficiency calculation unit 12 calculates such a tendency of change in efficiency.

  Next, the fuel cost calculation unit 13 shown in FIG. 1 obtains an increase in fuel consumption due to efficiency reduction using the calculated corrected compressor efficiency. For example, in the device configuration of the combined power plant shown in FIG. 11, when the efficiency of the compressor 22 decreases, the power used by the compressor increases, so the efficiency of the gas turbine 21 decreases. The output of the gas turbine 21 decreases and the exhaust gas temperature increases. In the exhaust heat recovery boiler 25 in the subsequent stage, since the temperature of the gas to be taken up has increased, the amount of steam generated increases. Therefore, the output of the steam turbine 26 increases. That is, when the efficiency of the compressor 22 decreases, the output of the gas turbine 21 decreases, while the output of the steam turbine 26 increases. At this time, since the output decrease of the gas turbine is larger, the total output decreases. Therefore, in order to obtain the same power generation output, fuel is excessively consumed.

  As described above, in a combined power plant, a gas turbine, an exhaust heat recovery boiler, and a steam turbine are related to each other. It is necessary to consider the impacts. In the system according to the present embodiment described in FIG. 1, the plant model database 14 is equipped with a heat balance model having functions of a gas turbine, an exhaust heat recovery boiler, and a steam turbine. The fuel cost calculation unit 13 uses the heat balance model stored in the plant model database 14 to calculate the increase amount of the fuel flow rate due to the efficiency reduction of the gas turbine compressor. In addition, the model data of not only a combined power generation plant but various plants are hold | maintained, and the increase amount of the fuel flow volume by the said efficiency fall is computable.

  Further, the fuel cost calculation unit 13 converts the increase amount of the fuel flow rate into the increase amount of the fuel cost. For this processing, the fuel cost database 15 stores the price of the fuel according to the purchase time as time series data. The fuel cost calculation unit 13 obtains the increase amount of the fuel cost by multiplying the increase amount of the fuel flow rate calculated using the heat balance model described above by the fuel price. FIG. 3 is a diagram showing a change with time of the fuel cost increase amount calculated by the fuel cost calculation unit 13.

  Next, the cumulative loss calculation unit 16 illustrated in FIG. 1 calculates the cumulative loss cost using the increase amount of the fuel cost calculated by the fuel cost calculation unit 13. FIG. 4 is a diagram showing a change with time of the accumulated loss cost. This can be obtained, for example, by integrating the trend of fuel cost increase. In the system according to the present embodiment, the calculated cumulative loss cost is compared with the maintenance cost for improving the efficiency, and the maintenance execution time at which the total cost of operation and maintenance is minimized is determined.

  The outline of the determination method is shown below. First, it is assumed that the time interval for performing maintenance is the same, and this is represented by T. Further, it is assumed that the efficiency is always restored to the same state by the maintenance, and the tendency of the subsequent efficiency to decrease is not changed. At this time, the increase amount of the fuel cost due to the reduction in the efficiency of the device is repeated in the same pattern as shown in FIG. Here, a function representing an increasing tendency of the fuel cost is defined by F (t) of Formula 2.

  t is time, n is a parameter indicating a tendency of efficiency reduction, and a is a coefficient. When n is 1, the efficiency decreases linearly, that is, the fuel cost increases linearly. When n is larger than 1, it indicates that the progress of efficiency reduction is fast, and when it is smaller than 1, it indicates that the progress is slow. The function representing the accumulated loss cost is expressed by L (t) in Expression 3 with respect to Expression 2 representing the fuel cost.

  The function F (t) representing the fuel cost expressed by Equation 1 is integrated. FIG. 5B shows a graph of the accumulated loss cost.

  Assuming a sufficiently long period P and assuming that the maintenance time interval is T as described above, the number of times maintenance is performed during the period P is P / T times. Assuming that the cost for one maintenance is M, the total cost, which is the sum of the increase in fuel cost due to the decrease in equipment efficiency during the period P and the cost required for maintenance, is expressed by C (T) in Formula 4. The

  The first term is the loss due to the increase in fuel cost, and the second term is the total amount required for maintenance. In order to minimize the total cost C (T), the condition of Equation 5 should be satisfied.

  The above formula 5 shows the case where the slope of the function of the total cost C (T) becomes 0, and the minimum value at which the fluctuating total cost becomes convex is obtained. From this condition, the relationship shown in Equation 6 can be derived. If Equation 3 is substituted into this relationship, the relationship of Equation 7 is obtained.

  In Equation 7, the left side is the accumulated loss cost L (T). The right side is a value obtained by dividing the maintenance cost M per time by the parameter n representing the tendency of efficiency reduction. The cost is minimized when both values match. When n = 1, that is, when the efficiency decreases linearly, the time at which the accumulated loss cost and the maintenance cost are equal is the minimum cost. However, it can be seen that the cost is not minimized when the reduction in the efficiency of the device progresses more rapidly or more slowly than linear.

  This relationship is shown in FIG. FIG. 6 is a graph showing the total cost C (T) expressed by Equation 4, the amount of loss due to the increase in fuel cost associated with efficiency degradation, which is the first term, and the total amount required for maintenance, which is the second term. The horizontal axis of the graph indicates the maintenance execution interval T, which corresponds to a state in which the maintenance frequency decreases as it goes to the right. (A), (b), and (c) have shown the case where n of Numerical formula 4 is 0.5, 1.0, and 2.0, respectively. In addition, the scale of the vertical axis | shaft of each graph and the horizontal axis are changing and shown in figure.

  The amount of loss due to an increase in fuel cost in a certain period P tends to increase monotonically as the maintenance execution interval T is extended, that is, the frequency of maintenance is reduced. On the other hand, the maintenance cost tends to monotonously decrease as the maintenance frequency decreases. Accordingly, the total cost C (T), which is the sum of both, is a downward convex function. The system determines an optimum execution time T of maintenance so that the total cost is minimized.

  In the figure, three patterns with different values of n are shown, and the relationship between the loss due to the increase in fuel cost and the maintenance cost under the condition that the total cost is minimized is seen. When (a) n = 0.5, the loss due to the increase in fuel cost is twice the maintenance cost, when (b) n = 1.0, both are equal, and (c) n = 2. It can be seen that when 0 is half, the total cost is minimized. This is equivalent to the relationship of Equation 7 described above. Different values of n indicate that the increasing tendency of the fuel cost due to the decrease in efficiency is different. The larger the value of n, the more rapidly the efficiency decrease and the more the fuel cost loss increases. That is, the relationship between the loss of the fuel cost that minimizes the total cost and the maintenance cost changes depending on the decreasing tendency of efficiency.

  Considering the above characteristics, in the system according to the present embodiment, the maintenance execution timing at which the cost is minimized is determined from the accumulated loss cost and the maintenance cost based on the tendency of decreasing efficiency, that is, the increasing tendency of fuel cost.

  The function calculation unit 17 performs fitting to the function as shown in FIG. 7 on the data calculated by the fuel cost calculation unit 13 shown in FIG. The function form at this time uses Equation 2 above. The value of the parameter n representing the fuel increase tendency is obtained by the fitting.

  Next, the optimum maintenance calculation unit 18 takes in the cumulative loss cost output from the cumulative loss calculation unit 16 and the parameter n representing the fuel increase tendency output from the function calculation unit 17, and calculates the maintenance date that minimizes the cost. The method for determining the maintenance date follows Equation 7 above. At this time, the maintenance cost is stored in the maintenance cost database 19 shown in FIG.

  FIG. 8 shows an outline of processing for determining the maintenance date that minimizes the cost. The time when the accumulated loss cost reaches the judgment reference cost is set as the optimal date. Here, the determination reference cost is a value on the right side shown in Equation 7, and is a value obtained by dividing the maintenance cost M by a parameter n representing a tendency of efficiency reduction. In the example of this figure, since the value of n determined by the function calculation unit 17 is greater than 1, the determination reference cost is lower than the maintenance cost. In other words, it is determined that the point in time when the accumulated loss cost reaches the maintenance cost amount is the optimum date that minimizes the cost. Further, when the value of n determined by the function calculation unit 17 is smaller than 1, the determination reference cost is larger than the maintenance cost. Therefore, the time point at which the accumulated loss cost is later than the time point at which the maintenance cost amount is reached is the minimum cost. Judged as the best day.

  FIG. 9 is an example of a display screen output by the input / output device 3. Reference numeral 31 denotes a trend of corrected compressor efficiency. Reference numeral 32 denotes a trend of an increase in fuel cost due to a decrease in compressor efficiency, and a fitting equation. Reference numeral 33 denotes an accumulated loss cost, a maintenance cost, and a determination reference cost, and outputs the optimum maintenance date determined from these. By providing such information to the user, it is possible to show the basis for the optimum maintenance date determined by the system. In addition, when a plurality of plants are operated, it is possible to display only the optimum maintenance date in each plant.

  The above is the flow of processing performed by the system in this embodiment. The above processing has been described on the assumption that there is one type of maintenance method. On the other hand, when there are a plurality of methods such as cleaning and blade replacement as maintenance for improving the efficiency of the compressor, as shown in FIG. 10, even if the judgment standard cost calculated from each maintenance cost is displayed. Good.

  In the above-described processing, the fitting to the function is performed with respect to the increase trend of the fuel cost, but it may be performed with respect to the decrease trend of the efficiency. In this case as well, the parameter n may be obtained by fitting to the function shown in Equation 2 above. However, since the fitting is for the downward trend, the coefficient a is a negative value.

  According to the present embodiment, in an environment where the efficiency of the plant component equipment decreases and the fuel cost increases, the increase amount of the fuel cost due to the decrease in efficiency is calculated, the cumulative loss cost that is this cumulative value is calculated, Comparing the cumulative loss cost with the maintenance cost for improving efficiency and determining the maintenance time that minimizes the total cost of the fuel cost and maintenance cost, the tendency to decrease in efficiency or increase in fuel cost Therefore, it is possible to accurately determine the time when the total cost is minimum. Thereby, the operation and maintenance cost of the plant can be reduced. In addition, when the efficiency trend is gradual, maintenance intervals can be extended more than before, so unnecessary maintenance work can be omitted, maintenance work time can be shortened, and plant operation rate can be improved. .

  In addition, the system according to the present invention can be used for all plants including power plants and chemical plants.

DESCRIPTION OF SYMBOLS 1 Maintenance planning system 2 Plant 3 Input / output device 4 Database part 5 Calculation part 11 Process value database 12 Equipment efficiency calculation part 13 Fuel increase calculation part 14 Plant model database 15 Fuel cost database 16 Cumulative loss calculation part 17 Function calculation part 18 Optimal maintenance Arithmetic unit 19 Maintenance cost database 21 Gas turbine 22 Compressor 23 Combustor 24 Expander (turbine)
25 Waste heat recovery boiler 26 Steam turbine 27 Condenser 28 Generator

Claims (10)

An equipment efficiency calculation unit for calculating the equipment efficiency of equipment constituting the plant;
A fuel cost calculation unit for determining the fuel cost of the device based on the device efficiency;
A function calculation unit for fitting the fuel cost time-series data to a function to obtain an increase tendency of the fuel cost;
An accumulated loss calculation unit for obtaining an accumulated value of the fuel cost;
Based on the increasing tendency of the fuel cost, an optimum maintenance calculation unit for obtaining a maintenance time that minimizes the cumulative value of the fuel cost and the total cost of the maintenance cost for improving the equipment efficiency;
A maintenance planning system for plant equipment. In the plant equipment maintenance planning system according to claim 1,
The maintenance plan system for plant equipment, wherein the increasing tendency of the fuel cost is expressed by an exponent value of a power function in which the fitting is performed. In the maintenance planning system for plant equipment according to claim 1 or 2,
The optimum maintenance calculation unit sets a reference cost for determining the maintenance time, and sets the maintenance time when the accumulated value of the fuel cost matches the reference cost. Planning system. In the plant equipment maintenance planning system according to claim 3,
A maintenance planning system for plant equipment, wherein the reference cost is changed based on an increasing tendency of the fuel cost. In the plant equipment maintenance planning system according to claim 4,
The maintenance cost system for plant equipment, wherein the reference cost is expressed by a value obtained by dividing the maintenance cost by an exponent value of a power function in which the fitting is performed. In the maintenance planning system for plant equipment according to any one of claims 1 to 5,
A plant equipment maintenance planning system, wherein the plant includes a power plant. In the plant equipment maintenance planning system according to claim 6,
A database for storing the heat balance model of the power plant,
The maintenance plan system for plant equipment, wherein the fuel cost computation unit computes an increase in fuel cost due to a reduction in efficiency of the equipment using the heat balance model. In the maintenance planning system for plant equipment according to any one of claims 1 to 7,
A maintenance planning system for plant equipment, wherein a trend of the accumulated value of the fuel cost is displayed together with the reference cost, and the maintenance time is presented. In the maintenance planning system for plant equipment according to any one of claims 1 to 8,
The function calculation unit obtains a tendency to decrease the device efficiency,
The maintenance planning system for plant equipment, wherein the optimum maintenance calculation unit obtains the maintenance time based on a tendency of reduction in equipment efficiency.   Obtaining the fuel cost of the equipment and its accumulated value based on the equipment efficiency of the equipment constituting the plant, and fitting the time series data of the fuel cost to a function to obtain the increasing tendency of the fuel cost, A maintenance planning method for plant equipment, characterized in that, based on an increasing trend, a maintenance time for minimizing a total cost of the fuel cost and a maintenance cost for improving the equipment efficiency is obtained.