JPH01300101A - Boiler controller - Google Patents

Abstract

PURPOSE:To perform such control as to minimize starting loss while maintaing opti mum rates of temperature rise and pressure rise by inferring a rate of change of fluid temperature by a fluid temperature change rate-inferring part incorporating a fuzzy inference function which uses a rate of change of steam temperature and a maximum thermal stress as input data, and controlling the rate of change of fluid temperature with the inferred rate of change as a set point. CONSTITUTION:When a requirement such as a scheduled time of end of starting is changed during a boiler starting operation, control rules for fuzzy inference in a steam temperature change rate-calculating part 80 are changed, for instance, a life consumption is changed from 80% to 90% whereas a limit for rate of change of steam temperature is raise, by a control rule change signal 85 supplied from a keyboard 94 through a simulator 92, and simulation is repeated until a result corresponding to the change in requirement is obtained. A control of a plant is maintained in the present condition by outputting a control-stopping signal 84 from the simulator 92 to a controlling part 81, and the control-stopping signal84 is not added or removed until a new manipulated variable signal 61 according to the change in requirement is obtained. This function makes it possible to cope with a change in operation requirements and to perform control with due consideration of safety.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a boiler control device suitable for operating a plant while managing the life consumption of pressure-resistant parts in a boiler system.

[Conventional technology]

FIG. 4 is a system diagram of a conventional boiler startup control device.

In Fig. 4, 1 is a water wall that constitutes the boiler furnace wall;
2 is a burner, and 3 is a boiler water supply pump that supplies water to the water wall 1. Reference numeral 4 denotes a steam/water disperser which separates a steam/water mixture produced when feed water is heated by the water wall 1 into steam and moisture. 5 is a superheater that heats the steam from the steam separator 4;
Reference numeral 6 represents an energy saver that preheats the water supplied from the water supply pump 3, and 7 represents a turbine connected to a generator. A turbine control valve 8 is interposed between the superheater 5 and the turbine 7 and controls the amount of steam flowing from the superheater 5 to the turbine 7. 9 is a superheater bypass valve that releases steam from the steam separator 4 to a condenser or the like. When a large amount of low-temperature steam flows into the superheater 5 during startup and prevents the temperature from rising at the outlet of the superheater 5, the superheater bypass valve 9 allows such low-temperature steam to escape and closes the superheater 5. It has the function of reducing the amount of steam passing through the superheater 5 and increasing the steam temperature at the outlet of the superheater 5. Reference numeral 10 designates a turbine bypass valve that releases steam generated from the outlet of the superheater 5 to a condenser or the like. This turbine bypass valve 10 has a function of releasing the generated steam when the turbine control valve 8 is fully closed in a state where the temperature and pressure have not been increased to the extent that the generated steam can be vented to the turbine 7. Even after venting to 7, if the aeration steam flow rate is small, it will be difficult to control the steam pressure by controlling the amount of fuel input, so the function contributes to steam pressure control by releasing the generated steam in this region.

11 is a steam pressure detector that detects the pressure of steam supplied from the superheater 5 to the turbine 7; 12 is a steam pressure setting device that sets the target pressure of the steam, that is, the target steam pressure;
A subtracter 13 calculates the difference between the value set in the steam pressure setting device 12 and the value detected by the steam pressure detector 11. 14 and 15 are proportional integrators that proportionally integrate the pressure deviation signal calculated and output by the subtracter 13. 16 is a function generator which inputs the value detected by the steam pressure detector 11 and outputs a predetermined value corresponding to this value. The output signal from the function generator 16 becomes an opening degree command signal that instructs the opening degree of the turbine bypass valve 10 to maintain the steam pressure at an appropriate pressure. 17 is a function generator which inputs the value detected by the steam pressure detector 11 and outputs a value corresponding to this value. The output signal from the function generator 17 becomes an opening degree command signal that instructs the opening degree of the superheater bypass valve 9 for discharging a large amount of low-temperature steam that prevents the temperature of the superheater 5 from rising. 18 is a terminal 18a.

18b and a switching piece 18C, the terminal 18a is connected to the proportional integrator 14, the terminal 18b is connected to the function generator 16, and the switching piece 18c is connected to the turbine bypass valve 10. A quotient signal selector 19 compares the output signal of the proportional integrator 15 and the output signal of the function generator 17 and outputs the larger signal to the superheater bypass valve 9. 20 is a fuel flow control valve that controls fuel supply to the burner 2, and 21 is an opening setting device that sets the opening of the fuel flow control valve 20 in accordance with the number of ignitions of the burner.

Here, the operation of the above device will be explained with reference to the time charts shown in FIGS. 5fa) to 5(e). Figure 5(a)
5 (b) shows the change in the opening degree of the superheater bypass valve 5 over time, and FIG. 5 (C) shows the change in the amount of fuel input over time.
Fig. 5 +dl shows the change in the steam pressure over time, and Fig. 5 fe) shows the change in the superheater outlet steam temperature over time. Time t0 is the ignition time, time t,
is the pressure increase completion time, time [2 is the temperature increase completion time, and time t is the turbine ventilation time. Also, P2 is the initial steam pressure value,
P is the boost target value.

After the ignition at time t0, the number of ignitions of the burner 2 is increased in stages, and in accordance with this, the opening degree of the fuel flow rate control valve 20 is controlled by the opening degree signal from the opening degree setting device 21, and the amount of fuel input is It increases step by step as shown in Figure 5(a). On the other hand, the signal switching device 18 is in a state where its switching piece 18c is switched to the terminal 18b before the steam pressure reaches the pressure increase target value P. Therefore, the turbine bypass valve 10
The opening degree of is controlled by the output of the function generator 16 corresponding to the steam pressure until the steam pressure detected by the steam pressure detector 11 reaches the boost target value P1, and is uniquely determined by the steam pressure. be done. The function generator 16 generates the target value P
The rate of change in steam pressure during the pressure raising process to 1 is set to an appropriate value.

Furthermore, as shown in FIG. 5(C), the turbine bypass valve 10 is operated at a pressure increase completion point P, after which the switching piece 18C of the signal switching device 18 is switched to the terminal 18a, and the steam is increased by the signal of the proportional integrator 14. Its opening degree is controlled to release pressure. In addition, while the steam pressure is low, the saturation temperature of the steam is low, and low-temperature steam is supplied from the steam separator 4.
The output signal of the function generator 17 becomes a signal that increases the opening degree of the superheater bypass valve 9, thereby allowing low-temperature steam to escape, reducing the amount of steam passing through the superheater 5, and increasing the exit steam temperature of the superheater 5. let After the steam pressure reaches the pressure increase target value P1, the opening degree of the turbine bypass valve 10 is adjusted to the pressure increase target value P set in the steam pressure setting device 12 as described above.
, and the actual steam pressure detected by the steam pressure detector 11.
It is controlled as shown in C).

Furthermore, after the pressure increase completion time t1, if the steam pressure becomes so high that it cannot be released by the turbine bypass valve 10, the output signal of the proportional integrator 15 also becomes large.
The high signal selector 19 selects the output signal and increases the opening degree of the superheater bypass valve 9 to release steam and suppress a rise in steam pressure.

Thermal stress depends on the metal temperature difference between the inner and outer surfaces of the container or piping, and the greater the wall thickness and the more rapid the temperature change of the internal fluid, the greater the thermal stress. becomes. From this point of view, the superheater outlet header and the steam/water separator (or drum) are known to be important parts of the boiler as well as thermal stress management membranes. The need to monitor the thermal stress generated at such locations is well known, and various thermal stress measurement methods have been developed to date.

Among these thermal stress measurement methods, methods such as attaching strain gauges are superior in terms of accuracy, but as a means of permanently installing them in boiler plants, methods that transmit measurement signals such as internal fluid temperature and pressure are better. The method of calculating thermal stress is called durability.
It is easy to handle, and this method is widely used in practice.

The sixth concept is to reflect the monitored thermal stress in the control system.
There is a main steam temperature predictive adaptive control shown in the figure.

This idea is to correct the amount of fuel input based on the deviation from the predicted value of future steam temperature based on the conventional predicted value of thermal stress.

[Problem to be solved by the invention]

The conventional techniques described above, including the concept shown in FIG. 6, have the following problems, which need to be solved. These problems will be explained in order below.

+11 In the conventional device shown in Fig. 4, the optimum temperature increase 1. It is difficult to set the boost pattern. Here, the optimal temperature increase,
The pressure increase pattern is a startup mode that increases the temperature and pressure in the shortest possible time while suppressing the occurrence of thermal stress in thick-walled parts of the boiler. By the way, in general, the most important thick-walled parts in a boiler system are the outlet header of the superheater 5 and the steam separator 4 (
In other words, the optimum temperature and pressure increase pattern is the rate of change in the steam temperature at the outlet of the superheater 5 (hereinafter referred to as the temperature increase rate), which affects the thermal stress of the outlet header of the superheater 5. ) and the steam pressure change rate (hereinafter referred to as pressure increase rate) that affects the thermal stress of the steam separator 4 (or drum) through the saturation temperature change. It can be said that this is a mode in which the limit value is maintained at all times.

Looking at the conventional equipment mentioned above from this perspective, the temperature increase rate,
The pressure increase rate is adjusted by the settings of function generator 1.6.17, but these settings require repeated starting tests on actual cans, which is troublesome, and furthermore, when starting, the steam pressure at ignition time t0 If the (initial pressure) is a steam pressure different from the one used for adjustment, a situation will occur where the temperature increase rate and pressure increase rate will deviate from the planned rate.

In order to prevent the negative effects of such deviations, the function generators 16 and 17 in conventional devices control the temperature rise rate and pressure rise rate no matter what initial pressure is started, or during any process of temperature rise or pressure rise. is set so that the limit value is not exceeded.

As a result, the temperature and pressure increase pattern deviates significantly from the optimal temperature and pressure increase pattern, and the startup time becomes considerably longer than when the temperature and pressure increase are optimal.

(2) With the conventional device shown in FIG. 4, it is difficult to manage the life of the plant. As mentioned above, this device also has a thermal stress monitoring function that allows you to grasp the thermal stress generated in thick walls during the startup process, and after a series of startups and shutdowns, it is possible to check the change range and duration of the thermal stress value during the thermal cycle. It is possible to calculate lifetime consumption.

However, the ultimate purpose of plant life management is
For a series of operations such as starting and stopping, depending on the situation,
For example, there are cases in which rapid startup is required with a certain level of life consumption, and cases in which startup is required to reduce life consumption as much as possible.
The goal is to flexibly use different operating methods to achieve startup according to the lifetime consumption value according to the case.

From this point of view, conventional devices only make it possible to know the life consumption value at the door after a certain operation, but do not meet the requirement of realizing operation in accordance with the life management policy at each startup etc. They are completely powerless against it.

(3) In the conventional device shown in FIG. 6 described above, compared to the device shown in FIG. 4, an improvement measure has been attempted in which the future behavior of thermal stress is reflected in the amount of fuel input. However, although this device has the idea of thermal stress predictive control, it cannot maintain the function of realizing flexible startup operation that realizes the life consumption allocated according to the situation described in the above item (2).

(4) A common drawback of the conventional devices shown in FIGS. 4 and 6 is that it is difficult to reduce startup loss. In the above-mentioned boiler apparatus, when starting at a given temperature increase rate and pressure increase rate, the amount of input fuel that passes through the fuel flow control valve 20, the opening degree of the superheater bypass valve 9, and the opening degree of the turbine bypass valve 10. The combination of is not uniquely determined. That is, for example, by putting a large amount of fuel into the burner 2, the superheater bypass valve 9
While there is a combination in which a large amount of steam is extracted from the turbine bypass valve IO, there is also a reverse combination. Among these combinations, the combination of the three that can maintain the given temperature increase rate and pressure increase rate is the operation with the least startup loss in achieving the same startup time.

However, in the conventional device, there is no function to operate the superheater bypass valve 9, the turbine bypass valve 10, and the fuel flow control valve 20 in a coordinated manner. There is no other way than to adjust each of 16° and 17 individually.

In reality, it is almost impossible to adjust these so that the above-mentioned optimal temperature increase rate and pressure increase rate are maintained and the startup loss is minimized.

[Means to solve the problem]

In short, the present invention has a function of measuring, calculating or estimating the temperature of the fluid in the pressure-resistant part and the generated thermal stress value of the pressure-resistant part;
In a boiler that has the function of controlling the temperature or temperature change rate of the fluid in the pressure-resistant section, start-up operations are assigned a certain life consumption value based on the relational expression between the maximum generated thermal stress value and the life consumption value after the completion of the relevant thermal cycle. The generated thermal stress maximum value is calculated, and the fluid temperature change rate is estimated by a fluid temperature change rate estimator that has a built-in fuzzy inference function that uses at least the steam temperature change rate and the thermal stress maximum value as input data, and this is estimated as the target value. By controlling the rate of change of fluid temperature, the above-mentioned problems can be solved.

[Background of the invention]

In the present invention, it is important to understand the relationship between the fluid temperature change rate and the maximum value of thermal stress, and the relationship between the maximum value of thermal stress and the life consumption value in thermal cycles. By the way, in the former case, after the fluid temperature changes, the heat capacity and
There are large delays due to heat conduction, and the latter cannot be determined until essentially one thermal cycle has been completed and this history is taken into account. Therefore, it is extremely complicated and difficult to handle these relational expressions using a method (physical model) that describes them using simultaneous differential equations or the like based on physical laws.

On the other hand, from the perspective of applying these relational expressions, since it is normal for a plant to start up on the order of 1,000 times during its service life, the maximum value of thermal stress and the life consumption value after one thermal cycle are It suffices if the relational expression with is accurate on average, and the influence of errors that cause uncertainty in individual cases need not be a problem as long as they cancel each other out each time. For this kind of application, the most suitable method is to obtain a relational expression from the accumulation of actual data (statistical model).

Regarding the statistical model method, see "Boiler Control Device" (Japanese Patent Application No. 61-262781) proposed by the applicant.
Also, regarding the method of life evaluation based on the maximum value of thermal stress,
The natural consequences are omitted here because they are detailed in the specifications of the "boiler load control device" (Japanese Patent Application No. 58-116201, Japanese Patent Application Laid-open No. 60-11002) proposed by the present applicant. As such, there is a strong correlation between the maximum value of thermal stress and the lifetime consumption after the completion of one thermal cycle, and the validity of adjusting them using a statistical relational expression is supported.

Furthermore, the relationship between the fluid temperature change rate and the thermal stress maximum value is such that the fluid temperature change rate is not uniquely determined once the thermal stress maximum value is determined. There are many constraints such as constraints, and considering the priority of these conditions,
In addition, in order to realize control based on the intuition and experience of a skilled operator, it is optimal to use fuzzy inference.

The concept of fuzzy theory is briefly described below. Fuzzy theory is described in detail in Haka Terano's ``Introduction to Fuzzy Systems'', Ohmsha, 1987.

Fuzzy (vague) theory is based on the intuition and experience of skilled operators, and ambiguous judgment methods (if..., then...) are applied in the form of control rules (IP). . . . THEN . . .), and it has the advantage that it is easy to incorporate ambiguous judgment situations into control calculations.

Based on fuzzy set theory, fuzzy theory expresses the degree of belonging to this set by a collection of elements expressed by a membership function. This membership function is from O to 1
This value is called the "grade" of belonging to that set.

This grade corresponds to the degree of ambiguity (1 is completely applicable, O is completely not applicable)
This allows for expressions that blur the boundaries. The membership function is based on a triangle as shown in FIG. Parameters of this triangle P In P 2+ P
By determining the values of the three points of 3, the vague concept of the input data is expressed. In fuzzy inference, the suitability of input data is inferred using a membership function. For example, ``If you pound a watermelon and it makes a good sound,
That watermelon tastes good. ” “When you hit this watermelon, it makes a very good sound.” “Therefore, this watermelon must taste very good.” Fuzzy reasoning is to find the third sentence based on the first sentence, which is called a control rule. . The input data is the sound made when tapping a watermelon, and the variables such as good and very good are called fuzzy variables, and membership functions represent criteria for decisions. When you listen to the sound of a watermelon and input it, its fitness is determined by the membership function corresponding to the fuzzy variables appearing in the conditions of the control rule, and the effectiveness of the execution is obtained.

In other words, each input data (for example, the maximum thermal stress value of the pressure-resistant part,
The effectiveness or priority of each constraint condition can be obtained based on the goodness of fit of the membership function corresponding to the delay time from the startup schedule, etc.), and the control rules based on the intuition and experience of a skilled operator can be used to Control operations can be realized based on a large amount of accumulated performance data.

Further, with reference to FIG. 8, a more specific explanation will be given based on a boiler control system diagram proposed prior to this application.

51 inputs measurement signals 63 such as steam temperature, steam pressure, delay time from start-up schedule, thermal stress, etc. from the plant 62, and calculates steam temperature change rate actual value 52 and maximum thermal stress actual value 53 of thick wall part. This is a calculation unit which is the first means to do this. Reference numeral 58 denotes a life consumption amount calculating unit which is a second means for receiving the thermal stress maximum actual value 53 and calculating a lifetime consumption actual value after completion of one heat cycle. 65 is the thermal stress maximum actual value 53,
A database that stores life consumption values 64.

68 is a thermal stress maximum limit value calculation unit that receives the life consumption amount command 67 assigned to the activation and calculates the thermal stress maximum limit value 57 corresponding to the life consumption amount command 67 by referring to the data signal 66 of the database 65. The database 65 and the thermal stress maximum limit value calculating section 68 together constitute a third means.

54.55.56 is a data evaluation unit that evaluates the data of information 63.52.53 using a membership function, 7
0 is an inference unit that performs fuzzy inference using the evaluation information of each data evaluation unit 54, 55, and 56 and the control rule 69; A temperature increase rate/pressure increase rate target value calculation unit for calculating,
The data evaluation sections 54, 55, and 56, the control rule 69, the inference section 70, and the calculation section 71 together constitute a fourth means.

60 is temperature increase rate/pressure increase rate target value 59, plant measurement signal 6
62 is a plant to be controlled. Details are shown in Figure 2.

Reference numeral 25 in FIG. 9 is a steam temperature detector for detecting the steam temperature from the superheater 5. 26 is a pressure increase target value setter, and 27 is a temperature increase target value setter for setting the outlet steam temperature of the superheater 5 at the time of completion of temperature increase. 28 is a saturation temperature change rate limit value setting device for setting a saturation temperature change rate limit value for suppressing thermal stress in the thick wall portion of the steam/water separator 4; 29 is a saturation temperature change rate limit value setting device for the thick wall portion of the outlet header of the superheater 5; This is a temperature increase rate limit value setting device that sets a temperature increase rate limit value for suppressing thermal stress. 30 is a rate-of-change target value calculating device, which calculates the detected values of the steam pressure detector 11 and the steam temperature detector 25, and each setting device 26°27.28.2
Each set value set in step 9 is inputted, and a temperature increase rate target value signal a and a pressure increase rate target value signal S obtained by performing predetermined calculations and control based on these values are output. Reference numeral 31 denotes an optimum manipulated variable calculation device, which calculates the detected values of the steam pressure detector 11 and the steam temperature detector 25, and the rate of change target value calculation device 30.
Calculation and control are performed based on the temperature increase rate target value signal a and the pressure increase rate target value signal S given by and according to a predetermined formula, and the resulting fuel flow control valve opening command signal C2 and superheat A turbine bypass valve opening command signal d2 and a turbine bypass valve opening command signal e2 are output.

35 is a differentiator which inputs the detected value of the steam pressure detector 11, differentiates it, and calculates the actual pressure increase rate; 33 is a differentiator which calculates the pressure increase rate obtained by the differentiator 35 and the pressure increase rate target value signal a; This is a subtracter that compares the voltages and outputs a boost rate deviation signal f, which is the deviation thereof. Further, 36 is a differentiator that inputs the detected value of the steam temperature detector 25, differentiates it, and calculates the actual temperature increase rate;
34 is a subtracter that compares the temperature increase rate obtained by the differentiator 36 and the temperature increase rate target value signal S, and outputs a temperature increase rate deviation signal g that is the deviation thereof. 32 is a correction operation amount calculation device;
Each opening command signal c! from the optimal operation amount calculation device 31 input earlier! +d2+e2 is corrected by a predetermined calculation and control based on the deviation signals f and g, and corrected opening command signals cZ'+d2' and ez' are output.

The action of the first means is to take in the plant measurement signal and calculate the heat transfer between the fluid and the metal of the pressure-resistant part, the temperature distribution in the metal of the pressure-resistant part, and the thermal stress components in the axial, radial, and connection directions based on the internal fluid conditions of the pressure-resistant part. It is to calculate.

The action of the second means is one heat cycle (usually starting-load) in which the fluid temperature inside the pressure-resistant part changes from a certain point of interest (usually the conditions at stop) and returns to the value at the point of interest. During the operation-stop period), the life consumption due to fatigue of the relevant part can be estimated from the change width (difference between positive maximum and negative maximum) of the difference between the three components of thermal stress (principal stress difference) calculated by the first method. , by calculating the maximum value of the square root of the sum of the squares of the three components (equivalent stress) and the life consumption due to creep over time, and calculating the life consumption during one heat cycle applied to the part by the sum of both. be.

The details of the operations of the first means and the second means are as described above in the previously published Japanese Patent Application No. 1tJi57-223939,
-115901 [Boiler stress monitoring device], patent application 58-
No. 116201, JP-A-60-11002 "Boiler load control device" specification and Hitachi Review Vol. 65 No. 6 p.
391r Boiler Thermal Stress Monitoring System”.

The third means uses the data stored in the database 65 to determine the fi1-type parameters b0. Determine b. This embodiment corresponds to the case where X is determined by knowing y in Equation 11, and the determined parameters are converted to b3° by the third means.

If b31 (the left side of the subscript indicates the means) is given, the following formula will work.

The action of the fourth means is based on the plant measurement signal 63 and the first
The third means has the function of calculating the temperature increase rate/pressure increase rate target value from the steam temperature change rate actual value 52 and thermal stress maximum limit value 57, a detailed diagram of which is shown in FIG. In order to calculate the target value of the temperature increase rate/pressure increase rate, predictive control is required because there is a long delay due to heat capacity, heat conduction, etc. before thermal stress reaches its maximum due to fluctuations in fluid temperature. be.

The method described here predicts the target value 59 of the temperature increase rate/pressure increase rate from the delay time 63 from the startup schedule, the steam temperature change rate actual value 52, and the thermal stress maximum limit value 57, but there are other methods as well. It is also conceivable to input data such as thermal stress on the turbine side or fluid temperature on the inlet side of the steam/water separator as a measure against protupene. In the figure, 54 is a startup schedule evaluation section, 55 is a temperature increase rate evaluation section, 56 is a thermal stress maximum value evaluation section, 70 is an inference section, 71 is a temperature increase rate/pressure increase rate target value calculation section, and 69 is 1). 2) is an example of a control rule for inferring the target value 59. 1): The delay time is slightly delayed (NS), the temperature increase rate is medium (PM), and the thermal stress P maximum limit value If is small (PS), set the temperature increase rate (ΔT) to medium (PM) and reduce the pressure increase rate (ΔP).
(PS) Let it be.

2): If the temperature increase rate is small (PS) and the maximum thermal stress limit value is medium (PM), increase the temperature increase rate (ΔT) (PB),
Set the pressure increase rate (ΔP) to medium (PM).

It represents the rule. The control rule is a rule that predetermines what to do with the exit in a certain situation (membership functions of evaluation units 54, 55, and 56 in the figure). Now, if the inputs 63, 52, and 57 are m, , mg, and m, respectively, then according to the rule of control regulation 69 1), m,
=Ns, mz =PM.

The degree of applicability (grade) of the proposition m3=PS is 0.8°0.2 from each membership function.
It becomes 0.5. The temperature increase rate/pressure increase rate target value (ΔT) is a fuzzy variable for the output of this control rule.

Since ΔP) is the membership function on the right side in the inference unit 70, the shaded part is obtained by multiplying the whole by 0.2. In other words, this corresponds to performing safer control by multiplying by a safety factor. It is also conceivable that the inference unit 70 calculates the values of the fuzzy variables (ΔT, ΔP) by averaging the degree of applicability of the propositions, which is determined by the control method (priority of control rule, confidence level). Good. Similarly, from the control rule 69-2), the fuzzy variable (ΔT
.

ΔP) selects the shaded part of 2) in the inference section 70.

The conclusion for each control rule is that in the case of fuzzy control, inference synthesis agents are often used, and the result of the sum operation of the fuzzy sets of outputs for synthesis is the 2 mT and m, respectively, are obtained by dividing the area of the membership function indicating the target value into two equal inference values.

The fifth means receives the temperature increase rate/pressure increase rate target value 59 from the fourth means, but this signal is necessary for each part subject to life management. Vessel 4
Calculate. The operation of the fifth means is as described in the specification of "Boiler Startup Control Device" (Japanese Patent Application No. 59-145932, Japanese Patent Application Laid-open No. 61-24905), and depending on the state of the plant, Start by calculating the plant operation amount (optimum operation amount) such as valve opening under the minimum fuel input condition to start the shortest time within the temperature increase rate/pressure increase rate target value limit allowable range given by signal 59. control.

Furthermore, in order to improve the accuracy of calculating the optimal operation amount of the fifth means, we have developed a "boiler startup control device" (Japanese Patent Application No. 60-282042, Japanese Unexamined Patent Publication No. 62/1983) having a parameter adaptive control function.
-141403) may be used.

With the above conventional technology, it is possible to start up the boiler efficiently within a preset period of time by controlling it using fuzzy theory while thermal stress is occurring in the boiler. It is difficult to respond when the required completion time changes.

Furthermore, when a certain operation is performed in response to a request, it is difficult to quantitatively grasp how the state changes after the operation, and it cannot be said that sufficient consideration is given to safety.

The present invention is constructed based on the problems of the prior art and the technical problems described in the background section of the invention, and implements an operation to achieve the steam temperature change rate calculated using a fuzzy inference function. In this case, by displaying the simulation results after performing this operation on the screen device, it is possible to quantitatively understand the change in the state of this operator.

In addition, if the simulation results are not satisfied, a control stop signal is output to the plant control unit, and a fuzzy inference control rule change signal is used to obtain results that correspond to changes in factors, and to perform control that takes safety into account. This is a boiler control device configured to make it possible.

[Implementation row]

Embodiments of the present invention will be specifically described below with reference to the drawings.

In FIG. 1, 63 is the steam temperature from the plant 62;
These are measurement signals such as steam pressure and thermal stress, and in response to this information, the life consumption amount calculation unit 58 calculates the life consumption amount after one heat cycle is completed.

68 is the life consumption value 64 from this life consumption amount calculation unit 58
This is a thermal stress maximum limit calculation unit that calculates a thermal stress maximum limit value 57 based on humidity. 80 receives the thermal stress maximum limit value 57 and the plant measurement signal 63, and uses a fuzzy inference function to transfer the target value 59 of the steam temperature change rate to 60, which calculates the manipulated variable. The manipulated variable signal 61 calculated by the manipulated variable calculator 60 passes through the controller 81 and controls the plant 62 using a control signal 82 . Further, the manipulated variable signal 61 from the manipulated variable calculation section 60 is transferred to the simulation section 83, the control rule change signal 85 is sent to the steam temperature change rate calculation section, and the control stop signal 84 is transferred to the simulation section 83.
is sent to the control section 81.

FIG. 2 shows the detailed configuration of the simulation section 83.

The configuration of the simulation section 83 is based on the plant measurement signal 6.
3 and the manipulated variable signal 61 are respectively stored in the plant data file 9.
0 and the manipulated variable data file 91 to the simulator 9
2, parameters are selected from the parameter menu file 95 according to the amount of operation on the keyboard 94, and the results of the simulation performed by the simulator 92 are displayed as a trend graph on the screen display device 96. Further, by operating the keyboard 94, a control stop signal 84 and a control rule change signal 85 are transferred to the control section 81 and the steam temperature change rate calculation section 80, respectively.

Next, the operation of this simulation section 830 will be explained. The plant data file 90 and the manipulated variable data file 91 are files that store the plant measurement signal 63 and the manipulated variable 61, and are used to import necessary data into the simulator 92 when a simulation request is made from the keyboard 94. It will be done. In addition, the parameter menu file 95 is prepared so that a plurality of display screens as shown in FIG. pressure, etc.) to enable simulation. In addition, the plant simulation results (trend graph) shown in Figure 3 allow operators to quantitatively understand plant trends by displaying actual values and predicted prices up to the present time on the same graph. It becomes possible to understand it.

If requirements such as the expected startup completion time change during boiler startup operation, for example, change the lifetime consumption from 80% to 90% and increase the steam temperature change rate limit value.
The fuzzy inference control rule in the steam temperature change rate calculation unit 80 is changed by a control rule change signal 85 from the keyboard 94 via the simulator 92, and the simulation is repeated until a result corresponding to the required change is obtained. In this way, until a simulation corresponding to the change in demand is obtained, the control of the plant is maintained as it is by outputting the control stop signal 84 from the simulator 92 to the control unit 81, and a new manipulated variable signal 61 corresponding to the change in demand is output. The control stop signal 84 is not added or subtracted until this is obtained. This function makes it possible to respond even when driving demands change, and to perform control that fully takes safety into consideration.

〔effect〕

In the present invention, the control rule for fuzzy inference in the steam temperature change rate calculating section is changed, and the simulation is performed again using the manipulated variable based on the change, so that the following effects can be achieved.

(11) It is possible to determine the temperature increase rate/pressure increase rate necessary to suppress the thermal stress generated in the thick wall portion within the limit value according to the plant situation.

(2) It is possible to grasp the allowable value of generated thermal stress necessary for startup within the arbitrarily given allowable life consumption value of the thick-walled part, depending on the situation of the plant.

(3) By incorporating a fuzzy inference function into the calculation unit for the target (limit) value of the temperature increase rate/pressure increase rate in fl) above, it is possible to consider the priority or effectiveness of many constraint conditions. , it becomes possible to control and operate the plant while managing the life consumption of the pressure-resistant parts.

[Brief explanation of the drawing]

1 and 2 are system diagrams of a boiler control device according to an embodiment of the present invention, FIG. 3 is a diagram showing a display example of an image display device, and FIG. 4 is a system diagram of a conventional boiler control device, Figure 5 is a timing chart of a conventional boiler control device, Figure 6 is a control conceptual diagram showing conventional boiler control, Figure 7 is a diagram showing the basic form of membership functions that determine fuzzy variables, and Figures 8 and 9. The figure shows a control system diagram of a conventional boiler control device.
FIG. 10 is a detailed diagram of the control means of the control device shown in FIG. 8. 51... Calculation unit, 54-56... Data evaluation unit, 58... Life consumption calculation unit, 60.
...Manipulated amount calculation unit, 62...Plant,
65...Database, 68...Thermal stress maximum limit value calculation unit, 70...Assistant theory Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 10I+! 2 13 pq Fig. 6 Fig. 7 Total of 5 stitches (wait) Fig. 9

Claims (1)

[Claims] a first calculation unit that calculates the rate of temperature change of the internal fluid in contact with the pressure-resistant part and the generated thermal stress value of the pressure-resistant part; and a second calculation unit that calculates the maximum value of the generated thermal stress based on the data from the first calculation unit. and at least the fluid temperature change rate determined by the first calculation section and the generated thermal stress maximum value determined by the second calculation section as input data, calculate the generated thermal stress. a third calculation unit that calculates a target control value of a fluid temperature change rate necessary to maintain the pressure-resistant part below a local maximum value; and a control means that controls an amount of heat that the fluid gives to the pressure-resistant part, 3. A boiler control device characterized in that the control means is configured to operate in accordance with the target value set by the calculation unit of No. 3.