JP2674640B2 - Optimization control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optimization control device used in, for example, a pulp and paper manufacturing plant, and particularly to optimization of a plant without a program model suitable for the plant. The present invention relates to an optimization control device that performs control. (Prior art) Normally, as a plant optimization control method, a model of the plant is created and the optimum operation amount of the plant is found on the model to perform optimization control. There is an optimization control method in which the evaluation is performed while changing the value to approach the optimum point. This latter model-less optimization control is also called an experimental optimization method, and is conventionally performed using the means shown in FIGS. 5 and 6. That is, this model-less optimization control determines a search point by calculation based on the process data PV of the plant 1, and actually gives the search point data SP determined here to the plant 1 to obtain a time constant of the plant or more. After being delayed by the time, the process data PV, that is, the evaluation value of the plant is read from the plant 1. Then, the evaluation value itself or a result obtained by performing arithmetic processing based on the evaluation value is used as an evaluation function, and it is determined whether or not the evaluation function is converged. When it is determined that it has converged, the control of the plant is continued using the determined search point data, and when it is determined that it has not converged, the search point is further changed to perform the same control and processing as described above. The optimization control is performed by iteratively finding the optimum search point. (Problems to be Solved by the Invention) However, the above-described optimization control evaluates the plant 1 after delaying at least the time of the plant time constant after giving the search point data to the plant 1. To
The following problems arise. For example, when the search points Xn to Xn + 1 are determined, the evaluation value is Pn to Pn + 1 as shown in FIG.
Move to. At this time, if these evaluation values are in the relationship of Pn <Pn + 1, there is no problem because the plant 1 is in the direction of optimization, but for example, in the case of the relationship of Pn> Pn + 1, the plant 1 is in the worsening direction. Nevertheless, the plant time constant T
Since the operation is continued during the time of
When Xn + 1 is obtained, it means that the plant 1 is already operating in a state worse than the state of the search point Xn. As a result, the plant 1 wastes energy, raises the operating cost, lowers productivity and various efficiencies, and, in the worst case, operates outside the constraint conditions of the plant 1. In some cases, the plant is operating in a very dangerous state. This is a particularly serious problem in the case of a plant having a long plant time constant (several tens of minutes in this recovery boiler) such as a recovery boiler used in a pulp and paper manufacturing plant. Since the present invention has been made in view of the above points, the operating time of the deterioration tendency in the plant is shortened as much as possible to accelerate the time until convergence, the operating cost is reduced, and the product quality and productivity are improved. An object is to provide an optimization control device that can contribute. (Means for Solving Problems) Therefore, in order to achieve the above-mentioned object, the present invention obtains a search point based on plant data obtained from a plant, and determines this search point for a time equal to or longer than a plant time constant. In the optimization control device for determining the optimum search point given to the plant in, determine whether the plant data read from the plant in a predetermined time within a time shorter than the time constant conforms to the plant conditions However, if it does not meet the plant conditions, it counts up, and when this count value reaches a predetermined value, it is determined that the plant is in a deterioration tendency, and a new data is added based on the plant data up to that point. The search points are obtained and the search points are given to the plant without taking time longer than the plant time constant. (Operation) Therefore, by adopting the above means, the present invention obtains the evaluation value and the constraint value while reading the plant data from the plant within the time of the plant time constant, and these values are the evaluation values which are the plant conditions. When the deviation allowable range or the constraint value condition is deviated more than once, it is determined that the plant is in the worsening direction, and the plant evaluation and the constraint determination are rounded up and the control is shifted to the optimization control. It is possible to judge the deterioration tendency of the plant within the time of the plant time constant, and it is possible to change the direction of the search point based on the result of this judgment and perform optimization control, so the plant can be converged quickly. By operating the plant properly, energy can be saved, and product quality and productivity can be improved. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. That is, the device of the present invention executes optimization control based on a predetermined program by using a microcomputer, but it can be functionally represented schematically by blocks as shown in FIG. In the figure, 1 indicates a plant such as a recovery boiler found in, for example, a pulp and paper manufacturing plant, which is normally an optimization control unit.
Optimization control is performed by 11. The optimization control unit 11 normally determines a search point based on the plant data a from the plant 1 and supplies the search point data b to the plant 1 to delay the time by a process time constant, and then the plant. 1 is evaluated, and this is repeated to determine the optimum point. However, when it is determined that the plant 1 is in a worsening tendency, a new search point is obtained based on the plant data up to now and the plant is selected. It has the function of giving and controlling. Reference numeral 10 is a deterioration tendency judgment function block, which has a deterioration tendency judgment activation control means 12. This deterioration tendency determination start control means 12 is provided from the optimization control unit 11 to the plant 1
It is activated after the search point data is given to the control circuit, and has a function of controlling the output of the start command and the determination cycle for determining the deterioration within the process time constant and the initialization of the counter 13. Reference numeral 14 denotes a data acquisition calculation means that receives a start command from the start control means 12 and acquires the plant data c related to the deterioration tendency determination (evaluation, restriction) from the plant 1, and if necessary, this is a filtering process for noise removal or a filtering process for noise removal. Various calculation processes are performed based on the plant data c for evaluation and constraint to obtain evaluation value and constraint value data. Reference numeral 15 is a comparison / judgment means for receiving the evaluation value and the constraint value data c'from the data fetching operation means 14 and comparing it with the plant condition (constraint value condition, allowable evaluation value deviation range) to judge whether or not there is a worsening direction. Therefore, this is specifically comparing the current constraint value data with the constraint value conditions stored in advance in the memory 16 in the case of the determination of the constraint value condition, and the optimization in the case of the determination of the evaluation value. Memory unit 16 to memory 16
It is determined whether or not the deviation between the previous evaluation value data and the current evaluation value data read via the same is within the evaluation value deviation allowable range prestored in the memory 16.
If the comparison / determination means 15 is in the worsening direction, a signal for counting up the count 13 as the counting / determination means is output. Reference numeral 17 denotes a trigger generating means, which has a function of sending a start trigger signal d to the optimization control unit 11 during the delay of the plant time constant when the count value of the counter 13 reaches a preset value. . Upon receiving the activation trigger signal d, the optimization control unit 11 obtains a new search point based on the plant data so far, and gives the search point to the plant 11 without a time longer than the plant time constant. is there. Next, the operation of the apparatus configured as described above will be described with reference to the flowchart of FIG. The optimization control unit 11 determines a search point based on the plant data a, gives this search point data b to the plant 1 and delays it for the time of the plant time constant, reads the plant data a from the plant 1 and reads the plant data a. I am evaluating,
When the search point data b is given to the plant 1, a start signal for judging a deterioration tendency is sent to the deterioration tendency judging function block 10 almost at the same time. This deterioration tendency judgment function block
Reference numeral 10 is for judging the deterioration tendency of the plant 1 within the time of the plant time constant. That is, when the start signal is received, the deterioration tendency determination activation control means 12 initializes the counter 13 and activates the data acquisition calculation means 14 in step S1. Here, the data acquisition calculation means 14
As shown in S2, the plant data c regarding the evaluation and constraints is read from the plant 1, and if necessary, the plant 1 is subjected to filtering processing for noise removal and various arithmetic processing.
The current evaluation value and current constraint value of are obtained. Thereafter, the evaluation value and the constraint value are sent to the comparison / judgment means 15 to be checked. First, in step S3, the current constraint value (gi, i = 1 to n) is compared with the constraint value condition (gli, i = 1 to n) read from the memory 16, and gi− (gli = αi) ≧ 0 i = 1 to m (upper limit constraint) gk− (glk = αk) ≦ 0 k = m + 1 to n (lower limit constraint) When it is determined that the tendency is worse, the counter 13 is incremented by one. . α is a preset allowable value. When it is determined that the constraint value does not tend to deteriorate at present, the process proceeds to step S4 and the evaluation value is determined. This evaluation value determination step S4 is performed in the present evaluation value (fi, i =
1 to n) and the previous evaluation value ▲ f stored in the memory 16
^j-1 _i ▼, If there is a relation of (2), it is determined that there is a tendency of deterioration, and the counter 13 is counted up (step S5). If the current evaluation value does not tend to deteriorate, the counter 13 is cleared as shown in step S6, and the plant time constant T is divided by 1 / n as shown in step S7.
Delayed by the time (see FIG. 3a), and if the time after that delay time has not reached the plant time constant T, the process returns to step S2 and the plant data c related to the evaluation value and the constraint value is returned from the plant 1 again. Is read and the operating tendency of the plant 1 is judged by comparing with the constraint value condition and the evaluation value deviation allowable range. Then, in the operation tendency judgment of the plant 1 as described above, for example, the current constraint value obtained in step S2 exceeds the constraint value condition in step S3 and the counter 13 is counted up, which is the preset value as in step S9. When it reaches, the process moves to step S10 and sends a start signal to the optimization control unit 11. Further, in step S4, the evaluation value determination means causes the difference between the current evaluation value and the previous evaluation value to be out of the allowable range and counts up 13, and if it reaches the preset value, the optimization control is performed as described above. A start signal is sent to the unit 11, and at the same time, a signal for stopping the judgment of the operation tendency of the plant 1 is sent to the deterioration tendency judgment start control means 12. The counter
The meaning of the preset value 13 is to judge that the plant 1 is truly in a tendency to deteriorate when the constraint value condition is exceeded or the current evaluation value is deteriorated continuously for the number of times corresponding to the preset value. When a start signal is given to the optimization control unit 11 in step 10, the control unit
11 indicates that the optimization control which is currently continuing is canceled even within the time of the plant time constant T, a new search point is determined based on the plant data so far, and this search point data is given to the plant 1. After that, the activation signal is sent again to the deterioration tendency activation control means 12. The evaluation value which is the search point data at this time is stored in the memory 16 and used as the previous evaluation value data. That is, assuming that the preset value of the counter 13 is [4], for example, the device of the present invention will remove the same value from the plant 1 every predetermined time t within the time of the plant time constant T as shown in FIG. 3 (a). Optimization is performed when the evaluation value data (see c in the same figure) and the constraint value data (see d in the same figure) in FIG. By shifting to the operation unit 11, the operation amount of the plant is given to the plant 1 from the dotted line in the opposite direction as shown in the experiment shown in the figure, and from that time, the optimization control unit 11 again sets the time of the plant time constant T. The plant 1 is evaluated later, and the constraint value condition over and the evaluation value deterioration state are determined at each time t within the plant time constant according to the flowchart shown in FIG. Therefore, according to the configuration of the embodiment as described above, the plant is evaluated with the plant time constant T, and the constraint value excess and the evaluation value deterioration tendency of the plant 1 are determined every time t within the time of the plant time constant T. Since, for example, time t
The optimization control unit 11 evaluates the plant even if it is not determined that the plant 1 is in a worsening tendency by the deterioration tendency determination for each, so that the optimization control of the plant 1 is ensured. Further, since the plant 1 determines whether or not the constraint value condition is exceeded within the time of the plant time constant T, it can be determined that the operation of the plant 1 is not preferable even if the evaluation value data does not deteriorate. It is possible to contribute to the control of the exhaust gas discharged from the recovery boiler used in the pulp and paper manufacturing plant to the specified value or less. Further, even when the constraint value condition is not exceeded, if the evaluation value of the plant 1 is in a deteriorating direction, it can be promptly detected and the operation amount of the plant 1 can be changed to perform the optimization control. Furthermore, if the preset value of the counter 13 is determined according to the plant, the deterioration direction of the plant can be reliably determined even within the time of the plant time constant, and thus the optimization direction can be swiftly changed. Moreover, since the present apparatus can shorten the operating time of the plant 1 in the worsening direction, it is possible to save the operating energy of the plant,
Product quality can also be improved. In the above embodiment, the constraint value condition determination is performed first from the viewpoint that plant safety is important, but the order of these determinations may be reversed, or the constraint value condition over determination is not performed. It is also possible to just judge the deterioration of the evaluation value.
Moreover, although the deterioration direction of the plant is determined by the logical sum of the constraint value condition over and the evaluation value deterioration, it may be determined by the logical product. Further, the counter 13 is commonly used for counting up the judgment results of both the constraint and the evaluation, but it may be provided individually. In particular, in the case of a plant in which the appearance of the transient state of the plant is different between the constraint value data and the evaluation value data after the search point data is assigned to the plant, this is effective from the viewpoint of preventing malfunction. Furthermore, the evaluation value deterioration judgment is
Although the previous evaluation value data is used, for example, the best evaluation value data may be used during the optimization search of one cycle instead of the previous evaluation value, or the best evaluation value may be obtained through several cycles. Data may be used.
This is advantageous, for example, in increasing the efficiency of the search when the plant 1 is relatively stable and reproducibility can be expected to some extent. Next, FIG. 4 is a system diagram in which the device of the present invention is applied to, for example, a combustion optimization control system for a recovery boiler. That is, this system uses the black liquor discharged as waste liquid in the chip digestion process for combustion in the recovery boiler in addition to the smelt (chemical raw material) used in the chip digestion process, as well as in the recovery boiler for recovering steam, etc. When the black liquor is burned, the air flow rate is adjusted to increase the burning efficiency.
The device of the present invention is applied for adjusting the air flow rate. In the figure, 21 is a recovery boiler that generates the above-mentioned smelt which is a raw material for chip cooking chemicals using black liquor as a combustion raw material, and the black liquor discharged as waste liquid by producing pulp from the chip cooking step is black liquor. It is sent through the injection line L1 and the injection gun 23 as the injection black liquor 22
Is to be injected into the boiler. Reference numeral 24 is a char bed in which the jet black liquor 22 is dried and accumulated, and a reduction reaction is caused by the combustion of the char bed 24, and a smelt 25 such as sodium sulfide is recovered from the spoutro 26. Further, air is sent to the recovery boiler 21 from the combustion air line L2 and blown into the lower, middle and upper stages of the recovery boiler. further,
The recovery boiler 21 has a water supply pump installed on the water supply line L3.
Water supply 28 is sent by 27. In the recovery boiler 21, 29 is a economizer, 30 is a drum, 31 is a superheater, 32 is a boiler heat transfer tube, 33 is a bank tube, and combustion gas 34 from the combustion of the boiler 21 causes the boiler heat transfer tube 32, etc. Get exhaust gas
Emitted as 35. In this process, the water supplied by the water supply pump 27 is heated by the exhaust gas 35 in the economizer 29 to become hot water, and subsequently heated by the bank tube 33 of the drum 30 to be steam and then sent to the superheater 31, Here, it is heated and taken out as main steam 36 from the main steam line L4 to the outside of the system. By the way, the boiler efficiency in the recovery boiler as described above is determined by the black liquor input heat quantity S1 obtained by the black liquor input heat quantity calculation unit 43 using the density 41 and the flow rate 42 of the injected black liquor and the water supply 28
Flow rate 44 and temperature 45 signals S2, S3 and main steam 36 flow rate
Introducing the output heat amount S4 obtained by the output heat amount calculation unit 49 using the 46, the pressure 47 and the temperature 48 into the boiler efficiency estimation calculation unit 50,
Here, both signals S1 and S4 are divided to obtain a boiler efficiency estimated value S5, which is supplied to the extreme value controller 51, so that the boiler efficiency estimated value S5 is maximized for each combustion air S6, S7. Some output distribution command values S8 and S9. 52 and 53 are the distribution command values S8 and S9 for the output flow rate 44 of the air flow rate control unit (not shown).
Is a multiplication unit that obtains, for example, a combustion flow rate command value for the lower stage flow rate adjusting unit 55 and the middle stage flow rate adjusting unit 56. Therefore, the device of the present invention is incorporated in the extreme value controller 51 in the system as described above, and the extreme value controller 51 has the SO ₂ concentration detected from the exhaust gas 35 as the plant data c related to the evaluation value. The NOx concentration signal S11 is input as the plant data c related to the signal S10 and the constraint value. As described above, when the NOx concentration exceeds the NOx concentration condition value, the counter 13 counts up, and this time the SO ₂ concentration is increased. When the difference between the value and the previous SO ₂ concentration value exceeds the allowable range, it is counted up, and when this counter 13 reaches the preset value, if it is controlled to increase the current flow rate, it will be lowered by the extreme value controller 51. The optimization control is performed while controlling the flow rate in the direction. Therefore, in the combustion optimization control system of this recovery boiler, the SO ₂ concentration and NOx can be exhausted with appropriate values. (Effects of the Invention) As described in detail above, according to the present invention, even in a plant having a certain plant time constant, the deterioration direction of the plant is detected within the plant time constant, and the direction of the plant operation amount is changed. Since the control is performed in accordance with the above, the optimizing control can be performed promptly by shortening the operating time, energy can be saved, the quality of the product can be improved, etc., and it is possible to provide the optimizing control device capable of increasing the productivity of the plant. .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 to FIG. 3 are for explaining one embodiment of the device of the present invention, and FIG. 1 is a functional block diagram schematically showing the device of the present invention, and FIG. Is a flow chart for explaining the operation of the device, FIG. 3 is a diagram showing the relationship between the plant time constant and the plant manipulated variable, and FIG. 4 is a system diagram in which the device of the present invention is applied to a combustion optimization control system for a recovery boiler. FIG. 5 is a schematic diagram for explaining a conventional device, and FIG. 6 is a diagram for explaining a defect of the conventional device. 1 ... plant, 10 ... deterioration tendency determination function block, 11
...... Optimization control unit, 12 …… Deterioration tendency judgment start control means, 13 …… Counter, 14 …… Data acquisition calculation means,
15 …… Comparison judgment means, 16 …… Memory, 17 …… Trigger generation means.

   ────────────────────────────────────────────────── ─── Continuation of front page    (72) Inventor Yoshikazu Fukushima               1-1, Jujo-cho, Yatsushiro-shi Tojo Paper Co., Ltd.               Inside the Yatsushiro Factory (72) Inventor Yohei Shiogoshi               1-1, Jujo-cho, Yatsushiro-shi Tojo Paper Co., Ltd.               Inside the Yatsushiro Factory (72) Inventor Masaru Nishimura               4-135 Shimaya, Konohana-ku, Osaka City Kawasaki               Heavy Industry Co., Ltd.Osaka Factory (72) Inventor Yasumitsu Kurosaki               1-1 Kawasaki-cho, Akashi-shi Kawasaki Heavy Industries Ltd.               Company Akashi factory (72) Inventor Toshiyuki Ibedo               1-1 Kawasaki-cho, Akashi-shi Kawasaki Heavy Industries Ltd.               Company Akashi factory (72) Inventor Shiro Nakabayashi               1-1 Kawasaki-cho, Akashi-shi Kawasaki Heavy Industries Ltd.               Company Akashi factory (72) Inventor Kazuyuki Iizuka               1-1-1 Shibaura, Minato-ku, Tokyo Stock market               Company Toshiba Head Office (72) Inventor Ryuichi Kuwata               No. 1 Toshiba Town, Fuchu City, Tokyo Higashi Co., Ltd.               Inside the Shiba Fuchu factory (72) Inventor Ao Kumaki               No. 1 Toshiba Town, Fuchu City, Tokyo Higashi Co., Ltd.               Inside the Shiba Fuchu factory (72) Inventor Atsushi Muramatsu               No. 1 Toshiba Town, Fuchu City, Tokyo Higashi Co., Ltd.               Inside the Shiba Fuchu factory                (56) References Japanese Patent Laid-Open No. 50-42281 (JP, A)                 JP 60-93507 (JP, A)                 JP 58-40616 (JP, A)                 Japanese Patent Laid-Open No. 50-53780 (JP, A)                 JP-A-56-17404 (JP, A)                 JP 58-5807 (JP, A)                 57-103506 (JP, U)                 Actual development Sho 58-15206 (JP, U)                 58-97608 (JP, U)

Claims (1)

(57) [Claims] Obtaining a search point based on the plant data obtained from the plant, the search point data is given to the plant to evaluate the operating state after a time equal to or longer than the plant time constant, and in the optimization control device for determining the optimum search point, It operates after the search point data is given to the plant,
Sequentially read the plant data from the plant at each predetermined cycle within a time shorter than the plant time constant, determine whether or not this plant data conforms to the plant conditions, and if the plant conditions do not conform, A plant tendency judging means for outputting a count-up signal, a preset value set in advance from a deterioration tendency in the operation of the plant is set, and is cleared after giving the search point data to the plant, from the plant tendency judging means. It counts up each time it receives a count-up signal, and when this count value reaches the preset value,
Count determination means for determining that the plant is in a deterioration tendency, and if this count determination means is in a deterioration tendency, a new search point is obtained based on the plant data up to that point, and the search point data And an execution means for giving the above-mentioned plant to the plant without exceeding a time longer than the plant time constant. 2. The optimization control device according to claim 1, wherein the plant condition uses one of the evaluation value deviation allowable range data and the constraint value condition data of the plant. 3. The plant tendency determining means of whether or not the plant data conforms to the plant condition compares the plant data of the present evaluation with the plant data of the previous evaluation, and the deviation is within the evaluation value deviation allowable range which is the plant condition. The optimization control device according to claim 1, further comprising an evaluation value determination means for determining whether or not 4. The plant tendency determining means of whether or not the plant data conforms to the plant condition, a constraint value condition determining means of determining whether or not the plant data of the present evaluation exceeds the constraint value condition which is the plant condition, Claim 1 which has an evaluation value judgment means which compares the plant data of this time evaluation with the plant data of the last time evaluation, and judges whether the deviation is within an evaluation value tolerance range. The described optimization control device.