JP6036376B2 - Boiler system - Google Patents

Description

  The present invention relates to a boiler system that controls a combustion amount of a boiler according to steam consumption by a PI or PID algorithm.

  DESCRIPTION OF RELATED ART Conventionally, the boiler system provided with the boiler and the control part which controls the combustion amount of a boiler according to the steam consumption (required load) of a steam using facility is known. In such a boiler system, the steam pressure in the steam header (hereinafter also referred to as “steam pressure value”) is adjusted according to the fluctuation of the steam consumption so that the steam steam consumption becomes a constant target steam pressure value regardless of the fluctuation of the steam consumption. Thus, the combustion amount of the boiler is controlled. Conventionally, in order to keep the steam pressure value of the steam header at the target steam pressure value against fluctuations in steam consumption, the steam amount to be generated in the boiler (hereinafter also referred to as “PID required steam amount”) is controlled by the PID algorithm. A boiler system using a technique has been proposed (see, for example, Patent Documents 1 and 2).

JP 2002-73105 A Japanese Patent No. 3805611

  By the way, in the control of the steam amount by the PID algorithm, for example, when the steam consumption near the maximum generated steam amount of the boiler system continues and then the steam consumption suddenly decreases, the positive accumulated up to then The calculated PID required steam amount does not decrease immediately due to the influence of the integral amount. For this reason, the steam pressure value of the steam header may temporarily exceed the target steam pressure value temporarily. After the steam pressure value suddenly exceeds the target steam pressure value, a negative integral value is accumulated this time, so that a rapid decrease in the PID required steam amount occurs. At this time, since the negative integral amount is excessively accumulated, the return of the output steam amount is delayed, and the steam pressure value subsequently decreases. Moreover, even if the output steam amount returns and the steam pressure value starts to rise, a large response delay occurs until the steam pressure value rises due to the influence of an excessive negative integral amount. Thereafter, this repetition causes a so-called hunting phenomenon in which the steam pressure value of the steam header fluctuates up and down without converging to the target steam pressure value. Such a hunting phenomenon may occur immediately after the boiler system is started.

  Therefore, an object of the present invention is to provide a boiler system that can quickly converge a steam pressure value to a target steam pressure value even when the steam consumption fluctuates rapidly.

  In the present invention, a boiler that generates thermal energy according to the amount of fuel burned, and a thermal energy output value that is an output value of the thermal energy generated in the boiler becomes a preset target thermal energy output value. Control means for controlling the combustion amount of the boiler based on a control amount calculated by a PI algorithm or a PID algorithm, and the control means has a deviation proportional output value calculated by the PI algorithm or PID algorithm. The present invention relates to a boiler system that resets a deviation integral output value calculated by the PI algorithm or PID algorithm to zero when the maximum output of the boiler is exceeded.

  Moreover, it is preferable that the said control means prevents the said deviation integral output value from exceeding the maximum output of the said boiler.

  Moreover, it is preferable that the said boiler is equipped with the some boiler main body which can increase / decrease the combustion amount continuously.

  Moreover, it is preferable that the said target thermal energy output value is set to below the maximum upper limit thermal energy output value which can operate | move the said boiler.

  According to the present invention, it is possible to provide a boiler system that can quickly converge a steam pressure value to a target steam pressure value even when the steam consumption fluctuates rapidly.

It is a schematic structure figure of boiler system 1 concerning a 1st embodiment. It is a graph which shows the steam pressure in the case of implementing pressure control only by the normal PID algorithm, using the boiler system 1 shown in FIG. 1 as a model. It is a graph which shows the steam pressure and steam quantity when zero reset of deviation integral output is performed in addition to pressure control by a normal PID algorithm, using the boiler system 1 shown in FIG. 1 as a model. 2 is a graph showing steam pressure and steam amount when zero reset of deviation integral output and high cut of deviation integral output are executed in addition to pressure control by a normal PID algorithm using the boiler system 1 shown in FIG. 1 as a model. . It is a graph which shows a steam pressure and the amount of steam when pressure control is implemented only by the normal PID algorithm from the state where the steam pressure of the steam header 6 is zero, using the boiler system 1 shown in FIG. 1 as a model. Using the boiler system 1 shown in FIG. 1 as a model, the steam pressure and the amount of steam in the case where zero reset of the deviation integral output is executed in addition to the pressure control by the normal PID algorithm from the state where the steam pressure of the steam header 6 is zero. It is a graph to show. Steam in a case where the boiler system 1 shown in FIG. 1 is used as a model and the zero pressure of the deviation integral output and the high cut of the deviation integral output are executed in addition to the pressure control by the normal PID algorithm from the state where the steam pressure of the steam header 6 is zero. It is a graph which shows a pressure and the amount of steams.

  Hereinafter, preferred embodiments (first to third embodiments) of a boiler system according to the present invention will be described with reference to the drawings.

  First, a first embodiment of a boiler system according to the present invention will be described with reference to FIGS. FIG. 1 is a schematic configuration diagram of a boiler system 1 according to the first embodiment.

  As shown in FIG. 1, the boiler system 1 according to the present embodiment includes a boiler group 2 including five boilers 20, a steam header 6 that collects steam generated in the boiler 20, and an interior of the steam header 6. A vapor pressure sensor 7 that measures pressure and a boiler control device 3 that controls the combustion state of the boiler group 2 are provided.

  The boiler group 2 includes five boilers 20 and generates steam to be supplied to the steam use facility 18 as load equipment. Each boiler 20 generates steam (heat energy) according to the amount of combustion of fuel. That is, the boiler 20 of this embodiment is a steam boiler.

  As shown in FIG. 1, the boiler 20 includes a boiler body 21 in which combustion is performed, and a local control unit 22 that controls the combustion state of the boiler 20.

  The local control unit 22 changes the combustion state of the boiler 20 according to the steam consumption. Specifically, the local control unit 22 controls the combustion state of the boiler 20 based on the number control signal transmitted from the boiler control device 3 via the signal line 16. The number control signal will be described later. Further, the local control unit 22 transmits a signal used in the boiler control device 3 to the boiler control device 3 via the signal line 16. Examples of the signal used in the boiler control device 3 include the actual combustion state of the boiler 20 and other data.

  The steam header 6 is connected to a plurality of boilers 20 constituting the boiler group 2 via a steam pipe 11. The downstream side of the steam header 6 is connected to the steam use facility 18 via the steam pipe 12.

  The steam header 6 collects and stores the steam generated in the boiler group 2. The steam header 6 adjusts the pressure difference and pressure fluctuation of one or more boilers 20 to be combusted, and supplies steam whose steam pressure value is adjusted to be constant (target steam pressure value) to the steam using facility 18.

  The vapor pressure sensor 7 is electrically connected to the boiler control device 3 via a signal line 13. The vapor pressure sensor 7 measures the vapor pressure value (thermal energy output value) of the vapor header 6 and transmits a vapor pressure signal corresponding to the vapor pressure value to the boiler control device 3 via the signal line 13.

  The boiler control device 3 is electrically connected to a plurality of boilers 20 via signal lines 16. The boiler control device 3 controls the combustion state (combustion amount) of each boiler 20 based on the steam pressure value of the steam header 6 measured by the steam pressure sensor 7. The boiler control device 3 will be described later.

  In the boiler system 1 configured as described above, the steam generated in the boiler group 2 is supplied to the steam using facility 18 via the steam header 6.

  In the boiler system 1, the steam pressure value of the steam header 6 varies according to the steam consumption (required load) in the steam using facility 18. The boiler control device 3 (control unit 4) calculates the PID required steam amount by the PID algorithm based on the steam pressure value (physical quantity) of the steam header 6. The PID required steam amount is a steam amount necessary for setting the steam pressure value of the steam header 6 to the target steam pressure value (target heat energy output value). The boiler control device 3 controls the combustion amount of each boiler 20 constituting the boiler group 2 based on the calculated PID required steam amount. Thereby, since the steam amount (output steam amount) supplied from each boiler 20 to the steam header 6 is adjusted, the steam pressure value of the steam header 6 can be brought close to the target steam pressure value. That is, the steam pressure value of the steam header 6 can be kept at a constant target steam pressure value according to the fluctuation of the steam consumption.

  Specifically, if the steam consumption increases due to an increase in demand for the steam use facility 18 and the amount of output steam supplied to the steam header 6 is insufficient, the steam pressure value of the steam header 6 decreases. On the other hand, if the steam consumption decreases due to a decrease in demand for the steam use facility 18 and the output steam amount supplied to the steam header 6 becomes excessive, the steam pressure value of the steam header 6 increases. The boiler control device 3 monitors the fluctuation of the steam consumption based on the fluctuation of the steam pressure value of the steam header 6. And the boiler control apparatus 3 calculates the PID request | requirement steam amount according to the steam consumption of the steam use equipment 18 based on the steam pressure value of the steam header 6, and respond | corresponds to this PID request | requirement steam amount to the steam header 6. The combustion amount of each boiler 20 is controlled so that the output steam amount thus supplied is supplied.

  The boiler 20 of this embodiment consists of a proportional control boiler comprised so that combustion amount can be increased / decreased continuously.

  The proportional control boiler can continuously increase or decrease the combustion amount at least in the range from the minimum combustion state (for example, the combustion state at 20% of the maximum combustion amount) to the maximum combustion state. The proportional control boiler can adjust the amount of combustion by controlling the opening degree (combustion ratio) of a valve that supplies fuel to the burner or a valve that supplies combustion air, for example.

  Next, the configuration of the boiler control device 3 will be described in detail. As shown in FIG. 1, the boiler control device 3 includes a control unit 4 as a control unit and a storage unit 5.

  The control unit 4 transmits various instructions to each boiler 20 via the signal line 16 and receives various data from each boiler 20 to control the combustion state and the number of operating units of the five boilers 20. Execute. When each boiler 20 receives a signal for changing the combustion state from the boiler control device 3, it controls the combustion amount of the corresponding boiler 20 in accordance with the instruction. The detailed configuration of the control unit 4 will be described later.

  The storage unit 5 stores information related to the instructions transmitted to each boiler 20, information related to the combustion state received from each boiler 20, information related to the priority order of each boiler 20, data necessary for calculating a PID required steam amount, which will be described later, and the like. Remember.

  Next, the configuration of the control unit 4 will be described in more detail. As shown in FIG. 1, the control unit 4 includes a steam amount calculation unit 41 and a unit number control unit 42.

  The steam amount calculation unit 41 calculates the PID required steam amount based on the target steam pressure value set in advance, the steam pressure value of the steam header 6 measured by the steam pressure sensor 7, and the like. Specifically, the steam amount calculation unit 41 sets the PID required steam amount to be described later so that the steam pressure value of the steam header 6 measured by the steam pressure sensor 7 becomes a preset target steam pressure value. Calculated by PID algorithm.

The steam amount calculation unit 41 calculates the PID required steam amount (PID control amount) based on the following equation (1).
PID required steam volume = Deviation proportional output (P control) + Deviation integral output (I control) + Deviation derivative output (D control) (1)

Moreover, each component which comprises PID request | requirement vapor | steam amount is calculated by following formula (2)-(4).
Deviation proportional output (PID_E) = PID_K × (target steam pressure value−current steam pressure value)
... (2)
Here, PID_K (proportional gain) is the boiler output (steam amount) per unit pressure deviation (1 kgf / cm ² or 1 MPa).

Deviation integral output (PID_EI) = PID_EI + PID_E / integration time (seconds)
... (3)
Deviation differential output (PID_ED) =
PID_K × (steam pressure value one second ago−current steam pressure value) × differentiation time (seconds)
... (4)

  The steam amount calculation unit 41 of the present embodiment calculates the PID required steam amount by summing up the outputs calculated by the above formulas (2) to (4).

  When the deviation proportional output (PID_E) calculated by the above equation (2) exceeds the maximum generated steam amount (maximum output) of this system, that is, the steam pressure value of the steam header 6 is proportional to the steam amount. At a point of time below the band (described later), the deviation integral output (PID_EI) is reset to zero (hereinafter also referred to as “zero deviation deviation output zero reset”).

The pressure proportional band in this embodiment is as follows.
Pressure proportional band = 9,000 kg / h (maximum total output for three vehicles) / 7,200 kg (kg / h) / (kg / cm ² )
= 1.25 kg / cm ²
Here, 7,200 kg (kg / h) / (kg / cm ² ) is a proportional gain in the present embodiment.

In a specific example of pressure control to be described later, the target steam pressure value is 8.0 kgf / cm ^2, and therefore 8.0−1.25 = 6.75 kg / cm ² is the lower limit value of the pressure proportional band. The steam amount calculation unit 41 performs zero reset of the deviation integral output when the steam pressure value of the steam header 6 falls below 6.75 kg / cm ² which is the lower limit value of the pressure proportional band.

  By performing zero reset of the deviation integral output in the steam amount calculation unit 41, the deviation integral output (PID_EI) is not included in the PID required steam amount calculated by the equation (1). Therefore, in the calculation of the PID required steam amount, it is possible to reduce the influence of an excessively accumulated positive deviation integral output (cumulative integral amount). A specific example of zero reset of the deviation integration output will be described later.

  The number control unit 42 performs so-called number control in which a required number of boilers 20 are combusted according to the steam consumption. Specifically, when the number of boilers 20 to be burned is increased due to an increase in steam consumption, the number control unit 42 starts combustion in order from the boiler 20 having a higher priority set in advance. Further, when the steam consumption is reduced and the number of boilers 20 to be burned is reduced, the number control unit 42 stops the combustion in order from the boiler 20 having a low priority set in advance.

  The number control unit 42 sets the number of boilers 20 to be burned based on the PID required steam amount calculated according to the steam consumption amount in the steam amount calculation unit 41. The number control unit 42 sets the boilers 20 that start or stop combustion according to the priority order described in the storage unit 5, and sends a number control signal (operation start or start) to the local control unit 22 of the boilers 20. Stop) is output. Thereby, the steam amount corresponding to the PID required steam amount (hereinafter also referred to as “output steam amount”) is supplied from the boiler 20 to be combusted to the steam header 6.

  Next, in the steam amount calculation unit 41 of the control unit 4, in addition to the comparative example when the pressure control is performed only by the normal PID algorithm and the pressure control by the normal PID algorithm, zero reset of the deviation integral output is executed. An embodiment in this case will be described.

  FIG. 2 is a graph showing the steam pressure and the amount of steam when pressure control is performed only with a normal PID algorithm using the boiler system 1 shown in FIG. 1 as a model. FIG. 3 is a graph showing the steam pressure and the steam amount when zero reset of the deviation integral output is executed in addition to the pressure control by the normal PID algorithm using the boiler system 1 shown in FIG. 1 as a model.

In this embodiment, the maximum number of combustion of the boiler group 2 is 3, the target steam pressure value is 8.0 kgf / cm ² , the proportional gain (PID_K) is 7,200 (kg / h) / (kg / cm ² ), The integration time was 10 seconds, the derivative time was 2 seconds, and the bias correction was 0 kg / h. Then, the steam consumption amount close to the maximum generated steam amount (maximum output) of this system continues until the elapsed time reaches about 1,300 to 1,400 seconds, and the steam consumption amount exceeds 1,400 seconds. A pattern that drops rapidly was set and a simulation calculation was performed. 2 and 3 show the results of the simulation calculation.

2 and 3, the horizontal axis indicates the elapsed time (seconds), the right vertical axis indicates the steam volume (t / h), and the left vertical axis indicates the steam pressure value (kg / cm ² ). 2 and 3, the thick solid line represents the steam pressure value of the steam header 6, the broken line represents the steam consumption, and the thin solid line represents the output steam supplied to the steam header 6. Note that the output steam amount indicates the total value of the steam amounts output from the three boilers 20 to be burned. Moreover, the simulation shown in FIG.2 and FIG.3 is started from the state which made the steam pressure value of the steam header 6 about 2.0 kg / cm < ² > (FIG. 4 of 2nd Embodiment mentioned later is also the same).

As shown in FIG. 2, the amount of output steam supplied from the boiler group 2 to the steam header 6 from the elapsed time 0 to about 1,300 seconds is 2 to 5 (t / h) depending on the steam consumption. ). During this time, since the steam consumption does not change rapidly, the output steam quantity corresponding to the calculated PID required steam quantity follows the fluctuation of the steam consumption. In addition, the steam pressure of the steam header 6 has almost converged to the target steam pressure value (8.0 kgf / cm ² ).

  On the other hand, the steam consumption close to the maximum generated steam amount (maximum output) of the boiler system 1 continues from the elapsed time 1,300 to approximately 1,400 seconds, and the steam consumption exceeds the elapsed time 1,400. There is a sharp decrease. Since the PID required steam amount calculated between this elapsed time 1,300 seconds and approximately 1,400 seconds is affected by the positive integral amount accumulated during this period, the elapsed time after 1,400 seconds is exceeded. Even if the steam consumption starts to decrease rapidly, the output steam amount supplied to the steam header 6 does not decrease immediately. The steam pressure value of the steam header 6 temporarily exceeds the target steam pressure value temporarily due to the influence of the positive integral amount.

  As described above, when the steam pressure value exceeds the target steam pressure value, accumulation of negative integral values proceeds in the correction process, so that the calculated PID required steam amount rapidly decreases. For this reason, in pressure control using only a normal PID algorithm, the return (increase) of the PID required steam amount is delayed due to the negative integral value, and the steam pressure value in the steam header 6 continues to drop. In addition, even after the PID required steam amount returns and rises, an excessive accumulation of negative integral values remains, resulting in a significant response delay. Therefore, in the comparative example shown in FIG. 2, a hunting phenomenon occurs in which the steam pressure value of the steam header 6 fluctuates up and down without converging to the target steam pressure value (see elapsed time after 1,440 seconds).

On the other hand, in the embodiment shown in FIG. 3, in the steam amount calculation unit 41, when the deviation proportional output (PID_E) exceeds the maximum generated steam amount of the boiler system 1, that is, the steam pressure value of the steam header 6 is the lower limit of the pressure proportional band. When the value falls below 6.75 kg / cm ² , zero deviation resetting of the deviation integration output is executed. Specifically, in FIG. 3, immediately after the steam pressure value decreases after 1,440 seconds, zero reset of the deviation integral output is not executed. However, after the elapsed time of 1,500 seconds, when the steam pressure value of the steam header 6 falls below 6.75 kg / cm ² , which is the lower limit value of the pressure proportional band, zero reset of the deviation integral output is executed at that time. Is done.

  As a result, the calculated integral PID steam amount does not include the deviation integral output (PID_EI). Therefore, as shown in FIG. 3, after 1,530 seconds, the output steam amount corresponding to the calculated PID required steam amount does not overshoot and quickly follows the fluctuation of the steam consumption (required load). To come. Further, the steam pressure value of the steam header 6 also converges near the target steam pressure value.

Further, the simulation results shown in FIG. 2, the hunting phenomenon, the vapor pressure value of the steam header 6, the maximum 9.28kg / cm ^2, the minimum 0.67 kg / cm ^2, and the fluctuation range thereof is 8.61kg / cm ² Met. In contrast, in the simulation results shown in FIG. 3, the vapor pressure value of the steam header 6, the maximum 9.10 kg / cm ^2, minimum 2.78kg / cm ^2, and the fluctuation range thereof and 6.32kg / cm ² became. Thus, in addition to the pressure control by the normal PID algorithm, when the zero reset of the deviation integral output is executed, the pressure fluctuation of the steam header 6 is less than that in the case of only the pressure control by the normal PID algorithm. Therefore, the steam pressure value can be kept stable.

  According to the boiler system 1 according to the first embodiment described above, when the deviation proportional output exceeds the maximum generated steam amount of the boiler system 1, that is, when the steam pressure value of the steam header 6 falls below the pressure proportional band, Deviation integral output zero reset is executed. According to this, when the steam consumption (required load) close to the maximum generated steam amount of the boiler system 1 continues, and when the steam consumption suddenly decreases, the excessive positive and negative integral amounts The influence can be eliminated. Therefore, the hunting phenomenon in which the steam pressure value of the steam header 6 fluctuates up and down without converging to the target steam pressure value is suppressed, and the steam pressure value can be quickly converged to the target steam pressure value.

  Next, a second embodiment of the boiler system according to the present invention will be described mainly with reference to FIG. FIG. 4 shows the steam pressure and the amount of steam when the deviation integral output zero reset and the deviation integral output high cut are executed in addition to the pressure control by the normal PID algorithm using the boiler system 1A shown in FIG. 1 as a model. It is a graph to show.

  In the second embodiment, the same components as those in the first embodiment will be described with the same reference numerals. The basic configuration of the boiler system 1A according to the present embodiment is the same as that shown in FIG. Here, differences from the first embodiment will be described.

  The boiler system 1A according to the present embodiment is different from the first embodiment in that the steam amount calculation unit 41A (see FIG. 1) executes a high cut of a deviation integration output described later.

  In addition to the above-described zero reset of the deviation integral output, the steam amount calculation unit 41A of the present embodiment uses the deviation integral output (PID_EI) calculated by the above equation (3) as the maximum generated steam amount (maximum) of the boiler system 1A. Output) is controlled so that it does not exceed the output. That is, the maximum generated steam amount is set to the maximum value of the deviation integral output (PID_EI), and the integral amount beyond that is cut (hereinafter also referred to as “high cut of the deviation integral output”).

  In general, the maximum amount of steam generated in the boiler system is a physical upper limit value of the boiler group, and therefore, even if an excessive PID required steam amount is calculated, it does not lead to appropriate control of the steam pressure value. Further, the increase in the positive integral value delays the subsequent decrease in the output steam amount. Therefore, further optimization of the PID required steam amount can be achieved by preventing the deviation integrated output from exceeding the maximum generated steam amount of the boiler system 1A.

  Next, simulation results when the deviation integral output zero reset and the deviation integral output high cut are executed will be described with reference to FIG. Note that the simulation conditions in this embodiment are the same as those in the first embodiment.

  In FIG. 4, the steam consumption close to the maximum generated steam amount (maximum output) of the boiler system 1 continues from the elapsed time 1,300 to approximately 1,400 seconds, and the steam consumption exceeds the elapsed time 1,400. A sudden decrease in volume has occurred. In the first embodiment, the steam pressure value of the steam header 6 is temporarily significantly higher than the target steam pressure value when the steam consumption starts to suddenly decrease after the elapsed time of 1,400 seconds. (See FIG. 3). This is because the PID required evaporation amount is excessively calculated due to the influence of the positive integration amount accumulated so far. In this way, if the PID required evaporation amount is calculated to be excessive, the steam consumption of the steam header 6 will be calculated since the PID required evaporation amount is calculated to be excessively reduced when the steam consumption subsequently starts to decrease rapidly. The pressure value will continue to drop. Therefore, it becomes impossible to follow the fluctuation of the steam consumption (required load).

  On the other hand, in the present embodiment, the deviation integral output (PID_EI) does not exceed the maximum generated steam amount (maximum output) of the boiler system 1A, so that the steam consumption rapidly increases after the elapsed time of 1,400 seconds. Therefore, the steam pressure value of the steam header 6 does not exceed the target steam pressure value. Therefore, the PID required evaporation amount is not calculated too small when the steam consumption starts to decrease sharply after the elapsed time of 1,400 seconds. Therefore, as shown in FIG. 4, the steam pressure value of the steam header 6 does not continue to drop, and it is possible to promptly follow fluctuations in steam consumption (required load). Further, the steam pressure value of the steam header 6 does not vary greatly as in the first embodiment (FIG. 3) between the elapsed time 1,440 seconds and 1,530 seconds, and is almost equal to the target steam pressure value. Converge near.

Further, in the simulation result shown in FIG. 4, the vapor pressure value of the steam header 6, the maximum 8.28kg / cm ^2, minimum 7.76kg / cm ^2, and the fluctuation range thereof became 0.52 kg / cm ^2. In this way, in addition to the pressure control by the normal PID algorithm, when the deviation integral output zero reset and the deviation integral output high cut are executed, the pressure control by the normal PID algorithm and the deviation integral output zero reset are performed. Compared with the combination, the pressure fluctuation of the steam header 6 becomes smaller, so that the steam pressure value can be kept more stable.

  According to the boiler system 1A according to the second embodiment described above, in addition to the zero reset of the deviation integral output, the deviation integral output so that the deviation integral output does not exceed the maximum amount of steam generated (maximum output) of the boiler system 1A. High cut is executed. According to this, when the steam consumption (required load) close to the maximum generated steam amount of the boiler system 1A continues and then the steam consumption suddenly starts to decrease, the excessive positive accumulated until then is increased. Therefore, the negative integral value is excessively accumulated in the correction process, so that the required PID required steam amount is not calculated excessively. Therefore, when the steam consumption starts to decrease rapidly, the steam pressure value of the steam header 6 does not continue to drop, so the steam pressure value can be targeted more quickly with respect to the sudden increase / decrease in the steam consumption. The vapor pressure value can be converged.

  Next, 3rd Embodiment of the boiler system which concerns on this invention is described with reference to FIGS. FIG. 5 is a graph showing the steam pressure and the steam amount when the pressure control is performed only with the normal PID algorithm from the state where the steam pressure of the steam header 6 is zero using the boiler system 1 shown in FIG. 1 as a model. FIG. 6 shows the steam pressure when the reset of the deviation integral output is executed in addition to the pressure control by the normal PID algorithm from the state where the steam pressure of the steam header 6 is zero, using the boiler system 1 shown in FIG. 1 as a model. It is a graph which shows vapor amount. FIG. 7 uses the boiler system 1 shown in FIG. 1 as a model to perform zero reset of the deviation integral output and high cut of the deviation integral output in addition to the pressure control by the normal PID algorithm from the state where the steam pressure of the steam header 6 is zero. It is a graph which shows the vapor | steam pressure and the vapor | steam amount in the case of doing.

  Since the structure of the boiler system 1 which concerns on 3rd Embodiment is the same as 1st Embodiment, description of each part which comprises a system is abbreviate | omitted. Here, differences from the first embodiment will be described.

This embodiment is different from the first embodiment in that the operation is started from the steam pressure value of the steam header 6 from 0 kg / cm ² . The simulation conditions in this embodiment are the same as those in the first embodiment.

As shown in FIG. 5, when the operation is started from a state where the steam pressure value of the steam header 6 is 0 kg / cm ² (for example, at the time of starting the system), the operation is started by pressure control using only a normal PID algorithm. For a while, the deviation between the target steam pressure value of 8.0 kgf / cm ² and the current steam pressure value of the steam header 6 is accumulated as a positive integral amount. Therefore, even when the current steam pressure value reaches the target steam pressure value, an excessive PID required steam amount is calculated until the deviation integral output decreases to an appropriate value due to the influence of the accumulated positive integral amount, The increase in the steam pressure value in the steam header 6 continues. Then, if the steam pressure value rises excessively, accumulation of negative integral values proceeds this time in the correction process, so that a rapid decrease in the calculated PID required steam amount occurs. As a result, as shown in FIG. 5, a hunting phenomenon in which the steam pressure value of the steam header 6 fluctuates up and down without converging to the target steam pressure value occurs.

On the other hand, in the embodiment shown in FIG. 6 (in combination with zero reset of the deviation integral output), the operation is started from a state where the steam pressure value of the steam header 6 is 0 kg / cm ² (hereinafter referred to as “zero pressure start”). When the deviation proportional output exceeds the maximum generated steam amount of the boiler system 1, that is, in the range where the steam pressure value of the steam header 6 is below the lower limit value 6.75 kg / cm ² of the pressure proportional band. The integral output is reset to zero. In other words, the integral value is not accumulated until the steam pressure value of the steam header 6 exceeds 6.75 kg / cm ^2, and accumulation of the integral value starts after exceeding the lower limit value 6.75 kg / cm ² of the pressure proportional band. According to this, since the positive integrated value is not accumulated until the steam pressure value of the steam header 6 exceeds 6.75 kg / cm ² after the operation is started, the current steam pressure value is the target steam pressure value. When the pressure reaches the value, an excessive PID required steam amount is not calculated. Therefore, the hunting phenomenon as shown in FIG. 6 is suppressed, and the steam pressure value can be quickly converged to the target steam pressure value.

In the simulation result shown in FIG. 6, the hunting phenomenon, the vapor pressure value of the steam header 6, the maximum 9.36kg / cm ^2, the minimum 0.66 kg / cm ^2, and the fluctuation range thereof is 8.70kg / cm ² Met. In contrast, in the simulation result shown in FIG. 6, the vapor pressure value of the steam header 6, the maximum 8.52kg / cm ^2, minimum 7.77kg / cm ^2, and the fluctuation range thereof is a 0.75 kg / cm ² became. As described above, in addition to the pressure control by the normal PID algorithm, when the zero reset of the deviation integral output is executed, in the case of only the pressure control by the normal PID algorithm from the state where the steam pressure of the steam header 6 is zero. In comparison, since the pressure fluctuation of the steam header 6 is reduced, the steam pressure value can be kept stable.

  Further, when the deviation integrated output high cut described in the second embodiment is executed at the zero pressure start shown in FIG. 6, the steam consumption rapidly increases after the elapsed time 1,400, as shown in FIG. 7. When it starts to decrease, it is possible to prevent the PID required evaporation amount from being excessively calculated. Therefore, the steam pressure value of the steam header 6 does not continue to drop, and it is possible to promptly follow fluctuations in steam consumption (required load).

  Therefore, in the boiler system 1 according to the first embodiment described above, the steam pressure value of the steam header 6 fluctuates up and down without converging to the target steam pressure value even in the case of the zero pressure start shown in the third embodiment. The hunting phenomenon is suppressed, and the steam pressure value can be quickly converged to the target steam pressure value.

  As mentioned above, although preferable embodiment of the boiler system which concerns on this invention was described, this invention is not restrict | limited to each embodiment mentioned above, It can change suitably.

  For example, the target steam pressure value (target thermal energy output value) may be set to be equal to or lower than the maximum upper limit pressure value (maximum upper limit thermal energy output value) that can be operated in the boiler. Generally, when the target steam pressure value is near the maximum upper limit pressure value of the boiler, the behavior may become unstable when the steam pressure value of the boiler temporarily exceeds the target steam pressure value. Therefore, when the target steam pressure value is set to, for example, about 90% to 85% of the maximum upper limit pressure value, the steam pressure value of the boiler does not carelessly exceed the target steam pressure value, so the boiler is more stable. It is possible to drive in the state.

  Moreover, in each embodiment, the example which applied this invention to the boiler system provided with the boiler group 2 which consists of the five boilers 20 was demonstrated. However, the present invention is not limited to this, and the present invention may be applied to a boiler system including a boiler group including six or more boilers, or may be applied to a boiler system including a boiler group including two to four boilers. Also good. Moreover, in each embodiment, the example which sets the number of the boilers 20 burned based on the PID request | requirement steam volume calculated according to the steam consumption and the preset priority order was demonstrated as number control. However, the number of boilers to be burned in a boiler group including a plurality of boilers may be set based on, for example, the load factor of the system or the operating status of each boiler. Moreover, although each embodiment demonstrated the example which combined the pressure control by this invention and the number control of a boiler, you may apply the pressure control by this invention to the pressure control of a single boiler. In that case, the PID required steam amount calculated by the PID algorithm is set as it is as the PID required steam amount in a single boiler.

  In each embodiment, an example in which the steam amount calculation unit 41 (41A) calculates the PID required steam amount by a PID (proportional + integral + derivative) algorithm based on the steam pressure value (physical quantity) of the steam header 6 will be described. did. However, the present invention is not limited to this, and can also be applied to control for calculating the PID required steam amount by the PI (proportional + integral) algorithm.

  Moreover, although each embodiment demonstrated the example using the steam boiler as the boiler 20, it is not restricted to this, The boiler 20 may be a hot water boiler. In that case, the control part 4 calculates a PID request | requirement temperature value by a PID algorithm based on the temperature value of the warm water generated with each boiler. In the present embodiment, the maximum output of the boiler group 2 is described as “maximum generated steam amount”, but the maximum output is, for example, “rated output”, “equivalent evaporation amount”, “actual evaporation amount”, or the like. Sometimes expressed in terms of. In the case of steam boilers and hot water boilers, they may be collectively referred to as “heat output”.

DESCRIPTION OF SYMBOLS 1,1A Boiler system 2 Boiler group 3 Boiler control apparatus 4 Control part 5 Memory | storage part 6 Steam header 7 Steam pressure sensor 18 Steam use equipment 20 Boiler 41, 41A Steam volume calculation part (control means)
42 Number control unit

Claims (4)

A boiler that generates thermal energy according to the amount of fuel burned;
A combustion amount of the boiler based on a control amount calculated by a PI algorithm or a PID algorithm so that a heat energy output value that is an output value of the heat energy generated in the boiler becomes a preset target heat energy output value Control means for controlling
With
The control means resets the deviation integral output value calculated by the PI algorithm or PID algorithm to zero when the deviation proportional output value calculated by the PI algorithm or PID algorithm exceeds the maximum output of the boiler. Boiler system. The boiler system according to claim 1, wherein the control means prevents the deviation integrated output value from exceeding a maximum output of the boiler. The boiler system according to claim 1, wherein the boiler includes a plurality of boiler bodies capable of continuously increasing or decreasing a combustion amount. The boiler system according to any one of claims 1 to 3, wherein the target thermal energy output value is set to be equal to or less than a maximum upper limit thermal energy output value at which the boiler can be operated.

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