JP5045914B2 - Boiler unit controller - Google Patents

Description

  The present invention relates to a boiler number control device, and more particularly to a boiler number control device in a multi-can installation system for burning a plurality of boilers according to a required load.

  As a boiler that can supply steam efficiently, a multi-can installation system that generates steam using a plurality of boilers is well known.

  In other words, a steam detector connected to a steam supply pipe that supplies steam generated in each boiler is provided with a pressure detector to grasp the state of the load. In order to follow the changing load, each boiler is shifted to combustion in accordance with the priority order set in advance, and if there is a load change, each boiler is burned or stopped according to this load change. (See Patent Document 1).

  On the other hand, each boiler is provided with a local control device that suppresses the maintenance and change of the state of each boiler. The local control device receives a signal from the number control device and controls each boiler. The combustion stage of each boiler (in the case of three-position control, each stage of standby, low fuel consumption, and high fuel combustion) is notified.

  FIG. 6 is a block diagram showing the processing of the number control device. The combustion amount calculation means 202 receives the output of the pressure detection device and a set value as a control target, and the required combustion amount is calculated from both values.

  The required combustion amount is a combustion amount corresponding to the steam header pressure. In the case of three-position control having stages of standby, low combustion, and high combustion, if the combustion amount for one boiler in a high combustion state is 1, In a boiler in which the amount of combustion at the time of high combustion is twice the amount of combustion at the time of low fuel, the difference in the amount of combustion between standby and low fuel or between low and high fuel can be expressed as 0.5. Therefore, if the required combustion amount is 1, there may be one high-burning boiler or two low-burning boilers. If the required combustion amount is 1.5, there may be one high-burning boiler and one low-burning boiler or three low-burning boilers.

  The boiler determination means 203 determines the combustion stage of each boiler from the required combustion amount and the priority given to each boiler. Here, the relationship between the priority order and each boiler has a predetermined pattern unique to the system and is not necessarily common. That is, let us consider a case where three boilers are controlled by setting standby as-, low fuel as L, and high fuel as H. When the required amount of combustion increases, the patterns "---", "L--", "LL-", "LLL", "HLL", "HHH", "---", "L--" There are patterns such as “H−−”, “HL−”, “HH−”, and “HHH”. The boiler determining means 203 determines the combustion stage of each boiler according to this pattern.

  The contents determined by the boiler determination means 203 are instructed to each boiler by the instruction means 204 and stored in the previous instruction table 207 as the previous instruction. Here, the previous instruction includes a combustion instruction and a standby instruction, and the combustion instruction further includes a high fuel instruction and a low fuel instruction in the case of the three-position control.

  The previous instruction table 207 is also written with the actual combustion stage of each boiler detected by the combustion stage detection means 201, and by comparing this with the previous instruction, the boiler determination means. Whether or not the instruction from 203 has been executed can be confirmed.

  By the way, at the time of maintenance and inspection of the system, one or a plurality of boilers to be inspected are paused, and the local controller of the paused boiler is excluded from the control targets of the unit controller. . Alternatively, the connection between the local control device and the number control device may be partially or completely disconnected for some reason and may be out of control of the number control device. In this way, a boiler that is not controlled by the number control device is independently controlled by the local control device.

  In this way, when all the boilers or some of the boilers are operating independently from the control of the number control device (self-combustion state), the number control device is restored. Will start each boiler according to the priority of each boiler and resume operation.

Note that the local control device is actually installed at the position of each boiler, or is incorporated in the number control device.
JP 2003-130303 A

  As described above, when the boiler that has been removed from the number control target is restored to the control target of the number control device and the operation according to the priority order is resumed, the following problems occur.

  FIG. 7 is a flowchart showing a procedure of conventional recovery processing. The figure shows the transition between the previous instruction and the actual combustion stage stored in the previous instruction table 207 in the unit control device immediately after recovery to the control target.

  In the figure, the numbers in the circles indicate the priority given to each boiler. Furthermore, the upper part of the rectangular frame which is a storage area corresponding to each boiler is the previous instruction column 207a in which the previous instruction (determination content of the boiler determining means 203) is written, and the lower part is the actual combustion stage (combustion stage detection). This represents the combustion stage column 207b in which the detection content of the means 201 is written. Here, as shown in FIG. 7 (a), the number of boilers is 5, and the priority order is 5, 3, 4, 2, 1 (the lower the numerical value, the higher the priority order) in the order of Units 1-5. Each boiler can be switched to three combustion stages of standby, low fuel, and high fuel, and the transition from standby to high fuel always goes through the low fuel combustion stage.

  If high combustion is 100%, the low combustion is 50%. In addition, it is assumed that Unit 1 and Unit 4 are currently operating at a low combustion stage, and Unit 3 is operating at a high combustion stage with a combustion amount of 2 (low combustion × 2 + high combustion = combustion amount 2). In addition, the boiler that is out of the control of the number control device detects that by the local control device and starts self-combustion, and the number control device displays “self-combustion” in the previous instruction column 207a in the upper stage of the previous instruction table 207. The writing and lower combustion stage column 207b is reset.

  Then, as shown in FIG. 7A, when the control of the number control device is restored, first, the combustion stage detection means 201 detects the combustion stage of each boiler, and enters the combustion stage column 207b of the previous instruction table 207. Write the detected content. Next, the combustion amount calculation means 202 calculates the required combustion amount based on the set value and the pressure from the pressure detection device. Next, according to the priority given to each boiler, the required amount of combustion, and the like, a combustion instruction (low fuel instruction, high fuel instruction) or standby instruction is issued to each local control device.

  Considering the case where the required combustion amount at the time of recovery is 3 (combustion amount for three high-burning boilers), the following is considered.

  As shown in FIG. 7 (b), high priority is given to Unit 5, Unit 4, Unit 2 from the priority order, Unit 3 was in the high combustion stage, and Unit 1 was in the low combustion stage. Is instructed to wait. Therefore, the No. 1 and No. 3 units that have been in combustion until now shift to the standby stage. Unit 5 and Unit 2 that have been instructed as described above will generate the steam pressure required by the unit control device together with Unit 4 when time elapses. Until then, only Unit 4 is temporarily in operation, and a drop in vapor pressure is inevitable.

  Next, the case where the required amount of combustion at the time of recovery is 1 is as follows.

  As shown in FIG. 7 (c), the high priority is given to Unit 5 from the priority order, and the Unit 3 that was in the high combustion stage, Unit 1 and Unit 4 that were in the low combustion stage are on standby. Instructions are given. Therefore, the No. 1, No. 3, No. 4 and No. 4 units that have been in combustion are shifted to a standby stage. As described above, the No. 5 machine in which the high combustion instruction is issued will generate the vapor pressure required by the unit control device over time, but from the high combustion instruction to the normal operation state. During this period, the vapor pressure required by the unit control device cannot be obtained. Therefore, a temporary drop in vapor pressure is inevitable.

  Next, FIG. 8 is a flowchart showing a recovery procedure when only the first unit having the lowest priority is out of control of the number control device, which is a phenomenon often seen during maintenance inspection.

  As shown in FIG. 8I, Units 2 to 5 are operating normally under the control of the number control device, but Unit 1 is out of control of the number control device and operated under the control of the local control device. It is assumed that

  Here, the combustion amount calculation means 202 of the number control device is configured so that the pressure of the steam header 4 is positioned within a predetermined control range where the set value is the upper limit P2 and the lower pressure is the lower limit P1. Is controlling the combustion. That is, as shown in FIG. 9, when the header pressure is close to the lower limit value P1, all the boilers need to burn, but when the header pressure approaches the upper limit P2, no further combustion amount is necessary (the number of burned units is zero).

Assuming that Unit 1 has been restored from being controlled by the unit control device to being controlled, and the required combustion amount has changed from 2.0 to 2.5 due to fluctuations in the required load, the number of units as shown in FIG. 8II (a) The control device issues a low-burning instruction to Unit 2, which has the highest priority after Units 4 and 5, and issues a standby instruction to Unit 1, which has been under the control of the local control device until then. As a result, as shown in FIG. 8II (b), Unit 1 shifts from the high combustion stage to the standby stage, and Unit 2 enters the low combustion stage through the purge state.

  As a result, when a predetermined time elapses, the necessary combustion amount for 2.5 vehicles required by the unit control device can be secured. However, since Unit 1 shifts to the standby stage, Until the steam of the required pressure can be supplied, only the combustion amount for two vehicles can be secured.

  The present invention has been proposed in view of the above-described conventional circumstances, and is a unit control device capable of obtaining a target vapor pressure with little pressure fluctuation even when the control by the unit control device is restored. The purpose is to provide.

  The present invention employs the following means in order to achieve the object.

  The present invention is premised on a boiler number control device for a multi-can installation system that includes a plurality of boilers having a plurality of combustion stages including a standby stage, and instructs the change of the combustion stages in response to a load request.

  In the boiler number control device, when a boiler that is not subject to number control is restored to control by the number control device, the restoration processing means notifies the boiler determining means of the state of each boiler at the time of restoration as it is as a previous instruction. And the boiler determination means determines the boiler which changes a combustion stage based on the combustion stage of all the boilers, and the required combustion amount corresponding to a priority and a required load.

  In the above configuration, when the boiler not subject to unit control is restored to the control by the unit control device, the boiler determining means burns the previous combustion instruction boiler preferentially over the previous standby instruction boiler among the previous instruction boilers. Decide on the boiler to change the stage. That is, when the combustion amount of the previous combustion instruction boiler is more than the required combustion amount, the boilers with lower combustion stages are used in order from the boiler with the lowest priority among the previous combustion instruction boilers.

  Further, for a boiler that is purged when a boiler that is not subject to unit control is restored to control by the unit control device, the recovery processing means is the previous combustion instruction boiler. When the combustion amount of the previous combustion instruction boiler is less than the required combustion amount, the boiler in the purge state is preferentially set as the combustion instruction boiler, and the combustion amount of the previous combustion instruction boiler is greater than the required combustion amount. When excessive, the boiler in the purge state is preferentially used as a standby instruction boiler.

  When the above process is completed, as the next process, the boiler determining means sequentially repeats determining a boiler whose combustion stage is changed based on the priority order of all the boilers.

  With the above-described configuration, the subsequent combustion control can be performed based on the combustion stage of each boiler when the number control is restored, so that there is an effect that the variation in the steam pressure is reduced. Further, by determining the combustion stage at the time of recovery in consideration of the purge state, the purge process is not wasted.

  FIG. 1 shows an example of a combustion system to which the present invention is applied. As shown in FIG. 1, a steam pipe 6 from each boiler 1 is connected to a steam header 4, and the steam header 4 is provided with a pressure detection device 3 that detects the pressure of the steam header 4. Further, each boiler 1 is provided with a local control device 5 that controls each boiler 1, and each local control device 5 is connected to the number control device 2.

  FIG. 2 shows a more detailed functional block diagram of the number control device. Each function described below may be configured such that a CPU and a program stored in a ROM or the like operate in cooperation, or may be configured by hardware.

  As in the prior art, the output of the pressure detection device 3 is input to the combustion amount calculation means 202, and a set value (set pressure value) as a control target is input from the set value table 205, and from these two values Obtain the required amount of combustion. Next, the required combustion amount obtained in this way, the priority given to each boiler, and the previous instruction content for each boiler are input to the boiler determining means 203, whereby the boiler determining means 203 determines the combustion stage of each boiler. In response to this determination, the instruction means 204 issues a combustion instruction (low fuel instruction, high fuel instruction) and standby instruction to each boiler. The priority order is stored in the priority order table 206, and the instructions given to the boilers issued by the instruction means 204 are stored in the previous instruction table 207 as previous instructions.

  In this configuration, during normal times (when all boilers are under the control of the number control device 2), when the required load increases and the steam pressure value decreases, the combustion stage is raised in order from the boiler with the highest priority, and the required load is reduced. When the steam pressure value decreases and the steam pressure value increases, the number of units corresponding to the required combustion amount is controlled by lowering the combustion stage in order from the boiler with the lowest priority.

  An integrated value of the combustion time is calculated for each boiler, and the priority order is changed so that the operation priority order becomes higher as the combustion time is shorter. This can prevent the specific boiler from being excessively consumed. Further, in this example, each boiler 1 takes three combustion stages of standby, low combustion, and high combustion, and cannot suddenly shift from the standby stage to the high combustion stage. It is supposed to shift to the stage.

(Embodiment 1)
In the above configuration, communication may not be possible between the local control device 5 and the number control device 2 for some reason. At this time, naturally, some or all of the local control devices 5 of the boilers 1 cannot be controlled by the number control device 2, but in FIG. 2, all the boilers 1 are out of control from the number control device 2. It is assumed to be described.

  Thus, when all the boilers are out of the unit control, each boiler 1 is independently controlled by the local control device 5 at a pressure between the upper and lower limits set in the local control device 5. The previous instruction stored in the previous instruction table 207 is “self-combustion” when all the boilers 1 are out of control by the number control device 2, and the combustion stage is “reset”. When the boiler determining means 203 is operated in this state, as described above, a temporary fluctuation occurs in the generated steam pressure. Therefore, in the present invention, the recovery processing means 208 is added to the unit control device 2 in addition to the above configuration. It is provided and the combustion of the boiler 1 is controlled by the following procedure.

  First, as in the prior art, the combustion stage detection means 201 detects the combustion stage of each boiler including the self-combustion boiler at the time of restoration when the control by the number control device 2 is restored. Next, the recovery processing means 208 writes the combustion stage at the time of recovery detected by the combustion stage detection means 201 as a previous instruction in the previous instruction table 207. Thereby, the boiler determination means 203 can obtain the previous instruction content.

  Therefore, the boiler determination means 203 determines the combustion stage of each boiler according to the following criteria in accordance with the required combustion amount (required load) determined by the combustion amount calculation means 202 together with the combustion stages of all the boilers and the priority order of all the boilers. Then, the instruction means 204 instructs each boiler to that effect, and writes this in the previous instruction table 207 as the previous instruction.

  The boiler determination criteria in the boiler determination means 203 are as follows.

  Determination criteria (1): The previous combustion instruction boiler is determined to be a boiler that changes the combustion stage preferentially over the previous standby instruction boiler.

  Determination criterion (2): When the combustion amount of the previous combustion instruction boiler is less than the required combustion amount and the previous combustion instruction boiler has a margin for raising the combustion amount, the combustion stage according to the priority order of the previous combustion instruction boiler Decide on a lifting boiler.

  Determination criterion (3): When the combustion amount of the previous combustion instruction boiler is less than the required combustion amount and the previous combustion instruction boiler has no room for raising the combustion amount, the combustion stage is increased in accordance with the priority order of the previous standby instruction boiler Decide the boiler.

  Determination criterion (4): When the combustion amount of the previous combustion instruction boiler is more than the required combustion amount, the combustion amount reduction boilers are determined in order from the boiler with the lowest priority among the previous combustion instruction boilers.

  Determination criteria (5): In the boiler determination process from the second time after the control by the number control means is restored, the boilers that change the combustion stage are determined based on the priority order of all the boilers.

  Further details will be described below with reference to specific examples.

  FIG. 3 is a flowchart showing the procedure of the recovery process according to the present invention. As in the case shown in FIG. 7, the transition between the previous instruction and the actual combustion stage stored in the previous instruction table 207 in the number control device 2 immediately after the non-controlled boiler is restored to the control target is shown. .

  As shown in FIG. 3A, the number of boilers is 5, and the priorities are in the order of 5, 3, 4, 2, 1 (the lower the numerical value, the higher the priority) in the order of Units 1-5. The upper part in the frame, which is a storage area corresponding to each boiler of the previous instruction table 207, is the previous instruction field 207a for storing the previous instruction, and the lower part is the combustion stage field 207b for storing the combustion stage.

  As described above, since the unit control device 2 and each local control device are not connected, each boiler 1 is controlled by the local control device 5, and at present, the first unit and the fourth unit are in the low combustion stage, 3 Unit No. 2 is in the high combustion stage, Unit No. 2 and Unit No. 5 are in the standby stage. Here, the case where the required combustion amount calculated by the combustion amount calculation means 202 is 3 is considered as follows.

  As shown in FIG. 3A, when the control by the number control device 2 is restored, as described above, the combustion stage detecting means 201 detects the combustion stage of each boiler at the time of restoration, and the combustion stage of the previous instruction table 207 is detected. Write in column 207b. Here, as described above, Unit 1 and Unit 4 are in the low combustion stage, Unit 3 is in the high combustion stage, and Units 2 and 5 are in the standby stage. Next, as shown in FIG. 3 (b1), the restoration processing means 208 writes the combustion stage as it is in the previous instruction into the previous instruction column 207a of the previous instruction table 207.

  The boiler determining means 203 refers to the combustion stages of all the boilers, the priorities of all the boilers, and the required combustion amount, and, as shown in FIG. 3 (c1), raises to the combustion stage in the previous combustion instruction boiler. Boilers with margins are extracted in descending order of priority, and here we decided to raise Units 4 and 1 from the current low-fuel stage to the high-fuel stage (see Decision Criteria (1) and (2)) Means 204 issues this instruction to each boiler. After confirming that Unit 4 having a high priority has shifted to high combustion, the instructing means 204 issues an instruction to raise Unit 1 from the current low-fuel stage to the high-fuel stage.

  When No. 1 and No. 4 shift to the high combustion stage based on the above instruction, the combustion amount of 3 is secured with respect to the required combustion amount of 3.

  Thereafter, when there is a request to increase the required combustion amount, the combustion stage raising boiler is determined according to the priority given to all the boilers for the increase (see determination criterion (5)). That is, when the required combustion amount becomes 3.5, a low combustion instruction is issued to Unit 5 having the highest priority with respect to the increase required combustion amount 0.5, and the required combustion amount of 3.5 is transferred to the low combustion stage. To meet.

  If there is a request for further increase in the required combustion amount 4.0 (increase required combustion amount 0.5) from this combustion stage, Unit 5 having a higher priority shifts to higher combustion.

  If the required amount of combustion decreases from this combustion stage, the first unit with the lowest priority among the boilers in the combustion state (whether or not the first unit is the previous combustion instruction boiler is not questioned) ) Transitions to the standby stage, and the boiler 1 that sequentially burns transitions, and normally shifts to normal control according to the priority order and the required amount of combustion (see decision criterion (5)).

  Next, considering the case where the required combustion amount calculated by the combustion amount calculating means 202 is 1, the following is considered.

  As in the above example, when the control by the number control device 2 is restored, the combustion stage detection means 201 of the number control device detects the combustion stage at the time of restoration and writes it in the combustion stage column 207b of the previous instruction table 207. Here, as shown in FIG. 3 (a), Unit 1 and Unit 4 are in the low combustion stage, Unit 3 is in the high combustion stage, Unit 2 and Unit 5 are in the standby stage.

  Next, the recovery processing means 208 replaces the combustion stage with the previous instruction and writes it in the previous instruction column 207a of the previous instruction table 207 as shown in FIG. 3 (b2). As a result, the boiler determining means 203 that has received the previous instruction refers to the previous combustion instruction boiler, the priority of the previous combustion instruction boiler, and the required combustion amount, and changes the combustion stage as follows. And the instruction means 204 issues an instruction of the changed content.

  That is, as shown in FIG. 3 (c2), the first combustion unit boiler having the lowest priority in the previous combustion instruction boiler is determined to be the standby boiler, and the next lower priority unit 3 is changed from the current high combustion stage to the low combustion. Decide the boiler to be lowered to the stage (see Decision Criteria (1) and (4)). The instructing unit 207 instructs each boiler on this determination content. As a result, when Unit 1 stands by and Unit 3 enters the low combustion stage, the total combustion amount becomes 1 (low combustion of Unit 3 + low combustion of Unit 4).

  After this, when the required load increases, Unit 5 with the highest priority shifts to low or high combustion, and if the required amount of combustion decreases from this combustion stage, The unit 3 with the lowest priority will be shifted to the steady state in the order of shifting to standby (see decision criterion (5)).

(Embodiment 2)
FIG. 4 is a flow diagram illustrating another embodiment of the present invention. As in the case shown in FIG. 3, the transition between the previous instruction and the actual combustion stage stored in the previous instruction table 207 in the number control device 2 immediately after recovery to the control target is shown.

  As shown in FIG. 4 (a), the number of boilers is 5, and the priority order is 5, 3, 4, 2, 1 in the order of Units 1-5. Further, as described above, when the state in which each local control device 5 is out of the control of the number control device 2 occurs, each boiler 1 is controlled based on the control of the local control device 5. Units 4 and 4 are in the low combustion stage, Unit 3 is in the high combustion stage, Unit 2 is in the standby stage, and Unit 5 is in the purge state.

  As shown in FIG. 4A, when the state in which the local control device 5 is under the control of the number control device 2 is restored, as described above, the combustion stage detection means 201 determines the combustion stage of each boiler at the time of restoration. Detected and written in the combustion stage field 207b of the previous instruction table 207.

  Next, the restoration processing means 208 writes each combustion stage as it is in the previous instruction column 207a as the previous instruction, and writes low fuel as the previous instruction for the purged boiler, as in the above embodiment. Next, the boiler determination means 205 determines a boiler whose combustion stage is changed according to the following criteria.

  Determination Criteria (6) When the combustion amount of the previous combustion instruction boiler is less than the required combustion amount (when there is an increase request), the boiler in the purged state is burned at the lowest combustion stage in the combustion instruction Use an instruction boiler.

  Determination Criteria (7) When the combustion amount of the previous combustion instruction boiler exceeds the required combustion amount (when there is a request for reduction), the boiler that has been in the purge state is preferentially used as a standby instruction boiler.

  Here, the case where the required combustion amount calculated by the combustion amount calculation means 202 is 3 is considered as follows.

  When the control by the number control device 2 is restored, the combustion stage detection means 201 of the number control device 2 detects the combustion stage of each boiler 1 at the time of restoration, and writes this combustion stage in the combustion stage column 207b of the previous instruction table 207. Here, as described above, Unit 1 and Unit 4 are in the low combustion stage, Unit 3 is in the high combustion stage, Unit 2 is in the standby stage, and Unit 5 is in the purge state. Next, as shown in FIG. 4 (b1), the recovery processing means 208 writes the combustion stage written in the combustion stage field 207b as it is in the previous instruction field 207a of the previous instruction table 207 as the previous instruction except for No. 5. At the same time, the No. 5 machine in the purged state is written in the previous instruction column 207a as low fuel.

  Next, the boiler determination means 203 refers to FIG. 4 (c1) with reference to the combustion stages of all the boilers including the written previous combustion instruction boiler, the priority order of all the boilers, and the necessary combustion amount (here, 3). As shown, the No. 5 machine with the highest priority among the previous combustion instruction boilers is determined as the high combustion instruction boiler (see decision criterion (6)). The instructions for all the boilers including the other previous instruction boilers are the same as the previous instruction, that is, Unit 1 and Unit 4 are low in combustion, Unit 3 is high in combustion and Unit 2 is in the standby stage. The instruction of the determined content is given to each boiler. When Unit 5 shifts to the high combustion stage, the combustion amount 3 required by the combustion amount calculation means 202 is satisfied. In the above, for example, when No. 4 has the highest priority, No. 5 is determined to be a low-burning instruction boiler and No. 4 is determined to be a high-burning instruction boiler.

  From this state, when the required amount of combustion decreases, the boiler 1 that sequentially burns in the procedure that Unit 1 with the lowest priority shifts to the standby stage, and regularly follows the priority and the required amount of combustion. The process shifts to normal control (see decision criterion (5)).

  Next, the case where the required combustion amount is 1.5 is considered as follows.

  As in the above example, when the control by the number control device 2 is restored, the combustion stage detection means 201 detects the combustion stage of each boiler 1 at the time of restoration, and writes this combustion stage in the combustion stage column 207b of the previous instruction table 207. Here, as described above, Unit 1 and Unit 4 are in the low combustion stage, Unit 3 is in the high combustion stage, Unit 2 is in the standby stage, and Unit 5 is in the purge state.

  Next, as shown in FIG. 4 (b2), the recovery processing means 208 replaces the combustion stage of each boiler other than the No. 5 machine with the previous instruction, and the purged No. 5 machine is set to low fuel, and the previous instruction table 207 Write in the previous instruction field 207a.

  Thereby, the boiler determination means 203 gives the following instructions with reference to the required combustion amount, the previous combustion instruction boiler and this priority. That is, as shown in FIG. 4 (c2), the purged No. 5 unit is preferentially determined as a standby boiler (decision criterion (7)), and the No. 1 unit having the lowest priority is set in the standby stage. Is determined (see decision criterion (4)). Next, the instructing unit 204 instructs each boiler to that effect. If Unit 1 moves to the standby stage, a total combustion amount of 1.5 can be achieved.

  After this, when the required load increases, Unit 5 with the highest priority shifts to low combustion, and when the required amount of combustion decreases from this state, Unit 3 with the lowest priority lowers the standby stage. The procedure will sequentially shift to a steady state (see Decision Criteria (5)).

(Embodiment 3)
The maintenance inspection is performed by stopping one or a plurality of boilers, and at this time, the local control device 5 of the stopped boiler is removed from the control of the number control device 2.

  FIG. 5 is a flow chart showing the recovery procedure of the present embodiment. In this embodiment, only the first unit with the lowest priority is excluded from the control of the number control device 2, and the other four boilers are number controlled. It is assumed that the device is operating normally under the control of the device 2. As in the previous embodiment, the number of boilers is 5, and the priority order is 5, 3, 4, 2, 1 in the order of Units 1-5.

  As shown in FIG. 5I, when only the first unit is out of the control of the unit control device 2, the first unit operates under the control of the local control unit 5, and the unit control unit 2 stores the previous instruction table 207 corresponding to the first unit. Write “self-combustion” in the previous instruction column 207a and “reset” in the combustion stage column 207b.

  At this time, if the required amount of combustion is 2.0, No. 4 and No. 5 in the controlled target boiler group will have high combustion. In addition, the first unit, which is a boiler controlled by the local control device 5, takes one of the standby stage, the low combustion stage, and the high combustion stage within the upper and lower pressure ranges set in the local control apparatus 5. However, here, it is assumed that when the control of the unit control device 2 is restored, the fuel is in a high combustion stage.

  Assuming that the first unit is restored to the control of the unit control device 2 and the required combustion amount has fluctuated to 2.5, as shown in FIG. 5II (a), the combustion stage detection means 201 combusts each boiler at the time of restoration. The stage is detected and written in the combustion stage column 207b of the previous instruction table 207. Here, as described above, No. 1, No. 4, No. 5, and No. 2 No. 3 are in the high combustion stage and No. 3 No. 3 is in the standby stage.

  Next, as shown in FIG. 5II (b), the recovery processing means 208 writes the combustion stage as it is in the previous instruction into the previous instruction column 207a of the previous instruction table 207.

  Here, since the required combustion amount requested is 2.5 and there is a combustion amount of 3 at the time of recovery, the boiler determining means 203 determines the combustion stage of all the boilers, the priority order of all the boilers, and the necessary combustion. Referring to the quantity, as shown in FIG. 5II (c), in accordance with the decision criterion (4), the low combustion instruction is issued to the first combustion engine with the lowest priority among the previous combustion instruction boilers at the time of recovery, and the priority is high Units 4 and 5 will be instructed to burn high, and units 2 and 3 will be instructed to wait.

  As a result, Unit 1 shifted from the high combustion stage to the low combustion stage, and the required combustion amount 2.5 could be realized without significant fluctuations in the combustion amount.

  After this, when the required combustion amount increases, among all the boilers, Unit 2, which has the highest priority after Units 4, 5, will enter the low combustion stage. From this state, if the required combustion amount decreases, the priority will be the highest. After going through the procedure that the first low unit moves to the standby stage, the four units will move to the steady state.

(Other embodiments)
In each of the above embodiments, the case where the combustion amount of the previous combustion instruction boiler is within the range of the required combustion amount has been described. However, the previous combustion instruction boilers are all high in combustion (that is, increased to the previous combustion instruction boiler). If the required amount of combustion is more than that, a low-burning instruction (combustion stage raising instruction) will be issued to the boiler with the highest priority in the standby (other than the previous combustion instruction) boiler. (See Decision Criteria (1) and (4)).

  Moreover, although the boiler having the states of the three combustion stages of standby, low fuel, and high fuel has been described, it is needless to say that the present invention can also be applied to a system including a boiler having more stages.

  Further, for the local control device 5 that is out of the control of the number control device 2, the instruction of “self-combustion” is written in the previous instruction column 207a of the previous table 207, but the state of the boiler from the number control device side is changed. When it can be grasped, the current combustion stage of the boiler may be written.

  Furthermore, in the above description, the combustion stage raising boiler is determined based on the combustion stage of the previous instruction table 207b, the priority order of each boiler, and the required combustion amount, but other conditions may be set depending on the situation. It does not exclude use.

  As described above, according to the present invention, the combustion stage of each boiler when the local controller that is out of the control of the unit controller is restored under the control of the unit controller is written in the previous instruction table as the previous instruction. Therefore, the boiler determining means can determine the boiler whose combustion amount is to be increased or decreased based on the previous instruction, and there is an advantage that the fluctuation of the pressure at the time of recovery is reduced. Further, it is less likely that the purge process of the boiler that is in the purge state at the time of recovery is wasted.

  The present invention is configured in the boiler unit control device so that the fluctuation of the steam pressure is reduced when the local control unit that is out of the control of the unit control unit is restored under the control of the unit control unit, and further, the purge state at the time of recovery Therefore, the multi-can combustion system can be operated efficiently and the industrial applicability is great.

1 is a schematic diagram of a multi-can combustion system to which the present invention is applied. It is a functional block diagram of the boiler number control device of the present invention. It is a flowchart which shows the operation | movement procedure of the boiler number control apparatus of this invention. It is a flowchart which shows another operation | movement procedure of the boiler number control apparatus of this invention. It is a flowchart which shows another operation | movement procedure of the boiler number control apparatus of this invention. It is a functional block diagram of the conventional boiler number control apparatus. It is a flowchart which shows the operation | movement procedure of the conventional boiler number control apparatus. It is a flowchart which shows another operation | movement procedure of the conventional boiler number control apparatus. It is a figure which shows the relationship of the required combustion amount and control width by a number control apparatus.

Explanation of symbols

201 Combustion stage detection means 202 Combustion amount calculation means 203 Boiler determination means 204 Instruction means 205 Setting value table 206 Priority order table 207 Previous instruction table 208 Recovery processing means

Claims (6)

In the boiler number control device of the multi-can installation system comprising a plurality of boilers having a plurality of combustion stages including a standby stage, and changing the combustion stage according to a load request,
When a boiler that is not subject to unit control is restored to the controlled object, a recovery processing means that notifies the boiler determining means as it is as the previous instruction of the combustion state of each boiler including the self-burning boiler at the time of the recovery;
Boiler determining means for determining a boiler for changing the combustion stage based on at least the combustion stage of all the boilers including the boiler notified from the recovery processing means, the priority order, and the required combustion amount corresponding to the required load. Boiler unit control device characterized by that.   The boiler number control device according to claim 1, wherein the boiler determining means determines, at the time of recovery, a previous combustion instruction boiler as a boiler that changes a combustion stage preferentially over a previous standby instruction boiler.   3. The boiler determination unit according to claim 2, wherein when the combustion amount of the previous combustion instruction boiler is more than the required combustion amount, the boiler determination unit sets the combustion stage lowering boiler in order from the lowest priority boiler among the previous combustion instruction boilers. Boiler unit control device.   2. The boiler number control according to claim 1, wherein when the combustion amount of the previous combustion instruction boiler is less than the required combustion amount, the boiler determination unit determines a boiler in a purged state as a combustion instruction boiler at the time of recovery. apparatus.   The number-of-boilers control according to claim 1, wherein when the combustion amount of the previous combustion instruction boiler is more than the required combustion amount, the boiler determination unit determines a boiler that has been in a purge state as a standby instruction boiler at the time of recovery. apparatus.   The boiler number control device according to any one of claims 2 to 5, wherein the boiler determining means sequentially repeats sequentially determining boilers whose combustion stages are changed based on priority orders of all boilers.

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