JP5541780B2 - Boiler multi-can installation system - Google Patents

Description

  The present invention relates to a boiler multi-can installation system in which a plurality of steam boilers are installed and a number control device for burning the required number of boilers based on the steam pressure value of the steam collecting portion is provided.

  A boiler multi-can installation system is widely used in which a plurality of small boilers are installed instead of a large boiler and the amount of steam generated is adjusted by controlling the number of boilers that are burned by a unit control device. In a multi-can installation system for steam boilers, a pressure detection device is provided in the steam collecting section that collects the steam generated in each boiler, and the steam pressure value detected by the pressure detection device controls the number of boilers burned Output to. In the number control device, the number of boilers to be burned is determined according to the steam pressure value in the steam collecting section, and a combustion command is output to each boiler. In the unit control device, the combustion amount of the boiler is determined according to the steam pressure value, and when the detected steam pressure value is low, the steam generation amount is increased by increasing the number of boiler combustions or the combustion amount of the boiler. Then, the steam generation amount is reduced by decreasing the number of boilers burned or the amount of combustion of the boilers as the steam pressure value increases. Control of keeping the steam pressure value within a predetermined range can be performed by increasing or decreasing the amount of combustion in the entire boiler according to the steam pressure value of the steam collecting portion.

  Specifically, as shown in FIG. 5, the number control device divides the adjustment range of the steam pressure into a plurality of pressure zones, and sets a combustion pattern that determines the combustion state of the boiler for each pressure zone. deep. If the boiler installed in multiple cans controls combustion at the three positions of high combustion, low combustion, and stop, the unit control device will use the high pressure, low combustion, Set how many units to stop. In the combustion pattern, determine the number of high combustion, low combustion, and stop so that the amount of combustion increases as the detected steam pressure value becomes the pressure zone on the low pressure side, and in order from the boiler with the highest priority of combustion Burn the determined number of boilers.

  In the boiler multi-can installation system, the amount of steam supplied from the boiler is increased or decreased by increasing or decreasing the amount of combustion in the entire boiler, but the output of the combustion command for the boiler and the actual change in the amount of generated steam appear. There is a time difference between The steam generation amount can be changed in a relatively short time if the combustion amount is reduced and if the combustion amount is increased from the state of combustion. However, when starting combustion of the boiler, a preparatory process such as pre-purge that ventilates the combustion chamber before starting combustion is necessary to prevent ignition with unburned residue remaining in the furnace. Thus, the combustion can be started only after the combustion preparation process is performed. Even if a combustion start command is output, steam cannot be generated in a boiler that is preparing for combustion, so the steam pressure value continues to decrease during that time.

In particular, when combustion is stopped in all boilers due to an increase in the steam pressure value, combustion can be started only after the combustion preparation process is completed, regardless of which boiler is instructed to start combustion. Therefore, the steam pressure value is greatly reduced because the steam supply is delayed.
Even if the steam pressure value becomes the pressure at the start of combustion and a combustion command is output to the boiler with the first priority in operation, the steam pressure value on the side where the steam pressure value is lower during the combustion preparation process in the first boiler When the pressure falls within the pressure category, the number control device outputs a combustion command to the boiler with the second highest operating priority. When the speed at which the steam pressure value decreases is high, combustion commands are sequentially output to the lower boilers before combustion starts. In this case, the steam pressure value is lowered because the combustion command is not output yet in the boiler that has output the combustion command. However, as the unit control device, the steam is output even if the combustion command is output to the boiler. Since the pressure value has decreased, it is determined that the combustion amount must be further increased, and the combustion command is output more than the combustion amount corresponding to the necessary steam amount. After that, when the boiler finishes the combustion preparation process and starts combustion one after another, the amount of steam generated becomes significantly larger than the amount of steam used. If the amount of steam generated is much larger than the amount of steam used, the steam pressure value will rise rapidly.

  In the unit control device, if the steam pressure value rises, the number of boilers burned is reduced to reduce the amount of steam generated. However, if the rise of the steam pressure value is rapid, the steam pressure value rises above the upper limit value of the pressure control range, and in that case, combustion is stopped in all boilers. When combustion of all boilers is stopped, even if the steam pressure value drops and a combustion command is output, steam preparation cannot be performed immediately because the preparation process for combustion is required. The value will drop rapidly. If it becomes like this, a steam pressure value will change a lot in a short time, and a boiler will generate hunting which repeats a combustion start and combustion stop in a short time, and cannot supply steam stably.

  Japanese Patent Application Laid-Open No. 2002-81606 describes an invention in which a gradient of steam pressure change during boiler combustion or standby is detected, and a change in combustion amount or a combustion start instruction signal is output early based on the detected gradient. There is. This shortens the time difference between when the combustion amount switching signal is output and when the combustion amount is changed.If the drop in the steam pressure value is abrupt, a combustion command is output at an earlier stage than usual. It is possible to reduce the delay. However, even in this case, a signal for sequentially switching the combustion amount according to the change of the steam pressure value is output, so that it is possible to completely prevent the occurrence of hunting that repeatedly increases and decreases the number of combustion due to excessive control. I couldn't.

JP 2002-81606 A

  The problem to be solved by the present invention is that in a boiler multi-can installation system that controls the number of boilers, it is possible to prevent a rapid drop in the steam pressure value due to a delay in steam supply and to stably supply steam. It is to provide a can installation system.

In the invention according to claim 1, a plurality of boilers are installed, and the steam generated by the plurality of boilers is once collected in the steam collecting part and then supplied to the steam necessary part. based on the vapor pressure value detected by the pressure detecting device provided in the boiler multi cans mounting system is provided with the unit count control device that performs output of the combustion command in descending order of priority boiler, quantity control device, the steam pressure value The steam pressure value at which the combustion stop command is output to the last boiler due to an increase and the steam pressure value at which the combustion execution command is output to the first boiler due to a decrease in the steam pressure value are set to the same value. The steam pressure value that outputs a command to decrease the combustion amount of the boiler by increasing the pressure value and the steam pressure value that outputs a command to increase the combustion amount of the boiler by decreasing the steam pressure value are different values. Characterized in that set.

According to a second aspect of the present invention, in the boiler multi-can installation system, when the number control device stops the combustion of the boiler due to an increase in the steam pressure value, one unit is combusted according to the increase in the steam pressure value. When the boiler combustion is restarted due to a decrease in the steam pressure value after the combustion of all boilers is stopped due to an increase in the steam pressure value, control is performed to start combustion with a plurality of boilers. And

The invention according to claim 3 calculates the steam usage status in the boiler multi-can installation system, and the unit control device sets the steam usage status when restarting combustion from the boiler all-can combustion stop state. Accordingly, control is performed to change the number of boilers that start combustion .

  By implementing the present invention, it is possible to prevent the steam pressure value from greatly decreasing due to the delay in steam supply even when combustion is started from a state where all the cans are stopped. Supply and reduction of the combustion amount increase / decrease frequency can be performed.

Configuration diagram of a boiler and a number control device for implementing the present invention Explanatory drawing which described change of steam pressure value in example and operation status of boiler Explanatory diagram listing steam pressure values and boiler combustion states in the present invention Explanatory drawing describing changes in steam pressure value and boiler operating status under conventional control Explanatory diagram listing steam pressure values and boiler combustion status in conventional control Explanatory drawing which showed the combustion pattern selection condition in 2nd Example

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a boiler and a number control device 2 for implementing the present invention. In the embodiment, three boilers 1 including No. 1 can, No. 2 can, and No. 3 can are provided, and each boiler 1 is connected to a common steam collecting portion 5. The steam generated in each boiler is collected in the steam collecting section 5 and then sent to the steam using device side, and the pressure detecting device 4 is provided in the steam collecting section 5. Each boiler 1 is provided with an operation control device 3, and the operation control of each boiler is performed by each operation control device 3. The operation control device 3 is connected to the number control device 2 that determines the combustion state of each boiler 1, and controls the operation based on the combustion command from the number control device 2.

  The number control device 2 determines the combustion amount in each boiler based on the steam pressure value detected by the pressure detection device 4. In the unit control device 2, the combustion state of the boiler is set in correspondence with the steam pressure value detected by the pressure detection device 4, and a combustion command is output to each boiler so that the determined combustion state is obtained. Further, the number control device 2 determines the priority of combustion for each boiler, and burns in order from the boiler with the highest priority. The priority order here is No. 1 boiler No. 1, No. 2 boiler No. 2 and No. 3 boiler No. 3.

  The steam pressure value and the combustion state of the boiler are set as shown in FIG. The adjustment range of the steam pressure value is divided into a plurality of pressure sections, and the combustion state of each boiler is determined for each pressure section. The boiler performs combustion control at three positions: high combustion, low combustion, and combustion stop. The high combustion, which is the maximum combustion amount, is H, the low combustion, which is half the amount of high combustion, is L, and the combustion stop is- Is shown. As the steam pressure value decreases, the combustion amount of the boiler increases, and when the steam pressure value increases, the combustion amount of the boiler decreases, thereby maintaining the steam pressure value within a predetermined range. The amount of evaporation indicates the amount of steam generated when the amount of steam generated by one high combustion unit is 2 t / h and the amount of steam generated by one low combustion unit is 1 t / h. When it is lower than 68 MPa, all three boilers are in high combustion, and the amount of steam generated is 6 t / h.

  The pressure category is set for each of the cases where the steam pressure value increases and decreases. When the steam pressure value is near the boundary of the pressure category, the detected steam pressure value is slightly It is possible to prevent a wasteful increase / decrease in the combustion amount due to fluctuation. For example, the initial steam pressure value is 0.69 MPa, and three boilers are performing high combustion. Since the steam supply amount is larger than the steam consumption amount, the steam pressure value rises to 0.71 MPa. Next, the case where the combustion state of the boiler is changed from H, H, H to H, H, L, and the steam pressure value returns to 0.69 MPa due to the decrease in the steam supply amount will be described as an example. In this case, since the pressure category at the time of pressure drop is lower than the pressure category at the time of pressure rise, after changing from H, H, H to H, H, L, the steam pressure value decreases to 0.68 MPa. Until it is H, H, and L, and the steam pressure value is 0.69 MPa, it is not necessary to change the combustion state. Therefore, the frequency of increase / decrease in the combustion amount can be reduced.

  However, the steam pressure value that outputs a combustion stop command to the last boiler due to an increase in the steam pressure value, and the steam pressure value that outputs a combustion execution command to the first boiler due to a decrease in the steam pressure value, Both are 0.90 MPa and the same value. Also, when changing the steam generation amount in the entire boiler by changing the steam pressure value, the combustion state is set so that the steam generation amount changes by 1 t / h at normal times, but all boilers are set to stop combustion. Only when combustion is started due to a decrease in the steam pressure value from the state, the combustion is started with two boilers, and the steam generation amount is increased by 2 t / h.

  This is because in a boiler, when changing the combustion amount between low combustion and high combustion and when stopping combustion, the combustion amount can be changed in a relatively short time, but when starting combustion after stopping combustion, It takes time to prepare for combustion, such as pre-purge to ventilate the furnace before the start, and steam generation is delayed by that much. If the steam pressure value drops while combustion is stopped in all boilers, no boiler can start combustion until the combustion preparation process is completed, and if the start of combustion is delayed, This is because the steam pressure value is greatly reduced. In the present invention, when a drop in the steam pressure value occurs from the state in which all cans are stopped, a combustion command is output early to prevent the start of combustion from being delayed, and at that time, a plurality of boilers are By outputting a combustion start command, the steam pressure value is prevented from drastically decreasing.

  FIG. 2 schematically shows a temporal change in the steam pressure value, the operation state of the boiler, and the amount of steam generated when the present invention is implemented. The upper part of FIG. 2 shows the fluctuation state of the steam pressure value, the middle part shows the operation state of each boiler based on the operation command output from the unit control device 2 to each boiler, and the lower part shows the steam generation in the entire boiler. The change in quantity is described.

  In FIG. 2, the No. 1 and No. 2 cans, which have the first and second combustion priorities, perform low combustion, and the No. 3 can starts from a state where combustion is stopped. At this time, the amount of steam generated is 2 t / h and the steam pressure value tends to increase. At time A, the steam pressure value is 0.86 MPa. When the steam pressure value becomes higher than 0.86 MPa, the combustion amount of the boiler defined in FIG. 3 becomes L, −, −, and therefore combustion of the No. 2 can is stopped at time A. From time A, only the low combustion in the No. 1 can is achieved and the steam generation amount is 1 t / h, but the steam pressure value continues to rise. When the steam pressure value reaches 0.90 MPa at time B, the combustion of the No. 1 can is stopped and the boiler stops the combustion of all the cans, and the amount of generated steam becomes zero.

  Thereafter, since the steam supply from the boiler is lost, the steam pressure value decreases after the delay time. When the steam pressure value becomes lower than 0.90 MPa at time C, the unit control device 2 has the first operation priority. The low combustion command is output to both the first can and the second can, and the combustion of the boiler is started and the supply of steam is resumed. However, in a boiler that has stopped burning, combustion cannot be started unless it undergoes a combustion preparation process, so the boilers of No. 1 and No. 2 can actually start combustion at the time when the combustion preparation process ends. From this point, the steam pressure value continues to decrease.

  After time D when the combustion preparation process is completed, the steam generation amount becomes 2 t / h due to the low combustion of the two boilers, and the steam pressure value starts to increase. Then, since the steam pressure value rose to 0.86 MPa at time E, the combustion of the No. 2 can be stopped, and the amount of steam generated after time E is 1 t / h.

  FIG. 4 shows an example of conventional control for comparison. FIG. 4 shows the same conditions as in FIG. 2, and the combustion pattern of the boiler with respect to the steam pressure is the case where the conventional combustion pattern described in FIG. 5 is implemented. In this case as well, the two boilers initially perform low combustion, the amount of steam generated is 2 t / h, and only the first can is low at time a, and the first can also stops burning at time b. The steam generation amount is the same as in FIG. Thereafter, at time c when the steam pressure value is reduced to 0.88 MPa, a combustion command for low combustion is output to the first can. In this case as well, in the boiler that has stopped combustion, combustion cannot be started unless the preparation process for combustion is performed, and during that period, steam supply cannot be performed, so the steam pressure value continues to decrease. Since the value has decreased to 0.84 MPa, the unit control device 2 outputs a combustion command for low combustion to the No. 2 can and starts preparation for combustion in the No. 2 can.

  The first can that previously output the combustion command has completed the combustion preparation process at time e and started low combustion, and the amount of steam generated is 1 t / h. However, since the steam supply amount is insufficient in one low combustion unit, the steam pressure value continues to decrease, and at time f, the steam pressure value decreases to 0.80 MPa. When the steam pressure value becomes less than 0.80 MPa, the number of boilers that perform low combustion becomes three, so the unit control device 2 outputs a low combustion combustion command to the No. 3 can that has stopped combustion. Start preparation for combustion in No. 3 can.

  The combustion preparation process in the No. 2 can is completed at time g, and when low combustion is started in the No. 2 can, the amount of generated steam is 2 t / h, so the steam pressure value is increasing. However, since the pressure is lower than the pressure at which combustion of the No. 3 can be stopped, preparation for combustion in the No. 3 can continues, and low combustion is also started in the No. 3 can from the time h when the preparation for combustion is completed. Thereafter, at time i, the steam pressure value increased to 0.82 MPa, so combustion of No. 3 can is stopped.

  The driving situation in the embodiment of FIG. 2 is compared with the driving situation in the conventional example of FIG. In the conventional example, the steam pressure value is greatly reduced due to the delay of the steam supply, and is lower than 0.80 MPa at time g. In the case of the example, since the delay of the steam supply is reduced, it is higher than 0.82 MPa even at the lowest time D, and the decrease in the steam pressure value is reduced. Further, in the conventional control, an operation for stopping combustion is performed immediately after low combustion is started in the No. 3 can boiler, and the number of changes in the combustion amount is increased. On the other hand, in the embodiment, since the change in the steam pressure value is reduced, the amount of combustion is not increased or decreased, and the steam can be supplied more stably.

  In the above embodiment, when the combustion is started after all the cans are stopped, the two boilers are burned at the same time. By doing so, the fluctuation of the steam pressure value can be further reduced. For example, if the flow rate of the steam sent from the steam collecting part 5 to the steam use location is calculated, the necessary number of boilers can be determined. Therefore, when starting combustion after stopping all-can combustion, the number of boilers is burned from the beginning. What should I do? Alternatively, the rate of decrease in the steam pressure value detected by the pressure detection device 4 of the steam collecting unit 5 may be calculated, and the number of combustion may be increased as the rate of decrease is increased.

  FIG. 6 shows a state in which the steam flow rate is calculated and the number of combustion units from the can stop of all cans is determined based on the steam flow rate. Here, a plurality of combustion patterns are set in advance, and the combustion pattern is selected according to the calculated steam flow rate. If the calculated steam flow rate exceeds 2 t / h, the amount of steam used is greater than the amount of steam generated even if 2 t / h steam is generated by low combustion of the two boilers. The steam pressure value will continue to decrease. In that case, when combustion becomes necessary from the state in which all cans are stopped, a combustion command for low combustion is output to the three boilers. If the steam generation amount is set to 3 t / h, the steam pressure value can be increased from a decrease to an increase after the start of combustion. Similarly, when the steam flow rate is 1 t / h to 2 t / h, the steam pressure value can be increased by causing the two boilers to perform low combustion and the steam generation amount to 2 t / h. Therefore, it is set so that the combustion command is output to the two boilers when the combustion is resumed from the stop of the combustion of all cans. In addition, when the steam flow rate is less than 1 t / h, the steam pressure value can be increased by performing low combustion with one boiler. The combustion command is output to the boiler.

DESCRIPTION OF SYMBOLS 1 Boiler 2 Number control device 3 Operation control device 4 Pressure detection device 5 Steam collecting part

Claims (3)

A plurality of boilers are installed, and the steam generated by the plurality of boilers is once collected in the steam collecting part and then supplied to the steam necessary part, and the steam detected by the pressure detection device provided in the steam collecting part In a boiler multi-can installation system equipped with a unit control device that outputs combustion commands in order from the highest priority boiler based on the pressure value, the unit control device burns to the last boiler due to an increase in the steam pressure value The steam pressure value at which the stop command is output and the steam pressure value at which the combustion execution command is output to the first boiler due to a decrease in the steam pressure value are set to the same value. and steam pressure values for outputting a decreasing command, the steam pressure value for outputting a command to increase the combustion amount of the boiler by lowering steam pressure value, characterized in that set to different values Boiler multi-cans installed system to. The boiler multi-can installation system according to claim 1, wherein when the steam pressure value rises , the unit control device stops combustion one by one in accordance with the rise of the steam pressure value, A boiler multi-can characterized in that when the combustion of the boiler is restarted by a decrease in the steam pressure value after the combustion of all the boilers is stopped by the increase of the pressure value, the combustion is controlled by a plurality of boilers. Installation system. 3. The boiler multi-can installation system according to claim 2 , wherein the steam usage status is calculated, and the unit control device starts combustion in accordance with the steam usage status when combustion is restarted from the boiler all-can combustion stop state. A boiler multi-can installation system characterized by performing control to change the number of boilers to be operated .

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