JP5465473B2 - 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 installed 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 the device. In the number control device, the number of boilers to be burned is determined according to the steam pressure value in the steam collecting portion. 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 amount of steam generated is increased by increasing the number of boiler combustions. The amount of steam generated is reduced by reducing the number of boilers that burn as the temperature rises. Control of keeping the steam pressure value within a predetermined range can be performed by increasing / decreasing the number of combustion boilers according to the steam pressure value of the steam collecting portion.

  Specifically, 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. 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, A combustion pattern that determines how many stops are set in advance. 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 can be 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 steam supplied appear. There is a time difference between When starting combustion of the boiler, in order to prevent ignition with the unburned portion remaining in the furnace, a preparatory process such as pre-purge that ventilates the combustion chamber before starting combustion is necessary. Combustion can be started only after the combustion preparation step is performed. Even if the combustion command is output, the boiler that is preparing for combustion cannot supply steam, and the steam pressure value during that time continues to decrease.

  If the steam pressure value falls within the lower pressure zone during the boiler combustion preparation process, the unit control device outputs a combustion command to the next combustion priority boiler. When the speed at which the steam pressure value decreases is high, in response to the decrease in the steam pressure value, the combustion command is output to the boilers installed in multiple cans one after another to increase the number of boilers in preparation for combustion. Try to make up for the shortage of steam by increasing the number of combustion. Then, it will output a combustion command to more boilers than the number of boilers corresponding to the amount of steam actually required, and after that the boiler finishes the combustion preparation process and starts combustion one after another, The amount of steam supplied is significantly larger than the amount of steam used. If the amount of steam supply is greater than the amount of steam used, the steam pressure value will increase, and if the amount of steam supply is significantly greater than the amount of steam used, the steam pressure value will increase rapidly.

  If the steam pressure value rises, the unit control system tries to balance the steam consumption and steam supply by reducing the number of boilers burned, but if the steam pressure value rises rapidly, the steam pressure value Without exceeding the adjustment range, the temperature rises to the upper limit value of the adjustment range, and as a result, all the boilers are stopped. Then, this time, the amount of steam supplied becomes significantly smaller than the amount of steam used, and the steam pressure value suddenly drops. In the multi-unit control system, the combustion command is sequentially output again to the boiler. However, since the combustion preparation process is necessary at the start of combustion, and steam cannot be supplied immediately, the steam supply is delayed and again necessary. The hunting which repeats outputting a combustion command with respect to the above boiler was generated. When hunting occurs, the steam pressure value repeatedly goes higher and lower than the adjustment range, so that it is impossible to stably supply steam.

  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. Has been. In this invention, since the combustion preparation process is started earlier than usual for the boilers with lower priority, the control delay can be reduced. However, even in this case, it has not been possible to completely prevent the occurrence of hunting that repeatedly increases and decreases due to excessive control.

  FIG. 3 is an explanatory diagram showing an example of changes in the steam pressure value and the operation status of the boiler in this conventional control. In this case, the steam pressure value reaches the upper limit value at time a, and the combustion in all the boilers is stopped with the number of combustion being zero. Thereafter, at time b, the steam pressure value is in the pressure range of one combustion unit, and the unit control device outputs a combustion start instruction signal to the boiler of the first can. However, in order for the boiler to start combustion, a preparatory process such as pre-purge is required, so combustion is not started immediately, and the steam pressure value continues to decrease. Further, at the time c when the steam pressure value is decreased, the combustion start instruction signal is output also to the No. 2 can, and the gradient of the change in the steam pressure value from the time b to the time c is detected. When this gradient is large, the combustion start pressure is not yet applied to the third and fourth boilers, but the unit control device outputs a combustion start instruction signal to the boilers of the No. 3 and No. 4 boilers. Keep going.

  At this stage, no boiler is burning, and all the boilers are preparing for combustion, so the steam pressure value continues to drop. Thereafter, at time d, the boiler of the first can starts combustion, and at time e, the boilers of the second to fourth can also start combustion. When combustion is started with four boilers, the amount of steam generated increases rapidly, so the steam pressure value increases rapidly. At time f, the steam pressure value reaches the upper limit of control, and the number of combustion units becomes zero. Because of this, combustion is stopped in all boilers. Then, since the amount of generated steam is rapidly reduced, hunting is repeatedly performed in which the steam pressure value rapidly decreases again. If it becomes like this, supply of the stable vapor | steam will become impossible.

JP 2002-81606 A

  The problem to be solved by the present invention is to provide a boiler multi-can installation system capable of stably supplying steam by preventing the occurrence of hunting in a boiler multi-can installation system performing unit control. It is in.

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 boiler with the highest priority based on the pressure value, the unit control device takes time to resume steam supply because all boilers have been stopped. In such a case, for a boiler whose priority is lower than a certain order, a delay for starting the output of the combustion command after a predetermined delay time from the normal combustion command output time determined from the steam pressure value. control has a row Migihitsuji to, whether performed the delay control in advance by detecting the elapsed time from the time of starting the output of the combustion command to the highest boiler priority, when the elapsed Is determined to be shorter than a reference time, and before the elapsed time reaches the reference time, when a combustion command is to be output to a boiler whose priority is lower than a certain order, For a boiler with a lower priority order, a delay control for starting the output of a combustion command after a predetermined delay time from the normal combustion command output time determined from the steam pressure value is performed, and the condition for performing the delay control If this is not the case, delay control is not performed.

  By practicing the present invention, it is possible to prevent the occurrence of hunting that causes a rapid decrease and increase in the steam pressure value, and to supply steam stably.

Configuration diagram of a boiler and a number control device for implementing the present invention Explanatory drawing which described change of steam pressure value and operation status of boiler in the present invention Explanatory drawing which showed change of steam pressure value by conventional control for comparison and operation situation of boiler

  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, four boilers 1 including No. 1 can, No. 2 can, No. 3 can and No. 4 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, No. 3 boiler No. 3, No. 4 No. 4 boiler No. 4.

  FIG. 2 schematically shows temporal changes in steam pressure values, boiler operating conditions, and steam generation. The upper part of FIG. 2 shows the change in steam pressure value, the middle part shows the operation state of the boiler based on the operation command output from the unit control device 2 to each boiler, and the lower part shows the steam generation amount in the entire boiler. The change of is described. In the number control device 2, the range of adjustment of the steam pressure value is divided into a plurality of pressure zones. When the steam pressure value becomes low, the number of boilers to be burned is increased, and when the steam pressure value becomes high, the boiler Reduce the number of combustion. The number control device 2 determines the number of boiler combustions based on the steam pressure value, and outputs combustion commands to the boiler operation control device 3 in order of priority.

  Further, in the unit control device 2, when it takes time to restart the steam supply because all boilers have been stopped, normal combustion determined from the steam pressure value is given to boilers that are lower in priority than a certain order. Delay control for starting the output of the combustion command after a predetermined delay time from the command output time is performed. The delay control is performed by the lower priority boiler when outputting a command to continuously increase the combustion amount of the boiler from the state where all the boilers to be controlled are in a can-stop state. In this embodiment, the priorities of the boilers that perform the delay control are the third and fourth, and the normal combustion command determined from the steam pressure value in the boilers lower than the third that has priority. The combustion command is output after a predetermined time delay from the output time.

  In FIG. 2, only the No. 1 can with the first combustion priority is burning, and the steam pressure value is starting to rise. At time A when the steam pressure rises and exceeds the upper limit of the steam pressure adjustment range, the number of boilers determined from the steam pressure value is zero, so the number control device 2 is used for the first can that was burning. Output a stop command to stop combustion. Thereafter, when there is no steam supply from the boiler, the steam pressure value starts decreasing, and at time B, a combustion command is output to the boiler of the No. 1 can, and the No. 1 can starts the combustion preparation process. In the No. 1 boiler, combustion starts after a certain period of time required for preparation for combustion. However, since the rate of decrease in the steam pressure value is large, the steam before the No. 1 boiler starts combustion. The pressure value is greatly reduced. Therefore, at time C, the combustion designation is output to the No. 2 boiler, and at time D and time E, the steam pressure is output to output the combustion command to the No. 3 and No. 4 boilers. It is a value. However, since the combustion command after all boilers to be controlled at the time A are stopped at all times, the command to increase the combustion amount of the boiler is output continuously from the time B, C, D, E. And at time E, for the No. 3 and No. 4 cans with the third and fourth priorities, delay control is performed to provide a predetermined delay time before the start of combustion preparation. .

  Thereafter, in the boilers of the No. 1 and No. 2 boilers that have started preparation for combustion, combustion is started as soon as the process of preparation for combustion is completed. When the combustion preparation process is completed and combustion starts, and the generation of steam begins, the steam pressure value increases. At time F, No. 3 can finishes the predetermined delay time and enters the preparation process, and No. 4 can be in the delay time. At this time F, the steam pressure value is in the pressure range where the number of combustion is three, so that the combustion stop is output to the No. 4 can with the fourth priority. Therefore, in No. 4 can, it stops without starting the process of combustion preparation. Furthermore, since the steam pressure value rises and the number of combustion units is two at time G, the No. 3 can that was preparing for combustion stops the preparation process at this point and stops combustion.

  In the conventional example shown in FIG. 3, when steam is generated by four boilers, the steam generation amount becomes very large, and the steam supply amount becomes much larger than the steam consumption amount. become. However, in this embodiment, since the delay control is performed by the boilers of No. 3 and No. 4 cans, combustion is not performed, and there are only two boilers that supply steam. Has become moderate.

  Even when the number of combustion is two, the steam pressure value is rising, and the combustion can be stopped even in the No. 2 can that has been combusting until the time H. After that, the steam pressure value has decreased, and preparation for combustion is started at No. 2 can at time I and at No. 3 can at time J. If the steam pressure value decreases in a straight line from the time when all cans are stopped to the start of combustion for the No. 3 can, delay control is performed before the start of combustion for the No. 3 can. Is not true. During the period from time A to time J when all cans are stopped, the output of a command for changing the combustion from the combustion execution to the combustion stop is given to the second, third and fourth priority boilers. Therefore, at time J, preparation for combustion is started without performing delay control.

  In this embodiment, even when only two boilers are combusting, the steam pressure value is rising, so at time DF, the steam pressure value falls to a pressure zone that causes the boiler to burn. However, the boilers of No. 3 and No. 4 boilers, which have a lower combustion priority, did not need to be operated. In this case, the boiler that does not need to burn quickly like the present invention can slow the change of the steam pressure value by delaying the start of combustion, and can prevent the occurrence of hunting. .

  In the embodiment, whether or not the delay control is performed is determined by whether or not a command for increasing the combustion amount of the boiler is continuously performed. However, delay control is performed because all boilers are stopped, it takes time to restart steam supply, steam supply temporarily falls short of time, and the steam pressure value decreases, so it is necessary to combust originally The determination to perform the delay control is not limited to the above method because the steam pressure value is prevented from suddenly rising by performing combustion up to a boiler having no noise. In other words, it is only necessary to prevent the start of combustion in the lower priority boiler when the time is little open from the state where all cans are stopped. When the elapsed time from the time B deviating from the time is shorter than the reference time, it may be determined that the delay control is performed in the boiler with the lower priority.

  If the steam pressure does not increase in the combustion for two boilers due to the large amount of steam used, the combustion can be performed based on the combustion command when the delay time ends in the No. 3 and No. 4 cans. . When steam is generated in the No. 3 and No. 4 cans, even if the amount of steam used is large, the steam pressure value increases, so there is no shortage of steam supply.

In the embodiment shown in FIG. 2, the combustion amount control of the boiler is controlled on-off. When the combustion amount control is controlled at three positions of high combustion, low combustion, and stop, control for changing the combustion amount between high combustion and low combustion is added, but a combustion preparation step is necessary when starting combustion. This is the same, and the above effect can be obtained by implementing the present invention even in the case of three-position control.

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

Claims (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, and the steam detected by the pressure detection device provided in the steam collecting part In a boiler multi-can installation system provided 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 has a plurality of boilers installed, The steam generated in step 1 is once collected in the steam collecting part and then supplied to the necessary steam part. Based on the steam pressure value detected by the pressure detector installed in the steam collecting part, the boilers are burned in order from the highest priority boiler. In a boiler multi-can installation system equipped with a unit control unit that outputs commands, the unit control unit is in priority order when it takes time to resume steam supply because all boilers have been stopped. For boilers to be lower than the rank that is, than the normal combustion command output time determined from the vapor pressure value, and the row Migihitsuji delay control to start output of the combustion instruction is delayed a predetermined delay time Whether to perform the delay control is determined by detecting the elapsed time from the start of the output of the combustion command to the boiler with the highest priority and determining whether the elapsed time is shorter than the reference time. If the combustion order is to be output to a boiler whose priority is lower than a certain order before the elapsed time reaches the reference time, The delay control for starting the output of the combustion command is delayed by a predetermined delay time from the normal combustion command output time determined from the steam pressure value, and if the condition for performing the delay control is not satisfied, the delay control is performed. Boiler multi cans installed systems, characterized in that not adversely.

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