JP2005049008A - Controller for number of boiler in multiple boiler installation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent output of a command for changing a combustion amount to a boiler which is not necessary to change the combustion amount and output an reverse command immediately after that. <P>SOLUTION: A multiple boiler installation system is equipped with a number of boiler controller 3 that determines a combustion state each of a plurality of boilers 1 installed therein according to the vapor pressure at a vapor gathering section 4 and controls the number of the boilers for the necessary number of boilers in combustion. When changing output of a combustion state is issued based on a vapor pressure variation, a combustion command for change of combustion state is not output until a predetermined time T passes after the vapor pressure change is detected. If the change direction of the vapor pressure is reversed within the predetermined time T, the combustion command of combustion state change based on the vapor pressure variation detected before the change direction of the vapor pressure is discarded. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a number control device in a boiler multi-can installation system.

  2. Description of the Related Art A boiler multi-can installation system that installs a plurality of boilers and adjusts the number of boiler combustions according to the load is known. In the case of a multi-can installation system for steam boilers, the steam pressure is adjusted by controlling the combustion amount (number) of the boilers based on the steam pressure value detected by the pressure detection device provided in the steam header. In the unit control system, the pressure control range of the steam pressure is divided into a plurality of pressure categories, and the combustion amount of the boiler is determined for each pressure category, and the combustion amount of the boiler is determined according to which pressure category the steam pressure value corresponds to. Find and burn as many boilers as necessary. Even if the steam supply amount is constant, the detected steam pressure value will increase if the steam usage amount in the steam usage section decreases, and the steam pressure value will decrease if the steam usage quantity in the steam usage section increases. Therefore, the steam pressure value becomes the control pressure by reducing the number of boiler combustions as the steam pressure value shifts to the high pressure side pressure category, and increasing the number of boilers burned as the steam pressure value moves to the low pressure side pressure category. Control to keep within the width.

  FIG. 3 explains the conventional number control. Here, five boilers for ON-OFF control are installed, and the pressure control range is 0.70 MPa to 0.78 MPa. In this case, when the steam pressure value is less than 0.70 MPa, 5 boilers are burned, and when the steam pressure value is within the range of 0.70 MPa to 0.72 MPa, 4 boilers are burned, and the steam pressure value is When it is within the range of 0.72MPa to 0.74MPa, 3 boilers are burned. When the steam pressure is within the range of 0.74MPa to 0.76MPa, 2 boilers are burned, and the steam pressure is 0.76MPa. If it is within the range of 0.78MPa, the number of combustion units is determined so that one boiler is burned, and when the steam pressure exceeds 0.78MPa, the number of boilers burned is zero.

  The steam pressure value in FIG. 3 starts from 0.72 MPa to 0.74 MPa, and in this case, three boilers burn. At first, the steam pressure value increased because the amount of steam used was small. When entering the pressure range from 0.74MPa to 0.76MPa at point a, the number of combustion units increased to 2 and increased further from 0.76MPa at point b. When entering the 0.78 MPa category, the number of combustion units is 1, and when the steam pressure value exceeds 0.78 MPa at point c, the steam pressure value rises and moves to the high pressure side pressure category so that the number of combustion units becomes 0 units. Control is performed to reduce the number of burns every time. After that, the steam pressure value has started to decrease due to the increase in the amount of steam used. From point d to point f, control is performed to increase the number of burned boilers each time the pressure class is changed to the low pressure side, and the number of burned units is reduced to three. It has increased. Thereafter, the steam pressure value increased again due to the decrease in the amount of steam used, and the number of combustion units decreased from 3 to 2 at point g.

  In FIG. 3, the number of combustion is decreased from point a to point c, the number of combustion is increased from point d to point f, and the number of combustion is increased at point g. Will increase. In particular, the boiler that has stopped combustion at point c starts combustion again at point d, which is immediately thereafter, and the boiler that has started combustion at point f stops combustion at point g, which is immediately after that. The reverse combustion command is output. When the number of combustion starts and stops increases, there is a problem that heat loss increases due to pre-purge performed before the start of combustion, and the life of the equipment is shortened. Further, a boiler that has received a combustion command requires time required for steaming preparation such as pre-purge when starting combustion, and steam cannot be supplied during that time. Therefore, although the combustion command was output due to the decrease in the steam pressure value, the steam pressure value further decreased during the steaming preparation time and entered into the low pressure side pressure section, and the unit control device burned to another boiler. A command may be output. In this case, if the steam pressure value rises when the boiler that has previously issued the combustion command starts combustion, the boiler that later output the combustion command is a boiler that did not need to start combustion, Combustion will be stopped in the middle of steaming preparation.

  The problem to be solved by the present invention is to prevent a situation in which an instruction to change the combustion amount is output to a boiler that originally does not need to change the combustion amount and the reverse output must be performed immediately thereafter. It is in.

   Installing multiple boilers, installing multiple boilers with a unit control device that controls the number of boilers that determine the combustion state of each boiler according to the steam pressure value in the steam collecting section and burns the required number of boilers In the system, when the combustion state change is output by the variation of the steam pressure value, the combustion command for changing the combustion state is not output until the predetermined time T has elapsed after the change of the steam pressure value is detected, and the predetermined time T When it is detected that the change direction of the steam pressure value is reversed, the combustion command for changing the combustion state based on the steam pressure value detected before the change of the steam pressure value change direction is discarded.

  By implementing the present invention, it is possible to reduce unnecessary changes in the amount of combustion before and after reversing the change direction of the steam pressure value.

  FIG. 1 is a block diagram showing the overall configuration of a boiler multi-can installation system in an embodiment of the present invention device, and FIG. 2 is an explanatory diagram showing the relationship between steam pressure change and boiler combustion control in the embodiment.

  In this embodiment, five boilers 1 that perform combustion control by ON-OFF are installed, and a steam header 4 that collects steam generated in each boiler is provided. The generated steam is collected in the steam header 4 through the steam pipe 5 that connects each boiler 1 and the steam header 4 and then sent to the steam using unit 2. The steam header 4 includes a pressure detector that detects the steam pressure. 6 is provided. Each boiler is provided with an operation control device 7, and the operation control device 7 receives a combustion command from the number control device 3 and performs combustion control of the boiler. The pressure control range is 0.70MPa to 0.78MPa, and the unit control device 3 keeps the steam pressure value detected by the pressure detector 6 of the steam header 4 within the pressure control range of 0.70MPa to 0.78MPa. Control the number of combustion.

  The number control unit 3 sets the number of boilers to be burned according to the steam pressure value. If the steam pressure value is less than 0.70 MPa, 5 boilers are burned, and the steam pressure value is 0.70 MPa to 0.72 MPa. When it is in the MPa pressure category, it burns 4 boilers, and when it is in the pressure category of 0.72 MPa to 0.74 MPa, it burns 3 boilers, and the steam pressure value is 0.74 MPa to 0.76 MPa. Two boilers are burned when in the pressure category, one boiler is burned when the steam pressure value is between 0.76 MPa and 0.78 MPa, and the boiler is burned when the steam pressure value exceeds 0.78 MPa The number of combustion is determined so that the number is zero. In addition, the number control device 3 instructs the boiler 1 to change the combustion amount after a predetermined time T has elapsed since the number of combustion was detected from the steam pressure value based on the above setting, and the predetermined time T If the change direction of the steam pressure value is reversed, the combustion command detected before the reversal is set to be discarded. The predetermined time T can be set to a value of 1 to 10 seconds (in units of 1 second).

  FIG. 2, which shows the change in the steam pressure value and the number of burned units, is in the pressure section where the steam pressure value is 0.72 MPa to 0.74 MPa, and the number of burned units starts from three. At the first stage, the steam pressure is increasing because the amount of steam used is small. When the pressure range from 0.74MPa to 0.76MPa is entered at point A, the unit controller 3 determines the number of combustion units determined from the steam pressure value. And that the change direction of the steam pressure is the upward direction. The number control device 3 does not output the combustion amount change after a predetermined time T has elapsed from when the number of combustion is detected from the steam pressure value. The output to be changed is not performed, and the number of combustion continues to be 3.

  When the steam pressure value rises and enters the pressure range from 0.76MPa to 0.78MPa at point B, the unit control device 3 detects that the number of combustion units determined from the steam pressure value is one, and the change direction of the steam pressure Detects that the pressure is rising. Since the output of changing the number of combustion to 1 is not performed until after the predetermined time T has elapsed, the number of combustion continues to be 3. Further, the steam pressure value change direction detected at point B is compared with the steam pressure value change direction detected at point A. When the change direction of the steam pressure value at the point A is the same as the change direction of the steam pressure value at the point B, the determination that the number of combustion detected at the point A is two is continued.

  When the elapsed time from the point A reaches the predetermined time T (for example, 3 seconds), the number control device 3 executes the output of the combustion command for changing to the two combustion numbers detected at the point A, and the combustion The number of combustion units is set to two by stopping the combustion of one unit from the three boilers.

  When the steam pressure value further rises and enters the pressure category higher than 0.78 MPa at point C, the unit control device 3 detects that the number of combustion units determined from the steam pressure value is 0, and the change direction of the steam pressure is Detect that the direction is ascending. Since the output of changing the number of burned units to 0 is not performed until a predetermined time T has elapsed from point C, the number of burned units is kept at 2 units, and the change direction of the steam pressure value detected at point C is The steam pressure value change direction detected at point B is compared. When the change direction of the steam pressure value at the point B is the same as the change direction of the steam pressure value at the point C, the determination that the number of combustion detected at the point B is one is continued.

  When the elapsed time from the point B reaches the predetermined time T, the number control device 3 changes the steam pressure value change direction to one that is detected at the point B after confirming that the change direction of the steam pressure value is not reversed. The number of combustion units is set to one by executing the output of the combustion command and stopping one combustion from the two boilers that are burning.

  The steam pressure value has fallen, and when entering the pressure segment from 0.76 MPa to 0.78 MPa at point D, the unit control device 3 detects that the number of combustion units determined from the steam pressure value is one, and the steam pressure It is detected that the changing direction is the descending direction. Since the number of combusted units at the present time is one, the detection that the number of combusted units detected from the steam pressure value is one is not to change the number of combusted units, but one unit detected here will be necessary in the future. Therefore, in the number control device 3, a combustion command for making one unit is output after a predetermined time T has elapsed, as in the case where it is determined that the number of combustion units needs to be changed. deep. Further, the steam pressure value change direction detected at point D and the steam pressure value change direction detected at point C are compared. Since the steam pressure value change direction at the point C is an ascending direction and the steam pressure value change direction at the point D is a descending direction, the steam pressure value change direction is reversed. If the change direction of the steam pressure value changes within the predetermined time T, the combustion command detected before the reversal of the steam pressure value change direction is discarded. The detection of being a stand is discarded.

  When the steam pressure value further falls and enters the pressure range from 0.74 MPa to 0.76 MPa at point E, the unit control device 3 detects that the number of combustion units determined from the steam pressure value is two, and changes in the steam pressure It is detected that the direction is the descending direction. Since the output of changing the number of combustion units to two is not performed until the predetermined time T has elapsed, the number of combustion units continues to be one, and the steam pressure value change direction detected at point E and point D The detected steam pressure value change direction is compared. Since the change direction of the steam pressure value at the point D is the same as the change direction of the steam pressure value at the point E, it is determined that the number of combustion detected at the point D is one.

  When the elapsed time from the point D reaches the predetermined time T, the number control device 3 confirms that the change direction of the steam pressure value is not reversed, and then sets the number of combustions as one detected at point D The output of the command is executed, but since the number of burned units is already one, the number of burned units does not actually change.

  When the steam pressure value further falls and enters the pressure range from 0.72 MPa to 0.74 MPa at point F, the unit control device 3 detects that the number of combustion units determined from the steam pressure value is 3, and changes in the steam pressure It is detected that the direction is the descending direction. Since the output of changing the number of combustion units to 3 is not performed until the predetermined time T has elapsed, the number of combustion units is kept at 1 unit, the change direction of the steam pressure value detected at point F, and point E The detected steam pressure value change direction is compared. Since the change direction of the steam pressure value at the point E is the same as the change direction of the steam pressure value at the point F, the determination of changing the number of combustion detected at the point E to two is continued.

  When the elapsed time from the point E reaches the predetermined time T, the number control device 3 outputs a combustion command to change the number of combustion units detected at the point E to two if the change direction of the steam pressure value is not reversed. However, at a point G at which the predetermined time T has elapsed, the pressure is in the range of 0.74 MPa to 0.76 MPa. The change direction of the steam pressure value at the point E is the downward direction, the change direction of the steam pressure value at the point G is the upward direction, and the change direction of the steam pressure value is reversed. The detection that the number of burned units detected in step 2 is discarded is discarded. At the same time, the steam pressure value changing direction at the point F is the descending direction, the steam pressure value changing direction at the point G is the rising direction, and the steam pressure value changing direction is reversed. The detection that the number of combustion detected by F is set to 3 is also discarded. In addition, the number control device 3 again detects that the number of combustion units determined from the steam pressure value is two because the pressure range from 0.74 MPa to 0.76 MPa is entered at the point G. Since the output of changing the number of combustion detected at the point G to two is not performed until the predetermined time T has elapsed from the point G, the number of combustion continues to be one.

  In the embodiment, the boiler is controlled on and off, and the combustion amount is controlled by the number of combustion units. However, the number of units is controlled by using a boiler that controls combustion at three positions: high combustion, low combustion, and stop. The same applies when performing the above. If each boiler performs stepwise combustion control, the control of the combustion amount is adjusted not only by the number of combustion units but also by the combustion amount in each boiler, but the unit number control method is the same as in the above embodiment. .

The block diagram which shows the whole structure of the boiler multi-can installation system in the Example of this invention apparatus. Explanatory drawing which showed the relationship between the steam pressure change and boiler combustion control in an Example Explanatory drawing showing the relationship between steam pressure change and boiler combustion control in the conventional example

Explanation of symbols

1 boiler
2 Steam use part
3 Number control device
4 Steam header
5 Steam piping
6 Pressure detector
7 Operation control device

Claims (1)

   Installing multiple boilers, installing multiple boilers with a unit control device that controls the number of boilers that determine the combustion state of each boiler according to the steam pressure value in the steam collecting section and burns the required number of boilers In the system, when the combustion state change is output by the variation of the steam pressure value, the combustion command for changing the combustion state is not output until the predetermined time T has elapsed after the change of the steam pressure value is detected, and the predetermined time T When a change in the direction of change of the steam pressure value is detected, the combustion command for changing the combustion state based on the steam pressure value detected before the change of the change direction of the steam pressure value is discarded. Number control device in multi-can installation system.

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