JP5522840B2 - Combustion amount change boiler - Google Patents

Description

  The present invention relates to a combustion amount changing boiler in which the combustion amount is set in a stepwise manner and the combustion amount can be increased or decreased according to load fluctuations.

  Boilers that set the combustion amount in stages like high combustion and low combustion and change the combustion amount as necessary are widely used. The combustion amount can be changed by increasing or decreasing the fuel supply amount and the combustion air supply amount. Since the fuel supply amount is changed by opening and closing an electromagnetic valve provided in the fuel supply path, it can be changed instantaneously. However, since the change in the combustion air supply amount is performed by changing the rotation speed of the blower motor or changing the opening of the damper provided in the middle of the air passage, it is not compared with the change in the combustion air supply amount. Takes a long time. For this reason, it is necessary to change the combustion amount due to the load change, and the load change occurs again while the operation for changing the combustion air supply amount is performed, and the change operation of the combustion amount must be canceled and returned to the original combustion amount. There were times when I had to go. If it is desired to return to the original combustion amount due to a load fluctuation in the middle of changing the combustion amount, if the cancellation of the combustion amount change is not accepted, the load followability becomes worse. However, if cancellation is performed in a dark manner, the balance between the fuel supply amount and the combustion air supply amount is lost, and there is a risk that harmful substances are generated, noise is generated, and a fire breaks out.

  Japanese Patent No. 4419156 describes an operation when cancellation of the change in the combustion amount occurs. For example, in the case of canceling the change to high combustion and returning to low combustion in the middle of the change from low combustion to high combustion, it returns to the low combustion that is the original combustion amount upon receiving the cancellation, and a predetermined time elapses. Until now, there has been proposed a boiler that performs control so as not to change to high combustion. However, in this control, regardless of the stage of the combustion amount change process, when the change in the combustion amount is canceled, the original combustion amount is restored. When the combustion amount is changed, the fuel amount and the combustion air are changed. There was a risk that the balance of the amount would be lost.

Japanese Patent No. 4419156

  The problem to be solved by the present invention is that, in a boiler that changes the combustion amount in stages, the change is canceled at the time of changing the combustion amount, and even when returning to the original combustion amount in the middle of changing the combustion amount Another object of the present invention is to provide a combustion amount changing boiler that can prevent the balance between the fuel supply amount and the combustion air supply amount from being lost and can maintain high combustion stability.

  In the first aspect of the invention, the fuel supply amount and the combustion air supply amount are set in stages, and the combustion amount is increased or decreased by increasing or decreasing the fuel supply amount and the combustion air supply amount. When the combustion amount is changed, the change of the combustion air supply amount is started first, and when the combustion air supply amount reaches the set value of the fuel supply amount change, the fuel supply amount is changed. In a combustion amount change boiler that is trying to change, if the increase in the combustion amount is canceled during the operation to increase the combustion amount based on the combustion command for increasing the combustion amount, the air supply amount decreases the fuel supply amount If the air supply amount has not reached the set value, the control in the direction of increasing the combustion amount is continued until the air supply amount reaches the set value for decreasing the fuel supply amount, and the air supply amount has reached the set value for decreasing the fuel supply amount. Later, fuel supply and combustion air supply decreased When canceling the decrease in the combustion amount while performing the operation to decrease the combustion amount based on the combustion command for reducing the combustion amount, before the air supply amount reaches the set value for the increase in the fuel supply amount. If there is, the control in the direction of decreasing the combustion amount is continued until the air supply amount reaches the set value for increasing the fuel supply amount, and after the air supply amount reaches the set value for increasing the fuel supply amount, It is characterized by starting the increase of the combustion air supply amount.

  According to a second aspect of the present invention, in the combustion amount change boiler, when the increase in the combustion amount is canceled during the operation of increasing the combustion amount based on the combustion command for increasing the combustion amount, the air supply amount is If there is a combustion command output that cancels the increase in the combustion amount after reaching the set value for the decrease in the fuel supply amount, control in the direction to decrease the air supply amount without starting the delay time is started. When the air supply amount reaches the set value for reducing the fuel supply amount, the fuel supply amount is reduced, and the reduction in the combustion amount is canceled during the operation of reducing the combustion amount based on the combustion command for reducing the combustion amount If there is a combustion command output that cancels the decrease in the combustion amount after the air supply amount reaches the set value for the increase in the fuel supply amount, the air supply amount is increased in the direction of increasing the delay time. Start control and air supply The amount is equal to or performs a increase of fuel supply amount after reaching the set value of the increase amount of fuel supply.

  By implementing the present invention, even when the change of the combustion amount is canceled and the change to the original combustion amount is made in the middle of the change of the combustion amount, the balance between the fuel supply amount and the combustion air supply amount is balanced. It is possible to prevent collapse and maintain high combustion stability.

Time chart in one embodiment of the present invention Configuration diagram of a boiler implementing the present invention Explanatory drawing of the combustion amount change cancel execution time in the present invention

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a time chart showing a boiler operation state in which the present invention is implemented, and FIG. 2 is a configuration diagram of the boiler in which the present invention is implemented. The upper part of FIG. 1 shows the combustion command of the boiler, the middle part shows the fuel supply amount, and the lower part shows the combustion air supply amount. The boiler 1 performs three-position combustion control of high combustion, low combustion, and stop, supplies fuel to the combustion device 4 through the fuel supply path provided with the fuel supply amount adjusting device 7, and operates the blower 2. Thus, combustion air is supplied to the combustion device 4. A damper device 3 is provided in the air passage that sends combustion air from the blower 2 to the combustion device 4, and the amount of air sent to the combustion device 4 is adjusted by changing the flow passage area of the air passage by the damper device 3.

  A fuel supply amount adjusting device 7 that adjusts the fuel supply amount supplied to the combustion device 4 adjusts the fuel supply amount in two stages, that is, a high combustion fuel supply amount and a low combustion fuel supply amount during combustion. The damper device 3 that adjusts the amount of combustion air supplied to the combustion device 4 also adjusts the amount of combustion air supplied in two stages during combustion, that is, a high combustion air supply amount and a low combustion air supply amount. The supply amount of fuel and combustion air is adjusted according to the combustion amount. When high combustion, high combustion fuel amount and high combustion air amount, when low combustion, low combustion fuel amount and low combustion air Supply quantity.

  The boiler 1 is provided with a steam pressure detection device 5 that detects the generated steam pressure value, and the boiler is operated based on the steam pressure value detected by the steam pressure detection device 5. When a single boiler is installed, the steam pressure value detected by the steam pressure detection device 5 is sent to the operation control device 6. If the steam pressure value sent from the steam pressure detection device 5 is equal to or lower than the lower limit value of the pressure adjustment range, the operation control device 6 outputs a combustion request and starts combustion of the boiler. At the time of combustion, the amount of combustion is adjusted by high combustion and low combustion according to the steam pressure value, and by performing combustion, the water pipe in the boiler is heated to supply steam. When the steam pressure value rises due to the steam supply and exceeds the upper limit value of the pressure adjustment range, the operation control device 6 outputs a standby request and stops combustion of the boiler.

  In the case of multi-can installation where a plurality of boilers are installed, a number control device (not shown) is provided, and the operation of each boiler is performed based on a command from the number control device. The steam pressure detecting device 5 is provided in a steam collecting portion that collects the steam of each boiler, and sends the steam pressure value detected by the steam pressure detecting device 5 to the unit control device. The number control device determines the combustion amount of the boiler based on the steam pressure value, outputs a combustion request to the required number of boilers, performs combustion, and outputs a standby request to the boiler that does not require combustion.

  In a boiler in which the fuel supply amount and the combustion air supply amount are adjusted, it is necessary to supply an appropriate amount of fuel and combustion air in order to perform stable combustion. If the balance between the fuel supply amount and the air supply amount is lost, the combustion state will deteriorate and harmful substances will be generated, noise will be generated due to expansion and contraction of the flame, and flame will be caused by excessive air It is very important to maintain the proper ratio of fuel to air, since a fire that blows out may occur. The fuel supply amount adjusting device 7 that increases and decreases the fuel supply amount adjusts the fuel supply amount by opening and closing an electromagnetic valve provided in the fuel supply path. Since the electromagnetic valve can be opened and closed instantaneously, The time required to increase or decrease the supply amount is very short.

  The damper device 3 that increases and decreases the supply amount of combustion air moves the position of the blades by rotating a damper motor connected to the damper shaft, thereby increasing or decreasing the flow passage area of the air passage. The amount cannot be changed instantaneously like opening and closing of a solenoid valve, and a certain amount of time is required. As a means for adjusting the combustion air supply amount, an inverter device is provided in the blower 2, and the rotational speed of the blower is changed by changing the power supply frequency of the blower 2, thereby increasing or decreasing the combustion air supply amount. Things are also done. However, also in this case, it is impossible to change the blower rotation speed instantaneously, and it takes time to change the combustion air supply amount.

  Therefore, when the combustion command changes from low combustion to high combustion or from high combustion to low combustion, if the change in the fuel supply amount and the change in the combustion air supply amount are started simultaneously, the fuel supply amount will change. However, the supply amount of combustion air hardly changes, and the balance between the supply amount of fuel and the supply amount of combustion air is lost. Therefore, when the combustion amount is changed, the change in the combustion air supply amount is started first, and when the change in the combustion air supply amount has progressed to some extent, the fuel supply amount is changed. And the balance of combustion air supply is kept from breaking. Specifically, a setting value for increasing the fuel supply amount and a setting value for decreasing the fuel supply amount are set between the low combustion air supply amount setting value and the high combustion air supply amount setting value. When the air supply amount increases to the set value for increasing the fuel supply amount, the fuel supply amount increases. When the combustion amount decreases, the fuel supply amount decreases when the air supply amount decreases to the set value for decreasing the fuel supply amount. The set value for increasing the fuel supply amount and the set value for decreasing the fuel supply amount are different values, and the set value for decreasing the fuel amount is set higher than the set value for increasing the fuel amount.

  The operation status of the boiler will be described with reference to FIG. In FIG. 1, the combustion command is indicated as H if the combustion amount determined from the steam pressure value is high, and the combustion command is indicated as L if the combustion is low. The first half of FIG. 1 is the case where there is no cancellation of the combustion amount change, and the second half is the case where there is a cancellation of the combustion amount change. In FIG. 1, the combustion command is low combustion (L), the fuel supply amount starts from a state for low combustion, and the air supply amount also starts from a state for low combustion. When the combustion amount determined from the steam pressure value at time a becomes high combustion and a high combustion (H) combustion command is output, the operation control device 6 first starts increasing the air supply amount. The opening degree of the damper device 3 is increased aiming at a set value for high combustion, and when it is detected that the blade position of the damper device has reached the set value for increasing the fuel supply amount at time b, the fuel supply amount is increased. . The change of the fuel supply amount by the fuel supply amount adjusting device 7 is completed in a very short time, and when the fuel supply amount is for high combustion, combustion at high combustion starts. At this point, the amount of air is not intended for high combustion, so the amount of air supply will be slightly short. However, the amount of air has increased to the fuel increase set value, so that the combustion state becomes abnormal. It is not balanced and can burn properly. The increase in the air supply amount continues after time b, the air supply amount approaches a more appropriate amount, and the increase in the air supply amount stops when the air supply amount for high combustion is reached.

  Thereafter, the combustion command is low combustion at time c, and the reduction of the combustion air supply amount starts from time c. When the air supply amount reaches the fuel decrease set value at time d, the fuel supply amount is decreased and combustion at low combustion is started. Also in this case, since the fuel supply amount is decreased after the air supply amount reaches the set value of the fuel supply amount decrease, proper combustion can be continued. Thereafter, the air supply amount continues to decrease until the air supply amount becomes a low combustion supply amount. Thus, at the time of changing the combustion amount, if the fuel supply amount is changed in a state where the air supply amount is changed to some extent, the combustion amount can be changed without greatly degrading the balance between the air supply amount and the fuel supply amount.

  When the combustion command becomes high combustion at time e, an increase in the air supply amount is started in the same manner as at time a, and when the air supply amount reaches the set value for fuel increase, the fuel supply amount is increased. However, in this change in the combustion amount, the combustion command becomes low combustion at time f, which is immediately after the air supply amount reaches the set value for increasing combustion and starts high combustion. When the change to the high combustion is canceled in the middle of the change from the low combustion to the high combustion and the low combustion is returned, the movement differs depending on the state of the air supply amount.

  If the air supply amount when the combustion command becomes low combustion is lower than the set value for reducing the fuel amount, the increase in the air supply amount is continued. When the air supply amount reaches the set value for reducing the fuel amount, the fuel supply amount is changed to low combustion, and the reduction of the air supply amount is started. If the air supply amount when the combustion command becomes low combustion is higher than the fuel amount reduction set value, start reducing the air supply amount immediately and the air supply amount will decrease. When the set value is reached, the fuel supply amount is changed to low combustion.

  The same applies to the case where the change to low combustion is canceled during the change to low combustion and returns to high combustion, and the movement varies depending on the state of the air supply amount. If the air supply amount when the combustion command becomes high combustion is higher than the set value for increasing the fuel amount, the air supply amount continues to decrease. When the air supply amount reaches the set value for increasing the fuel amount, the fuel supply amount is changed to high combustion and the increase in the air supply amount is started. If the air supply amount when the combustion command becomes high combustion is lower than the fuel amount increase set value, start increasing the air supply amount immediately and the air supply amount will increase. When the set value is reached, the fuel supply amount is changed to high combustion.

  In FIG. 1, since the air supply amount is lower than the set value for decreasing the fuel supply amount at time f, the increase in the air supply amount continues, and the time when the air supply amount reaches the set value for decreasing the fuel supply amount. At g, the fuel supply amount is changed to low combustion and the air supply amount starts to decrease.

  Thereafter, in FIG. 1, the combustion command becomes high combustion at time h. In this case, since the high combustion is achieved in the middle of the change from the high combustion to the low combustion, the change to the low combustion is cancelled. Since the air supply amount is lower than the fuel increase set value at the time h, the air supply amount starts increasing immediately at the time h. At time i when the air supply amount reaches the set value for increasing fuel, the fuel supply amount is set for high combustion, and thereafter, the air supply amount is increased until the set value for high combustion is reached.

  FIG. 3 summarizes and describes at which point the reversal of the air supply amount change direction is performed when the combustion amount change is canceled. In the first half of FIG. 3, when the combustion command was switched from low combustion to high combustion and the air supply amount was increasing, the combustion amount was returned to low combustion (cancellation change to high combustion) was output. There are cases. If the output of the combustion command to return the combustion amount is before reaching the set value for reducing the fuel supply amount, the air supply amount is not immediately reversed in the decreasing direction, but until the set value for reducing the fuel supply amount is reached. The increase in the air supply amount is continued and the reversal of the direction of changing the air supply amount is delayed. Further, if the output of the combustion command for returning the combustion amount has reached the set value for reducing the fuel supply amount, the reversal of the air supply change direction to the decrease side is immediately executed.

  The second half of FIG. 3 shows that when the combustion command is switched from high combustion to low combustion and the air supply amount is decreasing, the combustion amount is returned to high combustion (cancellation change to low combustion) and the output of the combustion command is present. There is a case. In this case as well, if the output of the combustion command for returning the combustion amount is before the fuel supply amount increase set value is reached, the air supply amount continues to decrease until the fuel supply amount increase set value is reached. Reversing the direction of air supply change is delayed. Further, if the output of the combustion command for returning the combustion amount has reached the set value for increasing the fuel supply amount, the air supply change direction is immediately reversed to the increase side.

  By doing so, since the fuel supply amount is changed when the supply amount of the combustion air reaches a predetermined amount, it is possible to prevent the balance between the air supply amount and the fuel supply amount from being greatly disrupted, It is possible to prevent the occurrence of a combustion failure or the like when canceling the combustion amount change.

1 boiler
2 Blower
3 Damper device
4 Combustion device
5 Steam pressure detector
6 Operation control device
7 Fuel supply amount adjustment device

Claims (2)

  A boiler in which the fuel supply amount and the combustion air supply amount are set in stages, and the combustion amount is increased or decreased by increasing or decreasing the fuel supply amount and the combustion air supply amount. When changing the combustion air supply amount, the combustion air supply amount is started first, and when the combustion air supply amount reaches the fuel supply amount change set value, the fuel supply amount is changed. In a change boiler, when canceling the increase in the combustion amount while performing the operation to increase the combustion amount based on the combustion command for increasing the combustion amount, if the air supply amount has not reached the set value for decreasing the fuel supply amount Continue the control in the direction of increasing the combustion amount until the air supply amount reaches the set value for decreasing the fuel supply amount, and after the air supply amount reaches the set value for decreasing the fuel supply amount, The reduction of air supply shall start and When canceling the reduction of the combustion amount while performing the operation to reduce the combustion amount based on the combustion command for reducing the amount of fuel, if the air supply amount is before reaching the set value of the fuel supply amount increase, the air supply amount is Continue control in the direction of decreasing the combustion amount until the fuel supply amount increase set value is reached. After the air supply amount reaches the fuel supply amount increase set value, the fuel supply amount increases and the combustion air supply amount increases. A combustion amount change boiler characterized by starting the operation.   In the combustion amount changing boiler according to claim 1, when canceling the increase in the combustion amount in the middle of performing the operation for increasing the combustion amount based on the combustion command for increasing the combustion amount, the air supply amount is reduced in the fuel supply amount. If there is a combustion command output that cancels the increase in the combustion amount after reaching the set value, control is started in the direction to decrease the air supply amount without delaying the delay. If the fuel supply amount is reduced when the set value for the supply amount reduction is reached, and the cancellation of the combustion amount is canceled during the operation to reduce the combustion amount based on the combustion amount reduction command, the air supply amount If there is a combustion command output that cancels the decrease in the combustion amount after reaching the set value for the increase in the fuel supply amount, start the control in the direction to increase the air supply amount without leaving the delay time, Air supply is fuel supply Combustion amount changing boiler, characterized in that after reaching the increased set value is performed in an increase in fuel supply amount.

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