JP4057491B2 - Combustion device for increasing / decreasing fan rotation speed and ventilation path flow area - Google Patents

Description

  The present invention relates to a combustion apparatus that increases and decreases the rotational speed of a blower and the area of a ventilation passage.

  For example, in the case of a boiler, a combustion device having a burner and a blower is provided, and combustion is performed while sending combustion air to the burner by the blower. When adjusting the combustion amount such as high combustion / low combustion / stop, the combustion amount is adjusted by increasing / decreasing the combustion air supply amount and the fuel supply amount. As a means for adjusting the combustion air supply amount, rotation speed adjusting means such as an inverter device is provided in the blower, and the rotation speed of the blower is increased or decreased.

  By adjusting the rotational speed of the blower, it is possible to supply the amount of combustion air that matches the amount of combustion, but in the case of low combustion where the rotational speed of the blower is reduced to reduce the air volume, smoke and vibration combustion are Combustion may become unstable. This is because the static pressure of the combustion air is reduced by reducing the amount of air generated by reducing the rotational speed of the blower, and this proves that the combustion is unstable.

Therefore, as described in Japanese Patent Application Laid-Open No. 2002-195552, the static pressure of the combustion air is kept high by reducing the flow passage area of the ventilation path during low combustion when the rotational speed of the blower is reduced, and during low combustion. It has also been proposed to prevent the combustion from becoming unstable.
By doing in this way, it became possible to ensure a static pressure even at the time of low combustion where the supply amount of combustion air decreases, and to prevent the combustion from becoming unstable. However, there remains a problem that combustion may become unstable when the combustion amount is shifted from low combustion to high combustion or when high combustion is shifted to low combustion.
JP 2002-195552 A

  The problem to be solved by the present invention is to prevent combustion from becoming unstable when changing the combustion amount to increase the combustion amount or decrease the combustion amount.

  Combustion device having a burner and a blower, a fuel supply amount adjustment means for increasing and decreasing the fuel supply amount, a rotation speed adjustment means for increasing and decreasing the rotation speed of the blower, and a flow passage area of the ventilation path connecting the burner and the blower When a flow passage area adjusting means is provided and the fuel supply amount is reduced to reduce the combustion amount, the rotational speed of the blower and the flow passage area of the ventilation path are reduced, the fuel supply amount is increased and the combustion amount is reduced. If the combustion amount is changed in a combustion device that increases or decreases the rotational speed of the blower and the flow path area of the ventilation path, the rotation speed of the blower is changed. Change the blower rotational speed and air flow so that the static pressure of the combustion air that changes due to the relationship between the "air volume" that changes due to the change in speed and the "flow area" that changes due to the flow area adjustment means does not decrease. Road surface Determine the order of the change.

  By carrying out the present invention, there is an advantage that combustion can be prevented from becoming unstable when the combustion amount is changed to increase the combustion amount or decrease the combustion amount.

  FIG. 1 is a time chart showing the combustion state and air volume adjustment status of the first embodiment of the apparatus of the present invention, and FIG. 2 is a time chart showing the combustion state and air volume adjustment status of the second embodiment of the apparatus of the present invention. FIG. 3 is a block diagram showing an outline of a boiler embodying the present invention, and FIGS. 4 and 5 are time charts showing a combustion state and a state of air volume adjustment in a conventional example. 1 and 4 show that when the time required to change the rotational speed of the blower is longer than the time required to change the flow passage area of the ventilation path when changing the combustion amount, FIG. 2 and FIG. This is a case where the time required to change the flow passage area of the ventilation path when changing the amount is longer than the time required to change the rotation speed of the blower.

  The boiler 1 is provided with a burner 2 at the top, and fuel is supplied through two fuel supply pipes 3. The fuel supply pipe 3 is provided with a first solenoid valve 4 and a second solenoid valve 5, and the fuel supply amount is adjusted by opening and closing the first solenoid valve 4 and the second solenoid valve 5. Also, a blower 6 is provided, and the combustion air is supplied from the blower 6 to the burner 2 by connecting the blower 6 and the burner 2 through the air passage 7. The combustion amount is controlled at three positions of high combustion, low combustion, and stop, and the combustion amount is changed by adjusting the fuel supply amount and the combustion air supply amount.

  The blower 6 is connected to an inverter device 8 which is a rotation speed adjusting means, and the inverter device 8 is set with a high combustion frequency and a low combustion frequency. The inverter device 8 adjusts the rotational speed of the blower 6 by changing the power supply frequency to the blower 6. A damper device 9 which is a flow path area adjusting means is provided in the middle of the ventilation path 7 connecting the blower 6 and the burner 2, and the opening degree of the high combustion position and the low combustion position is set in the damper device 9. The damper device 9 adjusts the flow path area of the ventilation path 7 by changing the opening degree. Operation control of the boiler is performed by the control device 10, and the control device 10 sends commands to each of the burner 2, the first electromagnetic valve 4, the second electromagnetic valve 5, the inverter device 8, and the damper device 9.

  When combustion is performed at low combustion, combustion is performed with a fuel supply amount for low combustion and a combustion air supply amount for low combustion, and when combustion is performed at high combustion, a fuel supply amount for high combustion and a fuel supply for high combustion are used. Combustion with combustion air supply. Low combustion and high combustion are set at a ratio of about 1: 2, and high combustion supplies about twice as much fuel and combustion air as low combustion. The fuel supply amount is adjusted by stopping the fuel supply when both the first solenoid valve 4 and the second solenoid valve 5 are closed, and by opening only the first solenoid valve 4, the fuel amount for low combustion, the first solenoid valve When both 4 and the second solenoid valve 5 are opened, a fuel amount for high combustion is supplied. The amount of combustion air is adjusted by the inverter device 8 and the damper device 9. In the case of low combustion, the inverter device 8 sets the rotational speed of the blower 6 to a low combustion speed, the damper device 9 sets the flow passage area of the ventilation path 7 to a low combustion opening, and in the case of high combustion, the inverter device 8 The rotational speed of the blower 6 is the high combustion speed, and the damper device 9 has the flow passage area of the ventilation path 7 as the high combustion opening.

  Since the adjustment of the fuel supply amount is controlled by opening and closing the first electromagnetic valve 4 and the second electromagnetic valve 5, the fuel supply amount can be changed instantaneously. However, the adjustment of the combustion air amount is performed by changing the rotational speed by changing the power frequency supplied to the blower 6 and changing the damper opening by driving the motor. Necessary. Therefore, when changing the combustion amount, start changing the combustion air supply amount first and change the fuel supply amount when the operating frequency of the blower reaches the preset value for changing the fuel supply amount. Like to do.

  First, the change state of the combustion amount and the combustion air supply amount will be described with reference to FIG. 1 which is the first embodiment. In the first embodiment, when the amount of combustion is changed, the time required to change the rotational speed of the blower is longer than the time required to change the flow passage area of the ventilation path, and low combustion When the combustion amount is changed from high to high combustion, the rotation speed of the blower is started first, and the damper opening is changed after the set time has elapsed.

  The figure starts from a state where the fuel supply amount is the low combustion supply amount, the blower rotational speed is the low combustion speed, and the damper opening is the low combustion opening. When changing the combustion amount from low combustion to high combustion, the control device 10 first outputs a command to the inverter device 8 to change from the low combustion frequency to the high combustion frequency, and outputs the output to the inverter device 8. The detection of the elapsed time from when it was performed is started. The inverter device 8 that has received the frequency change command increases the rotational speed of the blower 6 from the low combustion speed to the high combustion speed by increasing the frequency of the power source supplied to the blower 6. When the rotational speed of the blower 6 is changed, it cannot be changed instantaneously as in the case of changing the fuel supply amount, and the rotational speed of the blower increases gently. When the rotational speed of the blower 6 is increased, the air volume of the combustion air sent from the blower 6 to the burner 2 is increased.

  When the elapsed time since the frequency increase is output to the inverter device 8 reaches a predetermined time T, the control device 10 opens the high combustion opening from the low combustion opening to the damper device 9. Outputs a command to change the channel area to the desired degree. When the opening degree of the damper device 9 is increased, a certain amount of time is required, but the opening degree changing speed is faster than when the rotation speed of the blower is changed.

  Since the output to the damper device 9 is performed after a predetermined time T has elapsed since the output to the inverter device 8 has been performed, the amount of air flow that has not started to output the opening to the damper device 9 when the air volume is changed. It can be divided into a first period of change and a second stage of air volume change after the start of output of opening increase to the damper device 9. In the case of the first air change period, the flow area of the ventilation path 7 does not change, and the air volume increases due to the increase in the rotational speed of the blower, so that the static pressure at the primary side of the damper device increases. In the latter stage of the air volume change, the air volume continues to increase due to the increase in the rotational speed of the blower. However, the increase in the flow passage area due to the increase in the opening degree of the damper device 9 is more rapid than the increase in the air volume. The static pressure on the side part decreases. In this case, since the static pressure is increased more than usual by the increase in the air volume in the first stage of the air volume change, the static pressure does not greatly decrease when the combustion volume is changed, and the combustion does not become unstable.

  When detecting that the operating frequency of the blower has increased to a preset value for changing the fuel supply amount, the control device 10 opens the second solenoid valve 5 to increase the fuel supply amount and starts high combustion. To do. Thereafter, when the combustion amount is changed from high combustion to low combustion, the control device 10 outputs a command for changing from the high combustion frequency to the low combustion frequency to the inverter device 8, and at the same time to the damper device 9. On the other hand, a command for changing the flow path area from the high combustion opening to the low combustion opening is output. If the blower rotation speed is reduced and the damper opening is reduced at the same time, the change speed is faster when the damper opening is reduced. The effect of reducing the damper opening is greater than the decrease in air volume due to the air flow, and the static pressure at the primary side of the damper device increases. When the damper opening becomes the low combustion opening, the static pressure that has been increased decreases since the air flow is only reduced by the decrease in the rotational speed of the blower thereafter. When the operating frequency of the blower is reduced to the preset value for changing the fuel supply amount, the control device 10 closes the second electromagnetic valve 5 to reduce the fuel supply amount and starts low combustion.

  When the combustion amount is decreased, as in the case where the combustion amount is increased, the inverter device 8 is first output to change from the high combustion frequency to the low combustion frequency, and the damper device after a predetermined time has elapsed. When an output that decreases from an opening for high combustion to an opening for low combustion is applied to 9, the air volume decreases due to a decrease in the rotational speed of the blower while the flow passage area of the ventilation path 7 is not decreased. become. In this case, since the static pressure of the damper device primary side portion decreases, there is a risk that the combustion becomes unstable. For this reason, when the combustion amount is reduced, the change of the blower rotational speed and the change of the damper opening degree are performed simultaneously.

  Conventionally, even when the time required to change the rotational speed of the blower when changing the combustion amount is longer than the time required to change the flow passage area of the ventilation path, as shown in FIG. As shown, when the amount of combustion increases, the output of the blower rotation speed change and the output of the damper opening change are performed simultaneously. In this case, since the increase in the flow path area due to the increase in the opening degree of the damper device is more rapid than the increase in the air volume due to the increase in the rotational speed of the blower, the static pressure at the primary side portion of the damper device is to be reduced. In the present invention, in order to prevent the static pressure of the combustion air from decreasing at the time of combustion transition, the output of increasing the rotational speed of the blower is performed first, and then the output of increasing the opening degree of the damper device is performed. It is possible to prevent the combustion from becoming unstable.

  In this embodiment, when changing the combustion amount from low combustion to high combustion, the change of the blower rotational speed is started first, and the damper opening is changed after the set time T has elapsed. It is also possible to detect the frequency and output the change of the damper opening after the operating frequency has increased to the set value for changing the air volume, and the pressure in the burner part or the furnace, or the burner part pressure and the furnace A change in the damper opening may be output after the pressure differential pressure or the like is detected and the pressure increases to a set value.

  Next, the second embodiment will be described with reference to FIG. In the second embodiment, when the amount of combustion is changed, the time required to change the flow passage area of the ventilation path is longer than the time required to change the rotational speed of the blower, and high combustion When changing the combustion amount from low to low combustion, the damper opening change is started first, and when the damper opening decreases to the preset value for changing the air flow, the operation to change the blower rotation speed is performed. It is.

  The figure starts from a state where the fuel supply amount is the low combustion supply amount, the blower rotational speed is the low combustion speed, and the damper opening is the low combustion opening. When changing the combustion amount from low combustion to high combustion, the control device 10 outputs a command to the inverter device 8 to change from the low combustion frequency to the high combustion frequency, and at the same time to the damper device 9. A command for changing the flow path area from the low combustion opening to the high combustion opening is output. If the fan rotation speed is increased and the damper opening is increased at the same time, the change speed is faster when the fan rotation speed is increased. The effect of the increase in air volume due to the increase in the rotational speed of the blower is greater than the increase, and the static pressure in the burner portion is increasing. When the rotational speed of the blower becomes a high combustion speed, only the damper opening is increased thereafter, and the static pressure of the damper device primary side portion decreases. When the operating frequency of the blower increases to a preset value for changing the fuel supply amount, the control device 10 opens the second electromagnetic valve 5 to increase the fuel supply amount and starts high combustion.

  Thereafter, when the combustion amount is changed from high combustion to low combustion, the control device 10 first outputs a command to the damper device 9 to change from the high combustion opening to the low combustion opening. The damper device 9 that has received the command to change the opening degree reduces the flow passage area of the ventilation path 7 by reducing the opening degree from the high combustion opening degree to the low combustion opening degree. The state of change in the opening degree of the damper device 9 is detected, and when the opening degree of the damper device 9 decreases to a preset value for changing the air volume, the control device 10 causes the inverter device 8 to perform high combustion. Outputs a command to decrease from the frequency to the low combustion frequency.

  When the combustion amount is changed from high combustion to low combustion, since the output to the inverter device 8 is performed after the output to the damper device 9, the speed reduction output to the inverter device 8 is output when the air volume is changed. It can be divided into an air flow change first period that has not started and an air flow change later period after the start of output of speed reduction to the inverter device 8. In the case of the air volume change first period, the rotational speed of the blower 6 does not change, and the flow passage area of the ventilation path 7 is reduced by reducing the opening degree of the damper device 9, so the static pressure of the damper device primary side portion increases. In the latter stage of the air flow change, the flow passage area of the ventilation passage 7 continues to decrease due to the decrease in the opening of the damper device 9, but the air flow decrease due to the decrease in the rotational speed of the blower 6 is more rapid than the flow passage area decrease. The static pressure at the primary side of the damper device once increased decreases. In this case, since the static pressure is increased more than usual by reducing the opening in the first stage of air volume change, the static pressure does not greatly decrease when the combustion volume is changed, and combustion does not become unstable.

  Conventionally, even when the time required to change the flow passage area of the ventilation path when changing the combustion amount is longer than the time required to change the rotation speed of the blower, it is shown in FIG. As shown in the figure, when the combustion amount is reduced, the output of the fan rotation speed change and the output of the damper opening change are simultaneously performed. In this case, the static pressure at the primary side portion of the damper device is reduced because the air volume reduction due to the reduction in the rotational speed of the blower is more rapid than the flow path area reduction due to the reduction in the opening degree of the damper device. In the present invention, in order to prevent the static pressure of the combustion air from decreasing at the time of combustion transition, the output of reducing the opening degree of the damper device 9 is performed first, and then the output of decreasing the rotational speed of the blower is performed. It is possible to prevent the combustion from becoming unstable when the amount is changed.

  In this embodiment, when the combustion amount is changed from high combustion to low combustion, the change of the damper opening is started first, and when the damper opening decreases to the preset value for changing the air flow, Although the rotation speed is changed, the elapsed time after the change of the damper opening is output may be detected, and the change of the blower rotation speed may be output after the set time elapses. Alternatively, the pressure in the furnace, the differential pressure between the burner partial pressure and the furnace pressure, or the like may be detected, and the change in the damper opening may be output after the pressure has increased to a set value.

The time chart which showed the combustion state of the 1st Example of this invention apparatus, and the condition of air volume adjustment The time chart which showed the combustion state of the 2nd Example of this invention apparatus, and the condition of air volume adjustment The block diagram which showed the outline | summary of the boiler which is implementing this invention Time chart showing the state of combustion and air flow adjustment in the conventional example Time chart showing the state of combustion and air flow adjustment in the conventional example

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Boiler 2 Burner 3 Fuel supply piping 4 1st solenoid valve 5 2nd solenoid valve 6 Blower 7 Ventilation path 8 Inverter apparatus 9 Damper apparatus 10 Control apparatus

Claims (5)

Combustion device having a burner and a blower, a fuel supply amount adjustment means for increasing and decreasing the fuel supply amount, a rotation speed adjustment means for increasing and decreasing the rotation speed of the blower, and a flow passage area of the ventilation path connecting the burner and the blower When a flow passage area adjusting means is provided and the fuel supply amount is reduced to reduce the combustion amount, the rotational speed of the blower and the flow passage area of the ventilation path are reduced, the fuel supply amount is increased and the combustion amount is reduced. If the combustion amount is changed in a combustion device that increases or decreases the rotational speed of the blower and the flow path area of the ventilation path, the rotation speed of the blower is changed. Change the blower rotational speed and air flow so that the static pressure of the combustion air that changes due to the relationship between the "air volume" that changes due to the change in speed and the "flow area" that changes due to the flow area adjustment means does not decrease. Road surface Combustion apparatus which performs increase or decrease of the air passage flow area and blower speed, characterized by defining an order of the changes. In the combustion apparatus which increases / decreases the blower rotational speed and the ventilation passage flow path area according to claim 1, when increasing the combustion amount, the rotational speed increase is first output to the blower rotational speed adjusting means, A combustion apparatus for performing increase / decrease in fan rotational speed and ventilation path flow path area, characterized in that control is performed to delay the output of flow path area increase with respect to the area adjusting means. The combustion apparatus for increasing or decreasing the blower rotation speed and the ventilation passage flow passage area according to claim 2, wherein the time required to change the rotation speed of the blower when changing the combustion amount is determined by the flow passage area adjusting means. If the combustion device is longer than the time required to change the passage area of the passage, when increasing the combustion amount, first output the rotation speed increase to the blower rotation speed adjusting means, A combustion apparatus for performing increase / decrease in fan rotation speed and ventilation path flow path area, characterized in that control is performed to delay an output of flow path area increase with respect to the road area adjustment means. In the combustion apparatus which increases / decreases the blower rotation speed and the ventilation passage flow passage area according to claim 1, when the combustion amount is reduced, the flow passage area reduction means is first outputted to the flow passage area adjusting means, and the blower is provided. A combustion apparatus for performing increase / decrease in fan rotation speed and ventilation path flow path area, characterized in that control for delaying output of rotation speed reduction to rotation speed adjusting means is performed. 5. The combustion apparatus for increasing or decreasing the blower rotational speed and the ventilation passage flow passage area according to claim 4, wherein the time required for changing the flow passage area of the ventilation passage by the flow passage area adjusting means when changing the combustion amount. If the combustion device is longer than the time required to change the rotational speed of the blower, when reducing the combustion amount, first output the flow area reduction to the flow area adjustment means, A combustion apparatus for performing increase / decrease in fan rotation speed and ventilation path passage area, characterized in that control is performed to delay the output of rotation speed reduction with respect to the fan rotation speed adjusting means.

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