JP4238819B2 - Combustion equipment - Google Patents

Description

  The present invention relates to a combustion apparatus provided with a blower that adjusts the air volume by controlling the rotational speed of a fan.

  In a combustion apparatus such as a boiler that performs combustion control in a plurality of combustion states set such as three positions of high combustion, low combustion, and stop, the amount of air required for each combustion state varies. . Therefore, an amount of combustion air required in each combustion state is supplied by connecting an inverter to an electric motor including a fan constituting a blower and increasing or decreasing the fan rotation speed.

  However, in such a combustion apparatus, it takes a certain amount of time until the necessary air volume is reached after the blower starts changing the fan rotation speed, whereas the change in the fuel supply amount is instantaneously performed by switching the valve. Therefore, there is a problem in that the ratio between the fuel and the amount of air (hereinafter referred to as “air-fuel ratio”) collapses and combustion failure occurs.

Therefore, a combustion apparatus disclosed in the following Patent Document 1 has been proposed. The combustion apparatus described in Patent Document 1 includes two electromagnetic valves that allow a certain amount of fuel to pass. As shown in FIG. 5, in low combustion, only the first electromagnetic valve is opened to supply fuel. When the combustion process is changed from low combustion to high combustion, first, the blower starts to increase the fan rotation speed and opens the second electromagnetic valve after a predetermined time Ta has elapsed from the start of the increase. Similarly, when the combustion process is changed from high combustion to low combustion, the blower device starts to decrease the rotation speed of the fan and is configured to close the second solenoid valve after a predetermined time has elapsed from the start of the decrease. ing. That is, the combustion apparatus described in Patent Document 1 attempts to suppress the collapse of the air-fuel ratio as much as possible by changing the fuel supply amount by delaying the opening and closing of the second electromagnetic valve for a predetermined time from the start of changing the fan rotation speed. To do.
JP-A-9-210349

  However, in the combustion apparatus described in Patent Document 1, the change in the fuel supply amount performed between the low combustion process and the high combustion process is a two-stage change performed only by opening and closing the second electromagnetic valve. For this reason, the air-fuel ratio largely collapses from the start of change of the fan rotation speed until the second electromagnetic valve is opened and closed, causing combustion failure.

  The problem to be solved by the present invention is to provide a combustion apparatus that can always maintain a desirable air-fuel ratio and can perform stable combustion even if the fan rotation speed of the blower is changed.

The present invention has been made to solve the above-mentioned problems, and the invention according to claim 1 is characterized in that the rotational speed of the fan is set to at least a high combustion rotational speed or a rotational speed lower than the high combustion rotational speed. A blower that adjusts the air volume by controlling to a low rotational speed for combustion, and a fuel supply device that changes the fuel supply amount steplessly. While the rotation speed of the fan is changed, the fuel supply device changes the fuel supply amount steplessly so as to correspond to the change in the rotation speed of the fan. A first fuel valve that is opened in the combustion process; a second fuel valve that is opened in the high combustion process; a flow adjustment valve that changes the fuel supply amount steplessly; and the flow adjustment valve The And a transition valve that switches whether or not excess fuel is supplied, and when the low combustion process shifts to the high combustion process, the blower starts changing the rotation speed of the fan to a high combustion rotation speed. In addition, the transition valve is opened, and the flow control valve increases the fuel supply steplessly so as to correspond to the increase in the rotational speed of the fan, and from the time when the transition valve is opened. After a predetermined time has elapsed, when the transition valve is closed and the second fuel valve is opened, and the transition from the high combustion process to the low combustion process is performed, the blower rotates the rotational speed of the fan. To the low combustion rotational speed, the transition valve is opened, the second fuel valve is closed, and the flow control valve is adapted to respond to a decrease in the rotational speed of the fan. Step by step fuel supply Small Toe, after a predetermined time has elapsed from the time when the transition valve is opened, the transition valve is characterized by being a closed state.

According to the first aspect of the present invention, a desirable air-fuel ratio can be maintained even at the time of transition of the rotational speed of the fan, stable combustion can be performed, and in addition, the flow path resulting from the flow control valve It is possible to effectively prevent clogging, etc., and to enable stable operation with few failures.

According to a second aspect of the present invention, there is provided a blower that adjusts the air volume by controlling the rotational speed of the fan to at least a high combustion rotational speed or a low combustion rotational speed lower than the high combustion rotational speed. And a fuel supply device that changes the fuel supply amount steplessly. When changing the combustion process, the blower device changes the rotational speed of the fan, while the fuel supply device In the combustion apparatus that changes the fuel supply amount steplessly so as to correspond to the change in the rotational speed of the fan, the fuel supply apparatus includes a first fuel valve that is opened in a low combustion process, and a high combustion A second fuel valve that is opened in the process, a flow rate adjustment valve that changes the fuel supply amount in a stepless manner, and a transition valve that switches whether or not to supply fuel that passes through the flow rate adjustment valve. Low When shifting from the firing process to the high combustion process, the blower device starts changing the rotational speed of the fan to the high combustion rotational speed, the transition valve is opened, and the flow rate adjustment valve is The fuel supply amount is increased steplessly so as to correspond to the increase in the rotation speed of the fan, and the transition valve and the first fuel valve are closed after a predetermined time has elapsed since the transition valve was opened. The second fuel valve is opened, and when the high combustion process is shifted to the low combustion process, the blower starts changing the rotation speed of the fan to the low combustion rotation speed. In addition, the first fuel valve and the transition valve are opened, the second fuel valve is closed, and the fuel supply amount is adjusted so that the flow rate adjustment valve corresponds to a decrease in the rotational speed of the fan. Decrease steplessly, the transition valve opens After a predetermined time has elapsed from time point, the transition valve is characterized by being a closed state.

According to the second aspect of the present invention, a desirable air-fuel ratio can be maintained even at the time of transition of the rotational speed of the fan, stable combustion can be performed, and the flow path resulting from the flow rate adjustment valve It is possible to effectively prevent clogging, etc., and to enable stable operation with few failures. Furthermore, when a high combustion nozzle and a low combustion nozzle are provided, the fuel sprayed into the combustion chamber from the two nozzles does not interfere with each other and cause poor combustion, realizing better combustion. can do.

Further, the invention according to claim 3 is characterized in that, in addition to the constituent elements according to claim 1 or claim 2, at least the high combustion air volume position, or the low combustion air volume whose opening is smaller than the high combustion air volume position. It is provided with a damper that controls the air volume from the blower by being disposed at a position, and at the time of transition to the combustion process, the fuel supply amount is adjusted so as to correspond to the change in the rotational speed of the fan and the change in the opening of the damper It is characterized by stepless change .

According to the third aspect of the present invention, even when the damper is further provided, a desirable air-fuel ratio can be maintained even when the rotational speed of the fan is shifted, and stable combustion can be performed.

  According to the present invention, it is possible to provide a combustion apparatus that can maintain a desirable air-fuel ratio even when the fan rotation speed of the blower is changed and can realize stable combustion.

  Next, an embodiment of the present invention will be described. The present invention is used in a combustion apparatus that performs multi-position combustion control such as three-position combustion control that adjusts the combustion amount in three stages of high combustion, low combustion, and stop. The combustion apparatus of the present invention includes a blower that supplies combustion air to the combustion chamber. This blower device includes an electric motor including a fan and an air volume control device that is connected to the electric motor and controls the rotational speed of the fan. The air volume control device is not particularly limited, but an inverter is preferably used. The blower supplies three stages of air volume by increasing or decreasing the rotational speed of the fan to a high combustion rotational speed, an ignition rotational speed, and a low combustion rotational speed. The high combustion rotation speed and the ignition rotation speed are set to be higher than the low combustion rotation speed. For the sake of simplicity, this ignition rotation speed can also be used as the same rotation speed as the high combustion rotation speed. By the way, when employing multi-position combustion control other than three-position combustion control, other rotational speeds can be set in addition to these rotational speeds.

  First, in the first embodiment of the present invention, when changing the combustion process, the blower device changes the rotation speed of the fan, while the fuel supply device corresponds to the change in the rotation speed of the fan. Change the fuel supply steplessly. Here, the type of fuel is not particularly limited. The stepless change of the fuel supply amount corresponding to the change in the fan rotation speed means that the fuel supply amount is maintained so as to maintain a desired air-fuel ratio with respect to the air volume that increases or decreases with the change in the fan rotation speed. This means that the amount is changed steplessly, and is not limited to the case where the rotational speed of the fan increases or decreases in proportion to the elapsed time.

  Next, in the second embodiment of the present invention, when the low combustion process shifts to the high combustion process, the blower starts changing the rotation speed of the fan to the high combustion rotation speed, and The transition valve is opened, and the flow rate adjustment valve increases the fuel supply amount steplessly so as to correspond to the increase in the rotational speed of the fan, and after a predetermined time has elapsed since the transition valve was opened. When the transition valve is closed and the second fuel valve is opened, and the transition from the high combustion process to the low combustion process is performed, the blower device is used for low combustion with a low rotational speed of the fan. The change to the rotation speed is started, the transition valve is opened, the second fuel valve is closed, and the fuel supply amount is adjusted so that the flow rate adjustment valve corresponds to the decrease in the rotation speed of the fan. The transition valve is opened steplessly After a predetermined time has elapsed from time point, the transition valve is that is a closed state.

  Here, the first fuel valve and the second fuel valve are controlled by two operations of opening and closing, and allow a certain amount of fuel to pass through in the opened state. This second fuel valve is opened only in the high combustion process. The fuel supplied through the first fuel valve is set to a fuel supply amount necessary for the low combustion process. Further, the flow rate adjusting valve is configured to change the amount of fuel supplied passing through in a stepless manner. As this flow control valve, there is one that changes the fuel supply amount by steplessly adjusting the size of the flow path area, but the type of the valve is not particularly limited. The transition valve is controlled by two operations of opening and closing, and switches the presence or absence of supply of fuel passing through the flow rate adjusting valve. As described above, the second fuel valve that allows a constant amount of fuel to pass in the high combustion process is provided, and the flow rate adjustment valve is used only at the time of the transition of the fan rotation speed. Road clogging can be effectively prevented, and stable operation with few failures can be realized.

  Further, when the transition valve shifts from the low combustion process to the high combustion process, the air blower starts to change the rotation speed of the fan to the high combustion rotation speed and closes after a predetermined time has elapsed. Further, when shifting from the high combustion process to the low combustion process, the transition valve is opened when the blower starts changing the rotation speed of the fan to the low combustion rotation speed, and is closed after a predetermined time has elapsed. As a means for measuring the passage of the predetermined time, in addition to means for measuring time by a timer device, instead of the timer device, a wind pressure sensor for detecting the amount of air supplied by the air blower, an inverter outputs the electric motor. By using various sensors such as a flow rate sensor that detects the frequency signal that flows through the flow rate adjustment valve and a flow rate sensor that detects the amount of fuel that passes through the flow rate adjustment valve, the transition valve is closed when the detected value reaches the set value. Including means for enabling. By the way, the low combustion process and the high combustion process mean a process in a low combustion state and a process in a high combustion state, respectively.

  In the third embodiment of the present invention, when the low combustion process shifts to the high combustion process, the blower starts changing the rotational speed of the fan to the high combustion rotational speed, and the transition valve The valve is opened, and the flow rate adjustment valve increases the fuel supply amount steplessly so as to correspond to the increase in the rotational speed of the fan, and after the predetermined time has elapsed from the time when the transition valve is opened, the transition When the valve and the first fuel valve are closed, the second fuel valve is opened, and when the high combustion process shifts to the low combustion process, the blower rotates the rotation speed of the fan. The first fuel valve and the transition valve are opened, the second fuel valve is closed, and the flow rate adjusting valve is rotated at the rotational speed of the fan. Infinite fuel supply to cope with the decrease in fuel consumption Decreasing, after a predetermined time has elapsed from the time when the transition valve is opened, the transition valve is that is a closed state.

  In the third embodiment, in the high combustion process, the first fuel valve is closed and only the second fuel valve is opened. That is, the fuel supplied through the first fuel valve is set to a supply amount required in the low combustion process, and the fuel supplied through the second fuel valve is supplied in the high combustion process. Is set to

  Further, in the fourth embodiment of the present invention, the fuel supply amount is changed steplessly so as to correspond to the change in the rotational speed of the fan and the change in the opening degree of the damper at the time of transition to the combustion process. .

  Here, the damper controls the air volume of the combustion air supplied by the blower. Then, at the time of transition to the combustion process, the fuel supply device continuously adjusts the fuel supply amount so as to maintain a desirable air-fuel ratio with respect to the air volume that increases or decreases with the change in the rotation speed of the fan and the change in the opening degree of the damper. Change.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram of the combustion apparatus of the first embodiment, FIG. 2 is a schematic configuration diagram of a fuel supply device in the combustion apparatus of the first embodiment, and FIG. 3 is a diagram of the combustion apparatus of the first embodiment. It is a time chart of the control to perform.

  As shown in FIG. 1, the combustion apparatus 1 according to the present embodiment controls the air blower 2 that adjusts the air volume by controlling the rotational speed of the fan, and the air volume of the combustion air supplied by the air blower 2. A damper 3 and a fuel supply device 4 that changes the fuel supply amount steplessly are provided, and combustion is performed in the combustion chamber 5. The blower 2, the damper 3, and the fuel supply device 4 are controlled based on a control signal from the control unit 6. In the present invention, the type of fuel is not limited, but the combustion apparatus 1 of the present embodiment is an oil-fired boiler.

  The air blower 2 includes an electric motor 7 having a fan (not shown) and an inverter 8 connected to the electric motor 7 and controlling the fan rotation speed. From the inverter 8 based on a control signal from the control unit 6. The fan rotation speed is controlled by changing the output frequency signal. In this embodiment, as the frequency signal, a high combustion frequency, an ignition frequency, and a low combustion frequency are set from the highest, and the fan rotation speed when operating at each frequency is set to the high combustion frequency. Rotational speed, ignition rotational speed, low combustion rotational speed. By the way, the ignition frequency may be set to a higher numerical value than the high combustion frequency. In this embodiment, the purge frequency is set to be the same as the ignition frequency.

  The damper 3 is provided in a duct 9 serving as a flow path for combustion air supplied by the blower 2, and controls the air volume of the combustion air by partially closing a cross section of the duct 9. As the damper opening, a high combustion air volume position (90 ° with respect to the direction of the central axis of the duct 9, that is, a direction perpendicular to the air flow direction), and a low combustion air volume whose opening is smaller than the high combustion air volume position. Position (25 ° with respect to the direction perpendicular to the central axis direction of the duct 9) and an ignition air volume position with a smaller opening than the low combustion air volume position (with respect to the direction perpendicular to the central axis direction of the duct 9) 20 degrees) are set.

  Next, the fuel supply device 4 of the present embodiment will be described with reference to FIG. The fuel supply device 4 includes a fuel pump (not shown), a fuel tank (not shown), a first fuel valve 10, a second fuel valve 11, a flow rate adjusting valve 12, a transition valve 13, a low combustion nozzle 14 and a high Combustion nozzles 15 are provided, which are connected to each other through fuel flow paths 16, 17 and 18. The first fuel channel 16 is connected to a fuel pump and a fuel tank, and the fuel flows through the first fuel channel 16 in the direction of the arrow. A first fuel valve 10 is provided in the first fuel flow path 16, and is connected to a low combustion nozzle 14 at a downstream end of the first fuel valve 10. The fuel flow path branches from the first fuel flow path 16 to the second fuel flow path 17 and the third fuel flow path 18 on the upstream side of the first fuel valve 10. The second fuel flow path 17 is provided with the second fuel valve 11, and the third fuel flow path 18 is provided with the flow rate adjustment valve 12 and the transition valve 13 from the upstream side, and on the upstream side of the flow rate adjustment valve 12. Is provided with an orifice 19 for adjusting the amount of fuel supplied to the high combustion nozzle 15. The second fuel flow path 17 and the third fuel flow path 18 merge together at the downstream side of the second fuel valve 11 and the transition valve 13 and are connected to the high combustion nozzle 15 at the end. In the present embodiment, the transition valve 13 is arranged on the downstream side of the flow rate adjustment valve 12 in the third fuel flow path 18, but the transition valve 13 may be arranged on the upstream side of the flow rate adjustment valve 12.

  As the first fuel valve 10, the second fuel valve 11, and the transition valve 13, electromagnetic valves controlled by two operations of opening and closing are used. The flow rate adjusting valve 12 is a valve device capable of steplessly changing the size of the flow path cross-sectional area of the third fuel flow channel 18, and passes through the flow rate adjusting valve 12 and is a high combustion nozzle. The amount of fuel supplied to 15 can be changed steplessly.

  Next, a control method in the present embodiment that is executed by the control unit 6 will be described with reference to FIG. When the combustion apparatus 1 of this embodiment is activated, the blower 2 starts operation, the fan rotation speed is increased to the ignition rotation speed, and pre-purge is performed. During the pre-purge, the damper opening is set to the high combustion air volume position.

  After the pre-purge is performed for a predetermined time, the blower 2 is closed to the ignition air volume position while maintaining the fan rotation speed at the ignition rotation speed, and the process proceeds to the ignition process. In the ignition process, first, the ignition device is activated, the first fuel valve 10 is opened after a predetermined time has elapsed since the activation of the ignition device, and fuel supply is started. During this time, the ignition device is continuously activated, and is stopped after a predetermined time has elapsed since the start of fuel supply. By the way, the period from the start of the ignition device to the start of fuel supply is called pre-ignition, and the period from the start of fuel supply to the stop of the ignition device is called ignition try. An ignition process is configured.

  After the ignition process is completed, the state where the fan rotation speed is set to the ignition rotation speed and the damper opening is set to the ignition airflow position is continued for a predetermined time. Then, it shifts to a low combustion process. First, the air blower 2 starts changing the fan rotation speed to the low combustion rotation speed. Then, the elapsed time from the change start time of the fan rotation speed is measured by the time measuring means, and when the elapsed time reaches the set time T1, the damper 3 is opened to the low combustion air volume position. In this embodiment, the opening and closing speed of the damper 3 is slow, and as shown in FIG. 3, it is configured to change from the ignition air volume position to the low combustion air volume position at time T1. However, when the opening / closing speed of the damper 3 is fast, the damper 3 can be configured to open during the change of the fan rotation speed.

  In the low combustion process, the fan rotation speed is set to the low combustion rotation speed, and the damper opening is set to the low combustion air volume position. Here, the low combustion rotational speed is the rotational speed of the fan set so that the amount of combustion air required for the low combustion process is supplied when the damper is in the low combustion airflow position. Yes, with the damper in the fully open position, the speed is higher than the rotational speed of the fan, which is the air volume required for the low combustion process. Further, the low combustion air volume position of the damper is an opening degree in a state where the wind pressure generated by the flame is prevented from propagating in the direction of the fan in the low combustion process, and the rotation of the fan. When the speed is the low combustion rotational speed, it means a damper opening degree at which combustion air required for the low combustion process is supplied. In this way, by setting the fan rotation speed to the low combustion rotation speed and the damper to the low combustion airflow position in the low combustion process, the combustion air having the airflow required for the low combustion process is supplied and the blower 2 The discharge pressure on the side can be hardly affected by the wind pressure generated by the flame, and stable combustion can be performed even in the low combustion process. In the low combustion process, an amount of fuel necessary for the low combustion process is supplied to the low combustion nozzle 14 through the first fuel valve 10.

  When shifting from the low combustion process to the high combustion process, first, the flow rate adjusting valve 12 and the transition valve 13 are opened, and the time measuring means measures the elapsed time from when the transition valve 13 is opened, and the set time T2 Then, the blower 2 starts changing the fan rotation speed from the low combustion rotation speed to the high combustion rotation speed. This set time T2 is set to a time comparable to the time required from the start of the valve opening operation of the flow rate adjusting valve 12 until the fuel is actually supplied to the high combustion nozzle 15. By the way, when the time difference from the start of the valve opening operation of the flow rate adjusting valve 12 until the fuel is actually supplied to the high combustion nozzle 15 can be ignored, the set time T2 may not be provided. It does not matter before and after the change of the fan rotation speed and the opening operation of the flow rate adjusting valve 12.

  In this embodiment, an inverter 8 is used as an air volume control device, and the fan rotation speed is controlled to increase in proportion to the elapsed time. The flow rate adjusting valve 12 increases the fuel supply amount steplessly so as to maintain a desired air-fuel ratio in response to the increase in the fan rotation speed. The fuel supplied to the high combustion nozzle 15 through the flow rate adjusting valve 12 passes through the first fuel valve 10 when the fan rotational speed reaches the high combustion rotational speed. 14 is set so as to be the amount necessary for the high combustion process.

  Moreover, the elapsed time from the time when the transition valve 13 is opened is measured by the time measuring means, and when the elapsed time reaches the set time T3, the transition valve 13 is closed. The set time T3 is set to approximately the same time as the sum of the set time T2 and the time T4 required for the fan rotation speed to reach the high combustion rotation speed from the low combustion rotation speed.

  On the other hand, the flow regulating valve 12 is maintained in the open state even during the high combustion process after the transition valve 13 is closed. In the present embodiment, the first fuel valve 10 is also closed and the second fuel valve 11 is opened simultaneously with the transition valve 13 being closed. That is, in the high combustion process, an amount of fuel necessary for the high combustion process is supplied to the high combustion nozzle 15 only through the second fuel flow path 17, and the fuel is supplied to the low combustion nozzle 14. Not done. Thus, in the high combustion process, fuel is sprayed into the combustion chamber 5 only from the high combustion nozzle 15, so that the fuel sprayed from both nozzles 14, 15 does not interfere with each other and cause poor combustion. , Better combustion can be performed. In addition, since the flow rate adjusting valve 12 is used only at the time of transition of the fan rotation speed in this way, clogging of the flow path caused by the flow rate adjusting valve 12 can be effectively prevented, Stable operation with less can be realized.

  At the same time, the damper 3 is opened to the high combustion air volume position simultaneously with the start of changing the fan rotation speed from the low combustion rotational speed to the high combustion rotational speed. In this embodiment, the opening and closing speed of the damper 3 is slow, and as shown in FIG. 3, the damper 3 is configured to open from the low combustion air volume position to the high combustion air volume position at time T4. Since the flow rate adjustment valve 12 gradually increases the amount of fuel supplied to the high combustion nozzle 15 in response to the gradual increase in air volume caused by the change in the damper opening and the change in the fan rotation speed, that is, a smooth increase. Stable combustion can be performed without destroying the air-fuel ratio. In this embodiment, the damper 3 is configured to change from the low combustion airflow position to the high combustion airflow position at time T4. However, when the opening / closing speed of the damper 3 is fast, the fan rotation speed is changed. It can also be configured to open the damper 3 in the middle.

  In the high combustion process, the fan rotation speed of the blower 2 is maintained at the high combustion rotation speed while the damper opening is at the high combustion airflow position.

  When shifting from the high combustion process to the low combustion process, the first fuel valve 10 and the transition valve 13 that were in the closed state are first opened, and at the same time, the second fuel valve 11 is closed. Thus, fuel is supplied to the nozzles 14 and 15 through the first fuel passage 16 and the third fuel passage 18 instead of the second fuel passage 17. And the elapsed time from the time when the transition valve 13 is opened is measured by the time measuring means, and when the elapsed time reaches the set time T5, the fan rotation speed of the blower 2 is reduced from the high combustion rotation speed. The transition to the rotational speed for combustion is started. This set time T5 is approximately the same as the time required from when the transition valve 13 is opened until the fuel is actually supplied to the high combustion nozzle 15. By the way, when the time difference from when the transition valve 13 is opened to when the fuel is actually supplied to the high combustion nozzle 15 can be ignored, the set time T5 may not be provided, and the fan rotational speed is not required. It does not matter before and after the change and the opening operation of the transition valve 13.

  The change of the fan rotation speed is controlled by the inverter 8 so as to decrease in proportion to the elapsed time. The flow rate adjusting valve 12 decreases the fuel supply amount steplessly so as to maintain a desired air-fuel ratio in correspondence with the decrease in the fan rotation speed.

  Further, the elapsed time from the time when the transition valve 13 is opened is measured by the time measuring means, and when the elapsed time reaches the set time T6, the flow rate adjusting valve 12 and the transition valve 13 are closed. The set time T6 is set to a time comparable to the sum of the set time T5 and the time T7 required for the fan rotational speed to reach the low combustion rotational speed from the high combustion rotational speed.

  At the same time, the damper 3 is closed to the low combustion air volume position simultaneously with the start of the change of the fan rotational speed from the high combustion rotational speed to the low combustion rotational speed. In this embodiment, the opening and closing speed of the damper 3 is slow, and as shown in FIG. 3, it is configured to close from the high combustion air volume position to the low combustion air volume position at time T7. Since the flow rate adjustment valve 12 gradually reduces the amount of fuel supplied to the high combustion nozzle 15 in response to the gradual decrease of the air volume caused by the change in the damper opening and the change in the fan rotation speed, that is, the smooth decrease. Stable combustion can be performed without losing the air-fuel ratio. In this embodiment, the damper 3 is configured to change from the high combustion airflow position to the low combustion airflow position at time T7. However, when the opening / closing speed of the damper 3 is fast, the fan rotation speed is changed. The damper 3 can be configured to close in the middle.

  Completion of combustion is performed following the low combustion process, the first fuel valve 10 is closed, and the fan rotation speed of the blower 2 is shifted from the low combustion rotation speed to the ignition rotation speed, and the damper is opened. The post-purge is continued for a predetermined time in a state where the degree is set to the high combustion air volume position and the rotation speed for ignition is kept as it is. Thereafter, the blower 2 is stopped. In this way, the combustion device 1 stops operating. The post purge can be omitted as necessary.

  According to the first embodiment, stable combustion can be realized at the time of transition from the ignition process to the low combustion process and in the low combustion process, and the combustion apparatus 1 excellent in combustibility can be provided. Further, stable combustion is possible even if the air volume and fuel supply amount of combustion air in the low combustion process are reduced, and the turndown ratio (ratio of high combustion amount to low combustion amount) can be increased. Further, in the high combustion process, fuel sprayed from the nozzles 14 and 15 into the combustion chamber does not interfere with each other to cause poor combustion, and better combustion can be realized. Further, since the fuel supply amount is made the same by performing fuel supply through the first fuel valve 10 in common in the ignition process and the subsequent low combustion process, the ignition process can be performed by reducing the fuel supply amount in the low combustion process. The fuel supply amount can be reduced at the same time, and the ignition shock can be further suppressed.

  Next, a second embodiment of the present invention will be described. FIG. 4 is a time chart of control executed by the combustion apparatus of the second embodiment. In the second embodiment, the configuration of the combustion device 1 shown in FIG. 1 and the configuration of the fuel supply device 4 shown in FIG. 2 are common to the combustion device 1 of the first embodiment.

  The second embodiment is different from the first embodiment in that the first fuel valve 10 is continuously opened during combustion. Therefore, in the high combustion process, unlike the combustion device 1 of the first embodiment, the first fuel valve 10 is not closed, and the fuel that passes through the first fuel valve 10 and is supplied to the low combustion nozzle 14. And the amount of fuel that passes through the second fuel valve 11 and is supplied to the high combustion nozzle 15 is the fuel supply amount required for the high combustion process. In this case, fuel is sprayed from both the low combustion nozzle 14 and the high combustion nozzle 15 into the combustion chamber 5 at the same time. However, in order to perform good combustion, the fuel is sprayed from the nozzles 14 and 15. It is desirable to take measures to prevent the fuels from interfering with each other.

  As mentioned above, although the Example of this invention was described, this invention is not limited to the structure of the said Example, It can change suitably. For example, the second fuel flow path 17 provided with the second fuel valve 11 and the transition valve 13 in the fuel supply device 4 are not provided, and fuel is supplied through the third fuel flow path 18 in the high combustion process. You can also. Moreover, in the said Example, although the damper 3 was made into the low combustion air volume position in the low combustion process, it can also be comprised so that it may be set as the high combustion air volume position. Further, in the combustion apparatus for burning gas fuel, the present invention is configured such that a single nozzle is connected to a flow rate adjusting valve such as a motor valve, and a pressure equalizing valve such as a governor is provided on the upstream side to control the gas flow rate. In a combustion apparatus for burning oil fuel, the invention can be applied to a structure in which a single nozzle is connected to a flow rate adjusting valve. Of course, the damper 3 may be configured to be fully closed when combustion is stopped to prevent heat dissipation from a boiler body (not shown).

It is a schematic block diagram of the combustion apparatus in one Example of this invention. It is a schematic block diagram of the fuel supply apparatus in one Example of this invention. It is a figure which shows the control chart of the 1st Example in this invention. It is a figure which shows the control chart of the 2nd Example in this invention. It is a figure which shows the control chart in the conventional combustion apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Combustion device 2 Blower device 3 Damper 4 Fuel supply device 10 1st fuel valve 11 2nd fuel valve 12 Flow control valve 13 Transition valve

Claims (3)

A blower (2) that adjusts the air volume by controlling the rotational speed of the fan to at least a high combustion rotational speed or a low combustion rotational speed lower than the high combustion rotational speed;
A fuel supply device (4) that changes the fuel supply amount steplessly,
When changing the combustion process, the blower (2) changes the rotation speed of the fan, while the fuel supply device (4) changes the fuel supply amount so as to correspond to the change in the rotation speed of the fan. In a combustion device that changes steplessly,
The fuel supply device (4)
A first fuel valve (10) which is opened at least in a low combustion process;
A second fuel valve (11) opened in the high combustion process;
A flow rate adjustment valve (12) that changes the fuel supply amount steplessly;
A transition valve (13) for switching the presence / absence of supply of fuel passing through the flow rate adjustment valve,
When shifting from the low combustion process to the high combustion process, the blower (2) starts changing the rotational speed of the fan to the high combustion rotational speed, and the transition valve (13) is in the open state. The flow rate adjusting valve (12) increases the fuel supply amount steplessly so as to correspond to the increase in the rotational speed of the fan, and after a predetermined time has elapsed since the transition valve (13) was opened, The transition valve (13) is closed and the second fuel valve (11) is opened,
When shifting from a high combustion process to a low combustion process, the blower (2) starts changing the rotation speed of the fan to a low combustion rotation speed, and the transition valve (13) is in an open state. The second fuel valve (11) is closed, and the flow rate adjustment valve (12) decreases the fuel supply amount steplessly so as to correspond to the decrease in the rotation speed of the fan, and the transition valve ( The combustion valve characterized in that the transition valve (13) is closed after a predetermined time has elapsed since the time point 13) was opened. A blower (2) that adjusts the air volume by controlling the rotational speed of the fan to at least a high combustion rotational speed or a low combustion rotational speed lower than the high combustion rotational speed;
A fuel supply device (4) that changes the fuel supply amount steplessly,
When changing the combustion process, the blower (2) changes the rotation speed of the fan, while the fuel supply device (4) changes the fuel supply amount so as to correspond to the change in the rotation speed of the fan. In a combustion device that changes steplessly,
The fuel supply device (4)
A first fuel valve (10) that is opened in the low combustion process;
A second fuel valve (11) opened in the high combustion process;
A flow rate adjustment valve (12) that changes the fuel supply amount steplessly;
A transition valve (13) for switching the presence / absence of supply of fuel passing through the flow rate adjustment valve,
When shifting from the low combustion process to the high combustion process, the blower (2) starts changing the rotational speed of the fan to the high combustion rotational speed, and the transition valve (13) is in the open state. The flow rate adjusting valve (12) increases the fuel supply amount steplessly so as to correspond to the increase in the rotational speed of the fan, and after a predetermined time has elapsed since the transition valve (13) was opened, The transition valve (13) and the first fuel valve (10) are closed, and the second fuel valve (11) is opened.
When shifting from the high combustion process to the low combustion process, the blower (2) starts changing the rotation speed of the fan to the low combustion rotation speed, and the transition to the first fuel valve (10) is performed. The valve (13) is in the open state, the second fuel valve (11) is in the closed state, and the fuel supply amount is stepless so that the flow rate adjusting valve (12) corresponds to the decrease in the rotational speed of the fan. The combustion apparatus is characterized in that the transition valve (13) is closed after a predetermined time has elapsed since the transition valve (13) was opened. A damper (3) for controlling the air volume from the blower by being disposed at least at the high combustion air volume position or at a low combustion air volume position whose opening is smaller than the high combustion air volume position;
3. The fuel supply amount is changed steplessly so as to correspond to a change in rotational speed of the fan and a change in opening degree of the damper (3) at the time of transition to a combustion process. The combustion apparatus as described in.

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