JP5725608B2 - Combustion multi-position control boiler - Google Patents

Description

  The present invention relates to a boiler that controls the amount of combustion at multiple positions.

  In general, boilers perform control to increase or decrease the combustion amount in response to a steam load request, and increase or decrease the combustion amount by switching the supply amount of fuel and combustion air. Recently, the minimum combustion amount is reduced and the turndown ratio is set large, and the combustion position is controlled at multiple positions such as high combustion, medium combustion, low combustion, and stop, so that the efficiency at low load operation can be increased, Boilers that improve steam load followability and stabilize steam pressure have also appeared. As a means for adjusting the amount of combustion air supplied, a damper that provides a rotational speed control device such as an inverter device to the blower to increase or decrease the rotational speed of the blower, or to change the flow passage area to the combustion air blower passage This is done by providing a device and increasing or decreasing the flow area of the air passage.

  Japanese Patent Application Laid-Open No. 10-213320 discloses that the air flow rate is adjusted by using both the change of the blower rotation speed and the change of the flow passage area by the damper. In this case, even if the fan rotation speed change and the damper position change are started at the same time, the time required to change the fan rotation speed and the time required to change the opening of the damper are different. There were times when it was off. If the adjustment of the combustion amount is in the three positions of high combustion, low combustion, and stop, even if a temporary deviation of the air flow occurs when the combustion amount is changed, The gap does not grow any further. However, because the turndown ratio is large, the combustion amount is set to multiple positions such as high combustion, medium combustion, low combustion, and stop, and the change from low combustion to high combustion or high combustion When the combustion amount is changed greatly, such as when changing from low to low combustion, the deviation of the blast amount may become large. In this case, since the combustion amount is switched in a state deviating from an appropriate air amount, combustion misfire or vibration combustion may occur when the combustion amount is changed.

JP-A-10-213320

  The problem to be solved by the present invention is a boiler in which the combustion amount is controlled at multiple positions. The adjustment of the combustion air supply amount is performed by adjusting the rotational speed of the blower and adjusting the flow area of the combustion air supply path. A combustion multi-position control boiler that can prevent combustion misfire or vibration combustion from occurring when the combustion air supply amount is outside the proper range when the combustion amount is changed is provided. There is.

This is a boiler that can change the combustion amount in multiple stages, such as high combustion, medium combustion, and low combustion, and it uses both rotation speed change of the blower and flow passage area change of the air passage. In a combustion multi-position control boiler that adjusts the air supply amount for
When changing the combustion amount to two or more stages, such as changing from high combustion to low combustion, or changing from low combustion to high combustion, first the rotational speed of the blower aiming at the air supply amount at the combustion position in the middle Change and flow area change of the air passage are started, and the fuel is switched to the supply amount corresponding to the intermediate combustion position before the air supply amount reaches the set air volume at the intermediate combustion position. The change in the rotational speed of the blower and the change in the flow passage area of the blower that are aimed at the air supply amount at the combustion position in the combustion position are set at the combustion position in the middle of the flow passage area of the blower before the rotational speed of the blower. When the value reaches the value, the flow area change of the air passage is temporarily stopped and waits until the rotational speed of the blower reaches the set value at the combustion position in the middle, and the rotational speed of the blower is earlier than the flow area of the air passage. Set value at the combustion position on the way When it reaches, the rotation speed change of the blower is paused, and it waits until the flow passage area of the air passage reaches the set value at the combustion position in the middle, both the rotation speed of the blower and the flow passage area of the air passage After reaching the set position at the combustion position in the middle, aiming for the air supply amount at the target combustion position, start changing the rotation speed of the blower and changing the flow passage area of the air passage again, and then continue to supply the target fuel Control to switch to quantity.

  When the present invention is implemented, even if the combustion amount is largely changed, the combustion air supply amount will not be greatly deviated from the proper range, so that the occurrence of combustion misfire or vibration combustion is prevented when the combustion amount is changed. Can do.

Flow diagram of boiler implementing the present invention Time chart for explaining the operating state when the combustion amount in one embodiment of the present invention is changed from low combustion to high combustion Time chart for explaining the operation state when the combustion amount in one embodiment of the present invention is changed from high combustion to low combustion

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a flow diagram of a boiler implementing the present invention. In the boiler, vertical water pipes are arranged in a ring around the combustion chamber 3 provided in the center, and are connected to the header at the upper and lower parts of the water pipe. A combustion device 2 that generates a downward flame is provided above the combustion chamber 3, and the flame is burned in the combustion chamber 3 in the center of the boiler. The combustion device 2 is provided with a main burner 5 and a pilot burner 6. The combustion air used in the combustion device 2 is supplied by the blower 10. Combustion air from the blower 10 is supplied through the air passage 7, and the combustion air is rectified by the wind box 8 and supplied to the main burner 5 and the pilot burner 6. An inverter device 17 that changes the power supply frequency of the blower is connected to the blower 10, and the amount of combustion air sent to the combustion device 2 is adjusted by changing the rotational speed of the blower by the inverter device 17. Further, a damper 16 for changing the flow passage area of the air passage 7 is provided in the middle of the air passage 7, and the amount of combustion air sent to the combustion device 2 is also adjusted by the damper 16.

  The boiler controls the combustion amount at four positions of high combustion, medium combustion, low combustion, and stop, and the combustion amount is determined based on the steam pressure value detected by the pressure detection device 1 connected to the steam portion of the boiler. decide. When the steam pressure value is lower than the lower limit value of the control range, combustion is performed with high combustion, which is 100% combustion amount, and the steam pressure value is increased by increasing the steam generation amount. Conversely, when the steam pressure value becomes higher than the upper limit value of the control range, the increase of the steam pressure value is prevented by stopping the combustion. When the steam pressure value is within the control range, if the steam pressure value is relatively low, medium combustion with a combustion amount of 50% is performed, and if the steam pressure value is relatively high, low combustion with a combustion amount of 20% is performed. I do.

  Fuel is supplied to the combustion device 2 through the fuel supply pipe 4. The fuel supply pipe 4 branches off in the middle and is connected to each of the main burner 5 and the pilot burner 6. The fuel supply pipe 4 connected to the main burner 5 is provided with a main fuel cutoff valve 13, a main second solenoid valve 14 and a main third solenoid valve 15 as fuel supply amount adjusting means, and is connected to the pilot burner 6. The fuel supply pipe 4 is provided with a pilot fuel cutoff valve 12. The fuel is supplied to the main burner 5 by opening the main fuel shut-off valve 13, and the flow rate is switched by the main second solenoid valve 14 and the main third solenoid valve 15, thereby achieving high combustion, medium combustion, and low combustion. The fuel can be supplied. The main fuel shut-off valve 13 is a shut-off valve for completely shutting off the flow of fuel, and opens and closes at two positions: a 100% opening when the fuel flows and a 0% opening that shuts off the fuel. The main second electromagnetic valve 14 is an electromagnetic valve that is set to an opening that allows 100% fuel to flow when the valve is opened, and an opening that allows 20% fuel to flow even when the valve is closed. Opening and closing at 2 positions of opening and 20% opening. The main third electromagnetic valve 15 is also an electromagnetic valve set to have an opening for flowing 100% fuel when the valve is opened and an opening for flowing 50% fuel even when the valve is closed. Open and close at 2 positions of% opening and 50% opening.

  The fuel supply amount is controlled by opening / closing the main fuel cutoff valve 13, the main second solenoid valve 14, and the main third solenoid valve 15. When the combustion is stopped, the operation control device 11 performs control to close each control valve. The main second solenoid valve 14 and the main third solenoid valve 15 do not completely close the fuel gas flow path even if the valve closing control is performed, and the main second solenoid valve 14 and the main third solenoid valve 15 are opened as much as 20% or 50% of the fuel flows. . However, since the upstream main fuel cutoff valve 13 is closed, the gas fuel does not flow through the main second solenoid valve 14 and the main third solenoid valve 15, and the gas flow rate sent to the combustion device 2 is 0. %, Fuel gas supply is completely stopped.

  When starting the combustion of the boiler, first, the combustion of the pilot burner 6 is started, and the combustion of the main burner 5 is started using the flame of the pilot burner 6 as a fire type. In the case of pilot combustion in which only the pilot burner 6 is burned, the operation control device 11 opens only the pilot fuel cutoff valve 12 and keeps the other control valves closed. The combustion of the pilot burner 6 is performed only before and after the combustion of the main burner 5 is started. When the combustion of the main burner 5 is started, the pilot fuel cutoff valve 12 is closed to stop the combustion in the pilot burner 6.

  When the combustion amount of the boiler is low combustion, the operation control device 11 performs control to open only the main fuel cutoff valve 13, and performs control to close the main second solenoid valve 14 and the main third solenoid valve 15. When only the main fuel shut-off valve 13 is opened, the main fuel shut-off valve 13 has an opening at which 100% of fuel gas flows, and the main fuel shut-off valve 13 and the main second solenoid valve 14 each flow 20% of fuel gas. The opening and the opening through which 50% of the fuel gas flows. In this case, the amount of fuel gas that flows through the fuel gas supply pipe 4 and reaches the combustion device 2 is an amount that can be flowed by the main second electromagnetic valve 14 that is a bottleneck, and 20% of the fuel gas flows to the main burner 5 Sent. At this time, low combustion (20% combustion) can be performed by supplying air corresponding to the combustion amount of 20% from the blower 5 to the combustion device 2 as well.

  When the combustion amount of the boiler is medium combustion, the operation control device 11 performs control to open the main fuel cutoff valve 13 and the main second solenoid valve 14, and performs control to close the main third solenoid valve 15. When the main fuel shut-off valve 13 and the main second solenoid valve 14 are opened, the main fuel shut-off valve 13 is opened so that 100% of the fuel gas flows, and the main second solenoid valve 14 is also opened of 100% of the fuel gas. In the closed main third solenoid valve 15, the opening is such that 50% of the fuel gas flows. In this case, since the amount of fuel gas that flows through the fuel supply pipe 4 and reaches the combustion device 2 becomes an amount that can flow through the main third electromagnetic valve 15, 50% of the fuel gas is sent to the combustion device 2. At this time, medium combustion (50% combustion) can be performed by supplying air corresponding to the combustion amount of 50% from the blower 10 to the combustion device 2 as well.

  When the combustion amount of the boiler is high, the operation control device 11 performs control to open all the control valves of the main fuel cutoff valve 13, the main second solenoid valve 14, and the main third solenoid valve 15. In this case, since the main fuel cutoff valve 13, the main second solenoid valve 14, and the main third solenoid valve 15 have opening amounts through which 100% of the fuel gas flows, they flow through the fuel supply pipe 4 and reach the combustion device 2. The amount of fuel gas is 100%. At this time, high combustion (100% combustion) can be performed by supplying air corresponding to the combustion amount of 100% from the blower 10 to the combustion device 2 as well.

  Since the required combustion air supply amounts for high combustion, medium combustion, and low combustion are different, the damper 16 and the inverter device 17 adjust the combustion air supply amount. In the damper 16, a low fuel position is set as a setting position at the time of low combustion, a medium fuel position is set as a setting position for medium combustion, and a high fuel position is set as a setting position for high combustion. The set position is set to an air supply amount corresponding to each combustion state, and the flow passage area of the air passage 7 becomes larger in the order of low fuel position <intermediate fuel position <high fuel position.

  In the inverter device 17, a low fuel frequency is set as a set frequency at the time of low combustion, a medium fuel frequency is set as a set frequency for medium combustion, and a high fuel frequency is set as a set frequency for high combustion. The inverter device 17 also has an air supply amount corresponding to each combustion state, and the rotational speed in the blower 10 increases in the order of low combustion frequency <intermediate combustion frequency <high combustion frequency. The supply amount of combustion air for each combustion amount is adjusted by the damper 16 and the inverter device 17, and an amount of air corresponding to each combustion amount is supplied to the combustion device 2.

  When the combustion amount is changed between low combustion and medium combustion, the frequency by the inverter device 17 reaches the V2 switching frequency (main second solenoid valve switching frequency) set to a value between the low combustion frequency and the middle combustion frequency. Then, the main second solenoid valve 14 is operated to change the fuel supply amount. Similarly, when changing the combustion amount between the middle combustion and the high combustion, the V3 opening / closing position (main third solenoid valve opening / closing position) in which the position of the damper 16 is set to a value between the middle combustion position and the high combustion position. Is set so that the fuel supply amount is changed by operating the main third electromagnetic valve 15.

  FIG. 2 shows the state of change of the combustion state when the required amount of combustion is low combustion at the beginning but the required amount of combustion is changed to high combustion by skipping medium combustion. When the required combustion amount changes from low combustion to high combustion and the combustion amount increases, the operation control device 11 first starts increasing the frequency of the inverter device 17. At this time, the frequency of the inverter device 17 changes slowly because it cannot be changed rapidly. When the frequency of the inverter device 17 reaches the V2 opening / closing frequency, the damper position is changed from the low fuel position to the medium fuel position, and the main second electromagnetic valve 14 is opened to start medium combustion. Although the required combustion amount is high combustion and not intermediate combustion, the operation control device 11 temporarily performs intermediate combustion which is an intermediate combustion amount. Thereafter, when the damper 16 reaches the middle combustion position before the inverter device 17, the damper 16 temporarily stops changing the opening at the middle fuel position, and the frequency of the inverter device 17 reaches the middle combustion position. Wait until. Conversely, when the inverter device 17 reaches the middle combustion position before the damper 16, the inverter device 17 temporarily stops changing the frequency at the middle combustion position until the opening degree of the damper 16 reaches the middle combustion position. stand by. When both the damper 16 and the inverter device 17 reach the middle combustion position, the increase of the combustion air supply amount is resumed, the damper 16 changes the damper position aiming at the high combustion position, and the inverter device 17 The frequency is changed aiming at the fuel frequency. Thereafter, when the position of the damper 16 reaches the V3 open / close position, the main third solenoid valve 15 is opened to start high combustion, and when the damper 16 and the inverter device 17 reach the high combustion set position, the air supply amount is changed. finish.

  In FIG. 2, after that, the required amount of combustion decreases from high combustion to medium combustion, and then changes to low combustion. When changing from high combustion to intermediate combustion, the damper 16 and the inverter device 17 change toward the position for intermediate combustion. When the damper position reaches the V3 opening / closing position, the main third solenoid valve 15 is closed to set the combustion amount to medium combustion. After that, when the required amount of combustion is reduced to low combustion, the damper 16 and the inverter device 17 are changed aiming at the position for low combustion as before. When the frequency of the inverter device 17 reaches the V2 opening / closing frequency, the main second solenoid valve 14 is closed to reduce the combustion amount.

  FIG. 3 shows the state of change of the combustion state when the required amount of combustion was high combustion at the beginning but the required amount of combustion was changed to low combustion by skipping medium combustion. When the required combustion amount changes from high combustion to low combustion and the combustion amount is reduced, the operation control device 11 starts to reduce the frequency of the inverter device 17 and the flow passage area at the damper 16. At this time, the frequency of the inverter device 17 changes slowly because it cannot be changed rapidly. When the position of the damper 16 reaches the V3 open / close position, the main third solenoid valve 15 is closed to start medium combustion. In this case as well, the required combustion amount is low combustion and not intermediate combustion, but the operation control device 11 temporarily performs intermediate combustion, which is an intermediate combustion amount.

  When the damper 16 reaches the middle combustion position before the inverter device 17, the damper 16 temporarily stops changing the opening at the middle fuel position, and waits until the frequency of the inverter device 17 reaches the middle combustion position. . Conversely, when the inverter device 17 reaches the middle combustion position before the damper 16, the inverter device 17 temporarily stops changing the frequency at the middle combustion position until the opening degree of the damper 16 reaches the middle combustion position. stand by.

  When both the damper 16 and the inverter device 17 reach the middle combustion position, both the damper 16 and the inverter device 17 resume the reduction of the combustion air supply amount. The inverter device 17 changes the frequency with the aim of a low fuel frequency. Thereafter, when the frequency of the inverter device 17 reaches the V2 switching frequency, the main second solenoid valve 14 is closed to start low combustion, and when the damper 16 and the inverter device 17 reach the low combustion set position, the air supply amount is changed. Exit.

  In FIG. 3, thereafter, the required combustion amount increases from low combustion to medium combustion, and then changes to high combustion. When changing from low combustion to medium combustion, the damper 16 and the inverter device 17 change toward the position for medium combustion. When the damper position reaches the V2 open / close frequency, the main second solenoid valve 14 is opened to set the combustion amount to medium combustion. After that, when the required amount of combustion rises to high combustion, the damper 16 and the inverter device 17 are changed aiming at the position for high combustion as before. When the damper 16 position reaches the V3 opening / closing position, the main third solenoid valve 15 is opened to increase the combustion amount.

  Combustion multi-position control requires a change in the amount of combustion ahead of two or more (for example, changing from low to medium combustion to high combustion, or changing from high to medium combustion to low combustion) If the combustion air supply amount is adjusted by combining a plurality of combustion air supply amount adjusting means, the air supply amount may fall outside the proper range, and combustion misfire or vibration combustion may occur. It was. However, instead of directly changing to the final combustion amount, the combustion air supply amount is stabilized at the midway combustion amount, and then the switching of the combustion amount is resumed. Even when the air supply amount for combustion is adjusted by combining the adjusting means, it is possible to prevent the occurrence of combustion misfire or vibration combustion due to the air supply amount deviating from an appropriate range.

1 Pressure detection device 2 Combustion device
DESCRIPTION OF SYMBOLS 3 Combustion chamber 4 Fuel supply piping 5 Main burner 6 Pilot burner 7 Air supply path 8 Wind box 9 Steam piping 10 Blower 11 Operation control device 12 Pilot fuel cutoff valve 13 Main fuel cutoff valve 14 Main second solenoid valve 15 Main third solenoid valve 16 Damper 17 Inverter device

Claims (1)

This is a boiler that can change the combustion amount in multiple stages, such as high combustion, medium combustion, and low combustion, and it uses both rotation speed change of the blower and flow passage area change of the air passage. In a combustion multi-position control boiler that adjusts the air supply amount for
When changing the combustion amount to two or more stages, such as changing from high combustion to low combustion, or changing from low combustion to high combustion, first the rotational speed of the blower aiming at the air supply amount at the combustion position in the middle start the flow area change changes and air passage, the fuel keep switching the supply amount according to the combustion position in the middle at the time before the air volume supplied reaches a set air volume in the combustion position in the middle, middle The change in the rotational speed of the blower and the change in the flow passage area of the blower that are aimed at the air supply amount at the combustion position in the combustion position are set at the combustion position in the middle of the flow passage area of the blower before the rotational speed of the blower. When the value reaches the value, the flow area change of the air passage is temporarily stopped and waits until the rotational speed of the blower reaches the set value at the combustion position in the middle, and the rotational speed of the blower is earlier than the flow area of the air passage. Set value at the combustion position on the way Both reached the rotational speed change of the blower leave to wait until the flow channel area of the airflow path pause reaches the set value in the combustion position in the middle, the flow passage area of the rotational speed and the air passage of the blower After reaching the set position at the combustion position in the middle, aiming for the air supply amount at the target combustion position, start changing the rotation speed of the blower and changing the flow passage area of the air passage again, and then continue to supply the target fuel A combustion multi-position control boiler characterized by performing control to switch to a quantity.

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