JP3753851B2 - Boiler fuel supply change control device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel supply amount change control device for a boiler that adjusts a combustion amount in stages.
[0002]
[Prior art]
In the case of a boiler that performs combustion control at three positions of high combustion, low combustion, and stop, it is necessary to adjust the supply amount of combustion air in accordance with the fuel supply amount. As means for adjusting the air volume, rotation speed control means such as an inverter device is connected to the blower, and the supply amount of combustion air is adjusted by controlling the rotation speed of the blower.
Changing the rotational speed of the blower takes a longer time than changing the fuel supply amount, and if the air supply amount change and the fuel supply amount change output are performed simultaneously, the balance between air and fuel is lost. Therefore, the output of changing the rotation speed of the blower is performed first, and the rotation speed of the blower is detected by detecting the frequency output from the inverter. When the rotation speed of the blower reaches a predetermined value, the fuel is An output that changes the supply amount is performed.
[0003]
However, the density of air changes with temperature, and when the room temperature of the boiler chamber, that is, the temperature of combustion air, fluctuates, the amount of oxygen supplied fluctuates even if the rotational speed of the blower is the same. Combustion tends to become unstable when the fuel supply amount is changed, and the oxygen supply amount changes when the fuel supply amount is changed due to changes in the room temperature of the boiler chamber. There was a problem that the balance was lost and black smoke or white smoke was generated, causing boiler clogging.
[0004]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to prevent the combustion from becoming unstable when the fuel supply amount is changed in a boiler that controls the rotational speed of the blower.
[0005]
[Means for Solving the Problems]
It is a boiler with a combustion device that adjusts the amount of combustion in stages by adjusting the fuel supply amount in stages, and a rotation speed control means that controls the rotation speed is connected to a blower that sends combustion air and rotates. The air supply amount is adjusted according to the combustion amount by controlling the rotational speed of the blower by the number control means. When the rotational speed of the blower reaches the set value for changing the fuel supply amount, the fuel supply amount is adjusted. In a boiler that is being changed, a temperature measuring device that detects the temperature of combustion air is provided, and a correction device that changes the set value for changing the fuel supply amount based on the air temperature measured by the temperature measuring device Is provided.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention. The boiler 1 is provided with a combustion device 2 at the top, and combustion is performed by the fuel sent through the fuel supply pipe 3 and the combustion air sent from the blower 6. The amount of combustion is controlled by adjusting the fuel supply amount and the air volume. The fuel supply amount is controlled by a first electromagnetic valve 4 and a second electromagnetic valve 5 provided in the middle of the fuel supply pipe 3. Combustion stops when the solenoid valve 4 and the second solenoid valve 5 are closed, low combustion when only the first solenoid valve 4 is opened, and high combustion when the first solenoid valve 4 and the second solenoid valve 5 are opened. Become. The blower motor 7 is connected to an inverter 8 serving as a rotational speed control means, and the rotational speed (rotational speed) of the blower motor 7 is changed according to the frequency output from the inverter 8. A temperature measuring device 9 for detecting the temperature of the boiler room, a correcting device 12 for connecting the temperature measuring device 9 to change the set frequency, and a frequency detecting device 11 for detecting the frequency output from the inverter 8 are provided. Keep it. Combustion control such as opening and closing of the first solenoid valve 4 and the second solenoid valve 5 and air volume adjustment by the inverter 8 are performed by the combustion device 2, the first solenoid valve 4, the second solenoid valve 5, the inverter 8, the correction device 12, and the frequency detection. This is performed by the control device 10 connected to each of the devices 11.
[0007]
FIG. 2 is a time chart showing the state of combustion and air volume adjustment in one embodiment of the present invention, and shows the control performed by the control device 10. In this example, the combustion fluctuates as stop → low combustion → high combustion → low combustion → stop → low combustion → high combustion, and the room temperature of the first boiler chamber was low, but then increased, so combustion It is assumed that the volume of air necessary for the operation increases.
[0008]
The correction device 12 has a reference second electromagnetic valve opening / closing frequency that is the second electromagnetic valve opening / closing frequency at the reference temperature, and a calculation formula for calculating an increase / decrease value from the temperature measured by the temperature measuring device 9. Keep it. The correction device 12 substitutes the room temperature of the boiler room measured by the temperature measuring device 9 into the calculation formula, and inputs the value of the second electromagnetic valve opening / closing frequency calculated by increasing / decreasing it from the reference second electromagnetic valve opening / closing frequency to the control device 10. To do. When the set frequency is changed when the combustion is stopped for the first time, the combustion of the boiler is not performed in the morning when the temperature is not rising, and the temperature of the boiler chamber is low. It is assumed that the second electromagnetic valve opening / closing frequency (2), which is a small value, is set.
[0009]
When combustion is started and the combustion state is low combustion, the control device 10 outputs low combustion to the inverter 8, and the inverter 8 outputs a low combustion frequency to the blower motor 7 and is supplied to the combustion device 2. The air volume is a low combustion air volume. In the case of low combustion, only the first solenoid valve 4 is open, and the second solenoid valve 5 remains closed. When changing the combustion amount from low combustion to high combustion, the control device 10 changes the output to the inverter 8 to high combustion, and the inverter 8 changes the frequency from the low combustion frequency to the high combustion frequency, The rotational speed of the blower motor 7 gradually increases. When the frequency detection device 11 detects that the frequency output from the inverter 8 has reached the second electromagnetic valve opening / closing frequency (2), the control device 10 opens the second electromagnetic valve and starts high combustion. The frequency output to the blower motor 7 at the time of high combustion is the high combustion frequency, and the amount of air supplied to the combustion device 2 is the high combustion air volume.
[0010]
Thereafter, the same applies to the case where the combustion amount is changed from high combustion to low combustion. The inverter 8 changes the frequency from the high combustion frequency to the low combustion frequency, and the rotational speed of the blower motor 7 gradually decreases. . When the frequency detection device 11 detects that the frequency output from the inverter 8 has reached the second electromagnetic valve opening / closing frequency (2), the control device 10 closes the second electromagnetic valve and opens only the first electromagnetic valve 4. Transition to low combustion.
[0011]
When the combustion is stopped, the frequency output from the control device 10 becomes 0, and the blower motor 7 is also stopped. The correction device 12 changes the set frequency when the combustion is stopped. The correction device 12 substitutes the room temperature of the boiler room measured by the temperature measurement device 9 into the calculation formula, newly sets the second electromagnetic valve opening / closing frequency by calculation, and outputs it to the control device 10. Since the room temperature of the boiler chamber at this time rose due to the rise in temperature over time and the heat released when the boiler was burned, the second solenoid valve opening / closing frequency was higher than the previous value. 2 It is assumed that the solenoid valve opening / closing frequency (1) is set.
[0012]
In the next combustion, the second electromagnetic valve is opened and closed at a newly set frequency. When the combustion is started and the low combustion is performed, the inverter 8 outputs the frequency of the low combustion frequency to the blower motor 7. When changing the combustion amount from low combustion to high combustion, the control device 10 changes the output to the inverter 8 to high combustion, and the inverter 8 changes the frequency from the low combustion frequency to the high combustion frequency. When the frequency detection device 11 detects that the frequency output from the inverter 8 has reached the second electromagnetic valve opening / closing frequency (1), the control device 10 opens the second electromagnetic valve and starts high combustion. Since the second solenoid valve opening / closing frequency {circle around (1)} is set to a value higher than the second solenoid valve opening / closing frequency {circle around (2)}, the air supply amount when the high combustion is started is the second solenoid valve opening / closing frequency {circle around (2)}. The amount is larger than the case where is set. However, since the density in the combustion air is reduced due to the temperature rise in the boiler chamber, the amount of air actually sent when changing the fuel supply amount is the same as the previous time.
[0013]
The room temperature of the boiler room is the temperature of the combustion air, and if the air temperature is low, the density of the air is high, and if the temperature is high, the density is low. Is supplied with a large amount of oxygen, and the amount of oxygen supplied decreases at high temperatures. Therefore, as described above, when the temperature is low, the frequency is set lower to reduce the air supply amount when changing the fuel supply amount, and when the temperature is high, the frequency is set higher to increase the air supply amount when changing the fuel supply amount. Thus, the oxygen supply amount at the time of changing the fuel supply amount can be set to an appropriate amount.
[0014]
In addition, although the temperature change of the boiler room in one day was illustrated in the present embodiment, the setting value is changed by detecting the temperature of the air, so that it corresponds to the temperature change due to seasonal fluctuations. be able to.
[0015]
【The invention's effect】
By carrying out the present invention, it is possible to make the combustion air supply amount appropriate when changing the fuel supply amount, and to prevent the combustion from becoming unstable.
[Brief description of the drawings]
FIG. 1 is a block diagram of an embodiment of the present invention. FIG. 2 is a time chart of an embodiment of the present invention.
DESCRIPTION OF SYMBOLS 1 Boiler 2 Combustion apparatus 3 Fuel supply piping 4 1st solenoid valve 5 2nd solenoid valve 6 Blower 7 Blower motor 8 Inverter 9 Temperature measurement apparatus 10 Control apparatus 11 Frequency detection apparatus 12 Correction apparatus

Claims (1)

It is a boiler with a combustion device that adjusts the amount of combustion in stages by adjusting the fuel supply amount in stages, and a rotation speed control means that controls the rotation speed is connected to a blower that sends combustion air and rotates. The air supply amount is adjusted according to the combustion amount by controlling the rotational speed of the blower by the number control means. When the rotational speed of the blower reaches the set value for changing the fuel supply amount, the fuel supply amount is adjusted. In the boiler that is changing,
A temperature measuring device for detecting the temperature of the combustion air, and a correction device for changing the set value for changing the fuel supply amount based on the air temperature measured by the temperature measuring device ;
When changing the combustion amount from low combustion with small combustion amount to high combustion with large combustion amount, first increase the rotational speed of the blower gradually to the set value for changing the fuel supply amount set based on the air temperature When the rotation speed of the blower reaches, increase the fuel supply amount and start high combustion,
When changing the combustion amount from high combustion with a large amount of combustion to low combustion with a small amount of combustion, first reduce the rotational speed of the blower gradually to the set value for changing the fuel supply amount set based on the air temperature. A fuel supply amount change control device for a boiler, wherein when the rotation speed of the blower reaches, the fuel supply amount is decreased and low combustion is started .

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