1. Ultraviolet flame detector. Flame detector: Its main function is to monitor the formation of flames and generate a signal to report to the program controller.
There are three main types of flame detectors: photoresistor, ultraviolet UV electric eye and ionization electrode.
A. Photoresistor: It is mostly used on light oil and heavy oil burners. Its function and working principle are: the photoresistor is connected to a flame relay with three contacts. The resistance of the photoresistor changes with the amount of light received by the device. , the more light received, the lower the resistance. When the voltage applied to both ends of the photoresistor is constant, the current in the circuit is higher. When the current reaches a certain value, the flame relay is activated, allowing the burner to continue Work downward. When the photoresistor does not sense enough light, the flame relay does not work and the burner will stop working. Photoresistors are not suitable for gas burners because the flame is not bright enough when the gas burns.
B. Ionization electrode: mostly used on gas burners. The program controller inputs 220V voltage to the ignition transformer. One of the two output high-voltage wires is grounded, and the other is connected to the ignition electrode. The discharge between the electrode and the earth generates sparks, which ignites the gas and air mixture. The program controller supplies power to the ionization electrode. If Without a flame, the power supply to the electrode will stop. If there is a flame, the gas is ionized by its own high temperature. The ion current flows between the electrode, flame and burner head. The ion current is rectified into DC and reaches the burner shell through the ground. The flame relay makes it work to ensure the smooth progress of the subsequent work of the burner. If the ionization electrode is grounded, the current generated is AC instead of DC, the flame relay will not work, and the program controller will be locked. In addition, the ionization current and the ignition current pass through the same ground circuit. Since the ignition current is much stronger than the ionization current, if the two currents flow in opposite directions, the ionization current will be blocked by the ignition current, causing the burner to open circuit after the flame is formed. This This defect can be compensated by the reverse input of the ignition transformer, because after the wires are reversed, the direction of the alternating current of the ignition transformer is rotated 180°, and the direction of the generated ignition current is also rotated 180°. As a result, the two current directions are consistent, so the above defect is also overcome. In addition, the instability of the flame in the ionization zone will also cause the burner to be disconnected when the flame is still present. This may be because the air-gas ratio is inappropriate, which can be solved by adjusting the air volume or gas volume, or it may be that the air-gas distribution on the combustion head is uneven. The combustion head can be adjusted by
location to solve.
C. Ultraviolet UV electric eye: Generally used on oil and gas dual-purpose burners. This electric eye can only sense ultraviolet rays in the flame (spectral range 190~270 nanometers). The UV tube will not detect sunlight or ordinary light shining on the refractory material in the furnace. Or the glow substance in the furnace reacts. The life of the UV tube is about 10,000 hours at an ambient temperature not exceeding 50°C. High ambient temperature has a great impact on its life. If it receives a sufficient amount of ultraviolet light, it can generate an electric current, and with appropriate amplification, a machine or a flame relay, it can close. If the power of the UV tube is exhausted, even if there is no ultraviolet light, it will still show that it has received ultraviolet light. In order to overcome this defect, the program controller will add an appropriate voltage to both ends of it before each turn on, so that even if When the power is exhausted, its signal will only indicate that there is no flame, so the programmable controller will immediately stop working. In order to test the effect of the UV electric eye, pull it out from its original position for at least one minute after ignition. After the UV electric eye is withdrawn, the ultraviolet rays emitted by the flame cannot be detected, the relevant relay is disconnected, and the burner stops working. Even a small amount of oil will block the passage of ultraviolet rays into the photoelectric tube, causing the internal sensing element to not receive a sufficient amount of ultraviolet rays and fail to work. Therefore the photocell must be thoroughly cleaned. The UV tube cannot feel sunlight or the light of ordinary lamps. Its sensitivity can be tested by using a flame or a spark between the two electrodes of an ordinary ignition transformer. To ensure that the burner works properly, its current must be stable and cannot be lower than the current required by the programmable controller. This current can be detected with a microammeter.
The computer calculates the digitized image information in the image memory according to certain ignition criteria to obtain the presence or absence (0N/OFF) signal of the burner flame and sends it to the FSSS.
1. Ultraviolet flame detector. Flame detector: Its main function is to monitor the formation of flames and generate a signal to report to the program controller.
There are three main types of flame detectors: photoresistor, ultraviolet UV electric eye and ionization electrode.
A. Photoresistor: It is mostly used on light oil and heavy oil burners. Its function and working principle are: the photoresistor is connected to a flame relay with three contacts. The resistance of the photoresistor changes with the amount of light received by the device. , the more light received, the lower the resistance. When the voltage applied to both ends of the photoresistor is constant, the current in the circuit is higher. When the current reaches a certain value, the flame relay is activated, allowing the burner to continue Work downward. When the photoresistor does not sense enough light, the flame relay does not work and the burner will stop working. Photoresistors are not suitable for gas burners because the flame is not bright enough when the gas burns.
B. Ionization electrode: mostly used on gas burners. The program controller inputs 220V voltage to the ignition transformer. One of the two output high-voltage wires is grounded, and the other is connected to the ignition electrode. The discharge between the electrode and the earth generates sparks, which ignites the gas and air mixture. The program controller supplies power to the ionization electrode. If Without a flame, the power supply to the electrode will stop. If there is a flame, the gas is ionized by its own high temperature. The ion current flows between the electrode, flame and burner head. The ion current is rectified into DC and reaches the burner shell through the ground. The flame relay makes it work to ensure the smooth progress of the subsequent work of the burner. If the ionization electrode is grounded, the current generated is AC instead of DC, the flame relay will not work, and the program controller will be locked. In addition, the ionization current and the ignition current pass through the same ground circuit. Since the ignition current is much stronger than the ionization current, if the two currents flow in opposite directions, the ionization current will be blocked by the ignition current, causing the burner to open circuit after the flame is formed. This This defect can be compensated by the reverse input of the ignition transformer, because after the wires are reversed, the direction of the alternating current of the ignition transformer is rotated 180°, and the direction of the generated ignition current is also rotated 180°. As a result, the two current directions are consistent, so the above defect is also overcome. In addition, the instability of the flame in the ionization zone will also cause the burner to be disconnected when the flame is still present. This may be because the air-gas ratio is inappropriate, which can be solved by adjusting the air volume or gas volume, or it may be that the air-gas distribution on the combustion head is uneven. The combustion head can be adjusted by
location to solve.
C. Ultraviolet UV electric eye: Generally used on oil and gas dual-purpose burners. This electric eye can only sense ultraviolet rays in the flame (spectral range 190~270 nanometers). The UV tube will not detect sunlight or ordinary light shining on the refractory material in the furnace. Or the glow substance in the furnace reacts. The life of the UV tube is about 10,000 hours at an ambient temperature not exceeding 50°C. High ambient temperature has a great impact on its life. If it receives a sufficient amount of ultraviolet light, it can generate an electric current, and with appropriate amplification, a machine or a flame relay, it can close. If the power of the UV tube is exhausted, even if there is no ultraviolet light, it will still show that it has received ultraviolet light. In order to overcome this defect, the program controller will add an appropriate voltage to both ends of it before each turn on, so that even if When the power is exhausted, its signal will only indicate that there is no flame, so the programmable controller will immediately stop working. In order to test the effect of the UV electric eye, pull it out from its original position for at least one minute after ignition. After the UV electric eye is withdrawn, the ultraviolet rays emitted by the flame cannot be detected, the relevant relay is disconnected, and the burner stops working. Even a small amount of oil will block the passage of ultraviolet rays into the photoelectric tube, causing the internal sensing element to not receive a sufficient amount of ultraviolet rays and fail to work. Therefore the photocell must be thoroughly cleaned. The UV tube cannot feel sunlight or the light of ordinary lamps. Its sensitivity can be tested by using a flame or a spark between the two electrodes of an ordinary ignition transformer. To ensure that the burner works properly, its current must be stable and cannot be lower than the current required by the programmable controller. This current can be detected with a microammeter.
The computer calculates the digitized image information in the image memory according to certain ignition criteria to obtain the presence or absence (0N/OFF) signal of the burner flame and sends it to the FSSS.