As a mechatronic equipment with a high degree of automation, the burner can be divided into five major systems based on its functions: air supply system, ignition system, monitoring system, fuel system, and electronic control system.
1. Air supply system
The function of the air supply system is to deliver air with a certain wind speed and volume into the combustion chamber. Its main components are: casing, fan motor, fan impeller, air gun fire tube, damper controller, damper baffle, and diffusion plate.
Shell: It is the main component of the mounting bracket for each component of the burner and the fresh air inlet channel. From the appearance point of view, it can be divided into two types: box type and gun type. Most box type burners have an outer cover of injection molded material, and the power is generally small. Most high-power burners use split shells, usually gun type. The material of the shell is generally high-strength lightweight alloy castings.
Fan motor: It mainly provides power for the operation of the fan impeller and high-pressure oil pump. Some burners also use a separate motor to provide power for the oil pump. Some low-power burners use single-phase motors, which have relatively small power. Most burners use three-phase motors. The motor can only operate normally if the motor rotates in a certain direction.
Fan impeller: generates enough wind pressure through high-speed rotation to overcome the resistance of the furnace and chimney, and blows enough air into the combustion chamber to meet the needs of combustion. It consists of a cylindrical wheel equipped with blades with a certain tilt angle. The material is generally high-strength lightweight alloy steel, and there are also injection molded products. All qualified fan impellers have good dynamic balance performance.
Air gun fire tube: It plays the role of guiding air flow and stabilizing wind pressure. It is also an integral part of the air inlet channel. Generally, there is a jacket flange connected to the furnace mouth. Its constituent materials are generally high-strength and high-temperature-resistant alloy steel.
Damper controller: It is a driving device that controls the rotation of the damper baffle through a mechanical linkage.
There are generally two types of hydraulic drive controllers and servo motor drive controllers. The former works stably and is less prone to malfunctions, while the latter has precise control and smooth changes in air volume.
Damper baffle: Its main function is to adjust the size of the air inlet channel to control the amount of air inlet. Its composition materials include injection molding and alloy. Injection molding baffles are generally in the form of a single piece, and alloy baffles are available in various combinations such as single piece, double piece, and triple piece.
Diffusion plate: Its special structure can generate rotating airflow, which helps to fully mix air and fuel, and also regulates the secondary air volume.
2. Ignition system
The function of the ignition system is to ignite the mixture of air and fuel. Its main components are: ignition transformer, ignition electrode, and electric fire high-voltage cable.
Ignition transformer: It is a conversion component that generates high-voltage output. Its output voltage is generally: 2×5KV, 2×6KV, 2×7KV, and the output current is generally 15~30mA.
Ignition electrode: Converts high-voltage electrical energy into light energy and heat energy through arc discharge to ignite fuel. Generally, there are two types: single type and split type.
Electric fire high-voltage cable: Its function is to transmit electrical energy.
3. Monitoring system
The function of the monitoring system is to ensure the safe operation of the burner. Its main components include flame monitors, pressure monitors, monitoring thermometers, etc.
Flame monitor: Its main function is to monitor the formation of flame 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 functions and working principles 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 it receives, the lower the resistance. When the voltage applied to both ends of the photoresistor At a certain time, the current in the circuit is higher. When the current reaches a certain value, the flame relay is activated, allowing the burner to continue working 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 lines is connected to the ground, and the other is connected to the ignition electrode. The discharge between the electrode and the earth generates sparks, igniting 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 reversing the input of the ignition transformer, because reversing the wires will cause the ignition
The direction of the alternating current of the transformer is rotated 180°, and the direction of the ignition current generated is also rotated 180°.
If the two current directions are consistent, the above defects will be overcome. In addition, the flame in the ionization zone is unstable
It will also cause the burner to be disconnected when the flame is still there. It may be because the air-gas ratio is not appropriate.
It can be solved by adjusting the air volume or gas volume. It may also be caused by uneven distribution of air and gas on the combustion head.
Uniformity can be solved by adjusting the position of the combustion head.
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. Excessive ambient temperature has a great impact on its life. If it receives a sufficient amount of ultraviolet rays, it can generate an electric current, and with appropriate amplification, a machine or flame relay can cause it to 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 stop working immediately. 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 pulled out, 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, and its value cannot be lower than the pressure monitor: generally used for gas burners, mainly gas high pressure, low pressure monitoring, and wind pressure monitoring. If the burner is used for steam boilers, there is also steam pressure monitoring. .
Temperature monitor: mainly includes monitoring and control of flue gas temperature, monitoring and control of fuel (heavy oil) temperature, and monitoring and control of system water and medium water temperature.
4. Fuel system
The function of the fuel system is to ensure that the burner burns the fuel it needs. The fuel system of the oil burner mainly includes: oil pipes and joints, oil pump, solenoid valve, nozzle, and heavy oil preheater. Gas burners mainly include filters, pressure regulators, solenoid valve groups, and ignition solenoid valve groups.
Oil pipes and joints: used to transfer fuel.
Oil pump: A mechanism that generates pressure oil. The output oil pressure is generally above 10 bar to meet the requirements of atomization and fuel injection volume. It is divided into single-tube output and double-tube output. Some burner oil pumps are coaxially connected to the fan motor, and some have separate oil pump motor drives. Common oil pumps include J-type, E-type and TA-type, which are suitable for single-pipe and double-pipe oil systems. The oil pump contains a filter, pressure regulating valve and stop valve. The filter mainly protects the transmission mechanism. The E-type pump filter has a larger mesh. When the filter is clogged, it will cause excessive vacuum. The filter must be cleaned regularly. After cleaning or replacing the filter, the pump cover must be tightly sealed. Before the oil pump is operated, the suction side oil pipe must be filled with oil until the pump overflows. Otherwise, the pump will be damaged due to dry operation. The suction resistance of the oil pump suction port cannot exceed 0.4bar, and the pressure at the output port is generally 10~24bar. The maximum oil supply pressure of the J-type pump is 20bar, the maximum oil supply pressure of the E-type and TA-type pumps is 40bar, and the maximum oil supply temperature is 90°C.
Solenoid valve: used to control the on and off of the oil circuit, mostly two-way valves and three-way valves.
Nozzle: Its main function is to atomize oil droplets. The main parameters of the oil nozzle include injection angle (30°, 45°, 60°, 80°), injection mode (solid, hollow, semi-hollow) and fuel injection volume. Under the same pressure, a nozzle with a smaller injection volume has better atomization effect. Commonly used nozzles include simple mechanical atomization nozzles and oil return mechanical atomization nozzles. The former has a simple structure, simple system, and is relatively reliable. It is generally used for burners with smaller loads. The latter has a more complex structure and system, but It has good adjustment characteristics and is suitable for use when the boiler load often has a large range of adjustment. Simple mechanical atomization nozzles include tangential groove type and tangential hole type. The former has a larger atomization angle and smaller atomized particles.
Heavy oil preheater: A unique device for heavy oil burners. It is used to heat heavy oil to a certain temperature and reduce the viscosity to increase the atomization effect of heavy oil. Its temperature control device is interlocked with the burner control circuit.
Filter: Its function is to prevent impurities from entering the solenoid valve group and burner.
Pressure regulator: Its main function is to reduce and stabilize pressure. It is generally used in high-pressure gas supply systems. Its inlet pressure cannot be less than 100mbar.
Solenoid valve group: It is generally composed of a safety solenoid valve and a main solenoid valve. There are split and integrated types. The integrated solenoid valve group is usually also combined with a pressure stabilizing valve and a filter. Safety solenoid valves are generally quick-opening and quick-closing. The main solenoid valve is generally a two-stage type, and can be divided into quick-opening and quick-closing types and slow-opening and quick-closing types.
Solenoid valve leakage detector: Its function is to detect whether the solenoid valve group is closed tightly. Generally used on burners with power greater than 1400kw.
Ignition solenoid valve group: generally consists of a manual ball valve, a voltage regulator, and a solenoid valve. Mainly used for burners with higher power.
5. Electronic control system
The electronic control system is the command center and contact center of each of the above systems. The main control component is a programmable controller. Different programmable controllers are equipped for different burners. Common programmable controllers are: LFL series, LAL series, LOA series, LGB series , the main difference is the time of each program step.
Introduction to burner working process
Taking the proportional gas burner as an example, its working process has four stages: preparation stage, pre-purge stage, ignition stage and normal combustion stage.
Preparation stage: After the program controller is powered on, it starts the internal program self-test. At the same time, the servo motor drives the damper to the closed state. After the program self-test is completed, it is in the standby state. When the thermostat, over-high or low gas pressure switch, steam boiler steam When the pressure switch and other limit switches allow, the program controller starts and enters the pre-purge stage. If the solenoid valve group is equipped with a leakage detection system, the system will first perform valve leakage detection when the above-mentioned limit switch allows it. After the detection passes, it will enter the pre-purge stage.
Pre-purge stage: The servo motor drives the damper to the high fire opening state, and at the same time the fan motor starts to blow in air for pre-purge. Depending on the program controller, after about 20 to 40 seconds of purging, the servo motor drives the damper to ignition. Open state, ready to ignite. During the entire pre-purge stage, the air pressure switch measures the air pressure. Only when the air pressure is maintained at a high enough level can the pre-purge process continue.
Ignition stage: After the servo motor drives the damper to the ignition opening state, the ignition transformer cuts in and outputs high voltage to the ignition electrode to generate ignition sparks. After about 3 seconds, the program controller sends power to the safety solenoid valve and proportional solenoid valve. , after the valve is opened, the gas reaches the combustion head, mixes with the air provided by the fan, and then is ignited. Within 2 seconds after the valve is opened, the ionization electrode should detect the presence of flame. Only in this way, the program controller will continue the subsequent program. Otherwise, the program controller will lock and disconnect the solenoid valve to stop the gas supply and alarm at the same time.
Normal combustion stage: After a few seconds of normal ignition and stable combustion, the servo motor drives the damper to the high fire opening state. At the same time, the servo motor of the proportional gas regulating valve cuts in and adjusts the gas valve behind the gas valve according to the air pressure and furnace back pressure. Gas pressure is used to adjust the gas volume to achieve stable and efficient combustion. Thereafter, the burner automatically switches between small and large fires and shuts down according to the requirements of each limit switch. In addition, an ionization electrode and an air pressure switch monitor the burner throughout the combustion process.
Common fault phenomena, causes and solutions
In the event of a malfunction, you must first check whether the conditions for normal operation of the burner are met:
1. Is the power supply normal?
2. Is the fuel supply system normal? For example, is the gas pressure on the gas supply pipeline normal and is the ball valve open (gas machine)? Is there oil in the tank and is the valve on the oil supply and return pipe open (oil engine)?
3. Are the adjustments and interlock controls of all regulators and controllers normal? Such as temperature regulator, water flow switch, water level switch, oil level switch, gas pressure switch, etc.
4. Has the amount of air, gas or fuel during combustion been changed?
If it is determined that the fault is not caused by the above reasons, the relevant functions of the burner must be checked and tested. The general method is to remove some interlock controls, turn on the burner, and then accurately observe the following working processes. Based on the phenomenon, the problem can be quickly discovered and eliminated.
As a mechatronic equipment with a high degree of automation, the burner can be divided into five major systems based on its functions: air supply system, ignition system, monitoring system, fuel system, and electronic control system.
1. Air supply system
The function of the air supply system is to deliver air with a certain wind speed and volume into the combustion chamber. Its main components are: casing, fan motor, fan impeller, air gun fire tube, damper controller, damper baffle, and diffusion plate.
Shell: It is the main component of the mounting bracket for each component of the burner and the fresh air inlet channel. From the appearance point of view, it can be divided into two types: box type and gun type. Most box type burners have an outer cover of injection molded material, and the power is generally small. Most high-power burners use split shells, usually gun type. The material of the shell is generally high-strength lightweight alloy castings.
Fan motor: It mainly provides power for the operation of the fan impeller and high-pressure oil pump. Some burners also use a separate motor to provide power for the oil pump. Some low-power burners use single-phase motors, which have relatively small power. Most burners use three-phase motors. The motor can only operate normally if the motor rotates in a certain direction.
Fan impeller: generates enough wind pressure through high-speed rotation to overcome the resistance of the furnace and chimney, and blows enough air into the combustion chamber to meet the needs of combustion. It consists of a cylindrical wheel equipped with blades with a certain tilt angle. The material is generally high-strength lightweight alloy steel, and there are also injection molded products. All qualified fan impellers have good dynamic balance performance.
Air gun fire tube: It plays the role of guiding air flow and stabilizing wind pressure. It is also an integral part of the air inlet channel. Generally, there is a jacket flange connected to the furnace mouth. Its constituent materials are generally high-strength and high-temperature-resistant alloy steel.
Damper controller: It is a driving device that controls the rotation of the damper baffle through a mechanical linkage.
There are generally two types of hydraulic drive controllers and servo motor drive controllers. The former works stably and is less prone to malfunctions, while the latter has precise control and smooth changes in air volume.
Damper baffle: Its main function is to adjust the size of the air inlet channel to control the amount of air inlet. Its composition materials include injection molding and alloy. Injection molding baffles are generally in the form of a single piece, and alloy baffles are available in various combinations such as single piece, double piece, and triple piece.
Diffusion plate: Its special structure can generate rotating airflow, which helps to fully mix air and fuel, and also regulates the secondary air volume.
2. Ignition system
The function of the ignition system is to ignite the mixture of air and fuel. Its main components are: ignition transformer, ignition electrode, and electric fire high-voltage cable.
Ignition transformer: It is a conversion component that generates high-voltage output. Its output voltage is generally: 2×5KV, 2×6KV, 2×7KV, and the output current is generally 15~30mA.
Ignition electrode: Converts high-voltage electrical energy into light energy and heat energy through arc discharge to ignite fuel. Generally, there are two types: single type and split type.
Electric fire high-voltage cable: Its function is to transmit electrical energy.
3. Monitoring system
The function of the monitoring system is to ensure the safe operation of the burner. Its main components include flame monitors, pressure monitors, monitoring thermometers, etc.
Flame monitor: Its main function is to monitor the formation of flame 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 functions and working principles 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 it receives, the lower the resistance. When the voltage applied to both ends of the photoresistor At a certain time, the current in the circuit is higher. When the current reaches a certain value, the flame relay is activated, allowing the burner to continue working 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 lines is connected to the ground, and the other is connected to the ignition electrode. The discharge between the electrode and the earth generates sparks, igniting 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 reversing the input of the ignition transformer, because reversing the wires will cause the ignition
The direction of the alternating current of the transformer is rotated 180°, and the direction of the ignition current generated is also rotated 180°.
If the two current directions are consistent, the above defects will be overcome. In addition, the flame in the ionization zone is unstable
It will also cause the burner to be disconnected when the flame is still there. It may be because the air-gas ratio is not appropriate.
It can be solved by adjusting the air volume or gas volume. It may also be caused by uneven distribution of air and gas on the combustion head.
Uniformity can be solved by adjusting the position of the combustion head.
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. Excessive ambient temperature has a great impact on its life. If it receives a sufficient amount of ultraviolet rays, it can generate an electric current, and with appropriate amplification, a machine or flame relay can cause it to 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 stop working immediately. 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 pulled out, 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, and its value cannot be lower than the pressure monitor: generally used for gas burners, mainly gas high pressure, low pressure monitoring, and wind pressure monitoring. If the burner is used for steam boilers, there is also steam pressure monitoring. .
Temperature monitor: mainly includes monitoring and control of flue gas temperature, monitoring and control of fuel (heavy oil) temperature, and monitoring and control of system water and medium water temperature.
4. Fuel system
The function of the fuel system is to ensure that the burner burns the fuel it needs. The fuel system of the oil burner mainly includes: oil pipes and joints, oil pump, solenoid valve, nozzle, and heavy oil preheater. Gas burners mainly include filters, pressure regulators, solenoid valve groups, and ignition solenoid valve groups.
Oil pipes and joints: used to transfer fuel.
Oil pump: A mechanism that generates pressure oil. The output oil pressure is generally above 10 bar to meet the requirements of atomization and fuel injection volume. It is divided into single-tube output and double-tube output. Some burner oil pumps are coaxially connected to the fan motor, and some have separate oil pump motor drives. Common oil pumps include J-type, E-type and TA-type, which are suitable for single-pipe and double-pipe oil systems. The oil pump contains a filter, pressure regulating valve and stop valve. The filter mainly protects the transmission mechanism. The E-type pump filter has a larger mesh. When the filter is clogged, it will cause excessive vacuum. The filter must be cleaned regularly. After cleaning or replacing the filter, the pump cover must be tightly sealed. Before the oil pump is operated, the suction side oil pipe must be filled with oil until the pump overflows. Otherwise, the pump will be damaged due to dry operation. The suction resistance of the oil pump suction port cannot exceed 0.4bar, and the pressure at the output port is generally 10~24bar. The maximum oil supply pressure of the J-type pump is 20bar, the maximum oil supply pressure of the E-type and TA-type pumps is 40bar, and the maximum oil supply temperature is 90°C.
Solenoid valve: used to control the on and off of the oil circuit, mostly two-way valves and three-way valves.
Nozzle: Its main function is to atomize oil droplets. The main parameters of the oil nozzle include injection angle (30°, 45°, 60°, 80°), injection mode (solid, hollow, semi-hollow) and fuel injection volume. Under the same pressure, a nozzle with a smaller injection volume has better atomization effect. Commonly used nozzles include simple mechanical atomization nozzles and oil return mechanical atomization nozzles. The former has a simple structure, simple system, and is relatively reliable. It is generally used for burners with smaller loads. The latter has a more complex structure and system, but It has good adjustment characteristics and is suitable for use when the boiler load often has a large range of adjustment. Simple mechanical atomization nozzles include tangential groove type and tangential hole type. The former has a larger atomization angle and smaller atomized particles.
Heavy oil preheater: A unique device for heavy oil burners. It is used to heat heavy oil to a certain temperature and reduce the viscosity to increase the atomization effect of heavy oil. Its temperature control device is interlocked with the burner control circuit.
Filter: Its function is to prevent impurities from entering the solenoid valve group and burner.
Pressure regulator: Its main function is to reduce and stabilize pressure. It is generally used in high-pressure gas supply systems. Its inlet pressure cannot be less than 100mbar.
Solenoid valve group: It is generally composed of a safety solenoid valve and a main solenoid valve. There are split and integrated types. The integrated solenoid valve group is usually also combined with a pressure stabilizing valve and a filter. Safety solenoid valves are generally quick-opening and quick-closing. The main solenoid valve is generally a two-stage type, and can be divided into quick-opening and quick-closing types and slow-opening and quick-closing types.
Solenoid valve leakage detector: Its function is to detect whether the solenoid valve group is closed tightly. Generally used on burners with power greater than 1400kw.
Ignition solenoid valve group: generally consists of a manual ball valve, a voltage regulator, and a solenoid valve. Mainly used for burners with higher power.
5. Electronic control system
The electronic control system is the command center and contact center of each of the above systems. The main control component is a programmable controller. Different programmable controllers are equipped for different burners. Common programmable controllers are: LFL series, LAL series, LOA series, LGB series , the main difference is the time of each program step.
Introduction to burner working process
Taking the proportional gas burner as an example, its working process has four stages: preparation stage, pre-purge stage, ignition stage and normal combustion stage.
Preparation stage: After the program controller is powered on, it starts the internal program self-test. At the same time, the servo motor drives the damper to the closed state. After the program self-test is completed, it is in the standby state. When the thermostat, over-high or low gas pressure switch, steam boiler steam When the pressure switch and other limit switches allow, the program controller starts and enters the pre-purge stage. If the solenoid valve group is equipped with a leakage detection system, the system will first perform valve leakage detection when the above-mentioned limit switch allows it. After the detection passes, it will enter the pre-purge stage.
Pre-purge stage: The servo motor drives the damper to the high fire opening state, and at the same time the fan motor starts to blow in air for pre-purge. Depending on the program controller, after about 20 to 40 seconds of purging, the servo motor drives the damper to ignition. Open state, ready to ignite. During the entire pre-purge stage, the air pressure switch measures the air pressure. Only when the air pressure is maintained at a high enough level can the pre-purge process continue.
Ignition stage: After the servo motor drives the damper to the ignition opening state, the ignition transformer cuts in and outputs high voltage to the ignition electrode to generate ignition sparks. After about 3 seconds, the program controller sends power to the safety solenoid valve and proportional solenoid valve. , after the valve is opened, the gas reaches the combustion head, mixes with the air provided by the fan, and then is ignited. Within 2 seconds after the valve is opened, the ionization electrode should detect the presence of flame. Only in this way, the program controller will continue the subsequent program. Otherwise, the program controller will lock and disconnect the solenoid valve to stop the gas supply and alarm at the same time.
Normal combustion stage: After a few seconds of normal ignition and stable combustion, the servo motor drives the damper to the high fire opening state. At the same time, the servo motor of the proportional gas regulating valve cuts in and adjusts the gas valve behind the gas valve according to the air pressure and furnace back pressure. Gas pressure is used to adjust the gas volume to achieve stable and efficient combustion. Thereafter, the burner automatically switches between small and large fires and shuts down according to the requirements of each limit switch. In addition, an ionization electrode and an air pressure switch monitor the burner throughout the combustion process.
Common fault phenomena, causes and solutions
In the event of a malfunction, you must first check whether the conditions for normal operation of the burner are met:
1. Is the power supply normal?
2. Is the fuel supply system normal? For example, is the gas pressure on the gas supply pipeline normal and is the ball valve open (gas machine)? Is there oil in the tank and is the valve on the oil supply and return pipe open (oil engine)?
3. Are the adjustments and interlock controls of all regulators and controllers normal? Such as temperature regulator, water flow switch, water level switch, oil level switch, gas pressure switch, etc.
4. Has the amount of air, gas or fuel during combustion been changed?
If it is determined that the fault is not caused by the above reasons, the relevant functions of the burner must be checked and tested. The general method is to remove some interlock controls, turn on the burner, and then accurately observe the following working processes. Based on the phenomenon, the problem can be quickly discovered and eliminated.