Questions&Answers

Burner is the core component in the field of thermal engineering. Before all, you must establish a certain understanding of the concept and type of burner, if you want to engage in burner related work.

According to different properties, there is a variety of classification methods of burners.

Divided by fuel mode: oil burner, gas burner, dual fuel burner

Divided by combustion control mode: single stage fire burner, double stage fire burner, proportional control burner

Divided by fuel atomization mode: mechanical atomizing burner and medium atomizing burner

Divided by structure: Monoblock burner, Split-type burner

According to the more detailed classification standard, fuel oil combustion can be further divided into light oil burner, heavy oil burner, etc.; gas burner can be further divided into natural gas burner, liquefied gas burner, biogas burner, etc.

he split burner is mainly used in industrial production. Its main features are air supply system, combustion system, fuel delivery system and intelligent control system. Each system operates independently and is installed separately. Compared with the integral burner, the split burner is more suitable for large-scale equipment, high temperature and high pressure and other special conditions.

There are two basic conditions for the ignition of burners similar to that of internal combustion engines. One is well atomized fuel oil, and the other is high-pressure sparks. The former requires sufficient oil supply of the oil pump, stable injection pressure difference between the front and back of the nozzle, and fine oil mist. During ignition, the air supply should be small to prevent sparks and oil mist from blowing off; the latter requires that high-pressure sparks have enough ignition energy, the gap between the two ignition electrodes is 3-5mm, and the insulation between the two electrodes is good, so the sparks can smoothly skip the gap between the electrodes to ignite the diesel oil mist.

The common reason for the burner is not on fire is that there is no ignition high pressure. The first reason is that the ignition transformer is not energized (it may be that the relay in the power supply line or controller is in poor contact); the second one is that the insulation between the two thermal power poles is poor due to carbon deposition, and the high voltage is leaked, so there is no discharge spark. The distance between the ignition electrodes should be about 3mm, the distance between the ignition electrodes and the front end face of the nozzle should be about 5-7mm, and the insulation between the two electrodes must be good.

The possible causes include the blockage of the oil supply pipeline, the failure of the oil pump, and the leakage of the oil supply pipeline. Remove the high-pressure oil outlet pipe to check the pump oil condition. Normally, the oil column should be ejected outwards.

Another reason for the injector failure is that the fuel cut-off solenoid is not energized. When the oil cut-off solenoid valve loses power, even if the oil pump operates normally, the high-pressure end will not supply oil to the fuel injection nozzle. Only after the controller energizes the oil cut-off solenoid valve, can the diesel be ejected. The purpose is to prevent the original diesel stored in the furnace from deflagration in case of open fire. Under normal circumstances, the burner will conduct pre blowing before ignition, blow out the residual diesel in the combustion chamber, and then spray oil for ignition. In the pre blow stage, although the oil pump motor is running, the oil cut-off solenoid valve is not energized, and the high-pressure diesel oil pumped by the oil pump is cut off by the oil cut-off solenoid valve and cannot reach the fuel injection nozzle.

This is generally caused by insufficient fuel supply. If the diesel oil supply is not timely when the burner is working, it will inevitably lead to fire-fighting after oil cut-off. After the fire is extinguished, the flame sensor is in a high impedance state. The controller orders to stop the fuel injection and pre blow for about 10s, and then start the fuel injection. If the burner can be set up and reignited. If the diesel still cannot be supplied after the start of injection and the normal ignition cannot be achieved, the controller will automatically take measures to stop the injection and ignition after a delay of about 10s, and the air supply motor will also stop working and the red warning light will be on. After waiting for 1-2min, the thermal delay is over, and the red light can be reset manually to start the next ignition process automatically.

When the fuel oil supply is insufficient, the sound of "wheezing and wheezing" is often accompanied by the flame. At this time, the liquid in the oil supply pipeline may be accompanied by bubbles, which makes the injection pressure unstable and combustion unstable. In addition, when there is air bubble in the oil pipe, the running resistance of the oil pump will increase or decrease with it. When the fire is unstable, there is often black smoke.Because, the oil pressure can not be established when the oil supply is insufficient, so that the diesel fuel can not be completely combusted due to poor atomization.

The common causes of unstable fire are as follows:

When the oil pipe leaks, the external air will enter the oil pipe to form bubbles;

The oil pipe is narrow, blocked and compressed, which makes the oil path blocked and the diesel supply insufficient;

The filter screen of the oil supply system (including the inlet filter screen of the oil suction pipe, diesel filter element, oil pump filter screen, etc.) is blocked.

In winter, the oil supply system is often blocked, because of the poor fluidity of diesel oil when the temperature is low, it is easy to precipitate wax, which blocks the pipeline, diesel filter element, oil pump filter screen, nozzle filter screen, etc., making the oil supply system not smooth, causing unstable fire or fire fighting. If the temperature in the workshop is low, the oil supply pipeline can be heated with a baking lamp, especially the oil pump, filter element and other parts. When ignition is difficult, the air inlet can be baked to preheat the air inlet.

The diesel injected into the burner is mixed and burned at the same time. When the air supply is appropriate, the atomized CO2 and steam exhaust are colorless. When the air supply is insufficient, it will cause the incomplete combustion of diesel oil to generate CO and carbon particles, which will lead to black smoke. However, if the intake air volume is too large and strong, the oil mist that is too late to burn may be blown away, forming a white smoke discharge.

The common reason for black smoke is that the opening of combustion air inlet valve is too small, and the common reason for white smoke is that the opening of air inlet valve is too large. In both cases, the air inlet valve should be readjusted. When adjusting, you can observe the exhaust smoke color and adjust the opening of the damper until the exhaust smoke color is close to colorless.

Another reason for the black smoke is the poor atomization of diesel oil, which contains large droplets and cannot be fully mixed with air, resulting in black smoke due to incomplete local combustion.

The causes of poor diesel atomization are as follows:

The atomization capacity of the nozzle decreases seriously due to aging or clogging;

The oil pump outlet pressure is too high or too low.

The atomization effect is poor due to the low oil pressure of the nozzle caused by low pressure of the oil pump. But if the pressure of the oil pump is too high, the injection pressure will also be low. Because, the oil delivery volume of the oil pump is inversely proportional to the oil delivery pressure. If the oil pressure is too high, the oil delivery volume must be reduced. Because, the orifice of the nozzle is constant, the pressure difference between the two ends of the nozzle will be reduced, resulting in black smoke. This is due to the poor atomization of the oil supply. The oil outlet pressure of the oil pump can be adjusted according to the exhaust smoke color. Turn the pressure regulating screw clockwise to increase the oil output and decrease it; otherwise, the oil output will increase when the pressure drops.

One of the reasons for this typical failure is that the flame sensor of the burner accessories is contaminated.

The flame sensor is a photosensitive resistor. When it is exposed to light, its resistance value drops, showing a low impedance state; when there is no light, the resistance value rises, showing a high impedance state. The controller in the burner judges whether the combustion process continues according to the resistance value of the flame sensor. If the combustion stops and the flame sensor has a high impedance, stop the fuel supply immediately to prevent the accumulation of unburned diesel fuel.

The flame sensor probe is located in the air duct of the burner. Due to the smoke, tempering, air dust and other reasons, the surface of the flame sensor is easy to be dirty and thus lose the photosensitive function. Check the sensor probe and clean its surface with alcohol or detergent if necessary.

What should be done when the burner fails to start and work，after installation of burner and other related equipment.

Common causes

1.The power supply is not connected properly

2.No gas or low gas pressure

Solutions

1.Check the fuse of the program controller. Check the wiring of the temperature controller.

2.Check the valve device on the air supply pipeline has been opened.

Since gas burners use flammable and explosive gases such as natural gas, biogas, liquefied petroleum gas, coal gas, etc., they need to be inspected in detail before they are officially commissioned and put into use. The following three aspects require special attention:

1.Check whether the installation of gas pipeline is reasonable.

2.Check for leaks in the gas pipeline.

3.Check the gas delivery pipeline is kept clean and unobstructed, and the valve has been opened.

4.Completely deflate and evacuate the pipeline in front of the gas valve to ensure that no air is mixed in the fuel delivery pipeline.

5.Check the exhaust pipe has been connected to the outdoor.