1 Selection of different types of burners
1.1 Burners are divided into pressure atomization, medium atomization and tumbler atomization according to the atomization mode
(1) Pressure-type atomization is the mixture combustion with oxygen after the fuel is delivered to the nozzle by high-pressure pump. It is characterized by uniform atomization, simple work, less consumable products and lower cost. At present, most road construction machinery adopts this type of atomization model.
(2) Medium atomization is through 5 ~ 8kg of compressed air or with pressure vapor pressure to the nozzle periphery and fuel for premixed combustion, characterized by low fuel requirements (such as residue oil and other poor oil), but more consumables, the cost is increased, the road construction machinery industry is less use of this type.
(3) Turboscopic atomization is the process by which fuel is atomized by a high-speed turboscopic dish (about 6000 RPM).Can burn poor oil, such as high viscosity residue.But the model is expensive, and the rotating cup plate is easy to wear, the debugging requirements are very high.At present, the road construction machinery industry basically do not need this type of machine.
1.2 Burners can be divided into integrated gun type machine and split gun type machine according to the machine structure
(1) Integrated gun type machine is a combination of fan motor, oil pump, chassis and other control elements. Characterized by small volume and small adjustment ratio, generally 1:2.5, it mostly adopts high voltage electronic ignition system, which has lower cost but higher requirements on fuel quality and environment.Diesel-fueled equipment with output below 120t/h, such as Wiesel, Germany, can be used.
(2) Split gun machine is divided into four independent organs for main engine, fan, oil pump group and control components.It is characterized by large volume, large output power, the use of gas ignition system, relatively large regulation, generally 1:4 ~ 1:6, even up to 1:10, low noise, fuel quality and environmental requirements are not high.Domestic and foreign road construction industry mostly choose this type of machine, such as the UK "Park", Japan "Tanaka", Italy "ABS".
1.3 Structural composition of the burner
The automatic control burner can be divided into air supply system, fuel supply system, control system and combustion system.
(1) Sufficient oxygen shall be provided for complete combustion of the fuel in the air supply system. Different fuels have different air volume requirements. For example, 15.7m3/h of air shall be delivered for complete combustion of each kilogram of oil under standard pressure of No. 0 diesel.For complete combustion of heavy oil with calorific value of 9550Kcal/Kg, 15m3/h of air must be delivered.
(2) Fuel supply system To complete combustion fuel must be provided with a reasonable combustion space and mixing space.Fuel transport can be divided into high pressure transport and low pressure transport.The pressurized atomizing burner adopts the high-pressure conveying mode, and the pressure requirement is 15 ~ 28bar.The tumbler atomizing burner adopts low pressure conveying mode, and the pressure requirement is 5 ~ 8bar.At present, the fuel supply system of road building machinery industry mostly adopts high pressure transportation.
(3) Control system Road machinery industry, due to the particularity of its working conditions, choose the way of mechanical control, proportional control burners.
(4) The shape of the combustion system flame and the combustion completely depend on the combustion system.Generally, the flame diameter of the burner should be no more than 1.6m, and the width of the burner should be adjusted well, which is generally set at about 1:4 ~ 1:6.Too large flame diameter will cause serious carbon accumulation on the furnace tube, too long flame will lead to exhaust gas temperature exceeding the standard and damage the dust bag, will also coke material or material curtain covered with oil.Take our unit 2000 commercial concrete station as an example: the diameter of the drying cylinder is 2.2m and the length is 7.7m, so the maximum flame diameter should not be more than 1.5m, and the flame length should be adjustable within 2.5-4.5m.
2. Maintenance of burner
(1) Pressure regulating valve Regularly check the fuel pressure regulating valve or pressure reducing valve to determine whether the surface of the lock nut on the adjustable bolt is clean and removable.If the surface of the screw or nut is too dirty or rusty, repair or replace the regulating valve.
(2) Regularly check the oil pump to determine whether the sealing device is intact and the internal pressure is stable, and replace the damaged or leaking sealing device.When using hot oil, check that all tubing is well insulated.
(3) The filter installed between the tank and the oil pump shall be cleaned regularly and checked for excessive wear to ensure the smooth arrival of fuel from the tank to the oil pump and reduce the possibility of failure of potential components.The "Y" type filter on the burner should be cleaned frequently, especially when heavy oil or residuals are used, to prevent nozzle and valve clogging.When working, check the pressure gauge on the burner to see if it is within the normal range.
(4) For burners that require compressed air, check the pressure device to see if the required pressure is generated in the burner, clean all filters on the supply line and check the pipeline for leaks.
(5) Check whether the inlet protection device on the combustion and atomizing air blower is properly installed and whether the fan housing is free from damage and leakage.Observe the operation of the blade, when the noise is too large or vibration, the blade can be adjusted to eliminate.To the blower that belt wheel drives, want to lubricate bearing regularly and tighten belt, make sure blower can produce rated pressure.Clean and lubricate the air valve connection to see if it is smooth and replace parts if there is a malfunction.If the air pressure is too low, it will cause tempering, which will lead to overheating of the guide plate at the front end of the drum and the feeding plate in the combustion area. If the air pressure is too high, the current will be too large, and the temperature of the cloth bag will be too high or even burnt.
(6) The nozzle should be cleaned regularly and the spark gap of the ignition electrode should be checked (about 3mm).
(7) Always clean the flame detector (electric eye) to make sure whether the position is installed correctly, whether the temperature is appropriate, out of position and too high temperature will cause the photoelectric signal instability, or even break the fire.
Rational use of burning oil
Combustion oil is divided into light oil and heavy oil according to viscosity grade.Light oil can obtain good atomization effect without heating. Before using heavy oil or residuum, the oil should be heated to ensure that the oil viscosity is within the allowable range of the burner. The viscometer can be used to measure the results and find the best heating temperature of the fuel.Residue samples should be sent to the laboratory in advance for calorific value.
The burner should be checked and adjusted after heavy oil or residuum has been used for a period of time.Combustion gas analyzer can be used to determine whether the fuel is fully burned, and at the same time, check the drying drum and bag filter to see whether there is oil mist or oil smell, in order to avoid fire and grease blockage.The accumulation of grease on the atomizer will increase with the deterioration of the oil product, so it should be cleaned regularly.
When using residual oil, the outlet of the storage tank should be about 50cm higher than the bottom to avoid water and debris deposited at the bottom of the tank from entering the fuel line.Before the fuel enters the burner, it shall be filtered by a 40-purpose filter with an oil pressure gauge on each side of the filter to ensure that the filter works well and can be detected and cleaned in case of blockage.
In addition, after the end of the work, should first turn off the burner switch, then turn off the heavy oil heating, long time stop or cold oil should be switched oil valve, clean oil with light oil, otherwise it will cause oil blockage or difficult ignition.