Heavy oil is generally made cracking of heavy oil, heavy pressure, reduced crude oil or wax to blend in different proportions. In the selection, the general requirements should be high calorific value, good combustion performance, moderate viscosity, low corrosive and solid impurities, easy to store and transport.
1, the viscosity
Viscosity said fuel flow performance is good or bad, the greater the viscosity, atomization worse, is the most important indicator of quality heavy oil and the use of performance indicators, directly affect the oil pump, fuel consumption efficiency and injectors. With increasing temperature, the viscosity of heavy oil is gradually reduced, thus the high-viscosity oil to smoothly transport and atomization must be heated up.
Therefore, in the selection of oil, in addition to conventional indicators to understand the oil, but also must understand the viscosity of the oil - temperature curve, ensuring that the heating can achieve the viscosity of heavy oil burner before atomization required. For mechanical atomizer burner nozzle before its optimal fuel viscosity is 2.5 ~ 3.5 ° Et, high-pressure air atomizing burner optimum fuel viscosity 4.5 ~ 5.8 ° Et.
(Expressed in units of viscosity has a viscosity (° Et) and kinematic viscosity νt (mm2 / s, also known as centistokes cSt) two, the conversion relationship is: νt = 7.310 ° Et-6.31 / ° Et)
2, the amount of sulfur
In heavy oil, the sulfur can be in various forms of elemental, compounds exist. After the burning of sulfur-generated SO2, SO3, etc. into the atmosphere will seriously pollute the environment, combined with water vapor to produce highly corrosive sulfurous acid, sulfuric acid, etc., for flue dust, fan life impact. In addition, the impact on oil sulphide pipes, valves, pumps, seals, and others have varying degrees of gun. Therefore, the choice of heavy oil, the sulfur content as low as possible, generally less than 3%.
3, mechanical impurities
Mechanical impurities clogging the filter, spray gun, valve, accelerating pump, nozzle wear seriously affect the mechanical life, which generally requires mechanical impurity content is less than the fuel 0.5 to 1%.
4, the flash and fire
Flash and fire are important indicators of fire and explosion safety of the fuel, the higher the temperature, the better. When choosing oil, we must know the flash and fire to determine the heating temperature. In the non-pressure storage tanks of heavy oil opening, the heating temperature should be below the flash point of 10 ~ 20 ℃, which can effectively prevent fire.
5, the heat (calorific value)
Heat is an important economic indicator of fuel, and asphalt plant is directly related to fuel consumption, the higher the heat, the better. Typically low heat oil is 38.5 ~ 44MJ/kg.
6, the water content
Water is one of the main impurities in the fuel, which not only reduce the amount of combustible components of the fuel, and the fuel on fire difficult. Excessive moisture will increase the pipeline and equipment corrosion, increase heat losses and transportation energy consumption, while the moisture content will cause uneven flame pulsation even stall. Fuel should be used before the dehydration treatment, the moisture content should be controlled generally between 1% to 3%.