Due to the high viscosity and high colloid of the heavy fuel oil, those characteristice will directly affect the combustion performance, the decrease of the fuel oil atomization, incomplete combustion, the increase of harmful gas, nozzle easy coking and so on. How to improve the quality of the spray nozzle and the corresponding combustion efficiency and energy saving has become one of the main direction of research. For nozzle, within the required coverage, we want to get as far as possible fine droplets, which can help to accelerate combustion. With the rapid development of science and technology, there are more suitable fuel oil atomization technology, namely the research of hard carbide ultrasonic atomization nozzle. Ultrasonic atomization technology of atomized particle size smaller (usually under 100 microns), the uniformity of droplets is also very good (usually greater than 2 N values, a common burner N value, 1.1 to 1.7). Therefore, the ultrasonic atomizer can not only improve the combustion efficiency and reduce emissions of soot, nitrogen oxides, but also low oxygen combustion, conserve energy and protect environment. Due to the ultrasonic atomization mechanism is complicated, there are still some problem in practice so that they couldn't be widely used.
For ultrasonic atomizing burner, it can also be divided into dynamic and fluid power according to the ultrasonic sound source. The electrodynamic carbide ultrasonic atomization nozzle of ultrasonic generator are independent of atomizer set separately. When the fuel moves from liquid pipe nozzle into the front end, thanks to the influence of surface tension and affinity, it will form a layer of film after under the effect of ultrasonic atomization. The atomizer structure is compact and the adjusting range is extensive, which is suitable for small oil atomizer, while the fixing cost of the installing of the electrical equipment is higher.
Another fluid power type carbide ultrasonic atomization nozzle ultrasonic generator set in the nozzle, the principle of which is to use the jet of high speed jet impact excitation vibration resonance cavity, high intensity of the sound waves, which provide gas in the fuel injection and combustion noise vibration, spray combustion and high efficiency. Because of its wide working pressure, when the airflow is in subsonic or supersonic condition, there will be high pressure. As a result, nozzle has large capacity, relatively-simple structure and lower cost. So they have widely application prospect.
According to the related theoretical analysis and experimental research for dynamic ultrasonic atomization, we will use the computer image processing technology research focusing on the performance of piezoelectric transducer parameter, frequency and amplitude of driving voltage, the jet diameter and speed. The higher the excitation voltage is, the easier the jet fracture is. Improving the excitation voltage can improve the working conditions of cemented carbide spray nozzle. In addition, the nozzle cavity vertical gap exists the optimum value. The closer the clearance value stream is, the easier it breaks. The smaller the diameter of the nozzle is, the easier it forms droplets, and then it is easy to weaken the influence of other parameters and is prone to plug the nozzle. And the fluid-power type carbide depends on the audio frequency vibration of the air velocity and atomizer export structure. And there exists a critical value. If the air velocity is higher than the critical value, atomization quality will be improved significantly. On the other hand, the effect is not obvious.