Researches concerning the construction of ultrasonic gas filters

The paper presents a detailed analysis of the main disadvantages presented by the classic devices of filtration and purification of gases of any nature. Following the analysis of the main phenomena that occur in the propagation of ultrasounds through a gaseous medium: propagation velocity; compressing and scaling the environment according to the nature of ultrasonic waves; reflection and refraction of ultrasonic waves at the solid-gas interface; the creation of stationary waves and the emergence of pressure knots and antinodes; diffraction and diffusion of ultrasonic waves; attenuation of ultra-acoustic energy; ultraacoustic absorption; ultrasonic cavitation, etc. it is proposed to use the effects of their propagation in the filtration and purification process and the construction of ultrasonic filters operating on the principle of "ultrasonic agglomeration" on the principle of "ultrasonic shaking" or combined. The design of an ultrasonic filter in such a way that stationary waves allow it to retain the finest dust particles because in the pressure antinodes there is a phenomenon of coalescence involving the addition of fine particles to a larger particle (>10 mu m) which no longer represents a retention problem such that an ultrasonic filter has a retention depth of nearly 100%. During the propagation of the ultrasonic waves in the gaseous medium, compressions and dilatations are produced and the compression zone temperature becomes higher than in the scraping zone and hence in the depression area the extraction of the water from the environment takes place and in the compression zone it is being vaporized, therefore air drying is also carried out. By "ultrasonic agglomeration" of fine particles, their initial mass increases by coalescence of 2500 to 3500 times compared to the mass of the primary particles, being easily captured by the filter element, and by "ultrasonic shaking" the phenomenon of stomping of the cartridge filtering or clogging, performing cleaning during operation, without requiring interruption of gas transport and removal of the filter. Experimentally it was found that for a maximum filtration depth, increased efficiency of the filtration and purification process, a logical sequence of ultrasonic filters fitting their possibilities to completely retain the solid particles, to remove the water particles and to dry the gases. In the paper are presented four types of ultrasonic filters with possible use in gas filtration and purification: cyclone ultrasonic filter, vertical ultrasonic filter, ultrasonic horizontal conical filter and final ultrasonic filter, with their advantages and disadvantages.