Application of Acoustic Agglomeration to Reduce Fine Particle Emissions from Coal Combustion Plants
Removal of fine particles (smaller than 2.5 μm) from industrial flue gases is, at present, one of the most important problems in air pollution abatement. These particles, which are hazardous because of their ability to penetrate deeply into the lungs, are difficult to remove by conventional separation technology. Sonic energy offers a means to solve this problem. The application of a high-intensity acoustic field to an aerosol induces agglomeration processes which changes the size distribution in favor of larger particles, which are then easier to precipitate with a conventional separator. In this work, we present a semiindustrial pilot plant in which this process is applied for reduction of particle emissions in coal combustion fumes. This installation basically consists of an acoustic agglomeration chamber with a rectangular cross-section, driven by four high-power and highly directional acoustic transducers of 10 and/or 20 kHz, and an electrostatic precipitator (ESP). In the experiments, a fluidized be...
SONOPROCESSING OF FLUIDS FOR ENVIRONMENTAL AND INDUSTRIAL APPLICATIONS
Ultrasonics processing is becoming an increasily attractive field due to the sustainable character of the use of ultrasonic waves: low energy consumption and no contaminating processes. However the applications of ultrasonic energy in fluids, and more specifically in gases, have been limited for the difficulty to generate efficiently such energy in large scale processes. To overcome this problem a new family of ultrasonic generators with extensive radiators were developed during the last years. Such new generators opened possibilities to study and implement new processes in fluids at industrial level. This paper deals with the characteristics and performance of some new sonoprocesses in gases and multiphase media developed at industrial and/or semi-industrial level for environmental and industrial applications.
New Trends in Electrostatic Precipitation: Wide Duct Spacing, Precharging, Pulse Energization
Increased research in electrostatic precipitation has resulted in the emergence of promising new technologies. In a new design concept already widely used in Japan, the precipitator duct spacing is increased from the traditional 200-300 mm up to 400-600 mm, and the precipitator voltage is raised correspondingly, with precipitator performance remaining almost unchanged for the same precipitator volume and the same gas flow. For suitable applications, this design results in reduced installation costs and easier maintenance. Various devices for precharging of high resistivity dust now under development improve particle charging and thereby enhance precipitator performance. Pulse energization improves the performance of precipitators collecting high resistivity dust by improving particle charging and current distribution and allowing regulation of the precipitator current independent of precipitator voltage.