High-frequency electro-thermal processing of secondary nonmetallic raw materials

• Main Authors: A. V. Livshits, N. G. Filippenko, A. N. Larchenko, S. N. Filatova
• Format: Article
• Language: Russian
• Published: MGTU im. N.È. Baumana 2014-01-01
• Series: Nauka i Obrazovanie
• Subjects: recycling of industrial waste; secondary raw materials; highfrequency equipment; plastic; drying materials
• Online Access: http://technomag.edu.ru/jour/article/view/621

<p>Despite a large number of studies in industrial waste processing, this field is still a challenge. In this regard, new processing capabilities emerging from the use of high frequency (RF) and microwave (MW) heat equipment are a positive factor to be researched.</p><p>In HF and MW processing the heating process is determined by absorption of electromagnetic wave power through the processed material. This electromagnetic wave power is transmitted by the substance atoms and spent for heating a sample, polarization, and initiation of chemical reactions. The non-conductor (dielectric and semiconductor) material heat is explained by the existing effect of dielectric losses due to losses caused by the through electrical conductivity and slow processes of polarization. The dielectric losses due to electrical conductivity result from the Joule heat released when through-current flows through the dielectric.</p><p>The differences in frequency radiation of HF and microwave equipment define their different technological capabilities. HF-radiation represents almost homogeneous field between the plates of a running capacitor. With multiple reflection from the chamber walls MW-radiation is randomly distributed within the chamber. Thus, radiation partly returns to the generator, thereby affecting the equipment performance capability and life time. Microwave heating is uneven. The depth of penetration into the material is much less to HF-processing. HF heating features are high penetration of radiation and uniform heating of the material. Together with pre-pressing it can afford an opportunity to join the non-standard pieces of plastic to have the larger insulating items.</p><p>The fact of the selective effect on the material is positive when processing the waste. Since the tangent of angle of dielectric losses of materials such as wood is directly proportional to humidity, the heating automatically stops as wood dries. This fact was used to produce for the fuel briquettes, which were modified by waste of polyethylene. Using the authors’ snap enables producing the sawdust briquettes with enhanced heat of combustion.</p><p>Using the waste of pulp and paper industry was successful in creating the arrays of hydrolytic lignin for their use as a fuel or an insulation material. The presence of temperature gradient contributed to the mass-transfer of low boiling and water-soluble compounds to the sample surface, and, thus, to its hardening. The thermal insulation properties of produced material are higher than those of wood, claydite-concrete, etc. thereby making it advanced for further research.</p><p>The article draws a conclusion from the theoretical and experimental studies that the use of НF power for of waste processing has unconditional prospects.</p>