ABOUT THE REASONS FOR THE CHANGE IN THE MECHANICAL PROPERTIES OF PAPER ASHLESS FILTERS DURING THEIR PROCESSING IN A UNIPOLAR CORONA DISCHARGE

The article presents the study results of the structure and properties of paper ashless filters "Blue tape". It is shown that the "Blue tape" filter paper has a fairly high density with a relatively small number and size of voids (pores) between the fibers. When processing filters in the corona discharge field, an increase in their mechanical properties by 3.5–6% is observed, this is mainly due to the strengthening of the interfiber bond forces. The implementation of increased electrostatic bonding forces in the sheet structure leads to an increase in the resistance to the external tensile force necessary to break the paper filter. The observed dependences are associated with the orientation and ordering of the pulp and paper material structural elements, with an increase in the potential of the double electric layer on the fibers surface under the charge action carriers injected into the paper volume from the corona discharge and with the formation of a hetero charge due to the orientation of the polar cellulose groups and macromolecule segments during electreting. This is confirmed by the increase in the ζ – potential of the fibers of filters during processing in a negative corona discharge - it was found that the zeta – potential value of electret ashless filters is 18% higher than for the initial ones. The achieved results of increasing the ashless filters physico- mechanical properties will increase the efficiency of their use.

The Influences of Acoustic and Pulsed Corona Discharge Coupling Field on Agglomeration of Monodisperse Fine Particles

In view of the low efficiency of traditional electrostatic precipitators in removing fine particles, acoustic and pulsed corona discharge coupling fields were proposed to increase particle size. In this paper, monodisperse particles with three different sizes (0.5 μm, 2 μm, and 4 μm) were generated to investigate the agglomeration effect under different parameters in external fields. A larger reduction ratio of particle number concentration resulted in a higher agglomeration efficiency. Results indicated that, in the range from 800 to 2400 Hz, the acoustic agglomeration effect on 4-μm particles was better than that on 0.5-μm and 2-μm particles. In the pulsed corona discharge field, agglomeration efficiencies of the three particle sizes were lower than those in the acoustic field. However, application of the coupling field highly improved agglomeration efficiency compared with the single field. When a pulse input voltage of 50 kV with acoustic sound pressure level (SPL) of 143 dB and frequency of 1600 Hz was selected, the corresponding number reduction ratio of 0.5-μm, 2-μm, and 4-μm particles increased to 0.464, 0.526, and 0.918 from 0.254, 0.438, and 0.814 in the acoustic wave field and 0.226, 0.385, and 0.794 in the pulsed corona discharge field.