Principle of Multi-Pollutants Removal Technology in Flue Gas by Ozone - Simultaneous Multi-Pollutants Removal in Flue Gas by Ozone - page 35

pulse corona/streamer discharge, mixed discharge, and glow discharge. In recent
years, numerous theoretical studies, technological improvements, and new
attempts have been conducted to improve the ozone generation efficiency. Most of
them give prominence to the following aspects.

2.3.1 Electrode Type

Investigations into various electrodes (including linear, brush-like, spiral, mesh,
rotating, and water electrodes) has been performed so as to improve the discharge
condition and efficiency. Fig. 2.3 presents various electrode forms [11,12] .
Gibalov and Pietsch [13,14] theoretically and experimentally analyzed the
electric field, neutral particles, charged particles, and energy density distribution
of the coplanar dielectric barrier discharge (DBD) (Fig. 2.4) in correlation to space
and time. It was found that the electric field intensity ranged from 70 - 100 TD
when the gas source was air or pure oxygen. Boonseng . [15] developed a new

ozone generator with a brush-like electrode (the structure shown in Fig. 2.5) for
water treatment. Because the brush-like electrode increased the ionization area and
power, a strong non-uniform electric field thus developed and the ozone
generation efficiency increased. It was found that under circumstances with the
voltage and frequency of 15 kV and 20 kHz, the ozone concentration reached 64
ppm and ozone production efficiency exceeded 716 mg/(kWh). Within a
tube-type reactor (Fig. 2.6), Yehia's group [16-18] focused on comparing the ozone
production with respect to the electrode structure (including the wire-pipe,
wire-rectangular, and coaxial-tube types). Given the same wire diameter, discharge
power, and flow rate, a wire-tube-type electrode structure results in a larger
discharge current and higher ozone concentration, compared with a
wire-rectangular type, regardless of the alternating current (AC) or direct current
(DC) power source used. Among the three electrode structures, the coaxial-tube
type with silent discharging results in the highest ozone concentration, regardless
of the size of the wire and width of the gap used.

et al