Electrostatic water treatment apparatus

Electrostatic water treating apparatus having a hollow charging electrode with an external impervious dielectric coating immersed in the water to be treated in which the interior of the electrode is kept dry by a water tight cap telescoped over the dielectric coating and having an O-ring seal with its wet side engaging the water and its dry side vented to the atmosphere.

This invention is intended to simplify the construction and increase the 
reliability of operation of electrostatic water treating apparatus by an 
improved structure for supporing the charging electrode and for preventing 
injury to the dielectric coating during assembly or disassembly for 
inspection and repair. In one form a water pipe may serve the function of 
the shell through which the water to be treated is conducted into contact 
with the charging electrode.

In a preferred form of apparatus for the electrostatic water treatment a 
hollow electrode 1 having an insulating coating 2 on its outer surface is 
positively charged by a high positive voltage (e.g. 1,000 to 12,000 
volts). The electrode is at the center of an externally grounded metal 
shell 3, and the water to be treated enters through a fitting 4 and leaves 
through a fitting 4a. While the annular stream of water flows past the 
electrode the positive charge on the electrode attracts free electrons 
from the water and minerals and causes electron collisions with mineral 
and biological material in the water. As a result, the mineral and 
biological materials settle out and may be periodically flushed down a 
drain. 
The lower end of the tubular electrode 1 is closed by a water tight end cap 
5 shown in larger scale in FIG. 3, having cylindrical side walls 6 
telescoped over the lower end of the tube. On the interior of the 
cylindrical side walls is an annular groove 7 for an O-ring 8 or other 
self energizing seal which excludes water from the interior of the 
electrode and keeps it dry. At the upper end of the cap are projections 9 
which bear on the inner surface of the shell 3 and positively center the 
electrode within the shell. When the apparatus has a larger diameter, and 
a greater clearance is provided between the electrode and the shell, 
projections 9 may be extended or other spacing means added so the 
electrode is maintained in a central position. This is important to avoid 
damage to the dielectric coating 2 by scratching or scraping against metal 
surfaces during insertion or removal of the electrode for inspection and 
replacement or repair. 
Since the interior of the electrode is dry and vented to the atmosphere, 
the water pressure acting on the end cap would blow the end cap off the 
lower end of the electrode unless some restraint were provided. In the 
structure of FIG. 1, this restraint is provided by a cover 10, permanently 
welded to the lower end of the shell 3 on which the end cap 5 rests. 
At the upper end of the electrode is a liquid tight cap 11 having 
cylindrical side walls 12 telescoped over the upper end of the electrode. 
The side walls 12 have an internal groove 13 for an O-ring 8A or other 
style of pressure energizing seal which positively seals water from the 
interior of the electrode. At the center of the cap is opening 14 which 
vents the interior of the electrode to atmosphere and also provides an 
opening for electrically connecting the charging voltage to the electrode. 
The upper or dry side of O-ring 8A is also vented through opening 14. The 
top cap 11 is secured to the upper end of the shell 3 by a standard 
coupling 15 which is available at ASME certified pressure ratings required 
by the pressure of the water being treated. The end thrust from water 
pressure on the top cap 11 is transferred to the coupling 15 and from the 
coupling to the shell 3. 
The structure eliminates the need for special closures and easily meets 
pressure vessel code requirements. The bottom end cap 5 can be assembled 
on the electrode outside the shell where the assembly can be watched and 
checked. Insertion of the electrode and end cap assembly into the shell 
does not result in scratching of the dielectric coating due to the 
centering effect of the end cap. 
In FIGS. 5 through 8 is shown water treatment apparatus which can be 
inserted in existing piping which functions as a shell for conducting the 
water to be treated over the charging electrode. This structure uses a 
hollow electrode 1a with the dielectric coating 2a. One end FIG. 7 of the 
electrode is closed by a liquid tight cap 5a having cylindrical walls 6a 
telescoped over the electrode and having an internal groove 7a for an 
O-ring providing a water tight seal to the outer surface of the electrode. 
Spacing rods 9a center the electrode within the pipe so as to maintain a 
uniform electrostatic field between the electrode and the pipe. At the 
other end of the pipe (FIGS. 5 and 6) is a liquid tight cap 5b having side 
walls 6b telescoped over the outer surface of the pipe and provided with 
an internal groove 7b for an O-ring which provides a positive water tight 
seal to the outer surface of the electrode. The cap 5b is centered by a 
spider 16 having spokes 17 fixed at the inner end to the cap 5b and at the 
outer end to a sealing ring 18 clamped between the pipe flanges 19. In one 
of the spokes of the spider is a hollow metal tube 20 opened at its inner 
end to the dry side of the cap 5b and at its outer end to the atmosphere. 
The tube 20 also vents the dry side of O-ring in groove 7 to the 
atmosphere. This hollow tube 20 provides a conduit for a wire 21 
connecting a high positive voltage D.C. to the electrode. 
End thrust due to water pressure on the caps 5a and 5b is taken by wires or 
rods 22 connected between the outer ends of the spacing members 9a and 17. 
These rods or cables are close to the inner surface of the pipe and have 
minimal effect upon the electrostatic field acting on the water.