In a wire-pipe ESP, a wire that functions as the discharge electrode runs through the axis of a
long pipe, which serves as the collection electrode. The weighted wires are suspended from a frame in
the upper part of the ESP. The pipes can be cylindrical, square, or hexagonal. An example of a wirepipe
design is provided in Figure 5.2-3. Previously, only cylindrical pipes were used; square and
hexagonal pipes have currently grown in popularity. The space between cylindrical tubes creates a
great deal of wasted collection area. Square and hexagonal pipes can be packed closer together, so
that the inside wall of one tube is the outside wall of another.4 This situation is illustrated in Figure