Page 341 - Wastewater Solids Incineration Systems

302 Wastewater Solids Incineration Systems

FIGURE B.2 A progressing cavity pump with bridge-breaker (courtesy of Burl,
Washington).

2.2 Screw Conveyors
Screw conveyors are compact and may be used to convey solids horizontally and ver-
tically. They rotate in a stationary trough. There are two types of screw conveyors:
shaftless (see Figure B.3) and shafted. Both types are commonly used in bulk mate-
rial conveying applications. Unlike belt conveyors, screw conveyors may be
enclosed, reducing the potential for odors. Consistency of the material needs to be
considered, however; systems with a sticky consistency have had problems, particu-
larly in vertical applications.

2.3 Belt Conveyors
Belt conveyors have been used in many applications to convey solids from dewa-
tering to incineration, especially for MHFs because of low pressure of the feed loca-
tion. Belt conveyors come in varying types; flat belts are the most common but
ribbed belts are sometimes used, especially for inclines. Weight scales can be
installed to measure the quantity of solids conveyed. Because belt conveyors are
open, they can result in nuisance odors and require additional operator awareness
and safety precautions.