Page 124 - Root Cause Failure Analysis

CONVEYORS

Conveyors are used to transport materials from one location to another within a plant
or facility. The variety of conveyor systems is almost infinite, but the two major classi-
fications used in typical chemical plants are pneumatic and mechanical. Note that the
power requirements of a pneumatic-conveyor system are much greater than for a
mechanical conveyor of equal capacity. However, both systems offer some advantages.

PNEUMATIC

Pneumatic conveyors are used to transport dry, free-flowing, granular material in sus-
pension within a pipe or duct. This is accomplished by the use of a high-velocity air-
stream or by the energy of expanding compressed air within a comparatively dense
column of fluidized or aerated material. Principal uses are (1) dust collection; (2) con-
veying soft materials, such as flake or tow; and (3) conveying hard materials, such as
fly ash, cement, and sawdust.

The primary advantages of pneumatic-conveyor systems are the flexibility of piping
configurations and their ability to greatly reduce the explosion hazard. Pneumatic
conveyors can be installed in almost any configuration required to meet the specific
application. With the exception of the primary driver, there are no moving parts that
can fail or cause injury. However, when used to transport explosive materials, the
potential for static charge buildup that could cause an explosion remains.

Configuration
A typical pneumatic-conveyor system consists of Schedule-40 pipe or ductwork,
which provides the primary flow path used to transport the conveyed material. Motive
power is provided by the primary driver, which can be either a fan, fluidizer, or posi-
tive-displacement compressor.

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