TM 5-815-1/AFR 19-6
distributions are determined by gas sampling
inlet ductwork and the outlet ductwork. This pressure
and generally conform to statistical
drop is a result of entrance and exit losses, frictional
distributions. See figure 6-8.
losses and loss of rotational kinetic energy in the
(2) A fractional cyclone efficiency curve is used
exiting gas stream. Cyclone pressure drop will increase
to estimate what weight percentage of the
as the square of the inlet velocity.
b. Cyclone energy requirements. Energy require-
particles in a certain size range will be
collected at a specific inlet gas flow rate and
ments in the form of fan horsepower are directly pro-
cyclone pressure drop. A fractional efficiency
portional to the volume of gas handled and the cyclone
curve is best determined by actual cyclone
resistance to gas flow. Fan energy requirements are
testing and may be obtained from the cyclone
estimated at one quarter horsepower per 1000 cubic
manufacturer. A typical manufacturer's frac-
feet per minute (cfm) of actual gas volume per one
tion efficiency curve is shown on figure 6-9.
inch, water gauge, pressure drop. Since cyclone
(3) Cyclone collection efficiency is determined by
pressure drop is a function of gas inlet and outlet areas,
multiplying the percentage weight of particles
cyclone energy requirements (for the same gas volume
in each size range (size distribution curve) by
and design collection efficiency) can be minimized by
the collection efficiency corresponding to that
reducing the size of the cyclone while maintaining the
size range (fractional efficiency curve), and
same dimension ratios. This means adding more units
adding all weight collected as a percentage of
in parallel to handle the required gas volume. The
the total weight of dust entering the cyclone.
effect on theoretical cyclone efficiency of using more
units in parallel for a given gas volume and system
6-4.
Cyclone pressure drop and energy
pressure drop is shown in figure 6-10. The increased
requirements
collection efficiency gained by compounding cyclones
in parallel can be lost if gas recirculation among
a. Pressure drop. Through any given cyclone there
individual units is allowed to occur.
will be a loss in static pressure of the gas between the
6-5
Previous Page
