Volume
DRY IV Part 1
Introduction.
This part describes the basic
features of rotary dryers and their advantages and disadvantages
relative to other types of dryer, and the overall layout of
the volume.
Volume
DRY IV Part 2
State
of the Technology. This
part covers current equipment options. In rotary dryers, solids
are dried as they are transported along the interior of a rotating
cylinder or drum. They are classified as convective or conductive
dryers according to their primary mode of heat transfer. The
text concentrates mainly, although not exclusively, on direct-heated
convective dryers equipped with lifting flights to shower the
solids through the hot gas, which are known as cascading rotary
dryers. The current industrial practice relating to the design
and operation of rotary dryers is described in depth. Topics
covered include applications, cost, instrumentation, control,
modelling, safety and environmental considerations.
Volume
DRY IV Part 3
State
of the science.
This
discusses in depth the underlying scientific principles in
three main areas:
- Particle transport along rotary
dryers: particle flow, transport model, and drum holdup
calculations.
- Air flow and heat transfer:
spreading of particle cascades, air flow distribution, and
gas-to-particle heat transfer.
- Drying kinetics: the characteristic
drying curve, batch drying theory, through flow drying tests,
and examples.
Volume
DRY IV Part 4 Design guide.
This
covers scoping design, fitting mode, design mode, performance
mode, specification of operating variables, characterisation
of the solids, heat and mass balance calculations, drum and
flight specification, simulation procedure. The layout is
compatible with the PC program ROTARY. The material is largely
based on the earlier Design Report DR10, but the layout has
been completely revised to give a more systematic design procedure.
A cascading rotary
dryer is defined as a device in which solids are dried while
being transported along the interior of a rotating cylinder
equipped with lifting flights to shower the solids through
the hot gas. The design procedure is based solely on a new
particle transport model developed by SPS which enables the
user to calculate the dimensions and flight designs of the
drum to achieve the required solids residence time. The specification
of this parameter is covered by a comprehensive guide to operating
data on 87 industrial plants. The report describes the "Design
Methods" of which there are four. A "scoping"
design procedure is presented which is a simple hand calculation
requiring no experimental work to calculate the approximate
diameter and length of the drum for a given application. The
remaining three calculation procedures are far more detailed
and have been implemented in the ROTDRY and ROTBAS spreadsheet
programs and the ROTARY simulation program. A "fitting"
mode calculation is performed on data collected from either
a pilot plant or from full scale equipment to extract the
"dense phase velocity number" which is required
by the "design" and "performance" mode
calculations. In the "design" mode the diameter
and length of the drum are calculated more precisely and,
in addition, values of the slope, rotational speed and flight
dimensions are determined. In the "performance"
mode, the solids feed rate for a particular dryer operating
under specified conditions is estimated. The remainder of
Part 4 discusses specification of operating variables, characterisation
of the solids, heat and mass balance calculations, drum and
flight specification and the particle transport model.
