Methods for Design and
Optimisation of Rotary Granulator, Dryer, Cooler and Kiln
This is a comprehensive report covering the
complete process calculations of rotary granulator, dryer, cooler, kiln and
other associated equipments especially employed in a fertilizer granulation
plant. The methods for simulation and design presented are equally useful
for any other material other than fertilizers as well. A typical
granulation plant would employ a granulator, dryer, cooler, screens and recycle
system, and dedusting cyclones for dryer and cooler air streams.
The report consists of the following chapters:
- Some basic concepts covering dry and wet
bases, LMTD, psychrometric parameters, drying mechanisms, conversions
factors and some useful basic data.
- Solids residence time including its effect on
solids hold-up and material filling.
- Drive power for rotation including the
influence of cake thickness, scale-up etc. for both co-current and
counter-current operations, and the heat input due to power.
- Granulator heat transfer covering water and
steam injections, control logics, the influence of recycle on granulator
- Dryer heat transfer explaining the moisture
evaporation process, overall mass and heat balances, surface and internal
moisture evaporation rates for co- and counter-current flows, material CRH
and its influence on evaporation and moisture re-absorption. Methods are
presented for calculating outlet solids moisture content, outlet gas and
solids temperatures, outlet air humidities and dew point, and fuel
consumption. The complete profiles of solids moisture content, gas and
solids temperature within the dryer are predicted which give a great insight
into dryer operation, material degradation, optimisation etc.
- Cooler heat transfer giving an elegant and yet
simple model for predicting the profiles of solids moisture content, gas and
solids temperatures inside a counter-current cooler.
- Kiln heat transfer with special focus on
cement kiln circuit giving a model covering kiln, pre-heater and
pre-calciner, grate cooler and fans.
- Design aspects to establish optimum dryer
diameter, length, rpm, slope, air speed etc. to achieve desired drying
- Carryover and collection of fines giving
equations for dust entrainment rates, collection of entrained solids and
design of overhead cyclones for the same.
- Some industrial
case studies illustrating the actual benefits derived by some plants
using the various methods outlined in this report. In this chapter,
detailed predictions using our softwares GRAND and
RDSIMUL illustrate the utility of the comprehensive mathematical model
incorporating the various inter-connected equations presented in the
The various mathematical calculational procedures
are made easy to understand with the help of 39 worked-out examples and a few
case studies. These should be extremely useful to operating plants for
achieving process optimisation, to designers for designing optimum equipments,
and to engineers and plant operators as an effective learning/training aid.