24 PROjECT PRIDE
is used for grinding and hence increases the
grinding efficiency
• Maximum grinding pressure to be designed:
Having higher margins on grinding pressure
enables the mill to have excess margins for future
potentials
• Lesser pressure drop across nozzle ring with
minimum false air ingress: As pressure drop is
directly proportional to fan power consumption
we have asked all suppliers to have the least
pressure drop across mill with least false air
ingress
• Maximum nozzle ring area: The nozzle ring area
plays an important role in mill internal design as
it drives the lifting of material inside the mill with
a certain velocity and pressure. If the nozzle ring
area is increased, it provides a better potential for
the mill
• One size bigger classifier than standard size
for the offered mill: We have observed in recent
past that for any upgradation in VRM, suppliers
offer a bigger size classifier saying that it shall
enhance the productivity by 10% or so. Thereby
we analysed this parameter and have asked all
suppliers to offer their mill with at least one size
bigger classifier than their standard. Pfeiffer has
initially offered 16.57 m^2 and later on increased it
to 23.29 m^2