22 PROjECT PRIDE
Coal Grinding Technology
We have provided following inputs to suppliers for designing
the coal grinding system:
- Grindability: The petcoke and coal grindability
given to suppliers for mill designing and guarantee
were 38 HGI and 45 HGI respectively, the mill and
its circuit was designed for both fuels, i.e. petcoke
and coal; however, performance guarantee shall be
on petcoke - Capacity requirement: Capacity requirement
given to suppliers of 40 TPH petcoke @ 1% residue
on 90 microns and 75 TPH on coal @ 15% residue
on 90 microns considering kiln potential capacity
9,500 TPD considering 22 running hours - Feed moisture: The maximum feed moisture given
for system design is 7% on petcoke and 15% on coal - Available gas temperature: We have followed
WHRS concept since the beginning and thus we
intended our suppliers to design the mill in such a
way that it could run at less than 150 ̊C (PH boiler
outlet temperature). Initially suppliers were not
confident about zero water and 150 ̊C gas availability
at mill inlet but after discussion on some references
like Shree Cement (Pfeiffer mill) and Dalmia Kadapa
(Pfeiffer mill) – which were running mostly with no
water spray requirement over table – the suppliers
got convinced and submitted their offer accordingly.
However, FLSmidth Atox Mill still needed some