technical NOTES

potential capacity so the designed pressure of fan shall be 500 + 80 = 580 mmwg
(without WHRS), to have some margin on fan to manage the operating requirements
Then 580 + 70 = 650 mmwg (With WHRS).
Case Study -In one of the recent plant the design & expected operating
parameters are indicated in below table for Preheater fan.

Preheater Fan

Data

UOM

Design

Data

Guaranteed output

@ 8000 TPD

Potential Capacity

output @ 9500 TPD

WHRS

OFF

WHRS

ON

WHRS

OFF WHRS ON

Flow m3/hr 1270000 975600 800000 1126800 926000

Pressure mmwg -653 -357 -427 -501 -571

Temperature Deg C 299 244 150 244 150

Margin in

Flow over

design

%30591337

Margin in

Pressure

over design

%83533014

15.2 Cooler Vent Fan
Similarly, for Cooler vent fan also in the past it was designed at 150 mmwg pressure
and the fan was normally operated at 50-60 mmwg pressure only, the balance pres-
sure drop was kept to handle upset kiln condition which was a rare occasion. This
used to increase the vent fan power due to lower efficiency because of high differ-
ence in design and operating pressure.
But in new trend of industry the fan to be designed at 75-100 mmwg only which will
reduce the power consumption by 0.1 - 0.2 kwh/t of clinker.
Now a day the increasing trend to install WHRS so the fan has to design on WHRS
On and Off mode consideration and to design pressure to be limited to around 125
mmwg only so that better efficiency can be achieved in all mode of operations. And
it is better to stop the kiln or reduce the kiln feed in upset condition for some time
rather than design the vent fan at vey higher pressure which is inefficient mode and
higher power consumption all the time.

Case Study: - In one of the recent plant the design & expected operating
parameters are indicated in below table for Cooler vent fan