2. Power Generation by GPP (WHRS)- 4, 5 & 6 Stage Preheater
A study is carried out on 4, 5 and 6 stage preheater and its effect on power generation
by GPP and Sp. Fuel consumption of pyro process system. Installing 6 stage and
operating from 6 to 5 stage gives impact of around 20 kcal/kg clinker and additional
net power generation by WHRS is estimated by 1.27 MW, while 6 to 4 stage it
increases by around 45 kcal/kg clinker with additional power generation by 3.86
MW only from preheater and Cooler.
While calculating the monitory savings or losses on account of these, the cost in
curred on following equipment’s /items have been listed here
- Preheater fan power consumption due to change in gas flow requirement due
to change in Sp. Fuel consumption - Preheater Concrete cost
- Steel and fabrication cost of cyclone.
- Dip tube cost.
- Refractory cost
- Steel and fabrication cost of down comer duct
- Kiln feed bucket elevator cost
- GPP (WHRS) cost for higher sizing
Based on the sheet appended with detailed working on this it is evident that
the payback period is mainly depends upon the fuel cost and grid power cost of the
particular plant.
Normally, nowadays the fuel cost varies in the range of 1000-1500 Rs/ Mkcal and
Grid power cost varies from 5.5 – 7.1 Rs /kWh.
For example, with same amount of additional heat consumption and additional
power generation from different stages of preheater cyclone the change of payback
period is shown here for understanding
Comparison for 4/ 5/6 Stage Preheater (Estimation at 9500 TPD Capacity)
PH Stage Reduction
Remarks
Data Unit 4 stage 5 Stage 6 Stage
Base fuel cost Rs/ MKcal 1000 1000 1000
Green Fuel
Cost Rs/ MKcal^600600600
TSR % Rs/ MKcal 0% 0% 0%
SFC increase
due to AFR Kcal / %TSR 1.5% 1.5% 1.5%^
Net Fuel Cost Rs/ MKcal 1000 1000 1000