The Rotary Kiln at TeKumi was commissioned in February 2002. The process involves burning limestone at 1000
- 11 000C to produce a burnt lime (CaO) product. This paper describes the
design and installation of a trifoil system to improve the energy efficiency of
the kiln. An energy balance showed that 32 per cent of the energy was being
lost through the flue gases, compared to 5.8 per cent in shell losses and 2.5
per cent lost as heat in the product. The trifoil proved to be the best way to
tap the energy from the flue gases. Drying tests showed that a trifoil improved the
drying time of limestone by 37.5 per cent, compared to only 25 per cent for a
lifter system.
The trifoil system increases the surface area for heat transfer in a Rotary Kiln
by 180 per cent. The overal energy efficiency of the Rotary Kiln was improved by
15 per cent, resulting in a 15per centincrease in production and an 80C reduction in flue
gas temperature. This has reduced dust build up in the ducting while reducing
maintenance costs through a reduced fan speed. The trifoil hub was designed with
tooths at the centre to prevent shifting. Each trifoil leg has an anchor block
on the down side to prevent downward movement of the trefoil
legs.