12. Various Kiln Burners
12.1 Function
Function of a burner in cement manufacturing is to supply the fuel along with
conveying air and burn the fired fuel with the primary air supplied through
separate blower or fan, thus creating a sharp and strong flame inside the kiln to
burn the calcined raw mix at 1450-1550 Deg. C and produce clinker. Since the
burner has to fire & burn the fuel inside the kiln so its efficiency and sensitivity is
very important as far as flame shape and stability are concern.
12.2 Role of a Good Burner
- To maintain the good flame with desired momentum to achieve uniform heat
distribution across the burning zone resulting in good quality clinker and better
refractory life. - Primary air percentage should be minimum so that fuel consumption, power
consumption and NOx generation can be reduced. - It should have the ability to create a vacuum near to the flame so that
maximum secondary air coming from cooler can be absorbed into the flame
for proper and complete combustion of fired fuel so that no CO remains at kiln
inlet.
Short and Stable flame results in less structural growth of C3S & C2S. Alite Crystal
size will therefore be smaller. Due to smaller Alite crystal size, the clinker becomes
easy to grind. Also, due to Short and Stable flame, the formation of C3S is more in
comparison to other burners which results in higher early strength of the Product
in turn more fly ash can be added when manufacturing blended cements.
On account of reduced specific heat consumption, the combustion waste gas
quantity through Preheater exit will come down. As a result of this, the Preheater
fan & Main BH Fan Power Consumption will get reduced at base clinker production
or the clinker production can be increased by utilizing the margin available in the
PH fan.
Another important role of a burner is Low NOx Emissions
NOx formation is strongly dependent on: - Temperature peaks of flame with available concentrations of O2 and N2.
- Residence time of peak temperatures.
The flame of the burner has both an internal recirculation zone and a long external
one which results in NOx reduction. The unique jet air streams facilitate
substantially uniform heat distribution. Thus there will be no temperature peaks.
Thermal NOx formation is lower with uniform secondary air absorption in latest
burners in comparison to conventional burners where the localized temperature
peaks occur due to non-uniform secondary air absorption.
The another important features should be the adaptability of using different type
of fuel.