technical NOTES

Secondary Measures

• SNCR
  Reagents:


• Aqueous ammonia solution (20-25% by wt.)


• Urea solution (30-40% by wt.)
  Reactions


• 4NO + 4NH3+ O2à4N2+ 6H2O


• 6NO + 4NH3à5N2+ 6H2O


• 2NO2+ 4NH3+ O2à3N2+ 6H2O
  SCR
  NOx Abatement Measures


• Optimization of Primary Air,


• Transport Air and Excess Air

S.NO. Method Thermal NOx %

Reduction

Fuel NOx %

Reduction

1 Change of Raw mix burnability 0-10

2 Stable operation ( Expert system) 0-10

3 Low NOx burner 0-15

4 Change of Fuel type 0-15 0-50

5 High temperature combustion in

Calciner

0-25

6 Staged combustion in Calciner 0-25

7 Recombustion 0-55 0-20

8 NH3 injection (SNCR) Reduction Up to

75 %

8.4 Conclusion
Selection of Low NOx calciner to be done properly its design with respect to to
feeding point, TA duct entry and coal firing is very important to create sound
reduction zone to kiln the kiln NOx. Use of AFR`s and low cost fuel are the need
of hour also environmental norms will be more stringent so its designing is very
important. Also calciner sizing to be done as big as possible to have higher retention
time Ice 15-18 seconds so hard burnt fuel can burn properly without any CO thus
lesser oxygen level is required hence reducing NOx level of plant.