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Technical Cement Forum / Zero NOx

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Cement man 03/06/2013 08:09:01

Zero NOx

Good morning Everybody;

Our kiln is five stages preheater with PC and bypass system, we are facing the problem of very low excess O2 at cyclone-5 (less than one) and very less NOx (sometime drop to 5 or 0 ppm) and sure CO generate from time to time.

Our kiln was running normal but before 4 years and after kiln shutdown this problem started, we have tried everything to solve it but till now we couldnt solve this problem. Do any one have an idea how this problem can be solved? & How is it possible NOx = 0 ??? Where is NOx in the system going????

thanks

Ted Krapkat 04/06/2013 04:11:31

Hello Cement Man,

It sounds like you are generating a lot of CO at the back end which is destroying most of your NOx.

2CO + 2NO ---> 2CO2 +N2

4CO + 2NO2 ---> 4CO2 + N2

Which is not a bad thing in itself, but the lack of O2 in the back end of the kiln means that you are likely to experience regular rings and buildups due to excessive sulphur recirculation.

Are you able to increase the ID fan to maintain at least 2% O2 in the kiln inlet?

Regards,

Ted.

Cement man 04/06/2013 09:32:46

Thank you Ted for your answer ... Yes you are right; we are generating a lot of CO and that is because of lack in O2. We have also very hard and heavy build up (attached photo) in burning zone area. Regarding to ID fan speed; unfortunately the speed is maximum.

Thanks again

Regards

Attached files

April 2013 (4).JPG

Ted Krapkat 19/06/2013 02:04:49

Hello Cement Man,

A last resort method of increasing your kiln inlet O2 is to inject oxygen. A possible drawback of oxygen enrichment is that NOx emissions will probably increase. It is also expensive.

See;- http://www.airproducts.com/~/media/Files/PDF/industries/glass-cement-lime-when-to-enrich-the-kiln.pdf

Regards,

Ted.

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