Re: Raw Meal fineness x kiln output

Hello Firat,

Based on what you have told me so far, I suspect that your problem is to do with an excessive clinker dust cycle in the kiln and an exaggerated sulphur cycle. The two are most likely linked to the high suplhur content of petcoke.

The fact that your ASR in clinker is only 1.1, yet you are getting regular sulphur-related buildups and rings in the kiln inlet suggests that you have frequent combustion problems causing increased sulphur volatility.

The usual suspects when it comes to combustion problems include;-

• Insufficient kiln inlet O2
• Too coarse or variable fineness of the fuel delivered to the burner
• Insufficient burner momentum.

Here is a petcoke case study that may be of some use to you;-

http://ieeexplore.ieee.org/iel5/7432/20214/00934113.pdf

Another case study I have (in hardcopy only) from a Moroccan cement plant experiencing similar problems concluded that bad combustion conditions due to low burner momentum combined with high raw meal LSF (~109) and low O2 in kiln inlet caused increased sulphur volatisation which lead to high clinker dust loads, subsequent ring formation & excessive/unstable coating.

They focused on the following corrective actions;-

• Reduction of kiln feed LSF to improve burnability
• Adjustment of SR (2.4 to 2.2) and AR (2.2 to 1.7) to increase liquid phase quantity and optimise coating properties.
• Minimise sulphur cycle by increase O2 in kiln inlet from 2% to 3.5%
• Reduce clinker dust generation by standardising kiln operation.(less aggressive changes by operators) eg. minimise large fluctuations in the kiln feed rate.
• Investigate cooler operation towards reducing dust generation.
• Align the hot meal duct, through which the hot meal enters the kiln inlet, to minimise dust entrainment.
• Adjust burner radial air amount to obtain the optimum momentum.
• Minimise %Cl in the raw materials.

Another possibly useful indicator with regard to coating formation is the 'Sum Value' (according to Konopicky) which has the formula;-

     SV = 100 - C3S - (0.78 * C2S) + (2 * Fe2O3)

where; SV ~33  :Good coating and clinker granule development

            SV >40 :Excessive coating and clinker ball development

            SV <30 :Difficult burning and coating characteristics.

(other variatons of this formula are sometimes referred to as the 'Coating Index' or A.W.)

Hope this helps... 

Regards,

Ted.

Reply

Know the answer to this question? Join the community and register for a free guest account to post a reply.

Re: Raw Meal fineness x kiln output

Hello Ted,

I've read the article before. After reading that article, I've offered to reduce the petcoke injection velocity by a frequency convertor.

Combustion have problems but it is not really solved. We've fixed a mechanical problem with burner two weeks ago and 70% of CO has gone. But still it is not ok. Testo cannot read SO2. 1% Oxygen, Still too much CO. Momentum seems to be ok. The alignment of the burner is not so bad. Fineness of petcoke is 3,5% on 90 um. One problem is Shenck's fault on feeding dust. There is too much of fluctuations however, you can not see it from feeding. It can be seen from CO and kiln.

SV= 33-36. I've checked this by Coating Tendency or Index.

Thank you for guidance

Best regards,

Firat

Reply