Sir, In our plant we are getting more coating problems at Kiln inlet and Riser duct. Please tell me what is reason for the coating problem and give me some suggetion to minimize this problem.

Fuel using :Crude Oil

Regards

Regards

The main reason of coating formation in any kiln is unbalanced sulphur to alkali, molar ratio.If you balance the molar ratio your process buildup problem can be managed or minimized.

Bazarah,

 In my experience, buildups in this area usually originate from poor combustion resulting in high CO and SO3 in the kiln inlet.

Hi

Coating at kiln inlet ia mainly due to the volatiles like Chlorides, alkalies ( Na2O and K2O) and SO3. To minimise the coating formation, the alkali sulfate ratio should be around 1.1 so that these volatiles will come out as alkali sulfate along with the clinker so that the recirculation inside the kiln circuit will be less.

Chlorides should be controlled from the inputs like limestone, clay etc. If sea water is used in rawmill , or GCT or anywhere , then it will also increase the chloride content

When we use high sulfur coal or petcoke, the SO3 will increase.

If Sulfur is deficient in the circuit and alkalies are more, then we can add gypsum along with the rawmaterial to reduce the alkali sulfate ratio.

Even  after doing all the above, there will be some residual coating will be formed in the kiln inlet. It can be cleaned with out stopping the plant, by 

!. Kiln inlet area may be lined with silicon carbide based bricks or castable, which will form a glassy phase at high temp and thus avoids the coating formation

2. You can also use high pressure water pumps( 250 to 300 bar) for the removal of the coating

3. Any CO at kiln inlet will aggrevate the coating formtion.So reduced atmosphere should always be avoided at kiln inlet

4. Air blasters can be installed at the kiln inlet and can be operated using automatic timers

5. we can also use CARDOX system, which will blast the coating usiong CO2 blasting.

Regards

Vinayak

Sir hello,

if you are looking to minimize build up at kiln inlet and riser duct using a preventing automatic method, i would recommend using air blasters which will be blast plant compressed air  at fixed timing (hence every 15 minutes)

 High pressure water jetting can be stressfull for refractory coating

Cardox are quite effective, but need proper storage and licence, and triggers have to be done every time manually.

Cheers

thomas

www.staminair.com 

Hi,

  Paramount is to balance the alkali sulphate ratio but also try to avoid reducing atmosphere in the kiln . This is especially beneficial if the backend coating resulted from excess sulphur in the system. Oxidizing atmosphere wil encourage formation of SO3 which can react with the ever present CaO to form stable CaSO4 that will be expelled with the clinker.

                                                                                        Best regards,

                                                                                                   A Bashar.

Dear All ,

kindly i want to clarify info. about Alk-sulphate ( Na2SO4 & K2SO4 )

 these compounds share in build up in kiln inlet or come out with clinker ?

Sir,

 We noticed very high sulphur content (About 3-4) % and kiln was disturbing .The increase in sulphur %  was within a period of 24 hours.What was the reason for such sudden increase in sulphur??To balance sulphur alkali ratio is it advisable to stop alkali by pass system to increase the alkali and thus balance the ratio .Pl advise.

It can be very misleading to give advice without knowing all the operating data and details over a longer period.

However the high sulphur content over 24 hour period (short term) suggests it is not caused by raw meal/fuel chemistry but by insufficient combustion i.e. reducing atmosphare.

Such condition can occure when you get insufficient combustion air e.g. because of heavy build ups in the kiln inlet or kiln ring formation braking of and increase pressure drop at kiln inlet or ball formation.

Just a few of possible causes. To investigate the situation properly the frequency of such occurances should be monitored as well as all process/operation relevant data before-during- and after such occurences.

Generally first try to avoid such condition and if this fails install a bypass system.

Best regards,

WiZi