Coating formation in Kiln Inlet
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
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Re: Coating formation in Kiln Inlet
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.