The heat transfer coefficient between the kiln and the charge, is important for the correct prediction of energy flow and temperatures in the kiln, and is not very well known. The inner kiln surface temperature is part of the outcome of the solution of the kiln wall energy equation.

Short time operation has increasing temperature with time, but in long term operation the temperature varies with length along the kiln, not so much with time, but still somewhat variant wnen the load changes rate or composition.

Dear Prem Baboo,

I appreciate your idea and sending the attachments. As you mentioned, internal wall has also an important role in heat transfer modeling in rotary kilns . In cement rotary kilns due to their long length, temperatures(internal wall,charge, freeboard gas and shell) change generally with length and it is constant with time, which is a steady state heat transfer. Short melting rotary kilns have a 4-5 meter length and the temperature of charge changes much with time, which is an unsteady state heat transfer. I'd like to know about short melting rotary furnaces and the variation of flame temperature( freeboard gas temperature zone) with time and along the furnace.

Dr Jerry Decker

Thanks for your constructive comments. In the lead melting rotary furnace, time operation is about  3 hours and length of furnace is 4.5 m. I am really curious to know can I assume flame temperature is constant with time and it just varies along the kiln? because the charge temperature(lead scrap) changes with time.

Here is a link related to kiln firing that may be helpful:

http://www.cementkilns.co.uk/ck_firing.html

If you are firing solid fuel (coal or Petcoke) it is very likely that you will experience variability in both fuel quality and air fuel ratio that will result in variations in flame temperature.  If you are using natural gas as a fuel this is less likely but the burner will deteriorate over time and might require adjustment to keep fired duty and the fuel/air ratio constant. 

Dear Rick Manner

Thanks for your  helpful answer.

I am interested cooperation in your project ,