I want to know about calculation methods of gas and material flow in preheater, pc, kiln, cooler. Further, can you advise why we are getting brown clinker problem in our 2000tpd off-line calciner kiln from which we are recently producing 2500tpd while having 90-91 LSF, 2.26 SM, 1.4 AM and kiln feed residue up to 22 per cent. How we can improve our clinker quality?

The calculation of gas and material flow in the preheater relies on the principles of stoichoimetry (to assess the combustion gas products from the fuel) and the conservation of mass. In principle what goes into the kiln must come out somewhere and will allow you to prepare a mass balance for the kiln. With regard to the brown clinker you are producing this is most probably caused by having reducing burning conditions in the burning zone of the kiln. This is very bad for clinker quality and fuel efficiency of the kiln. Almost certainly the problem is with the kiln burner and might be solved by adjustment. You must be sure that you maintain at least one per cent oxygen at the kiln inlet.

It is known in all cement standards that the Initial Setting Time is 45 minutes minimum and the Final Setting Time is 10 hours maximum. Is there any definite time to be considered between end of initial setting and start of final setting to ensure cement quality and workability.

There is no definite interval between the initial and the final set of cement that denotes good or bad quality or workability. You must bear in mind that the test for setting time is conducted at a constant temperature in the laboratory. This is not the case when the cement is used in practice. In cold countries the setting time extends in practical applications and therefore a short setting time is best in these conditions. In hot countries (such as the Sudan) the setting time is shortened in practice and therefore a longer set in the laboratory conditions would be desirable.