I think the effect on oxygen demand will remain marginal at best.

What is not marginal on the other hand is the effect of alkalis on volatile cycles. An increase of the cycles would transport heat from the burning zone to the base of PH and this can have an effect on your heat consumption and PH outlet temperature, especially if you have a preheater kiln without calciner (is this the case?)

Furthermore, increased cycles can also lead to build-ups in the PH increasing the pressure drop, hence the need for higher fan speed.

You should try to establish a simple cycle balance of the volatile species (Na, K, Cl, S) before/after change of raw materials. Analysis in clinker and hot meal should be enough for first assessment.

Best regards,

 

Dear Sir,

         Our 4000t/d Plant is a in line calciner kiln using about 90% coal and 10 %gas.We use gas as per the availabilty of it. Recently we noticed the sulphur content increasing from 1.5% to later on to 4.0 % on the hot raw meal where as it was less in the clinker .What was the reason for this high sulphur and under such conditions is it advisable to stop Alkali bypass system to increase the alkali content and balance the alkali sulphur molar ratio??Is it due to high sulphur we noticed coating development in the burning zone area or is it vice versa .Your valuable comment will be well appreciated.

Dear sir

Eying on your statement i had one doubt. As you enlightened accentuating on 

effect of alkalies on volatile cycle.  What does it mean.

As  cycle increses it transfer more heat  thereby increasing in consumption as well.pertinent to my quiries i would add that how this increase in cycle going to make  an substantial impact in increase in velocity of fan.

My perception is , there is on possibility which we have untouched is Delta P across the Preheater. Well this is all my perception been expressed on basis of my Knowledge, You may be absolutly right on your view , but what makes me to post hereis how it impacts. 

I am new to this field, can you make your effeort to exude me your views on basis of your experience and experise as well.

Awaiting to your reply

Rahul

High alkali loading in your kiln feed without balancing the alkali sulphate ratio in your system could lead to the excess alkali conndensing in the cooler part of the pre-heater. This partial blockage of the preheater will cause an obstruction on the air circuit pushing you to need a much higher ID fan speed. I think the solution to this lies in effective use of the the alkali bypass and use of slightly high sulphur fuel to balance the ASR.