Cyclone Draft

Can anybody tell me whether the draft for each of the cyclone  should be positive or negative. I have seen many plants where all the draft is indicated positive and at some places they are negative. What is its significance?

Also what is the reason for indicating mmwg for the cyclone draft in india rather than mbar. what is the relation between the two.

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Re: Cyclone Draft

There is negative pressure in every cyclone of a suspension preheater. That negative pressure is created by the induced draft fan and causes the exhaust gases to be drawn out of the kiln and up, through the preheater. mmWG and mbar are both units of pressure. 1 millimeter of water [4 °C] = 0.098 066 5 millibar.

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Re: Cyclone Draft

Well i love the way Newbie asks the questions!

When there is Suction ( Let say you are taking cold drink through straw in your mouth you suck it) ther pressure in your mouth is -ve which is generally termed as ID ( Induced Draught) Like in preheater cyclones Preheater  "ID" fan "Sucks" Gases Obviously the pressure is -ve there. Now coming to your question why some plants show +ve Draught? It's Not that there is a +ve pressure inside that prehater, it's simply because "EVERYBODY KNOWS IT'S -Ve" why put -ve sign which consumes screen space?

coming to your Second question reminds me the day when My professor Said to me "ITS OLD SCHOOL TO USE METRIC SYSTEM OF UNITS IN INDIA" as india has legally adopted SI System of units Ref : IS 10005  when i used kg/cm2 for pressure units ins ted of Pa (Pascal) . Like Most of the indian culture is influenced by British "THANKYOU" ya "DHANYAVAD" well as always thankyou.When early cement plants were setup in india most of them were supplied by German companies (KHD/Polysius) Like most of European countries where metric system largely prevails that culture of Metric system was inculcated in Indian cement industries. and second reason is mmWG can be easily imagined when compared to other units say 10330 mmWG it's the pressure your body feels when you dive in 10.33 m of water.

 Now the "quick" relation between these units is 1mbar = 10 mmWG = 100 Pa for precise conversion see Perry's Handbook of Chemical engineers or any other standard book (the difference will be g = 9.80665)

I always encourage my clients to use SI system of units which are flawlessly defined

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Re: Cyclone Draft

Thank you very much as your answers are really helping me out.

Now , if we increase the feed rate , what should happen to the -ve pressure in each of the cyclone at its inlet & exit ,cyclone draft , draft at the kiln inlet & Preheater ID Fan power & why?

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