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Technical Cement Forum / excess air in raw mill

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NCC 31/08/2007 16:40:07

excess air in raw mill

hello,

we use a ball mill for raw material grinding with central discharge, the problem arises with the difference in volume flow of air at NTP between the inlet and the outlet, for eg at the inlet we have a volume flow of 33000Nm3/hr, the out let volume flow comes around to almost double this value around 70000Nm3/h. what is the reason for this sudden difference

here are some more details

inlet air first chamber= 330C, flow = 74000m3/hr=39000Nm3/hr

outlet = 88C, flow = 100000m3/h= 81000Nm/h

very less amount of air is entering through the second chamber,

opinion would be greatly appreciated

sameh fareed 01/09/2007 09:55:33

You have very huge amount of false air ,

the main source of it :

1-Center discharge seal.

2-Double flap of meal feed.

3-circulation system.

you have to check O2 at:

1-gas duct to mill inlet.

2-gas duct after mill (duct going to static separator)

3- After static separator.

4-After cyclones.

By this way you can indentify where the air leakage.

R.M.SAHU 02/11/2007 09:59:26

The main reason seems to false air ingress between mill inlet and outlet.You may find out source of false air ingress point.Most probabily from mill outlet discharge seal.

emadissa 18/01/2012 13:08:30

in addition to the above mentioned; you have to conduct mass balance considering the volume of water vapor coming out in mill outlet stream. water vapor comes from moisture content in raw material.

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