By using the concept of coal-pulverizing output per unit cylinder volume of the ball mills

a simplified calculation method for output of ball mills with single-inlet and single-outlet has been introduced into output calculation of ball mills with double-inlets and double-outlets

the coal-pulverizing output for per unit cylinder volume in pulverizing standard coal

as well as the calculation formula for coal-pulverizing output per unit cylinder volume in pulverizing other coal sorts being put forward

including for BBD type

D-type

and SVEDALA-type ball mills with double-inlets and double-outlets.Through calculation of output for SVEDALA-type ball mill of boiler no.3 in Shang'an Power Plant

and for D-10D-type ball mill of boiler no.1 in Erzhou Power Plant during practical operation according to said formula

and comparison with the actually measured outputs

it shows that the results tally very well.