Vertical Raw Mill Heat Balance Excel Sheet

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Vertical Raw Mill Heat Balance Excel Sheet

 

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PROCESS FILES
VRM HEAT AND MASS BALANCE
FLOW MEASUREMENTSBEFORE MILL IDFBEFORE MILLAFTER MILL
Temperature, oC8320086
Static pressure, mm H2O-1026-95-866
Barometric pressure, mm H2O101861018610186
Dynamic pressure, Pd, mm H2O26.0052.0050.00
Gas density at std. cond., kg/Nm31.371.391.38
Gas density at actual cond., kg/Am30.9450.7950.960
Average ( Pd ) 1/25.107.217.07
Flow area, m26.807.406.80
Pitot coefficient0.7340.7340.734
Gas velocity, m/s23.2235.8123.45
Vol. flow rate, Am3/h568543953983574038
Vol. flow rate, Nm3/h392074545472399412

HEAT AND MASS BALANCE of VRM (mill to cyclone)
Date:
Raw feed condition:  Rate265mt/h
Temperature35°C
Moisture5.0%
Raw meal collected at cyclone:  Rate                         176.56mt/h
Temperature (after cyclone)83°C
Moisture of mill product0.8%
Weight of H2O vapor from raw matls.                         11,220kg/h
Dust going to bag house at cyclone efficiency of70%77218.90kg/h                   196.9g/nm3
Hot gas condition before mill
Temperature200°C
Pressure-95mmH2O
Oxygen content9.6%
Volume at actual condition953,983Am3/h
Volume at standard condition545,472Nm3/h
Gas condition after the mill
Temperature86°C
Pressure-866mmH2O
Oxygen content11.5%
Volume at actual condition574,038Am3/h
Volume at standard condition399,412Nm3/h
Volume of H2O vapor from  raw mat’l                           9,048Nm3/h
Gas condition at the mill fan inlet
Temperature83°C
Pressure-1026mmH2O
Oxygen content12.3%
Volume at actual condition568,543Am3/h
Volume at standard condition392,074Nm3/h
HEAT AND MASS BALANCE  of VRM
Reference temp.20deg C
TempCp
InputNm3/hMass, kg/hHeat, kcal/h°Ckcal/kg
Raw material ( dry)            251,750.00              1,691,760.00350.192
Raw material moisture              13,250.00                 463,750.00351.000
Dust suspended at gas from CT                5,646.33                 216,819.232000.192
Hot gas  from CT545,472.11            758,206.23           36,546,631.222000.241
False air at mill120,047.50            154,861.27              1,306,716.99350.241
False air after mill to fan inlet62,029.22              80,017.70                 675,188.09350.241
Grinding heat              2,067,526.03
727,548.83        1,263,731.53           42,968,391.56
Output
New raw meal + kiln dust collected at cyclone, dry            180,177.43              2,990,945.40830.200
New raw meal + kiln dust going to baghouse,dry              77,218.90              1,281,833.74830.200
Raw meal moisture                1,453.04                 120,602.64831.000
Exit gases:  gas from preheater        545,472.11            758,206.23           14,985,755.22830.238
false air from raw mill        182,076.72            234,878.97              4,707,502.52830.241
H2O vapor from raw mat’l             9,513.67              11,796.96              7,491,631.08830.288
Heat loss by radiation & convection              1,024,813.39
        737,062.50        1,263,731.53           32,603,083.99
-24.12%
Grinding heat computationRadiation & convection losses
mill motor2496.83kwWater evaporated           11,796.96kg/h
classifier motor86.96kwR/C factor                   11.95kcal/kg H2O
mill fan*0kwHeat loss at the mill        140,977.01kcal/h
total2583.79kwHeat loss at the cyclone883,836.38
assumed % efficiency0.93Total heat loss     1,024,813.39kcal/h
Heat Balance at Cyclone
TempCp
InputNm3/hMass, kg/hHeat, kcal/h°Ckcal/kg
Gases:hot gas from preheater545,472.11758,206.23           15,527,409.02860.238
water vapor from raw matl9,513.6711,796.96              7,507,533.29860.288
false from at mill120,047.50154,861.27              3,215,952.37860.241
false air at cyclone62,029.2280,017.70              1,659,033.59860.241
R.mealraw meal, dry251,750.00              4,330,100.00860.200
dust suspended at gas from CT5,646.33                   97,116.95860.200
raw meal  moisture1,453.04                 124,961.77861.000
1,263,731.53           32,462,106.98
Output
Gases:hot gas from preheater758,206.23           14,985,755.22830.238
water vapor from raw matl11,796.96              7,491,631.08830.288
false air fr. mill to dust col.234,878.97              4,707,502.52830.241
R.mealnew raw meal + dust collected at  cyclone, dry180,177.43              2,990,945.40830.200
new raw meal + kiln dust going to baghouse,dry77,218.90              1,281,833.74830.200
raw meal moisture after cyclone1,453.04                 120,602.64831.000
1,263,731.53           31,578,270.60
Radiation & convection loss (by bal.)                 883,836.38
Stoichiometric calculation fot verifying measured data:
Volume of hot gas before the mill                       545,472Nm3/h
Volume of H2O vaporized from raw materials                           9,048Nm3/h
Volume of false air entering the mill (by O2 bal)                       120,047Nm3/h16.3%
Volume of gas leaving the mill                       674,568Nm3/h
Volume of false air after mill to mill fan inlet (by O2 bal.)                         62,029Nm3/h8.4%
Volume of gas at the mill fan inlet (calculated)                       736,597Nm3/h
Volume of gas at mill fan inlet (measured)                       392,074Nm3/h
Difference of computed and measured volume-87.9%ok
Note: Minimal difference validates computed and measured  values
Estimate of kiln dust:
O2 at Ph exit6.00%
O2 at rm3 inletkg/h9.60%
Water vapor at cond. Tower9963.68035.16nm3/h
False air24.96%134127.37nm3/h
Preheater gas volume403309.58nm3/h
Kiln dust at assumed30.00%collection at CT5646.33kg/hsuspended in gas
20g/nm31882.11kg/hcollected
Specific volumes used
Air1.24kg/nm3
Combustion gas1.29kg/nm3
Water vapor1.39kg/nm3

 

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