To All the members of Production department.pl find below
some very important tips during kiln operation.
It is requested to use these tips during operation:
•
Every 1 % reduction in free lime increases 10 – 25
kcal/kg clinker heat consumption.
•
Every 10% increase in preheater exit temp., increases
7-10 kcal/kg clinker heat consumption.
•
Every 10% increase in clinker temperature, increases 2
kcal/kg of clinker heat consumption.
•
Every 1% increase in kiln PH exit O2% increases 7
kcal/kg of clinker heat consumption.
•
Every 1% increase in residue (kiln feed) in 90 micron,
increases 5-10 kcal/kg clinker heat consumption.
•
Every 0.1 increase in silica modulus, increases
10kcal/kg clinker heat consumption.
•
Every 1% increase in kiln feed LSF increases 15 kcal/kg
clinker heat consumption.
•
Every 100 blain increase in cement increases 1.5
kwh/MT of power consumption.
•
Every 1% reduction in primary air reduces 0.7 kcal/kg
clinker heat consumption.
•
Every 10 degree centigrade increase in flame
temperature increases 1% kiln production.
•
Every 100 blain increase in cement increases 1.5 Mpa of
•
Every 1% increase in fine coal moisture reduces 10 to
14 degree centigrade flame temperature.
•
Every 1% reduction in clinker-free lime, increases 4.0 %
C3S in clinker.
•
Every 1% increase in C3S reduces 0.3 to 0.5 kwh/MT
clinker grinding energy consumption.
Hi everyone!
Anyone can tell me how to operate the rawmill without the hot gas generator. Our plan have a rawmill without hot gas generator. The heat sourse is from the kiln, but at initial we just use the heat when heat the kiln. So the heat sourse from heating the kiln is enough for operate the rawmill? and if increase the heat sourse from increasing the fuel firing in Calciner is affect to refractory of the suspension preheater
• It has been observed that normally hot gas generator is used for initial start up of the new kiln when raw mill must be started before the kiln. In such cases, precalciner can be used as hot gas generator even before the kiln light up without any problem. But please remember that this arrangement is only for those plants who intend to maintain at least 50% stock of raw meal in silo during operation. If raw meal silo level is often taken to below 50% level at the time of kiln shut down and raw mill capacity just meets the required kiln feed rate then it is better to have a hot gas generator to ensure regular supply of raw meal at start up of kiln
• my coal ball mill is 2.5 *4m with 10 tph having coal with 7 % input moisture & 1 % output moisture.
• it is connected with a auxiliary furnace.
• i want to calculate the amount of coal fired into the furnace to get grind the coal.
• Mill outlet temp . 80 deg
• velocity through mill 1.5 m/s
• gr. media in mill is 27 t Dear Mr. Rajesh,
sending you two excel sheet ( pasted ) . Please send me your mill's details as shown below ( in Bold ) to get full report. Vikpro
Mill Dia Mill Length Mill Capacity Gypsum % Clinker input Gypsum input Power input, Mill Clinker Temp. ( Tk ) Gypsum Temp. ( Tg) Cement Temp. ( Tc) Temp. of Air ( TL )
Mill vent Air per kg of Cement. Mill Ventilation temp Avg. Mill surface Temp
Mill Surface Area Specific Heat of Cement Radiation of Mill shell / m2 Specific Heat of Air.
1) Loss of efficiency by generating heat in the Mill 2) Loss by Radiation through mill shell.
3) Losses by heating the mill vent Air.
4) Losses not measurable such as sound generation & Vibration.
5) Total KWh
Heat Balance ( Mill ) Mill Dia 2.2 Mill Length 12 Mill Capacity 18 Gypsum % 4 Clinker input 17.28 Gypsum input 0.72
Power input, Mill 2436 Power input, Motor 600 Clinker Temp. ( Tk ) 15 Gypsum Temp. ( Tg) 15 Cement Temp. ( Tc) 95 Temp. of Air ( TL ) 15 Temp. of Water ( Tw ) 15 Mill Ventilation temp Avg. 45 Normal H2O vapour in Dry Air 0.2 Mill surface Temp 40 Mill Surface Area 90.5
Total Heat Input Heat entering Mill with Clinker 49248 Heat entering Mill with Gypsum 2797.2 Heat entering Mill with Air. 4.665 Heat entering Mill with Motor. 2094960 Total Heat entering Mill 2147005
Total Heat Output Heat leaving With H2O Vapour
Heat leaving with Air. 304367.9 Heat leaving with Cement 324900 Heat leaving through mill Surface 9854.108 Total Heat leaving Mill only 379196.9 Total amount of Air in Mill 10301.84 Air per ton of Cement 572.32 Total amount of Water in Mill 2431.23 Amount of Water. lit/ ton cement 135.07 water Vapour / Kg Air 0.24 With determined air Volume, and
without water injection, the Cement Temp. would be ……
Vikpro
Grinding and Generation of Heat. Mill Dia Mill Length Mill Capacity Gypsum % Clinker input Gypsum input Power input, Mill Clinker Temp. ( Tk ) Gypsum Temp. ( Tg) Cement Temp. ( Tc) Temp. of Air ( TL )
Mill vent Air per kg of Cement. Mill Ventilation temp Avg. Mill surface Temp
Mill Surface Area Specific Heat of Cement Radiation of Mill shell / m2 Specific Heat of Air.
1) Loss of efficiency by generating heat in the Mill 2) Loss by Radiation through mill shell.
3) Losses by heating the mill vent Air.
4) Losses not measurable such as sound generation & Vibration.
5) Total KWh
Heat Balance ( Mill ) Mill Dia 2.2m Mill Length 12m Mill Capacity 18t/h Gypsum % 4% Clinker input 17.28t/h Gypsum input 0.72t/h Power input, Mill 2436Kw Power input, Motor 600Kw Clinker Temp. ( Tk ) 15C Gypsum Temp. ( Tg) 15C Cement Temp. ( Tc) 95C Temp. of Air ( TL ) 15C Temp. of Water ( Tw ) 15C Mill Ventilation temp Avg. 45C
Normal H2O vapour in Dry Air 0.2 0.28kg H2O vapour / kg dry air. Mill surface Temp 40C
Mill Surface Area 90.5M2 Total Heat Input Heat entering Mill with Clinker 49248K cal / hr Heat entering Mill with Gypsum 2797.2K cal / hr Heat entering Mill with Air. 4.665K cal /kg air Heat entering Mill with Motor. 2094960K cal / hr Total Heat entering Mill 2147005K cal / hr
Total Heat Output
Heat leaving With H2O Vapour 621.7K cal / kg H2O vapour / Kg Air Heat leaving with Air. 304367.9K cal / kg 29.545K cal / kg air
Heat leaving with Cement 324900Kcal / Hr Heat leaving through mill Surface 9854.108Kcal / Hr Total Heat leaving Mill only 379196.9K cal / hr Total amount of Air in Mill 10301.84Kg / hr Air per ton of Cement 572.32Kg / ton Total amount of Water in Mill 2431.23Lit/ hr Amount of Water. lit/ ton cement 135.07lit/ ton water Vapour / Kg Air 0.24kg/kg Air With determined air Volume, and
without water injection, the Cement
Temp. would be …… 482.72C
Vikpro
Grinding and Generation of Heat.
Mill Dia Mill Length Mill Capacity Gypsum % Clinker input Gypsum input
Power input, Mill
Clinker Temp. ( Tk )
Gypsum Temp. ( Tg)
Cement Temp. ( Tc)
Temp. of Air ( TL )
Mill vent Air per kg of Cement.
Mill Ventilation temp Avg.
Mill surface Temp
Mill Surface Area
Specific Heat of Cement 0.184
Radiation of Mill shell / m2
Specific Heat of Air.
1) Loss of efficiency by generating heat in the Mill
2) Loss by Radiation through mill shell.
3) Losses by heating the mill vent Air.
4) Losses not measurable such as sound generation &
Vibration.
5) Total KWh
6)Total % of power converted into Heat.
75 % of motor efficiency Considered.
Heat Balance ( Mill ) Mill Dia 2.2m Mill Length 12m Mill Capacity 18t/h Gypsum % 4% Clinker input 17.28t/h Gypsum input 0.72t/h Power input, Mill 2436Kw Power input, Motor 600Kw Clinker Temp. ( Tk ) 15C Gypsum Temp. ( Tg) 15C Cement Temp. ( Tc) 95C Temp. of Air ( TL ) 15C Temp. of Water ( Tw ) 15C Mill Ventilation temp Avg. 45C
Normal H2O vapour in Dry Air 0.2 0.28kg H2O vapour / kg dry air. Mill surface Temp 40C
Mill Surface Area 90.5M2 Total Heat Input Heat entering Mill with Clinker 49248K cal / hr Heat entering Mill with Gypsum 2797.2K cal / hr Heat entering Mill with Air. 4.665K cal /kg air Heat entering Mill with Motor. 2094960K cal / hr Total Heat entering Mill 2147005K cal / hr
Total Heat Output
Heat leaving With H2O Vapour 621.7K cal / kg H2O vapour / Kg Air Heat leaving with Air. 304367.9K cal / kg 29.545K cal / kg air
Heat leaving with Cement 324900Kcal / Hr Heat leaving through mill Surface 9854.108Kcal / Hr Total Heat leaving Mill only 379196.9K cal / hr Total amount of Air in Mill 10301.84Kg / hr Air per ton of Cement 572.32Kg / ton Total amount of Water in Mill 2431.23Lit/ hr Amount of Water. lit/ ton cement 135.07lit/ ton water Vapour / Kg Air 0.24kg/kg Air With determined air Volume, and
without water injection, the Cement
Temp. would be …… 482.72C
xxxx, whoever you are,
The picture below shows what a typical answer to your question might be. (never trust any model !) For this calculation, I made some assumptions that might not be suitable for your application (specially
- coal with Low Heat Value of 25.9 GJ/t (wet basis 1% moisture) - coal analysis CHONS-Ash = { 66%, 5%, 5% , 1.5%, 1%, 20.5%} - recirculation of 70% of the hot gases
- mill power consumption of 400 kW, fan power consumption of 40 kW As you can see, 51 kg/h of coal are needed, in this case.
This is equivalent to an heat consumtion of 2.05GJ/tWaterVapor.
This is rather low and it is explained by the heat generated by the mill itself.
The sensible heat from the hot gases represent a power of 367 kW, which is slightly lower than the power of the mill.
The oxygen content in the exhaust gases is rather high: 16.5% .
This might be very undesirable depending on the volatile content and the fineness. I maintained the requested gas speed at mill end (1.5 m/s).
Finally, the dew point of the exhaust gases is 54°C which is nearly 30°C between the gas temperature. Increasing the recirculation will decrease the oxygen level.
Increasing the recirculation will also decrease the heat consumption.
For example, with a recirculation of 90%, the oxygen level drops to 9.7% and the heat consumption to 38 kg(coal)/h or 1.53 GJ/tWaterVapor.
Note that increasing the recirculation also increases the dew point in the gas circuit. Eventually, the dew point will come too close to the gas temperature, and the risk of condensation on cold points will increase. Here, for 90% recirculation, the dew point rises to 77°C which is only 7°C below the gas temperature. Overall, I like pictures!
What should be ideal tyre migration values for all three stations for a 6.2x90 , 10000 TPD kiln? Is there any relation between Kiln dia and ideal value?
