loesche round table vicat

Performance of Vertical Roller Mills at

Bharathi Cement Corporation Pvt. Ltd., Nallalingayapalli

Olivier ThomasPerformance Director

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2Loesche India Round Table 2012

Line #1 Commissioning in September 2009:

- LM 54.6 for raw mix grinding.- LM 26.3 for coal grinding.- LM 63 3+3 for clinker grinding.

Line #2 - Commissioning in February 2011:

- LM 54.6 for raw mix grinding.- LM 26.3 for coal grinding.- LM 53 3+3 for clinker grinding 2 units.

Cement Plant:

- Budget of 2.46 M Tons Cement of dispatch in 2012.- A-Grade Cement positioned on the south Indian market and MH.- Cement Ratio OPC : PPC : PSC = 45 : 55 : 5.- PPC with an addition of 27 28% of fly ash.- Consumption of Indian, Indonesian, SA coal and petcoke (6% sulphur content)- Usage of secondary fuels Up to 10% substitution rate (wood chips and pharmaceutical wastes).

Technical Configuration

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Commissioning PhaseFocus Point LM 53 3+3 Successful Learning CurveThink, Study, Feel, Measure and Observe Start-up to nominal capacity in 45 days

Phase #1 Start-Up: Ensure a thorough cold commissioning and testing Control management pressure to delay the start-up if necessary.

Work up properly all pre-conditions between parties, especially regarding clinker C3S, temperature and content of additives.

Make sure commissioning engineers have a dedicated operating station.

Start the mill in complete manual mode. Set a lower fineness target Objective to observe and feel the mill.

Proceed with frequent in-the-field inspections with Loesches commissioning engineers.

Adjust hydraulic settings accordingly after this first phase to ensure a sustainablecapability of successful start-up when pressing the start button for the next times.

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Phase #2 Observe & Feel:We are entering a testing phase to determine if the mill can respond to our demand Increase material output and achieve fineness.

Increase grinding pressure If main motor kW do not increase, material is being flushed out of the table by the rollers. It is a way to determine if the dam ring height is adapted.

Increase grinding pressure dP (mill) is decreasing since we are grinding faster and more finer particles are leaving the system faster than coarser particles.

Optimize total air volume so that rejects stay at a minimum.

Determine if sudden dP variations are linked to a change in the clinker quality (granulometry and/or temperature) Do not fight it!

Measure fineness after a few hours Adjust grinding pressure and draft. Keep in mind: Rollers and grinding pressure give Blaine. Separator gives rejects.

A lower draft (or total flow) increases the efficiency of the separator Never overlook this aspect.

Commissioning Phase

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Performance Conversion FactorCompare to suppliers specification

Clinker Grinding:

Expected Output (t/h) = Nominal Output / (Targeted Blaine / Original Blaine) ^ 1.4Formula can be applied to power consumption (or at motor shaft only)

e.g. LM 53 3+3 in OPC at 3,200 Blaine.Specification = 230 t/h at 3,000 Blaine and 25.4 kWh/Ton Cement.Expected Output = 230 / (3,200 / 3,000)^1.4 = 210 t/h.Expected Power Consumption = 25.4 * (3,200 / 3,000)^1.4 = 27.8 kWh/Ton Cement.

Raw Mix Grinding:

See next slide for Polysius conversion factor.e.g. LM 56.4.

Specification = 21.85 kWh/T at R90 = 14% or R212 = 2%.Expected Power Consumption at R90 = 19% Nominal Value * (1.04 / 1.14).(See next slide)

Commissioning Phase

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Commissioning Phase

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Performance Control Loop

Clinker Grinding:

1.Recirculation Damper Position = f (Mill Inlet Pressure).2.Feed Rate = f (Mill Differential Pressure).3.Booster Fan Speed = f (Mill Outlet Temperature).4.Draft Fan Speed = f (Total Air Flow).

Water injection does not control mill outlet temperature for a cement mill (not simply manageable).

Raw Mix Grinding:

1.Recirculation Damper Position = f (Mill Inlet Pressure).2.Feed Rate = f (Mill Differential Pressure).3.Water Injection = f (Mill Outlet Temperature) See control philosophy between tableand top section injection.4.Draft Fan Speed = f (Total Air Flow).5.Baghouse Inlet Damper = f (Draft Fan Outlet Pressure).

Commissioning Phase

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Loesche Optimization Plan - Cement Mill LM 53 3+3

and LM 63 3+3

Targets:

Increase mill output. Reduction in Specific Power Consumption. Consistency of produced cement quality. Stability of operation. Optimize water consumption for bed formation (Important in India).

Performance Improvement

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Not done


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Dam Ring Water Injection


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Cone Stump Classifier Static Blades


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Bed formation with S-Roller for effective grinding on a specific

surface or width of the M-Roller


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Verification of louver ring blinding pattern

Impact of too much water injection


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Technical Calculation Plant Level:

CM2/CM3 LSKS 87Motor power % Speed

Motor Speed Reducer Speed

Rotor Circ. Velocity

Standard Value

Rotor Circonferential Velocity kW VFD rpm n1 (rpm) n2 (rpm) m/s m/sMotor 250 100 1500 1500 95.6 26.8 25 - 30

600 38.3 10.7Ratio 15.6904

Diameter Perimeter HeightPeripheric Rotor Area

m m m m2Rotor Diameter 5.35 16.8 3.273 55.0

Mill Output PPC 230t/h Standard ValueSpecific rotor load 4.2t/hm2 10t/hm2

Air Amount 550000m3/hSpecific air load 0.42kg/m3 < 0,75kg/m3

Air ratio 2.4m3/kg


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Bharathi - CM2/CM3 - Specific Grinding Pressure (1 Roller):Grinding force kN F = Fr + Fh

Roller grinding force kN Fr = (Mr*9,81)/1000Roller weight kg Mr

Hydraulic grinding force kN FhSpecific grinding pressure kN/m2 Kt = F/A

Roller projected area m2 A

Mr 27000 kgOperational pressure 86 bar

Counter pressure 20 barDcyl 0.4 mDrod 0.16 mCylinder number per roller 2

Roller diameter 2.24 mRoller width 0.71 mA (projected) 1.5904 m2

Fr 265 kNFh 931 kNF 1196 kNKt 752 kN/m2

Loesche maximum value 1200 kN/m2


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Bharathi - CM2/CM3 - Calculation - Absorbed Power - KWh/t:N (kW) = kT*A*z*v*

Master Rollers - M (z) 3Slave Rollers - S (z) 3Friction Coefficient () 0.1Roller Diameter - Max = 2,5m -Min = 2,15m 2.5m 1.47mRoller Width] 0.71m 0.48mProjected Area (A) 1.775m2 0.7056m2Table Diameter 5.3Grinding Path Diameter 5.3m 4.6Table Speed 22.6tr/mn 1.18m/s 22.6tr/mn 1.18m/sRoller Speed (v) 47.9tr/mn 6.27m/s 70.7tr/mn 5.44m/sMechanical Coupling - Yield 0.95Electrical Motor - Yield 0.960Mill Specified Output 208t/h PPC 3600cm2/g

Theory

ActualLimestone &

Gypsum ClinkerM-Rollers'

pathS-Rollers'

path Sum Power at

motor's mtr ForecastkN/m2 kN/m2 kN/m2 kW kW kW kW kWh/t

Specific Grinding Pressure 752 650 800Absorbed Power - Table 2798 352 3149 3453 16.6Installed Power - Table 4700


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Performance Figures

Raw Mill #2 LM 56.4:

Specification 21,85 kWh/Ton Material at R90 = 14%. Expected power consumption = 20.47 kWh/Ton Material. Expected mill production output = 375 t/h. Actual grinding fineness at R90 = 17 to 18%. Actual Performance.

17.5 kWh/Ton Cement. 415 t/h.

Cement Mill #2 LM 53 3+3:

Specification. PPC = 29.2 kWh/Ton Cement and 203 t/h at 3,600 Blaine.

PG Test. PPC = 21.38 kWh/Ton Cement and 217 t/h at 3,625 Blaine.

Daily Plant Operation. PPC = 26.9 kWh/Ton Cement and 201 t/h at 3,570 Blaine.


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Operation of vertical mills for clinker grinding:

1. Performances are achieved in a reliable manner.

2.Increase of mill output is noticeable during longer operational runs.

3.Specific Power Consumption has decreased (expect 1 to 2 kWh/Ton Cement).

4.Rejects below 45 m and [3 30]m range are consistent and there is room for

adjustment with the separator Check water demand on a regular basis.5.LM 53 3+3 operates with stability and is to be considered as a good system when

analyzed thoroughly and operated properly.

6.Water injection remains too high (3.5% of total mill output) and needs to decrease to

2.5%.

7.Hardfacing on the rollers and table remains an expensive maintenance operation.

8.Commissioning needs always to be combined with an analysis of clinker grindability.

9.Optimization of clinker granulometry and temperature is also part of getting the best

out of a LM 53 3+3.


Thank You

loesche round table vicat

Documents

coal grinding

grinding pressure dp

raw mix grinding

kwhton cement

cement plant

grade cement

expected output th

sure commissioning engineers