Loesche Round Table VICAT

Performance of Vertical Roller Mills at Bharathi Cement Corporation Pvt. Ltd., Nallalingayapalli Olivier Thomas Performance Director

Technical Configuration 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.

- 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). Loesche India Round Table 2012

2

© by LOESCHE GmbH

Cement Plant:

Commissioning Phase Focus Point – LM 53 3+3 – Successful Learning Curve Think, 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.

• Adjust hydraulic settings accordingly after this first phase to ensure a “sustainable” capability of successful start-up when pressing the ‘start’ button for the next times.

Loesche India Round Table 2012

3

© by LOESCHE GmbH

• Proceed with frequent in-the-field inspections with Loesche’s commissioning engineers.

Commissioning Phase 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!

• A lower draft (or total flow) increases the efficiency of the separator  Never overlook this aspect. Loesche India Round Table 2012

4

© by LOESCHE GmbH

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

Commissioning Phase Performance – Conversion Factor Compare to supplier’s specification

Clinker Grinding: Expected Output (t/h) = Nominal Output / (Targeted Blaine / Original Blaine) ^ 1.4 Formula 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.

See next slide for Polysius conversion factor. e.g. LM 56.4. Specification = 21.85 kWh/T at R90µ = 14% or R212µ = 2%. Expected Power Consumption at R90µ = 19%  Nominal Value * (1.04 / 1.14). (See next slide)

Loesche India Round Table 2012

5

© by LOESCHE GmbH

Raw Mix Grinding:

Loesche India Round Table 2012

6

© by LOESCHE GmbH

Commissioning Phase

Commissioning Phase 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).

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 ‘table’ and ‘top section injection’. 4.Draft Fan Speed = f (Total Air Flow). 5.Baghouse Inlet Damper = f (Draft Fan Outlet Pressure).

Loesche India Round Table 2012

7

© by LOESCHE GmbH

Raw Mix Grinding:

Performance Improvement Loesche Optimization Plan - Cement Mill LM 53 3+3 and LM 63 3+3



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).

Loesche India Round Table 2012

8

© by LOESCHE GmbH

Targets:

Loesche India Round Table 2012

9

© by LOESCHE GmbH

Performance Improvement

Performance Improvement

Loesche India Round Table 2012

10

© by LOESCHE GmbH

Not done

Performance Improvement

Loesche India Round Table 2012

Water Injection

11

© by LOESCHE GmbH

Dam Ring

Performance Improvement

Loesche India Round Table 2012

Classifier Static Blades

12

© by LOESCHE GmbH

Cone Stump

Performance Improvement

Loesche India Round Table 2012

13

© by LOESCHE GmbH

Bed formation with ‘S-Roller’ for effective grinding on a specific surface or width of the ‘M-Roller’

Performance Improvement

Loesche India Round Table 2012

Impact of too much water injection

14

© by LOESCHE GmbH

Verification of louver ring blinding pattern

Performance Improvement Technical Calculation – Plant Level:

Rotor Diameter

Mill Output PPC Specific rotor load Air Amount Specific air load Air ratio

Loesche India Round Table 2012

% Speed

Motor Speed

kW 250

VFD 100

rpm 1500

Diameter Perimeter m m 5.35 16.8

230t/h 4.2t/hm2 550000m3/h 0.42kg/m3

Height m 3.273

Reducer Speed n1 (rpm) 1500 600 Ratio Peripheric Rotor Area m2 55.0

n2 (rpm) 95.6 38.3 15.6904

Rotor Circ. Velocity

Standard Value

m/s 26.8 10.7

m/s 25 - 30

Standard Value 10t/hm2 < 0,75kg/m3

2.4m3/kg

15

© by LOESCHE GmbH

CM2/CM3 LSKS 87 Rotor Circonferential Velocity Motor

Motor power

Performance Improvement Bharathi - CM2/CM3 - Specific Grinding Pressure (1 Roller): kN kN kg kN kN/m2 m2

Mr Operational pressure Counter pressure Dcyl Drod Cylinder number per roller Roller diameter Roller width A (projected) Fr Fh F Kt Loesche maximum value

Loesche India Round Table 2012

F = Fr + Fh Fr = (Mr*9,81)/1000 Mr Fh Kt = F/A A 27000 86 20 0.4 0.16 2 2.24 0.71 1.5904

kg bar bar m m

265 931 1196 752 1200

kN kN kN kN/m2 kN/m2

m m m2

16

© by LOESCHE GmbH

Grinding force Roller grinding force Roller weight Hydraulic grinding force Specific grinding pressure Roller projected area

Performance Improvement Bharathi - CM2/CM3 - Calculation - Absorbed Power - KWh/t: N (kW) = kT*A*z*v*µ Master Rollers - M (z) Slave Rollers - S (z) Friction Coefficient (µ) Roller Diameter - Max = 2,5m Min = 2,15m Roller Width] Projected Area (A) Table Diameter Grinding Path Diameter Table Speed Roller Speed (v) Mechanical Coupling - Yield Electrical Motor - Yield Mill Specified Output

3 3 0.1 2.5m 0.71m 1.775m2 5.3 5.3m 22.6tr/mn 47.9tr/mn 0.95 0.960 208t/h

1.47m 0.48m 0.7056m2 4.6 22.6tr/mn 70.7tr/mn

1.18m/s 6.27m/s

PPC

1.18m/s 5.44m/s

3600cm2/g

Theory

Specific Grinding Pressure Absorbed Power - Table Installed Power - Table

Loesche India Round Table 2012

kN/m2 752

kN/m2 650

kN/m2 800

Sum

Power at motor's mtr Forecast

kW

kW

kW

kW

kWh/t

2798

352

3149

3453

16.6

4700

17

© by LOESCHE GmbH

Limestone & M-Rollers' S-Rollers' path path Actual Gypsum Clinker

Performance Improvement Performance Figures Raw Mill #2 – LM 56.4: • Specification – 21,85 kWh/Ton Material at R90µ = 14%. • Expected power consumption = 20.47 kWh/Ton Material. • Expected mill production output = 375 t/h. • Actual grinding fineness at R90µ = 17 to 18%. • Actual Performance. 17.5 kWh/Ton Cement.  415 t/h.

• 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.

Loesche India Round Table 2012

18

© by LOESCHE GmbH

Cement Mill #2 – LM 53 3+3:

Performance Improvement 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 µm and [3 – 30]µm 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.

9.Optimization of clinker granulometry and temperature is also part of getting the best out of a ‘LM 53 3+3’.

Loesche India Round Table 2012

19

© by LOESCHE GmbH

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

Thank You