Vertical Roller Mill

VERTICAL VERTIC AL ROLLER MILLS

© Confederation of Indian Industry

Vertical Roller Roller Mills Mills (VRM)  An

advancement over over ball mill



Roller Rol ler mil milll – Grin Grindin ding g b b Com!r Com!ress ession ion



Rollers " #alls on ring



$resentl %or Ra& meal' Coal  Cement



More Energ e%%icient © Confederation of Indian Industry

VRM  *eat+re *eat+res s  VRM

,rive  -./ o% ball mill



,r moist+re +! to 01 /



More com!act  Less s!ace



*an $o&e $o&err cons cons+m +m!t !tion ion  2ig3 2ig3



Se!ar Se!arat ator or  In Inte tegr gral al $ar $artt o% Mill Mill © Confederation of Indian Industry

*eat+res o% VRM  Energ 

E%%icient Grinding Sstem

Mill Mi ll drive drive – -./ les less s cons+ cons+m!t m!tion ion

 Most Most

s+ite s+ited d %or %or drin dring g – +!to +!to 01/ 01/

moist+re  More

com!act  occ+!ies less s!ace

 More

amenable %or Controls © Confederation of Indian Industry

Com!arison o% #all Mill  VRM #all Mill

Moist+re (/) Mill ,rive (+nits"ton) *an 8 se!arator Total

VRM

45.

65.

45.

65.

0-5.

0-5.

751

751

059

15.

651

651

0159

095.

0-5.

0-5.

Ideal c3oice %or 3ig3 moist+re material © Confederation of Indian Industry

E:ERG; SAVI:G I: VRMs 

*ine t+ning o% lo+vres



Mec3anical Recirc+lation sstem



2ig3 e%%icienc classi%ier



2ig3 Level Control sstem


Install Variable Area Lo+vre Ring  Air

%lo& inside VRM not +ni%orm

 Material

leaves in a de%inite !attern

aro+nd table  Ma<5

material be3ind and in %ront o% eac3

roller


Install Variable Area Lo+vre Ring 

=ni%orm area lo+vre ring 

=ni%orm gas sstem



=neven bed o% material



Gas !re%ers !at3 o% least resistance



2ig3er gas %lo& rates essential


Install Variable Area Lo+vre Ring  Variable 

area lo+vre ring

Larger area at !oints o% larger concentration



Gas %lo& directed to material



$otential o!en area 3ig3er



Lo&er $r5,ro! and lo&er gas %lo&



Red+ced %an !o&er cons+m!tion



$resentl %i


$r5,ro! across mill – >6.MM ?G



*lo& t3ro mill – 4'-.'... M4 " 2R



Mill o+t!+t – 011 T$2



Recommended to install variable area lo+vre © Confederation of Indian Industry


$r5 ,ro! across mill – >@. MM ?G



*lo& t3ro mill – 4'0.'... M4"2R



Mill o+t!+t – 011 T$2

 Ann+al

savings – 01... =S,


R e j e c t s

Area – 1.132 m2

G a s R e j e c t s

,

C

#

A A

#

C ,

Velocity – 83 MPS

E

*

* E

E *

,

*

C

r e l l o R 1

E , C #

4 Roller

# A A 2 Roller

# C

A A

,

r e l l o R 3

#

E *

C

*

,

o r o t M

E

Mill Door

E *

*

E

# , C # A A


C

R e j e c t s

, G a s R e j e c t s

*an $o&er Cons+m!tion in VRM 

2ig3 in com!arison to #all Mill



Maor Reason  2ig3er 

!ress+re dro!

-.. – 9.. mm ?G

 2ig3er

air %lo& rates


$ress+re dro! in a VRM 

Ranges %rom -..  9.. mm ?g



$ress+re dro! 

61/  Mill lo+vre



@1/  2o+sing  classi%ier


?3 2ig3 $ress+re ,ro! B 

2ig3 lo+vre velocit  11 – >1 m"sec



?3 3ig3 lo+vre velocit B 

Li%t !articles o% 3ig3er siDes 



Grinding table to se!arator

Red+ction o% lo+vre velocit 

Red+ction o% mill  $



2ig3er +antit o% reects at mill bottom


Mec3anical Recirc+lation Sstem 

Reects 3andled mec3anicall



Recirc+lated bacF to mill t3ro+g3 #E



Tremendo+s red+ction in !ress+re dro!  energ cons+m!tion


Installation o% Mec3anical Recirc+lation


Lo+vre velocit vs5 Mill !o&er Lo+vre velocit (m " sec) 61

1.

41

Mill $ (mm ?g)

9..

74.

-1.

Reect rate (/ o% %led)

.

1 – 01/ 01./

*an $o&er (+nits " ton)

759

151

-56

Mill !o&er (+nits " ton)

751

757

65@

Total !o&er

045-

0@50

0@50

 Incl+des !o&er %or mec3anical recirc+lation © Confederation of Indian Industry

Lo+vre velocit – 2o& m+c3 red+ction !ossible B  Air   



%lo& t3ro+g3 mill de!ends on

Lo+vre velocit ,ring re+irement Se!arator re+irement

Red+ction o% lo+vre velocit to lo&er levels  

Large material 3andling e+i!ment Large mill 3o+sing  

Leads to !rese!aration Less stabilit  Table vibration

O!tim+m lo+vre velocities &it3 mec3anical recirc+lation  -1 – 11 m"sec © Confederation of Indian Industry

Red+ce Recirc+lation Air in VRM Recirc+lation 2ig3

air – 7. FM4"2r

recirc+lation air

2ig3 2ig3 2ig3

velocit At lo+vres $ !o&er cons+m!tion


Red+ce Recirc+lation Air in VRM

Trial

taFen

Recirc+lation R$M

red+ced b @. FM4"2R

o% class red5

Same

resid+e maintenance


Red+ce Recirc+lation Air in VRM R"M

*an !o&er cons+m!tion red+ced b 01. F?

Savings 

->... =S,


Se!arators %or VRMHs 

I stage



Static se!arator



II stage



,namic conventional se!arator



III stage 

2ig3 e%%icienc se!arator


2ig3 E%%icienc Se!arators  Air

re+irement lo&er



2ig3 e%%5  .57 – .5> Fg matl " Fg o% air



Conv5

 .5- – .51 Fg matl5 " Fg o% air



#etter se!aration e%%icienc



Lo&er  $J across mill



2ig3er o+t!+t  lo&er s!eci%ic energ cons+m!tion © Confederation of Indian Industry

2ig3 e%%icienc Se!arator

Old Se!arator

*eat+res o% 3ig3 e%%icienc Se!arator 

Minim+m !rese!aration in mill 3o+sing



Ma


Coarse ret+rn dro!s e

*eat+res o% 3ig3 e%%icienc Se!arator 

#ene%its 

Increase in o+t!+t – 0. to 4./



Red+ction in s!eci%ic energ – 

 Ver

051 to 451 +nits"ton

attractive %inanciall


Re!lacement &it3 2ig3 E%%icienc Se!arator (Ra& Mill) #e%ore Ca!acit

A%ter

@1. T$2 @9. T$2

Resid+e (9. )

0051/

045@/

Mill !o&er (+nits " ton)

-56

-50

*an !o&er (+nits " ton)

>51

75@

0454

0.54

Total $o&er


Effect of Roller to Table Dia


E%%ect o% Roller to Table ,ia

For the LM 38.4 the ratio between diameter for roller and table is 0.45, for the Ube LM 45.4 the ratio is 0.5, whereas for the LM 56.4 the ratio is 0.40.


E%%ect o% Roller to Table ,ia LM 38.4

LM 45.4(Ube)

LM 56.4

Diameter of Grinding Table

3.80 m

4.50 m

5.60 m

Diameter of Rollers

1.70 m

2.24 m

2.24 m

Width of Rollers

0.67 m

0.85 m

0.85 m

Kwh/ts, Mill

6.31

5.99

7.00

Kwh/ts, Fan

6.23

5.51

7.00

12/0.8

11/0.8

11/0.9

Dust Load (g/cum)

610

630

595

Delta P, Mill

83

56

87

3-5

2-4

5-8

Residue (90/212 microns)

Vibration of Mill


E%%ect o% O!erating $ress+re Ube LM 40.4

Grinding Pressure

650

662

675

687

700

Capacity

290

295

300

305

310

Kwh/ts, Mill

9.0

9.0

9.0

9.0

9.0

Vibration

4-5

4-5

4-5

4-5

4- 4.5

Delta P of Mill

54

53.5

53

52.5

52

kN/m2


E%%ect o% O!erating $ress+re



0. / increase in Grinding !ress+re 

Ca!acit increase b 6/



Mill drive SEC no c3ange



*an !o&er .51 F?3 " MT red+ction © Confederation of Indian Industry

In%l+ence o% *eed SiDe %or an LM -.5- Ra& Mill Max 90 mm Max 30 mm Capacity

240

262

Kwh/ts, Mill

8.05

7.41

Delta , Mill

76

73

5&7

4&6

!i"#ati

%$© Confederation of Indian Industry

2ig3 Level Control Sstem %or Mills 

Conventional – O!en loo! controls



I Generation  



$J vs *eed controls

Latest control sstem 

Min5 4 to 1/ im!rovement – $rod+ction  Energ



More stable o!eration o% VRM © Confederation of Indian Industry

2ig3 Level Control Sstem %or Mills 

Latest control sstem  *eedJ

– #ased on $' Load 

Recirc+lation (#5E)  Mill 



%lo&J Fe!t constant

Mill Load'

$' Recirc+lation load



*ineness !redicted



Se!arator s!eed varied

$rediction mec3anism varied de!ending on act+al %ineness © Confederation of Indian Industry

#EST RA? MILL VRM SEC Sl no

$arameter

$lant 0

$lant @

0

O+t!+t' T$2

-.4

4@.

@

Mill ,$' mm ?C

61.

6-.

4

Se! Loading' g"m4

147

-91

-

Mill drive SEC' F? "MT Material

95@1

75..

1

Mill %an SEC'

1579

75-.

F? "MT Material © Confederation of Indian Industry

Vorte< recti%ier %or classi%ier „Vortex Rectifier“

rotor

grit cone

 lo&

d! leading to a red+ced s!eci%ic energ cons+m!tion © Confederation of Indian Industry

Vorte< recti%ier %or classi%ier  Vorte<

Finetic energ rec+!eration

 Restores

a linear

%lo& in t3e d+ct&orF


Install Vorte< recti%ier %or classi%ier

conventional design

L,C (ne& design)

 3ig3

 3omogeneo+s

velocit di%%erences

distrib+tion © Confederation of Indian Industry

velocit

To S+m=!  VRM

– ,evelo!ing into an e
c3oice 



Ra& mill' Coal' Cement  Slag

*+rt3er im!rovement o!!ort+nities 

Mec3anical recirc+lation



2ig3 e%%icienc se!arators



2ig3 level control sstem © Confederation of Indian Industry

Vertical Roller Mill

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