1. Industrial Applications of Drives

2. Mills
Steel Mills
Paper Mills
Cement Mills
Textile Mills .

3. Steel Mills
Steel mill can refer to the steel works making rolled products from iron ore, but it also designs, more precisely the plant where steel semi-finished casting products (blooms, ingots, slabs, billets) are made, from molten pig iron or from scraps.

4. Functions of Steel Mills
iron making (conversion of ore to liquid iron),
steel making (conversion of pig iron to liquid steel),
casting (solidification of the liquid steel),
roughing rolling/billet rolling (reducing size of blocks)
product rolling (finished shapes).

5. Pig Iron crude iron as first obtained from a smelting furnace, in the form of blocks

6. Iron and Steel
The difference between iron and steel is that iron is an element, and steel is an alloy of iron, small amounts of carbon and another material, usually another element like chromium. 
Iron is alloyed with other elements to make it stronger and more useful and to keep it from rusting

7. Major Steel Plants in India

8. steel plants in India Name Location Owner
Tata Iron And Steel Corporation
Jamshedpur, Jharkhand
Tata Steel
Visvesvaraya Iron And Steel Plant
Bhadravati,
SAIL
Bhilai Steel Plant
Chhattisgarh
Durgapur Steel Plant
Durgapur, West Bengal
Bokaro Steel Plant
Jharkhand
Chandrapur Ferro Alloy Plant
Chandrapur,Maharashtra
IISCO Steel Plant
Asansol,West Bengal
Salem Steel Plant
Tamilnadu
Rourkela Steel Plant
Odisha
Vijayanagar Steel Plant
Bellary Karnataka
Jindal Steel And Power
Visakhapatnam Steel Plant
Visakhapatnam ,AP
Rastriya Ispat Nigam Limited(Vizag Steels)
steel plants in India

9. Semi-finished casting products are classified into following types
Ingots
Blooms
Slabs
Billets

10. Ingots
Ingot is commonly used name for the large sized castings produced in a foundry or during iron making.
Ignots are very large casting products, greater in size and shape than blooms, billets and slabs.
There are no specific standard dimensions for ingots.
Ingot generally has rectangular/square cross section, but it is not necessary that it should be uniform through out its length. (Ingot may have variable cross section.)

11. Blooms blooms has rectangular /square cross section.
The cross section area of bloom is always
greater than 36 Sq inches 
Produced in Blooming MIll .

12. Billets Billet has a square/Rectangular cross section
area , but cross section area of
billet should be same through out
its length.
The cross section area if billet is
always less than 36 in2.
The Billets are used in the manufacturing process of Steel bars.
Produced in Billet mill

13. Slabs
A slab can be considered as a special case of Bloom i.e. a Bloom with lesser thickness. A slab is rolled from an ingot or a bloom .
generally has a rectangular cross section
Slabbing mill

14. Ingot>Bloom>Billet>Slab
If Weight is Compared
Ingot>Bloom>Billet>Slab

16. Rolling Mills(Rolling of steel )
Rolling Mills are divided into four types 1.Reversing hot rolling mill 2.Continuous hot rolling mill 3.Reversing cold rolling mill 4.Continuous cold rolling mill

17. reducing the thickness incrementally with each pass.
Continuous rolling
Reverse rolling
Continuous mill consists of several Strands, Each one of them carrying pressing rolls.
The metal passes through all the stands in only one direction and gets rolled simultaneously by some or all of them.
A reversing mill is a rolling mill in which the work piece is passed forward and backward through a pair of rolls
reducing the thickness incrementally with each pass.

18. Hot rolling and Cold rolling mills
Hot rolling is a mill process which involves rolling the steel at a high temperature (typically at a temperature over 1700° F), which is above the steel's recrystallization temperature
This makes the steel easier to form, and also results in products that are easier to work with
Heavy reduction in area of the work piece can be obtained.
Very thin sections are not obtained
Hot roll surface has(metal oxide) on it , this surface finish is not good
Blooms,slabs,billets ,strips etc are manufactured
Cold rolling occurs with the metal below its recrystallization temperature (usually at room temperature),
It also improves the surface finish and holds tighter tolerances
Heavy reduction is not possible
Thin sections are obtained.
The cold rolled surface is smooth and oxide free
roll it more to get more exact dimensions and better surface qualities.
Polished surfaces

19. Schematic diagram of stages in hot reversing mill

20. Reverse hot rolling mills
Ingot buggy Red hot ingot
Receiving table---Horizontal support to ingot
Weighing table----To weigh passing ingot
Approach table
Intermediate table
Front work table---To provide rigid support to required by working roll to prevent bending
Mill stand Main working Roll
Back work table
Intermediate table-
Runout table To provide rigid support to required by working roll to prevent bending
Shear Table Rolled metal is cut into standard length

21. Process of mill Process---
Reversing hot rolling mills roll out blooms or slabs from hot steel ingots, Which come directly from heating chamber.
MILL STAND—The ingots are rolled by working rolls into blooms, as they pass through the mill stand several times in the forward and reverse directions.
The gap length between the main rolls is reduced gradually in successive passes by bringing down the top roll of the main rolls (Adjustment is made by screw down mechanism)
From ingot ,Bloom is produced

22. screw down mechanism
A screw –down mechanism is used to adjust the position of the top roll for each pass depending upon the reduction of the metal required .

23. Drive used DC motors are used
Blooming Mill can be reversed from 50RPM in forward direction to 50 RPM in reverse direction in just second
Motor capacity varies from 2.5MW to 10MW
Twin drive is used –Top and bottom rolls of each stand are individually driven
Plugging and Dynamic braking are preferred for control scheme.

24. Requirements of the drive
Wide range of Speed variation
Ability of the motor and its control equipement to permit frequent starts and Reversals.
Reversal of the direction of rotation of the motor without causing serious disturbances in the power handling circuits
Automatic control of operation
High reliability
Accuracy
Auxiliary drives—to convey products
for mechanical adjustments

25. Types of Rolls(wheels)

29. Continuous hot rolling mills
It produces Billets or strips
It has 2 group of stands
1.Roughing stand—Reduction of metal size
2.Finished stand—Final thickness is obtained
Each stand may have two high or f our high type rolls
Both provide support to steel.
Metal passes through both sets of stands in only one direction.
Both group of stands roll together or
may not.
They are far apart

30. Four high stand In a four – high stand ,
Inner rolls of smaller diameter are the working rolls
Outer rolls are used to vary and maintain the gap between the working rolls
For continuous operation
Wound rotor type Induction motor
Or Synchronous motor
Or Dc shunt motors are
preferred

31. Requirements of the drives
1.Wide range of speed variation 2.Accuracy Motor should be controlled to a high degree of accuracy to avoid sag of the metal between stands(Motor speed is controlled accurately) 3.Automatic control of operation Sudden application of metal to rolls may drops the speed of rolls, so speed should be restored quickly as possible by control scheme 4. Auxiliary drives—to convey products for mechanical adjustments 5. High reliability

32. Reversing cold rolling mills

33. Schematic diagram consists of
AIM: Production of the desired strip (Thickness reduce)
Reel stand—Strip reel is placed
Tension rolls---prevent bending of working steel and avoids sag and Avoid breaking of strip.
Main stand—Main mill stand where actual process carried away

34. Process
Strip reel is wound on a mandrel(Supporting Stand) on one of the reel stands.
Another stand carries an empty mandrel.
End of the reel is threaded properly
Mill speed is increased gradually.
In this process one reel gets coiled
and other is uncoiled .

35. Process conti
When ,only few turns are left to be rolled ,speed is reduced and direction is reversed ,ensuring that the strip does not come out of the uncoiling reel.
Effective diameter of reel changes as strip is unreeled at input end and reeled up at output end
Same procedure is repeated for both Directions
DC motors are used

36. Requirements of drive Mill stand is of four high type is required.
Inner rolls of smaller diameter(200mm to 500mm) are the working rolls
Outer rolls are used as back up rolls, to prevent bending of work rolls
Coiler and uncoiled are driven by separate motors
Wide range of Speed variation
Ability of the motor and its control equipement to permit frequent starts and Reversals.
Reversal of the direction of rotation of the motor without causing serious disturbances in the power handling circuits
Automatic control of operation
High reliability
Accuracy
Auxiliary drives—to convey products
for mechanical adjustments

37. Continuous cold rolling mills
The metal in this mill passes in only one direction through several successive stands
Four high type
Coiler and uncoiler reel
For continuous operation
Wound type Induction motor
Or Synchronous motor
Or Dc shunt motors are preferred

38. Paper mills
Two main processes 1.Pulp making 2.Paper making Raw material -Wood -Bamboo -Jute

39. Pulp-Pulp is a lignocelluloses fibrous material prepared by chemically or mechanically separating cellulose fibres from wood, fiber crops or waste paper

40. Pulp making
Pulp is made in two ways 1.Mechanical method 2.Mechanical and chemical processing Mechanical method— -Grinding a Wood of 1meter length in stone grinders. Mix with water -Grinder should have constant speed -consumes lot of energy -synchronous motor is used. Speed is rpm Rating is 3Mw –4Mw. End product is PULP

41. 2.Mechanical and chemical processing
Wood  chips(cms)
Chips are treated with alkalies along with other raw material like grass, etc
During chemical treatment ,
material is continuously beaten
(beaters)
For beaters—Slip ring IM is used.
Bleaching Process-Washing ,
cleaning ,refining
End product is PULP

42. beaters

43. Depending upon the size of mill,ratings of motor will differ from kW to MW
Chipper
Beater
Refiner

44. Paper making process involves
Forming of sheets
Removing water from sheets
Drying of sheets
Pressing of sheets
Reeling up of sheets

45. Paper making

48. Process
Couch section(Wire section)—Paper pulp(Moisture content of 98%-99%) is transfered to the wire.
Fibres are uniformly deposited on mesh and water drips down.
Most quantity of water drips through the wire mesh and further removed by sucking.
At the end of this section Moisture content is 80%.

49. Pressing Section
Pressing Section—Sheet is pressed between woollen felt So water is removed from wet sheet
At the end of this section Moisture content is 60-65%.

50. Process conti....
Dryer section—Sheet is dried by passing it over and under the heat cylinders until desired dryness is achieved.
Control of electric drives in this section is very important
At the end of this section Moisture content is 6%.
Calendar section –Sheet is subjected to pressure and Friction so that the compact and smooth surface of sheet
Reel section—Sheet is wound up on a Mandrel(Reel stand)

51. Requirements of paper machine drives
1.Depending on purpose speed may be constant or adjustable. 2.Each section should run at specified speed and all should be independently adjustable . 3.Smooth and quick starting of the sections without causing excessive starting current , are required. 4.Control system employed should be flexible in nature 5.The motor should be capable of running at speeds 10-25m/min some times

52. Types of drives Line shaft drive Sectional drive
Line shaft drive---a  line shaft system uses one prime mover to power the whole machine instead of a different one for each section
Various sections of paper machine
are driven from a line shaft
Cone pulleys and belts through gears

54. Sectional drives
Each section of the paper machine has its own electrical motor .
All the motors are operated from common supply bus
Each motor speed is controlled using converter

55. Sectional paper machine for newsprint paper
Sectional paper machine for fine and medium quality paper
Paper machine for household paper (tissue etc.)
Paper machine for specialty paper

56. terminologies
Draw-it is speed difference between two adjacent sections of the paper machines
Inch reverse—during operation, paper may jammed in the dryer section .to remove the paper it is necessary that paper should come reverse slightly called inch reverse

57. Comparison between line shaft drive and sectional drives
1.all section should run at line shaft speed
2.No close loop control.
Uses pulley and belts speed change is done by slipping of belts.
so no effective speed control of each section
1.Independent operation of sections
2.Close loop feed back control for each section.
Controlling is easy and effectives

58. Comparison conti.....
3.Inch reverse is Not possible 4. In case of fault ,tripping of each section is not possible
3.Inch reverse is possible 4.Each section have its own set of devices that permit starting and safety interlocks any fault occurs ,only that section can be tripped

59. Overloading cannot be sensed and not possible to stop each drive
5.overloading in a particular section can be sensed and drive can be stopped.

60. Cement mill
A cement is a binder, a substance used in construction that sets and hardens and can bind other materials together.
cement is used as a component in the production of concrete and of concrete, which is a combination of cement and an aggregate (sand ,grinded stones etc) to form a strong building material.

61. Process consists of
grinding a mixture of limestone and clay or shale to make a fine "rawmix“
heating the rawmix to sintering temperature (up to 1450 °C or 2600 ° F) in a cement kiln
grinding the resulting clinker to make cement 

62. lime and silica as main components
Raw materials
lime and silica as main components
Alumina and ferric oxide as fluxing components which reduces the melting temperature of silica
Limestone(calcium oxide)
Silica (silicon dioxide)
Aluminium oxide
Ferric oxide(iron oxide)
Water(For wet process)

63. process
Lime stone mined from quarries is crushed and transported to plants by dumpers, trucks or ropeways depending on the area and distance involved.
Crushed limestone now a mixed with required proportion of corrective additives like clay bauxite, iron ore . Together grinded in grinder.

64. Fine powder coming out is homogenised in silos by passage of air

65. Kiln features Over a billion tonnes of cement are made per year
cement kilns are the heart of this production process: their capacity usually defines the capacity of the cement plant. As the main energy-consuming part.
improvement of kiln efficiency has been the central concern of cement manufacturing technology.
Temperature is 2600 ° F
Produces Clinker-grayish black pellets

67. Cement clinker is produced in
kiln at high temperature.
Dry process—composed dry powder is obtained
Wet process-Water is added to raw material while grinding to produce slurry.
after 3-4 days clinker is mixed with right amount of gypsum is fed to cement grinding mills and ground to required fitness.
Cement is stored in bags and
dispatched to dealers

68. Types of drives Raw mill and cement mill drives
grinding a mixture of limestone and clay or shale to make a fine "rawmix" ( Rawmill)
Kiln drives
Crusher drives
Waste gas fan drives
Compressor drives

69. Crusher drive- motor used for crusher is slip ring IM.
without any external resistance in series
Fan drives– slipring IM with speed between RPM
Compressor drive—either slipring or sq cage IM kw

70. Raw mill and cement mill drives—slipring Im of 6.6kv
Kiln drives—slip ring IM or dc motors with ward Leonard speed control
Rating Kw
Maximum speed of kiln is 1RPM
Starting torque should be % of full load torque

71. Textile mills
A cotton mill is a factory housing powered spinning or weaving machinery for the production of yarn or cloth from cotton

72. processes
Cotton to slivers-spinning-weaving-finishing

73. Cotton to slivers
-ginning-process of separating the seeds from cotton
-bales of ginned cotton are transported to mills.
-cleaning--Impurities are picked up and removed in blow room.
-cotton is transformed to laps and fed to cording section.
-converted to slivers
-slivers are gathered in cans and processed in a drawing machine ,which makes uniform fibre.

74. Spinning( slivers -------yarn)
-At this stage sliver is fragile condition and bulky.
-diameter is reduced , and made it to suitable for final spinning.
-Spinning –continuous yarn of sufficient strength
- yarn is wound on bobbin

75. weaving Process is carried in looms
Weaving- means joining of two sets of threads
extends the length of fabric .

76. finishing Finishing involves
bleaching- impurities like oil and grease are removed .whiteness increases.
Calendaring- in which the fabric is passed between heated rollers to generate smooth, polished cloth
dyeing-giving colour to cloth
printing-producing designs and patters in multicolour
packing

77. Motors used for textile process
Loom motors- motors-sq cage IM with high starting torque
Spinning motors-sq cage IM with high starting torque
Card motors-
Carding-- the fibres are separated and then assembled into a loose strand (sliver or tow) at the conclusion of this stage.
motors-sq cage IM with high starting torque
speed is rpm