APPLICATIONS OF VIBRO FEEDERS IN VISAKHAPATNAM STEEL PLANT MINIPROJECT REPORT A Dissertation submitted in partial fulfillment of the Requirement for the award of the degree of Bachelor of technology In Electrical & Electronics Engineering BY L .NAVEEN (09JH1A0228) B .SANKARA RAO (09JH1A0207) K .VENU PRASAD (09JH1A0226) N .MADHU BABU (09JH1A0230) G .VIDYADHAR (09JH1A0248)
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APPLICATIONS OF VIBRO FEEDERS IN
VISAKHAPATNAM STEEL PLANT
MINIPROJECT REPORT
A Dissertation submitted in partial fulfillment of the
Requirement for the award of the degree ofBachelor of technology
In
Electrical & Electronics EngineeringBY
L .NAVEEN (09JH1A0228)
B .SANKARA RAO (09JH1A0207)
K .VENU PRASAD (09JH1A0226)
N .MADHU BABU (09JH1A0230)
G .VIDYADHAR (09JH1A0248)
G.V.V.R .INSTITUTE OF TECHNOLOGY,
BHIMAVARAM
ACKNOWLEDGEMENT
We express our deep sense of gratitude to our project guide
Sri. S.SUDHAKARA REDDY Asst. General Manager (E), Steel Melting
Shop of Visakhapatnam Steel Plant for his excellent guidance,
encouragement and valuable advice throughout the course of my
project.
We are thankful to the Training Department for providing us
an opportunity for doing this project.
L.NAVEEN
B.SANKARA RAO
K.VENUPRAS
AD
N.MADHU
BABU
G.VIDYADHAR
CERTIFICATE
This is to certify that Sri L.NAVEEN , Sri B.SANKAR RAO , Sri K.VENU
PRASAD , Sri N.MADHU BABU , Sri G.VIDYADHAR has done the
project titled“APPLICATIONS OF VIBRO FEEDERS”
under my guidance as a partial fulfillment of 3rd B.Tech (EEE)
HEAD OF THE DEPARTMENT INTERNAL GUIDE
Sri V.VERRAJU S.SUDHAKAR REDDY,
EEE Department, Asst.Genaral Manager (E),
G.V.V.R .INSTITUTE OF TECHNOLOGY , Steel Melt Shop,
BHIMAVARAM. VISAKAPATNAM STEEL
PLANT.
CERTIFICATE
This is to certify that Sri L.NAVEEN has done the mini project titled“APPLICATIONS OF VIBRO FEEDERS”
under my guidance as a partial fulfillment of 3rd B.Tech (EEE)
.
HEAD OF THE DEPARTMENT INTERNAL GUIDE
Sri V.VERRAJU S .SUDHAKAR REDDY,
EEE Department, Asst.Genaral Manager (E),
G.V.V.R .INSTITUTE OF TECHNOLOGY , Steel Melt Shop,
BHIMAVARAM. VISAKAPATNAM STEEL PLANT.
.
CERTIFICATE
This is to certify that Sri B.SANKARA RAO has done the mini
project titled “APPLICATIONS OF VIBRO FEEDERS” under my
guidance as a partial fulfillment of 3rd B.Tech (EEE).
HEAD OF THE DEPARTMENT INTERNAL GUIDE
Sri V.VERRAJU S .SUDHAKAR REDDY,
EEE Department, Asst.Genaral Manager (E),
G.V.V.R .INSTITUTE OF TECHNOLOGY , Steel Melt Shop,
BHIMAVARAM. VISAKAPATNAM STEEL PLANT.
CERTIFICATE
This is to certify that Sri K.VENU PRASAD has done the mini project titled“APPLICATIONS OF VIBRO FEEDERS”
under my guidance as a partial fulfillment of 3rd B.Tech (EEE)
HEAD OF THE DEPARTMENT INTERNAL GUIDE
Sri V.VERRAJU S .SUDHAKAR REDDY,
EEE Department, Asst.Genaral Manager (E),
G.V.V.R .INSTITUTE OF TECHNOLOGY , Steel Melt Shop,
BHIMAVARAM. VISAKAPATNAM STEEL PLANT.
CERTIFICATE
This is to certify that Sri N.MADHU BABU has done the mini project titled“APPLICATIONS OF VIBRO FEEDERS”
under my guidance as a partial fulfillment of 3rd B.Tech (EEE)
HEAD OF THE DEPARTMENT INTERNAL GUIDE
Sri V.VERRAJU S .SUDHAKAR REDDY,
EEE Department, Asst.Genaral Manager (E),
G.V.V.R .INSTITUTE OF TECHNOLOGY , Steel Melt Shop,
BHIMAVARAM. VISAKAPATNAM STEEL PLANT.
CERTIFICATE
This is to certify that Sri G.VIDYADHAR has done the mini project titled“APPLICATIONS OF VIBRO FEEDERS”
under my guidance as a partial fulfillment of 3rd B.Tech (EEE)
HEAD OF THE DEPARTMENT INTERNAL GUIDE
Sri V.VERRAJU S .SUDHAKAR REDDY,
EEE Department, Asst.Genaral Manager (E),
G.V.V.R .INSTITUTE OF TECHNOLOGY , Steel Melt Shop,
BHIMAVARAM. VISAKAPATNAM STEEL PLANT.
DECLARATION
We here by solemnly declare that the mini project titled
“APPLICATIONS OF VIBRO FEEDERS” is a genuine
bonafide work done by us and is not submitted by any others at any
time before.
The Project work was done in partial fulfillment of the requirements
for the completion of 3rd B tech (EEE)
L.NAVEEN
B.SANKARA RAO
K.VENU PRASAD
N.MADHU BABU
G.VIDYADHAR
CONTENTS
S.NO. Title
1. Introduction to VSP
2. Overview of SMS
3. Description of VIBRO FEEDERS.
4. Operation of VIBRO FEEDER derives details.
5. Importance of storage and handling instructions.
6. Installation process.
7. Feeder controls.
8. Circuit diagrams for vibro feeders.
9. Applications.
10. Advantages and disadvantages of vibro feeders.
1. Introduction to Visakhapatnam Steel Plant
Visakhapatnam Steel Plant (VSP), the first integrated shore based ( bay of
Bengal shore at east side) steel plant in the public sector, is located at
Visakhapatnam in the State of Andhra Pradesh with a capacity of 3 MT liquid
steel production per year. Expansion works going on to increase capacity to 6.3
MT per year. Planning to expand to 16MT capacity by 2020 in phased manner.
Besides this, VSP has five Regional Marketing Offices and 21 Branch Sales
Offices with a wide network of Stockyards all over the country to support
marketing and distribution of its products and services.
VSP is renowned for its modern technology and facilities. Many of
them are incorporated for the first time in the country. The salient
technological features are:
2 7m tall Coke Oven Batteries with coke dry quenching.
3 Biggest Blast Furnaces in the country with 3200 cum useful volume.
4 Bell less top charging system in Blast Furnaces (BF).
5 100% slag granulation at the BF cast house.
6 LD gas recovery system.
7 100% Continuous Casting of Liquid Steel.
8 High speed and high capacity Rolling Mills.
9 Extensive Waste heat recovery systems.
10 Comprehensive pollution control measures.
VSP is an integrated steel plant that produces long products. Its products
are Wire Rods, Plain and Reinforced Bars, Light and Medium Structural, Rounds
Squares, Basic grade Pig Iron and Coal Chemicals, etc. In addition to finished
steel, the product mix of VSP envisages production of semi-finished products
like Blooms and Billets with a view to balance the product-mix. VSP caters to
the Construction industry, Railways, Automobile industries, Engineering
and Howler Tone alert etc. All exchanges working in the steel plant are
interconnected by means of junction lines and have closed numbering scheme.
The 2000 lines exchange in township is interconnected to the BSNL
network. Due to this interconnection all the subscribers of this exchange can
receive incoming calls from any part of the world. A few subscribers are
provided with facility to contact subscribers connected to the BSNL network
and cellular and mobile phones in and around Visakhapatnam.
PROCESS COMMUNICATION SYSTEMS: -
To facilitate coordination, operation & management activities of
production, maintenance & service departments, the following process
communication systems are provided:
a) Dispatcher communication system
b) Loudspeaker intercom systems
c) Loudspeaker broadcasting systems
d) Loudspeaker conference communication system
e) Industrial public address system
f) Hotline communication systems
g) VHF communication systems
MONITORING AND SIGNALING SYSTEMS: -
To facilitate monitoring production, maintenance & service activities, the
following monitoring and signaling systems are provided:
a) Closed Circuit Television Systems (CCTV)
b) Central fire alarm signaling system
c) SCADA system
d) Shift change Announcement Siren System and air raid-warning system
3.STEEL MELTING SHOP
STEEL MELT SHOP (SMS):-
Steel is an alloy iron and carbon, where carbon should be less than 2%.
Hot metal produced in B.F contains impurities like carbon, sulphur,
phosphorous, silicon etc., these impurities will be removed in steel making by
oxidation process. There are three L.D converters to convert hot metal in to
steel. The steel melt shop comprises two 1300-ton hot metal mixers, three 130-
ton LD converters and six 4-stand bloom casters. Each converter is being
provided with gas cleaning plant for cleaning and recovery of LD gas, which
will be used as a fuel in plant.
CONVERTER IN SMS
Continuous Casting Machine (CCM) receives Liquid Steel from the
LD Converters and 100% Continuous casting is done in these machines.
CCMs produce 320mm x 250mm and 250mm x 250mm sized blooms,
which are sent to LMMM & MMSM rolling mills for rolling as per the
customer requirement for sale. This is a continuous process & CCMs
are expected to cast liquid steel without any interruption for profitable
operation & higher productivity. After tapping is done from convertor,
liquid steel is brought to Continuous Casting Machine in a ladle. From
ladle liquid steel is throttled into the Tundish through which liquid steel
is throttled into the moulds for casting.
CONTINUOUS CASTING DEPT
SECTIONS OF SMS
MIXER SHOP
Metallic horizontal cylindrical devices with refractory brick lining
inside are called mixers. Liquid pig iron at 1500oC from Blast Furnaces will
be stored in mixers (2 no of mixers are there in SMS), each of them are
capable of storing 1300 T of hot metal. For this purpose, two no. of 200T
capacity EOT (Electrically over transmission) cranes installed. Each mixer is
tilted by two Thyrister controlled DC motors simultaneously to tap liquid
metal whenever required. Each time 150 T of hot metal will be collected in
to ladle and will be shifted to converter shop by Hot metal transfer car
driven by thyristor control DC motor.
CONVERTER SHOP
Pig iron will have the impurities like Sulpher& Phosphors and 4% carbon.
Steel will have 1% carbon. To convert liquid pig iron into liquid steel LD
converters will be used. 3 nos. of LD converters are there in converter shop.
Four thyristor controlled DC motors will tilt each converter simultaneously.
150T of Liquid pig iron (hot metal) will be charged into converter. For this
purpose, two no. of 200T capacity EOT (Electrically over transmission)
cranes installed. Oxygen will be blown in to converters through lance for 17
minutes to get steel. Each converter will have 2 lances (one is standby),
each driven by thyristor controlled DC motor. After process 150 T of liquid
steel at 1700oC is collected in to refractory brick lined steel vessel ( called
ladle ), which placed on thyristor controlled DC motor driven Steel Transfer
Car (STC). Similarly Waste material (called liquid slag ) will be collected into
slag pot, which placed on thyristor controlled DC motor driven Slag pot
Transfer Car (SPTC). To treat at ladle furnace, injection refining & up
temperature and return of ladles 3 more such cars will be used.
Large quantity of Carbon Monoxide will be produced in this process,
which will be collected by induce draft fans and used as fuel in reheating
furnaces. These fans will be driven by 6.6 KV, 2.5 MW, 3- phase induction
motor. Each converter will have one motor. For dust exhaust system 6.6
KV, 1.0 MW, 3- phase induction motor will be used ( one for Converter shop
and one for mixer shop ). For cooling system each converter will have 4
circulating water pumps, 4 fin fan coolers, 2 makeup water pumps. All these
motors are 3- phase induction motors.
Raw materials will be shifted by 7 conveyors and these motors also 3-
phase induction motors. Slag yard and scrap yard are equipped with 2 EOT
cranes each. Slag yard was equipped with 3- phase induction motors driven
2 slag dump cars. Ladle preparation bay was equipped with 3 EOT cranes.
CONTINUOUS CASTING DEPARTMENT
Steel from converters will be further treated by adding ferro-silicon,
ferro-manganese etc., and trapped oxygen will be removed by adding
aluminum. This will be mixed by argon rinsing. Temperature will be raised in
Ladle furnace or IRUT if required.
With the help of 200 T EOT crane (3 nos are there) ladle will be placed
on stand and Steel will be solidified (casted) into rectangular bars called
blooms. These blooms are stored in Bloom Storage yard and dispatched to
rolling mills with the help of EOT cranes for required shape.
EOT CRANES
In SMS itself 50 EOT cranes are available. These cranes are installed on
rails at certain height Power supply will be tapped from bus bars (called Direct
Supply Lines) through sliding current collector assembly. Three movements in
both directions with three or four different speeds are required namely Long
Travel, Cross Travel and Hoist. Some cranes will have two cross travels and two
or three hoists. Long travel will have four ( two in case of very small cranes )
slip ring induction motors. Each Cross Travel, Hoist (2 motors in case of big
cranes ) will have one slip ring induction motor.
VIBRO FEEDERSDESCRIPTION:-
The TRF Electro magnetic Vibrating Feeder consists basically of:
1. A trough for conveying the material. This is usually of Fabricated mild Steel construction,Either open, enclosed, tubular, or of a section specially designed to suit requirements and in general can be supplied with liners or wearing plates when necessary .
2. A vibrator unit of cast iron construction which is generally mounted below the trough.
3. A spring system under compression which connects together the trough and the vibrator unit.
4. An Electromagnet consisting of a laminated armature attached to the trough and an E or U shaped laminated core attached to vibrator unit. The core separated
from the armature by an air gap is fitted with either one or two coils which are energized by a pulsatingcurrent .The machine, therefore,forms a spring-connected two-mass vibration system with the electromagnet providing the exciting force.
The springs are so chosen that the natural frequency of the machine corresponds approximately to the frequency of the pulsating power supply. In this way full advantage is taken of the high amplitude and low power consumption associated with a two-mass vibrating system operating under conditions of resonance.
The feeder can be supported in position by means of suspension rods or by floor mountings and in each case adequate vibration absorbers are incorporated.with single vibrator feeders a combination of suspension and floor-mounting is permissible, but is not recommended for multi vibrator machines.
Vibro –conveyors, long feeders ,and some large heavy duty feeders are fitted with more than one vibrator. With such machines all vibrators automatically operate in synchronism when connected to the same power supply.
Feeder Grizzlies are similar to standard feeders with the exception that an inclined section of self-relieving Grizzly bars is fitted at the discharge end.
Specially designed troughs for de-breezing,bagging, spreading etc.., are also available to suit particular requirements.
Vibro feeder internal diagram
Principle of operation:-The vibrator coils are energized by a unidirectional pulsating current derived from the A.C mains supply by means of half wave rectification or by the electronic methods. Thus 50 impulses per second are produced when operating on the standard 50 cycles supply.
On the powered part of the cycle, i.e, when current is allowed to flow, magnetic attraction takes place between the core and armature of the electromagnet. The trough and the vibrator unit are therefore drawn towards each other, and at the same time the spring system is deflected.
The resulting restoring force built up in the deflected spring causes the return stroke to be completed during the non-powered part of the cycle ,and the trough and the vibrator unit therefore move away from each other.
This sequence is repeated during each complete full cycle of the A.C. power supply causing the machine to vibrate at the same frequency as that of the supply, i.e. 50 vibrations per second on a 50 H.Z supply.
Some small light duty feeders operate direct from the A.C. mains without half-wave rectification .thus,as the coils are energized twice each complete cycle the frequency of vibration is twice that of the power supply i.e.100 vibrations per second on a 50 cycle supply.
The amplitude of vibration is controlled by varying the power input to the vibrator coils by means of a thyristorised electronic controller or a rheostat or a variable transformer suitable for 415 volts, single phase 50 cycle supply.
STORAGE AND HANDLING INSTRUCTIONS:-
STORAGE:-
1. Store the machine under the cover of roof if possible or otherwise it should be necessarily coverd by tarpaulins.
2. The springs must not be taken out or loosened and the trough should not be seperated from the casting while storing or installing the equipment. However,if it is unavoidable please contact TATA-ROBINS-FRASER LTD,jamshadpur -831007.
3. Take extra care to avoid the possibility of water entering the coil & making it damp.
4. The suspension rods should be carefully stored to avoid the possibility of bending and threads being spoiled.
5. Other accessories like electronic controller or rectifier,rheostat etc.. should be kept with extreme care under the cover of roof and extra care should be taken to avoid the possibility of water entering and making the equipment damp.
6. Do not remove or loosen any bolt.
HANDLING :-
1. Avoid dragging,bumping and side jacking to prevent distortion.
2. Do not sling around springs and around the trough.
3. Do not open out or cut off any part of the feeder. The suspension rods can be opened if it is necessary.
4. Extra precautions should be taken not to disturb the position of the springs while handling or installing.
5. All the spare parts should be stored in a dry and clean area protected from the weather.
INSTALLATION
GENERAL:-
Feeders and feeder grizzlies can usually be erected in position without any dismantling of the machines being required.
If however,sight conditions make it necessery for the trough to be removed from the vibrator bracket to facilitate erection ,care should be taken to ensure that on reassembly all bolts fixing the trough to the vibrator bracket are thoroughly tightened.high strength friction grip bolts,when fitted,should be tightened in accordance with the torque values as givcen under “MAINTENANCE”.
All bolts should be further checked for tightness after a week’s operation.
If further dismantling is found to be necessary, e.g,removal of the vibrator bracket from the vibrator assembly,the advice of TRF should be obtained.
ANGLE OF INSTALLATION :-
For free –flowing materials the normal angle of installation of the feeder trough is 10 deg downhill, unless otherwise agreed or advised by TRF.
For sticky materials provision should be made to enable the angle to be increased to at least 15 deg in order to facilitate the flow of material.
SUSPENDED TYPE FEEDERS :-
Suspension rods should always be attached to a main structure.
Suspension from long un supported spans of structural steel work should be avoided as loss of effective vibration in the machine will occure if the structure is insufficiently rigid and likely to flex.
Suspension rods should be supported by a plate or bracket not less than ¾ ‘thick mounted at 90 deg to the line of the rods.
All rods should be well clear of local obstructions to allow the feeder to swing freely under working conditions. This is particularly important when rods have to pass through a concretefloor, or between parts of deep section channels.
The inclination of suspension rods will depend on the position of the support points, but they must be symmetrically inclined when viewed from the end of the feeder and vertical when viewed from the side. By splaying out the rods symmetrically excessive side movement of the feeder can be prevanted.
Each pair of rods should be evenly loaded. The loading on any rod can be adjusted by slightly lengthening or shortening the effective rod length by means of the fixing nuts or turnbuckle, if fitted.
When a feeder is suspended directly from the inclined sides of a bunker the fixing brackets must be set out sufficiently to allow adequate adjustment to be made to the suspension rod lengths should it be found necessary to alter the angle of installation of the feeder.
Each suspension rod is held bymeans of two nuts which should be located and securely locked together, on TOP of the supporting bracket or structure.
MINIMUM LONGITUDINAL AND LATERAL CLEARANCES :-
As some swinging movement of the feeder may take place under the influence of the load, particularly if this is intermittent, sufficient clearance must be provided to prevent the feeder from striking the chutes or adjcent steel work. Minimum longitudinal clearance should be ‘2’and the lateral clearance should be ‘1’approx.
FLOOR MOUNTED TYPE FEEDERS
A concrete base is recommended wherever possible but if the feeder is to be mounted on a steel structure it is essential that the members carrying the feeder are sufficiently substantial and rigid to prevent bending or whipping occurring under the effect of vibration.
Floor mounting plates with locating rings attatched are supplied for bolting down the concrete base or supporting structure to locate the rubber or coil spring absorbing feet.
Clearances between chute work ,bunker outlet or skirt plated and trough of a floor mounted feeder should be approximately ‘1’ this is also applied to liner fixing bolts.
BUNKER DESIGN;-
The design of bunker out lets discharging into vibrating feeders and conveyers should incorporate the following points for maximum operational efficiency:
1. The bunker outlet should be arranged so that ,as far as possible ,none of the bunker load has to be directly supported by the feeder trough. This can be achieved by careful design of the back plate of the bunker outlet,which should extend to about a value of ‘1’of the trough bottom.
The amplitude of vibration is controlled by varying the power input to the vibrator coils by means of a thyristorised electronic controller or a rheostat or a variable transformer suitable for 415 volts, single phase 50 cycle supply.
STORAGE AND HANDLING INSTRUCTIONS:-
STORAGE:-
1. Store the machine under the cover of roof if possible or otherwise it should be necessarily coverd by tarpaulins.
2. The springs must not be taken out or loosened and the trough should not be seperated from the casting while storing or installing the equipment. However,if it is unavoidable please contact TATA-ROBINS-FRASER LTD,jamshadpur -831007.
3. Take extra care to avoid the possibility of water entering the coil & making it damp.
4. The suspension rods should be carefully stored to avoid the possibility of bending and threads being spoiled.
5. Other accessories like electronic controller or rectifier,rheostat etc.. should be kept with extreme care under the cover of roof and extra care should be taken to avoid the possibility of water entering and making the equipment damp.
6. Do not remove or loosen any bolt.
HANDLING :-
1. Avoid dragging,bumping and side jacking to prevent distortion.
2. Do not sling around springs and around the trough.
3. Do not open out or cut off any part of the feeder. The suspension rods can be opened if it is necessary.
4. Extra precautions should be taken not to disturb the position of the springs while handling or installing.
5. All the spare parts should be stored in a dry and clean area protected from the weather.
INSTALLATION
GENERAL:-
Feeders and feeder grizzlies can usually be erected in position without any dismantling of the machines being required.
If however,sight conditions make it necessery for the trough to be removed from the vibrator bracket to facilitate erection ,care should be taken to ensure that on reassembly all bolts fixing the trough to the vibrator bracket are thoroughly tightened.high strength friction grip bolts,when fitted,should be tightened in accordance with the torque values as givcen under “MAINTENANCE”.
All bolts should be further checked for tightness after a week’s operation.
If further dismantling is found to be necessary, e.g,removal of the vibrator bracket from the vibrator assembly,the advice of TRF should be obtained.
ANGLE OF INSTALLATION :-
For free –flowing materials the normal angle of installation of the feeder trough is 10 deg downhill, unless otherwise agreed or advised by TRF.
For sticky materials provision should be made to enable the angle to be increased to at least 15 deg in order to facilitate the flow of material.
SUSPENDED TYPE FEEDERS :-
Suspension rods should always be attached to a main structure.
Suspension from long un supported spans of structural steel work should be avoided as loss of effective vibration in the machine will occure if the structure is insufficiently rigid and likely to flex.
Suspension rods should be supported by a plate or bracket not less than ¾ ‘thick mounted at 90 deg to the line of the rods.
All rods should be well clear of local obstructions to allow the feeder to swing freely under working conditions. This is particularly important when rods have to pass through a concretefloor, or between parts of deep section channels.
The inclination of suspension rods will depend on the position of the support points, but they must be symmetrically inclined when viewed from the end of the feeder and vertical when viewed from the side. By splaying out the rods symmetrically excessive side movement of the feeder can be prevanted.
Each pair of rods should be evenly loaded. The loading on any rod can be adjusted by slightly lengthening or shortening the effective rod length by means of the fixing nuts or turnbuckle, if fitted.
When a feeder is suspended directly from the inclined sides of a bunker the fixing brackets must be set out sufficiently to allow adequate adjustment to be made to the suspension rod lengths should it be found necessary to alter the angle of installation of the feeder.
Each suspension rod is held bymeans of two nuts which should be located and securely locked together, on TOP of the supporting bracket or structure.
MINIMUM LONGITUDINAL AND LATERAL CLEARANCES :-
As some swinging movement of the feeder may take place under the influence of the load, particularly if this is intermittent, sufficient clearance must be provided to prevent the feeder from striking the chutes or adjcent steel work. Minimum longitudinal clearance should be ‘2’and the lateral clearance should be ‘1’approx.
FLOOR MOUNTED TYPE FEEDERS
A concrete base is recommended wherever possible but if the feeder is to be mounted on a steel structure it is essential that the members carrying the feeder are sufficiently substantial and rigid to prevent bending or whipping occurring under the effect of vibration.
Floor mounting plates with locating rings attatched are supplied for bolting down the concrete base or supporting structure to locate the rubber or coil spring absorbing feet.
Clearances between chute work ,bunker outlet or skirt plated and trough of a floor mounted feeder should be approximately ‘1’ this is also applied to liner fixing bolts.
BUNKER DESIGN;-
The design of bunker out lets discharging into vibrating feeders and conveyers should incorporate the following points for maximum operational efficiency:
1. The bunker outlet should be arranged so that ,as far as possible ,none of the bunker load has to be directly supported by the feeder trough. This can be achieved by careful design of the back plate of the bunker outlet,which should extend to about a value of ‘1’of the trough bottom.
2. Unless this done, the damping effect of the bunker load on the feeder vibration will seriously affect the feeder output.
3. Unless the depth of bed of material on the trough is adequate it is unlikely that the feeder will be able to give the required feed rate.
4. The vertical dimension of the bunker throat opening therefore must be sufficiently large to allow the correct depth of bed to be carried by the feeder. As the material tends to fall away from the top of the throat opening at the angle of rest this dimension will have to be somewhat larger than the depth of bed.
5. The correct depth of bed for the required feed rate is measured towards the discharge end of the feeder at point just before the material beings to fall away. This is usually advised at the time of quoting by TRF who will also be pleased to advise on the design of bunker openings.
6. It should also be noted that the size of throat opening may be governed the size of the maximum lump being handled.
7. A cut-off gate fitted to the bunker outlet is desirable.This will enable (a) the depth of bed to be adjusted and (b) the flow of material from the bunker to be stopped to facilitate feeder tuning and maintenance.
8. Skirt plates forming part of the bunker outlet and extending over the length of the feeder will usually have to be provided in order to contain the required depth of bed of material.The bottom edge of each skirt plate should be tapered relative to the feeder trough, and not parallel to it, so that the gap between the skit plate end the trough progressively increases towards the discharge end if the feeder.The prevents materials from getting trapped between the bottom of the skirt plate and the trough which, if it occurs, can affect feeder performance.The clearance should be sufficient to allow for the possibility of having to flatten the angle of the feeder an still to maintain the self –relieving action.
9.The bunker outlet should extend across the width of the feeder to the recommended clearance of 1” from the sides of the through.
FEEDER CONTROL
ELECTRONIC CONTROLLER:-
Presently TRF Electromagnetic Feeders are fitted with ELECTRONIC CONTROLLERS housed in a sheet steel enclosure, which is suitable for wall mounting and is off dust proof construction. The unit consists of a rotary ON/OFF switch , protective fuses, potentiometer, thyristor, indicating meters and lamps, flush mounted on the front door. The other components are mounted inside the enclosure suitably designed to allow for air circulation to enable the generated heat to be dissipated away. Unless otherwise specified, the controller is suitable for operating on 415 volts , single phase 50 c/s. AC supply system and the DC output can be varied from ‘0’ TO 100% of the rated value.
Power input for electromagnetic feeder is controlled by varying the input voltage or current. Each thyristor combines the functions of rectifying the AC supply and controlling power output. Thyristor is a current controlled silicon rectified.
With an AC voltage between the anode and cathode of a thyristor which is in triggered state, current will flow during each positive half cycle, the output being a series of uni-directional power impulses which are fed to the coil of the electromagnetic feeder.
Triggering impulses are produced by a simple DC voltage. The level of this control voltage determines the point in each positive half cycle at which the conduction is initiated. If a thyristor is triggered at the beginning of each positive half cycle, maximum power is available. As the triggring point is moved towards the end of half cycle by varying the DC control voltage the power available is progressively reduced.
Hence, the amplitude of the vibration of the electromagnetic vibrator can be closely controlled simply by adjusting the control voltage.
LOCATION OF CONTROLLER:-
Wherever possible the controller is located adjacent to the feeder as this allows the operator to observe the effect of adjustment on the feeder discharge rate and also will facilitate maintenance and tuning adjustments.
Where site requirements dictate the positioning of the control equipment at a central point, adjustment of feeder discharge rate, local to the feeder may be done by the provision of a remote control station. In common with other electrical, apparatus the controller must be protected from damp and in out door locations
THE FOLLOWING STEPS ARE RECOMMENDED TO BE FOLLOWED FOR INSTALLATION OF THE CONTROLLER UNITS:-
(a) After termination and glanding of the supply cable ensure that the glanding is proper so that no clearance exists between the cable and gland.
(b) Connect the outgoing cable also and ensure proper glanding as mentioned above.
(c) Connect the outgoing cable from the controller unit to the feeder coil wires.(d) Ensure that allinstallations are carried out as per statutory regulations.
Having completed installation the following steps may be taken for commissioning:
1. Select the potentiometer for the ‘Low’ position.2. The controller is now ready for being switched on.3. The main switch may be now be brought to the ON position and the following should be
checked:(a) Glowing of indicating lamp.(b) Reading of Ampere meter (This should be ‘O’ corresponding to the minimum setting
of the potentiometer).4. Now increase the potentiometer gradually and observe the deflection in the ampere meter,
which should go on increasing steadily.5. Now try to change the potentiometer settings a few times bringing it from high to low
position alternately.It will be noted that the vibrations will also fluctuate in the same manner.
6. In case the above variations in the vibrations are consistent with the variation of controller knob, than set the potentiometer at the desired level for required output.
CONVENTIONAL CONTROLLER ARRAMENGEMENT WITH RECTIFIER AND RHEOSTAT:-
WIRING:-
The wiring diagram shows the basic series circuit consisting Rheostat and Rectifier. One wire from the switch fuse goes via Rheostat to one of the Vibrator coil (s) leads, and the other wire from the switch fuse directly to the other Vibrator coil (s) leads.
RECTIFIER:
The rectifier must be mounted with the cooling fins vertical to ensure adequate ventilation.
In common with other electrical apparatus the rectifier must be protected from damp and in outdoor situations should be protected from the weather by a suitable shroud or weather – proof cubicle
A free passage of air round the rectifier is essential and it should not therefore be mounted in a cupboard or other enclosed place.
For wall mounting type of rectifiers, spacers are provided to enable the case to be fixed clear of the wall to ensure a free all-round passage of air.
The rectifier must not be mounted directly above the Rheostat, or other source of heat.
RHEOSTAT:-
The Rheostat is included in the circuit for the purpose of increasing or decreasing the amplitude of vibration and hence the feed rate.
It should be located, if possible, near the feeder to enable the operator to observe the effect of Rheostat adjustment on the feed-rate, and also to facilitate the tuning procedure.
FLAP OPERATED SWITCH:-
The takes the form of a of load operated flap switch witch is mounted upon the face of the bunker outlet and which has a snap lock switch connected into the controller or supply line to the feeder.This enables a feeder to be stopped automatically, started or run at a fixed reduced discharge rate according to the depth of material present in the feeder trough.
Typical applications of this switch are:-
To disconnect the feeder or to run it at reduced amplitude when the bunker becomes empty.This will prevent damage which may occur if the feeder is allowed to run for a long period at high amplitude without load.
To maintain a bed of material in feeder so that uncontrolled flushing of material over the feeder is prevented when the refilling of an empty bunker is started. This is particularly necessary for a ground hopper feeder in a Wagon –tippler installation.
CLEARANCE:-
Adequate clearance must be provided about the feeder so that all parts are accessible. This is Particularly important at the back of the feeder where the clearance should be sufficient to allow the spring bolts to be removed.
OPERATION:-
Variation to the discharge rate of a feeder must be achieved by use of the control unit provide. When a gate is fitted to the bunker this should be opened sufficiently for the feeder to draw the requisite depth of bed of material for the output. Under no circumstances should the feeder be run at maximum amplitude and the discharge rate adjusted by opening or closing the gate.
APPLICATIONS OF VIBRO FEEDER:-
1. This vibro feeders are being used in LD converters for required amount of materials used are coke, dolomite, lime stone, dolo chips, iron ore etc.
2. Vibro feeders also being used in calcining plants for the chemical requirements in plant acquisitions.
3. in general we see these in filling of urea bags certain amount of weight is filled it completes closing same in case of rice bags that we generally use in our daily life.
4. SINTER PLANT and RMHP are department which are in use of these vibro feeders.
ADVANTAGES:-
1. Vibro feeders are meant to be in the automatic system process to fulfill the requirement of the needed for large machines.
2. These are having machine made systems manual usage will be difficult as well as risky so more machines are used in this vibro feeder in steel plant.
3. More time is being saved because machines are replaced by man and operations which are done in larger system is made easy.
DISADVANTAGES:-
1.Protection is less and if damage occurs we have to check for this problem in all entire machines.
2.More health problems are occurred at these working places. This is the main disadvantage.