BRO TECHNICAL: GMI

DIRECTOR GENERAL BORDER ROADS

GENERAL MAINTENANCE INSTRUCTION NO: 237

ON OPERATION AND MAINTENANCE OF

30/45 TPH ASPHALT DRUM MIX PLANT (SPEEDCRAFTS)

1. INTRODUCTION

1.1 National highways and Airfields are being constructed by using bitumen bound material of desired composition in determined thickness. To have a good quality, speed and better riding surface, Asphalt drum mix plant of higher capacity has been introduced in the BRO. Regular servicing and preventive maintenance are essential to prolong the life of the plant and also reduce the maintenance, ensure timely repairs to arrest defects from developing into major one, to operate plant efficiently at all time, to maintain breakdown and tome loss.

1.2 These instructions are issued as guidelines for operation, general and schedule maintenance, lubrications and safety precautions. All information and instructions are given in the GMI is according to the latest operations and maintenance manual of the plant.

2. AIM

(a) To enumerate the details and preventive maintenance of 30/45 TPH Asphalt Drum mix plant (Speed Craft).

3. ACTION BY

a)	USER UNIT. To carry out periodic inspection, regular servicing and preventive maintenance tasks as laid down.
b)	FIELD WORKSHOP (GREF)
	i)	To carry out and monitor, maintenance schedule and periodic oil changes as per periodicity laid down by the manufacturer.
	ii)	To advice user units in respect of any discrepancy/short coming noticed.
c)	MOBILE MAINTENANCE TEAM: To ensure lubrication and maintenance are carried out timely and accordingly appraise OC filed workshop for necessary action, if required.

4. DETAILS

The details of operations and maintenance of the plant are as under:-

a)	General and safety rules.
b)	Plant introduction.
c)	Major fitments of Asphalt Drum Mix Plant.
d)	Installation and care.
e)	Control system.
f)	Empty run test and plant operation.
g)	Starting up and shut down procedure of the plant.
h)	Calibration of belt feeder.
j)	Maintenance and adjustment.
k)	Lubrication chart and lubricant quantity.

5. Please acknowledge receipt.

(Hari Prakash)

SE (E&M) FS

Director (Tech)

For Dir Gen Border Roads

1. GENERAL

This General Maintenance Instruction is required to pay attention and followed by the operator and supervisor for ensuring efficient and trouble free operation of the plant.

This instruction is required to be carefully preserved for all the times so that, whenever become necessary, it can be referred for operational pre-requisites and recommended maintenance instructions and schedule.

SAFETY RULES

Most accidents are caused by someone due to failure of following simple and fundamental safety rules or precautions.

Regardless of the care used in the design and construction of the machinery, there are many points that can not be completely safe guarded.

A careful operator is the best insurance against an accident.

THE COMPLETE OBSERVANCE OF ONE SIMPLE RULE WOULD PREVENT MANY SERIOUS ACCIDENTS.

THE RULE IS

“NEVER ATTEMPT TO CLEAN OIL, OR ADJUST ANY MACHINE PART WHILE IT IS IN MOTION”

2. PLANT INTROUDCTION

2.1 Now-a-days road and highways network is most essential for a modern industrialized country because a natural earth track can neither support modern wheel loads nor provide an adequate riding surface. It has now become a standard practice to use bitumen bound material in the construction of heavy duty streets, roads and air ports etc.

2.2 Asphalt Drum Mix Plant: In Asphalt Drum Mix Plant both aggregate and the bitumen are heated and then alongwith filler material they are mixed thoroughly in the mixed drum to prepare hot bitumen mix for the base and surfaces courses, The main function of the Drum Mix Plant are:-

2.2.1. Proportioning of different size of aggregates as per mix design.

2.2.2. Heating & drying the aggregate.

2.2.3. Heating the bitumen.

2.2.4. Mixing the proportioned aggregates, bitumen and filler material to produce a homogenous mix.

3. MAJOR FITMENS OF ASPHALLT DRUM MIX PLANT

3.1.4. Bins Feeder:- It is built on a single chassis consisting of four individual bins. At bottom of each bin hand operated radial gate is provided to regulate the aggregate flow. Individual belt feeder controlled by AC motor is provided below each gate to discharge the aggregate on to the gathering conveyor.

3.2. Gathering Conveyor:- A Gathering Celt Conveyor is provided along centre line of the chassis of 4-bin to receive aggregate discharged from each bin feeder.

3.3. Vibratory Screen:- Below discharging end of the gathering conveyor, a vibratory screen is provided at receiving end of the slinger conveyor to separate oversize aggregate. A vibratory motor is installed on body of the vibratory screen to give vibrating motion to screen as and when required.

3.4. Slinger Conveyor:-An inclined slinger belt conveyor is provided to receive screened aggregates and feed the same to the dryer mixer.

3.5. Dryer Mixer:-It is fabricated to ensure proper heating and mixing of aggregate and filler material with molten bitumen. The dryer drum is fitted with two steel tires (tie ring) on its outer periphery and the tie rings are freely mounted over set of turnion rollers. Since the dryer is mounted slightly inclined keeping the receiving end of the dryer higher than its discharge end, the internal movement of the dryer drum between tie ring and turnion rollers are encountered by a set of vertical guide rollers. The rotational movement to drum is given by chain and sprocket drive.

The dryer burner and its air blower is installed and fitted to receiving end of the drum. Fuel to burner is supplied by a fuel pump.

A series of rows containing steel blades of different shapes are mounted over inner periphery of the drum throughout its length. The function of the blade is to collect the aggregate from bottom of the drum and to lift it up to top and allows the aggregate to fall through hot flame as well as hot gases. The other function of the blade is to carry the aggregate from receiving end of the drum to discharge end.

From receiving end, two-third length of the dryer is heating zone and balance one-third length is mixing zone. In the heating zone, aggregates get dry and heated and in the mixing zone the aggregate gets mixed with molten bitumen and filler material.

The molten bitumen and filler material are fed through separate piping at junction of the heating and mixing zone of drum.

The final mix gets discharged by discharge mouth of the dryer on to the load out conveyor.

3.6. LDO (fuel) pump Station:-It consists of LDO pump and LDO tank. LDO tank acts as a storage tank of fuel to be supplied to drier burner as well as Asphalt burner. The Asphalt burner is inbuilt with its own fuel pump and hence no separate fuel pump is required to feed the fuel to Asphalt burner.

A LDO (Fuel) pump station consisting of fuel pump coupled with driving motor mounted on a single base is provided to supply the fuel to dryer burner.

3.7. Mineral filler Unit:-A Mineral filler Unit fitted with air blower and air rotary valve is utilized to supply required mineral filler material directly into the dryer mixer through a separate piping. The mineral filler material is kept in the hopper of the filler unit and the flow of the same is controlled by rotary valve and AC motor.

3.8. Asphalt Tank:-A fully insulated Asphalt (Bitumen) tank of adequate capacity is provided for storage as well as heating of the bitumen. The tank is inbuilt with internal fire tube with top exhaust for heating the contents. An oil fired burner is fitted to the inlet mouth of the fire tube at the base of the tank to produce heat. The facility of internal circulation of molten bitumen to tank is also provided for homogenous mixing and fast heating of the bitumen inside the tank.

3.9. Asphalt Pump Station:-An Asphalt Pump station equipped with AC motor, reduction gear box and jacketed Asphalt pump mounted on a single base is fitted to outlet of the Asphalt tank. The pump draws the molten bitumen from the tank and feed the same to mixing end of the dryer mixer through separate piping. The feed of molten bitumen to dryer is controlled by AC motor.

3.10. Load Out Conveyor:-Final mix from the dryer mixer is discharged on to the inclined load out conveyer. The function of load out conveyor is to carry the final mix up to top of the conveyor and to discharge the same either into the silo are directly into tipper truck through discharge hopper.

3.11 Storage Silo (Optional):-A Storage Silo of adequate capacity is installed for receiving final mix material and to discharge the same into the tipper through discharge hopper as and when required. In this case hopper is fitted to bottom opening of the silo. The opening and closing of the gate of the hopper is hydraulically operated. The silo is mounted on four pillars at sufficient height ensuring free passage of tipper truck below discharge hopper of the silo.

When silo is not opted then the discharge hopper is fitted to discharge end of the load out conveyor.

3.12 Multi cyclone Unit:-A multi cyclone unit is fitted in between dryer and exhauster unit through inlet and outlet tubes. The hot fume of dryer along with aggregate dust sucked by the exhauster unit is routed through the multi cyclone unit. The function of the multi cyclone is to trap the heavy aggregate dust particles which is collected at bottom of the unit and get discharged automatically time to time.

A Flap type gate along horizontal plane is fitted at bottom opening of the multi cyclone unit, which is hinged at one side with counter weight device. The function of counterweight is to keep the flap gate always in closed position. The dust particles get accumulated on surface of the flap and as soon as weight of the accumulated dust increases then counter weight value, the flap gets open in downward direction and accumulated dust particles get discharged just below the gate and after discharge the flap gate comes back in its original position due to counter weight device.

3.13 Exhauster Unit:-The Exhauster unit is connected to outlet tube of the multi cyclone. The function of exhauster unit is to suck the hot fumes along with fine aggregate dust particle and discharge the same either directly to atmosphere through exhauster chimney (when air pollution control unit is not opted) or to top inlet of venture of the air pollution control unit.

3.14 Air Pollution Control Unit (Optional):-This unit mainly consists of venture, vertical water tank of cylindrical shape and a water pump station. The exhauster out let is connected to the top inlet of the venture. The bottom outlet of the venture is connected to the bottom inlet of the vertical water tank. The final dust free exhaust is discharged through top of the water tank through chimney.

A shower unit is fitted at top of the venture for spraying the water. The hot exhaust coming out from the venture passes through spray of water by which the suspended dust particle along with other impurities get wet and collected at bottom of the water tank as sediments. The wet sediments settled at bottom of the water tank are removed time to time through man hole provided to side of the tank.

A water pump station is installed to supply water through separate piping.

3.15 Water pumps station:-A water pump station with adequate capacity of ground RCC water tank is installed near by the air pollution control unit. The ground tank consists of three inter connected taper sections as 1, 2 and 3. The water pump is installed at lower taper section to lift the water to the top of the venture. Water sprayed to the venture is collected at the bottom of the vertical water tank which is routed back to the higher taper section of the ground tank. The system works as a close circuit of water circulation. The makeup water which gets vaporized is fed to the tank through other source of water as and when required.

3.16 Control Cabin:-A fully automatic electronic control panel is installed in a air conditioned cabin for controlling the quantity and quality of the final mix in pre-required proportion in operator sitting inside the cabin. Adequate safety measures are adopted to avoid short circuit.

4. INSTALLATION AND CARE

4.1. Construct the concrete foundation as per lay-out foundation drawing supplied by the manufacturer.

4.2. With the help of carne, place the heavy fitments such as 4-bin, dryer, multi cyclone, asphalt tank, LDO tank, exhauster, mineral filter etc at their respective locations.

4.3. Complete the installation of above heavy fitments as per layout.

4.4. Complete the piping work for fuel, bitumen, water and mineral filler.

4.5. Complete the electric wiring for all the electric motors and controls with control panel.

4.6. Refer electric wiring diagram for selection of proper size of electric cables and their routing for different capacities of motors and controls. Care should be taken during installation

4.7. Ensure that conveyor structure is perfectly straight and leveled.

4.8. Ensure that set of v-belt driving and driven pulleys are properly mounted over shafts with keys and face of the pulleys are perfectly aligned.

4.9. Ensure that all types of conveyor rollers are correctly mounted with their axis perpendicular to the centre line of the conveyor and all rollers are rotating freely.

4.10. Ensure that there is a equal initial belt tension on both top and bottom of the conveyor belt.

4.11. Ensure that all gear boxes are fitted with recommended grade of gear oil up to correct level and all bearing, chain & sprockets and other lubricating points are greased and lubricated.

4.12. Ensure that foundation bolt of all motors, gear boxes and other major fitments are full tight.

4.13. Ensure that all the electric motors and hydraulic power pack are covered against protection of rain.

4.14. Ensure that holding bolts of all the self aligned bearings are properly tight.

4.15. Ensure that correct belt tension to all v-belt drive.

4.16. Ensure proper earthing of the entire plant including control cabin to avoid to any electric shock.

4.17. Ensure that all electric cables routing from the control cabin to different electric controls are underground. Also ensure that the eclectic cables above the ground connecting different electric motors and controls should not hang lose and routed properly tied with plastic tie band.

5. CONTROL SYSTEM

A centralized control system is designed to make the operation of the plant easy and compact. A microprocessor based electronic control panel is installed inside a air conditioned controlled cabin. All electric loads (electric motor and temperature sensors) installed at various location of the plant are connected to the control panel through underground electric cable so that single operator sitting inside the cabin can control operation of entire plant.

Transparent glass of the cabin ensures clear view of the entire plant during operation. Configuration of the control panel depends upon specific design based on various equipments to be connected. However in general following are the common loads to be connected to the panel for which push button type individual control switch are provided on the panel.

1. Main power

2. Exhauster

3. Dryer drum

4. Hot conveyor

5. Cold conveyor

6. Gathering conveyer

7. Dryer burner

8. Dryer LDO Pump

9. Dryer Solenoid valve

10. Dryer burner ignition

11. Dryer blower

12. Asphalt burner

13. Hot oil pump

14. Hydraulic power pack

15. Hopper open close

16. Load Cell

17. Water Pump

18. Vibratory screen

19. Filler Blower

20. Filler valve

21. Bin Fedder-1

22. Bin Feeder-2

23. Bin Feeder-3

24. Bin Feeder-4

25. Bin vibrator

26. Asphalt %

27. Bin Fedder-1

28. Bin Feeder-2

29. Bin Feeder-3

30. Bin Feeder-4

31. Filler material %

32. Asphalt pump forward-reverse

33. Asphalt blower(change over switch)

34. Totalized

6. EMPTY RUN TEST AND PLANT OPERATION

6.1 Empty Run Test

6.1.1 After completing entire installation work and electric cabling of the plant, the correctness of fitments and rotation of each motor should be checked before commissioning of the plant.

6.1.2. Lubricate and fill with recommended oil and lubricants as applicable to different fitments in accordance with lubrication chart.

6.1.3. Ensure electric supply from generator to control panel placed inside the cabin.

6.1.4. Lift up the main supply toggle switch to ‘ON’ position provided at outer wall at right side of the control panel.

6.1.5. Lift up all MCB switch to ‘ON’ position by opening front and back cover of the control panel. Refit the covers.

6.1.6. Ensure that push type emergency switch provided at the top of the panel is in released position.

Note

Now start the each motor in following sequence and if found correct, switch off this particular motor before starting second motor.

ii)

Rotation of any 3-phase motor can be corrected (in case running in wrong direction) by interchanging the cable position either at motor terminal or at control panel terminal.

6.2 Exhauster

6.2.1. Push the “on” button of “main power” provided at left top of feather touch controls. After pushing this button all the red indicators will glow at top of the panel.

6.2.2. Start the exhauster by pushing its respective “on” button on control panel.

6.2.3. Check the correct rotation of the exhauster.

6.2.4. Check that V-belt running smoothly. Adjust the belt tension if needed.

6.3. Dryer Drum:

6.3.1 Start the Dryer Drum by pushing its respective “on” button on control panel.

6.3.2. Check that rotation of Dryer Drum is correct.

6.3.3. Check that tension in chain running over dryer drum is correct. Adjusted if needed.

6.3.4. Check that entire width of both the dryer tie rings running perfectly over trunion rollers.

6.3.5. Check that first 2 guide rollers from rotor side running freely in contract with side face of the tie ring.

6.3.6. Check that upper edge of the guide roller is 5 mm below than inner edge of the tie ring at contact point.

6.3.7. Check that there is an initial gap of 4 to 5 mm in between first guide roller form burner side and tie ring face to take care of expansion of dryer drum due to heat.

6.4 Dryer Burner.

6.4.1 Light the Dryer Burner following sequence as explained in para 7.3.4.

6.5. Slinger/Cold Conveyor.

6.5.1 Start the cold conveyor by pushing its respective “on” button on control panel.

6.5.2. Check that conveyor belt running over its idlers centrally. If running out, adjust the same as explained in para 9.2.

6.5.3. Check that belt tension is correct. Adjust if required with the help of tensioners.

6.5.4. Check that belt is running in correct direction.

6.6. Gathering conveyor:

6.6.1. Start the gathering conveyor by pushing its respective “on” button on control panel.

6.6.2 Check that conveyor belt running over its idlers centrally. If running out, adjust the same as explained in para 9.2.

6.6.3. Check that belt tension is correct. Adjust if required with the help of tensioners.

6.6.4. Check that belt is running in correct direction.

6.7. Bin Feeders (4 Nos):

6.7.1. Start each Bin feeder one by one by pushing there respective “on” button on control panel and check their speed by using their respective percentage regulator knob.

6.7.2. Check that conveyor belt running over its idlers centrally. If running out, adjust the same as explained in para 9.2.

6.7.3. Check that belt tension is correct. Adjust if required with the help of tensioners.

6.7.4. Check that belt is running in correct direction.

6.8. Hot conveyor:

6.8.1. Start the conveyor by pushing its respective ‘ON’ button on control panel.

6.8.2. Check that conveyor belt running over its idlers centrally. If running out, adjust the same as explained in para 9.2.

6.8.3. Check that belt tension is correct. Adjust if required with the help of tensioners.

6.8.4. Check that belt is running in correct direction.

6.9. Open – Close of Discharge Hopper:

6.9.1. Start the hydraulic power pack by pushing its respective “on” button on control panel.

6.9.2. Push the open-close push button simultaneously and check the opening and closing action of the hopper gate. In case it is found opposite ie on pushing “open” button, hopper gate closes then interchange the position of hydraulic pipe ends either at hydraulic power pack or at hydraulic cylinder port.

6.10. Asphalt Pump Station:

6.10.1. Start the Asphalt Pump by pushing its respective “on” button on control panel.

6.10.2. Check that pump is running in correct direction ie it is running in forward direction in “forward mode” and in reverse direction in “reverse mode” if found opposite, interchange the cable position either at motor terminal or at control panel terminal.

6.11. Mineral filer:

6.11.1. Start the Air Blower and rotary valve by pushing its respective “on” button on control panel.

6.11.2. Check that both Air Blower and air rotary valve is running in correct direction.

6.12. Plant operation :

6.12.1. Before start, check the oil level of gear boxes up to the correct level and all bearings, chain and sparest, gear and pinion of dryer shaft are lubricated properly.

6.12.2. Start the exhaust to ensure that complete exhaust system is thoroughly working. Never start any other operation if exhaust system is malfunctioning.

6.12.3. Start the bin feeder conveyers, gathering conveyor, slinger conveyor and load out conveyor simultaneously and check that all the conveyors are running centrally and straight over driving and trailing rollers. IN case of non central running of any of the belt, adjust the same.

6.12.4. After confirming no load operation, feed the pre proportioned material on gathering conveyor through bin feeders. Adjust opening of feeder gate and feeder speed for pre required quantity of material through each bin. The operating and closing of the feeder gate can be regulated by rotating the hand wheel in clock or anti-clock wise direction fitted to the radial gate of the feeder. The speed of the feeder belt can be increased or decreased by regulating the speed of the AC motors provided individually for each bin feeder.

6.12.5. The material collected on gathering conveyor through each of the bin feeder is feed on to the slinger conveyor through vibratory screen. The oversize material gets separated over the screen which falls down at one side of the screen through side opening of the screen. Vibratory motion to the screen is given as and when required. It is advised that a man should stand near the screen to pick up the over sized aggregate off the screen to ensure that the opening of the screen should not get blocked.

6.12.6. The aggregate falling on receiving end of the slinger conveyor is fed directly to the dryer mixer. Simultaneously molten bitumen is fed through other end of the dryer by separate piping. The mineral filer material is also fed into the dryer as per requirement. All the materials fed into the dryer get mixed with bitumen and the final mix is discharged through the discharge gate of the dryer. The final mix material from the dryer is discharged on to the receiving end of the load out conveyor which in turn, carries the same and discharges either in to the storage silo or directly into the tipper through discharge hopper.

6.12.7. Quantity of material feed should be controlled. If the material is fed in excess, the conveyor motors will get overloaded and material on the belt will also apt to spill.

6.12.8 In addition to the control of material fed, the belt tension should be maintained properly to transmit the load.

6.12.9 The operator in the cabin should keep is eyes on motors Ampere meter regularly as this will give an indication of any over loading and assistance in tracing faults of the system.

6.12.10. Before stopping the plant, it should be ensured that there is no material left on any of the conveyor belts as well as in the dryer mixer.

6.12.11. The dryer drum with dryer burner’s air blower should run at least for half an hour for cooling of the dryer. The exhauster, slinger belt and or conveyor should also keep running idle during this period.

6.12.12. For efficient operation and maximum life of the plant, operating condition and operating area should be kept as clean as possible. Any spillage of material should be cleaned regularly. Discharge offer and conveyor belt should be inspected regularly and any build up of material which is accumulating should be removed to minimize any blockage.

6.12.13. Immediate attention should be given in case of any item of the plant require repair/ replacement to avoid the possibility of a chain reaction of damage. If needed, expert advice should be taken.

7. STARTING UP AND SHUT DOWN PROCEDURE OF THE PLANT

7.1. Plant Starting Procedure

7.1.1. Ensure eclectic supply from generator to control panel installed inside the control cabin.

7.1.2 Lift up the main supply toggle switch to “on” position provided at outer wall at right side of the control panel.

7.1.3. Ensure that push type emergency switch provided at top of the panel is in released position is in “on” position.

Note: When emergency switch will be in “pushed down” position, nor any other switch will work.

7.1.4. Open front and back vertical cover of the control panel and lift up all the MCB switch to “on” position except the MCB switch provided for exhaust blower, ie, keep the exhaust blower MCB switch remain in “off” position ie in down position.

7.1.5. Fit the front and back vertical covers back to its position.

7.2 Heating the Bitumen inside Asphalt Tank :

7.2.1. A change over switch is provided at top of the panel marked 1-0-2. Mark ‘1’ is related to asphalt burner of asphalt tank No 1, ‘0’ indicates neutral position and mark ‘2’ is related to asphalt burner of asphalt tank No 2. In case only one asphalt tank is applicable then put the changeover switch to mark ‘l’ position, This will ensure the electric connection with asphalt burner fitted to asphalt tank No.1

7.2.2. A push type “on-off” feather touch control buttons are provided for each electric load at top centre of the control panel. Push the “on” button of “main power” provided at left top of feather touch controls. After pushing the button all the red indicators will glow at top of the panel.

7.2.3. Push the “on” button of exhauster provided just below the “main power” button and wait for 8 to 10 seconds to hear a “kit” sound i.e to come the exhauster MCB switch from star to delta position.

Note: Ensure that MCB switch of exhauster should be in “off” position as explained in para 7.1.4

7.2.4. Now open the ball valves provided at outlet of the LDO tank as well as below the Asphalt burner provided in fuel line and ensure that fuel supply from LDO tank to burner is clear.

IMPORTANT- There should be enough bitumen inside the Asphalt tank i.e. at least the fire tube to which the burner is fitted must be covered with bitumen. Otherwise the outer surface of the fire tube inside the tank will become red-hot and there will be chance of fire catching inside the tank.

Layer of bitumen above top surface of the fire tube should not be less than 4” (100 mm) at the time of lighting the burner.

7.2.5. Two outlets for molten bitumen are provided in same vertical line to which 2-way type open-close valves are fitted.

Note: Before firing (lighting) the burner, ensure that these 2 valves are in closed position.

7.2.6. To light the burner, push the “on” button of “Asphalt blower-1” of feather touch control at top of the panel.

By pushing this bottom, burner will get lighted. For smooth burning: fuel pressure, combustion head and air supply ratio may require some minor adjustments, which can be done manually during lighting the burner.

Normal setting valves are as under:-

Combustion head

Between 4.5 to 6.5

Fuel pressure

Between 14 to 16 Kg/Cm²

Air damper

Between 3 to 5

Setting value of combustion head is calibrated and marked on combustion head rod of the burner. This can be adjusted by opening the top cover of the burner.

The fuel pressure can be read in pressure gauge fitted to burner fuel pump and it can be adjusted by tightening or releasing fuel pressure relief screw provided at side of the pressure gauge for at fuel pump body.

Air damper ie amount of air supply can be adjusted by rotating the air damper flap in clock or anti-clock wise direction which is in shape of quadrant of a circle.

7.2.7. Melting time of bitumen will depend upon the amount of bitumen as well as initial temp of the bitumen inside the tank. Required temp of molten bitumen is 150⁰C to 160⁰C. (The temp of molten bitumen can be read on control panel or by manual from temp gauge fitted on bitumen tank.)

7.2.9 Wait to reach the bitumen temp 140⁰C to 145⁰C. Now set bitumen line for circulation i.e to circulate the molten bitumen from bitumen tank to bitumen pump and back to bitumen tank. This well ensures the homogeneous temp of molten bitumen inside the tank. Required bitumen line can be set by selecting different valves positions provided in the bitumen line.

7.2.10. Bitumen pump can be run in both forward as well as in reverse direction. For this purpose a selector switch is provided at top of the panel marked FORWARD-REVERSE.

By selecting forward mode, start the bitumen pump by pushing the “on” button of “Asphalt Pump” on feather touch controls at top of the panel.

The molten bitumen will start circulating from tank to pump and back to tank.

7.2.11. Wait to raise the molten bitumen 155⁰C to 160⁰C. Once the required temp reaches, stop (off) the burner by pushing the respective “off” button on the control panel.

7.2.12. Now the molten bitumen is ready for use i.e for mixing with hot aggregates.

7.3. Heating of aggregate and mixing with bitumen and other filler material.

7.3.1 First push the ‘off” button of the exhauster and then put the exhauster MCB switch “on” position by opening the front cover of the panel and then refit the cover.

Note: Before starting the mixing operation, ensure that all the MCB switches provided Inside the panel for each electric loads are in “on” position.

7.3.2. Follow the following sequence for starting the plant.

Start exhauster

Push “on” button of exhauster on control panel.

Start dryer drum

Push “on” button dryer on control panel.

Start hot conveyor

Push “on” button of hot conveyor on control panel.

Start dryer drum

Push “on” button of exhauster on control panel.

Start singer/cold conveyor

Push “on” button of cold conveyor panel.

Start gathering conveyor

Push “on” button of gathering conveyor on control panel.

7.3.3. Select the “reverse” mode of bitumen pump selector switch and start the bitumen pump by pressing the respective “on” button. The bitumen pump will run in reverse direction i.e pump will run but it will not draw the molten bitumen from the tank.

Set the bitumen line to route the molten bitumen to dryer drum by selecting and setting the respective 2 way and 3 way valve positions.

7.3.4. For dryer burner four controls are provided as under:-

Fuel pump for dryer burner.

Air blower for dryer burner.

LDO valve Ignition.

Light the dryer burner, following sequence as under:

Start the fuel pump – Push “on” button of LDO pump on control panel. Keep the Ignition “on” button in pressed position and press the L.D.O valve ‘on” button. By doing so, flame will take place at mouth of the dryer then lift the finger and immediately start the dryer blower by pushing respective “on” button and so the burner will start burning with its full length of flame inside the dryer.

7.3.5. Press bin-1 aggregate feeder “on” button at pre-calibrated value of feeder gate opening and rotate the bin-1 percentage regulator knob to its pre-calibrated value as per required mix design. By doing so, aggregate from bin-1 will start falling from feeder conveyor on to gathering conveyor.

Similarly start bin-2, bin-3 and bin-4 feed conveyor one by one by following above operational sequence at their pre-setting of feeder gates opening.

7.3.6. The gathering conveyor carrying the aggregates discharged by all the 4 bins and in turns the same is discharged on to the cold conveyor through vibratory screen.

7.3.7. Cold conveyor receives the screened aggregates at its receiving end and feeds the same to the mouth of the dryer drum.

7.3.8. As soon as the aggregates start entering the dryer drum change the bitumen pump selector switch from REVERSE to forward position so that bitumen pump starts drawing and lifting the molten bitumen to mixing zone of dryer.

7.3.9. Start the filter blower as well as air rotary valve by pushing the corresponding “on” buttons if needed as per mix design. Slow or fast of air rotary valve regulates (controls) the quantity of filter material, which is blown to the dryer by stream of air produced by air blower. Quantity of filter material is regulated by percentage regulator knob provided for air rotary valve on control panel.

7.3.10. Set the bitumen and filter material quantity by regulating their percentage regulator knobs.

7.3.11. Final hot mix material will start coming out from discharge mouth of the dryer, which is falling directly on to the hot conveyor which in turn get discharged into the tipper truck through its gob hopper.

Note: Percentage of bitumen can be increased or decreased by observing final mix quality by regulating its percentage regulator knob.

7.3.12. The mix temp will depend on moisture content of the aggregate as well as on quantity of aggregate fended to dryer drum. For optimum mix temp (120⁰C to 130⁰C) the feed of aggregate from each bin feeder should be controlled accordingly by regulating the respective percentage regulator knobs.

7.3.13. A hydraulic power pack is provided for opening and closing the button gate of discharge hopper.

An “open” – “close” push button switch is provided for opening and closing of the hopper. Push “open” button to open the discharge gate of the hopper to discharge the hot mix material into tipper truck and push “close” button to close the hopper gate. Open close operation should be repeated at regular intervals.

7.4. Feeding of aggregate to all 4 bins:

7.4.1. It should be ensured that no any bin should get empty during operation of the plant. A loader should be regularly engaged to fill each bin with required size of aggregate as per mix design.

7.5. Plant shut down procedure:

7.5.1 Push “off” button one by one of bin-1, 2, 3 and 4 to stop discharge of aggregate from all 4-bin feeders and simultaneously bring all the 4 percentage regulator knobs to zero

7.5.2. When all the aggregate get discharged from gathering conveyor, stop the gathering conveyor by pushing respective “off” button on control panel

7.5.3. Wait to enter all the aggregate to dryer through cold conveyor and after one minute push the “off” buttons of LDO valve and LDO pump to shut off the dryer burner flame.

7.5.4 Observe the discharge of hot mix material on hot conveyor and when it is near to finish.

Stop feeding of filler material by pushing “off: button of filler blower and filler air rotary valve.

Change the position of bitumen pump change over switch from “FORWARD” to “REVERSE” position to stop feeding of molten bitumen to dryer drum.

When the bitumen pump change over switch is set to REVERSE position, the bitumen pump starts rotating in reverse direction and the molten bitumen present inside bitumen pipeline is pumped back into the bitumen tank

7.5.5. Allow to run cold conveyor, dryer blower, dryer drum, hot conveyor and exhauster for 30 minutes for cooling of dryer drum and their after shut off all the above one by one is same sequence i.e cold conveyor, dryer blower, dryer drum, hot conveyor and at last the exhauster blower.

During cooling time of dryer drum, following equipments must be cleaned at end of the day’s work.

7.6. Cleaning of Asphalt/ bitumen pump:

7.6.1. Close 2way valve to stop flow of molten bitumen from asphalt tank to asphalt pump.

7.6.2. Set the 3 way valve to flush mode for cleaning the pump and discharge the contents to outside small drum of capacity nearly 57 liters having complete open top.

7.6.3. A conical funnel in bitumen line above bitumen pump is provided for cleaning purpose. Open the ball valve, fitted just below the funnel.

7.6.4. Change the bitumen pump selector switch from REVERSE to FORWARD position.

7.6.5. Pour about 4 liters of diesel into the funnel and let it discharged to outside flush tank. Repeat cleaning of pump by pouring another 4 liters of diesel.

7.6.6. Set the position of 3 way valves to stop flow from pump side i.e it neither opened to neither flush line or to dryer drum line.

7.6.7. Switch “off” the bitumen pump by pushing respective “off” button on control panel. Bring the bitumen percentage regulator knob to zero.

7.6.8 Pour about another 4 liters of diesel through the funnel and close the ball valve fitted below the funnel and remain the diesel inside pump to avoid any chance of jamming of the pump.

Note: On next working day, before starting of bitumen pump the free rotation of the pump must be checked by rotating the AC motors and reduction gear box joint coupling by hand and discharge the diesel left inside pump to outside flush tank.

7.7. Cleaning of discharge mouth of dryer, hot conveyor and discharge hooper.

7.7.1. Before leaving the work place at end of the days work above equipment must be cleaned with special type of cleaning tools for smooth running and longer life of the equipment.

8. CALIBRATION OF BELT FEEDER

8.1. Calibration of belt feeder is to be done manually before actual operation of the plant. Calibration depends upon mix design

Example

Let mix design include 4 types of aggregate size as under :

25 mm

20%

19 mm

25%

Total 100%

12 mm

40%

5 mm

10%

Bitumen

05%

8.2. Let the plant output is to be set 90 TPH

Suppose 25mm aggregate filled in bin No-1.

19mm aggregate filled in bin No-2.

12mm aggregate filled in bin No-3.

06mm aggregate filled in bin No-4.

Discharge of aggregate from belt feeder No1 =

20 x 90 x 1000

Kg/min = 300 Kg/min.

10060

Similarly discharge from belt feeder No 2 =

25x 90 x 1000

Kg/min = 375Kg/min.

10060

Discharge from belt feeder No 3 =

40 x 90 x 1000

Kg/min = 600Kg/min.

10060

And discharge from belt feeder No 4 =

10 x 90 x 1000

Kg/min = 150 Kg/min

10060

8.3. Now chose the belt feeder whose discharge is maximum. In above case, feeder No 3 having maximum discharge among 4

Discharge from belt feeder No 3 = 600 Kg/min = 100 Kg/10 Sec.

Feeders having maximum discharge should be calibrated first:

8.4. Procedure:

Set the feeder radial fare opening (Vertical gap above feeder belt to bottom edge of radial gate) to 150 mm.

Start the belt feeder No,3 and set the percentage regulator knob 20%.

Collect the discharge for 10 sec and measure the weight. It can be either more than 100 Kg or less than 100 Kg.

Depending upon weight observed, keeping belt feeder percentage regulator knob at same value i.e at 20%, either increase the feeder gate opening in case discharge is less than 100 Kg or decrease the gate opening in case discharge is more than 100 Kg.

By repeating this hit and trial practice fix the discharge to 100 Kg/10 second. In this way the belt feeder No.3 is calibrated to required value.

8.5. Calibration of feeder No. 2

Discharge from feeder No. 2 = 375 Kg/min = 62.5 Kg/10 sec.

Start the belt feeder No.2 and set the percentage regulator knob to 20% ie at same value at which the feeder No. 3 is calibrated.

Following the above procedure, set the gate opening of feeder No. 2 to have a discharge of 62.5/10 sec. Now the feeder No. 2 is calibrated to required value.

8.6. Similarly calibrate the feeder No. 1 and 4 by setting their percentage regulator knob at same value of 20%.

8.7. To have said output of 90 TPH with above m ix design as taken in example, set the feeder gates opening to calculated values and run the all four belt feeders at same speed ie. at 20%.

9. MAINTENANCE AND ADJUSTMENT

9.1. For reliable operation and longer life of the plant, regulator maintenance and adjustment is necessary.

As general guidance to food maintenance the following points should be inspected regularly and action should be taken as necessary.

9.2. Check that the feed on the conveyor belt is central and belt is running straight. If not, establish the use of the non-central feed and adjust the belt as necessary. Belt adjustment:

For each conveyor, belt tightening/loosening screws are provided at each side of belt at one end of the conveyor.

Example:

Let belt has got shifted from central axis to right side when viewed from screw end of the belt. For central running of the belt, it should be adjusted. It can be adjusted in two ways

By tightening right end of the belt, or

By loosing left end of the belt.

In case the belt has got shifted towards right side due to slackness of the belt at right end then to shift the belt towards central axis, the right end belt to the tightened and if it has got shifted due to over tightening of the belt at left end of the belt to be loosen to make it central.

9.3. Contamination caused by spillage and accumulation on belt should be cleaned regularly. This also applies to the cleaning of machinery. Rotating parts must only be cleaned when they are at rest to avoid any accident.

9.4. Check that all conveyor rollers are running freely without producing any abnormal sound. If not, lubricate or rectify the rollers as necessary to avoid unnecessary belt wear.

9.5. Lubricate all bearing and moving parts such as chain & sprocket, gear & pinions etc. at regular service.

9.6. In case of gear boxes, check the oil level weekly, top up to correct level when found less. Drain and refill with fresh oil as recommended in lubrication chart.

9.7. If the plant is going to be stationary for a week or more without any operation then all the conveyor, silo and discharge hopper should be cleaned thoroughly.

9.8. Check the v-belt tension and their alignment regularly and adjust correctly if needed.

9.9. If any item of the plant require repair or replacement it should be repaired or rep laced without any delay to avoid the possibility of any chain reaction of damage. Also during operation, if any abnormality seen should be noted and expert advice should be taken.

9.10. Refer lubrication chart for type of lubricant and lubrication frequency.

10. LUBRICATION CHART & LUBRICANT QUANTITY

S/No

Item

Lubricant Type

Frequency

All gear box fitted to bin feeder, gathering conveyor, singer conveyor, load out conveyor and dryer mixer.

Gear Oil, 90M or equivalent

1000 hrs

Chain & sprocket and gear & pinions fitted to dryer mixer.

Wheel bearing grease

50 hrs

All bearings fitted to conveyor rollers turnion & guide roller and driving unit of dryer

Wheel bearing grease

50 hrs

Hydraulic oil of hydraulic power pack

Hydraulic oil, 68M or equivalent

500 hrs

All conveyor idler rollers and other lubricating points

Mobil oil 20W/40 or equivalent

Regularly as necessary.

LUBRICANT QUANTITY

S/No

Gear Oil

DM 45

DM 50

DM 60

4 Bin feeder gear box

0.5 Ltr

0.9Ltr

Gathering conveyor gear box

0.9 Ltr

1.5 Ltr

Cold conveyor gear ox

0.9 Ltr

Hot conveyor gear box

0.9 Ltr

Dryer drum gear box

6 Ltr

14 Ltr

Mineral filler gear box

1 Ltr

2 Ltr

Asphalt pump gear box

1 Ltr

Hydraulic Oil

Hydraulic power pack

40 Ltr

Note :

1. Use reputed make of lubricants such as Indian Oil/Bharat Petroleum/Hindustan Petroleum/ Shell or equivalent.

2. The bearings should not be over lubricated, over lubrication will heat up the bearings.

_______________

BRO TECHNICAL

Search This Blog

Monday 6 April 2020

GMI - 237

No comments:

Post a Comment