GENERAL:

For Modernization of country, smooth road is a must now a day because a natural earth track cannot bear the wheel load and cannot provide smooth riding surface, So for today it is essential to use bitumen bound material in the construction of Roads and Airports.

DRUM MIX PLANTS : 
To prepare hot asphalt mix for the base and surface coarsens, both the aggregate and the bitumen are heated and then along with filler material they are mixed thoroughly in Drum mix plant. It’s functioning consists of :

• Proportioning of the aggregates

• Heating and Drying the aggregate

• Heating the Bitumen

• Mixing and Proportioning of aggregate filler and bitumen as a homogeneous mix.

Drum Mix Plant Mainly consists of:

• Feeders (Three of Four Bin) with Gathering Conveyor.

• Slinger conveyor with weighing scale unit.

• Dryer unit with Burner, Exhauster, Multi-cone Dust collector, Screw Conveyor.

• Load out conveyor with discharge hopper.

• Lime hopper with pneumatic conveying system.

• Bitumen Tank.

• Service tank for fuel.

• Control Cabin with control panels.

• Wet Dust Collector for pollution control (Optional) 

Drum mix plant is a continuous mix plant. The system consists of a total proportional controlled feed system, which delivers material on a slinger (charging) conveyor by Gathering conveyor. The asphalt and filler proportion enters the drum simultaneously with aggregate.

Drum mix plant is a continuous mix plant. The system consists of a total proportional controlled feed system, which delivers material on a slinger (charging) conveyor by Gathering conveyor. The asphalt and filler proportion enters the drum simultaneously with aggregate.

MIXING :

The parallel flow drum mixer is a large rotating cylinder supported with four steel tyres bolted to the outside of the drum. The main gearbox drives the drum by the chain to a large sprocket bolted to the outside of the drum.

As the aggregate discharges from the slinger conveyor in to the drum mixer charging chute the bitumen is introduced. The bitumen cools very fast and balls up with the fine aggregates and dust. The first sections of flights are spirals that prevent the material from moving backwards to the slinger conveyor end. It prevents spillage. The second flights set are angles that roll the material with minimum amount of exposure to the direct flame. The last set flights are cupped shaped. These flights are meant to lift the material from bottom to the top of the drum, discharging it in a vial through hot gases quickly spread over the aggregate.

COMBUSTION CHAMBER :

It is a steel cylinder with refractory material at the charging end of the drum. The function of the cylinder is to obtain complete combustion of the fuel. After some operation, combustion chamber gets very hot. In the case of oil, the atomized spray of the fuel from the burner, passing through the chamber, comes in contact with intense heat, which converts the atomized spray to a gas. Once in a gaseous form, the fuel burns instantly.

: MINERAL FILLER :

COMPRESSOR:

The twin-lobe compressor is a positive displacement rotary blower or roots blower is very precision machine. The clearance between rotor to rotor and rotor to casing are very fine. The compressor has two rotors each having two lobes of identical profile rotates without touching each other or casing also. Since no part inside the compression chamber touches each other, lubrication of the compressor chamber is not needed and compressed air delivered is free from oil. There is also no wear in compression chamber so maintenance cost is very low.

The Compressor foundation is done by leveling. Provide anti-vibration pad on base frame of compressor. Compressor is connected with mineral filler hopper through rotary valve by pipe line.

The mineral filler consist of the rotary valve which is driven by a D.C. Motor through gear box as variable speed for quantum adding of filler material to the aggregate with bitumen. The filler material is passed through pipe line by compressed air.

The parallel flow drum mixer is a large rotating cylinder supported with four steel tyres bolted to the outside of the drum. The main gearbox drives the drum by the chain to a large sprocket bolted to the outside of the drum.

As the aggregate discharges from the slinger conveyor in to the drum mixer charging chute the bitumen is introduced. The bitumen cools very fast and balls up with the fine aggregates and dust. The first sections of flights are spirals that prevent the material from moving backwards to the slinger conveyor end. It prevents spillage. The second flights set are angles that roll the material with minimum amount of exposure to the direct flame. The last set flights are cupped shaped. These flights are meant to lift the material from bottom to the top of the drum, discharging it in a vial through hot gases quickly spread over the aggregate.

COMBUSTION CHAMBER :

It is a steel cylinder with refractory material at the charging end of the drum. The function of the cylinder is to obtain complete combustion of the fuel. After some operation, combustion chamber gets very hot. In the case of oil, the atomized spray of the fuel from the burner, passing through the chamber, comes in contact with intense heat, which converts the atomized spray to a gas. Once in a gaseous form, the fuel burns instantly.

: MINERAL FILLER :

COMPRESSOR:

The twin-lobe compressor is a positive displacement rotary blower or roots blower is very precision machine. The clearance between rotor to rotor and rotor to casing are very fine. The compressor has two rotors each having two lobes of identical profile rotates without touching each other or casing also. Since no part inside the compression chamber touches each other, lubrication of the compressor chamber is not needed and compressed air delivered is free from oil. There is also no wear in compression chamber so maintenance cost is very low.

The Compressor foundation is done by leveling. Provide anti-vibration pad on base frame of compressor. Compressor is connected with mineral filler hopper through rotary valve by pipe line.

The mineral filler consist of the rotary valve which is driven by a D.C. Motor through gear box as variable speed for quantum adding of filler material to the aggregate with bitumen. The filler material is passed through pipe line by compressed air

• Ensure that the filler material is dry and screened.

• Avoid any sharp bends in the pipe lines.

• Bends should be large in radius.

• Check air breather & filter regularly.

• It should be free from dust and foreign particles.

• Check the “V” Belt alignment of compressor and drive.

• Use Enklow 320 or equivalent oil for compressor.

BITUMEN TANK:

The tanks are cylindrical in shape fabricated out of 5 mm thick steel plate and is well insulated with fibre glass wool to avoid heat losses. The tanks are mounted on a sturdy steel frame and suitable for fitting axles or jacks for installation.

The tanks are heated by the direct firing principle for maximum thermal efficiency. A chimney leads the flue gases out into the atmosphere. A wide enough man-hole with its cover is provided on top of the tank for an easy services as well as for temperature gauge is fitted on the tank wall with other standard accessories with tin pipe, over twin & vent pipe, inlets, outlets & drain, access ladder etc. Large diameter steel tubes are positioned within the tank in a “U” formation and the design facilitates easy removal of the tubes for replacement or for clearing of carbon deposits inside the fire tube.

The efficient use of bitumen depends upon its viscosity at the time of application. Bitumen viscosity varies with its temperature so that it is controlled in terms of bitumen temperature, which is easily measurable.

Bitumen tank is fully insulated to minimize the heat loss. Bitumen inside the tank is heated by “U” shape heating tube fitted with an automatic burner of adequate capacity. The fuel for this burner is supplied from the fuel tank, which is on the top of bitumen tank. On the top of the bitumen tank manhole is provided for inspection and charging of bitumen. On the front side of the backside a thermometer is provided to see the temperature of bitumen for operator and thermocouple connected with control panel to read temperature of bitumen for operator. Bitumen pump of Drum Mix Plant is driven by a D.C. Motor to have variable speed.

The several stages through which bitumen passes requires heat to maintain proper operating temperature of about 150 deg C to 180 deg C. The bitumen pump and all bitumen lines except pipe- fittings and valves are jacketed to cover by hot oil. Hot oil tank is mounted on the top of the bitumen tank. Separate motor and driven pump is used to circulate the hot oil from tank to jacketing sections.

All the accessories like bitumen tank, hot oil pump, Reduction gearbox with D.C. Motor, Jacketed pump are rest on sturdy chassis and are provided with rigid legs for erection purposes.

While lightening up the burner for heating the bitumen, make sure that “ U” shaped heating pipes are immersed in to the bitumen otherwise it may lead to fire in the tank Hence never light up the burner incase “ U” shape heating pipes are open.

BURNER

The following operation is performed by bitumen. When power is on the immersion heater in the pre-heater heats up the fuel up to the thermostat range and there after maintains a fuel supply at the burning temperature. During the heating period the fuel is free to expand out of pre-heater and circulate around the nozzle, solenoid valves and back to the heating tank. If the fuel of the burner is Diesel, then pre-heating operation is not required in the Drum Mix Plant.

The burner operates on hi or low flame in response to the demand of temperature of mix material. The burner is operated in auto or manual condition. In manual operation, first set the selector switch of the flame in the hi or low position. Push the ignition button and at the same time start the pump. When the flame is lightened up, release push button and start the blower.

To shut-off the burner stop the pump whenever required. Keep blower in running condition for some period. In running condition if blower flame is filed the buzzer blows to indicate through the controller in the control cabin.

INSPECTION AND MAINTENANCE OF DRUM MIX PLANT:

• Check the fuel temperature during running condition.

• Check the fuel oil pressure as per requirement. If required set it by pump pressure.

• Check the pump, heater and other pipe lines against leakage.

• Inspect the burner flame daily to ensure that no change has taken place since it’s previous condition.

• Check that sight glass and photocell are neat and clean.

• Examine fire refractory block against damage weekly.

• Clean all nozzles within a week. Never use a pin or metal scraper for cleaning the nozzle. Ensure if nozzles have different capacity, then re-insert in same manner.

• Check that the electrodes and porcelain are clean and spark gap is currently set.

• Regularly clean the oil filter.

WET DUST COLLECTOR:

This is optional equipment used to control the pollution. By the thermo drum mix process two types of emission may be encountered: particulates and blue smokes. Elimination of blue smokes by protecting the asphalt from the radiant heat and the agglomeration of particulates with foaming asphalt. However not all of the fine particulates with foam is engulfed with asphalt, So it is necessary to take additional measures to collect sufficient quantities of these particulate emissions.

The efficient method of collecting sufficient quantities of these particulate emissions is the wet type collector. The principle of this equipment is wetting the dust particles entrained in the exhaust gas stream and tapping them in water droplets which for out of the exhaust gas and drained from the system in the form of a water sludge.

OPERATING PRINCIPLES OF THE VENTURI TYPE WET DUST COLLECTOR :

The dust laden exhaust gas is drawn from the drum mixer and in to the Ventura by exhauster. At the Ventura throat the exhaust gas passes through a water spray introduced by a two-nozzle spray bar. Dust particles surrounded by water spray gets wetted. The extreme turbulence in the Ventura promotes close, intimate contact of water and dust particles to assure through mixing. In the separator, the dust-laden water is then drained out in the form of water sludge in to a setting pond.

High pressure in the exhaust gas stream assures most efficient operation of the Ventura type collectors with less maintenance. The exhaust gas stream more than doubles its rate of speed as it is forced through the Ventura and this rapid acceleration creates extreme turbulence in the exhaust gas stream causing a highly effective and efficient mixing action between the dust particles and spray water. The completely assembled Ventura has an adjustable throat powered by a linear actuator, which is controlled from an operator’s console. This permits fine-turning to get the optimum cleaning efficiency for Drum Mix plant operating conditions.

CONSTANTLY PRIMED WATER PUMP :

Water pump supplied with wet collector of Drum Mix Plant is frame mounted with a sealed water tank from the inlet side of the water pump. In operation, the pond water enters high in the tank and exists near the bottom. When shut down, the tank maintains a head of water on the pump for start up. This eliminates the priming of the pump on start-up.

SETTLING POND FOR SLUDGE DRAINAGE :

A setting pond will have to be constructed of sufficient size and water capacity depending on the model of wet dust collector being used with the thermo drum in Drum Mix Plant. The settling would have an approximately equivalent to the amount of water passing through the wet collector in one hour, The settling pond is divided into three sections by weirs. The sludge from the separator enters section first where much of the particulates settle out before flowing over in to the second section. By the time water enters section three is amply clarified for re-circulation.

NOTICE:

As a safety precaution, always enclose or cover-up setting pond with fencing, as water temperature during operation is approximately 150 deg. F.

OPTIONAL EQUIPMENT FOR DRUM MIX PLANT:

• Automatic pressure jet oil burner with thermostatic controls.

• Bitumen pump with jacketed body.

• Bitumen metering system with variable speed 5 HP D.C. drive motor.

• Bitumen strainers.

• Rotary gear pump.

• Stationary or Mobile.

• Barrel Lifting arrangement.

• Suitable axles (with or without Pneumatic tyres to render the unit mobile)

• Automatic oil firing system can be supplied as packaged unit designed for installing on to locally made tanks confirming to PERFECT design requirements.

• Multi tank distribution depots for higher capacity bitumen storage with modular tank designs.

• Custom built tanks for higher storage capacity.