|
D&G Asphalt Plant
1. Batching System
Every bin is equipped with a belt feeder controlled by frequency conversion, so the primary recipe is accurate with low energy consumption. Bin-wall vibrators are mounted on walls of sand silo to ensure the feeding quantity. The inlet is fixed mesh to prevent overflow and oversized material entering into the bins. The bins are mounted with emergent shutdown to stop the plant when an emergency occurs. The alarm system is controlled by the PEPPERL+FUCHS approach switch. The discharge door can be adjusted accordingly to ensure the pre-mix of the aggregate materials.
2. Filler Bin
Specially designed filler screw feeds filler from the filler bin to filler weighing hopper by various screw pitches. The fluidifying air system fixed in the tank cone is made of silicon dryer, adjusting pressure valve, solenoid and air ejector, to avoid humping in the bin cone. The blowing time and the intermission time can be adjusted to ensure equable and continuous filler feeding. The bag filter is fixed to the top of the filler bin to ensure that the filler conveying equipment works reliably.
3. Drying System
The design and high temperature resistant coating are totally based on the European standard, with a rational ratio of height to diameter, low energy consumption and high output. D&G adopts professional diesel/heavy oil burners from Italy, with low oil consumption and high intellectual; the steel plates of dryer blades are made of HARDOX 400 — high wear resistant and heat resistant special steel which is the best in the world, and process to dryer blades 
by digital-control cutting and NC bending.
Reducer: D&G uses the imported BONFIGLIOLI disc reducers (Italy), SKF heavy bearings (Switzerland) and central lubricating system. Motor: D&G adopts IP 55 ABB motors Sweden (Shanghai) or SIMENS motors.
4. Mixer
The mixer is manufactured according to European designs. It consists of double horizontal shafts, double reducers, and double motors and high-pressure asphalt sprayers and adopts the compulsory method of mixing. The plates are symmetrically crossed, which can ensure high-speed, effective and good mixing. The inner scale boards, plates and arms are made of high chromium and high molybdenum materials
. They are easy to be adjusted and changed. D&G adopts SKF heaving bearings (Sweden), ROSSI reducers (Italy), ABB vertical motors (Sweden) and NORGREN pneumatic components (UK). After assembly, the mixer is commissioned for 12 hours with electricity to ensure its good performance. The useful life is as long as that of the best in the world.
5. Vibrating Screen
D&G adopts the international double vibrating motors (or double horizontal shafts) and compulsory vibrating screen, the passing rate of which can reach 95%. The maintenance interval is 1000 hours. We adopt the CSI digital vibrating tester (USA) to do a 48-hour continuous test on every operating vibrating screen before ex-works. The layers of the screen are designed accurately. The inter-bins are large in volume. This can adapt to and satisfy the requirements of the materials and working conditions.
6. Weighing System
Both the aggregate and filler scales weigh the aggregate and filler accumulatively (5 aggregates, filler and recycled filler). Whether in the RFA (Relay-based Full Automatic) mode or the FCC (Fully Computerized Control) mode, both scales may be configured and controlled independently. In the RFA mode, the drop height is controlled manually while in the FCC mode, automatic drop height control is available, that is, the computer calculates and automatically corrects the lead times before the gate may be closed when various kinds of aggregate, filler and bitumen are weighed, with reference to the history on weighing errors introduced in weighing these kinds of materials. If steady flow of materials is maintained, the designed weighing accuracy is obtained after 3-5(average) batches of mix are processed.
The weighing hopper is a container with hot oil cladding to preserve heat and ensure weighing accuracy. The weighing hopper can calculate the portion of aggregates against that of the asphalt and display the temperature of asphalt on the computer in the control cabin. The data can be printed if necessary. The mixing-batch counter is connected to the bitumen sprinkler system. The counter increases by one for each batch of bitumen sprinkling.
7. Bag Filter
The special designed gravity filter is simple in structure and effective in filtering dust. The bag filter is installed with a cleaner, which blows back the dust using the ambient air in pulses. Both the interval and duration of the blowback may be adjusted easily from the cab, with reference to the readings on an indicator gauge showing the differential pressure between the upper and lower chambers of the collector and thereby indicating how much dust is attached to the bag wall. The bags are made of DUPONT NOMEX high temperature resistant materials. The level of emission is below 20mg/Nm3. It is installed with alarms which can warn against excessively high or low temperatures. Whenever the temperature exceeds the set point, the control system will shut off the fuel supply automatically, thereby effectively maximizing the bag life. The dust discharged from the bag filter is collected and conveyed to the inlet of filler elevator by the screws.
8. Hot Storage Bin
The hot storage bin is rectangular in shape. Its discharging door can be controlled in the control cabin or on the ground. An insulation layer is wrapped around the bin, including the bin body and the bottom cone part, for thermal conservation purposes. The discharging door is installed with an electric heater. The bin is designed to prevent isolation. It is fixed with a continuous level indicator (connected with acoustic and optical alerts). The skip is pulled to travel along the guide by the frequency controlling windlass. On the guide there are upper/lower limit switches and upper/lower gauge limit switches to maintain the safety running of the lorry on the guide. The frequency controlling windlass used in the drive & transmission system ensures steady and reliable operation of the lorry.
9. Control Room
The physical dimensions of the standard central control cabin are 6.0 x 2.5 m. The cabin is equipped with air conditioning and German electronic control cabinets and console. D&G adopts the products of SIMENS (Germany) such as PLC, low pressure electronic devices, contactors and industrial control computers. The LCD monitors, meters, buttons, indicators, transducers and enclosed switches are renowned ones from Germany and Japan. A 120-hour continuous test is conducted to the control system before leaving the factory to ensure its good operation. 
D&G adopts the Microsoft® operating system. The operating modes can be switched while the plant is operating. The control system is equipped with a network adaptor and modem. The production conditions can be checked through SMS, therefore it can be monitored and diagnosed from a distance.
 |
 |