The Bulk Material Handling Business Unit of Larsen & Toubro Limited (L&T) have conceived, designed, supplied, erected and commissioned an integrated material handling system at Visakhapatnam in the state of Andhra Pradesh, India for the company Vizag Seaport Limited. The scope of work carried out by L&T includes design & supply of equipment such as Mobile Hoppers, Stacker Reclaimers, Wagon Loaders, Conveyors, erection, testing and commissioning with the exception of Civil work. Vizag Seaport Limited, a Joint Venture company formed by RIPLAY, UK and PSL, Bangkok & Gammon India, awarded the EPC contract to L&T ECC Division for the Bulk Cargo handling system.
Vizag Seaport Limited has set up two multipurpose berths EQ8 and EQ9 for handling heterogeneous cargo on BOT basis as per the agreement signed by them with Visakhapatnam Port Trust. Generally berth EQ8 is utilised for unloading import cargo – mainly coking coal, limestone etc and EQ9 is utilised for loading export cargo – mainly thermal coal. The total length of the berth is 510 m with a width of 20.4 m. The berths are designed to handle a total cargo of seven MTPA by vessels with capacities of 45,000 DWT to 70,000 DWT and with berth occupancy of 60 per cent. The port is located near the coal jetty area, opposite to the GFCL yard, in the northern arm of the inner harbour of Visakhapatnam, in the State of Andhra Pradesh, India. At present a draft of 10 m is available and it will be further dredged to a draft of 13.5 m.
An innovative plant layout was developed by L&T due to enormous space constraint and without compromising the loading/unloading capacities of the equipment and overall cargo handling facilities. This was done by keeping two stacker reclaimers on the same track and by introducing an elevator conveyor after the tripper. Also, the wagon loader was conceived with boom conveyors on either sides of the platform, as the complete rake of 58 wagons could not be placed, and required splitting into two rakes. The material handling system supplied by L&T was conceived with the following basic operational scheme:
1) An average daily unloading rate of 1,500 T/h using two mobile harbour crane of 750 T/h average capacity each (supplied by others)
2) Storage of cargo at a stockpile of 160,000 and a capacity using either of two stacker reclaimers of 1,600 T/h stacking – 1,050 T/h reclaiming
3) Per day loading of four railway rakes of 58 wagons each, using one wagon loader of capacity 1,050 T/h.
The above scheme was facilitated with a network of conveying systems with sufficient redundancy to take care of ship unloading and wagon loading operations.
The mobile harbour crane discharges the cargo into the mobile hoppers that are mounted at the edge of Berth EQ8. From the mobile hopper the cargo is taken to the stockyard either by conveyors BC1, BC2, yard conveyor BC3 and stacker reclaimer SR1 or by conveyor BC1, BC2, yard conveyor BC4, and stacker reclaimer SR2. Two stacker reclaimers SR1 and SR2, which are mounted on the same rail track on yard conveyors BC3 and BC4, are used for stacking the material.
The reclaimed cargo by the stacker reclaimer is led to loader conveyor BC6 through conveyor BC5. There is a provision to load the material directly on a truck from the mobile hopper which is fitted with a telescopic chute for direct dispatch to the client through a road weigh bridge. A belt weigher, in-motion weighbridge, and road weighbridge have been installed to get the flow rates and loading and unloading data.