Dust-free ship-unloading
Ships that are loaded with cement can be unloaded dust-free using a pneumatic loading and unloading installation. Van Aalst Group specializes in both mobile self-unloaders and unloading systems that are installed on cement carriers. The installations are always equipped with TBMA loading chutes to ensure the dust-free transfer of product.
Ship loads of cement can be transferred efficiently and dust- free into silos using a pneumatic loading and unloading facility. These facilities can be equipped with a loading chute that is able to fill bulk trucks and/or railcars.
If a port only occasionally docks a cement-carrying ship, it will not necessarily be equipped with an onshore pneumatic unloading system with loading chute. In this situation, it is better if the vessel itself is equipped with an unloading installation. These vessels are especially useful as they can sail all over the world, and call at ports that lack the appropriate infrastructure for unloading cement.
Pneumatic unloading systems can be installed on vessels from 2,000dwt, but are of particular interest for cement carriers transporting up to 30,000 tonnes of cement. Unloading capacities can range from 100tph (tonnes per hour) to 1,200tph.
Companies like Novalgoma, which rent cement carriers, therefore often equip their (new) ships with installations from Van Aalst. Van Aalst Group BV has been active in the engineering and construction of pneumatic handling systems for self- unloading cement carriers since the 1970s. The corresponding loading chutes are designed and delivered by TBMA.
CEMENT
CARRIERS
In cement
carriers, the
equipment for
pneumatic
unloading is
placed in an
engine room
between two
cargo spaces of
the ship. In both
spaces, a suction
pipe is placed
which ends at the bottom of the hold. A provision is placed in the pipe of the suction nozzle for mixing the cement with air, so that the powder can be easily sucked into the transport vessels. In order to minimize the wear and tear in the suction pipe, the bends are less than seven times the radius of the pipe’s diameter, and they maintain the full diameter throughout the whole length.
Dust-free ship-unloading
The length and diameter of the suction nozzle co-determine the required vacuum capacity. The flat bottom is aerated to fluidize the product to ensure that the very last bit of cement flows into the mouthpiece of the suction pipe.
RE-LOADER TANKS
The re-loader tanks in the engine room first are filled and then pressed empty. A vacuum pump first empties Tank One. Then a valve connected to the suction pipe opens, allowing a mixture of cement and air to be drawn into the vessel. The air escapes at the top of the vessel through a dust filter; the cement remains in the vessel as a result of the force of gravity. The amount of cement in the boiler is monitored by a level probe. Once Vessel One is full, the system switches automatically several valves, so that Boiler Two is filled.
