Grain Logistics
Grain logistics
Logistics is becoming more and more important because of the globalisation of the
economy. The free trade between nations heralds substantial opportunities in the field of
logistics. Moreover the competition arising from the privatisation of ports around the
world, coupled with the increasing trade volume between countries, will lead to a
reduction in the costs of operations.
Pneumatic equipment - examples
Grain from the USA is exported in big oil tankers which has resulted in logistic
problems due to the draft of the tankers and the fact that there is only a small hole
through which the grain can be accessed. As a result mobile pneumatic unloaders with a
pipe size of 8" (210 mm) have been developed for this type of operation. They can be
seen in use in world-wide lighterage operations. The popularity of these mobile pneumatic
unloaders is due to their low cost, versatility, ease of operation, ease of maintenance
and portability. Mobility is particularly important because of the varieties of volume
encountered and the diversity of places where the grain is unloaded.
The installation of a boom improves efficiency as the operator is no longer dependent
on the ship's gear. The length of the pipes is easily adjusted upwards or downwards so the
use of suction/pressure is totally practical. Under the conditions shown in Fig. 1, 140
t/h can be achieved. Fig. 2 depicts a stream of grain as can be seen on barge unloading
operations, transhipment and ship to shore facilities.
This type of equipment has limited use in the more sophisticated ports within the
countries of the world as the increase in volume, which has already been discussed, has
led to the development and introduction of specialised terminals with high capacities and
the ability to comply with the more stringent environmental regulations.
Fig. 3 and 4 show pneumatic unloaders for an oil processing plant which have the added
advantage that they can unload during bad weather. In this case the decision to use
pneumatic equipment is very much influenced by environmental regulations. Sound insulation
of the blower house reduces noise and dust is captured by means of filter. Moreover the
ease with which the pipe length can be adjusted solves the problem represented by natural
rise and fall of the tide.
Moving large volums of grain in a non-specialised terminal poses several logistical
problems which have been addressed by Multiport equipment. A generator is essential either
to overcome local availability of power or just to reduce the cost of obtaining the
necessary energy. The boom on such equipment is usually between 20 m to 27 m, depending on
the size of the ship and the shore layout. This equipment is normally used to load trucks.
Its standard capacity is up to 300 t/h.
A rail mounted Multiport is generally used in a specialised terminal such as a port
silo, a flour mill or a feed mill. A continuous flow of material is essential for the
greatest efficiency of the overall discharging operation. The power normally via a cable
drum but the layout varies according to the shore installation. In these circumstances the
most efficient method of unloading is achieved through a combination of standard
components with custom made parts.
In Fig. 5 the boom has been lowered to the ground to make maintenance easier. In this
position it is also ideal for anchoring it down in areas such as those which are prone to
typhoons.
As its name suggests the Combiport offers more than one option in one piece of
equipment. It is possible to unload from large vessels and load into smaller units. The
loading operation can also be carried out in conjunction with a dust reduction system.
This system minimises the air flow. As a result the dust is not pushed out with the air.
The piece of equipment shown was also equipped with a 7 ton winch to lift a frontloader
into the hatch.
Pneumatic unloaders can be used for non-free flowing materials. Usually the type of
equipment that is commonly seen in river operations is used. The material is collected by
means of a hydraulic rotary feed nozzle.
Every minute counts when large volumes have to be discharged. For this reason any winch
that is required for the frontloader should be independent. The use of 7 ton frontloaders
resulted in a speedy clean up operation at the tower, 600 t/h, which is shown in Fig. 8.
To move this frontloader onto the ship, a 7 ton crane was installed in the same structure
with independent control.
The dual lines enables work at two points to be carried out concurrently, which results
in a higher than average performance in the normal use of events and during the clean up
operation.
Fig. 9 shown the 90° bend with basalt whilst Fig. 10 shows the grain being fed to two
belt conveyors, each with its own dust reduction system. 2 unloaders of 1000 t/h have been
produced for the biggest flour mill in the world in Indonesia.
Customised Solutions
In older mills the unloading systems are no longer compatible with the size of the new
ships. Therefore the mechanical conveyors and their scale must be upgraded when it comes
to a new unloading system. Attaching a pneumaic boom to an existing wall or on a new
dolphin can sometimes solve some of the problems posed in upgrading these facilities.
Conclusion
Practical experience dictates that the use of pneumatic unloaders for grain offers the
best technical / economical solution. The higher energy consumption of the pneumatic
systems is easily offset by the combination of low maintenance costs, easy operation and a
safe and reliable means of operation.
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