STEP 1 : Which product(s) will be discharged ?

Most free flowing products with a density between 0.5 and 1.5 and a natural angle of repose less than 40° can be handled by VIGAN equipment.

Products such as all kind of cereals (corn, wheat, barleys, ….),oilseeds, nuts, raw materials for animal feeding, certain chemicals such as soda ash, alumina , …. but also slightly compacted products such as soy bean meal (SBM).

VIGAN equipment do not damage the products: see explanations

STEP 2 : How many tons to be unloaded per year ?

This amount has always be in mind to balance its importance with the financial investment, the unloading rate (or also called handling capacity) in metric tons per hour (mtph) and /or with other factors.

Most useful data is to compute the tonnage of each product and the forecasted figures for the coming years.

STEP 3 : What is the target unloading rate ?

Maximum capacity versus average capacity in mtph

Most commonly and in practice, maximum capacity is defined at the beginning (top) of the hold discharge when the intake nozzle (suction or mechanical) is in the middle of the opening area of the hold.

Nominal capacity refers usually to the calculated capacity during the engineering and the design of the equipment.

Average capacity is considering the whole ship unloading operation and therefore also the cleaning period during which the unloading rate use to drop significantly.

Many factors are affecting the average capacity in practice such as for instance:

• Type and number of machine(s) in operation
• Size and type of unloaded vessels
• Manpower
• Captain instructions
• Weather conditions
• Auxiliary equipment ,
• and others : maintenance, type of product, ….

For Continuous Ship Unloaders (CSU), the average unloading efficiency varies usually between 60 % (mobile or portable) and up to 80 % (Tower, NIV or SMPORTER type).

When comparing the average unloading efficiency between equipment and/or experimented unloading operations, a most careful attention must be paid on considering exactly the same parameters such as taking or not into account any stoppage due to silo or warehouse problems, the lack of trucks for product loading, the times “lost” for the displacement of the equipment along the ship and so on.

Example:
maximum capacity 300 mtph – average efficiency 70 %
average unloading rate : 210 mtph.
Let suppose 22 working hours per day:
+/- 4620 tons per day (tpd)

• average unloading rate and
• number of working hours per day.

• Enough trucks to ensure the product transport at maximum unloading rate ?
  This is a most common limiting factor when the maximum unloading capacity is above 300 – 400 mtph.
• Sufficient capacity (maximum !!!) of the conveying system to the silos and/or warehouse ?
• Other factors such as maximum berth occupancy time and so on ?.

STEP 4 : CHOOSE YOUR EQUIPMENT

VIGAN main types of equipment and most common maximum capacities:

PNEUMATIC

• Mobile or portable (also called vacuvators or grain pumps)
  Maximum capacity : from 120 to 250 mtph.
• Tower type -> mostly for barge of vessel less than 20,000 DWT
  Maximum capacity : from 200 to 400 mpth
• NIV or gantry type -> mostly for vessels more than 20,000 DWT up to Post Panamax
  Maximum capacity : from 200 to 600 mpth

MECHANICAL : SIMPORTER (Twin belt technology)

Maximum capacity : from 600 to 1,500 mpth

It should be noted the following:

• Almost all equipment can be either mobile, either self-propelled or stationary.
• Most of VIGAN equipment are customized : many options and accessories available.