- Application field
- Vapor Recovery Process
- Terminal implementation
Q(i): is given by the maximum loading capacity of the terminal (max. N° loading arms connected x capacities) + vapour growth factor. The vapour growth factor is given by the pressure drop of the vapour collector and the vaporization of the vapours above the liquid.
Q(c): as loading is continuous it is directly based on Q(i)
Q(4): again as the loading is continuous it is based on Q(i) – vaporization effect which stabilized during loading.
Q(d): Not considered as loading is continuous over a long period and no adjustment can be done.
Concentration: is a uctuating value as maximum concentration is reached only at the end of the loading operation and is almost nil at the beginning.
Vapour composition is based on the same principle than for trucks, composed of light ends HC.
A: The distance is generally long between jetties and VRU and a blower may be necessary to drag the vapours through the system. The blower is located at the outlet of the unit as it is the safest place (clean air in normal operation).
B: The dock Safety Unit design depends on Terminal philosophy but due to modern vessels design a shutdown valve and a DA is sufficient (see our HAZOP)
Hydrocarbon vapours are heavier than air and form a layer on top of the product. This layer prevents further evaporation
After 80% of the loading time the new vapours start leaving the vessel.
At the end of the loading operation the relative vapour saturation will reach approximately 80%
During unloading of the tanker inert gas or exhaust vapour is injected into the tanker. The Oxygen content is less than 5% by volume; Overall vapour concentration after unloading is relatively low.
Relatively high content of Methane
Mercaptan / Hydrogen Sulphide