From a product contamination standpoint is nitrogen blanketing a fixed roof tank preferable to using a floating roof tank.
Fixed roof tank vs floating roof tank.
Floating roof also reduces the static electricity hazard.
Of currently used tank designs the fixed roof tank is the least expensive to construct and is generally considered the minimum acceptable equipment for storing liquids.
The primary consideration in selecting the type of roof is to prevent the vapour loss where by emission to atmosphere is eliminated.
Perfect designed internal floating roof storage tank is the best method to control the evaporation loss of the fixed roof tank.
Internal floating roof tank can be used to store gasoline jet fuel and other volatile oil and liquid chemicals like aldehydes alcohols methanol ethanol ketones acetone benzene benzene toluene xylene styrene.
This vapor was ignited at a boiler house some distance away.
When the tank was refilled with warm crude oil at 37 c 100 f vapor was pushed out into the space above the floating roof and then out into the atmosphere through vents on the fixed roof tank figure 5 16.
An external floating roof tank is a storage tank commonly used to store large quantities of petroleum products such as crude oil or condensate.
The roof rises and falls with the liquid level in the tank.
As per the oil indystry practice in india floating roof tank is used for storing hsd.
Closed floating roof tank this has an internal floating roof but eliminates natural ventilation of the tank vapor space.
It consists of an open topped cylindrical steel shell equipped with a roof that floats on the surface of the stored liquid.
Instead the cfrt is equipped with a pressure vacuum pv vent and may even include a gas blanketing system such as that used with fixed roof tanks these tanks are designed as in appendix c of the api standard 650.
Floating roof tank can be divided into two types internal floating roof and external floating roof.
A typical fixed roof tank consists of a cylindrical steel shell with a cone or dome shaped roof that is permanently affixed to the tank shell.