Ahmed Saad Noaman
Petrojet
Cairo
External floating single-roof tanks
should not be used to store gasoline
in hot regions unless the deck plate’s
thickness exceeds 10 mm and it has
been treated with an anti-corrosion
coating. Solar radiation can cause large
problems in storage tanks with floating roofs. The direct contact between
the fluid and the floating deck raises
the fluid’s temperature and increases
the vaporization rate of products inside
the tank, both wasting product which
could otherwise be sold and creating an
unsafe operating environment.
This article centers on a study performed to determine the effects of July
31, 2016, solar radiation on a gasoline
storage tank in Cairo, Egypt. Late July is
typically the hottest time of the year in
Cairo, 40° C. with 20 mph winds. The
study was repeated and analyzed under
corrosion conditions to determine corrosion’s effect on fluid temperature.
The study used computational fluid dynamics (CFD) analysis to measure the gasoline’s temperature for 1
hr and then calculate vapor losses by
the charts provided in Perry’s Chemical Engineering Handbook. 1 Simulating solar radiation’s effect on fluid temperature inside the tank during design
will increase the tank’s safety during
operation.
Previous studies focused on if thermal stress on the floating roof could
Study sets
design limits on
floating single-roof tanks
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FLOATING ROOF DESIGN DATA Table 1
Min.-max product specifc gravity 0. 7-1.0
External rim height, Hor; Internal rim height, Hir; mm 950, 550
Pontoon length, w; mm 2,000
Rim distance, mm 200
Number of pontoons, N 20
External rim diameter, Øor; Internal rim diameter, Øir; mm 39,600, 35,544
Bulkhead external height, Boh; Bulkhead internal height, Bih; mm 935, 535
Bulkhead length, Wb; mm 1,972
External rim thickness, Tor; mm 10
Corroded external rim thickness, Tor; mm 7
Internal rim thickness, Tir; mm 16
Upper pontoon thickness, Ttp; Lower pontoon thickness, Tbp; mm 5, 8
Height above deck level, Hsub; mm 950
External rim height, Hor; mm 550
Corrosion allowance 3
Tensile strength: ultimate, yield; MPa 380-485, 205
Design yield strength, MPa; elongation at break 136, 25%
Bulk, shear modulus; GPa 160, 80
Poisson’s ratio 0.25
FLUID, SOLID MESH Table 2
Cell type Number of cells
Fluid 294,170
Partial 85,822