ABSTRACT
As per the way of heat transfer and its main characteristics for oil tank, the theoretical model of steam coil heating in large oil storage tanks was established. The Visual Basic language was applied for calculating the temperature field of crude oil in the heating process by the trial method procedure, and the variation law of temperature field and the energy effective utilization rate of oil tank could be obtained. Results show that the temperature of crude oil and the energy effective utilization rate became higher with the increase of the ambient temperature, steam pressure, and the reduction of storage liquid level. The temperature of crude oil near the steam coil became higher with the increase of steam pressure. The oil temperature at the tank outlet presented periodic change, which was affected simultaneously by the steam pressure and the ambient temperature.
Nomenclature
a | = | heat transfer coefficient for steam coil, W/(m2 · °C) |
d | = | the inner and outer diameter of the coil as well as the diameters of each layer with the sediments, m |
λ | = | the heat conductivity coefficient of crude oil, W/(m · °C) |
ρ | = | the density of crude oil, kg/m3 |
c | = | the specific heat of crude oil, J/(kg · °C) |
υ | = | the viscosity of crude oil, m2/s |
β | = | the expansion coefficient of crude oil, °C−1 |
ε | = | the intermediate coefficient, nondimensional |
Nu | = | the Nusselt number, nondimensional |
Re | = | the Reynolds number, nondimensional |
Gr | = | the Grashof number, nondimensional |
Pr | = | the Prandtl number, nondimensional |
Fo | = | the Grid Fourier number, nondimensional |
Bi | = | the Grid Biot number, nondimensional |
K | = | total heat transfer coefficient, W/(m2 · °C) |
F | = | the area of steam coil heater, m2 |
t | = | temperature, °C |
G | = | the mass of in-tank oil, kg |
τ | = | the total heating time, s |
η | = | the effective utilization rate, % |
Q | = | quantity of heat, kJ |
Subscripts | = | |
0 | = | steam coil |
1 | = | forced convection |
2 | = | natural convection |
i | = | number |
f | = | floating Roof Tank |
x | = | x orientation |
y | = | y orientation |
o | = | the heated oil |
oz | = | final |
os | = | initial |
j | = | ambient environmental |
p | = | coil wall |
z | = | steam |
zong | = | total quantity of heat released |
Nomenclature
a | = | heat transfer coefficient for steam coil, W/(m2 · °C) |
d | = | the inner and outer diameter of the coil as well as the diameters of each layer with the sediments, m |
λ | = | the heat conductivity coefficient of crude oil, W/(m · °C) |
ρ | = | the density of crude oil, kg/m3 |
c | = | the specific heat of crude oil, J/(kg · °C) |
υ | = | the viscosity of crude oil, m2/s |
β | = | the expansion coefficient of crude oil, °C−1 |
ε | = | the intermediate coefficient, nondimensional |
Nu | = | the Nusselt number, nondimensional |
Re | = | the Reynolds number, nondimensional |
Gr | = | the Grashof number, nondimensional |
Pr | = | the Prandtl number, nondimensional |
Fo | = | the Grid Fourier number, nondimensional |
Bi | = | the Grid Biot number, nondimensional |
K | = | total heat transfer coefficient, W/(m2 · °C) |
F | = | the area of steam coil heater, m2 |
t | = | temperature, °C |
G | = | the mass of in-tank oil, kg |
τ | = | the total heating time, s |
η | = | the effective utilization rate, % |
Q | = | quantity of heat, kJ |
Subscripts | = | |
0 | = | steam coil |
1 | = | forced convection |
2 | = | natural convection |
i | = | number |
f | = | floating Roof Tank |
x | = | x orientation |
y | = | y orientation |
o | = | the heated oil |
oz | = | final |
os | = | initial |
j | = | ambient environmental |
p | = | coil wall |
z | = | steam |
zong | = | total quantity of heat released |