The spheres are not insulated, & hence i assume that during afternoon the temp. of vapor space may go as high as 60°C due to heat absorption from atm. while the same time the bulk liquid may remain same at normal temp. What we understand that we can cool the vapor space by spraying the LPG from transfer pumps at lower flow rates ( flow load is decided based on heat load in vaporised state).
I am furnishing the detailed design data could you please help me out if iam not wrong, & suggest me .
1. LPG Operating pressure of the Sphere : 11.4 barg
2. Initial temperature of vapor inside the Sphere : 50°C
3. Volume of the Sphere : 3140 m³
4. Initial vapor space available : 15% of Total volume i.e 471 m³
5. Avg. Molecular weight of LPG : 47.91 kg/kmole (HYSYS)
6. Liquid desntiy at 50°C : 500 kg/m³ ( HYSYS)
7. Avg. Specific heat of LPG Vapor at 50°C : 143.5 kJ/kgmole°C
8. Avg. Specific heat of LPG Vapor at 60°C : 92.35 kJ/kgmole°C
9. Vapor pressure at 50°C : 10.87 barg
10 Vapor pressure at 60°C : 13.56 barg
Assuming a steady state I have calculated vapor load in sphere for a temp rise of 10°C ( from 50 to 60) & total amount of heat in the vapors at 60°C.
Amount of vapor formed by the increase in temp. comes around 2921.12 kg to cool the same I have used bulk LPG from same sphere assuming it to be at 30°C.
I have estimated a cooling flow rate requirement of around 25 m³ to sprayed in one hour.
We have detailed out some spray arrangement also attached here for your reference, I need to confirm about the spray arrangement & requirement for LPG cooling .
Whether cooling requirement may arise due to other reasons also apart from heat absorption please let me know.