A tanker carrying tolueneis unloaded to an onshore storage tank using the ship’s pumps. The pipeline is 225-mm inside diameter and 900-m long (200-m long suction line, 700-m long discharged line). Miscellaneous losses due to fittings, valves, etc., amount to 100 equivalent pipe diameters at the suction side, and 500 equivalent pipe diameters at the discharged side. The maximum liquid level in the destination storage tank is 30 m above the lowest liquid level in the ship’s tanks. The ship’s tanks are nitrogen blanketed and maintained at an absolute pressure of 1.05 bar (1 bar = 105 Pa). The storage tank has a floating roof, which exerts an absolute pressure of 1.1 bar on the liquid. The ship must unload 1000 metric tons within 5 hours. Taking pump efficiency as 70%, (ρ = 874 kg/m3, μ = 0.62 cP, Pvapor = 0.037 atm absolute). Determine: A. Pump head (m) B. Pump differential pressure (Pa) C. Suction head (m) and pressure (Pa) D. Discharge head (m) and pressure (Pa) E. Actual pump power (kW) F. Available NPSH (m)
A tanker carrying tolueneis unloaded to an onshore storage tank using the ship’s pumps. The pipeline is 225-mm inside diameter and 900-m long (200-m long suction line, 700-m long discharged line). Miscellaneous losses due to fittings, valves, etc., amount to 100 equivalent pipe diameters at the suction side, and 500 equivalent pipe diameters at the discharged side. The maximum liquid level in the destination storage tank is 30 m above the lowest liquid level in the ship’s tanks. The ship’s tanks are nitrogen blanketed and maintained at an absolute pressure of 1.05 bar (1 bar = 105 Pa). The storage tank has a floating roof, which exerts an absolute pressure of 1.1 bar on the liquid. The ship must unload 1000 metric tons within 5 hours. Taking pump efficiency as 70%, (ρ = 874 kg/m3, μ = 0.62 cP, Pvapor = 0.037 atm absolute). Determine:
A. Pump head (m)
B. Pump differential pressure (Pa)
C. Suction head (m) and pressure (Pa)
D. Discharge head (m) and pressure (Pa)
E. Actual pump power (kW)
F. Available NPSH (m)
Note:
• The equivalent length method for minor losses can be computed as: ΣF minor (head units) = fD (Leq/Dpipe) x (v^2/2g)
• Use the Churchill equation for calculation of the Darcy friction factor
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