The below figure shows a pump that transfers a steady stream of 35◦API crude oil from an oil tanker to a refinery storage tank, both free surfaces being open to the atmosphere. The effective length—including fittings—of the commercial steel pipe is 6,000 ft. The discharge at point 4 is 200 ft above the pump exit, which is level with the free surface of oil in the tanker. However, because of an intervening hill, point 3 is at a higher altitude than point 4. Losses between points 1 and 2 may be ignored. The crude oil has the following properties: Density ρ = 53 lbm/ft 3 ; Viscosity μ = 13.2 cP; Vapour Pressure Pv = 4.0 psia Answer the following questions: 1. If the combination of pump and motor is 80% efficient, how much electrical power (kW) is needed to drive the pump? 2. If, in order to avoid vapour lock, the pressure in the pipeline must always be above the vapor pressure of the crude oil, what is the maximum permissible elevation of point 3 relative to point 4?
The below figure shows a pump that transfers a steady stream of 35◦API crude oil from an oil
tanker to a refinery storage tank, both free surfaces being open to the atmosphere. The
effective length—including fittings—of the commercial steel pipe is 6,000 ft. The discharge
at point 4 is 200 ft above the pump exit, which is level with the free surface of oil in the
tanker. However, because of an intervening hill, point 3 is at a higher altitude than point 4.
Losses between points 1 and 2 may be ignored.
The crude oil has the following properties:
Density ρ = 53 lbm/ft 3 ; Viscosity μ = 13.2 cP; Vapour Pressure Pv = 4.0 psia
Answer the following questions:
1. If the combination of pump and motor is 80% efficient, how much electrical power
(kW) is needed to drive the pump?
2. If, in order to avoid vapour lock, the pressure in the pipeline must always be above the
vapor pressure of the crude oil, what is the maximum permissible elevation of point 3
relative to point 4?
3. If the flow in the pipeline were at the upper limit of being laminar, what pump exit
pressure would then be needed? (Answer this part without using the friction factor plot.
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