ASSIGNMENT 7 – RELIEF SIZING
Due date:
19 September 2008
QUESTION 1
Problem 9-1.
Estimate the diameter of spring-type liquid reliefs for the following conditions:
QUESTION 2
Problem 9-25.
A relief device must be designed for a vessel to relieve 1800 gpm of crude oil liquid in
the event that a discharge line is blocked. The MAWP is 250 psig, and a maximum
backpressure of 50 psig is expected. The specific gravity of the oil is 0.928, and its
viscosity is 0.004 kg/m s.
a.
b.
c.
Specify an appropriate set pressure and overpressure for this relief.
What type of relief should be used: a rupture disc, a conventional spring-operated
relief, or a balanced-bellows relief?
Determine the relief diameter required, in inches.
QUESTION 3
Problem 9-28.
A relief device must be installed on a vessel to protect against an operational upset. The
relief must discharge 53,500 lb/hr of hydrocarbon vapor. The relief temperature is 167°F,
and the set pressure is 75 psig. Assume an overpressure of 10% and a backpressure of 0
psig. The hydrocarbon vapor has a molecular weight of 65, a compressibility of 0.84, and
a heat capacity ratio of 1.09. Determine the diameter of the relief.