Question 1

A one-meter in diameter holding tank, which is opened to the atmosphere, is filled with water. A four-inch line (ID) connects the bottom of the tank to a control valve, 30 feet below (assume the liquid level in the tank has negligible impact on the head). To simplify head loss calculations, use a constant friction factor of 0.06.

a) Obtain the pressure versus volumetric flow rate graph for the system outlined (the graph must include the hydrostatic head, pressure drop across the valve and line losses).

b) Based on the ratio of the highest to lowest pressure drop across the valve, would a linear or equal percentage valve be better suited?

c) Based on your recommendation in b), obtain a suitable valve size if the maximum desired flow rate is 150 gpm.

d) Obtain the installed valve characteristic curve for a linear and equal percentage valve. Does your recommendation made in b) hold?

Question 2

Draw a P&ID of a suitable control system around a steam condenser. Inlets of the condenser include saturated steam and a glycol liquid stream that needs to be heated. The control objective is to be able to maintain the outlet temperature of the glycol stream at a desired set point.