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In a vacuum column overhead ejector condenser, Cooling water supply pressure and cooling water return pressure (Both at ground level battery limit) to condenser (as provided to vendor) is 3.5 Kg/cm2(g) and 2.5 Kg/cm2 (g) respectively. As per the elevation drawing and layout, cooling water supply pressure at inlet of first stage condensers appears to be around 0.34 Kg/cm2g considering static head and frictional loss. At the outlet of condenser pressure becomes -0.16 Kg/cm2g considering differential pressure across first stage condenser in cooling water side as 0.5 Kg/cm2.
With this condition cooling water flow will be established across condenser or not? If not, will placing the isolation valves of return line at ground level help in water circulation across condenser?
 
Answers
18/08/2015 A: Ralph Ragsdale, Ragsdale Refining Courses, ralph.ragsdale@att.net
I won’t verify your calculations. Just be sure to consider the “pressure gauge pressure” at the water supply, the line friction drop, and the static head at the condenser inlet. Allow for a reasonable condenser pressure drop. What is the calculated “gage pressure” at the condenser outlet? It must be high enough to flow into the required return system back pressure calculated at the elevation of the condenser. Again, include static head and line loss in that calculation as well.