Pressure control strategy in Condensers.

Control of  condensing pressure is of interest, the system shown in Figures 

These systems operate by throttling the cooling water flow through the condenser, causing a potential for high-temperature rise that is acceptable only when the water is chemically treated against fouling.

For good, sensitive control, the water velocity through the condenser should be such that its residence time does not exceed 1 min. Another rule of thumb is to keep the water velocity above 4.5 ft/s (1.35 m/s)