TABLE OF CONTENTS Cooling of fluids is an essential process at power-generation and industrial plants. Control of cooling water chemistry is very critical in preventing corrosion and fouling, and ensuring equipment reliability.
The most important uses for cooling water include:
Condensing turbine exhaust steam
Cooling process fluids
Protecting high pressure pump bearings
The volume of cooling water required for these processes, especially steam condensation, is often quite large. (Sufficient cooling water flow to steam condensers allows the condensed steam to reach its lowest temperature, which is important with regard to the thermodynamic concepts outlined in Supplement 2-1.) High cooling water flow rates usually prohibit the mechanical purifying techniques (demineralization, RO) that are used for smaller purposes such as boiler makeup production. Yet, some form of treatment is required to protect equipment. The following sections discuss types of cooling systems, water quality variations between different sources of supply, and treatment methods. Changing environmental regulations and improvements in cooling water treatment chemicals have added a complexity to treatment selection.
The type of cooling system most suitable for a process depends upon process operation, flow requirements, availability and quality of water, and environmental requirements regarding discharge. Most cooling systems belong to one of the following categories:
Once-through
Open recirculating (evaporative cooling towers)
Closed recirculating
Dry cooling systems for steam condensation are becoming more popular, especially at facilities where makeup water is scarce or where liquid discharges are restricted or banned. A detailed discussion of dry cooling systems is outside the scope of this...
