Closed recirculating cooling system

Figure 1.2 Schematic of closed recirculating cooling system.

In open recirculating systems evaporation is the major factor in heat disposal. In these evaporative systems circulating water is continuously scrubbed with air, therefore saturated with dissolved oxygen. In contrast, water in closed recirculating cooling systems usually will contain minimum dissolved oxygen, even though the systems may include vented expansion tanks. 

Reactor coolant primary circulation system Depending on design, this closed-loop cooling system may recirculate high-purity treated water or other fluid at 300,000 to 450,000 US gpm (1,136-1,704 m3/m), and at velocities of 15 to 16 ft/s 4.5 to 4.9 m/s. 

CAS 111-30-8 8001-54-5 EINECS/ELINCS 203-856-5 204479-9 Uses Microbicide, slimicide, bactericide, algicide, surfactant for water treatment, recirculating cooling towers, air washer systems, recirculating process water, closed loop cooling systems, reverse osmosis, to clean and penetrate microbiologically fouled suifs. 

The arrangement for closed recirculation is shown in Fig. 4.40. It overcomes many of the problems encountered with the open system. Typical applications include engine cooling and heat rejection from refrigeration plant. 

FIGURE 4.40 Cooling water system (closed recirculation). 

Figure 8-3 Three basic types of cooling water systems. Top the once-through system where the cooling water is used once and then discharged. Middle the open recirculation system where the water is cooled and recycled through a system in which it comes in direct contact with air. Bottom a closed recirculation system where the water is cooled and recycled without coming in direct contact with the atmosphere.

The closed recirculation system (see Fig. 8-3) is used when it is necessary or economical to produce cooling water at a temperature below that feasible with an open system, or it is important to prevent foreign matter from getting into the water.14 Here secondary heat exchangers are used to remove the energy. The only water loss is due to leaks, and since it is an isolated system, any water pretreating that is required is minimal. 

The most appropriate system for the plotform wos considered to be on indirect seawater cooling system which uses seawater to cool recirculating inhibited fresh woter in o closed loop system. The fresh water is circulated on the shell side of the process exchangers to minimise corrosion problems ond eliminate the need to use exotic materials which would be... 

Widespread practice has always existed, unfortunately, by owners and operators of cooling systems, or their general contractors and consultants, to specify chemical treatment operating standards in isolation, with little or no actual contact with prospective vendors of water treatment service companies before the issuance of such standards. There is now a growing tendency for particularly low corrosion rates to be specified as a part measure of the quality of water treatment and technical services to be provided in water management contracts (say below 1 mpy for steel in closed-loop systems and below 2 mpy for steel in open-recirculating systems). These low rates are often unattainable in practice. 

A closed-circuit grinding system employs a high-efficiency air classifier wherein the classifier feed (i.e., the mill discharge) is exposed to outside air rather than recirculated air, thus reducing the product-cooling load. The system is shown in Fig. 13.4. 

Most cooling towers are open-recirculating types in which heat rejection mainly is accomplished by evaporation of water. There also are closed cooling systems (of which an automobile radiator would be typical), from which heat is dissipated by the forced flow of air across radiation sections. In some combination systems, heat from closed cooling circuits is transferred through heat exchangers into circulating water which is cooled by evaporative systems. 

The cooling water system of the MTR reactor is a closed recirculating aystea with a saall percentage of purge and aake-up water in order to control the intensity of long-lived induced activity and the accuaulation of corrosion products. 

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