Cooling closed-recirculating

Figure 1.2 Schematic of closed recirculating cooling system.

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. 

Deuterium sulfide is introduced with shaking into an ice-cooled suspension of Ig in DgO placed in a closed recirculating glass apparatus with all joints melt-sealed. Unconverted DgS is reintroduced into the reaction mixture. The heavy hydriodic acid formed is separated from the precipitated sulfur by filtration (in the absence of air) and separated from the dissolved DsS by prolonged evacuation. 

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. 

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. 

Starting in December 1984, the 107-N spent fuel storage basin cooling water recirculation system was operated. The 107-N basin recirculation facility cleaned N Basin in a closed-loop system. Mixed wastes were routed to the 190,000-L (50,000-gal) tank, where they were neutralized and then pumped to the 1314-N LWLS (DOE-RL 1990). 

Cooling water systems may be either recirculating or once-through types. In closed recirculating systems, oxygen can be excluded, and corrosion often can be controlled by adjusting the pH to an alkaline value. 

Vacuum flash processes, which operate under the atmospheric boiling point of the solution, include the Uhde—LG. Farbenindustrie process and the closely related Kestner process (22). In these, ammonia, nitric acid, and recirculated ammonium nitrate solution are fed into the neutralizer. Hot solution overflows to an intermediate tank and then to a flash evaporator kept at 18—20 kPa (0.18—0.2 atm) absolute pressure. Partial evaporation of water at this point cools and concentrates the solution, part of which is routed to evaporation. The rest is circulated to the neutralizer. 

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