Closed cooling circuit

WSAC (Fig. 12-8n). Often one of the streams is closed-circuit cooling water to be used for remote cooling applications. These might be apphcations not compatible with a WSAC (rotating seals, bearings, cooling jackets, internal reactor cooling coils, etc.) or merely numerous, smml process streams in small HXs. 

Closed-circuit cooling splits the water chemistry needs into two isolated systems the evaporating section, exposed to the environment, and the circulated cooling section, isolated from the environment. Typically, this split reduces total water chemistry costs and water-related operations and maintenance problems. On the other hand, the split permits the effective use of a low-quality or contaminated maheup water for evaporative cooling, or a water source having severe seasonal quality problems, such as high sediment loadings. 

The closed circuit cooling ofthe industrial water by means ofcooling towers will be utilized with a flow of 6,000 m /h. 

The most powerful oxidizing inhibitors (chromates and nitrites) are toxic and their use is regulated or even prohibited by environmental legislation. Although chromates and nitrites may still be found in some closed-circuit cooling systems, they are increasingly replaced by other compounds such as molybdates or silicates. 

If no open cooling circuit is possible due to the structural conditions of the procedural processes, then the ring liquid is completely returned. The heat is then to be dissipated via an additional heat exchanger. It is now a matter of a closed circuit cooling (Figure 3.33). 

Another problem was the interaction between carbon dioxide and graphite, which is another form of carbon. The reaction is CO2 + C 2CO. In a closed circuit cooling system as used in PIPPA, graphite is initially removed into the gas phase until an equilibrium state is reached when no further removal occurs. This does not mean that the reaction ceases, because different parts of the reactor at different temperatures and under different intensities of irradiation cannot all be in equiUbrium with the particular steady state composition reached by the gas. Parts of the core will therefore lose graphite to the gas stream, resulting in a transfer of graphite from one part of the core to another. 

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