Tempered heat exchange systems

See also trouble shooting suggestions related to gas-liquid separators, furnaces, and pumps. 

Coolant or heating media is circulated in a closed loop vith controlled purge and addition of fresh media. The circuit may include a storage tank. 

For systems requiring more uniform temperature, to minimize local hot or cold spots for systems that tend to foul for systems that operate close to the freezing points for systems vith materials that thermally degrade easily. Example, batch polymerizers condensers for fatty acids or alcohols or for maleic anhydride. 

Use a circulating pump or ejector. For a pump, the system resistance is frictional with the typical head required of about 12 m. Often select a drive at 1200 rpm. 

Consider installing a check valve (and perhaps a fail-safe-closed valve) in the return line. 

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In this chapter in Section 3.1 we consider mechanical drives. In Sections 3.2 and 3.3 furnaces and exchangers, condensers and reboUers are considered followed by fluidized bed with coil in the bed, Section 3.4 and static mixers. Section 3.5. Direct contact systems are considered next liquid-liquid. Section 3.6 gas-liquid cooling towers. Section 3.7 gas-liquid quenchers. Section 3.8 gas-liquid condensers. Section 3.9, and gas-gas thermal wheels. Section 3.10. Heat loss to the atmosphere is described in Section 3.11. Refrigeration, steam generation and high temperature heat transfer fluids are presented in Sections 3.12 to 3.14, respectively. Tempered heat exchange systems are considered in Section 3.15. 

Thus far, our discussion of ensembles has been limited to closed systems, i.e., systems for which the mrmber of particles N is fixed. Now we consider an open system, i.e., a system that can exchange particles with its sirrroundings. The volume F of the system is fixed and the temperature is maintained at the temperature T by keeping the system in thermal contact with a large heat bath (at the temper-atiue T) with which it is able to exchange both energy and particles. Such a system is called an open, isothermal system. Its macroscopic state is called a grand canonical ensemble. 

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