Dowtherm heater

FIG. H-40 16,000 kW Dowtherm heater in west coast U.S. chemical plant. (Source Armstrong Engineering Associates.)... 

Heater Imparts sensible heat to a liquid or a gas by means of condensing steam or Dowtherm. 

Heat-transfer-fluid heaters maintain the temperature of a circulating liquid heating medium (e.g., a paraffinic hydrocarbon mixture, a Dowtherm, or a molten salt) at a level that may exceed 673 K (750°F). 

Heater Heats fluid (adds sensible heat) but does not vaporize except for effect of temperature on vapor pressure. Heating medium is usually steam, Dowtherm, or similar fluid that condenses at pressure and temperature desired, imparting its latent heat to fluid (gas or liquid). 

Afo( The fluids given a only examples, i.e., for heat exchangers brine as welt ss water tor heaters, Dowtherm as well as steam fw codiers, ammoaia instead of Freon are understood to apply also. 

Fired heaters are available for providing heat transfer media of the types described in Section 13.2, including hot water, steam, mineral oils, silicon oils, chlorinated diphenyls (Dowtherm A), and molten (fused) salts. Fired heaters are also used as reactors, such as reformers in petroleum refineries and for pyrolysis of organic chemicals. Purchase costs for these specific types of fired heaters, based on heat duty, are presented in Table 16.32. 

In the process to produce acetone from isopropyl alcohol (see process description on CD), heat is supplied to the endothermic reaction using a Dowtherm A (or molten salt) loop and a fired heater. 

Indirect fluid heater Very useful for high-pressure or corrosive fluids where special metallurgy (i.e., corrosion-resistant metals) can be used in smaller, less costly containment than traditional shellside boiling. Heating medium (steam/ dowtherm/electric, etc.) heats an intermediate bath of water/NH3/Therminol or similar heat-transfer fluid that then heats a second coil at much lower cost than shellside heating or boiling. (See Fig. V-8.)... 

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