Equipment costs (16): AIR-COOLED EXCHANGERS
15 Jan 2000
Continuing our series on budget cost estimates for specific plant equipment items, Costimator this month turns his attention to air-cooled heat exchangers.
Air-cooled exchangers can be considered as an alternative to water-cooled units when cooling water is scarce or expensive, or when the costs of closed circuit cooling water systems are high. Clearly, the effectiveness of air cooling diminishes with increasing ambient temperatures.
Used for either cooling or condensing, typically air-cooled exchangers are constructed from banks of finned tubes over which air is blown (forced draught) or drawn (induced draught) by fans mounted below or above the tube banks.
The data presented in Figure 16 cover the costs of a wide range of sizes of air coolers. The data are averaged over a wide spectrum of operating conditions and tube length. In Table 16 we quote conversion factors for six different materials of construction. Thus, for example, an exchanger that might need to be constructed from 316 stainless steel to cope with the properties of a particular process stream, would cost 2.85 times its carbon steel equivalent.
{{Table 16: Materials factors for air-cooled heat exchangers
Material of construction Factor
Carbon steel 1.00410 stainless steel 2.00304 stainless steel 2.50316 stainless steel 2.85310 stainless steel 3.30Monel 3.50}}
