Sizing shell/tube heat exchangers

If exchangers are countercurrent devices, then the number of units equals the number of shells, providing indithdual shells do not exceed some practical upper size limit. If, however, equipment is used that is not completely countercurrent, as with the 1-2 shell and tube heat exchanger, then... 

Heat exchangers used in gas production facilities are shell-and-tube, double-pipe, plate-and-frame, bath-type, forced-air, or direct-fired. In this chapter we will discuss the basic concepts for sizing and selecting heat exchangers. This is just a brief overview of this complex subject and is meant to provide the reader with a basis upon which to discuss specific sizing and selection details with heat exchange experts in engineering companies and with vendors. 

To actually build a commercial-sized side entry reactor is another problem. Chem. Eng. News (1997) reports on how this was cleverly done by using a reactor somewhat like a shell-and-tube heat exchanger which used porous walled tubes. 

The standard length of tubes in a shell-and-tube heat exchanger is 8, 12, or 16 ft, and these standard-length tubes are available in a variety of different diameters and wall thickness. Exchangers with small-diameter tubes are less expensive per square foot of heat-transfer surface than those with large-diameter tubes, because a given surface can be fitted into a smaller shell diameter however, the small-diameter tubes are more difficult to clean. A tube diameter of or 1 in. OD is the most common size, but outside diameters ranging from f to lj in. are found in many industrial installations. 

The type of heat exchanger to be selected depends primarily on the type of fluids involved, the size and weight limitations, and the presence of any phase-change pmetsses, For example, a heat exchanger is suitable to cool a liquid by a gas it the surface area on the gas side is many limes that on the liquid side. On tile other hand, a plate or shell-and-tube heat exchanger is very suitable for cooling a liquid by another liquid. 

Process Design of a Shell-and-Tube Heat Exchanger 204 Sizing a Condenser for a Mixture by the Silver-Bell-Ghatly Method 207... 

A thermal expansion joint may be installed on the exchanger shell. As plant size increases, the shell-and-tube heat exchanger becomes more cost effective and will be the exchanger of choice. At intermediate sizes, both types must be evaluated for process and economic reasons. 

Table 4.6 Calculation Procedure for Sizing Shell-and-Tube Heat Exchangers ...

The small size of hollow fiber allows high surface area to volume ratios in hollow fiber modules ranging from 500 to 10,000 m /m in comparison with 500 and 1000 m /m for plate and frame and spiral wound modules, respectively. The majority of hollow fiber modules are assembled as shell and tube heat exchanger (Fig. 4). Flow can occur in the exterior (shell side) or the interior (lumen) of the fibers in a counter-current or cocurrent manner. Shell-side flow can be introduced or collected using side ports in the external casing (Fig. 4A) or a central tube in the middle of the module to create radial flow across the fiber bundle... 

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