The required heat duty, film coefficients, conductivity, etc. for a shelland-tube heat exchanger can be calculated using the procedures in Heat Transfer Theory, Approximate U-values are given in Table 2-8. In the basic heat transfer equation it is necessary to use the log mean temperature difference. In Equation 2-4 it was assumed that the two …
Read More…Category: Shell and Tube Exchangers
TEMA Glasses and Tube Materials
TEMA standards provide for two classes of shell and tube exchanger qualities. Class C is the less stringent and is typically used in onshore applications and where the temperature is above ~20°F. Class R is normally used offshore and in cold temperature service. Table 3-2 shows the most important differences between a Class R and …
Read More…Heat Exchanger Placement of Fluid
The question always comes up of which fluid to put in the tubes and which fluid to put in the shell. Consider placing a fluid through the tubes when: 1. Special alloy materials are required for corrosion control and high temperatures. 2. Fluid is at high pressures. 3. Fluid contains vapors and non-condensable gases. 4. …
Read More…Heat Exchanger Selection of Types
In selecting an exchanger, one must know the advantages and disadvantages of each type. The three basic types of shell-and-tube exchangers are fixed tube sheet, floating head, and U-tube. Table 3-1 summarizes the comparison between these three exchangers.
Read More…Heat Exchangers Classification
In addition to the type description code there is also a shorthand that is used for classifying heat exchangers. The first element of the shorthand is the nominal diameter, which is the inside diameter of the shell in inches, rounded off to the nearest integer. For kettle reboilers and chillers (remember the kettle has a …
Read More…Heat Exchanger Options
There are many different arrangements of the shells, tubes and baffles in heat exchangers. Figure 3-6 is a list of TEMA standard classifications for heat exchangers, which helps to describe the various options. Theseare best understood in conjunction with the example configurations given in Figures 3-7 through 3-9. The first letter designates the front end …
Read More…Heat Exchanger Shells
Shells up to 24-in. OD are fabricated from pipe using standard pipe nominal diameters. Standard pipe diameters and wall thicknesses are given in Volume 1, Tables 9-5 and 9-9 (1st edition: 9-4 and 9-7), Shells larger than 24-in. in diameter are fabricated by rolling steel plate. The wall thickness of the pipe or plate used …
Read More…Heat Exchanger Tube Pitch
Tube holes cannot be drilled very close together, since this may structually weaken the tube sheet. The shortest distance between two adjacent tube holes is called the “clearance.” Tubes are laid out in either square or triangular patterns as shown in Figure 3-5. The advantage of square pitch is that the tubes are accessible for …
Read More…Heat Exchanger Tubes
Heat-exchanger tubes should not be confused with steel pipe or other types of pipe that are extruded to steel pipe sizes. The outside diameter of heat-exchanger tubes is the actual outside diameter in inches within a very strict tolerance. Heat-exchanger tubes are available in a variety of metals including steel, copper, brass, 70-30 copper-nickel, aluminum …
Read More…Heat Exchanger Baffles
Shell-and-tube exchangers contain several types of baffles to help direct the flow of both tube-side and shell-side fluids. Pass partition baffles force the fluid to flow through several groups of parallel tubes. Each of these groups of tubes is called a “pass,” since it passes the fluid from one head to another. By adding pass …
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