Page 22 - Applied Process Design For Chemical And Petrochemical Plants Volume III

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12 Applied Process Design for Chemical and Petrochemical Plants

Figure 10-4D. Vertical longitudinal finned-tube tank heater, which is Figure 10-4E. Longitudinal finned-tube tank suction direct line heater.
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used in multiple assemblies when required. (Used by permission: (Used by permission: Brown Fintube Co., A Koch Engineering Co.,
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Brown Fintube Co., A Koch Engineering Co., Bul. 4—5.) Bul. 4—5.)

Figure 10-4F(1). Single concentric corrugated tube in single corrugated shell. (Used by permission: APV Heat Transfer Technologies.)

Figure 10-4F(2). Multicorrugated tubes in single shell. (Used by permission: APV Heat Transfer Technologies.)

This tube is useful when the shell-side fluid is not com- monel, nickel, stainless steel, alloy steels, various brasses, etc.
patible with the material needed for the tube-side fluid, or From these combinations most process conditions can be sat-
vice versa. The thicknesses of the two different wall materials isfied. Combinations such as steel outside and admiralty or
do not have to be the same. As a general rule, 18 ga is about cupro-nickel inside are used in ammonia condensers cooled
as thin as either tube should be, although thinner gages are with water in the tubes. Tubes of steel outside and cupro-
available. In establishing the gage thickness for each com- nickel inside are used in many process condensers using sea
ponent of the tube, the corrosion rate of the material should water. These tubes can be bent for U-bundles without loss of
be about equal for the inside and outside, and the wall thick- effective heat transfer. However, care must be used, such as
ness should still withstand the pressure and temperature by bending sand-filled or on a mandrel. The usual minimum
conditions after a reasonable service life. radius of the bend for copper-alloy—steel type duplex tube is
More than 100 material combinations exist for these three times the O.D. of the tube. Sharper bends can be made
tubes. A few materials suitable for the inside or outside of the by localized heating; however, the tube should be specified at
tube include copper, steel, cupro-nickel, aluminum, lead, the time of purchase for these conditions.