Page 83 - Process Equipment and Plant Design Principles and Practices by Subhabrata Ray Gargi Das
P. 83

80     Chapter 4 Shell and tube heat exchanger





               Table 4.2 Standard TEMA heat exchanger terminology/nomenclature.
               Tag in                                       Tag in
               Fig. 4.6     Terminology/Nomenclature        Fig. 4.6   Terminology/Nomenclature
                 1.    Stationary head e channel             21.    Floating head cover e external
                 2.    Stationary head e bonnet              22.    Floating tube sheet skirt
                 3.    Stationary head flange e channel or bonnet  23.  Packing box
                 4.    Channel cover                         24.    Packing
                 5.    Stationary head nozzle                25.    Packing gland
                 6.    Stationary tube sheet                 26.    Lantern ring
                 7.    Tubes                                 27.    Tie rods and spacers
                 8.    Shell                                 28.    Transverse baffles or support plates
                 9.    Shell cover                           29.    Impingement plate
                10.    Shell flange e stationary head end     30.    Longitudinal baffle
                11.    Shell flange e rear head end           31.    Pass partition
                12.    Shell nozzle                          32.    Vent connection
                13.    Shell cover flange                     33.    Drain connection
                14.    Expansion joint                       34.    Instrument connection
                15.    Floating tube sheet                   35.    Support saddle
                16.    Floating head cover                   36.    Lifting lug
                17.    Floating head cover flange             37.    Support bracket
                18.    Floating head backing device          38.    Weir
                19.    Split shear ring                      39.    Liquid level connection
                20.    Slip-on backing flange

              From (1988). Standards of Tubular Exchanger Manufacturers Association (7th ed.), Table Ne2, 9: Tubular Exchanger Manufac-
              turers Association, Inc. All rights reserved.


             4.3 Design considerations
             As with double-pipe exchangers, shell and tube exchangers are also designed with specified pressure
             drop constraints on both the streams. However, due to greater variety and complexity of shell and tube
             configurations, there are more design variables to be considered. In addition, since the primary flow
             pattern in the shell is both transverse and parallel to the tubes, the flow in reality is tortuous and more
             complex. This arises because part of the fluid bypasses the main heat transfer surface due to various
             leakages namely tube to baffle leakage stream, tube bundle to shell bypass stream and baffle to shell
             leakage stream. The amount of these leakage streams can be substantial which may decrease the main
             stream flowing across the tube bundle to less than 50% of the total shell-side flow. Presence of these
             bypass streams complicates the analysis of shell-side heat transfer and pressure drop. Thus, design of
   78   79   80   81   82   83   84   85   86   87   88