Fixed-head heat exchangers

Suppose the cost for a fixed-head heat exchanger constructed of 316 stainless steel operating at 300-600 psi is to be estimated. The base case is a carbon steel, floating-head exchanger operating at 100 psi of area A. For such operation (Kuri and Corripio 1984), the base cost is... 

Because there appears to be no cost data for chlorinators, we will approximate the cost by using a fixed-tube, shell-and-tube heat exchanger. From Table 2.9, the cost of a 1,000 floating-head heat exchanger in January 1990 was 14,000. As indicated in Table 2.4.1, each chlorinator requires 330 fr of surface area. 

Many configurations of shell-and-tube heat exchangers are available, with Figure 13.8a being the simplest. It is a one-tube-pass, one-shell-pass, fixed (stationary)-head heat exchanger. 

FIG. 11-36 Heat-exchanger-component nomenclature, (a) Internal-floating-head exchanger (with floating-head hacking device). Type AES. (h) Fixed-tiihe-sheet exchanger. Type BEM. (Standard of Tiihiilar Exchanger Manufacturers Association, 6th ed., 1978. )... 

The tube-plates (tube-sheets) in shell and tube heat exchangers support the tubes, and separate the shell and tube side fluids (see Chapter 12). One side is subject to the shell-side pressure and the other the tube-side pressure. The plates must be designed to support the maximum differential pressure that is likely to occur. Radial and tangential bending stresses will be induced in the plate by the pressure load and, for fixed-head exchangers, by the load due to the differential expansion of the shell and tubes. 

The design type refers to variations in equipment configuration (e.g., fixed head versus floating head in a heat exchanger). The adjustment for material of construction is used principally to account for the use of alloy steel instead of carbon steel. The pressure rating factor allows adjusting costs for pressures other than the refer-... 

FIGURE 3 Sectional view of a typical fixed tubesheet shell-and-tube heat exchanger (A) tubes (B) tubesheets (C) shell (D) tube-side channel and nozzles (E) channel cover (F) pass divider plate (G) stationary rear head (bonnet type) (H) tube support plates (or baffles). 

Figure 13.8 Shell-and-tube heat exchangers (a) 1-1 fixed head (b) segmental baffles (c) 1-2 fixed head (d) 1-2 floating head.

The 1-1 fixed-head shell-and-tube heat exchanger of Figure 13.8a has several limitations ... 

Other mappings can be altered in a similar fashion. For example, for the condenser, the mapping is altered from a shell-and-tube heat exchanger with a fixed tube sheet to one with a floating head. When the desired changes are completed, press OK to continue and wait for the equipment mapping and sizing to be completed. 

For shdl and tube heat exchange Numerous related topics including evaporation Section 4.1, distillation. Section 4.2, crystallization Section 4.6, freeze concentration Section 4.3, melt crystallization. Section 4.4, PFTR reactors Sections 6.5-6.12. Approach temperature 5 to 8°C use 0.4 THTU/pass design so that the total pressure drop on the liquid side is about 70 kPa. Allow 4 velocity heads pressure drop for each pass in a multipass system. Put inside the tubes the more corrosive, higher pressure, dirtier, hotter and more viscous fluids. Recommended liquid velocities 1 to 1.5 m/s with maximum velocity increasing as more exotic alloys used. Use triangular pitch for all fixed tube sheet and for steam condensing on the shell side. Try U = 0.5 kW/m °C for water/liquid U = 0.3 kW/m °C for hydrocarbon/hydrocarbon U = 0.03 kW/m °C for gas/ liquid and 0.03 kW/m °C for gas/gas. 

Shell-and-tube heat exchangers can be broken down into (1) pipe-coil (2) double-pipe (3) fixed-head, single-pass (4) fixed-head, multipass (5) floating-head, multipass (U-tube) (6) kettle reboiler (7) thermosyphon reboiler and (8) shell nomenclature. These devices can be mounted vertically or horizontally. 

The fixed capital investment is equal to the total module cost of the compressor (centrifugal), g the compressor drive (electric), and heat exchanger (shell-and-tube, floating head). The... 

These baffles are built into the head and return ends of an exchanger to direct the fluid through the tubes at the proper relative position in the bundle for good heat transfer as well as for fixing velocity in the tubes, see Figures 10-lD and 10-3. 

The three most common types of shell-and-tube exchangers are fixed tubesheet design, U-tube design, and the floating head type. In all types, the front-end head is stationary, while the rear-end head could be either stationary or floating depending upon the thermal stresses in the shell, tube, or tubesheet due to temperature differences as a result of heat transfer. 

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