Tubing types

The shell-and-tube heat exchanger is probably the most common type of exchanger used in the chemical and process industries. The simplest type of such device is the 1-1 design (1 shell pass, 1 tube pass), as illustrated in Fig. 7.7a. Of all shell-and-tube types, this comes closest to pure countercurrent flow and is designed using the basic coimtercurrent equation ... 

As probes must be manufactured individually for each different tube type, the probe development is an important factor for the economic use of the method. The classical procedure of probe development is a combination of experience and experiment. The new probe design is based on the experience with already manufactured probes. For an evaluation of the new design the probe must be manufactured. If the probe design is complicated, for example due to dual exciter coil arrangement or segmented differential detector coil systems, the costs of the development can be very high. Therefore a method for the pre-calculation of the probe performance is extremely useful. 

Round-bottomed flasks (Fig. 22(A)) of various sizes and having necksof various lengths and widths. They can be closed with stoppers (Fig. 22(B)), or fitted with any of the following units reflux air-condensers (Fig. 22(C)) or water condensers (Fig. 22(D)) distillation heads, of the simple knee-tube type (Fig. 22(E)), or with a vertical joint (Fig. 22(F)) for thermometers, etc., or with... 

Oxidation Step. A review of mechanistic studies of partial oxidation of propylene has appeared (58). The oxidation process flow sheet (Fig. 2) shows equipment and typical operating conditions. The reactors are of the fixed-bed shell-and-tube type (about 3—5 mlong and 2.5 cm in diameter) with a molten salt coolant on the shell side. The tubes are packed with catalyst, a small amount of inert material at the top serving as a preheater section for the feed gases. Vaporized propylene is mixed with steam and ak and fed to the first-stage reactor. The feed composition is typically 5—7% propylene, 10—30%... 

Fig. 9. Tube-type continuous-flow rotor. Courtesy of SorvaE.

Heat Recovery Equipment. Factors that limit heat recovery appHcations are corrosion, fouling, safety, and cost of heat-exchange surface. Most heat interchange utilizes sheU and tube-type units because of the mgged constmction, ease of mechanical cleaning, and ease of fabrication in a variety of materials. However, there is a rich assortment of other heat exchangers. Examples found in chemical plants in special appHcations include the foUowing. 

TABLE 10-31 Copper Water Tubing—Types K, L, M (ASTM B88) ... 

TEMA-style shell-and-tube-type exchangers constitute the bulk of the unfired heat-transfer equipment in chemical-process plants, although increasing emphasis has been developing in other designs. These exchangers are illustrated in Fig. 11-35, and their features are summarized i n Table 11-11. 

TABLE 11-11 Features of TEMA Shell-and-Tube-Type Exchangers... 

Performance testing of heat exchangers is described in the American Institute of Chemical Engineers Standard Testing Procedure for Heat Exchangers, Sec. 1. Sensible Heat Transfer in SheU-and-Tube-Type Equipment. ... 

Another growing field is that of nonmetallic heat exchanger designs which typically are of the shell and tube or coiled-tubing type. The graphite units were previously discussed but numerous other materi- s are available. The materials include Teflon, PVDF, glass, ceramic, and others as the need arises. 

These shell-and-tube-type exchangers are similar to the Teflon designs but have some mechanical advantages over Teflon units. First... 

FIG. 11 -58 Stationary vertical-tube type of indirect beat-transfer equipment with divided solids inside tubes, laminar solids flow and steady-state beat conditions. 

Large vapor-hqiiid disengaging area—submerged-tube type... 

Entrainment losses by flashing are frequently encountered in an evaporator. If the feed is above the boiling point and is introduced above or only a short distance below the liquid level, entrainment losses may be excessive. This can occur in a snort-tube-type evaporator if the feed is introduced at only one point below the lower tube... 

Tube-type. These separators are typically divided into two sections (I) precharging and (2) separation. The precharging section is designed to create or enhance the charge difference between particles to be separated (typically by some form of contact mechanism or external pretreatment to render one constituent positive or negative in comparison to the other materials present. The separation section consists of two vertical walls of tubes opposing each other. Each tube... 

In a tube type ESP, the tubes are 8-25 cm in diameter and 1-4 m long. They are arranged vertically in banks with the central wires, about 2 mm in diameter, suspended in the center with tension weights at the bottom. Many innovations, including square, triangular, and barbed wires, are used by different manufacturers. 

Common to all air cooled heat exchangers is the tube, through which the process fluid flows. To compensate for the poor heat transfer properties of air, which flows across the outside of the tube, and to reduce the overall dimensions of the heat exchanger, external fins are added to the outside of the tube. A wide variety of finned tube types are available for use in air cooled exchangers. These vary in geometry, materials, and methods of construction, which affect both air side thermal performance and air side pressure drop. In addition, particular... 

Evaporators, Horizontal-Tube Type - The basic horizontal-tube evaporator is illustrated in Figure 12. The body of this evaporator is the liquor compartment and is in the form of a vertical cylinder. It is closed, top and bottom, with dished heads, although the bottom may be conical. The lower body ring is provided on opposite sides with steam compartments, closed on the outside by cover plates and on the inside by tube sheets. Between these tube sheets are fastened a number of horizontal tubes. The two steam chests with their connecting mbes form the steam compartment, and the tube wall heating surface. Steam is introduced into one steam chest and as it flows through the tubes it washes non-condensed gases and condensate ahead of it, so that these are withdrawn from the opposite steam chest. 

Figure 9 shows the details of a typical horizontal tube-type ozone generator. This unit is preferred for larger systems. Water-cooled plate units are often used in smaller operations. However, these require considerably more floor space per unit of output than the tube-type units. The air-cooled Lowther plate type is a relatively new design. It has the potential for simplifying the use of ozone-generating equipment. However, it has had only limited operating experience in water treatment facilities. 

Figure 9. Horizontal tube-type ozone genrator.

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