Plate exchanger construction

A spiral plate exchanger is illustrated in Figure 9.90 in which two fluids flow through the channels formed between the spiral plates. With this form of construction the velocity may be as high as 2.1 m/s and overall transfer coefficients of 2.8 kW/m2 K are frequently obtained. The size can therefore be kept relatively small and the cost becomes comparable or even less than that of shell and tube units, particularly when they are fabricated from alloy steels. 

Fig. 9. Plate heat exchangers (a) plate—frame heat exchanger when hot fluid from the heat source enters the heat exchanger through connections in the stationary frame plate and is channeled over one side of each plate. Cold fluid enters through different frame plate connections and flows on the other side of each plate in a direction opposite to the hot fluid direction. Courtesy of Bell Gosset. (b) Limco model 6502 plate—fin heat exchanger having compact plate—fin aluminum brazed liquid-to-aii construction. The brazed plate—fin construction provides the most efficient heat-exchanger system in terms of size,...

Kumar, H. (1984) Inst Ghent Eng Syni Ser. No. 86, 1275. The plate heat exchanger Construction and design. 

Instruments for the in-situ analysis of thin-layer plates are constructed according to the following principle (Fig. 1). The light from various exchangeable sources passes a monochromator or a monochromatic filter. The monochromatic light falls slitshaped or spot-shaped onto the thin-layer plate to be measured the latter is positioned on a movable plate table. The light which is either reflected, transmitted through the plate or emitted in the form of fluorescence finally reaches a detector. 

Plate-and-frame coolers have made some inroads into this application. These will be much smaller than the typical shell-and-tube coolers, at the expense of a greater pressure drop. Titanium plates are necessary, and welded construction of the plates is highly recommended [16]. Plate-and-frame units will probably become more common as the increasing use of the newest membrane cells allows operating pressures to increase. Few units are found today in sizes above 100 tpd chlorine. Section 9.3.2.4 on caustic cooling briefly discusses the general characteristics of plate exchangers. 

The vessel geometries can be broadly divided into plate- and shell-type configurations. The plate-type construction used in flat covers (closures for pressure vessels and heat exchangers) resists pressure in bending, while the shell-type s membrane action operates in a fashion analogous to what happens in balloons under pressure. Generally speaking the shell-type construction is the preferred form because it requires less thickness (as can be demonstrated analytically) and therefore less material is required for its manufacture. Shell-type pressure components such as pressure vessel and... 

Cowan, C. T, Choosing Materials of Construction for Plate Heat Exchangers, Chem. ng ,June 9 (1975) p. 100. 

When mild steel construction is acceptable and when a closer temperature approach is not required, the tubular heat exchanger will often be the most economic solution since the plate heat exchanger is rarely made in mild steel. 

Plate and frame exchangers are suited to high sanitation services, and are 25-50% cheaper in stainless construction than shell-and-tube units. 

Figure 1.26 Large-capacity heat exchanger, e g. for use on oil platforms, constructed from diffusion-bonded plate stacks comprising a vast number of millimeter-sized channels. This apparatus was manufactured by Heatric (Poole, UK).

Different from sole combinations of micro devices, this refers to a total system with many functional elements and flow-distribution and, recollecting zones, typically composed of 2-D plate-type architecture. Each of these plates usually has a separate fimction, comprising imit operations and reaction. Frequently, micro mixing and micro heat exchange fimctions and corresponding elements are employed. Often, the system can be composed of different elements resulting in different process flow combinations. Such an approach may be termed a construction kit. 

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