Plate heat exchangers advantages

A further advantage of the plate heat exchanger is that the effective mean temperature difference is usually higher than with the tubular unit. Since the tubular is always a mixture of cross and contra-flow in multi-pass arrangements, substantial correction factors have to be applied to the log mean temperature difference (LMTD). In the plate... 

The plate heat exchanger can also be used for evaporation of highly viscous fluids when the evaporation occurs in plate or the liquid flashes after leaving the plate. Applications generally have been restricted to the soap and food industries. The advantage of these units is their ability to concentrate viscous fluids of up to 50 poise. 

It generally is considered that resistance due to fouling is lower with plate heat exchangers than with tubular units. This is the result of four advantages of plate-type exchangers ... 

The advantages and disadvantages of plate heat exchangers, compared with conventional shell and tube exchangers are listed below ... 

Gasketed plate heat exchangers are commonly used in food processing. What advantages does the design offer in such applications ... 

For certain applications multi-pass arrangements are used. When a plate heat exchanger is used instead of the tubular unit, boiling on the heating surfaces is avoided by increasing the static head using a line restriction between the plate pack and the separator. Compared with tubular units, lower circulation rates and reduced liquid retention times are important advantages. Plate-type units are discussed further in Section 14.7.7. 

APV, whose Paraflow plate heat exchanger is illustrated in Volume 1, Chapter 9, supply climbing and falling-film plate evaporators with evaporative capacities up to 10 kg/s. Such units offer the advantages of short contact and residence times and low liquor hold-up, and hence are widely used for the concentration of heat-sensitive materials. 

For some products it has been found advantageous to pressurise the plate heat exchanger, with an orifice or valve preventing boiling until the liquor enters the separator, in what is known as the APV Paraflash system. This is a special case of the forced circulation evaporator described earlier. 

Similarly to many other cases described above, the microchannel plate heat-exchanger technology offers advantages for simplification of the reactor. 

The application of plate heat-exchanger reactors carries advantages for all types of fuel processing reactors, namely for the reformer, the water-gas shift reactor and the... 

Figure 6.7 illustrates the advantage of coupling an exothermic reaction with an endothermic reaction performed on both sides of the wall of a plate heat-exchanger coated with catalyst. Temperature gradients are reduced and coupling of both reactions is only separated through a thin layer of metal sheet. 

These alloy coatings have advantages over tin in atmospheric exposure where there is heavy pollution by oxides of sulphur. They are cathodic to steel and anodic to copper. In industrial atmospheres, however, formation of a layer of lead sulphate seals pores and produces a generally stable surface and terne-plate has been used extensively as roofing sheet, especially in the USA. It is easily and effectively painted when additional protection is required. Copper heat exchangers in gas-fired water-heaters may be coated by hot dipping in 20% tin alloy . 

The indirect internal reformer (HR) is situated within the cell stack in separate reforming channels, where only the reforming reaction takes place. This concept features energetic coupling with the exothermic oxidation process. The main advantage is that no external heat exchanger is required, as the separator plate between HR and anode channel fulfills this function. The HR can be seen as an external reformer operating at fuel cell temperature. 

The tube-in-shell system (Figure 17-lB) is occasionally used. This configuration is very similar to a shell-and-tube heat exchanger. The membrane would be coated on a porous support. The main advantage of these systems is that they can be cleaned by passing sponge balls through the separators. The surface area per unit volume is more than for plate-and-frame but less than for spiral-wound. 

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