Plate-type heat exchangers

Recuperative systems use conventional shell-and-tube or plate-type heat exchangers. Plate-type units are reported to be more economical for low to moderate temperature service (to about 1,000°F), while shell and tube are preferable for higher temperatures (van der Vaart et al., 1990). Because of the temperature limitations of conventional heat exchangers, recuperative systems are normally designed to heat the feed gas to no more than l,200°F. A conventional. shell-and-tube recuperative system can typically recover 60 to 80% of the available energy. 

Fig. 10. Plate-—coil heat exchangers. Plate—coil is a very efficient and versatile prime surface-type heat exchanger.

Figure 3.11 Photograph of the multi-plate stack reactor, originally designed as a counter-flow heat exchanger this type of reactor was also used for periodic operation [13].

Plate-fin heat exchangers. Another type of plate heat exchanger is the plate-fin heat exchanger. This is illustrated in Figure 15.17. The plate-fin heat exchanger consists of a series of flat plates, between which is a matrix formed... 

Type of heat exchanger Plate and frame (gaskets) Fully welded plate (Alfarex) Brazed plate Spiral Brazed plate-fin Diffusion- bonded plate-fin Printed circuit Polymer (e.g. channel- plate) Chart-flo... 

Shell Sizes Heat-exchanger shells are generally made from standard-wall steel pipe in sizes up to 305-mm (12-in) diameter from 9.5-mm (ys-in) wall pipe in sizes from 356 to 610 mm (14 to 24 in) and from steel plate rolled at discrete intervals in larger sizes. Clearances between the outer tube limit and the shell are discussed elsewhere in connection with the different types of construc tion. 

There are two major types gasketed and welded-plate heat exchangers. Each shall be discussed individually. 

When the solute has a large heat of solution or when the feed gas contains high percentages of the solute, one should consider the use of internal coohng coils or intermediate external heat exchangers in a plate-type tower to remove the heat of absorption. In a packed tower, one could consider the use of multiple packed sections with intermediate hquid-withdrawal points so that me hquid coiild be cooled by external heat exchange. 

Other types of plate-and-frame heat exchangers are double-wall-plate exchangers, welded-plate exchangers, wide-gap-plate exchangers, and brazed-plate exchangers. Each type is briefly described below. 

This type of filter allows pressurized filtration of a slurry mixture to remove solids. A set of filter plates is sandwiched together in series with a configuration similar to the plates on a plate-and-frame heat exchanger. After the plates are compressed... 

A common type of heat exchanger used in industrial ventilation is the plate fin-and-tube heat exchanger (Fig. 9.7). Liquid or gas flows in the tubes, with a gas or a liquid circulating outside the tubes between the plates. 

Plate-type design (space heaters) Type of heat exchanger characterized by a substantial proportion of its heat output being by way of radiant energy. 

Heat exchangers used in gas production facilities are shell-and-tube, double-pipe, plate-and-frame, bath-type, forced-air, or direct-fired. In this chapter we will discuss the basic concepts for sizing and selecting heat exchangers. This is just a brief overview of this complex subject and is meant to provide the reader with a basis upon which to discuss specific sizing and selection details with heat exchange experts in engineering companies and with vendors. 

Various designs of liquid/liquid heat exchanger are widely used. Choice is partly influenced by the cleanliness of the liquids and the need for regular cleaning. A compact and commonly used type is the plate heat exchanger. 

Plates are available with effective heat transfer area from 0.03 to 3.5 m and up to 700 can be contained within the frame of the largest plate-type heat exchanger, providing over 2400 m of surface area. Flow ports and associated pipework are sized in proportion to the plate area and control the maximum liquid throughput. 

One particularly important feature of the plate heat exchanger is that the turbulence induced by the troughs reduces the Reynolds number at which the flow becomes laminar. If the characteristic length dimension in the Reynolds number is taken as twice the average gap between plates, the Re number at which the flow becomes laminar varies from about 100 to 400, according to the type of plate. 

Bypassing in a plate-type exchanger is less of a problem and more use is made of the flow separation which occurs over the plate troughs since the reattachment point on the plate gives rise to an area of very high heat transfer. 

Most plate heat exchanger designs fall into the viscous flow range. Considering only Newtonian fluids since most chemical duties fall into this category, in laminar ducted flow the flow can be said to be one of three types ... 

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