Principles And Applications

The Paraflow is the original plate-type heat exchanger designed by APV to provide maximum efficiency and cost-effectiveness in handling thermal duties while minimizing maintenance downtime and floor space requirements.

Frame, Plates, and Gaskets

The Paraflow plate heat exchanger as shown in Figure 1 consists of a stationary head and end support connected

Nozzles

Tie bar

Bottom carrying bar

End support

Head

Moveable follower

Figure 1. The APV CREPACO Paraflow plate heat exchanger.

Nozzles

Tie bar

Bottom carrying bar

Moveable follower

Top carrying bar

End support

Head

Figure 1. The APV CREPACO Paraflow plate heat exchanger.

alternative metals which, with various types of flanged or sanitary connections, form the inlet and outlet nozzles. By using intermediate connector plates as shown in Figure 2, units can be divided into separate sections to accommodate multiple duties within a single frame.

The closely spaced metal heat-transfer plates have troughs or corrugations that induce turbulence to the liquids flowing as a thin stream between the plates (Fig. 3).

The plates have corner ports which in the complete plate pack form a manifold for even fluid distribution to the individual plate passages (Fig. 4).

The seal between the plates is established by a peripheral gasket that also separates the thruport and flow areas with a double barrier. The interspace is vented to atmosphere to prevent cross-contamination in the rare event of leakage (Fig. 5).

As an exclusive feature, Paraflow heat-exchanger plates have interlocking gaskets in which upstanding lugs and scallops are sited intermittently around the outside edges. These scallops ensure that there are no unsupported portions of the gaskets and, in combination with the patented form of pressed groove, provide mechanical plate-to-plate support for the sealing system. The upstanding lugs (Fig. 6) maintain plate alignment in the Paraflow during pack closure and operation. The groove form provides 100% peripheral support of the gasket, leaving none of the material exposed to the outside. In addition, the gasket-groove design minimizes gasket exposure to the process liquid.

by a top carrying bar and bottom guide rail. These form a rigid frame that supports the plates and moveable follower. In most units, plates are securely compressed between the head the follower by means of tie bars on either side of the exchanger. In a few models, central tightening spindles working against a reinforced end support are used for compression. When Paraflows are opened, the follower moves easily along the top bar with the aid of a bearing supported roller to allow full access to each individual plate.

With the exception of some sanitary models that are clad with stainless steel, Paraflow frames are fabricated of carbon steel and are finished in chemical-resistant epoxy paint. Frame ports accept bushings of stainless steel or

Plate Arrangement

Comparison of Paraflow plate arrangement to the tube and shell-side arrangement in a shell and tube exchanger is charted in Fig. 7. Essentially, the number of passes on the tube side of a tubular unit can be compared with the number of passes on a plate heat exchanger. The number of tubes per pass also can be equated with the number of passages per pass for the Paraflow. However, the comparison with the shell side usually is more difficult since with a Paraflow, the total number of passages available for the flow of one fluid must equal those available for the other fluid to within ± 1. The number of cross passes rt\

Second stage cooling liquid o

| First stage _ cooling liquid

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