How Plate–and–Shell Heat Exchangers Work

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GESMEX GmbH

When Low Pressure Drop Counts

Exhaust gas streams, from which heat is to be recovered, frequently have high temperatures but low pressures. Accordingly, any heat exchangers in the gas duct must work at low pressure drops.

Gesmex provides a special heat exchanger for such cases: These “thermo-plate” units consist of pairs of plates which have been given a cushion-like form by spot welding and subsequent flaring under pressure. A heat transfer fluid flows through this narrow gap, while the exhaust gas flows through the wider channels between the plate pairs; the channel width can be varied to match the available pressure drop.

How HEat Exchangers Cope with Acid Condesate

Exhaust gases often contain sulphur or nitrogen oxides, which can produce acids on cooling and condensation. This can lead to corrosion of standard stainless steels (e.g. 1.4404), therefore Gesmex uses special alloys: Since thermo-plates are not embossed, they can be made from materials that would not be an option for conventional heat exchanger plates. Another advantage of thermo-plates are that the easy cleanability compared to standard corrugated plates.

Thermo-plates can be fitted into a separate shell or mounted directly in the exhaust gas duct. The TP Hex design, for example, has a cylindrical shell in which thermo-plates are fitted so as to lie parallel to the cylinder axis. The plates in the middle of the cylinder are wide, while those at the edges are narrow, so all the space inside the cylinder is used to best possible effect. ●

* The author heads Gesmex’s product management.

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