In a plate heat exchanger, the liquid to be processed is pumped into one side of the plates while the liquid facilitating heating and cooling is pumped into the other.
Photos courtesy of by Trelleborg AB

With energy conservation a major focus for manufacturers, the demand for plate heat exchangers is booming, according to Trelleborg AB in Trelleborg, Sweden. As fundamental parts of many production processes, the exchangers allow the use of what otherwise would be wasted heat.

“Heat is generated in all types of processing,” says Jon Cutler, Trelleborg sealing solutions material development manager for plate heat exchanger gaskets. “In less environmentally aware times, heat was just pumped out of the processing system and wasted. That wasn’t good for energy conservation or the atmosphere.”

Today, however, fewer companies waste the heat their processes generate. Plate heat exchangers are key to capturing process heat and effectively reusing it, either within the processing system itself or by diverting the energy elsewhere. The applications are countless, according to Trelleborg. Originally, the heat exchangers were used in the sterilization and pasteurization of dairy products, mainly milk. Now, however, they are used in almost every processing plant, as well as on ships and to feed heating systems for buildings.

A key element of plate heat exchangers is that both liquids come into contact with the maximum plate surface area to rapidly exchange heat from one liquid to the other.

“In power stations, PHEs [plate heat exchangers] make it possible for the steam used for energy production to be diverted into heating offices and homes,” Cutler says. “In processing plants, PHEs ensure efficient energy use by recycling heat. When they are employed within a system, the overall heat loss can be extremely low.”

The plates within a plate heat exchanger are sealed with rubber gaskets, preventing the two liquids within the unit from leaking out or mixing. Gaskets are critical elements within the exchanger and potentially their weakest link.

Sealing conditions are demanding. Temperature extremes range from -49 to 392°F (-45 to 200°C) and many chemicals are aggressive, says Trelleborg's Jonas Jerleus, sealing solutions global PHE coordinator. As the liquids are pushed through a large exchanger with as many as 200 plates, the pressures also are high, Jerleus says.

Cutler notes that Trelleborg, a maker of gaskets for more than 25 years, has invested heavily in research and development to maximize gasket life and optimize design. “If there is one thing we pride ourselves on more than any other,” he says, “it is the initial fit of our gaskets.”