Why are narrow plates used for welding plate exchangers?
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Recently, it has been found that many welding plate exchanges use narrow plates with a width of 400/600, with multiple cores stacked together. Why is this? Is using a 1200 width more labor-saving?
Plate exchangers are relatively fragile; larger areas suffer more under pressure and are also prone to deformation due to thermal expansion
If it is too wide, the sheet will expand and deform, resulting in increased smoke resistance. Which company’s product is this? What measures are taken to prevent deformation?
Can larger panel sizes be achieved with anti-deformation supports? Thank you
This requires taking into account the temperature of the flue gas; an excessively wide range also has a significant impact on deformation. Deformation-resistant supports include corrugated plate types and supports with impact holes; it seems that the support type with impact holes does not yield very good results at present
Firstly, there is no pressure involved; it’s at atmospheric pressure. Secondly, thermal expansion can be managed using expansion joints. In the past, many large plates with a size of 1200 have also been used
The sheet metal will expand in the direction of the heat; deformation is impossible, as the temperature has not reached a level that could cause the stainless steel to deform
On the contrary, the plate expands toward the colder end, reducing the space of air at that cold end and thus increasing resistance
These all have expansion joints; deformation will occur in the direction of those expansion joints, so the plate won’t deform and narrow the flow channel, right?
Plate heat exchangers with large plates of several thousand square meters each can generally only be manufactured in a plate-and-shell design, such as the PACKINOX products. Otherwise, it cannot even withstand almost 0.1 MPa of gauge pressure. Sheet materials cannot be shaped using machining and pressing methods; for example, to process a corrugated sheet of 1200x2400 mm, an hydraulic press with a force of 300,000 tons would be required! Generally, only the explosive forming process can be used, making the processing relatively complex. The so-called plate-and-shell structure involves placing the welded plate assemblies, which have a rectangular box-like appearance, inside a pressure vessel tower. The tower is filled with gases such as nitrogen to create a pressure inside it that is higher than the pressure of the process materials or utility fluids contained within the plate assemblies; an appropriate margin is also left to ensure that, during operation and maintenance, the corrugated plate assemblies are always under external pressure greater than internal pressure, thereby preventing them from bursting.
The type you mentioned is a plate-and-shell heat exchanger; the other type needs to be able to withstand pressure. For those where the requirements for the flow channels aren’t very high, I’ve seen ones that can handle 10 kilograms of pressure, and they consist of a single heat exchange core. The images I’ve shared show designs for use in normal-pressure media. What I don’t quite understand is why they use narrow plates, such as those with a width of 600, to form the core; after all, wouldn’t it be simpler to use wider plates, like those with a width of 1200?