Big Mistakes to avoid in Plate Heat Exchanger calculation and material selection

Big Mistakes to avoid in Plate Heat Exchanger calculation and material selection

In the recent years use of Plate Heat Exchangers increased more than other type  Plate & Frame Heat Exchangers Market ,therefore it’s time to focus on mistakes to avoid in calculation and material selection.

 #1 Selection of connection size: typical nozzle velocity with water is 5.5 m/s. Major part of PHE design software switches to larger  size if it is higher.

Standard velocity in piping is 2-2.5 m/s so that size of connections is normally smaller and conic reductions are often required. Don’t select automatically PHE with connections same size of piping: double check velocity in nozzles!Heat-Exchanger-calculation

#2 Fouling Factor has been topic of discussion since years. PHE FF  must be 1/10 of Shell&Tube HEX FF as finally API 662 recommended. There is confusion among process engineers on FF to be used in PHE and often EPC Contractors data sheets are mentioning FF for S&T HE’s. Investigations demonstrated that these values are not giving good results in PHE since they often results in oversized units with premature fouling due to reduced velocity and turbolence.

#3 Plate pack size must be considered from maintenance standpoint. Many times to reduce impact cost of large frames, selection is a PHE with plates pack of 400 plates… easy to sell not to open and close!

#4 Diameter of channel plate required is often underestimated. Of course pressing depth of 2.2 mm is more efficient than a 4.4 mm, but if application is Oil & Gas in a refinery in the Middle East long life of PHE is a priority.

If solids or fibers are present, maybe a free flow plate is required  channel 11 mm

Heat-Exchanger

#5 Pressure drop is a driving force in PHE’s creating turbolence to get high U value. In calculation DP can dramatically change Heat Transfer Area required.

Furthermore Process Engineers specified sometimes DP for S&T HE’s while typical DP in PHE is 0.7 bar.

PHE

Before deliver calculation double check if DP could be increased!

#6 Plate material selection is related to fluids involved. Stainless steel is common material with water, but often Chloride level ppm is underestimated

Pipeline installation company,New roc phe,Heat exchanger maintenance contractors

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