During field commissioning, a common situation is encountered: two plate-and-frame fin heat exchangers with identical nominal parameters—one operates with a stable pressure drop, while the other triggers a pressure drop over-limit alarm shortly after being put into operation. Inspection of the medium flow rate and inlet temperature shows no significant deviation. The problem often lies in the matching of plate channel and pass arrangement during the selection stage. The pressure drop of a plate-and-frame fin heat exchanger is jointly determined by the plate corrugation angle, channel spacing, and number of passes. Looking only at the heat transfer area is not sufficient.
Medium temperature and chemical properties are the two basic inputs for gasket selection. Under operating conditions with a design temperature of 200°C and a design pressure of 1.6 MPa, commonly used nitrile gaskets are suitable for neutral oils and warm water, EPDM gaskets are suitable for hot water and steam condensate, and fluoroelastomer gaskets are suitable for some weakly corrosive media. During selection, the medium concentration, upper operating temperature limit, and whether aromatic hydrocarbons or ketone solvents are present should be checked. If necessary, compatibility data should be requested from the gasket supplier.
The heat transfer area is jointly determined by the heat load and the inlet/outlet temperature difference. Design and selection personnel can first obtain the heat load from the process, then calculate the logarithmic mean temperature difference based on the inlet and outlet temperatures on both sides, and divide the two to obtain the required area. Subsequently, the effective area per plate is determined according to the frame plate specifications to obtain the number of plates. If the medium temperature difference is small while the heat load is large, priority should be given to increasing the number of passes or adjusting the plate corrugation form rather than simply increasing the number of plates.
The BRF-140 model is suitable for medium-low pressure and medium temperature conditions with a design pressure of 1.6 MPa and a design temperature of 200°C. In retrofit and replacement projects, the orientation of the original pipeline connections, anchor dimensions, and nozzle diameters must be checked to avoid installation difficulties caused by space constraints. If the original equipment is an old-style plate-and-frame heat exchanger, it is also necessary during replacement to confirm whether the sealing gasket groove type of the new plates is consistent with the original spare parts, so as to reduce downtime.
