During a field inspection, an O&M technician asked: For a BRF-60 plate-frame fin heat exchanger, the outlet temperature gradually decreases during operation, but the primary-side and secondary-side flow rates are both normal. What could be the cause? Such problems are relatively common in HVAC, district heating, and medium-temperature heat exchange sections of chemical processes. The following answers several typical questions from a product technical perspective.
Q: What factors are usually related to an increase in fin-side pressure drop?
A: Dust accumulation, scaling, or foreign matter blockage between fins are common causes. The BRF-60 uses a plate-frame structure, and the fin channels are relatively narrow. If the medium contains dust or tends to scale, the flow area will decrease after long-term operation. It is recommended to judge based on the inlet and outlet differential pressure gauges. When the differential pressure continues to rise, arrange a shutdown inspection and clean with low-pressure water or compressed air along the fin direction to avoid damaging the fins.
Q: How should the fin material be selected according to medium corrosiveness?
A: It is necessary to check the medium composition, concentration, and operating temperature. Carbon steel is suitable for weakly corrosive conditions such as general HVAC circulating water; stainless steel 304 can be used for medium-temperature heat exchange in most chemical processes; if the medium contains chloride ions at high concentration, 316L stainless steel should be selected. During selection, attention should also be paid to the risk of galvanic corrosion at the connection between the fins and the plate frame, and if necessary, use the same material or insulation measures.
Q: What dimensions need to be confirmed for the installation space?
A: In addition to the equipment's external dimensions, the withdrawal distance of the frame plate must be confirmed. Maintenance of the BRF-60 plate-frame fin heat exchanger usually requires pulling the frame plate out along the guide rail. If the reserved space is insufficient, fin cleaning and seal replacement will be difficult to carry out. At the same time, the matching flange standard and pressure rating should be consistent with the on-site piping to avoid secondary modification.
Q: How should the nameplate parameters be used in daily inspections?
A: The nameplate should clearly mark the design pressure of 1.6 MPa, design temperature of 200°C, heat exchange area, and medium flow direction. During inspection, the actual operating pressure and temperature should be compared with the nameplate values to prevent seal failure or fin deformation caused by overpressure and overtemperature. If the operating parameters are close to the design upper limits, check whether the system has uneven flow distribution or bypass short-circuiting.
Q: After changes in heat load and temperature difference, how can it be determined whether the area is suitable?
A: The required heat exchange area can be recalculated based on the actual heat load and logarithmic mean temperature difference. If the actual area is obviously insufficient, the outlet temperature will remain low; conversely, excessive area margin may cause investment waste and lag in regulation. It is recommended to periodically review based on operating data and design parameters, and if necessary, communicate with the manufacturer about selection adjustments.
