An operator at a certain facility reported that the shell-side inlet-to-outlet pressure drop of a shell-and-tube heat exchanger rose from 0.08 MPa to 0.13 MPa within two weeks, while the outlet temperature decreased simultaneously. On-site inspection confirmed that the tube-side flow rate remained unchanged, and the initial judgment was shell-side fouling or blockage of the baffle plate channels. This phenomenon suggests that routine maintenance should focus on the synchronized changes in pressure drop and temperature difference, rather than only looking at a single outlet temperature.
The GCH-420 shell-and-tube heat exchanger is suitable for heat exchange conditions such as liquid-liquid, vapor-liquid, and oil-water. After commissioning, it is recommended to record the inlet and outlet temperatures, pressures, and flow rates of both the tube side and shell side on a shift basis to form trend curves. When the shell-side pressure drop continues to rise or the heat transfer temperature difference deviates from the design value by more than 15%, an inspection should be scheduled. Recording data also helps distinguish among three types of problems: fouling, leakage, and improper medium distribution.
The medium distribution between the shell side and tube side should be determined during the selection stage in combination with corrosiveness and fouling tendency. During routine inspections, attention should be paid to whether there are erosion marks at the tubesheet welds, flange sealing surfaces, and baffle plate notches. For media prone to fouling, inspection points can be set based on pressure drop trends; it is not advisable to simply disassemble for inspection at fixed intervals, so as to avoid repeated disassembly and assembly affecting sealing performance.
A common question from procurement personnel: which parameters need to be confirmed first for selection? Answer: The chemical composition, operating temperature, flow rate, and allowable pressure drop of the media on the tube side and shell side must be clarified. These parameters directly affect material selection and heat transfer area calculation. When parameters are incomplete, it is recommended to first conduct medium analysis before determining the model, so as to avoid aggravating fouling after commissioning due to low flow velocity.
