When design and selection personnel face multiple welded plate heat exchanger schemes, they tend to compare only heat transfer area and quotation. In fact, the plate forming method, channel structure, nozzle arrangement, and material combination of a welded plate heat exchanger jointly determine the applicable operating boundaries. Taking the YBJ-90 type as an example, the single-plate heat transfer area, plate thickness, design pressure, and design temperature should be checked as a combination rather than taking the highest value of each item individually. For a scheme with a larger area but narrower channels, the pressure drop will rise significantly in media with higher viscosity, and the energy consumption of the circulation pump will increase accordingly.
This heat exchanger is suitable for heat exchange between clean or lightly fouling liquids and gases, such as hydraulic oil cooling, domestic hot water preparation, and process fluid heat recovery. Compared with detachable plate heat exchangers, welded plate heat exchangers have no gaskets and usually allow higher design pressure and temperature limits, but the requirements for medium cleanliness are also more explicit. For media containing fibers, particles, or prone to crystallization, filtration should be installed upstream or a wide-channel structure should be used; otherwise, after blockage, cleaning can only rely on chemical circulation, resulting in less maintenance flexibility.
The detachable structure facilitates mechanical cleaning by removing plates, while the welded structure mainly relies on chemical cleaning. Before cleaning, the medium side should be confirmed to avoid using cleaning agents incompatible with the plate material; after cleaning, thorough rinsing should be carried out to reduce residue. Before restarting equipment that has been out of service for a long time, the insulation resistance should be measured. If it is below the specified value, the equipment can be dried in an oven at about 200°C, or heated by applying power at reduced voltage, until the insulation resistance recovers. For sections with continuous operation and short shutdown windows, this maintenance characteristic needs to be considered at the selection stage.
For occasions with higher pressure ratings, cleaner media, and stable maintenance cycles, welded plate heat exchangers are comparable in terms of footprint and pressure-bearing capacity; for operating conditions requiring frequent mechanical cleaning, the feasibility of chemical cleaning should be evaluated. It is recommended to specify the medium side, cleaning method, and backup plan in the technical agreement so that equipment parameters match the full-cycle maintenance arrangements.
