In steam-heated circulating water or thermal oil systems, it is common for the heat exchanger outlet temperature to be normal during initial operation but gradually decline after several months. Inspection upon disassembly often reveals fouling between plate bundles or aging gaskets. Such problems are mostly related to insufficient estimation of operating boundaries during selection.
The BRQ-220 plate-shell heat exchanger can adopt a fully welded plate bundle structure with a gasket-free design, and its applicable temperature range can be extended to below 400°C with a design pressure not exceeding 4.0 MPa. If the medium temperature exceeds the upper temperature limit of the gasket, the fully welded solution should be given priority to avoid frequent replacement of sealing components.
The sealing gasket material should be selected according to the medium temperature and chemical properties: nitrile gaskets are suitable for oil and water conditions below 80°C; EPDM gaskets are suitable for hot water and steam conditions below 120°C and have good aging resistance; fluororubber gaskets can be used for weakly corrosive media below 180°C. Different batches of gaskets must not be mixed in the same equipment to avoid leakage caused by inconsistent compression.
Removable plate bundles facilitate mechanical cleaning and are suitable for media prone to fouling; fully welded plate bundles have no gaskets and are suitable for clean media at high temperature and high pressure that are not prone to fouling. During selection, a comprehensive judgment should be made based on the maintenance cycle and cleaning method.
