Three months after a plate-and-shell heat exchanger at a heating station was put into operation, dripping occurred at the secondary-side hot water outlet flange. Inspection after disassembly revealed hardening cracks at the edge of the sealing gasket. The actual operating temperature was about 135°C, but an EPDM gasket was selected during installation, whose upper applicable temperature limit is 120°C. Such problems mostly arise from a mismatch between gasket selection and actual operating conditions.
1. Nitrile gasket: suitable for oil and general water media below 80°C, with relatively low cost and good oil resistance.
2. EPDM gasket: suitable for hot water and steam conditions below 120°C, with good aging resistance.
3. Fluororubber gasket: can be used for corrosive media below 180°C, with strong chemical resistance.
4. Gaskets from different batches must not be mixed, to avoid sealing failure caused by hardness or dimensional deviations.
5. For the BRQ-75 plate-and-shell heat exchanger, it is recommended to select the gasket material according to the maximum working temperature plus a 10°C margin.
The BRQ-75 plate-and-shell heat exchanger adopts a combined structure of plate pack and shell. The shell side can withstand relatively high pressure, with a design pressure of 2.5 MPa; the plate side is suitable for clean media or media containing a small amount of particles, with a design pressure of 1.6 MPa. If the solid content of the medium exceeds 5%, a filter should be installed at the inlet to avoid blockage of the plate channels.
Nominal heat exchange area: 75 m²; plate material: 304/316L stainless steel; shell material: carbon steel or stainless steel; design temperature: -20°C to 200°C; connection specification: DN150; gasket material: nitrile/EPDM/fluororubber (selected according to working conditions).
The BRQ-75 plate-and-shell heat exchanger can be used in scenarios such as secondary networks of central heating, air-conditioning chilled and hot water systems, and chemical process cooling. Under clean water-to-water heat exchange conditions, the heat transfer coefficient can reach about 4000 W/(m²·K). During installation, space must be reserved for pulling out the plates to facilitate later cleaning and gasket replacement.
