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Shell
& Tube Heat Exchangers
Double-wall heat exchangers : enhancing safety and efficiency
The need to protect the environment is ever increasing , Funke is playing its part in many ways and one is through the development of a double-wall safety range of heat exchangers . These units are designed to prevent cross-contamination between fluids inside the heat exchanger .
Text & images by Funke Wärmeaustauscher
How it works Safety heat exchangers are designed as three chamber devices with straight internal tubes and fixed ( F ) or removable ( P ) tube bundle . In each individual internal tube of the tube bundle a further smaller internal tube is installed . These concentric internal tube pairs form radial gaps which are interconnected by the design of the double tubesheets and thus produce the enclosed safety space . A mixing of the flowing operating media is prevented in this way . This sealed safety space is filled with a special barrier fluid . It is responsible for the heat transfer in the radial gap and functions as a transmitter in the leak monitoring system . The safety area is sealed off and permanently monitored for pressure changes . In the case of a leakage of the outer or inner tube , the corresponding pressure change within the safety space will be detected by the pressure control device and signalled accordingly . The safety area is also equipped with an expansion tank which prevents false alarms due to thermal volume or pressure changes .
Structure on inner tube before expanding .
Double-wall tube with enhanced contact surface between both tubes through hydraulic expansion .
Shellside Fully welded with or without expansion below and fixed tube bundle ( SWF ) or with removable tube bundle ( SWP )
Tubeside Tube-in-Tube-System and Double Tube- Sheets on both sides
Three – Room – Device Shellside – red Tubeside – blue Safety room – yellow
Safety Room P – Pressure Transmitter ,
Pressure Monitoring V – Volume Expansion Tank
Basic principle of the serial standard ( type SWF and SWP ).
50 Heat Exchanger World September 2024 www . heat-exchanger-world . com