CHX™ condensing heat exchangers use a single gas pass to remove both sensible and latent heat from the flue gas. The flue gas enters the heat exchanger covered with DuPont fluoropolymer through a carbon steel inlet plenum at the top and flows downward across the horizontal banks of heat exchanger tubes and exits the heat exchanger through an FRP outlet plenum on the
As the flue gas temperature reaches the water vapor dew point at the tube surfaces, condensation occurs. Due to the hydrophobic nature of DuPont fluoropolymer, droplets of condensate form and fall as a constant rain over the tube array. This provides two important advantages. It enhances the latent heat transfer and at the same time keeps the tube surface clean.
The modules are manufactured in a number of different sizes. The variety of module sizes and the modular construction allow the CHX condensing heat exchanger design to be optimized for each application.
The CHX™ tubing, in water cooled applications, is 1.125 in. O.D. alloy C70600 covered with a 0.015 in. thick extruded layer of DuPont FEP. The inside surfaces of the heat exchanger shell are covered with a 0.060 in. thick sheet of DuPont PTFE. During fabrication, the tubes are pushed through extruded tube seals in the tube sheet covered with FEP to form a resilient seal. This ensures that all heat exchanger surfaces exposed to the flue gas are protected against acid corrosion. Tube connections are made outside of the heat exchanger shell.
To protect the DuPont fluoropolymer, maximum flue gas inlet temperature is limited to 500° F. The maximum water inlet pressure and the maximum water outlet temperature are 150 psig and 250° F respectively. CHX™ heat exchangers are installed as passive systems in order to assure that these limitations will always be met.
The CHX heat exchanger can also be used to heat air. The materials of construction and the maximum operating parameters vary somewhat from above.
Condensing Heat Exchanger
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