The gas is heated by suspending an element, consisting of smooth tubes, in the gas duct. Flue gas at >600°C flows through these tubes.
For both gas streams, the pressure drop was limited to only a few millibars. There were also dimensional restrictions, which led Robox to choose a single-pass design. However, as a result of the single-pass design, stresses occur because the channels expand. Robox has designed a single-pass element that is not affected by these expansions.
The system will operate under various cases, so the design has been optimized for the design case where the most heat must be exchanged and the design case where the pressure drop is the bottleneck.
This concerns an element mounted in a duct where the flue gas must heat the gas in the duct in a single pass. The design is according to ASME VIII Div. 1.