What is high flux tubing or high flux tube? |
High flux tubing is specifically designed to enhance heat transfer efficiency in the nucleate boiling regime. A thin, porous metal layer or matrix is bonded metallurgically to the heat-transfer surface. Saturated liquid is drawn into the layer by capillary action and vaporizes from the extremely large number of stable generation sites which exist in the structure. Boiling side heat transfer coefficients of 10-30 times that of bare tubes can be achieved, resulting in an overall heat transfer improvement of 2-4 times that of bare tubes.
In new installations, the use of high flux tubing allows reduced exchanger surface area and/or lower utility consumption, resulting in substantial savings in capital and operating costs. For large reboiler duties, the use of high flux tubing can reduce the total number of exchanger shells required, resulting in not only reduced exchanger costs but savings in piping, controls, foundation, and plot plan space. The use of high flux tubing exchangers is particularly attractive for grassroots heavy aromatics separation, natural gas de-ethanizing, heat-pumped propylene/isobutene fractionators, and ammonia plant syngas chilling applications.
In retrofit situations, the use of high flux tubing in existing exchanger shells can allow increased capacity and/or elimination of a new exchanger addition. Alternatively, the use of high flux tubing can allow the use of lower pressure steam at fixed capacity, reducing utility costs. In a revamp situation, the use of high flux tubing, as an alternative to a new exchanger, is particularly attractive due to conservation of plot space, minimum downtime, and short lead-times.
Stable boiling is achievable at low temperature differentials. This feature can be used minimize the Log Mean Temperature Difference (LMTD) of the heat exchanger to reduce utility consumption. This is particularly effective in heat pump applications by reducing the compressor demand.
High flux tubes can be either ID or OD coated for boiling on the tube side or shell side, and the non-coated side can be finned or fluted for additional heat transfer capacity.
Years of commercial experience have shown the high flux tubing is not prone to fouling due to the extremely active boiling surface. High flux equipped exchangers have shown long-term, reliable operation. |