Falling Film Plate Evaporators
Falling film provides the most effective use of a heating surface, and the RDG double embossed plate style heating elements are the most efficient surface in use today. Our plate evaporators offer many operational benefits, as compared to other tubular design products on the market, such as:
- Film quality – RDG heating elements are spaced within the evaporator vessel so that generated process vapors do not disturb the falling liquid film. To ensure film continuity and integrity, the liquid is redistributed as it flows down the surface by the staggered pitch of the plate’s dimples.
- Entrainment – Produced vapors are released upon generation between the adjacent elements. The available vapor space in both the vessel and between elements is sized to minimize and avoid entrainment of the circulating liquor. The highest vapor velocity for the system is at the entrance to the entrainment separator assembly.
- Steam side coefficient – The small pressure drop over each element assures uniform steam distribution within that element. This makes the evaporator less sensitive to the presence of non-condensable gases, for they are removed from the system more effectively.
- Scaling and cleaning – Deposits form as a result of the evaporation process on the external surface of elements. Since the external surface of the RDG elements is irregular and convex, the deposits have a lower tendency to adhere, tend to spill off and can be more easily removed via chemical or mechanical cleaning. All external surfaces are more accessible for inspection and cleaning than a typical tubular surface.
- Selective condensate – Design of the RDG element allows for countercurrent flow of the incoming steam and the produced condensates. As a result, the elements act as an enrichment column for volatile organics. RDG elements can effectively concentrate 80% of the incoming methanol and BOD content into a five percent foul condensate product stream.