Use of the lotus effect in process engineering

Abstract

The invention provides an evaporator having a heatable heat exchange surface, which has a self-cleaning microstructured surface with elevations and depressions. The microstructured surface of the heat exchange surface may be produced by powder coating. The invention additionally provides a process for the evaporative concentration of solutions in an evaporator having a self-cleaning microstructured heat exchange surface, the solution for evaporative concentration preferably comprising viscous or solid constituents in solution, emulsion or suspension. Using the evaporators of the invention, caking of the viscous or solid constituents on the heat exchange surfaces during the evaporative concentration of the solutions is prevented. As a result, such solutions may be concentrated to a solvent content of <5% by weight.

We claim:  
     
         1 . An apparatus or part thereof for chemical plant construction, having a self-cleaning microstructured surface with elevations and depressions.  
     
     
         2 . An apparatus or part thereof as claimed in    claim 1   , selected from the group consisting of internal apparatus, vessel and reactor walls, discharge devices, fittings, circuit systems, evaporators, filters, centrifuges, columns, dryers, internals, packings, and mixing elements.  
     
     
         3 . An apparatus as claimed in    claim 2    in the form of an evaporator having a heatable heat exchange surface, wherein the heat exchange surface has a self-cleaning microstructured surface with elevations and depressions.  
     
     
         4 . An evaporator as claimed in    claim 3    in the form of a forced circulation, flash or coiled tube evaporator.  
     
     
         5 . An evaporator as claimed in    claim 3    in the form of an evaporator tube in which an annular flow is able to develop.  
     
     
         6 . An evaporator as claimed in    claim 3   , wherein the microstructured surface of the heat exchange surface is produced by powder coating.  
     
     
         7 . A process for the evaporative concentration of solutions in an evaporator having a self-cleaning microstructured heat exchange surface as defined in    claim 3   .  
     
     
         8 . A process as claimed in    claim 7   , wherein the solution for evaporative concentration comprises viscous or solid constituents in solution, emulsion or suspension.  
     
     
         9 . A process as claimed in    claim 7   , wherein the solution for evaporative concentration is an aqueous or aqueous-organic salt solution.  
     
     
         10 . A process as claimed in    claim 8   , wherein evaporative concentration is conducted to a solvent content of <5% by weight.