Photobioreactor Design and Fluid Dynamics

Photobioreactor design is a subject of great relevance for the attainment of a sustained development in modern technology,and has also considerable interest from the basic scientific and technologic point of view.The aim of the present review paper is presenting and comparing some of the recent attempts by the authors of modelling photosynthesis in reactors.A short inspection of the kinetic models proposed for photobioreactor design is done,and some examples of the integration of such kinetic models and bioreactor fluid dynamics in the modelling of photobioreactors are presented

Recirculation in airlift reactors: degassing at normal and elevated pressures

Gas-lift reactors are the simplest pneumatic reactors. Gas put into the reactor in lower part imparts flow of bubbles producing continuous circulating flow of liquid (or liquid-solid). Gas itself is leaving reactor through upper part of it passing gas separator zone. Three principal types of gas-lift reactors are known: bubble column (BC), internal-loop airlift (IALR) and external-loop airlift (EALR). If in first case reactor (BC) is just vertical vessel (mainly cylindrical one), both air lifts have a riser with co-current upflow gas and liquid and a downcomer with downflow of liquid phase with entrapped bubbles moving up in relation to liquid. That means that gas is put into the riser through a sparger (gas distributor device). Amount of gas retained in reactor defines in large extent intensity of transfer phenomena in reactor - hydraulics, mass transfer, heat transfer. Its value is expressed by gas hold-up that is main parameter of gas-lift reactor performance. Basically, gas hold-up is function of flow rate of gas put into the reactor and of flow rate of gas going out from the reactor. The last one in turn depends considerably on type and dimensions of reactor, properties of gas and liquid phase. The most of authors studied gas hold-up in all reactor types at room pressure. And almost no data can be found on performance of air-lift reactors at high pressures that is important for processes with solid catalysts in gas-liquid medium. (orig.)Available from TIB Hannover: F00B211+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEGerman-Israeli Foundation for Scientific Research and Development (GIF), Oberschleissheim (Germany)DEGerman