Gas-Liquid Solid-Foam Reactors: A study of reaction engineering characteristics (EPC.5784)

Een nieuw type gas-vloeistof reactor wordt ontwikkeld, waarin open-cel schuimmaterialen (zoals koolstof-, keramische- en metaalschuimen) als katalysatordrager worden gebruikt. Hiermee kan een optimale stof- en warmteoverdracht worden bereikt waardoor geïntensiveerde chemische procesvoering mogelijk wordt. Verwacht wordt dat het gebruik van open-cel, netvormige schuimen, als katalysatordrager in gas-vloeistof reactoren, zal leiden tot aanzienlijk hogere stofoverdrachtsnelheden en minder terugmenging, dit alles met nauwelijks toename van de drukval. Hogere katalysatoractiviteit en productselectiviteit worden mogelijk, wat tot een aanzienlijke verkleining van apparatuur, verminderde verliezen aan afvalstoffen en minder energieverbruik zal leiden. Dit verhoogt de winstgevendheid van de chemische procesindustrie en is bovendien bevorderlijk voor het milieu.

The objective of this project is to develop a generic design methodology for new structured gas-liquid reactors that exploit open cell foam materials (viz., carbon, ceramic, and metal foams) as catalyst supports for optimum mass and heat transfer and hydrodynamics, enabling intensified chemical processes. Furthermore it is the aim of the project to assess the feasibility of these novel structured reactor configurations as to provide a potential edge over existing and conventional multiphase reactor technologies.
In this project a detailed experimental study is proposed of the hydrodynamic properties and mass transfer characteristics of open cell, reticulated foam materials that will be used as structured catalyst supports in gas-liquid reactors. The slurry bubble column is chosen as a typical paradigm of a gas-liquid-solid reactor where we replace the suspended catalyst particles by a solid structured foam as support for the catalyst. For this purpose a rectangular bubble column will be constructed, enabling the insertion of different blocks of foam materials. Blocks with different pore sizes will be used, ranging from 0.25 to 5 mm. Hydrodynamic properties of these new gas-liquid-foam reactor systems will be determined: i.e., flow regime transitions, gas hold-up, residence time distribution for gas and liquid, and pressure drop. Main system variables are the superficial gas and liquid velocities, using co-current up-flow as well as down-flow. Also flow limits will be set for counter-current flow and cross-flow. Gas-liquid-solid mass transfer rates will be determined and evaluated in relation to dissipated energy. Aiming at providing generic design tools, the measured hydrodynamic and mass transfer properties of these new gas-liquid solid-foam reactor systems will be described by engineering-type correlations that will serve as input for reactor design models.
It is expected that the use of open cell, reticulated foams, as catalyst support in gas-liquid reactors, will result in considerably higher mass transfer rates and less back-mixing, albeit at the expense of dissipated mixing energy. Higher catalyst activities and product selectivities will be possible, enabling significant size reduction of equipment and decreased loss of waste products. This will add to the profitability of the chemical process industries and will as well be beneficial to the environment.
In the last year of the project, a parallel process design study will be performed by a graduate design student (twaio) in close co-operation with the industrial users, comparing the application of the new reticulated foams with conventional packed bed and slurry systems, and with modern structured alternatives, like monoliths and Sulzer packings. This will ensure an efficient transfer of the design methodology to the industrial users as well as will provide a well-founded outlook on possible future utilizations of these new gas-liquid solid-foam systems.