Numerical simulations of turbulent multiphase flows with atomization and sprays

CO2 from the flue gases of a rotary kiln in a cement industry (CO2: 25 vol%) will be used for the production of value-added chemicals (acid additives for cement formulations) and materials (CaCO3 nanoparticles to be used as concrete fillers). In other words, a circular-economy-approach is established in a way that the CO2 produced by cement manufacturing is re-used in a significant part within the plant itself to produce better cement-related products entailing less energy intensity and related CO2 emissions by a quadratic effect.

Ionic liquids (bare or amine-functionalised) will be the key technological playground for the efficient and cost-effective (<30 €/ton) purification of CO2 to a purity grade sufficient for the above mentioned utilisation paths. A dedicated pilot plant (flue gas flow rate: 50 Nm3/h) will be developed, based on the knowledge-based selection of the best ionic-liquids composition and operating conditions.

Within a final TRL 6 integrated system demo campaign, the thereby derived CO2 will be utilised in parallel to:

• Promote the precipitation of nano-CaCO3 powders which act as strength enhancer and accelerator of the hydration rate.
• Synthesize through electrocatalytic and catalytic pathways formic acid, oxalic acid and glycine to be used as hardening acceleration promoters, grinding aids or ionic liquids additives, respectively.

Distinctive features of the RECODE approach are the high process intensification and scale-up-ability, the use of low-grade heat sources, the meaningful reduction of CO2 emissions (>20% accounting for direct and indirect means) and the good market potential of their products at a mass production scale.

EBIvbt at KIT will support the project by designing the simultaneous compression-dissolution unit responsible for dissolving the CO2 within an ionic liquid. Experimental investigations will cover a wide range of activities containing the spray characteristics at various pressures, finding the optimum motion profile for the piston (to gain maximum energy efficiency), designing and building of a fully functional test-rig.

On the other hand, EBIvbt at KIT will also model the simultaneous compression-dissolution unit with the help of computational fluid dynamics. The model will combine both Eulerian approach (in particular VOF method) for modelling of multiphase flows, with the Lagrangian approach suited for spray computations. The former is suited for scenarios where the accurate modelling of the liquid flows (motion/deformation of the liquid film) is of interest while the latter is suited for cases where abundant number of liquid droplets are involved. This combination will benefit from reasonable computational time and accuracy of the simulations. The hybrid model will account a single way conversion of Lagrangian particles to VOF, hence capturing the effect of film creation upon impact of the liquid droplets to the walls of the cylindrical container. Dynamic mesh technique will be used to account for the motion of the piston during compression. Dissolution process will be modelled with continuous species transfer (CST) method. The method will solve an extra transport equation (PDE) for concentration of  CO2 within gaseous and liquid phases. Moreover, it will also use Henry’s law to compute the amount of dissolved gas at the interfacial region.