Experimental Measurement of the Bulk and Flow Properties of Gas-Liquid-Solid Mixtures
In many reactors gas, liquid and particles are bought together. Understanding the flow of the mixture can be important for design and scale-up of the reactor. Here we investigate bulk and flow behavior of mixtures of gas, liquid and solid particles. We focus on dense mixtures of particles. The effect of water on the packing and flow properties of fine (cohesive) and coarse (non-cohesive) particles was experimentally investigated. Four different particle sizes ranging from 10 micron to 275 microns, were studied with various weight percent of water. The dry coarse particles flowed smoothly while the fine particles required agitation to initiate flow. The poor flow associated with fine particles is due to the formation of agglomerates due to cohesion. Agglomerates form when the interparticle forces (primarily van der Waals forces) are greater than the mass of the particle. Weak agglomerates can form with coarse particles when small amounts of moisture are added to coarse particles, creating liquid bridges between the particles. When enough moisture is added to the samples, the voids in the agglomerates fill up with water, creating a dispersion or slurry. Since sample characterization is dependent on many different conditions and properties, a multi-faceted approach was undertaken. With the use of a Freeman FT4 Powder Rheometer, measured changes in bulk density, porosity, compressibility, flow function coefficient, cohesion, flow energy and pressure drop of the bed were collected as a function of liquid content and particle size. The results show that both liquid content and particle size distribution play significant roles on the packing and flow of the particles. With a greater understanding of the many bulk properties associated with wetted material, changes can be implemented to improve how these materials are handled and processed in reactors, effectively lowering manufacturing costs.