When a fluid which may be liquid or gas flowing through equipment and pipes which are filled with packing materials or solid obstruction(particles in case of catalyst powder) and even in the case of solid transport by mean of fluid flowing system, we come across a lot of variation in calculations and design such type of equipments. Flow condition certainly varies when they are no packing the equipment and when structured packing or random packing have used the flow of fluid differ with respect the type of packing used. So initially the concept of "Flow of fluid through packed and fluidized bed" is dealt fluid mechanics and then due to its wide application in the study of fluidized bed reactors and packed bed separation towers it has been given a different subject during the course of design sophisticated equipment for a process industry.
Pressure drop is one of the important parameter, which handles most of the design concepts. Types of equipment are modified according to the pressure drop calculations and a lot of equation like Ergun equation is mostly used to do the job. Friction factor calculation and Friction loss determine the energy required to operate the equipment with full efficiency.
Latest reactor design is made with a view that it can be used to handle fluidized catalyst so that the catalyst can be regenerated and maintenance cost can be decreased and even it can to multi-task for producing products based on the demand. With the change in catalyst different products are obtained from same raw materials in the same reactor. The replacement of the catalyst becomes easy and can be done with less cost, due to fluidization operation design.
Document on Flow through packed and fluidized beds