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 lot of variation in calculations and design such type of equipments. Flow condition certainly vary when they is no packing the equipment and when structured packing or random packing are 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 than due to it wide application in study of fluidized bed reactors and packed bed separation towers it has been given as 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. Equipments are modified according to the pressure drop calculations and lot of equation like Ergun equation are mostly used to do the job. Friction factor calculation and Friction loss determines the energy required to operate the equipment with full efficiency.
Latest reactor design are 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 change in catalyst different products are obtained from same raw materials in 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