This article presents a new method for the control of a gas-sand conical fluidized bed with a wide size distribution of particles. A two-step procedure was developed and experimentally tested. The minimum velocity for full fluidization is determined by a new statistically based method and then the fully fluidized state is initiated and controlled. It is proven that the characteristics of the pressure drop vs. fluidization velocity remain practically the same for different bed heights and over a wide size distribution of particles. The method analyses the recorded pressure drops with a histogram. The minimum velocity for full fluidization is determined as the smallest fluidization velocity from the histogram bin with the highest density. Finally, it is also proved that the fluidization velocity is a reliable parameter for controlling the fluidization. The method was used to control fully fluidized beds at the minimum gas velocity in a pilot FICFB gasificator.

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Dedicated to the memory of Prof. Dr. Jurij V. Bren~i~. AbstractA successful co-gasification of plastics and biomass was achieved in the 100 kW dual fluidized bed (DFB) gasification pilot plant. The results of a pilot plant experiment were used as a sound basis for scale-up prediction to 750 kW semiindustrial DFB plant. By an eightfold increase of mass and heat flows a rather simplified co-gasification process was predicted. Namely, the losses occurring in gasification plants are expected to be relatively smaller in larger plants. The effect of decreased losses was studied with an equilibrium model. Three different situations were simulated with the following fixed values of losses: 70 kW, 115 kW and 160 kW. The model showed an increase in fuel conversion when losses were reduced.

The main purpose of a fast internal circulating fluidized bed gasifier is the steam reforming of solid organic matter, like biomass, to a nearly nitrogen-free syngas. The calorific value of this syngas is approximately three times higher than the gas from common air-driven gasifiers. This article deals with a study of the particle dynamics in a 1 MW t fast internal circulating fluidized bed plant and focuses on the design of the gasification reactor's geometry. Superheated steam is used for the fluidization and gasification in the reactor. The gasification of solid fuels causes an increase in the volume flow of the fluidizing gas and at the same time also a change in the fluidization regime. Approaching a turbulent fluidization regime or even fast fluidization is not desirable. However, with the proper design of reactor, i. e., an appropriately conical bed angle, suitable gasification conditions in the form of a fluidizing regime can be achieved across the entire height of the bed. For the purposes of the experimental research, a semi-industrial unit was setup. The process was designed and experimentally tested on a lab-scale, cold-flow model and scaledup to a semi-industrial process. The guidelines for designing the geometry of the gasification reactor were set.