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Sunflower husk (SFH) contributes 45–60% of the total sunflower seed weight and is a by-product of the sunflower oil industry. Among other elements, SFH ash contains K, Na, Ca and Mg. These elements cause rapid growth of ash deposits on convective heating surfaces of the boiler, resulting in reduced efficiency. The aim of this paper is to examine the possibility of producing quality fuel from SFH by its pretreatment with the technique of torrefaction in a fluidized bed in superheated water vapor. Continuous monitoring of the innovative SFH torrefaction process allowed for the determination of optimal process durations. SFH could be converted into a biofuel, having high calorific value and suitable characteristics for co-combustion with coal. Furthermore, the torrefaction in a fluidized bed of superheated water vapor allowed for a 6-fold reduction in the required process duration in comparison with data reported from the literature for the process of torrefaction in a dense bed, along with a 3-fold reduction in the chlorine content in SFH ash. These effects are beneficial to resolve the problem of corrosion on convective heating surfaces of boilers. However, torrefaction in superheated water vapor did not significantly reduce the content of alkaline and alkaline-earth elements in SFH ash. Still, this issue may be alleviated by significantly increasing the duration of SFH pretreatment. [ABSTRACT FROM AUTHOR]

The process of wet torrefaction (WT) in a fluidized bed powered by superheated steam is applied to produce biochar, which can be subsequently processed into activated carbon, as an interesting bioproduct with high specific surface area. In this study, WT process was carried out at a temperature of 300-350 °C using mixtures of chicken manure and pine sawdust. Both the composition of the initial biomass, and the temperature of WT process had a considerable effect on the contents of non-condensable gaseous torrefaction products. Increasing the proportion of chicken manure in the mixture increased processing time from 30 to 46 minutes. Hence, in this work, it is hypothesized that two processes may have taken place concomitantly in the reactor: wet torrefaction of chicken manure and wet gasification of sawdust. Biochar obtained after WT of chicken manure as sole feedstock, and in mixture with sawdust was further activated using potassium hydroxide at a temperature of 750 °C. The activated carbon had following characteristics: specific pore surface area according to BET: 2031-3392 m²/g, and specific volume of pores with a size of less than 2 nm (micropores): 0.592-0.841 cm³/g. Furthermore, the quality of activated carbon in terms of porosity decreased with higher shares of sawdust in the mixture. [ABSTRACT FROM AUTHOR]

The torrefaction process of biowaste types, such as a mixture of chicken manure and wood sawdust, wood sawdust and sunflower husk, is proposed to be carried out in a fluidized bed, which is formed by the crushed biowaste, blown from the flue gases leaving the boiler. The preliminary studies of the oxidative torrefaction process showed that the time of biomass particles in such reactor may not exceed 5 minutes. In order to ensure the indicated time of the biomass particles in the oxidation torrefaction reactor, it is proposed to place a number of vertical partitions installed at a distance of 50 mm from each other in a fluidized bed. These partitions provide a loop-like movement of biowaste material from the place of loading into the reactor to the place of unloading. As studies on a cold apparatus showed, these partitions can provide the necessary time in the reactor and a set degree of biowaste treatment. For a reactor with a diameter of 1 m, the presence of such a package of partitions provides the time of biomass particles in a fluidized bed for 5 minutes with a reactor productivity of 300 kg/h in the initial biomass or 150 kg/h in the resulted biochar. [ABSTRACT FROM AUTHOR]