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Consideration has been given to problems of chemical activation of a solid product of hydrothermal carbonization (hydrochar) of biomass. Pellets from a mixture of poultry litter and straw subjected to carbonization in a fluidized bed in a medium of superheated water vapor at a temperature of 300°C were impregnated with water solution of ferric nitrate, dried in the air at a temperature of 100°C, and held for 2 h at a temperature of 300°C for degradation of iron(III) nitrate and its transformation into iron oxides. The pellets were activated at a temperature of 700–800°C in a horizontal tube furnace in an inert argon atmosphere. The obtained ferromagnetic sorbents have a rather developed system of micro- and mesopores. Furthermore, a twofold increase in the duration of activation results in an 18% increase of the pore specific surface, and the rise in the temperature of the activation process leads to an increase in this surface by 45%.

An experimental study of fluidization of two types of bidispersed layer with a pronounced bimodal particle size distribution has been carried out. The possibility of using the equivalent diameter of the mixture particles, calculated from the weight average diameter of the particles constituting the mixture, is shown.

A study has been made of the hydrodynamic characteristics of the transition of a multicomponent bed consisting of coal sludge and straw pellets to a fluidized state. It has been shown that increase in the fraction of large particles (pellets) in the bed leads to a decrease in its relative height and in the amplitude of pulsations of the pressure difference in it; this contributes to the rise in the degree of conversion of chemical reations occurring in the bed. The possibility of assessing the minimum fluidization velocity of a multicomponent bed from the dependence of the standard deviation of a pulsation of the pressure difference in it on the velocity of air blown though the bed has been proved.

Results of determination of effective heat capacity of untreated biomass granules are furnished. It is shown that evaporation of moisture and other volatile components present in the material affects heat absorption by the material. A mathematical model of the temperature field in reactor chambers during low-temperature biomass pyrolysis is given.

A relationship is established between statistical characteristics of the random process of press-gradient pulsation in a fluidized bed and changes in the bed’s fractional composition. This relationship can be used to monitor the process of defluidization (transition of the bed from the fluidized to the non-fluidized state) based on the results of a comparative analysis of the above-mentioned statistical characteristics. The feasibility of performing such monitoring was confirmed experimentally from the combustion of lowmelting biogranules (straw granules) in a fluidized bed. It was found that the bed remains in the fluidized state as long as the dimensionless amplitude of the pressure-gradient pulsations does not exceed 0.1. The utility of the proposed monitoring method was also substantiated by comparative studies of changes in the fractional composition of a fluidized bed and the temperature and chemical composition of the flue gases.

This article presents test results for a reactor model designed for low-temperature pyrolysis of biomass. The efficiency of the pyrolysis attains maximum values at 240–250°C and a process duration of 50 min. The test results are used in the development of an industrial reactor with a capacity of 1 ton/h with respect to initial biomass.