Pyrolytic carbon (pyrocarbon) is a high-purity type of carbon resulting from the decomposition of gases, whether natural or formed as byproducts, within the porous carbon material generated by the thermal destruction of biomass. Hydrogen is formed in the thermal decomposition of hydrocarbon gases during semicoking. A cost–benefit analysis is presented for the construction of industrial systems to produce pyrocarbon. Systems for semicoke production based on the technology proposed by the Joint Institute for High Temperatures (in collaboration with Kurchatov Institute and Tatneft) are considered.

The pyrolysis of two types of raw materials of plant origin (sawdust and sunflower husks), components of the organic matter of biomass (hemicellulose, cellulose, and lignin), and model mixtures prepared from components in accordance with their fractions in the raw materials was studied. Pyrolysis of the materials was carried out using TGA and a laboratory setup with a fixed bed reactor. The distribution and composition of the products were determined at pyrolysis temperatures of 350, 425, 500, and 575°C. Experimental data obtained with the biomass samples and model mixtures were compared with calculated values obtained based on the pyrolysis of individual components and their fractions in the biomass. The possibility of predicting the distribution of pyrolysis products depending on the component composition was investigated. The influence of intercomponent interaction in biomass on the yield and composition of pyrolysis products was revealed.

This paper analyzes the features of the implementation of the torrefaction process according to the technology developed at the Joint Institute for High Temperatures of the Russian Academy of Sciences using the internal energy of a controlled exothermic reaction. This technology allows reducing energy consumption by several factors for the torrefaction process. In experiments on the installation and in the numerical simulation of the process, an oscillatory change in the temperature of the processed biomass is revealed. A mechanism is presented for controlling the mode parameters of the torrefaction process using the effect of exothermic heat release, which ensures the smoothing of temperature oscillations of the process in a highly energy-efficient manner.

The article presents the main factors influencing the country’s transition to a “green” energy, as opposed to the energy, the development of which is accompanied by large-scale environmental pollution, as well as the accumulation of a significant amount of production and consumption waste. The results of comparative calculations of the main parameters for traditional and non-traditional power plants for the conditions of Russia are considered. The comparison was made for nuclear power plants, thermal power plants operating on coal and on natural gas; hydroelectric power station; as well as network wind farms and solar power plants – without accumulation. It is shown that a promising direction in the construction of wind and solar power plants, as well as other generating facilities based on RES, is to cover the own energy needs of various enterprises and organizations. The proposed direction of energy development is promising and economically beneficial also due to the fact that biomass in our country is one of the most common types of renewable energy sources. About 48% of the world’s peat reserves and 23–24% of timber are concentrated in Russia, as well as huge amounts of agricultural waste. The article proposes effective technical solutions in the field of energy use of biomass. It is shown that for Russia a promising direction for the modernization of the existing energy supply system is the combined use of various types of renewable energy sources and local bioenergy resources that complement each other and provide guaranteed energy supply to consumers while minimizing the required investments.

The results of experimental and computational studies of torrefaction (low-temperature pyrolysis) of granular plant biomass are presented. As a result of this process, high-quality solid hydrophobic biofuel with increased calorific value is obtained from biomass of various types (including waste). Unlike fossil coal, torrefied fuel contains virtually no sulfur and heavy metals, has a lower ash content, and is a carbon-neutral product. The carbon dioxide released during the combustion of plant biofuels is completely absorbed during the period of plant growth. Biofuels are a renewable resource. The annual increase in biomass is 400 billion t, and the rate of energy accumulation by terrestrial biomass is 3 × 1021 J/year. The article considers a vertical reactor with a dense layer of pellets moving towards the heating gas flow under the action of its own weight and features of its operation, taking into account the possible implementation of the concept of a controlled exothermic reaction. To ensure the set mode, the plant has two control units: for controlling and maintaining the set temperature of the coolant at the reactor inlet and for controlling the opening of dampers for unloading finished products into the cooling zone. Experimental and calculated data are presented for three characteristic operating modes of the installation: with limitation of the exothermic reaction due to the control of the inlet temperature, with a controlled exothermic reaction, and with the production of biochar. The second mode turned out to be the most energy efficient. The deviation of the calculated data from the experimental data was no more than 4

The influence of the temperature of hydrothermal carbonization and torrefaction on the properties of biochar obtained from biomasses (peat and sawdust) and model mixtures of structural components (cellulose, hemicellulose, and lignin) prepared in percentage ratios corresponding to their amounts in real biomass was studied. It was found that the yield of biochar decreased with temperature in both of the processes, whereas the degree of deoxygenation, the amount of carbon in the biochar, and its calorific value increased. A comparison of biochars from biomass and model mixtures was carried out. An assumption on the screening effect of lignin in heat treatment, which reduced the degree of degradation of the structural components of biomasses, was made.

The results of a study of the pyrolysis of dried sewage sludge taken from a fixed-bed reactor of urban wastewater treatment plants are presented. The obtained experimental data made it possible to estimate the migration activity of heavy metals entering into the composition of the sewage sludge. Measurements were carried out for vanadium (V), chromium (Cr), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), strontium (Sr), lead (Pb), rubidium (Rb), barium (Ba), zirconium (Zr), and arsenic (As). It is shown that the emission of heavy metals upon release of volatile substances during pyrolysis is characteristic for almost all of the studied elements, among which As, Rb, Co, and Ba are the elements having the highest migration activity.

A comprehensive study of the two-stage thermal processing of dried sewage sludge (SS) into synthesis gas with a high hydrogen content is carried out. The data of the thermogravimetric (TG) analysis of the studied material are used to determine the kinetic parameters of its decomposition. An experimental study of the pyrolysis of dried SS in a fixed-bed reactor makes it possible to reveal the main regularities in the formation of pyrolysis products (semicoke, tar, noncondensable gas, and water). Using the data of gas chromatography-mass spectrometry, the quality of liquid pyrolysis products is assessed. It is shown that the two-stage thermochemical conversion of the initial material, which combines pyrolysis and the subsequent heterogeneous cracking of volatile pyrolysis products, makes it possible to effectively obtain a fairly pure high-calorie gas, the main components of which are hydrogen and carbon monoxide.

The work is devoted to an experimental and design-theoretical analysis of combustion regimes of depleted compositions of gas mixtures based on hydrogen and syngas in the combustion chamber of a spark-ignition internal combustion engine. The analysis made points to the energy advantages of use of syngas compared to hydrogen. Here, on the one hand, it has been shown that the indicated efficiency is weakly dependent on the excess-hydrogen coefficient, which allows the conclusion on the expediency of utilization of depleted compositions as more environmentally safe ones. On the other, the existence of a certain concentration limit has been demonstrated below which a significant underburning of a fuel–air mixture, including that determined by the dynamics of the combustion front in the combustion chamber of the internal combustion engine, is observed.

The transformations of hemicelluloses, cellulose, and lignin isolated from peat and sawdust were studied under conditions of hydrothermal carbonization and torrefaction. The effect of heat-treatment temperature on the yield and composition of the resulting biochars was established. It is shown that the nature of the raw material and the heat-treatment method have a significant effect on the carbon efficiency of the thermochemical conversion of its components. Carbohydrate components of sawdust were converted to a lesser extent than similar components of peat. Mild heat-treatment conditions (below 300°C) had almost no effect on lignin.

The results of studies on the application of pyrolytic methods for the processing of solid municipal waste into liquid and gaseous fuels are presented. The features and types of pyrolytic processes are reviewed, and the key pyrolytic products are analyzed in detail with respect to the process pressure and heating rate of the initial mass of solid municipal waste. Since the liquid products produced with standard pyrolysis have a high content of oxygen-rich compounds and water, catalytic methods are employed to make high-quality boiler or transport fuels. The main types of catalysts, their properties, and their effects on the process are considered. The advantages of a two-stage process, in which the pyrolytic products at the second stage of the process undergo high-temperature catalytic cracking with the formation of synthesis gas (syngas), are analyzed.

Within the framework of the model of ideal mixing of particles in a fluidized bed, the conditions needed for carrying out the continuous process of precarbonization (torrefaction) of biowaste in a fluidized bed reactor have been elucidated. The dependence of the degree of torrefaction on the average residence time of particles in the reactor and on the characteristic time of torrefaction has been established.

Experimental and calculated data on the characteristics of synthesis gas, which can be obtained by the two-stage pyrolytic conversion of various types of biomass related to wastes from the woodworking industry and agricultural production, as well as industrial and domestic organic wastes, are presented. The variety of properties of the test types of hydrocarbon raw materials made it possible to establish the influence of the characteristics of processed biomass on the characteristics of the resulting synthesis gas (composition, volumetric yield, and heating value). It was found that the ratio H-2/CO in the resulting synthesis gas can be purposefully changed by choosing a feedstock with an appropriate H/O atomic ratio. It was proposed to use the volatile content of the processed raw material calculated on a dry ash-free basis as a parameter that determines the energy efficiency of the two-stage process of pyrolytic conversion of biomass into synthesis gas. The range of volatile content corresponding to the maximum values of the degree of energy conversion was established.