Evgenij Yur'Evich Shadrin

The aim of the work is to study the effect of diluting gases (nitrogen, carbon dioxide, and steam) and oxygen on the combustion of liquid fuel atomized with superheated steam. Main attention is paid to optimizing the combustion process environmental and power performance characteristics. Experiments were carried out using a laboratory burner with fuel atomized by means of steam into a preliminary gas generation chamber, in which atomized fuel is mixed with blast of various compositions. Operating conditions with addition of diluting agents at room temperature and with heating them to 250°C, as well as cases with the use of oxygen-enriched blasting, were studied. The study results have shown that the temperature of supplied gases plays the key role in the combustion process: in admitting cold dilution agents, the flame temperature decreased by 150–200°C, and the chemical reactions slowed down, whereas when heated gases were admitted, the high flame temperature remained unchanged. With increasing the oxygen fraction, a growth of temperature was observed. It has been determined that the ingress of cold diluting agents in the fuel entailed a more efficient reduction of NO_x and CO emissions in comparison with the operating conditions with admission of a heated mixture. At the same time, the admission of heated gases resulted in lower emissions under the operating conditions with oxygen enrichment. Injection of steam resulted in a lower production of NO_x, but it entailed higher CO emissions and caused the combustion to become unstable. By using the method proposed in the article, it is possible to reduce the NO_x emissions (up to 50%), which is commensurable with this indicator in the case of conventional recirculation of flue gases, but with a lower fraction of them (5–10% against 20–30%). This makes the technology involving steam-assisted atomization and controlled dilution of fuel a promising option for use in the power industry and metallurgy, sectors in which high energy efficiency and environmental safety are of importance.

This study investigates the thermal decomposition, ignition, combustion, and gasification processes of composite fuels derived from anthracite coal and pine sawdust. The research highlights the non-additive behavior of composite fuels, demonstrating enhanced reactivity and combustion efficiency compared to simple mixtures. Thermogravimetric analysis (TGA) revealed distinct stages of thermal decomposition, with composite fuels exhibiting combined processes of volatile release and coke residue decomposition, unlike mixtures. Ignition experiments in a vertical tubular furnace showed reduced flash delay times for composites, attributed to the formation of active surface centers during mechanical activation. Flare combustion studies confirmed more stable and complete combustion of composites, achieving higher temperatures and improved flame stability. Plasma gasification experiments indicated that composite fuels provide more uniform gas evolution, with higher yields of hydrogen (H₂) and carbon monoxide (CO), while reducing nitrogen oxide (NO) emissions. The findings underscore the potential of composite fuels for optimizing energy efficiency and reducing environmental impact in coal-fired power plants, supporting the transition to sustainable energy solutions.

In this work the combustion characteristics of liquid hydrocarbons when atomized by a high-speed air jet were studied, using diesel fuel as an example. This approach to spraying liquid fuel in combustion processes has a number of advantages over traditional spraying: the ability to supply fuel with a low degree of purification, reducing the chance of coking of fuel equipment. Using an atmospheric burner device with natural air supply into the mixing chamber, the dependences of the composition of intermediate and final combustion products were studied, and the flame temperature was measured at various fuel flow rates and parameters of the atomizing air jet (flow rate, temperature). A comparison of the obtained characteristics was made for equivalent modes at different temperatures of the supplied atomizer. It was found that when heated air is used as a sprayer, higher flame temperatures are ensured, which ensures more complete fuel burnout and a decrease in CO concentration in the flue gases, but at the same time, a slight increase in NOx was observed.

In this work we study the process of co-combustion of pulverized coal fuel (coal grinded up to 100 microns) and liquid (diesel) fuel in a new low-power burner, where coal-air mixture is fed tangentially together with secondary air, and liquid fuel is atomized by a high-velocity steam jet. Temperature profiles and composition of intermediate combustion products along the vertical axis of the burner have been studied. The heat release (power) and the gas composition of final combustion products have been measured. This allowed us to demonstrate the principal possibility of combined combustion of coal dust and diesel fuel in a compact laboratory burner.

Combustion of liquid hydrocarbons atomized with a jet of superheated steam is experimentally studied using n-heptane as an example. This is considered as a promising method for efficient and environmentally safe combustion. The study uses a burner with forced air supply to the gas generation chamber. It is a modernized design of an atmospheric burner with natural air inflow, studied by the authors earlier, and it allows obtaining additional information about the effect of changing the excess air ratio inside the device on the process of burning liquid fuel in the presence of superheated steam. New data on the environmental and energy characteristics of the burner under study were obtained based on thermocouple measurements, gas analysis of intermediate flame components, measurements of combustion efficiency and harmful emissions in the final combustion products. They were compared with characteristics of the burner with natural air inflow. It was found that the formation of carbon monoxide during heptane combustion is reduced by 25 %, and the formation of nitrogen oxides is reduced by 15 % with a decrease in the excess air ratio in the combustion chamber from 0.7 to 0.16. At the same time, a burner with natural air inflow is characterized by a higher flame temperature and a shorter flame length. At that, the level of CO and NO_x emissions in all regimes corresponds to the European standard EN 267. It was determined that the forced air flow does not have a noticeable effect on the heat generated for the studied regimes, and the calorific value of fuel combustion in all cases is close to the higher calorific value of heptane, which indicates the high efficiency of the combustion method under study.

The characteristics of a fuel spray atomized by a steam jet were studied using the method of shadow photography. The studied method of forming a two-phase flow for dispersing liquid fuel allows application of a wide range of hydrocarbons and increases the service life of the combustion equipment due to the absence of fuel spraying nozzles. Using a long-focus macroscopic lens, the dispersed composition of spent engine oil was measured at various fuel supply frequencies: 10, 25, and 40 Hz. The dispersed phase velocity was determined using the PIV-algorithms; it amounted to 60 m/s for all studied regimes. It is shown that the frequency of liquid fuel supply does not affect the size and velocity of the formed fuel droplets.

The spatial structure of a swirling turbulent flow has been investigated based on the three-component laser Doppler anemometry method in an isothermal laboratory model of a four-vortex furnace. The structure of the vortex cores of the flow with the shape of a deformed vertical elliptical cylinder is visualized using the ?minimum total pressure? criterion. The spectrum of velocity pulsations indicates the absence of unsteady periodic vortex structures, which means the occurrence of a stable vortex flow in the volume of the combustion chamber.