The thermolysis of Mongolian coals of different ranks was studied using thermal analysis (TG/DTG). The stepwise decomposition under conditions of programme

The work determines the characteristics of the processes of thermal decomposition and combustion when heating coal, cedar needles, and their mixtures with different fuel particle sizes. Based on the results of thermal analysis, the following characteristics were determined: the temperature at which the coke residue ignition occurs, the temperature at which the combustion process is completed, and the combustion index. An analysis was carried out of the interaction between the fuel mixture components on the characteristics of their combustion for compositions (50% coal and 50% biomass) with a particle size of 100–200 μm and 300–400 μm. The combustion kinetic parameters of individual solid fuels and their mixtures containing 50% coal and 50% biomass are compared. The activation energy for coal combustion was 60.3 kJ mol⁻¹, for biomass 24.6 kJ mol⁻¹, and for mixture 42.5 kJ mol⁻¹. The co-combustion of coal and biomass has a positive effect on the main combustion characteristics of solid fuels. Fuels with particle sizes of 100–200, 200–300, and 300–400 μm were studied at temperatures of 500–800 °C under heating conditions in a heated airflow. Using a hardware-software complex for high-speed video recording of fast processes, the ignition delay times were determined, the values of which for the considered fuels vary in the range from 0.01 to 0.20 s. Adding 50 wt% biomass with particle sizes of 100–200, 200–300, and 300–400 μm to coal reduces the ignition delay times of mixtures by 55, 41, and 27%, respectively. The results obtained can become the basis for the conversion and design of modern power plants operating on solid fuel mixtures to co-combust coal with biomass.

Large city-scale coal-fired combined heat and power (CHP) plants are one of the main contributors to greenhouse gas emissions. The motivation is to find a way to decrease the contributions in the most feasible way possible. The importance of this study is that it presents a methodology for comparing scenarios from both environmental and economic points of view. The scenarios aim to enhance the environmental performance of combustion flue gas-treatment units. The scenarios include installing an advanced electrostatic precipitator (ESP), a hybrid system comprising ESP and a bag filter, a combined cyclone and baghouse filter, a hybrid baghouse filter with novel electrostatic tissue, a wet flue gas desulfurization (WFGD) scrubber, a WFGD with (NH₄)₂SO₄ technology, and fuel conversion (incl. biomass). Each of the scenarios is evaluated according to (a) primary energy consumption, (b) capital (CapEx) and operational (OpEx) costs, and (c) the obtained environmental effect (decreasing emissions of particulate matter (PM), CO₂, SO₂, and NO_x). Adopting biomass waste decreases CO₂ emissions by 50%. PM from the coal-fired boiler with particle filtration is lower compared to biomass but is two times higher than that from natural gas. Using advanced filters for a CHP plant decreases total emissions and PM by 2100–2800%. The largest effect on air quality is achieved by filtration and WFGD, with emissions decreasing by 43%. Primary energy consumption is maximal in fuel conversion and ESP scenarios. The conversion to limestone-based WFGD or the installation of a hybrid filter separately are the most viable options, totaling EUR 14.2 billion of CapEx. However, combining several technologies is essential to increase the quality of flue gas treatment.

The dissolution of bituminous coal at mild temperature was studied using a variety of commercially available coal- and petroleum-derived hydrocarbon fractions, hydrorefined derivatives and blends as solvents. The chemical and molecular composition of the coal, solvents and extracts were characterized by chemical and group analyses, and by IRFT, 1H NMR, GC-MS and liquid chromatography. Low volatile solvents like highly aromatic coal tar (CT), its anthracene fraction (AFCT), petroleum-derived solvent (HGOCC) and binary blends were found to exhibit high performance for coal dissolution into quinoline solubles (to 79‒82%), and the yields of gases being no more than 0.5%. The extracts obtained using CT and AFCT solvents represented pitch-like matter consisting of rarely substituted aromatic molecules with 4‒5 condensed rings. HGOCC extract was much less aromatic, the aromatic rings being highly substituted with fairly large alkyl substituents. The blended solvents yielded more extracts, and their molecular indexes were average between those obtained with each solvent separately. A remarkable finding was that the extracts obtained were characterized by significantly lower content of benzo(a) pyrene (BaP) compared to solvents used, its content further decreased as the time of coal dissolution increased.