Solid Fuel Chemistry最新文献

Ashless extracts, hypercoals, were obtained from Tuvan coals of the Ulug-Khem basin by dissolving them in N-methylpyrrolidone. The yield of the extracts was 27.3–79.4%, and their ash content was 0.5–0.8%. The composition of the products of pyrolysis, carried out at 420°C, of the initial coals and the hypercoals obtained from them was studied. It was found that high volatile bituminous coal (coal from the Elegest deposit) can be extracted most effectively. The qualitative and quantitative compositions of pyrolysis products were not fundamentally different in the initial coals and the corresponding extracts. According to TGA data, the decomposition of extracts (hypercoals) occurred at lower temperatures relative to that of the original coals with a high yield of volatile components.

The influence of torrefaction on the characteristics of binary fuel blends consisting of plant biomass and high-ash carbon-containing technogenic waste is considered. It has been shown that through torrefaction it is possible to compensate for a decrease in the heating value of fuel blends associated with the addition of a high-ash component. A criterion for choosing a torrefaction mode was proposed and a corresponding analytical expression was obtained to calculate the minimum permissible biomass content in the fuel blend. This expression can be used in relation to fuel blends of various types of plant biomass and high-ash carbon-containing waste. Quantitative data demonstrating the improvement of the hydrophobic properties of fuel blends as a result of torrefaction are presented.

The mixtures of graphite and anthracite with lithium carbonate in atmospheres of argon and air were studied using differential scanning calorimetry (DSC). It was found that, in a temperature range of 100–500°C, the weight loss in argon was stronger than that in air. This phenomenon was caused by the removal of oxygen compounds with carbon. Competing processes of the formation of oxygen compounds with carbon and coal and the desorption of oxygen-containing substances occurred in air. The thermal effects for graphite–lithium carbonate systems in argon and in air were compared using DSC and gravimetry curves. It was found that the molar ratio between carbon(IV) and carbon(II) oxides in the reaction products up to 700°C can be estimated at 10 : 1. Endothermic effects of lithium carbonate melting in an argon atmosphere for the mixtures of graphite and anthracite with lithium carbonate were observed at 732 and 727°C, respectively. The peaks of endothermic effects in air did not correspond to the heat absorption curves in argon. The most probable explanations of the observed effects were given: the presence of lithium carbonate and lithium oxide phases and the manifestation of the stretched nature of the pre-transition region of lithium carbonate. Using powder X-ray diffractometry, it was found that the burnout of a carbon phase at 500°C in graphite and anthracite did not lead to a significant change in the interplanar distances in lithium carbonate.

The kinetic features of the decomposition of fuel pellets formed from birch phloem and its composites with the addition of oil-containing waste (OCW) were studied by methods of thermogravimetric analysis carried out in various atmospheric conditions. The characteristic temperature ranges of thermal decomposition of the materials from which pellets are formed were identified. The rates of mass loss and activation energy at the main stages of thermal decomposition were evaluated. And the combustion indices of composite compositions were determined to identify the possibility of using such compositions as alternative fuels. By evaluating activation energies for each stage of sample decomposition, the limiting influence of certain stages of the thermal destruction process was established.

Ash and slag waste from coal combustion is considered as a source of valuable metals. The results of a study of ash and slag waste from CHPPs in Primorye, coal combustion products in the Amur oblast, and some products of ash and slag waste fractionation for gold and scandium content are presented. The concentration levels of these metals were studied by instrumental neutron activation analysis for a preliminary assessment of their possible industrial significance.

A model has been developed for the deposition of rare earth elements with yttrium, trace elements, and nonferrous metals in platform and activated structures of the Upper Amur region. Genetic types of lanthanide enrichment are considered; lanthanides are shown to concentrate nonuniformly in coal seams and in coal combustion products. Light rare earth elements predominate in coals. The capacity of peat and coal for metal extraction from aqueous solutions was proven. Criteria for a preliminary assessment of coal as a raw material for lanthanides were considered and prospects for their identification were analyzed.

Dezful Fractures exert a critical influence on global fluid flow dynamics in carbonate reservoirs. Our study concentrated on fractures in two wells in the Karanj oil/gas field in the southern Embayment of the Zagros Basin, utilizing FMI image logs across the Gachsaran and Asmari Formations. A notable finding was the highest bedding frequency identified in Zone 1-1 of the Asmari Formation. In this rock section, 44 open fractures were identified – 7 medium, 22 minor, and 15 hairline fractures – with dips mainly between 63 to 85 degrees. Notably, the absence of borehole breakout due to low horizontal stress was observed. Instead, induced fractures consistently followed a prevailing N75E/S75W trend, aligning with regional stress patterns. Bed dips ranged from 21 to 57 degrees, averaging at 12 degrees towards S38W, with strikes at N52W/S52E. Zone 1-1 of the Asmari Formation exhibited the highest bedding frequency. Expanding our analysis to the entire Karanj field’s reservoir rock, a total of 703 open fractures were identified, showing dips from 21 to 80 degrees. A significant observation was a potential fault at 1536.5 m, characterized by a strike of N45E-S45W and a dip of 75 degrees in the S45E direction. At depths of 2276.85 and 2279.5 m, fault evidence was also noted in the image logs. This research significantly contributes to our understanding of fracture patterns in carbonate reservoirs, providing valuable insights into fluid flow dynamics.

The effect of adding coal gangue (CG) under different ratios, temperatures and atmospheres on the slagging of wheat straw (WS) combustion was studied in a tubular furnace. At 800°C, there was obvious agglomeration and melting on the ash surface, caused by the reaction of alkali metal elements and alkali earth metal elements with SiO₂ to form low melting point silicate substance, resulted in serious slagging. After adding CG, Al₂O₃ in CG reacted with SiO₂ to form high melting point silicate minerals, which reduced the tendency of biomass slagging. According to the slagging discriminant results of empirical index, sample with 20% CG added combustion in air atmosphere has the lowest slagging tendency. The FactSage results showed that after adding CG, in the whole temperature range, there was no significant difference between the O₂/CO₂ atmosphere and the air atmosphere, but the phase contents were different.

To comparatively analyze the distribution characteristics of spontaneous combustion hazard zones in upside and downside ventilation airflow adopted mining areas, field measurements of O₂ and CO concentrations were determined at the two sides of intake and return airways and the middle of the goaf in 1201 working face of DuanWang Mine; characteristic combustion temperatures and spontaneous ignition kinetic parameters of coal samples were obtained by thermogravimetric analysis; distributions of oxygen and temperature fields under different heat source intensities in upside and downside ventilation airflow adopted working faces were compared by CFD simulation. The results show that the critical positions of the inertisation zone in the goaf corresponding to the intake side, return side and middle of the working face were 200 m, 290 m and 175 m away from the working face, respectively; the moisture evaporating temperature of the coal sample was around 170°C, and the ignition point temperature was about 320°C. When the heat flux was 0 W/m², the areas of spontaneous combustion hazard zones (oxygen volume fraction >8%) in upside and downside ventilation airflows adopted goafs were almost the same; as the heat source increased, the distribution of spontaneous combustion hazard zones in the goaf was more significantly affected by the hot wind pressure, the hazardous area in upside ventilation goaf was about 3 times of that in downside ventilation when the heat flux reached 20 W/m². The simulation laws were consistent with the measured results. The comparative analysis concludes that downside ventilation is conducive to preventing and controlling spontaneous combustion of residual coal in this working face.