FUEL AND ENERGY COMPLEX OF IRKUTSK REGION IN CONTEMPORARY CONDITIONS. PROBLEMS AND PROSPECTS FOR DEVELOPMENT

The article discusses the formation of the power industry of the Irkutsk region (IR), the structure of its fuel and energy complex (FEC). The modern fuel resource base of the region and its prob-lems are analyzed. All components of the fuel and energy complex are considered: oil and gas, coal and electric power. The most problematic areas in each of the components of the fuel and energy complex are highlighted and some recommendations for their elimination are proposed. Also shown are new risks and threats to IRs associated with the fuel and energy complex region.

Study on the technology of enhancing permeability by deep hole presplitting blasting in Sanyuan coal mine

To reduce gas disasters in low permeability and high gas coal seams and improve gas predrainage efficiency, conventional deep hole presplitting blasting permeability increasing technology was refined and perfected. The damage degree of coal and rock blasting was quantitatively evaluated by using the value range of the damage variable D. According to the actual field test parameters of coal seam #3 in the Sanyuan coal mine, Dlim = 0.81 ~ 1.0 was the coal rock crushing area, Dlim = 0.19 ~ 0.81 was the coal rock crack area, and Dlim = 0 ~ 0.19 was the coal rock disturbance area. The blasting models under different blasting parameters were established by ANSYS/LS-DYNA software. The influence radius of single-hole blasting was 3.1 m, the hole diameter of double-hole blasting was 113 mm, the hole spacing was 5.5 m, and the delayed blasting time was 25 ms. According to the numerical simulation results, the determined parameters were tested on the working face of the 1312 transportation roadway in coal seam #3 of the Sanyuan coal mine. The results show that after blasting, the permeability of the original coal seam was increased by more than 30 times, the gas concentration was increased by 2.16 times, and the single hole purity and mixing volume were increased by 4.73 and 4.27 times, respectively. The positive effects of deep hole presplitting blasting permeability enhancement technology on the pressure relief and permeability enhancement of a low pressure and high gas coal seam were determined.

Study on the Technology of Enhancing Permeability by Millisecond Blasting in Sanyuan Coal Mine

To reduce gas disasters in low permeability and high-gas coal seams and improve gas predrainage efficiency, conventional deep-hole presplitting blasting permeability increasing technology was refined and perfected. The numerical calculation model of presplitting blasting was established by using ANSYS/LS-DYNA numerical simulation software. The damage degree of coal and rock blasting was quantitatively evaluated by using the value range of the damage variable D. According to the actual field test parameters of coal seam #3 in the Sanyuan coal mine, Dlim = 0.81–1.0 was the coal rock crushing area, Dlim = 0.19–0.81 was the coal rock crack area, and Dlim = 0–0.19 was the coal rock disturbance area. By comparing and analysing the damage distribution nephogram of coal and rock mass under the influence of different millisecond blasting time interval and the blasting effect of simulation model, the optimal layout parameters of multilayer through cracks were obtained theoretically. And, the determined parameters were tested on the working face of the 1312 transportation roadway in coal seam #3 of the Sanyuan coal mine. The permeability effect was compared and analysed through the analysis of the gas concentration, gas purity, and mixing volume before and after the implementation of deep-hole presplitting blasting antireflection technology, as well as the change of gas pressure, attenuation coefficient, permeability coefficient, and other parameters between blasting coal seams. The positive role of millisecond blasting in reducing pressure and increasing permeability in low permeability and high-gas coal seam were determined.

The structural transformation and reburning characteristics of gas coal in Ningwu coalfield fire

With the expansion of the scale of coal mining, the safety problems caused by the reburning of coal are becoming more and more serious. In this paper, the pyrolysis characteristics of gas coal and the exothermic characteristics of reoxidation of residues were studied by using a synchronous thermal analyzer. The functional groups of pyrolysis residues were tested, and the group content and characteristic structural parameters were calculated based on quantum chemistry method. The results show that with the increase of pyrolysis temperature, Volatile maximum separation rate (Vmax) and the change in the residual weight of the coal sample (ΔWvp) increase. The increase of temperature will lead to the decrease of hydroxyl and aliphatic hydrocarbon content in coal, and the increase of aromatic hydrocarbon. With the deepening of pyrolysis, the ignition point temperature of coal samples decreases first and then rises, the combustion intensity and combustion concentration are strengthened. The pyrolysis results show that 462.8°C is the critical temperature for the transition during pyrolysis. The ignition point of the residue is less affected by the pyrolysis conditions, and the ignition temperature of the raw coal and the pyrolysis residue varies within 330.57°C–334.98°C.

CLASSSFICATION OF COAL RESERVES AT THE TYAGLIV AND LYUBELYA FIELDS OF THE SOUTH-WESTERN COAL-BEARING REGION OF THE LVIV-VOLYN BASIN BASED ON THE MAIN NATURAL INDICATORS

A geological-statistic analysis of commercial resources and the predictive coal-bearing potential of the fields of the South-Western coal region, the principal promising part of the Lviv-Volyn Coal Basin, has been carried out. Based on the detailed analysis and systematization of data from prospecting and exploratory-assessment works regarding the depth of occurrence and the thickness of coal seams, ash content, sulphur content and grade composition of coal, resources of the Tyagliv and Lyubelya fields has been re-evaluated. These characteristics have been studied by discrete intervals. Re-evaluation of resources and their classification were carried out for every coal seam, the mine field, the field, and the coal-bearing region on the whole. In total, the analysis was performed for 24 coal seams. By the depth of occurrence of coal seams the majority of coal reserves at the Tyagliv and Lyubelya fields belong to the group of 600-900 m. The majority of predictive resources of coal within the Lyubelya field (6.6%) falls to the group of 900-1200 m. According to the thickness of coal seams, the most of the balance and overbalance reserves at the Tyagliv field is attributed to the groups of 0.61-0.80; 0.81-1.00 m, and at the Lyubelya field to the groups of 0.81-1.00; 1.01-1.20; 1,21-1.50 and over 1.5 m. Within the Lyubelya field, the predictive resources of coal are contained in the group of 0.81-1.00 m. According to the value of ash content, 50 % of balance and overbalance reserves of coal at the Tyagliv field are related to the groups of the medium-ash and ash coal. At the Lyubelya field, the most of coal reserves (66.4%) also corresponds to the group of medium-ash coal, and predictive resources — to the groups of medium-ash (43.1%) and ash (53.1%) coal. According to the content of the mass fraction of sulphur, at the Tyagliv field the balance and overbalance reserves of high-sulphur coal prevail, with the amount of sulphur, low-sulphur and medium-sulphur coal being at the equal ratios. At the Lyubelya field, high-sulphur and low-sulphur coal prevail almost at the equal ratios. Regarding predictive resources, the group of high-sulphur coal prevails within the field. The coal seams within the Tyagliv and Lyubelya fields differ from analogous ones in the industrial part of the basin by the higher thickness and the area of distribution. The depth of occurrence of the seams increases for 15-300 m. Coal in the fields of the South-Western coal region has higher quality and the least ash content. According to brand composition of coal, the technologic groups of gas coal, gas-fat coal and fat coal (according to the Ukrainian classification) prevail at the Tyagliv field. It is proved that gas coal is suitable for coking. At the Lyubelya field, fat, coke-fat and coke coal prevail. Сoke coal comprises almost a half of the reserves. In the region, reserves and resources of coal are estimated to be over two billion tons, which exceeds in two times the residual reserves of the commercial part of the basin. The analysis of the raw material base of the Tyagliv and Lyubelya fields, estimation of reserves and evaluation of coal resources have a great importance for developing and working-out of the feasibility study for their commercial development.

CONVERSION OF LOW AND MEDIUM POWER BOILERS FOR COMBUSTION OF SOLID FUEL BIOMASS

The paper analyzes the existing fleet and the possibilities of replacing anthracite and natural gas boilers of low and medium capacity and substantiates that the reconstruction with conversion to biomass is appropriate for boilers with a thermal capacity of more than 5 MW. The main problem is the reduction of heat perception of furnace screens and increase of heat removal to the convective pass due to the increased specific yield of biomass combustion products. Based on the analysis of changes in the nature of combustion processes and redistribution of heat exchange in the boiler, it was determined the criteria for the possibility of converting boilers from fossil fuels to biomass with maximum use of available equipment and the most acceptable fuel for this - agricultural pellets and wood waste. Technical solutions for the reconstruction of a boiler with a dense bed with a steam capacity of 20 t/h on anthracite (24 t/h on natural gas) have been developed and calculated with transfer to burning of granules of biomass and/or gas coal without change of dimensions of a fire chamber and without loss of thermal power due to compensation of the lowered heat absorption of a fire chamber by increase of a surface of a water economizer with corresponding decrease in an air heater. Technical solutions were used during the reconstruction of 4 boilers "Babcock-Wilcox" of Khorostkiv Sugar Plant. Co-combustion of biofuel pellets with coal is implemented in the range of components share from 0 to 100%. When burning granules, underburning in the fly ash is almost absent, ash deposits on convective surfaces are self-cleaning for several hours of work on gas coal. The solutions developed allowed to solve the problem of renovation of old boilers with the expansion of their fuel base and improvement of environmental performance through the use of biomass. Bibl. 18, Fig. 3, Tab. 4.