Conversion of coal and sludge in the flow of superheated steam
In connection with the significant increase planned by 2020 in the share of coal in power balance of the Russian Federation it is becoming urgent to develop technology of nonfuel use of coal wastes. Increase of extraction and enrichment of coal leads to increased amount of waste of coal industry. The waste contains significant organic component in the amount of economically beneficial to use, but not quite suitable for processing with the use of existing traditional technologies. Such waste are high-ash sludge, waste of coal-concentrating factories and dropout generated in coal mining, as well as low-grade coals. Therefore, of great importance is the development of technology of nonfuel use of organic part of low-grade coals and wastes of coal-mining industry. Gasification with using of superheated water vapor is one of the technologies of processing of such materials with high humidity and ash content. Technology of steam superheating can be based on the burning of stoichiometric oxygen-hydrogen mixture in a steam flow. In relation to raising efficiency of energy devices this technology is under development both in our country and abroad. The advantage of using of superheated water vapor as active agent is confirmed by recent foreign studies. <br> Small-scale experimental studies were conducted aimed on obtaining data necessary to develop industrial technology for steam gasification of low rank coal and sludge. Burning of stoichiometric mixture of hydrogen and oxygen was used for steam overheating at testbed system. Temperatures of overheated steam and gasified sample were measured using thermocouples. Flowing gas analyzer Test-1 was used to measure concentration of gas phase components Н2, CO, CO2 in cooled gasification products. Convection heat transfer coefficient of granular material with overheated steam was determined using data of temperature measurements. Dependences of mass rates of reactions on time at different steam temperatures were determined using data of temperature measurements. In present paper for the first time burning of stoichiometric mixture of hydrogen and oxygen was used for steam overheating at study of steam gasification. Obtained data will be used to develop industrial technology for steam gasification of waste of coal-mining industry. Small-scale experimental studies and computational modeling allow us to reduce time of technology development and to cut down expenses. In conclusion it can be noted that the obtained experimental data will be used for selection of the technological scheme of process of layering conversion of carbon-bearing materials in a superheated steam.