Study of flare gases utilization technology at mining sites

Introduction. Flaring of gas in flares is one of the main factors of global warming and climate change. Flaring is inevitable and is an integral part of technological processes as a measure to ensure their safety and continuity. On the other hand, flare gases, in particular methane gas flows from coal mines, are considered as high-value products that can be used as raw materials for the production of synthetic fuels and hydrogen. The purpose of the study. Evaluation of existing and creation of new scientific and technological solutions for obtaining products with added value during the utilization of flare gases at mining facilities. Materials and methods. The developed technology consisted of two main stages. For preliminary cleaning of flare gas, the amine cleaning process using diet was used. The intermediate component for extracting valuable products from the purified flare gas is syngas. H2 was obtained through a membrane separator after steam reforming of methane. The modeling was carried out in the Aspen Hysys software environment, which is one of the most effective and flexible simulators for modeling thermochemical processes. The feedstock for the process under consideration was a stream of flare gas from coal mines, mostly consisting of methane (the mole fraction of CH4 is 0.85). An economic analysis of the known technologies for converting flare gases into valuable products (GTG, GTE, GTL) was also carried out in comparison with the developed technology based on the use of the capital return concept. Results and discussion. The resulting process model contained a flare gas cleaning unit and a methane steam reforming unit. Based on the process flow charts, flare gas conversion models into valuable components with an input feedstock flow rate of 4500 m3/h were obtained. The yield of the final product (H2 ) according to the model calculations was 1864 m3/h. An economic analysis was conducted comparing the gas-to-liquid (GTL), gas-to-electricity (GTG) and gas-to-ethylene (GTE) technologies with the hydrogen production technology being developed. Based on the economic analysis, it was determined that the investment amount in the project is not high, less only in the low-tonnage GTL technology, but the best return on investment indicator was obtained. Conclusion. The obtained models allow to perform primary calculations of technological processes, as well as to estimate operating costs and capital cost of the modeled installations. Resume. The results of the work show that projects for conversion of flare gas into valuable products for mining enterprises in Russia can fully satisfy the three-sphere structure of sustainable development proposed by René Passet, according to which development can be considered sustainable only if it simultaneously has a positive social, environmental and economic impact.