Coal mining is accompanied by the release of coal mine methane. Its emissions into the atmosphere within methane-air mixture have a negative impact on the ecological situation. The modern approach involves the use of methane-air-mixture for heat boilers or units to generate electricity. For the generation of heat and electrical energy the coal mine methane could be used in cogeneration gas turbine plants with an altered sequence of processes. Thermo — and gas dynamics studies were conducted in a wide range of parameters of gas turbine plants. For small power plants recommended are: 2.8 compression ratio, turbine inlet — 1173 K, gas cooler inlet temperature — 303 K, 0.8 regeneration ratio. In this case the electrical efficiency of gas turbine plant is 25–26% and even 63–64% if produced heat is counted. Cogeneration gas turbine plant with an altered sequence of process has smaller capital and operating costs compared to traditional gas turbine unit. The use of methane-air mixture as fuel in such gas turbine units increases the profitability of coal mining and improves the ecological situation in the region.
In the present work mathematical modeling of a CHP system based on Micro Gas Turbine (MGT) with Inverted Brayton Cycle (IBC) (also known as subatmospheric) is provided. Nominal electric power of the facility is 10 kW. Engineering calculation based modeling is conducted to determine optimal parameters of each component, electrical and total efficiency at full load. Further dynamic modeling is provided for the components with determined optimal parameters. With chosen optimal parameters of the scheme components and coolant temperature the dynamic (time-dependent) modeling of disturbance from the nominal state with no control, ramp down and ramp up of power load (a) and heat load (b) with the activated control system was provided. An iteration based approach of MGT modeling is suggested. The difficulties in the system control under reduction of heat consumption are revealed and challenged. The final objectives of the research are comparison of the IBC with the conventional Brayton cycle for MGT application from the electric efficiency, dynamic behavior and controllability points of view, creation of the control system for such a facility.
Improving the ecological condition of water basins is closely connected with reconstruction of systems for water disposal and wastewaters treatment. Modernization of old-fashioned wastewater treatment plants, and operating cost saving is possible by means of transition to effective technological solutions, including the process of substrate anaerobic digestion with production of biogas and raw material for high-quality fertilizers. Biogas can be used in power stations for production of thermal and electrical energy required for wastewater treatment plant needs. This energy also reduces the plant’s operating cost. A scheme of a module for anaerobic digestion has been proposed, and application of utilization cogeneration gas-turbine units with an external supply of warmth to cyclic air has been justified. Optimum parameters of utilization gas-turbine units have been determined. At air temperature in front of the turbine 1190 K the compression ratio in a cycle is equal to 4,2, electric efficiency — 0,313, the general one taking into account the developed warmth — 0,872. In some cases the gas-turbine unit can be manufactured without booster fuel compressor.
This paper’s aim is enhancement of efficiency for fans adjusting by turn of rotor blades. A high load axial fan and a fan with decreased rotor’s pitch chord ratio by reduction of blades number were investigated. Have been performed tests of the fan with design characteristics as follows: theoretical head coefficient Ht = 0,3, mass flow rate Ca = 0,4, hub’s relative diameter ν = 0.6, and with blades, graded on the law of permanent circulation. The area of effective adjustment was estimated by the performance factor value η* ≥ 0,8. When changing the stagger angles in a wide range from 26° to 70°, the area of highly economical work was in variation ranges 0,26–0,78 for the mass flow rate Ca , and 0,24–0,5 for the theoretical head coefficient Ht accordingly. Tests of fans with a reduced blades number in the rotor (12 instead of 16 for the original fan) has showed that under the same stagger angles the fan’s high-efficiency operating mode is approximately in the same range of Ca variation at slightly reduced values of theoretical head coefficient. Maximal performance factor has increased on 2.5%. Decreasing the number of rotary blades, simplifying the turning mechanism and reducing the weight are possible in the design of fans with increased values of aerodynamic load coefficients.
Обосновано использование древесных отходов для получения генераторного газа с последующей выработкой электрической энергии. Представлена схема энерготехнологической установки с газификацией древесных отходов, включая предварительную подготовку сырья. Рассмотрена высокотемпературная сухая очистка генераторного газа, позволяющая упростить конструкцию установки и использовать теплоту выходящего из газификатора газа. Рассмотрена нетрадиционная схема газотурбинной установки с воздушной турбиной и с давлением в камере сгорания, близким к атмосферному. Проведена оптимизация цикла рассматриваемой газотурбинной установки. Представлены результаты расчетов основных элементов установки.
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