Control of characteristics of closed gas turbine plants of submarines propulsion complexes

Подводная техника особенно нужна при работе и снабжении подводными судами объектов на Арктическом шельфе вдоль Северного морского пути, связанного с преодолением ледовых полей. Среди различных типов энергетических установок для подводной техники перспективны замкнутые газотурбинные установки (ЗГТУ), способные в одноконтурном варианте работать на углеводородных типах топлива. В качестве окислителя можно использовать воздух, который на судах можно хранить в сжатом виде. В этом случае не нужна специальная береговая инфраструктура, ограничивающая дальность плавания подводной техники. За основу базовой схемы ЗГТУ принят газотурбинный двигатель (ГТД) с регенерацией (Р) теплоты, как более экономичный по сравнению с ГТД простого цикла, и схемы которого характерны для микрогазотурбинных двигателей. Также рассмотрены ЗГТУ с турбокомпрессорным утилизатором (ТКУ) и регенерацией теплоты как более экономичные и обладающие удельной мощностью в 1,3…1,5 раза большей, чем в ЗГТУ с Р. Определены характеристики ЗГТУ на переменных режимах, так как подводная техника используется при исследовательских, технологических и транспортных работах при частичных нагрузках и различных видах нагружения. Для улучшения экономичности ЗГТУ на режимах частичного нагружения предложено применить регулируемый сопловой аппарат (РСА) в свободной силовой турбине. На частичных нагрузках посредством РСА можно перераспределить теплоперепад между турбинами, изменить расход газа через турбины, приблизить регулирование к количественному типу. При этом наблюдается увеличение эффективного КПД относительно других способов регулирования при уменьшении мощности двигателя и рост начальной температуры газа, который приближает параметры рабочего цикла двигателя к номинальным значениям. Underwater equipment is especially needed when operating and supplying objects by submarines on the Arctic shelf along the Northern Sea Route associated with ice fields overcoming. Among the various types of power plants for underwater equipment, closed gas turbine plants (CGTP) are promising, capable of operating in a single-circuit version on hydrocarbon types of fuel. Air can be used as an oxidizing agent, which can be stored compressed on ships. In this case, there is no need for a special coastal infrastructure that limits the range of navigation of underwater equipment. A gas turbine engine (GTE) with heat regeneration (R) is adopted as the basis for the basic scheme of CGTP, as it is more economical in comparison with a simple cycle GTE, and the schemes of which are typical for microgas turbine engines. Also considered are CGTP with a turbocompressor utilizer (TCU) and heat regeneration as more economical and having a specific power 1.3...1.5 times higher than in CGTP with R. The characteristics of CGTP in variable modes are determined, since underwater equipment is used in research, technological and transport works at partial modes and various types of loading. To improve the efficiency of CGTP in partial loading modes, it is proposed to use a variable area nozzle (VAN) in a free power turbine. At partial loads, by means of VAN, it is possible to redistribute the heat drop between the turbines, change the gas flow rate through the turbines, and bring the regulation closer to the quantitative type. At the same time, there is an increase in the effective efficiency relative to other control methods with a decrease in engine power and an increase in the initial gas temperature, which brings the parameters of the engine operating cycle closer to the nominal values.

OPERATION OF ELECTRIC HEAT-GENERATION GAS TURBINE PLANTS OF COMPLEX CYCLES ON NOMINAL AND VARIABLE MODES

The results of research and development of cogeneration gas turbine engines (GTE) of complex cycles are presented. It is shown that the use of an overexpansion turbine (OT) in a gas turbine engine makes it possible to increase the efficiency of the engine on a par with the use of heat regeneration (R). The combination of these two methods in a GTE with OT and R provides a further increase in the engine's efficiency. It has been established that at partial loads, each design scheme has its own patterns of change in engine characteristics, which determine the field of application of cogeneration gas turbine engines. Examples of the possibilities of changing the working process in the engine are given, which allow to control the energy flows in the cogeneration power plant.

Analysis of the secondary circuit of a gas-cooled fast reactor

The article focuses on a power conversion system for a gas-cooled fast reactor working with helium. The power conversion system, i.e., secondary and possible tertiary system of a power plant, is used to convert heat generated by nuclear fission into electrical energy. The presented research deals with the conceptual design of this system, mainly its secondary circuit, which is assumed to be a Brayton cycle. Several concepts are evaluated, including single and staged compression and possible heat regeneration. The goal of the work is to select the main parameters of such a cycle that would not only be ideal in terms of efficiency, but would also allow decay heat to be used and further converted into electricity. In this way, the secondary cycle could be used as an additional safety system for the nuclear power plant.

Improvement of power efficiency and environmental safety of ship boilers

The article focuses on the methods of reducing nitrogen oxide emissions that are important to consider and apply in operation of ship boilers and thermal power plants, along with other activities aimed to protect the environment. Nitrogen oxide emissions can be restrained by using the technological (primary, in-process) operations. Flue gas recirculation is the most popular method of restraining nitrogen oxide emissions in oil-gas boilers, reducing the temperature and nitrogen oxide concentration in flue gases. Besides affecting the environment, the combustion products recirculation greatly lowers the technical and economic performance of the boiler by decreasing its performance that is why using the method remains limited. There has been described the scheme of flue gas recirculation in the ship auxiliary boilers that ensures reduction of nitrogen oxide emissions and increase in efficiency of boiler furnace. It has been proposed to combine steam and carbon dioxide fuel conversion with power combustion and thermochemical heat regeneration. Thermodynamic feasibility of combustion product recirculation in ship auxiliary boiler has been given. Using the power and stoichiometric analyses of reference liquid fuel combustion, the possibility of fuel conversion has been illustrated for the case when both fuel and recirculation gases are supplied into reburning zone of the furnace. The calculations determine air oxygen ratio for reburning and oxidative zones, flue gas recirculation factor and furnace efficiency change at thermochemical heat regeneration. The study results are proposed to use in non-stoichiometric and staged fuel combustion.

Complete power cycle exhaust heat regeneration and second law logic

It is demonstrated, given a sufficiently large positive excess enthalpy of solution reaction between a molecular solid solute and a low boiling point solvent, that the differential in excess enthalpies of solution between the reaction in the solvent's dense liquid and expanded supercritical states will enable the solution, when used as the working fluid in a closed condensing power cycle, to attain complete exhaust heat regeneration. Xenon is used as the solvent to demonstrate the potential. Errors in 18th century logic that helped establish the second law are explained.

Thermodynamic and Economic Analysis of Trigeneration System Comprising a Hierarchical Gas-Gas Engine for Production of Electricity, Heat and Cold

This paper presents the results of analysis of energy and economic efficiency of the hierarchical gas-gas engine, with a note that a trigeneration system was analyzed, in which the production of electricity, heat and cold are combined. This solution significantly increases the energy efficiency of the gas and gas system compared to a system without cold production. The analysis includes a system comprising a compressor chiller which is driven by an electric motor in the system, as well as a system applying the mechanical work that is carried out via a rotating shaft of rotor-based machines, i.e., a gas turbine and a turboexpander. The comfort of the regulation of the refrigerating power rather promotes the use of a solution including an electric motor. Analysis contains also a schematic diagram of the system with a absorption chiller, which is driven by low-temperature enthalpy of exhaust gases extracted from a hierarchical gas-gas engine. Application of turboexpander with heat regeneration in the trigeneration system is also analyzed. Based on the multi-variant economic and thermodynamic calculations, the most favorable system variant was determined using, among others, the specific cost of cold production.