The so-called expander-generator sets (EGS) have found some application in Western Europe. Their operation is based on a drop in the pressure of natural gas (NG), which comes to a power-generating or industrial facility, and which used to be lost in choking devices of the gas distribution station (GDS) of these facilities. The capacity of such sets, e.g., in Germany, is limited to just tens to hundreds of kilowatts. The benefit for their owners lies in obtaining, according to the German law, markups to the cost of energy released to electricity consumers. However, the economic environment in place in Russia is somewhat different.According to the author, the limited number of EGS in Russia’s power industry, as well as cases of their decommissioning, are due to the lack of evidence of their thermodynamic or technical-economic efficiency, or even worsening economic conditions at facilities, where those were implemented. Besides, the facilities in question have to be provided with considerable specific conditions. These include a relatively high value of initial NG pressure at the input of EGS, its considerable flow rate and the possibility of NG heating at the input of EGS. This necessity to heat NG upstream the EGS is determined, on the one hand, by the intention to enhance the EGS capacity, and on the other hand, by having to comply with requirements imposed by the EGS manufacturer regarding the temperature values upstream and downstream the EGS. Without a required source of heat of relevant parameters at the facility, application of EGS turns out to be impossible, altogether. An interest in EGS in Russia arose due to construction and commissioning (first, at CHPP-21, and later at CHPP-23 of Mosenergo) of two power-generating centers, each equipped with two 5 MW EGS. Since then, a large number of articles have been published, and numerous theses have been defended based on the studies undertaken, mostly of analytical nature. Yet, those publications have not considered, for a real expander, matters of effects produced by the relation between the absolute electrical efficiency (ηe) of CPP and/or CHPP and the efficiency ratio of expander (ηer ), the NG expansion ratio (δ). Conditions, at which heating NG upstream the EGS is expedient, have not been established, either, whereas these are the factors crucial for economic feasibility of a TPP to be equipped with EGS.
The current operating regimes for turbines of this type and their possible long-term uses affect the choice of a rational option for the modernization of the low-pressure cylinder (using a three stage rotor with reduced lengths of the working blades in the last stage or removal of working blades in the last stages), which should be made taking into account the specific conditions at each given heating and electric power plant. Studies of T-250/300-240 turbines at the heating and electric power plant TÉTs-23 of JSC "Mosénergo" operating without working blades in the last stages of the low-pressure cylinder are described. These demonstrate increased efficiency during both summer and winter operation under the conditions at this plant. The condition of the trailing edges of the working blades in stages 30 and 39 is found to be excellent, but erosion of the steam inlet deflector cone in the region of the feedthrough for the low-pressure cylinder along the direction of the twist in the flow is observed. It is proposed that an alignment module be installed at the outlet of the low-pressure cylinder for protection from overload, the compressor effect, and root eddies. For further increases in efficiency it is proposed to examine the feasibility of raising the maximum allowable temperature of the exhaust at the low-pressure cylinder of the modernized turbine.
Hydrogen energy combines a set of technologies for the production, transportation, storage and use of a versatile secondary energy carrier — hydrogen. The energy use of hydrogen is formed from the possibilities of environmentfriendly generation of electricity and long-term storage without loss, including on a large scale. Questions related to the consumption of hydrogen as a promising environment-friendly and versatile energy carrier and energy storage in various sectors of the national economy were formulated in the early 70s of the last century after the first oil fuel crisis. It has become obvious that it is necessary to develop new, ecologically optimal energy technologies based on the use of renewable energy sources, nuclear energy, coal and versatile environment-friendly energy carriers, making it possible to replace non-renewable energy resources as these are depleted and become more expensive. Hydrogen as a secondary energy carrier reveals its potential in a global strategy for sustainable energy development in the 21st century, which confronts the challenges of irreversible climate change, unsustainable oil production and increasing environmental pollution. Hydrogen can play a key role in mainline transportation by road and rail, in coastal and international shipping, in air transport, as well as in long-term and seasonal storage of electricity in networks, relying mainly on local renewable energy sources and local raw materials. The decisive element in the commercialization of hydrogen fuel technologies in Russia at the current stage is the formation of cost-effective hydrogen-transport-energy complexes, in particular, within power generating facilities.
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