Hydrogen-oxygen Steam Generator Research Articles

Investigation on combustion efficiency of the hydrogen–oxygen mixture at various pressures and excess oxidizer based on experimental and theoretical studies

One of the ways to improve the efficiency of power plants, including nuclear power plants, can be the use of hydrogen energy complexes and hydrogen-oxygen steam generators in their composition. This is done by electrolysis production of hydrogen and oxygen and their further use in technological schemes of power units in the form of thermal energy. Fundamental in assessing the efficiency of such use of hydrogen technologies is the efficiency of hydrogen combustion in oxygen medium under different schematic-parametric conditions. In this paper combustion processes were studied in terms of evaluating efficiency of the hydrogen-oxygen mixture combustion at various pressures and an oxidizer excess. For this purpose, a calculation model of combustion processes of the hydrogen-oxygen mixture, including heat and mass transfer under the boundary conditions of the experiment was verified on the basis of the experimental data, obtained at 4-section flame tube. Has shown that increasing the pressure of the combustion products leads to a noticeable decrease in hydrogen underburning. The maximum effect is observed in the third section of the flame tube (a reduction by 56.72%), and the minimum effect is found in the first section (a reduction by 7.58%). In this case, the average specific reduction in hydrogen underburning in sections I-IV of the flame tube within the considered pressure ranged between 8.13, 17.41, and 31.34%/MPa, respectively. An increase in an oxidizer excess lead to a regular decrease in hydrogen underburning. In this case, the maximum decrease in hydrogen underburning is achieved with an oxidizer excess ratio of 2 in the third section of the flame tube (a reduction by 58.86%). At the same time, an increase in the positive effect of increasing pressure is observed. In this case, in the first two sections of the flame tube, the greatest dependence on the increase of an oxidizer excess ratio is observed. Thus, the maximum relative reduction in hydrogen underburning is achieved at the pressure of 6 MPa, and as a result amounts to 24.46% and 43.5% with the oxidizer excess ratio at 1.5 and 2, respectively.

Compact and fast-response 150 kW hydrogen-oxygen steam generator

Burning of hydrogen produces high-grade heat, which can be used for zero-carbon power generation and/or heating and in heat-intensive industries. In combination with water electrolysis, hydrogen combustion provides efficient energy storage method for variable renewables. Hydrogen combustion systems are compact, powerful and highly maneuverable in comparison with fuel cells. We present experimental results of fire tests of a water-cooled hydrogen-oxygen steam generator (HOSG). This fast-response device has start-up time less than 15 s to thermal capacity of 147 kW. Temperature of generated steam is within 1173–1273 K, parameters of steam and energy conversion efficiency can be adjusted the water-to-hydrogen ratio. The maximum efficiency of conversion of chemical energy of hydrogen into enthalpy of steam is 98.7%.

Technical and economic optimization of the hydrogen-thermal energy storage at nuclear power plant

The article discusses and optimizes the system developed by the authors based on closed-cycle hydrogen-thermal storage using external and built-in hydrogen-oxygen steam generator. On the basis of the finite element method with the use of the ANSYS software package, the process of starting up and entering the operating mode of the steam generator was simulated. The distribution dynamics of temperature fields and thermomechanical stresses in the walls of the combustion chamber are shown. When using the built-in combustion chamber, the maximum wall temperature after reaching the operating mode was 391°C and for 179°C for the external combustion chamber. The distribution dynamics of thermomechanical stresses fields practically corresponds to the distribution dynamics of temperature fields. In this case, the thermomechanical stresses for the built-in combustion chamber amounted to 219MPa, for the external – 195MPa. Taking into account the estimation of the calculated lifetime, an optimization technical and economic analysis of the efficiency implementation of hydrogen-oxygen steam generator was carried out. The use of built-in hydrogen-oxygen steam generator makes it possible to increase the efficiency of off-peak electricity use by 14.76% and to reduce the cost of peak electricity production by 18.4%, taking into account the lifetime.

Primary frequency regulation in the power system by nuclear power plants based on hydrogen-thermal storage

According to the Technical Requirements for Generating Equipment of Participants in the Wholesale Market of the Unified Energy System (UES) of Russia, from 2016 to participate in the general primary frequency regulation (PFR), the maneuverable characteristics of generating equipment of nuclear power plants with VVER reactors put into operation before 2009 should ensure frequency deviations guaranteed realization of the required primary power for loading up to 2% of the nominal electric power. For this, the current capacity of the reactor installation should be maintained at a level of not more than 98% of the nominal thermal power. The fulfillment of this requirement significantly reduces the installed capacity utilization factor (ICUF) of reactor plant.In addition, at present in the UES of the Russian Federation there is a tendency towards an increase in the deficit of peak and half-peak capacities. The majority of fossil fuel-fired thermal stations are switched to the half-peak mode, which negatively affects their efficiency and reliability. In addition, the rise in price of natural gas makes it more profitable to sell it abroad instead of burning at power plants. On the other hand, an increase in the share of nuclear power plants is observed in the UES, which exacerbates the problems associated with the passage of minima and maxima of the daily load in the power system, due to the economically and technically justified need to load NPPs with maximum CUF.The authors developed an approach to solving this problem by combining NPPs with an environmentally friendly energy source – an autonomous hydrogen power complex (AHPC), which includes heat accumulators and an additional multifunctional steam turbine unit. The developed energy complex will allow energy to be accumulated during hours of minima load in the power system due to the electrolysis of water to produce hydrogen and oxygen, as well as the accumulation of hot water in the storage tanks. The accumulated energy can be used to generate super-nominal electricity to cover the half-peak load zone in the power system. In addition, the presence of a low-power steam turbine installation will ensure uninterrupted power supply to consumers of their own needs at the NPP by using the energy of the residual heat from the reactor when the station is completely de-energized.Based on the proposed power complex, a method has been developed to ensure the participation of NPPs in the PFR in an energy system with a constant CUF. To assess the effectiveness of the proposed solution, a methodology for thermodynamic analysis of the power complex based on the combination of NPPs with AHPC was developed. The dependence of the required hydrogen fuel consumption and the efficiency of using off-peak electricity on the temperature of the feed water supplied to the hydrogen-oxygen steam generator from the hot water tanks is constructed.Based on the results obtained, the technical and economic efficiency of the developed power complex is considered. The accumulated net present value was determined depending on off-peak electricity tariffs with three variants of the forecast dynamics of the half-peak electricity tariff, taking into account natural gas savings, reduced investment in NPP safety systems and the economic effect of ensuring the participation of NPPs in the PFR with the plant load at 100%.

Development of an automated system for experimental investigation of thermal processes in a hydrogen-oxygen steam generator

The paper presents the results of the development and creation of an automated system of scientific research (ASSR). It provides experimental studies of heat and mass transfer processes in a hydrogen-oxygen steam generator (HOSG). The most relevant fields of application of hydrogen-oxygen steam generators are considered. The paper discusses the most relevant areas of application of hydrogen-oxygen steam generators, scientific and technical barriers to the introduction of technology and the features of the construction of ASSR for experimental research. The schematic diagram of the primary measuring transducers and the control mechanisms of the experimental stand are described. The choice of the configuration of the automated control and measurement system is justified from the point of view of completeness and reliability of the obtained data.

Features of thermodynamic and thermal processes in hydrogen combustion units and systems on their basis

The main types and designs of hydrogen combustion units (HCU), including hydrogen-oxygen steam generators, superheaters and air heaters of various power levels, are considered. The main problems arising in the development, creation and testing of such installations are determined, including the problems of cooling the most heat-stressed units, mixing of the main components of the fuel and oxidizer, mixing of high-temperature combustion products and ballasting components, problems associated with the completeness of hydrogen combustion and ensuring safety during operation.

Comprehensive methodology for identifying tariff zones of efficiency of hydrogen-thermal accumulation system at the NPP

In countries with developed nuclear energy, there are problems associated with non-uniformity of the daily electricity load, due to the economically justified need to load nuclear power plants with a maximum installed capacity utilization factor. This is due to the cheapness of nuclear fuel compared to organic and, at the same time, high investment compared to thermal power plants, as well as the presence of technological limitations on maneuverability. Most organic fuel thermal power plants are switched to half-peak mode, which negatively affects their efficiency and reliability.In addition, the ever-increasing requires on the level of safety negatively affect the economic competitiveness of nuclear power plants. Improving safety through the introduction of passive heat removal systems of the reactor core is provided for in new NPP projects. These systems have several disadvantages: maintenance costs; a significant increase in capital investment; emergency cooling mode.To solve these problems, the authors developed a system of hydrogen-thermal accumulation, which, when combined with a nuclear power plant, allows one to accumulate cheap energy during the hours of a decrease in load in the power system due to electrolysis of water to produce hydrogen and oxygen, and thermal accumulation of hot water in heat-insulating tanks. Thanks to the use of hot water tanks, investment in the accumulation system is significantly reduced. Thanks to the use of a hydrogen-oxygen steam generator, the opportunity to generate an additional main steam and to use it in the additional steam turbine unit appears, which will allow to avoid costly modernization of the main equipment of the nuclear power plant and reducing its lifetime. The presence of a low-power steam turbine unit as part of the accumulation system ensures uninterrupted autonomous power supply to consumers of the NPP own needs due to the possibility of using the energy of the reactor residual heat, when the station is completely blackout. The method of combining the hydrogen complex with thermal accumulators is completely new and has no analogues.The economic efficiency of the developed energy complex has been investigated. The accumulated net present value was determined depending on the off-peak electricity tariff for the three options of the half-peak electricity tariff, taking into account possibility to refuse expensive heat exchangers of the passive heat removal systems. It is shown that the use of the proposed scheme is advisable in regions with off-peak electricity tariffs in the range 0–0.32 cents/kW·h, 0–0.8 cents/kW·h and 0–1.25 cents/kW·h, respectively, depending on the forecast dynamics of the half-peak electricity tariff. The average payback period of the accumulation system for given conditions is equal to 3–15 years.

Research of the application of hydrogen as a fuel to improve energy and environmental performance of gas turbine plants

THE PURPOSE. To consider various variants of thermal schemes of power plants and to assess the main technical and economic parameters. The article presents the results of the development of schemes of electric power plants with a capacity of up to 100 kW with a steam-generating hydrogen-oxygen plant for modeling and selecting effective options for thermal schemes of microgeneration power plants at the stage of design and development of energy systems. METHODS. The analysis of the proposed variants of thermal schemes with a hydrogen-oxygen steam generator, including circuit solutions of micro-gas turbine installations with a hydrogen-oxygen steam generator, a scheme of a steam-gas installation with a hydrogen-oxygen steam generator and intermediate steam superheating, a scheme of a steam-turbine installation with a hydrogen-oxygen steam generator, a scheme of a steam-turbine installation with a hydrogen-oxygen steam generator and a single-stage intermediate steam superheating, is performed, the scheme of a steam turbine installation with a hydrogen-oxygen steam generator and an intermediate superheat of steam and a steam cooler. RESULTS. A variant of the thermal scheme is proposed, which will allow determining the approach to estimating the fuel component of the production cost of heat and electricity for domestic power plants. The article describes a chemical method for producing hydrogen under laboratory conditions in hydrogen generators based on the hydrolysis of a solid reagent-aluminum-in a reaction vessel, in which the contact of aluminum particles occurs in the liquid phase of an aqueous solution of caustic soda. A feature of the proposed method is the possibility of regulating the flow rates in the supply lines of an aqueous suspension of aluminum and an aqueous solution of caustic soda, which can significantly improve the quality of regulation and reduce the cost of operating such systems. To a large extent, the creation of such systems becomes possible if there is a demand for the generated electrical energy, which determines the need to ensure high values of technical and economic indicators of the operation of power plants. CONCLUSHION. Calculated estimates have shown that the specific consumption of conventional fuel for the production of electric energy by microgeneration systems based on gas turbine units with a hydrogen generator with a capacity of 5-100 kW ranges from 0.098 to 0.117 kg/kWh.

Investigation of thermal processes in hydrogen-oxygen steam generators of kilowatt power class

PURPOSE. Testing of a hydrogen-oxygen steam generator (HOSG) of the kilowatt power class for the study of heat and mass transfer processes. METHODS. At the first stage, the technological system of diagnostics and control was considered, with the help of which preliminary tests were carried out. According to the results of which the structural elements of the HOSG were modernized. Further, at the second stage, an automated process control system was created, which ensured the conduct of multi-mode tests of the HOSG. RESULTS. The design of the HOSG showed its efficiency. The changes in the cooling water flow rate, pressure and temperature in the evaporation chamber during multi-mode tests are presented, as well as the generalized results of experimental studies, which show the dependence of the steam temperature on the mass fraction of water at different coefficients of the excess oxidizer.CONCLUSION. During the preliminary tests, the development of upgraded components of the HOSG was carried out, ensuring an increase in the efficiency of its operation. The created automated control system made it possible to successfully conduct subsequent multi-mode tests with two different types of cameras. The indicators of unreacted hydrogen are comparable to those already achieved in existing devices. The characteristic transition times from mode to mode show compliance with the requirements for creating autonomous power plants based on renewable energy sources.

Investigation of thermal processes in hydrogen-oxygen steam generators of kilowatt power class

THE PURPOSE. To analyze the current state and prospects for the hydrogen energy development. To consider the possibility of implementing a project aimed at producing hydrogen on the territory of the Republic of Crimea. To choose a suitable location for the facility construction. To provide for the use of renewable sources to supply consumers of the facility with electricity. To study the existing methods of obtaining hydrogen in order to select the suitable one for use on the territory of the Republic of Crimea. To calculate the amount of electricity generated by the selected source and consumed by the elements of the hydrogen production system. To determine the cost of the project and its payback period. METHODS. The method of calculating the amount of electricity generated by the source, as well as the method for determining the cost of project implementation and payback based on data from open sources were used to achieve the set goals. In this work, a simulation of a facility consisting from an electricity source – a solar power plant with an installed capacity of 110 MW, a hydrogen production system – an electrolyser with a capacity of 50 MW, a seawater desalination system – a reverse osmosis unit with a capacity of 600 tons of water per day was performed. Various types of electrolysers were analyzed. RESULTS. The balance of energy generated and consumed by the elements of the hydrogen production system was determined. The capital costs of implementation and the annual operating costs of the project were calculated. CONCLUSHION. The recoupment of such a project, according to preliminary estimates, will be from seven to eight years with a capital investment of about five billion rubles.

Первичное регулирование частоты тока в энергосистеме атомными электростанциями на основе водородно-теплового аккумулирования

According to the Technical Requirements for Generating Equipment of Participants in the Wholesale Market of the Unified Energy System (UES) of Russia, 2016 to participate in the general primary frequency regulation (PRCF), the maneuverable characteristics of generating equipment of nuclear power plants with VVER reactors put into operation before 2009 should ensure frequency deviations guaranteed realization of the required primary power for loading up to 2% of the nominal electric power. For this, the current capacity of the reactor installation should be maintained at a level of not more than 98% of the nominal thermal power. The fulfillment of this requirement signifi- cantly reduces the installed capacity utilization factor (CUF) of reactor plant. In addition, at present in the UES of the Russian Federation there is a tendency towards an increase in the deficit of peak and half-peak capacities. The majority of fossil fuel-fired thermal stations are switched to the half-peak mode, which negatively affects their efficiency and reliability. In addition, the rise in price of natural gas makes it more profitable to sell it abroad instead of burning at power plants. On the other hand, an increase in the share of nuclear power plants is observed in the UES, which exacerbates the problems associated with the passage of minima and maxima of the daily load in the power system, due to the economically and technically justified need to load NPPs with maximum CUF. The authors developed an approach to solving this problem by combining NPPs with an environmentally friendly energy source - an autonomous hydrogen complex (AHC), which includes thermal batteries and an additional multi- functional steam turbine unit. The developed energy complex will allow energy to be accumulated during hours of minima load in the power system due to the electrolysis of water to produce hydrogen and oxygen, as well as the accumulation of hot water in the storage tanks. The accumulated energy can be used to generate super-nominal electrici- ty to cover the half-peak load zone in the power system. In addition, the presence of a low-power steam turbine installation will ensure uninterrupted power supply to consumers of their own needs at the NPP by using the energy of the residual heat from the reactor when the station is completely de-energized. Based on the proposed energy complex, a method has been developed to ensure the participation of NPPs in the PRCF in an energy system with a constant CUF. To assess the effectiveness of the proposed solution, a methodology for thermodynamic analysis of the energy complex based on the combination of NPPs with AHC was developed. The dependence of the required hydrogen fuel consumption and the efficiency of using off-peak electricity on the temper- ature of the feed water supplied to the hydrogen-oxygen steam generator from the hot water tanks is constructed. Based on the results obtained, the technical and economic efficiency of the developed energy complex is considered. The accumulated net present value was determined depending on off-peak electricity tariffs with three variants of the forecast dynamics of the half-peak electricity tariff, taking into account natural gas savings, reduced investment in NPP safety systems and the economic effect of ensuring the participation of NPPs in the PRCF with the plant load at 100%.

Application of Hydrogen–Oxygen Steam Generators for Secondary Flash Steam Superheating at Geothermal Power Plants

One of the promising areas of applying hydrogen technologies in power engineering is to increase the capacity utilization factor and efficiency of turbine units by means of hydrogen–oxygen steam generators for superheating the working medium under the conditions in which the surplus electricity generated at power plants during the periods of daily and seasonal reduction in electric power consumption can be used for generating hydrogen. The use of steam superheating systems on the basis of hydrogen–oxygen steam generators at geothermal power plants is especially important in view of a low energy potential of geothermal heat carrier serving as the initial heat source. The article presents the results from computational studies of the technical advisability and technical-economic efficiency of implementing systems for increasing the secondary flash steam energy potential by using a hydrogen–oxygen steam generator and a binary power unit at a direct-cycle geothermal power plant operating on steam hydrotherms. The results from computational studies into the power characteristics of a combined binary cycle geothermal power plant with secondary flash steam superheating depending on the expansion pressure variations and the hydrogen–oxygen steam generator capacity are considered. It has been determined that the use of a 12-MW hydrogen–oxygen steam generator for superheating secondary flash steam results in that the steam wetness downstream of the steam turbine last stage decreases from 14 to 7%. Calculation results have shown that the topping of a direct-cycle geothermal power plant with a system for increasing the energy potential of secondary flash steam on the basis of a hydrogen–oxygen steam generator and a binary power plant makes it possible to increase the geothermal power plant capacity by almost 25% and its efficiency by 3.0–3.5%. Based on the feasibility study results, investors can select the optimal composition and characteristics of equipment in implementing a system for increasing the energy potential of secondary flash steam using a hydrogen–oxygen steam generator and a binary power unit at a direct-cycle geothermal power plant.

Thermodynamic Modeling of oxyhydrogen fueled combined cycle power plant

Renewable power generation can reduce the dependence on fossil fuels while minimizing greenhouse gas emissions from electric power generation. However, most renewable energy sources are naturally occurring which makes them seasonal and generally unpredictable over time. With more countries trending toward renewable power by 2050, it is imperative that technologies are developed which can utilize and optimize the storage and distribution of this type of power. Hydrogen energy storage is becoming increasingly popular due to its versatility. It is considered an energy carrier like electricity and can be generated and stored in large quantities and for long periods of time. Hydrogen can be derived from water, biomass, and other technologies and can generate electric power using fuel cells and through combustion. This study investigates a novel combined cycle configuration which is thermodynamically analyzed to identify its potential to adapt steam from a hydrogen oxygen steam generator. A thermodynamic analysis on the system is performed using Engineering Equation Solver from F Chart Software. Results show that the oxygen hydrogen fueled combined cycle excels in the specific power ratio, as this cycle was able to achieve the lowest pressure values at the highest points for both thermal loading and pressure loading. This is a major advantage since the thermal loading on some of the power cycles are much higher that what is currently in use, thus reducing it even by a smaller percentage is significant. The oxygen hydrogen fueled combine cycle reduced the specific power by 78%, pressure at the most thermal loaded point by 157%, and pressure at the most pressure loaded element by 10% when compared to other common cycles.

Геотермальные энерготехнологии России

The results of scientific and technical investigations and development of geothermal technologies in Russia are presented. Information on the geothermal resources in Russia, the characteristics of geothermal fields and the physicochemical properties of geothermal fluids is given. The article presents the most significant results from experimental studies and numerical modeling of crisis phenomena in wet steam flows in the zone near the upper boundary curve, the generation and precipitation of a dispersed liquid phase, the flow of liquid films and moisture separation, and the formation of deposits and regularities relating to flow accelerated corrosion of structural metals in a multicomponent geothermal fluid. The article also discusses the design features and advantages of Russian geothermal equipment, including gravity separators, steam turbines with a developed system for intra-channel separation of moisture from the flow path, a cooling system, and a system for reinjection of waste geothermal fluid. It is shown that the use of gravity separators produced by the JSC Machine Building Plant ZiO Podolsk makes it possible to keep the moisture content of steam at the turbine inlet at a level of 0.1-0.5%, thereby significantly reducing the deposit formation rate in the turbine stages. It is also shown that the use of the intra-channel separation system and the steam turbine’s dedicated separation stage makes it possible to remove more than 80% of moisture from the flow path. Basic information about the process flow diagrams, design and technical characteristics of the equipment installed at the operating Russian geothermal power plants, including the Verkhne-Mutnovskaya GeoPP and the Mutnovskaya GeoPP in Kamchatka, is given. Some results from recent studies on achieving more efficient use of the geothermal fluid heat are presented, in particular, through applying a system for superheating steam at the turbine inlet and secondary flashed steam by using hydrogen-oxygen steam generators. Promising sites for constructing new Russian geothermal power plants have been identified.

Application of Hydrogen-oxygen Steam Generators for Increasing the Reliability of Functioning of the Unified Energy Power System

Application of Hydrogen-oxygen Steam Generators for Increasing the Reliability of Functioning of the Unified Energy Power System

Increase of maneuverability of nuclear and geothermal power plants by hydrogen-oxygen complexes

We present results of feasibility analysis of hydrogen-oxygen complexes for base load power plants. To increase flexibility of nuclear and geothermal power plants it is proposed to produce hydrogen and oxygen by excess power and use the gases in hydrogen-oxygen steam generators to produce high temperature steam and provide additional power during power ramps. It is possible to decrease the time of power ramp from 20% to 100% of nominal capacity from 13-15 min to 1.5, while the main steam generator increases capacity with the rate 5-6%/min. Taking into account a rare need in such a big power ramps and low capital intensity of hydrogen-oxygen steam generators, the total increase of capital investments in a nuclear plant should be ca. 1%.

A Combined Binary-Cycle Geothermal Power Plant with a Secondary Flash Steam Superheating System: Choice of Optimal Working Fluids

The article presents the results from numerically modeling the process circuit of a combined binary-cycle double-flash geothermal power plant (GeoPPs) with the use of secondary flash steam superheating by means of a hydrogen–oxygen steam generator. Geothermal heat carrier from substandard wells of the Mutnovsk geothermal field, as well as separated steam and waste brine from the Mutnovsk GeoPP, were taken as the primary heat source. Numerical investigation results have shown that the application of secondary flash steam superheating by means of a hydrogen–oxygen steam generator makes it possible to increase the steam turbine’s power output and its flow path efficiency owing to the steam wetness reduced by more than a factor of two. In addition, reduced steam wetness helps prevent erosion damage to the last-stage turbine rotor blades. Data on the effect that the use of different organic substances has on the efficiency and power output of the binary installation and of the GeoPP as a whole are given. Optimization investigations have shown that the highest power output and efficiency values of the binary installation used as part of a combined binary-cycle GeoPP at the lowest specific brine flowrate are achieved in using organic substances from the groups of nontoxic fire- and flame-proof (R-31-10 and RC-318) and low-toxic fire- and flame-proof ones (R-227ea, R-236fa, R1318, and R-134a) as working fluids. It has been established that the highest power output values of a combined binary-cycle double-flash GeoPP with secondary flash steam superheating by means of a hydrogen–oxygen steam generator are achieved in using the organic working fluids R-31-10, R‑227ea, and RC-318. In so doing, the optimum design pressure in the expander-separator at which the highest efficiency and power output of the studied GeoPP are obtained makes 0.47 MPa. In solving optimization problems on selecting the working fluids for binary combined-cycle GeoPP installations, it is proposed to use multiaxial composite diagrams of the relative values of geothermal power plant parameters and characteristics. An example of drawing a multiaxial composite diagram for the relative values of parameters and characteristics for a combined binary-cycle GeoPP for the R-290, R-31-10, R-32, and RC-318 working fluids is given. The numerical investigation results can be used in designing new and modernizing the operating GeoPPs that use steam geothermal sources.

Optimization Investigations of a Combined Binary-Cycle Geothermal Power Plant with Two Separation Pressures and Flashed Steam Superheating Using a Hydrogen–Oxygen Steam Generator

The article considers the specific features of and prospects for improving the efficiency of geothermal power plants (GeoPPs) that use a steam–water mixture from geothermal fields and steam superheating as an energy source. The process flow diagram of a combined binary-cycle GeoPP with two separation pressures and flashed steam superheating with the use of a hydrogen–oxygen steam generator is proposed. The advisability of using a separator downstream of the high-pressure section for decreasing the steam moisture at the turbine condenser inlet is substantiated. The article also presents the results from numerical optimization investigations of the effect that the choice of organic working fluid has on the efficiency, safety, and environmental characteristics of the binary installation used as part of a combined-cycle GeoPP. The following groups of organic substances as possible candidates for use as working fluid are considered: nontoxic, nonflammable, and nonexplosive ones (group I); low-toxic, nonflammable, and nonexplosive ones (group II); nontoxic inflammable ones (group III); and low-toxic, inflammable, and explosive ones (group IV). Typical dependences characterizing the effect that the pressure in the expander and the saturation pressure in the evaporator have on the binary turbine net power output, on the specific flowrate of separated geothermal brine per unit power capacity, on the binary cycle efficiency, and on the GeoPP efficiency as a whole are shown taking as examples the use of cyclobutane and octafluoropropane as a working fluid. For a few working fluids, the existence of extremes in the above-mentioned dependences is established, which determine the binary installation optimal power values and the minimal geothermal brine specific flowrate. Based on the numerical analysis results, limitations are imposed on the admissible maximum and minimum pressure values in the binary circuit. Bar charts of calculated process characteristics influencing the binary turbine flow path’s design and efficiency are plotted. A priority (according to the maximum net power output criterion) list of working fluids relating to the group of environmentally friendly organic substances for the combined-cycle GeoPP binary installation with flashed steam superheating taking into account process-related limitations is drawn up.

Efficiency of steam generation in hydrogen-oxygen steam generator of kilowatt power class

Efficiency of steam generation in hydrogen-oxygen steam generator of kilowatt power class

Efficiency of Steam Generation in a Hydrogen-Oxygen Steam Generator of Kilowatt-Power Class

The article presents the results of experimental studies and optimization of the processes of mixture formation, combustion, and steam generation in a kilowatt power–class, experimental, hydrogen-oxygen steam generator. The optimal design of the mixturing element and the combustion chamber for their failsafe operation and minimal hydrogen content in the generated steam is determined. The influence of the pressure in the evaporation chamber and of the generated steam temperature on the completeness of hydrogen combustion is studied. The results of multiregime tests of the hydrogen-oxygen steam generator at a power of up to 200 kW are presented.