Steam Turbine Plant Research Articles

Bench studies of the influence of operating conditions on operational safety of steam turbine air-cooled condensers at subzero outdoor temperatures

Condensation processes are widely spread in various branches of industrial production and, in particular, in electric power industry, where, according to experts' data, heat removal in thermodynamic cycles of steam turbine plants (STP) operating as part of combined cycle plants (CCP) and autonomously, in the 21st century will be exercised mainly in air-cooled condensers (ACC). At the same time, the use of ACC as a part of steam turbine units operating in climatic conditions typical for the Russian Federation (RF) determines the relevance of problems to be solved to ensure their safe operation at subzero outside temperatures. One of these challenges is to ensure long-term safe operation of the ACC, with the formation of ice on the inner surface of the heat exchange pipes minimized. To conduct the research, Steam Turbine Air-Cooled Condenser research and training stand was used. The paper presents the combined circuit and measurement diagram of the research and training stand, and gives a brief description of the design of the ACC. Experimental modes have been determined, and methods for processing experimental data and analyzing the results obtained have been developed. As part of the study, experiments were carried out on 18 steady-state operation modes of the stand. At the same time, the values of the main operational parameters of the ACС varied within the following limits: the temperature of the cooling air at the ACС inlet — from minus 11,5°C to minus 1,8°C; the cooling ratio — from 176 to 790. The relative weight content of air in the vapor varied from 0,051% to 0,12%. An analysis of the obtained results was carried out, on the basis of which a relationship was established that allows, for various negative temperatures of the cooling air at the inlet to the ACС, to determine the highest value of the cooling ratio at which its long-term safe operation is possible. An algorithm for using the obtained relationship is given.

Neural network for predicting operating modes and calculating energy characteristics of steam turbine plants

The article describes the results of work on the creation of neural networks calculating the technical and economic parameters of all possible modes of operation of a thermal turbine unit with a steam turbine of type PT-60-130/13. In accordance with the objectives set, recommendations for the preparation of training data samples are formulated. The input and output parameters of the condensing and heating modes of operation of the steam turbine are determined. The results of research on determining the most optimal architecture of neural networks for calculating the energy characteristics of steam turbine plants of the heating type are presented. The results of calculations of the mean squared errors of neural network predictions from the results of calculations performed using a verified object-oriented model of a PT-60-130/13 turbine unit are tabulated.Graphs of the dependence of the specific heat consumption for the generation of electrical energy on the power of a PT-60-130/13 turbine unit for condensation and heating modes of operation using neural networks are plotted. The conclusion is formulated about the possibility of using neural networks for the development of energy characteristics and regulatory documentation on fuel use of equipment of thermal power plants.

Thermodynamic Analysis and Comparison of Power Cycles for Small Modular Reactors

Small nuclear power plants can provide a stable, carbon-free energy supply to civil infrastructure and industrial enterprises in remote regions isolated from unified energy systems. More than 70 projects of small modular reactors are currently being developed by IAEA member countries; several low-power power units are already supplying thermal and electrical energy to consumers. One of the main limitations standing in the way of widespread dissemination of this technology is the high specific capital cost of a low-power nuclear power plant; therefore, new scientific and technical solutions are needed in this industry. Increasing the thermodynamic efficiency of power cycles of small modular reactors can become a driver for reducing the cost of supplied electrical energy. This paper presents the results of a comprehensive thermodynamic analysis of existing and promising power cycles for small modular reactors. In addition to traditional steam power cycles, cycles using non-traditional working fluids, including carbon dioxide, freons, and helium cycles, are considered. Optimal sets of thermodynamic parameters were determined to ensure maximum net efficiency of electricity production. For water-cooled reactor plants, a maximum efficiency of 33.5% at an initial temperature of 300 °C could be achieved using a steam turbine cycle. It was revealed that for reactor plants with liquid metal and liquid salt coolant in the range of initial temperatures above 550–700 °C, the maximum thermal efficiency was provided by the Brayton recompression cycle with a carbon dioxide coolant: the net electrical efficiency exceeded the level of steam turbine plants, with intermediate superheating of the steam, and could reach a value of 49.4% at 600 °C. This makes the use of these cycles promising for low-power nuclear power plants with a high initial temperature. In small gas-cooled reactor plants with a helium coolant, the use of a binary cycle consisting of a helium Brayton cycle and a steam-powered Rankine cycle provided an efficiency of 44.3% at an initial helium temperature of 700 °C and 52.9% at 1000 °C. This was higher than in the Brayton cycle with a recuperator, with a minimum temperature difference in the heat exchanger of 20 °C: the efficiency was 40.2% and 52%, respectively. Also, the transition to power cycles with non-traditional working fluids will lead to a change in the operating conditions of turbomachines and heat exchangers.

Comparative study of steam, organic Rankine cycle and supercritical CO2 power plants integrated with residual municipal solid waste gasification for district heating and cooling

Among the different waste-to-energy solutions, gasification is considered a promising option and an alternative to landfilling of residual municipal solid waste (RMSW). Therefore, the potential of RMSW air gasification in combination with three different power cycles for district cooling and heating applications is investigated. The model of a fluidized bed air gasifier developed in Aspen Plus is integrated with the models of steam turbine (ST), organic Rankine cycle (ORC), and supercritical CO2 (sCO2) Brayton cycle power plants for the combined cooling, heating, and power production in district networks.The results of the numerical study show that the ST power plant provides higher electrical power compared to the other systems, while sCO2 exhibits better thermal power and the maxima combined energy conversion efficiency. In between, ORCs prove to be a reliable and flexible solution for varying RMSW compositions and temperature levels of the district network. The size of the district network strongly varies with scenarios and in the best case, more than 1,400 residential buildings can be connected to the trigeneration plant considering 20 ktons/year of RMSW input to the gasifier.

Integrated Thermoelectric Energy Storage in A Combined Cycle Solar Power Plant (tour)

Multi megawatt-thermoelectric energy storage based on thermodynamic cycles is an ambitious solution for the renewable energies conversion. The main advantage of this technology is the capacity of energy storage, However, ensuring the operation of TEES stations during unfavorable weather conditions is suspended. In this article, a specific thermoelectric energy storage system was studied «TEES», the TEES system converts electrical energy into sensible heat by means of an electric heater that uses the joule heating effect, the system TEES converts sensible heat into electrical energy by means of a hybrid power plant that operates on a combined cycle « Brayton and Rankine ». The hybrid power plant uses two thermal energy sources In order to secure the station in unfavorable weather conditions for the production of solar energy. The main idea is to using the gaz and the sensible heat stored as two thermal inputs in the gas turbine that uses a Brayton cycle, the thermal rejection from the gas turbine was recovered and used as a thermal input in the conventional steam turbine plant that uses a Rankine cycle. A thermodynamic analysis of the TEES system was performed in steady state, using the thermodynamic properties of the Coolprop database, a maximum thermal efficiency or Round trip electrical efficiency of 50% has been reached; when the heating temperature of the compressed air reaches 1100 ° C and When the isentropic efficiency of steam turbine is 90 percent.

Method of object-oriented modeling of steam turbine plants taking into account variations in turbine efficiency under variable operating modes

The article proposes an object-oriented method for modeling steam turbine plants. The novelty of the method is in the application of a steam turbine model that takes into account variations in internal efficiency under variable operating modes.The article presents the results of theoretical substantiation of nonlinear dependence of the power of the turbine compartments on the steam flow passing through them, based on the change in the internal efficiency of the stages under variable modes described by the Stodola-Flugel equation. An empirical dependence of the efficiency of the stage operation on the relative steam consumption is proposed. Recommendations on the use of empirical form in the development of models of steam turbine compartments are given. The empirical dependences of the relative internal efficiency of turbine compartments obtained from the results of thermal tests of an operating turbine unit are presented.As a factor of practical significance of the research, a model of PT-60-130/13 type steam turbine plant has been developed involving the use of an object-oriented programming language. Recommendations on the description of classes of objects within the steam turbine plant. The developed STP model enables to simulate any operating modes depending on electrical and thermal loads, as well as to take into account the influence of deviations of external factors from nominal values when developing a system of corrections or estimating an increase in fuel consumption associated with these deviations.

Dual steam turbines in biogas power processes

The combined-cycle power plant (CCPP) is arguably the most economically and environmentally significant example of process intensification. Its wide-spread application has doubled the thermal efficiency of electricity generation over the last two decades. In its use for biogas fuel, a mixture of methane and carbon dioxide is produced at low pressure. The gas is compressed to a high enough pressure so that the carbon dioxide can be removed by amine absorption. The remaining methane is compressed to a higher pressure and burned with air in a combustion gas turbine in a combined cycle gas/steam power plant. The gas turbine and the steam turbine produce power. The compression of the feed gas and of the air represent parasitic power losses, which reduce the net power produced.A previous paper illustrated how this process is designed and how it is controlled. The purpose of this paper is to extend the study in two ways. First, the optimum combustor pressure is determined that gives the maximum net power production for a fixed methane feed flowrate. Second, a dual steam turbine plant is compared with a single turbine system.

Feasibility Study of Scheme and Regenerator Parameters for Trinary Power Cycles

Natural gas-fired combined cycle plants are nowadays one of the most efficient and environmentally friendly energy complexes. High energy efficiency and low specific emissions are achieved primarily due to the high average integral temperature of heat supply in the Brayton–Rankine cycle. In this case, the main sources of energy losses are heat losses in the condenser of the steam turbine plant and heat losses with the exhaust gases of the waste heat boiler. This work is related to the analysis of the thermodynamic and economic effects in the transition from binary to trinary cycles, in which, in addition to the gas and steam–water cycles, there is an additional cycle with a low-boiling coolant. A method for the feasibility study of a waste heat recovery unit for trinary plants is proposed. The schematic and design solutions described will ensure the increased energy and economic performance of combined cycle power plants. Based on the results of the thermodynamic optimization of the structure and parameters of thermal schemes, it was found that the use of the organic Rankine cycle with R236ea freon for the utilization of the low-grade heat of a trinary plant’s exhaust gases operating from a GTE-160 gas turbine makes it possible to achieve a net electrical efficiency of 51.3%, which is a 0.4% higher efficiency for a double-circuit combined cycle gas turbine plant and a 2.1% higher efficiency for a single-circuit cycle with similar initial parameters. On the basis of the conducted feasibility study, the parameters and characteristics of the heat exchangers of the regenerative system of the waste heat recovery unit are substantiated. The use of plain fin-and-tube heat exchangers in the regenerative system of the utilization cycle is the most promising solution. It was found that the level of allowable pressure loss in the regenerator of 10 kPa and the degree of regeneration of 80% allow for maximum economic efficiency of the waste heat recovery unit.

Acoustic Method for Detecting Air Suction in the Vacuum System of Steam Turbine Plants of Thermal Electric Power Stations

Acoustic Method for Detecting Air Suction in the Vacuum System of Steam Turbine Plants of Thermal Electric Power Stations

Innovative solutions in the energy sector

Combined heat and power plants (CHPPs) allow for significant savings in primary energy resources and a reduction in environmental pollution. Mostly it is carried out using steam turbines. However, in the eighties of the twentieth century, a new promising direction in the development of cogeneration appeared. These are plants operating on the organic Rankine cycle (ORC). An analysis of energy innovations abroad is required for the development and adaptation of this direction to Russian realities. Therefore, an analysis of the energy and environmental efficiency of high-moisture biofuels and biofuel mixtures with high ash content was carried out in boilers operating as part of a CHP using ORC technology and traditional steam turbine plants. Some recommendations for the innovative development of small and medium-scale power generation were proposed.

Operating Thermal Power Plants Efficiency Improvement under Current Conditions

In the present-day conditions, the issue of energy saving is becoming increasingly acute and permanently relevant. This situation is caused by rapid growth in prices for primary energy resources and by the need to reduce the share of natural gas in the incoming part of the energy balance of Belarus. According to available statistics, with the commissioning of the Belarusian NPP, the share of natural gas in the incoming part of the energy balance decreases from 97 to 59 %. In the economic complex, the share of this primary energy resource is projected at 70 %. The problem of energy saving is solved most rationally and with the least investment only by increasing the efficiency of natural gas use, especially due to the commissioning of the Belarusian NPP, the issue of preserving the possibility of using centralized heating facilities is acute. It is necessary to increase the thermodynamic efficiency of the cycles of steam turbine plants, both heating and condensing, which form the basis of the generation of the Belarusian power system, in order to restore the energy characteristics of the power system, which have somewhat decreased with the commissioning of the NPP. In the limit, the share of natural gas in the incoming part of the energy balance should be reduced to values not exceeding 50 %, in accordance with the requirements of energy security. The article considers examples of utilization of low-temperature secondary energy flows occurring at thermal power plants: the heat of the cooling processes of the generator, lubrication systems, as well as the heat of condensation of turbine exhaust steam and deeper cooling of flue gases. On the basis of this review, it is expected to identify promising areas of relevant research in relation to the energy system of Belarus.

Математическая модель расходных характеристик паротурбинных установок

A large number of generating equipment installed at thermal power plants (TPPs) operate at the limit of their fleet life resource or beyond it. Malfunctions and defects occur during the entire period of operation of steam turbine plant (STP) of TPPs. It causes performance degradation of efficiency, reliability, and maneuverability of STP. Thus, the methods to provide monitoring over the technical position of the elements and/or functional units of steam turbine plant are to be applied. Hence, special attention is to be paid to the development of methods to monitor the technical position and diagnostics of generating equipment of TPPs. The methods are based on a mathematical model of flow characteristics of steam turbine plants. It allows us to consider the effect of changes in the open flow area of the individual compartments of a steam turbine on the pressure distribution over the flow path. To develop the model, the authors have applied mathematical modeling methods and the balance relations of mass and energy methods. The solution of the equations of the obtained linear and nonlinear systems is carried out by methods of computational mathematics. Calculation of thermodynamic parameters of the coolant is carried out based on tables of properties of water and water vapor and software for their description. A mathematical model of a steam turbine plant has been developed. It represents a set of linear and nonlinear algebraic equations that consider the flow discharge characteristics of the steam turbine compartments. Also, it makes possible to assess the technical position and it considers the effect of defects on the pressure distribution over the flow path of the steam turbine. The results of the statistical analysis prove that the model has been recognized adequate under the variation range in the electrical load. The results of the development of mathematical steam turbine plant model can be used to develop intelligent systems to monitor and diagnose power generating equipment of TPPs. Application of these systems allow the management of the TPP to change over from the system of preventive maintenance of equipment to the system of the repair of equipment according to technical position.

Methodology for assessing the aerodynamic imbalance of GTE impellers

Increased vibration during testing and operation of gas turbine engines may be caused by aerodynamic imbalance. As usual, aerodynamic imbalance is eliminated on stands simulating the operating conditions of the impellers. Existing stands have a high cost of testing or do not allow to make allowances for all the factors during the operation of the impellers. A review of models and techniques has shown the importance of considering operating parameters when calculating aerodynamic imbalance. The paper provides a methodology for calculating the aerodynamic imbalance of the impeller. The methodology is based on the use of finite element modeling (FEM). The proposed method for assessing the aerodynamic imbalance of the impellers makes it possible to take into account the rotational speed, the actual geometry of the blades based on the measurement results, as well as the assembly conditions and the operating conditions of the impeller. The technique was used through the example of a specially designed and manufactured impeller with geometric deflections. Theoretical and experimental studies have been carried out. The discrepancy between theoretical and experimental data did not exceed 15.5%. The developed model can be used at enterprises that manufacture gas turbine engines, gas compressor units, steam turbine plants and wind power plants.

Краткий анализ создания атомных подводных лодок и отраслевых стандартов проектирования систем энергетических установок

Object and purpose of research. A wide application of nuclear technologies and new types of weapons, electronic sensors, automation systems and tools have increased combat capabilities of the Navy and its major component represented by submarine forces. Materials and methods. Nuclear submarines are core weapons of the Naval Forces, which can efficiently perform strategic and tactical roles, including multiple tasks. Main results. This paper briefly analyzes the steam-generation and steam-turbine plants development of submarines and elaboration of industry standards used for design of the systems supporting of nuclear submarines. Conclusions. This paper assesses the relevancy of standards used in development of steam-generation and steam-turbine plants for advanced nuclear submarines and identifies the scope for their further improvement to take into account modern nuclear submarine requirements in the design.

Decreasing the Weight-Size Parameters of Gas-Steam Turbine Plant by Increasing the Efficiency of Thermodynamic Processes in the Condenser

The aim of this work is decreasing the weight-size parameters of the contact gas-steam turbine plant and contact condenser elements by increasing the efficiency of thermal-gas dynamic processes of condensation through rational irrigation of countercurrent gas-steam flow. To achieve the goal the total efficiency of water-return drops ranging from 0.1 to 1 mm at different initial velocities from 5 to 35 m/s emitted by the multi-nozzle sprinkler was determined by mathematical modeling of the liquid droplet movement processes, heat and mass transfer between the liquid droplet and gas-vapor mixture, and gas-vapor mixture pressure loss. The effect of increasing the gas-steam mixture velocity from 3.3 to 6 m/s on the overall efficiency of water return was determined. The novelty of the obtained results was defined by an increase in the water return into cycle from 12 to 13% with a droplet diameter of 0.3 -- 0.4 mm and the initial velocity from the sprinkler of 5--10 m/s. The velocity of the mixture was to 6 m/s at rational correlations of the initial velocity of the droplets’ escape, which increased the total amount of heat withdrawn to 11%. The positive effect conditions of irrigation processes on thermogasdynamic and weight-size parameters of the condenser elements for the contact gas and steam turbine plant at full pressure recovery coefficients of over 0.967 were substantiated. The most significant result was the reduction of the weight-size parameters of the marine infrastructure object power plant from 8 to 19%.

Техніко-економічні показники технологій теплової енергетики, що експлуатуються в маневрених режимах

There is a deficit in united energy system of Ukraine of installed capacity of flexible generation units which are able to quickly reach the operating mode, change the power generation levels in a wide range. To model additional measures increasing the flexibility of the power system, it is necessary to know the technical and economic indicators of thermal power technologies and its specific operating modes. The purpose of the article is to determine: efficiency factors depending on the power unit load; start-up costs depending on downtime duration and different fuel prices; the influence of maneuvering modes on lifetime resource indicators; as well as comparison of indicators for various technologies of thermal energy. The following thermal power technologies: natural gas, hard or bituminous coal fired steam turbine supercritical pressure, steam-gas, gas turbine open cycle and gas piston engines. The calculation formulas allowing estimate the influence of the power plant operation mode on the efficiency is obtained. The results of calculation of the start-up specific costs depending from the type of the unit and the idle time is presented. The different values of thermal power unit start-up cost are presented depending on idle time. As an example, the balancing of 660 MW electric power with different equipment composition are considered. The analysis of the results shows that the highest start-up cost is for coal-fired steam turbine plants, and the composition of the equipment with the lowest start-up cost varies depending on the downtime: up to 2 hours, 2 – 5 hours, more than 5 hours. Formulas for recalculating the cost of starting at different fuel prices are obtained. The influence of maneuvering modes on the lifetime resource indicators of thermal power plants is also presented. The conventional thermal power generators of the united energy system of Ukraine have actually overcome their physical capabilities to ensure effective load following, therefore, it is necessary to introduce new highly flexible capacities, and the proposed formulas and results could be helpful to determine the volumes and characteristics of new thermal power plants needed to implement into power system. Keywords: thermal power, maneuverable mode, efficiency, downtime, start-up cost, service life

Nuclear cogeneration for cleaner desalination and power generation – A feasibility study

Abstract Population growth, economic development, groundwater impairment due to salt water intrusion and local vulnerabilities caused by rising sea levels prompt immediate necessity for customized adaptation strategies for the cities of Homestead and Miami in Florida. This paper presents a feasibility study of nuclear energy driven cogeneration plant for water and power production in Homestead, FL. Miami-Dade and Homestead, Florida is home to the Turkey Point Nuclear Generating Facility. The focus of this study is to investigate the economic feasibility of a seawater desalination facility on the site of an existing nuclear generating plant. While the cost of seawater desalination is often too great to overcome, it is hypothesized that sharing the infrastructure and processes with a power generating facility will lower the cost of producing freshwater. The analysis was completed with the aid of the desalination modeling software, DEEP. First, we estimate the population growth and water demands for Homestead, FL and then identify a suitable water desalination plant configuration based on freshwater and power production costs. We then compare cogeneration (water and power) schemes based on different energy sources and desalination technologies. The energy sources considered are nuclear energy, oil and natural gas for steam turbine and combined cycle power plants. In addition, we evaluate the water and power production costs for hybrid desalination configurations. Finally, the freshwater costs through nuclear desalination were assessed with other options and conventional ground water system costs. Environmental emissions saved through nuclear desalination and the need for considering this option despite the high costs are discussed in detail. The study concluded that reverse osmosis desalination plant powered by nuclear energy produced water at the lowest cost which is still three times the cost of current water rates in Homestead, Florida.

Прогнозный сравнительный анализ модернизации АЭС на базе комбинирования с автономным водородным энергокомплексом и газотурбинной установкой

Optimizing existing nuclear power plants adding developing power technology can help find effective ways of improving variable power loads in an electric power system. One of the most promising options is combining a nuclear power plant with a newly developed autonomous hydrogen complex reported in our research. The ability of storing unused energy and releasing it when needed will raise contribution of nuclear power plants in compensating improving variable power loads, shorten emissions as well as contribution of conventional thermal power plants into electric power generation. Also, as we demonstrated in our previous research results, a low-power steam turbine plant used in the said autonomous hydrogen complex can support an auxiliary power system of a nuclear power plant reusing residual reactor heat in case of an outage.

Parametric Study on the Performance of Combined Power Plant of Steam and Gas Turbines

Abstract This paper deals with aspects of the combined power and power (CPP) plants. Such plants consist of two major parts: the steam turbine and gas turbine plants. This study investigates the efficiency of CPP under the effect of several factors. CPP plants including an open cycle gas turbine and a bottoming cycle steam turbine can achieve the highest thermal efficiency obtained with turbomachinery up to date. In this cycle, the anticipated waste thermal energy of the exhaust of gas turbine is used to generate high-pressure steam to empower the steam turbine in the steam cycle. By systematically varying the main design parameters, their influence on the CPP plant can be revealed. A comprehensive parametric study was conducted to measure the influence of the main parameter of the gas and steam cycles on the performance of CPP. The results exhibit that the overall plant thermal efficiency is significantly greater than that of either of the two turbines. Due to the high thermal efficiency, a significant reduction in the greenhouse effect can be achieved. It is found that the regenerative steam cycle will reduce the overall efficiency of the combined cycle. On the other hand, using the reheat steam cycle in the CPP plant will lead to an increase in both the thermal efficiency of the plant and the dryness factor of steam at the exit of the steam turbine.

The Upgrading of the Combined-Cycle Cogeneration Plant with Heat-Recovery Steam Generators for Large Cities of the Russian Federation

In most large cities of Russia, the annual heat consumption exceeds the annual electricity consumption more than twice as a rule. On the contrary, the electric power of the combined-cycle cogeneration heat-power plant (CCCHPP) with heat-recovery steam generators (HRSG) is much higher than the thermal power of the cogeneration extraction of its steam turbine plant. This necessitates equipping combined-cycle gas turbine–combined heat and power plants (CCGT–CHPP) with additional heat sources to cover the heat loads of the heating season, which exceed the heat capacity of the cogeneration extractions of the combined-cycle gas turbines. The article shows that the use of water-heating boilers in this capacity has a number of serious disadvantages. These disadvantages can be eliminated by equipping HRSGs with afterburner units (ABUs), which burn the gas fuel in the residual oxygen of the exhaust gases of the gas turbine engine (GTE) directly in the HRSG. The range of thermal loads can be expanded, and the efficiency of the ABU application can be significantly increased by mounting the ABUs in the HRSG downstream from the high-pressure steam superheater upstream from the high-pressure evaporator. Furthermore, it is necessary to integrate a number of new components into the HRSG configuration, such as a water low-pressure steam superheater (WLPSSH) used instead of the gas LPSSH, a reduction device, and a peak network heater included in the heating plant of the steam turbine unit as the third stage of the network water heater at high (peak) thermal loads. By the example of the PGU-450T CCCHPP, the fundamental possibility of implementing the proposed modernization of its complete HRSG without making any changes to the design of the steam turbine is shown. Since the low-pressure drum of this HRSG is additionally equipped with a deaeration unit, the upgraded HRSG of the PGU-450T plant had also to be equipped with a water condensate heater upstream from the deaerator and additional shut-off and control valves that maintain the pressure in the deaerator and assure the subcooling of the water condensate at the deaerator inlet within the permissible range of all operating modes as well as under changing thermal loads all the year round.