Power Plant Unit Research Articles

Voltage deviations influence on asynchronous characteristics of powerful asynchronized turbogenerator

The widespread applying of electrical grids with voltage classes 330 and 750 kV with powerful units of nuclear and heat power plants creates a set of problems with normal modes ensuring in the Ukrainian energy system. Due to sufficiently great transverse capacitance of such overhead lines, significant amounts of reactive power excess are possible in the system. This phenomenon manifests itself especially in the load reduction hours in the power system through the visible voltage levels deviation at the energy-generating nodes in an upward direction. The application of asynchronized turbogenerators with the ability to work in asynchronous mode could solve the problem of reactive power excesses in the energy-generating nodes during load reduction hours in the power system due to their possibility of deep reactive power consumption. The paper presents the calculated results of the asynchronous modes coordinates for an asynchronized turbogenerator with a capacity 1000 MW based on the parameters of the equivalent circuit, taking into account possible generator stator voltage deviations within ±10%. The influence of voltage deviations on the asynchronous modes coordinates is shown. Due to the obtained characteristics, it is possible to perform engineering estimations of the possible asynchronous mode applying for the asynchronized generator under conditions of nuclear and thermal power plants and taking into account possible voltage deviations.

Analysis of Main Influencing Factors of the Wastewater Evaporation in Flue Duct

Desulfurization wastewater has the characteristics of small discharge and high pollution, and must be strictly treated. To obtain the main factors affecting the evaporation characteristics of desulfurization wastewater in boiler flue, a 600MW unit of a coal-fired power plant in China was taken as an example. According to the theory of fluid mechanics and heat transfer, the numerical simulation method was used. The results show that the way the nozzle is installed on the upper wall of the flue inlet can enhance the evaporation effect of the desulfurization wastewater. It is also revealed that the influence of the flue gas flow rate on the droplet evaporation effect is relatively small. The smaller droplet diameter and the higher flue gas inlet temperature will obviously enhance the evaporation effect of the droplets in the flue. However these two factors will increase the operating cost and reduce the boiler thermal efficiency. Therefore, the values of the droplet diameter and the flue gas inlet temperature need to be further determined by technical and economic comparison.

Analysis on the Causes of Cracking at the Last Stage Blade of the Low-pressure Rotor in thermal power plant

Transverse cracking occurred in the blade body of the last stage of the low pressure rotor of a 200MW unit in a thermal power plant. The causes of blade cracking were analyzed by means of macro morphology, SEM, microstructure, mechanical properties, chemical composition and energy spectrum analysis. The results show that the corrosive Cl- accumulates on leaves, and then combined action of tensile stress is formed with the static load and dynamic load during the blade operation, and the stress corrosion microcracks had been conceived in the Cl- corrosion region. Under the long period cyclic excitation stress of the blade during the rotor rotation at high speed, the crack source extends in fatigue mode, finally resulting in cracking.

Improving of manufacturability of loaded parts working surfaces using strengthening combined treatment

The information on the new processes designed and adopted for implementation on the combined surface treatment of loaded parts and assembly units of advanced power plants and special technological equipment is presented, the original means of technological equipment are described, and the prospects for further expansion of their technological capabilities and impact on improving of the manufacturability of products are given.

Modernization of Power-Generating Units with RBMK-1000 Reactors

A nuclear power plant is a complex technological facility. The introduction of new standards and experience gained in the operation of domestic and foreign nuclear power plants requires the introduction of changes in the operating organization of existing nuclear power plants and improvements in their equipment. A general survey of the modernization of existing nuclear power plants with RBMK-1000 type reactors is presented. Measures for modernization of the power-generating units of nuclear power plants carried out following the accident at the Chernobyl nuclear power plant and at the present time are discussed. Because of modernization, the safety, reliability and economic efficiency of nuclear power plants have improved. The principal focus is on modernization of the reactor plant.

Contribution of Energy Storage Technologies in Load Frequency Control - A Review

Due to increase population and the continuous efforts through the global residents to lessen the impact of environment change have caused the prompt usage of renewable based energy plants such as wind power plant and solar centered different power generation units. The usage of such power generating unit is purely dependent upon nature. Additionally, integration of renewable unit to power system causes instability. The frequency stability is one of the important aspects and depends on balance between generation and demand. To restore the frequency deviation back to its normal condition, an effective control strategy called Load Frequency Control (LFC) is adopted. To improve the performance of the control scheme different energy storage technologies can be considered. The storage technology not only has distinctive features of fast response and high energy density but also helps in load leveling, peak shaving, black start support etc. In this paper, comprehensive survey of diverse energy storage technology, its current market scenario and utilization in LFC services are presented by collecting, reviewing and interrupting numerous research articles. From the litertures survey, it is observed that, the existing strategies can be categorized in to two categories that is Grid scale System and Load Scale system. Further, load scale system is sub-categorized into coordinated aggregate system and non-coordinated individual system. In this paper, each control scheme is discussed theatrically also the pros and cons of each is addressed from technical point of view.

CFD Simulation Research on Agglomeration between Coal-fired Ash Fine Particulate and Atomized Droplets

In this paper, a collision model between atomized droplets of agglomeration solution and particles is established. On this basis, the effects of flue gas temperature, atomized droplet diameter and other factors on the particle agglomeration process are studied. In addition, the evaporation model of agglomeration solution in the flue of a power plant is established for the coal-fired unit of power plant. Through CFD software, the variation of flow field velocity, temperature and pressure in the flue is simulated to determine whether the chemical agglomeration technology has negative impact on the actual operating conditions of the power plant. The simulation results show that the velocity and pressure of the flow field in the flue have no obvious change after the agglomerating agent is injected. Besides, the temperature drop of about 7°C. The droplets evaporate completely at a distance of 7-8 m after spraying. The evaporation time of droplets is within 1.6 s.

Technical and Economic Impact of the Inertia Constraints on Power Plant Unit Commitment

The whole interconnected European network is involved in the energy transition towards power systems based on renewable power electronics interfaced generation. In this context, the major concerns for both network planning and operation are the inertia reduction and the frequency control due to the progressive decommissioning of thermal power plants with synchronous generators. This paper investigates the impact of different frequency control constraints on the unit commitment of power plants resulting from market simulations. The market outputs are compared in terms of system costs, and of frequency stability performance evaluated on the basis of the rate of change of frequency and the maximum frequency excursion. The best compromise solution is found using a multiple-criteria decision analysis method, depending on the choice of the decision maker’s weighting factors. The proposed approach is tested on a real case taken from one of the most relevant future scenarios of the Italian transmission system operator. The results show how the best compromise solution that can be found depends on the decision maker preference towards cost-based or frequency stability-based criteria.

Study of change in 300 MW power unit efficiency operation under reduced loads

The article presents the results of the study of technical and economic parameters of power unit’s operation under reduced turbine generator loading, related to the night power dip and wear of power plant units. Changes in fuel consumption under reduced loading, change in power unit efficiency and change in main specific characteristics of the power unit were investigated. Conclusions on the 300 MW power unit’s operation modes under different turbo-generator loads were drawn based on the results of the calculations and investigations.

Improving the Efficiency of the Three-Stage Technique of Mathematical Model Identification of Complex Thermal Power Equipment

The problems of state estimation of thermal power system operation and identification of mathematical model parameters have not been acceptably solved due to the complexity of studied objects and their mathematical models, and the lack of effective methods, algorithms and computer programs to solve the required mathematical problems. The results of solving the indicated problems are of importance as such, and play a great part in the qualitative solution to the problems of thermal power equipment control, e.g., the problems of optimal load dispatch among thermal power plant units and optimal control of thermal power equipment operation conditions. The paper describes an effective three-stage technique of mathematical model identification of complex thermal power equipment. The technique allows us to more effectively detect gross errors in measurements of control parameters used for identification of the mathematical model of the studied equipment, to evaluate correctness and rectify errors in the mathematical model construction, and to improve identification accuracy. The article presents a new formulation of the optimization problem for more efficient identification of mathematical models of heat power equipment. An effective three-stage technique of mathematical model identification of complex thermal power equipment was tested on a detailed mathematical model of the present-day 225 MW generating unit that was constructed by the author. The paper presents results of solving the identification problem of mathematical model parameters of a generating unit.

Experimental studies of a hybrid car and electric car interference immunity

This article covers a hybrid car interference immunity research. A combined unit-power plant vehicle prototype (a hybrid car) of a famous Russian brand is a subject of this research. Its configuration included a motor control center in boot of a car and a standard internal combustion engine control system (ICE) with upgraded software for joint operation of two power plants.

Long-term operation of a boiling pressure vessel and its internals

This study concerns the long-term operation (LTO) of a boiling water reactor (BWR) reactor pressure vessel (RPV) and its internals. The main parts of this study are: survey on the susceptibility to degradation mechanisms, and computational time limited ageing analyses (TLAAs). The ageing of nuclear power plants (NPPs) emphasizes the need to anticipate the possible degradation mechanisms. The BWR survey on the susceptibility to these mechanisms uses the RPVs and significant internals of the Olkiluoto power plant units OL1 and OL2 as a pilot project. For the components that screened in, the potential to brittle, ductile or other degradation is determined. This was carried out by applying structural mechanics and fracture mechanics procedures. Only some most significant cases and results are presented here.

Peculiarities of the Use of Heat-Resistant Steels for Steam Pipelines and the Elements of Their Systems

Power generating units of heat and power plants equipped with steam boilers that have supercritical and high steam parameters and the system of steam pipelines produce the major portion of electric power in Ukraine. This scientific paper describes the peculiarities of the use of heat-resistant pearlitic steels of 12Х1МF, 15Х1М1F, 12Х2МFSR grades and others. These steels are used to manufacture the elements for the steam pipelines of thermal power plants whose service life has already run out and it is a vital problem at the moment. This scientific paper looks into the reasons for the appearance of damages and degraded operating performances of the welded pipe junctions of steam pipelines. The research data obtained during the studies of the structure and mechanical properties of the welded junctions of steam pipelines have been given. Consideration was given to the factors that affect welded junctions during their long-term operation. It was established that the welded junctions made of heat-resistant pearlitic steels degrade during their long-term operation following the creep crack formation mechanism. It was established that the welded junctions of steam pipelines with the accrued operating time of 270.000 hours and an increased number of the start-stop cycles of power generating units are characterized by an increased probability of faults following the fatigue mechanism. It depends to a great extent on the local concentration of stresses in the structures of welded junctions and their structural state.

ENSURING THE QUALITY OF MANUFACTURING GEAR TRANSMISSIONS IN POWER MECHANICAL ENGINEERING

The development of modern power engineering goes along the line of continuous increase of speeds, efficiency and power units. Gears and gearboxes are crucial parts of modern mechanisms and occupy an important place in the domestic power engineering industry. The strength and durability of gears, in addition to design factors, to a large extent depends on the processing techniques. The final stage of manufacturing such wheels is the gear grinding operation. In the process of tooth-grinding, complex and unique thermomechanical processes take place in the thin surface layer. As a result of short-term heating to high temperatures, structural transformations, called prizhogami, occur in such a surface layer, and in some cases even micro and macro-cracks. In addition, there are cases of manufacturing gears with hidden grinding defects (for example, the appearance in the surface layer of teeth of large tensile stresses), which reduces the service life, and in some cases causes the teeth to break under operating conditions. The development of effective measures to ensure the quality of the surface layer during a gear grinding operation largely depends on the ability to predict (or calculate) temperatures and residual stresses along the depth of the cemented tooth layer. A method for calculating the internal residual stresses arising during gear grinding of wheels from cemented steels is proposed. On the basis of the performed calculations and experiments, the ways of improving the quality of manufacturing the working surfaces of gears used in units of thermal and nuclear power plants are proposed and substantiated.

Solar-assisted steam power plant retrofitted with regenerative system using Parabolic Trough Solar Collectors

This work investigates the performance of a conventional steam power plant retrofitted with a solar-assisted regenerative system using Parabolic Trough Solar Collectors (PTC). The solar collectors were used to compensate for the effect of removing Low-Pressure (LP) turbine extractions without changing other elements of a 300 MW power plant unit during peak load operations. The steam power plant, located in Kuwait, receives high levels of solar irradiation. Modeling of the solar-assisted regenerative system using PTC is simulated for Kuwait’s weather conditions. Results of the system analysis show that removing the LP turbine extractions enhanced the performance of the steam power plant by 9.8 MW, with an optimum PTC aperture area equal to 25,850 m2. A techno-economic analysis was used to estimate the Levelized Cost of Energy (LCOE). Compared to an equivalent photovoltaic solar plant, the optimum aperture area and LCOE for the PTC solar plant were found to be less by 45% and 44%, respectively. When compared to an equivalent conventional steam turbine, the solar-assisted steam power plant decreased cost by 56% over the lifecycle of 25-years.

Energy and exergy analyses of a novel ammonia combined power plant operating with gas turbine and solid oxide fuel cell systems

This study deals with a new combined power plant that utilizes only ammonia as a fuel for multigeneration purpose. The system comprises two main powering sources, a gas turbine cycle (GTC) running on ammonia and using hydrogen as a promoter, and ammonia fed solid oxide fuel cell (SOFC). The waste heat from the gas turbine exhaust gases is recovered using Rankine cycle (RC) to generate additional electric power, and the waste heat from the condenser of the RC is utilized to heat water for residential application. The residual thermal energy from the exhaust gases is used to operate an absorption chiller system (ACS) to provide refrigeration for the industry. The electricity generated from the RC is supplied to an ammonia electrolyzer to produce hydrogen, which can be stored for other applications. The system is analyzed thermodynamically using the first and second laws of thermodynamics. Moreover, Exergy destruction and losses of the different combined power plant units are determined. Furthermore, a comprehensive parametric study is carried out to investigate the effect of varying ambient conditions, operating and design parameters on the overall performance of the combined system and subsystems. The energy and exergy efficiencies of the multigeneration system are found to be 58.78% and 50.66%, respectively.

Increasing the efficiency of the thermal power units at zoning of heat load curve

The article deals with the work of heat and power units of thermal power plants in the conditions of disaggregation of the heat load schedule. The purpose of the work is to increase the efficiency of operation of CHP units operating under the conditions of the zoned temperature schedule. To achieve the obtained results, mathematical modeling based on the methods of differential-exergetic and thermodynamic analysis; methods of material, energy and exergetic balances. Research has shown that in order to increase the efficiency the original method of splitting the temperature graph into three zones can be used, each of which is characterized by the method of regulation of heat supply, and to assess the effect of the minimum fuel consumption criterion can be used. The method of determining the equivalent design temperature, which takes into account the regime peculiarities of heat and power units in the form of a method of regulation of heat supply, is developed. Study has shown that three design points should be available when zoning the temperature schedule. Based on optimization calculations for standard sizes of heat and power units of a wide range of capacities, the calculations show that the optimal parameters of heat and power units in the conditions of zoning of the temperature schedule as a whole correspond to the standard values. In addition, it is shown that in each zone of the temperature schedule there is a saving of fuel, which can be from 3 to 30% depending on the type of power unit, its capacity and zone of the temperature schedule, and the annual fuel consumption of the heat and power units can be reduced by approximately 10%. It is shown that when conventional power units operate according to the zoned temperature schedule and in the first zone (quantitative regulation), preference should be given to power units with steam production. In the second zone (mixed regulation), the operation of power units with steam extraction and heat and power units is equivalent. In addition, in the third zone (qualitative regulation) preference should accrue to heat and power units.

Assessment of Optimum Slurry Pipe Design for Minimum Erosion

Particulate erosion is a major concern in slurry handling unit of a thermal power plant. The pipe bends are the most erosion affected element of a pipeline unit thus, a cost-effective method to reduce pipeline erosion is highly desirable. This work aims to suggest the optimal pipe bend design to minimize the particulate erosion by analyzing the erosion wear in geometrically different pipe bends for bottom ash slurry flow by using Computational Fluid Dynamics code FLUENT. A Three-dimensional simulation study of erosion wear is carried out by implementing Euler-Lagrange modeling along with the standard k-ε turbulence model to solve the complex multi-phase flow. Pipe bends of different bending angle (30°, 45°, 60°, and 90°), diameter (50 to 250 mm) and bending ratio (r/D = 1 to 2.5) are evaluated at different flow condition. The wear location gets shifted to the upper section of the bend and its magnitude is significantly reduced with the increase in pipe diameter and bending angle. The dynamics of multiphase slurry through different bends is analyzed to understand the complex wear phenomenon. The simulation result shows good agreement with the published findings. Finally, a least erosion affected pipe bend profile is suggested for slurry transport unit.

Optimization of Flow Field and Nox Concentration Field of Denitrification System in Coal-Fired Power Plant

A unit of a coal-fired power plant in North China was selected to study. The flow field distribution and NOx concentration distribution at the inlet and outlet of the denitrification system are tested. Then, the flow field adjustment and optimization of the unit are carried out based on the above test results, and the verification test of optimized flow field and NOx concentration distribution are carried out. After the flue optimization, the uniformity of NOx concentration distribution at SCR reactor inlet and outlet was improved, and the flue rate at SCR reactor inlet need further optimization through combustion adjustment.

Water filter with central perforated pipe for livestock complexes

Improving the livestock sector is a priority for the development of agricultural production in the Russian Federation. The development of animal husbandry to a certain extent depends on the use of clean drinking water. The use of contaminated drinking water for animals and birds leads to the accumulation of harmful and toxic substances in meat, milk and eggs. The use of such products by people significantly affects their health, leads to various diseases and shortens life expectancy. To filter water from various impurities, slotted filters are used in livestock complexes that do not provide high-quality water purification. A prototype of a filter for water purification with a central perforated pipe with a productivity of 5 m3/h with an increased service life of the filter bag has been developed. The developed filter provides water purification from high concentration of salts of iron, manganese, chlorine, hardness salts, hydrogen sulfide, pesticides, and also various organic compounds. The purified water is clean and transparent, has a pleasant taste, contains the optimal chemical composition of various impurities, does not contain pathogens and helminth eggs, and therefore meets the high sanitary and hygienic requirements for the safe drinking water for farm animals in the water treatment line of the livestock complex. It can also be used in chemical water treatment units of thermal power plants and other organizations.