Power Plant Unit Research Articles

Работа осевой турбинной ступени в области малорасходных режимов. Общие положения

The involvement of power units of thermal power plants (and many power units of nuclear power plants in the near future) to regulate the frequency in the electric network leads to the expansion of shutdowns or equipment deep unloading at night. This circumstance negatively affects the reliability, efficiency and service life of power plants. With significant unloading the operation of turbines is accompanied by ventilation power losses, ventilation heating, and a significant increase in the axial flexural-torsional resonance vibrations of the working blades of the steam turbine at the last stages. In addition, at low-flow rates, the maximum erosive wear of the input edges of the working blades of the last stages by coarsely dispersed droplet-impact moisture and their outlet edges occurs by the reverse currents of the vapor-droplet mixture and moisture particles sucked from the condenser and the outlet pipe of the exhaust part of the LPC into the flow path of the cylinder. On the one hand, the nature of the steam flow spatial structure at low-flow modes of steam turbines operation is well studied. But on the other hand it needs to bring to the used terminology uniformity and clarify the characteristics of the modes.

Research on Vibration Fault Diagnosis Technology of Steam Turbine Unit in Power Plant Based on Wavelet Theory

Aiming at the frequency spectrum characteristics of the vibration of steam turbine generator sets, a fault diagnosis method of steam turbine rotor vibration based on wavelet packet transform is proposed, which can better reflect the spectral components and energy contained in vibration signals than general wavelet transform. Experimental analysis shows that the fault feature extraction method based on wavelet packet analysis and signal energy decomposition can obtain the fault status of steam turbine rotor vibration; according to the frequency spectrum characteristics of different faults, different faults can be identified, so as to perform steam turbine rotor vibration fault diagnosis. This method is more effective than the fault feature extraction method based on Fourier transform and is suitable for mechanical fault diagnosis.

Application Study on Zero Output Technology of Low Pressure Cylinder of 350MW Supercritical Unit

In response to the requirement of national thermal power flexibility reform policy and the need of regional central heating development, a 350MW supercritical unit in a power plant has been transformed with zero output technology of low pressure cylinder. In this paper, the scope and content of low pressure cylinder zero output transformation are discussed, peak shaving and heating capacity after transformation are analyzed, the difference between operation effect and calculation result after unit transformation is compared by test, and the matters needing attention in future operation are given, which provides reference for technical transformation of low pressure cylinder zero output of other power plant units.

Analysis of Leakage and Corrosion of Air Preheater in Coal-Fired Power Plant

A unit of a coal-fired power plant (300MW) in North China was selected to study. The flue gas parameters (NH3, O2 and flue gas temperature) at the outlet of denitration system, oxygen content at the inlet and outlet of air preheater, and composition of combustion coal were tested. Then, the air leakage and corrosion of air preheater were evaluated from the operation of denitration system, air preheater leakage detection, and acid dew point calculation of flue gas. The influence of ammonium hydrogen sulfate from denitration system on the downstream air preheater is limited due to the low ammonia escaping. The air leakage rates of the air preheater at the side A and B were 8.45% and 3.01%, which are higher than the normal value (< 3%). Due to the air leakage of air preheater on side B, the cold end temperature of air preheater is significantly lower than the acid dew point of flue gas, resulting in the condensation of sulfuric acid mist in flue gas on the air preheater and the sulfuric acid corrosion on the air preheater.

Reliability and Maintainability Investigation of Generator in Steam Turbine Power Plant using RAMD analysis

Generator is key unit of steam turbine power plant which is used to convert mechanical energy into electrical energy. This energy is further used for completing the requirement generated by various sectors of country. Generator is one of the most important component of steam turbine power plant configured with seven subsystems in series configuration. So, it is necessary to ensure its smooth functioning which is attain by the proper functioning of its subcomponents. It is important to increase operational availability of subsystem. Hence, present study is proposed to investigate various reliability measures of generator used in STP through RAMD approach at component level. For this purpose, mathematical models using Markovian birth death process have been developed for all subsystems of generator. These models are very helpful in reliability, maintainability, and availability analysis of generators. RAMD analysis will play significant role in this direction. This will help to find critical component of system so that proper maintenance strategies can be proposed. It is assumed that all failure and repair rates associated with each component followed exponential distribution and adequate repair facility always remains available with system. Various system performance measures like reliability function, maintainability function, dependability function and steady state availability for different components as well as system have been evaluated. The numerical results have been derived to highlight the importance of study.

Methodology and hardware-software complex for diagnosing diesel generator units of nuclear power plants

Methodology and hardware-software complex for diagnosing diesel generator units of nuclear power plants

Using a heat pump at the polygeneration complex in agricultural industry

Environmentally friendly technologies in agriculture and agricultural industry are associated with the processing of products in polygeneration complexes. These complexes include the main line of product processing, the energy complex for the production of steam and hot water, as well as the refrigeration complex. A principle diagram has been developed for solar collectors and the improved lithium bromide refrigeration machines connected to power units of thermal power plant operating on natural gas. According to preliminary estimates, the proposed scheme increases the thermal power plant efficiency by 2-3%. This complex can be used to produce compressed carbon dioxide, which has applications in various industries. The most common is its use in the agricultural industry and the oil industry.

Methodology and hardware-software complex for diagnosing diesel generator units of nuclear power plants

Methodology and hardware-software complex for diagnosing diesel generator units of nuclear power plants

Topping with a Natural Gas-Fired Combined Cycle Unit of a Coal-Fired Cogeneration Power Plant with Cross Connections

Thermal power plants (TPP) with cross connections and having a minimum reference fuel rate of 321 g/(kW h) prevail in the structure of the generating capacities in Russia. In practice, this characteristic is often above 500 g/(kW h). Application of parallel-type, dual-fuel combined-cycle units (CCUs) using coal as the main fuel, for improving the efficiency of power plants with cross connections is considered. Such CCUs have high efficiency and are suitable for modernization of operating subcritical power plants with cross connections. The power of CCUs with gas turbines manufactured in Russia or having a high degree of production localization in Russia can be as high as 200–250 MW. In all the cases, a new heat-recovery steam generator (HRSG) and a new steam turbine for a live-steam pressure of 12.8 and 8.8 MPa must be developed. The paper considers the process features of such dual-fuel cogeneration CCUs based on a 6FA gas turbine. A CCU thermal scheme is developed. Bled steam conditions under different operating conditions are determined considering the bypass of the main condensate and feedwater lines. GCU performance indices as a function of ambient air temperature are determined. In addition, an option was considered for modernizing the existing cogeneration power plant (TETs) in the town of Seversk by implementation of a dual-fuel CCU based on an 82 MW 6FA gas turbine and a T-96/122-8.8 steam turbine while maintaining the coal-fired power steam boilers in operation. It is demonstrated that the proposed modernization option makes it possible to reduce the fuel cost by approximately 240 million rubles per year while increasing the electricity delivery under cogeneration conditions by 1.7 times.

Evaluation study on the effect of production and fluid reinjection towards reservoir using micro gravity in Kamojang geothermal field

Geothermal fluid exploitation is expected to cause physical as well as chemical changes to the reservoir of a geothermal field. This is what happened to Kamojang Geothermal Field which has been producing for four periods, starting from the initial production capacity of 30 MW (1983) which became 140 MW (1987), then 200 MW (2008) and 235 MW since 2015 up to now. To observe changes of subsurface condition, Microgravity, is called time-lapse gravity as well, as one of geophysical survey activity is carried out in order to obtain the reservoir changes in a wider view based on the changes of gravity value as a reflection of rock density changes due to the extracted fluid mass. Generally, the microgravity study result from 1984 until 2018 shows the existence of microgravity value changes which correlates to the amount of fluid mass produced and the water mass which was reinjected back into the reservoir. This can be observed from the Time-lapse Anomaly Map in accordance to each of the production period of Geothermal Power Plant (GPP) Unit 1, 2, 3, 4 and 5.

Оценка динамических нагрузок на стены и перекрытие подреакторного помещения РБМК-1000 при паровом взрыве

One of the conditions for the safe operation of a nuclear power plant (NPP) unit is a comprehensive design and experimental justification of its failure-free operation in all operating modes and limitation of accident radiation consequences, including those in the case of severe beyond design basis accidents. According to the nuclear power industry development plans in Russia, new NPPs equipped with RBMK-1000 reactors are not supposed to be constructed in the future. Although the assigned service life of RBMK-1000 based power units that remain in operation is close to expiration, these power units account for most of the electricity generation in the total amount of nuclear power capacities in Russia (about 40%); therefore, the relevant industry organizations have decided to extend their operation. This article analyzes the severe accident evolvement scenario at an RBMK-based NPP during the stage of severe core damage, in the course of which fuel-containing masses collapse into the subreactor space filled with water. Once fuel-containing masses emerge in the sub-reactor room, they come in interaction with the reactor base concrete. There is a potential danger of the concrete floor slab melting and the corium collapsing into the bubbler pool water. The main strategy foreseen for keeping the molten core within the reactor space boundaries involves decay heat removal from the reactor and cooling of the support metal structures by supplying water. However, the filling of the subreactor space with liquid may give rise to conditions under which vapor explosion can occur. The maximum dynamic impact applied to the RBMK-1000 subreactor room walls in the event of possible interaction between the molten corium and water during a severe beyond design basis accident is estimated. It is shown that when the corium melt interacts with a large amount of water in the subreactor room, the kinetic energy of the resulting water vapor is sufficient to cause significant destruction of the power unit building. When the water level in the subreactor room falls below one meter, the destruction hazard becomes less probable. The mass of hydrogen released as a result of the interaction is also estimated.

Оцінювання вірогідності контролю параметрів ізоляції обмотки статора блока ''генератор–трансформатор''

It is shown that significant aging of electrical equipment of power plants, high cost of failures, the need to continue its operation, compliance with safety rules requires increasing the reliability of monitoring the technical condition of insulation. Analysis of existing methods of continuous monitoring of the technical condition of the insulation of the stator winding of a synchronous generator operating in a unit with a transformer showed their significant shortcomings, namely the low sensitivity to changes in insulation damage near the neutral of the stator winding and symmetrical reduction of insulation parameters. This does not allow to detect damage at an early stage of its development. In addition, there is a faulty operation of the controls due to asymmetries of phase voltages. To increase the probability of controlling the insulation parameters of the stator winding of the synchronous generator, the method, principle of construction, algorithm of diagnostic control complex, as well as software algorithm used to process measurement data and determine the insulation parameters of the stator winding based on microprocessor. The probability of control of the proposed method of controlling the insulation of the stator winding of a synchronous generator operating in a unit with a transformer based on the superimposition on the circuit containing the stator winding, AC signals with a frequency lower than the rated frequency, DC voltage, use the energy of the pre-charged capacitor and the calculation of the insulation parameters of the "generator-transformer" unit. Expressions are given to determine the total active resistance relative to the ground and at the place of formation of the shunt connection with the ground, the equivalent insulation capacity, the tangent of the dielectric loss angle in the insulation, the probability of false and indefinite failure, the probability of “suitable” multiparameter control. The expressions necessary for calculating the probability of control of active resistance relative to ground, transient resistance at the place of shunt formation, insulation capacity relative to ground, tangent of dielectric loss angle of stator winding of synchronous generator operating in block with transformer are obtained. Based on the obtained expressions, the probability of the result “suitable” is calculated. The results of calculations can be used in the design of relay protection and diagnostic systems for electrical equipment of new power units, as well as in the reconstruction of existing power units of power plants.

On the issue of the use of waste from water desalting ion exchange units of power plants

On the issue of the use of waste from water desalting ion exchange units of power plants

Results of the study of vibrations of concrete structures of the hydropower plant building

The paper considers the results of studying vibrations of certain components of the hydropower plant building and their influence on the structure of the building as a whole. Vibration loads on various elements of the hydropower plant building which can cause damage to the building, thereby reducing the operational reliability of the whole structure and doing potential harm to the environment and human life support, is analyzed. The necessity for vibration monitoring of structures which should be conducted constantly or periodically to determine the present condition of structures is reasoned. Vibrations of the section concrete parts and vibrations of hydroelectric power plant units are considered. To detect the vibrational movements of the section as a solid body on an elastic base Section № 2of the hydropower plant building has been chosen. The recording of vibrations has been conducted for all three components: Z (vertical), H II (horizontal, parallel to the flow) and H ⊥ (horizontal, perpendicular to the flow) and the obtained data are given in this paper. The intervals of observed and dominant periods of vibrations are estimated. The research provides the data on amplitudes and accelerations of vibrations, as well as on the maximum recorded peak-to-peak swing. Based on the analysis of the received vibrograms, it is stated that the recorded vibrations are non-periodic and have a relatively narrow range of periods. In conclusion it is underlined that in order to determine the maximum possible amplitudes of section vibrations as well as to calculate the corresponding dynamic stresses in ceiling trusses it is necessary to observe vibrations when hydraulic units are operated simultaneously and the flow passes through the fully open bottom spillways of the inspected section.

Data modelling and simulation control of steam heat circulation system in coal-fired power plant

To make up for the lack of domestic research on the dynamic model of the unit in a gas-steam combined cycle power plant, the thesis researched and established a real-time digital simulation model of the combined cycle power plant unit. Firstly, the theory found a non-real-time digital simulation model in MATLAB/SIMULINK environment. Then the paper converts it into C language code and uses the C Builder tool to encapsulate it into a simulation model that can run in real-time. Finally, the thesis conducted a simulation test on the model on real-time digital simulation and compared it with the field test results. The simulation results show that the combined cycle power plant unit model we have established can meet the real-time simulation requirements of the power system in terms of computational efficiency and model accuracy.

4E analysis and multi-objective optimisation for a solar hybrid steam power plant using ABC algorithm: a case study in Iran

The objectives of this study are 4E analysis and multi-objective optimisation for solar hybrid fossil fuel power generation system and steam power plant without solar field (WSF) of Karaj during a year. The analysis is performed using MATLAB programing, and validated with a power plant unit data. The results show that system with oil-water heat exchanger (solar hybrid system), has less CO2 emission and fuel consumption than WSF power plant but 2.8% more exergy efficiency. The annual average contribution of steam on the production of electricity during sunny hours and during the day, are 15% and 7.3%, respectively. By using artificial bee colony (ABC) algorithm, system is optimised for maximum exergy efficiency and minimum cost of produced electricity. Furthermore, sensitivity analysis is performed to study the solar tracking modes, changing the number of collector loops, capacity of the power plant, interest rate and plant economic life on unit cost.

A review study on the active methods of heat transfer enhancement in heat exchangers using electroactive and magnetic materials

The paper focuses on the review of different techniques for minimization of energy consumption by increasing the heat transfer enhancement in the heat exchangers, which are being used in several fields like solar air heaters, automobile radiators, condenser, and evaporators of power plant units, refrigeration unit, steam turbines, etc. There are several techniques to enhance the heat transfer, and all are classified under Active and passive methods. In Active methods, there is the use of an external power source, while in passive methods the modification of the inner surface of the heat exchanger is made by using inserts, etc. In both, the processes increase in heat transfer also cause the subsequent increases in friction factor causing more pumping power requirement. The present review work presents the various active methods and materials that are used to enhance the heat transfer while keeping the friction factor as low as possible. The new techniques like electroactive and magnetic material are also discussed in the article which enhances the rate of heat transfer in combination with passive methods. The Electrohydrodynamic method shows an increase in heat transfer by 20 times as compared to only 3 times increase in friction factor while using vibration the increases in heat transfer is by 97%. The magnetic material has increased the Nusselt number in combination with the passive technique by 10%.

IMPROVEMENT OF ICS OF POWER PLANT UNIT FOR DIFFERENT MODES OF OPERATION

The analysis of the criteria for improving the technical and economic efficiency in the operation of the electric power equipment of power units of power plants. It is indicated that the existing methods for calculating the technical and economic effect do not take into account the factors that lead to technical and economic costs when the power unit is stopped and the load of electricity consumers is reduced. A significant factor in increasing the technical and economic efficiency in the operation of automated control systems for technological processes at the power unit of the power plant is operational control to identify information with a low level of reliability. It is shown that the reliability of the functioning of the technological equipment of the power unit significantly depends on the efficiency of automated control in emergency situations, when unauthorized shutdowns of the power unit occur due to false alarms. It was found that the reason for false alarms is information about the parameters of the technological process of the power unit, which is characterized by a low degree of reliability. It is shown that unforeseen unauthorized shutdowns of the power unit and a decrease in the load for power consumers lead to significant economic and material losses, and, consequently, to a decrease in technical and economic efficiency with automated control of the power unit. It is shown that the applied technical and economic models do not take into account financial and material costs that occur due to an unauthorized shutdown of the power unit and a decrease in the load for electrical consumers in case of false alarms in real time. A unified integrated economic and mathematical model has been developed, which allows calculating the economic effect, taking into account the change in the reliability of the technological equipment of the power unit, due to the timely prompt detection of false alarms and information with a low degree of reliability. To calculate the economic effect on the basis of the developed unified economic and mathematical model, a modular block of the mode of emergency situations is proposed, associated with the modules of false positives and emergency signs, taking into account the static and operational technical and economic components. Practical recommendations are given for using the technical and economic module in the software and hardware complex of the power unit, which allows calculating the technical and economic effect based on statistical data coming from the data memory and current data from the power unit.

Selective sulfur removal from semi-dry flue gas desulfurization coal fly ash for concrete and carbon dioxide capture applications

High-sulfur mixed fly ash residues from semi-dry flue gas desulfurization units in coal-fired power plants are unsuitable for use as supplementary cementitious material (SCM) for concrete production or carbon dioxide utilization. In this work, we explore the potential for upcycling a representative spray dry absorber ash (10.44 wt% SO3) into concrete-SCM by selective sulfur removal via weak acid dissolution while simultaneously exploring the possibility for CO2 capture. Towards this effort, parametric studies varying liquid-to-solid ratio, acidity, and CO2 pressure were conducted in a batch reactor to establish the sulfur removal characteristics in de-ionized water, nitric acid, and carbonic acid, respectively. The dissolution studies show that the leaching of sulfur from calcium sulfite hemihydrate, which is the predominant S phase, is rapid and achieves a concentration plateau within 5 min, and subsequently, appears to be controlled by the primary mineral solubility. Preferential S removal was sufficient to meet SCM standards (e.g., 5.0 wt% as per ASTM C618) using all three washing solutions with 0.62–0.72 selectivity (S^), defined as the molar ratio of S to Ca in the leachate, for a raw fly ash with bulk S^ = 0.3. Acid dissolution with 1.43 meq/g of ash or under 5 atm CO2 retained > 18 wt% CaO and other Si-, Al-rich phases in the fly ash. Based on the experimental findings, two sulfur removal schemes were suggested for either integration with CO2 capture and utilization processes using flue gas or to produce fly ash for use as a SCM.

Spectroscopy of Radiostrontium in Fuel Materials Retrieved from the Chernobyl Nuclear Power Plant.

Some basic methods of measuring radiostrontium activity by spectroscopic methods are considered in this study. These methods of assessing beta spectra and the characteristic radiation that accompanies the breakdown of radiostrontium are described. The sensitivity of these methods based on the assessments of beta spectra both after radiochemical procedures and without radiochemistry is presented. The objective of this paper is to review the spectroscopic procedures that have been developed and used to determine radiostrontium in various matrices; they are focused on modern methods. Samples of fuel particles of different origins, obtained from the Chernobyl Nuclear Power Plant Unit 4, were analyzed using the methods presented in this study.