Operation Of Thermal Power Plants Research Articles

Features of the Mechanism of Gas-phase Ignition of Wood Biomass Particles

ABSTRACT Use of woody biomass instead of coal as fuel for thermal power plants (TPP) is considered a promising direction for reducing emissions of anthropogenic substances during the operation of coal-fired thermal power plants. But the process of replacing coal with wood in the thermal power industry is happening very slowly due to objective reasons. The main one is the deposition of particles that have not fully passed the pyrolysis stage (in this case, a layer of substance in a resinous state is retained in the wood particle) on heating surfaces (for example, superheaters) and a decrease in the efficiency of using the heat of combustion of fuel as a result of contamination of the heating surfaces. Therefore, when developing technologies for burning dispersed wood in the furnaces of boiler units, reliable experimental data are required on the characteristic times of ignition and combustion of woody biomass particles, taking into account the time of transition from local (focal) gas-phase ignition to the combustion of volatiles in the entire vicinity of the particle (tsf). The article presents the results of experimental studies of flame propagation processes in the small vicinity of a particle during the ignition period. The experiments made it possible to establish that the flame propagation velocity in the small vicinity of the particle significantly depends on the ambient temperature. It is shown that under conditions of low-temperature heating (air temperature Tg = 873 K), the propagation velocity of the combustion (flame) is minimal. An increase in Tg values (from 873 K to 1273 K) leads to a significant (4–5 times) increase in the time of complete flame coverage of the particle. According to the results of the experiments, two heating modes were identified: high-temperature and low-temperature with a conditional interface Tg = 873 K. At Tg = 873 K, the characteristic particle size of wood biomass has no significant effect on the characteristics and conditions of flame propagation in a small vicinity of the particle. An increase in the ambient temperature (up to 1273 K) leads to an increase in the influence of particle size on the characteristics and conditions of flame propagation. A hypothesis describing the process of flame propagation has been developed.

Thermal energy storage integration for increased flexibility of a power plant with post-combustion CO2 capture

Flexible operation of thermal power plants will become increasingly relevant in the coming years. This work evaluates the effect of integrating a steam accumulator into a 598 MW supercritical coal-fired power plant with moving bed temperature-swing adsorption CO2 capture. Charging the accumulator with reheat steam from the turbine train can reduce the net power output by up to 1.4 % (8.2 MW) for around 200 min. Small charging flow rates are recommended to maximize the final pressure of the accumulator. Covering the sorbent regeneration duty and meeting the demand of two feedwater heaters were considered as alternatives for discharging of the accumulator. Thermal storage discharging was found to give relative power plant load increases between 1.7 and 11.2 % (10.2–66.9 MW) for up to 37.5 min, which exceeds the requirement for primary reserve. Increases in the electrical energy output of 10.5–11 MWh were achieved. The flexibility modes studied in this work are compatible with high CO2 recovery rates.

ISSUES OF WATER USE IN THERMAL POWER PLANTS. PROBLEMS AND SOLUTIONS

The article considers the most effective methods of water treatment for thermal power plants. Water treatment is one of the most important processes in the operation of thermal power plants (TPP). The quality of water treatment for use in boiler units of thermal power plants is of fundamental importance to ensure the efficiency and durability of process equipment. This article reviews the main aspects of water treatment in TPP plants, including treatment methods, water quality characteristics and standards, and the impact of water treatment on the overall energy efficiency and safety of power generation in TPP plants.

An Opportunity for Coal Thermal Power Plants Facing Phase-Out: Case of the Power Plant Vojany (Slovakia)

The study deals with the possibilities of using alternative types of fuels to produce electricity. Power Plant Vojany (PPV) is a thermal power plant (TPP) in eastern Slovakia, which is part of the company Slovenské elektrárne, a. s. (SE). PPV primarily used black coal to produce electricity, which had to be imported from abroad (the Russian Federation). This activity has become inefficient both economically and environmentally, due to the high price of CO2 permits and the high emission factor of this type of fuel. PPV decided to co-combust biomass and refuse-derived fuel (RDF), which resulted in much better economic conditions due to their price, economic efficiency, and partly closed CO2 cycle. The aim of the paper is to explore the possibilities related to the production of energy in the cleanest possible way and with the least possible damage to the environment in coal thermal power plants using the example of operating Power Plant Vojany located in eastern part of Slovakia and to inspire each other for the modern transformation. For the purposes of hypothesis verification, analytical methods focused on overview studies of average fuel prices, comparisons, and the balance of fuels in connection with eliminated CO2 emissions, as well as municipal waste (MW) management in the EU and V4 countries, were used. The authors also focused on the energy recovery and combustion of MW and tracking the achieved CO2 savings in connection with the development of fuel sources in PPV. The results point to the fact that PPV is one of the power plants that could use biomass and RDF as fuel, which confirms the economic advantages of this procedure. The results confirm that the potential of RDF production in Slovakia is sufficient to ensure the operation of PPV at planned, even higher volumes of electricity production. The transformation to cleaner operation of coal thermal power plants represents a significant contribution of this study.

Proposal design and thermodynamic analysis of a coal-fired sCO2 power system integrated with thermal energy storage

It is essential to develop supercritical carbon dioxide (sCO2) power systems integrated with thermal energy storage (TES) to achieve efficient and flexible operation of thermal power plants. This study proposes a novel integrated configuration of the sCO2 coal-fired power system and TES. The extracted sCO2 from the high-pressure turbine inlet is utilized as the source of the stored heat, and the extracted heat is used for storage, work, and recovery in steps to decrease the feasible lowest power load ratio. While in the discharging process, the stored energy is used to heat the branched sCO2 to increase the output power. Thermodynamic models for both design and off-design conditions are developed, and the multi-parameter optimization is carried out by genetic algorithm aiming at the highest energy efficiency. The energy conversion characteristics of the heat storage/release process are obtained, and the impacts of variations in the sCO2 extraction ratio and the initial temperature of the molten salt on the performance are analyzed. The results indicate that the adjustable power load range of the integrated system widens with an increase in the sCO2 extraction ratio. When the extraction ratio reaches its maximum value of 0.2749, the minimum power load of the charging process can reduce from 30 % of the rated load to 10.47 %, and the load of the discharging process can increase from 75 % of the rated load to 88.20 %, thus enhancing the operational flexibility. At this point, the round-trip efficiency of the TES system is 67.56 %, which is mainly limited by the performance of the charging process, especially the throttling loss of the turbine. Furthermore, as the temperature of the molten salt cold tank increases, the heat storage capacity decreases, while the minimum power load of the unit increases, thereby reducing the system's flexibility.

Impact of change in coal quality on operating parameters of thermal power plant Stanari and its risk assessment

The technical and technological characteristics of the Stanari Power Plant block were designed based on the results of the analysis of coal samples from the Raskovac opencast mine. There haven't been any notable variations in the coal quality during the Stanari thermal power plant's present operating term from the project's stated values. For the expected lifetime of mine, i.e., the thermal power plant operation until 2050, it is necessary to unearth the total remaining available coal reserves from the Stanari basin. The thermal power plant's operation may be significantly impacted by variations in coal quality at the Ostruznja opencast mine. The use of coal with quality parameters lower than designed can cause problems in the operation of the boiler, stoppages in operation, and an increased volume of maintenance and overhaul of the boiler. Coal quality control in the process of sampling, mining, transportation, and depositing of coal must be at a level that enables smooth operation of the thermal power plant. This paper presents test results during the operation of the thermal power plant burning coal of different quality, (LCV in range from 9,100 to ?7,500 kJ/kg), a risk assessment of long-term planning, and the effectiveness and economy of the thermal power plant operation. The potential economic effects and reliability of the operation of thermal power plants due to the increased consumption of coal, limestone and self-consumption in operating modes with significantly lower coal quality than designed were analyzed in particular.

Methods of using waste from steam-gas thermal power plants

At present, the composition of steam and condensate in periodic motion during 45кthe continuous operation of thermal power plants is getting worse and worse. Great importance is attached to the prevention of industrial wastewater pollution. In industry, water is used as a raw material and energy source, as a coolant or heater, as a solvent and extractant, and it is purified in wastewater treatment plants and discharged back into water bodies. Therefore, it is important to further improve the engineering work of wastewater treatment in water conservation. Water is the main technological raw material for obtaining steam in thermal power plants. It is the most widely used product in the continuous operation of the plant.

Chemical properties and ecological condition changes of the degraded soils as a result of industrial activities

The article describes the man-made degradation of irrigated soils, resulting from chemical pollution, changes in soil chemistry, and heavy metal pollution during thermal power plant operation. According to the results, the pH value of the soil fell from 7.2 to 6.1 as a result of man-made degradation, ie the acidic environment increased as a result of pollution. Also, some heavy metals, including As - increased by 4.2 times, Cr - by 16 times, Ni - by 2.5 times, Rb - by 3.7 times, Zn - by 4.8 times. Changes in soil environment and soil ecological status have resulted in deterioration in fertility rates and negatively impacted crop yields and quality.

Cooperative Operation of Distributed Energy Resources and Thermal Power Plant With a Carbon-Capture-Utilization-and-Storage System

Carbon-capture-utilization-and-storage (CCUS) system plays a critical role in the process of decarbonization. This paper proposes a cooperative operation model for a CCUS-based thermal power plant and distributed energy resources. The critical purpose is to achieve a higher profit and flexibility together with a lower carbon emission for the CCUS system under the electricity, carbon, ancillary services, and synthesis fuel markets. First, to enhance the operational flexibility in various markets, a critical focus of this paper is on elaborating feasible operation domain of the CCUS system through identifying the physicochemical processes associated with carbon dioxide (CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> ) treatment and multi-energy conversion. Second, a Nash-bargaining framework is developed to describe how the CCUS works with distributed energy resources cooperatively to consume cheap and clean renewables to treat CO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> . Third, to solve the cooperative operation problem efficiently and accurately, an adaptive sequential cone programming (ASCP) method together with a progressive hedging variant of the Benders decomposition (PH-BD) algorithm are designed. Case studies indicate the total revenue of the thermal power plant under the cooperative mode is improved by up to 8.85% and 66.53% compared with the individual mode with and without the CCUS. Further, the solution quality and efficiency of proposed methods are verified.

A computer vision approach to improve maintenance automation for thermal power plants lubrication systems

PurposeLubricating oil leakage is a common issue in thermal power plant operation sites, requiring prompt equipment maintenance. The real-time detection of leakage occurrences could avoid disruptive consequences caused by the lack of timely maintenance. Currently, inspection operations are mostly carried out manually, resulting in time-consuming processes prone to health and safety hazards. To overcome such issues, this paper proposes a machine vision-based inspection system aimed at automating the oil leakage detection for improving the maintenance procedures.Design/methodology/approachThe approach aims at developing a novel modular-structured automatic inspection system. The image acquisition module collects digital images along a predefined inspection path using a dual-light (i.e. ultraviolet and blue light) illumination system, deploying the fluorescence of the lubricating oil while suppressing unwanted background noise. The image processing module is designed to detect the oil leakage within the digital images minimizing detection errors. A case study is reported to validate the industrial suitability of the proposed inspection system.FindingsOn-site experimental results demonstrate the capabilities to complete the automatic inspection procedures of the tested industrial equipment by achieving an oil leakage detection accuracy up to 99.13%.Practical implicationsThe proposed inspection system can be adopted in industrial context to detect lubricant leakage ensuring the equipment and the operators safety.Originality/valueThe proposed inspection system adopts a computer vision approach, which deploys the combination of two separate sources of light, to boost the detection capabilities, enabling the application for a variety of particularly hard-to-inspect industrial contexts.

Application of Model-based Deep Reinforcement Learning Framework to Thermal Power Plant Operation Considering Performance Change

In recent years, there have been increasing expectations for the development of advanced plant operational support systems that can automate complex tasks and autonomouslyoptimize operational procedures in thermal power plants. The performance of the equipment changes during operation and maintenance; hence, it is necessary to adjust the operating process to satisfy the operational constraints. In this study, we investigated a framework based on model-based deep reinforcement learning for acquiring control methods that are robust to changes in equipment performance using a digital twin model. A case study of the operational planning of a thermal power plant was presented and it was demonstrated that a stable control system can be constructed even when plant characteristics are changing.

A Study on The Projection of Coal-Fired Thermal Power Plants

In this study, the main countries with high coal-fired power plant installation capacity and Türkiye, which are among the first in the world in electricity production in this field, and Türkiye are discussed, and parameters such as the installed power and capacity developments of the coal-fired power plants in these countries, electrical energy production values and CO2 emissions from fossil fuels have been evaluated over the years. Emissions from fossil fuels have been evaluated over the years. In this study, predictions about the future of coal-fired power plants were tried to be made by making projection studies. Analysis results are indicated and interpreted with figures and tables. When projections are made according to the current situation, it is predicted that in 2030 and 2050, China will be the first in coal-fired power plant installed power development and electricity production, and accordingly in CO2 emissions from fossil fuels. In addition, the capacity utilization rates, which are an important parameter regarding the efficient operation of coal-fired thermal power plants and their age, have been determined for certain countries over the years. In this study, the country with the highest capacity ratio, with a capacity ratio of around 90%, was determined as Japan. Today, in connection with the re-emergence of coal with the emergence of the energy crisis, energy production planning, and projection studies gain strategic importance for each country. In the literature, country-based projection studies for coal-fired power plants are insufficient and limited. Comprehensive projection study in this area contributes to the studies in the literature.

Modelling of automated steam coal transportation and enrichment systems for efficient operation and cost reduction of thermal power plants

This paper investigates the efficiency of fuel enrichment to reduce the costs of thermal power plants (TPPs). An objective function is formulated to define and measure the desired results. The annual costs of TPPs and additional costs associated with the use of highly abrasive coal are analyzed. The costs of enrichment, in particular, flotation enrichment, are considered. A cost analysis and a transportation problem are presented to demonstrate the results. In general, this paper provides insight into the financial implications of fuel enrichment strategies for thermal power plants.

Effect of Flexible Operation on Residual Life of High-Temperature Components of Power Plants

Electricity generation from renewable energy sources is emerging as a result of global carbon emission reduction policies. However, most renewable energy sources are non-dispatchable and cannot be adjusted to meet the fluctuating electricity demands of society. A flexible operation process has been proposed as an effective solution to compensate for the unstable nature of renewable energy sources. Thermal load fluctuations during flexible operation may cause creep–fatigue damage to the high-temperature components of thermal power plants, as they are designed with a focus on creep damage under a constant power level. This study investigated the residual life of high-temperature components, such as a superheater tube and a reheater header, to failure under flexible operation conditions using finite element analysis and empirical models. First, we determined an analytical solution for the straightened superheater tube under thermal conditions and compared it with the numerical solution to verify the numerical models. Through the verified finite element model, the creep–fatigue life of the reheater header was estimated by considering flexible operation factors and employing the Coffin–Manson and Larson–Miller models. Although fatigue damage increases with decreasing minimum load and ramp rate, we confirmed that creep damage significantly affects the residual life during flexible operation. In addition, a surrogate model was proposed to evaluate the residual life of the reheater as a function of the flexible operation factors using the machine learning methodology, based on the results of finite element methods. It can be used to predict its residual life without performing complex thermo-structural analysis and relying on empirical models for fatigue and creep life. We expect our findings to contribute to the efficient operation of thermal power plants by optimizing the flexible operation factors.

Energy-Efficient Solutions in Design, Construction and Operation of Thermal Power Plants and Heating Networks

The article deals with topical issues related to the introduction of energy-efficient measures in the energy sector of Russia. A comprehensive study and research of the current situation in the field of technological processes for generating electric and thermal energy of thermal power plants (hereinafter TPP), transportation and distribution of energy in thermal networks has been carried out. The analysis of the main equipment and the parameters of the working environment influence on the efficiency of the thermal power plant, taking into account the technological features and energy losses of the steam power cycle of heat and electric power generation, was carried out. The main existing problems and sources of energy losses in heat supply systems are considered. Recommendations are given for introduction and development of energy-efficient solutions and technologies in the design, construction and operation of thermal power plants and heating networks. Promising measures aimed at maximum effect of energy saving are proposed for consideration, including the design and construction of new or modernization of existing thermal power plant equipment, the introduction of combined-cycle power plants, the use of frequency drives of critical rotating mechanisms, the introduction of automatic or remote manual process control systems, the introduction of digital production, including digital counterparts of objects, digital heating points and electrical substations, installation of additional sensors and metering devices with the introduction of monitoring systems and predictive prognostics of equipment, the use of geo-information systems with visualization of three-dimensional schemes and the development of mathematical models of heating networks, carrying out a full-scale instrumental control of critical pipelines metal using robotic complexes. Practical examples of energy-efficient measures application at existing thermal power plants and heating networks are given.

Fine Particulate Matter Concentration and Early Deaths Related to Thermal Power Plants and National Industrial Complexes in South Korea

Thermal power plants (TPPs) and national industrial complexes (NICs) are widely known as being among the major causes of changes in the concentrations of fine particulate matter (PM2.5). However, little is known about the changes in PM2.5 concentration caused by the operation of these facilities in South Korea and the health burden attributable to them, including early death. There were two purposes to this study. The first was to quantitatively evaluate the changes in PM2.5 concentration caused by TPPs and NICs in Korea. The second was to estimate the number of early deaths as a health burden attributable to such changes in PM2.5 concentration. The changes in PM2.5 concentration caused by the operation of TPPs and NICs were investigated within TPPs in 2013 and within NICs in 2015. The number of early deaths in 2015 caused by changes in PM2.5 concentration was estimated using the Environmental Benefits Mapping and Analysis Program (BenMAP). Nationwide, the annual average concentration of PM2.5 caused by the operation of TPPs and NICs was estimated to increase by 0.611 μg/m3 and 1.245 μg/m3, respectively, suggesting that NICs contributed about twice as much to this concentration as TPPs. The same trend was also observed regarding the number of early deaths, with TPPs and NICs accounting for 1017 and 2091 early deaths per year, respectively, indicating that the operation of NICs causes a health burden about twice as high as that caused by TPPs. However, the changes in PM2.5 concentration were found to be high near TPPs and NICs, while the health burden caused by exposure to PM2.5 varied according to the level of population distribution and mortality in each air (quality) control zone (ACZ) to which one is exposed. The findings of this study are expected to be utilized as reference data when setting goals to strengthen air quality management (AQM) in each ACZ in Korea.

Flow methods as a general approach to automation of the chemical analysis of aqueous media (review)

The article is devoted to the consideration of general approaches to automating the analysis of aqueous media, which are the main objects of chemical analysis including natural and waste waters, as well as technological media in various industries (microelectronics, biochemical industries, nuclear and thermal power engineering), which are the main consumers of high-purity water used for pre-start flushing of inline equipment to the required cleanliness of surfaces, for preparation of coolants that ensure the operation of nuclear and thermal power plants. In all these cases, the content of impurities in used or spent and intended for discharge aqueous media is strictly regulated. Changes in the content of impurities in controlled media often occur spontaneously due to equipment failure on the controlled objects. Prompt response to such changes and their timely elimination can be performed more efficiently if chemical and technological control of the normalized parameters of aqueous media of any named origin and destination is carried out in a continuous automatic, on-line, mode, which guarantees the exclusion of gaps or delays in obtaining information about equipment failure on a controlled facility in case of technological control or about unauthorized discharges of pollutants in case of environmental control. Possible methodological approaches to the development of systems for continuous chemical monitoring of quality or levels of contamination of aqueous media are considered on the basis of the above prerequisites, and applicability of various flow methods for these purposes is discussed in the order of their appearance in the arsenal of analytical chemists.

INFLUENCE OF PRESSURE IN THE TURBINE CONDENSER ON HEAT SUPPLY EFFICIENCY OF NPP WITH HEAT PUMP

The use of a heat pump for heat supply makes it possible to practically stop thermal pollution of the environment during the operation of thermal and nuclear power plants in winter. If a steam turbine condenser is used as a low-potential energy source for heat pump, the amount of released thermal energy will be equal to the sum of the thermal power of the NPP condenser and the power of the heat pump compressors. From the point of view of environmental safety, heat supply by combining power plant with a heat pump is an urgent task. But it is known that the due to the lack of steam extraction for water heating, the additional electrical power of the cogeneration heat and power plant will be less than the capacity of the heat pump compressors. Thus, in terms of thermodynamic efficiency, the use of a heat pump loses to a traditional cogeneration plant. The purpose of the work is to determine the influence of the final pressure in the turbine condenser on the thermodynamic efficiency of a nuclear power plant with a heat pump. A mathematical model of the thermal scheme of the K-1000-5.8/1500 NPP turbo-plant during summer and winter operation with heating plant has been developed. With the heating plant capacity of 230 MW, the electric capacity of NPP unit decreases by 43.5 MW. A mathematical model of a heat pump has been developed, for which a steam turbinecondenser is used as a low-potential energy source. To ensure the release of 230 MW of heat, the power of the heat pump compressor must be 48.4 MW. Thus, if the heating plant is replaced with a heat pump of the same capacity, the electric power will decrease by 4.8 MW. Calculations were made regarding the influence of the final pressure in the condenser on the exergetic efficiency of the NPP with heat pump, which uses the entire capacity of the turbine condenser. The analysis of the obtained results showed that the exergetic efficiency due to the increase in electric power released in winter increases with the increase of the final pressure in the condenser. This is explained by an increase in the heat pump coefficient of performance.

Prospect for the use of the solar updraft tower project for the generation of electrical energy in the republic of Uzbekistan

Fulfilling the decision of the Paris Agreement on Climate Change (COP-21 of the UNFCCC) dated December 12, 2015, the government of the Republic of Uzbekistan has developed and adopted an energy development plan of the Republic for 2020-2030. The plan provides for the construction of 3 GW of wind and 5 GW of solar power plants annually. RES will generate electrical energy in parallel with the generation of energy by thermal stations and transfer it to the general energy system. The main disadvantage of the joint operation of RES and thermal power plants is the need to have standby generating capacity due to the fact that the sources of solar and wind energy are fickle by nature. System costs rise with the increasing share of renewable energy sources. The Solar Updraft Tower project is a renewable energy option that does not have the main disadvantage of other types of renewable energy sources - the variability of electricity production and therefore is more acceptable for operating conditions in a single energy system. The article discusses and evaluates the Solar Updraft Tower (SUT) project for the generation of electrical energy, taking into account the conditions of Uzbekistan.

Design, commissioning and operation of a mini hybrid parabolic trough solar thermal power plant for direct steam generation

Parabolic Trough Collectors (PTCs) are the most mature, reliable and widespread among Concentrated Solar Power (CSP) technologies for electricity generation. The conventional power plants relying on PTCs use synthetic oil as Heat Transfer Fluid (HTF) which has limited life span, has limited operation temperature, is expensive and harmful to the environment. In the present research work, a new perspective has been developed to directly generate steam in the collectors, eliminating the need for HTF in the solar field and avoiding auxiliary heat exchangers. A mini hybrid Direct Steam Generation PTC power plant having a boiler as a backup that can be operated with biogas or natural gas is installed at Ecole Nationale d'Ingénieurs de Tunis (ENIT) within the framework of REELCOOP project (Renewable ELectricity COOPeration). The description, commissioning and operation of the solar plant are presented in this paper. The plant is designed and tested under real-life operating conditions in the south Mediterranean region. The feasibility of the DSG process in horizontal parabolic trough collectors has been confirmed and an important know how has been acquired regarding the operation of DSG solar plant. The main instructions for the operation of the solar plant have been presented including start-up and shutdown procedures of the plant, as well as the safety measures to be considered.The development of this plant is aimed to address the challenge of coupling intermittent solar radiation and the presence of a two-phase fluid in the absorber tubes. An important know how has been acquired regarding the operation of DSG solar plants in solar only mode and in hybrid mode which allowed to balance strengths and weaknesses of solar and biogas/natural gas technologies. By combining both systems, we have tackled the problem of the controllability of the energy supply while exploiting as much as possible renewable sources.