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Fly ash waste is a by-product of coal burning at PLTU Nagan Raya, Aceh Province, Indonesia. Since 2017, the coal used is a mixture of 90% Kalimantan coal (sub-bituminous) and 10% local Nagan Raya coal (lignite) which is still young so that the mineral ash content is still high. Silica is among the interesting minerals to be extracted from fly ash, given its wide range of benefits. This paper describes the process of extracting silica from fly ash at the Aceh power plant through the leaching method using a chemical solution and heating for 2 and 4 hours at a temperature of 100°C. The difference in heat treatment aimed to study the changes in properties and obtain the best method in the silica extraction process. The effect of heat treatment on silica characteristics was studied based on X Ray Diffraction (XRD) test for phase identification, Scanning Electron Microscopy (SEM) test for morphological identification, Energy Dispersive X-Ray Spectroscopy (EDS) test for mineralogy element identification, Fourier Transform Infra-Red (FTIR) test for identification of functional groups and surface chemistry, and differential calorimetric analysis/thermogravimetric (DSC/TGA) test for identification of thermal properties. As a result, it was found that fly ash still contains unburned carbon, which significantly affects its color, and has the potential for application as a hydrogen storage material because its pore diameter structure is larger than 0.7 nm. The silica extracted from fly ash is capable of achieving a purity of up to 87% and exhibits excellent thermal stability, especially at temperatures between 120-300 °C; thus, it has the potential to be a catalyst material in the adsorption-desorption reaction of hydrogen by magnesium, although further research is still needed. [ABSTRACT FROM AUTHOR]

Chemical composition, surface morphology characteristics, and mineralogical characteristics of feed coals from six power plants were studied in this paper, as well as alteration behavior of mineral phase, functional groups, and trace elements during combustion. The apparent morphology of feed coals is different in compactness and order, while sharing a similar lamellar shape. Quartz, kaolinite, calcite, and illite are the main minerals in feed coals. There are obvious differences in the calorific value and temperature range in volatiles stages or coke combustion stages for feed coals. Peak positions for the main functional groups in feed coals are similar. After burning at 800 ℃, most organic functional groups in feed coals were lost in products, but the group of -CH2 on the side chain skeleton of n-alkane and the aromatic hydrocarbon bond (Ar–H) still existed in the ash, and the vibration of Si–O-Si bond and Al–OH bond in inorganic functional groups was strengthened. During combustion, Pb and Cr in feed coals will be accumulated in the mineral residues, unburned carbon, and residual ferromanganese minerals, along with the loss of organic matter and sulfide or the decomposition of carbonate. Pb and Cr are more easily adsorbed by the fine-graded coal combustion products. Occasionally, the abnormal phenomenon occurred in a medium-graded ash but with the maximum adsorption of Pb and Cr, which is mainly caused by the collision and agglomeration of the combustion products, or the adsorption capacity of different mineral components. The effects of diameter, coal species and feed coal on the forms of Pb and Cr in combustion products were also analyzed in this study. The study has some guiding significance for understanding the behavior track and alteration mechanism of Pb and Cr during coal combustion. [ABSTRACT FROM AUTHOR]

With continuous improvements in integration, totalization and automation, remaining useful life predictions of mechanical equipment have become a key feature of technology and core element of equipment prediction and health management. The traditional method based on degradation mechanisms is not fully capable of predicting remaining useful life, especially for special power plants that use industrial transmissions, barrel launchers, etc. The expected service requirements are higher for condition monitoring and remaining service life prediction. The effective prediction of the remaining useful life of such special power plants is a major challenge and technical bottleneck in the industrial field and national defense equipment construction. This paper analyzes and expands on the research on the remaining life prediction methods for special power plants and analyzes the remaining life prediction methods of existing dynamic models, as well as data-driven and data–model fusion drives, and specific ideas for future research and development in four aspects, including remaining useful life prediction tests supplemented with soft measurements. Additionally, future research directions for the remaining life prediction of special power plants are provided. [ABSTRACT FROM AUTHOR]

In this paper, the modified artificial bee colony optimization algorithm, in which the accept–reject method is used as a part of the solution process in order to limit the random search space, is proposed for solving the optimization problems. The accept–reject method can find points of desirable quality and high accuracy with the help of probabilistic functions and limited the random search space, which increases the speed of the algorithm for the next steps and also reduces the number of iterations of the artificial bee algorithm. Then, the next phases of the bee algorithm will be executed in the interval determined by the accept–reject method. One of the most important issues in intelligent algorithms, especially the bee algorithm, is that in problems with several local optimal points, sometimes the algorithm gets stuck in the trap of local optimal points and does not reach the global optimal points. By using the motion step determination parameter in the employed bee phase, the algorithm can be guided to reach the global optimal points while correctly adjusting the movement of the bees for searching in random food sources, which will help improving the problem-solving process. This algorithm is tested by the basic benchmark functions as well as the benchmark functions of CEC 2005 and CEC2017 and CEC2019 and an engineering problem related to the planning of a virtual power plant. The results show that the proposed algorithm is superior in comparison to other algorithms. [ABSTRACT FROM AUTHOR]

Owing to the complicated environments, the service life of bag-filter or electrostatic-bag composite precipitators with polyphenylene sulfide (PPS) is greatly deviated from the ideal time. In this paper, the structural transformation of PPS-based bag filter materials collected from the coal-fired power plants with different loading units were investigated systematically. As the SO2 content increases, the surface evolution of PPS fibers from smoothness to crack occurs. An opposite trend is observed for melting point and cross breaking strength. The major reason for the failure of PPS-based bag filters is that working temperature (T) often passes through acid dew gas point (Ta), and the SO3 would be produced during the condensing of H2SO4 when T is lower than Ta. The SO3 with strong oxidation would attack the weak C-S bonds of PPS, resulting in the oxidation or even sulfonation of PPS-based bag filters. This work discloses the actual structural evolution of PPS and some corresponding rules under the complicated corrosive gases with high temperatures, which provides a guidance for prolonging the service life of PPS-based bag filters during the usage of coal-fired power plants. [ABSTRACT FROM AUTHOR]

The emission reduction of global greenhouse gases is one of the key steps towards sustainable development. Demand response utilizes the resources of the demand side as an alternative of power supply which is very important for the power network balance, and the virtual power plant (VPP) could overcome barriers to participate in the electricity market. In this paper, the optimal scheduling of a VPP with a flexibility margin considering demand response and uncertainties is proposed. Compared with a conventional power plant, the cost models of VPPs considering the impact of uncertainty and the operation constraints considering demand response and flexibility margin characteristics are constructed. The orderly charging and discharging strategy for electric vehicles considering user demands and interests is introduced in the demand response. The research results show that the method can reduce the charging cost for users participating in reverse power supply using a VPP. The optimizing strategy could prevent overload, complete load transfer, and realize peak shifting and valley filling, solving the problems of the new peak caused by disorderly power utilization. [ABSTRACT FROM AUTHOR]

Large-scale photovoltaic power plants located in highland mountainous areas are vulnerable to landslides due to extreme rainfall, posing a significant threat to the normal operation of photovoltaic power plants. However, limited research has been conducted on landslide risk assessment specifically tailored to large photovoltaic power plants, with most studies focusing on static assessments that lack long-term sustainability in risk assessment and prediction. In this paper, a dynamic study on landslide risk at a large photovoltaic power plant project under extreme rainfall conditions is conducted. Firstly, the factors in landslide susceptibility assessment based on typical landslide characteristics in the study area are selected and an assessment index database using mapping units to extract the relevant factors is established. Subsequently, the ANP-FBN model is employed to evaluate the landslide susceptibility of large photovoltaic power plant sites. Furthermore, an assessment index system for landslide hazard vulnerability is developed by considering population, economic, and material vulnerabilities, and the AHP method is adapted to assess landslides vulnerability in the study area. Finally, the landslide rainfall threshold with the susceptibility and vulnerability assessment results are coupled to achieve a dynamic assessment of landslide hazard risk at large photovoltaic power plant sites under extreme rainfall conditions. The findings highlight that the central valley and the eastern steep slope of the study area are the primary "high" and "very high" risk areas. Moreover, with the increase in rainfall duration, the risk level of landslide hazards in the study area also rises. [ABSTRACT FROM AUTHOR]

Multi-energy virtual power plant (MEVPP) has attracted more and more attention due to its advantages in renewable energy consumption and carbon emission reduction. However, the characteristics of multi-energy coupling and the access of renewable energy may lead to some challenges in the operation of MEVPP. In this paper, a data-driven distributionally robust chance constraints optimization model (DD-DRCCO) is proposed for the dispatching of MEVPP. Firstly, the uncertainties of wind power and photovoltaic output forecasting errors are modeled as an ambiguity set based on the Wasserstein metric. Secondly, combined with the chance constraint, the expected probability of the inequality constraint with uncertain variables is limited to the lowest allowable confidence level to improve the reliability of the model. Thirdly, the forecast errors of wind power and photovoltaic are considered in the constraint conditions, so that the system can effectively resist the interference of uncertain output. Besides, based on the strong duality theory, the DD-DRCCO model is equivalent to a MILP problem which is easy to solve. Finally, simulations implemented on a typical MEVPP are delivered to show that our proposed model: 1) The model is data-driven, and the conservativeness is kept at a low level, and the solution time is about 7s~8s; 2) The MEVPP system can achieve a balance between economy and low-carbon, making the total operation cost reduced by 0.89% compared with no increase of electric boiler; 3) The CO2 emission during the operation of the MEVPP system was significantly reduced by about 87.33 kg. [ABSTRACT FROM AUTHOR]

In a thermal plant, the combustion system of the coal-fired boiler is a nonlinear time-varying system, which leads to undesired responses, if traditional proportional-integral-derivative controllers are utilized. Internal process delay is an important characteristic of the steam pressure in the boiler of coal-fired power plants, which affects the closed-loop dynamics. To compensate for this significant delay and reach the desired performance, a novel control strategy based on a combination of an optimal fractional-order proportional-integral-derivative (OFOPID) controller with a Smith predictor (SP) structure is suggested in this paper that achieves the desired control performance required for the optimal operation of the boiler. The simulation results of a coal-fired power plant boiler with the power of 300 MW show that the performance is improved considerably by having lower overshoot and lower rise and settling times, as well as a lower mean square error during the operation of the power plant Boiler. [ABSTRACT FROM AUTHOR]

Coal‐fired thermal power must be flexible to enable the grid absorption of inconsistent photovoltaic (PV) and wind power. Combined heat and power (CHP) coal‐fired plants are the primary source for district heating systems. This paper uses a 330 MW subcritical CHP unit as an example to carry out the study. With the promotion of building energy efficiency, when the thermal index is reduced to below 20 W/m2, the low‐load operation of CHP can meet the wind power and PV feed‐in demand and guarantee residential heating without the need for flexibility modification. Meanwhile, more renewable energy generation can reduce carbon emissions from the power supply, further contributing to reducing carbon emissions from buildings. The impacts of different envelope parameters and supplementary heat sources on building carbon emissions are also studied. The conclusion shows that the degree of their impact on carbon emissions ranks as ESMs (energy supply modes) > Factor D (infiltration N50) > Factor A (external wall heat transfer coefficient) > Factor C (window heat transfer coefficient) > Factor B (roof heat transfer coefficient). When the building's heating energy consumption gradually decreases, the distributed heat pump unit can replace the coal‐fired boiler to supply the peak heat load demand. In the future, China's district heating systems can be gradually changed from the current CHP and coal‐fired boilers to CHP and distributed heat pumps. [ABSTRACT FROM AUTHOR]

Ca-looping is an effective way to capture CO2 from coal-fired power plants. However, there are still issues that require further study. One of these issues is the effect of steam on the Ca-looping process. In this paper, a self-madethermogravimetric analyzer that can achieve rapid heating and cooling is used to measure the change of sample weight under constant temperature conditions. The parameters of the Ca-looping are studied in detail, including the addition of water vapor alone in the calcination or carbonation stage and the calcination/carbonation reaction temperatures for both calcination and carbonation stages with water vapor. Steam has a positive overall effect on CO2 capture in the Ca-looping process. When steam is present in both calcination and carbonation processes, it increases the decomposition rate of CaCO3 and enhances the subsequent carbonation conversion of CaO. However, when steam was present only in the calcination process, there was lower CaO carbonation conversion in the following carbonation process. In contrast, when steam was present in the carbonation stage, CO2 capture was improved. Sample characterizations after the reaction showed that although water vapor had a negative effect on the pore structure, adding water vapor increased the diffusion coefficient of CO2 and the carbonation conversion rate of CaO. [ABSTRACT FROM AUTHOR]

Carbon dioxide capture and utilization (CCU) technology is a significant means by which China can achieve its ambitious carbon neutrality goal. It is necessary to explore the behavioral strategies of relevant companies in adopting CCU technology. In this paper, an evolutionary game model is established in order to analyze the interaction process and evolution direction of local governments and coal-fired power plants. We develop a replicator dynamic system and analyze the stability of the system under different conditions. Based on numerical simulation, we analyze the impact of key parameters on the strategies of stakeholders. The simulation results show that the unit prices of hydrogen and carbon dioxide derivatives have the most significant impact: when the unit price of hydrogen decreases to 15.9 RMB/kg or the unit price of carbon dioxide derivatives increases to 3.4 RMB/kg, the evolutionary stabilization strategy of the system changes and power plants shift to adopt CCU technology. The results of this paper suggest that local governments should provide relevant support policies and incentives for CCU technology deployment, as well as focusing on the synergistic development of CCU technology and renewable energy hydrogen production technology. [ABSTRACT FROM AUTHOR]

Today, the expansion of power sources is the main task to meet the development of demand. Therefore, Da Nang City has been approved to build the Khanh Son waste incineration power plant in the near future. The Khanh Son power plant project not only helps to reduce a large amount of waste in the area but also provides electricity supply directly to the city, increasing the budget for that locality. However, the connection of this power plant to the system will modify the operating parameters of the grid which may cause some negative impact on the regional power system. Therefore, the main aim of this paper is to simulate various operation modes of the system such as steady-state mode, short circuits, and transient to evaluate the impact of the connection of the new power plant on the national power. The result shows that the Khanh Son power plant helps to reduce the overload of the main cable during the high load scenario, the stability of the system is enhanced significantly. Based on the simulation results, some recommendations to ensure the stabilizing of the grid have been proposed as well. [ABSTRACT FROM AUTHOR]

Coal mills consume a huge amount of station service electricity power of a coal-fired power plant. Meanwhile, the operation of coal mills also has a large influence on boiler combustion. Among all the operating factors, the electricity current intensity of coal mills reflects the electricity power consumption as well as operating status of coal mills. If the electricity current intensity of coal mills can be predicted by giving a set of operation parameters, the operating status can be adjusted accordingly. The electricity current intensity of coal mills can be reduced or minimized subject to the coal type parameters and the load of the boiler through optimizing the coal mill operations. This paper builds a model to predict the electricity current intensity of coal mills using a Support Vector Machine based on a set of practical sensing data. Via optimizing the hyperparameters of the model, a reasonable prediction ability is achieved. Under a given production running condition, the electricity current intensity of the coal mill decreases from 47.9 AM to 46.5 AM, which is a remarkable achievement for the coal mill running process. This method may provide a feasible online solution for coal mill optimization. [ABSTRACT FROM AUTHOR]

Accurate models of power plants play an important role in maintaining the reliable and secure grid operations. In this paper, we propose a synchrophasor measurement-based generator parameter calibration method by a novel deep learning method with high computational efficiency. An elementary effects-based approach is developed to identify the critical parameters from a nonlinear system with much better performance than the widely used trajectory sensitivity-based method. Then, synchrophasor measurement-based conditional variational autoencoder is developed to estimate the parameters’ posterior distributions even in the presence of a high-dimensional case with eighteen critical parameters to be calibrated. The effectiveness of the proposed method is validated for a hydro generator with a very detailed model. The results show that the proposed approach can accurately and efficiently estimate the generator parameters’ posterior distributions even when the parameters true values are not in support of the prior distribution. [ABSTRACT FROM AUTHOR]

To effectively utilize ventilation air methane (VAM), it is proposed to pass it into the boiler of the coal‐fired power plant for mixed combustion. However, the different types of thermal coal utilized present distinct characteristics when mixed with VAM. In this paper, lignite, bituminous coal, and anthracite are selected to study the CH4 conversion rate, system ignition temperature, and NO emission characteristics of the VAM‐pulverized coal coupled system on a fluidized bed experimental platform. The experimental results show that the ignition temperatures of VAM are 748, 736, and 732 °C when the CH4 concentration is 0.25, 0.5, and 0.75%. After the addition of thermal coal, the ignition temperature decreased significantly. When the CH4 concentration is 0.25%, the ignition temperature of the lignite‐VAM system is the lowest, which is 450 °C. Anthracite has the strongest catalytic effect on CH4 combustion. When the heating rate is 5 °C /min, the reaction rate of CH4 is the fastest in the anthracite‐VAM coupled system. Under laboratory conditions, the peak NO concentration in the coal‐VAM coupled system was lignite > bituminous coal > anthracite at different CH4 concentrations, and the CH4 in VAM had a reducing action on the NO generated during mixed combustion, with a stronger reducing effect observed as the CH4 concentration increased. The results of this study can lay the foundation for the industrial application of the mixed combustion of VAM and thermal coal, and be of great significance for solving the practical problems caused by the change of boiler coal types. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

This paper examines the health tradeoffs associated with the historical expansion in coal-fired electricity generation in the United States. We combine newly digitized data on all major coal-fired power plants for the period 1938–1962 with two complementary difference-in-differences strategies. Coal-fired plants imposed large negative health externalities that were partially offset by the benefits of local electricity generation. The health impacts varied widely according to initial electricity access and evolved as the stock of generating capacity expanded over the sample period. These findings highlight the importance of accounting for both current and future payoffs when designing environmental regulation. [ABSTRACT FROM AUTHOR]

This work investigates the decarbonization potential of large-scale implementation of BECCS (in the form of biomass co-firing and post-combustion amine-based CO2 capture) in over 150 existing coal-fired power plants in China, combining GIS-based geospatial analysis of biomass availability from agricultural residues and modelling of the techno-environmental performance of the retrofitted power plants. Using a 500-m resolution map of cropland in China, the availability of residual biomass at a radius of 25–100 km from each power plant is estimated. The biomass yield is then matched with the required input for a set of co-firing scenarios, identified by the optimal mix of different co-firing ratios (10%, 25%, and 40%) and increasing % of total plant's capacity to be retrofitted with the chosen BECCS system. Power generation performance and required biomass for the retrofitted plants are modelled in the Integrated Environmental Control Model (IECM). According to the results, the total decarbonization potential of the modelled large-scale implementation of BECCS ranges from 0.3 to 1.8 Gt CO2/yr (15–81% of BAU emissions), depending on the biomass collection radius. The Chinese provinces of Shandong, Jiangsu, Anhui, and Henan have the most potential for BECCS implementation, while coal-rich regions (e.g. Inner Mongolia) or highly developed coastal areas (Guangdong, Zhejiang) are constrained by local biomass availability. Overall, this work demonstrates the significant potential of the sustainable large-scale implementation of BECCS in China and provides suggestions to policymakers to include this technology in the portfolio of solutions towards carbon neutrality. [ABSTRACT FROM AUTHOR]

This paper follows a practical approach to evaluate particulate matter emissions from biomass-fuelled power plants and analysis measurement uncertainties. Sixty-seven measurement reports from 11 biomass power plants, all equipped with fabric filters as dust control device, were analysed. Particulate matter emission measurements by gravimetrical standard reference method were chosen to provide the most reliable values to investigate the influence of bag filter parameters, such as media age or bag filter length. 92.1% of total dust emission measurements were below lower BAT-associated emission levels (BAT-AELs) for waste incineration. Data also showed that bag filter media older than 6 years can still secure very low dust emission levels. This work also gives a summary of findings and problems with uncertainty of automated measuring systems for dust emissions in biomass combustion applications in practice and quality assurance level one (QAL1) process related to very low emission levels such as lower best available techniques reference document (BREF) values. Practical examples on issues of continuous dust emission monitoring devices are also given. [ABSTRACT FROM AUTHOR]

Electrostatic precipitator (ESP) is the main equipment for flue dust control of coal‐fired power plants in China, accounting for about 70% of the total currently. In this paper, energy efficiency data of ESP, including 202 sets before ultra‐low emission and 45 sets after ultra‐low emission are systematically studied and analyzed by using the research method of field testing and technical investigation. The results showed that after ultra‐low emission, the energy consumption and converted CO2 emission of ESP in coal‐fired power plants increased significantly, and the specific power consumption and energy consumption corresponding to unit mass particulate matter (PM) removal increased by 49.61% and 139%, respectively, and the converted CO2 emission increased by 1.67 × 10−4 kg CO2/m3 and 31.12 kg CO2/t PM on average. The energy consumption of low‐low‐temperature ESP (LLT‐ESP) was positively correlated with its emission reduction range. Before and after the gas cooler operation, the power consumption, specific power consumption and energy consumption corresponding to unit mass PM removal increased by 8.06%–38.68%, 10.66%–60.14% and 7.23%–62.98%, respectively, and the CO2 emissions corresponded increased by 26.29–691.81 kg CO2/h, 0.46–2.18×10−4 kg CO2/m3, 1.10–23.62 kg CO2/t PM, respectively. LLT‐ESP had a great possibility to optimize the operation for energy‐saving and carbon‐reduction, because when the high voltage power supply operated on the maximum output mode and the energy‐saving mode, the drop of power consumption and specific power consumption was around 52.00%–58.23%, 52.02%–58.29%, respectively, and the CO2 emission reductions corresponded was 1,039.25–1,359.35 kg CO2/h, 2.71–3.58×10−4 kg CO2/m3, respectively. LLT‐ESP also had the great optimizing possibility for energy‐saving and carbon‐reduction during low load operation, as when the load reduced from 100% to 50%, the specific power consumption and energy consumption corresponding to unit mass PM removal increased by 5.05%–45.50%, 6.59%–63.90%, respectively, and the CO2 emissions corresponded increased by 0.38–2.44×10−4 kg CO2/m3, 6.76–45.98 kg CO2/h, respectively. The operation energy consumption can be effectively reduced by integrated use of multiple electric dust removal technologies, such as compared with LLT‐ESP technology, the power consumption, specific power consumption and energy consumption corresponding to unit mass PM removal of "low‐low‐temperature + moving electrode+ electrostatic agglomeration" decreased by 37.88%, 30.08% and 45.29% respectively, and the corresponding CO2 emission decreased by 697.22 kg CO2/h, 1.87×10−4 kg CO2/m3 and 32.98 kg CO2/t PM, respectively. The current national standard GB 37484‐2019 is no longer applicable to the energy efficiency evaluation of the ESP in ultra‐low emission units. This study can provide data support for the revision of national standard GB 37484‐2019 and the collaborative efficiency of coal power plant pollution reduction and carbon reduction. © 2023 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

The development of new energy vehicles has become an important means by which China can continue to grow as a major automobile manufacturing powerhouse while joining the worldwide effort to tackle climate change. This paper uses Chinese‐listed new energy vehicle companies during 2015–2019 as the research sample and examines the impact of government subsidies on enterprise innovation, with the technical background of CEOs as an important moderating factor. We also analyze the extent of this moderating role within different institutional environments and corporate ownership structures. The results show that government subsidies can encourage new energy vehicle enterprises to increase innovation investment, and CEOs' technical backgrounds can strengthen this relationship. Compared with regions with better institutional environments, the moderating effect of CEOs' technical backgrounds is more obvious in regions with poor institutional environments, and when compared with state‐owned enterprises, the effect is more obvious in the private sector. We propose a list of government and internal enterprise policies that would make use of the insights gained from our research results. [ABSTRACT FROM AUTHOR]

Within the XFLEX HYDRO project, the possibility of increasing the flexibility of hydro power plants to support the Electric Power System (EPS) is investigated. The flexibility of the pumped-storage power plant Frades 2, as the target, should increase by extending the operating range for each unit and by using the hydraulic short circuit (HSC) operation mode. Transient investigations of the additional plant conditions are performed to ensure the safety of the plant. With a 1D model of the entire hydro power plant including both pump-turbines, valves, surge tanks, and the water-bearing components, extensive calculations are carried out to verify the safety of the existing plant for extended operation conditions. In particular, the study focuses on the synchronous and asynchronous emergency shutdowns of the plant in the new operating conditions as well as other operation-related power plant transients regarding the HSC mode. With the results presented in this paper, the flexibility of the plant Frades 2 can be increased. Delayed emergency shutdowns are identified as particularly critical during the study and should always be given additional consideration in transient investigations. [ABSTRACT FROM AUTHOR]

Copyright of Journal of South China University of Technology (Natural Science Edition) is the property of South China University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this study, a coal-fired power plant with an integrated S-CO2 cycle is proposed to improve the system operational flexibility. To optimize the performance, a control strategy of variable load regulation is proposed. First, a dynamic mathematical model of the system is established based on the conservation of mass and energy principles, and then, dynamic verification of the model is carried out. In order to evaluate the performance of the proposed system, an exergy analysis is performed on the S-CO2 cycle, indicating that the exergy loss rate of the heater in the cycle is the highest. Finally, the dynamic performance of the system is simulated, and the dynamic response of the power generation load is analyzed. In addition, the system is evaluated based on the performance indicator of the flexibility of the power generation. It was found that the proposed system in this paper has a large load ramp rate which can quickly follow the load response. Meanwhile, compared with load downregulation, the system has greater potential for load upregulation. [ABSTRACT FROM AUTHOR]

Circulating fluidized bed (CFB) boilers with wet flue gas desulfurization (WFGD) system is a popular technology for SO2 removal in the coal-fired thermal power plant. However, the long response time of continues emission monitoring system (CEMS) and the hardness of continuously monitoring the coal properties leads to the difficulties for controlling WFGD. It is important to build a model that is adaptable to the fluctuation of load and coal properties, which can obtain the SO2 concentration ahead CEMS, without relying on coal properties. In this paper, a prediction model of inlet SO2 concentration of WFGD considering the delay between the features and target based on long-short term memory (LSTM) network with auto regression feature is established. The SO2 concentration can be obtained 90 s earlier than CEMS. The model shows good adaptability to the fluctuation of SO2 concentration and coal properties. The root-mean-squared error (RMSE) and R squared (R2) of the model are 30.11 mg/m3 and 0.986, respectively. Meanwhile, a real-time prediction system is built on the 220 t/h unit. A field test for long-term operation has been conducted. The prediction system is able to continuously and accurately predict the inlet SO2 concentration of the WFGD, which can provide the operators with an accurate reference for the control of WFGD. [ABSTRACT FROM AUTHOR]

Marginal abatement cost (MAC) plays an essential role in pricing pollutants and guiding environmental policies. Considering the heavy polluting nature of China's coal power industry, this paper aims at providing companies and policymakers with more comprehensive information on the cost of abatement by estimating the MACs of CO2 and SO2 for coal-fired power plants (CFPPs) in China. This study contributes to the literature by considering an interconnected two-stage production system to investigate. The estimation framework is advanced in combining the electricity production and pollution abatement process of CFPPs into a convex quantile regression (CQR) model. The results show that the averages of MAC for CO2 and SO2 are estimated to be 367.56 Yuan/ton and 662.30 Yuan/ton, respectively, indicating that the reduction of such emissions is still costly. The heterogeneous analysis then indicates that large CFPPs, central-government-owned power plants (CGOPPs), and low-regulated CFPPs tend to possess lower MACs for CO2. Regarding SO2, large and medium-sized power plants show significantly larger MACs than small plants. In addition, the MACs of SO2 for CGOPPs and high-regulated CFPPs are more concentrated at high levels. In the second part, the Tobit regression analysis was used to discuss the determinants of MACs for CO2 and SO2. Factors like carbon emission intensity, load, and operating hours can notably decrease MACs for CO2, while MACs for SO2 tend to be positively affected by the total abatement cost and the abatement rate of the FGD equipment. In addition, the MACs for the large CFPPs, CGOPPs, and high-regulated CFPPs are more likely to be affected by the selected influence factors. Based on these results, we conclude with some policy recommendations. [ABSTRACT FROM AUTHOR]

Copyright of Power Generation Technology is the property of Power Generation Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Considerable efforts are made in order to reduce the power sector's carbon footprint. Paired with a realization that thermal power plants are likely to play a significant role during the transitional period towards a 100% sustainable energy system, carbon capture and storage (CCS) retrofit is becoming a growingly important consideration for a number of power plant operators. This paper analyzes the possibility of retrofitting a coal-fired power plant based in Croatia. A techno-economic model of the proposed unit is built setting up key elements of the technological solution and determining their capital and operational costs. Both a sensitivity analysis and a market analysis are conducted in order to best evaluate the feasibility of the CCS retrofit project. Particularities of South East Europe power sectors are considered utilizing an optimization software. Special consideration is given to the influence of the EU emission trading scheme (ETS) on CCS projects. Further research focuses on the main factors influencing the potential implementation of CCS. Key recommendations that might aid CCS deployment are outlined signaling stronger government support, stable regulatory framework, and market incentives as crucial factors able to foster CCS development. Considering the project in the study, analyses showed that, although technically feasible, CCS retrofit is currently not a financially viable option. Without a stable regulatory framework able to guarantee an adequate supporting scheme, the project is not market competitive. It is important to note that the economic gap of CCS retrofit has been considerably reduced during the past years. [ABSTRACT FROM AUTHOR]

In this review paper, we have tried to highlight the tribological effects that occur in different power plants during power generation. Although papers related to tribological effects on all power plants were not found. Among the papers that have been found, the tribological effect on wind turbine power plants has been observed more. The main wear items are the turbine, bearings, generator, gearbox, pitch systems, yaw systems, blades, and brakes. Appropriate lubrication choice and helical gears can reduce the three-body wear experienced by the gearbox. Tribological design in terms of nuclear power plants can help to generate reliable energy from nuclear power reactors. Some components of the reactor can be lubricated by newly invented materials. Corrosion in coal-fired thermal power plants can lead to great damage and significantly shorten the life of several parts. Vibration in a gas turbine power plant is the main cause of surface wear and vibration reduction can produce efficient energy. Surface erosion of turbines has a significant impact on hydroelectric power generation. These erosions are due to corrosion by solid elements, which is due to the large sediment concentration used to make the turbine and the low hardness of the material. [ABSTRACT FROM AUTHOR]

The main focus of this paper is to address issues related with the impact of the small and medium size hydro power plants connected to the distribution network in Albania, respectively, to 35, 20, 10 and 6 kV distribution network. Considering the significant positive impact in generation they have had also an impact on the distribution system as far as the technical and financial aspects of the distribution network are concerned. The results of the analysis performed indicates that the Middle and South-East areas have been impacted from the deployment of hydro power plants in these area due to the increased power injected from these hydro power plants. Referring to the topology of the network, load demand, constrains and amortization of the distribution network, difficulties faced with the maintenance of the feeders and substations in the subject, this situation has created some problems and issues in respect of very high levels of the voltage in the substations during the minimum load consumption, overloaded of the distribution network as well as frequent outages of lines and feeders in some areas. The analyse performed supports the necessity of reinforcement of the network and the need of clear and strict rules to be followed in respect of connection point of hydro power plants into the distribution network, in order to guarantee a reliable and secured operation of the network and to contribute to the improvement of the performance indicators of the distribution network. [ABSTRACT FROM AUTHOR]

The air pollution situation in the northern part of China has become a threat to the current status of China's energy consumption. This has created pressure to relocate coal plants to the western section of the country. We apply a spatial panel data method to empirically examine the relationship between fine particulate matter (PM2.5) concentration, precipitation and wind speed by using the sample data of 50 cities over 11 months. Based on the empirical parameters, the paper simulates the potential impacts of the proposed coal plants and the coal plants currently under construction for the PM2.5 concentrations across all cities once these coal plants are operational. The results show that the new capacities will increase PM2.5 concentrations in northwest and northeast China, but at acceptable levels and lower than levels in Beijing, Tianjin, Hebei and Shandong. [ABSTRACT FROM AUTHOR]

Nitrogen oxides (NOx) are one of the air pollutants, mainly from coal‐fired power plants, industrial furnaces, etc. In order to control NOx, reduce the preparation cost of denitration catalyst. Selective catalytic reduction is currently the most effective and mature technology for removing NOx. In this paper, solid waste fly ash was used as catalyst carrier, shear reactor was used to prepare Mn−Ce/FA catalyst, and successfully applied to SCR denitration. The catalyst was characterized by SEM, XRD, FTIR, XPS. The results showed that the catalyst prepared by shearing had more dispersed active components. When the power was 80 W, time was 20 min, rotation speed was 120 r/min, and the molar ratio of Mn−Ce was 1 : 1, the optimal catalyst was prepared. Under these conditions, the catalyst had the best activity and strong stability, the denitration performance was the best, up to 82.6 % within 30 min. The introduction of SO2 still showed high catalytic activity and stability, and the removal rate reduced to 73.21 %. After SO2 was stopped, the removal rate rebounded to 77.89 %. Also, Mn−Ce/FA catalyst had good cyclability and stability in the denitration process. [ABSTRACT FROM AUTHOR]

The shortage of urban water caused by CCS retrofitting over coal-fired power plants has become an emerging issue, especially in China where water resources are scarce. In this study, we quantified the impact of CCS retrofitting on water resources and analyzed the increased water pressures due to CCS retrofits in 234 cities of China. We identified 54 cities with 165 power plants that would face water pressure due to CCS retrofitting for achieving 2 °C targets. The results show that the average water withdrawal and water consumption of power plants in 234 cities would increase by 1.63 times and 1.49 times, respectively, involving 480 million people in China. The ratio of freshwater withdrawal to available water (WTA) and the ratio of freshwater consumption to available water (CTA) at the city-level increased by 0.2 and 0.06 under 2 °C constraints respectively, involving a population of 84 million people. Moreover, CO2-EWR technology does not provide relief from urban water stress. This paper assesses the water demand for carbon capture technologies and provides a basis for siting future large-scale deployment of carbon capture technologies in China. [ABSTRACT FROM AUTHOR]

Carbon Capture, Utilization, and Storage (CCUS) is an important potential technical way for coal power plants to achieve near-zero carbon emissions with the current energy structure in China being dominated by coal. However, CCUS is still at the early demonstration stage, and there are many uncertainties in the business model and policy incentives that the traditional method can no longer handle. At the same time, few studies have analyzed these issues. Taking coal-fired power plants as the research object, we adopt the system dynamics method (SD) to compare the economic feasibility, stability, and CO2 emission reduction effect of the CCUS in the vertical integration model and the CCUS operator model. Furthermore, this paper also studies the effect of different incentive policies on CCUS. Results show the following: (1) Both models are economically viable. From the stability perspective, the CCUS operator model is superior to the vertical integration model. (2) In terms of the effect of individual policies, the government's preference for subsidies to the coal-fired power plant can significantly reduce CO2 emissions. Increasing the additional government subsidy and carbon tax can accelerate the CCUS system into a relatively stable state, but beyond a certain range, the marginal CO2 capture rate, marginal CO2 emission reduction rate, and marginal profit rate of each department will be significantly reduced. The storage enterprise highly depends on the government subsidy. Low government subsidy allocation, low additional government subsidy, and a low carbon tax will lead to continuous negative profits for the storage enterprise, making the CCUS system unsustainable. (3) The impact of combination policies on CCUS is not simply the sum of the effects of individual policies. Each policy has a counteracting or reinforcing effect on the other. [ABSTRACT FROM AUTHOR]

In the present paper, a rigorous analysis of a sub-critical steam power plant (120 MW) with reheating and regenerative configuration is presented, using energy and exergy analysis. The total work output from the power plant is 121.80 MW, which is close to the real value of 120 MW. The calculated energy efficiency of the steam power plant is 34.7%, while its exergy efficiency is 32%. In addition to it, energy analysis introduces the condenser as a major source of heat loss, on other hand, exergy analysis introduces the boiler as a major source of exergy destruction. Further to understand the effect of main steam temperature, reheating temperature and condenser pressure on the power plant, a parametric study is being conducted. [ABSTRACT FROM AUTHOR]

The construction of a new CFPP in Indonesia, which was located next to three existing power plants and utilized an existing discharge channel, faced the problem of insufficient capacity of the existing discharge channel to deliver water to four power plants. The problem occurred not only because of the overcapacity of the cooling water flow proposed by the new CFPP but also because of the small size of the culvert located in the discharge channel. This paper discusses several methods to overcome this problem by enlarging the culvert area or by removing the culvert from the channel and replacing it with a bridge. A hydraulic study was investigated using the HEC-RAS software by utilizing inputs obtained from the existing channel geometry and flow measurement data. It was found that additional culverts on both sides with a size of 2 m x 4 m and 3 m x 1 m could reduce the water level by 1.12 m and 0.39 m, respectively. Meanwhile, removing the culvert provided a significant water level reduction of 1.39 m. Enlarging the culvert was chosen as the solution to the discharge channel capacity issue since removing the culvert would require temporarily closing the channel during construction and stopping the operation of the existing power plant. [ABSTRACT FROM AUTHOR]

This paper investigated the performance of Malaysian power plants from the year 2015 to 2017 using Malmquist Total Factor Productivity (TFP) index, which is based on Data Envelopment Analysis (DEA). This approach offers substantial advantages as compared to other existing methods as it can measure productivity changes over time for a variety of inputs and outputs. Moreover, it comprises two primary components: the technical efficiency change and the technological change indexes that provide clearer insight into the factors that are responsible for shifts in total factor productivity. This study uses a single input, installed generation capacity (MW), and two outputs, average thermal efficiency (%) and average equivalent availability factor (%). These output-input data included ten main power plants: TNB Natural Gas, SESB Natural Gas, SESB Diesel, SEB Natural Gas, SEB Coal, SEB Diesel, IPP Semenanjung Natural Gas, IPP Semenanjung Coal, IPP Sabah Natural Gas, and IPP Sabah Diesel. The results have two significant implications for fossil fuel power plants in Malaysia. First, technological change was the primary factor in boosting the TFP performance of the fossil fuel power plants in Malaysia. Meanwhile, the decline in TFP performance in Malaysian fossil fuel power plants may be attributed, in part, to a lack of innovation in technical components as the results found that the average technical efficiency changes in 2015 - 2016 were at 146% and then dropped significantly to 2% in 2016 - 2017. Second, the average scale efficiency changes rose dramatically from -53% to 3% providing a significant contribution to the improvement of technical efficiency changes. The fossil fuel power plants become efficient as the power plants' size increases. This indicates that the size of a power plant positively impacts the performance of the TFP. [ABSTRACT FROM AUTHOR]

The utilization of residual energy of high‐temperature flue gas at the tail of coal‐fired boilers has attracted widespread attention in recent years. The thermal performances of the boiler and system in different split‐flow layouts still need to be analyzed and compared in detail. Thermodynamic models for four different splitting layouts of supercritical carbon dioxide (S‐CO2) Brayton cycles tailored for coal‐fired power plant are built and validated. By performing the process simulations, the effects of splitting ratios on the system thermal performance are comparatively analyzed when the secondary split point and the confluence point are set at different positions. The maximum system efficiency of the two‐split layout with a secondary splitting point at the inlet of the cold side of the high‐temperature recuperator (HTR) can be obtained within a range of secondary split ratio. The maximal and minimal boundaries are determined by the exhaust flue gas temperature and the heat capacity match in the recuperators, respectively. The mass flow rate of the cold stream in the low‐temperature recuperator (LTR) should be kept unchanged by constraining the sum of primary and secondary split ratios, the constant to prevent the cycle efficiency from decreasing dramatically, if the splitting layout with the split point at the outlet of the main compressor (MC) is used. The two‐splitting layout with a secondary splitting point at the inlet of the cold side of the HTR has the best performance by comparing the system efficiencies of different layouts. If there are any improved coupling approaches of the S‐CO2 Brayton cycle and boiler, this paper can provide the reference for the selections of the split ratios. [ABSTRACT FROM AUTHOR]

Air is the basis for the existence of life on Earth; but in the present age of modernization the degrading quality of air year by year, due to the growth of Industrialization, urbanization, automobiles, coal-fired thermal power plants, and various other factories is the matter of real concern. To predict the future growth of air pollutants numerous prediction models have been developed by researchers. Time-series ARIMA model although quite useful for forecasting but fails to handle non-stationary problems. Among all the existing forecasting models, wavelets along with the Machine learning models have proved to be very successful and have been widely used in various fields like mathematical modeling, signal recognition, image recognition, classification, function approximation, data processing, filtering, clustering, compression, robotics, and decision making. It is also used in the field of mathematical forecasting for developing efficient prediction models. This paper aims to develop a wavelet-ANFIS conjugation model and a wavelet-ARIMA coupled model along with the time-series ARIMA model for the prediction of black carbon concentration over the Raniganj, Jharia, and Bokaro coal mines of India, by considering a long term data obtained by NASA (http://nasa.gov/) and compare the results obtained by these models for determining the best prediction model. The validity of the results is tested with the help of error measures like RMSE, MSE, MAPE, MAE, and relative error. Results over the three sample sites conclude that the Wavelet-ANFIS conjugation approach outperforms the wavelet-ARIMA coupled approach and the simple time-series ARIMA model. [ABSTRACT FROM AUTHOR]

Dust emissions must be managed and reduced as much as possible to safeguard the environment and human health. Plate-type electrostatic precipitators have been used to decrease pollution in a number of sectors, particularly for applications needing massive volumes of gas to be dedusted at high dust concentrations and temperatures. This paper examines large-capacity plate-type electrostatic precipitators with three sections used in a coal-fired thermal power plant. Using simulations and experiments, the collection efficiency (in different ways of supplying sections, without and with sections rapping), the influence of dust resistivity and a dust layer on the surfaces of collection electrodes, the electrical parameters (voltage, current density, and space charge density) for the sections of the electrostatic precipitators, and the electrical parameters of the power sources (voltage, current, power, and power factor) are studied. A higher dust resistivity will cause a change in the shape of the voltage delivered to the sections, an increase in the average voltage from sections, and a decrease in collecting efficiency (by a few percent). A greater degree of intermittence alters the current-voltage characteristics of the sections, decreases the current across the sections, and improves collection efficiency. The density of space charges increases with the degree of intermittency and is highest at the input section. With increasing thickness of the dust layer on the collection electrodes, the collection efficiency increases. PM10 dust particles (which have a lower migration speed) are the hardest to collect with ESPs. When the sections are rapping, PM 20–30 dust particles are more difficult to collect because their migration speeds decrease significantly (compared to the situation when the sections are not rapping). The operation of the power sources of the ESP sections is dynamic, being controlled by the regulators, and the current (or current density), depending on the voltage characteristics, changes permanently (at intervals of a few seconds). The power sources of the sections are deforming consumers (the current is much different from the sinusoidal form). [ABSTRACT FROM AUTHOR]

In this paper, the quantile impact value (QIV) method was proposed as a weight coefficient distribution method to evaluate the influence of proximate analysis components on the low calorific value (LCV) of blended coals. Through data analysis technology, a new prediction model based on the QIV and the support vector regression (SVR) has been proposed to estimate the LCV. The comparisons between different analysis results reveal that the QIVW-GA-SVR model proposed here is consistently better than those models without weight coefficient distribution. [ABSTRACT FROM AUTHOR]

Near-zero carbon emission power (NZCEP) plants, consisting of gas-fired units; wind turbines; power-to-gas (P2G); and carbon capture, utilization and storage (CCUS) systems, have recently received a lot of attention due to their enormous benefits in reducing carbon emissions and increasing the consumption of renewable energy. However, a complex environment of interest and a combination of risks makes their development very slow. This paper establishes a risk analysis framework for NZCEP considering multi-stakeholder participation. Firstly, a synthetic risk factor system was constructed based on stakeholders' interests. Subsequently, interval type II trapezoidal fuzzy numbers were used and final weights were calculated from both subjective and objective aspects. Finally, we applied an acronym in Portuguese of the interactive and multi-criteria decision-making (TODIM) method to site selection to achieve a balance of interests of all stakeholders. In addition, a case study was conducted. The case result demonstrates that Zhengzhou in Henan Province is the best choice for a NZCEP power plant. A further finding is that government plays an important role in the development of NZCEP plants, with site selection results being the most sensitive to changes in the government's risk appetite. Moreover, human resources are an important factor in the siting of an NZCEP plant. [ABSTRACT FROM AUTHOR]