Supercritical Thermal Power Plant Research Articles

Thermodynamic and Economic Analysis of a Standalone Supercritical Thermal Power Plant Integrated with Molten Carbonate Fuel Cell

A detailed technoeconomic analysis of a standalone steam cycle integrated with molten carbonate fuel cell and an organic Rankine cycle is presented herein. The modeling and thermodynamic analysis of the proposed plant is performed using a commercially available software tool called Cycle Tempo. The response surface methodology tool is employed to develop regression models to predict the plant's energy, exergy efficiencies, and levelized cost of electricity (LCOE) for varying independent factors: fuel utilization factor (uf) CO2 utilization factor (ϕ), and current density (i) of the fuel cell. The response surfaces developed from the models are used to conduct the parametric analyses on the plant. The desirability test performed for multiobjective optimization has shown the optimum plant configuration, with higher energy, exergy efficiencies, and a lower LCOE is obtained for uf = 0.85, ϕ = 60%, and i = 1000 A m−2 With an intent to reduce CO2 emissions, monoethanolamine‐based carbon capture system is implemented to the plant configuration, that exhibits maximum energy efficiency for ϕ = 90%, and results in an LCOE of 6.53 Rs kWh−1.

New estimation method of limit pressures for thick curved pipes under internal pressure applicable to various bend angles

In this study, a new estimation method of limit pressures (loads) is suggested for reliability design of curved pipes under high internal pressure and temperature. The curved pipes are used in boiler pipes in a supercritical thermal power plants. To find any design parameters and their dimensions in reliability design of curved pipes, various boilers in supercritical thermal power plants in operation were investigated. In order to analyse the effect of the design parameters on the limit pressure, the design of experiment (DOE) was applied to design a curved pipes with various combinations of design parameters, and then the FE limit load analyses were performed to obtain limit pressures. The thickness of the curved pipe has the greatest effect on the limit pressure among the design parameters. Although the bend angle is design parameter, the proposed estimation methods for easily calculating the limit load do not include the bend angle and then there have been difficulties in reliability design of curved pipes with any band angle. Therefore, to solve such difficulties, two estimation methods of limit pressure (load) including bend angle were suggested and the validity of the proposed estimation methods of limit load (plastic pressure) under internal pressure was objectively verified through statistical error analysis with the 60 FE analysis results which are different from the data used when the method was derived. The proposed estimation method applicable to various bend angles shows the best results in the evaluation of mean error, maximum error, and standard deviation of error, which are evaluation criteria. The proposed estimation method shows a very good result compared to existing methods, having the mean error of 0.89%, a maximum error of 2.50%, and a standard deviation of 0.70% for all data regardless of the bend angle.

Continual Learning for Multimode Dynamic Process Monitoring With Applications to an Ultra–Supercritical Thermal Power Plant

This paper introduces a novel sparse dynamic inner principal component analysis (SDiPCA) based monitoring for multimode dynamic processes. Different from traditional multimode monitoring algorithms, a model is updated for sequential modes by memorizing the significant features of existing modes. By adopting the concept of intelligent synapses in continual learning, a loss of quadratic term is introduced to penalize the changes of mode–relevant parameters, where modified synaptic intelligence (MSI) is proposed to estimate the parameter importance. Thus, the proposed algorithm is referred to as SDiPCA–MSI. When a new mode arrives, a set of normal samples should be collected. The previous significant features are consolidated without explicitly storing training samples, while extracting new information from the current mode. Consequently, SDiPCA–MSI can provide outstanding performance for successive modes. Characteristics of the proposed approach are discussed, including the computational complexity, advantages and potential limitations. Compared with several state-of-the-art monitoring methods, the effectiveness and superiorities of the proposed method are demonstrated by a continuous stirred tank heater case and a practical industrial system. Note to Practitioners—Multimode process monitoring is increasingly significant as industrial systems generally operate in varying operating conditions. However, most researches focus on multiple local monitoring models for complex multimode processes and assume that data of all possible modes are available and stored before learning. When similar or new modes arrive, local models are rebuilt corresponding to each mode and the model’s capacity would increase with the continuous emergence of modes. Adaptive methods are a branch of multimode monitoring algorithms, but they strive to extract information of the current mode to ensure the monitoring performance while forgetting the previously learned knowledge gradually. This paper proposes a novel sparse dynamic inner principal component analysis with continual learning ability for multimode dynamic process monitoring, where modified synaptic intelligence is developed to measure the parameter importance accurately. It requires limited computation and storage resources for successive modes, which is convenient for practical applications. Similar to current multimode process monitoring algorithms, a set of data should be collected before learning a new mode, which may bring difficulties to real–time monitoring. For industrial systems, such as large–scale power plants and chemical systems, the proposed method has outstanding ability to monitor successive dynamic modes.

Thermodynamic Analysis of a Reconfigured 500-MWe Supercritical Thermal Power Plant by Integrating Solid Oxide Fuel Cell and a Gas Turbine

Thermodynamic Analysis of a Reconfigured 500-MWe Supercritical Thermal Power Plant by Integrating Solid Oxide Fuel Cell and a Gas Turbine

A new assessment mechanism of primary frequency regulation capability for a supercritical thermal power plant in deep peaking

AbstractWith the rapid development of renewable energy, the primary frequency control (PFC) is becoming more critical and significant to ensure the stability of the electrical power system. As the main role of PFC, the thermal power unit tends to in a wide operation interval, and the changes in PFC characteristics along with working conditions are inevitable. By decomposing and quantifying the dynamic energy conversion process, this paper proposes a novel mechanism to evaluate the PFC capability for the supercritical thermal power plants that covered 30%–100% of the rated load. In the mechanism, a refined steam turbine model is established to reflect the short‐term dynamic response of PFC by combining it with the coupling characteristics of the main steam valve and main steam pressure in the later phase. Meanwhile, as a new prior assessment index, the equivalent electricity has been put forward to quantify the PFC capability for the power plant. In a case study of a 600 MW supercritical power plant, the capacities of PFC under 30%–50% of the rated load are quantified for the first time. Comparison results between theoretical calculation and real PFC test show that the proposed PFC capability assessment mechanism has acceptable accuracy of 96.1%, which could be effective to assess the frequency response reserve and stability margin in the grid.

Enhancing the Energy Efficiency of a Supercritical Thermal Power Plant Through Improved Plant Load Factor, and Optimized Performance of Auxiliary Equipment

Enhancing the Energy Efficiency of a Supercritical Thermal Power Plant Through Improved Plant Load Factor, and Optimized Performance of Auxiliary Equipment

Issues and solutions for integrity of pressure vessels and piping subjected to long-term creep exposure in supercritical thermal plants

ABSTRACT ASME BPVC Section VIII Division 2 (‘ASME VIII(2)’) and ASME B31.1 are being used not only for low-temperature design but also for high-temperature design in the creep range in supercritical thermal power plants. However, creep effects in ASME VIII(2) and B31.1 are taken into account implicitly, and there could be significant technical issues in terms of conservatism in the case of long-term operation in the creep range because their design evaluation results do not change across plant operation time. The conservatisms of ASME VIII(2) and B31.1 have been quantified based on comparisons with nuclear-grade design rules of ASME BPVC Section III Division 5 and RCC-MRx which take creep hold time into account explicitly. It was shown that ASME VIII(2) and B31.1 results could be non-conservative if operation time exceeds a certain time limit, which raises concerns around non-conservatism in the case of long-term operation within the creep range.

Numerical analysis of environment-friendly solar aided coal-fired supercritical thermal power plant cycle integrated with dual heat exchangers

The hybrid solar-coal supercritical steam thermal system has been developed in current research work. The proposed system uses a double-tank heat storage system to increase the stability of the solar tower system, and two heat exchangers to transfer heat from molten salt in the solar tower system to steam in a supercritical coal-fired thermal system. TRNSYS software has been used as a platform to build a model of the solar coal-fired hybrid supercritical steam thermal system. Local weather data is imported to simulate the characteristic year’s operation of a hybrid system under design and off-design working conditions. The variation of heat transferred from solar system to supercritical steam thermal system, power generated from supercritical steam thermal system, solar-electrical generation capacity, efficiency and proportion of solar power generation are compared and analyzed. The results show that after the system is integrated, the tower solar steam production mechanism will increase the output power of supercritical steam thermal system and reduce thermal efficiency of the integrated system. When boiler steam flow rate is kept at less than reference flow rate after joining with solar steam flow rate, total steam flow rate exceeds the reference flow rate, while solar steam flow rate increases.

Irreversibility analysis of various components in a supercritical thermal power plant

Irreversibility analysis of various components in a supercritical thermal power plant

Irreversibility analysis of various components in a supercritical thermal power plant

Irreversibility analysis of various components in a supercritical thermal power plant

Thermodynamic analysis of a coal fired supercritical thermal power plant integrated with molten carbonate fuel cell powered by coal gasification

Thermodynamic analysis of a coal fired supercritical thermal power plant integrated with molten carbonate fuel cell powered by coal gasification

Thermodynamic analysis of a coal fired supercritical thermal power plant integrated with molten carbonate fuel cell powered by coal gasification

Thermodynamic analysis of a coal fired supercritical thermal power plant integrated with molten carbonate fuel cell powered by coal gasification

Securing integrity of high-temperature pressure boundary components in supercritical thermal plants with application of alternative design rules

Technical issues of ASME BPVC Section VIII Division 2 (hereafter, ‘ASME VIII(2)’) were investigated when it was applied to design of high-temperature pressure vessels in supercritical thermal power plants subjected to long-term operation in the creep regime. The design rules of ASME VIII(2) are generally used for the design of pressure vessels operating not only at low temperature but also at high temperature in the creep range. The potential connections of ASME VIII(2) with a number of defects in pressure vessels due to technical issues on the implicit consideration of the creep effects were investigated. For the superheater component subjected to long-term operation in the creep regime, design evaluations were conducted according to ASME VIII(2) and three alternative design rules of ASME BPVC Section III Division 5 Subsection HB, French RCC-MRx and ASME Section VIII Division 2 Code Case 2843–2 that consider creep effects explicitly. Code comparisons were made in terms of conservatism. It was shown that there does exist concern about the non-conservatism of ASME VIII(2) associated with designs subjected to long-term operation in the creep range; the issues can be addressed with application of three alternative design rules to enhance integrity of pressure vessel.

Techno-economic analysis of a 500 MW<SUB align="right">e supercritical coal-based thermal power plant with solar assisted MEA-based CO<SUB align="right">2 capture

The present study deals with the techno-economic analysis of a 500 MWe supercritical (SupC) thermal power plant (TPP) integrated with solar assisted monoethanolamine (MEA) absorption-based CO2 capt...

A novel thermodynamic method and insight of heat transfer characteristics on economizer for supercritical thermal power plant

The technology of installing economizer has been proven to be an efficient way of recovering waste heat from flue gas of coal-fired power plants. In this study, a novel theoretical model of economizer involving heat transfer characteristics and regarding the variation of physical properties for working fluid is proposed to evaluate and analyze the thermodynamic performance of economizer for supercritical unit. With such a tool, a theoretical investigation on heat transfer characteristics and exergy analysis of process with regard to economizer installed in a 660 MW supercritical unit is performed. The performance parameters on heat transfer are graphically presented. Moreover, the heat transfer performance of economizer from novel theory is compared with that obtained by traditional method, and the drawbacks of traditional model are thoroughly revealed.Investigation results show that, the temperature difference of counter-flow heat transfer is not always greater than that of forward-flow heat transfer along heating surface length, but the boundary point appears at the dimensionless length of 0.2–0.3 of economizer area, and the lower boiler load, the closer boundary point is to 0.2. The deviation between average heat transfer coefficient and local heat transfer coefficient reaches the maximum at flue gas outlet of economizer, and which varies with load and layout. Furthermore, the heat transfer area required for each 1 °C rise of water temperature and exchanged heat, influenced by the change of physical properties of heat transfer medium, show a different trend with increment in water temperature for economizer under different arrangements. The exergy efficiency presents different variation laws in process heat transfer with different layout and different loads, and such a phenomenon is obviously different from that obtained on overall heating surface. This work provides a broadly applicable approach for economizer and even other heat exchangers to formulaically revealing the veritable microcosmic principles of heat transfer characteristics.

Investigations on creep life of Alloy 617 material for the final stage superheater coils for ultra super critical thermal power plants

Thermal power plant will continue to cater to the power demand of India at least for two more decades. Research is going on continuously to increase the temperature of operation of the materials used in power plant to increase the operating efficiency, conserve the fuel and reduce the environmental impact of power generation. Superheater coils made of nickel based alloys have an advantage over conventionally used materials like AISI 316, P91, P92 in powerplants. In the present work, an attempt is made to understand the creep related life of nickel based superalloy, Alloy 617 material in India powerplants. Alloy 617 can be a potential material for an ultra-super critical powerplant as it is known to withstand temperatures of around 700 °C and supercritical pressure upto 300 bar. These parameters significantly higher than the present operating values of 600 °C and 250 bar pressure in a typical Indian scenario. Extensive literature survey was carried out to understand the existing creep models, the thermophysical properties and parameters for evaluating Larson-Miller Parameter (LMP). Heat transfer simulation was carried out using ANSYS to predict the temperature field and the hoop stresses induced in the final stage of super heater coil exposed to the severest operating conditions in the power boiler, was predicted based on the boiler operating pressure in the ultra-super critical region. Formation and growth of oxide scale was not considered in the present model as literature suggests that the rate of oxide formation is negligible for the present material at 700 °C. Hoop stress and temperature distribution were used to predict the total life by applying Larson Miller Parameter approach. Robinson’s damage summation rule was attempted to determine the creep life of the material for the above conditions. Based on the analysis, it is observed that Alloy 617 can be the most suitable material for final stage superheater coil operating at around 700 °C.

A L1-LEMPC hierarchical control structure for economic load-tracking of super-critical power plants

The super-critical thermal power plants are undertaking more and more responsibilities for the balance of the power grid intermittency of the renewable energies. However, the frequent wide-range load regulation may deteriorate the operational efficiency of the power plant. To this end, a hierarchical control structure with two layers is proposed in this paper. An economic model predictive controller using a locally linearized model of the plant (LEMPC) is employed in the upper layer to realize an optimal load tracking. A L1 adaptive controller in the lower layer forces the plant to track the optimal trajectory by estimating and compensating the lumped uncertainty between the real plant and the linear model. The tracking performance is theoretically proved to reach the desired transient process. The proposed hierarchical control architecture is validated through simulations on a simplified 1000MW super-critical boiler-turbine unit model with comparison to the other two conventional real-time optimization control approaches. The results show that the proposed L1-LEMPC control system produces better load tracking performance than the other two conventional control strategies with higher operational economy efficiency. Moreover, under the environment of severe external disturbance and parameter perturbation, the proposed control system still maintains satisfactory performance.

Water footprint of thermal power in China: Implications from the high amount of industrial water use by plant infrastructure of coal-fired generation system

To reflect an important aspect of the water footprint of thermal power in China, this study as an extension of a previous work (Wu et al., 2018a) uncovers the high amount of industrial water use induced by plant infrastructure of a typical coal-fired power generation system. The systems process method is used by combining process analysis and water intensities obtained from systems input-output analysis. Industrial water use induced by plant infrastructure is accounted to be several times greater than previous estimates, and approximate to or much larger than that induced by fuel mining, preparation and transport in total. For per unit of electricity output, the water use by plant infrastructure amounts to 8.4% of the direct freshwater withdrawal for the majority of supercritical thermal power plants equipped with wet tower cooling, and even up to 38% of the freshwater withdrawal for some plants with air tower cooling. The annual water use induced by coal-fired power generation infrastructure in China is estimated to be 0.6%, 7%, and 23% of the annual freshwater withdrawal by China, Japan, and United Kingdom, respectively. The outcome provides a benchmark for policy makers to measure and curb the upstream water use by plant infrastructure.

COMPARISON OF ENERGY FLOW STREAM AND ISENTROPIC METHOD FOR STEAM TURBINE ENERGY ANALYSIS

In this paper, a comparison of two different methods for a steam turbine energy analysis is presented. A high-pressure steam turbine from a supercritical thermal power plant (HPT) was analysed at three different turbine loads using the energy flow stream (EFS) method and isentropic (IS) method. The EFS method is based on steam turbine input and output energy flow streams and on the real steam turbine produced power. The method is highly dependable on the steam mass flow rate lost through the turbine gland seals. The IS method is based on a comparison of turbine steam expansion processes. Observed energy analysis methods cannot be directly compared because they are based on different sources of steam turbine energy losses, so, an overall steam turbine energy analysis is presented. Unlike most steam turbines from the literature, the analysed HPT did not have the highest overall energy efficiency at a full load due to exceeding the water/steam critical pressure at the turbine inlet during such operation.

Effect of Heat Treatment on Microstructure and Hot Impact Toughness of Various Zones of P91 Welded Pipes

The new generation super critical thermal power plants are required to operate at enhanced thermal efficiency of over 50% to reduce the fuel consumption and environmental pollution. Creep strength-enhanced ferritic steels, commonly known as Cr-Mo alloys such as P91 (X10CrMoVNb 9-1) are such material of choice for the next generation power plants. The operating requirement of these next generation power plants is that steam temperature of around 650 °C is maintained. For such high-temperature application, creep strength of material is the primary consideration together with adequate weld heat-affected zone (HAZ) toughness. Present work deals with the effect of high service temperature on impact toughness of P91 (X10CrMoVNb 9-1) base material, weld fusion zone, and HAZ. The impact toughness of HAZ for conventional weld groove design and narrow weld groove design has been evaluated experimentally in as-welded and at different post-weld heat treatment conditions. Fractography of the impact toughness specimens of base metal, weld fusion zone, and HAZ was carried out using scanning electron microscope. The effects of heat treatment schemes on the percentage of element present at the fracture surface were also studied.