Search Results (179)

In ultra-supercritical (USC) power plants, P92 steel welded joints are continuously subjected to creep-fatigue (CF) loading, rendering them susceptible to premature cracking during service. To investigate the CF interaction behavior, CF tests were performed on P92 steel welded joints at 650 °C under various dwell times. The results indicate that prolonged dwell periods progressively shorten the cycle life. Scanning electron microscopy (SEM) observations reveal that with increasing dwell time, the fracture mechanism of the P92 steel gradually transitions from a fatigue-dominated failure mode to one governed by creep-fatigue interaction damage. Subsequently, nanoindentation was employed to evaluate the hardness (H), elastic modulus (E), and creep deformation, based on which the strain rate sensitivity (m) was estimated and the underlying damage mechanisms were thoroughly discussed. Full article

When methane (natural gas) fuel gas turbines switch to hydrogen–ammonia co-fuel, their thermodynamic performance undergoes significant changes. To expand the operating range of heavy-duty gas turbines when using hydrogen–ammonia co-fuel and to improve their thermodynamic performance, based on the 255.6 MW heavy-duty gas turbine at the Banshan Power Plant in Hangzhou, China, a simulation model was established. A strategy based on changing the angle of the compressor inlet guide vanes (IGVs) was proposed. The thermodynamic performance, turbine stage supercritical flow velocity, and flow matching characteristics of gas turbines were studied under different hydrogen–ammonia mixing ratios. The results indicate that the developed model can accurately predict the performance of the gas turbine under rated operating conditions, yielding a rated output power of 254.59 MW and an efficiency of 36.33%, with relative errors of −0.4% and −1.54% compared with the design values, respectively. When hydrogen–ammonia blended fuel is employed, the outlet Mach numbers of the second- and third-stage turbine stators exceed the safety limit unity. Reducing the IGV angle effectively decreases the turbine stator outlet Mach number and improves operational safety, although a slight reduction in gas turbine efficiency is observed. As the ammonia volumetric fraction in the blended fuel increases, the gas turbine output power increases while the efficiency decreases slightly, accompanied by a reduction in turbine stator outlet pressure and an increase in outlet temperature. Further investigation shows that, after IGV regulation, the combustor outlet pressure, gas turbine power output, and efficiency all increase. Under a fixed IGV opening condition, the gas turbine efficiency gradually decreases with increasing ammonia volumetric fraction. Under off-design fuel flow conditions, increasing the relative fuel flow leads to higher combustor outlet pressure and temperature, whereas increasing the ammonia volumetric fraction causes a slight reduction in these parameters. This research can provide theoretical support for the optimal design and operation of gas turbines using hydrogen–ammonia mixed fuel. Full article

Traditional fossil-fuel-based industries, including electric power generation and petrochemical production, are plagued by their inherent carbon dioxide emissions. Current efforts to minimize CO₂ discharge tend to focus on costly capture and sequestration rather than utilizing the process energy and products to produce profitable chemicals. This work describes a concept and design strategy for a comprehensive facility to convert natural gas and air to carbon monoxide, which could be further used to synthesize desirable compounds and fuels. The basic components of the process are an improved supercritical carbon dioxide (sCO₂) electric power plant for driving solid-oxide electrolysis cell (SOEC) reduction in CO₂ to CO. This study examines opportunities for integrating a sCO₂ process with an associated air separation unit (ASU) and an SOEC, including material recycling and heat integration. A Life Cycle Assessment (LCA) is expected to show more positive results than for separate processes. Preliminary economic evaluations provide a profitable process and product route for the combined process, suggesting that carbon emission reduction could be good business. Full article

This study presents a comprehensive life cycle assessment (LCA) of the modernization of an existing 460 MW coal-fired power unit into a hybrid system incorporating a high-temperature gas-cooled reactor (HTGR). The analysis was conducted from a cradle-to-grave perspective using a functional unit of 1 MWh of net electricity, based on the ecoinvent 3.9 database and the ReCiPe 2016 Midpoint method. The results indicate that the modernized system achieves a global warming potential (GWP) of 18.2 g CO₂-eq/kWh, representing a 93.5% reduction compared to a supercritical coal-fired unit. The largest contribution to the total environmental burden is associated with the upstream uranium supply chain, accounting for approximately 42% of GWP. In contrast, the operational phase exhibits a negative contribution due to the application of environmental credits resulting from the avoidance of emissions related to coal combustion. The findings also confirm a significant improvement in resource efficiency, including reduced primary energy demand and waste generation compared to the reference system. Sensitivity analysis demonstrated the robustness of the results with respect to variations in key economic and thermodynamic parameters, particularly CAPEX (capital expenditures) and operating temperature. Overall, the results suggest that hybrid retrofitting of coal-fired power plants with HTGR technology may serve as a viable transitional pathway supporting the decarbonization of the Polish energy sector. Full article

The demand for efficient combustion in boilers drives the development of ultra-supercritical power plants. P92 steel pressure, and pipelines operate in high-temperature and high-pressure environments and are prone to high-temperature creep damage. Non-destructive testing is a key method to ensure the safety of the pipe. However, existing non-destructive testing methods are difficult to achieve non-destructive detection of creep damage. Creep damage affects magnetic Barkhausen noise (MBN) and magneto-acoustic emission (MAE) signals; therefore, it is possible to evaluate creep damage using these signals. This article first establishes a theoretical model for MBN and MAE. Afterward, the influence of magnetizing waveform, amplitude, and frequency on MBN and MAE signals was studied through experiments. Finally, by analyzing the characteristics of MBN and MAE signals, the optimal magnetization conditions and signal characteristic parameters for detecting creep damage using MBN and MAE signals were determined. The experimental results also confirmed the correctness of the theoretical model. Full article

To address the problems of inaccurate blended coal quality prediction and difficulty in constrained coal blending optimization in coal-fired power plants, a data-driven coal blending optimization method based on Random Forest (RF) and the Coati Optimization Algorithm (COA) is proposed. First, an RF-based prediction model is developed to estimate key blended coal quality indices, including heating value, volatile matter, ash content, and sulfur content, under small-sample conditions. Second, based on actual operating data from an ultra-supercritical unit and relevant national standards, plant-specific boundary constraints for as-fired coal quality are established. Third, the RF prediction model is embedded into the COA-based optimization framework to search for blending schemes with minimum procurement cost under multiple coal quality constraints. The results show that the RF model achieves higher prediction accuracy than the conventional weighted average method for all four quality indices. In the case study, the cost-oriented optimized scheme reduces the procurement cost by 5.05% while satisfying the prescribed coal quality constraints. The proposed method provides a feasible decision-support approach for coal blending management in coal-fired power plants. Full article

The article documents the cause of a sharp decrease in the fracture toughness of HR3C austenitic steel intended for heat exchange surfaces of supercritical energy blocks during its exposure to elevated temperature. The documentation of the cause of the decrease in fracture toughness is based on a combination of fractographic observation of the fracture surfaces of the tested samples, linked through ongoing precipitation changes in the steel to the fracture toughness of the steel. The result is a description of the decrease in fracture toughness in relation to the Larson–Miller parameter and subsequently the change in fracture toughness in relation to the precipitation changes in HR3C steel. This dependence provides a tool for numerical calculations and simulations of heat exchange surfaces of power plants made of HR3C steel and the simulation of their behavior when cracks are present. Full article

Many countries rely on coal for energy security during renewable transitions. This study conducts a technical, economic, and environmental analysis of hybridizing a supercritical coal-fired power unit with photovoltaics (PV) to create a sustainable hybrid system at a plant in Silesian Voivodeship, Poland. The goal is to assess costs and optimal operating conditions for a coal–PV hybrid under varying scenarios, using a decision-support model that integrates fuel prices, CO₂ emission charges (EUA), and technical parameters. Two main scenarios are modeled. In auxiliary-only PV (112 MW system), real-time power supplies pumps and fans, cutting coal consumption without storage; LCOE decreases with annual hours (2800–7000), outperforming conventional coal across EUA prices (20–50 EUR/t). In PV surplus export, excess generation (1300 h/year) is grid-fed for revenue, amplifying LCOE reductions—hybrid superiority emerges above 34 EUR/t EUA, per equivalence thresholds. Results show coal electricity exceeds low-emission costs above 34 EUR/t CO₂, with maximum disparity at 50 EUR/Mg. The hybrid leverages existing infrastructure, mitigates solar intermittency via auxiliary supply, ensures baseload continuity, boosts flexibility, and prolongs asset life—reducing >123,000 EUA/year at 145,000 MWh PV output. This sustainable hybrid promotes energy transition, reduces fossil fuel dependence, and aligns with global sustainability goals. Full article

The application of ultra-supercritical power plant boilers is becoming increasingly widespread. P92 steel, as a typical material used for boiler main steam pipes, plays a critical role in unit safety, making the detection of its creep damage highly significant. However, existing conventional non-destructive testing methods are difficult to effectively detect creep damage. To address this issue, a magnetoacoustic emission (MAE)–magnetic Barkhausen noise (MBN) composite measurement system is developed, which is adapted to 20 Hz and 0.3 A sine wave excitation to trigger the synchronous pickup of MBN and MAE signals of P92 steel. After collecting signals with different creep life ratios (0%~100%) under working conditions of 650 °C and 100 MPa, time-domain (absolute mean, peak value, etc.) and frequency-domain (bandwidth) features are extracted. In response to the non-monotonicity between the magnetoacoustic features and the creep damage grade, principal component analysis (PCA) is introduced to reduce dimensionality. Different creep levels of samples in the two-dimensional principal component space are presented as clear gradient clustering, achieving the accurate differentiation of creep stages. Research has shown that the MAE-MBN composite system combined with PCA can effectively characterize the creep damage of P92 steel, providing a novel non-destructive detection path for the in-service life assessment of power plant components. Full article

Corona quenching is a major obstacle to the stable and efficient operation of electrostatic precipitators (ESPs) in coal-fired power plants, particularly under high-ash coal combustion. This study evaluates a novel double-V labyrinth pre-collection device as an active strategy to mitigate corona quenching. Field measurements from a 660 MW ultra-supercritical coal-fired unit, combined with computational fluid dynamics (CFD) simulations, demonstrate that the retrofit significantly improved inlet flow uniformity and reduced fly ash concentration before the ESP. Consequently, corona discharge stability was enhanced, overall collection efficiency increased from 99.42% to 99.92%, and outlet fly ash concentration decreased from 81 mg/m³ to 20.5 mg/m³. Although the pressure drop rose modestly (128 Pa to 187.5 Pa), the overall ESP energy demand was reduced due to more stable operation at lower voltages. These results confirm the technical feasibility and engineering applicability of pre-collection technology, providing a cost-effective solution to overcome corona quenching and ensure ultra-low emission compliance in large coal-fired units. Full article

This study investigates the energy performance and preliminary turbomachinery design of post-combustion CO₂ compression systems integrated into an ultra-supercritical coal-fired power plant with carbon capture and storage (CCS). To enable pipeline transport, CO₂ must be delivered at 150 bar and 15 °C, i.e., in liquid phase. Unlike conventional configurations that compress CO₂ entirely in the gaseous/supercritical phase before final cooling, two alternative layouts are proposed, introducing an intermediate liquefaction step prior to liquid-phase compression. Each layout uses a chiller system that operates at CO₂ condensation temperatures of 10 °C and 20 °C. The energy performance and the system layout architecture are evaluated and compared with the conventional gaseous-phase compression configuration. An in-depth sensitivity analysis, which varies the flow coefficient, the working coefficient, and the degree of reaction, confirms that the turbomachinery preliminary design, based on input parameters related to the specific speed, is a high-efficiency design. The results indicate that the 10 °C liquefaction layout requires the least compression power (60 MW), followed by the 20 °C layout (62.5 MW) and the conventional system (67 MW). Including the consumption of the chiller, the proposed systems require an additional power of 11–12 MW, compared to just over 1 MW for the conventional layout with simple CO₂ cooling. These results highlight the significant influence of the integration of the chiller on the overall power requirement of the system. Although the proposed configurations result in a larger equipment footprint, the integrated capture and compression/liquefaction system allows for very low CO₂ emissions, making the power plant more sustainable. Full article

Improving the energy efficiency of advanced ultra-supercritical (USC) power plants by increasing steam operating temperature up to 700 °C can be achieved, at reduced cost, by using novel engineering design concepts, such as coated steam pipe systems manufactured from high temperature materials commonly used in current operational power plants. The durability of thermal barrier coatings (TBC) in advanced USC coal power systems is critically influenced by thermally grown oxide (TGO) evolution and interfacial stress under thermo-chemo-mechanical coupling. This study investigates a novel dual-pipe coating system comprising an inner P91 steel pipe with dual coatings and external cooling, designed to mitigate thermal mismatch stresses while operating at 700 °C. A finite element framework integrating thermo-chemo-mechanical coupling theory is developed to analyze TGO growth kinetics, oxygen diffusion, and interfacial stress evolution. Results reveal significant thermal gradients across the coating, reducing the inner pipe surface temperature to 560 °C under steady-state conditions. Oxygen diffusion and interfacial curvature drive non-uniform TGO thickening, with peak regions exhibiting 23% greater thickness than troughs after 500 h of oxidation. Stress analysis identifies axial stress dominance at top coat/TGO and TGO/bond coat interfaces, increasing from 570 MPa to 850 MPa due to constrained volumetric changes and incompatible growth strains. The parabolic TGO growth kinetics and stress redistribution mechanisms underscore the critical role of thermo-chemo-mechanical interactions in interfacial degradation. These research findings will facilitate the optimization of coating architectures and the enhancement of structural integrity in high-temperature energy systems. Meanwhile, clarifying the stress evolution within the coating can improve the ability to predict failures in USC coal power technology. Full article

With the continuous increase in the proportion of renewable energy in the power grid, enhanced operational flexibility of the power system is required. As baseload generators, combined heat and power (CHP) units are prime candidates for flexibility retrofits that guarantee grid stability. Among the available options, molten-salt thermal energy storage (TES) offers an energetically efficient route to decouple heat and electricity production in CHP plants. In this study, a 660 MW ultra-supercritical coal-fired unit is taken as the object of investigation. Sixteen technical routes incorporating steam extraction and electric heating for thermal energy storage and discharging are systematically designed. Results demonstrate that all the combined schemes significantly improve the operational flexibility of the unit. Among them, the C1-S1 configuration exhibits the most outstanding overall economic performance, with a six-hour thermal storage capacity of 294.34 MWh. The system exergy destruction is measured at 6258 kW, while the round-trip efficiency and thermal efficiency are determined to be 81.11% and 45.48%, respectively. Full article

In the context of the zero-carbon transition, this article provides a comprehensive review of Organic Rankine Cycle (ORC) technologies for low-grade heat recovery and conversion to power. It surveys a wide range of renewable and waste heat sources—including geothermal, solar thermal, biomass, internal combustion engine exhaust, and industrial process heat—and discusses the integration of ORC systems to enhance energy recovery and thermal efficiency. The analysis examines various configurations, from basic and regenerative cycles to advanced transcritical and supercritical designs, cascaded systems, and multi-source integration, evaluating their thermodynamic performance for different heat source profiles. A critical focus is placed on working fluid selection, where the landscape is being reshaped by stringent regulatory frameworks such as the EU F-Gas regulation, driving a shift towards low-GWP hydrofluoroolefins, natural refrigerants, and tailored zeotropic mixtures. The review benchmarks ORC against competing technologies such as the Kalina cycle, Stirling engines, and thermoelectric generators, highlighting relative performance characteristics. Furthermore, it identifies key trends, including the move beyond single-source applications toward integrated hybrid systems and the use of multi-objective optimization to balance thermodynamic, economic, and environmental criteria, despite persistent challenges related to computational cost and real-time control. Key findings confirm that ORC systems significantly improve low-grade heat utilization and overall thermal efficiency, positioning them as vital components for integrated zero-carbon power plants. The study concludes that synergistically optimizing ORC design, refrigerant choice in line with regulations, and system integration strategies is crucial for maximizing energy recovery and supporting the broader zero-carbon energy transition. Full article

Radioactive organic anion exchange resins present a significant challenge in nuclear power plant waste disposal due to their volatility, instability, and biotoxicity. Based on experimental degradation data from the supercritical water oxidation (SCWO) of organic anion exchange resin waste liquids from the nuclear industry, this study conducted correlation analysis, cluster analysis, and Sobol sensitivity analysis of key process parameters. The results indicate that temperature is the primary factor influencing chemical oxygen demand (COD) and total nitrogen (TN) removal, while oxidant dosage exhibits a notable synergistic effect on nitrogen transformation. A Gaussian Process Regression–Non-Dominated Sorting Genetic Algorithm II (GPR–NSGA-II) multi-objective optimization model was developed to balance COD/TN removal rate and treatment cost. The optimal operating conditions were identified as a temperature of 472.2 °C, an oxidant stoichiometric ratio (OR) of 136%, an initial COD concentration of 73,124 mg·L⁻¹, and a residence time of 3.8 min. Under these conditions, COD and TN removal efficiencies reached 99.63% and 32.92%, respectively, with a treatment cost of 128.16 USD·t⁻¹. The proposed GPR–NSGA-II optimization strategy provides a methodological foundation for process design and economic assessment of SCWO in treating radioactive organic resin waste liquids and can be extended to other studies involving high-concentration, refractory organic wastewater treatment. Full article