Search Results (129)

Carbon capture is pivotal for achieving carbon neutrality; however, its high energy consumption severely limits the operational flexibility of power plants and remains a key challenge. This study, targeting a full flue gas carbon capture scenario for a 1000 MW coal-fired power plant, identified the dual-element (“steam” and “power generation”) coupling convergence mechanism. Based on this mechanism, a comprehensive set of mathematical model equations for the “carbon–electricity–heat” coupling process is established. This model quantifies the dynamic relationship between key operational parameters (such as unit load, capture rate, and thermal consumption level) and system performance metrics (such as power output and specific power penalty). To address the challenge of flexible operation, this paper further proposes two innovative coupled modes: steam thermal storage and chemical solvent storage. Model-based quantitative analysis indicated the following: (1) The power generation impact rate under full THA conditions (25.7%) is lower than that under 30% THA conditions (27.7%), with the specific power penalty for carbon capture decreasing from 420.7 kW·h/tCO₂ to 366.7 kW·h/tCO₂. (2) Thermal consumption levels of the capture system are a critical influencing factor; each 0.1 GJ/tCO₂ increase in thermal consumption leads to an approximate 2.83% rise in unit electricity consumption. (3) Steam thermal storage mode effectively reduces peak-period capture energy consumption, while the chemical solvent storage mode almost fully eliminates the impact on peak power generation and provides optimal deep peak-shaving capability and operational safety. Furthermore, these modeling results provide a basis for decision-making in plant operations. Full article

The CO₂ capture process in coal-fired power plant flue gas still faces the difficulties of low material performance and high energy and cost consumption. It is necessary to develop new capture solvents and materials, and also new capture process configurations, to achieve breakthroughs in capture performance and process technology. In various process configurations for CO₂ absorption, lean solution vaporization and compression (LVC) is a commonly used and effective one for reducing the energy and cost consumption. This work propose a partial lean solution vaporization and compression (PLVC) configuration to decrease energy and cost consumption for CO₂ capture, considering the price difference in heat and electricity with the high prices of compressors. The three heat exchange methods of no heat exchange, separate heat exchange, and merged heat exchange for lean solution after flash evaporation are also proposed with PLVC, which could be used in the range of low (0–25%), middle (25–75%), and high split ratios (75–100%) of lean solution for the lowest total heat consumption of the aqueous AMP + PZ solvent. Therefore, the comprehensive cost of the capture process can be minimized by considering different prices of steam heat, electricity, and compression facility. Full article

Ammonia–coal co-firing is emerging as a promising technological pathway to reduce carbon production during coal-fired power generation. However, the coupling effects of the ammonia energy ratio (E_NH3) and equivalence ratio on the ignition mechanism and emission characteristics—particularly under staged injection conditions—remain insufficiently understood. This study investigates these characteristics in a laboratory-scale furnace. Spontaneous chemiluminescence imaging and flue gas analysis were employed to decouple the effects of aerodynamic interactions and chemical kinetics. The experimental results reveal that the ammonia injection strategy is the critical factor governing coal ignition performance. Compared to the premixed mode, staged injection—which establishes an independent, high-temperature ammonia flame zone—provides a superior thermal environment and circumvents oxygen competition between the fuels, thereby markedly promoting coal ignition. At an E_NH3 of 50%, the staged configuration reduces the ignition delay time of coal volatiles by a striking 60.93%. Within the staged configuration, increasing either the co-firing ratio or the overall equivalence ratio further enhances coal ignition. Analysis of pollutant emissions elucidates that the formation of NO, N₂O, and NH₃ is intimately linked to the local combustion conditions of ammonia. An excessively lean local equivalence ratio leads to incomplete ammonia combustion, thereby increasing N₂O and NH₃ slip. Full article

Managing phosphorus (P) in acidic paddy soils is crucial for sustaining rice yields. However, the effects of combined humic acid (HA) and flue gas desulfurization gypsum (FG), a by-product of coal-fired power plants, on P forms remain poorly understood. This study examined P forms using a sequential extraction procedure and XANES spectroscopy following the application of HA, FG, and HA + FG. HA increased organic labile P, while FG and HA + FG promoted HCl-extractable Pi and humic Po, respectively. XANES data revealed that P associated with aluminum (Al) (hydr)oxides was dominant in acidic paddy soils. Brushite (CaHPO₄·2(H₂O)) accounted for 25% and 19% of total P in the FG- and HA + FG-treated soil, respectively. Iron (Fe)-bound P was absent in control and FG-treated soils but was present as strengite (FePO₄·2H₂O) in HA- and HA + FG-treated soils (23% and 30% of the total P, respectively). Inositol hexakisphosphate (IHP), a non-labile Po, was in HA- and HA + FG-treated soil (12% and 31% of the total P, respectively). Archerite (KH₂PO₄) was 40% and 20% of the total P in HA- and HA + FG-treated soil, respectively. HA alone is an effective soil amendment that enhances P cycling and availability by increasing organic P mineralization, boosting rice yield in acidic paddy soil. Full article

The study examines the influence of diverse flue gas compositions on the operational parameters and efficiency of MCFCs (molten carbonate fuel cells) as CO₂ separation devices to provide foundational knowledge on MCFC operation under various industrial conditions. MCFCs inherently rely on the presence of CO₂ at the cathode, where it combines with oxygen to form carbonate ions that migrate through the electrolyte; thus, CO₂ acts as a carrier species rather than a fuel, enabling simultaneous electricity generation and CO₂ separation. The findings indicate that MCFCs are most effective when operated with CO₂-rich flue gases, such as those from coal and lignite-fired power plants with CO₂ contents of roughly 12–15 vol.% and O₂ contents of 2–6 vol.%. In these cases, CO₂ reduction rates of up to 80% can be achieved while maintaining favorable cell voltages. Under such conditions, relevant also for the cement industry (CO₂ between 15 and 35 vol.%), the Nernst voltage can reach about 1.18 V. In contrast, flue gases from gas turbines, which typically contain only 4–6 vol.% CO₂ and 11–13 vol.% O₂, result in lower Nernst voltages (0.6–0.7 V) and a decrease in efficiency. To address this issue, potential modifications to the MCFC electrolyte are suggested to enhance oxygen-ion conductivity and improve performance. By quantifying the operational window and CO₂-reduction potential for different sectors at 650 °C and 1 atm using a reduced-order model, the paper provides a technology assessment that supports sustainable industrial operation and the design of CCS (carbon capture and sequestration) strategies in line with climate goals. Full article

Growing efforts to reduce air pollution have accelerated the development of advanced flue gas treatment technologies for coal-fired power plants. This study presents the design, development, and industrial-scale implementation of a microwave-assisted non-thermal plasma reactor, powered by a 75 kW, 915 MHz magnetron, for simultaneous sulfur dioxide (SO₂) removal and fly ash agglomeration. The reactor was installed on the outlet line of the selective catalytic reduction (SCR) system of a 22 MW_e pulverized-coal-fired boiler and evaluated under real flue gas conditions. The flue gas stream, extracted by an induced-draft fan, was supplied to the reactor through two configurations—radial and axial injection—to investigate the influence of gas flow rate and microwave power on SO₂ abatement performance. Under radial injection, the system achieved a maximum SO₂ removal efficiency of 99.0% at 5194 Nm³/h and 75 kW, corresponding to a specific energy consumption of 14.4 Wh/Nm³. Axial injection resulted in a removal efficiency of 97.5% at 4100 Nm³/h. Beyond SO₂ mitigation, exposure of flue gas to the microwave-assisted plasma environment significantly enhanced particle agglomeration, as confirmed by means of SEM imaging and particle size distribution analyses. Notably, the proportion of fine particles smaller than 2.5 µm (PM_2.5) decreased from 70.25% to 18.63% after plasma treatment, indicating improved capture potential in the downstream electrostatic precipitator (ESP). Overall, microwave-assisted plasma provides efficient SO₂ removal and enhanced particulate capture, offering a compact and potentially waste-free alternative to conventional systems. Full article

To address the challenges of combustion stability and pollutant control during biomass co-combustion in coal-fired boilers under deep peak regulation, a numerical simulation study was conducted on a 660 MW front-and-rear wall opposed-fired pulverized coal boiler using computational fluid dynamics (CFD) technology. First, the reliability of the numerical model was validated under the Boiler Maximum Continuous Rating (BMCR) condition by comparing the simulated results of furnace outlet temperature and NO concentration with on-site operational data, with relative errors of 1.2% and 1.9%, respectively, both within the acceptable range of 5%. Subsequently, the effects of different biomass co-combustion ratios (0%, 5%, 10%, 15%, 20%) and injection positions (primary air nozzles of lower, middle, and upper burners) on the in-furnace velocity field, temperature field, component distribution (O₂, CO, CO₂), and NO emissions were systematically analyzed. The results indicate that increasing the biomass co-combustion ratio does not alter the overall variation trend of flue gas components but significantly affects their concentrations: the O₂ content at the furnace outlet decreases gradually, while the CO₂ content increases, and the NO emission concentration decreases continuously. A 20% co-combustion ratio is identified as the optimal choice, balancing combustion efficiency and NO reduction. Regarding injection positions, biomass injected at the middle burner’s primary air nozzle achieves the best NO control effect, reducing NO emissions by 22% compared to pure coal combustion. This is attributed to the formation of a stable reducing atmosphere in the main combustion zone, which facilitates NO_x reduction. The research findings provide valuable theoretical references and technical support for the parameter optimization and safe, low-emission operation of biomass co-combustion in large-scale coal-fired boilers. Full article

This study systematically compares thermal power direct carbon emission data quality control systems in China, the EU, and the U.S., quantifying differences and proposing optimization strategies. Core results: (1) Regulatory frameworks: The EU’s “Directive-Regulation-Standard” system controls data uncertainty ≤ ±3%; the U.S. “Clean Air Act+40 CFR Parts 75/98” framework achieves Continuous Emission Monitoring System (CEMS) median accuracy ~2% but has regional gaps; China’s 2024 legalization of CEMS data leaves a 32% eastern–western installation gap (~90% vs.~58%). (2) Technical paths: The EU mandates CEMS for units > 20 MW (65% ultrasonic flowmeters); the U.S. uses CEMS for coal-fired (error ≤ 1%) and accounting for gas-fired units; China’s 70% S-type Pitot tubes have 17% error in complex flow fields, while pilot multi-channel ultrasonic flowmeters reach ±1.5%. (3) Mechanisms: The EU’s QAL1-QAL3+AST cuts uncertainty by 40–60%; the U.S. NIST calibration limits cross-plant deviation ≤ 1.5%; China’s big data boosts anomaly identification by 72% but lacks full-process control. (4) China-specific proposals: Mandate CEMS for units > 300 MW, build 3–5 national flue gas platforms by 2026, and offer 60% western equipment subsidies, supporting carbon data quality improvement and international mutual recognition. Full article

The co-firing of coal and refuse-derived fuel (RDF) from municipal solid waste recycling is gaining support in countries in which energy production is based on solid fuels. It is the result of the rising priority given to renewable energy sources, the circular economy, and effective waste management through sorting, recycling, and thermal conversion. Despite the increasing efficiency of recycling and the ever-lower quantities of waste delivered to waste dumps, the problem of the residual fraction remains unsolved. The portion of mixed municipal waste that cannot be recycled exhibits a high energy value. For this reason, it should be neither stored nor burnt in household boiler rooms, as doing so would constitute an environmental hazard. However, the waste can be used as an additive to fine coal in power boilers, provided that they are equipped with flue gas monitoring and purification systems. Tests involving proportionally prepared compositions of fine coal and refuse-derived fuel burnt in a laboratory boiler revealed a major variability in the flue gas parameters (physicochemical), depending on the applied proportions of the individual components. For instance, when burning a composition of 50% fine coal and 50% refuse-derived fuel, a reduction in CO₂ emissions by about 12% was noted compared with that when burning fine coal exclusively. Furthermore, when burning refuse-derived fuel, an addition of 20% fine coal is enough to produce a 2.8% reduction in CO emission. Meanwhile, a composition of 80% fine coal and 20% refuse-derived fuel would reduce the emissions by 393 ppm. During the measurements, it was also noted that most of the measured parameters indicated a decrease in individual gas contents relative to the emissions obtained when burning fine coal or refuse-derived fuel exclusively. These relationships can be applied to prepare fuel compositions based on refuse-derived fuel and fine coal, depending on the power and flue gas purification capabilities of individual cogeneration systems. Full article

Coal-fired power plants, as the largest source of human-made mercury emissions, often lack specialized mercury emission control devices. Therefore, developing cost-effective adsorbents and studying their regeneration properties are highly important for mercury removal from flue gas. In this study, the regeneration efficiency and stability of a composite material made from polymetallic Fe/Cu-doped modified biochar combined with the MOF material Cu-BTC were investigated. Based on the analysis of microscopic characteristics, the molecular structure of the regenerated composites was modeled, and the adsorption and regeneration process of Hg⁰ on their surface was simulated using density functional theory. This helped uncover the underlying mechanisms of mercury removal and regeneration. The results indicate that the optimal regeneration temperature and atmosphere were 350 °C and 5% O₂, resulting in the formation of a derived carbon material. The regeneration efficiency reached 92% of that of the original mercury adsorption capacity, and over 80% efficiency was maintained after 10 regeneration cycles. The regenerated samples adsorbed Hg⁰ through the combined action of surface metal oxides, the metal element Cu, and oxygen-containing functional groups. Full article

The sulfur dioxide removal in thermoelectric plants occurs through flue gas desulfurization (FGD), which produces waste that needs to be correctly disposed of. This exploratory research aims to characterize waste obtained from an FGD plant in Candiota, Rio Grande do Sul, Brazil, and evaluate its potential as alternative mineral source in obtaining alkali-activated materials (AAM). The dried and processed waste was called FGD-D, and AAM was produced by mixing FGD-D with sodium-based alkaline activating solutions. The amounts of FGD at formulations ranged from 31.6 (F1) to 38.9 wt.% (F4), and the use of metakaolin was not necessary. The results show that the chemical composition of FGD-D is composed mainly of calcium oxides (38 wt.%), sulfur (22 wt.%), and silica (19 wt.%). Crystalline phases and a high amorphous fraction were identified in the residual samples. The use of FGD-D in AAM proved to be an alternative mineral source, showing an exothermic reaction with subsequent rapid hardening and increased compressive strength values ranged from 7.7 ± 1.3 Mpa for F1 to 14.4 ± 1.8 Mpa for F4 at seven days. The results demonstrate the potential of using FGD-D in AAM formulations, opening positive perspectives for a more sustainable destination for these residual materials. Full article

In industrial production, flue gas heat exchangers are often affected by the low-temperature condensation of industrial flue gas due to the influence of the working environment, resulting in serious ash deposition and corrosion. In order to solve this problem, in this study, we developed an ash deposition and corrosion monitoring system to compare the ash deposition prevention performance and corrosion resistance of different materials, as well as its influence on the heat transfer performance of different materials in the same environment. The following coatings were selected for the experiment (values in parentheses are the concentrations of the added compounds): ND, Q235, 316L, Ni-Cu (0.4 g/L)-P, Ni-P-SiO₂ (40 g/L), Ni-Cu (0.4 g/L)-P-SiO₂ (20 g/L), Ni-Cu (0.4 g/L)-P-SiO₂ (40 g/L), and Ni-Cu (0.4 g/L)-P-SiO₂ (60 g/L). The results show that the Ni-Cu (0.4 g/L)-P-SiO₂ (40 g/L) coating has excellent corrosion resistance, while the Ni-Cu (0.4 g/L)-P-SiO₂ (60 g/L) coating shows excellent antifouling performance. Through the comparative analysis of polarization curves, impedance spectra, and coupled corrosion experiments, the test materials were ranked as follows based on their corrosion resistance: 316L > Ni-Cu-P-SiO₂ (40 g/L) > Ni-Cu-P-SiO₂ (20 g/L) > Ni-P-SiO₂ > Ni-Cu-P-SiO₂ (60 g/L) > Ni-Cu-P > ND > Q235. It was also demonstrated that the new coated pipes were able to reduce the exhaust temperature below the dew point and maximize the recovery of energy from the exhaust gas. The acid–ash coupling mechanism of the coating in the flue gas environment was further analyzed, and an acid–ash coupling model based on Cu and SiO₂ is proposed. This model analyzes the effect of the coating under the acid–ash coupling mechanism. Using coated tubes in heat exchangers helps to recover waste heat from coal-fired boilers, enhance heat exchange efficiency, extend the service life of heat exchangers, and reduce costs. Full article

The efficient removal of elemental mercury (Hg⁰) from coal-fired flue gas is a critical challenge in environmental governance. This study proposes utilizing waste fluid catalytic cracking catalyst (WFCC) as the potential support for Hg⁰ catalytic oxidation. After activation (AFCC) via calcination decarbonization, a composite support (AFCC-PG) was fabricated using palygorskite (PG) as a binder. Subsequently, VO_x was loaded onto the support to form the VO_x/AFCC-PG catalyst for Hg⁰ removal. Experimental results demonstrate that the VO_x/AFCC-PG catalyst achieves >95% Hg⁰ removal efficiency under simulated flue gas conditions (150 °C, GHSV = 6000 h⁻¹) while maintaining excellent stability over 60 h. Furthermore, Hg-TPD and XPS analyses indicate that the synergistic lattice oxygen oxidation–adsorption established between VO_x and the AFCC-PG plays a key role in efficient Hg⁰ removal. This study proposes a cost-effective strategy for both the resource utilization of waste catalysts and the control of mercury pollution in coal-fired flue gas. Full article

To compensate for the instability of renewable energy sources during China’s energy transition, large thermal power plants must provide critical operational flexibility, primarily through deep peaking. To investigate the combustion performance and wear and tear of a 600 MW pulverized coal boiler under deep peaking, the gas–solid flow characteristics and distributions of flue gas temperature, wall heat flux, and wall wear rate in a 600 MW tangentially fired pulverized coal boiler under variable loads (353 MW, 431 MW, 519 MW, and 600 MW) are investigated in this study employing computational fluid dynamics numerical simulation method. Results demonstrate that increasing the boiler load significantly amplifies gas velocity, wall heat flux, and wall wear rate. The maximum gas velocity in the furnace rises from 20.9 m·s⁻¹ (353 MW) to 37.6 m·s⁻¹ (600 MW), with tangential airflow forming a low-velocity central zone and high-velocity peripheral regions. Meanwhile, the tangential circle diameter expands by ~15% as the load increases. The flue gas temperature distribution exhibits a “low-high-low” profile along the furnace height. As the load increases from 353 MW to 600 MW, the primary combustion zone’s peak temperature rises from 1750 K to 1980 K, accompanied by a ~30% expansion in the coverage area of the high-temperature zone. Wall heat flux correlates strongly with temperature distribution, peaking at 2.29 × 10⁵ W·m⁻² (353 MW) and 2.75 × 10⁵ W·m⁻² (600 MW) in the primary combustion zone. Wear analysis highlights severe erosion in the economizer due to elevated flue gas velocities, with wall wear rates escalating from 3.29 × 10⁻⁷ kg·m⁻²·s⁻¹ (353 MW) to 1.23 × 10⁻⁵ kg·m⁻²·s⁻¹ (600 MW), representing a 40-fold increase under full-load conditions. Mitigation strategies, including ash removal optimization, anti-wear covers, and thermal spray coatings, are proposed to enhance operational safety. This work provides critical insights into flow field optimization and wear management for large-scale coal-fired boilers under flexible load operation. Full article

This study investigates the emission characteristics and environmental impacts of pollutants from bagasse-fired biomass boilers through the integrated field monitoring of two sugarcane processing plants in Guangxi, China. Comprehensive analyses of flue gas components, including PM_2.5, NOx, CO, heavy metals, VOCs, HCl, and HF, revealed distinct physicochemical and emission profiles. Bagasse exhibited lower C, H, and S content but higher moisture (47~53%) and O (24~30%) levels compared to coal, reducing the calorific values (8.93~11.89 MJ/kg). Particulate matter removal efficiency exceeded 98% (water film dust collector) and 95% (bag filter), while NOx removal varied (10~56%) due to water solubility differences. Heavy metals (Cu, Cr, Ni, Pb) in fuel migrated to fly ash and flue gas, with Hg and Mn showing notable volatility. VOC speciation identified oxygenated compounds (OVOCs, 87%) as dominant in small boilers, while aromatics (60%) and alkenes (34%) prevailed in larger systems. Ozone formation potential (OFP: 3.34~4.39 mg/m³) and secondary organic aerosol formation potential (SOAFP: 0.33~1.9 mg/m³) highlighted aromatic hydrocarbons (e.g., benzene, xylene) as critical contributors to secondary pollution. Despite compliance with current emission standards (e.g., PM < 20 mg/m³), elevated CO (>1000 mg/m³) in large boilers indicated incomplete combustion. This work underscores the necessity of tailored control strategies for OVOCs, aromatics, and heavy metals, advocating for stricter fuel quality and clear emission standards to align biomass energy utilization with environmental sustainability goals. Full article