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Objective The aim is to study the application of calcium-based dry desulfurizer in the field of flue gas desulfurization, and give full play to the advantages of low cost, good desulfurization performance and environmental friendliness of calcium-based desulfurizer, so as to achieve the up-to-standard emission of SO2 in flue gas. Methods The physical and chemical properties of the prepared calcium-based desulfurizer were characterized by XRD, BET, FTIR and XPS. Additionally, simulating sulfur-containing waste gas, the effects of SO2 content, reaction temperature, O2 content and volume space velocity on the desulfurization performance of calciumbased dry desulfurizer were investigated by a fixed bed reactor. Results The prepared calcium-based desulfurizer demonstrated effective desulfurization, and its optimum operating temperature range was 220-300 ℃, which was suitable for the case that the volume fraction of SO2 in flue gas did not exceed 0.4%. The increase of O2 content produced new active sites for adsorption, which could promote desulfurization process. When the volume space velocity was in the range of 500-2 000 h−1, the sulfur capacity did not change much. Conclusions The application of calcium-based dry desulfurizer in the field of flue gas desulfurization has high efficiency and stability, which can provide reference for its wide application in the industrial field. [ABSTRACT FROM AUTHOR]

To eliminate the flow dead zone and homogenize the asymmetric flow field of a grate furnace, spirally twisted tape inserts (STTIs) with a pitch ratio of 1.5 were installed in the vertical flues of an SCL1000-13.5/450 grate boiler. The arrangement schemes found to be present inside the chosen 1000 t/d grate furnace, determined using the orthogonal experimental method, included separate installation in chamber II, separate placement in chamber III, and simultaneous arrangement in both chamber II and chamber III. The effects of row spacing H, column spacing W, and mounting angle φ were investigated by means of the practicable and feasible numerical simulation method. With a focus on the uniformity degree of the flue gas, the results showed that temperature distribution is directly correlated with the velocity field. When it comes to the uniformity of the flow field, the exclusive use of STTIs in chamber II was better than that in chamber III. Under the optimal combination scheme of STTIs in both chamber II and chamber III (scheme N323), the exhaust gas temperature reached the minimum value and the uniformity index of temperature increased to the range of 0.994~0.997. The findings in this work could provide a reference for the optimization of the flow field in a grate furnace. [ABSTRACT FROM AUTHOR]

An improved method was developed to calculate direct emissions from seven municipal solid waste incineration plants by adjusting the physical compositions of waste by invoking the proportion of co-incinerated waste and the bottom ash yield. The fossil carbon fractions of the waste components were determined by carbon-14 (14C) testing. Based on the improved method, direct emissions were in the range of 222–610 kg CO2-eq/t waste, corresponding to reductions of 3.4–221 kg CO2-eq/t waste compared with the method without waste composition adjustment. The 14C contents of the flue gas before and after gas cleaning were tested to validate the improved method, and indicated fossil CO2 emissions of 249–446 and 233–405 kg CO2-eq/t waste, respectively. The direct emissions obtained by the improved method were closer to the results of 14C testing, due to more accurate estimations of the actual waste composition. The method was further combined with a life cycle analysis of the waste incineration process, obtaining total carbon emissions in the range from –33.2 to 483 kg CO2-eq/t waste. The findings provide a new means of accurately calculating carbon emissions from waste incineration. Highlights: • Co-incinerated waste and bottom ash yield were used to adjust waste composition. • Fossil carbon contents of the waste and flue gas were determined by 14C testing. • The improved method reduced fossil CO2 emissions by 3.4–221 kg CO2-eq/t waste. • Life cycle GHG emissions from waste incineration was –33.2–483 kg CO2-eq/t waste. [ABSTRACT FROM AUTHOR]

Due to its good corrosion resistance and high rigidity, fluoroplastic steel heat exchangers have become one of the main feasible solutions to the problem of flue gas waste heat recovery. Therefore, a heat transfer performance test of a fluoroplastic steel heat exchanger was carried out, and a new heat transfer correlation (Nu = 0.11Re0.72Pr0.36, 1900 < Re < 4100, Pr ≈ 0.8) of a fluid transverse tube bank suitable for smooth fluoroplastic surfaces was proposed. Comparing the results of the proposed correlation and the Zhukauskas correlation, the calculation discrepancy was decreased when using the proposed correlation, and the average discrepancy dropped from 16.8% to 3.3%. As the thickness of the fluoroplastic film was reduced, the gap between the two correlations widened. Thus, the Zhukauskas correlation was not applicable to fluoroplastic steel heat exchangers with a thin fluoroplastic film. However, the deviation between the two correlations decreased as the condensing heat transfer area increased. For the fluoroplastic steel heat exchanger with a large condensation heat transfer area, the Zhukauskas correlation could still be utilized. It was interesting to observe that the deviation between the two correlations was reduced when only flue gas condensation was present, but it showed an increasing trend with the increase in condensation intensity. [ABSTRACT FROM AUTHOR]

A flue gas condenser (FGC) system recovers heat from exhaust flue gases in energy production and chemical plants, reducing air pollution due to dust, SOx, and HCl. An FGC system is divided into indirect contact condenser (ICC) and direct contact condenser (DCC) types. In an ICC, the exhaust gases do not mix with the working fluid, and a water film is formed during flue gas condensation for partial SOx removal. In a DCC, direct mixing of the exhaust flue gas with the cooling fluid (mainly water) occurs, with simultaneous absorption of SOx. In this study, we investigated the SO2 removal efficiency and heat recovery of an ICC, a DCC, and a DCC–ICC hybrid system, and compared the results of the hybrid system with those obtained for a single DCC type at the same liquid-to-gas (L/G) ratio. The SO2 removal characteristics of the hybrid system were examined based on the L/G ratio and absorbent-to-SO2 molar ratio. In the reference ICC-type FGC system, the exit temperature of the mixed gas was 28 °C, with the condensed water ratio and heat recovery efficiency being 80.9% and 93.4%, respectively. At an L/G ratio of 1.5–3.5, the SO2 removal efficiency of a single DCC was 31.5–65.9%, whereas that of the hybrid FGC system (with packing material) increased from 47.1% to 72.3%, which further increased to ~90% upon the addition of NaOH at a molar ratio of 0.7 and an L/G ratio of 1.5. [ABSTRACT FROM AUTHOR]

Torrefaction is an effective method to improve the quality of biomass feedstocks for a subsequent thermal conversion process. Torrefaction has been widely developed for biomass upgrading in terms of increasing bulk and energy densities, reducing water and oxygen contents, and improving hydrophobic properties, which are favorable for transportation and storage. Moreover, the torrefied biomass can be easily ground to even particle sizes, which favor the downstream thermochemical conversion process such as gasification. This paper reports on the progress in the dry and wet torrefaction of biomass sources. Key findings and challenges of torrefied biomass gasification are highlighted as well. In general, the properties of biomass feedstocks can be improved by the torrefaction process. Torrefaction for biomass gasification can improve the quality of syngas. In particular, gasification of torrefied biomass involves a merit of volatile matter (tar precursor) removal prior to the gasification process. The properties of torrefied biomass are significantly affected by the torrefaction conditions mainly including atmosphere, temperature, and pressure. The presence of an appropriate amount of oxygen gas leads to a superior performance for biomass torrefaction. The oxygen-containing gas and the waste heat from industrial flue gas can be utilized to reduce the operating cost, thus making the biomass torrefaction pretreatment more commercially feasible. [ABSTRACT FROM AUTHOR]

Water supply challenges are caused by population growth, industrialization, as well as the scarcity of freshwater resources. Low‐grade waste heat‐driven seawater desalination technologies may improve the water‐energy nexus issues of desalination systems by different configurations. The data envelopment analysis is used to determine the best final decision to achieve a better comparison of different parameters. The optimal configuration of low‐grade waste heat driven seawater desalination is studied using flue gas waste heat in heat recovery boilers of an industrial oil refinery. Nine different types of multistage flash and multi‐effect distillation (MED) desalination plants have been considered. The results show that the multistage flash brine recirculation may produce more desalinated water while the multi‐effect distillation with three stages (3‐stage MED) has the best payback period. Using 3‐stage MED with a production of approximately 19,630 kg/h of water from 5.3 MW exhaust gas is more suitable for this design. Thus, the proposed strategy guides us toward the best decisions to configure low‐grade waste heat‐driven desalination plants for better design considering rigorous simulations for the plants. Moreover, this framework enables us to consider different criteria of technical, economic, and environmental issues for optimal configuration. [ABSTRACT FROM AUTHOR]

This study aims to explore the use of Dielectric Barrier Discharge (DBD) technology for the joint treatment of methane (CH4) and nitrogen oxide (NO) in the exhaust of Liquid Natural Gas (LNG) engines during cold starts and at mid to low loads when the exhaust temperature is below 500 °C. Through experiment and numerical simulation, the effect of discharge power on the removal efficiency of CH4 and NO in the exhaust of LNG engines was investigated under the condition of simulated flue gas temperature at 438 °C. A plasma chemical model suitable for analyzing the mixture of N2/O2/H2O/CH4/NO in the exhaust gases of LNG engines was constructed and validated. The study found that the conversion efficiency of CH4 and NO exhibits different trends with the increase of discharge power, and CH4 tends to be oxidized to CO under plasma conditions. Key reaction pathways for the DBD treatment of CH4, NO, CO, and NO2 were identified, and an important chemical reaction pathway with the potential for the joint treatment of CH4 and NO was found: CH3O2 + NO → CH3O + NO2. Additionally, the crucial pathways for the stable conversion of NO to NO2 were identified: O + NO + N2 → NO2 + N2 and NO + O3 → NO2 + O2, providing forward-looking theoretical guidance for subsequent research on plasma-facilitated selective catalytic reduction of NOx by CH4. [ABSTRACT FROM AUTHOR]

This paper focuses on the combustion of hydrogen in boilers, as it appears to be a more effective method than using fuel cells for heating purposes due to higher boiler efficiency. One of the main disadvantages of hydrogen combustion in air is NO x formation. Therefore, the authors decided to introduce corona discharge as an innovative technique to clean hydrogen flue gas by effectively reducing NO x levels. The method involves generating positive plasma at atmospheric pressure by applying up to a 23 kV voltage difference between rod and ring-shaped electrodes. Experimental studies have shown that corona discharge can significantly lower the concentrations of NO and NO x in exhaust gases. The maximum DeNO x level was found to be 32.3%, while the plasma generator uses 17.5% of the power contained in burned hydrogen. The findings suggest that this technology holds potential for application in industrial hydrogen combustion systems, offering an environmentally friendly alternative to conventional NO x reduction methods. [Display omitted] • Corona discharge is promising approach for cleaning hydrogen flue gas from NO x. • The level of NO x removal depends on their concentration. • After plasma treatment, the level of NO decreases while NO 2 increases. • The maximum investigated level of DeNO x was 32.3%. [ABSTRACT FROM AUTHOR]

The study performs energy and exergy analyses for each component such as boilers, buildings, distribution networks and heat exchangers of a new generation district heating system. Energy and exergy efficiencies are compared for all system components, and energy and exergy losses are presented using Sankey and Grassman diagrams. Three flue gas condensers with finned bundles are designed for different capacities of boilers that intend to recover water and heat from the waste flue gas in the district heating system due to high flue gas energy losses. Colburn-Hougen and one-dimensional finite difference methods are used to design the flue gas condensers with the MATLAB program. The exergy analysis showed that the exergy input to the system is lost by 4.52% from the distribution networks, 4.15% from all buildings and 2.18% from the flue gas. In the system, the energy and exergy efficiencies of the boilers are calculated to be 87.23% and 17.32%, respectively, and the heat loss from the flue gas is found to be 12%. The design results show that the values of mass convection coefficient (km) for all flue gas condensers decrease from 0.0706 at the inlet condensation zone to 0.0354 towards the outlet. The total condensation rate and condensation efficiency are found to be 86 kg/h and 60%, respectively, for the 2500 kW boiler. [ABSTRACT FROM AUTHOR]

This paper conducts an energy efficiency assessment of the steam system in a cigarette factory. By analyzing different heat-consuming units, a heat utilization model is established to calculate the thermal efficiency and exergy efficiency of each unit and to identify factors affecting the efficiency of units with low heat utilization. The results indicate that the exergy efficiency of the steam system is only 7.13%, with significant exergy losses. Among these, the exergy efficiency of the production system is 4.20%, followed by the exergy efficiency of the heat source at 34.80%. Based on these findings, an energy-saving retrofit plan utilizing flue gas waste heat to provide hot water is proposed. This approach can improve boiler efficiency by 11.5%, demonstrating effective results. [ABSTRACT FROM AUTHOR]

Flue gas emissions are the waste gases produced during the combustion of fuel in industrial processes, which are released into the atmosphere. These identical processes also produce a significant amount of wastewater that is released into the environment. The current investigation aims to assess the viability of simultaneously mitigating flue gas emissions and remediating wastewater in a bubble column bioreactor utilizing bacterial consortia. A comparative study was done on different growth media prepared using wastewater. The highest biomass yield of 3.66 g L−1 was achieved with the highest removal efficiencies of 89.80, 77.30, and 80.77% for CO2, SO2, and NO, respectively. The study investigated pH, salinity, dissolved oxygen, and biochemical and chemical oxygen demand to assess their influence on the process. The nutrient balance validated the ability of bacteria to utilize compounds in flue gas and wastewater for biomass production. The Fourier Transform–Infrared Spectrometry (FT–IR) and Gas Chromatography–Mass Spectrometry (GC–MS) analyses detected commercial-use long-chain hydrocarbons, fatty alcohols, carboxylic acids, and esters in the biomass samples. The nuclear magnetic resonance (NMR) metabolomics detected the potential mechanism pathways followed by the bacteria for mitigation. The techno-economic assessment determined a feasible total capital investment of 245.74$ to operate the reactor for 288 h. The bioreactor's practicability was determined by mass transfer and thermodynamics assessment. Therefore, this study introduces a novel approach that utilizes bacteria and a bioreactor to mitigate flue gas and remediate wastewater. [ABSTRACT FROM AUTHOR]

The development of electrocatalysts that convert CO2 and N2 in flue gas to directly usable urea does not only explore the hidden value of exhaust gas but also alleviates the global environmental issues caused by excessive CO2 emissions; yet, related research studies are still in their infancy. Herein, multi-porous Cu–W18O49@ZIF-8, composed of ultra-small nanosized ZIF-8 on Cu-doped W18O49 nanowires, was fabricated as a urea-generation electrocatalyst in flue gas. It exhibits an appealing Faraday efficiency of urea up to 16.1% at −0.9 V (vs. RHE) and an outstanding yield of 1.33 mmol g−1 h−1 at −1.0 V (vs. RHE) under the flue gas atmosphere. The catalytic performance was maintained for a wide range of N2 : CO2 ratios. Theoretical calculations indicate that the doped copper regulates the electron density around the adjacent W–W, which facilitates N2 adsorption, partly suppresses the HER side reaction, and decreases the ΔG of the following multi-step hydrogenation after *CO insertion until urea production. [ABSTRACT FROM AUTHOR]

The quest for effective technologies to reduce SO2 pollution is crucial due to its adverse effects on the environment and human health. Markedly, removing a ppm level of SO2 from CO2‐containing waste gas is a persistent challenge, and current technologies suffer from low SO2/CO2 selectivity and energy‐intensive regeneration processes. Here using the molecular building blocks approach and theoretical calculation, we constructed two porous organic polymers (POPs) encompassing pocket‐like structures with exposed imidazole groups, promoting preferential interactions with SO2 from CO2‐containing streams. Markedly, the evaluated POPs offer outstanding SO2/CO2 selectivity, high SO2 capacity, and an easy regeneration process, making it one of the best materials for SO2 capture. To gain better structural insights into the notable SO2 selectivity of the POPs, we used dynamic nuclear polarization NMR spectroscopy (DNP) and molecular modelling to probe the interactions between SO2 and POP adsorbents. The newly developed materials are poised to offer an energy‐efficient and environment‐friendly SO2 separation process while we are obliged to use fossil fuels for our energy needs. [ABSTRACT FROM AUTHOR]

To explore the effects of waste heat (50–170°C) from steel plant flue gas on the column photobioreactor algal liquid temperature for microalgal production, a flue gas‐microalgal liquid heat transfer model was developed that simulated the microalgal growth environment for flue‐gas carbon dioxide (CO2) fixation. The simulation results showed that the influence of high‐temperature flue gas weakened with the increasing microalgal liquid temperature due to enhanced evaporation and heat dissipation. Increasing the flue gas temperature and aeration rate resulted in a higher microalgal liquid temperature up to a maximum increase of 4.16°C at an ambient temperature of 25°C, an aeration rate of 2 L/min, and a flue gas temperature of 170°C. In an experiment on the effect of incubation temperature on the growth rate of microalgae, at an optimal temperature of 35°C, the Chlorella sp. PY‐ZU1 growth rate exhibited a remarkable increase of 104.7% compared to that at 42.5°C. Therefore, modulating the flue gas conditions can significantly increase the microalgal growth rate for CO2 fixation, making it a promising approach to increase biomass production for efficient carbon utilization. [ABSTRACT FROM AUTHOR]

Recently, supercritical CO2 (S-CO2) has been extensively applied for the recovery of waste heat from flue gas. Although various cycle configurations have been proposed, existing studies predominantly focus on the steady analysis and optimization of different S-CO2 structures under design conditions, and there is a noticeable deficiency in off-design research, especially for the innovative S-CO2 cycles. Thus, in this work aimed at the proposed novel S-CO2 power cycle, off-design characteristics and corresponding control strategies are investigated for the waste heat recovery. Based on the design parameters of the S-CO2 cycle, structural dimensions of printed circuit heat exchangers (PCHEs) and shell-and-tube heat exchangers are determined, and design values of turbines and compressors are specified. On this basis, off-design models for these key components are formulated. By manipulating variables such as cooling water inlet temperature, cooling water mass flow rate, flue gas inlet temperature and flue gas mass flow rate, cycle performances of the system are analyzed under off-design conditions. The simulation results show that when the inlet temperature and the mass flow rate of cooling water vary separately, the thermal efficiency both can reach the maximum value of 28.43% at the design point. For the changes in heat source parameters, the optimum point is slightly deviated from the design condition. Amidst the fluctuations in flue gas inlet temperature, the thermal efficiency optimizes to a peak of 28.56% at 530 °C. In the case of variation in the flue gas mass flow rate, the highest thermal efficiency 28.75% can be obtained. Furthermore, to maintain the efficient and stable operation of the S-CO2 power cycle, the corresponding control strategy of the cooling water mass flow rate is proposed for the cooling water inlet temperature variation. Generally, when the inlet temperature of cooling water increases from 23 °C to 27 °C, the cooling water mass flow should increase from 82.3% to 132.7% of the design value to keep the system running as much as possible at design conditions. [ABSTRACT FROM AUTHOR]

As an indispensable component of coal-fired power plants, boilers play a crucial role in converting water into high-pressure steam. The oxygen content in the flue gas is a crucial indicator, which indicates the state of combustion within the boiler. The oxygen content not only affects the thermal efficiency of the boiler and the energy utilization of the generator unit, but also has adverse impacts on the environment. Therefore, accurate measurement of the flue gas's oxygen content is of paramount importance in enhancing the energy utilization efficiency of coal-fired power plants and reducing the emissions of waste gas and pollutants. This study proposes a prediction model for the oxygen content in the flue gas that combines the whale optimization algorithm (WOA) and long short-term memory (LSTM) networks. Among them, the whale optimization algorithm (WOA) was used to optimize the learning rate, the number of hidden layers, and the regularization coefficients of the long short-term memory (LSTM). The data used in this study were obtained from a 350 MW power generation unit in a coal-fired power plant to validate the practicality and effectiveness of the proposed hybrid model. The simulation results demonstrated that the whale optimization algorithm–long short-term memory (WOA-LSTM) model achieved an MAE of 0.16493, an RMSE of 0.12712, an MAPE of 2.2254%, and an R 2 value of 0.98664. The whale optimization algorithm–long short-term memory (WOA-LSTM) model demonstrated enhancements in accuracy compared with the least squares support vector machine (LSSVM), long short-term memory (LSTM), particle swarm optimization–least squares support vector machine (PSO-LSSVM), and particle swarm optimization–long short-term memory (PSO-LSTM), with improvements of 4.93%, 4.03%, 1.35%, and 0.49%, respectively. These results indicated that the proposed soft sensor model exhibited more accurate performance, which can meet practical requirements of coal-fired power plants. [ABSTRACT FROM AUTHOR]

Gas turbine combustors are often subjected to combustion instabilities because of variability of operating conditions, affecting components, and altering exhaust emissions. Herein, the analysis focuses on simulating numerically the non‐premixed combustion as unsteady flamelet combustion and detailed kinetic mechanism. The goal is analyzing exhaust gases under unsteady inlet airflow conditions to define operation guidelines. The numerical approach is validated using data from the literature for nonperturbed cases. Three periodical perturbations of different amplitude show differences with the nonperturbed case. Besides emission of exhaust gases, the temperature field is sensitive to airflow inlet conditions. According to the simulation results, a strong dependence of temperature and pressure in primary and dilution zones of combustor exists on the inlet air pressure condition. Emissions of flue gases like CO and NOx respond to combustor thermal behavior showing high sensitivity to inlet air pressure as well. Results indicate that moderate pressure oscillations may derive into flashback effects. [ABSTRACT FROM AUTHOR]

An electrostatic precipitator (ESP), which filters the fine particles present in the exhaust gas generated from a power plant, has a better particle-collection efficiency when there exists a uniform flow in the dust collection chamber. However, most former investigations examined the flow distribution via numerical approaches that modeled the perforated plates within the inlet diffuser as porous media, which have not been adequately validated. Therefore, the aim of this study was to examine the performance of the porous media model for simulating the flow through perforated plates of an ESP diffuser by numerical simulation and experiment. Simulation results using the porous media model were compared with those obtained with a fully resolved mesh precisely describing the complete geometry of the entire perforated plate. The results obtained with both these methods were consistent with experimental results obtained upstream of the inlet diffuser, but the porous media model could not accurately simulate the flow distribution across the perforated plates. Overall, this model failed to predict the deflection of incoming flow on the solid bars and the wakes behind the bars, and could not reflect the vena contracta phenomenon occurring within the holes of the plate. As a result, the simulated flow distribution at the entrance of the main dust-collection chamber differed from that observed in the experiment, which resulted in poor prediction of the flow field inside the chamber. Therefore, this porous media model requires further improvement for wide-scale adoption in industrial practical applications, e.g., ESP for flue gas treatment in power plants. • Examination of the porous media model for simulating flow through perforated plates. • Experimental validation provided by particle image velocimetry (PIV) measurements. • Results compared with simulations fully resolving the perforations in the plates. • Porous media model cannot capture detailed flow physics such as the vena contracta. • The model inaccurately overestimates the streamwise directionality of the flow. [ABSTRACT FROM AUTHOR]

In this study, we have designed and developed an implantable thermoelectric generator (TEG) module tailored for large-scale flue gas waste heat recovery. We also have established a test stand to simulate diverse operational conditions, and systematically examined the influence of different operating conditions, including flue gas temperature, flue gas velocity, and cooling water temperature, on the electrical performance of the TEG module. When the flue gas temperature is 139 °C, the flue gas flow rate is 3.4 m/s, and the cooling water temperature is 20 °C, the TEG module operates at its peak performance. It achieves an open-circuit voltage of 856.3 V and an output power of 150.58 W. Furthermore, the TEG module demonstrates a notable power generation capacity of 3.86 kW/m3 and a waste heat recovery capacity of 135.85 kW/m3. The results prove the TEG module as an effective solution for large-scale flue gas waste heat recovery in industrial settings, contributing to sustainable energy practices. This study supports the application of thermoelectric power generation in the industrial sector, offering significant potential for advancements in energy efficiency. [ABSTRACT FROM AUTHOR]

The conversion furnace of the hydrogen production unit uses high-pressure fuel gas from the factory pipeline network as fuel, after cutting out the PSA exhaust gas during shutdown stage, and before cutting in the PSA exhaust gas during start-up stage. There is a problem of high oxygen content and excessive NOx converted concentration in the discharged flue gas. Therefor, the industrial application and optimization of the non-ammonia bio-based non-catalyst denitration reducing agent skid-mounted technology are carried out during the shutdown and start-up process. The results show that after adding the agent in an atmospherea with a smoke temperature of 450 ~850°C, the actual measured value of NOx is reduced to ultra-low level, which solves the problem of high-fold oxygen multiple, and achieves full-time compliant external discharge of NOx in the discharged flue gas; during the shutdown process, the daily average value of NOx converted concentration decreases from 279 mg/m to 129 mg/m (meeting the index requirements of below 180 mg/m³), while during the start-up process, the daily average value of NOx converted concentration decreases from 502 mg/m to 104 mg/m³. [ABSTRACT FROM AUTHOR]

This article analyzes the effect of modifications of injector opening pressure on the operating values of a compression ignition engine, including the temperature of the exhaust gas. A program of experimental investigation is described, considering the available test stand and measurement capabilities. The structure of the test stand on which the experimental measurements were conducted is presented. The method of introducing real modifications of injector opening pressure to the existing test engine was characterized. It was proposed to use F statistic of Fisher-Snedecor (F-S) distribution to evaluate the importance of the impact of modifications of injector opening pressure on the specific enthalpy of the flue gas flow. Qualitative and statistical studies of the results achieved from the measurements were carried out. The specific enthalpy of the exhaust gas for a single cycle of the compression ignition engine, determined from the course of rapidly variable flue gas temperature, was analyzed. The results of these studies are presented and the usable adoption of this type of assessment in parametric diagnosing of compression ignition engines is discussed. [ABSTRACT FROM AUTHOR]

Environmental impact assessment of energy generation processes is essential to evaluate their contributions toward the global carbon footprint. Even though hydrogen is a non-carbonaceous energy source, the pathways undertaken for its production can have harmful environmental implications. Thus, this study focuses on investigating the exergoenvironmental performances of the copper-chlorine, iron-chlorine, and magnesium-chlorine thermochemical hydrogen generation processes. This study also performs a comparative exergoenvironmental analysis of the three processes. The performances of the various processes are examined based on of the environmental impact rates of exergy destruction, component-related environmental impact rates, cumulative environmental impact rates, and exergoenvironmental factors. The global warming potentials of the thermochemical cycles are also evaluated and compared for various electricity sources to obtain hydrogen. The modeling and simulation of each process are performed using Aspen-plus by considering various heat recovery approaches for thermal management. The results suggest that the environmental impact rates of exergy destruction are relatively much higher compared to the environmental impact rates associated with the components for all processes. Furthermore, the hydrolysis step yields the highest component-associated environment impact rate for all thermochemical cycles considered (Fe–Cl: 3497 mPts/h, Cu–Cl: 1997 mPt/h, and Mg–Cl: 910 mPts/h). Moreover, the magnesium-chlorine cycle results in the highest environmental impact rate of exergy destruction (650,328 mPts/h) while the iron-chlorine cycle has the highest component-related environmental impact rate (5219 mPts/h) among the three cycles. In addition, the global warming potential of the magnesium-chlorine cycle is relatively higher compared to the copper-chlorine cycle for several electricity sources. [Display omitted] • An exergoenvironmental analyses of three thermochemical cycles is performed. • Each cycle is incorporated with thermal management schemes for higher efficiencies. • Industrial waste flue gases are considered as a heat source for hydrolysis reaction. • A hydrogen production capacity of 668 kg/h is considered for each cycle. • A comparison of global warming potential for various electricity sources is made. [ABSTRACT FROM AUTHOR]

Selective carbon capture from exhaust gas and biogas, which mainly involves the separation of CO2/N2 and CO2/CH4 mixtures, is of paramount importance for environmental and industrial requirements. Herein, we propose an interesting metal-organic framework-based nanotrap, namely ZnAtzCO3 (Atz− = 3-amino-1,2,4-triazolate, CO32− = carbonate), with a favorable ultramicroporous structure and electrostatic interactions that facilitate efficient capture of CO2. The structural composition and stability were verified by FTIR, TGA, and PXRD techniques. Particularly, ZnAtzCO3 demonstrated high CO2 capacity in a wide range of pressures, with values of 44.8 cm3/g at the typical CO2 fraction of the flue gas (15 kPa) and 56.0 cm3/g at the CO2 fraction of the biogas (50 kPa). Moreover, ultrahigh selectivities over CO2/N2 (15:85, v:v) and CO2/CH4 (50:50, v:v) of 3538 and 151 were achieved, respectively. Molecular simulations suggest that the carbon atom of CO2 can form strong electrostatic Cδ+···δ−O-C interactions with four oxygen atoms in the carbonate ligands, while the oxygen atom of CO2 can interact with the hydrogen atoms in the triazolate ligands through Oδ−···δ+H-C interactions, which makes ZnAtzCO3 an optimal nanotrap for CO2 fixation. Furthermore, breakthrough experiments confirmed excellent real-world separation toward CO2/N2 and CO2/CH4 mixtures on ZnAtzCO3, demonstrating its great potential for selective CO2 capture. [ABSTRACT FROM AUTHOR]

In this study, a comprehensive examination was conducted to explore the technology involved in the recovery of waste heat from flue gas emitted by a 1000 MW unit. Traditional methods are constrained in their ability to harness waste heat from flue gas solely for the purpose of generating medium-temperature water. The system being examined not only recovers waste heat but also utilizes it to generate steam, thereby greatly improving resource efficiency. The process entails utilizing the flue gas to heat water to a certain temperature, followed by subjecting it to flash evaporation. This process leads to the generation of low-pressure waste heat steam. Within the steam ejector, the waste heat steam combines with high-pressure motive steam extracted from the source, resulting in the formation of medium-pressure steam. Within the steam ejector, the waste heat steam blends with high-pressure motive steam drawn from the source, forming medium-pressure steam that eventually feeds into the A8 steam extraction pipe (low-pressure turbine pumping pipe). The present study examines the fluctuation patterns in motive steam flow, suction coefficient, waste heat steam volume, and outlet temperature of the flue water heat exchanger when different motive steam sources are used. Additionally, the research calculates the reduction in CO2 emissions, the coal consumption for power supply, and the cost savings in fuel for the retrofitted system. The findings indicate that maximizing energy utilization can be achieved by operating the retrofitted unit at the lowest feasible waste heat steam pressure. The implementation of the new system has resulted in a substantial decrease in coal consumption for power supply. When employing main steam as the extraction steam source, the consumption of coal for power generation decreases in proportion to the decrease in waste heat steam pressure while maintaining a constant unit load. When the waste heat steam pressure reaches 0.0312 MPa, the recorded coal consumption for power generation varies between 289.43 g/kWh at 100% turbine heat acceptance (THA) and 326.94 g/kWh at 30%THA. When comparing this performance with the initial thermal power plant (TPP) unit, it demonstrates reductions of 2.26 g/kWh and 1.52 g/kWh, respectively. After implementing modifications to this 1000 MW unit, it is projected that the annual CO2 emissions can be effectively reduced by 6333.97 tons, resulting in significant cost savings of approximately USD 0.23 million in fuel expenses. This system exhibits considerable potential in terms of emission reduction and provides valuable insights for thermal power plants aiming to decrease unit energy consumption. [ABSTRACT FROM AUTHOR]

Regulating electron transport rate and ion concentrations in the local microenvironment of active site can overcome the slow kinetics and unfavorable thermodynamics of CO2 electroreduction. However, simultaneous optimization of both kinetics and thermodynamics is hindered by synthetic constraints and poor mechanistic understanding. Here we leverage laser-assisted manufacturing for synthesizing CuxO bipyramids with controlled tip angles and abundant nanograins, and elucidate the mechanism of the relationship between electron transport/ion concentrations and electrocatalytic performance. Potassium/OH− adsorption tests and finite element simulations corroborate the contributions from strong electric field at the sharp tip. In situ Fourier transform infrared spectrometry and differential electrochemical mass spectrometry unveil the dynamic evolution of critical *CO/*OCCOH intermediates and product profiles, complemented with theoretical calculations that elucidate the thermodynamic contributions from improved coupling at the Cu+/Cu2+ interfaces. Through modulating the electron transport and ion concentrations, we achieve high Faradaic efficiency of 81% at ~900 mA cm−2 for C2+ products via CO2RR. Similar enhancement is also observed for nitrate reduction reaction (NITRR), achieving 81.83 mg h−1 ammonia yield rate per milligram catalyst. Coupling the CO2RR and NITRR systems demonstrates the potential for valorizing flue gases and nitrate wastes, which suggests a practical approach for carbon-nitrogen cycling. Controlling the kinetics and thermodynamics of electrochemical processes is essential to achieve high-performance multielectron reduction. Here, the authors report laser-induced copper bipyramids with abundant nanograins and controlled tip angles for enhanced multielectron CO2 and nitrate reduction. [ABSTRACT FROM AUTHOR]

The present work focuses on the combustion of alternative renewable fuels, ammonia in this case, in a system, such as the Laboratory Unit CYclonic (LUCY) burner. This reactor can operate under Moderate or Intense Low-oxygen Dilution (MILD) combustion conditions thanks to a strong internal recirculation of flue gases. Experimental data, including in-flame temperatures and exhaust gas composition, are available. Numerical simulations based on Computational Fluid Dynamics (CFD) techniques are performed and compared to the experiments to analyze the suitability of existing numerical sub-models. More specifically, a sensitivity analysis is carried out both for the turbulence closure models, i.e., RNG k-ϵ, BSL k-ω and Reynolds Stress Model, and for the combustion models, i.e. Flamelet Generated Manifold, Eddy Dissipation Concept and Partially Stirred Reactor, incorporating seven different kinetic schemes. [ABSTRACT FROM AUTHOR]

The integration of renewable energy sources, such as solar, biomass, and geothermal, with other technologies and energy production cycles holds the potential to significantly enhance power generation processes' efficiency. A novel trigeneration structure is introduced that harnesses geothermal energy and waste energy from flue gases. The proposed system comprises several key components, like combined flash and binary geothermal system, a water desalination unit, a Kalina power and cooling cycle, and organic Rankine cycles. The system is analyzed from various perspectives, encompassing energy, exergy, economic, and environmental viewpoints. This assessment allows for a holistic understanding of the trigeneration structure's performance, considering its energy efficiency, exergetic effectiveness, economic viability, and environmental impact. By combining elements, the trigeneration system aims to optimize the utilization of geothermal energy while efficiently converting waste energy from flue gases into useful power. The implementation and evaluation of this trigeneration structure offer promising prospects for sustainable and more effective power generation, promoting the integration of renewable resources with existing energy production technologies. The potential benefits of this approach could lead to a more environmentally friendly and economically viable solution for meeting our energy demands. [ABSTRACT FROM AUTHOR]

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Methanol is expected to be a possible solution for reducing global greenhouse gas emissions and minimizing the dependency on fossil fuels. This paper presents a systematic approach of methanol (MeOH) production from industrial waste gases including flue gas (FG) and coke oven gas (COG) that are considered an important threat to the environment. The impact of process parameters, including dimensional parameters (length, diameter, and number of tubes) and operational parameters (reactor temperature, pressure, and thermal fluid temperature) over the MeOH synthesis, are investigated by Aspen Plus. Firstly, the synthesis process is designed and optimized using syngas (SG) as a feed material. Secondly, by replacing the feed material with FG and COG, methanol production variability is investigated and demonstrated for the same optimized process. Afterward, an efficient heat exchange network system is developed for all three different processes using Aspen Energy Analyzer. The optimized dimensional parameters of the MeOH synthesis reactor are determined to be a length of 12 m, a diameter of 0.06 m, and 5000 tubes for achieving a conversion rate of 75%. Meanwhile, the optimized operational parameters are identified as a reactor temperature of 209   ° C , reactor pressure of 70 bar, and thermal fluid temperature of 196   ° C . Furthermore, the influence of the stoichiometric number (SN) on the process was observed with higher SN values resulting in increased hydrogen (H2) concentration and an improved forward reaction of MeOH synthesis, leading to higher conversion rates. The findings and insights gained from this study can serve further improvements and advancements in MeOH synthesis processes. [ABSTRACT FROM AUTHOR]

This study explores the differences between two novel cogeneration systems with different connection modes. These two systems are the series and parallel systems composed of the Brayton cycle, the organic flash cycle, and the organic Rankine cycle, respectively, which both recover flue gas waste heat and LNG cold energy. First, the equipment and overall system performance of the series system and the parallel system are compared from three aspects of thermodynamics, economy, and exergoenvironment to evaluate the basic performance of the two systems under initial conditions. Next, the performance variations of both systems are assessed by varying the compressor outlet pressure, flash pressure, R14 mass flow rate, and heat source temperature. Finally, the Multi-Objective Cuckoo Search algorithm is used to optimize the systems for two and three objectives, taking the exergy efficiency, payback period and product unit exergoenvironmental impact as objective functions. The final results indicate that the three-objective optimized parallel system has the best performance, the exergy efficiency, payback period, and product unit exergoenvironmental impact of that is 62.25%, 1.389 years, and 7.799 × 10−3 mpt/kJ, respectively. By comparing the performance differences between the series system and the parallel system, this study provides application ideas for engineering requirements. [ABSTRACT FROM AUTHOR]

With the increasing volume of environmental monitoring data, extracting valuable insights from multivariate time series sensor data can facilitate comprehensive information utilization and support informed decision-making in environmental management. However, there is a dearth of comprehensive research on multivariate data analysis for process monitoring in typical polluting enterprises. In this study, an artificial neural network model based on back-propagation algorithm (BP-ANN) was developed to predict the wastewater and exhaust gas emissions using IoT data obtained from process monitoring of a typical polluting enterprise located in Taizhou, Zhejiang Province, China. The results indicate that the model constructed has a high predictive coefficient of determination (R2) with values of 0.8510, 0.9565, 0.9561, 0.9677, and 0.9061 for chemical oxygen demand (COD), potential of hydrogen (pH), electrical conductivity (EC), flue gas emission (FGE), and non-methane hydrocarbon concentration (NMHC) respectively. For the first time, the variable importance measure (VIM)–assisted BP-ANN was employed to investigate the internal and external correlations between wastewater and exhaust gas treatment, thereby enhancing the interpretability of mapping features in the BP-ANN model. The predicted errors for pH and FGE have been demonstrated to fall within the range of − 0.62 ~ 0.30 and − 0.21 ~ 0.15 m3/s, respectively, with average relative errors of 1.05% and 9.60%, which is advantageous in detecting anomalous data and forecasting pollution indicator values. Our approach successfully addresses the challenge of segregating data analysis for wastewater disposal and exhaust gas disposal in the process monitoring of polluting enterprises, while also unearthing potential variables that significantly contribute to the BP-ANN model, thereby facilitating the selection and extraction of characteristic variables. [ABSTRACT FROM AUTHOR]

Industry processes require large amounts of energy inputs and often generate high temperatures exit gases that can potentially serve as secondary sources of energy. Waste heat recovery offers an opportunity for energy conservation that deserves more attention in the current global effort. Recovery of such waste heat can result in substantial reductions in net energy demand. Based on these objectives, this report describes the result of an experimental study that used solid particles in a vertical riser to recover gas energy from hot air through co‐current contact with solid particles. To study the hydrodynamic aspects of the riser section, this study utilized a fabricated experimental apparatus similar to the vertical duct used in the cement industry. The purpose of this study is to collect hydrodynamic data because there is limited information available about these aspects in the literature. A metallic fluid particle heat exchanger has been investigated through experiments. Various sizes of quarry dust and iron ore particles are studied in the present study. An empirical correlation is used to fit the mixing length (LA) determined at different parametric levels (gas velocity, particle size, solid feed rate, and solid density). Experimental correspondence for mixing length or LA is given as LAdt=5.1875dpdt0.1837wswg−0.1374ugμgdt2gρg0.3015ρpρg0.3961. The constructed experimental setup demonstrates a suspension preheater (SP) used in modern cement plants, but the correlation can be extended to a variety of other industries where waste heat recovery is feasible. [ABSTRACT FROM AUTHOR]

A 46 MW pulverized coal industrial boiler with swirl burner had severe slagging and high NOx emission during actual operation. To solve these problems, a full-scale industrial test was carried out. The flue gas temperature and the composition of exhaust gas were obtained under different ratios of secondary and separated secondary air. The results shown that reducing the ratio of secondary and separated secondary air could delay the ignition of pulverized coal and weaken the flame deflection, which was conducive to slowing down the burner slagging problem. However, it will aggravate the erosion of high temperature flue gas on the back wall, and further aggravated the furnace slagging problem. Changing the air ratio couldn't substantially improve the problem of high exhaust temperature. Properly reducing the ratio of secondary and separated secondary air could effectively control NOx emission. When the ratio of secondary and separated secondary air was reduced from 73:27 to 52:48, the NOx emission was reduced by 44.8%. Reducing the ratio of secondary and separated secondary air leaded to the increase of carbon content in fly ash and slag, but the heat loss of exhaust gas was reduced and the thermal efficiency of boiler was increased. [ABSTRACT FROM AUTHOR]

For most Claus sulfur recovery units, the sulfur-containing and oxygen-containing waste gases from liquid sulfur pool are usually introduced into the incinerator for incineration, resulting in a significant increase in the concentration of SO2 in the discharged flue gas, posing a risk of exceeding environmental standards. In order to achieve the treatment and resource utilization of sulfur-containing waste gas, a new type of antioxidant low-temperature tail gas hydrogenation catalyst has been developed and evaluated. The physical and chemical properties, catalytic activity, and oxygen resistance indicators have been examined. The oxygen volume fraction in the imported feedstock tail gas of the reactor can reach 1 %. Based on the excellent catalytic activity and oxygen resistance of the new hydrogenation catalyst, a new process technology for recovering waste gas from liquid sulfur pool to the hydrogenation reactor has been developed. The temperature rise of the reactor bed is about 36 °C higher than that of the conventional process, and the organic sulfur hydrolysis conversion rate reaches 100%. In 2019, the technology was first applied to a 200,000 TPY two-stage conventional Claus sulfur recovery unit in Puguang Gas Field. The results show that the performance of the new antioxidant low-temperature tail gas hydrogenation catalyst is comparable to that of imported catalysts, and its oxygen resistance meets the demand for resource conversion of waste gas from oxygen-containing liquid sulfur pool in large sulfur recovery units. The reduction in SO2 emissions from flue gas is over 50%, and the emission concentration is below 200 mg/m³. This technology can be promoted and applied in similar sulfur recovery units. [ABSTRACT FROM AUTHOR]

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Objectives The aims are as follows: (1) Improving the selective absorption effect of amine solution and reducing the energy consumption of the unit; (2) Improving the quality of liquid sulfur products and reducing the SO2 mass concentration in emission flue gas; (3) Realizing the domestic application of catalysts. Methods Guided by data simulation, combined with field tests, the unit operation parameters were optimized, and the 2-layer absorption tower tray was removed. Results The product gas yield increased by more than 1.3 percentage points, the electric power consumption of the amine circulating pump motor decreased by 12. 46%, and the volume of amine regeneration steam decreased by 11%. Through the technical transformation such as liquid sulfur bubble degassing, liquid sulfur pool exhaust gas into Claus furnace, and hot nitrogen sulfur blowing, the quality of liquid sulfur products is stable and up to standard, and the SO2 mass concentration of emission flue gas is lower than 200 mg/m³. Through the development and application of domestic hydrolysis, sulfur production and hydrogenation catalysts, good application results have been achieved, which is worthy of popularization and application. Conclusion The further development of high sulfur gas promoted through a series of production optimization, technical transformation and domestic application of catalysts. [ABSTRACT FROM AUTHOR]

One of the significant factors contributing to high energy consumption is the unutilized waste heat from flue gas in industrial boilers. Thermoelectric generator (TEG) technology can directly convert thermal energy into electrical energy, and has been gradually applied in the field of waste heat recovery due to its simple and reliable structure, environmental protection, and other advantages. In this paper, a thermoelectric generator simulation system of boiler flue gas waste heat is proposed. The experimental platform is designed by simulating the flue gas waste heat temperature condition of boiler, and the structure of cold end module and hot end module is optimized. During the experiment, the fixed temperature difference was set at 120 °C (hot end:150 °C~cold end: 30 °C). An analysis is conducted on the volt-ampere characteristics and output power of the TEG module. The output characteristics of the TEG system are analyzed under the conditions of variable load, constant load, different pump speed, different heat dissipation modes, and series and parallel connection method. The results show that the experimental platform can instantaneously and accurately test the output parameters of the TEG system, and ensure the intended design requirements. When the ratio of the load resistance to the internal resistance of the TEG module is approximately 1–1.15, the output power of the system reaches its maximum. In order to optimize the output power of the TEG system, a power prediction-based adaptive variable step size maximum power point tracking (MPPT) algorithm is introduced. Additionally, a corresponding mathematical model is formulated. Simulations demonstrate that the time of the improved algorithm to reach the stable maximum power point is 1.54 s faster than that of the traditional algorithm. The improved MPPT algorithm satisfies the criteria for speed and accuracy, diminishes superfluous energy waste, and enhances the overall system efficiency. The research results have certain guiding significance for the design and application of subsequent TEG system. [ABSTRACT FROM AUTHOR]

Net power plant efficiency is the ratio of exportable electrical power output to the product of fuel consumption rate and fuel heating value. Conventionally, power plants are designed to attain the maximum net power plant efficiency by using regenerative feed water heating, in which extracted steam from steam turbine is used to increase feed water temperature. An important factor that determines the net power plant efficiency is the temperature of flue gas exhausted from the power plant. Decreasing this temperature increases the net power plant efficiency. However, exhaust flue gas temperature should not be lower than the lower limit in order to avoid the corrosion resulting from condensation of sulfuric acid vapor in flue gas on heat exchanger tubes. The lower limit can be raised by reducing fuel moisture content and raising air temperature at boiler inlet. In this paper, it is proposed that low-pressure extracted steam should be used for fuel drying in steam dryer, and vapor released from steam dryer should be used for air heating in heat recovery air preheater. By doing so, the lower limit of exhaust flue gas temperature is decreased, and the net efficiency of the power plant is increased. A case study of a 600-MW lignite-fired power plant is used to demonstrate that the integration of steam dryer and heat recovery air preheater is economically justified. [ABSTRACT FROM AUTHOR]

Since it is difficult to deal with high‐concentration nitrates in scrubbed wastewater onboard vessels, the application of traditional wet denitration technology is limited to some extent. Here a novel method for removing pre‐oxidized NOx by using Na2SO3/THS composite solution is proposed with the aim to obtain high NOx absorption efficiency and low nitrate concentration in scrubbed wastewater simultaneously. The effects of Na2SO3 concentration, THS concentration, NOx oxidation degree, coexistence of SO2 and O2 in flue gas, initial pH value and temperature of absorption solution on denitration performance were discussed in detail. The results showed Na2SO3 could reduce NOx to nitrate, nitrite, and N2. The addition of THS could promote NOx absorption greatly by forming complexes with SO32−. When initial NOx concentration was 1000 ppm with a NOx oxidation degree of 50%, O2 concentration was 8%, Na2SO3 and THS concentrations were 25 and 20 mmol/L, a NOx absorption efficiency of 87% could be achieved, while nitrate and nitrite concentrations were 32.97 and 14.19 mg/L, respectively. [ABSTRACT FROM AUTHOR]

The complex composition of solid waste leads to the variability of flue gas emissions during its incineration, which poses a challenge to the stable operation of incineration and pollution control systems. To address this problem, the study explored a new method to predict the concentrations of flue gas pollutants during incineration based on the composition of mixed solid waste using machine learning. Through comprehensive model interpretation and analysis, the important influence of waste composition characteristics on the generation of flue gas pollutants during incineration was deeply explored. The study found that rubber and plastic components significantly promoted the conversion of C to CO during waste incineration; N content and C/N ratio had a significant effect on the generation of NO X ; S content and C/S ratio affected the generation of SO 2 ; Cl content and C/Cl ratio had a significant effect on the generation of HCl, especially with PVC components. The extreme gradient boosting tree (XGBOOST) model optimized by feature engineering showed more excellent R2-validation (0.98, 0.94, 1.00, 0.98, 1.00, 0.98) for predicting CO 2 , CO, N 2 O, NO, SO 2 , and HCl concentration, than K-nearest neighbor (KNN), random forest (RF), and light gradient boosting machine (LGBM). This study provides a new prediction and optimization method for waste incineration plants, which can guide the regulation of feedstock and incineration parameters, thus improving operating efficiency and pollution control. It is of great significance to promote sustainable waste management and environmental protection. • A novel ML-based approach predicts flue gas concentrations from waste composition. • Feature engineering identifies key predictors and uncovers nonlinear relationships. • XGBOOST outperforms other models in predicting flue gas pollutant concentrations. • The approach optimizes waste composition and enhances pollution control efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Acid-mediated modification promotes Ca-O-Mn interaction in Hap-based material. • The effect of two Ca-O-Mn interactions on physicochemical properties was revealed. • Removal of C 7 H 8 and HCHO over sustainable catalyst derived from waste Hap. • The mechanism concerning removal of C 7 H 8 and HCHO on Mn/BC-OA was proposed. The emissions of toluene and formaldehyde, both recognized as hazardous volatile organic compounds (VOCs) resulting from the burning of petroleum products and coal, are receiving increasing attention. In this study, we investigated the acid-mediated manganese modification to promote the simultaneous removal of toluene and formaldehyde in simulated flue gas over waste hydroxyapatite. Characterization results indicated that the acid-mediated modification, based on the Dissolution-precipitation mechanism, effectively enhanced Ca-O-Mn interaction compared to the modification method based on Ion exchange mechanism. The Ca-O-Mn interactions in hydroxyapatite and MnO x exhibited a comparable impact on the improvement of morphology characteristics. Furthermore, the Ca-O-Mn interactions in MnO x with a more positive influence on catalytic activity, due to promoting the generation of active oxygen species, including lattice oxygen with enhanced activity and abundant chemisorbed oxygen species. Hence, the acid-mediated modification endowed Mn/BC-OA with a higher specific surface area and metal dispersion, as well as abundant surface-active oxygen species. These improvements in morphology and surface chemical properties synergistically enhanced the catalytic activity of Mn/BC-OA for toluene and formaldehyde, as well as simultaneous removal of mixed VOCs in simulated flue gas. Finally, Mn/BC-OA was proved with well renewable performance and superior durability, indicating its potential for simultaneous removal of toluene and formaldehyde in simulated flue gas. [ABSTRACT FROM AUTHOR]

High-temperature thermal injection is a key step in extracting unconventional oil and gas. The study proposes an innovative application approach for downhole combustion heaters, which utilizes low calorific value gas as the heat source for in-situ combustion and heat injection mining. This paper employs numerical simulation methods to analyze the catalytic combustion processes of methane, hydrogen, and carbon monoxide, and yields quantitative data on exhaust gas temperature and conversion rates. The research reveals significant differences in the impact of different types of low calorific value gases on catalytic combustion. Hydrogen combustion is most sensitive to temperature changes. As the mole fraction of hydrogen increases from 2 % to 10 %, the exhaust gas temperature rises from 909.18 K to 919.51 K. Moreover, the limitation in the number of catalyst active sites is an important factor affecting catalytic combustion performance. The catalytic combustion of low calorific value gases composed of hydrogen and carbon monoxide results in a change of exhaust gas temperature ranging from 908.72 K to 913.11 K. The determination of the theoretical results provides a reference basis for the subsequent experimental development of low calorific value gas catalytic combustion heaters, and offers a new approach for energy conservation and emission reduction. The figure illustrates the use of low calorific value gas in the in-situ thermal recovery process of unconventional oil and gas. The low calorific value gas is combusted in a downhole catalytic combustion heater, generating high-temperature flue gas that heats the unconventional oil and gas layers to facilitate the extraction process. A portion of the low calorific value waste gas that is produced is then reinjected, completing the cycle. [Display omitted] • Catalytic combustion converts low-calorific value gases to high-temp outputs. • Explored the characteristics of catalytic combustion of different gas components. • Low-calorific value gas heating extraction reduces energy use and environmental impact. [ABSTRACT FROM AUTHOR]

• A specific review on chlorobenzene elimination is proposed. • Catalysts' surface oxygen and acid sites affect the chlorobenzene oxidation. • Differences between Cl deposition and adsorption decide catalysts' stability. • The insufficient oxidation caused the formation of various byproducts. • H 2 O, NO x /NH 3 , Hg0, and other VOCs have varying effects on chlorobenzene removal. The emission of chlorinated volatile organic compounds (Cl-VOCs) is a significant contributor to air pollution, impacting both the environment and human health. Chlorobenzene, with typical characteristics of Cl-VOCs, is often used as a representative compound in research owing to its widespread presence in various industrial processes such as fine chemical engineering and coking. Catalytic oxidation has emerged as an effective technology for removing chlorobenzene from waste gases. Metal oxides such as MnO x , CoO x , CeO x , FeO x , CuO x , and VO x have garnered attention for their potential as active species and additives in chlorobenzene oxidation, offering advantages such as earth abundance, ease of fabrication, and relatively low cost. This review provides a comprehensive overview of recent advancements in the catalytic oxidation of chlorobenzene using metal oxide-based catalysts. Key properties such as activity, selectivity, stability, and adaptability to flue gas components are considered crucial for evaluating these catalysts. The review systematically examines the progress made in enhancing these properties. Given the generation of various byproducts and the presence of diverse flue gas components such as Hg0, NO x , and other VOCs, strategies for improving CO 2 selectivity, adaptability to flue gas components, and overall stability of the catalysts are discussed. Mechanisms underlying chlorobenzene degradation are also elucidated from a microscopic perspective. Finally, the review emphasizes the need for designing and developing new catalysts capable of achieving stable, long-term performance in real-world flue gases to effectively reduce VOC emissions. [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.)