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High-temperature ESPs are proposed to improve energy efficiency and avoid damage to downstream equipment in integrated gasification combined cycle and pressurized fluidized-bed combustion. In this study, the effects of temperature and pressure on negative corona discharge characteristics were compared. Gas temperature varied from 373 K to 1073 K, and pressure varied from 30 kPa to 100 kPa to achieve the same gas density. The additional corona current Δ I t induced by high temperature was calculated, and the additional ion current Δ I i and electron current Δ I e were studied. A wire-type electrode, a spiral electrode, a ribbon electrode, and four gas compositions (N 2 /CO 2 /SO 2 /air) were investigated in the plate-type discharge configuration. Results show that corona current increases more rapidly with increasing gas temperature than that with decreasing pressure at the same gas density. The current density is 0.87 mA/m at 973 K and atmosphere pressure, which is higher than 0.45 mA/m at 30.9 kPa and room temperature. An additional temperature effect on corona discharge is proposed apart from the decrease of gas density as temperature increases. Δ I t increases with increasing temperature because of enhanced molecule kinetic energy and ionization rate. The electron-carried current is important at temperatures above 873 K. Δ I e /Δ I t increases from 0 to 0.941 when temperature increases from 773 K to 973 K. Compared with the Δ I t of wire and spiral electrodes, the Δ I t of ribbon electrode is significantly larger because of the enhanced electron avalanche and secondary electron emission. Negative corona discharge does not occur in N 2 , and corona onset voltages are in the following sequence: CO 2 > SO 2 (6000 ppm) > air, which is determined by gas molecule ionization energy. Δ I t / I P is smaller in gas atmosphere with strong electronegativity. [ABSTRACT FROM AUTHOR]

Highlights: [•] The NOx absorption and nitrite/nitrate formation in limestone slurry was studied. [•] The NOx compositions and SO2 significantly affects NOx absorption rates. [•] The mechanism of NOx absorption and conversion in limestone slurry was proposed. [ABSTRACT FROM AUTHOR]

Equilibrium capacity expansion is an effective tool to help regulators predict the generation evolution of power systems by analyzing the decision-making of generation companies (Gencos). With the development of carbon markets (CMs) and electricity markets (EMs), Gencos' decisions in these two markets (encompassing investment and bidding decisions related to carbon emission allowances and electricity) are deeply intertwined through market clearing results. However, existing studies mainly focus on equilibrium capacity expansion with fixed carbon prices and usually ignore the realistic clearing process of CMs, which cannot simulate Gencos' coupled decision-making and accurately predict generation evolution under the CMs and EMs. This paper proposes a two-level equilibrium capacity expansion model for power systems which considers the coupled decisions of Gencos between CMs and EMs. At the upper level, multiple Gencos' coupled decision models are proposed based on their interaction with market clearing results. At the lower levels, CMs and EMs are respectively cleared to determine the varying carbon and electricity prices. Furthermore, the developed equilibrium capacity expansion model is reformulated as an equilibrium problem with equilibrium constraints (EPEC), which is solved by a diagonalization-based solution procedure. Finally, a provincial power system of southeast China is used to validate the performance of the proposed framework. The results illustrate that under CMs and EMs, non-fossil energy would account for 81.3% of total capacity and 73.88% of total generation in 2050. Compared to the existing model using fixed carbon prices, the consideration of realistic carbon market clearing will promote the installation of renewable energies and improve social welfare. The proposed model can provide beneficial references for regulators to perceive the evolution of power systems in CMs and EMs. • A two-level equilibrium capacity expansion model for power systems is proposed. • A novel coupled decision model for Gencos in CMs and EMs is developed. • The proposed model is solved by a diagonalization based solution procedure. • The results can guide the transition of power systems under the CMs and EMs. [ABSTRACT FROM AUTHOR]

• An efficient framework to exploit the flexibility of local energy hubs in system risk management. • The flexible-region-based framework can guarantee privacy concerns and improve computational efficiency. • The flexible region contains time-independent and temporal-related parts. • The model can mitigate the operational risks of integrated electricity-gas systems. • The model can effectively reduce the total costs of the whole system. Faced with increasing operational uncertainties, e.g. wind power variation, the risk management of integrated electricity-gas systems (IEGSs) has become extremely vital, which puts forward a higher requirement for flexible resources. On the demand side of IEGSs, local energy hubs (LEHs) composed of different energy devices can provide flexible resources for system risk management through multi-energy substitution. However, it can be difficult to exploit the operational flexibility of massive LEHs in IEGS operation owing to two major issues, namely 1) privacy concerns of individuals; 2) computation efficiency requirements. To address this, an efficient framework based on flexible regions is innovatively proposed for exploiting LEH flexibility in the risk management of IEGSs. The flexible region is estimated to characterize the adjustable range of energy inputs to LEHs considering the operational requirements of internal energy devices. On this basis, essential flexibility-related information of LEHs is directly utilized for system risk management, which can preserve individual privacy and avoid time-consuming iteration. Firstly, a generalized method based on Minkowski Summation is proposed to efficiently determine the flexible region of LEH, which contains time-independent and temporal-related parts. The two regions are formulated separately considering the multi-energy substitution of LEH and the charging/discharging process of electric storage. The flexible region is then mathematically formulated as a set of linearized equations, which can be directly incorporated into the system scheduling model. On this basis, a risk-based two-stage optimization model is developed for the coordinate dispatch of IEGSs and LEHs considering wind power uncertainties. Case studies demonstrate that the exploitation of LEH flexibility can effectively mitigate operational risk levels of IEGSs and reduce system costs. Besides, the proposed model has the advantage of high computation efficiency compared to the existing iteration-based method. [ABSTRACT FROM AUTHOR]

• Developed a molecular dynamics model to study the nano-scale transport of gaseous pollutants in titania-based catalysts. • Investigated the diffusivity under the impacts of different molecules, temperatures, pore widths and hydroxyl sites. • Studied the influences of competitive diffusion of mixed pollutant molecules on the diffusivity. Mass transfer can significantly affect the SCR process which is designed for NOx removal. However, it is still challenging to characterize the transport of gaseous species involved in the process, especially at nano-scale. This work probes into the application of non-equilibrium molecular dynamics (NEMD) simulations to study the mass transfer of multi-pollutants over a titania-based catalyst. A dual control-volume (DCV) model was proposed to simulate transport of typical gaseous molecules (e.g. NO, NH 3 and SO 2). The impacts of temperature, pore width, hydroxyl sites and competitive diffusion on diffusivity of objective molecules were studied in details. The results showed that temperature and surface sites could affect NH 3 more significantly than NO and SO 2 , yet the influence of surface sites was strongly size-dependent. The reduction in NH 3 diffusivity caused by the presence of surface sites decreased from 32.37 % to 2.97 % when the pore width grows from 25 Å to 75 Å. The competitive transport between NH 3 and SO 2 has also mitigated the impacts of surface sites on both molecules. [ABSTRACT FROM AUTHOR]

Ceria has absorbed extensive interests in functioning as catalysts for low-temperature (LT) selective catalytic reduction (SCR) of NOx due to its abundant surface oxygen species and salient redox property. The mechanistic interpretations of how such redox property contributes to its LT-SCR activity, however, still remain debated. Here, we use a model tungsten-promoted ceria catalyst (WO 3 /CeO 2), known as preeminent in LT-SCR reactions, and combine steady-state kinetic, structural characteristic and in situ spectroscopic experiments with theoretical treatments to reveal the mechanistic connections between NO oxidative activation and LT-SCR turnovers. We show that, compared with NO oxidation to NO 2 , NO oxidative activation to nitrite intermediates is both kinetically and thermodynamically more favorable; surface nitrate species are not detected in the present case, indicating their more difficult formation than nitrites. All these results thus suggest the prevalence of NO activation to nitrites over NO to nitrates or oxidation to NO 2 and subsequent occurrence of fast SCR in the WO 3 /CeO 2 -catalyzed LT-SCR reaction. These findings progress the understanding of LT-SCR reaction mechanism on CeO 2 -based catalysts and convey a detailed perspective of different reaction intermediates and their consequences for LT-SCR turnovers, which may contribute to the rational design of catalysts towards further improved LT-SCR activity. [ABSTRACT FROM AUTHOR]

This study investigated the cost and potential of energy conservation and collaborative pollutant emission reduction in the iron and steel industry in China. A total of 24 technologies were selected, and their investments, operation costs, energy saving benefits, abatement benefits, abatement coefficients and popularising rates were collected and calculated using the 2013 data as the baseline. A new parameter, AP eq , reflecting the characteristics of energy conservation and multi-pollutant collaborative emission reduction was set up. The conservation and emission reduction supply curves (CERSCs) were analysed. These 24 technologies resulted in the abatement of SO 2 , NO x , PM 10 , CO 2 and AP eq to 621.6 kt, 398.9 kt, 390.2 kt, 291.1 Mt and 699.5 kt, respectively. The influences of discount rates and weight factors on the abatement supply curves were also discussed. Results show that, with the increase in the discount rate, the abatement costs increase and the amount of that abatement cost below zero decreases. Finally, the pollutant reductions in three key areas in China were analysed. The reduction potentials of the Beijing–Tianjin–Hebei region, Yangtze River Delta and Pearl River Delta are 107, 79 and 13 kt, respectively, and the corresponding abatement costs are 7.52, −51.54 and −1.76 billion Yuan. Policymakers can choose suitable and economic technologies according to the calculation of the CERSCs. [ABSTRACT FROM AUTHOR]

• Accelerated discovery of Hg0 sensing materials was achieved. • Data mining via a synergy of Pymatgen, Factsage, Aflow & density functional theory. • Predicting transition-metal dichalcogenide is based on component-oriented structure. • Evaluation of adsorption-based Hg0 sensing is done via first-principles calculation. • PdS 2 is the most superior dichalcogenide for a Hg0 sensing material. The detrimental impact of urban airborne Hg0 from fossil fuel utilization has necessitated the discovery and development of Hg0 sensing materials for effective Hg0 detection and mitigation of the pollutant. Earlier studies have hypothetically and experimentally supported 2-dimensional transition-metal dichalcogenides (2D TMDCs), particularly MoS 2 to have excellent performance for Hg0 removal. However, the potential of other TMDCs is yet to be investigated for Hg0 sensor application. In this study, a total of 28 transition metals within periods 4–6 of the periodic table, excluding the lanthanides series, were examined. To ensure proper data management flow, a high-throughput data mining approach with integrated machine learning and cheminformatics simulation approaches is developed. The systemic approach integrates the Pymatgen, Factsage, Aflow and density functional theory simulation tools for accelerated discovery of suitable TMDCs from raw data via the chemical vapour reaction route. Predicted results showed that TiS 2 , NiS 2 , ZrS 2 , MoS 2 , PdS 2 and WS 2 exhibited TMDCs characteristics. Furthermore, first-principles calculation shows Hg-uptake capacity is in the order NiS 2 > PdS 2 > TiS 2 > ZrS 2 > WS 2 > MoS 2 , while Hg sensing response is in the order PdS 2 > MoS 2 > WS 2 > ZrS 2 > NiS 2 > TiS 2. Accordingly, PdS 2 depicted to be the most suitable TMDCs for airborne Hg0 sensor application. The proposed systemic approach is an initial platform for materials discovery using integrated machine learning approaches and is well-suited for the screening and the discovery of new materials based on component-oriented structures. [ABSTRACT FROM AUTHOR]

• Energy-cyber-physical-systems improve flexibility in fuel sources & energy products. • Quantitative analysis of improvement in coal-sludge co-combustion is conducted. • Quantitative thermodynamic and economic assessments are conducted. • The heating, cooling, power and compressed air products are stably produced. • Artificial neural network is employed for the prediction of realistic scenarios. The fluctuating energy requirement from time-varying demand changes require flexible power system to respond to the dynamic load balance. In certain scenarios, flexible power systems are necessary to provide high system efficiencies and increase the long-term economic benefits. Therefore, it is important to identify the relationship between energy requirement of a city and/or industrial zone with the dynamics of a flexible power system. In this paper, we evaluate the possible benefits of adopting the energy-cyber-physical-systems (e-CPSs) concept in realization of a flexible closed-loop control power system in case of coal-sewage sludge co-combustion. The case study performance analysis of flexibility, efficiency and economics (FEE) for a 356 MW coal-fired power plant was conducted by means of simulation in Aspen PLUS software. The analysis was based on a specific multifarious model of a dynamic power system with two energy sources and four energy products. The results confirmed that substantial advantages including a more flexible, efficient and economically viable system can be achieved by using e-CPSs based solution in different case scenarios. Moreover, following the analyzed data from the proposed case scenarios, a forecasting model for optimization of the power plant parameters based on the use of artificial neural network (ANN) was established. The results showed that ANN-based approach for predictive model is capable of modelling the complex process within an acceptable prediction accuracy. The study demonstrates that the proposed flexible closed-loop control power system based on e-CPSs concept is able to achieve higher efficiency and economic benefits compared to the traditional approaches. [ABSTRACT FROM AUTHOR]