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Acid gas enrichment (AGE) is a new method to increase the H 2 S conversion in conventional Clause process. In this paper effect of methyl diethanolamine (MDEA) flow rate, MDEA temperature, acid gas flow rate, and AGE tower pressure on the outlet H 2 S and CO 2 concentration and energy consumption have been studied. A novel procedure based on enthalpy of combustion in the reaction furnace and incinerator is conducted for energy consumption calculations. By changing MDEA and inlet acid gas flow rates, a maximum H 2 S concentration in the enriched stream could be attainable. Increasing MDEA temperature will decrease maximum H 2 S concentration and enriched acid flow rate; also, CO 2 concentration in off-gas will be decreased. By increasing AGE pressure, maximum H 2 S concentration in the enriched stream will be diminished. At higher MDEA flow rates, lower AGE pressures will bring higher H 2 S concentration in enriched acid gas stream. According to flame temperature simulation in the reaction furnace, energy consumption is directly related to H 2 S concentration in the sulfur recovery unit (SRU) feed stream. Results show that maximum H 2 S concentration in the enriched acid gas stream has the best conditions from energy point of view. At optimum conditions, H 2 S concentration in enriched acid gas is 62.45 mol%, which has been increased by 24.8%, compared with existing plant conditions, and energy consumption has been decreased by 25.05 GJ/h, and CO 2 concentration in off-gas is 94.94 mol%. • Study the effect of process variables on the AGE streams by ProTreat software. • Determine the relation between reaction furnace temperature and H 2 S concentration. • Generate an EES procedure for heat of combustion in reaction furnace. • Evaluate the fuel gas consumption and therefore energy consumption. • Multi-objective optimization based on the TOPSIS method. [ABSTRACT FROM AUTHOR]

Heating in wind-chilled environments is a serious task. The catalytic combustion heater (CCH) provides more efficient and cleaner in combustion compared to conventional heaters with high pollutant emission and low energy utilization. In this paper, the heating ability of CCH on human body in a wind-chilled environment (apparent temperatures between −14.8 °C and 12.4 °C) was investigated by collecting skin temperature and subjective thermal evaluation data from 23 subjects. The impact of cold air on localized heating of body parts by CCH was clarified using decision trees and dimensionless correlation coefficients. A human-computer interaction regulation strategy was proposed to simultaneously satisfy the requirements of effective heating, low energy consumption, and low pollution. Finally, CCH and a commercial heater were compared in terms of heating effectiveness and energy consumption in a real outdoor environment. The results showed that CCH effectively solved the problem of excessive cold extremities, and the temperature difference between thoracoabdominal area and extremities was reduced by 57.5–87.9% to within 2 °C. In a strong convective environment, wind speed was the decisive factor (coefficient of 0.95), inducing 46% radiant heat loss. Inputting personnel subjective perception, dynamic environmental parameters, and pollutant thresholds to adjust the injected gas flow enabled intelligent control. In a real cold scenario, the CCH saved 65.9% of energy compared to a commercial heater when achieving the same heating effect. This study provides a reference for the application of catalytic combustion technology in cold outdoor heating and also provides an important theoretical basis for the construction of heating strategies for CCH. [Display omitted] • A new catalytic combustion heat source was proposed to offset the cold exposure. • Heating characteristics of the CCH were obtained in wind-chilled condition. • The impact of strong convection on CCH radiant heating was quantified. • A comfortable and sustainable optimal control strategy for CCH was proposed. [ABSTRACT FROM AUTHOR]

Considering the environmental pollution caused by the direct stacking or landfilling of various sludge, the combustion characteristics of bituminous coal, Fe-rich industrious sludge, and their blend were studied using thermogravimetric analysis at non-isothermal and isothermal conditions. It was found that the volatile matter in sludge with low C/H ratios will be released and burned in the low-temperature stage, then the generated heat will promote extra heat for the combustion of fixed carbon in coal when the addition of sludge was greater than 60%. The used Flynn-Wall-Ozawa and Kissinger-Akahira-Sunose methods were more accurate for coal, sludge, and their blend with low sludge addition. After comparing the activation energy, a suitable addition of sludge was found to improve the combustion and kinetic characteristics of fixed carbon but do less help to volatile matter in coal. As to the heavy metals emission, the synthetic effect of the blend combustion enhanced the Pb emission when sludge addition was more than 60% but almost did not affect Cr, Ni, Zn, and Cu. By sampling dynamically during the co-combustion, it was found that the leaching toxicity of heavy metals was greatly related to the combustion degree. The stabilization of Al, Ca, Cr, and Zn was finished as their leaching toxicity decreased to a constant value before the burnout of fixed carbon (100∼120s) while that of Ni was slightly delayed, especially when the coal was added. Besides, the leaching concentration of Cu gradually increased with combustion time and its stabilization cost more time. Such a time-controlled combustion strategy may also be worthy of further research to help dispose of other solid wastes with similar composition. [Display omitted] • The FWO and KAS methods were more accurate for co-combustion with low sludge addition. • Combustion of volatile matter in sludge helped the combustion of fixed carbon in coal. • The volatilization of Pb was promoted with the sludge addition in blend combustion. • Leaching concentrations of metals were greatly related to the combustion degree. [ABSTRACT FROM AUTHOR]

Altering the atmosphere type may boost the physicochemical drivers of the combustion, thus contributing to the circularity and sustainable management of hazardous wastes. This study aimed to compare the combustions of spent pot lining (SPL) in the oxy-steam and air atmospheres. The SPL combustion with 21% (Oxy21), 30% (Oxy30), and 40% (Oxy40) O 2 in the oxy-steam atmosphere improved the performance indices. Weighted mean activation energy (E m) fell from 148.36 kJ/mol in the air atmosphere to 118.04 kJ/mol in Oxy21, with the lowest E m value occurring in Oxy30 (referred to as energy-saving pathway). With the temperature rise, the pattern of fluorine distributions in the air atmosphere (the oxy-steam atmosphere) exhibited 65.60 → 92.27% (65.87 → 9.08%) of fluorine in bottom ash, 7.33 → 31.84% (22.31 → 72.83%) in off-gas, and 0.4 → 2.56% (11.82 → 22.22%) in fly ash. The increased O 2 concentration slightly affected the combustion characteristic indices and fluorine distributions. Steam appeared to enhance the pore expansion. The advance decomposition of Na 3 AlF 6 , the new emergence of NaAlO 2 , and the disappearance of CaF 2 characterized the oxy-steam combustion of SPL. The gas-ash-energy nexus was jointly optimized via artificial neural network. The oxy-steam combustion destroyed the stability of both soluble and insoluble fluorine, thus greatly releasing fluorine-bearing gas. [Display omitted] • Oxy-steam combustion was innovatively applied to the SPL treatment. • Fluorine distributions of ashes and gases were quantified. • Shift from the air to oxy-steam combustion reduced the energy barrier. • Steam boosted the outward release of both soluble and insoluble fluorides. • Ash-gas-energy nexus was jointly optimized for the first time. [ABSTRACT FROM AUTHOR]

The present research aims to examine the energy, exergy and sustainability analysis of a traditional four-pan jaggery unit based on the consumption and resource transformations involved in the sugarcane-based jaggery production process. The exergy analysis has been conducted based on an experimental study with the help of thermodynamic relations including the component-wise specific exergy for jaggery production. The energy and exergy of the jaggery unit are compared during the winter and the summer. The obtained average thermal energy efficiency of the jaggery unit shows an increment of 8.1% as compared to the winter season. In addition, when accounting for the combustion performance of bagasse, the exergy efficiency of jaggery plant in the summer is higher than the winter. Furthermore, negative environmental impacts are indicated by a poor exergy sustainability score during both seasons. In summer, the jaggery facility operates more sustainably than in the winter, as shown by the higher value of environmental benign index. Energy analysis alone conceals the fact that the primary factor in resource use is exergy destruction due to irreversibilities in combustion and heat transfer. By assessing the process fluxes in terms of exergy, this study enhances the transparency of resource consumption and losses in the production of jaggery. • Comparison of energy and exergy efficiency of the four-pan jaggery unit. • Thermal efficiency in summer is higher than winter season. • Exergy destruction during the combustion of bagasse is high in both seasons. • Operation of Jaggery unit is more eco-friendly in the summer season. [ABSTRACT FROM AUTHOR]

In order to increase the energy density and generate more products in a sustainable framework, the current study proposes a geothermal-driven power plant combined with an electrolyzer, boosted by an oxyfuel combustion power plant for a novel multigeneration task. The system produces power, heating, methanol, and carbon dioxide (CO 2) in a coherent manner, benefiting from low-emission framework and high thermodynamic performance. This system has not been evaluated before. The proposed system consists of a combined flash and binary geothermal plant, a hydrogen production unit, an oxyfuel power unit, a heat and power generation unit, a transcritical CO 2 Brayton cycle, a steam Rankine cycle, and a methanol generation unit. Hence, the proposed system is analyzed from the energy, exergy, environmental, and economic points of view. In addition, a parametric analysis is performed to assess the effects of some basic thermodynamic parameters on the cycle performance. The parametric study reveals that the increase in the working fluid temperature leads to an increase in the net power and energy and exergy efficiencies, and low pressure of the gas turbine is an important factor for enhancing the total thermodynamic efficiency of the system. Also, the system's energy and exergy efficiencies together with the total unit cost of products are found to be 47.2%, 40.34%, and 5.53 $ G J , respectively. Moreover, the CO 2 footprint corresponding to the electricity and methanol outputs are obtained at 0.0023 k g C O 2 k W h and 0.056 k g C O 2 k g M e O H , respectively. [ABSTRACT FROM AUTHOR]

The second-generation energy crop Miscanthus x giganteus (Mxg) demonstrated ability to produce adequate biomass yield even in marginal or contaminated soils. This renewable biomass can be utilized energetically or transformed into various biobased products and thus contribute to decrease of primary resources and fossil fuel use. To evaluate potential effects on energetic biomass properties Mxg was grown in diesel contaminated soils. Traces of total petroleum hydrocarbons were found solely in the leaves, however most likely resulting from air contamination. No differences were detected in the elemental composition of the raw biomass. Biomass combustion heat value reached average of 17.23 ± 0.21 MJ kg−1; contamination-originated leaves had slightly but significantly decreased heat values (14.41 ± 1.10 MJ kg−1) while heat of other parts was comparable to control. Thermogravimetric curves, simulating thermic utilization processes, were comparable both under oxygen (combustion) and nitrogen (pyrolysis). No diesel impacts were observed on the pyrolysis products yield. Higher amounts of CH 4 , C 2 H 6 , C 3 H 4 , C 3 H 6 and C 3 H 8 were detected in the pyrolysis gas from aboveground biomass from contaminated soil. Diesel contamination decreased significantly biochar surface. Concentrations of acids and esters in biooil were increased on the expense of concentrations of furans in the case of samples from contaminated soils. No significant effect on phenols and ketones concentrations in the biooil was observed. The amount of acetic acid, as the main biooil component, increased in the above- and below-ground plant parts along with the higher diesel concentrations in soil. Despite slight changes detected, the parameters of the biomass produced in diesel-contaminated soils present no obstacle to its energetic utilization and Mxg can be recommended for productive phytomanagement of such soils. • Uptake of petroleum hydrocarbons from soil by miscanthus was not proved. • Biomass from contaminated soils had comparable combustion parameters as control. • Effect of soil contamination on pyrolysis products composition was observed. [ABSTRACT FROM AUTHOR]

In this paper, we present a novel artificial heat reservoir system for extracting spontaneous combustion energy of abandoned coal gangue. The construction process and operation method of the proposed artificial heat reservoir are introduced in detail. A multi-physical fields coupling model of seepage, heat transfer and oxidation of coal gangue is established. The spatio-temporal variation of temperature field, seepage field, oxygen concentration field and residual fuel amount in the oxidation process of coal gangue were numerically investigated. Sensitivity analysis of key parameters was carried out to provide reference for the optimization of artificial heat reservoir. Finally, the heat extraction performance of artificial heat reservoir was studied by using steel U-shaped tube, and its heating potential was evaluated. The results indicates that the process of spontaneous combustion of coal gangue can be divided into two stages: slow heating stage and rapid heating stage. The proposed artificial heat reservoir system presents a "low temperature zone-high temperature zone-low temperature zone" distribution from bottom to top. This alternating and layered temperature zones in vertical direction will form a thermal siphon effect and drive the air to flow upwards. In the rapid heating stage, the temperature increases faster with the increase of ventilation rate. When the porosity is greater than 0.35, it has a great influence on the spatial design of the heat extraction system. The specific heat capacity only affects the changing rate of temperature field and oxygen seepage velocity, but does not affect their final states. The thermal conductivity of coal gangue has little influence on each physical field of reservoir. The heat transfer rate of the middle part of the U-shaped tube is relatively large, the average value of which is about 150 W/m. The heat transfer of U-shaped tube only affects the area within the radius of 2 m. The research can provide a new idea for coal gangue disposal and heat utilization. [ABSTRACT FROM AUTHOR]

Current management of solid waste from pulp and paper activities represents an environmental and economic burden worldwide due to pollution emissions. This study investigates the potential of hydrothermal carbonisation (HTC) treatment as a sustainable alternative for producing cleaner and energy-dense solid fuel from paper mill sludge. The effect of process parameters (temperature, reaction time and solid load) on hydrochar fuel formation from paper sludge was evaluated and, for the first time, the paper sludge-derived hydrochar was optimised to maximise the mass yield and calorific value using response surface methodology (RSM). The physicochemical characteristics, thermal fuel behaviour, energy recycling efficiency and electricity generation potential were assessed by proximate and ultimate analysis, thermogravimetry, bomb calorimeter, scanning electron microscopy and process energy assessment. Results showed that hydrochar fuel formation and properties were mainly influenced by the process temperature and residence time, and governed by dehydration and decarboxylation reactions which reduced the atomic H/C and O/C ratios by 35.5% and 64%, respectively. The produced hydrochars presented low sulphur, nitrogen and ash content with a maximum calorific value (HHV) of 22.9 MJ/kg, equivalent to the HHV of coal for commercial utility in South Africa. The HHV of the hydrochar corresponded to a 49.80% increase over the HHV of the initial feedstock. The optimum operating conditions were 231 ± 1 °C and 1.99 h for a hydrochar yield of 74.4% and calorific value of 18.5 MJ/kg. The energy assessment showed that up to 58.34% of the energy produced by hydrochar fuel combustion may be recycled as heat or power, while the remaining 41.66% of the combustion energy could be utilised to sustain the HTC treatment of paper sludge. The substantial water demand was concluded to be a drawback. Thus, water recirculation and the potential to catalyse the HTC reactions to increase overall process efficiency will constitute a future study to make the process more environmentally friendly for industrial-scale application. [Display omitted] • Dehydration and decarboxylation were predominant. • Optimum energy yield of 18.5 MJ/kg and 74.4% hydrochar was achieved under 231 ± 1 °C and 1.99 h. • Higher HTC reaction severity enhanced the physicochemical properties of the hydrochar. • Hydrochars produced have low nitrogen and sulphur (<1%) content. [ABSTRACT FROM AUTHOR]

CaO and MgO are important industrial raw materials commonly produced by either the decomposition of calcium carbonate at about 900 °C, or the calcination of dolomite, a mixed calcium and magnesium carbonate, calcined either to MgO.CaCO 3 at about 750 °C, or to MgO.CaO at 900 °C. ln this research, the decomposition reaction of 104–147 μm dolomite and limestone particles was investigated, both without and with steam added to the reaction. A series of experiments was performed in terms of relevant parameters such as time, temperature and amount of H 2 O added. Reactants and reaction products were fully characterized and demonstrate the different morphology and specific surface area of the raw carbonate ores and the calcined oxides. Adding H 2 O during calcination has a significant positive effect. The calcination shows that steam can significantly accelerate the reaction rate, and reduce the decomposition temperature by ∼100 °C, thus reducing the cost of the decomposition by increasing the yield for a given reaction time, while also reducing the required sensible heat of the feedstock and combustion air. This ultimately reduces the amount of fossil fuel or alternative energy carriers, thus reducing the CO 2 footprint of the system. The improved operating conditions foster the use of concentrated solar calcination. The CO 2 footprint of the carbonate decomposition can be reduced by ∼4% in traditional kilns, and by as much as 20% if concentrated solar kilns are used. Both applications are currently investigated in pilot-scale operations. • Calcination of dolomite and limestone particles was studied, without and with adding steam. • Steam accelerates the reaction rate and reduces the calcination temperature by ∼100 °C. • Adding steam reduces the energy requirement, thus reducing the CO 2 footprint of the system. • CO 2 emissions are reduced by ∼4% in conventional kilns, and by ∼20% in solar kilns applications. [ABSTRACT FROM AUTHOR]

The objective of the present study is to use life cycle assessment (LCA) to guide the design and implementation of circular business models (CBM) in the wood panel industry towards a cleaner production. Initially, searches in the literature were carried out to select articles on LCA of wood panels, to investigate the possible synergies between LCA and CBMs in the wood panel industry. Investigations of the production system of reconstituted wood panels, with regard to both the biological and technical cycles, allowed spotting signs of existing circularity in some parts of the manufacturing stage, such as the use of wastes for combustion and generation of energy, and the use of ash from combustion processes. In order to reduce impacts, identified via LCA, CBMs for the wood panel sector were proposed, seeking to reduce the impacts identified via LCA and fill the circular gaps left by existing practices. [ABSTRACT FROM AUTHOR]

This study aims to produce natural grown fungi fiber with improved thermal stability and fire resistance. A novel strategy was explored by supplying nutrition enriched with silicon source. The results showed that Si enrichment improved the thermal stability of fungi fiber, possibly due to the thermally stable Si being utilized for fungi cell wall construction. Meanwhile, while nutrition enriched with low Si concentration accelerated fungi fibers production, further increases in Si concentration inhibited the fungal growth. These were attributed to the effects of Si and pH and on fungal metabolism, which was verified by Fourier Transform Infrared (FTIR) and Scanning Electron Microscope/Energy Dispersion Spectroscopy (SEM/EDS) microstructural characterization. Based on experimental observations, the study further investigated two strategies to facilitate fungi to utilize more Si in the fiber construction to enhance its fire resistance, i.e., application of pH buffer and selection of a new fungi strain with higher Si tolerance (Fusarium oxysporum). Both strategies achieved favorable results. Performance wise, fibers produced by both fungi Pleurotus ostreatus and Fusarium oxysporum featured higher residual weights than synthetic PVA fiber (by 2122% and 2223% respectively by Thermogravimetric Analysis (TGA)). Furthermore, with Si source enrichment, the fire resistance of fungi fibers improved further. For example, adding 3% Si to the nutrition of Fusarium oxysporum increased the TGA residual weight of its fiber by 93.81% compared with fiber grown without Si enrichment. Besides, Si enrichment reduced the peak heat release rate and the total heat of combustion of the produced fungi fiber by 50% and 35.09% respectively as measured by Microscale Combustion Calorimetry (MCC) test; these are also significantly less than those of the PVA fibers commonly used for building constructions (87.26% and 72.59% respectively), indicating improved fire resistance. [Display omitted] [ABSTRACT FROM AUTHOR]

The reheating furnace operation in the hot mill is natural gas- and electricity-intensive. Oxygen enrichment combustion for reheating furnaces has been proposed to curb and replace natural gas use. In this study, heat transfer in steel slabs in the combustion environment of a push-type reheating furnace was simulated using a computational fluid dynamics (CFD) model. Two oxygen enrichment methods that optimized for performance were selected— a medium oxygen enrichment (MOE) case and an oxy-fuel (OF) case. A life cycle analysis (LCA) characterized the energy and emission profiles of an integrated iron and steel manufacturing process using the two oxygen enrichment cases for the hot mill. These conditions were evaluated for energy use and carbon intensity and compared with a baseline case. Results show that with oxygen enrichment, natural gas consumption can decrease by 19.6%–26.8%, total energy consumption (natural gas and electricity) can decrease by 15.1%–20.7% in the hot mill. Emissions of greenhouse gases can decrease by 11.1%–15.2% in the two optimized cases with 14%–27% reductions in regulated criteria pollutants (nitrogen oxides, carbon monoxide, particulate matter, volatile organic compounds, black carbon, organic carbon, and volatile organic carbons). There is a tradeoff between reducing natural gas consumption and increasing electricity demand from a life cycle perspective. Although the OF case resulted in higher energy- and emissions-related benefits, the MOE case showed the more desirable heat flux uniformity, which is key to maintaining product quality. The analysis suggests that oxygen enrichment in the reheating furnace process can have a significant impact on hot mill environmental performance and become a contributing factor in transitioning to low-carbon steel manufacturing. • Oxygen enrichment in reheating furnace for producing hot rolled steel is simulated. • Reduction of fossil energy use by 20.7% and GHG emission by 15.2% in hot mills. • NO x , CO, VOC, PM 10 , PM 2.5 BC, and OC emissions decrease 14%–27% in hot mills. • Heat available for combustion in the reheating furnace doubled. • Electricity use increases in hot rolled steel life cycle. [ABSTRACT FROM AUTHOR]