Furnace Gas Research Articles

Spatio-temporal and multi-mode prediction for blast furnace gas flow

The reasonable and stable distribution of blast furnace (BF) gas flow is the basis for maintaining the smooth operation of BF. Therefore, the accurate detection of the gas flow distribution is essential in the BF ironmaking process due to the direct impact on productivity, stability, and efficiency. However, there is a significant challenge to capture the complex interactions and dynamic changes of the ironmaking process by single predictive mode and two-dimensional (2D) distribution, leading to a lack of flexibility and interpretability in dealing with different abnormalities. To address this issue, a novel spatio-temporal multi-mode approach for three-dimensional (3D) BF gas flow prediction is proposed in this article. First, Pearson correlation analysis is employed to evaluate correlated variables in the spatial dimension. The precise temporal correlations among the multiple variables are matched with mutual information (MI) to extract spatio-temporal variables. Next, the spatio-temporal variables are decomposed utilizing variation mode decomposition (VMD), and the noise is removed with integrated correlation analysis and Fourier transform (FT) to identify and retain the relevant information. Finally, the MI-VMD-Informer is innovatively proposed to establish three different prediction modes based on spatio-temporal features, thus obtaining 2D and 3D gas flow distributions. The superiority of the proposed method is verified by actual BF production data.

Modeling selective absorption of H2S from a gas mixture containing CO2 within rotating packed bed based on surface renewal theory

Compared to conventional packed beds (PBs), the rotating packed beds (RPBs) demonstrate superior selectivity for H2S. RPBs can selectively absorbing more than 99 % of H2S in CO2-rich gas mixtures, while the co-absorption rate of CO2 in RPBs is only 1/9 of that in PB columns. Therefore, RPBs have been well applied in the gas purification for natural gas, blast furnace gas, and refinery gas. While, modeling the selective reaction process in RPBs under conditions of rapid liquid film renewal remains challenging. Here, a diffusion–reaction mass transfer model based on surface renewal theory is established. The model elucidates the mechanism behind the selective absorption of H2S, and also demonstrate how RPBs enhance liquid film absorption. Experimental data collected from an RPB operating under actual conditions were used to validate the model. The model demonstrates high precision in predicting the removal efficiency of H2S and CO2.

Tailoring Li assisted CZTSe film growth under controllable selenium partial pressure and solar cells.

It is still critical to prepare a high-quality absorber layer for high-performance Cu2ZnSnSe4 (CZTSe) multi-component thin film solar cell. The gas pressure during the selenization process is commonly referred to as the pressure of inert gas in the tube furnace, while the exact selenium partial pressure is difficult to be controlled. Therefore, the grain growth under different selenium partial pressures cannot be made clear, and the film quality cannot be controlled as well. In this work, we use a sealed quartz tube as the selenization vessel, which can provide a relatively high and controllable selenium partial pressure during the selenization process. To further tailor the grain growth, lithium doping is also utilized. We find that lithium can greatly promote the growth of CZTSe films as the selenium partial pressure is controlled near the selenium saturation vapor pressure. Combined with ALD-Al2O3, the crystallization quality of CZTSe absorber films is significantly enhanced and the efficiency of CZTSe solar cells achieved a significant improvement. This work clarifies the effect of controllable Se pressure on CZTSe film growth and can lead to better results in CZTSe and other multi-compound thin film solar cells.

Study on Oxygen-Enriched Combustion Characteristics of Blast Furnace Gas Boiler

ABSTRACT To study the dynamic characteristics of OEC (oxygen-enriched combustion) in a BFG (blast furnace gas) boiler, the BFG boiler of an iron and steel enterprise is taken as the research object, and a thermal test bed for OEC of BFG is set up, and a thermodynamic simulation model of the BFG boiler is constructed based on the heat loss of chemical incomplete combustion obtained from thermal test, using MSP (Multi-Subject Simulation Platform). The effects of OC (oxygen concentration) and the position of oxygen entering the furnace chamber on the key parameters of the OEC process of the BFG boiler under different working conditions were analyzed. The results showed that the excess air coefficient of 1.2 and exhaust temperature of 120°C was kept constant during the thermal test. With a fuel volume of 2.4 Nm3/h, for example, after the OC was increased from 21% to 40%, the combustion flame temperature in the furnace was increased by about 34°C, the heat loss due to unburned gas was reduced by 0.21%, and the boiler efficiency was increased by 1.38%. In the dynamic model, at the instant when the OC is changed, the disturbance of the whole system is relatively large, and the FAT (furnace average temperature) outlet, the pressure of the steam ladle, and the MST (main steam temperature) will have a step change, and then gradually level off again. With the increase of OC, the combustion reaction is more and more intense, the steam side of the heat transfer process is strengthened, the boiler efficiency is improved, and the FAT chamber outlet, the steam ladle pressure and the MST after OEC in different ways of oxygen entry into the furnace chamber will be longer and longer to reach a stable value. The results of the study can provide a reference for the OEC operation of BFG boilers.

Performance analysis of a medical waste gasification-based power generation system integrated with a coal-fired power unit considering dispatching optimization

This paper collects into a medical waste plasma gasification, a cleaning system, a gas turbine, a syngas storage tank and a coal-fired power unit to establish the medical waste plasma hybrid peak shaving system. In this system, medical waste is transported into a plasma gasification furnace and prepared as syngas by reaction. Then, the syngas is delivered to the gas turbine after cooling and deacidification. Finally, the flue gas from the combustion of the gas turbine is used to heat the condensate of a coal-fired power unit. Compared to the coal-fired power unit, the system has a larger range of peak load capability. Establish the integrated regional power grid dispatching model. The paper selects five typical days, which combine the actual data to comprehensively consider many factors. Then analyze the optimal economy of the regional power grid and propose the optimal dispatch scheme for the regional power grid. After modification, the system energy efficiency is 37.38 %, and system exergy efficiency is 36.19 %. After the dispatching optimization, the average daily profit is 140.78 k$, the profitability can reach initial cost in 6.20 years, and the net present value generated by the medical waste plasma hybrid peak shaving system is 178,410.43 k$.

Effects of elevated oxygen content and temperature on the laminar burning velocity of the blast furnace gas in oxygen-enriched air condition

Oxygen-enriched air combustion holds promise as an effective method for harnessing blast furnace gas (BFG) in the steel industry. In this study, the laminar burning velocities of blast furnace gas were measured using the heat flux method under elevated oxygen mole fractions (0.3–1.0) and temperatures (303–353 K). Subsequently, the measured data were used to evaluate the GRI-Mech 3.0, Li, FFCM-1, and Konnov 2023 mechanisms. Comparisons between experimental and calculated laminar burning velocities revealed that the Konnov 2023 mechanism well predicts the experimental data at all conditions, while the predictions of the other three mechanisms deviate from the experimental data. The laminar burning velocities of blast furnace gas increased with elevated oxygen mole fraction and temperature. Interestingly, the peak of laminar burning velocity shifts from the fuel-rich side to the fuel-lean side with an increase in oxygen mole fraction, which is mainly due to the fuel-lean shift peak of adiabatic flame temperature and the higher diffusive properties of the gas mixture at fuel-rich side. The reaction CO+OH<=>CO2 + H emerges as the most significant reaction influencing laminar burning velocities. The elevated oxygen mole fraction reduces the dependence of the power exponent α on the fitted temperature range. Corresponding oxygen mole fractions for the blast furnace gas are determined to be 0.59 at φ = 0.8 and 0.93 at φ = 0.9, respectively, at which the laminar burning velocity of the BFG/O2/N2 mixture equals that of the CH4/Air mixture.

Thermodynamic Feasibility of Chemical Looping CO Production from Blast Furnace Gas Based on Fe-Ca-Based Carriers

Thermodynamic Feasibility of Chemical Looping CO Production from Blast Furnace Gas Based on Fe-Ca-Based Carriers

Efficient prediction for Blast Furnace Gas holder level using novel preprocessing techniques and weight correction strategy

Accurately forecasting the level of Blast Furnace Gas (BFG) holder, managing the balance of gas supply and demand, strategically allocating BFG brings substantial economic and social benefits. In order to address the issues of volatile fluctuation, strong temporal variability, and high uncertainty of BFG, this paper proposes an efficient system for predicting the BFG holder level. Variational Mode Decomposition is utilized to separate components with different frequencies. The number of modes is determined according to Energy Ratio. Improved Discrete Wavelet Threshold is employed to eliminate noise. The grid search approach adjusts the activation functions. What is more, Particle Swarm Optimization is used to correct the weights of subsequences and emphasize critical information. Experimental results demonstrate that Root Mean Squared Error of the system are 0.0411, 0.0423 and 0.0416 for the three real-time monitoring datasets in April 2021. The average improvement percentage for the second dataset is 67.5% when compared to other commonly models. It is obvious that the prediction errors are minimized, and the stability and generalizability of the hybrid prediction system are enhanced. Additionally, the performance of the system is further verified through Diebold–Mariano test, improvement percentage test, and effectiveness test.

Carbon-free power generation strategy in South Korea: CFD simulation for ammonia injection strategies through boiler burner configurations in tangentially fired boiler

To achieve carbon neutrality in power generation, incorporating ammonia-coal co-firing into coal-fired boilers effectively reduces CO2 emissions. Here, we aimed to optimize ammonia injection methods by investigating the feasibility of 20 % ammonia co-firing in a pulverized coal (PC) boiler through numerical simulations. These simulations aim to analyze the effects of different ammonia injection strategies and burner configurations on the combustion performance and NOx emission characteristics of a 500 MW tangentially fired PC boiler. Results showed that compared to using five burners, single-burner injection reduced outlet NO concentration by 22.72 ppm and unburned carbon content to 0.30 %, which is 0.80 % lower than multi-burner injection and even below the 0.45 % in coal-only combustion. The optimal case (burner A for ammonia injection) achieved a furnace outlet flue gas temperature of 1247.35 K, close to 1241.98 K in coal-only combustion, with the lowest NO emissions (193.89 ppm) among all ammonia co-firing cases. Positioning the single burner for ammonia injection revealed that utilizing the blending method with the ammonia injection burner, such as in the case of upper burner injection, increases both furnace temperature and high-temperature zone areas. However, employing in-boiler blending methods with lower-positioned burner ammonia injection distributes high-temperature zones more extensively. Comparing ammonia injection through coal and auxiliary oil burners, using only the lowest-level burner can significantly reduce NOx emissions while maintaining combustion and thermal efficiencies. This study is the first to simultaneously consider the number, position, method, and type of ammonia injection burners in large-scale commercial coal-fired boilers, providing a valuable reference for future research and practical boiler operations. This comprehensive analysis underscores how ammonia injection strategy and position can optimize ammonia-coal co-firing boiler performance.

Low-NOx thermal plasma torches: A renewable heat source for the electrified process industry

Industrial thermal plasma torches can heat a gas up to 5000–20,000 K, i.e., well above the temperature needed to replace the heat generated from the combustion of traditional fossil fuels (e.g., coal, oil, and natural gas) in large-scale process industry furnaces producing construction materials (e.g., iron, steel, lime, and cement). However, there is a risk for significant NOx emissions when air or N2 are used as plasma-forming gas since the temperature somewhere in the furnace always will be higher compared to the threshold NOx formation temperature of ∼1800 K. Torch NOx forms inside the high temperature region of the plasma torch (>5000 K) when air is used as gas. Process NOx forms instead when the hot gas (when air or nitrogen is used as plasma forming gas) from the plasma torch mixes with process air downstream the torch. By analysing the complex chemistry of both the torch- and process NOx formation with thermodynamic equilibrium and one-dimensional chemical kinetic calculations it was shown that adding H2 to the plasma-forming N2 gas significantly reduces the NOx emissions with more than 90 %. Verifying experiments with air, pure N2, and mixtures of H2 and N2 as plasma-forming gas were performed in a laboratory scale insulated laboratory furnace with different pre-heating temperatures of process air (293, 673, and 1073 K) which the plasma gas mixes with downstream the torch. Depending on the pre-heating temperature the NOx emissions were between 12,000–14,000 mg NO2/MJfuel when air was used as plasma forming gas. Substantial NOx emission reduction occurs both when N2 replaces air, where the NOx emissions was in the span of 8000–11,500 mg NO2/MJfuel and furthermore when H2 was mixed into the N2 gas stream. For the highest degree of H2 mixing (28.6 vol-%), the NOx emissions were between 450–1700 mg NO2/MJfuel depending on the pre-heat temperature of the process air, i.e., a reduction of 88–96 % and 85–94 %, respectively when air or N2 was used as plasma forming gas. The measured NOx emissions are then of the same order of magnitude as would be expected from the combustion of traditional fuels (coal, oil, biomass and pure H2). Finally, by analysing the aerodynamics in an axisymmetric furnace with an experimentally validated computational fluid dynamics (CFD) model using reduced chemistry for the NOx formation (19 species and 70 reactions), further guidelines into the process of NOx reduction from thermal plasma torches are given.

Effect of multi-component gas on removal of trace hydrogen sulfide activity from blast furnace gas using activated carbon adsorbent

Abstract In the steel industry, blast furnace gas (BFG) is huge with complex components. The existence of hydrogen sulfide (H2S) in the BFG can produce sulfur dioxide (SO2) after combustion, which will increase the source of SO2 pollution and make the desulphurization more difficult, to be threat to people health. At present, the removal of H2S by dry adsorption with modified activated carbon adsorbent is a high-precision and low-cost desulphurization method. However, the effect of complex gas components in BFG on the adsorption of H2S by activated carbon adsorbent is not sufficient. Based on the fixed bed adsorbent evaluation system, a new type of highly efficient copper-cerium oxide (Cu–Ce–O) modified activated carbon H2S adsorbent was developed. And the effects of carbon monoxide (CO), carbon dioxide (CO2), hydrogen (H2), oxygen (O2), sulfur dioxide and hydrogen chloride (HCl) in BFG on the desulfurization activity of adsorbents were investigated. The results showed that the performance of H2S removal decreased in the presence of CO, CO2, HCl and SO2, and improved in the presence of H2 and O2. Other parameters were also studied which might influence the process. The application of modified activated carbon adsorbent in simulated BFG is basically stable. According to the fitting results of adsorption kinetics for the five adsorption models, as the atmosphere becomes BFG from N2, pore diffusion becomes the main adsorption form. However, the effects of internal diffusion, chemical adsorption and external mass transfer decreased. The Bangham model is the most suitable model to describe H2S adsorption process.

Looking beyond energy efficiency targets: Life cycle sustainability of mechanical and water heating equipment in Canadian homes

The building sector's impacts on climate are widely acknowledged, leading to policies and standards promoting energy-efficient buildings. In order to achieve sustainability in a holistic sense, the environmental, social, and economic impacts of equipment used in buildings need to be evaluated. In this regard, a novel decision support framework is introduced to evaluate the heating and cooling equipment in single-family detached homes. Energy simulation, life cycle environmental, social, and economic analyses, and a multi-criteria decision-making method are used to identify the most sustainable set of equipment. This framework is demonstrated through its application on mechanical and water heating equipment in three existing residential buildings of varying energy efficiencies (low, medium, and high, the latter being net-zero home) over a 50-year study period.The results indicate that the carbon footprint of a natural gas furnace is six times higher than that of other equipment. In contrast, the drain water heat recovery unit showed the lowest impacts attributed to lower material and energy usage. For most equipment, the product stage accounted for more than 50% of the total impacts. When grouped, the equipment in the low-efficiency home showed the highest environmental impacts, while the equipment in the medium-efficiency home had higher social and economic impacts. Overall, the equipment set in a net-zero home is the best choice under equal, pro-social, and pro-economic scenarios and only lags behind the equipment set in a medium-efficiency home for pro-environmental scenario. The work will help improve sustainable building policies beyond immediate energy and operational cost savings.

Exploring enhanced CO2 separation from blast furnace gas: A multicolumn vacuum swing adsorption approach with process design and experimental assessment

Excessive emissions of carbon dioxide (CO2) are a major driver of global warming. Blast furnace gas (BFG) represents a major source of CO2 emissions in the steel industry, accounting for approximately 30 % CO2 emissions among the industry sectors. Hence, effective CO2 capture from BFG is imperative. This study presents an approach utilizing the vacuum swing adsorption (VSA) technology to capture CO2 from BFG. A 6-column VSA rig was designed and constructed to separate CO2 from a simulated BFG (CO2/N2 = 20 %/80 %) using zeolite 13X as adsorbents. The VSA process involved steps of adsorption, desorption, heavy product purge, light product re-pressurization, and pressure equalization. Five different process modes, i.e., 1-column and 3-step, 2-column and 6-step, 2-column and 8-step, 3-column and 9-step, and 4-column and 16-step configurations, were implemented to evaluate the influence of various process design factors on the separation performance. Additionally, a 6-column and 36-step process was devised to conduct a parametric study of VSA cycles by varying the adsorption duration and desorption pressure. Results revealed the pivotal role of heavy product purge and pressure equalization on the separation performance. The six-column process achieved a CO2 purity and recovery of 94 % and 82 %, respectively, with a energy consumption of 0.76 GJ/tonCO2 when employing a desorption step duration of 240 s and pressure of 8 kPa. In addition, a method of process optimization based on the bed capacity ratio, C, was introduced in this study, which provides a dimensionless quantity of the utilization of the adsorption column. Moreover, capturing CO2 from BFG through the VSA cycle not only enhances its heating value but also yields substantial advantages in terms of mitigating CO2 emissions.

Retrofitting homes in Ontario entails significant embodied emissions: new policies needed

ABSTRACT Emissions reduction policies and programs should consider both the operational emissions reduction from single family home retrofits and the embodied emissions of the retrofit materials. This is because it can take 0.9–10.1 years before the emissions savings from building envelope upgrades in a gas-heated home equal the embodied emissions from the materials used. The wide range reflects the range of embodied emissions for different insulation and window replacement options. Heat pumps also have significant embodied emissions from their manufacture and from refrigerant leaks, but it takes less than two and a half years of operations in Ontario to offset the emissions investment relative to heating with a gas furnace. We recommend that Canada accelerate the phase out of insulation materials with high embodied emissions and increase incentives for window replacements. Programs and policies should also consider the age of the home and the potential energy savings when recommending building envelope improvements to maximize the total emission reduction potential. Finally, heat pumps should be promoted in all homes where low carbon electricity is available because this is the simplest and most effective way to reduce carbon emissions, especially when embodied emissions are considered.

Parameter study of waste shiitake substrate/waste polyethylene Co-gasification using Aspen Plus kinetic modeling

Waste Shiitake Substrate, a major agricultural waste in Taiwan, is typically packaged in plastic bags (Waste Polyethylene, PE) during mushroom cultivation process. Consequently, these plastic bags become additional waste that requires proper disposal. In recent years, Taiwan has produced over 150,000 tons of waste shiitake substrate annually, with approximately 1580 tons of plastic bags used for mushroom cultivation. Up to now, there has not been an effective method for handling this waste. This study aims to develop a co-gasification process using the complementary characteristics of WSS and PE. Unlike traditional direct combustion, the co-gasification approach can convert these wastes into cleaner bioenergy. This study aims to develop an Aspen Plus model for a laboratory-scale 1 kWth bubbling fluidized bed gasifier. This model incorporates kinetic reactions and tar formation during co-gasification. The model accurately predicted the experimental results. Different variables were investigated, including gasifier temperature, blending ratio (BR) of the two fuels, mixing ratio (MR) of the gasifying agent, and equivalence ratio (ER). The results showed that hydrogen production correlated positively with the steam-to-carbon ratio in the gasification medium, whereas carbon monoxide (CO) was more affected by the feedstock type and equivalence ratio, with CO reaching its peak at an equivalence ratio of 0.2. When gasifying using only waste shiitake substrate (BR = 0%), at an ER of 0.2, a gasification furnace temperature of 950 °C, and an MR of 100% (pure CO2), the maximum CO mass flow rate in the syngas is obtained. Waste plastics contain significant amounts of volatile matter and no oxygen, leading to increased production of CH4, CO, and H2 during co-gasification with the addition of waste plastic. For plastics, high temperature and low ER conditions promote the production of CO, H2, and CH4 because of the significant tar content, thereby enhancing the Cold gas efficiency (CGE). When the gasification temperature is 950 °C, with 80% polyethylene (BR = 80%) and an ER of 0.1, the highest HHV is achieved. These results can serve as a reference for determining the operational conditions for the scale-up of gasification systems.

Influence of RED‐II Calculation Rules on the Carbon Footprint of Methanol E‐Fuel

AbstractThe carbon footprint of methanol from cradle‐to‐grave is evaluated using three process concepts to capture CO2, i.e., one using CO2 from direct air capture (DAC) and the other two utilizing CO2 from a steel mill's blast furnace gas (BFG). Hydrogen is supplied by onsite electrolysis, or from a German offshore wind park, or an Australian solar park with ammonia as hydrogen carrier. The study is of interest to life cycle assessment (LCA) practitioners, policymakers, and industries’ management who are involved in regulating, planning, implementing, and operating projects which aim to produce fuels using hydrogen from electrolysis (so‐called ‘e‐fuels’). The influence of assumptions in the RED‐II delegated act regarding recycled carbon fuels and renewable liquid and gaseous fuels of non‐biological origin on the carbon footprint results is examined. The RED‐II assumption regarding the credits for captured CO2 after 2041 indicate that DAC‐based concepts are advantageous with respect to BFG, although the LCA results indicate the opposite. Using green hydrogen from nearby locations reduces carbon footprints more than faraway locations due to transport‐related emissions.

Simplified oxygen-limited thermal treatment without tube furnace and inert gas

The article introduces a cost-effective and user-friendly alternative to traditional pyrolysis techniques, obviating the necessity for intricate tube furnaces and inert gas environments. This novel approach employs materials capable of reacting with and sequestering oxygen to establish an oxygen-depleted atmosphere. The experimental setup entails positioning a crucible containing the sample inside a ceramic pot, enveloped by varying sizes of wood coal particles, and subsequently subjecting the ceramic pot to furnace conditions. Utilizing this oxygen-limited strategy, a biochar sample, derived via hydrothermal processing, underwent carbonization at 650°C for 6.5 hours, with outcomes compared against ambient condition carbonization under identical temperature and duration parameters. Gravimetric analysis revealed that wood coal effectively curtails oxygen availability, augmenting biochar yield from 1.53 % to 19.50 %. Fourier-transform infrared spectroscopy (FTIR) indicates diminished oxygen functional groups, while X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM) affirmed a denser, compact carbon structure in biochar produced under oxygen-restricted conditions versus ambient conditions. The carbon content percentage in biochar samples treated at 650°C for 6.5 hours under both conditions was assessed via energy-dispersive X-ray spectroscopy (EDX) data. The emergence of a novel carbon nanomaterial, derived from biomass waste through our oxygen-limiting method, may exhibits applications in energy storage and water purification. Our approach offers simplicity, cost-efficiency, and straightforward implementation while upholding the integrity of pyrolysis/thermal treatment within inert conditions, ensuring the robustness of the procedure.

Experimental Validation of Stationary and Transient Models of a Methanol Demonstration Plant

AbstractThe system integration of cross‐industrial networks in the Carbon2Chem® project relies on numerical simulations. Hence, this study validates the methanol synthesis loop models vs. the measurements from a demonstration plant, focusing on the thermodynamic, kinetic, and dynamic aspects. The plant can produce up to 500 L per week of methanol from real blast furnace gases of the thyssenkrupp steel plant in Duisburg. Despite its small size, it comprises a recycle gas loop and an original reactor tube of 6 m in length. After validation, the simulation models are used to analyze the dynamic operation limits of the plant, and they are transferred to the model of an industrial size to analyze the operation of cross‐industrial networks with volatile boundary conditions.

Experimental constraints on iron and sulfur redox equilibria and kinetics in basaltic melt inclusions

The oxidation states of dissolved iron (Fe) and sulfur (S) in silicate melts were studied experimentally by heating Hawaiian olivines containing S-bearing melt inclusions (MIs) in a 1 atm gas-mixing furnace. The MIs are closed with respect to S and C, but equilibrate with the oxygen fugacity (ƒO2) and water fugacity (ƒH2O) of the furnace. We also conducted experiments using a S-free synthetic Hawaiian MI composition held on Pt-loops. Experiments were run at 1225 °C for 8–96 hr in H2-CO2 gas mixtures corresponding to ƒO2 values that varied over seven orders of magnitude and then drop-quenched into water. Time-series experiments show that MI Fe3+/Fe2+ and S6+/S2− ratios reached constant values within ∼24 hr. The H2O contents of the Pt-loop glasses and the dehydrated MIs overlap and are proportional to the fH2O in the furnace gas. The slope of log10(Fe3+/Fe2+) vs. log10ƒO2 is 0.25±0.02(2σ) for the Pt-loop glasses and 0.23±0.01(2σ) for the quenched MIs; the slopes of the two sets of experiments are consistent with equilibrium having been reached via the reaction FeO + ¼ O2 = FeO1.5. S-bearing quenched MI glasses have Fe3+/Fe2+ ratios that are systematically low compared to ratios measured in the S-free Pt-loop glasses run at the same T and ƒO2; this may reflect an effect of S on Fe3+/Fe2+, although further experiments are needed to explore this possibility. S6+/S2− ratios in the experimental melt inclusions vary systematically as a function of ƒO2, and the measured ratios agree with independent calculations of S oxidation state in basaltic melts.After being held at 1225 °C for 24 or 48 hr, a subset of olivine-hosted MIs were cooled at rates of 1700–40,000 °C/hr and quenched at temperatures between 900 °C and 1150 °C to explore whether Fe and S speciation are modified during cooling. Fe and S speciation in isothermal and cooled MIs held initially at the same ƒO2 overlap within uncertainty, suggesting that the T dependence of the homogeneous reaction 8Fe3+ + S2− = 8Fe2+ + S6+ is small and/or its kinetics are sluggish relative to cooling rates required to quench basaltic liquids to glasses. The centers of unheated, naturally quenched MIs from Papakōlea, Hawaii with syneruptive cooling rates ranging from ∼50 to 12,000 °C/hr were also measured for Fe and S speciation. MIs that experienced the lowest cooling rates have higher Fe3+/Fe2+ and S6+/S2− ratios relative to rapidly cooled inclusions of comparable size. The increase in Fe3+/Fe2+ is due to olivine crystallization on the inclusion walls during cooling and diffusion of the resulting oxidized boundary layer into MI interiors. Diffusive modification is minimized in MIs that have been rapidly cooled and/or are sufficiently large such that the oxidized boundary layer is restricted to a narrow region adjacent to the inclusion walls. Our experiments and their comparison to naturally quenched MIs show that measurements of Fe3+/Fe2+ and S6+/S2− ratios in quenched basaltic glasses and in the centers of rapidly cooled and/or large MIs are likely to be representative of the redox state in the melt at magmatic temperatures prior to quenching to glass.

1.05 MW molten salt furnace experimental investigation of full-conditional thermal energy storage for the transfer and storage of waste heat from blast furnace gas

This paper proposes the use of heat storage devices and technologies to convert the unstable heat of gas generated by the iron and steel industry into stable heat, thus realizing the controllable and stable utilization of the gas waste heat. To this end, a 1.05 MW molten salt furnace energy storage experimental system was developed, utilizing a spiral coil type molten salt furnace to heat solar salt and achieve energy transfer and storage. The study comprehensively analyzes the preheating, heating, cooling, and special working conditions of the molten salt furnace. The experimental results demonstrate that the coils can be preheated within 150 min and heats the solar salt to over 570 °C at the rated load. However, the vertical and axial directions of the coil exhibit varying degrees of thermal stress under different operating conditions. In addition, the Reynolds number and Nusselt number of the heat transfer process were calculated and the convective heat transfer correlation equation was fitted using the similarity principle to find the heat transfer efficiency of the molten salt furnace of 77.12 %. These findings are expected to address the waste blast furnace gas issue and contribute to developing a sustainable energy system in the steel industry.