Furnace Gas Research Articles

Synthesis of AlPO-18 Zeolite Membrane by Sonication-Assisted Hydrothermal Method for H2 Separation from Blast Furnace Flue Gas

In this study, AlPO-18 zeolite has been synthesized at temperatures ranging from 140° to 180°C and varying synthesis time from 3 to 20 h using sonication mediated hydrothermal process. The characterization results of the synthesized powders and membranes revealed that phase pure AlPO-18 zeolite has been formed at 150°C for 15 h under sonication energy of 250 W. For comparison, the same has been synthesized by the conventional method for 200°C and 69 h. In the sonochemical process, H2O molecule splits into hydrogen radicals (H•) and hydroxyl (•OH) radicals with intense local heating and high pressure during the collapsing of cavitation, which initiates the formation of dihydrogen phosphite (H2PO3•) and dihydrogen phosphate (H2PO4•) radicals and facilitate the formation of AlPO-18 zeolite. Finally, the performance of the membranes has been studied with varying feed pressures for different binary gas mixtures and single gases, and simulated blast furnace (BF) gas has been used to study the separation efficiency of the membranes. The highest separation factors, calculated from BF mixture gas of H2/CO2 and H2/N2 have been achieved as 8.7 and 21, respectively. These results show the possibility of hydrogen recovery from BF flue gas to convert waste to wealth.

Study and mechanism of formation of phosphorus production waste in Kazakhstan

Abstract This article contains information about the accumulated industrial waste from phosphorus production and methods for its recycling and disposal to produce marketable products. Monitoring of cottrel dust’s impact on the environment, namely, ground and surface water, soil, and atmosphere was carried out. The mechanism of formation of cottrel dust was studied. The dispersed, chemical, and phase compositions of the dust in furnace gases during the electrothermal smelting of phosphorites were determined. The sequence of chemical reactions during the formation of cottrel dust was elucidated. The ratios of initial components entering the chemical reaction and the thermodynamic parameters (Gibbs energy) were determined using the Chemistry HSC-6 software package. IR spectral and elemental analyses were carried out for determining cottrel dust’s functional groups and elemental composition. Based on modern instrumental studies, it was found that the total content of phosphorus(v) oxide in cottrel dust was 30.7%. This content of phosphorus(v) oxide is sufficient to use cottrel dust as an initial raw material for producing phosphorus-containing fertilizers. This method was proposed for processing cottrel dust to produce monocalcium phosphate on a production scale. The chemical composition of the resulting monocalcium phosphate was determined and confirmed by analytical methods. The proposed technology for producing monocalcium phosphate from cottrel dust is recommended for use in the agro-industrial complex.

Effects of cooling rate upon annealing on the microstructure and properties of the FeCo49V2Nb0.2 alloy

In this paper, the influence of heat treatment on the magnetic properties of permendur the FeCo49V2Nb0.2 alloy used as the rotor core of a generator is investigated. The as-cast alloy is forged, hot and cold rolled to a thickness of 0.2 mm. The alloy samples were annealed in an argon gas furnace at different cooling rates. The results of measuring properties using the vibrating sample magnetometer method and measuring hardness show that the cooling rate has a significant impact on the properties of the FeCo49V2Nb0.2 alloy. Combining X-ray diffraction analysis and microstructure analysis allows us to explain the changes in properties obtained. From the results obtained, a conclusion can be drawn about the appropriate cooling rate for this alloy to achieve the best magnetic properties.

Computational fluid dynamics simulation on oxy-fuel combustion performance of a multiple-burner furnace firing coking dry gas

In heat production and power generation utilizing carbon-based fuels, oxy-fuel combustion is regarded as a potential method for carbon capture and sequestration. However, few studies, if any, have been performed on the impacts of exhaust dehydration efficiency and oxygen purity on the parameters of oxy-fuel combustion. In the current study, based on the experimental data, the oxy-fuel combustion characteristics of coking dry gas (CDG) in a gas-fired furnace were investigated using the computational fluid dynamics approach. The simulation results illustrate that the CO2 concentration in the flue gas could rise by nearly 14% as the dehydration efficiency increases from 0.60 to 0.95. The contents of CO2 elevate with the oxygen purity, while H2O and N2 show an opposite trend. Within the scope of the present study, an O2 content of 32% and an excess oxygen ratio of 1.1 are recommended given the combustion performance and economic issue. Due to the impacts of combustion performance, cost of ASU, CO2 enrichment, and so on, the selection of oxygen purity needs to be considered comprehensively. The content of N2 declines with the increase of the dehydration efficiency, which benefits the enrichment of CO2. The present work contributes to the clean and efficient utilization of combustible exhaust gas and provides further knowledge on green and low-carbon development.

Achieving equitable space heating electrification: A case study of Los Angeles

A major step towards residential building decarbonization is the electrification of natural gas space heating. Current inequities such as limited access to cooling technologies and high energy burden can be addressed in transition if we take steps now to understand the economic impacts of different electric technologies. This study presents a novel high-resolution techno-economic model, the Marginal Net Present Value Upgrade Analysis model, which improves upon existing literature that examines the economics of electrifying space heating through a more detailed cost calculation and the use of a variable discount rate. Results show that 1) electrifying with heat pumps is only recommended for owners who are replacing a natural gas furnace and central AC system, 2) renters are highly vulnerable in this transition in that electric resistance technologies are the least capital intensive technology for landlords to install, with renters bearing the increased operational cost, 3) rebates from the Inflation Reduction Act of 2022 allow most qualifying landlords and owners to install even the highest efficiency heat pumps at a net savings when compared to the baseline heating and cooling system, and 4) reducing capital costs are more critical than altering utility rates to achieve high heat pump penetration. The model developed herein can support decision-making related to electrification and energy efficiency policy and rulemaking and will give insight into the impact residential building electrification can have on marginalized communities.

Tailored Cu-Fe-based oxygen carrier for moderate-temperature chemical looping hydrogen generation from blast furnace gas

Chemical looping hydrogen generation (CLHG) offers a promising solution for producing H2 from industrial off-gas, such as blast furnace gas. However, increasing H2 production capacity of the oxygen carrier (OC) at moderate temperature remains a significant challenge. In this study, a novel Cu-Fe-based OC is tailored for moderate-temperature CLHG from blast furnace gas. The results demonstrates that the tailored OC exhibits a superior H2 production capacity of 12.99 mmol·g−1 at 550 °C, which is 6.5 times higher than that of Fe2O3 at the same temperature. The addition of Cu leads to the formation of oxygen defects, which facilitate the migration of lattice oxygen, thereby the activity of the OC is enhanced. Furthermore, cyclical experiments demonstrates that O2-assisted regeneration strategy can effectively suppress the segregation of Cu during the cycling process, and the tailored OC shows good stability during 10 redox cycles. No additional separation process was required and the purity of the hydrogen was higher than 99%. The findings here open a new avenue for efficient CLHG from industrial off-gas at moderate operation temperature.

Analysis of the Impact of Plasma Jet Mode on Medical Waste Gasification Furnace

Analysis of the Impact of Plasma Jet Mode on Medical Waste Gasification Furnace

Analyzing the methanation thermodynamic feasibility of steel plant byproduct gases

To improve the utilization of byproduct gases in the steel plant, the coke oven gas (COG) methanation combined with blast furnace gas (BFG) and basic oxygen furnace gas (BOFG) was proposed in viewpoint of economy and environment. The optimization mathematics model based on Gibbs free energy minimization was established to predict the thermodynamic feasibility of the proposed methanation. To solve the proposed model, the convenient method was implemented by using the Gibbs module in Aspen Plus software. Effects of operation parameters on the methanation performance were revealed to identify the optimized conditions. To reduce the solid carbon concentration, it was found that the optimized conditions of temperature, pressure and stoichiometric number were 650 °C, 30 bar and 3.0, respectively. Moreover, it was discovered that 10 mol% of BFG or BOFG could be mixed into COG to obtain the maximum methane yield. In addition, it was testified that there were the good agreements between calculated results and industrial and published data, which indicated that the proposed methanation was thermodynamically feasible. Therefore, the simple and easy method was developed to evaluate the methanation operating conditions from the aspect of thermodynamic equilibrium, which provided the basic process conditions of byproduct gases methanation to enhance the steel plant efficiency and reduce carbon emissions.

The valorisation of steel mill off-gas via chain elongation into higher value-added products: A prospective life cycle assessment

Nowadays, one of the greatest challenges for the steel industry is decarbonisation to decrease its pressure on the environment. For this purpose, deploying carbon capture and utilisation technologies such as syngas fermentation can be instrumental, as they allow carbon in steel mill off-gas to be converted into ethanol. However, as ethanol is of relative low value, technologies that can upgrade it towards higher-value chemicals are becoming attractive. One such a technology is chain elongation, as it can convert ethanol effluents from syngas fermentation into caproic acid, which can subsequently be used as a feedstock to produce chemicals such as plasticisers. As information regarding the environmental sustainability of chain elongation is limited, in this study, a prospective environmental hotspot analysis on chain elongation was performed, assessing climate change and resource footprint indicators, from a Life Cycle Assessment perspective, based on a theoretical scale-up. In addition, climate change impacts of a novel basic oxygen furnace gas (BOFG) to plasticiser value chain integrating the theoretically scaled-up chain elongation technology (PLAST) were assessed and compared with two other valorisation routes, considering a US and a European scenario: BOFG incineration with electricity production (ELEC) and syngas fermentation for the production of ethanol for use as a fuel (ETOH). The hotspot analysis showed that electricity and chemicals consumption, mainly K-acetate, were the largest contributors to both the climate change and resource consumption footprint. For the US scenario, the novel PLAST route showed similar climate change impacts to the ETOH route, while the impacts were 15% higher than those of the ELEC pathway. In the European scenario, with a greener electricity mix, the PLAST route showed similar impacts compared to both the ELEC and ETOH routes. Although uncertainties lie within the results, this study highlights the potential of chain elongation as a part of an alternative carbon capture and utilisation pathway for the steel industry. For this however, further technological advances are required, such as changes in process configurations and increases in caproic acid productivity, which should be the focus of future research.

Study of thermal properties and stresses in a 1.05 MW molten salt furnace for recovering and storing blast furnace gas waste heat

Utilizing a molten salt furnace to recover waste heat from blast furnace gas and storing it in high-temperature molten salt represents an innovative solution for steel waste heat recovery systems. In this study, a 1.05 MW spiral coil vertical molten salt furnace thermal energy storage system was constructed. During the thermal storage experiment under a 75 % heating load, the system achieved a heating efficiency of 74.57 % and a molten salt temperature of 560.3 °C. To analyze the thermal performance and thermal stress of the molten salt furnace, a three-dimensional transient numerical computational model using ANSYS Fluent and Matlab software was developed. A two-dimensional thermoelastic model was employed to assess the thermal stress of the spiral coil. The deviations between the experiment and simulation for the molten salt outlet and coil temperature were 1.40 % and 1.66 %, respectively. Furthermore, the three-dimensional temperature and thermal stress distributions under the benchmark case were simulated, finding that the maximum coil temperature reached 574.20 °C, while the maximum coil stress was 446.30 MPa. Increasing the heating load, molten salt inlet temperature, and time all lead to increased equivalent thermal stress. However, the location of the coil radius at 16 mm showed a minor sensitivity to heat flow density. Additionally, increasing the molten salt inlet mass flow rate by 0.1 kg/s resulted in a 2.99 MPa reduction in equivalent thermal stress. This paper provided valuable insights into the thermal properties and evolution of thermal stresses during the heating process in molten salt furnaces, offering a promising approach for recycling blast furnace gas in steel plants.

Aspen Simulation Study of Dual-Fluidized Bed Biomass Gasification

This article establishes a thermodynamic model of a dual-fluidized bed biomass gasification process based on the Aspen Plus software platform and studies the operational control characteristics of the dual-fluidized bed. Firstly, the reliability of the model is verified by comparing it with the existing experimental data, and then the influence of different process parameters on the operation and gasification characteristics of the dual-fluidized bed system is investigated. The main parameters studied in the operational process include the fuel feed rate, steam/biomass ratio (S/B), air equivalent ratio (ER), and circulating bed material amount, etc. Their influence on the gasification product composition, reactor temperature, gas heat value (QV), gas production rate (GV), carbon conversion rate (ηc), and gasification efficiency (η) is investigated. The study finds that fuel feed rate and circulating bed material amount are positively correlated with QV, ηc, and η; ER is positively correlated with GV and ηc but negatively correlated with QV and η; S/B is positively correlated with GV, ηc, and η but negatively correlated with QV. The addition of CaO is beneficial for increasing QV. In actual operation, a lower reaction temperature in the gasification bed can be achieved by reducing the circulating bed material amount, and a larger temperature difference between the combustion furnace and the gasification furnace helps to further improve the quality of the gas. At the same time, GV, ηc, and η need to be considered to find the most optimized operating conditions for maximizing the benefits. The model simulation results agree well with the experimental data, providing a reference for the operation and design of dual-fluidized beds and chemical looping technology based on dual-fluidized beds.

Determination of an axial gas cyclone separator cut-off point by CFD numerical modeling

Determination of an axial gas cyclone separator cut-off point by CFD numerical modeling

Development and Characterization of a Remanufactured Motorcycle Clutch Hub from End-of-Life Aluminium Alloy

This study aims to employ reverse engineering in the development of the Yamaha CY 80 motorcycle clutch hub using end-of-life (EOL) aluminium alloy obtained from automotive vehicle scraps. The remanufactured motorcycle clutch hub underwent characterization and transient thermal analysis by integrating the geometric and structural features of the clutch hub. The EOL aluminium was thoroughly washed with a sodium hydroxide (NaOH) solution, cleaned with running water, and dried under sunlight to remove impurities trapped on the metal surfaces. The EOL aluminium alloy was melted in a gas furnace, and the molten metal was cast into the clutch hub using a permanent mold designed with the geometric features and characteristics of the Yamaha CY 80 motorcycle clutch hub. The EOL aluminium alloy was characterized using Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). The remanufactured CAD model of the Yamaha CY 80 motorcycle clutch hub was subjected to transient thermal analysis using ANSYS Workbench to predict the thermal behavior of the clutch hub during operation. The FTIR spectra exhibited the following distinctive bands: Al-O stretching modes in octahedral and tetrahedral structures, as well as symmetric bending of Al-O-H, with wavenumbers between 340 and 3131 cm-1 for -OH bonds and between 2109 and 1688 cm-1 for H-O-H bonds. The SEM-EDS micrographs indicated that the two main elements were bromine and silicon. Results from the transient thermal analysis indicated that the minimum and maximum temperatures were 40.109 °C and 250.09 °C within a time frame of 240 seconds. The maximum total heat flux was 30,271,000 W/m2. The compressive yield strength and tensile yield strength obtained in this study were 280 MPa, while the ultimate tensile strength was measured at 310 MPa. The alternating stress levels ranged from 62.05 MPa to 275.8 MPa. This study established that the material is susceptible to fatigue failure, as the alternating stress levels were below the material’s yield strength of 280 MPa.

ЕФЕКТИВНІСТЬ ВИКОРИСТАННЯ НИЗЬКОКАЛОРІЙНОГО ПАЛИВА В ПРОТИТОЧНИХ ВАПНЯНО-ВИПАЛЮВАЛЬНИХ ПЕЧАХ

Highly expensive energy carriers require revision of the existing engineering approaches in heating of industrial furnaces. The paper presents the results of research into the performance of a shaft kiln for lime-stone burning, which was fired with mixtures of natural gas and a fuel gas of a low calorific value. On the basis of studying various schemes of fuel distribution between the burners, the optimal operation mode of the kiln with reduced consumption of natural gas by 30% was identified. The lime quality indicators increase when the blast furnace gas is supplied to the central burner and improve when supplied to the peripheral burners. The joint supply of blast furnace gas in the calorific value section of the natural blast furnace mixture 9.4 ÷ 35 MJ/m3 allows keeping the performance of the furnace unchanged. At the same time, the coefficient of replacing natural gas with blast furnace gas is close to unity The proposed mode of heating the furnace with a capacity of 200 t/day with a natural blast furnace mixture provides 30% natural gas savings

Physical mixing of K2CO3/Al2O3 and poly(divinylbenzene) to promote COS removal from blast furnace gas with high humidity at low temperature

Blast furnace gas (BFG) is a high emission and widely used secondary energy source. However, the presence of sulfide in BFG leads to environment pollution. Carbonyl sulfide (COS) is the main (70 %) sulfide in BFG. Catalytic hydrolysis is an important method for COS removal, but the excessive water contained in BFG can significantly inhibit the performance of hydrolysis catalyst. In present work, K2CO3 was loaded on Al2O3 support using wet impregnation method to improve its hydrolysis efficiency. Moreover, a physical mixing method was employed to combine K2CO3/Al2O3 with hydrophobic poly(divinylbenzene) (PDVB) to improve the water resistance of K2CO3/Al2O3. It was found that a simple physical mixture of PDVB with K2CO3/Al2O3 could modulate the local environment of K2CO3/Al2O3, shifting the water-sorption equilibrium on the surface of the catalyst and releasing partial water-covered catalyst surface for hydrolysis. Under the reaction temperature of 90 °C and water vapor content of 34.4 g/m3, the hydrolysis efficiency of COS increased by ∼22.5 % via mixing K2CO3/Al2O3 with PDVB. This approach demonstrates the potential to enhance the hydrolysis efficiency of catalyst for COS removal from BFG with high humidity at low temperature, which is crucial for the practical application of desulfurization of BFG.

Exploring Extreme Voltage Events in Hydrogen Arcs within Electric Arc Furnaces

This study highlights the potential utilization of hydrogen gas in electric arc furnaces for achieving cleaner and more sustainable steel production. The application of hydrogen offers a promising path for reducing carbon emissions, enhancing energy efficiency, and advancing the concept of “green steel”. This study employs a 2D axisymmetric induction-based model to simulate an electric arc under atmospheric pressure conditions. We conducted numerical simulations to compare compressible and incompressible models of an electric arc. The impact of compressibility on hydrogen arc characteristics such as arc velocity, temperature distribution, and voltage drop were investigated. Additionally, different applied current arcs were simulated using the compressible model. When compared to an incompressible arc, the compressible arc exhibits a higher voltage drop. This higher voltage drop is associated with lower temperatures and lower arc velocity. A rise in applied current results in an upward trend in the voltage drop and an increase in the arc radius. In addition, the increased applied current increases the probability of voltage fluctuations. The voltage fluctuations tend to become more extreme and exert more stress on the control circuit. This has an impact on emerging electric arc technologies, particularly those involving the use of hydrogen. These fluctuations affect arc stability, heat output, and the overall quality of processes. Thus, the precise prediction of voltage and the ability to stabilize the operation is critical for the successful implementation of new hydrogen technologies.

Application of laser surface detection technology in blast furnace gas flow control and optimization

Abstract The gas flow distribution inside a blast furnace affects its smelting. Laser surface detection technology can control the gas flow distribution and promote the stable and smooth running of blast furnace by observing and adjusting the surface condition in the blast furnace in real-time. The laser surface inspection technology in blast furnace gas flow control and optimization was introduced, with Masteel 4,000 m3 blast furnace as an example. The results showed that the 30 W high-power laser had good penetration performance and could obtain clear scanning images of the material surface. In the process of strengthening smelting, the laser detection system determined that the central airflow of blast furnace was insufficient, resulting in a decrease in furnace condition stability, and promptly took measures to adjust the angle of the mineral coke fabric equipment and lifting line. After adjusting the material line, the central airflow was properly suppressed and stabilized, the angle of edge platform increased, the airflow developed properly, and two suitable gas flows were formed, which finally stabilized the furnace condition. Meanwhile, the small duct airflow other than the central airflow was found in time through the laser detection system, which provided conditions for operators to take measures to effectively eliminate the duct airflow, thereby avoiding big impacts on the blast furnace operation and technical and economic indexes. Therefore, the laser surface detection technology could effectively judge the gas flow distribution in the furnace, which contributed to timely adjustment of process parameters and optimization of blast furnace operation.

Dicalcium ferrite: A chemical heat pump in integrated carbon capture and chemical looping combustion for the steel industry

An integrated calcium and chemical looping combustion using dicalcium ferrite (Ca2Fe2O5, C2F), a mixed phase from iron and calcium oxides, is proposed here to remove carbon (CO + CO2) contained in the blast furnace gas from the steel industry. C2F is particularly attractive in chemical looping hydrogen production due to its lower PO2, therefore C2F can split steam into H2. Here, the low PO2 property allows C2F to have endothermic combustions in CO and H2 combustion (Stage 1 in the carbonator). The heat of combustion is chemically stored as reduced-carbonated C2F to be utilised for sorbent regeneration (Stage 2 in the calciner), essentially pumping the heat from the carbonator to the calciner. Combustion that occurred at PCO/PCO2 of the typical BFG in which the C2F should have not been able to combust CO, suggesting an enhanced combustion phenomenon. Experiments demonstrated in a fluidised bed and a thermogravimetric analyser led to indications that rather than following reaction pathways in an order of (i) C2F is reduced into CaO and metallic Fe and (ii) the CaO is absorbed CO2 in Stage 1, C2F might directly form Fe + CaCO3 under a mixture of CO and CO2, allowing the C2F to react with BFG. Reincorporation of the reduced-carbonated oxides into C2F drives lower decarbonation temperatures compared to CaO alone, suggesting a promising route to improve energy efficiency in capturing carbon in the hard-to-decarbonise steel industry.

Performance and economic analysis of a molten salt furnace thermal energy storage and peaking system coupled with thermal power units for iron and steel gas waste heat recovery

A new peaking system utilizing a molten salt furnace energy storage system coupled with a blast furnace gas thermal power unit in a steel mill is proposed, which stores excess blast furnace gas thermal energy in molten salt and releases the thermal energy for power generation during peak power demand. The heating efficiency of 74.57% is experimentally verified by building a molten salt furnace, and a 135 MW blast furnace gas thermal power unit is simulated using modeling to explore the energy storage and peak shifting performance and economic feasibility of the system. The results show that during the charging phase, the system can recover up to 9.361 t/h of standard coal, increasing the low valley regulation ratio to 20.31% with the increase of extraction rate. During the discharging phase, the system can provide an additional 17.42 MW of generating power, with a peak modulation ratio of 12.90%. The exergy losses from the combustion process dominates the overall system exergy losses with a maximum of 21.00 MW, followed by the exergy from the turbine, which occupies 18.42% of the input energy. The cycle efficiency of the system is up to 63.54%, and the molten salt temperature has a more significant impact on the system performance than the molten salt flow rate. The economic feasibility analysis yields a peaking capacity cost of $74.28/kWh for the modified system. The system will complete 100% recovery of the investment cost in 4.90 years, and thereafter, the annual profit is more than $3.71 Million. The peaking hours and regional electricity price are the main factors affecting the system. The effect of critical factors on the payback years of the system was further explored, and the payback years remains within 8 years only when the molten salt temperature is above 500 °C and the molten salt flow rate exceeds 400 t/h.

Pilot-scale testing on catalytic hydrolysis of carbonyl sulfur combined with absorption-oxidation of H2S for blast furnace gas purification

About 70 % of the flue gas in the iron-steel industry has achieved multi-pollutant ultra-low emissions in China until 2023, and then the blast furnace gas purification has become the control step and bottleneck. Our research group has designed and constructed the world's first blast furnace gas desulfurization pilot plant with the scale of 2000 Nm3/h in October 2021. The pilot plant is a two-step combined desulfurization device including catalytic hydrolysis of carbonyl sulfur (COS) and absorption-oxidation of H2S, continuously running for 120 days. In the hydrolysis system, one reason for catalyst deactivation has been verified from the sulfur deposition. HCN in blast furnace gas can be hydrolyzed on the hydrolysis catalyst to produce the nitrogen deposition, which is one of the reasons for catalyst deactivation and has never been found in previous studies. The deposition forms of S and N elements are determined, S element forms elemental sulfur and sulfate, while N element forms -NH2 and NH4+. In the absorption-oxidation system, the O2 loading and the residence time have been optimized to control the oxidation of HS− to produce elemental sulfur instead of by-product S2O32−. The balance and distribution of S and N elements have been calculated for the whole multi-phase system, approximately 84.4 % of the sulfur is converted to solid sulfur product, about 1.3 % of the sulfur and 19.2 % of N element are deposited on the hydrolysis catalyst. The pilot plant provides technical support for multi-pollutant control of blast furnace.