Basic Oxygen Furnace Gas Research Articles

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.

Life Cycle Assessment of Aviation Fuel Production from Steel-Industry Off-Gas

The steel industry in China, the world’s largest, contributes to about 15% of the nation’s total carbon emissions. Instead of direct combustion, the technology of converting off-gas from the steel industry into liquid fuels not only enhances the added value of this byproduct but also helps alleviate carbon emissions. This study, for the first time, integrates the specific circumstances of China to evaluate the carbon emissions of Ethanol to Jet (ETJ) and Fischer–Tropsch to Jet (FTJ) fuel technologies utilizing Basic Oxygen Furnace Gas (BOFG) and Coke Oven Gas (COG) as feedstocks. Six cases were examined using Aspen Plus (V11) for mass and energy balance: Case 1: BOFG/ETJ, Case 2: BOFG/FTJ, Case 3: COG/ETJ, Case 4: COG/FTJ, Case 5: (COG + BOFG)/ETJ, and Case 6: (COG + BOFG)/FTJ. The analysis underscores that the FTJ pathway exhibits superior carbon reduction efficiency relative to ETJ. Compared to traditional petroleum-based aviation fuels (86.65 g CO2eq/MJ), the FTJ pathways utilizing COG or COG + BOFG as feedstocks exhibit significant advantages in greenhouse gas (GHG) emission reductions, with carbon emissions of 23.60 g CO2eq/MJ and 41.48 g CO2eq/MJ, respectively, representing reductions of 72.76% and 52.13%. Furthermore, employing uncertainty analysis based on the Monte Carlo method establishes the credibility of the findings. Finally, sensitivity analysis for parameter optimization and process improvements demonstrates the significant impact of the life cycle assessment (LCA) allocation method on computational results for exhaust gas feedstocks. Given the limited coverage of lifecycle assessments for Ethanol to Jet and Fischer–Tropsch to Jet pathways in China, this study could assist policymakers in determining the development trajectory of sustainable aviation fuel (SAF) in China.

Enhancing the production of liquid hydrocarbons by coupling blast furnace gas (BFG) of steelwork with syngas in the GTL process

Steelwork is one of the main emitters of CO2 in the world. For this reason, many efforts are being made to reduce or avoid CO2 emissions by unit optimization or by carbon capture and storage (CCS) or utilization (CCU) processes. In the steelwork, three main off-gases are generated including the Blast Furnace Gas (BFG), the Coke-Oven Gas (COG), and the Basic Oxygen Furnace Gas (BOFG). Different processes and technologies can be proposed for recovery based on the volume and composition of the steelwork off-gases. In this paper, the BFG stream is utilized to improve the efficiency of the GTL process and reduce CO2 emissions. For this purpose, a part of the BFG gases is mixed with the syngas produced in the methane autothermal reforming process and injected into the Fischer-Tropsch reactor to produce liquid hydrocarbons. The BFG flow rate was determined according to the optimum H2/CO value. The pressure and volume of the reactor were set at 10 bar and 300 m3 for optimal hydrocarbon production. The simulation results showed that mixing a portion of the BFG with the syngas increases the C5 + production by 11268 bbl/day, while the CO2 emissions decreased by 146529 ton/yr.

Utilization of Synthetic Steel Gases in an Additively Manufactured Reactor for Catalytic Methanation

The path to European climate neutrality by 2050 will require comprehensive changes in all areas of life. For large industries such as steelworks, this results in the need for climate-friendly technologies. However, the age structure of existing steelworks makes transitional solutions such as carbon capture, utilization and storage (CCUS) necessary as short-term measures. Hence, a purposeful option is the integration of technical syntheses such as methanation into the overall process. This work summarizes hydrogen-intensified methanation experiments with synthetic steel gases in the novel additively manufactured reactor ‘ADDmeth1’. The studies include steady-state operating points at various reactor loads. Blast furnace gas (BFG), basic oxygen furnace gas (BOFG) and three mixtures of these two gases serve as carbon sources. The methanation achieved methane yields of 93.5% for BFG and 95.0% for BOFG in the one-stage once-through setup. The results suggest a kinetic limitation in the case of BFG methanation, while an equilibrium limitation is likely for BOFG. There is a smooth transition in all respects between the two extreme cases. The reaction channel inlet temperature ϑin showed a large influence on the reactor ignition behavior. By falling below the threshold value, a blow-off occurred during experimental operation. By means of a simulation model, practical operating maps were created which characterize permissible operating ranges for ϑin as a function of the gas composition and the reactor load.

Bed configurations in CO vacuum pressure swing adsorption process for basic oxygen furnace gas utilization: Experiment, simulation, and techno-economic analysis

CO is a primary component of basic oxygen furnace gas (BOFG) and can be used for producing fuel and various value-added chemicals. It can be typically obtained from steel mill gases via separation. Herein, suitable bed operation configurations for vacuum pressure swing adsorption (VPSA) were determined based on the desired CO product purity (PURCO,P) when separating CO from simulated BOFG (CO:CO2:N2:CH4 = 65:20:10:5 mol%) using a numerical model validated with experimental data. By changing the operation steps, one case of two-bed, four-step (2-bed), one case of three-bed, five-step (3-bed), and two cases of four-bed, six-step (4-bedbase and 4-bedmod) operation configurations were considered at a setting temperature of 60 ℃, desorption pressure of 0.13 kgf cm−2, and adsorption pressure in the range of 2.5–4.0 kgf cm−2. The sensitivities of these four operation configurations were evaluated to compare the separation performance and economic benefits of each operation configuration. In the 2-bed case, the PURCO,P demonstrates a separation limit (92.1–92.7 mol%). When targeting PURCO,P ≥ 99.00 mol%, the 3-bed case presents the most favorable CO recovery values (RECCO,P; 92.97–94.13 %) and unit production costs of CO (UPCCO; 0.252–0.357 US$ Nm−3), whereas the 4-bedmod case presents optimal RECCO,P (82.06–91.65 %) and UPCCO values (0.273–0.406 US$ Nm−3) when targeting PURCO,P ≥ 99.99 mol%, under the same operating conditions. These results indicate cost-effective CO-VPSA process configurations for enriching CO from BOFG, based on the target PURCO,P.

Integrated Process Design and Life Cycle Assessment of Carbon Monoxide Provision from Basic Oxygen Furnace Gas

AbstractVacuum pressure swing adsorption (VPSA) processes are promising separation technologies to recover valuable compounds from industrial off‐gases. In this work, the separation of CO from basic oxygen furnace gas (BOFG) with a three‐bed VPSA process for high‐purity applications using a dynamic process model is analyzed. The analysis evaluates technical operating ranges for providing 99.9 % pure CO and assesses system‐wide environmental impacts using life cycle assessment. The results show that CO from BOFG as feedstock for chemicals reduces greenhouse gas (GHG) emissions by about 10 % for Germany's current grid mix regardless whether the VPSA process operates at maximum productivity (0.18 Nm3h−1kg−1ads) or maximum recovery (95.7 %). Further reduction in GHG emissions by up to 68 % can be achieved using renewable energy albeit increasing other environmental impacts such as mineral and metal depletion. Overall, VPSA offers a viable, short‐term solution for providing low‐carbon CO from BOFG.

Economic Evaluation of Renewable Hydrogen Integration into Steelworks for the Production of Methanol and Methane

This work investigates the cost-efficient integration of renewable hydrogen into steelworks for the production of methane and methanol as an efficient way to decarbonize the steel industry. Three case studies that utilize a mixture of steelworks off-gases (blast furnace gas, coke oven gas, and basic oxygen furnace gas), which differ on the amount of used off-gases as well as on the end product (methane and/or methanol), are analyzed and evaluated in terms of their economic performance. The most influential cost factors are identified and sensitivity analyses are conducted for different operating and economic parameters. Renewable hydrogen produced by PEM electrolysis is the most expensive component in this scheme and responsible for over 80% of the total costs. Progress in the hydrogen economy (lower electrolyzer capital costs, improved electrolyzer efficiency, and lower electricity prices) is necessary to establish this technology in the future.

Bed Configurations in Co Vacuum Pressure Swing Adsorption Process for Basic Oxygen Furnace Gas Utilization: Experiment, Simulation, and Techno-Economic Analysis

Bed Configurations in Co Vacuum Pressure Swing Adsorption Process for Basic Oxygen Furnace Gas Utilization: Experiment, Simulation, and Techno-Economic Analysis

Deriving Economic Potential and GHG Emissions of Steel Mill Gas for Chemical Industry

To combat global warming, industry needs to find ways to reduce its carbon footprint. One way this can be done is by re-use of industrial flue gases to produce value-added chemicals. Prime example feedstocks for the chemical industry are the three flue gases produced during conventional steel production: blast furnace gas (BFG), basic oxygen furnace gas (BOFG), and coke oven gas (COG), due to their relatively high CO, CO2, or H2 content, allowing the production of carbon-based chemicals such as methanol or polymers. It is essential to know for decision-makers if using steel mill gas as a feedstock is more economically favorable and offers a lower global warming impact than benchmark CO and H2. Also, crucial information is which of the three steel mill gases is the most favorable and under what conditions. This study presents a method for the estimation of the economic value and global warming impact of steel mill gases, depending on the amount of steel mill gas being utilized by the steel production plant for different purposes at a given time and the economic cost and greenhouse gas (GHG) emissions required to replace these usages. Furthermore, this paper investigates storage solutions for steel mill gas. Replacement cost per ton of CO is found to be less than the benchmark for both BFG (50–70 €/ton) and BOFG (100–130 €/ton), and replacement cost per ton of H2 (1800–2100 €/ton) is slightly less than the benchmark for COG. Of the three kinds of steel mill gas, blast furnace gas is found to be the most economically favorable while also requiring the least emissions to replace per ton of CO and CO2. The GHG emissions replacement required to use BFG (0.43–0.55 tons-CO2-eq./ton CO) is less than for conventional processes to produce CO and CO2, and therefore BFG, in particular, is a potentially desirable chemical feedstock. The method used by this model could also easily be used to determine the value of flue gases from other industrial plants.

Integration of Renewable Hydrogen Production in Steelworks Off-Gases for the Synthesis of Methanol and Methane

The steel industry is among the highest carbon-emitting industrial sectors. Since the steel production process is already exhaustively optimized, alternative routes are sought in order to increase carbon efficiency and reduce these emissions. During steel production, three main carbon-containing off-gases are generated: blast furnace gas, coke oven gas and basic oxygen furnace gas. In the present work, the addition of renewable hydrogen by electrolysis to those steelworks off-gases is studied for the production of methane and methanol. Different case scenarios are investigated using AspenPlusTM flowsheet simulations, which differ on the end-product, the feedstock flowrates and on the production of power. Each case study is evaluated in terms of hydrogen and electrolysis requirements, carbon conversion, hydrogen consumption, and product yields. The findings of this study showed that the electrolysis requirements surpass the energy content of the steelwork’s feedstock. However, for the methanol synthesis cases, substantial improvements can be achieved if recycling a significant amount of the residual hydrogen.

Physicochemical Phenomena of CO2 Injection in Polymetallic Ironmaking

Abandoned basic oxygen furnace gas (ABOFG) is a kind of byproduct fuel resource produced in the basic oxygen furnace (BOF) steelmaking process with a high temperature of 1773–1873 K and 20–40% (vol.%) CO and 20–30% (vol.%) CO2 and is usually ignited and discharged as waste gas (34.7% abandoned rate). The effects and physicochemical phenomena of injecting CO2‐containing ABOFG into high‐Cr‐bearing vanadia−titania magnetite ironmaking are investigated. The thermodynamic calculation shows that the ABOFG injection changes the gas partial pressure and the oxygen potential in the slag−coke interfaces and suppresses the titanium carbonitride formation. According to the results of softening−melting−dripping experiments, the content of titanium carbonitride in the high‐titanium slag decreases from 2.53% to 1.14% as the CO2 content in ABOFG increases from 0 to 30%, which is conducive to improving the high‐temperature physicochemical properties of molten slag. The recoveries of vanadium and chromium are also improved with the decrease in iron loss. Moreover, the residual coke still maintains a considerable compressive strength with a slight effect from ABOFG injection, which is expected to reduce carbon consumption.

Enrichment of Integrated Steel Plant Process Gases with Implementation of Renewable Energy

The steel industry is one of the most important industry sectors, but also one of the largest greenhouse gas emitters. The process gases produced in an integrated steel plant, blast furnace gas (BFG), basic oxygen furnace gas (BOFG) and coke oven gas (COG), are due to high shares of inert gas (nitrogen) in large part energy poor but also providing a potential carbon source (carbon monoxide and carbon dioxide) for the catalytic hydrogenation to methane by integration of a power-to-gas (P2G) plant. Furthermore, by interconnecting a biomass gasification, an additional biogenic hydrogen source is provided. Three possible implementation scenarios for a P2G and a biomass gasification plant, including mass and energy balances were analysed. The scenarios stipulate a direct conversion of BFG and BOFG resulting in high shares of nitrogen in the feed gas of the methanation. Laboratory experimental tests have shown that the methanation of BFG and BOFG is technically possible without prior separation of CO2. The methane-rich product gas can be utilised in the steel plant and substitutes for natural gas (NG). The implementation of these renewable energy sources results in a significant reduction of CO2 emissions between 0.81 million tonnes CO2eq and 4.6 million tonnes CO2eq per year. However, the scenarios are significantly limited in terms of available electrolysis plant size, renewable electricity and biomass.

CO2 injection improves the high-temperature performances of Cr-bearing vanadia-titania magnetite smelting in blast furnace

The effects of CO2 injection on the high-temperature metallurgical performance of Cr-bearing vanadia-titania magnetite (CVTM) in blast furnace (BF) smelting were investigated. The dry air or O2-enriched air is not necessarily suitable for any blast furnace production, and CO2-containing high-temperature energy-carried gas (CHEG) also can be an alternative injection gas with lower cost and pollution. This kind of CHEG can be blast furnace gas, basic oxygen furnace gas, coke oven gas, sintering gas and rotary kiln gas and so on, which contained high sensible heat and CO2, H2 and CO. Injecting CHEG into the blast furnace can replace air injection to achieve the heat balance in the cohesive zone and raceway. The calculated boundary injection ratio of CO2 is approximately 15.3%, and the experimental optimal CO2 injection ratio is about 10∼20%. CO2 injection benefits the blast furnace operation, the permeability of cohesive zone, recovery ratio of Cr and V. With increasing injected content of CO2, the temperature range of softening zone [T40-T4] and melting-dripping zone [Td-Ts] decrease almost 20℃, and the dripping ratio increases from 62.36% to 69.76%, the recovery of V increases from 32.75% to 47.96%, and the recovery of Cr increases from 42.35% to 64.41%. The CO2 injection affects the melting temperature of the high-titanium slags to be higher and the maximum temperature difference can reach 45℃, which is beneficial to the slag stability and separation of slag-iron and restrain the over-deduction of titania to TiN upon the slag-coke interface with lower N2.

Study on the High-temperature Properties of High-titania Slags produced with Cr-bearing Vanadia-titania Magnetite Smelting in Blast Furnace

The high-temperature metallurgical property of high-titania slag is one of the most significant indicators to measure the production status of Cr-bearing vanadia-titania magnetite blast furnace (CVTM-BF). Due to the continuous high temperature in the furnace, titania is over-reduced to titanium carbonitride with a high melting point (over 3000°C), which causes the viscosity of the slag to be too high to separate the molten iron and molten slag well. However, a high proportion of N2 in the air blasted into the furnace participates in the generation of TiN, and the large required air volume causes a high coke ratio and excessively high furnace temperature, which is not conducive to suppressing the over-reduction of titania. Here we show that TiN was significantly reduced and the metallurgical properties of high-titania slag were improved by injecting abandoned basic oxygen furnace gas (ABOFG), which is a kind of by-product gas containing CO, CO2, lower N2 and high physical heat. The experimental results demonstrated that the ABOFG was likely to function in suppressing TiN from 2.46% to 1.06%, dropping the melting temperature down from 1478.8°C to 1290.3°C, pushing the slag-iron interface tension from 0.641 N/m to 0.882 N/m as well as bring the viscosity down from 0.353 Pa⋅s to 0.341 Pa⋅s. Overall, ABOFG as a kind of endothermic atmosphere compared to O2-enriched air is beneficial to restrain the over-deduction of titania to TiN upon the slag-coke interface with lower N2. It also helps CVTM-BF to be recovered from the continued deterioration as soon as possible.

Environmental benefits of urea production from basic oxygen furnace gas

Basic oxygen furnace gas (BOFG) is a multi-component residual flow from integrated steel mills composed of CO, CO2, O2, N2 and H2. In this study, we use the life cycle assessment method to quantify the environmental impacts of six applications of BOFG: heat for internal use in the steel mill, heat combined with CO2 storage, electricity production, urea production, urea production combined with CO2 storage and flaring. Urea can be produced from solely BOFG components, making use of the sorption enhanced water–gas shift technology. This application of BOFG is described here for the first time. The environmental impacts of these six applications were compared in light of the impacts of their conventional production (‘counterfactual’). Using BOFG for the production of electricity and urea would result in net greenhouse gas emissions of 0.87 tCO2-eq/tBOFG and 0.69 tCO2-eq/tBOFG, respectively. When excess CO2 is transported and stored, net emission savings could be achieved when producing urea (−0.11 tCO2-eq/tBOFG) and heat (−0.12 tCO2-eq/tBOFG) from BOFG, again as compared to their counterfactual of conventional production. Overall environmental impacts were slightly lower for electricity (5.2E−4 DALY/tBOFG, 1.9E−6 species.yr/tBOFG) compared to urea (6.2E−4 DALY/tBOFG, 1.9E−6 species.yr/tBOFG). Sensitivity analysis showed, however, that when replacing cleaner electricity (e.g. under future power decarbonisation), these relative environmental benefits of electricity production from BOFG are diminished. We conclude that urea production, rather than the current practice of electricity production, is the best investigated option to reduce environmental impacts of BOFG, which can lead to net environmental benefits when combined with CO2 storage.

Performance optimization of an open simple-cycle gas turbine combined cooling, heating and power plant driven by basic oxygen furnace gas in China's steelmaking plants

Based on production data of some steelmaking plants in China and applying finite-time thermodynamics, this paper establishes a physical model of simple open gas turbine combined cooling, heating and power plant driven by basic oxygen furnace gas. Thermal process of each component is analyzed. Useful energy output rate and first law efficiency are considered as optimization objectives. Cases with or without constraints of fuel mass flow rate and overall size are investigated. In the case of without constraints, compressor inlet pressure drop (i.e. air mass flow rate) and pressure ratio are respectively optimized, and the maximum useful energy output rate is obtained. In the case of with constraints, it is found that the first law efficiency also exists maximum with respect to compressor inlet pressure drop and pressure ratio, the optimal flow area allocations among the components are obtained. The results show that maximum useful energy output rate and first law efficiency increase with heat source temperature, efficiencies of compressors and turbine, component flow area and cooling temperature, while decrease with heating temperature. Effects of energy and exergy saving, CO2 emission reduction and cost saving are analyzed compared with conventional separate generation plants, and partial model is validated.

Techno-economic assessment of SEWGS technology when applied to integrated steel-plant for CO2 emission mitigation

Mitigation of CO2 emissions in the industrial sector is one of the main climate challenges for the coming decades. This work, carried out within the STEPWISE H2020 project, performs a preliminary techno-economic assessment of the Sorption Enhanced Water Gas Shift (SEWGS) technology when integrated into the iron and steel plant to mitigate CO2 emissions. The SEWGS separates the CO2 from the iron and steel off-gases with residual energy content (i.e. Blast Furnace Gas, Basic Oxygen Furnace Gas and Coke Oven Gas) and the produced H2 is sent to the power generation section to produce the electricity required by the steel plant, while the CO2 is compressed and transported for storage. Detailed mass and energy balances are performed together with a SEWGS cost estimation to assess the energy penalty and additional costs related to CO2 capture. Results demonstrates the potential of SEWGS to capture over 80 % of CO2 in the off-gases, which results in entire plant CO2 emission reduction of 40 % with a Specific Energy Consumptions for CO2 Avoided (SPECCA) around 1.9 MJ/kgCO2. SEWGS outperforms a commercial amine scrubbing technology which has a SPECCA of 2.5 MJ/kgCO2 and only 20 % of CO2 avoided. The cost of CO2 avoided calculated on the basis of a fully integrated steel plant is around 33 €/tCO2 compared to 38 €/tCO2 of the amine technology.

The Effect of Abandoned Basic Oxygen Furnace Gas Blowing on the Softening–Melting–Dripping Performance of Full High Cr‐Bearing Vanadia–Titania Magnetite Pellets

It is inevitable to encounter increase in slag thickness, foaming slag, and high iron loss due to excessive formation of titanium carbonitride in blast furnace smelting of full high Cr‐bearing vanadia–titania magnetite (HCVTM). The effects of softening–smelting–dripping properties, the content variation of titanium carbonitride, and mineral element migration process of full HCVTM pellets with abandoned BOF gas (ABOFG) blowing are studied using X‐ray diffraction (XRD), X‐ray fluorescent (XRF), inductively coupled plasma‐atomic emission spectroscopy (ICP‐AES), X‐ray photoelectron spectroscopy (XPS), electron probe microanalysis‐wavelength‐dispersive spectrometer (EPMA‐WDS), and scanning electron microscope‐energy dispersive spectroscopy (SEM‐EDS). ABOFG is a type of neglected byproduct gas resource produced in the steelmaking process with high physical and chemical thermal energies and contains 20–40% CO, 20–30% CO2, 2–5% O2, and 30–50% N2. As the concentration of CO2 in ABOFG increases, the position and height of the cohesive zone decline, and the concentration of titanium carbonitride decreases from 1.424% to 1.035%, which are beneficial to the BF smelting process. In addition, the migration processes of Ti, V, and Cr are also affected, especially Ti tends to enrich in the dripped slag, whereas V and Cr tend to concentrate at the dripped iron.

Techno-economic analysis of methanol production from joint feedstock of coke oven gas and basic oxygen furnace gas from steel-making

This paper presents a study of the techno-economic analysis of producing methanol (MeOH) from steel mill off-gases, especially coke oven gas and basic oxygen furnace gas. The mixed off-gases produce syngas with appropriate H2/CO ratio and are converted to MeOH. A detailed kinetic model over a commercial catalyst Cu/ZnO/Al2O3 is applied for MeOH synthesis reaction. Four process designs were analyzed; they are combinations of two syngas compositions and the presence or absence of an interim MeOH-separation unit. When production rate was 22.2–28.3 t MeOH h−1, the unreacted purged gas could be used to generate electricity or can be sold as a fuel. The energy efficiency was in the range of 54.6–55.9%, considering both MeOH and electricity as an energy output. A heat-exchanger network is designed to minimize energy usage in the process. We analyzed the proposed process techno-economically and calculated a minimum selling price. The best case gives $0.57 kg−1 which is slightly higher than the recent market price, although a sensitivity analysis suggests that the price can be decreased in some cases. This study can be a basis for further research on this process.