Search

In this study, a novel configuration, Adiabatic and Plate Water-cooled Reactors, which called APW is introduced as an alternative for a two stage conventional methanol process consisting of gas-cooled and water-cooled reactors. In the APW configuration, the gas-cooled reactor is replaced with two adiabatic reactors with the optimized basic design. A water-cooled reactor is like a plate heat exchanger with three sections by the different number of plates. The gas flow rate through each section is optimized, so that pressure and temperature changes along these sections are almost identical. Mathematical modeling indicates that, temperature rise within the adiabatic reactor precludes gas condensate formation, consequently improves the catalyst durability. Moreover, the small length to cross section ratio of the adiabatic bed results in low pressure drop. Also, high average temperature and low pressure drop along the adiabatic beds enhance methanol production. The proposed configuration, provides different advantages than the conventional process, e.g. low pressure drop, high cooling efficiency of the water-cooled reactor and higher H 2 and CO 2 conversions. The APW configuration enhances the methanol production rate 12.2% in comparison with conventional configuration. Other advantages in this configuration are, eliminating condensate formation, preventing greenhouse gas emissions and improving catalyst durability. Unlabelled Image • In this study, a novel configuration composed of adiabatic and plate water-cooled reactors is introduced. • Temperature increase inside adiabatic reactors precludes condensation and low pressure drop improves methanol production. • High temperature along adiabatic reactors and high cooling efficiency along water-cooled reactors improve process efficiency. [ABSTRACT FROM AUTHOR]

• Measures for reducing the carbon intensity of blast furnace ironmaking were introduced. • Influences of low-carbon ironmaking processes on fuel requirements are reviewed. • The introduction of alternative reductants cannot eliminate the need for metallurgical coke. • Sustainability of blast furnace ironmaking depends on improving the H/C replacement ratio. • Introduction of hydrogen promotes the solution loss and structural degradation of coke. The blast furnace technology is still the main ironmaking route with a current global share of 70%. Reduction of fossil carbon consumption and CO 2 emissions in blast furnace operations are essential for the decarbonization of steelmaking. Potential solutions such as introducing renewable carbon-based materials (torrefied biomass, charcoal), using hydrogen-enriched reducing gases (i.e., hydrogen gas, coke oven gas, reformed coke oven gas, green methane), oxygen enrichment with top gas recycling, and carbon capture and storage/utilization have been considered to decrease emissions. The enhanced sustainability of blast furnace operations depends primarily on improving the hydrogen-to-carbon replacement ratio. Hydrogen is an effective reducing agent, producing steam during the reduction of ferrous burden. The replacement of coke and PCI with hydrogen leads to reduced fuel rates and CO 2 emissions. Although implementing the innovative ironmaking solutions reduces coke and coal consumption, coke cannot be replaced entirely as it plays an irreplaceable role as a mechanical support network and the permeable layer for gas movement in the blast furnace. The injection of alternative reducing agents into the blast furnace alters the reaction environment by changing gas composition and temperature. Therefore, understanding the impacts of new reaction conditions on coke rate and quality requirements is important to both coal producers and steel manufacturers. This paper reviews the current understanding of how the introduction of alternative reducing agents into the blast furnace influences the gasification behavior, degradation mechanism, and consumption rate of coke. The review also identifies the knowledge gaps and future research opportunities in the field. [ABSTRACT FROM AUTHOR]

In this work, the absorption process of carbon dioxide is performed in a custom designed high pressure experimental setup in which the gas and nanofluid are in direct contact at static state in a closed vessel. The initial condition of the tests are set at 20, 30, and 40 bar and 308 K. Nanoparticles of SiO2, Al2O3, Fe3O4, and carbon nanotubes (CNTs) are dispersed in pure water to form nanofluids at concentrations of 0.02, 0.05, and 0.1 wt %. Also, CNT nanoparticle has been dispersed in methyldiethanolamine and diethanolamine aqueous solutions at the concentration of 0.02 wt %. The absorption performances of different nanofluids are compared with the base solutions and with other nanofluids at different conditions. The results show that SiO2 and Al2O3 are more effective at higher nanoparticle concentrations (0.1 wt %), and they can enhance the absorption capacity up to 21% and 18%, respectively. Fe3O4 and CNT are more effective at lower nanoparticle concentration (0.02 wt %), and they can increase it up to 24% and 34%, respectively. CNT nanoparticle is more effective for methyldiethanolamine solution compared to diethanolamine solution with an increase in the absorption capacity up to 23%. It seems that gas adsorption on the nanoparticles surface leads to higher absorption capacity of nanofluids at equilibrium condition. [ABSTRACT FROM AUTHOR]

Conventional methanol synthesis process (CR configuration) consists of water-cooled and gas-cooled reactors in which methanol and water are condensed inside the gas-cooled reactor which deactivates the catalyst. In this study, two novel configurations (AW and ACW configurations) are represented to address this problem in which the gas-cooled reactor is replaced with adiabatic reactor. Moreover, a condenser is applied between adiabatic and water-cooled reactors in ACW configuration. Results show that temperature increases somewhat along the adiabatic reactor that prevents gas condensate formation. Besides, the adiabatic reactor maximum temperature is less than that of first reactor in CR configuration which prevents copper based catalyst thermal sintering. Moreover, a high cross section-to-length ratio of the adiabatic reactor leads to negligible pressure drop along the reactor and improvement in CO2 conversion to methanol that has positive environmental effects. Also, water mole fraction decreases along the reactors of AW and ACW configurations to prevent the deactivation of catalyst active sites. Eventually, methanol production rates by AW and ACW configurations are improved around 25.5% and 43.1% in comparison with CR configuration. So, novel AW and ACW configurations provide many benefits including improvement in catalyst activity and durability, CO2 conversion, and the methanol production rate. [ABSTRACT FROM AUTHOR]

In this study, SO 2 absorption performance of the novel amino acid salt aqueous solutions such as sodium lysinate and sodium glycinate from simulated flue gas were studied and compared with frequently utilized absorbents including ethylenediamine, 2-amino2-methyl1-propanol (AMP) and disodium hydrogen phosphate. SO 2 -aqueous solution equilibrium data of these absorbents at concentration of 0.1 M in a stirred batch reactor exhibited that amino acid salt aqueous solutions and especially sodium lysinate had higher SO 2 solubility at 298 K. In order to ensure the SO 2 removal efficiency at practical condition, the suggested absorbents were applied in a packed column. The experimental results imply better removal efficiency of amino acid salt solutions consistent with absorption equilibrium data. The effects of parameters such as temperature, SO 2 inlet concentration and liquid–gas flow ratio on removal efficiency were investigated for 1 M concentration of sodium lysinate solution. SO 2 removal efficiency enhanced with increasing gas–liquid flow ratio, but both temperature and SO 2 inlet concentration had opposite effects. [ABSTRACT FROM AUTHOR]