SO₂ Tolerance of Rice Hull Ash Based Fe-Cu Catalysts for Low-Temperature CO-SCR of NO

Rice husk ash (RHA) has potential as a supporter of catalysts. In this research, we studied the activity and SO2 tolerance of RHA-based Fe-Cu oxide in the reduction of NO by CO. Characterization methods were employed to study the properties of the catalysts and their SO2 tolerance. Activity and SO2 resistance were also tested at different temperatures. We recommend two catalysts with SO2 resistance ability: Fe0.67Cu0.33/RHA (the highest catalytic activity) and Fe0.8Cu0.2/RHA. The NO removal rate hardly changed with the addition of SO2 and was kept at about 100%. However, the CO conversion rate decreased with increasing SO2 at the lower reaction temperatures, which may be due to the formation of sulfites. Fortunately, the deactivation was reversible and can be reduced with an increase in the reaction temperature. The results of our research may help promote the application of CO-SCR

SO2 Tolerance of Rice Hull Ash Based Fe-Cu Catalysts for Low-Temperature CO-SCR of NO

Rice husk ash (RHA) has potential as a supporter of catalysts. In this research, we studied the activity and SO2 tolerance of RHA-based Fe-Cu oxide in the reduction of NO by CO. Characterization methods were employed to study the properties of the catalysts and their SO2 tolerance. Activity and SO2 resistance were also tested at different temperatures. We recommend two catalysts with SO2 resistance ability: Fe0.67Cu0.33/RHA (the highest catalytic activity) and Fe0.8Cu0.2/RHA. The NO removal rate hardly changed with the addition of SO2 and was kept at about 100%. However, the CO conversion rate decreased with increasing SO2 at the lower reaction temperatures, which may be due to the formation of sulfites. Fortunately, the deactivation was reversible and can be reduced with an increase in the reaction temperature. The results of our research may help promote the application of CO-SCR

Combustion Characteristics and NOx Emission through a Swirling Burner with Adjustable Flaring Angle

A swirling burner with a variable inner secondary air (ISA) flaring angle β is proposed and a laboratory scale opposed-firing furnace is built. Temperature distribution and NOx emission are designedly measured. The combustion characteristics affected by variable β are experimentally evaluated from ignition and burnout data. Meanwhile, NOx reduction by the variable β is analyzed through emissions measurements. Different inner/outer primary coal-air concentration ratios γ, thermal loads and coal types are considered in this study. Results indicate that β variation provides a new approach to promote ignition and burnout, as well as NOx emission reduction under conditions of fuel rich/lean combustion and load variation. The recommended β of a swirling burner under different conditions is not always constant. The optimal βopt of the swirling burner under all conditions for different burning performance are summarized in the form of curves, which could provide reference for exquisite combustion adjustment

Experimental study on desulfurization efficiency and gas-liquid mass transfer in a new liquid-screen desulfurization system

This paper presents a new liquid-screen gas-liquid two-phase flow pattern with discarded carbide slag as the liquid sorbent of sulfur dioxide (SO2) in a wet flue gas desulfurization (WFGD) system. On the basis of experimental data, the correlations of the desulfurization efficiency with flue gas flow rate, slurry flow rate, pH value of slurry and liquid-gas ratio were investigated. A non-dimensional empirical model was developed which correlates the mass transfer coefficient with the liquid Reynolds number, gas Reynolds number and liquid-gas ratio (L/G) based on the available experimental data. The kinetic reaction between the SO2 and the carbide slag depends on the pressure distribution in this desulfurizing tower, gas liquid flow field, flue gas component, pH value of slurry and liquid-gas ratio mainly. The transient gas-liquid mass transfer involving with chemical reaction was quantified by measuring the inlet and outlet SO2 concentrations of flue gas as well as the characteristics of the liquid-screen two-phase flow. The mass transfer model provides a necessary quantitative understanding of the hydration kinetics of sulfur dioxide in the liquid-screen flue gas desulfurization system using discarded carbide slag which is essential for the practical application.Liquid-screen gas-liquid two-phase flow Mass transfer Desulfurization Sulfur dioxide

Kinetic Modeling Study of the Industrial Sulfur Recovery Process for Operating Condition Optimization

Sulfur recovery from acid gas (H2S and CO2), which is contained in fresh natural gas, can bring many economic and environmental benefits, and this topic has been studied for years. Finding an optimal operating condition for the factory is of much importance. In this paper, we built a reactor network analysis model with a detailed mechanism to describe and calculate the process in the sulfur recovery unit. This detailed mechanism included 94 species and 615 elementary reactions. Our model has a more accurate residence time than other existing models. This simulation model was verified with industrial data, and the calculation result was highly consistent with the industrial data and more accurate than other approaches. Then, we used this reactor network analysis model to study the effect of the excess air coefficient, the thermal reactor temperature, and the temperature of cooling water on the sulfur recovery efficiency of a real device in the Puguang gas field. The result showed the excess air coefficient and thermal reactor temperature had a clear impact on sulfur recovery efficiency. After analysis, we got the optimum condition parameters for this device. At last, these parameters were tested in the real sulfur recovery device, and the result was reasonable. Our research provides a way to improve the sulfur recovery process in the industry, and it can be helpful to reduce pollution emissions and improve economic performance

Transient Calculation Studies of Liquid–Solid Collision in Jet Descaling

Sichuan is gradually being transformed and is utilizing groundwater and thermal resources. However, this investigation found that the high mineralization rate of geothermal resources in the Sichuan Basin is common and efficient, and environmentally friendly descaling technology is the key to promoting the utilization of thermal resources in low-yield oil and gas wells. Due to the high efficiency, low cost, and lack of pollution of high-pressure jet descaling, it has attracted more and more attention recently, but the mechanism of jet descaling is still unclear. The key to jet descaling is the stress concentration in the scale caused by the impact of droplets from the jet. In this paper, the process of jet descaling is simplified as a 2D droplet–scale collision with a detailed theoretical analysis of the stress on the scale. A circular droplet was simulated to impact the surface of the scale. By using numerical methods for transient calculations, we couple the pressure of the droplets and the scale strain. We acquired transient equivalent stress fields inside scales and pressure distributions inside the water droplet. As a result of the impact, areas of high stress in the scale appeared. Due to the stress superposition, the highest stress is concentrated in two areas: the contact edge and the shaft. These results can identify the mechanism for high-pressure jet descaling and help improve the efficiency of high-pressure water-jet descaling

Effect of Degassing on the Stability and Reversibility of Glycerol/ZSM-5 Zeolite System

Gaseous phase plays roles in a liquid/nanoporous system during application that adequate attention should be paid to the gaseous effects and the nanoscale gas-liquid interaction. In the present study, two glycerol/ZSM-5 zeolite systems with different amount of residual gas are compared by performing a series of experiments. Influences of loading rate, as well as system temperature on the gas-liquid interactions, are studied. Results show that vacuum degassing pretreatment is required to obtain a reversible and stable energy absorption system. Moreover, the influence of gas on a liquid/nanoporous system is found to mainly act on the liquid outflow. After the routine vacuum degassing pretreatment, the residual air that is left in the nanopores is around 0.9014 nm–3 per unit specific pore volume, as presented in the current study. During compression, the existing gas left in the nanochannel tends to gather into the gas cluster, which further promotes the liquid outflow during unloading. However, excessively dissolved gas may reduce the driving force for liquid outflow by breaking the continuity of the liquid molecular chain in nanochannel. Consequently, small bubbles as a labile factor in the system must be excluded for the steady use of the system. This work sheds some light on the effect of the amount of residual gas on the liquid/nanoporous system and gives guidance on the pretreatment of the liquid/nanoporous material mixture before encapsulating