Papers by Keyword: SCR

Abstract: Mg-Mo-V-Ti catalysts of low temperature denitrification were prepared by dipping method. In order to study the activity of selective catalytic reduction, the catalyst was placed in a fixed bed reactor. Industrial flue gas was simulated with cylinder gas. Results indicate that the 0.1wt% content of MgO catalyst has good performance on denitration activity and sulfur resistance. The effects of oxygen content, space velocity and reaction temperature on the activity of the 0.1MgO-6MoO₃-3V₂O₅-TiO₂ wt% catalyst were investigated. With the increase of oxygen concentration, the denitrification efficiency increases when the oxygen concentration is less than 8%. When the oxygen content is greater than 8%, the denitrification efficiency is almost the same. The denitrification efficiency decreases with the increase of space velocity. The removal efficiency of NO 0.1MgO-6MoO₃-3V₂O₅-TiO₂ wt% catalyst over increases first and then becomes stable with the increase of temperature, and the conversion efficiency of SO₂ is less than or equal to 2.2% at 120~240 °C.

Abstract: Mo-V-Ti catalysts of low temperature denitrification were prepared by dipping method. In order to study the activity of selective catalytic reduction, the catalyst was placed in a fixed bed reactor. Industrial flue gas was simulated with cylinder gas. The experimental condition is NO: 500ppm, NH₃:500ppm, O₂:8%, SO₂:100ppm, N₂: equilibrium gas, space velocity: 36000h^-1. Results indicate that the catalyst prepared by dipping method had good denitrification activity and sulfur resistance at low temperature. The optimum ratio of catalyst was 3V₂O₅-6MoO₃-91TiO₂ (wt %). The conversion efficiency of NO was 80~93%, and the conversion efficiency of SO₂ was less than 1% at 180~260 °C.

Abstract: The objective of this work is to determine the maximum reduction of NO_x emissions by varying the concentrations of urea solution with a reduction catalyst, and optimization of the urea injection by the evaporation of the solution, using the CFD-Fluent solver. An aqueous solution of urea was injected in the engine exhaust pipe for reducing NO_x emissions, in a single cylinder light duty, stationary, four stroke, air cooled DI diesel engine, fuelled with neat diesel and diesel-ethanol blends (10%). The concentration of the urea solution was varied from 30 to 35% by weight with constant flow rates, and tested with a Titanium dioxide (TiO₂) coated catalyst, fitted on the engine exhaust pipe, which controls the by products of ammonia and water vapour. The results indicated that a maximum of 70% NO_x reduction was achieved when the engine was fuelled with diesel-ethanol blends at a constant flow rate of 0.75 lit/hr with an urea concentration of 35%, and also that 66% reduction of NO_x was achieved, using the Titanium dioxide catalyst in the Selective Catalytic Reduction system with neat diesel. From the simulation results,it was seen that only at 75% and 100% load,the evaporation point of the urea solution was higher than that of the boiling point (423 K), due to complete vaporisation of water.

Abstract: Selective Catalytic Reduction catalyst (Cu-Mn/CSC) was derived from coconut shell carbon (CSC). The bimetallic catalysts, Copper and Manganese (Cu-Mn), were deposited onto CSC using wet impregnation technique while the calcination stage was performed under low temperature ambient air. The samples were then characterized using nitrogen adsorption-and-desorption, carbon dioxide temperature-programmed desorption, ammonia temperature-programmed desorption, hydrogen temperature-programmed reduction as well as scanning electron microscopy. The results showed that the synthesis process increased the external surface area and regulated the distribution of slit-shape pores on Cu-Mn/CSC. Besides, Cu-Mn was found to be reduced and the surface has more acidic groups compared to basic. These findings indicated the potential of using CSC as a precursor for NOx-Selective Catalytic Reduction catalyst.

Abstract: Two catalysts (V₂O₅/AC and V₂O₅/CNTs) with different loadings, prepared by impregnation method, were used to research the DeNOx activity under N₂ and CO₂ atmospheres respecitively at the temperature range from 100°C to 300°C using a fixed bed reactor. Effects of temperature, loading and support on the DeNOx activity were studied. The results show that the NO conversion of the both catalysts increases with the reaction temperature. The loading and support have significant effects on the activities. 9%V₂O₅/AC and 9%V₂O₅/CNTs yielded 80% and 66.6% NO conversion at 250°C respectively under N₂ atmosphere, however, they yielded 78.1% and 75.1% respectively under CO₂ atmosphere.

Abstract: This work try to optimize the flow field and concentration field of SCR system. Firstly, the original SCR system is simulated by Fluent and two kinds of guide plates are utilized. The simulation results show that the straight guide plate is slightly better than curve guide plate. The relatively standard deviation of velocity and concentration fields and pressure drop agree with the design rules. To verify the simulation results, a 1:10 scale cold plexiglass test plant is established and this plant is simulated correspondingly. The simulation results are in good agreement with experimental results. So the simulation results of original SCR system are credibly and can guide the practical engineering.

Abstract: The turbo diesel SCR system has been researched and analyzed in this paper. By using software of CATIA, three-dimensional physical model of SCR system has been established, and with software of AVL-FIRE, the boundary conditions have been set, simulated and optimized. In the process of SCR system optimizing, it mainly optimized the pray angle. Compare the effects of processing NOx to obtain batter optimization results. At last the optimization results are compared by bench test, and the experimental results are quite consistent with simulation.

Abstract: NOx emission of diesel engine is an important pollutant to the environment, in the bench test of SCR technology for the diesel engine NOx reducing effect. Diesel engine NOx to ESC test cycle emission by 10.73,down to 3.24; ETC test cycle of the diesel engine NOx emission decreased from 9.533 to 2.98, the diesel engine emissions to meet Euro IV emission standards. Experimental results showed that SCR can effectively reduce NOx emission of diesel engine and the pollution of the environment.

Abstract: This paper presents a research on the problem of catalyst failure in a selective catalytic reduction (SCR) system. The preliminary analysis indicates that the catalyst failure is caused by abrasion. For this, firstly, the mechanism of abrasion is analyzed through a field experiment. Secondly, according to the results from the field experiment, a scheme is put forward to optimize the flow field. Finally, the application results show that the uniformity of fly ash distribution in the flue gas are improved prominently, the reliability of the SCR system is enhanced at the same time.

Abstract: In this paper, the NOx emission of original diesel engine and the urea supply model of SCR system under different working conditions of ESC were obtained according the requirement of GB17691-2005[1]. Then the model of urea demand was established, and the comparison was made with the actual urea supply. In addition, the causes of the differences between them were analyzed.