• Journal of Korean Society of Environmental Engineers
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• v.29 no.12
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• pp.1329-1336
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• 2007

This study was carried out to develop an efficient process abating high NO concentration. A hybrid process of selective catalytic reduction(SCR) and activated carbon fiber(ACF) adsorption was newly designed and tested. Used ACF in NO adsorption was regenerated by simultaneously applying heat and vacuum. The result of ACF regeneration was for superior in the desorption condition at $140^{\circ}C$ and vacuum 600 mmHg. A commercial catalyst was used at the conditions of reaction temperature at $300^{\circ}C$, $NH_3/NO$ mole ratio = 1.0 for SCR process. NO evolved from ACF regeneration reactor could be removed by SCR reactor up to 98%. But high concentration of NO was exhausted from SCR reactor for one minute when the flue gas of NO 300 ppm and deserted NO from ACF regeneration were simultaneously treated by the same SCR reactor. Therefore, it is necessary to use additional small sized SCR reactor or to increase $NH_3$ concentration for a short time along with NO concentration rather than to mix flue gas with the gas evolving from ACF regeneration at fixed $NH_3$ inlet concentration. The hybrid process of SCR and ACF showed high NO removal efficiency over 80% at any time courses. Through the repeated cycles, stable DeNOx efficiency was maintained, indicating that the hybrid process would be a good countermeasure to the spotaneously high NO concentration instead of increasing the SCR capacity.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.855-861
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• 2013

Small-pore Cu-chabazite SCR catalysts with high NOx conversion at low temperatures are of interest for marine diesel engines with exhaust temperatures in the range of 150 to $300^{\circ}C$. Unfortunately, fuels for marine diesel engines can contain a high level of sulfur of up to 1.5% by volume, which corresponds to a $SO_2$ level of 500 ppm in the exhaust gases for an engine operating with an A/F ratio of 50:1. This high level of $SO_2$ in the exhaust may have detrimental effects on the NOx performance of the Cu-chabazite SCR catalysts. In the present study, a bench-flow reactor is used to investigate the effects of sulfur poisoning on the NOx performance of Cu-chabazite SCR catalysts. The SCR catalysts were exposed to simulated diesel exhaust gas stream consisted of 500 ppm $SO_2$, 5% $CO_2$, 14% $O_2$, 5% $H_2O$ with $N_2$ as the balance gas at 150, 200, 250 and $300^{\circ}C$ for 2 hours at a GHSV of 30,000 $h^{-1}$. After sulfur poisoning the low-temperature NOx performance of the SCR catalyst is evaluated over a temperature range of 150-$300^{\circ}C$ to determine the extent of the catalyst deactivation. Desulfation is also carried out at 600 and $700^{\circ}C$ for 30 minutes to determine whether it is possible to recover the NOx performance of the sulfur-poisoned SCR Catalysts.

• Resources Recycling
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• v.29 no.2
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• pp.62-68
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• 2020

In new millennium, wide-reaching demands for selective catalytic reduction (SCR) catalyst have been increased gradually in new millennium. SCR catalyst can prevent the NO_x emission to protect the environment. In SCR catalyst the main composition of the catalyst is typically TiO₂ (70~80%), WO₃ (7~10%), V₂O₅ (~1%) and others. When the SCR catalysts are used up and disposed to landfills, it is problematic that those should exist in the landfill site permanently due to their extremely low degradability. A new advanced technology needs to be developed primarily to protect environment and then recover the valuable metals. Hydrometallurgical techniques such as leaching and liquid-liquid extraction was designed and developed for the spent SCR catalyst processing. In a first stage, V and W selectively leached from spent SCR catalyst, then both the metals were processed by liquid-liquid extraction process. Various commercial extractants such as D2EHPA, PC 88A, TBP, Cyanex 272, Aliquat 336 were tested for selective extraction of title metals. Scrubbing and stripping studies were tested and optimized for vanadium and tungsten extraction and possible separation. 3^rd phase studies were optimized by using iso-decanol reagent.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.6
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• pp.601-607
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• 2015

A set of novel silicon controlled rectifier (SCR) devices' characteristics have been analyzed and verified under the electrostatic discharge (ESD) stress. A ring-shaped diffusion was added to their anode or cathode in order to improve the holding voltage (Vh) of SCR structure by creating new current discharging path and decreasing the emitter injection efficiency (${\gamma}$) of parasitic Bipolar Junction Transistor (BJT). ESD current density distribution imitated by 2-dimensional (2D) TCAD simulation demonstrated that an additional current path exists in the proposed SCR. All the related devices were investigated and characterized based on transmission line pulse (TLP) test system in a standard $0.5-{\mu}m$ 24 V CDMOS process. The proposed SCR devices with ring-shaped anode (RASCR) and ring-shaped cathode (RCSCR) own higher Vh than that of Simple SCR (S_SCR). Especially, the Vh of RCSCR has been raised above 33 V. What's more, their holding current is kept over 800 mA, which makes it possible to design power clamp with SCR structure for on chip ESD protection and keep the protected chip away from latch-up risk.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.11
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• pp.83-89
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• 2008

The Effect of Space Velocity(SV) on NOx conversion rate was performed to develop NOx reduction after-treatment system. SV is calculated from engine exhaust gas volume and SCR catalyst volume. Found the Urea injection duty of maximum efficiency for NOx conversion if increase SV, NOx Conversion rate is down. Especially, when SV is more than $110,000h^{-1}$, NOx conversion rate decrease suddenly. Same case, if SV is lower than $40,000h^{-1}$, NOx conversion rate is down. Also, the characterization of Urea-SCR system was performed. Three candidate injectors for injecting Urea were tested in terms of 속 injection rate and NOx reduction rate. The performances of SCR catalytic converter on temperature were investigated. The performance of Urea-SCR system was estimated in the NEDC test cycle with and without EGR. It was found that nozzle type injector had high NOx conversion rate. SCR catalytic converter had the highest efficiency at the temperature of $350^{\circ}C$. EGR+Urea-SCR system achieved NOx reduction efficiency of 73% through the NEDC test cycle.

• International Journal of Naval Architecture and Ocean Engineering
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• v.13 no.1
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• pp.659-673
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• 2021

This study aims to investigate the impact of the High Pressure Selective Catalytic Reduction system (SCR-HP) on a large marine two-stroke engine performance parameters by employing thermodynamic modelling. A coupled model of the zero-dimensional type is extended to incorporate the modelling of the SCR-HP components and the Control Bypass Valve (CBV) block. This model is employed to simulate several scenarios representing the engine operation at both healthy and degraded conditions considering the compressor fouling and the SCR reactor clogging. The derived results are analysed to quantify the impact of the SCR-HP on the investigated engine performance. The SCR system pressure drop and the cylinder bypass valve flow cause an increase of the engine Specific Fuel Oil Consumption (SFOC) in the range 0.3-2.77 g/kWh. The thermal inertia of the SCR-HP is mainly attributed to the SCR reactor, which causes a delayed turbocharger response. These effects are more pronounced at low engine loads. This study supports the better understanding of the operating characteristics of marine two-stroke diesel engines equipped with the SCR-HP and quantification of the impact of the components degradation on the engine performance.

• Journal of Navigation and Port Research
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• v.40 no.4
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• pp.173-181
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• 2016

From 2016, controls on reduction of NOx and SOx emissions from the vessels that are operated in the emission control area were tightened. The selectivity catalytic reduction system of the denitrification equipment which NOx among the above controlled materials is very effective and used commercially very much. But it has the disadvantage that CSR is activated at high temperatures. Therefore, the SCR and SCR activation instrument that can react even at low temperatures by using micro-nano bubbles so that the above problems can be minimized were developed. And the computational fluid dynamics technique was used by ANSYS-CFX package to prepare the plan that improves the SCR system's efficiency. Simulation for the viscous flow analysis of the SCR system was executed by applying the Navier-Stokes equation to it as a governing equation. For the SCR system's shape, 3D modeling was done by using CATIA V5. SCR jet nozzle's position was checked by changing it to the intervals of 1/3, 1/2, and 2/3 from the inlet of the vent pipe to compare the SCR system's efficiency. And the number of nozzles was compared and analyzed by simulating 4, 6, and 8 holes to check an effect of the number on the SCR system's efficiency. The simulation result has found that the closer nozzles are to the inlet of the vent pipe and the more nozzles are, the more efficiency is improved.

• Journal of Nutrition and Health
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• v.46 no.6
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• pp.493-502
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• 2013

In this study, we designed to confirm the dietary effect of anti-obesity of fermented soybean curd residue (FSCR; SCR-Meju; Biji-meju) by A. oryzae, which is well known as a Korean traditional meju microbe. We observed that body weight gain, serum and hepatic lipid profile, as well as the activity of ROS generating enzyme and ROS scavenging enzyme in high-fat diet induced obese mice fed experimental diet (SCR and SCR-meju). Body weight gain and epididymal fat weight of HC (high-fat diet control) was markedly higher than that of NC (Normal control). Conversely, body weight gain and epididymal fat weight of the SCR (Biji) and SCR-meju (Biji-meju) group was significantly lower than that of HC; these of the SCR-meju group was lower than that of the SCR group. Furthermore, serum TG and total-cholesterol and LDL-cholesterol contents of SCR and SCR-meju groups were lower than that of HC, and HDL-cholesterol level of the SCR-meju group was significantly higher than that of HC. In conclusion, although precise mechanisms of the antiobese effects of SCR-meju in this study are unknown, the present study provides an experimental evidence that SCR-meju may prevent obesity and obesity related metabolic syndromes, such as hyperlipidemia, hypertension and diabetes, and liver disease by high-fat diet. Nevertheless, further study in this filed will be needed.

• Applied Chemistry for Engineering
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• v.17 no.4
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• pp.409-413
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• 2006

An experimental study on a combined $De-NO_x$ process of non-thermal plasma and $NH_{3}$ SCR, which can be operated under low temperature conditions, i.e. $150{\sim}200^{\circ}C$, has been conducted. The test results confirmed feasibility of fast SCR reaction, which shows faster reactivity compared with typical SCR reaction under the low temperature conditions. The test showed that pre-oxidation step to convert NO to $NO_2$ is necessary for the fast SCR reaction, and the appropriate ratio of $NO_{2}/NO_{x}$ ranges from 0.3 to 0.5. Ammonium salts produced under low temperature conditions, effects of hydrocarbons on the combined process, the operation power of the process are discussed in the present study.

• Journal of the Korean Applied Science and Technology
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• v.35 no.3
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• pp.876-885
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• 2018

Utilization of spent RHDM(Residue Hydrodemetallation) catalyst as de-NOx SCR(Selective Catalytic Reduction) catalyst was studied by conducting by heptane cleaning and high-temperature roasting for removal of deposited carbon and sulfur. Followed by oxalic acid leaching was carried out for controlling excess vanadium deposited on spent RHDM catalyst in search of appropriate vanadium loadings for the best SCR performance and the leaching conditions are 5~15wt% concentration of oxalic acid and 5min leaching time at $50^{\circ}C$ with the ultra-sonic agitator. De-NOx activities of prepared and commercial SCR catalyst were measured by the atmospheric SCR catalyst performance test unit, their residual content were also carried out by ICP, C&S Analysis and XRF. Acid leaching (AL-10) catalyst showed the highest de-NOx efficiency of all prepared catalysts and the de-NOx efficiency over wash coated catalyst(WC-AL-10) was equivalent to that of commercial SCR catalyst. Therefore the possibility of using as SCR catalyst for each application by adjusting treatment conditions of spent RHDM catalyst was found and further research will be needed in detail for the its commercialization.