• 한국연소학회:학술대회논문집
• /
• 2001.11a
• /
• pp.153-160
• /
• 2001

The combustion test used DTF was performed to obtain the characteristics of NOx emission and reduction. In this test, major factor of NOx emission was a stoichiometric air ratio. At the onset of combustion to be rich oxygen, NOx was produced rapidly. Optimum condition for NOx reduction was formed under about AR:0.7 in the combustion test of Alaska coal. Investigations were undertaken with 200KW(th) test combustor. In combustion test, the major variables were coal feed ratio of center/outer, stoichiometric air ratio at the onset of combustion. The lowest NOx emission, 182ppm(6% O2 base), was achieved at about AR:0.6 of the first combustion stage with low NOx burner. Also, unburned carbon content of char collected in this combustion condition was about 1wt%.

• Journal of Korean Society for Atmospheric Environment
• /
• v.14 no.2
• /
• pp.107-116
• /
• 1998

Coal gasification fuel has generally a lower calorific values than natural gas and also contains ammonia which is a main source of fuel NOx. Such a fuel is in need of the advanced technologies for the NOx reduction with higher combustion efficiency. Therefore fuel staged combustion was investigated for the fuel NOx control using a bench scale gas combustoi for the fuel NOx control. Parametric screening studies were performed with the variation of air ratio, retention length and reburning fuel. The NOx reduction efficiency was increased with an increase of total air ratio having optimum reburning air ratio differently, The Increased retention length of the reburning zone was preferable for NOx reduction. Hydrocarbonic reburning fuels like propane and butane were more effective for the NOx reduction efficiency than hydrogen fuel. The NOx concentration at exit was linearly increased according to the fuel-N the fuel.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.12 no.5
• /
• pp.66-72
• /
• 2004

In this study, the effects of oxygen component in fuel and exhaust gas recirculation(EGR) method on the exhaust emissions has been investigated for a D.I. diesel engine. It was tested to estimate change of exhaust emission characteristics for the commercial diesel fuel and oxygenate blended fuel which has five kinds of blending ratio. Dimethoxy methane(DMM) contains oxygen component 42.5% in itself, and it is a kind of effective oxygenated fuel for reduction of smoke emission. It was affirmed that smoke emission was decreased with increasing of DMM blending ratio. But, NOx emission was increased compared with commercial diesel fuel. It was needed a NOx reduction counterplan that EGR method was used as a countermeasure for NOx reduction. It was found that simultaneous reduction of smoke and NOx emission was achieved with DMM blended fuel and cooled EGR method(1015%).

• Proceedings of the KSME Conference
• /
• 2008.11b
• /
• pp.3096-3101
• /
• 2008

Selective Catalytic Reduction (SCR) technology is well-known to be effective for the reduction of NOx emission. So car manufacturers has adopted Ures-SCR system to be satisfied with emission regulation. This paper discusses the effective of $NH_3/NOx$ ratio and SCR catalyst temperature in the $NH_3$-SCR reactor on DeNOx performance. So it is shown the characteristic of NOx conversion and ammonia slip using the $NH_3$ instead of Urea-Solution. From the result of this study, it is found to optimize $NH_3/NOx$ ratio to have the best case of high NOx conversion and low ammonia slip at variable SCR catalyst temperatures. Lastly, it is also found the characteristics of NOx conversion and ammonia slip with compared with Urea.

• Journal of Korean Society of Environmental Engineers
• /
• v.22 no.11
• /
• pp.1977-1983
• /
• 2000

SCR(selective catalytic reduction) pilot plant for reduction of the nitrogen oxides using diesel oil as a reductant was installed at the NG(natural gas) fired combined cycle and the activity of Pt(0.3%)/Zeolite catalyst was studied in real flue gas condition according to the amount of reductant. reaction temperature and space velocity. NOx conversion gradually increased with increasing the diesel oil concentration up to C/N ratio 5.5(C/N ratio: the ratio of the number of carbon atom to the number of NOx molecules included in the flue gas). Increasing the reaction temperature. NOx conversion increased and reached a maximum conversion of 50% at $190^{\circ}C$. NOx conversion did not changed with increasing the space velocity up to 18,500/hr and then gradually decreased. These results reveal the potential for diesel oil as a reductant for de-NOx SCR process.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.4
• /
• pp.506-513
• /
• 2020

In this study, the mechanical properties, absorption, and reduction performance of NOx in the mortar containing mineral admixture like zeolite and active hwangtoh were evaluated. Zeolite and active hwangtoh were used as binder, and zeolite and active hwangtoh were substituted for cement. The substitution ratio of two types of mineral admixtures was considered as 20 and 30% respectively. As a result of evaluating the compressive strength and flexural strength of each mortar specimen, the highest strength in the plain mixture was evaluated. As the substitution ratio of zeolite and active hwangtoh increased, the compressive and flexural strength decreased. In addition, the difference of compressive and flexural strength between active hwangtoh and zeolite mixing was evaluated to be insignificant. To evaluate the absorption rate, the mixture was designed to lower the W/B ratio of the existing mixture and set the substitution ratio of active hwangtoh and zeolite at 25%. The highest absorption ratio in the mortar with zeolite was evaluated, and the difference in absorption ratio between the remaining two mortar mixtures was small. The assessment of reduction performance of NOx considering the application of photocatalyst showed a clearly decreasing reduction behavior, even if they were the same mortar mixture. Zeolite and active hwangtoh also showed a higher NOx reduction than the Plain mixture, because of their porosity properties. In the case of active hwangtoh, the absorption ratio was lower than that of zeolite mixture, but the reduction of NOx performance was better than the result of zeolite mixture.

• 유체기계공업학회:학술대회논문집
• /
• 2006.08a
• /
• pp.569-572
• /
• 2006

In present study, the influence of changing combustor pressure on flame stabilization and nitrogen oxide (NOX) emission in the swirl flame with secondary fuel injection was investigated. The combustor pressure was controlled by suction at combustor exit. Pressure index ($P^*=Pabs/Patm$), where Pabs and Patm indicated the absolute pressure and atmosphere pressure, was controlled in the range of 0.7~1.15 for each equivalence ratio conditions. It could be observed that flame stable region became narrower with decreasing equivalence ratio and pressure index. In this combustion system, stable flames were formed until $P^*=\;0.7$. Emission index decreased with decreasing pressure index for overall equivalence ratio conditions and NOx reduction rates were almost identical for $P^*<1$ regardless of equivalence ratio though EINOx values showed different level with change of equivalence ratio for $P^*{\geq}1$. It is also observed that EINOx decreased with increasing secondary fuel injection ratio. Emission index of nitric oxide was controllable by adjusting the changing combustor pressure and injecting secondary fuel and this NOx reduction technology is applicable to industrial furnaces and air conditioning system.

• Journal of the Korea Convergence Society
• /
• v.10 no.4
• /
• pp.131-138
• /
• 2019

Diesel engines have important advantages over its gasoline counterpart including high thermal efficiency, high fuel economy and low emissions of CO, HC and $CO_2$. However, NOx reducing is more difficult on diesel engines because of the high $O_2$ concentration in the exhaust, marking general three way catalytic converter ineffective. Two method available technologies for continuous NOx reduction onboard diesel engines are Urea-SCR and LNT. The implementation of the Urea-SCR systems in design engines have made it possible for 2.5l and over engines to meet the tightened NOx emission standard of Euro-6. In this study, we investigate the characteristics of NOx reduction with respect to engine speed, load, types of catalyst and the $NH_3$/NOx ratio and present the conditions which maximize NOx reduction. Also we provide detailed experimental data on Urea-SCR which can be used for the preparation for standards beyond Euro-6.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.448-453
• /
• 2003

In this study, the effects of oxygen component in fuel and exhaust gas recirculation(EGR) method on the exhaust emissions has been investigated for a D.I. diesel engine. It was tested to estimate change of exhaust emission characteristics for the commercial diesel fuel and oxygenate blended fuel which has five kinds of blending ratio. Dimethoxy methane(DMM) contains oxygen component 42.5% in itself. and it is a kind of effective oxygenated fuel for reduction of smoke emission. It was affirmed that smoke emission was decreased with increasing of DMM blending ratio. But, NOx emission was increased compared with commercial diesel fuel. It was needed a NOx reduction countermeasure that EGR method was used as a countermeasure for NOx reduction. It was found that simultaneous reduction of smoke and NOx emission was achieved with DMM blended fuel and cooled EGR method($10{\sim}15%$).

• Transactions of the Korean Society of Automotive Engineers
• /
• v.10 no.3
• /
• pp.77-84
• /
• 2002

Measurements of NO and NOx emission of laminar partially premixed LPG/air flames with and without acoustic excitation are reported. The NOx emission at the tailpipe of a combustion chamber is determined by chemiluminescent analyser. The NOx measurements are taken in flames with several different center tube equivalance ratio( ø$\sub$o/), and overall equivalace ratio(ø$\sub$o/) for a fixed fuel flowrate. The NOx emission decrease to reach a minimum value at an optimum ø$\sub$c/ 2. Theø$\sub$c/ 2 flame gives a compromise of thermal NO and prompt NO mechanism. In the case of excitation. the visual shape of the flame is changed from laminar flame to turbulent-like flame. With increasing levels of excitation amplitude, an optimum value of the NO and NOx emission exists. A shorter flame caused by the enhanced upstream mixing due to acoustic excitation results in the reduction of NO and NOx emission in the present flames. The reduction of flame length affects the shorter residence time of center tube mixture, and significantly influences the NOx reduction.