• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.39-41
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• 2012

The influence of coal blending methods such as out-furnace (external or pre-mixed) blending and in-furnace (initially non-mixed) blending with different excess oxygen (highest, medium, and lowest stoichiometric conditions) on unburned carbon and NOx emissions of blend combustion in an entrained flow reactor (EFR) has been analyzed, using experimental and numerical approaches for binary coals used by Korean power plants. The results confirm that under the medium condition, contrasting processes such as reactive and un-reactive effects occur with SBRs in the out-furnace blending method. The in-furnace blending method results in an improvement in the efficiency of unburned carbon fractions and a further reduction in the NOx emission. Under the highest condition, the unburned carbon fraction in both the out-furnace and the in-furnace blending methods corresponds with the tendency under the medium condition with contrasting processes of lower magnitude, whereas the NOx emission in the highest condition increases slightly. Under the lowest conditions, the unburned carbon fraction in the out-furnace blending method gradually decreases as SBR decreases, without a competition effect. The reduction of NOx emission under the lowest conditions is more effective than those under other conditions for the two blending methods because of a homogeneous and heterogeneous NOx reduction mechanism.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.81-88
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• 2002

It's well known that with the increase of preheated air temperature NOx is increasing ,while the energy consumption is decreasing. In this study the experimental study was carried out to find out a new method breaking the above-mentioned old concept. From the variation of configuration of gas nozzle and hot test on the temperature distribution and NOx, it was found out that the reduction of NOx was due to the effect of internal gas recirculation, which will be caused by air emitting velocity from burner nozzle.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.2
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• pp.180-186
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• 2009

To meet the NOx limit without a penalty of fuel consumption, urea SCR system is currently regarded as promising NOx reduction technology for diesel engines. SCR system has to achieve maximal NOx conversion in combination with minimal $NH_3$ slip. In this study, as a basic research to develop an algorithm for urea injection control, the characteristics of engine out NOx emission and behavior of NOx reduction during steady-state and transient conditions were investigated using 2L DI diesel engine. Test results show that on increasing the catalyst temperature the variations in the outlet NOx concentration are faster and maximal allowable $NH_3$ storage exponentially decreases. For change from a low to high engine load, it can be seen that a few seconds after load-step is required to reach full NOx conversion and the adsorbed amount of $NH_3$ at lower temperature desorb during the next temperature increase, causing $NH_3$ slip. Engine out NOx emission needs to be corrected because NOx emissions just after step load is lower than that of steay state condition.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.1123-1128
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• 2001

In this study, As a plan of essential solution for out-door air pollution, a basic study was carried out to develop a paint with photocatalystic $TiO_{2}$ which can eliminate the $NO_{X}$ from atmosphere. A series of Experiment were carried out according to kind of binder, photocatalyst, light source. Through Experiment of out-door exposure test, the endurance ability and NOx removal efficiency of the specimen were evaluated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.12
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• pp.1793-1801
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• 2001

A study of low NOx atomizer was carried out to reduce nitrogen oxides(NOx) in a liquid fuel burner flame. The basic concept of NOx reduction in this atomizer is the fuel 2-staging combustion which is generated by a single atomizer forming two different stoichiometric flames. Two orifices swirl atomizer was selected and modified to realize this concept, and it was tested to obtain the design process of low NOx atomizer. These experiments were achieved to find out the relationship between the injection pressures and the flow rate, spray angle and drop size of swirl atomizer as well as to confirm the NOx reduction concept in real plant(power boiler). In comparison between experimental and theoretical results, the correct discharge coefficient and spray angle were obtained. In real burning test, NOx reduction rate was reached to above 27% of the case using conventional swirl atomizer.

• Environmental Engineering Research
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• v.11 no.3
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• pp.149-155
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• 2006

NOx reduction experiments were conducted by direct injection of urea into a diesel fueled, combustion-driven flow reactor which simulated a single engine cylinder ($966cm^3$). NOx reduction tests were carried out over a wide range of air/fuel ratios (A/F=20-40) using an initial NOx level of 530ppm, and for normalized stoichiometric ratios of reductant to NOx (NSR) of 1.5 to 4.0. The results show that effective NOx reduction with urea occurred over an injection temperature range of 1100 to 1350K. NOx reduction increased with increasing NSR values, and about a 40%-60% reduction of NOx was achieved with NSR=1.5-4.0. Most of the NOx reduction occurred within the cylinder and head section (residence time <40msec), since temperatures in the exhaust pipe were too low for additional NOx reduction. Relatively low NOx reduction is believed to be due to the existence of higher levels of CO and unburned hydrocarbons (UHC)inside the cylinder, and large temperature drops along the reactor. Injection of secondary combustible additives (diesel fuel/$C_2H_6$) into the exhaust pipe promoted further substantial NOx reduction (5%-30%) without shifting the temperature windows. Diesel fuel was found to enhance NOx reduction more than $C_2H_6$, and finally practical implications are further discussed.

• 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.

• Proceedings of the KSME Conference
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• 2000.11b
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• pp.715-719
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• 2000

It is reported that we are facing the serious environment pollution difficulties such as acid rain, green house effects, etc. The gaseous matter CO, NOx, SOx, VOCs which are regarded as main factors for these current pollutions are mainly emitted from power plants and vehicles. Therefore several leading countries are regulating the related laws strictly, especially exhaust emissions from a Diesel engine without an after treatment device. The Objective of this study is to find out NOx removal characteristics focused on emissions of a Diesel engine using radical at each engine speed and load. It is generated from outer air and put into a mixing chamber in the end of exhaust line. In addition, the optimum temperature condition to activate reaction by radical is experimentally carried out. Concentration of exhaust emissions is analyzed from the gas anlayzer(KaneMay) and FTIR to estimate by-products.

• International Journal of Automotive Technology
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• v.7 no.3
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• pp.269-276
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• 2006

Running tests on roads were conducted to clarify the influences of road infrastructure, traffic condition and vehicle's emission level to the amount of emission at local roadsides, and to reveal the operation patterns which can reduce the emission peaks. NOx emission peaks of two light duty freight diesel vehicles which have different emission levels were evaluated by using an on-board measurement system. Tests were carried out with various payload conditions and road conditions. As a result many NOx emission peaks were observed when the vehicles were starting or accelerating at intersections. The test vehicle which has higher emission level caused higher frequency and level of NOx emission peaks. Shifting up at lower engine speed in combination with lower acceleration brought out not only reduction of NOx emission peaks level but also of $CO_2$ mass emission.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.11
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• pp.1616-1623
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• 2001

A basic experimental study has been carried out to find out the design parameters of fuel 2-staging atomizers in order to reduce nitrogen oxides(NOx) rate emitted from the steam boilers used the liquid fuel. The heavy fuel oil(B-Coil) and fuel 2-staging Y-jet twin-fluid atomizers were adopted in this study. The results of this paper were obtained from the real as well as the model scale atomizers. In the case of model atomizers test, NOx reduction rate was strongly dependent on the staged fuel rate, but it was weakly dependent on the injection hole arrangement and air swirl conditions. The real scale atomizers was designed and manufactured on the base of these test results, and those was mounted and operated in the real boiler generates 185 ton steam per an hour. The reduction rate of the model and real plant was reached 10∼30% of base NOx by atomizers. but dust was sharply increased in the low O$_2$combustion region of the real plant.