• Title, Summary, Keyword: Exhaust gas temperature

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Mixer design for improving the injection uniformity of the reduction agent in SCR system

  • Hwang, Woohyeon;Lee, Kyungok
    • Journal of the Korea Society of Computer and Information
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    • v.22 no.1
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    • pp.63-69
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    • 2017
  • In this paper, we propose a method to optimize the geometry and installation position of the mixer in the selective catalytic reduction (SCR) system by computational fluid dynamic(CFD). Using the commercial CFD software of CFD-ACE+, the flow dynamics of the flue gas was numerically analyzed for improving the injection uniformity of the reduction agent. Numerical analysis of the mixed gas heat flow into the upstream side of the primary SCR catalyst layer was performed when the denitrification facility was operated. The characteristics such as the flow rate, temperature, pressure loss and ammonia concentration of the mixed gas consisting of the flue gas and the ammonia reducing gas were examined at the upstream of the catalyst layer of SCR. The temperature difference on the surface of the catalyst layer is very small compared to the flow rate of the exhaust gas, and the temperature difference caused by the reducing gas hardly occurs because the flow rate of the reducing gas is very small. When the mixed gas is introduced into the SCR reactor, there is a slight tendency toward one wall. When the gas passes through the catalyst layer having a large pressure loss, the flow angle of the exhaust gas changes because the direction of the exhaust gas changes toward a smaller flow. Based on the uniformity of the flow rate of the mixed gas calculated at the SCR, it is judged that the position of the test port reflected in the design is proper.

An Investigation of Combustion Emission Characteristics of Kerosene Fan Heater with Addition of Water Droplets by Ultrasonic Atomizer (초음파 수첨가 연소에 의한 석유 홴 히터의 배기가스 특성 고찰)

  • Kim, J.K.;Jeong, K.J.
    • Journal of Power System Engineering
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    • v.3 no.3
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    • pp.44-53
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    • 1999
  • This study is concerned with the emission characteristics of kerosene fan heater, which is burned with kerosene and water droplets simultaneously in the burner, in order to prohibit the emissions of harmful exhaust gas and reduce smell caused by incomplete combustion, and the addition of water droplets to the conventional kerosene fan heater was performed by ultrasonic atomizer. For the investigation of this study, the measurement of exhaust gas components and exhaust gas temperature was carried out by using an automatic combustion gas analyser and $NO_x$ analyser, and the measurement of consumption weight of oil and water was obtained by using electric digital balance. Consequently, according as the water percent weight ratio of about $21{\sim}23%$ was supplied for this study, it was found that the combustion-generated $NO_x$ and CO emissions were reduced very largely, but the emissions of $O_2\;and\;CO_2$ and the temperature of exhaust gas were not changed.

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Effect of Recirculation of Rotary Kiln Exhaust Gas for the Carbonation of Lime on the Combustion Conditions and the Amounts of NOx (생석회 탄산화를 위한 회전로 배가스 재순환이 연소 및 NOx 발생양에 미치는 영향)

  • Lee Man-Seung;Lee Si-Hyunh
    • Resources Recycling
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    • v.12 no.1
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    • pp.41-47
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    • 2003
  • In order to improve the hydration resistance of lime in the air at room temperature, carbonation and hydration experiments have been conducted. Carbonation of the surface of lime by about 6 wt% was needed to suppress the hydration of lime used in steel-making. The effect of recirculation of rotary kiln exhaust gas for the carbonation of lime on the combustion temperature and NOx concentration was analyzed by thermodynamics. From the thermodynamic calculation results, it was frond that the equi-librium combustion temperature and NOx concentration decreased with increasing volume percentage of exhaust gas.

Comparative Part Load Performance Analysis of Gas Turbine Power Generation Systems Considering Exhaust Heat Utilization (배열 이용도를 고려한 가스터빈 발전시스템의 부분부하 성능 비교분석)

  • Kim, T.S.
    • The KSFM Journal of Fluid Machinery
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    • v.6 no.3
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    • pp.28-35
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    • 2003
  • This paper presents analysis results for the effect of power control strategies on the part load performance of gas turbine based power generation systems utilizing exhaust heat of the gas turbine such as combined cycle power plants and regenerative gas turbines. For the combined cycle, part load efficiency variations were compared among different single shaft gas turbines representing various technology levels. Power control strategies considered were fuel only control and IGV control. It has been observed that gas turbines with higher design performances exhibit superior part load performances. Improvement of part load efficiency of the combined cycle by adopting air flow modulation was analyzed and it was concluded that since the average combined cycle performance is affected by the range of IGV control as well as its temperature control principle, a control strategy appropriate for the load characteristics of the individual plant should be adopted. For the regenerative gas turbine, it is likewise concluded that maintaining exhaust temperature as high as possible by air flow rate modulation is required to increase part load efficiency.

CFD Analysis on Effect of Pressure Drop and Flow Uniformity with Geometry in 13" Asymmetric DPF (13" 비대칭 DPF 내 형상에 따른 배압 및 유동균일도 영향에 관한 전산해석연구)

  • HAN, DANBEE;BYUN, HYUNSEUNG;BAEK, YOUNGSOON
    • Transactions of the Korean hydrogen and new energy society
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    • v.31 no.6
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    • pp.614-621
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    • 2020
  • Recently, as the fine dust is increased and the emission regulations of diesel engines are strengthened, interest in diesel soot filtration devices is rapidly increased. In particular, there is a demand for technology development for higher efficiency of diesel exhaust gas after-treatment devices. As part of this, many studies conducted to increase the exhaust gas treatment efficiency by improving the flow uniformity of the exhaust gas in the DPF and reducing the pressure drop between the inlet and outlet of disel particle filter (DPF). In this study, computational fluid dynamics (CFD) simulation was performed when exhaust gas flows into the canning reduction device equipped with a 13" asymmetric DPF in order to maintain the flow uniformity in the diesel exhaust system and reduce the pressure. In particular, a study was conducted to find the geometry with the smallest pressure drop and the highest flow uniformity by simulating the DPF I/O ratio, exhaust gas temperature, inlet-outlet pressure and flow uniformity according to the geometry and hole size of distributor.

CHANGE OF CATALYST TEMPERATURE WITH UEGI TECHNOLOGY DURING COLD START

  • CHO Y.-S.;KIM D.-S.
    • International Journal of Automotive Technology
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    • v.6 no.5
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    • pp.445-451
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    • 2005
  • Most of the pollutants from passenger cars are emitted during the cold-transient phase of the FTP-75 test. In order to reduce the exhaust emissions during the cold-transient period, it is essential to warm up the catalyst as fast as possible after the engine starts, and the Unburned Exhaust Gas Ignition (UEGI) technology was developed through our previous studies to help close-coupled catalytic converters (CCC) reach the light-off temperature within a few seconds after cold-start. The UEGI system operates by igniting the unburned exhaust mixture by glow plugs installed upstream of the catalyst. The flame generates a high amount of heat, and if the heat is concentrated on a specific area of monolith surface, then thermal crack or failure of the monolith could occur. Therefore, it is very important to monitor the temperature distribution in the CCC during the UEGI operation, so the local temperatures in the monolith were measured using thermocouples. Experimental results showed that the temperature of CCC rises faster with the UEGI technology, and the CCC reaches the light-off temperature earlier than the baseline case. Under the conditions tested, the light-off time of the baseline case was 62 seconds, compared with 33 seconds for the UEGI case. The peak temperature is well under the thermal melting condition, and temperature distribution is not so severe as to consider thermal stress. It is noted that the UEGI technology is an effective method to warm up the catalyst with a small amount of thermal stress during the cold start period.

An Axisymmetrical Study on the Secondary Reaction of Launch Vehicle Turbine Exhaust Gas Using the Detailed Chemistry Model (상세 화학반응 모델을 이용한 발사체 터빈 배기가스의 이차연소 해석의 축대칭 해석)

  • Kim, Seong-Lyong;Kim, In-Sun
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • pp.857-862
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    • 2011
  • 3 dimensional turbine exhaust gas flow was simplified to an axisymmetrical flow and calculated with detailed chemistry models. GRI 35 species-217 reaction step model and simplified 11 species 15 reaction model was applied to the secondary reaction of the turbine exhaust gas and compared. All the model captured the secondary combustion on the base region, and the temperature was 600K higher than that without turbine exhaust gas. This means the local temperature of the base can be higher in the case of real 3 dimensional flow. The simplified model show the similar results to the GRI detailed chemistry model although the former affected the engine plume structure slightly.

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Effect of Exhaust Gas Recirculation on Ignition Characteristics of N-heptane/N-butanol Blend Fuels in Rapid Compression Machine (급속압축기에서 노말헵탄 노말부탄올 혼합연료의 점화지연 / 특성에 배기가스 재순환이미치는 영향)

  • Kang, Ki-Joong
    • Journal of the Korean Society of Mechanical Technology
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    • v.19 no.6
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    • pp.778-784
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    • 2017
  • The autoignition characteristics of n-heptane/n-butanol were investigated both experimentally and numerically. The effects of oxygen concentration and exhaust gas recirculation rate on the autoignition characteristics were evaluated. A rapid compression machine was employed to measure ignition delay times of blended fuels. A numerical study on the ignition delay time was performed using the CHEMKIN-PRO software to calculate ignition delay time and predict the chemical species in the combustion process. The results revealed that the ignition delay time increased with decreasing oxygen concentration due to the thermal load effect of nitrogen. The oxidation reaction of n-heptane in a low temperature regime was limited with decreasing oxygen concentration. The ignition delay time sharply decreased with exhaust gas recirculation because of the intermediate species in the exhaust gas. Exhaust gas recirculation reduced first ignition delay dramatically. However, the time interval between the first and main ignition increased with increased exhaust gas recirculation.

A Study on the Exhaust Performance of Contaminant by Establishment Height of Hood (랜지후드의 설치 높이에 따른 오염물질의 배출성능에 관한 연구)

  • 송필동;박명길;함진식
    • Proceeding of Spring/Autumn Annual Conference of KHA
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    • pp.99-104
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    • 2001
  • This paper is contents that experiment exhaust performance of contaminant by establishment height gas table and hood establishment height. Hood made to control from gas table to 10 centimeters space from 30 centimeters to 70 centimeters. Exhaust fan operated by 110V, 160V, 220V, and gas used propane gas. Center part appeared highest as result that measure wind velocity and temperature from hood lower part. Wind velocity from hood lower part was proved that dominate contaminant exhaust performance. Exhaust performance of carbon dioxide and heat showed that 30 centimeters case overmatches because establishment height of hood compares 80 centimeters. Case of carbon dioxide of exhaust performance by establishment height of hood overmatched more than heat.

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A Study on the Reduction of $NO_x$ Emission from Dual Fuel Engine for Co-generation System (열병합발적용 Dual Fuel Engine의 질소산화물 배출저감에 관한 연구)

  • 정일래;김용술;심용식
    • Journal of Korean Society for Atmospheric Environment
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    • v.7 no.1
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    • pp.31-40
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    • 1991
  • This study shows the correlation between $NO_x$ emission in the exhaust gas and various operation factors of dual fuel engine for Co-generation system. General tendency was shown that the thermal efficiency was lowered by the change of operation factors. However these were not confirmed on this experiment. Increasing T4 temperature (exhaust gas temperature at turbo-charger inlet) reduces $NO_x$ emission rate. The higher T4 temperature requires lower excess air as the excess air ratio is controlled by T4 temperature on gas mode operation. Another tendency was that $NO_x$ emission rate is reduced in case of increasing boost air temperature, quantity of pilot oil or bypassing flue gas through the exhaust gas boiler. The diameter of the fuel injection nozzle was changed smaller than design value and the injection timing was readjusted. Thus $NO_x$ emission rate could be reduced as retarding injection timing and changing hole diameter of fuel injection nozzle, however maxium engine out-put was decreased by changing fuel nozzle on the diesel mode operation.

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