• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.1686-1691
• /
• 2004

The effect of recirculated exhaust gas on performance and exhaust emissions with FGR rate are investigated by using a natural circulation, pressurized draft and water tube boiler with FGR system operating at several boiler loads and over fire air(OFA) damper openings. The purpose of this study is to apply the FGR system to a power plant boiler for reducing $NO_{x}$ emissions. To activate the combustion, the suction damper of two stage combustion system installed in the upper side of wind box is opened by handling the lever between $0^{\circ}$ and $90^{\circ}$ , and the OFA with 0 to 20% into the flame is supplied, as the combustion air supplied to burner is reduced. It is found that the fuel consumption rate divided by evaporation rate does not show an obvious tendency to increase or decrease with rising the FOR rate, and $NO_{x}$ emissions are decreased, at the same OF A damper opening, as FOR rates are elevated and boiler loads are dropped.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.31 no.5
• /
• pp.405-415
• /
• 2007

The effects of recirculated exhaust gas on exhaust emissions under four kinds of nozzle tip with the different fuel consumption rates are experimentally investigated by using an once-through boiler with a FGR system. The purpose of this study is to develop the FGR control system for reducing $NO_x$ emissions in boilers. Intake and exhaust oxygen concentrations, and equivalence ratio are considered to figure out the effect of FGR rate on exhaust emissions at various fuel consumption rates. It is found that $NO_x$ emissions are markedly decreased, while soot emissions are increased owing to the drop of intake and exhaust oxygen concentrations, and the rise of equivalence ratio as FGR rates are elevated. One can also conclude that the reduction in $NO_x$ emissions is more considerably influenced by the variation of equivalence ratio due to the FGR rate than the fuel consumption rate.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.11 no.4
• /
• pp.37-43
• /
• 2003

The exhaust gas recirculation (EGR) is needed for one of various strategies to reduce NOx emission. But to get the proper EGR rate, the intake and exhaust system become complicated, also application of EGR system is difficult because of the penalty in fuel consumption and the increase in particulate matter. This study is focused on the development of EGR valve using the electrical method. The effects of EGR on the characteristics of NOx, CO, CO2 emissions and particulate mater have been investigated using small-displacement size 0.8-liters engine of diesel passenger car operating at several loads and speeds. After the analysis and comparison between conventional E-EGR valve and developed E-EGR valve performance by test bench, the estimation of vehicle application was executed through the EGR map and CVS-75 test result measured on the chassis dynamometer.

• Journal of the Korean Institute of Gas
• /
• v.22 no.3
• /
• pp.7-12
• /
• 2018

Thermal NOx is generated in a high temperature environment in a combustion facilities. Exhaust gas recirculation method is widely used among various methods for reducing nitrogen oxides in combustion devices. In the present study, the computational fluid dynamic analysis was accomplished to elucidate the cold flow characteristics in the flue gas recirculation burner with both outlets opening. Because the reciculation pipes is installed toward the tangential direction, the swirling flow is formulated in the burner and the phenomenon of the reverse flow creation is detected at the center area of circular burner. We are confirmed that this is the similar trend with the burner with one side outlet closed. From the present study, it was seen that the recirculated inflow from both recirculated burner outlets increased by about 5% compared to the burner with one side outlet opening. At the outlet located at the exhaust gas recirculation pipe inlet(gas exit 1), the inlet flow was formed in the entire region. At the opposite outlet(gas exit 2), the total flow was discharged, but the center part of the burner was observed to have a reverse flow. The flow rate at the gas exit 2 was 3 ~ 5 times larger than the flow rate at the gas exit 1.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.22 no.7
• /
• pp.90-97
• /
• 2014

The effects of high pressure and low pressure exhaust gas recirculation (HP/LP EGR) portion on diesel engine combustion and emissions characteristics were investigated in a 2.2 L passenger-car diesel engine. The po3rtion of HP/LP EGR was varied from 0 to 1 while fixing the mass flow rate of fresh air. The intake manifold temperature was lowered with the increasing of the portion of LP EGR, which led to the retardation of heat release by pilot injection. The lowered intake manifold temperature also resulted in low nitrogen oxide (NOx) emissions due to decreased in-cylinder temperature and prolonged ignition delay, however, the carbon monoxide (CO) emission showed opposite trend to NOx emissions. The brake specific fuel consumption (BSFC) was decreased as the portion of LP EGR increased due to lowered exhaust manifold pressure by wider open of turbocharger vane. Consequently, the trade-off relationship between NOx and BSFC could be improved by increasing the LP EGR portion.

• Korean Chemical Engineering Research
• /
• v.40 no.6
• /
• pp.681-686
• /
• 2002

In the industrial field, the theory of drying process is different from the practical application, and it is effective to reduce energy by recirculation of the heat of exhausting gas. But the study of this field may not be performed still. The cure properties of the urea resin moulding compounds was investigated according to drying temperature, drying time, recycle rate of exhausting gas and moulding temperature in the process of drying and moulding. We obtained the following results; water content of material decreases with increasing drying time and drying temperature, and the rate of drying also decreases with increasing recycle rate of exhausting gas. Specially, The cure fluidity of the urea resin moulding compounds decreases, with increasing drying temperature, recycle rate of exhausting gas and moulding temperature. And the correlation equations on water content and cure fluidity of the urea resin moulding material were obtained through a regression analysis of experimental data.

• Journal of the KSME
• /
• v.20 no.1
• /
• pp.21-30
• /
• 1980

기관의 흡기에 배기의 일부를 혼입하는 배기재순환 (Exhaust Gas Recirculation, 약해서 EGR)은 배기중의 NOx 농도를 저하시키는 효과가 있기 때문에 자동차용 기관의 배기정화를 위한 유효한 수단의 하나로 생각된다. 배기가스의 공해성분인 CO, HC NOx 중에서 CO, HC는 실용적인 처 리방법이 각각 여러종류 개발되어 있지만 NOx를 기관으로부터 배출한 후의 단계에서 처리하는 실용적인 방법은 매우 어렵다, 따라서 이와 같은 단계에 있어서는 EGR를 유효하게 이용하는 것이 NOx 저감대책의 지름길이라 할 수 있다. 그러나 EGR를 시행하는 경우, 신기의 흡입량은 EGR에 의하여 제한을 받아 감소하므로 신기의 감소분만큼 출력이 저하하는 것을 막을 도리는 없다. 따라서 장래 대부분의 자동차용기관이 EGR시스템을 정착하게 되면 동력성능을 저하시 키지 않기 위하여 EGR에 상당하는 실린더용적의 증가를 하거나, 어떠한 대책이 필요할 것이다. 그러므로 저자는 장래 EGR시스템을 장착하게될 경우를 고려하는 기관에 EGR을 시해하는 경우, 기관사이클, 연소 및 배기성분 운전 Paramater와 EGR의 관계등에 대하여 기술하고저 한다.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.19 no.5
• /
• pp.593-598
• /
• 2018

Computational fluid dynamics was used to develop a heat-recovery ventilator for preventing freezing in cold weather. An optimal internal return damper was applied, and a prototype was made for frost and freezing experiments. A total of 16 models were used to design the optimal internal return damper with the maximum exhaust recirculation ratio. The exhaust recirculation ratio of the exhaust air to the outdoor air was 59.9-62.3%. The tests showed that frost and freezing did not occur at outdoor air temperatures of $-15^{\circ}C$ or higher in both exhaust recirculation operation and normal operation. However, at an outdoor air temperature of $-20^{\circ}C$, no freezing occurred in the outdoor air area when the internal return damper was opened by 45 degrees. Heat recovery ventilators for preventing cold weather frost and freezing should be operated in two operation modes: normal and exhaust recirculation mode. An operating algorithm was developed for the heat-recovery ventilator operating in normal mode when the outdoor temperature is higher than $-15^{\circ}C$ and recirculation mode when the temperature is lower.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.40 no.4
• /
• pp.263-273
• /
• 2016

The effect of recirculated exhaust gas on performance and exhaust emissions with FGR rate are investigated by using a natural circulation, pressurized draft and water tube boiler with FGR system operating at several boiler loads and over fire air damper openings. The purpose of this study is to apply the FGR system to a power plant boiler for reducing $NO_x$ emissions. To activate the combustion, the OFA with 0 to 20% is supplied into the flame. When the suction damper of two stage combustion system installed in the upper side of wind box is opened by handling the lever between $0^{\circ}$ and $90^{\circ}$, also, the combustion air supplied to burner is changed. It is found that the fuel consumption rate per evaporation rate did not show an obvious tendency to increase or decrease with rising the FGR rate, and $NO_x$ emissions at the same OFA damper opening are decreased, as FGR rates are elevated and boiler loads are dropped. While a trace amount of soot is emitted without regard to the operation conditions of boiler load, OFA damper opening and FGR rate, because soot emissions are eliminated by the electrostatic precipitator with a collecting efficiency of 86.7%.

• Journal of the Korea Society of Computer and Information
• /
• v.25 no.2
• /
• pp.189-195
• /
• 2020

In this study, the inlet duct and guide vane of the gas floating absorption tower were redesigned to improve the desulfurization efficiency so that the exhaust gas can be uniformly introduced into the absorption tower. In order to reduce the sulfur oxide pollutants among the main sources of air pollutants in industrial boilers, the existing equipment is redesigned and solved. For this purpose, change the exhaust gas, the slurry and recycling the adsorbent to improve the removal efficiency of SOx component in the exhaust gas inside the gas floating absorption tower so as to uniformly contact. And the initial design value and CFD value for the pressure loss from the boiler outlet to the gas floating absorption tower outlet are verified. Also, the velocity distribution of the exhaust gas, the concentration distribution of the recycled adsorbent, the liquid slurry behavior, and the pressure loss were compared. The results confirmed that the desulfurization efficiency was improved because the pressure loss from the boiler outlet to the absorption tower outlet was reduced and the deflection of the exhaust gas was minimized.