• 설비공학논문집
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• 제12권2호
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• pp.120-130
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• 2000

A flow uniformity in a duct cooler of duct system of FGD(Flue Gas Desulfurization) linking a reheater and a absorber has been investigated in the present study. For this purpose, the flow characteristics according to the geometry of a vertical and horizontal vane in a curved duct of the duct system has been examined with the aid of a numerical simulation. The results indicate that the vertical vane with a little deflection toward a recirculation region makes the flow distribution in the duct cooler more uniform than that without deflection, and horizontal vane does not effect the change of the flow distribution for an angle of inclination. The mean flow uniform factor shows its maximum for duct system without the vane(case NP) and its minimum for the vertical vane with a little deflection(case P-0.8-0) .

• 한국연소학회지
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• 제16권3호
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• pp.12-20
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• 2011

Oxy-coal combustion for $CO_2$ capture in coal power plants entails a mode switching from air-firing to oxyfiring. In this study, procedure of the mode switching was investigated and discussed through experiments in pilot scale facilities: (1) a 0.3 $MW_{th}$ furnace with a vertical single burner and a FGR(Flue Gas Recirculation) system (2) a 1 $MW_{th}$ furnace with horizontal 4 burners and a FGR system. Principle of the mode switching was established and performed with control of FD fan, FGR fan, ID fan and oxygen flow rates. We have found that equivalence ratio in the oxy-firing mode should be increased more than that in the air-firing to achieve stable mode switching. Control of FD, ID and FGR fans should be performed carefully in the mode switching, in the sense of complete combustion and flame attachment. Moisture contents in the ash and the flue gas recycled to the primary oxidizer stream should be removed to prevent condensation, corrosion and duct clogging.

• 한국연소학회:학술대회논문집
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• 대한연소학회 2003년도 제27회 KOSCO SYMPOSIUM 논문집
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• pp.89-94
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• 2003

For the development of high efficiency and low emission combustion systems, high temperature air combustion technology has been tested by utilizing preheated air over 1100 K and exhaust gas recirculation. In this system, combustion air is diluted with large amount of exhaust gases ($N_2$, $CO_2$), such that the oxygen concentration is relatively low in the reaction zone, leading to low flame temperature. Since, the temperature fluctuations and sound emissions form the flame are small and flame luminosity is low, the combustion mode is expected to be flameless or mild combustion. Experiment was performed to investigate the turbulent flame structure and $NO_X$ emission characteristics in the high temperature air combustion focused on coflowing jet diffusion flames which has a fundamental structure of many practical combustion systems. The effect of turbulence has also been evaluated by installing perforated plate in the oxidizer inlet nozzle. LPG was used as a fuel. Results showed that even though $NO_X$ emission is sensitive to the combustion air temperature, the present high temperature air combustion system produce low $NO_X$ emission because it is operated in low oxygen concentration condition in excess of dilution.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1686-1691
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• 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.

• 대한기계학회논문집B
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• 제31권5호
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• pp.405-415
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• 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.

• Korean Chemical Engineering Research
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• 제47권4호
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• pp.512-517
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• 2009

순산소 연소에서 $SO_2$ 농도는 배가스의 재순환으로 인해 기존의 공기연소에 비해 3배 이상 높게 나타나고, $CO_2$ 농도와 $SO_2$ 농도가 높기 때문에 탈황현상이 기존의 공기 연소와는 다르게 나타난다. 본 연구에서는 순산소 연소조건에서 로내탈황 특성을 알아보기 위해 Drop Tube Furnace(DTF)를 이용하여, 반응온도, 유입 $SO_2$ 농도 그리고 Ca/S 비 등의 운전변수에 따른 $SO_2$ 제거효율을 측정하였으며 수분의 영향에 대해서도 알아보았다. 반응온도, 유입 $SO_2$ 농도 그리고 Ca/S 비가 증가함에 따라 $SO_2$ 제거효율은 증가하였고 유입가스 내 수분이 존재할 경우 $SO_2$ 제거효율은 약 4~6% 증가하는 것으로 나타났다.

• 대한기계학회논문집B
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• 제33권7호
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• pp.552-558
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• 2009

An experimental study using the combustor with branch tube was conducted in order to model the industry combustor with FGR (flue gas recirculation) system and to study a thermo-acoustic instability generated by a branch tube. The branch tube is a structure used to modify a system geometry and then to change its pressure field, and the thermo-acoustic instability, usually occurs in a confined geometry, can result in serious problems on industrial combustors. Thus understanding of the instability created by modifying geometry of combustor is necessary to design and operate combustor with FGR system. Pressure fluctuation in the combustion chamber was observed according to diameter and length of branch and it was compared with the solution of 1-D wave equation. It was found that branch tube affects the pressure field in the combustion chamber, and the pressure fluctuation in the combustion chamber was reduced to almost zero when phase difference between an incipient wave in the combustion chamber and a reflected wave in the branch tube is $\pi$ at the branch point. Also, the reduction of pressure fluctuation is irrespective of the installed height of branch tube if it is below $h^*=0.9$ in the close-open tube and open-open tube.

• 대한기계학회논문집B
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• 제34권4호
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• pp.409-416
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• 2010

순산소 연소와 배가스 재순환(FGR : Flue Gas Recirculation) 기술은 $CO_2$ 저감 목적으로 많은 연구자들의 관심을 받아왔다. 본 연구는 다공 동축 버너를 이용하여 산소 공급비(OFR : Oxygen Feeding Ratio)에 따른 순산소 연소 특성과 동일 조건에서 FGR 시스템을 모사하기 위하여 공급 위치에 따른 $CO_2$ 첨가 효과의 특성을 비교하는 데에 초점을 맞추었다. 순산소 연소는 당량비 0.93 에 해당하는 연료 유량 15lpm 일 때 OFR 전 영역에서 안정적이었고, 화염 구조와 길이는 OFR 에 따라 변동하였다. 순산소 연소에 $CO_2$ 를 첨가할 때, 안정, 천이, 준평형, 불안정 그리고 날림 등의 다양한 안정화 모드가 관찰되었으며, 연소로 내의 전반적인 온도분포가 감소하였고, 특히 case 4 에서 1800 K 이하로 떨어져 최대 감소 효과를 보였다. 노즐 끝단으로부터 높이에 따른 $CO_2$ 농도는 첨가된 $CO_2$ 의 체적 비율에 따라 변동하였다.

• Korean Chemical Engineering Research
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• 제48권1호
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• pp.116-120
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• 2010

CCS($CO_2$ capture & storage) 기술의 하나인 순산소 석탄화력발전 시스템에서 시스템의 안정한 운전을 위하여 연소가스 재순환이 적용되게 된다. 연소가스 재순환시 황산화물 및 분진의 농축이 발생되게 되며 일반적인 화력발전 시스템에서 탈황 및 집진과는 다른 형태의 운전조건을 나타내게 되므로 상용 석탄화력 발전소에 적용하기에 앞서 관련 연구가 필요하다. 본 연구에서는 이와 같은 순산소 석탄 연소 시스템에서 황산화물 및 분진의 효과적인 제거를 위하여 석회석을 이용한 로내탈황 및 고온 전기집진에 관한 기초적인 연구를 수행하였다. 석회석을 이용한 로내탈황에서 ash에 의한 탈황효과를 포함하여 60%의 탈황효율을 나타내었고 전기집진의 경우에는 $CO_2$ 비율이 높을수록 분진입자의 크기가 클수록 코로나 전류량의 감소로 인하여 집진효율이 저하하는 것으로 나타났다.

• 공업화학
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• 제18권1호
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• pp.29-35
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• 2007

현재 국내 화력발전소에서 운영중인 일부 배연탈황설비는 건설비 절감을 위해 설계시 여유율을 축소하여 비정상상태에 대응이 어렵고, 노후화 등으로 탈황효율이 저하하는 등 일부의 문제점이 제기되고 있다. 이러한 문제점에 대응하기 위해, 본 논문에서는 흡수액의 pH, 입구 $SO_2$ 농도, 운전 단수 변경 및 liquid distribution ring (LDR) 등의 탈황설비의 운전 조건 변경에 따른 탈황율을 검토하였으며, sulfite 이온 및 Al/Fx 이온이 석회석의 blinding에 미치는 효과에 대해 실험하였다. 흡수액 재순환 펌프를 3대 운전하였을 때는 2대 운전했을 때와 비교하여 탈황율이 최대 12% 향상하였고, LDR을 설치함에 따라 탈황효은 약 2~7%가 향상하였다. Limestone blinding 현상이 발생한 흡수액에 dibasic acid (DBA)를 500, 1,000 ppm 주입하였을 때 흡수액 용존산소가 0.5 ppm 이상 증가하며, limestone blinding 현상을 완화하였다. 흡수액 중에 $Al^{3+}$, F- 이온이 공존한 경우 석회석 용해속도는 20% 감소하였다.