• 한국연소학회:학술대회논문집
• /
• 한국연소학회 2006년도 제32회 KOSCO SYMPOSIUM 논문집
• /
• pp.69-74
• /
• 2006

An Experimental study was conducted on $CO_2$ recycle combustion heating system using pure oxygen instead of conventional air as an oxidant, which is thereby producing a flue gas of mostly $CO_2$ and water vapor($H_2O$) and resulting in higher $CO_2$ concentration. The advantages of the system are not only the ability to control high temperatures characteristic of oxygen combustion with recycling $CO_2$. but also the possibility to reduce NOx emission in the flue gas. A small scale industrial reheating furnace simulator and specially designed variable flame burner were used to characterize the $CO_2$ recycle oxy-fuel combustion, such as the variations of furnace pressure, temperature and composition in the flue gas during recycle. It was found that $CO_2$ concentration in the flue gas was about 80% without $CO_2$ recycle, but increased to $90{\sim}95%$ with $CO_2$ recycle. The furnace temperature and pressure was decreased due to recycle and the NOx emission was also reduced to maintain under 100ppm.

• KEPCO Journal on Electric Power and Energy
• /
• 제2권2호
• /
• pp.285-291
• /
• 2016

In chemical-looping combustion, pure oxygen is transferred to fuel by solid particles called as oxygen carrier. Chemical-looping combustion process usually utilizes a circulating fluidized-bed process for fuel combustion and regeneration of the reduced oxygen carrier. The performance of an oxygen carrier varies with the active metal oxide and the raw support materials used. In this work, spraydried Mn-based oxygen carriers were prepared with different raw support materials and their physical properties and oxygen transfer performance were investigated to determine that the raw support materials used are suitable for spray-dried manganese oxide oxygen carrier. Oxygen carriers composed of 70 wt% $Mn_3O_4$ and 30 wt% support were produced using spray dryer. Two different types of $Al_2O_3$, ${\gamma}-Al_2O_3$ and ${\alpha}-Al_2O_3$, and $MgAl_2O_4$ were applied as starting raw support materials. The oxygen carrier prepared from ${\gamma}-Al_2O_3$ showed high mechanical strength stronger than commercial fluidization catalytic cracking catalyst at calcination temperatures below $1100^{\circ}C$, while the ones prepared from ${\alpha}-Al_2O_3$ and $MgAl_2O_4$ required higher calcination temperatures. Oxygen transfer capacity of the oxygen carrier prepared from ${\gamma}-Al_2O_3$ was less than 3 wt%. In comparison, oxygen carriers prepared from ${\alpha}-Al_2O_3$ and $MgAl_2O_4$ showed higher oxygen transfer capacity, around 3.4 and 4.4 wt%, respectively. Among the prepared Mn-based oxygen carriers, the one made from $MgAl_2O_4$ showed superior oxygen transfer performance in the chemical-looping combustion of $CH_4$, $H_2$, and CO. However, it required a high calcination temperature of $1400^{\circ}C$ to obtain strong mechnical strength. Therefore, further study to develop new support compositions is required to lower the calcination temperature without decline in the oxygen transfer performance.

• 한국연소학회지
• /
• 제18권4호
• /
• pp.1-11
• /
• 2013

The oxy-fuel combustion is $CO_2$ capture technology that uses mixture of pure $O_2$ and recirculated exhaust as oxidizer. Currently some Oxy-fuel power plants demonstration project is underway in worldwide. Meanwhile research project for converting 125 MWe Young-Dong power plant to 100 MWe oxy-fuel power plants is progress. In this paper, 1 D process analytical approach was applied for conducting process design and operating parameters sensitivity analysis for oxy-fuel combustion of Young-Dong power plant. As a result, appropriate gas recirculation rates was 74.3% that in order to maintain normal rating superheater, reheater steam temperature and boiler heat transfer patterns. And boiler efficiency 85.0%, CPU inlet $CO_2$ mole concentration 71.34% was predicted for retrofitted boiler. The oxygen concentration in the secondary recycle gas is predicted as 27.1%. Meanwhile the oxygen concentration 22.4% and moisture concentration 5.3% predicted for primary recycle gas. As the primary and secondary gas recirculation increases, then heat absorption of the reheater is tends to increases whereas superheater side is decreased, and also the efficiency is tends to decrease, according to results of sensitivity analysis for operating parameters. In addition, the ambient air ingression have a tendency to lead to decline of efficiency for boiler as well as decline of $CO_2$ purity of CPU inlet.

• 한국연소학회지
• /
• 제21권4호
• /
• pp.39-47
• /
• 2016

The aims of this research were to investigate combustion characteristics of lab-scale pressurized oxy-fuel combustion(POFC) system. In this study, the reactor, 800 mm long, was equipped with co-axial burner. Low calorific value syngas that is composed of mainly CO and $H_2$ was used as fuel whereas pure oxygen was used as an oxidant. Thermal heat input to the reactor varied from 2.6 kW to 6.1 kW. The reactor pressure also increases from atmospheric up to 15 bar. The results show that as the pressure increase, the temperature of reactor decreases on the whole in all cases. A significant temperature drop was observed especially at the bottom section of the reactor that exist flame. In addition, the flame instability increases as the pressure increases. Furthermore $NO_x$ emissions increases from atmospheric up to 2 bar. However beyond 2 bar, $NO_x$ emission reduces as pressure increases. Lastly $NO_2$ ratio in $NO_x$ also increases as pressure increases.

• 한국수소및신에너지학회논문집
• /
• 제8권1호
• /
• pp.5-10
• /
• 1997

Because of environmental pollution and reserve limitations of fossil fuels, several alternative energies have been developing. One of them, the hydrogen is researched as a highly probable solution. In this study pure hydrogen gas and oxygen gas are burned in combustor to reduce the emission, and a gas turbine is used. Cooling water around the combustor recovers the cooling heat loss to useful work by being expanded from liquid to vapor, being injected into the combustor and making pressure rise with working fluid to get more turbine power. Because pure hydrogen and oxygen are used, there is no carbonic emission such as CO, $CO_2$, HC nor $NO_x$, and $SO_x$. The power is obtained by turbine system, which makes lower noise and vibration than any reciprocating engine. Running of a turbine is searched under various conditions of hydrogen flow rate and water injection rate. Maximum speed of the turbine is obtained when the combustion reaches steady state. It is enable to determine the optimum rate between hydrogen flow and water injection which makes turbine run maximum speed.

• 한국지열·수열에너지학회논문집
• /
• 제18권4호
• /
• pp.12-21
• /
• 2022

Steam assisted gravity drainage(SAGD) is a process that drills well in the underground oil sands layer, injects hightemperature steam, lowers the viscosity of buried bitumen, and recovers it to the ground. Recently, direct contact steam generator(DCSG) is being developed to maximize steam efficiency for SAGD process. The DCSG requires high technology to achieve pressurized combustion and steam generation in accordance with underground pressurized conditions. Therefore, it is necessary to develop a combustion technology that can control the heat load and exhaust gas composition. In this study, process analysis of high-pressurized DCSG was conducted to apply oxygen enrichment technology in which nitrogen of the air was partially removed for increasing steam production and reducing fuel consumption. As the process analysis conditions, methane as the fuel and normal air or oxygen enriched air as the oxidizing agent were applied to high-pressurized DCSG process model. A simple combustion reaction program was used to calculate the property variations for combustion temperature, steam ratio and residual heat in exhaust gas. As a major results, the steam production efficiency of DCSG using the pure oxygen was about 6% higher than that of the normal air due to the reducing nitrogen in the air. The results of this study will be used as operating data to test the demonstration device.

• 청정기술
• /
• 제27권4호
• /
• pp.367-371
• /
• 2021

순산소 석탄 화력 발전 시스템은 CO₂ 가스 회수 및 저장 기술(CCS: carbon capture & storage)의 하나로 순산소와 재순환된 연소가스를 이용하여 석탄 연소를 수행하는 기술이다. 이는 이산화탄소와 질소가 혼합된 배출 가스를 생산하는 기존의 공기 연소 시스템과 달리 공기 중의 산소를 먼저 분리하여 생산된 순산소와 재순환된 연소 가스를 이용하여 석탄을 연소하면 이산화탄소와 질소를 분리하는 후처리 공정 없이 이산화탄소만으로 이루어진 배출 가스를 생성하여 이의 저장을 용이하게 하는 기술이다. 본 연구에서는 O₂/CO₂ 혼합 모의 가스를 이용하여 순산소 연소 시 발생되는 대기오염물질인 NO, SO₂의 생성 특성을 살펴보았다. 반응 온도를 900 ℃ ~ 1200 ℃, 산소 분율을 30% ~ 50%로 변화시키면서 실험한 결과 생성 가스 내 NO 및 SO₂의 농도는 반응 온도와 산소 분율이 증가할수록 증가하는 현상을 나타내었으며 CO₂의 분율도 증가하는 현상을 나타내었다. 순산소 연소에서 30% O₂/CO₂를 이용한 연소와 air 조건인 21% O₂/N₂ 연소에서 NO 발생을 비교한 결과 양쪽 모두 반응 온도에 따라서 NO 발생이 증가하게 되며 순산소 연소 조건에서 air 연소에 비하여 약 40 ~ 80 ppm까지 NO 발생이 낮아지는 현상을 나타내었다.

• 한국수소및신에너지학회논문집
• /
• 제14권1호
• /
• pp.24-34
• /
• 2003

For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion may yield great advantages for the savings of energy to $CO_2$ separation and suppressing the effect on environment, In chemical-looping combustor, fuel is oxidized by metal oxide medium in a reduction reactor. Reduced particles are transported to oxidation reactor and oxidized by air and recycled to reduction reactor. The fuel and the air are never mixed, and the gases from reduction reactor, $CO_2$ and $H_2O$, leave the system as separate stream. The $H_2O$ can be easily separated by condensation and pure $CO_2$ is obtained without any loss of energy for separation. In this study, five oxygen carrier particles such as NiO/bentonite, NiO/YSZ, $(NiO+Fe_2O_3)VYSZ$, $NiO/NiAl_2O_4$, and $Co_{\chi}O_y/CoAl_2O_4$ were examined &om the viewpoints of reaction kinetics, oxygen transfer capacity, and carbon deposition characteristics. Among five oxygen particles, NiO/YSZ particle is superior in reaction rate, oxygen carrier capacity, and carbon deposition to other particles. However, at high temperature ($>900^{\circ}C$), NiO/bentonite particle also shows enough reactivity and oxygen carrier capacity to be applied in a practical system.

• 한국연소학회지
• /
• 제21권2호
• /
• pp.7-14
• /
• 2016

Evaporation and combustion characteristics of fuel droplet with carbon nanoparticle were investigated in a rapid compression machine(RCM). RCM is an experimental equipment to simulate one compression stroke of reciprocating engine. Nitrogen was charged into reaction chamber for evaporation experiment, while oxygen was charged for combustion experiment. N990 carbon black and n-heptane were used to synthesize the carbon nanofluids. Surfactant, span80, was used to make synthesis easier. The droplet pictures were taken using a high speed camera with 500 frames per second. Thermocouple, of which tip is $50{\mu}m$, was used not only to measure transient bulk temperature, but also to suspend the droplet. Reaction chamber temperature was calculated from pressure data. The evaporation rate of nanofluids was improved compared to pure fuel. The ignition delay was promoted due to the nanoparticle, but the burning rate was decreased.

• International Journal of Safety
• /
• 제4권2호
• /
• pp.24-29
• /
• 2005

An experimental study was presented for extinguishing characteristics of liquid fuel fire by water mist($Dv_{0.99}{\leq}200{\mu}m$) containing potassium acetate and sodium acetate trihydrate. To evaluate the extinguishing performance of water mist containing additives, the evaporation characteristics of a water droplet on a heated surface was examined. The evaporation process was recorded by a charge-coupled-device camera. Also, small-scale extinguishing tests were conducted for n-heptane pool fire in ventilated space. During the experiments, flame temperatures were measured, and concentrations of oxygen and carbon monoxide were analyzed by a combustion gas analyzer. The average evaporation rate of water droplet containing additives was lower than that of pure water at a given surface temperature and decreased with the concentration increase due to the precipitation of salt in the liquid-film and change of surface tension. In case of using additives, the fire extinguishing times was shorter than that of pure water at a given discharge pressure and it was because the momentum of a water droplet containing additives was increased. And also dissociated metal atoms, potassium or sodium, were reacted as a scavenger of the major radical species OH, H which were generated for combustion process. Moreover, at a high pressure of 4 MPa, the fire was extinguished through blowing effect as well as primary extinguishing mechanisms.