• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.29 no.11 s.242
• /
• pp.1277-1284
• /
• 2005

The combustion characteristics of methane oxygen diffusion flames have been investigated to give basic information for designing industrial oxyfuel combustors. NOx reduction has become one of the most determining factors in the combustor design since the small amount of nitrogen is included from the current low cost oxygen production process. Flame lengths decreased with increasing fuel or oxygen velocity because of the enhancement of mixing effect. Correlation equation between flame length and turbulent kinetic energy was proposed. NOx concentration was reduced with increasing fuel or oxygen velocity because of the enhanced entrainment of the product gas into flame zone as well as the reduction of residence time in combustion zone.

• The KSFM Journal of Fluid Machinery
• /
• v.12 no.4
• /
• pp.30-36
• /
• 2009

Recently, there has been growing interest in the oxyfuel combustion cycle since it enables high-purity $CO_2 capture with high$ efficiency. However, the oxyfuel combustion cycle has some important issues regarding to its performance such as the requirement of water recirculation to decrease a turbine inlet temperature and proper combustion to enhance cycle efficiency. Also, Some of water vapour remain not condensed at condenser outlet because cycle working fluid contains non-condensable gas, i.e., $CO_2$. The purpose of the present study is to analyze performance characteristics of the oxyfuel combustion cycle with different turbine inlet temperatures, combustion pressures and condenser pressure. It is expected that increasing the turbine inlet temperature improves cycle efficiency, on the other hand, the combustion pressure has specific value to display highest cycle efficiency. And increasing condensing pressure improves water vapour condensing rate.

• Journal of Advanced Navigation Technology
• /
• v.22 no.2
• /
• pp.90-95
• /
• 2018

In the solid rocket motor (SRM), a thrust of rocket is generated by a nozzle so it is very important device. The nozzle of SRM is a condition of high temperature and high pressure so occurs the erosion by combustion gas. The liquid rocket propulsion systems (LRPSs) cools the nozzle by the fuel and oxidizer but SRM does not cool the nozzle. This paper deal with the development of the oxy-acetylene torch tester and investigate the thermochemical erosion properties for the thermal insulation materials of the graphite rocket nozzle throat through the experiment. The results of experiments are compared with the results of Theoretical model and identify the key factors affecting of erosion. The results is in good agreement with the experimental data.

• Journal of Korean Society of Environmental Engineers
• /
• v.31 no.5
• /
• pp.371-377
• /
• 2009

In oxy-fuel combustion, $CO_2$ concentration in the flue gas may be enriched up to 95% owing to the gas recirculation. Under the high $CO_2$ concentration, the calcination characteristic of limestone is different from that of the conventional air combustion system. In this study, three types of limestone taken from different regions in Korea were used as $SO_2$ absorbent and their calcination characteristics depending on calcination temperature were investigated. The experiments were performed to examine the effects of operating variables such as absorbent species, reaction temperatures on the $SO_2$ removal efficiency and reacted limestone particles were captured to examine the sulfur contents. The degree of calcination and the specific surface area increased with calcination temperature and $SO_2$ removal efficiency increased with reaction temperature. The results showed remarkable difference in $SO_2$ removal efficiencies between the limestone types. The sulfur content of the reacted limestone with the highest $SO_2$ removal efficiency was about 10%.

• 한국연소학회:학술대회논문집
• /
• 2007.05a
• /
• pp.54-59
• /
• 2007

In a view of capturing $CO_2$ as a greenhouse gas, an experimental study was conducted on the combustion characteristics of pulverized coal in $O_2$/$CO_2$ environment using TGA/DSC and DTF facilities. The effects of gas composition and concentration on the processes of devolatilization and char burning experienced by coal particles in combustion furnace and on the concentration of products such as $CO_2$, CO and $NO_x$ were observed using TGA/DSC and DTF respectively. As results, it were found that the rate of devolitilation is nearly independent on the $O_2$ concentration if it is over 20% but the char burning rate is a sensitive function of $O_2$ percent, and the two rates can be controlled by $O_2$ concentration in order to be similar with those of air combustion case. It was also found that high concentration $CO_2$ can be captured by oxy-coal combustion and high concentration of CO and low value of $NO_x$ are exhausted in that case. Additionally, NO reducing reaction by CO with char as catalyst was observed and a meaningful results were obtained.

• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.3062-3067
• /
• 2007

HVOF thermal spray guns are now being widely used to produce protective coatings, on the surfaces of engineering components. HVOF technology employs a combustion process to heat the gas flow and melt the coating materials which are particles of metals, alloys or cermets. Particle flow which is accelerated to high velocities and combustion gas stream are deposited on a substrate. In order to obtain good quality coatings, the analysis of torch design must be performed. The reason is that the design parameters of torch influence gas dynamic behaviors. In this study, numerical analysis is performed to predict the gas dynamic behaviors in a HVOF thermal spray gun with various torch shapes. The CFD model is used to deduce the effect of changes in nozzle geometry on gas dynamics. Using a commercial code, FLUENT which uses Finite Volume Method and SIMPLE algorithm, governing equations have been solved for the pressure, velocity and temperature distributions in the HVOF thermal spray torch.

• Korean Chemical Engineering Research
• /
• v.56 no.6
• /
• pp.856-863
• /
• 2018

In order to investigate the re-carbonation behaviors of limestones in an oxy-circulating fluidized bed combustor (Oxy-CFBC), the re-carbonation characteristics of domestic 4 different limestone samples were analyzed in a thermogravimetric analyzer (TGA-N1000) with the higher concentration of $CO_2$. Effect of reaction temperature ($600{\sim}900^{\circ}C$) and $CaCO_3$ content (77~95%) of limestones were determined and the mass change of the CaO was observed. Under the temperature of $800^{\circ}C$, the conversion rate increased with increasing reaction temperature. However, the conversion rate decreased with increasing reaction temperature over $800^{\circ}C$. In the case of $CaCO_3$ content, the conversion was remarkably different at $870^{\circ}C$. In addition, reaction rate equations for simulating the re-carbonation of limestone by using gas solid reaction models were proposed in this study.

• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.6
• /
• pp.420-425
• /
• 2011

In general, the decomposition of $CaSO_4$ formed by sulfation reaction in the in-furnace desulfurization process using limestone has strong effect on the desulfurization reaction under the oxy-fuel combustion condition. In this study, the conversion rates were measured and reaction rates were calculated in order to investigate the effects of the experimental variables such as temperature and the concentrations of $CO_2$, $O_2$, $SO_2$, on the $CaSO_4$ decomposition reaction using DTF (Drop Tube Furnace) in the desulfurization reaction. The conversion rate and the reaction rate of $CaSO_4$ decomposition reaction were increased with reaction temperature. $CO_2$ concentration has little effect on $CaSO_4$ decomposition reaction in the presence of $O_2$. Under the same experimental conditions, the decomposition rate of $CaSO_4$ was enhanced with the decreasing the $O_2$ concentration, but vice versa with the increasing of $SO_2$ concentration.

• Journal of the Korean Institute of Gas
• /
• v.23 no.1
• /
• pp.27-35
• /
• 2019

In order to solve the global warming and reduce greenhouse gas emissions, $CO_2$ capture technology was developed by applying oxy-fuel combustion. But there has been such a problem that its economic efficiency is low due to the high price of oxygen gases. ASU is known to be most suitable method to produce large quantity of oxygen, to reduce the oxygen production cost, the efficiency of ASU need to be improved. To improve the efficiency of ASU, exergy analysis can be used. The exergy analysis provides the information of used energy in the process, the location and size of exergy destruction. In this study, the exergy analysis was used for process developing and optimization of large scale ASU. The process simulation of ASU was conducted, the results were used to calculate the exergy. As a result, to reduce the exergy loss in the cold box of ASU, a lower operating pressure process was suggested. It was confirmed the importance of heat leak and heat loss reduction of cold box. Also, the unit process of ASU which requires thermal integration was confirmed.

• Proceedings of the Korea Air Pollution Research Association Conference
• /
• 2010.04a
• /
• pp.369-370
• /
• 2010