• Fire Science and Engineering
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• v.22 no.3
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• pp.252-257
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• 2008

With the rapid exuberant growth of the forest, the number and size of forest fires and the costs of wildland fires have increased. The flame spread rate of forest fires is depending on the environmental variables like the wind velocity, moisture of grassland, etc. If we know the effects of the environmental variables on the fire growth, it is useful for wildland fiIre suppression. But analysis of the spread rate of wildland fire for these effects have not been established. In this study, the effects of wind velocity and height of grassland fuel have been investigated using the WFDS which is developed at NIST for prediction of the spread of wildland fires. The results showed that the relation between the height of the fuel and the spread rate of the head fires is, and the spread rates related to the wind velocity are predicted 17% less than the experimental results of Australia. When the wind velocity is over 7.5m/s, the concentration of pyrolyzed gas phase fuel is getting low due to fast movement of pyrolyzed gas, the flame spread rate becomes slow.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.409-416
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• 2010

The use of oxy-fuel combustion and flue gas recirculation (FGR) for $CO_2$ reduction has been studied by many researchers. This study focused on the characteristics of oxy-fuel combustion and the effects of $CO_2$ addition from the point of view of oxygen feeding ratio (OFR) and the position of $CO_2$ addition in order to reproduce an FGR system with a triple concentric multi-jet burner. Oxy-fuel combustion was stable at all OFRs at a fuel flow-rate of 15 lpm, which corresponds to an equivalence ratio of 0.93; however, the structure and length of the flame varied at different OFRs. When $CO_2$ was added in oxy-fuel combustion, various stability modes such as stable, transient, quasistable, unstable, and blow-out were observed. The temperature in the combustion chamber decreased upon $CO_2$ addition in all conditions, and the maximum reduction in temperature was below 1800 K. $CO_2$ concentration with respect to height varied with the volume percent of $CO_2$ at the nozzle tip.

• Korean Chemical Engineering Research
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• v.51 no.2
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• pp.163-170
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• 2013

Selective catalytic reduction of $NO_x$ by $NH_3$ ($NH_3$-SCR) over $V_2O_5/TiO_2$-based catalysts is recently reported to be an anthropogenic emitter of $N_2O$ that is a global warming gas with a global warming potential of 310. Therefore, this review will get a touch on significance of some parameters regarding $N_2O$ formation in the $deNO_xing$ reaction for fossil fuels-fired power plants applications. The $N_2O$ production in $NH_3$-SCR reaction with such catalysts occurs via side reactions between $NO_x$ and $NH_3$ in addition to $NH_3$ oxidation, and the extent of these undesired reactions depends strongly on the loadings of $V_2O_5$ as a primary active component and the promoter as a secondary one ($WO_3$ and $MoO_3$) in the SCR catalysts, the feed and operating variables such as reaction temperature, $NO_2/NO_x$ ratio, oxygen concentration, gas hourly space velocity, water content and thermal excursion, and the physical and chemical histories of the catalysts on site. Although all these parameters are associated with the $N_2O$ formation in $deNO_xing$ reaction, details of some of them have been discussed and a better way of suppressing the $N_2O$ production in commercial SCR plants has been proposed.

• Microbiology and Biotechnology Letters
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• v.44 no.2
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• pp.145-149
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• 2016

Thermal acid hydrolysis pretreatment of Kappaphycus alvarezii was carried out with 12% (w/v) seaweed slurry and 180 mM H₂SO₄ at 140°C for 5 min. Utility of the thermotolerant yeast Kluyveromyces marxianus KCTC7150 was evaluated with respect to cell growth and ethanol fermentation at 40°C was close to optimal for enzymatic hydrolysis. This could lead to the integration of both the saccharification and fermentation processes. The levels of ethanol production by simultaneous saccharification and fermentation (SSF) with non-adapted and adapted K. marxianus KCTC7150 were 9.1 g/l with an ethanol yield (Y_EtOH) of 0.24 and 10.2 g/l with an ethanol yield (Y_EtOH) of 0.27 at 156 h, respectively. The two-phase SSF process was employed in this study to improve the efficiency of ethanol fermentation. Adapted K. marxianus KCTC7150 using the two-phase SSF process produced 13.5 g/l with an ethanol yield (Y_EtOH) of 0.35 at 96 h. Development of the two-phase SSF process could enhance the overall ethanol fermentation yields of the seaweed K. alvarezii.

• Journal of Soil and Groundwater Environment
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• v.8 no.3
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• pp.37-44
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• 2003

Fuel oxygenates, such as Methyl tertiary Butyl Ether (MTBE) is additive in gasoline used to reduce air pollution. Gasoline components and fuel additives can leak: form underground storage tanks. MTBE is far more water soluble than gasoline hydrocarbons like BTEX then it travels at essentially the same velocity as groundwater. MTBE in drinking water causes taste and odor problems. Therefore, the purpose of the this study is to examine the ability of ground tire to sorb MTBE in water. The study consisted of running both batch and column tests to determine the sorption capacity, the required sorption equilibration time, and the flow through utilization efficiency of ground tire. The batch test result indicated that ground tire can attain equilibrium sorption capacities about 0.5 mg of MTBE. The result of column test indicate that ground tire has on the 36% utilization rate. Finally, it is clear that ground tire represented an attractive and relatively inexpensive sorption medium for a MTBE. Authors thought that to determine the economic costs of ground tire utilization, the cost to sorb a given mass of contaminant by ground tire will have to be compared to currently accepted sorption media. The cost comparison will also have to include regeneration and disposal cost.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.35 no.3
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• pp.309-319
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• 2011

We experimentally investigated lifted propane jet flames diluted with nitrogen to obtain flame-stability maps based on heat-loss-induced self-excitation. We found that heat-loss-induced self-excitations are caused by conductive heat loss from premixed flame branches to trailing diffusion flames as well as soot radiation. The conductive-heat-loss-induced self-excitation at frequencies less than 0.1 Hz is explained well by a suggested mechanism, whereas the oscillation of the soot region induces a self-excitation of lift-off height of the order of 0.1 Hz. The suggested mechanism is also verified from additive experiments in a room at constant temperature and humidity. The heat-loss-induced self-excitation is explained by the Strouhal numbers as a function of the relevant parameters.

• Applied Chemistry for Engineering
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• v.26 no.2
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• pp.224-228
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• 2015

The carbon precursor pitch from pyrolyzed fuel oil (PFO), by-product of Naphta cracking process (NCC), was prepared through heat and UV irradiation treatments with various concentrations of $AlCl_3$, which is a new pitch preparation method. The reformed pitches were characterized by measuring their elemental composition, chemical structure of components, molecular weight distribution, and softening point. The oxygen contents of reformed pitch increased as increasing $AlCl_3$ amounts on the other hand, the carbon and hydrogen contents were not nearly changed. UV irradiated reformed pitches were composed of more aromatic carbon compounds than that of using only heat-treatment without any UV irradiation. The addition of $AlCl_3$ catalyst was ineffective on the aromaticity of reformed pitches. The softening point of prepared pitches was in the range of $103.3{\sim}168.9^{\circ}C$. Also the yield of prepared pitch increased from 48% to 80% when 5 wt% of $AlCl_3$ was added during the heat and UV irradiation reforming. It is expected that the UV irradiation reforming method can be practical and helpful to produce high yields of pitches with diverse properties.

• Membrane Journal
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• v.17 no.3
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• pp.197-209
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• 2007

In this study, a multi-staged pilot-scale membrane plant was constructed and operated for the separation of $CO_2$ from LNG-fired boiler flue gas of 1,000 $Nm^3/day$. The target purity and recovery ratio of $CO_2$ required for the pilot plant were 99% and 90%, respectively. For this purpose, we previously developed the asymmetric polyethersulfone hollow fibers and evaluated the effects of operating pressure and feed concentration of $CO_2$ on separation performance[1,2]. The permeation data obtained were also analyzed in relation with the numerical simulation data using counter-current flow model[3,4]. Based on these results, we designed and prepared the demonstration plant consisting of dehumidification process and four-staged membrane process. The operation results using this plant were compared with the numerical simulation results on multi-staged membrane process. The experimental results matched well with the numerical simulation data. The concentration and the recovery ratio of $CO_2$ in the final stage permeate stream were ranged from $95{\sim}99%$ and $70{\sim}95%$, respectively, depending on the operating conditions. This study demonstrated the applicability of the membrane-based pilot plant for $CO_2$ recovery from flue gas.

• Journal of the Korean Institute of Gas
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• v.14 no.3
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• pp.41-45
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• 2010

The physical properties of DME(Dimethyl Ether) are very similar to LPG and well-mixed. As cetane number of DME is similar to diesel fuel that can replace diesel fuel and alternative energy. DME is a clean energy source that can be manufactured from various raw materials such as natural gas, CBM(Coal Bed Methane) and biomass. DME has no carbon-carbon bond in its molecular structure and its combustion essentially generates no soot as well as no SOx. The development of DME process in KOGAS have 4 section. First, syngas section can be manufactured various syngas ratio. This completes the tri-reforming process for the synthesis gas ratio of approximately 4.0 to 1.0 range can be adjusted. Second, $CO_2$ is removed from the $CO_2$ removal section of about 92~99%, so the maximum concentration of $CO_2$ entering the DME synthesis reactor should not exceed 8%. Third, in the DME synthesis section, if the temperature of DME reactor increases, the activity of DME catalyst increased. but for the long-term activity is desirable to maintain the proper temperature. Finally, the purity of DME in the DME purification section is over 99.6%.

• Journal of Soil and Groundwater Environment
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• v.8 no.4
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• pp.64-67
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• 2003

In order to identify the origin and nature of the spilled oil in the potential source, we analyzed the concentrations of specific fuel constituents in fuel standard and environmental samples. The ratios of pristane/phytane are virtually unaltered because these compounds have the same bolatility in environmental samples. These were useful to identify the source of the fuel oil and to assess the effect of microbial degradation and weathering of the fuel oil. We analyzed the ratios of pristane/phytane in neat white kerosene, boiler kerosene, JP-8 and diesel products from L and S gas station. The ratios of pristane/phytane in L-white kerosene and JP-8 was 3.10 $\pm$0.03 and 1.77 $\pm$ 0.01, respectively. Otherwise, the ratios of pristane/phytane in water phase after distribution of fuel oil and water was 2.97 $\pm$0.02 in case of white kerosene and 1.65 $\pm$ 0.02 in case of JP-8. It is apparent from the results that the ratios of pristane/phytane were as product-specific, especially between kerosene and JP-8, and therefore, can also be used for fuel type identification in free products and groundwater samples which were collected in monitoring wells.