• Journal of Energy Engineering
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• v.2 no.3
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• pp.285-292
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• 1993

A cylindrical-shape, horizontal furnace was used to investigate the effect of particle size on the pulverized coal combustion behavior. Three differently-sized fractions (5, 30, and 44 microns in average diameter) of high-volatile bituminous coal, were burned in the test furnace. Ignition characteristics of pulverized coal flame were determined through the amount of methane in the carrier gas for the self-sustaining flame. Easiest ignition occurred with the immediately-sized coal particles. Ignition of coal jet flame appeared to occur through a gas-phase homogeneous process for particles larger than 30 microns. Below this limiting size, heterogeneous process probably dominated ignition of coal flame. Oxygen concentration of combustion air was varied up to 50%, to determine the oxygen-enrichment effect on the coal ignition behavior. Oxygen enrichment of primary air assisted ignition behavior of pulverized coal flame. However, enrichment of secondary air didn't produce any effect on the ignition behavior.

• Journal of the Korean Society of Combustion
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• v.7 no.1
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• pp.31-36
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• 2002

Vortical structures are investigated numerically for both cold and combusting flows from a two-dimensional bluff-body burner in the transitional flow regime from steady to unsteady state. The Reynolds number of the central fuel flow is varied from 10 to 230 at a fixed air Reynolds number of 400. The flame sheet model of infinite chemical reaction and unit Lewis number are assumed in the simulation. The temperature dependence of the viscosity and diffusivity of the gas mixture is also considered. The vortex shedding is observed depending on the fuel flow. For cold flow, four different types of vortical structure are identified. However, for combusting flow of methane-air system the vortical structures change significantly due to a large amount of heat release during the combustion process, in contract to cold flow.

• Journal of environmental and Sanitary engineering
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• v.15 no.4
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• pp.35-43
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• 2000

Aqueous solutions of chlorobenzene and chlorinated phenols were exposed to 200kHz ultrasound with a power of $6.0W/\textrm{cm}^2$ per unit volume on sonochemical reactor under ambient temperature and pressure conditions. The concentration of chlorobenzene and chlorinated phenols decreased with ultrasound, indicating first-order kinetics. Degradation rate constants are calculated from the slope of plots. The order of the rate constants is as follows : 2-chlorphenol(2-CP)$\leq$ 4-chlorophenol(4-CP)<3-chlorophenol(3-CP)$5.63~9.96({\times}10^{-2})min^{-1}$ under argon. The degradation was suppressed by the addition of t-BuOH and the suppressed yield was agreed with their reactivity for hydroxy radical. The main products of these systems were formic acid, acetic acid, small amount of methane and inorganic carbon forms as carbon dioxide, carbon monoxide in sonolysis of chlorinated phenols, and also these results agreed with change of TOC.

• Preventive Nutrition and Food Science
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• v.9 no.2
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• pp.187-189
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• 2004

To isolate a mutant strain which overproduces tryptophan, mutants of Candida rugosa were screened after EMS (ethyl methane sulfonate) mutagenesis. Fluorotryptophan, a tryptophan analogue, was used for selection of a tryptophan-overproducing mutant after mutagenesis. Among 50 mutants, several candidates were selected based on intracellular tryptophan content. Amino acid analysis results showed that C3 was the best strain because it had the highest amount of tryptophan among the mutants.

• Proceedings of the KSME Conference
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• 2003.11a
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• pp.332-337
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• 2003

Oxygen-enriched non-premixed flame characteristics was investigated numerically with variation of dilution methods, which are Flue gas recirculation(FGR) and fuel injection recirculation(FIR). In order to compare flamelets in various oxygen-enrichment conditions reasonably, the adiabatic flame temperature and Damkoller number was held fixed by modulating amount of diluents to fuel and oxidizer stream and by varying global strain rate of flame respectively. Also modified GRI 3.0 reaction mechanism was utilized, which was able to predict oxygen-enriched methane flame correctly. Fundamental flame characteristics such as structure, heat release rate and extinction with FGR and FIR were compared in various oxygen enrichment conditions.

• Biotechnology and Bioprocess Engineering:BBE
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• v.8 no.5
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• pp.309-312
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• 2003

The transformation capacity (T$\_$c/) of Methylosinus trichosporium OB3b in the degradation of ethylene chlorides was determined by measuring the decrease of soluble methane monooxygenase (sMMO) activity of resting cells in batch experiments. All measurements of sMMO activity were taken in the presence of 20 mM formate to avoid the deficiency of reducing power, and within 2 hrs to avoid the effect of natural inactivation from instability of the resting cells. The constant T$\_$c/ values of 0.58 ${\pm}$ 0.132 and 0.80 ${\pm}$ 0.17 ${\mu}$mol/mg cell were obtained for trichloroethylene (TCE) and 1,2-dichloroethylene (cis and trans-1,2-DCE), respectively, regardless of their concentrations. The transformation capacity measured by this method can be used to predict the amount of cells that should be stimulated in in-situ bioremediation.

• Journal of the Korea Organic Resources Recycling Association
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• v.25 no.3
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• pp.55-62
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• 2017

In this study, we investigated the effect of seaweed (SW) addition on the anaerobic digestion of food waste (FW). Anaerobic batch experiments were carried out at various substrate concentrations (2.5 to 10.0 g VS/L) and mixing ratios (FW:SW=100:0, 75:25, 50:50, 25:75 and 0:100 on VS basis) of FW and SW. The methane yield of FW alone was 394, 377, 276, $49mL\;CH_4/g\;VS_{added}$ at each substrate concentration (2.5 to 10.0 g VS/L). In cases of co-digestion, methane yield decreased (up to 15 %) with increasing mixing ratio of SW at low substrate concentration (2.5 to 5.0 g VS/L), while it increased (up to 240 %) at high substrate concentration (7.5 to 10.0 g VS/L). The synergistic effect was calculated based on the amount of methane generated from the single-feedstock digestion of FW and SW. The synergistic effect was not found at 2.5 and 5.0 g VS/L. However, the synergistic effect increased (up to 25% = synergistic increment/total methane production at 10.0 g VS/L, FW:SW=50:50) with increasing the ratio of seaweed at 7.5 and 10.0 g VS/L. At 10.0 g VS/L of FW alone, the accumulated amount of organic acids was 7,426 mg COD/L, which was decreased to 2,346 mg COD/L by seaweed (FW:SW=50:50) addition. The reason for the synergistic effect was to control the production rate of the organic acids by adding SW that has a relatively lower biodegradability compared to FW.

• Korean Chemical Engineering Research
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• v.50 no.5
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• pp.802-807
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• 2012

The autothermal reforming of methane to syngas has been carried out in a reactor charged with both a Ni (15 wt%)-Ru (1 wt%)/$Al_2O_3$-MgO metallic monolith catalyst and an electrically-heated convertor (EHC). The standalone type reactor has a start-up time of less than 2 min with the reactant gas of $700^{\circ}C$ fed to the autothermal reactor. The $O_2/CH_4$ and $H_2O/CH_4$ ratio governed the methane conversion and temperature profile of reactor. The reactor temperature increased as the reaction shifted from endothermic to exothermic reaction with decreasing $H_2O/CH_4$ ratio. Also the amount of $CO_2$ in the products increases with increasing $H_2O/CH_4$ ratio due to water gas shift reaction. The 97% of $CH_4$ conversion was obtained and the reactor temperature was maintained $600^{\circ}C$ at the condition of $GHSV=10,000\;h^{-1}$ and feed ratio ($H_2O/CH_4=0.6$ and $O_2/CH_4=0.5$). In this condition, the maximum flow rate of the syngas generated from the reactor charged with 170 cc of the metallic monolith catalyst is $0.94\;Nm^3/h$.

• Journal of the Korea Organic Resources Recycling Association
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• v.8 no.3
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• pp.89-96
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• 2000

Waste oyster shell was used to study the applicability on anaerobic composting of garbage. Experiment was conducted with five anaerobic reactors. After garbage and compost for inoculation were mixed, waste oyster shell was added into mixed waste in mesophillic temperature for 60 days with 30%, 60% respectively. The amount of produced methane gas, gas composition, organic removal efficiency and pH were measured. Result showed that the amounts of produced gas were 0.62 l /g-VS in R-1, 0.63 l /g-VS in R-2, 0.16 l /g-VS in R-3, 0.75 l /g-VS in R-4, 0.21 l /g-VS in R-5 and the amounts of produced methane gas were 0.32 l /g-VS in R-1, 0.37 l /g-VS in R-2, 0.04 l /g-VS in R-3, 0.42 l /g-VS in R-4, 0.05 l /g-VS in R-5. Proportion of mathane gas which determines the efficiency of anaerobic composting was over 55%. pH were 6.0~8.0 in R-2 and R-4 which contained 30% of waste oyster shell and pH were increased over 8.5 in R-3 and R-5 which contained 60% of waste oyster shell. Since pH were so high and it had a negative effect on microbial growth, anaerobic reaction were not well operated in R-3 and R-5.

• Korean Journal of Environmental Agriculture
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• v.13 no.3
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• pp.311-320
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• 1994

This study was conducted to investigate the biochemical properties of isolated bacteria, low temperature tolerant methane-producing clostridia which were selected for using them as inoculum to anaerobic fermentation of agricultural and livestock wastes at low temperature. The results were; 1. Low temperature tolerant methane-producing clostridia were isolated from the samples which showed the high methanogenesis rate by enrichment culture at low temperature in cellulose medium. These clostridia, Clostridium botulinum SRC-64, Clostridium scatologens SRC-91 and Clostridium tyrobutyricum SRC-100, were isolated from swampy sediment at latitude $56.9^{\circ}N$, lake sediment IV at latitude $55.0^{\circ}N$, and tidal land soil II at latitude $37.0^{\circ}N$, respectively. The optimum growth temperature for these isolates was $37^{\circ}C$ and the minimum, around $10^{\circ}C$. They all had detectable amount of $F_{420}$, specific coenzyme of methanogens. 2. As anaerobic fermentation products of glucose SRC-64 produced $H_2$, acetic, isovaleric and caproic acid, SRC-91 produced $H_2$, propionic, butyric, valeric, and caproic acid, and SRC-100 produced only acetic and propionic acid. The isolates were produced $CH_4$ ranged from 2.6 to 8.68 n moles/ml for 2 days at $13^{\circ}C$.