• Transactions of the Korean hydrogen and new energy society
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• v.23 no.5
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• pp.559-571
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• 2012

Dimethyl ether (DME) is a new clean fuel as an environmentally-benign energy resource. DME can be manufactured from various energy sources including natural gas, coal, and biomass. In addition to its environmentally friendly properties, DME has similar characteristics to those of LPG. The aim of this article is to represent the development of new DME process with KOGAS's own technologies. KOGAS has investigated and developed new innovative DME synthesis process from synthesis gas in gaseous phase fixed bed reactor. DME has been traditionally produced by the dehydration of methanol which is produced from syngas, a product of natural gas reforming. This traditional process is thus called the two-step method of preparing DME. However, DME can also be manufactured directly from syngas (single-step). The single-step method needs only one reactor for the synthesis of DME, instead of two for the two-step process. It can also alleviate the thermodynamic limitations associated with the synthesis of methanol, by converting the produced methanol into DME, thereby potentially enhancing the overall conversion of syngas into DME. KOGAS had launched the 10 ton/day DME demonstration plant project in 2004 at Incheon KOGAS LNG terminal. In the mid of 2008, KOGAS had finished the construction of this plant and has successively finished the demonstration plant operation. And since 2008, we have established the basic design of commercial plant which can produce 3,000 ton/day DME.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.02a
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• pp.383-383
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• 2010

Gas-phase hydrogen atoms create a variety of chemical and physical phenomena on Si surfaces: adsorption, abstraction of pre-adsorbed H, Si etching, Si amorphization, and penetration into the bulk lattice. Thermal desorption/evolution analyses exhibited three distinct peaks, including one from the crystalline bulk. It was previously found that thermal-energy gaseous H(g) atoms penetrate into the Si(100) crystalline bulk within a narrow substrate temperature window(centered at ~460K) and remain trapped in the bulk lattice before evolving out at a temperature as high as ~900K. Developing and sustaining atomic-scale surface roughness, by H-induced silicon etching, is a prerequisite for H absorption and determines the $T_s$ windows. Issues on the H(g) absorption to be further clarified are: (1) the role of the detailed atomic surface structure, together with other experimental conditions, (2) the particular physical lattice sites occupied by, and (3) the chemical nature of, absorbed H(g) atoms. This work has investigated and compared the thermal H(g) atom absorptivity of Si(100), Si(111) and Si(110) samples in detail by using the temperature programmed desorption mass spectrometry (TPD-MS). Due to the differences in the atomic structures of, and in the facility of creating atom-scale etch pits on, Si(100), (100) and (110) surfaces, the H-absorption efficiency was found to be larger in the order of Si(100) > Si(111) > Si(110) with a relative ratio of 1 : 0.22 : 0.045. This intriguing result was interpreted in terms of the atomic-scale surface roughening and kinetic competition among H(g) adsorption, H(a)-by-H(g) abstraction, $SiH_3(a)$-by-H(g) etching, and H(g) penetraion into the crystalline silicon bulk.

• Resources Recycling
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• v.26 no.5
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• pp.61-66
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• 2017

Vanadium Dioxide has been investigated for use as a "spectrally-selective" window coating to block infrared transmission and reduce the loss of building interior heat through windows. The preparation of thermochromic $VO_2$ powder by the reductive reaction with hydrogen was studied. The reductive reaction method has many advantages of easy and mass production of $VO_2$ powder according to controlled reaction without semi-conductor equipments like sputter and beam evaporator. The reaction temperature, time, concentration of reductive gas, post-annealing condition and W addition as dopant would affect the characterization of $VO_2$ powder and its thermochromism. Many applications for electrical device and energy-saving technologies is expected.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.1
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• pp.17-21
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• 1991

The study was performed to investigate the effects of gaseous emission of sulfur dioxide and hydrogen fluoride on the growth of rice plant under stressed field conditions. This study is specifically dealt with multiple effects of sulfur dioxide and hydrogen fluoride on various plant growth indicators such as leaf damage, weight of grain, panicles per hill, spikelets per panicle and percent fertility. It appears that there is a good correlation between ambient concentrations of sulfur oxides and sulfur contents found in leaves with an average correlation coefficient of 0.868 within a 1% significance level. A better multiple correlation was found between percent leaf damage and sulfur and fluorine contents found in leaf with a significance of 1% level. The correlation coefficient ranges from 0.807 to 0.978 with an average being 0.922. An evaluation of data observed has demonstrated that both panicles per hill and percent fertility are significantly affected by air pollutants. As expected, hydrogen fluorides have more effects than sulfur oxides. It is, however, interesting to note that spikelets per panicle has slightly been affected while no indication of effects on l000-grain weight has been observed. This may lead to a conclusion that a reduction in yield of rice under polluted field conditions may have more been caused by the diminution panicles per hill and percent fertility rather than by the diminution of spikelets per panicle and grain weight.

• Journal of Environmental Science International
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• v.21 no.7
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• pp.883-890
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• 2012

Emission characteristics of gaseous odor compounds emitted from the charcoal manufacturing process were investigated, and evaluated the odor removal efficiency of odor control devices. It was found that the measured odor dilution ratio of emission gases ranged from 10,000 to 44,814, which exceed largely the emission standard in the stack. Methylmercaptan, trimethylamine, hydrogen sulfide, acetaldehyde were turned out as major odor compounds of the charcoal manufacturing process. It was revealed that the odor removal ratio of odor control devices were very low due to the its improper maintenance and wrong design.

• Aerospace Engineering and Technology
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• v.7 no.2
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• pp.170-175
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• 2008

In this study, it was investigated that the characteristics of startup and compatibility using several type hot and cold gases. The characteristics of starting LRE by pyro starter was compared with that by a Helium spinner. The compatibility of pyro gas, a gaseous Helium, Hydrogen+Nitrogen mixture gas, and air was investigated by a simple 1D turbine analysis considered the properties of each gas and turbine efficiency. Most of them were compatible to start up the LRE however air was properly used only for low power mode of turbine.

• 한국신재생에너지학회:학술대회논문집
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• 2008.05a
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• pp.247-250
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• 2008

Biomass gasification is a promising technology for producing a fuel gas which is useful for power generation systems. In biomass gasification processes, tar formation often causes some problems such as pipeline plugging. Thus, proper tar treatment is necessary. So far, nickel (Ni)-based catalysts have been intensively studied for the catalytic tar removal. However, the deactivation of Ni-based catalysts takes place because of coke deposition and sintering of Ni metal particles. To overcome these problems, we have been using ruthenium (Ru)-based catalyst for tar removal. It is reported by Okada et al., that a Ru/$Al_2O_3$ catalyst is very effective for preventing the carbon deposition during the steam reforming of hydrocarbons. Also, this catalyst is more active than the Ni-based catalyst at a low steam to carbon ratio (S/C). Benzene was used for the tar model compound because it is the main constituent of biomass tar and also because it represents a stable aromatic structure apparent in tar formed in biomass gasification processes. The steam reforming process transforms hydrocarbons into gaseous mixtures constituted of carbon dioxide ($CO_2$), carbon monoxide (CO), methane ($CH_4$) and hydrogen ($H_2$).

• Journal of the Korean Society of Visualization
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• v.3 no.2
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• pp.51-56
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• 2005

Acoustic excitations were imposed to coaxial air jet of non-premixed jet flame with hydrogen gaseous injected axially in the center of the flow. The frequencies of excitation were three dominant resonant frequencies at 1L, 2L, 3L. modes including specially 514 Hz (2L-mode) which was estimated theoretically as longitudinal mode of combustor characteristics. The mixing enhancement by acoustic forcing has been investigated quantitatively using PLIF and PIV. The effect of acoustic excitation on combustion process was significant to enhance mixing rate that coincides with specific resonant frequencies. And the behavior of vortex-interaction on flame structure was a good evidence to investigate the phenomenon of shear/mixing layer of fuel-air jet structure. The results obtained in this study concludes that generated streamwise vortex by acoustic excitation has a potential to enhance the mixing rate and abating NOx emissions.

• Environmental Engineering Research
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• v.12 no.4
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• pp.157-175
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• 2007

The membrane biofilm reactor (MBfR) creates a natural partnership of a membrane and biofilm, because a gas-transfer membrane delivers a gaseous substrate to the biofilm that grows on the membrane's outer wall. $O_2$-based MBfRs (called membrane aerated biofilm reactors, or MABRs) have existed for much longer than $H_2$-based MBfRs, but the $O_2$-based MBfR is a versatile platform for reducing oxidized contaminants in many water-treatment settings: drinking water, ground water, wastewater, and agricultural drainage. Extensive bench-scale experimentation has proven that the $H_2$-based MBfR can reduce many oxidized contaminant to harmless or easily removed forms: e.g., ${NO_3}^-$ to $N_2$, ${ClO_4}^-$ to $H_2O$ and $Cl^-$, ${SeO_4}^{2-}$ to $Se^0$, and trichloroethene (TCE) to ethene and $Cl^-$. The MBfR has been tested at the pilot scale for ${NO_3}^-$ and ${ClO_4}^-$ and is now entering field-testing for many of the oxidized contaminants alone or in mixtures. For the MBfR to attain its full promise, several issues must be addressed by bench and field research: understanding interactions with mixtures of oxidized contaminants, treating waters with a high TDS concentration, developing modules that can be used in situ to augment pre-denitrification of wastewater, and keeping the capital costs low.

• 한국연소학회:학술대회논문집
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• 2004.06a
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• pp.227-234
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• 2004

For gaseous fuel combustion with inherent $CO_2$ capture and low NOx emission, chemical-looping combustion(CLC) may yield great advantages of savings of energy to $CO_2$ separation and suppressing the effect on environment. In chemical-looping combustor, fuel is oxidized by metal oxide medium (oxygen carrier particle) 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. The purpose of this study is to demonstrate inherent $CO_2$ separation and no NOx emission and to confirm high $CO_2$ selectivity, no side reaction (i.e., carbon deposition, hydrogen generation) by continuous reduction and oxidation experiment in a 50kWtb chemical-looping combustor. NiO/bentonite particle was used as a bed material and $CH_4$ and air were used as reacting gases for reduction and oxidation respectively.