• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.165-166
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• 2014

The application of particle reaction model in the packed bed process modeling is discussed for iron ore pellet induration process. Combustion of coke breeze in the pellet is estimated by using shrinking unreacted-core model and grain model in which the progress of chemical reaction is described in different concepts. Under the identical inlet gas and solid conditions, the calculation using shrinking core model showed deviated results in terms of temperature profile and conversion fraction, which may imply the significance of selecting proper particle reaction model in consideration of particle characteristics and process operation conditions.

• Journal of the Society of Naval Architects of Korea
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• v.61 no.1
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• pp.51-60
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• 2024

Hi Air Korea and Hanwha ocean are currently developing an Onboard Carbon dioxide Capture System (OCCS) to absorb CO₂ emitted from ship's engine using a sodium hydroxide(NaOH) solution, and converting the resulting salt into a solid form through a chemical reaction with calcium oxide (CaO). The system process involves the following steps; 1)The reaction of CO₂ gas absorption in water, 2)The reaction between carbonic acid (H₂CO₃) and NaOH solution to produce carbonate or bicarbonate, and 3)The reaction between carbonate or bicarbonate and CaO to form calcium carbonate (CaCO₃). And ultimately, the solid material, CaCO₃, is separated and discharged using a separator. The OCCS has been installed on an ship and the test results have confirmed significant reduction effects of CO₂ in the ship's exhaust gas. A portion of the exhaust gas emitted from the engine was transferred to the OCCS using a blower. The flow rate of the transferred gas ranged from 800 to 1384 m³/hr, and the CO₂ concentration in the exhaust gas was 5.1 vol% for VLSFO, 3.7 vol% for LNG and a 12 wt% NaOH solution was used. The results showed a CO₂ capture efficiency of approximately 42.5 to 64.1 vol% and the CO₂ capture rate approximately 48.4 to 52.2kg/hr. Additionally, to assess the impact of the discharged CaCO₃on the marine ecosystem, we conducted "marine ecotoxicity test" and performed Computational Fluid Dynamics (CFD) analysis to evaluate the dispersion and dilution of the discharged effluent.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.821-825
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• 2014

Steam gasification of sawdust char was performed in a thermobalance reactor at high temperature. Gasification temperature was changed from $850^{\circ}C$ to $1400^{\circ}C$ and steam partial pressure was 0.3, 0.5 and 0.7 atm. Three models of gas-solid reaction were applied to the reaction kinetics analysis and modified volumetric model was an appropriate model. Reaction control regime and diffusion control regime were distinct depending on the temperature. Apparent activation energy and pre-exponential factors for both of the regimes were evaluated and the effects of steam partial pressure were examined. $H_2$ concentration in the produced gas was two times higher than that of CO due to the gasification accompanying by the water gas shift reaction.

• Bulletin of the Korean Chemical Society
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• v.30 no.2
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• pp.459-463
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• 2009

Furoxanaldehydes possessing phenyl or alkenyl groups at the 3- or 4-position of the furoxan ring were designed for alkyne formation on a solid surface. Furoxans 2 and 3 were prepared from the corresponding alkenes 2a and 3a by the reaction with NaN$O_2$ in acetic acid. Furoxan 4, in which the furoxan ring is conjugated with a double bond, was prepared from bis(bromomethyl)benzene 4a in 5 steps using the Wittig reaction of aldehyde 1 as the key step. The electron beam-mediated fragmentation of furoxanaldehydes 1-4 in a mass spectrometer was exploited by focusing on alkyne formation on the solid surface. The fragmentation of furoxan 3 possessing diaryl groups afforded diarylacetylene at high efficiency, suggesting that the aryl group conjugated with the furoxan ring could facilitate alkyne formation with the evolution of NO.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.4
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• pp.259-264
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• 2011

Gas hydrate is formed by physical binding between water molecule and gas such as methane, ethane, propane, or carbon dioxide, etc., which is captured in the cavities of water molecule under the specific temperature and pressure. $1\;m^3$ hydrate of pure methane can be decomposed to the methane gas of $172\;m^3$ and water of $0.8\;m^3$ at standard condition. If this characteristic of hydrate is reversely utilized, natural gas is fixed into water in the form of hydrate solid. Therefore, the hydrate is considered to be a great way to transport and store of natural gas in large quantity. Especially the transportation cost is known to be 18~25% less than the liquefied transportation. However, when methane gas hydrate is artificially formed, its reaction time may be too long and the gas consumption in water becomes relatively low, because the reaction rate between water and gas is low. Therefore, for the practical purpose in the application, the present investigation focuses on the rapid production of hydrates and the increment of the amount of captured gas by adding zeolite into pure water. The results show that when the zeolite of 0.01 wt% was added to distilled water, the amount of captured gas during the formation of methane hydrate was about 4.5 times higher than that in distilled water, and the methane hydrate formation time decreased at the same subcooling temperature.

• Bulletin of the Korean Chemical Society
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• v.34 no.12
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• pp.3767-3770
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• 2013

Potassium methylselenite ($KSeO_2(OCH_3)$) was reduced to elemental selenium, Se(0), and then doped onto montmorillonite K 10 (MK10) clay to examine the interaction between elemental mercury (Hg(0)) vapor and Se(0) in an effort to understand the possible heterogeneous reaction of Hg(0) vapor and Se(0) solid. The clay was used as a cost-effective support material for uniform dispersion of Se(0). The Se(0)-doped MK10 showed an excellent reaction performance with Hg(0) under an inert nitrogen gas at 70 and $140^{\circ}C$ in our lab-scale fixed-bed system. However, the precursor, $KSeO_2(OCH_3)$-doped MK10 showed a negligible reaction performance with Hg(0), suggesting that the oxidation state of selenium plays a key role in the reaction of Hg(0) vapor and selenium compounds.

• Korean Journal of Materials Research
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• v.22 no.11
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• pp.575-580
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• 2012

The purpose of this study is to investigate the crystalline structure and optical properties of (GaZn)(NO) powders prepared by solid-state reaction between GaOOH and ZnO mixture under $NH_3$ gas flow. While ammoniation of the GaOOH and ZnO mixture successfully produces the single phase of (GaZn)(NO) solid solution within a GaOOH rich composition of under 50 mol% of ZnO content, this process also produces a powder with coexisting (GaZn)(NO) and ZnO in a ZnO rich composition over 50 mol%. The GaOOH in the starting material was phase-transformed to ${\alpha}$-, ${\beta}-Ga_2O_3$ in the $NH_3$ environment; it was then reacted with ZnO to produce $ZnGa_2O_4$. Finally, the exchange reaction between nitrogen and oxygen atoms at the $ZnGa_2O_4$ powder surface forms a (GaZn)(NO) solid solution. Photoluminescence spectra from the (GaZn)(NO) solid solution consisted of oxygen-related red-emission bands and yellow-, green- and blue-emission bands from the Zn acceptor energy levels in the energy bandgap of the (GaZn)(NO) solid solutions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.8
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• pp.1022-1030
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• 1999

A numerical study was carried out to analyze the effect of flow distribution of stirred part and plug flow part on combustion efficiency at the coal gasification process in an entrained bed coal reactor. The model of computation was based on gas phase eulerian balance equations of mass and momentum. The solid phase was described by lagrangian equations of motion. The $k-{\varepsilon}$ model was used to calculate the turbulence flow and eddy dissipation model was used to describe the gas phase reaction rate. The radiation was solved using a Monte-Carlo method. One-step parallel two reaction model was employed for the devolatilization process of a high volatile bituminous Kideco coal. The computations agreed well with the experiments, but the flame front was closer to the burner than the measured one. The flow distribution of a stirred part and a plug flow part in a reactor was a function of the magnitude of recirculation zone resulted from the swirl. The combustion efficiency was enhanced with decreasing stirred part and the maximum value was found around S=1.2, having the minimum stirred part. The combustion efficiency resulted from not only the flow distribution but also the particle residence time through the hot reaction zone of the stirred part, in particular for the weak swirl without IRZ(internal recirculation zone) and the long lifted flame.

• Proceedings of the Korean Environmental Health Society Conference
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• 2003.06a
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• pp.152-156
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• 2003

Air pollution problems due to the emission of pollutants from the various industrial facilities become serious issues and lots of air pollution control processes have been developed. To remove the SO$_2$ and NOx emitted from the solid waste incinerator and coal fired power plants, we studied the Ca-based sorbent which was prepared by waste clam and limestone. The objectives of this study were to develop a clam-based sorbent for removal of SO$_2$ and NOx, and to investigate the physicochemical properties of the waste clam sorbent. In order to determine acid gas removal capacity of sorbent, the batch study on SO$_2$ and NOx removal was performed with the Ca-based sorbent in the fixed bed reactor. Results of the research revealed that clam-based sorbent can be used as the iron-manufacturing industry and chemical adsorbents for the removal of acid gases because the lime content of the waste calm was more than 53.92%. From physicochemical analysis and gas reaction experiments, it could be concluded that clam is good sorbent for the removal of SO$_2$ and NOx in waste incinerator and flue gas desulfurization processes.

• Journal of the Korean Solar Energy Society
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• v.30 no.5
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• pp.11-16
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• 2010

Methane hydrate is crystalline ice-like compounds which formed methane gas enters within water molecules composed cavity and each other from physically-bond at specially temperature and pressure condition. $1m^3$ of methane hydrate can be decomposed into the maximum of $216m^3$ of methane gas under standard condition. If these characteristics of hydrate are utilized in the opposite sense, natural gas can be fixed into water in the form of a hydrate solid. Therefore the use of hydrate is considered to be a great way to transport and store natural gas in large quantity. However, when methane hydrate is formed artificially, the amount of gas that is consumed is relatively low, due to the slow reaction rate between water and methane gas. Therefore for practical purposes in the application, the present investigation focuses on increasing the amount of gas consumed by adding chemically oxidized OMWCNTs to pure water. The results show that when 0.003 wt% of oxidation multi-walled carbon nanotubes was added to pure water, the amount of gas consumed was almost four times more than that of pure water indicating its effect in hydrate formation and the hydrate formation time decreased at alow subcooling temperature.