• Journal of Korean Society of Environmental Engineers
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• v.31 no.10
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• pp.883-892
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• 2009

We evaluated the degradation properties of various alkanolamine absorbents (MEA, AMP, DEA, and MDEA) having different chemical structures for $CO_2$ capture. The degradation of $CO_2$ absorbent in general was known to be caused by oxygen which is in flue gas and by heat source, respectively. To analyze the effect of $CO_2$ and $O_2$ on degree of degradation, we conducted a variety of experiments at $30^{\circ}C$ and $60^{\circ}C$ (oxidative degradation) and $130^{\circ}C$ and $150^{\circ}C$ (thermal degradation), respectively. DEA showed the worst property for oxidative degradation in the presence of oxygen among the alkanolamine absorbents. In the case of thermal degradation, the degradation of absorbent was occurred for most of absorbents at $150^{\circ}C$. Among these absorbents, MEA and DEA gave the worst results. As a result, AMP which is a primary amine and having a steric hindrance showed the best result through the degradation test. But, the degradation of absorbent proceeded easily in the case of DEA which is a secondary amine and having 2 OH groups in terminal position. Consequently, we have evaluated the degree of degradation of various absorbents having different chemical structures to give the basic data for the development of alkanolamine absorbent.

• Particle and aerosol research
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• v.13 no.4
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• pp.151-158
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• 2017

Electrostatic precipitator is widely used to remove particulate matters in indoor air and industrial flue gas due to low pressure drop and high collection efficiency. However, it has a low collection efficiency for the submicrometer sized particles. Electrospraying is a potential method to increase the particle charging efficiency, which results in increased collection efficiency. Although particle charging efficiency is highly dependent upon droplet size, the effective measuring method of the droplets is still uncertain. Tap water was electrosprayed in this study, and the images of electrosprayed droplets were taken with a high speed camera coupled with several visualization methods in order to measure the droplets size. The droplet size distribution was determined by an image processing with an image-J program. As a result, a droplet measured by a laser visualization, had a half size of that by a Xenon light visualization. In addition, the experimentally measured droplet sizes were a good agreement with the predicted values suggested by $Fern{\acute{a}}ndez$ de la Mora and Loscertales(1994).

• Korean Chemical Engineering Research
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• v.46 no.4
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• pp.806-812
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• 2008

The ammonia decomposition reaction has been of increasing interest as a means of treating ammonia in flue gas in the presence of precious metal catalyst. Various catalysts, $Pt-Rh/Al_2O_3$, $Pt-Rh/TiO_2$, $Pt-Rh/ZrO_2$, $Pt-Pd/Al_2O_3$, $Pd-Rh/Al_2O_3$, $Pd-Rh/TiO_2$, $Pd-Rh/ZrO_2$, $Pt-Pd-Rh/Al_2O_3$, $Pd/Ga-Al_2O_3$, $Rh/Ga-Al_2O_3$, and Ru/Ga-$Al_2O_3$, were synthesized by using excess wet impregnation method. Using a homemade 1/4" reactor at $10,000{\sim}50,000hr^{-1}$ of space velocity in the presence of precious metal catalyst ammonia decomposition reactions were carried out to investigate the catalyst activity. The inlet ammonia concentration was maintained at 2,000 ppm, with an air balance. Both $T_{50}$ and $T_{90}$, defined as the temperatures where 50% and 90% of ammonia, respectively, are converted, decreased significantly when alumina-supported catalysts were applied. In terms of catalytic performance on the ammonia conversion in the presence of hydrogen sulfide, $Pt-Rh/Al_2O_3$ catalyst showed no effect on the poisoning caused by hydrogen sulfide. These results indicate that platinum-rhodium bimetallic catalyst is a useful catalyst for ammonia decomposition.

• Clean Technology
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• v.24 no.1
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• pp.27-34
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• 2018

Catalytic filter has many advantages for the industrial application owing to its bi-functional ability to treat nitrogen oxides and particulate simultaneously. The technical feasibility of using the catalytic filter in the flue gas treatment process will be more promoted if the high porous ceramic sheet filter is utilized. However, it is not easy to prepare the effective catalytic filter using sheet filter as it has less room for catalyst support due to its thin layer. In this study, catalytic filter using a domestic ceramic sheet filter element has been prepared and conducted the experimental evaluation for NO reduction performance. The current sheet filter element shows the low catalytic activity less than 92% conversion for NO concentration 700 ppm at the face velocity $0.02m\;s^{-1}$. This unexpected low catalytic activity seems to be caused by the present of extraordinary large pores from the lack of uniformity in the pore size distribution of the sheet filter. The large pore size of the sheet filter is reduced by composing the smaller powder as its raw material, which presents improvement in NO conversion more than 96%. More improvement is observed showing 98% NO conversion which is applicable to a commercial plant when the catalyst coating layer is expanded by adding the large $TiO_2$ particles during the catalyst preparation. Both of above two methods is regarded as that the broad gates of the larger pores in the coating layer are effectively filled with the proper catalyst. So these results encourage the utilization of sheet filter as a good catalytic filter material with its potential merit of high permeability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5376-5383
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• 2011

The objective of this study is the development of carbon-recycle technology, that converts carbon dioxide captured from flue gas to carbon monoxide or carbon for reuse in industrial fields. It is difficult to decompose $CO_2$ because $CO_2$ is very stable molecule. And then metal oxide was used as an activation agent or catalyst for the decomposition of $CO_2$ at low temperature. Metal oxides, which converts $CO_2$ to CO or C, were prepared using Ni-ferrite by solid state method and hydrothermal synthesis in this study. TPR/TPO and TGA were used as an analysis method to analyze the decomposition characteristics of $CO_2$. As the results, the reduction area of $H_2$ was high value at 15 wt% of NiO and the decomposition area of $CO_2$ was superior capacity at 5 wt% of NiO. However, TGA data showed contrary results that reduction area of $H_2$ was 28.47wt% and oxidation area by $CO_2$ was 26.95wt% at 2.5 wt% of NiO, one of the Ni-ferrite powders synthesized using solid state method. $CO_2$ decomposition efficiency was 94.66% and it is excellent results in comparison with previous studies.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.11
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• pp.5357-5364
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• 2011

The objective of this study is development of carbon recycle technology which convert carbon dioxide captured from flue gas to carbon monoxide or carbon and reuse in industrial fields. Since carbon dioxide is very stable and difficult to decompose, metal oxide was used as activation agent for the decomposition of carbon dioxide at low temperature. Metal oxides which convert $CO_2$ to CO or carbon were prepared using Ba-ferrite by solid and hydrothermal synthesis. TPR/TPO and TGA were used in this study. The results of TPR by H2 and TPO by $CO_2$ showed that Ba-ferrite powders synthesized by hydrothermal method were better than those by solid method. TGA showed contrary results that reduction of Ba-ferrite powders synthesized using solid method by $H_2$ was 21.96 wt%, oxidation by $CO_2$ was 21.24 wt% and 96.72 wt% of $CO_2$ decomposition efficiency showing excellent oxidation-reduction characteristics at $500^{\circ}C$.

• Journal of Radiation Industry
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• v.10 no.4
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• pp.173-179
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• 2016

Coals and coal ashes, raw materials and by-products, in coal-fired power plants contain naturally occurring radioactive materials (NORM). They may give rise to internal exposure to workers due to inhalation of airborne particulates containing radioactive materials. It is necessary to characterize radioactivity concentrations of the materials for assessment of radiation dose to the workers. The objective of the present study was to analyze radioactivity concentrations of coals and by-products at four coal-fired plants in Korea. High purity germanium detector was employed for analysis of uranium series, thorium series, and potassium 40 in the materials. Radioactivity concentrations of $^{226}Ra$, $^{228}Ra$, and $^{40}K$ were $2{\sim}53Bq\;kg^{-1}$, $3{\sim}64Bq\;kg^{-1}$, and $14{\sim}431Bq\;kg^{-1}$ respectively in coal samples. For coal ashes, the radioactivity concentrations were $77{\sim}133Bq\;kg^{-1}$, $77{\sim}105Bq\;kg^{-1}$, and $252{\sim}372Bq\;kg^{-1}$ in fly ash samples and $54{\sim}91Bq\;kg^{-1}$, $46{\sim}83Bq\;kg^{-1}$, and $205{\sim}462Bq\;kg^{-1}$ in bottom ash samples. For flue gas desulfurization (FGD) gypsum, the radioactivity concentrations were $3{\sim}5Bq\;kg^{-1}$, $2{\sim}3Bq\;kg^{-1}$, and $22{\sim}47Bq\;kg^{-1}$. Radioactivity was enhanced in coal ash compared with coal due to combustion of organic matters in the coal. Radioactivity enhancement factors for $^{226}Ra$, $^{228}Ra$, and $^{40}K$ were 2.1~11.3, 2.0~13.1, and 1.4~7.4 for fly ash and 2.0~9.2, 2.0~10.0, 1.9~7.7 for bottom ash. The database established in this study can be used as basic data for internal dose assessment of workers at coal-fired power plants. In addition, the findings can be used as a basic data for development of safety standard and guide of Natural Radiation Safety Management Act.

• Economic and Environmental Geology
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• v.52 no.2
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• pp.119-128
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• 2019

About 300,000 tones of oyster shell are annually produced in Korea and, thus, a massive recycling plan is required. Many desulfurizing studies using oyster shells with chemical composition of $CaCO_3$ have been performed so far; however, most of them have focused on dry desulfurization. This study investigates the possibility of using oyster shells for wet desulfurization after calcination. For this, a simulated wet desulfurization facility of spray type was devised and compared the SOx-stripping characteristics of calcined oyster shell with those of limestone. The calcined oyster shell slurry indicate a better desulfurizability than the slurries of raw shell or limestone because the oyster shell transformed to a more reactive phase ($Ca(OH)_2$) by the calcination and hydration. Because of this reason, when the calcined oyster shell slurries were used, the reaction residue showed the higher gypsum ($CaSO_4{\cdot}2H_2O$) contents than any other cases. In the continuous desulfurization experiments, calcined oyster shell slurry showed a wider pH variation than limestone or raw oyster shell slurries, another clear indication of high reactivity of calcined oyster shells for $SO_2$ absorption. Our study also shows that the efficiency of wet desulfurization can be improved by the use of calcined oyster shells.

• Korean Chemical Engineering Research
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• v.57 no.3
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• pp.400-407
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• 2019

Oxy-combustion with a circulating fluidized bed (Oxy-CFBC) technology has been paid attention to cope with the climate change and fuel supply problem. In addition, Oxy-CFBC technology as one of the methods for carbon dioxide capture is an eco-friendly that can reduce air pollutants, such as $SO_2$, NO and CO through a flue gas recirculation process. The newly developed $100kW_{th}$ pilot-scale Oxy-CFBC system used for this research has been continuously utilizing to investigate oxy-combustion characteristics for various fuels, coals and biomasses to verify the possibility of fuel diversification. The anthracite is known as a low reactivity fuel due to a lot of fixed carbon and ash. Therefore, this study aims not only to improve combustion efficiency of an anthracite, but also to capture carbon dioxide. As a result, compared to air-combustion of sub-bituminous coal, oxy-combustion of anthracite could improve 2% combustion efficiency and emissions of $SO_2$, CO and NO were reduced 15%, 60% and 99%, respectively. In addition, stable operating of Oxy-CFBC could capture above 94 vol.% $CO_2$.

• Clean Technology
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• v.27 no.1
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• pp.61-68
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• 2021

Selective catalytic reduction (SCR) is widely used as a method of removing nitrogen oxide in large-capacity thermal power generation systems. Uniform mixing of the injected ammonia and the inlet flue gas is very important to the performance of the denitrification reduction process in the catalyst bed. In the present study, a computational analysis technique was applied to the ammonia injection system design process of a denitrification facility. The applied model is the denitrification facility of an 800 MW class coal-fired power plant currently in operation. The flow field to be solved ranges from the inlet of the ammonia injection system to the end of the catalyst bed. The flow was analyzed in the two-dimensional domain assuming incompressible. The steady-state turbulent flow was solved with the commercial software named ANSYS-Fluent. The nozzle arrangement gap and injection flow rate in the ammonia injection system were chosen as the design parameters. A total of four (4) cases were simulated and compared. The root mean square of the NH3/NO molar ratio at the inlet of the catalyst layer was chosen as the optimization parameter and the design of the experiment was used as the base of the optimization algorithm. The case where the nozzle pitch and flow rate were adjusted at the same time was the best in terms of flow uniformity.