• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.9
• /
• pp.862-869
• /
• 2010

Numerical analysis was done to evaluate the gas flow distribution in small scale SCR system which has $2.4{\times}2.4{\times}3.1\;m^3$ in volume and 25,300 Sm3/hr in flue gas flow capacity. Various types of baffles proposed for controlling the flow uniformity were evaluated by the CFD analysis to find the optimal geometry of the baffle in the SCR system. By installing baffles in the SCR system, the RMS (%) value was raised up to 6.2% compared with the baffle-uninstalled state. The effect of baffle thicknesses on the RMS (%) value was not shown within 0 and 8 mm in thickness, but the RMS (%) value was raised by 2.5% in 10 mm of baffles thickness, which causes the unstability in flow. By comparison between the shape of baffles, it is known that the lattice type baffle has better performance in controlling the flow uniformity than the circular truncated cone type baffle or mixer type baffle. RMS (%) values have more that 10% difference according to the shape of baffle type.

• Journal of the Korean Chemical Society
• /
• v.29 no.1
• /
• pp.52-60
• /
• 1985

Oxides of nitrogen (NO$_x$) in exhaust gases was determined by absorbing the gas in alkaline peroxide solution containing 0.03${\%}$ H2O2 and 0.1N NaOH. About 100 ppm of NO$_x$ was rapidly oxidized to NO$_2$ or N$_2$O$_5$ by H$_2$O$_2$ and required a contact time of 2 minutes with the absorbing solution for complete absorption. With vigorous shaking including air or oxygen gas, high concentration of NO$_x$ (>200 ppm) can be absorbed within 30 minutes. The remaining H$_2$O$_2$ affect the absorbance of color solution strongly. However, the excess H$_2$O$_2$ was completely decomposed by zinc powder 0.5g and the sample solution should be adjusted to the pH range 6.1∼6.6 before the reduction so that conversion of nitrate to nitrite ion is possible. The absorbed NO$_x$ is determined colorimetrically by the diazotization-coupling method with sulfonilamide and NEDA as the coupling agent. The sensitivity of the new method was 4.48 ${\times}$ 10$^4$ as molar absorptivity which was high sensitive compared with that obtained for the usual zinc reduction NEDA method with O$_3$. This method was far more rapid, brief and accurate than previously published O$_3$-NEDA method in Korean industrial standard.

• Journal of Environmental Health Sciences
• /
• v.33 no.3
• /
• pp.217-226
• /
• 2007

The purpose of this study is to estimate the emission factor of $non-CO_2$ global warming gases such as $N_2O$ and $CH_4$ by measuring concentrations from stacks of waste incinerators and cement production plants. Based on the established monitoring methods, $N_2O$ concentration measured from stacks in incinerator were between 0.62 and $40.60\;ppm_v$ (ave. $11.50\;ppm_v$). The concentration of $N_2O$ was dependent on the incinerator types. However, the concentrations of $CH_4$ gas were between 2.65 and $5.68\;ppm_v$ (ave. $4.22\;ppm_v$), and did not show the dependency on the incinerator types. In the cement production plant, the concentration ranges of $N_2O$ from the stack were from 6.90 to $10.80\;ppm_v$ (ave. $8.60\;ppm_v$), and $CH_4$ were between 1.80 and $2.20\;ppm_v$ (ave. $2.60\;ppm_v$). Using measured concentrations, the emission amounts of $N_2O$ and $CH_4$ from stacks per year were calculated. The results were is 4.2 ton $N_2O/yr$ in the incinerators, and 53.7 ton $N_2O/yr$ in the cement facilities. The big difference is from the flow rate of flue gas in the cement facilities compared to the incinerators. By the same reason, the $CH_4$ emission amounts in cement plant and incinerator was found to be 339 ton $CO_2/yr$ and 34.1 ton $CO_2/yr$, respectively. Finally, the emission factor of $N_2O$ in the incinerators were calculated using the measured concentration and the amount of incinerated wastes, and was $42.5\sim799.1\;g/ton$ in kiln and stoker type, $11.9\sim79.9\;g/ton$ in stoker type, 90.1 ton/g in rotary kiln type, 174.9 g/ton in fluidized bed type, and 63.8 g/ton in grate type, respectively. Also, the emission factors of $CH_4$ were found to 65.2-91.3 g/ton in kiln/stoker type, 73.9-122 g/ton in stoker type, 109.5 g/ton rotary kiln, and 26.1 g/ton in fluidized bed type. This result indicates that the emission factor in incinerators is strongly dependent on the incinerator types, and matched with result of IPCC (International Panel on Climate Change) guideline.

• Korean Chemical Engineering Research
• /
• v.60 no.4
• /
• pp.582-587
• /
• 2022

Biphasic solvents are attracting attention as energy-reducing solvents for capturing CO₂ from flue gas in combustion process. In this study, considering diethylenetriamine (DETA) and diethylethanolamine (DEEA) mixed solvents, one of the biphasic solvents by blending of two types of amines, the CO₂ absorption rates of DETA and DEEA was measured by wetted wall column. The effects of DETA and DEEA concentrations and operating temperature on the overall mass transfer coefficient were investigated. As a result, the overall mass transfer coefficient was proportional to the DETA concentration. However, in the case of the DEEA concentration, the effect was small and when the concentration was exceeded, the overall mass transfer coefficient decreased. The DETA aqueous solution showed little change in the overall mass transfer coefficient with the operating temperature, whereas the DEEA aqueous solution increased the overall mass transfer coefficient with the operating temperature. As a result of obtaining the observed reaction rate constant under the pseudo-first-order reaction assumption, it was found that the observed reaction rate constant in DETA aqueous solution was proportional to the DETA concentration, but DEEA did not fit the pseudo-first-order reaction assumption.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.5
• /
• pp.1-6
• /
• 2021

Mercury, once released, is not destroyed but accumulates and circulates in the natural environment, causing serious harm to ecosystems and human health. In the United States, sulfur-impregnated activated carbon is being considered for the removal of vapor mercury from the flue gas of coal-fired power plants, which accounts for about 32 % of the anthropogenic emissions of mercury. In this study, a high-efficiency porous mercury adsorption material was developed to reduce the mercury vapor in the exhaust gas of coal combustion facilities, and the mercury adsorption characteristics of the material were investigated. As a result of the investigation of the vapor mercury adsorption capacity at 30℃, the silica nanotube MCM-41 was only about 35 % compared to the activated carbon Darco FGD commercially used for mercury adsorption, but it increased to 133 % when impregnated with 1.5 % sulfur. In addition, the furnace fly ash recovered from the waste copper regeneration process showed an efficiency of 523 %. Furthermore, the adsorption capacity was investigated at temperatures of 30 ℃, 80 ℃, and 120 ℃, and the best adsorption performance was found to be 80 ℃. MCM-41 is a silica nanotube that can be reused many times due to its rigid structure and has additional advantages, including no possibility of fire due to the formation of hot spots, which is a concern when using activated carbon.

• Journal of Korean Society of Disaster and Security
• /
• v.16 no.3
• /
• pp.1-15
• /
• 2023

This study focuses on modeling the impact of ammonia leakage from the storage tank in a combined cycle power plant's flue gas denitrification facility. It employs accident impact assessments and diffusion models to determine the optimal scenarios for ammonia storage tank leakage accidents. The study considers the operating conditions of variables as standard conditions for predicting the extent of damage. The Taean combined cycle power plant is chosen as the target area, taking into account seasonal factors such as temperature, humidity, wind speed, atmospheric stability, and wind direction. By utilizing a Gaussian diffusion model, the concentration of ammonia gas at various locations is estimated to assess the potential extent of external damage resulting from a leak. The study reveals that in conditions of high temperature and stable atmosphere within the specified range, lower wind speeds contribute to increased damage to the human body due to ammonia diffusion.

• Korean Chemical Engineering Research
• /
• v.53 no.5
• /
• pp.590-596
• /
• 2015

Estimating potential of $CO_2$ emission reduction of non-capture $CO_2$ utilization (NCCU) technology was evaluated. NCCU is sodium bicarbonate production technology through the carbonation reaction of $CO_2$ contained in the flue gas. For the estimating the $CO_2$ emission reduction, process simulation using process simulator (PRO/II) based on a chemical plant which could handle $CO_2$ of 100 tons per day was performed, Also for the estimation of the indirect $CO_2$ reduction, the solvay process which is a conventional technology for the production of sodium carbonate/sodium bicarbonate, was studied. The results of the analysis showed that in case of the solvay process, overall $CO_2$ emission was estimated as 48,862 ton per year based on the energy consumption for the production of $NaHCO_3$ ($7.4GJ/tNaHCO_3$). While for the NCCU technology, the direct $CO_2$ reduction through the $CO_2$ carbonation was estimated as 36,500 ton per year and the indirect $CO_2$ reduction through the lower energy consumption was 46,885 ton per year which lead to 83,385 ton per year in total. From these results, it could be concluded that sodium bicarbonate production technology through the carbonation reaction of $CO_2$ contained in the flue was energy efficient and could be one of the promising technology for the low $CO_2$ emission technology.

• Korean Chemical Engineering Research
• /
• v.50 no.4
• /
• pp.646-653
• /
• 2012

We studied the economic evaluations on Korea Institute of Energy Research (KIER)'s $CO_2$ capture process using dry sorbents, and compared the results with those of comparable technologies. Capital and operating costs of the $CO_2$ capture system for 500 MW coal fired power plant were estimated to determine the economic feasibility. LCOE (Levelized Cost of Energy) and $CO_2$ capture cost appeared 32.46$/MWh and 28.15$/ton$CO_2$, respectively. The internal rate of return (IRR), the net present values (NPV), and the payback period (PBP), were calculated by assuming several variables. As the result of calculation, IRR of KIER's $CO_2$ capture system was 15%, NPV was calculated 6,631,000$, and PBP was 5.93 years at $50/t$CO_2$ of CER price. Consequently, this process can compete with other comparative processes using dry sorbents.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.8 no.1
• /
• pp.8-16
• /
• 2020

As the circulating fluidized bed combustor(CFBC) boilers system to generate electric power increase in order to reduce environmental pollution, a lot of CFBC fly ashes(CFFA) are produced. CFFA has limited use in concrete because it contains free CaO, which can cause cement expansion and rapid initial hydration. In this study, the microstructure and the initial development of compressive strength characteristics were experimentally analyzed to be used as a stimulant to replace natural gypsum by mixing with CFFA and phosphate gypsum to enhance the initial strength of portland blast furnace slag cement. The recycled gypsum was used as flue-gas desulfurization gypsum and phosphate gypsum. Experimental results show that the initial strength development is relatively lower when CFFA and dihydrate gypsum are mixed, but the strength improvement effect of the mixture with CFFA and anhydrous gypsum as an anhydritedII typed crystalized gypsum is similar to that of natural gypsum. As a result, it w as analyzed to have high possibility of use for stimulant of portland blast furnace slag cement.

• Journal of the Korean Recycled Construction Resources Institute
• /
• v.4 no.3
• /
• pp.227-234
• /
• 2016

In this study, asphalt paving filler, which satisfies the KS standards, were prepared from industrial by-products, such as fly ash generated from thermal power plants, cogeneration ash generated from cogeneration plants, and desulfurized gypsum generated from the flue-gas desulfurization process. The properties of the prepared mixed filler and the existing limestone filler were compared through laboratory tests for preparing asphalt mixture using each filler. In addition, asphalt pavement field tests were conducted using the limestone filler and mixed filler. The dynamic stability, Marshall stability, tensile strength ratio, saturation, porosity, and flow value of the asphalt mixtures used in the field test were evaluated, as was done in the laboratory test. The laboratory and field construction test results revealed outstanding tensile strength ratio, Marshall stability and dynamic stability when using the prepared filler than for the existing limestone filler. Through optimization of the mixing design, the possibility of developing fillers, which the characteristics of the existing limestone filler, was confirmed.