• Journal of Environmental Science International
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• v.15 no.6
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• pp.587-592
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• 2006

The advantage of CFBC(Circulating fluidized bed combustor) is that it can apply to various fuel sources including the lower rank fuel and remove SOx by means of direct supply of limestone to the combustor without additional desulfation facility. In this paper, we denote characteristics of fly and bed ash to reuse finer limestone usually abandoned(used spec[Coarse LS] 0.1mm under 25%, new spec[Fine LS] 0.1mm under 50%). According to the results, the chemical composition of fly ash was as follows; $SiO_2\;40.8%,\;Al_2O_3\;31.9%,\;CaO\;10.7%,\;K_2O\;4.46%$ in the case of coarse limestone and $SiO_2\;41.1%,\;Al_2O_3\;31.3%,\;CaO\;10.9%,\;K_2O\;4.66%$ in the case of fine limestone. The chemical composition of bed ash was as follows; $SiO_2\;54.2%,\;Al_2O_3\;33.1%,\;CaO\;1.56%,\;K_2O\;4.34%$ in the case of coarse limestone and $SiO_2\;53.8%,\;Al_2O_3\;32.6%,\;CaO\;2.21%,\;K_2O\;4.45%$ in the case of fine limestone. It showed that there was no significant change in chemical composition. And it is conformed that there was no significant change in particle size and shapes.

• Resources Recycling
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• v.27 no.3
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• pp.58-65
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• 2018

For the recycling of coal ash from the domestic circulating fluidized bed boilers, a lime-based sorbent with 0.2~0.4 mm size was prepared by using limestone powder and CFBC fly ash. Mixing a small amount of slaked lime in the lime-based absorbent lead the formation of calcium silicate on the surface of the particle and the strength of absorbent particle was improved. As a result of comparing the desulfurization characteristics, it was found that the conversion rate was about 10% higher than that of commercially available limestone desulfurization used in the furnace, which is confirmed that it can be used as a desulfurization absorbent.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.7
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• pp.677-686
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• 2016

A thermal power plant is the first CFBC (Circulating Fluidized Bed Combustion) power plant consisting of 2 boilers-1 turbine. The optimal height of a stack needs to be approximately 156 meters in the case of this thermal power plant; however, the thermal power plant sites satisfy a function and reduce the construction cost by using mountains in the sites after cutting the ground and locating an integrated office and chimney at an altitude of 70 meters thereby lowering the height of the stack to 86 meters. In addition, the integrated office, which has a combined stack style with a unique design, is constructed by connecting with 2 stacks and disposing the office and an observatory in the space between them. Therefore, this study examined the design concept that fulfils the structural, functional, and aesthetic factors, harmoniously by joining the integrated office and the stack, which are disparate, and investigated special construction methods (Slip Form, Steel Inner Flue & Lift-up) through which heterogeneous architectures are structurally, functionally, and aesthetically constructed.

• Resources Recycling
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• v.31 no.3
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• pp.40-52
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• 2022

This study analyzed the amount of carbon dioxide reduction and economic benefits of detailed processes of CO₂ 6,000 tons plant facilities with mineral carbonation technology using carbon dioxide and coal materials emitted from domestic circulating fluidized bed combustion power plants. Coal ash reacted with carbon dioxide through carbon mineralization facilities is produced as a complex carbonate and used as a construction material, accompanied by a greenhouse gas reduction. In addition, it is possible to generate profits from the sales of complex carbonates and carbon credits produced in the process. The actual carbon dioxide reduction per ton of complex carbonate production was calculated as 45.8 kgCO₂eq, and the annual carbon dioxide reduction was calculated as 805.3 tonCO₂, and the benefit-cost ratio (B/C Ratio) is 1.04, the internal rate return (IRR) is 10.65 % and the net present value (NPV) is KRW 24,713,465 won, which is considered economical. Carbon mineralization technology is one of the best solutions to reduce carbon dioxide considering future carbon dioxide reduction and economic potential.

• Korean Chemical Engineering Research
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• v.47 no.5
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• pp.580-586
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• 2009

In this study, co-combustion characteristics of Chinese bituminous coal and North Korean anthracite were investigated using a 2 MWe scale circulating fluidized bed power plant. At first, the combustion efficiency of bituminous coal of China and Australia as a function of excess air ratio and temperature were observed. The results showed that the combustion efficiency was influenced by particle size and volatile content of coal, the combustion efficiency of Chinese bituminous coal was over 99.5%. The unburned carbon particles from fly ash and bottom ash were a content 5~7% and 0.3%, respectively. The combustion efficiency with the mixture ratio 20% of bituminous coal and anthracite decreased over 5% because of the increase of entrained particles by a small average particle size of anthracite in the combustor. However, the outlet concentration of $SO_2$ and $NO_x$ was not changed remarkably. The concentrations of the typical air pollutants such as $NO_x$ and $SO_2$ were 200~250 ppm($O_2$ 6%), 100~320 ppm($O_2$ 6%) respectively. The outlet concentration of $NO_x$ was decreased to 30~65% with $NH_3$ supplying rate of 2~13 l/min in SCR process. The $SO_x$ removal efficiency was up to 70% by in-furnace desulfurization using limestone with Ca/S molar of approximately 6.5. With wet scrubbing using $Mg(OH)_2$ as absorbent, the $SO_x$ removal efficiency reached 100% under near pH 5.0 of scrubbing liquid.

• Korean Chemical Engineering Research
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• v.47 no.6
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• pp.795-800
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• 2009

In this study, the $CO_2$ removal characteristics of the Vortex tube type absorbtion apparatus were investigated to enhance the compactness of $CO_2$ absorption process and to reduce the amount of absorbing solution of the $CO_2$ separation process. The Vortex tube with the diameter of 17 mm and the length of 250mm was introduced in the experimental apparatus to treat $20Nm^3/hr$ of $CO_2$ containing flue gas. The flue gases for experiments containing 11~13 vol% of $CO_2$ were supplied from the coal-firing CFBC power plant with 12 ton/hr of steam producing capacity. The mixed solutions of 20 wt% of MEA as base solution with the adding solutions like HMDA, AMP and KOH were used as absorbents. The experiments were executed under the various conditions like the absorbing solution concentrations in the range of 20 to 50 wt%, the flow rate of $CO_2$ containing flue gases in the range of 6 to $15Nm^3/hr$ and the flow rate of absorbing solution in the range of 1.0 to 3.0 l/min. As a results, the $CO_2$ removal efficiency of mixed absorbent of 20 wt% of MEA with HMDA was remarkable. From this study, we concluded that the efficient separation of $CO_2$ from flue gases using the features of the Vortex tube type absorbing unit for gas/liquid contact and the separation of gas/liquid be possible. But more works are needed to increase the $CO_2$ removal efficiency of Vortex tube process.

• Clean Technology
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• v.24 no.3
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• pp.212-220
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• 2018

Oxy-fuel combustion is considered as a promising greenhouse gas reduction technology in power plant. In this study, the behaviors of NO and $SO_2$ were investigated under the condition that in-furnace $deNO_x$ and $deSO_x$ methods are applied in oxy-fuel circulating fluidized bed combustion condition. In addition, the generation trends of $SO_3$, $NH_3$ and $N_2O$ were observed. For the purpose, limestone and urea solution were directly injected into the circulating fluidized bed combustor. The in-furnace $deSO_x$ method using limestone could reduce the $SO_2$ concentration in exhaust gas from ~403 to ~41 ppm. At the same experimental condition, the $SO_3$ concentration in exhaust gas was also reduced from ~3.9 to ~1.4 ppm. This trend is mainly due to the reduction of $SO_2$. The $SO_2$ is the main source of the formation of $SO_3$. The negative effect of $CaCO_3$ in limestone, however, was also appeared that it promotes the NO generation. The NO concentration in exhaust gas reduced to ~26 - 34 ppm by appling selective non-catalytic reduction method using urea solution. The $NH_3$ concentration in exhaust gas was appeared up to ~1.8 ppm during injection of urea solution. At the same time, the $N_2O$ generation also increased with increase of urea solution injection. It seems that the HNCO generated from pyrolysis of urea converted into $N_2O$ in combustion atmosphere. From the results in this study, the generation of other pollutants should be checked as the in-furnace $deNO_x$ and $deSO_x$ methods are applied.