• 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.

• Journal of the Korean GEO-environmental Society
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• v.11 no.5
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• pp.25-34
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• 2010

In this study characteristics for reclaimed ash was studied to enlarge the usage of reclaimed ash which is reaching to 72 million ton producted from whole thermal power plants in South Korea. Fly ash and bottom ash are reclaimed separately at some of thermal power plants. However, typically bottom ash and fly ash are mixed when they are buried at most of the thermal power plant, as a result the engineering characteristics of ponded ash are not investigated properly. In order to investigate the engineering characteristics of the ponded ash, laboratory tests were performed with ponded ash and fly ash from youngheung and samcheonpo thermal power plants. Specific gravity, unit weight, and grain size analysis test were fulfilled to evaluate the physical characteristics and triaxial permeability test, direct shear test, unconfined compressive strength test, compaction test were performed to evaluate the mechanical characteristics. And also engineering characteristics of coal ash from anthracite and Bituminous thermal power plants were compared and studied respectively. As a result of the study, it was confirmed that using coal ash from Bituminous thermal power plants can be effective in the place where lightweight materials are required and using coal ash from anthracite thermal power plants can be effective as backfill material which require higher permeability. Finally, it was confirmed that fly ash from youngheung thermal power plants which has the lowest permeability among the tested material is suitable for a field requiring impermeable material.

• Korean Journal of Soil Science and Fertilizer
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• v.27 no.4
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• pp.275-283
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• 1994

The effects of anthracite and bituminous fly ash application on rice yield were investigated and the available silicate in paddy soil with ash application was analyzed. The obtained results are as follow : The yield of rice gradually decreased as the amount of anthracite ash increased. On the contrary, the rice yield gradually increased as the amount of bituminous ash increased. At harvesting stage the chemical properties in soil such as pH, organic content, and inorganic content($P_2O_5$, K. Ca, Mg and available $SiO_2$) were higher in bituminous ash treated soil than in anthracite treated soil. The amount of inorganic components in rice plant such as T-N, $P_2O_5$, $K_2O$, CaO, and MgO gradually decreased with the growing stage of rice. However, the amount of available silicate increased with the growing stage of rice. The silicate content in soil was determined by two different methods ; 1N-NaOAc extracted method and submerging setting method. In bituminous ash treated soil, the correlation between the silicate content in plant and in soil was found when the silicate content in soil was determined by the soil submerging method. In anthracite ash treated soil, however no correlation was found between the silicate content in plant and in soil determined by either method.

• Journal of Energy Engineering
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• v.21 no.1
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• pp.68-74
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• 2012

Sub-bituminous coals have been used increasingly in coal-fired power plants with a proportion of over 50% in the blend with bituminous coals. As a result, the unburned material in fly ash has increased and is causing problems in utilizing the fly ash as an additive for concrete production. In this study, analysis of fly ash obtained from a 500 MWe power plant was carried out and unburned material in the fly ash found to be soot. The coals used in the plant were analyzed with CPD model to investigate the sooting potential depending on the coal type and blending ratio.

• Journal of the Korean Ceramic Society
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• v.54 no.2
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• pp.128-136
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• 2017

Fly ash from a circulating fluidized bed combustion boiler (CFBC fly ash) is very different in mineralogical composition, chemical composition, and morphology from coal ash from traditional pulverized fuel firing because of many differences in their combustion processes. The main minerals of CFBC fly ash are lime and anhydrous gypsum; however, due to the fuel type, the strength development of CFBC fly ash is affected by minor components of active $SiO_2$ and $Al_2O_3$. The initial hydration product of the circulating fluidized bed combustion fly ash (B CFBC ash) using petro coke as a fuel is Portlandite which becomes gypsum after 7 days. Due to the structural features of the portlandite and gypsum, the self-cementitious strength of B CFBC ash was low. While the hydration products of the circulating fluidized bed combustion fly ash (A CFBC ash) using bituminous coal as a fuel were initially portlandite and ettringite, after 7 days the hydration products were gypsum and C-S-H. Due to the structural features of ettringite and C-S-H, A CFBC ash showed a certain degree of self-cementitious strength.

• Journal of the Mineralogical Society of Korea
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• v.27 no.1
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• pp.31-40
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• 2014

In present study, we geochemically investigated the fresh coal ashes and the saline ash pond of an electric power plant in Korea, which burns imported bituminous coals. The goals are to see the chemical changes of the ash pond by reaction with coal ashes and to investigate the relative leachability of elements from the ashes by reaction with saline waters. For this study, one fresh fly ash, one fresh bottom ash, and 7 water samples were collected. All the ash samples and 2 water samples were analyzed for 55 elements. The results indicated that the fly ashes are enriched with chalcophilic elements such as Cu, Zn, Ga, Ge, Se, Cd, Sb, Au, Pb, and B relative to other elements. On the other hand, concentrations of As, Ba, Co, Ga, Li, Mn, Mo, Sb, U, V, W, and Zr are much higher in the ash pond than those dissolved in the seawater. Ag, Bi, Li, Mo, Rb, Sb, Sc, Se, Sn, Sr, and W show high ratios of elemental concentrations in pond water to those in the fly ash. Our results imply that the leaching of trace elements is regulated by geochemical controls such as solubility and adsorption even though the trace elements are relatively enriched on the ash surfaces after the coal combustion due to their volatilities.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.1
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• pp.115-123
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• 1990

The purpose of this study was to examine the uses of coal ash as a type of construction material. The methods of examination were chemical anlysis, soil laboratory test and the soil vibration test. Materials used were coal ash obtained as a by-product from 5 thermal power plants in Yongdong, Yongwol, Sochon(anthracite coal) and in Samchonpo and Honam (bituminous coal). Over 70% of the coal ash consisted of silica and alumina. The fly ash grain size showed a uniform distribution from fine-sand to silt, and that of the bottom ash showed from sand to gravel. The specific gravity and density of the coal ash were low. The long term strength increased gradually due to the self-setting property resulting from pozzolanic activity. The shear strength was higher than that of general soil. Cohesion and optimum moisture content of anthracite coal ash were higher than bituminous coal ash, whereas the maximum dry density was higher in bituminous coal ash. The coal ash dynamic Young's modulous curve range was similar to that of general soil. Of the results from the soil vibration test by car-running, the size relative acceleration level in the ash pond was higher than that of natural ground, but the damping ratio was lower than that of natural ground near the ash pond. The coal ash has more advantageous engineering properties than general soil with particles of the same size. For example, the California Bearing Ratio of the bottom ash at both Yongdong and Yongwol was 77~137%. Therefore we expect that if further study is done, coal ash can be used as a construction material when reclaiming seashore, construction embankments, road construction, making right-weight aggregate, or as a general construction material.

• Journal of environmental and Sanitary engineering
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• v.14 no.3
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• pp.63-70
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• 1999

A study on the zeolite synthesized of bituminous coal fly ash from power plant has been carried out to reuse industrial waste. The synthesized zeolite was proved to be 4A type by means of the X-ray diffraction analysis and the degree of crystallinity was found to be higher than 90%. Then the synthesized zeolite was used as an adsorbent to remove the heavy metal ions in the CU, Pb, and Cd containing wastewater and water. Also, adsorption characteristics and kinetics of synthesized zeolite in the each metal ion solutions were studied. In each ion solutions, the adsorbed amounts of Pb, Cd, and Cu to the unit weight of synthesized zeolite were 141.6, 118.8, and 131.4mg/g respectively when each metal ion concentration was 500mg/L solution. The adsorption kinetics was fitted well to the Freundlich isotherms. The value of l/n for Pb, Cd, and Cu and 0.27, 0.50, and 0.66, respectively. Those results showed that the synthesized zeolite could be used as an adsorbent to remove single heavy metal ions in the wastewater and water. The heats of adsorption, H values of Pb, Cd, and Cu were 4.87, 14.95, and 18.23kacl/mol by the Henry-van't Hoff equation.

• Journal of the Korean Society of Combustion
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• v.14 no.2
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• pp.1-9
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• 2009

New way to effectively capture $CO_2$ in coal fired power plant is the combustion of coal using oxy-fuel technology. Combustion characteristics of Minco sub-bituminous coal at oxy-fuel conditions using TGA and drop tube furnace (DTF) were included activation energy about the char burnout, volatile yield and combustion efficiency of raw coal, the porosity of pyrolyzed char and fusion temperature of by-product ash. TGA result shows that the effect of $CO_2$ on combustion kinetics reduces activation energy by approximately 7 kJ/mol at air oxygen level(21% $O_2$) and decreases the burning time by approximately 16%. The results from DTF indicated similar combustion efficiency under $O_2/CO_2$ and $O_2/N_2$ atmospheres for equivalent $O_2$ concentration whereas high combustion efficiency under $O_2/N_2$ than $O_2/CO_2$ was obtained for high temperature of more than $1,100^{\circ}C$. Overall coal burning rate under $O_2/CO_2$ is decreased due to the lower rate of oxygen diffusion into coal surface through the $CO_2$ rich boundary layer. By-product ash produced under $O_2/CO_2$ and $O_2/N_2$ was similar IDT in irrelevant to $O_2$ concentration and atmospheres gas during the coal combustion.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.130-134
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• 1995

To investigate the influence of coal fly ash treatment on the heavy metal content in the infilteration water, 12t/10a/year of fly ash(Anthracite and Bituminous) were applicated at two paddy fields of different textured soils, clay loam and sandy loam, for 3 and 2 years, respectively. The infilteration waters were collected 30, 60 and 100cm of soil depth and the heavy metal contents were measured. In the paddy field of clay loam, the content of Zn in the infilteration water were increased with fly ash treatment and increasing soil depth, but it didn't show any significance. In the clay loam soil, successive application of fly ash for 3 years brought to increase Pb, Zn content in the infilteration water, Pb content was the highest at 100cm of soil depth, but the content of others were lower than non-treatment. In the paddy field of sandy loam, successive application of fly ash for 2 years increased Cd, Ni and Mn content in the infilteration water at anthracite ash application, but the contents of other elements were similar or lower than non-treatment.