국내 석탄 연소 발전소 내 작업종사자의 입자 흡입에 따른 내부피폭 방사선량 평가

이도연,진용호,곽민우,김지우,김광표 (사)한국방사선산업학회 2023 방사선산업학회지 Vol.17 No.2

Coal-fired power plants handle large quantities of coal, one of the most prominent NORM,and the coal ash produced after the coal is burned can be tens of times more radioactive than thecoal. Workers in these industries may be exposed to internal exposure by inhalation of particles whilehandling NORM. This study evaluated the size, concentration, particle shape and density, and radioactivityconcentrations of airborne suspended particles in the main processes of a coal-fired power plant. Finally,the internal radiation dose to workers from particle inhalation was evaluated. For this purpose, airborneparticles were collected by size using a multi-stage particle collector to determine the size, shape, andconcentration of particles. Samples of coal and coal ash were collected to measure the density andradioactivity of particles. The dose conversion factor and annual radionuclide inhalation amount werederived based on the characteristics of the particles. Finally, the internal radiation dose due to particleinhalation was evaluated. Overall, the internal radiation dose to workers in the main processes of coalfiredpower plants A and B ranged from 1.47×10-5~1.12×10-3 mSv y-1. Due to the effect of dust generatedduring loading operations, the internal radiation dose of fly ash loading processes in both coal-fired powerplants A and B was higher than that of other processes. In the case of workers in the coal storage yard atpower plants A and B, the characteristic values such as particle size, airborne concentration, and workingtime were the same, but due to the difference in radioactivity concentration and density depending onthe origin of the coal, the internal radiation dose by origin was different, and the highest was found wheninhaling coal imported from Australia among the five origins. In addition, the main nuclide contributingthe most to the internal radiation dose from the main processes in the coal-fired power plants wasthorium due to differences in dose conversion factors. However, considering the external radiation doseof workers in coal-fired power plants presented in overseas research cases, the annual effective dose ofworkers in the main processes of power plants A and B does not exceed 1 mSv y-1, which is the dose limitfor the general public notified by the Nuclear Safety Act. The results of this study can be utilized to identifythe internal exposure levels of workers in domestic coal-fired power plants and will contribute to theestablishment of a data base for a differential safety management system for NORM-handling industriesin the future.

콜타르로부터 탄소섬유 제조를 위한 프리커서용 석탄계 핏치의 제조

고효준,박창욱,조효행,유미정,김명수,임연수,Ko, Hyo Joon,Park, Chang Uk,Cho, Hyo Hang,Yoo, Mi Jung,Kim, Myung-Soo,Lim, Yun-Soo 한국재료학회 2013 한국재료학회지 Vol.23 No.5

Coal tar is the primary feedstock of premium graphitizable carbon precursor. Coal tars are residues formed as byproducts of thermal treatments of coal. Coal tar pitches were prepared through two different heat treatment schedules and their properties were characterized. One was prepared with argon and oxidation treatment with oxygen; the other was prepared with oxygen treatment at low temperature and then argon treatment at high temperature; both used coal tar to prepare coal tar pitches. To modulate the properties, different heat treatment temperatures ($300{\sim}400^{\circ}C$) were used for the coal tar pitches. The prepared coal tar pitches were investigated to determine several properties, such as softening point, C/H ratio, coke yield, and aromaticity index. The coal tar pitches were subject to considerable changes in chemical composition that arose due to polymerization after heat treatment. Coal tar pitch showed considerable increases in softening point, C/H ratio, coke yields, and aromaticity index compared to those characteristics for coal tar. The contents of gamma resin, which consists of low molecular weight compounds in the pitches and is insoluble in toluene, showed that the degree of polymerization in the pitches was proportional to C/H ratio. Using an oxidizing atmosphere like air to prepare the pitches from coal tar was an effective way to increase the aromaticity index at relatively low temperature.

Enhancement of slurryability and heating value of coal water slurry (CWS) by torrefaction treatment of low rank coal (LRC)

Park, Ju-Hyoung,Lee, Young-Joo,Jin, Min-Ho,Park, Se-Joon,Lee, Dong-Wook,Bae, Jong-Soo,Kim, Joeng-Geun,Song, Kwang Ho,Choi, Young-Chan Elsevier 2017 Fuel Vol.203 No.-

<P><B>Abstract</B></P> <P>To improve cold gas efficiency of entrained-flow gasification, coal water slurry (CWS) as a fuel must have high heating value at low viscosity. Especially, considering unstable supply of bituminous coal, the preparation of CWS with high coal content from low-rank coal remains a challenging topic. In this study, we report a remarkable improvement in coal content of CWS at low viscosity (1000cP) through torrefaction of low-rank coal. Compared to dried coal (moisture-free coal), the torrefaction of low-rank coal leads to an improvement in hydrophobic nature of coal surface and a decrease in coal porosity. The moisture readsorption ratio of the torrefied low-rank coal significantly decreases due to its high hydrophobic nature and low porosity. As a result, Kideco coal showed a 6% and 58.7% increase in the coal content and heating value of CWS after torrefaction at 300°C in comparison to those of CWS made with dried coal. Ultimately, the torrefied coal-based CWS with enhanced coal content and heating value at low viscosity is expected to contribute to an increase in the efficiency of a gasifier and IGCC process.</P> <P><B>Highlights</B></P> <P> <UL> <LI> VM was partly removed, and FC content and calorific value increase through torrefaction. </LI> <LI> Coal surface turned hydrophobic and pore volume decreased through torrefaction. </LI> <LI> Torrefaction inhibits water reabsorption and reduces the water filled in void volume. </LI> <LI> Torrefaction of LRC was conducted to prepare CWS with a higher coal content. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A comparison of spontaneous combustion susceptibility of coal according to its rank

Wantaek Jo,Ho Kyung Choi,Sangdo Kim,유지호,전동혁,Young-joon Rhim,Jeong-hwan Lim,Si-hyun Lee 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.5

This study investigated spontaneous combustion susceptibility of coal according to the rank. To estimate the spontaneous combustion susceptibility of coal, both crossing-point temperature (CPT) measurement and gas analysis by using gas chromatography (GC) were performed. For the experiment, Eco coal and Kideco coal, Indonesian lignite,and Shenhua coal that is Chinese bituminous coal were used. The lignite such as Eco coal and Kideco coal contains more functional groups that easily react to oxygen more so than Shenhua coal. For this reason, the lignite is more easily oxidized than bituminous coal at low temperature, which results in high O2 consumption, increase in CO and CO2 generation,and low CPT. Although the CPT of Eco coal and Kideco coal is identical to each other as they are the lignite,Kideco coal has a lower initial oxidation temperature (IOT) and maximum oxidation temperature (MOT) than those of Eco coal. This means that although each coal has the same rank and CPT, spontaneous combustion susceptibility of coal may vary because the initial temperature of the coal at which oxidation begins may be different due to the substances that participate in oxidation.

석탄의 발열량 범주별 CO2 배출량 분석을 통한 석탄발전의 온실가스 감축 방안 연구

정현록 한국기후변화학회 2022 한국기후변화학회지 Vol.13 No.4

In this paper, we sought to reduce greenhouse gas emissions from coal power plants by analyzing CO2 emissions by coal calorific value. To this end, the analysis data of coal introduced to three coal power plants in Korea from 2014 to 2021 was used, and the CO2 emissions for high-calorific coal, medium-calorific coal, and low-calorific coal were analyzed. The CO2 emission factors were 95,264 kgCO2/TJ for high-calorific coal, 97,096 kgCO2/TJ for medium-calorific coal, and 100,027 kgCO2/TJ for low-calorific coal. CO2 emission intensity was 891.33 kgCO2/MWh for high-calorific coal, 908.47 kgCO2/MWh for medium-calorific coal, and 935.89 kgCO2/MWh for low-calorific coal. Therefore, CO2 emissions can be reduced by increasing the proportion of high-calorific coal compared to low-calorific coal in coal power generation. However, some issues need to be addressed before expanding the proportion of high-calorific coal. First, as particulate matter emissions are higher for high-calorific coal, the performance of air pollution prevention facilities must be improved. Second, because the price of high-calorific coal is higher than that of low-calorific coal, policy changes regarding the individual consumption tax imposed on coal are needed to improve the price competitiveness of high-calorific coal.

Evaluation of the Coal-Degrading Ability of Rhizobium and Chelatococcus Strains Isolated from the Formation Water of an Indian Coal Bed

( Durgesh Narain Singh ),( Anil Kumar Tripathi ) 한국미생물 · 생명공학회 2011 Journal of microbiology and biotechnology Vol.21 No.11

The rise in global energy demand has prompted researches on developing strategies for transforming coal into a cleaner fuel. This requires isolation of microbes with the capability to degrade complex coal into simpler substrates to support methanogenesis in the coal beds. In this study, aerobic bacteria were isolated from an Indian coal bed that can solubilize and utilize coal as the sole source of carbon. The six bacterial isolates capable of growing on coal agar medium were identified on the basis of their 16S rRNA gene sequences, which clustered into two groups; Group I isolates belonged to the genus Rhizobium, whereas Group II isolates were identified as Chelatococcus species. Out of the 4 methods of whole genome fingerprinting (ERIC-PCR, REP-PCR, BOX-PCR, and RAPD), REPPCR showed maximum differentiation among strains within each group. Only Chelatococcus strains showed the ability to solubilize and utilize coal as the sole source of carbon. On the basis of 16S rRNA gene sequence and the ability to utilize different carbon sources, the Chelatococcus strains showed maximum similarity to C. daeguensis. This is the first report showing occurrence of Rhizobium and Chelatococcus strains in an Indian coal bed, and the ability of Chelatococcus isolates to solubilize and utilize coal as a sole source of carbon for their growth.

석탄회를 활용한 친환경적 광해복구사업 추진방안에 관한 연구

조한나,맹준호 한국폐기물자원순환학회 2016 한국폐기물자원순환학회지 Vol.33 No.4

More than 8 M tons of coal ash is generated from coal-fired thermal power plants every year, and the generation rateof coal ash has been increasing steadily recently. However, the recycling rate of coal ash is about 70%. It is time tointroduce the beneficial use of coal ash. Much coal ash is used in mining applications and reclamation sites in the EUand the U.S. However, coal ash cannot be used at mine reclamation sites in Korea because of its legal limitations dueto environmental concerns. Therefore, in this research, the eco-friendly use of coal ash at mine reclamation sites in Koreais presented. To develop the eco-friendly use of coal ash at mine reclamation sites in Korea, this study examined thebeneficial use of coal ash at mines and the environmental issue of the specific use of coal ash at mine reclamations sitesand carried out case studies on the use and management systems of coal ash in overseas countries and investigation ofthe present use of coal ash at mine reclamation sites in Korea.

Effects of solvent extraction on the microstructure of bituminous coal-based graphite

Wang Lipeng,Yao Zongxu,Guo Zhimin,Shen Xiaofeng,Li Zhiang,Zhou Zhengqi,Wang Yuling,Yang Jian-Guo 한국탄소학회 2022 Carbon Letters Vol.32 No.3

Coal-based graphite has become the main material of emerging industries. The microstructure of coal-based graphite plays an important role in its applications in many fields. In this paper, the effect of carbon disulfide/N-methyl-2-pyrrolidone solvent mixture extraction on the microstructure of bituminous coal-based graphite was systematically studied through preliminary extraction coupled with high-temperature graphitization. The graphitization degree g (75.65%) of the coal residue-based graphite was significantly higher than that of the raw coal-based graphite. The crystallite size La of the coal residue-based graphite was reduced by 47.06% compared with the raw coal-based graphite. The ID/ IG value of the coal residue-based graphite is smaller than that of the raw coal-based graphite. The specific surface area (16.72 m2/g) and total pore volume (0.0567 m3/g) of the coal residue-based graphite are increased in varying degrees compared with the raw coal-based graphite. This study found a carbon source that can be used to prepare coal-based graphite with high graphitization degree. The results are expected to provide a theoretical basis for further clean and efficient utilization of the coal residue resources.

Screening of Microorganisms able to Degrade Low-rank Coal in Aerobic Conditions: Potential Coal Biosolubilization Mediators from Coal to Biochemicals

Yokimiko David,Mary Grace Baylon,Sudheer D. V. N. Pamidimarri,Kei-Anne Baritugo,채철기,김유진,김태완,김민식,나정걸,박시재 한국생물공학회 2017 Biotechnology and Bioprocess Engineering Vol.22 No.2

Coal is one of the major sources of energy, fuel, and other related chemicals. The processes to utilize coal for energy, fuel and other chemicals such as coal combustion, liquefaction, carbonization, and gasification pose a great threat to the environment by emitting toxic particles and CO2 to the atmosphere. Thus, biological beneficiation of coal can be a good strategy to utilize coal with environmental sustainability. Here, we report the screening of microorganisms able to degrade or depolymerize coal. These host strains are potential candidates for the development of biological treatment process of coal. A total of 45 microbial strains were isolated from sludge enriched with coal and were identified based on 16S rRNA sequencing. Four strains of three genera, Cupriavidus sp., Pseudomonas sp., and Alcaligenes sp., were further characterized for their abilities to degrade coal. The degree of coal degradation was analyzed by measuring the increase in absorbance at 450 nm by UV spectroscopy. These microorganisms were also able to increase the pH of the culture media as a response to the acidic nature of coal. Laccase-like activity was also found in these strains when tested for RBBR dye degradation. Since biological degradation of coal through the use of microorganisms is a good alternative to chemical combustion of coal, microbial strains isolated in this study can be potential biological catalysts for coal conversion into valuable chemicals.

Bio-solubilization of the untreated low rank coal by alkali-producing bacteria isolated from soil

메리 그레이스 베일런,요키미코 데이비드,Sudheer D. V. N. Pamidimarri,Kei-Anne Baritugo,채철기,김유진,김태원,김민식,나정걸,박시재 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.1

Coal is a hydrocarbon-rich fossil fuel considered as a possible replacement for petroleum as a feedstock for the production of fuel and valuable chemicals. In this study, bacteria capable of solubilizing untreated low rank coal were isolated from soil. A total of 19 microorganisms were isolated from soil enriched in MR medium with coal and were identified based on 16S rRNA sequencing. The identified soil isolates belonging to the genera Citricoccus, Comamonas, Cupriavidus, Sphingomonas, and Sphingopyxis were screened based on their growth in the chemically defined MR medium containing different concentrations of coal. Among the identified microbial strains, Cupriavidus necator S2A2, Sphingopyxis ginsengisoli S2B14 and Sphingomonas sp. S2B18 were further characterized for their ability to degrade low-rank coal. Cupriavidus necator S2A2, Sphingopyxis ginsengisoli S2B14 and Sphingomonas sp. S2B18 were found to solubilize untreated low-rank coal as indicated by the release of solubilized coal products detected at OD450 when they were grown in LB medium containing 1% coal. Sphingomonas sp. S2B18 showed the highest coal solubilization activity, based on the high absorbance of its culture supernatant (0.190). Although laccase-like activity was not detected in these strains when tested for RBBR dye degradation, increase in the pH of the culture medium up to 8.25- 8.34 was observed. This may be attributed to the excretion of alkaline substances in the culture medium. Since biosolubilization of coal by microorganisms is a good alternative for the chemical conversion of coal, microorganisms screened in this study can be potentially used as biological catalysts for the conversion of coal into valuable chemicals.