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Combustion behaviors of wood pellet fuel and its co-firing with different coals
Lkhagvadorj Sh,정태용,전기태,박경원,이병화,전충환 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.9
Biomass resources, which are carbon-neutral and sustainable, may help to address climate change and reduce greenhouse gas emissions. This study was performed to examine the effects of wood pellet (WP) particle size, environmental conditions (stoichiometric ratio;SR), and blending ratio on the combustion characteristics of single fuels and blends using a thermogravimetric analyzer and drop tube furnace (DTF). The results indicate that WP demonstrated a higher mass reduction in the devolatilization region and a faster reaction rate compared with coal. Blends tested in the analyzer showed the expected profiles for devolatilization and char oxidation without the presence of non-additive effects. However, the DTF results showed that simultaneous reactive and non-reactive phenomena occurred with increasing biomass-blending ratios. When WP fuel containing fine particles (< 200 µm) was blended with coal under low SR conditions, early-stage oxygen deficiency was caused by rapid combustion. WP fuel containing coarse particles (> 600 µm) showed that unburned carbon (UBC) increased owing to slower reactivity. WP fuel containing particles of 400 µm or less in size demonstrated superior UBC performance, indicating that biomass-coal blends were significantly affected by blending ratio, particle size, and the surrounding environment.
Lkhagvadorj Sh,Byoung-Hwa Lee,Tae-Yong Jeong,전충환 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
Using biomass to produce energy is becoming a more desirable approach to environmentally sustainable energy production. However, there are currently several obstacles to efficient exploitation of this fuel source. In this study, the effects of torrefaction and ash reduction on the grindability of pitch pine sawdust (PSD) and its blends with coal were investigated. The particle size distributions after grinding, Hardgrove grindability index (HGI), scanning electron microscopy (SEM), and Brunauer-Emmett-Teller (BET) results of the fuels treated by the different methods were compared. The results indicated that ash reduction improved the grindability of raw PSD better than torrefaction, whereas torrefaction improved the grindability of ash-reduced PSD. Biomass particles produced by ash reduction generated high electrostatic forces and were relatively small. The SEM and BET results showed that the particles pretreated by ash reduction and torrefaction lost their characteristic fibrous structure and had a higher pore volume and surface area after grinding. The particle size distributions of the coalPSD blends were between those of coal and biomass. Both the 10 wt.% raw and ash-reduced PSD-coal blends exhibited similar grinding behaviors to pure coal after torrefaction. Therefore, ash reduction and torrefaction improved the grindability of single biomass fuels and coal-PSD blends.
바이오매스(우드펠릿) 혼소율 및 입자크기에 따른 연소 특성에 관한 연구
락와더르지(Lkhagvadorj Sh),김상인(Sang-In Kim),임호(Ho Lim),이병화(Byoung-Hwa Lee),김승모(Seung-Mo Kim),전충환(Chung-Hwan Jeon) 대한기계학회 2016 大韓機械學會論文集B Vol.40 No.1
최근 바이오매스와 석탄의 혼소 기술이 화력 발전의 주요한 연소 기술 중 하나로 떠오르고 있다. 그러나 혼소는 실제 발전용 보일러 적용시 많은 검증들을 필요로 한다. 본 연구에서는 바이오매스 혼소시 연소 특성을 알아보기 위해 열중량 분석기(Thermogravimetric analyzer, TGA)와 하향분류층 반응기(Drop tube furnace, DTF)를 사용하였으며, TGA의 TG/DTG 분석을 통한 반응성과 DTF를 이용한 UBC를 측정하여 연소 특성을 분석하였다. 특히 석탄과 바이오매스 혼소율(Biomass blending ratio) 및 바이오매스 입자 크기 변화에 따른 특성을 분석하였다. 그 결과, 바이오매스의 혼소율이 증가함에 따라 산소 부족으로 인한 반응 특성이 나타났으며, 이는 바이오매스가 가진 초기의 빠른 연소 특성 때문이다. 또한, 본 연구 결과를 통해 바이오매스의 최적 혼소 조건(UBC 발생량 기준)은 5%로 나타났으며, 산소 부화 조건은 바이오매스 혼소시 발생하는 산소 부족 현상을 저감시켜 미연분 상승을 완화시켜줄 수 있다. Co-firing of biomass with coal is a promising combustion technology in a coal-fired power plant. However, it still requires verifications to apply co-firing in an actual boiler. In this study, data from the Thermogravimetric analyzer(TGA) and Drop tube furnace(DTF) were used to obtain the combustion characteristics of biomass when co-firing with coal. The combustion characteristics were verified using experimental results including reactivity from the TGA and Unburned carbon(UBC) data from the DTF. The experiment also analyzed with the variation of the biomass blending ratio and biomass particle size. It was determined that increasing the biomass blending ratio resulted in incomplete chemical reactions due to insufficient oxygen levels because of the rapid initial combustion characteristics of the biomass. Thus, the optimum blending condition of the biomass based on the results of this study was found to be 5 while oxygen enrichment reduced the increase of UBC that occurred during combustion of blended biomass and coal.
바이오매스(EFB) 반응 및 혼소에 따른 연소 특성에 관한 연구
임호(Ho Lim),락와더르지(Lkhagvadorj Sh),박호준(Ho-Jun Park),전충환(Chung-Hwan Jeon) 한국에너지기후변화학회 2016 에너지기후변화학회지 Vol.11 No.2
In this study, the combustion characteristics of co-firing are analyzed based on the experimental methods. In order to determine the characteristics, the reactivity and unburned carbon (UBC) are investigated with blending ratio through TGA (Thermogravimetric analyzer) and DTF (Drop tube furnace), respectively. EFB (Empty Fruit Bunch), one of biomass fuels, is used. And Trafigura is applied, which is bituminous coal and has been used at the power plant. As a result, EFB shows that there are main stages such as dehydration, devolatilization and residue char combustion through TGA while coal combustion indicates one stage except dehydration. Especially, the volatile combustion including hemi-/cellulose and lignin indicates stronger than coal. In blends, as EFB fraction increases the characteristic of EFB represents obviously. DTF results show EFB affects UBC in co-firing. This is because of fast volatile combustion of EFB in initial combustion.
회분식 반응기에서 폐 EPS(Expanded polystyrene)의 열분해를 통한 스티렌모노머(SM) 전환 최적 조건 도출에 관한 연구
노영훈(Young-Hoon Noh),박주형(Ju-Hyoung Park),락와더르지(Lkhagvadorj Sh),송규섭(Gyu-Seob Song),김진성(Jin-Seung Kim),최영찬(Young-Chan Choi),최종원(Jong-Won Choi),박세준(Se-Joon Park),송광호(Kwang-Ho Song),이영주(Young-Joo Lee) 한국열환경공학회 2022 열환경공학 Vol.17 No.2
As the use of plastics becomes more common, the generation of waste plastics increases, and soil and air pollution problems are intensifying accordingly. To reduce this problem, the importance of plastic recycling is emphasized, and among them, a chemical recycling method using a pyrolysis process is the most effective in terms of recovering raw materials and reducing waste sources. Among various plastics, polystyrene has the highest monomer yield during pyrolysis and is one of the promising options because it is converted into a monomer with only a simple heat treatment. In this study, pyrolysis of waste EPS, which accounts for a significant amount of polystyrene, was performed using a batch reactor. Also, Temperature and catalyst conditions were diversified to select optimal conditions. As a result of the pyrolysis experiment, when the BaO catalyst was used at 390°C, the generated oil and SM mass showed the maximum value (Oil 33.2g, SM 19.27g), and this was selected as the optimal waste EPS recycling condition.
바이오매스(호두껍질) 혼소에 대한 연소 특성에 관한 연구
김진호(Jin-Ho Kim),이병화(Byoung-Hwa Lee),락와더러지(Lkhagvadorj Sh),김상인(Sang-In Kim),전충환(Chung-Hwan Jeon) 대한기계학회 2015 大韓機械學會論文集B Vol.39 No.1
본 연구에서는 발전소의 혼합연료로서 바이오매스인 호두껍질(Walnut Shell)에 대한 연소특성을 조사하기 위하여 열중량 분석기(TGA)와 분류층 반응기(DTR)를 이용하여 실험을 수행하였다. 바이오매스 WS는 기존 석탄과 비교하여 낮은 온도 영역에서 활발한 연소반응을 보였고, 활성화 에너지 또한 낮은 값을 가짐으로써 연소반응속도가 더욱 증가함을 확인할 수 있었다. 바이오매스 WS와 역청탄의 혼소에 있어서 고정층 분석에서는 혼소 영향이 선형적으로 나타나는 것을 확인할 수 있었다. 그렇지만 분류층 반응기에서는 바이오매스 혼소율을 5%증가 시에는 UBC가 감소하다가 이후에 다시 UBC가 증가하는 Non-additive 현상을 확인할 수 있었다. 이는 바이오매스의 급격한 연소로 주위에 산소 부족현상이 생겨 석탄의 연소가 지연되는 것을 보여준다. 이 현상을 해결하기 위하여 산소를 증가시켜주었을 때 더 높은 혼소율을 성취할 수 있음을 보여주었다. Combustion characteristics for co-firing of biomass (Walnut Shell) as blending fuel in coal fired boiler have investigated using thermogravimetric analyser (TGA) and drop tube reactor (DTR). The results show that devolatilization and char combustion for WS occurs at lower temperature than those of existing coals and has lower activation energy value, which is resulting in higher reactivity. When the WS is blended with coal, TGA results show linear profiles depending on blending ratio for each fuel. However, DTR results exist the non-additive phenomena for blending of WS. As blending ratio of WS increase, the UBC decrease at BBR 5%, but the UBC rather increase from BBR 10% due to oxygen deficiency formed from rapid combustion of WS. This paper propose that fuel lean condition by oxygen rich lead to higher blending ratio of biomass by solving the oxygen deficiency condition.