• 한국연소학회지
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• 제19권3호
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• pp.8-17
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• 2014

The aims of this research were to evaluate effects of biomass co-firing to pulverized coal power plants and the variation of co-firing ratios on the plant efficiency related to power consumption of auxiliary system and flue gas characteristics such as production and component by process simulation based on the existing pulverized coal power plant. In this study, four kinds of biomass are selected as renewable fuel candidates for co-firing: wood pellet(WP), palm kernel shell(PKS), empty fruit bunch(EFB) and walnut shell(WS). Process simulation for various biomass fuels and co-firing ratios was performed using a commercial software. Gas side including combustion system and flue gas treatment system was considering with combination of water and steam side which contains turbines, condenser, feed water heaters and pumps. As a result, walnut shell might be the most suitable as co-firing fuel among four biomass since when 10% of walnut shell was co-fired with 90% of coal on thermal basis, flue gas production and power consumption of auxiliary systems were the smallest than those of other biomass co-firing while net plant efficiency was relatively higher than those of other biomass co-firing. However, with increasing walnut shell co-firing ratios, boiler efficiency and net plant efficiency were expected to decrease rather than coal combustion without biomass co-firing.

• Journal of the Korean Wood Science and Technology
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• 제48권5호
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• pp.651-665
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• 2020

Hydrolysis of biomass for the production of fermentable sugar can be improved by the addition of surfactants. In pulp and paper mills, lignin, which is a by-product of the pulping process, can be utilized as a fine chemical. In the hydrolysis process, lignin is one of the major inhibitors of the enzymatic breakdown cellulose into sugar monomer. Therefore, the conversion of lignin into a biosurfactant offers the opportunity to solve the waste problem and improve hydrolysis efficiency. In this study, lignin derivatives, a biosurfactant, was applied to enzymatic hydrolysis of various lignocellulosic biomass. This Biosurfactant can be prepared by reacting lignin with a hydrophilic polymer such as polyethylene glycol diglycidylethers (PEDGE). In this study, the effect of biosurfactants on the enzymatic hydrolysis of pretreated sweet sorghum bagasse (SSB), oil palm empty fruit bunch, and sugarcane trash with different lignin contents was investigated. The results show that lignin derivatives improve the enzymatic hydrolysis of the pretreated biomass with low lignin content, however, it has less influence on the enzymatic hydrolysis of other pretreated biomass with lignin content higher than 10% (w/w). The use of biosurfactant on SSB kraft pulp can increase the sugar yield from 45.57% to 81.49%.

• 공업화학
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• 제22권3호
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• pp.296-300
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• 2011

본 연구에서는 열병합 발전소의 원료로서 목질계 바이오매스로 임목 부산물, 폐목재, 야자수 부산물, 야자수 껍질의 연소 특성을 조사하기 위하여 열중량 분석기를 이용하여 연소 실험을 수행하였다. 목질계 바이오매스의 비교군으로는 일반적인 석탄을 사용하였다. 열중량 분석기 결과로부터, 목질계 바이오매스의 연소는 석탄과 비교하여 낮은 온도인 $280^{\circ}C$에서 $420^{\circ}C$ 구간에서 가장 활발한 연소반응을 보였음을 확인 할 수 있었다. 열중량분석에 의하여 측정된 활성화 에너지에 있어서 임목 부산물은 석탄 및 기타 목질계 바이오매스와 비교하여 가장 낮은 활성화 에너지 값을 나타내었으며, 또한 목질계 바이오매스의 경우 석탄과 비교하여 연소반응속도가 크게 증가함을 확인 할 수 있었다. 이는 목질계 바이오매스의 높은 연소개시 속도를 보이는 것을 나타내며, 이러한 결과는 석탄과 비교하여 낮은 비등점의 휘발분을 많이 포함하는 목질계 바이오매스의 특성에 기인하는 것으로 판단된다.

• 펄프종이기술
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• 제46권1호
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• pp.18-28
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• 2014

Renewable Portfolio Standards(RPS) is a regulation that requires a renewable energy generated from eco-friendly energy sources such as biomass, wind, solar, and geothermal. The RPS mechanism generally is an obligatory policy that places on electricity supply companies to produce a designated fraction of their electricity from renewable energies. The domestic companies to supply electricity largely rely on wood pellets in order to implement the RPS in spite of undesirable situation of lack of wood resources in Korea. This means that the electricity supply companies in Korea must explore new biomass as an alternative to wood. Palm kernel shell (PKS) and empty fruit bunch (EFB) as oil palm wastes can be used as raw materials used for making pellets after their thermochemical treatment like torrefaction. Torrefaction is a pretreatment process which serves to improve the properties including heating value and energy densification of these oil palm wastes through a mild pyrolysis at temperature typically ranging between 200 and $300^{\circ}C$ in the absence of oxygen under atmospheric pressure. Torrefaction of oil palms wastes at above $200^{\circ}C$ contributed to the increase of fixed carbon with the decrease of volatile matters, leading to the improvement of their calorific values over 20.9 MJ/kg (=5,000 kcal/kg) up to 25.1 MJ/kg (=6,000 kcal/kg). In particular, EFB sensitively responded to torrefaction because of its physical properties like fiber bundles, compared to PKS and hardwood chips. In conclusion, torrefaction treatment of PKS and EFB can greatly contribute to the implement of RPS of the electricity supply companies in Korea through the increased co-firing biomass with coal.

• 펄프종이기술
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• 제47권1호
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• pp.24-34
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• 2015

Domestic companies supplying electricity must increase obligatory duty to use renewable energy annually. If not met with obligatory allotment, the electricity-supply companies must pay RPS (Renewable Portfolio Standards) penalty. Although the power plants using a pulverizing coal firing boiler could co-fire up to around 3 per cent with wood pellets mixed in with coal feedstock without any major equipment revamps, they recorded only about 60 per cent fulfillment of RPS. Consequently, USD 46 million of RPS penalty was imposed on the six power supplying subsidiaries of GENCOs in 2014. One of the solutions to reduce the RPS penalty is that the power supply companies adopt the co-firing of torrefied lignocellulosic biomass in coal plants, which may contribute to the use of over 30 per cent of torrefied biomass mixed with bituminous coals. Extra binder was required to form pellets using torrefied biomass such as wood chips, PKS (Palm Kernel Shell) and EFB (Empty Fruit Bunch). Instead of corn starch, 30, 50 and 70 per cent of Larix saw dusts were respectively added to the torrefied feedstocks such as Pinus densiflora chips, PKS and EFB. The addition of saw dusts led to the decrease of the calorific values of the pellets but the forming ability of the pelletizer was exceedingly improved. Another advantage from the addition of saw dusts stemmed from the reduction of ash contents of the pellets. Finally, it was confirmed that torrefied oil palm biomass such as PKS and EFB could be valuable feedstocks in making pellets through improved binding ability.

• 청정기술
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• 제23권1호
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• pp.73-79
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• 2017

기후 변화 대응을 위한 온실가스 감축 측면에서, 석탄화력발전소에서 바이오매스 사용량은 계속하여 증가되어 왔다. 파리 협정 이후 온실가스 감축 목표치가 더욱 구체화되면서 바이오매스 사용은 급격히 더 많아질 것으로 예상된다. 미분탄 석탄 화력발전에서 바이오매스 혼소시 가장 큰 문제점 중 하나는 바이오매스의 미분성이 석탄에 비해 훨씬 낮다는 것으로, 이를 해결하기 위해 가장 먼저 바이오매스의 미분성 측정 방법을 확립하는 작업이 필요하다. 석탄의 경우 HGI (hardgrove grindability index)측정 장치를 통해 분쇄도 측정이 가능하여 이를 표준으로 삼고 있지만, 바이오매스의 경우 표준 측정 방법이 확립되어있지 않다. 본 연구에서는 볼 밀과 입자 크기별 분포량을 이용한 석탄과 바이오매스의 분쇄 실험을 진행하였다. 실험에는 석탄 1종과 바이오매스 6종을 사용하였다. 분쇄시간에 따른 입자 분포량을 비교하고, $75{\mu}m$ 이하 입자 분포량으로 분쇄도를 평가하였다. 실험결과 반탄화 바이오매스 TBC (torrefied biomass chip)와 TWP (torrefied wood chip)는 발전용 사용적합 기준에 대해 대략적으로 70%의 값을 나타냈다. 다른 바이오매스들의 경우 반탄화 바이오매스와 비교했을 때 분쇄성이 훨씬 더 낮은 결과를 보였다. TBC와 TWP는 수분이 감소하고 섬유질 구조가 분해되는 반탄화 과정을 통해 분쇄가 향상되었다. 또한 분쇄도가 높은 반탄화 바이오매스가 소모전력이 낮게 측정되었다. 본 연구를 통해 바이오매스의 석탄화력발전 적용을 위한 표준화 작업의 기초 자료들을 확보할 수 있다.

• 펄프종이기술
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• 제48권2호
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• pp.34-45
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• 2016

Global warming and climate change have been caused by combustion of fossil fuels. The greenhouse gases contributed to the rise of temperature between $0.6^{\circ}C$ and $0.9^{\circ}C$ over the past century. Presently, fossil fuels account for about 88% of the commercial energy sources used. In developing countries, fossil fuels are a very attractive energy source because they are available and relatively inexpensive. The environmental problems with fossil fuels have been aggravating stress from already existing factors including acid deposition, urban air pollution, and climate change. In order to control greenhouse gas emissions, particularly CO2, fossil fuels must be replaced by eco-friendly fuels such as biomass. The use of renewable energy sources is becoming increasingly necessary. The biomass resources are the most common form of renewable energy. The conversion of biomass into energy can be achieved in a number of ways. The most common form of converted biomass is pellet fuels as biofuels made from compressed organic matter or biomass. Pellets from lignocellulosic biomass has compared to conventional fuels with a relatively low bulk and energy density and a low degree of homogeneity. Thermal pretreatment technology like torrefaction is applied to improve fuel efficiency of lignocellulosic biomass, i.e., less moisture and oxygen in the product, preferrable grinding properties, storage properties, etc.. During torrefacton, lignocelluosic biomass such as palm kernell shell (PKS) and empty fruit bunch (EFB) was roasted under an oxygen-depleted enviroment at temperature between 200 and $300^{\circ}C$. Low degree of thermal treatment led to the removal of moisture and low molecular volatile matters with low O/C and H/C elemental ratios. The mechanical characteristics of torrefied biomass have also been altered to a brittle and partly hydrophobic materials. Unfortunately, it was much harder to form pellets from torrefied PKS and EFB due to thermal degradation of lignin as a natural binder during torrefaction compared to non-torrefied ones. For easy pelletization of biomass with torrefaction, pellets from PKS and EFB were manufactured before torrefaction, and thereafter they were torrefied at different temperature. Even after torrefaction of pellets from PKS and EFB, their appearance was well preserved with better fuel efficiency than non-torrefied ones. The physical properties of the torrefied pellets largely depended on the torrefaction condition such as reaction time and reaction temperature. Temperature over $250^{\circ}C$ during torrefaction gave a significant impact on the fuel properties of the pellets. In particular, torrefied EFB pellets displayed much faster development of the fuel properties than did torrefied PKS pellets. During torrefaction, extensive carbonization with the increase of fixed carbons, the behavior of thermal degradation of torrefied biomass became significantly different according to the increase of torrefaction temperature. In conclusion, pelletization of PKS and EFB before torrefaction made it much easier to proceed with torrefaction of pellets from PKS and EFB, leading to excellent eco-friendly fuels.