• Journal of the Korean Wood Science and Technology
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• 제51권5호
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• pp.381-391
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• 2023

Densification is a technique used to improve biomass quality in wood pellet manufacturing and torrefaction treatment. In this study, the effects of torrefaction on the quality of Calliandra wood pellets were investigated, and pellets of Calliandra wood (Calliandra calothyrsus) and bark were evaluated. The study was conducted using a completely randomized design with two treatment factors, namely torrefaction temperature (250℃ and 300℃) and torrefaction duration (30, 45, and 60 min). The results showed that the interaction between temperature and torrefaction duration significantly affected the compressive strength, proximate value, and calorific value of the torrefied Calliandra wood pellets. An increase in the temperature and torrefaction duration decreased the compressive strength, moisture content, volatile matter content, and ash content of the torrefied Calliandra wood pellets. Conversely, the calorific value of Calliandra wood pellets increased with increasing temperature and torrefaction duration. The best-quality Calliandra wood pellets were produced at a torrefaction temperature and duration of 300℃ and 60 min, respectively. In terms of important quality parameters, ash content of 0.90% and calorific value of 6,303.80 cal/g were observed, which complied with the quality standards of Indonesian National Standard 8675:2018 and Deutsche Industrie Norm 51731.

• 한국농공학회논문집
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• 제56권6호
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• pp.55-62
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• 2014

Torrefaction is considered as a promising pre-treatment for thermochemical utilization of biomass. Torrefaction temperature and time are the critical operation parameters. In this study, investigated were the effects of reaction temperature and time on product composition of torrefaction. scanning electron microscope (SEM) images and thermo gravimetric analyzer (TGA) results were also compared for the effects of the operating parameters. SEM images showed that the pores were observed at the temperature of $250^{\circ}C$ for 30 minutes. Rapid decreases in weight were observed the temperature between 200 and$400^{\circ}C$. Higher heating value of the torrefied biomass was over 5,000 kcal/kg at the temperature of $250^{\circ}C$ for 45 minutes. Energy density, which is defined as the ratio of the energy yield over the mass yield was 1.36 at the temperature of $250^{\circ}C$ for 45 minutes. The energy density was higher up to 1.6 at the temperature of $280^{\circ}C$, which indicates greater loss in mass. The major components of the gas produced in the torrefaction were $CO_2$ and CO, with traces of methane. The total amount of gas was 31.54 l/kg and the calorific value of the gas was $1,164.4Kcal/Nm^3$ at the temperature of $250^{\circ}C$ for 30 minute reaction time. Based on the results of this study, the temperature of effective torrefaction is about $250^{\circ}C$ for 30 to 45 minutes of reaction time. Considering the heating value, it is desirable to utilize the gas for efficient process of torrefaction.

• Korean Chemical Engineering Research
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• 제52권5호
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• pp.672-677
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• 2014

반탄화는 $200{\sim}300^{\circ}C$의 불활성분위기에서 바이오매스를 전처리하는 열처리공정이며 이러한 반탄화 공정은 바이오 매스에 함유된 섬유질성분의 분해온도에 크게 영향을 받은 것으로 알려져 있다. 본 연구에서는 사탕수수 부산물의 반탄화 특성에 관한 연구를 수행하였으며 반탄화 온도 및 반탄화 시간에 따른 에너지 수율, 발열량 및 발생가스 그리고 가연분과 회분의 관계에 중점을 두었다. 또한 본 연구에서는 TGA(Thermogravimetric Analyzer)를 이용한 사탕수수 부산물의 반탄화 반응에 대한 활성화 에너지의 변화도 함께 고찰하였다. 본 연구로부터 반탄화 온도에 따라 회분 및 발열량은 증가하였으나 가연분 및 에너지 수율은 감소하였으며 또한 산소성분을 함유한 일산화탄소가 탄화수소 화합물, $C_xH_y$ 보다 더 낮은 온도에서 분해되기 시작하는 것을 확인할 수 있었다.

• Korean Chemical Engineering Research
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• 제51권4호
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• pp.465-469
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• 2013

본 연구는 반탄화된 OPF(oil palm fronds)의 연료로써 이용가능성을 알아보았다. OPF는 200, 250, 300, $350^{\circ}C$에서 각각 1시간과 2시간 동안 반탄화를 진행하였다. 반탄화된 OPF는 온도가 높아짐에 따라 그리고 반탄화 시간이 증가됨에 따라 발열량이 증가하였다. 또한, 반탄화 시간보다는 반탄화 온도가 더 중요한 요소였다. 하지만 반탄화 온도가 높아질수록 반탄의 수득률이 감소함으로 적절한 반탄화 온도가 요구되었다. $250^{\circ}C$에서의 반탄화로는 헤미셀룰로오스의 분해가 상당히 진행되고 $300^{\circ}C$에서는 셀룰로오스의 분해까지도 거의 진행됨을 OPF의 열분해 거동으로부터 알 수 있었다. 또한, 반탄화된 OPF는 바이오매스의 grindability를 향상시킴으로 분쇄에 소모되는 에너지를 감소시킴을 예측할 수 있었다.

• Journal of Biosystems Engineering
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• 제38권3호
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• pp.180-184
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• 2013

Purpose: This study explored the factors influencing heating value in the process of torrefaction of water hyacinth. Methods: Torrefaction was applied with three temperature settings (200, 300, $400^{\circ}C$) and three time settings (1, 2, 3 h) using small electric heaters (11.3L of holding volume). This study investigated the heating values with the washing process and process factors influenced the torrefaction. In addition, this study compared the heating values in washed and unwashed samples and suggested the optimal conditions for increasing heating value. Results: Torrefaction increased the heating value by 8.18 ~ 30.04%. Comparing heating values of each condition, the optimal temperature for torrefaction was $300^{\circ}C$ and holding time was 1 hour. The washing process increased the heating value by 19 ~ 27%. The heating value of the sample treated at $300^{\circ}C$ for three hours was 4310.80 kcal/kg, which was greater than the first class wood pellet of 4300 kcal/kg. Conclusions: This study proved that the torrefaction and washing process increased the heating value of water hyacinth. Therefore, water hyacinth is expected to be an eco-friendly biomass which substitutes for wood pellet.

• 한국수소및신에너지학회논문집
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• 제28권6호
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• pp.683-690
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• 2017

Wood pellet (WP), empty fruit bunch (EFB) and palm kernel shell (PKS) which are biomass fuels for power generation are selected to study the characteristics of torrefaction process. These biomass fuels are torrefied at $220^{\circ}C$, $250^{\circ}C$, and $280^{\circ}C$. The heating value of biomass fuels is increased depending on the torrefaction temperature. However, due to energy yield decline, it is not always desirable to torrefy biomass at higher temperature. Considering the mass yield and energy yield after torrefaction, the most proper temperature conditions for torrefaction of WP is $250-280^{\circ}C$ and for EFB, PKS are $220-250^{\circ}C$. Additionally, to investigate the phenomenons of chlorine release during torrefaction process, Ion Chromatography (IC) method was used. In the case of EFB and PKS torrefied at $300^{\circ}C$, the chlorine component has been reduced by 97.5% and 95.3% compared to the raw biomass, respectively. In conclusion, torrefied biomass can be used as alternative fuels in replacement of coals for both aspects of heating value and chlorine corrosion problems.

• Journal of the Korean Wood Science and Technology
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• 제43권2호
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• pp.196-205
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• 2015

The aim of this study was to evaluate the fuel characteristics of thermally treated wood chips of the Larix kaempferi C. As torrefaction temperature was increased ($200^{\circ}C$ to $300^{\circ}C$), the carbon content, calorific value, and mass loss of torrefied wood chips increased significantly. The torrefied wood chips were shown to have hydrophobic properties even when only treated by mild torrefaction. The energy required to grind torrefied wood chips was reduced by the torrefaction process. Different sizes of wood chips were used in this study; however, this produced almost no difference in the fuel characteristics of processed Larix kaempferi C, except in the distribution of ground wood particles. Similar results were observed when the wood chips were torrefied for different lengths of time (15 min to 60 min) at a constant temperature. Torrefaction was shown to have positive effects on the fuel characteristics of Larix kaempferi C, including improved energy density, storage, and grindability.

• 공업화학
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• 제25권5호
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• pp.510-514
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• 2014

본 연구에서는 고형연료로써의 에너지 잠재성을 평가하기 위하여 하수슬러지의 기본특성에 대한 반탄화의 영향을 고찰하였으며, 이를 위하여 $150{\sim}600^{\circ}C$의 온도조건에서 하수슬러지의 반탄화 실험을 수행하였다. 반탄화된 하수슬러지는 에너지 수율, 회분, 가연분 및 고위발열량에 의하여 분석되었으며, 반탄화 과정에서 발생되는 가스성분 또한 분석하였다. 또한 본 연구에서는 하수슬러지의 반탄화 반응에 대한 속도론적 해석을 위하여 열중량 분석을 수행하였다. 본 연구로부터 반탄화 온도가 증가함에 따라 회분함량은 증가하는 반면에 에너지 수율, 고위발열량 및 가연분은 감소하는 것으로 나타났으며, 또한 $300^{\circ}C$에서 하수슬러지 내에 함유된 가연성 성분의 열분해로 인하여 일산화탄소 및 탄화수소 가스가 발생하기 시작함을 확인할 수 있었다.

• 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.

• 신재생에너지
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• 제9권4호
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• pp.40-50
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• 2013

This study was performed to investigate the potential of torrefied tulip tree (TT) for the production of pellets. For this purpose, chemical composition and fuel characteristics of torrefied TT were examined. In addition, pellets were fabricated by using sawdust of torrefied TT chip, and durability of the pellet was measured. Lignin content of torrefied TT was higher than that of non-torrefied TT, and increased with the increases of torrefaction temperature and time. Fuel characteristics of torrefied TT were affected by torrefied conditions, and the characteristics were influenced more by torrefaction temperature than by torrefaction time. Higher heating value (HHV) and ash content (AC) of torrefied tulip tree increased with increasing torrefaction temperature, and the values were much higher than HHV and AC values of non-torrefied TT. Durability of pellets fabricated with $230^{\circ}C$- and $250^{\circ}C$-torrefied TT was higher than that of $270^{\circ}C$-torrefied TT, and the value exceeded the minimum requirement (-97.50%) of the 1st-grade pellet standard designated by Korea Forest Research Institute. Based on the results, torrefaction treatment of $250^{\circ}C/50min$ to TT might be a optimal condition for the production of TT pellets considering the mass balance and fuel characteristics of TT as well as the durability of the pellets. Thus, it is confirmed that torrefied TT can be used as a raw material for the production of bio-pellets.