• Journal of the Korean Wood Science and Technology
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• v.43 no.1
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• pp.122-134
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• 2015

This study was conducted to investigate the potential of torrefied larch wood as a raw material of pellets. First of all, larch chip was torrefied at the temperatures of 230, 250 and $270^{\circ}C$ for 30, 50 and 70 min. Secondly, moisture content, moisture absorption, higher heating value and ash content of the torrefied chip were measured to examine the effects of torrefaction conditions on the fuel characteristics of larch. Thirdly, surfaces of the torrefied chip were observed by light microscope (LM), field emission scanning microscope (FE-SEM) and SEM-energy dispersive spectroscopy (EDXS). With the increases of torrefied temperature and time, contents of lignin increased and those of hemicellulose reduced. Moisture content of torrefied larch chip was greatly lower than that of non-torrefied chip. Moisture absorption of the torrefied chip decreased as torrefaction temperature increased. As torrefaction temperature increased, higher heating value and ash content of larch chip increased. However, durability of torrefied-larch pellets was remarkably lower comparing to non-torrefied-larch pellets. When surface of larch chip was observed by LM and FE-SEM, surface color and cell wall of the chip was getting darker and more collapsed with the increases of torrefaction conditions. Through the analysis of SEM-EDXS, distribution and quantity of lignin existing on the surface of larch chip increased with the increases of torrefied conditions. In conclusion, $270^{\circ}C$/50 min might be an optimal condition for the torrefaction of larch with the aspect of fuel characteristics, but torrefaction condition of $230^{\circ}C$/30 min should be considered according to the durability of torrefied-larch pellets.

• New & Renewable Energy
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• v.9 no.3
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• pp.29-35
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• 2013

This research analyzed the fuel characteristic change of spent coffee bean by torrefaction. The calorific value was increased from 4,974 kcal/kg to 6,075 kcal/kg ($260^{\circ}C$, 30min), 6,452 kcal/kg ($270^{\circ}C$, 30min), 6,823 kcal/kg ($280^{\circ}C$, 30min), 6,970 kcal/kg ($260^{\circ}C$, 30min). The highest energy yield was obtained when the spent coffee bean were torrefied on the condition of $280^{\circ}C$, 30min. The moisture absorption rate was decreased from 5.12% to 2.76% when the spent coffee bean were torrefied on the condition of $290^{\circ}C$, 30min. Lignin was increased from 11.33% to 14.39% on the condition of $260^{\circ}C$ 30min. But it did not preferability to torrefy spent coffee bean at temperature of more than $270^{\circ}C$ because lignin decreases to the level that is hard to make pellet.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.375-378
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• 2014

In this study, we carried out torrefaction experiment using PKS(Palm Kernel Shell), and Bagasse as a raw material of oversee of herbaceous biomass and using waste wood and logging residue as a raw material of domestic of woody biomass. And then, by analyzing the physical & chemical properties, we investigated the characteristics as a fuel. By using the result of thermo gravimetric analysis, the biomass residue was torrefied for 30 minutes at a temperature range of $250-350^{\circ}C$ in anaerobic condition. As a result, torrefied materials of moisture content are lower than raw, but of fixed carbon, calorific value and ash are higher than raw.

• Journal of the Korean Wood Science and Technology
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• v.43 no.3
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• pp.381-389
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• 2015

In this study, the effects of moisture content and particles size of ground particles of torrefied larch chips on the pelletizing process were investigated depending on torrefaction conditions ($220^{\circ}C$-50 min, $250^{\circ}C$-50 min, $250^{\circ}C$-120 min). The moisture content in the torrefied chip decreased to 0.69~1.75%, while ash content and calorific value increased compared to untreated chip. In addition, weight loss significantly increased during torrefaction due to hemicellulose degradation. The carbon content in torrefied larch chip increased compare to untreated larch chip, while the hydrogen and oxygen contents decreased. The lignin and glucan contents in torrefied larch chip increased with increasing severity of the torrefaction condition, while hemicellulose decreased. In the particle size distribution of ground particles of torrefied larch chip, larch torrefied at severe conditions was found to produce smaller particles (~1 mm) than that of the larch torrefied at mild conditions. Macropore (over $500{\AA}$) in the torrefied particle was produced during torrefaction. During the pelletizing using ground particles of torrefied larch chip, the pressure needed in pelletizing decreased and pellet length increased with increasing moisture content, regardless of the particle size.

• Journal of the Korean Applied Science and Technology
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• v.36 no.2
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• pp.560-571
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• 2019

In the study, used torrefaction method to make sample from organic waste of livestock manure for Biomass-solid refuse fuel feasibility study of torrefied materials. Fallen leaves and sawdust added in torrefaction methods with livestock manure, that additives were used to improve the lower calorific value of livestock manure. During the torrefaction experiment, the reaction temperature was varied from $200^{\circ}C$ to $260^{\circ}C$ and $20^{\circ}C$ to prepare a sample. The reaction time was divided into 15, 30 and 45min to determine the effect of the experimental conditions on the torrified products. The additives were mixed at a ratio of 9:1 and 8:2 (Cow manure: additive) relative to the livestock manure. Through this experiment, it was obtained 3,500 kcal/kg standard product of solid fuel produced in Korea and improved product was obtained by adding additives.

• 한국연소학회:학술대회논문집
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• 2014.11a
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• pp.263-263
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• 2014

Low temperature pyrolysis of woody biomass has been conducted to produce highcalorie torrefied fuel. In this experiment, to maximize the energy efficiency in heat transfer, flue gas is directly used for heat source in the torrefier. To accomplish the oxygen free environment in the torrefaction reactor, a burner has been developed and it can be runned with fuel rich state. An inner central axis rotating type of reactor was applied in experiment. To use the calorific gases produced from torrefier, another burner is developed to combust them.

• Resources Recycling
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• v.30 no.4
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• pp.46-53
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• 2021

Biomass can be considered as chemical energy obtained from nature, and includes all living organisms such as plants, animals, and microorganisms. Biomass is eco-friendly, is easily obtainable from the environment, and can be recycled without special treatment processes. Biomass can also be converted into bioenergy fuel through pyrolysis and fermentation. Therefore, it has been considered as a renewable energy source, which prevents the depletion of natural resources such as fossil fuels. In this study, torrefaction to increase the carbon content in various types of biomass sources (sawdust, rice straw, rice bristles, coffee ground, and waste wood) was conducted under an inert atmosphere and at a temperature of 523~573K. The possibility of using torrefied biomass as an alternative to solid fuel for industrial purposes was analyzed by examining the carbon concentration and combustion behaviors.

• Journal of Energy Engineering
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• v.23 no.3
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• pp.235-240
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• 2014

In this study, the torrefaction of food waste was conducted to characterize its product, to find out effect of the operating temperature and to assess the feasibility of being used as fuel. The operating temperature was varid from $180^{\circ}C{\sim}270^{\circ}C$ and heat was provided by using nitrogen gas or waste oil heat carrier. The solid yield and moisture content were reduced were reduced as temperature increased. The moisture content reduction and thermochemical conversion were observed at higher than $240^{\circ}C$. At low operating temperature, heat transfer efficiency was higher with wast oil heat carrier. As temperature increases, there was not difference in heat transfer efficiency of two different heating methods. The lower heating value product was increased from 660 to 6,400 Kcal/kg with nitrogen gas and 6,890 Kcal/kg with waste oil heat carrier. The elemental analysis indicates that, as temperature increases, the carbon content of product increases and oxygen content decreases. From the analysis of O/C and H/C, the torrefaction product was close to low grade coal. The characteristics of fuel converted from the food subsequent thermochemical treatment.

• KEPCO Journal on Electric Power and Energy
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• v.2 no.4
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• pp.525-529
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• 2016

Biomass co-firing to existing thermal power plants is one of the most economical and efficient way to reduce $CO_2$ emission from the plant. There are several methods of co-firing and it can be categorized into (1) Parallel co-firing, (2) Indirect co-firing, and (3) Direct co-firing. Parallel co-firing is the most expensive way to high-ratio co-firing because it requires biomass dedicated boiler. Direct co-firing is widely used because it does not need high capital cost compared with the other two methods. Regarding the direct co-firing, it can be classified into three methods- Method 1 does not need retrofit of the facilities because it uses existing coal mills for pulverizing biomass fuels. In this case high-ratio co-firing cannot be achieved because of poor grindability of biomass fuels. Method 2 needs biomass-dedicated mills and revision of fuel streams for the combustion system, and Method 3 needs additional retrofit of the boiler as well as biomass mills. It can achieve highest share of the biomass co-firing compared with other two methods. In Korea, many coal power plants have been adopting Method 1 for coping with RPS(Renewable portfolio standards). Higher co-firing ratio (> 5% thermal share) has not been considered in Korean power plants due to policy of limitation in biomass co-firing for securing REC(Renewable Energy Certificate). On the other hand, higher-share co-firing of biomass is widely used in Europe and US using biomass dedicated mills, following their policy to enhance utilization of renewable energy in those countries. Technical problems which can be caused by increasing share of the biomass in coal power plants are summarized and discussed in this report. $CO_2$ abatement will become more and more critical issues for coal power plants since Paris agreement(2015) and demand of higher share of biomass in the coal power plants will be rapidly increased in Korea as well. Torrefaction of the biomass can be one of the best options because torrefied biomass has higher heating value and grindability than other biomass fuels. Perspective of the biomass torrefaction for co-firing is discussed, and economic feasibility of biomass torrefaction will be crucial for implementation of this technology.

• Journal of the Korea Organic Resources Recycling Association
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• v.26 no.2
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• pp.75-84
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• 2018

In this study, the analysis of torrefaction products was carried out for fueling of sewage sludge. The mixed samples were composed as follows : 50% of sewage sludge and 50% of rice husk and CR(Coffee Residue). In this experiment, the reaction time(30min, 60min) and temperature($200^{\circ}C$, $250^{\circ}C$, $300^{\circ}C$) were expressed as a single variable using SF(Severity Factor). As a result, it was confirmed that as the SF increased, the heating value and fuel ratio increased, but the CI(Combustibility Index) decreased. The heating value was similarly increased as CR(Coffee Residue) and SF increased. The fuel ratio range of mixed samples was equal to that of lignite(0.5~1.0) in case of SF lower than 6.19 and that of bituminous coal(1.0~1.8) in case of SF higher than 7.36 or above. The CI showed a stable range(3,000~5,500kcal/kg) in low SF as the content of mixed samples contained more rice husk than CR.