• Journal of the Korean Wood Science and Technology
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• v.44 no.5
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• pp.685-694
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• 2016

In this study, the thermal degradation behavior of biomass during torrefaction was studied by thermogravimetric and byproduct gas analysis. Torrefaction temperature, time, and heating rate were $220{\sim}300^{\circ}C$, 110 min, and $10{\sim}30^{\circ}C/min$, respectively. The degradation rate of yellow poplar was 8.01~8.81% at $220^{\circ}C$ and 71.86~77.38% at $300^{\circ}C$ depending on heating rate. The degradation rate significantly increased at temperature over $240^{\circ}C$. On the other hand, degradation rate of larch was relatively low as 49.58~54.15% at $300^{\circ}C$. The activation energy of yellow poplar was 87.32~91.24 kJ/mol; these values did not significantly change with heating rate. The activation energy of larch was 83.85~91.60 kJ/mol. The major components of the gas generated during torrefaction were derived from hemicellulose. The component types and concentrations increased with torrefaction severity. High concentrations of furfural and acetic acid were detected during torrefaction of yellow poplar.

• 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.

• 한국연소학회:학술대회논문집
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• 2012.11a
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• pp.205-206
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• 2012

A novel torrefaction process is suggested to improve energy efficiency and to produce high quality biomass fuel. Major developments for novel torrefaction process are as follows. 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 is developed and it can be runned with fuel rich state. To use the calorific gases produced from torrefier, another burner is developed to combust them. In the test, the novel torrefaction process leads low energy consumption and the quality of torrefied fuel becomes better.

• 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.

• 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 Society of Agricultural Engineers
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• v.59 no.5
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• pp.17-23
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• 2017

In South Korea, 25 % of annual agricultural residues (11.64 million tons) are unused. The hydrophilicity, low lower heating value (LHV), and low energy density of agricultural residues can be obstacles for efficient usage. Torrefaction, a low temperature pyrolysis process, can be a solution to overcome these disadvantage of agricultural residues. In this study, agricultural residues such as bean stem, pepper stem, perilla stem, sorghum stem, acorn shell, and ginkgo shell are torrefied at 200, 230, and $250^{\circ}C$ and evaluated energy properties, respectively. The torrefaction can increase the LHV and energy density rate of agricultural residues from 3,331~4,444 kcal/kg to 4,166~5,830 kcal/kg and 20~30 %, respectively.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.46 no.1
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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.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.1
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• pp.81-89
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• 2018

Fuel blend technique is one of the most effective way of using biomass to replace the coal. Many studies on combustion characteristics with coal and biomass blends have been conducted. In this study, char reactivity and emission characteristics of coal (Suek) and biomass (EFB) blends has been investigated by TGA and DTF to evaluate the applicability of the pre-treated (torrefaction, ash removal technology) EFB to pulverized coal boiler. In all blending cases, char reactivity improved as the blending ratio increases (10, 20, and 30%), especially torrefied EFB blended at 30%. Also, unburned carbon decreased as the blending ratio increases in all types of EFB. NOx emission showed the increase and decrease characteristics according to the content of fuel-N of raw EFB and torrefied EFB. But the amount of NOx emission at ashless EFB blends is greater than that of Suek despite of lower fuel-N. It indicated that co-firing effect of using the pretreatment biomass fuel is relatively better than those of the untreated biomass fuel about char reactivity and emission characteristics.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.47 no.1
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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.

• Korean Chemical Engineering Research
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• v.55 no.3
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• pp.395-400
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• 2017

Coke strength was increased by adding ash-free coal (AFC) binder. In this study, the effect of the AFC binder on the physical and chemical properties of coke was experimentally investigated to understand the molecular mechanism for the improved coke strength. For reduced $CO_2$ emission in steelmaking industry, torrefied biomass fuel mixed with coal binder is also considered. The interface between the base coal and AFC was thus examined using Scanning Electron Microscope (SEM). The coke strength was commonly measured by performing the indirect tensile test and Nuclear Magnetic Resonance (NMR) spectroscopy in $^1H$ and $^{13}C$ modes. For comprehensive mechanism study of the enhanced coke strength thus obtained, ordinary coal for thermal power plant use was carbonized with AFC for subsequent SEM examination. The NMR spectroscopy results of coke samples positively revealed that the tensile strength was proportional to the average number of aromatic rings.