• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.39 no.8
• /
• pp.683-691
• /
• 2015

Circulating Fluidized Bed(CFB) combustion has the several advantages which are the fuel flexibility, the economy, the efficiency and the environment. It is necessary to apply a renewable energy to produce electricity due to the Renewable Portfolio Standard(RPS) mandates recently. So, in this study, co-combustion with a coal and a wood pellet was investigated to evaluate the combustibility and the environment as function of blending ratio of them in a Lab-scale CFB reactor. To investigate the characteristics of the co-combustion, the blending ratio which is the weight of wood pellet by the total calorific value of the supplied, was considered. Bed material was a river sand(No. 7). As increasing the blending ratio, the exhausted gas emissions such as CO, NOx, HC and SOx were decreased. But in case of wood pellet over 30%, CO, HC and SOx emission were increased. And the gas temperatures at the downstream were decreased.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.4
• /
• pp.590-596
• /
• 2019

Uses of fossil fuels like coal and oil increases with industrial development, and problems like abnormal climate come up as greenhouse gas increases. Accordingly, studies are actively conducted on eco-friendly renewable energy as a replacement for the main resources, and especially, wood pellets with high thermal efficiency are in the limelight as an alternative fuel in thermal power stations and gas boilers. However, despite a constant increase in their usage, few studies are conducted on their risks like fire and spontaneous combustion. Thus, this study found the auto-ignition temperature and critical ignition temperature of wood pellets with a change in flow rate in a thermostatic bath, using a sample vessel with 20 cm in length, 20 cm in height and 14 cm in thickness to predict their ignition characteristics. Consequently, at the flow rate of 0 NL/min, as the core temperature of the sample increased to higher than the ambient temperature, they ignited at $153^{\circ}C$, when the critical ignition temperature was $152.5^{\circ}C$. At the flow rates of 0.5 NL/min and 1.0 NL/min, it was $149.5^{\circ}C$, and at the flow rate of 1.5 NL/min, it was $147.5^{\circ}C$. Consequently, at the same storage, the more the flow rate, the lower the critical ignition temperature became.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.63 no.1
• /
• pp.64-71
• /
• 2018

To improve the soil of reclaimed land, we added organic materials at a level of 3,000 kg/10 a. As a result, the electrical conductivity (EC) value of reclaimed soil decreased by 58%, the organic material content increased from 6.7 to 16.0 g/kg, the porosity increased from 1.57 to 1.31%, the soil hardness decreased from 20.2 to 17.9 mm and the plow layer was deepened from 19.8 to 26.8 cm. After these physiochemical improvements to the reclaimed soil, the growth phase of crops was improved compared to that of non-treatment crops. The height of kenaf (Hibiscus cannabinus L.) cultivated in the reclaimed land containing organic materials was increased by 18.8%. Especially, the improvement effects of pellet type manure compost and rice straw on kenaf were more preferable than those of other organic materials. When the kenaf was cultivated in the reclaimed land containing organic materials, the yield increased. The average yield of the treatment crops was 9,218 kg/10 a, 2.1 times higher than that of non-treatment crops. The most effective treatments to increase the yields were pellet type manure compost (10,848 kg/10 a, 148% increase), rice straw (120% increase) and chopped kenaf (95% increase). To increase the physicochemical enhancements to the reclaimed land soil and most improve yields, the most effective type of organic materials was the pellet. The organic material types that maintained a better growth phase and most increased the yield were the liquid and pellet types. When we used pellet type organic material, the plant height of kenaf was increased by 41% in comparison with that of the non-treatment crops and yield was increased by more than 122%. Additionally liquid type organic material improved the yield (by 127%).

• Journal of the Korean Wood Science and Technology
• /
• v.43 no.3
• /
• pp.374-380
• /
• 2015

The quality characteristics of the woodpellet manufactured from two domestic pines (Pinus densiflora S. et Z. and Pinus rigida Mill.) were investigated for the efficient energy use of woody biomass resources. Properties of woodpellets such as moisture content, heating value, ash content, apparent density and durability were determined by using the standard test method of woodpellets of Korea Forest Research Institute (KFRI) and elemental analysis. The results of elemental analysis for C, H, O and N showed 61.42% carbon, 5.56% hydrogen, 32.87% oxygen, and 0.15% nitrogen for Pinus densiflora S. et Z. and 61.03% carbon, 5.96% hydrogen, 32.83% oxygen, and 0.18% nitrogen for Pinus rigida Mill. No significant difference between Pinus densiflora S. et Z. and Pinus rigida Mill was observed on elemental analysis. Heating values of each woodpellet were ranged from 19.00 to 19.42 MJ/kg which satisfied the first grade quality standard (${\geq}18.0MJ/kg$) by KFRI. The ash contents of woodpellet were slightly different between Pinus densiflora S. et Z. and Pinus rigida Mill., and satisfied the first grade quality standard (${\leq}0.7%$) by KFRI. Apparent density of woodpellet (Pinus densiflora S. et Z.) was passed the first grade standard level (${\geq}640kg/m^3$), and woodpellets from Pinus rigida Mill. satisfied the second grade quality of the standard. The moisture contents of each woodpellet were satisfied by the first grade quality standard (${\leq}10%$). The durability of woodpellet (Pinus densiflora S. et Z.) was passed the third grade level (${\geq}95%$), but Pinus rigida Mill. woodpellet was insufficient to satisfy the quality standard.

• Monthly Korean Chicken
• /
• v.18 no.9
• /
• pp.104-108
• /
• 2012

• Journal of computational fluids engineering
• /
• v.13 no.4
• /
• pp.50-57
• /
• 2008

The prediction of hydrate pellet decomposition characteristics is required to design the regasification process of GTS (gas to solid) technology, which is considered as an economic alternative for LNG technology to transport natural gas produced from small and stranded gas wells. Mathematical model based on the conservation principles, the phase equilibrium relation, equation of gas state and phase change kinetics was set up and numerical solution procedure employing volume averaged fixed grid formulation and extended enthalpy method are implemented. Initially, porous methane hydrate pellet is at uniform temperature and pressure within hydrate stable region. The pressure starts to decrease with a fixed rate down to the final pressure and is kept constant afterwards while the bounding surface of pellet is heated by convection. The predicted convective heat and mass transfer accompanied by the decomposed gas flow through hydrate/ice solid matrix is reported focused on the comparison of spherical and cylindrical pellets having the same effective radius.

• 한국신재생에너지학회:학술대회논문집
• /
• 2008.05a
• /
• pp.221-224
• /
• 2008

We made densified wood pellet by hemp woody core as replacing wood resource. Hemp was separated into the bast fiber and the woody core by hot steaming treatment. The hemp woody core had a similar lignin content and carbohydrate composition with hardwood. Also, the hemp had a low ash content, which resulted in a low ash formation in pellet burning. Heating value of the hemp pellet had a very similar to the pellet made by hardwoods. The hemp woody core can replace hardwood for densified wood pelletmaking.

• 한국신재생에너지학회:학술대회논문집
• /
• 2006.11a
• /
• pp.521-524
• /
• 2006

Recently, densified pollet fuel from wood biomass is widely used at North America and Europe as a regenerable and clean carbon neutral bioenergy. High-pressure compaction of sawdust of several species of wood to form a densified fuel was studied. Calorific and elemental analysis were carried out to assess pellet fuels Hot-press process was adopted for compact ion of sawdust and compaction was performed under prescribed condition. Densified fuels were evaluated by its oven-dry density and fines after 5-minute shaking test. The target density and fines of densified fuels were over $1.2g/cm^3$ and below 0.5%, respectively. When the press-temperature is over $60^{\circ}C$ densified fuels with density over $1.2g/cm^3$ and with fines below 0.5% can be produced. And the pressure over $1000kgf/cm^2$ was effect ive for this production.

• Resources Recycling
• /
• v.2 no.4
• /
• pp.10-16
• /
• 1993

Reduction behavior of stainless steelmaking dust by microwave heating process was investigated using coke and charcoal as reducing agents. Pellet dust and stanless steelmaking dust pelletized with reducing agent were reduced by the heating upto $1000^{\circ}C$ in microwave oven. The results showed that charcoal and coke seemed effective in the reduction of metals from stainless steelmaking dust by microwave heating and charocal was found to be better than coke. Degree of reduction seemed similar with the power of 500W and 700W in microwave oven. Dusts were rapidly reduced within 20 minutes. Reducing degree decreased in the order of Fe>Ni>Cr.

• 한국전산유체공학회:학술대회논문집
• /
• 2008.03a
• /
• pp.268-275
• /
• 2008

The prediction of hydrate pellet decomposition characteristics is required to design the regasification process of GTS (gas to solid) technology, which is considered as an economic alternative for LNG technology to transport natural gas produced from small and stranded gas wells. Mathematical model based on the conservation principles, the phase equilibrium relation, equation of gas state and phase change kinetics was set up and numerical solution procedure employing volume averaged fixed grid formulation and extended enthalpy method are implemented. Initially, porous methane hydrate pellet is at uniform temperature and pressure within hydrate stable region. The pressure starts to decrease with a fixed rate down to the final pressure and is kept constant afterwards while the bounding surface of pellet is heated by convection. The predicted convective heat and mass transfer accompanied by the decomposed gas flow through hydrate/ice solid matrix is reported focused on the comparison of spherical and cylindrical pellets having the same effective radius.