• Journal of the Korean Society of Tobacco Science
• /
• v.26 no.2 s.52
• /
• pp.117-125
• /
• 2004

In this study, we have investigated the natural and puffing combustibility of cigarette brands and the compulsory ash-drop, and analysed factors related to the materials. Cigarette combustibility was greatly affected by the tobacco weight in cigarettes rod. Combustion rate of 4AOR cigarette made by flue-cured tobacco was 5.02 $^{mm}/_{min}\;and\;10\%$ faster than 1BO cigarette. Combustion pattern has interrelation with sugars, chlorine and ash contents among tobacco components. Combustion rate of 4DL, flue-cured tobacco was 55 seconds faster than 1CL tobacco extremely much in sugars contents, and ash drop was maintained at $21\%$ longer. Combustion time and burning rate were fast in cigarette made by expanded tobacco slice and tobacco stem and the formation of ash was poor. The length of puffed ash drop of expanded tobacco slice and tobacco stem were 18.6 mm and 25.2 mm and these forced ash drop length were 3.8 mm and 4.9 mm respectively. Puffed burning rate of general cigarette was $14.3\%$ faster than static burning rate and super slim type cigarettes was $21.3\%$ faster. Combustion rate and ash drop of domestic and foreign cigarette brands were quite different depending on tar level and cigarette types. The lower tar level, the faster combustion rate and the shorter ash drop.

• 한국연소학회:학술대회논문집
• /
• 2012.04a
• /
• pp.341-342
• /
• 2012

The effect of high ash coal which has relatively high ash content and low combustibility on unburned carbon and NOx emission was experimentally investigated at several excess air ratio and particle size conditions of four coals containing different ash content in a drop tube furnace. Flue gas was measured by Gas analyzer in order to figure out unburned carbon characteristics. The results show that the higher content of ash makes the higher unburned carbon rate, subsequent changes in NOx emission characteristics was investigated.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.37 no.4
• /
• pp.405-413
• /
• 2013

The char oxidation characteristics of high ash coal were experimentally investigated at several temperatures (from 900 to $1300^{\circ}C$) for 4 types of coals (Gunvor, Glencore, Noble, and ECM) under atmospheric pressure in a drop tube furnace (DTF). The char reaction rate was calculated from the exhaust gas concentrations (CO and $CO_2$) using FT-IR, and the particle temperature was measured using the two-color method. In addition, the activation energy and pre-exponential factor for high ash coal char were calculated based on the Arrhenius equation. The results show that as the ash content increases, the particle temperature and area reactivity decreases. This is because in high ash coal, the large heat capacity of the ash, ash vaporization, and relatively low fixed carbon content of ash suppress combustibility during char oxidation. As a result, the higher ash content of coal leads to high activation energy.

• Clean Technology
• /
• v.26 no.1
• /
• pp.22-29
• /
• 2020

Recently, as the fine dust is increased and the emission regulations of diesel engines have been tightened, interest in diesel soot filtration devices has rapidly increased. There is specifically a demand for the technological development of higher diesel exhaust gas after-treatment device efficiency. As part of this, many studies were conducted to increase exhaust gas treatment efficiency by improving the flow uniformity of the exhaust gas in the diesel particulate filter (DPF) and reducing the pressure drop between the inlet and the outlet of DPF. In this study, the effects of pressure drop by the flow rate and temperature of exhaust gas, DPF I/O ratio, Ash, and PM amount in diesel reduction device were simulated via a 12" diameter DPF and diesel oxidation catalyst (DOC) using ANSYS Fluent. As the flow rate and temperature decreased, the pressure drop decreased, whereas the PM amount affected the pressure drop more than the ash amount and the pressure drop was lower in anisotropic DPF than isotropic DPF. In the case of DPF flow uniformity, it was constant regardless of the various variables of DPF. In ESC and ETC conditions, the filtration efficiency for PM was similar regardless of anisotropic and isotropic DPF, but the filtration efficiency for PN (particle number) was higher in anisotropic DPF than isotropic DPF.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.38 no.12
• /
• pp.963-969
• /
• 2014

Four coal sources that had different ash contents were evaluated in a drop tube furnace (DTF). Combustion experiments were conducted by using several sources with different particle sizes and excess air ratios under air-staging conditions to determine the optimized combustion conditions of high-ash coal, with an emphasis on the combustion efficiency and NOx emissions. The results show that the higher ash content results in a large amount of carbon remaining unburned, and that this effect is dominant when the largest particle size is used. Furthermore, the ash content of coal does affect the Char-NOx concentration, which decreases with the particle size. The results of this study suggest that an air-staged system can be useful to reduce the NOx emissions of high-ash coal and that control of the air stoichiometric ratio of the primary combustion zone (SR1) is effective for reducing NOx emissions, especially by considering unburned carbon contents.

• Plant Journal
• /
• v.11 no.1
• /
• pp.50-57
• /
• 2015

This study presents prediction of maximum fly ash conveying capacity of fly ash system in a power plant. The mixture ratio and pressure drop characteristics of air-fly ash flow in piping system are not well understood due to the complexity of particle motion mechanism. In this paper, the researcher investigated the optimum mixture ratio when the pressure drop of fly ash conveying system is equal to maximum static pressure of displacement fly ash transport blower and the capacity of fly ash transport according to the optimum mixture ratio by experimenting the fly ash conveying system of domestic D coal thermal power plants, which is currently in operation. The experiment results showed that the maximum fly ash conveying capacity of fly ash system were founded under the condition of maximum air volume 5,040 m3/h, static pressure of trip condition 1,163 mmH2O. In addition, it was predicted maximum mixture ratio of the air-fly ash was 8.66 and maximum capacity of fly ash conveying was 52,600 kg/h under these conditions.

• Korea-Australia Rheology Journal
• /
• v.13 no.1
• /
• pp.47-54
• /
• 2001

Prediction of the maximum packing volume fraction with non-spherical particles has been one of the important problems in powder technology. The sphericity of fly ash particles depending on the particle diameter was measured by means of a CCD image processing instrument. An algorithm to predict the maximum packing volume fraction with non-spherical particles is proposed. The maximum packing volume fraction is used to predict the slurry viscosity under well dispersed conditions. For this purpose, Simha's cell model is applied for concentrated slurry with wide particle size distribution. Also, Usui's model developed for aggregative slurries is applied to predict the non-Newtonian viscosity of dense fly ash - water slurry. It is certified that the maximum packing volume fraction for non-spherical particles can be successfully used to predict slurry viscosity. The pressure drop in a pipe flow is predicted by using the non-Newtonian viscosity of dense fly ash-water slurry obtained by the present model. The predicted relationship between pressure drop and flow rate results in a good agreement with the experimented data obtained for a test rig with 50 mm inner diameter tube. Base on the design procedure proposed in this study, a feasibility study of fly ash hydraulic transportation system from a coal-fired power station to a controlled deposit site is carried out to give a future prospect of inexpensive fly ash transportation technology.

• Journal of computational fluids engineering
• /
• v.16 no.2
• /
• pp.66-74
• /
• 2011

The SCR catalyst in coal-fired power plant is eroded by the collision of fly ash on the catalyst surface. However the erosion of SCR catalyst by the collision of fly ash has not been fully studied, especially in terms of fluid dynamics. Hence, in the present study, we focus on the gas and solid flows inside the SCR catalyst duct and their consequent effect on the erosion characteristics. For this purpose, computational fluid dynamics is applied to investigate the two-phase flows and to evaluate the erosion rate for different flow and particle injection conditions. Also, the erosion rate and pressure drop of commonly used square shape are compared with equilateral triangle and hexagon shapes. The pressure drop of SCR catalyst is increased when SCR catalyst surface area per unit volume increases. The erosion rate of SCR catalyst is enhanced when the particle velocity, mass flow rate of particle, particle diameter and cell density of SCR catalyst are increased. From the results, the pressure drop and erosion rate at the catalyst surface can be minimized by reducing cell density of SCR catalyst to decrease particle velocity and number of particle impacts.

• Journal of Korean Society for Atmospheric Environment
• /
• v.20 no.3
• /
• pp.361-369
• /
• 2004

A metal fiber bed has seldom been applied to the practical filtration process despite its excellent mechanical and chemical stability. The filter-bed used in this work was highly porous with open structure, of which apparent porosity was 80 ∼ 90%. Although pressure loss across the filter-bed was very low, separation efficiency was found to be quite high. This paper focuses on the basic filtration mechanisms of a metal filter-bed and a thin ceramic filter from fly ash for reference. The experimental parameters were face velocity, dust loading and porosity of filter-bed. Pressure drop increased with increasing face velocity and dust feeding load for both filters. It also showed that dust particles deposited in the deep flow path, finally resulting in clogging the pore channels. It thereby indicates that the dominating mechanism of the metal filter-bed would be depth filtration. Meanwhile, the thin fly ash composite filters trapped the aerated dust mainly on the surface of the filter medium, so that the instantaneously formed dust layer might cause a steep increase of pressure drop across the filtration system.

• Transactions of the Korean Society of Mechanical Engineers B
• /
• v.21 no.2
• /
• pp.264-274
• /
• 1997

A numerical analysis on condensation and coagulation of the metallic species with fly ash particles pre-existing in an incinerator was performed. Waste was simplified as a mixture of methane, chlorine, and small amounts of Pb and Sn. Vapor-phase amounts of Pb- and Sn -compounds were first calculated assuming a thermodynamic equilibrium state. Then theories on vapor-to-particle conversion, vapor condensation onto the fly ash particles, and particle-particle interaction were examined and incorporated into equations of aerosol dynamics and vapor continuity. It was assumed that the particles followed a log-normal size distribution and thus a moment model was developed in order to predict the particle concentration and the particle size distribution simultaneously. Distributions of metallic vapor concentration (or vapor pressure) were also obtained. Temperature drop rate of combustion gas, fly ash concentration and its size were selected as parameters influencing the discharged amount of metallic species. In general, the coagulation between the newly formed metal particles and the fly ash particles was much greater than that between the metal particles themselves or between the fly ash particles themselves. It was also found that the amount of metallic species discharged into the atmosphere was increased due to coagulation. While most of PbO vapors produced from the combustion were eliminated due to combined effect of condensation and coagulation, the highly volatile species, PbCl$_{2}$ and SnCl$_{4}$ vapors tended to discharge into the atmosphere without experiencing either the condensation or the coagulation. For Sn vapors the tendency was between that of PbO vapors and that of PbCl$_{2}$ or SnCl$_{4}$. To restrain the discharged amount of hazardous metallic species, the coagulation should be restrained, the number concentration and the size of pre-existing fly ash particles should be increased, and the temperature drop rate of combustion gas should be kept low.