Thermogravimetric (TG) analysis was used to investigate the effects of carbonization and solvent extraction on the combustion characteristics of sewage sludge. Initial temperature (IT) and peak temperature (PT) represent combustion characteristics in carbonized sludge (CS). The sludge extracted (ECS) from CS using solvent extraction exhibited higher IT and PT than raw sludge (RS). First, indicate that carbonization was carried out at two different temperatures, 300 and 400oC, to produce CS300 and CS400; then, compare the corresponding IT and burnout temperature (BT). All IT and PT values for ECS300 were lower than those values for RS and CS. The activation energy determined for the combustions of CS300 and ECS300 was lower than the one for the combustion of RS. The ECS300 activation energy (combustion zone of char) was determined to be 90.7 ~ 99.1 kJ/mol, lower to the range of 109.3 ~ 126.9 kJ/mol for coal.

The fuel characteristics, the combustion characteristics, and the kinetic study of sample that had been torrefied at 250 ~ 300oC were investigated for orange peel, rice husks, wood chips, and wood pellets. When higher torrefaction temperature was used, reduction of the yield, and increase in the fuel ratio, and decrease of volatile content were found. As a result, improvement of the fuel characteristics was confirmed. As parameters for the combustion characteristics, initial temperature (IT) was rised slightly because of the high torrefaction temperature of the wood chip, and burnout temperature (BT) showed lowered. The combustion time (tq) of torrefied wood chip (TC) is shorter than raw sample, and unburned carbon generation will be suppressed. The activation energy of the char combustion reaction (2nd) is reduction compared to the raw sample, and the pre-exponential factor was decreased. As a result, the combustion reaction rate constant (k) of the torrefied wood chips, should be determined considering the activation energy and the pre-exponential factor.

Efforts were made to determine the activation energy and the reaction order by adopting Kissinger and Flynn-Wall-Ozawa analysis methods. All the data were acquired from TGA thermograms for the mixed fuels with different temperature heating rates. It could be known that both the coal and the mixed fuels decomposed thermally at temperature ranges of 300～700℃. The temperature at the maximum reaction rate, Tp, could be determined by DTG method, which could be obtained by differentiation of TGA thermogram. Kissinger analysis showed the linear relationship with experimental data, showing the activation energy of 319.64 ±4 kJ/mol. From Flynn-Wall-Ozawa analysis, it was shown that the activation energies and the reaction orders did not undergo any significant changes with both the conversions and the heating rates. It was considered from this facts that the combustion mechanism of the mixed fuels could not be affected by the extent of conversion and heating rate. In the present study, the activation energies showed different values according to the different analysis methods. The difference might be originated from the inconsistency of the mathematical data treatment method. In other words, while the activation energies obtained from the Kissinger method indicated the average values for overall reaction, that from Flynn-Wall-Ozawa method showed the average values for the each conversion around Tp.

MILD (Moderate and Intense Low oxygen Dilution) combustion using high temperature exhaust gas recirculation is applied to solid fuels of dried sewage sludge and pulverized coal combustion to investigate the effect of reduction of NOx emission in a pilot scale combustor. High temperature exhaust gas recirculation is accomplished by entraining high temperature exhaust gas to air jets at just exit of the combustion chamber without a heat exchanger. High temperature exhaust gas recirculation makes the solid fuel flame stable and extremely uniform color and uniform temperature distribution. NOx concentration at the combustor exit was 62% and 40% less in the high temperature exhaust recirculation MILD combustion compared with the conventional combustion using air jet only for sewage sludge and pulverized coal respectively.

Diesel DeNOx experiments using the SNCR process were performed by directly injecting NH3 into a simulated engine cylinder (966 cm3) for which a diesel fuelled combustion-driven flow reactor was designed by simulating diesel engine geometry, temperature profiles, aerodynamics and combustion products. A wide range of air/fuel mixtures (A/F=20∼45) were combusted for oxidizing diesel flue gas conditions where an initial NOx levels were 250~900 ppm and molar ratios (β=NH3/NOx) ranged from 0.5∼2.0 for NOx reduction tests. Effective NOx reduction occurred over a temperature range of 1100∼1350 K at cylinder injections where about 34% NOx reduction was achieved with β=1.5 and cylinder cooling at optimum flow conditions. The effects of simulated engine cylinder and exhaust parts, initial NOx levels, molar ratios and engine speeds on NOx reduction potential are discussed following temperature gradients and diesel engine environments. A staged injection by NH3 and diesel fuel additive is tested for further NOx reduction, and more discussed for practical implication.

Renewable energy has been focused issue in terms of green house gas (GHG) prevention as well as the sustainable development. One of the most feasible and economical ways to enhance the renewable energy production would be the biomass energy production, which is renewable in terms of carbon neutral. At present, many developed country discovered the biomass resources that will be fitted to their purpose. In Malaysia and Indonesia, palm kernel shell (PKS) was only the waste to dumping on the ground around 5 years ago, but they are exported to all over the countries as a biomass resources. The woody biomass has been the most traditional biomass resources, and their price is so high and quantity is so limited that the electric generation can’t obtain enough quantities to fulfill their renewable energy obligation quarter. Within near future, many types of biomass like rice husk pellet, coconut shell, and empty fruit bunch (EFB) pellet, will be traded commercially and imported to Korea after all. The Korean power plant company using coal try to discover the biomass resources in south. east Asia. In this study, 7 types of biomass was tested for fuel quality as well as the combustion behavior, and compared to each other. It can be found that the fuel property of biomass can be varied with the types and the combustion pattern may not be identical with respect to the types of the biomass. PKS was the very good fuel with high calorific value, but contains some chloride. Wood chips also were a good fuel property cleaner than coal in terms of emission gas. The rice straw, however was not good enough to use as a fuel.

In the present study, MILD (Moderate and Intense Low oxygen Dilution) combustion technology is adopted as one of the most effective tool for reduction of NOx emission in solid fuel combustion. We tried to achieve MILD combustion using the high temperature exhaust recirculation without any heat exchanger for preheating air. High temperature exhaust recirculation is accomplished by entraining the high temperature exhaust gas to air jets at just exit of the combustion chamber. This high temperature exhaust recirculation could recirculate heat and inert exhaust gas simultaneously. MILD combustion using the recirculation of the high temperature exhaust gas is experimented to investigate the effect of low NOx emission for the recycled solid fuel of the dried sewage sludge and pulverized coal. NOx emission could be reduced drastically by using this advanced combustion technique. Maximum 68% and 57% of NOx reduction was achieved for sewage sludge and pulverized coal respectively, in the high temperature exhaust recirculation MILD combustion compared with the conventional combustion using air jet only. This type of MILD combustion makes the apparent flames of both solid fuels extremely uniform without high temperature flamelet.

숯은 제조 및 활용과정에서 연소를 통해 함유된 성분들을 방출한다. 연소는 숯의 화학조성뿐만 아니라 숯의 표면 물성변화를 초래하고 다른 성분을 흡착하기 쉬운 상태로 변형시키기도 한다. 본 연구에서는 국내에서 시판되는 4종 숯에 대하여 화학적, 열적안정성과 중금속 및 유기유해물질의 거동 연구를 수행하였다. 상온에서 400℃까지 열중량분석(TGA)과 시차주사열량계를 이용한 연소에 따른 중량변화와 관련된 물질거동 연구를 수행하였다. TGA 분석결과 대부분 시료에서 200℃ 이전 약 10% 중량이 감소하였으며, 200℃ 이전에 잔류유기물과 가스상 물질이 소실되는 것을 알려준다. 열분석에 의한 질량 감소는 천연숯과 인공숯에서 다르게 측정되었다. 천연숯 K1, C1 에서는 400℃까지의 가열 반응결과 약 15% 중량 감소가 있었으며, 인공숯 K2, C2의 경우 약 20%의 중량 감소가 있는 것으로 검출되었다. 가열에 의한 400℃ 이하 중량감소는 주요 유기물과 VOC의 소설에 기인하는 것으로 나타났다. 화학조성분석에 근거한 X-선 회절분석을 실시하였다. 분석결과 첨가제인 Ba이 Ba(NO3)2 및 BaCO3 등의 형태로 NaNO3와 함께 숯에 다량 존재하는 것으로 분석되었다.

This is a study on the volatile organic compounds(VOCs) concentrator with zeolite adsorptive honey rotor and catalytic combustion system for abating VOCs emitted from printing industry. VOCs emitted from the printing industry is mainly caused by organic solvent of printing ink. The content of organic solvents in printing ink varies from 40% to 75% and its content in the gravure ink is higher than that in any other ink. The average concentrations of each VOCs are 139 ppm for toluene, 152.1 ppm for MEK, 256.9 ppm for methanol and 42.9 ppm for isopropyl alcohol. We used zeolite honeycomb for absorbent of VOCs concentrator and palladium for catalyst combustion system. This system abated over 96% of emitted total VOCs, 98% of toluene, 100% of MEK, 92% of methanol and 100% of isopropyl alcohol. It is concluded that the low-leveled high-volume VOCs emitted from printing process were removed almost by concentrator with zeolite adsorptive honey rotor and catalytic combustion system.

The Kyoto Protocol, that had been in force from February 16, 2005, requires significant reduction in CO₂emissions for all anthropogenic sources containing transportation, industrial, commercial, and residential fields, etc, and automotive emission standards for air pollutants such as particulate matter (PM) and nitrogen oxides (NOx) become more and more tight for improving ambient air quality. This paper has briefly reviewed homogeneous charge compression ignition (HCCI) combustion technology offering dramatic reduction in CO₂, NOx and PM emissions, compared to conventional gasoline and diesel engine vehicles, in an effort of automotive industries and their related academic activities to comply with future fuel economy legislation, e.g., CO₂emission standards and corporate average fuel economy (CAFE) in the respective European Union (EU) and United States of America (USA), and to meet very stringent future automotive emission standards, e.g., Tier 2 program in USA and EURO V in EU. In addition, major challenges to the widespread use of HCCI engines in road applications are discussed in aspects of new catalytic emissions controls to remove high CO and unburned hydrocarbons from such engine-equipped vehicles.

이 연구에서는 알코올과 증류수를 특정비율로 혼합한 특수용매를 사용하여 합성한 Gd2O3:Eu 나노 분말이 Europium(Eu)함량에 따라 어떤 입자특성과 발광특성을 가지게 되는지에 대하여 조사하였다. 액상법에 사용된 이 용매는 Gadolinium(Gd)과 Europium(Eu)의 용해되는 시간을 현저히 줄임으로써, 실험시간이 단축됨을 확 인하였다. 이번 실험에서 Gd2O3:Eu 나노 powder 형광체의 입자특성은 SEM(scanning electron microscope)과 EDX(Energy Dispersive X-ray)를 사용하였으며, 나노 powder의 발광특성은 PL(Photoluminescence), CL(CathodeLuminescence)을 사용하여 측정하였다. 결정들은 30nm∼40nm의 크기의 결정을 가졌고 발광특성 은 약 620nm의 특정 파장에서 크게 반응함을 알 수 있었으며, Europium(Eu)함량이 1wt%에서 3wt%, 5wt% 로 늘어날수록 Photon의 count가 증가하게 되어 발광효율이 증가함을 알 수 있었다.

Numerical study is conducted to predict effects of radiative heat loss and fuel composition in synthetic gas diffusion flame diluted with CO₂. The existing reaction models in synthetic gas flames diluted with CO₂ are evaluated. Numerical simulations with and without gas radiation, based on an optical thin model, are also performed to concrete impacts on effects of radiative heat loss in flame characteristics. Importantly contributing reaction steps to heat release rate are compared for synthetic gas flames with and without CO₂ dilution. It is also addressed that the composition of synthetic gas mixtures and their radiative heat losses through the addition of CO₂ modify the reaction pathways of oxidation diluted with CO₂.

The coal gasification fuel is important to replace petroleum fuel. Also they have many benefits for reducing the air pollution. Measurements on the combustion characteristics of synthetic gas from coal gasification have been conducted as compared with LPG in constant volume combustion chamber. The fuel is low caloric synthetic gas containing carbon monoxide 30%, hydrogen 20%, carbon dioxide 5%, and nitrogen 45%. To elucidate the combustion characteristics of the coal gasification fuel, the combustion pressures, combustion durations, and pollutants(NOx, CO2, CO) are measured with equivalence ratios(ø), and initial pressures of fuel-air mixture in constant volume chamber. In the case of the coal gasification fuel, maximum combustion pressure and NOx concentration are lower rather than LPG fuel. However CO and CO2 emission concentration are similar to that of LPG fuel.

The advantage of CFBC(Circulating fluidized bed combustor) is that it can apply to various fuel sources including the lower rank fuel and remove SOx by means of direct supply of limestone to the combustor without additional desulfation facility. In this paper, we denote characteristics of fly and bed ash to reuse finer limestone usually abandoned(used spec[Coarse LS] 0.1mm under 25%, new spec[Fine LS] 0.1mm under 50%). According to the results, the chemical composition of fly ash was as follows; SiO2 40.8%, Al2O3 31.9%, CaO 10.7%, K2O 4.46% in the case of coarse limestone and SiO2 41.1%, Al2O3 31.3%, CaO 10.9%, K2O 4.66% in the case of fine limestone. The chemical composition of bed ash was as follows; SiO2 54.2%, Al2O3 33.1%, CaO 1.56%, K20 4.34% in the case of coarse limestone and SiO2 53.8%, Al2O3 32.6%, CaO 2.21%, K2O 4.45% in the case of fine limestone. It showed that there was no significant change in chemical composition. And it is conformed that there was no significant change in particle size and shapes.

We have studied the catalytic combustion of soot particulates over perovskite-type oxides prepared by malic acid method. The catalysts were modified to enhance the activity by substitution of metal into A or B site of perovskite oxide. In addition, the reaction conditions such as temperature and O2 concentration were investigated. The partial substitution of alkali metals into A site in the LaMnO3 catalyst, enhanced the catalytic activity in the combustion of carbon particulate and the activity was shown in the order: Cs＞K＞Na. For the La1-xCsxMnO3 catalysts, the catalytic activity showed the maximum value with x=0.3 but no more increase on the catalytic activity was shown with x＞0.3. For the La0.8Cs0.2MnO3 catalyst, the substitution of Fe or Ni increased the ignition temperature. The ignition temperature decreased with an increase of O2 concentration, however, no more increase in the catalytic activity was shown with O2 concentration＞0.2. The introduction of NO into reactants showed no effect on the catalytic activity.