Analyzing results of exhaust gas of solid fuel burning are investigated with measuring position in a pilot scale MILD(Moderate and Intense Low oxygen Dilution) combustor using high temperature exhaust gas recirculation. Flue gas hasbeen measured at exit of combustion chamber and stack, especially. Oxygen concentration measured at stack is higherand carbon dioxide concentration is lower than that measured at exit of combustion chamber, because air flows into theflue gas from the post-treatment facilities, such as gas cooler and bag filter, due to negative pressure caused by inducedblower. Low carbon dioxide concentration can cause an error which estimates higher air ratio than actual air flow rateneeded for complete combustion. Average calculated concentration of measured nitric oxide and carbon monoxide forreference concentration of 6% oxygen have no notable difference with measuring position. But, time resolution of thedata measured at exit of combustion chamber is better than that measured at stack. It is confirmed that MILD combustionof solid fuel of pulverized coal using high temperature exhaust gas recirculation can reduce dramatically nitric oxideemission.

우리나라는 해양투기제도 시행 첫 해인 1988년에 55만톤의 폐기물을 해양 투기한 이래로 2011년까지 총 1억 2천만톤 이상의 폐기물을 대한민국 EEZ 경계에 위치한 3개의 지정해역에 투기하였다. 그러나 2011년 말 전체 해양투기량의 약 절반을 차지하던 하수오니 및 가축분뇨의 해양투기를 2012년부터 금지시키고 2013년도부터는 2012년도 전체 투기량의 절반을 차지하고 있는 음폐수의 해양투기를 금지하기로 이미 법제화한 바 있다. 이에 따라 국내 축산농가를 중심으로 연간 약 4700만톤(‘10년 기준) 대량으로 발생하고 있는 축산분뇨의 처리방안에 대한 다양한 방안이 검토 및 연구되고 있다. 이러한 축산분뇨 처리 방안 중 하나로 축분에 한 연료화 검토가 진행 중이며, 현재까지는 주로 소형의 보일러 연료로 활용이 대부분이나 최근 화석연료인 석탄을 대량으로 소비하며 이산화탄소 대량 배출원의 하나인 석탄화력발전소에 혼합연료로 활용하는 방안이 검토 중에 있다. 축분을 석탄화력발전소의 혼합연료로 사용할 경우 폐기물인 축분의 대용량 처리가 가능하고, 또한 향후 축분연료가 대용량 발전소의 연료로 고시될 경우 발전회사의 RPS(신재생에너지공급의무제; Renewable Portfolio Standard) 달성에 기여할 수 있기 때문에 축분연료의 발전용 석탄과의 혼합연소 가능성에 대한 관심이 크게 증가하고 있는 실정이다. 본 연구에서는 국내화력발전소의 RPS 대응방안의 일환으로 검토 중인 축분연료의 석탄과의 혼합비율에 따른 연소특성 평가를 통해 축산폐기물의 연료화 가능성을 검토하였다.

폐기물 고형연료(RDF : Refuse-Derived Fuel) 또는 고형연료제품(SRF : Solid Refuse Fuel)은 가연성 고체폐기물을 분쇄한 후에 선별 및 건조 과정을 거쳐서 제조되는 성형 또는 비성형 고체연료로서 회석연료의 대체에너지로 이용이 가능하고, 일반적인 소각 방법에 비하여 수송성, 저장성, 연소 안정성이 우수하여 소각시설의 열이용에 따르는 많은 문제점을 해소할 수 있는 장점을 가지고 있다. 본 연구에서는 RDF에 대한 연소 특성을 파악하기 위한 목적으로 실험실 규모의 연속식 및 회분식 연소 장치를 이용하여, RDF의 조성과 연소 조건에 따른 비교실험이 수행되었다. RDF 연소 특성실험에 사용되는 RDF 시료는 모두 6 종류의 원료와 실험실 규모의 압착 기구를 이용하여 3종류 형태(Powder, Chip, Plate)로 제조되었으며, RDF 연소 특성 비교 실험은 100 ~ 300 g-RDF/시간의 처리 용량을 가진 연속식의 실험실 규모 연소 장치와 길이가 600 mm인 연소로에 장착된 내경 70 mm의 석영 튜브를 이용하는 회분식의 RDF 연소 장치를 이용하여 수행하였다. 주요한 실험 결과를 살펴보면 우선 2 ~ 6 g/개 범위의 무게를 가진 RDF 시료는 대부분이 5 분 정도의 시간내에서 연소가 종료되었으며, CO는 100 ~ 300 ppm (12% O₂), NO는 200 ppm (12% O₂) 이하의 배출 농도를 나타냈다. RDF 제조용 원료로 사용된 PE 및 PP의 함량이 높아질수록 CO 배출 농도는 급격히 증가하며, O₂ 농도는 PE 및 PP의 함량이 증가할수록 감소하는 경향을 보인다. 또한 NO 및 CO₂의 경우는 PE 및 PP의 함량에 따른 배출농도의 변화가 상대적으로 작게 나타났으며, RDF 시료중의 염소 성분 함량이 일정한 조건에서는 흡수제로 사용되는 Ca(OH)₂의 투입량이 많아질수록 바닥회재 중의 염소 함량이 증가하였다.

폐기물의 에너지화는 경제, 산업, 공공정책 등 국가적으로 다양한 분야에 상당한 관심이 집중되어 있는 분야이다. 폐자원 에너지화 기술은 현재는 소각과 퇴비화에서 점차 소각+에너지회수, 가스화, RDF/RPF 등 고형연료화, 바이오 가스화 등으로 변화하고 있다. 그중 폐기물 가스화 기술은 폐기물을 이용한 다양한 에너지원으로 자원화 하는 기술로서 가스화를 통해 생산된 합성가스를 이용하는 산업과 밀접한 연관성을 갖고 있다. 가스화 공정은 석탄, 중질 잔사유, 석유코크스, 바이오매스, 폐기물 등의 탄소를 함유하는 모든 물질에서 H2와 CO의 합성가스를 생성하는 공정이다. 본 연구에서는 폐기물 가스화를 통하여 얻어진 합성가스를 기존의 LNG 연소로에 혼소하여 연소특성을 연구하고자 한다. 가스화 연료를 생산하여도 수요처가 없다면 경제성이 떨어지는 것에 착안하여 기존에 LNG 연료를 사용하는 연소로에 일부를 혼소시켜 열유동의 안정성도 어느 정도 확보하면서 상대적으로 가격이 저렴한 합성연료를 사용함으로써 연료비를 절감하는데 일조하고자 한다. 연구결과를 살펴보면 폐기물 가스화 합성연료를 사용함에 따라 전반적인 연소성능은 유사한 경향을 보였으나 화염의 형태가 ‘intensive’ 한 형상에서 좀 더 ‘broadening’ 해진 형상으로 전이되어 감을 확인하였다. 또한 LNG 연소로의 swirl버너에서 관찰되던 중앙재순환 영역(CTRZ:Central Toroidal Recirculation Zone)의 소멸과 화염의 부분적인 lift-off 현상이 관찰되었다. 그러나 전반적인 연소성능은 유사한 형태를 나타내어 향후 버너부근의 혼합강화를 위하여 운전조건을 변화시켜 연구를 지속적으로 수행한다면 LNG에 비해 상대적으로 발열량이 낮고 주입량이 많은 합성연료의 불리한 점을 충분히 보완할 수 있을 것으로 판단된다.

The following are the results from an evaluation of the combustion characteristics of biomass processed with lowtemperature carbonization and coal, and those of a blend of both. Differential thermo-gravimetric (DTG) analysis has revealed that the number of curves was reduced as a result of carbonization and that the fuel quality was improved due to the increase of initial temperature (IT). It was also confirmed that the carbonized samples consisting only of the biomass required less combustion time (tq), while samples blended with coal burned longer than the weighted average value. The combustion time of a blended sample was shorter at an carbonization temperature of 400oC than at 300oC, and the combustion stability was achieved due to a narrow range of change in the combustion characteristics. The reaction rate constant (k) of the samples blended with coal was found to be smaller for all blend ratios, when compared with that of the unblended samples (raw, carbonized biomass). The combustion reaction models that were applicable for the devolatilization-combustion zone were diffusion (D1, D3) and Reaction order (O3) models; diffusion (D1-D4) model was primarily employed in the char combustion zone. In summary, low-temperature carbonization contributed to minimizing the change in the combustion characteristics of the biomass/coal blend.

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.

This study investigated the House of Commons through the combustion characteristics of the flammable after performing the experiment for predicting fire constellation is to present basic material. Combustibles of the House of Commons was established to investigate through the standard model, such a list of proposed standards for the combustible

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.

In this study, a cold model of a circulating fluidized bed is developed and tested for designing a char combustor. This study has been carried out to investigate effects of the solid circulation rate and superficial gas velocity on the hydrodynamic characteristics in a circulating fluidized bed. Solid holdup and pressure drop in the riser increases with the increase of solid circulation rate, but decreases with increasing superficial gas velocity. The solid holdup in the dense region increases with increasing solid circulation rate at lower gas velocities, whereas it is independent of solids circulation rate at higher gas velocities.

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.