This study was carried out to design and develope conveyer combustion type coal heater in the green house. Different from existing coal heater, the conveyer combustion type coal heater was designed for circulating coal from supplying to exhausting. The size of traveling grate and velocity reduction gear ratio for driving traveling grate were designed to product coal heater had 200,000kcal/hr heating capacity. The result is that the coal heater of 200,000kcal/hr heating capacity was determined by the width of grate in between 600 to 800㎜ when the horizontal length of conveying combustion area was 1,500㎜. And the first and second reduction ratio of 1:100 and 1:70 was more effective at 1,350rpm, respectively, in the coal heater of 200,000kcal/hr heating capacity.

By the end of 2012, the recycled proportion of domestic waste tires was 287,330 ton (93.9%) of the amount of waste tires discharged (305,877 ton). The waste tires have been reused for heat supply, material recycling and other purposes; the proportions are 50.1%, 20.7% and 23.1%, respectively. In the case of heat supply, waste tires are supplied to cement kiln (104,105 ton, 68%), RDF manufacture facilities (47,530 ton, 31%) and incinerators (1,923 ton, 1%). Recently, there has been an increase in the use of waste tires at power generation facilities as an auxiliary fuel. Thus, physico-chemical analysis, such as proximate analysis, elemental analysis and calorific value analysis have been carried out to evaluate potential of waste tires as an auxiliary fuel in Korea. The LHV (Lower Heating Value) of waste tires is approximately 20% higher than that of coal, at an average of 8,489 kcal/kg (7,684 ~ 10,040 kcal/kg). Meanwhile, the sulfur content is approximately 1.5wt. %, and balance of plant (e.g. pipe line, boiler tube, etc.) may be corroded by the sulfur. However, this can be prevented by construction and supplementation with refractories. In this study, TDF (Tire Derived Fuel) produced from waste tires was co-combusted with coal, and applied to the CFB (Circulating Fluidized Bed) boiler, a commercial plant of 100 tons/day in Korea. It was combined with coal, ranging from 0 to 20wt. %. In order to determine the effect on human health and the environment, gas emission such as dioxin, NOx, SOx and so on, were continuously analyzed and monitored as well as the oxygen and carbon monoxide levels to check operational issues.

There is an increasing demand for sustainable resources due to a steady increase in energy demand. As the1996 Protocol to the London Convention takes effect, conversion of sewage sludge to energy is increasing. To use waste as fuel, it is important to understand its combustion characteristics. Using thermogravimetric analysis, the combustion of coal, dried sewage sludge, and SRF was characterized in this study. Dried sludge and SRF showed similar combustion behavior at all temperature increase rates of 5, 10, 25, 40, and 100oC/min. Coal burned at a higher temperature as the temperature rate increased. This may be ascribed to the much higher volatile matter contents of dried sludge and SRF comparative to coal.

화력발전소에서 석탄을 이용하여 에너지를 생산하는 연소방식에는 크게 미분탄 연소방식과 순환 유동층 연소방식으로 구분된다. 순환 유동층 연소방식은 기존 연소로에는 적합하지 않은 고유황탄, 저품위탄, 폐기물 등 모든 가연성 물질에 대하여 광범위한 원료 사용이 가능하다. 또한, 질소산화물의 배출을 억제하기 위해 연소로 온도를 약 900℃ 정도로 유지하고 암모니아를 분무하며, 석탄과 석회석을 혼소하여 노(盧) 내에서 직접 탈황을 실시하는 등의 공정관리를 실시하고 있다. 이러한 순환 유동층 연소방식의 석탄재(이하 CFBC-FA)는 화학적 특성이 미분탄 연소방식의 F급 석탄재와는 달리 CaO 화합물이 다량 함유되어 있어 콘크리트 혼화재로 사용할 경우 Free CaO 성분이 콘크리트의 이상 응결현상, 슬럼프의 손실, 지연제의 사용량 증가, 내구성 저하 등의 문제를 발생시키고, 특히 콘크리트의 팽창, 균열　등의 문제를 발생하여 물성을 저하시키는 것으로 알려져 있으며, 전량 매립처리 되고 있어 재활용 방안이 요구되고 있다. 본 연구에서는 CFBC-FA를 건설재료(콘크리트 구조물 적용 제외)로 활용하기 위해 CFBC-FA의 물리․화학적 특성 분석을 실시하였으며, 고로슬래그와 CFBC-FA를 활용한 무기결합재 물성평가를 실시하였다. 본 실험에 사용한 CFBC-FA는 미분탄 연소방식의 석탄재와는 달리 CaO 함량 32.4%, SO₃ 함량 8.4%로 높았으며, SiO₂ 30.5%, Al₂O₃ 15.9%로 구성되어 있음을 확인하였다. Free CaO 함량은 17.3%, 비중은 2.8, 강열감량은 3.4%, pH는 12.4, 평균입경은 7.23 ㎛로 측정되었으며, 입형은 미분탄 연소방식의 석탄재와 같은 구형이 아닌 부정형임을 확인하였다. 이러한 물성을 지닌 CFBC-FA를 개질처리하여 제조한 결합재의 수화열, 유동성, 강도 측정을 실시하였다. 개질처리한 CFBC-FA의 혼입량이 증가할수록 유동성은 감소하는 경향을 나타내었으며, 수화열은 높아지는 경향을 보였다. 수화열의 발열성상은 보통포틀랜드 시멘트 및 슬래그시멘트와 달리 가수 후 2시간 이내에 최고 온도에 도달하고 있음을 확인하였다. 개질처리한 CFBC-FA와 고로슬래그의 혼합비율이 55:45인 결합재와 슬래그 시멘트의 재령7일 압축강도는 각각 12.7 MPa, 17.6 MPa였으며, 28일 압축강도는 30.0 MPa, 29.8 MPa 로 측정되었다.

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.

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.

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.