The non-reacting flow field and the movement of sand particles inside a 30MW circulating fluidized bed combustor is numerically simulated via the finite volume method. The primary air is supplied through 23x23 array of nozzles located on the bottom and the secondary air is supplied through 12 inlet pipes located on the side walls. The steady state velocity field shows that a very complex flow pattern is formed in the lower part of the combustor. As the gas moves upward, the velocity magnitude decreases and the gas exits the combustor after hitting the top wall. To investigate the behavior of sand particles with different diameters, a particle tracking calculation is performed by introducing sand particles continuously at the z=3 m plane. For the given air flow rate condition, sand particles smaller than 0.3 mm show a complex movement pattern near the secondary air inlet and then rise toward the outlet.

The aim of this project was to explore the potential of the torrefaction treatment for upgrading sewage sludge into valuable product. An ancillary investigation on the cold fluidization and the behavior of sewage sludge was analyzed. The effects of the main torrefaction variables, temperature and residence time, on the performance parameters such as fixed carbon, calorific value; molar ratios, ultimate and proximate analysis, chemical exergy etc. were investigated for torrefied sewage sludge. Results for both the reactors showed that the thermochemical transformations that sewage sludge underwent, as a results of the release of volatile matter due to thermal decomposition of its organic constituents, resulted in significant improvement of their chemical and physical properties. Results obtained from this study showed that despite the leverage that fluidized bed offers (heat and mass transfer) fixed bed configuration was more pronounced for torrefaction of sewage sludge. However, a decisive conclusion cannot be made at this stage as more detail study would be required to draw a definitive conclusion over the preference of reactor for torrefaction.

현재 국내 도시 생활쓰레기 및 산업쓰레기의 처리 시, 매립지 부족과 침출수 등으로 인한 2차 오염문제로 매립처리 방법은 우리나라에서는 적절치 않다. 하지만 쓰레기의 소각처리의 경우, 소각으로 인한 열작감량이 매우 크고 폐에너지 회수의 장점도 있기에 국내 쓰레기의 처리는 소각에 많이 의존하고 있다. 또한 국내 대체에너지의 목표치가 높아지는 상황에서 폐기물의 대체 에너지가 큰 역할을 해 주어야 한다. 폐기물 고형연료를 연소하는 과정 중에는 여러 문제점이 있는데, 설비의 고온 부식의 영향 및 연소로 내 국부적인 가열로 인한 설비의 파손, 연소로 내 불규칙적 유동현상으로 인한 연소 장애 등이 있다. 따라서 앞에서 말한 문제점들을 보안하며 보일러의 안정적인 운전 및 열효율 향상을 위해서는 기본적으로 연소로 내 유동현상을 정확히 예측할 수 있어야 한다. 이를 위해 우리는 상용화 되고 있는 50ton/day 이상 Stoker 보일러 현장 운전조건을 대입, Ansys CFD Fluent.18을 사용하여 시뮬레이션을 진행하였다. 연소로 내 열의 유동해석, 배출가스의 흐름 등을 예측하여 연소장애의 원인을 찾아보고 이에 맞는 대안을 찾기 위한 연구를 하였다.

In this work, the separation characteristics of CO2 from CO2 and CH4 mixed gas was studied using pressure swingadsorption (PSA) process. Zeolite 13X was used as an adsorbent to adsorb CO2 from gaseous stream in a fixed-bed ofadsorbent. The adsorption experiments were performed with various gas flow rates, adsorption pressures and temperatures.The deactivation model was used to analyze the adsorption kinetics of CO2 using the experimental breakthrough data.From this work, it was found that the activation energies of adsorption and deactivation were 29.15 and 13.0 kJ/mol,respectively. And the experimental breakthrough curves were agree very well with the adsorption isotherm models basedon Freundlich equation.