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김사중 ( Kim Sa Jung ),이찬기 ( Lee Chan Gi ),송평섭 ( Song Pyeong Seob ),윤종성 ( Yun Jong Seong ),강용 ( Kang Yong ),김준식 ( Kim Jun Sig ),최명재 ( Choe Myeong Jae ) 한국공업화학회 2003 공업화학 Vol.14 No.5
폐폴리스티렌 및 범용 폴리스티렌을 각각 시료로 하여 TGA (thermogravimetric analysis)를 이용하여 열분해와 연소 반응을 수행하여 폐폴리스티렌과 범용 폴리스티렌의 열분해 및 연소반응 특성을 검토하였다. TGA의 승온속도는 10 K/min, 20 K/min, 30 K/min, 40 K/min 및 50 K/min로 변화 시켰으며, 질소와 산소 분위기에서 가열온도는 323 K~1073 K 범위에서 수행하였다. 반응 특성 검토에서 중요한 요소인 반응차수 및 활성화 에너지들은 Kissinger, Freeman-Carroll, Chatterjee-Conrad, Friedman 및 Coats-Redfern 방법을 사용하여 해석하였고, 각각의 방법에 따른 열분해와 연소반응의 활성화에너지 값을 구하여 비교, 해석하였다. 연구에 사용된 해석 방법과 실험조건에 따라 결과값에 차이가 있음을 알 수 있었으며, 연소 분위기의 겉보기 활성화에너지 값은 140~225 kJ/mol으로 열분해 분위기의 155~260 kJ/mol 값보다 작게 나타났다. Thermal characteristics and kinetic parameters of polystyrene waste and polystyrene were determined by means of thermogravimetry (TGA) at non-isothermal heating conditions(10 K/min, 20 Wmi, 30 K/min, 40 Wmin and 50 K/min) both for pyrolysis and combustion processes. Activation energies and reaction orders of the samples were determined by different methods such as Kissinger, Freeman-Carroll, Chattejee-Conrad, Friedman and Coats-Redfem methods. These methods were compared in terms of their accuracy and the ease of interpretation of the kinetics of thermal decomposition. It was found that the apparent activation energies of the thermal processes were different with variation of analytical methods and experimental conditions. The apparent activation energy of combustion at the atmosphere of 80∼130 KJ/mol was lower than that of pyrolysis at the atmosphere of 90∼150 KJ/mol.
분체공학 , 유동층 , 고분자 , 재료 ( 무기 , 유기 ) : 삼상 순환유동층에서 기체 - 액체 물질전달 특성
김사중(Sa Jung Kim),강용(Yong Kang),박성희(Sung Hee Park),조용준(Yong Jun Cho),김상돈(Sang Done Kim) 한국화학공학회 2001 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.39 No.5
Characteristics of gas-liquid volumetric mass transfer has been investigated in a riser of three-phase circulating fluidized bed(0.102 m ID and 3.5 m in height). Effects of gas(0.01-0.09 m/s) and liquid(0.12-0.43 m/s) velocities, solid circulation rate(2-8 ㎏/㎡s) and fluidized particle size(1.0-3.0 ㎜) on the volumetric gas-liquid mass transfer coefficient have been examined. The mass transfer coefficient has been recovered from the concentration profile of dissolved oxygen in the axial direction of the riser by means of axial dispersion model. Tap water, filtered and compressed air and glass bead whose density is 2,500 ㎏/㎥ were employed as a liquid, gas and solid phase, respectively. It has been found that the gas velocity is a important factor to determine the value of mass transfer coefficient; the mass transfer coefficient increases with increasing gas velocity but it dose not change considerably with the variation of liquid velocity in the beds of relatively large particle(d_p: 1.7-3.0 ㎜), although the k_La value increases slightly with increasing U_L in the beds of 1 ㎜ glass bead. The value of mass transfer coefficient increases with increasing solid circulation rate as well as particle size. The mass transfer coefficient has been correlated as a function of operation variables as well as dimensionless groups.
김준식(Jun Sik Kim),김사중(Sa Jung Kim),윤종성(Jong Sung Yun),강용(Yong Kang),최명재(Myoung Jae Choi) 한국공업화학회 2002 공업화학 Vol.13 No.5
폐유와 같은 산업 폐기물의 처리는 환경 보호 측면에서 많은 관심을 모아지고 있다. 토양 등에 2차 오염의 문제가 있는 매립에 의한 처리 대신에 폐유의 연소는 적절한 처리 방법으로 특히, 폐유의 높은 발열량을 고려하면 보다 타당한 방법이라 할 수 있다. 따라서, 본 실험에서는 유동층 연소로(0.1 m ID×2.5 m in height)에서 폐유 연소시 열전달 특성에 대한 운전 변수들의 영향을 고찰하였다. 과잉공기율과 폐유의 공급속도는 각각 0∼60% 그리고 10∼40 g/min으로 하였다. 유동층의 층 영역에서 폐유 연소시 열전달계수는 온도 증가에 따라 증가하였으나 과잉공기율의 증가에 따라 열전달계수는 감소하였다. 그리고, 폐유 공급속도의 증가에 따라 최대값을 나타내었다. 하지만, 프리보드영역에서의 열전달계수는 과잉공기율과 폐유 공급속도의 증가에 따라 증가하였다. 본 실험의 결과는 폐유의 연소를 위한 유동층 연소로의 적정한 조업조건의 결정과 이의 설계 및 scale-up을 위한 기초자료로 활용될 수 있다. Disposals of industrial wastes such as waste oil have been one of the important public concerns in view of environmental protection. Because of the secondary pollution of soil, combustion of waste oil has been one of the appropriate methods instead of landfill, especially, considering the heating value of waste oil. In this study, therefore, effects of operating variables on the heat transfer characteristics of waste oil combustion have been investigated in a fluidized-bed combustor (0.1 m ID×2.5 m in height). The excess air ratio and feed rate of waste oil are ranged from 0 to 60% and from 10 to 40 g/min, respectively. The heat transfer coefficient was increased with increasing bed temperature, but it was decreased with increasing excess air ratio. And it had a maximum in the range of the feed rate in the bed region of the fluidized bed. In the freeboard region of the fluidized bed, however, the heat transfer coefficient was increased with increasing excess air ratio and feed rate of waste oil, respectively. The results of this study can be utilized to determine the optimum conditions of fluidized-bed combustor for combustion of waste oil and design as well as scale-up of it.
분체공학 , 유동층 , 고분자 , 재료 ( 무기 , 유기 ) : 유동층 반응기에서 폐 Polystyrene 의 열분해 특성
김준식(Jun Sik Kim),김사중(Sa Jung Kim),윤종성(Jong Sung Yun),강용(Yong Kang),최명재(Myoung Jae Choi) 한국화학공학회 2001 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.39 No.4
Pyrolysis of polystyrene wastes was investigated in a fluidized bed reactor. The feed materials were GPPS(general purpose polystyrene) and EPSW(expanded polystyrene waste). Nitrogen and silica sand were used as a fluidizing gas and a bed material, respectively. Effects of temperature(400-650℃) and gas velocity(0.3-0.6 m/s) on the yields of oil and styrene monomer were determined. It has been found that the yields of oil and styrene monomer exhibited maximum values with increasing pyrolysis temperature or gas velocity in the reactor. The maximum yields of oil and styrene monomer were 93 wt% (600℃) and 65 wt%(500℃), respectively in the beds of GPPS and 95 wt%(600℃) and 60 wt%(550℃), respectively in the beds of EPSW. The pyrolysis temperature affected the composition of products for the pyrolysis of PS and the velocity of fluidization gas affected the determination of product yield in the fluidized bed reactor.