서지주요정보
내부순환유동층 반응기에서의 폐타이어 가스화 특성 연구 = Gasification characteristics of waste tire in an internally circulating fluidized bed
서명 / 저자 내부순환유동층 반응기에서의 폐타이어 가스화 특성 연구 = Gasification characteristics of waste tire in an internally circulating fluidized bed / 이승엽.
저자명 이승엽 ; Lee, Seung-Yup
발행사항 [대전 : 한국과학기술원, 2000].
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등록번호

8011144

소장위치/청구기호

학술문화관(문화관) 보존서고

MCHE 00024

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초록정보

As the result of the increase of automobiles, disposal of waste tires becomes a critical social problem. Most waste tires are being disposed in landfills. Therefore, several processing routes have been proposed for converting waste tires into useful products. Of course, the gasification route may be an especially attractive solution. Several types of gasifiers have been developed. In particular, fluidized bed is used for gasification to convert coal, biomass, waste tires into fuel or synthesis gas since it has many advantages such as isothermal operation and high heat transfer. But the several problems in a fluidized bed are known to be high carbon loss due to particle shattering and subsequent elutriation of fines, and low conversion of reactant gases owing to gas bypass. To solve these problems, it is suggested that a draft tube has been inserted in a fluidized bed to divide it into two reaction zones. The draft zone is combustion zone with air and the annulus region is gasification zone with steam. By fluidizing solids in a draft tube at a velocity of 7-10 times the minimum fluidizing velocity and in the annulus region at 0.7-1.4 times the minimum fluidizng velocity, it is possible to induce gross circulation of the bed materials between draft tube and annulus region. Circulation of the solid materials within the reactor provides heat transfer from the combustion zone(draft tube) to the gasification zone(annulus region). By installing a gas separator over the draft tube, gas of high calorific value can be produced in the annulus region. In this study, the effects of reaction temperature(750-900℃), steam/C ratio (0.94-1.67) and oxygen/C(0.23-0.47) ratio on gasification reaction have been determined. Typical waste tires have more volatile matter than any other materials. Therefore, the gases from devolatilization reaction influenced the gas yield from gasification reaction. The effect of reaction temperature on gas yield from devolatilization reaction had been investigated with the same condition of gasification in an internally circulating fluidized bed (ICFB). From the gas yield from devolatilization reaction with increasing reaction temperature, the correlation equations of gas yield have been obtained. $y_{H_2,d}$ = -13.01 + 0.023 T $y_{H_2,a}$ = -10.55 + 0.018 T $y_{CO_2,d}$ = -28.13 + 0.045 T $y_{CO_2,a}$ = -26.26 + 0.042 T $y_{CH_4,d}$ = -86.21 + 0.014 T $y_{CH_4,a}$ = -100.33 + 0.016 T $y_{C_2H_4,d}$ = 106.22 - 0.07 T $y_{C_2H_4,a}$ = 114.15 - 0.07 T $y_{C_2H_6,d}$ = 22.76 - 0.02 T $y_{C_2H_6,a}$ = 20.61 - 0.02 T $y_{C_3H_6,d}$ = 34.37 - 0.04 T $y_{C_3H_6,a}$ = 32.29 - 0.03 T (T : ℃) where, $y_i$ is the gas yield of each component (g/kg tire) in draft tube and annulus region. As reaction temperature is increased, the product gas contained 21.53-39.16 % $H_2$, 3.67-12.17 % CO, 34.83-19.63 % $CO_2$, 12.53-15.28 % $CH_4$, 24.98-14.95 % $C_2H_4$, 0.44-0.16 % $C_2H_6$, 1.71-0.12 % $C_3H_6$. The compositions of $H_2$ and CO increase and $CO_2$ decrease with increasing reaction temperature since char-steam gasification reaction is endothermic. With increasing reaction temperature, composition of $CH_4$ increases and other hydrocarbons decreases due to the steam reforming and thermal cracking reaction. The calorific value of product gas which is higher than that of fluidized bed decreases from 24.45 to 21.67 MJ/㎥. The carbon conversion of product gas increases from 27.21 to 34.27 % and gas yield increases as reaction temperature is increased. The cold gas efficiency increases from 46.94 to 51.56 % and it is higher than that of fluiidized bed (Raman et.al, Lee et.al) because of longer particle residence time and higher energy transfer. The composition of product gas is insensitive to steam/C ratio since char steam gasification reaction rate is very slow. The carbon conversion, gas yield, cold gas efficiency are almost constant with increasing steam/C ratio. The compositions of $H_2$ and CO decreased since they recombined with the additional increase of oxygen and $CO_2$ from the enhancement of char combustion reaction. The calorific value and cold gas efficiency decrease from 21.81 to 18.59 MJ/㎥ and from 53.27 to 39.68 %. Since char combustion reaction increases with increasing the oxygen/C ratio, the carbon conversion of product gas increases from 34.13 to 38.16 %. A mathematical model is proposed based on the bed hydrodynamics, reaction kinetics and empirical correlation equations of gas yield obtained from devolatilization to predict the behavior of gasification in an ICFB. The simulated results are compared with the real experimental data. The comparison between the experiment and simulation results exhibits a good agreement so that the proposed model can be used as a guide to predict gasification reaction in an ICFB.'

서지기타정보

서지기타정보
청구기호 {MCHE 00024
형태사항 ix, 109 p. : 삽도 ; 26 cm
언어 한국어
일반주기 부록 : 1, Mathematical program of ICFB model. - 2, Experiment data table
저자명의 영문표기 : Seung-Yup Lee
지도교수의 한글표기 : 김상돈
지도교수의 영문표기 : Sang-Done Kim
학위논문 학위논문(석사) - 한국과학기술원 : 화학공학과,
서지주기 참고문헌 : p. 85-90
주제 가스화
폐타이어
내부순환유동층반응기
모델
Gasification
Waste tire
ICFB
Model
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