H<sub>2</sub>/CO계의 흡착탑 수치모사 및 흡착 동특성

양재영; 한상섭; 조찬휘; 이한주

HWAHAK KONGHAK, Vol.33, No.1, 56-68, February, 1995

Export Citation

H₂/CO계의 흡착탑 수치모사 및 흡착 동특성

Numerical Simulation of Adsorption Bed and Bed Dynamics for H₂/CO Gas Mixture

양재영, 한상섭, 조찬휘, 이한주

초록

흡착탑의 모사를 위해 H₂와 CO 기체에 대해 zeolite 5A 흡착제를 이용하여 uptake curve를 얻어서 고체확산 모형에 적용하고, 실험치와 fitting함으로써 유효확산계수를 구하였으며, 이 계수를 이용하여 흡착속도식(Gluec-kauf LDF 모형, Vermeulen 모형, Nakao-Suzuki모형)의 특성을 파악하고 흡착탑의 모사에 적용하여 파괴곡선의 동특성을 고찰하였다. H₂/CO 혼합물에 대해서 LRC 모델로 흡착평형을 예측하여 좋은 결과를 얻었으며, 이 모델을 흡착탑의 모사에 사용하였다. T.G.A. 방법에 의한 uptake curve와 각 흡착속도식에 의한 것을 비교한 결과 LDF모형은 흡착초기에 실제 흡착량 보다 낮은 값을 예측하나 Vermeulen 모형은 높은 값을 예측하였으며, 특히 Glueckauf 모형은 D_et/R_p²>0.1조건하에서 정확한 값을 예측하는 특성을 보였다. 흡착탑의 모사를 위해 FCS(flux corrected scheme)을 이용하였으며, 각 모형으로 파과곡선을 예측한 결과 uptake curve를 fitting하여 얻어낸 최적의 LDF 계수(K)를 이용한 Nakao-Suzuki 모형이 가장 좋은 예측을 하였으며 Langmuir isothem 보다는 LRC(Loading Ratio Correlation)를 이용한 모사가 실험치에 보다 가까웠다. 등온조건하의 파과곡선과 비교한 결과 본 계의 흡착탑의 모사에 에너지수지식이 필수적이며, 탑 내 온도의 상승후 하강하는 변화의 여향으로 파과곡선은 긴 꼬리를 가지는 것으로 사료된다.

To study the dynamic behavior of an adsorption bed, adsorption equilibrium was investigated first and uptake curves were obtained in order to determine effective diffusivity(defined by solid diffusion model), and then the effective diffusivity was used for studying characteristics of sorption rate and simulating the adsorption bed behavior using adsorption rate models by LDF, Vermeulen, and Nakao-Suzuki. LRC isotherm model predicted adsorption equilibrium of the gas mixture(H2/CO)well and was employed in the simulation of an adsorption bed. Comparison of uptake curves obtained by T.G.A. method with those estimated by adsorption rate models showed the following; LDF model predicted lower adsorption amount than experimental by T.G.A. method at the early stage of adsorption, while Vermeulen model predicted higher. However, Glueckauf LDF model showed good agreement with experimental data under the condition of D_et/R_p²>0.1. FCS(flux corrected scheme)was used satisfactorily for eliminating numerical oscillation in simulation of an adsorption bed. A theoretical analysis by Nakao-Suzuki model with optimum coefficient, K, obtained by matching the experimental uptake curve, showed that it provided a satisfactory prediction of the observed breakthrough curve in comparison with other models. LRC was more suitable to predict breakthrough curve than Langmuir isotherm. From the result of breakthrough curve under isothermal conditions, it was shown that energy balance should be included in the simulation of the adsorption bed behavior and breakthrough curve had a long tail probably caused by the adsorption heat and heat loss.

[References]

Alpay E, Scott DM, Chem. Eng. Sci., 47(2), 499 (1992)
Battrum MJ, Thomas WJ, Trans. IChemE., 69(A), 119 (1991)
Buzanowski MA, Yang RT, Chem. Eng. Sci., 44(11), 2683 (1989)
Buzanowski MA, Yang RT, Chem. Eng. Sci., 46(10), 2589 (1991)
Cen P, Yang RT, Ind. Eng. Chem. Fundam., 25, 758 (1986)
Chihara K, Suzuki M, J. Chem. Eng. Jpn., 16(1), 53 (1983)
Crank J, "The Mathematics of Diffusion," 2nd Ed., Clarendon Press (1975)
Do Dd, Mayfield PLJ, AIChE J., 33(8), 1392 (1987)
Do DD, Rice RG, AIChE J., 32(1), 149 (1986)
Doong SJ, Yang RT, AIChE J., 32(3), 397 (1986)
Garg DR, Ruthven DM, Chem. Eng. Sci., 28, 791 (1973)
Glueckauf E, Trans. Faraday Soc., 51, 1540 (1955)
Kikkinides ES, Yang RT, Chem. Eng. Sci., 48(6), 1169 (1993)
Liaw CH, Wang JSP, Greenkorn RA, Chao KC, AIChE J., 25, 376 (1979)

[Referenced By]

[1] Alpay E, Scott DM, Chem. Eng. Sci., 47(2), 499 (1992)

[2] Battrum MJ, Thomas WJ, Trans. IChemE., 69(A), 119 (1991)

[3] Buzanowski MA, Yang RT, Chem. Eng. Sci., 44(11), 2683 (1989)

[4] Buzanowski MA, Yang RT, Chem. Eng. Sci., 46(10), 2589 (1991)

[5] Cen P, Yang RT, Ind. Eng. Chem. Fundam., 25, 758 (1986)

[6] Chihara K, Suzuki M, J. Chem. Eng. Jpn., 16(1), 53 (1983)

[7] Crank J, "The Mathematics of Diffusion," 2nd Ed., Clarendon Press (1975)

[8] Do Dd, Mayfield PLJ, AIChE J., 33(8), 1392 (1987)

[9] Do DD, Rice RG, AIChE J., 32(1), 149 (1986)

[10] Doong SJ, Yang RT, AIChE J., 32(3), 397 (1986)

[11] Garg DR, Ruthven DM, Chem. Eng. Sci., 28, 791 (1973)

[12] Glueckauf E, Trans. Faraday Soc., 51, 1540 (1955)

[13] Kikkinides ES, Yang RT, Chem. Eng. Sci., 48(6), 1169 (1993)

[14] Liaw CH, Wang JSP, Greenkorn RA, Chao KC, AIChE J., 25, 376 (1979)