Determination of characteristic desorption temperature by thermal-pulse regeneration: A case study of water-activated alumina system

Abstract

This study demonstrates that the characteristic temperature can be determined from analysis of the effluent temperature curves from a fixed bed with adsorbents. Since the continuous, accurate measurement of temperature is considerably easier to achieve than that of isotherm and concentration, it basically provides a novel alternative approach to determine the characteristic temperature of an adsorption system. The thermal-pulse regeneration method is commonly used for conserving thermal energy in industrial applications of air prepurification units based on the temperature swing process. The peak temperature of the residual thermal pulse (RTP), namely the cooling-peak, is usually considered an important reference for evaluating the degree of regeneration completion and the level of heat utilization efficiency. A small-scale experimental system was set up, and a set of experimental runs was performed to investigate the relationships between the RTP and the regeneration efficiency. Under the same initial test-bed conditions, regeneration experiments were carried out at various injected thermal pulse (ITP) magnitudes, and an interesting result was observed; that is, as the ITP magnitude becomes smaller, the occurrence times of the cooling peaks exhibit a C-shaped variation tendency with a minimum time point. Concentration analysis indicates that the minimum time point is given by the optimum run of regeneration, and therefore the cooling-peak that gives the minimum time point is the optimum regeneration temperature (the characteristic temperature) of the adsorbent-adsorbate system.