Estimation of Performance of Absorption/Desorption System for Regenerating Waste Water From Industrial Process

More reduction in energy consumption is requested to the industrial processes. In particular, large quantity of waste water at low temperature is released from chemical and steel processes. In this study, adsorption/desorption process of zeolite and water pair were selected to generate steam from water at low temperature. Contacting water liquid and zeolite directly, adsorption heat released from zeolite makes excess water evaporate. Basic experiments for adsorption/desorption process were carried out. First of all, adsorbents with different type were tested to find the candidate of the proposed system, and then suitable adsorbent was selected. From the basic adsorption experiment, generation of steam from the water liquid was confirmed by the proposed system. In the desorption process, hot dry gas was introduced to the adsorbent. The effect of gas temperature and its flow rate was investigated. The performance of the system was theoretically investigated based on overall heat and mass balances. As a result, the ratio of enthalpy of recovered steam of 140°C to input waste water of 80°C was around 6 when adsorption process was only considered. On the other hand, the ratio was 0.57 when waste heat was utilized for the desorption process. However if waste heat such as exhaust gas can be utilized for the desorption process, the ratio, that is, the efficiency would increase.