(146b) Self-Heat Recuperative Seawater Desalination Process Using Fluidized Bed

Recently, it is presumed that there will be a serious shortage of water in several years later due to the high growth rate of population and industrial development. To alleviate the water shortage, more attention has been paid to desalination technology. One of the typical desalination processes is a multi-stage flash desalination. This process is categorized as thermal desalination process because it produces pure water by evaporation. The thermal process has the following two major advantages; seawater quality does not seriously affect the operation condition and product water salinity is low enough for industrial usage. However, this process consumes a lot of energy, thus the remarkable energy saving technology of thermal process is in great demand. So far, to reduce the energy consumption, we proposed a novel thermal desalination based on self-heat recuperation, which is a method for energy saving. By a process simulator, it was revealed that the proposed desalination process energy consumption is reduced to 1/4 of conventional thermal desalination process. Furthermore, it was elucidated that the specific energy consumption decreased as the recovery ratio (= the product water flow rate / the feed water flow rate) increased. However, in the thermal desalination process with high recovery ratio, a problem of scale deposition, which leads to a reduction of heat transfer efficiency in heat exchanger occurs.

In this research we introduce self-heat recuperative seawater desalination process with fluidized bed for solving the problem. In the desalination process, the fluidized bed is employed as an evaporator. It might be seen that this process has the following advantages; good heat transfer properties and less scale deposition because of water evaporation taking place on heated particles in fluidized bed evaporator.

In addition, we investigated the influence on the specific energy consumption and feasibility to the society of the proposed desalination process.