In the drying application of activated alumina, a heating regeneration method is generally employed, and generally, hot nitrogen is used for purging regeneration. This is because of the strong interaction of water and activated alumina, and it is difficult to completely desorb the adsorbed water by other methods. The heating and desorption process includes three steps of heating, rinsing, and cooling. The higher the heating temperature, the more complete the desorption regeneration. Generally, the activated alumina heating regeneration temperature is between 180 and 350 °C. The temperature of the activated alumina column is generally raised to 280 ° C for 4 hours. The heating rate is about 50 ° C per hour. Since high concentrations of water vapor at high temperatures can severely damage the structure of the activated alumina, the activated alumina bed must be flushed with nitrogen, air, product gas or other suitable gas while heating. The flushing gas stress is free of moisture because the amount of water in the flushing gas directly affects the regeneration effect.
The regenerated activated alumina bed must be cooled before the adsorption operation can be carried out. When the bed is flushed with the cooling gas, the gas used is also stressed to be free of moisture, and the flow direction of the cold stripping gas is the same as the direction of the adsorption cycle. When the activated alumina is used for drying a liquid such as propylene, it is necessary to first drive out the liquid of the activated alumina bed without any dead angle. Otherwise, the residual liquid reacts or carbonizes upon heating, so as to seriously affect the performance and operating life of the adsorption cycle.