How to judge whether the heating regeneration of molecular sieve is complete?

First of all, the steam pressure and flow required for heating the molecular sieve must meet the requirements of the process design.

 

The heating regeneration process can be judged by the regeneration temperature curve, as shown in the figure. In the figure, AB is the pressure relief stage. As the pressure drops, the adsorption capacity of the molecular sieve is reduced, and the originally adsorbed water and carbon dioxide molecules are partially desorbed, and the temperature drops.



BC is the heating stage. The inlet temperature of the polluted nitrogen increases rapidly, but the outlet temperature will continue to decrease at first, and then gradually increase. Because the heat at this time is first consumed on the heat required for desorption, the middle and upper molecular sieve of the bed is desorbed and the heat is stored in the bed. The factors affecting the regeneration effect at this stage are: nitrogen flow, heating time and regeneration temperature. It mainly monitors the inlet temperature of polluted nitrogen.



CD is the cold blowing stage. The outlet temperature of polluted nitrogen will continue to rise. At the beginning of this stage, the heat stored in the molecular sieve bed is used to continue to desorb the lower molecular sieve until the cold blowing curve takes up the highest value-the "cold blowing peak" temperature is a sign of the complete regeneration of the entire bed. Because it is the least easy to regenerate completely at the exit site. If the temperature here can meet the requirements, the internal temperature must exceed this temperature, indicating that the internal regeneration has been completed. Therefore, during the cold blowing stage, the peak temperature of the outlet is mainly monitored.