The required steam pressure, flow rate, etc. should meet the process design requirements when the molecular sieve is heated. The heating regeneration process in small air separation unit can be judged by the regeneration temperature curve.
In the unloading stage, the adsorption capacity of the molecular sieve decreases due to the pressure drop, and some of the water and carbon dioxide molecules originally adsorbed are desorbed, and the temperature drops.
In the heating stage in small air separation unit, the inlet temperature of dirty nitrogen rises rapidly, but the outlet temperature continues to drop at the beginning and then rises gradually. Because the heat at this point is first consumed in the heat required for desorption, the molecular sieve in the middle and upper part of the bed is desorbed, and the heat is stored in the bed. The factors that influence the regeneration effect in this stage are: nitrogen flow rate, heating time and regeneration temperature. Mainly, the temperature of the dirty nitrogen inlet is monitored.
In the cold-blow stage, the dirty nitrogen outlet temperature continues to rise. At the beginning of this phase, the heat stored in the molecular sieve bed is used to continue desorption of the lower molecular sieve until the highest point of the cold-blow curve - the "peak cold-blow" temperature - which is a sign of complete regeneration of the entire bed. In the exit part is not easy to regenerate completely, if the temperature there can meet the requirements, the internal temperature must be more than the temperature here, it means that the internal regeneration is complete. Therefore, in the cold blowing stage, the peak temperature of the outlet is mainly monitored.
Dear air separation has strict requirements in the design of the small air separation unit, large air separation unit and liquid air separation plant manufacturing process, and the relevant systems are presented with technical specifications.
