Dynamic simulation of modified claude cycle

The dynamic simulation of a modified Claude cycle has been carried out to liquefy Nitrogen. The cycle consists of two heat exchangers, one turboexpander and one J-T Valve. A phase separator is present to separate the liquid and vapor. The simulation model has been built using commercially available software Aspen Hysys® of Aspen Tech company. The paper aims to study the dynamic behavior to estimate the cool down time to get the liquid. To get the accurate results the sizing data of the heat exchangers and phase separator are given as input to the model. A level controller also used to maintain the liquid level of the phase separator. The transient behavior of streams inside the heat exchangers, the J-T valve, turboexpander and liquid volume percentage in the phase separator are discussed. This knowledge of simulation can be utilized for optimized operation of the plant.