Simulation of Turboexpander Based Nitrogen Liquefier

ABSTRACT

In spite of nearly half a century of R&D experience, our country is still dependent on imports for most of its needs in cryogenic refrigerators and liquefiers. These products are proprietary in nature which makes it very expensive for its cost and maintenance. So it is imperative that our country develops an indigenous nitrogen liquefier to meet the need of liquid nitrogen. With the support from the Department of Atomic Energy, our institute has initiated a programme on development and study of a nitrogen liquefier of intermediate capacity (in the range of 10-50 litres/hr) by using technologies already developed in our country. The process is based on a suitable modified Claude cycle which minimizes the number of heat exchangers and also takes care to accommodate the inhouse developed turboexpander. The process design is carried out using the standard calculation procedure and is validated by using process simulation software, Aspen. The thermodynamic parameters (temperature, pressure, pinch point temperature) are evaluated to obtain the optimum mass fraction through turboexpander for maximum liquid yield. Parametric study is carried out to access the role of different component efficiencies in predicting overall system efficiency at the design and off design conditions.

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