Process design of cryogenic system using ASPENHYSYS simulation

Abstract

The thermodynamic efficiency of any process is dependant upon following factors:
(a) The efficiency of independent components used.
(b) Operating condition i.e. variation of input parameter(like temperature, Pressure etc)
To improve the efficiency of any process, efficiency of component is fixed (it is dependant upon level of technology available and cost of equipment), thus we are left with optimizing operating condition which is under our control. This paper presents analysis of thermodynamic cycle
commonly used for liquefaction of Nitrogen (N2) under given set of operating condition and efficiencies. The liquefying temperature of Nitrogen being 77.36K is taken into consideration.
The cycles considered are:
(a) Simple LINDE-HAMPSON cycle
(b) CLAUDE cycle
Computer-aided process design programs, often referred to as process simulators, flow sheet simulators, or flow sheeting packages, are widely used in process design. Aspen
HYSYS by Aspen Technology is one of the major process simulators that are widely used in chemical and thermodynamic process industries today. It specializes on steadystate analysis. System simulation is the calculation of operating variables such as pressure, temperature and
flow rates of energy and fluids in a thermal system operating in a steady state. The equations for performance characteristics of the components and thermodynamic properties along with energy and mass balance form a set of
simultaneous equations relating the operating variables. The mathematical description of system simulation is that of solving these set of simultaneous equations which may be
non-linear in nature.
Cryogenics is the branch of engineering that is applied to very low temperature refrigeration applications such as in liquefaction of gases and in the study of physical phenomenon at temperature of absolute zero. The various cryogenic cycles as LINDE cycle, CLAUDE cycle etc
govern the liquefaction of various industrial gases as Nitrogen,Helium etc. The following work aims to simulate the cryogenic cycles with the help of the simulation tool ASPEN HYSYS where all calculations are done at steady state and the results hence obtained.