Design and Analysis for Sizing and Layout of Piping and Valves for Cold Box System of Helium Refrigerator/Liquefier

Abstract

It is planned to design and develop an indigenous Helium Refrigerator/Liquefier (HRL) of 1 kW cooling capacity at 4.5K at the Institute for Plasma Research, Gandhinagar. For development of HRL a cold box system, consists many cryogenic components, is the most important one. The cold box is used to produce liquid helium at 4.5K temperature. Such a low temperature is achieved in the cold box using equipments like heat exchangers, liquid helium bath, cryogenic valves, turbo expanders, 80K and 20K absorber beds with filters (used for helium gas purifications). These parts of cold box are connected using various pipes and valves. The present work involves the sizing of pipe and valves and layout of components used in the cold box system. The sizing of pipe is done by the pressure drop analysis. During the operation, at low temperature, these components are shrinking and can lead to thermal stress. Thermal stress analysis of various pipes is carried out using CAESAR-II software. Support structures for all components are designed for permissible heat conduction. After deciding size required for vacuum chamber of cold box from layout of component, the design of vacuum chamber is done according to American Standard for Mechanical Engineering (ASME), section VIII, division I. Reinforcement requirement is checked for opening and pipe penetrations. Saddle support is used to support a cold box. Structural analysis is done in ANSYS for support structure and vacuum vessel.