PITA Fiscal Year 2013 Projects

Continuous Desiccation System for Cryogenic Cooling

Lead University: Lehigh University
PI: James T. Hsu, Dept. of Chemical Engineering
Co-PI(s): Lori Herz, Bioengineering Program
PA Industry: Dynalene Inc

The objective of his project is to design and optimize a continuous desiccation system for cryogenic cooling. In the operation of a cryogenic cooling system (normally operated in the range of -50 to -100 C) in which the refrigerant is used or processed, high concentration of entrapped frozen water can cause considerable difficulty by either clogging or obstructing the free passage of fluid through process piping. Also, the entrapped water can decrease the heat transfer capability of the cryogenic cooling system. Furthermore, water tends to form hydrated sludge’s which are difficult, if not entirely impossible, to pump. Excessive quantities of entrapped water can result from such factors as: 1) inadequate drying of refrigerant or improper storage of factory, 2) storage tank vent breathing, 3) inadequate total suction head in pumps, 4) process piping exposed to water moisture during assembly, installation or repair operations. Thus, in many refrigeration systems, moisture levels below 100 ppm at 70 F must be maintained if problems such as sludge formation, acid and icing in the cooling coils are to be avoided.

The desiccation systems to remove water currently used are operated in a batch mode or as a slip-stream from the main fluid stream. There is no desiccation system commercially available that is continuous. In this project a continuous desiccation system will be developed for cryogenic cooling system. The water will be removed by passing the refrigerant through a desiccant column which is packed with adsorbents. A continuous desiccation system will be developed based on swing operation with two columns, one for dewatering and the other one for regeneration. When the operating column is saturated with water then the regenerated one will be switched for dewatering operation.