Impact of Feedstock Variations on the Performance of Multi-Component Refrigeration Compressors

Conventional ethylene technology uses three separate refrigeration compressor systems. Lummus has developed a patented mixed refrigeration system that provides the refrigeration needs from ambient to -140°C.

Based on the inherent process flexibility with respect to feedstock variations, a significant number of commercially successful plant applications have been realized. The Binary/Tertiary Refrigeration Technology has been applied to over 20 grassroots and revamped olefins plant designs and is currently in operation at 11 different locations.

This paper will introduce and explain the basic design features and desired performance characteristics of the mixed refrigerant compressor system which have resulted in reliable, cost effective solutions for the olefins industry.

Application of binary or tertiary refrigeration systems reduces the overall number of compressors and driver casings with significant capital savings. However, certain engineering considerations must be addressed in the compressor design. Specifically, low design temperatures similar to ethylene/propylene compressors, and high design pressures, similar to methane compressors, must be simultaneously satisfied. Furthermore, side loads are frequently applied for refrigeration compressors, resulting in very small flow passages in the binary and tertiary compressor designs. Thus, suitable design and manufacturing considerations must be incorporated.