ethylene boil off gas use propylene as refrigerant

good day everyone,

did anyone here work with BOG system ? especially for ethylene BOG.
I just start working with BOG system and want to know what is fundamental design for boil off gas system. I use liquid propylene for refrigerant unit to liquefaction ethylene.

liquid propylene are compressed by screw pump, beside ethylene compressed use two stage reciprocating compressors.

thank you for valuable sharing,