FCC volume expansion = 100 – (C3+ Liquid Yield)
C3+ liquid yield, vol% FF = 100*{sum of bpd of all liquid products (C3 through decanted oil) / feed bpd}
C3+ liquid yield is typically expressed for standard cut yields meaning that the C3 product lost to dry gas is added to the actual C3 recovered.
For conventional FCC units the value of C3+ liquid will range from 106 – 114 vol% FF. The actual value is dependent on feed quality and conversion. Low hydrogen content feeds (coker gas oils or resids) will have low vakyes high hydrogen content feeds (hydrotreated gas oils or tight oils will have high values). When comparing your unit to others you must be careful to only compare it to units with similar feed. Untreated virgin gas oils typically have a value of 110 to 112 vol% of fresh feed at 650-F conversion between about 75 to 80 vol% FF.
