Question 75: Do you draw liquid hydrocarbon from the overhead system in the vacuum tower after the pre-condenser? What is the operating temperature of the tower overhead? What issues do you observe?
Andrew W. Sloley (CH2M HILL)
At vacuum tower top temperatures over 135-150°F some material heavy enough to condense after the pre-condenser goes overhead. In units with extremely paraffinic feeds the hydrocarbon can form wax in the pre-condenser, leading to reduced heat transfer and higher vacuum tower pressures. Other units get liquid carryover from the upper pumparound. This liquid shows up in the precondenser liquid.
Year
2014