Ethylene Furnace Recovery Quench Oil Circuit Optimization

A 50% reduction in heat dissipation to cooling tower water was achieved in the ethylene furnace recovery section at Beaumont Chemical Plant via improvements in constrained multi-variable control by a team of operations and engineering. Following strategy was employed successfully:

1. The Primary Fractionator cutpoint temperature was maximized against tower overheads and bottoms constraints ­ resulted in lessening the heat losses to CT water.
2. Quench oil flow to downstream distillation tower reboilers was maximized against hydraulic constraints in quench oil circuit while minimizing supplemental reboiler steam.

This amounted to an additional 175,200 MMBTU/Y energy being recovered from quench oil as reboiler duty in downstream distillation towers while unloading the CT exchangers in QO circuit.