Debottlenecking Hydraulic Limits

One example of hydraulic debottlenecking an aromatics extraction unit was particularly dramatic. A market supply disruption raised the price of benzene dramatically. All efforts were made to increase the unit charge rate and maximize benzene production. However, the benzene rundown line became the unit-limiting item. Operations then decided to turn on the spare pump. This increased the capacity by approximately 10%. There was room for more, however. Operations typically ran down a single rundown line into a day tank to minimize the amount of offspec produced by an upset. Another set of day tanks had a separate day tank. So operations began using the second rundown line in parallel. This greatly debottlenecked the system. At the higher flow rates, the control valve pressure drop became limiting so the trim in the control valve was replaced. The combination of all of these items increased the maximum benzene production rate by over 35%. And the only money spent was for the new control valve trim. The payout for replacing the control valve trim would be measured in minutes !