Provalve trays boost amine regenerator capacity
The Problem
The Tower and the Solution
The Bottom Line
The Problem
Just prior to a major turnaround, a refiner decided to update one of its amine regenerator columns. By increasing the sieve hole area from 8% to nearly 14%, the refiner hoped to provide a much-needed capacity boost. However, calculations based on Fractionation Research Inc. (FRI) correlations showed that the new configuration would only increase capacity modestly and not enough to get the sieve trays below 100% of flood. In response, Saint-Gobain NorPro proposed a solution that would significantly boost capacity without postponing the scheduled turnaround at minimal cost.
The Tower and the Solution
The refinery's north amine regenerator column was a 126-in. (3200-mm) ID column with 23 two-pass trays on 24-in. (610-mm) tray spacing. The bubble cap trays above the flashing feed were not to be modified.
The calculations showed that Provalve trays would provide a significant capacity increase, with the percent flood less than 79%. In addition, the turndown capabilities of the Provalve trays was far superior to the originally proposed sieve trays with 14% hole area.
To minimize costs, the NorPro design reused the existing downcomers and tower attachments, which were adequate, and replaced only the tray decks.
The Bottom Line
The Provalve tray decks fit perfectly to the existing downcomers and attachments, which had been supplied years before by another equipment manufacturer. In fact, the refinery inspector remarked that the fit and quality of workmanship were excellent.
The refiner has reported that the revamped amine regenerator has been working quite well. In post-audit testing conducted by the refinery, the column has demonstrated the design capacity and pressure drop predicted by Saint-Gobain NorPro. In addition, the refiner was especially pleased with the operating flexibility the Provalve trays afforded.
"The unit was run in a million different directions, and the Provalve trays came through it well," the refiner said. As a result, the refiner has been able to optimize operations to save on steam costs.
Based on the positive results in the north column, the refiner has decided to perform a similar revamp in the south amine regenerator column.