(34c) Troubleshooting & Optimizing Refining Vacuum Towers

Case Study #1: Tower pressure is a crucial parameter for optimum VDU column performance.

Operating pressure of a VDU column located in Europe was slowly rising, making vacuum residue quality unacceptable for bitumen production. Client suspected vacuum system efficiency was decreasing and planned for unit shutdown. In order to shorten shutdown duration, GTI Solutions (GTIS) was invited to perform a plant survey and to identify the faulty equipment.

GTIS not only identified the root cause but also provided solutions without a plant shutdown, saving client time and money.

This study demonstrates how a methodological troubleshooting exercise can help plant operators determine the root causes of VDU column malperformance and implement correct solutions.

Case Study #2: A refinery in Japan processing a mixture of Middle East crudes had experienced coking in the wash bed of a vacuum tower. Product qualities had gradually reduced whereas pressure drops increased over time. This occurrence repeated between plant turnarounds with varying degree of run-lengths and product qualities. As a corrective measure, the refinery was tasked to identify optimal packings for the wash oil bed.

This case study demonstrates the importance of packing selection, especially for the wash bed of a vacuum tower. Results from a series of plant turnarounds, where the wash bed was packed with various packing textures, will be presented.