CDU-VDU REVAMPS

Every crude or vacuum unit revamp is unique because no two existing units are the same. Revamp requirements are determined by existing process and equipment design and desired crude blend flexibility. All Process Consulting Services revamps begin with a thorough test run and detailed analysis of the existing unit. Although a detailed test run and subsequent analysis require time and money for planning, execution, and refinery personnel time, the resulting performance analysis is critical for determining both the opportunities and potential problems within the unit. Our experience coordinating over 75 test runs has allowed Process Consulting Services to develop robust and efficient systems for identifying and capturing the significant volume of data needed to determine the performance of current equipment and the changes necessary to achieve revamp goals.

Although we strive to identify a path to achieving a refiner’s particular revamp goals, sometimes these aspirations must be tempered with reality. In some cases more investment than expected is needed to meet goals. In other instances, goals must be adjusted to meet the realities presented by poor existing unit designs. Process Consulting Services can help a refiner determine which revamp options can be completed feasibly and economically.

In the United States, refiners want to process high volumes of tight sands crudes such as Eagle Ford without spending enough money to mitigate the process risks of running shale crudes. Some refiners expect run lengths of 7-8 years between scheduled turnarounds but do not make the changes needed to maintain adequate velocities in their heaters and heat exchangers. Without taking the time and investing the capital to ensure that the refinery is prepared to run these crudes, expecting long run lengths is simply unreasonable. As increasing volumes of these crudes are processed in higher blend percentages, more and more refiners are experiencing unexpected shutdowns, sometimes as often as every six months.

Internationally, refiners are seeing more opportunities to process heavy and extra-heavy crudes. For the past thirty years US refiners have been processing these crudes and Process Consulting Services has learned how to do this reliably and efficiently. CDU/VDUs designed for light or medium gravity crudes cannot reliably process heavier crudes to meet diesel and vacuum gas oil yield expectations. Common problems that we have encountered over the years include poor desalting, exchanger fouling, crude and vacuum tower overhead system fouling and corrosion, low diesel and vacuum gas oil (VGO) recovery, and heater coking. When North American refiners first began processing these heavy crudes they learned these lessons the hard way. Process Consulting Services has the experience and expertise to make sure that international refiners can benefit from the lessons learned here in the US rather than repeating the same mistakes and experiencing short run length and low product yields. There is a belief that anybody can design a CDU/VDU because they are open art processes. While this is true, not all CDU/VDUs are the same, and US refiners have learned this lesson the hard way.