Los Angeles, CA, U.S.

Hydrotreating and Hydrocracking Reactor Replacement

​Fluor installed three new reactors at Unocal's Los Angeles, California refinery as part of its hydrotreating and hydrocracking reactor replacement project.

The reactor replacement work involved installation of three new reactors in a conventional two-stage Unicracking™ configuration. The design was based on achieving 100 percent conversion to naphtha and lighter products.

In addition, Fluor completed construction of a selective catalyst reduction unit for the hydrogen furnace and completed three NOx reduction projects during the shutdown period.

Client's Challenge

​An especially significant challenge of this effort was that all work had to be performed in an operating refinery to very stringent OSHA, Fluor and Unocal safety rules and regulations. The installation would take place in a confined space, and all preparation had to be accomplished while the plant, a high-pressure, high-temperature process producing hydrogen and various hydrocarbons, was in operation.

Fluor's Solution

It took 18 months of continual coordination, planning and brainstorming to safely ship, haul, offload and erect the three vessels. The new reactors and structures were designed using Fluor's 3D CAD Plant Design System. A three-dimensional model was made of the lift to identify and address potential problems prior to actual construction.

The extremely confined area where the new reactors were installed called for an innovative construction approach. A series of transporters and transfer beams were used to transport and position the reactors. The reactors were then hoisted into place using the accompanying structure. Ranging in size from 380 to 580 tons, the three new reactor vessels were erected and the erecting beams dismantled within 15 days.


​As many as half of the project construction tasks were completed prior to the shutdown. Actual shutdown and turnaround activities were completed in 43 days, achieving over 500,000 hours without a lost-time accident. Workers peaked at 750 including staff, direct hires and subcontractors.

Fluor's safety record and ability to manage complex refinery projects during operating conditions were key factors in the success of Unocal's hydrotreater upgrade and reactor replacement project.