Reduced coke yield and increased operating flexibility. For many years, delayed coking units have played an important role in oil refineries as one of the most cost effective processes to convert vacuum residue into more valuable products. The delayed coking yields are the result of thermal reactions and are mainly a function of feed properties and operating conditions such as furnace outlet temperature and drum pressure; however, this process results in coke yields from 20-40% of feed.

Process Description
Albemarle and OptiFuel Technology Group (OFTG) have developed and optimized a technology, referred to as OptiFuel Technology (licensed by Albemarle), employing a coker additive to reduce the coke yield and increase liquid yields in these delayed cokers. OptiFuel’s patented technology along with Albemarle’s proprietary coker additives not only improve performance and profitability, but also increase flexibility that can be used to reduce bottlenecks, increase throughput, and produce more valuable products. Figure 1 shows a schematic of the OptiFuel Technology main process components.

The OptiFuel Technology Process invented by OFTG, consists of injection of an additive into the vapor region at the top of a coker drum. The additive mixture is comprised of a liquid portion (the carrier) and a proprietary solids additive supplied by Albemarle. In addition to reducing coke yields, it is also possible to apply the technology for debottlenecking purposes.

Performance Benefits
The potential benefits of this technology have been demonstrated at a pilot facility using a test matrix capturing a wide range of operating conditions with and without Optifuel additive. Testing studies were completed at Pennsylvania State University (PSU) with two different coker feeds (A and B) described in Table 1 and eight different additive formulations.