The increased presence of heavy crudes on the market has led many refiners to focus on technology suitable for upgrading these discounted, heavy feedstocks. Coking is a major bottom-of-the-barrel upgrading process whose popularity has risen steadily in response to heavier crude supplies and the dwindling demand for residual fuel oils. This process converts heavy feedstocks such as vacuum residuals, heavy cracked gas oils, and decanted oils into gas, LPG, relatively low-boiling distillates, and solid coke. Furthermore, petroleum coke, a byproduct of coking, is finding use in a variety of markets throughout the industrial sector. Historically, strong gasoline markets and diverse outlets for petroleum coke made delayed coking the most prolific residue upgrading technique; however, some of these market factors are changing as diesel demand is outpacing gasoline and some outlets for petcoke have or will come under scrutiny with new SOX and CO2 regulations. Operational improvements and technical advances must be applied by refiners to support continued growth of coking technology as it is utilized in plants dealing with difficult feedstocks, tight production margins, demanding efficiency standards, and stringent environmental constraints.
As the worldwide crude slate shifts to heavy and extra-heavy refinery feeds, refiners will need to take advantage of various bottoms upgrading techniques to cut deeper into the crude barrel to yield valuable distillate products. Many of these technologies have been around since the 1950s or even earlier and have reached commercial maturity. Some of the more advanced processes have recently evolved as modifications of conventional processes to deal with the increased resid contents of incoming feeds. Finally, the development of highly integrated processing schemes has aided refiners in economically processing resid streams.
Due to the flexibility of the process, coking has emerged as the leading technology in residue upgrading both in the refinery and in upstream heavy oil upgrading plants. Several significant trends have emerged that can be identified by analyzing the recent research work related to coking processes. Delayed coking has received much of this focus, particularly with regards to innovations that increase product yields and quality as well as integrated processing options that incorporate delayed coking with other refining technologies such as hydroprocessing, solvent deasphalting, and catalytic cracking. Recent research work has resulted in the introduction of new furnace designs as well as other pieces of equipment and devices that can provide environmental, energy consumption, safety, reliability and economic benefits. Significant resources have also been invested in efforts to develop defoamers and anti-coking agents for use in the delayed coking process. And researchers have investigated drum cracking that occurs during coking operations and have utilized modeling for drum fatigue life prediction.
Additionally, the coking section features the latest trends and technology offerings, including:
- Updated global coking market including the impact of the new IMO spec on coking capacity, current issues regarding petcoke exporting/importing, and the inadequate supply of needle coke and its impact on global prices of graphite electrodes;
- Update on the coking units utilizing the SYDEC technology of Amec Foster Wheeler and Honeywell UOP;
- Revamping a delayed coker with ThruPlus technology from Bechtel Hydrocarbon Technology Solutions (BHTS);
- ThruPlus ELECTROPOWER nuclear delayed coking process from BHTS;
- Update on the delayed coking units offered by CLG;
- CLG Feasibility study for the revamp of a coking unit to boost its processing capacity;
- Benefits of gasification incorporation into the FLEXICOKING process from ExxonMobil;
- Update on FLEXICOKING units including a refinery upgrade project in Greece;
- Center feed device from DeltaValve; and
- A discussion of the latest patent applications and research papers regarding coking technology, including delayed coking and fluidized bed coking.