By E.J. “Chip” Troxclair, Manager – Gasification, ConocoPhillips
The status quo can be expensive. The market for natural gas is experiencing higher costs and increased price volatility and supplies are likely to remain tight. Meanwhile, the demand for energy, but more importantly clean energy, keeps growing. Factor in the increased use of heavier crude feeds to refineries and the continued dependence on coal-based power generation, and it is no wonder that petroleum coke and coal gasification are becoming more attractive to power generators and refiners alike.
Petcoke supplies are increasing as refiners add capacity, and coal is plentiful and readily accessible in the United States. Through gasification, these lower-cost feedstocks become sources of clean, reliable power. Currently, about 50 percent of America’s electricity is produced from coal alone, so continued use of coal and the increased use of petcoke to produce clean, efficient energy makes great economic sense. Clearly, gasification is a process whose time has come.
Three Decades of Leadership
ConocoPhillips’ award-winning E-Gas Technology leverages over 30 years of gasification technology development, design and commercial operating experience to provide the industry with an ideal solution for petcoke or coal utilization. Among its advantages:
E-Gas Technology is versatile. Its unique, proprietary design can be applied with gas turbine and steam power generation in an integrated gasification combined cycle (IGCC) configuration to produce electric power. The technology can also be used to co-produce synthesis gas and other products such as hydrogen, substitute natural gas (SNG) and chemicals in highly flexible combinations. Plant configurations can employ multiple trains or product prioritization to ensure high reliability of product supply.
E-Gas Technology is highly efficient. The unique two-stage E-Gas process can readily capture about 95 percent of the energy stored in feedstocks, consisting of as much as 80 percent of the chemical energy with an additional 15 percent thermal energy in the form of steam generation. Overall, net plant heat rates, including the auxiliary loads for air separation and other associated process units, are better than supercritical coal designs.
E-Gas Technology is among the cleanest technologies available for coal or petroleum coke-based electric power generation. When compared to conventional pulverized coal-based power generation, E-Gas Technology offers higher system efficiencies, comparable costs and lower emissions. Particulates are removed from the syngas and recovered using a dry particulate recovery process. These solids are recycled to the gasifier, resulting in a near-complete conversion of the carbon in the feedstock. This process offers significant advantages (less water consumption and less wastewater generation) over wet-particulate scrubbing alternatives. Sulfur, mercury and other trace contaminants are removed pre-combustion as well.
The E-Gas process is fuel flexible. To date, E-Gas Technology has significant hours of operation and has gasified over a million tons each of petroleum coke, bituminous coal and low-rank, sub-bituminous coal. One-third of the coal-to-power gasification in the United States is from the E-Gas process on Powder River Basin sub-bituminous coal. The E-Gas process has also demonstrated the ability to switch on the fly from coal to petcoke and back without process modifications.
The E-Gas Technology is operation driven. In its previous installations, the E-Gas Team has had a major role in all phases of the project, from design and construction through start-up and commercial operation. The lessons learned in 80,000 hours of operation involving our own people are already built into the design for the next generation of E-Gas Technology facilities. With partners, ConocoPhillips is continuing an operations and maintenance presence for new customers that desire this support.
The Right Environment for the Future
The ConocoPhillips E-Gas Process can meet stringent environmental standards by removing feedstock impurities that cause air pollution while it converts those feedstocks into clean synthesis gas that can then be used for power generation, hydrogen or chemicals. The process achieves very low levels of SOx and NOx emissions and eliminates all particulates from the syngas prior to the sulfur-removal step. This dry system is inherently more efficient than wet scrubber systems, removing more particulates and avoiding black-water problems, which lead to equipment wear, water consumption and wastewater generation. Mercury is also readily removed from the syngas, with 90 to 95 percent of mercury capture attainable and at a much lower cost than removing mercury from the exhaust of pulverized coal units.
In the process, about 99 percent of the sulfur in the synthesis gas is recovered and converted to elemental sulfur or sulfuric acid that can then be sold in agricultural and other markets. Additionally, the process produces no coal-ash waste since the ash emerges as an inert slag that can be marketed for numerous applications in the construction industry.
Finally, E-Gas Technology offers important advantages in dealing with greenhouse gases like CO2. With the ConocoPhillips process, CO2 emissions are approximately 20 percent lower than emissions from many of the pulverized coal plants currently in operation. The process is more readily adapted to CO2 capture and sequestration than combustion technologies because carbon is removed pre-combustion. Plants utilizing the E-Gas Technology can be efficiently and cost effectively upgraded in the future for the removal of CO2, utilizing existing technologies. The impact of carbon removal on an IGCC plant is less than half the cost of conventional cost combustion technologies and has only about half of the efficiency impact. The result is a lower cost of electricity.
It’s All in the Process
Planning for future needs is becoming increasingly important as environmental standards intensify. The wrong choice today could end up costing millions of dollars in upgrades later, and could even compromise a company’s future. At the same time, significantly higher energy prices have made gasification attractive again, and the technology is even more appealing when electricity producers and refiners recognize it can generate more value from asphalt, petroleum coke and other bottom-of-the-barrel products.
Against that background, the ConocoPhillips E-Gas Technology is well positioned to add value to those applications where solid fuels can be converted into high value products. For 30 years, it has demonstrated the efficiency, fuel and product flexibility and commercial scale operability needed for today’s energy needs. Its superior environmental advantages, high efficiency and relatively low cost make E-Gas Technology the gasification technology of choice for any solid fuel application.