CCS and Power Systems
Advanced Energy Systems - Gasification Systems
Long-Term Candle Filter Tests
Performer: Southern Company Services, Inc.
Project No: NT0000749
Program Background and Project Benefits
Gasification is used to convert a solid feedstock, such as coal, petcoke, or biomass, into a gaseous form, referred to as synthesis gas or syngas, which is primarily hydrogen and carbon monoxide. With gasification-based technologies, pollutants can be captured and disposed of or converted to useful products. Gasification can generate clean power by adding steam to the syngas in a water-gas-shift reactor to convert the carbon monoxide to carbon dioxide (CO2) and to produce additional hydrogen. The hydrogen and CO2 are separated—the hydrogen is used to make power and the CO2 is sent to storage, converted to useful products or used for EOR. In addition to efficiently producing electric power, a wide range of transportation fuels and chemicals can be produced from the cleaned syngas, thereby providing the flexibility needed to capitalize on the changing economic market. As a result, gasification provides a flexible technology option for using domestically available resources while meeting future environmental emission standards. Polygeneration plants that produce multiple products are uniquely possible with gasification technologies. The Gasification Systems program is developing technologies in three key areas to reduce the cost and increase the efficiency of producing syngas: (1) Feed Systems, (2) Gasifier Optimization and Plant Supporting Systems, and (3) Syngas Processing Systems.
Syngas processing research and development underway emphasizes technologies that can be efficiently integrated into the plant, optimized with the temperature and pressure requirements of other systems, and meet product delivery specifications. A major cost element in gasification plants is converting raw syngas into a pure and specific gas used to create the plant's target product suite. High-hydrogen, low-methane, ultraclean syngas is versatile and can be used for power production with CO2 capture, fuels or chemicals production, and for many polygeneration applications. The technologies being developed are focused on high-efficiency processes that operate at moderate to high temperatures and clean syngas of all contaminants to the extremely low levels needed for chemical production—often significantly lower than the U.S. Environmental Protection Agency (EPA) required levels for power plants.
The National Carbon Capture Center (NCCC) is working to develop candle filters that can efficiently remove particulates from syngas at varying temperatures, using low-cost materials and innovative design. Integrated gasification combined cycle (IGCC) plants produce a low-to-medium-BTU fuel gas (syngas) that must pass through filters to separate the fine fly ash particles from the hot gas so that these harmful by-products are deposited on the filter tubes, and do not reach the high-speed gas turbine during combustion or the atmosphere as particulate emissions. Testing and evaluation of long-term material performance of particulate control device (PCD) filter elements is performed at the NCCC using a commercially available Siemens PCD. Located downstream of the primary gas cooler, the PCD houses up to 91 candle-type filter elements. Successful development of durable, economical, high-temperature, hot gas filter systems will reduce cost and increase the efficiency by improving IGCC plant reliability, availability and maintainability.