Gasification Systems - Feed Systems
Modification of the Developmental Pressure Decoupled Advanced Coal (PDAC) Feeder
National Carbon Capture Center at the Power Systems Development Facility
Southern Company Services, Inc.
Project Number: 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.
Feed systems research is underway to reduce the cost and increase the efficiency, through design and advanced plant integration, of fuel and oxygen feed to commercial gasifiers. High-pressure solid feed systems will expand the use of our nation's Western low-cost, low-rank coals for high-pressure gasifiers (currently limited to more expensive fuel), enable co-feeding of coal with other advantageous fuels (such as biomass), and encourage higher pressure (and therefore more efficient) operation of dry feed gasifiers. ITM technology will lower the cost of oxygen production through reduced capital costs, and result in more efficient IGCC power plants through turbine integration, as compared to today’s commercially available, energy intensive technology for oxygen production—cryogenic air separation.
The National Carbon Capture Center (NCCC) is developing the Pressure Decoupled Advanced Coal (PDAC) feeder to operate with a wide variety of coals and biomass feedstocks to increase the fuel flexibility of integrated gasification combined cycle (IGCC) systems. The PDAC feeder is a non-mechanical feed control device with no moving parts which combines successful novel concepts (developed for continuous ash depressurization systems) with traditional designs for flow rate control. The driving force for solids flow is a pressure differential, and the solids flow is metered by the conveying gas. Successful development of high-pressure solid feed systems enables utilization of the Nation's large reserves of low-cost, low-rank coals in dry feeding of high-pressure gasifiers, allows for the co-feeding of coal with other advantageous fuels (such as biomass), and provides for higher pressure (and therefore more efficient) operation of dry-feed gasifiers.
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