Subtask 3.12 - Oxygen-Fired CFBC

Hajicek, Douglas ; Musich, Mark ; Henderson, Ann

University of North Dakota

关键词: Heat Transfer;    02 Petroleum;    Combustion;    Petroleum Products;    Oxygen;   

DOI  :  10.2172/984656
RP-ID  :  None
RP-ID  :  FC26-98FT40320
RP-ID  :  984656

美国|英语

来源: UNT Digital Library

【 摘 要 】

Traditionally, air is used as the source of oxygen for firing a combustion system. A fully oxygen-fired circulating fluidized-bed combustion (CFBC) system would result in the production of a flue gas stream consisting of mostly carbon dioxide and water. The concentrated carbon dioxide stream would be available for sequestering or other purposes. Temperatures in an oxygen-blown CFBC system would be controlled by a combination of flue gas recycle, solids recirculation, and by appropriately sizing and locating the amount of heat-transfer surface required. Flue gas recycle provides the additional gas required for adequate fluidization and circulation of solids replacing the nitrogen that would be present in an air-blown system. The amount of flue gas recycle will determine how much of the remaining heat from the coal combustion will have to be removed. If the amount of flue gas recycle required by increasing solids recirculation and oxygen staging is limited, introducing the pure oxygen at multiple locations in the combustor to result in a more even temperature profile should result in a more compact system, thus reducing initial capital costs for construction. The overall efficiency of the process should be greater than that of an air-blown system since less fuel is required for the creation of the same amount of energy. The Energy & Environmental Research Center (EERC) is in a unique position to advance this technology. It has a world-class CFBC pilot plant, has experience with firing a wide range of fuels in our air-fired CFBC pilot plant, has prior experience with oxygen-firing a slagging furnace system in a pulverized coal-fired mode with a bituminous coal, and has all of the components required for oxygen-firing right next to the CFBC pilot plant already in place. An engineering study was performed to identify methods, an overall appropriate configuration, and an operating strategy for a fully oxygen-fired CFBC pilot plant by: (1) developing a plan to optimize the amount of flue gas recycle required to control bed temperature; (2) determining how to best utilize the heat-transfer surfaces in a CFBC pilot plant, such as increased external bed surface, to more beneficially use increased solids recycle; (3) identifying appropriate methods for staged addition of the oxygen/recycled flue gas streams to maintain a good temperature profile in the combustor; and (4) determining the level of effort required to convert the EERC CFBC pilot plant to one that is oxygen-blown. The EERC additionally used its experience to consider what would be required for firing a wide range of fuels from biomass to low-rank coals to high-rank coals and petroleum cokes. These proposed modifications will be performed based upon obtaining the required funding.