Patent Application
20090272822
The subject matter disclosed herein relates generally to integrated gasification combined-cycle (IGCC) power generation systems, and more particularly to systems for injecting feed into a gasifier. Some gasifiers convert a mixture of fuel, air or oxygen, temperature moderator, and/or slag additive into an output of partially oxidized gas, sometimes referred to as “syngas.” The syngas is supplied to the combustor of a gas turbine engine, which powers a generator that supplies electrical power to a power grid. Exhaust from the gas turbine engines may be supplied to a heat recovery steam generator that generates steam for driving a steam turbine. Power generated by the steam turbine may be used, for example, to drive an electrical generator that provides electrical power to the power grid.
Fuel, air, oxygen, temperature moderator, such as water or steam, slag additive, or any combination thereof is injected into the gasifier from two or more separate sources through a feed injector that couples the feed sources to a feed nozzle. The feed sources traverse the feed injector as two or more feed streams and are joined together in a reaction zone downstream of the nozzle. Typically, a slurry or other fuel stream is mixed with an oxidizer by using impinging jets, impinging streams, coaxial shear-layers, or a combination thereof, as illustrated in U.S. Pat. No. 4,775,314. Additionally, gasification feed injectors have used mechanical means to cause a helical flow path of the solids stream as described in WO 2004/094568.
There is a need for properly mixing pneumatically conveyed solid feeds with an oxidizer.
For gasification operations, conventional feed injectors have not utilized swirled fluid oxidizer streams to enhance or control mixing of a slurry or fuel stream. Embodiments described herein relate to different mixing options and more particularly to mixing options for pneumatically conveyed fuel with several including swirling and several not requiring swirling.
In accordance with one embodiment disclosed herein, a feed injector system comprises a circular cross-sectional (circular) channel configured for pneumatically conveying pulverized solid fuel feed from a respective source to a reaction zone and an annular cross-sectional (annular) channel substantially concentric with the circular channel and configured to impart swirling flow to a fluid oxidizer stream.
In accordance with another embodiment disclosed herein, a feed injector system comprises a center body, a first annular channel substantially concentric with the center body and configured for imparting swirling flow to a first fluid oxidizer stream, a second annual channel substantially concentric with the first annular channel and configured for pneumatically conveying pulverized solid fuel feed from a respective source to a reaction zone, and a third annual channel substantially concentric with the second annular channel and configured for imparting swirling flow to a second fluid oxidizer stream.
In accordance with still another embodiment disclosed herein, a feed injector system comprises a circular channel configured for pneumatically conveying pulverized solid fuel feed from a respective source to a reaction zone, a first annular channel substantially concentric with the circular channel and configured for conveying a first fluid oxidizer stream, a second annular channel concentric with the first annular channel and configured for conveying a liquid slurry, and a third annular channel concentric with the second annular channel and configured for conveying a second fluid oxidizer stream.
In accordance with still another embodiment disclosed herein, a feed injector system comprises a circular channel configured for conveying a liquid slurry, a first annular channel substantially concentric with the circular channel and configured for conveying a first fluid oxidizer stream, a second annular channel concentric with the first annular channel and configured for pneumatically conveying pulverized solid fuel feed from a respective source to a reaction zone, and a third annular channel concentric with the second annular channel and configured for conveying a second fluid oxidizer stream.
These and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein:
Embodiments disclosed herein include systems and methods for injecting feed into a gasifier. As used herein, the singular forms “a,” “an” and “the” include plural referents unless the context clearly dictates otherwise.
A fluid oxidizer stream flows through annular channel 14. Annular channel 14 includes an arrangement of a plurality of swirl vanes 24 to impart a tangential velocity component to the flow of the fluid oxidizer stream (in other words, to impart swirling flow to the fluid oxidizer stream). The swirl vanes are attached to outer surface of the first cylindrical wall 13 as seen in
A discharge end 16 of annular channel 14 may extend beyond a discharge end 18 of circular channel 12. In one embodiment as shown in
Referring to
In another embodiment, the circular channel 12 is configured to convey a liquid slurry and the second annular channel 20 is configured to pneumatically convey pulverized solid fuel feed from a respective source to a reaction zone in a gasifier.
In embodiments, wherein a third annular channel is present, a second fluid oxidizer stream is conveyed through the third annular channel. The third annular channel 22 may also include an arrangement of a plurality of swirl vanes 24 to impart a tangential velocity component to the second fluid oxidizer stream. The swirl vanes are attached to outer surface of third cylindrical wall 19, the inner surface of the fourth cylindrical wall 21, both surfaces, or are held in place by any other means that allows the feed injector to function as described herein. If desired, an appropriate gap may be maintained using spacers or centering fins, for example.
The swirling flows of the fluid oxidizer streams from the first and third annular channels atomize the slurry and oxidize the pneumatically conveyed pulverized solid fuel feed and the carbonaceous material that is contained in the slurry. In one embodiment as shown in
Although the swirling flows are believed to be beneficial for mixing purposes, in some embodiments, the alternating and momenta of the fluid oxidizer streams are sufficient for mixing, and the structure including circular channel 12, and first, second, and third annular channels 14, 20, and 22 will not necessarily include swirl vanes or any swirling mechanism.
The second annular channel 56 is substantially concentric with the first annular channel 54 and defined by the space between the first cylindrical wall 55 and a second cylindrical wall 57. Pulverized solid fuel feed is pneumatically conveyed from a respective source to a reaction zone in a gasifier through the second annular channel 56.
The third annular channel 58 is substantially concentric with the second annular channel 56 and is defined by the space between the second cylindrical wall 57 and a third cylindrical wall 59. A second fluid oxidizer stream is conveyed through the third annular channel 58. The third annular channel 58 also includes an arrangement of a plurality of swirl vanes 24 to impart a tangential velocity component to the second fluid oxidizer stream. The swirl vanes are attached to outer surface of the second cylindrical wall 57, the inner surface of the third cylindrical wall 59, or both surfaces.
A discharge end 60 of the third annular channel 58 extends beyond the center body 51, the first annular channel 54 and the second annular channel 56. The conical member 53 of the center body 51 is useful for preventing a recirculation zone as a result of the wake formed by center body 52.
The swirling flows imparted by the first annular channel 54 and the third annular channel 58 oxidize the pulverized solid fuel feed that is conveyed through the second annular channel producing syngas. The swirl vanes in the first and third annular channels can be arranged to impart swirling flows in same direction or in opposite direction as discussed above.
The ends of the cylindrical walls are shown as flat in the above figures of all the embodiments. However, in one embodiment, the ends of the cylindrical walls may be rounded, tapered or shaped to control vortex shedding.
Embodiments described herein may thus be used to improve the mixing of pneumatically conveyed solid feeds with an oxidizer, and thus are useful in increasing carbon conversion of the feed stock, increasing the output of syngas, and efficiency of the gasifier.
Although most of the examples herein have been described as systems, each is also applicable as a method of use with one example being a method for operating a feed injector system comprising (a) supplying pulverized solid fuel feed from a source to a reaction zone through a circular channel configured for pneumatically conveying the pulverized solid fuel feed; and (b) supplying a fluid oxidizer stream through an annular channel substantially concentric with the circular channel and configured to impart swirling flow to the fluid oxidizer stream.
While certain features of the invention have been illustrated and described herein, many modifications and changes will occur to those skilled in the art. For example, in other embodiments, the liquid slurry is replaced by a non-slurry feed such as a pneumatically conveyed solid particulate feed, a liquid fuel such as a liquid hydrocarbon fuel, a gaseous fuel such as a gaseous hydrocarbon fuel or fuel gas, or a temperature moderator such as water. In still other embodiments, one of the fluid oxidizer streams in the embodiments incorporating two fluid oxidizer streams is replaced by an alternate gaseous feed, such as a gaseous hydrocarbon fuel, fuel gas, or recycle syngas, or a gaseous temperature moderator, such as recycle carbon dioxide or steam. In still other embodiments, the fluid oxidizer stream is combined with a temperature moderator, such as steam or water, upstream of the discharge end of the injector system in any manner that facilitates operation of the injector system as described herein. In still yet other embodiments, the pulverized solid fuel is combined with recycle solids or slag additive upstream of the discharge end of the injector system in any manner that facilitates operation of the injector system as described herein.
It is to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.
