Patent Application
20090272034
This invention relates generally to integrated gasification combined-cycle (IGCC) power generation systems, and more specifically to advanced methods and apparatus for injecting feed into a gasifier.
At least some known gasifiers convert a mixture of fuel, air or oxygen, steam, and/or limestone 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 also drives an electrical generator that provides electrical power to the power grid.
The fuel, air or oxygen, steam, and/or limestone are injected into the gasifier from separate sources through a feed injector that couples the feed sources to a feed nozzle. At least some know gasification feed injectors include relatively long concentric conduits, for example, nine feet long that extend from sources external to the gasifier to an opposite end terminating inside the gasifier. The feed flows through the conduits at relatively high velocities may induce a vibratory response in one or more of the concentrically configured conduits. The vibrations tend to induce fatigue failure of components of the feed injector.
In one embodiment, a gasifier system includes a first substantially cylindrically shaped conduit that includes a radially outer surface, a radially inner surface, and a thickness of material extending between the outer and inner surfaces. The first conduit further includes a supply end, a discharge end and a length extending therebetween. The gasifier system further includes a second conduit at least partially within and substantially concentrically aligned with the first conduit. The second conduit includes a radially outer surface, a radially inner surface, and a thickness of material extending between the outer and inner surfaces. The second conduit further includes a supply end, a discharge end, and a length extending therebetween. The second conduit discharge end is coupled to the first conduit discharge end. The gasifier system also at least one support member extending between the radially outer surface of the second conduit and the radially inner surface of the first conduit wherein the support member is positioned along a length of the second conduit to facilitate reducing a vibratory response of the second conduit to a flow of fluid through at least one of the first and second conduits.
In another embodiment, a method of assembling a gasifier feed injector includes providing a first feed pipe having a first outside diameter. The first pipe further including a supply end, a discharge end, and a length extending therebetween. The method also includes providing a second feed pipe having a first inside diameter, a supply end, a discharge end, and a length extending therebetween coupling a support member to an outside surface of the first pipe at a position along the length of the first pipe that is determined to facilitate reducing a vibratory response of the first pipe to a flow of fluid through at least one of the first pipe and the second pipe. The support member is sized to extend from the outside surface of the first pipe to an inside surface of the second pipe. The method also includes inserting the first pipe into the second pipe such that the first pipe and the second pipe are substantially concentrically aligned.
In yet another embodiment, a gasification system includes a pressure vessel for partially oxidizing a fuel, and a feed injector configured to inject a fuel into the pressure vessel wherein the feed injector further includes a first substantially cylindrically shaped first conduit, a second conduit at least partially within and substantially concentrically aligned with said first conduit, and at least one support member extending between a radially outer surface of the second conduit and a radially inner surface of the first conduit. The first conduit includes a radially outer surface, a radially inner surface, and a thickness of material extending between the outer and inner surfaces. The first conduit further includes a supply end, a discharge end and a length extending therebetween. The second conduit includes a radially outer surface, a radially inner surface, and a thickness of material extending between the outer and inner surfaces. The second conduit further includes a supply end, a discharge end, and a length extending therebetween. The support member is positioned along a length of the second conduit to facilitate reducing a vibratory response of the second conduit to a flow of fluid through at least one of the first and second conduits.
The following detailed description illustrates the disclosure by way of example and not by way of limitation. The description clearly enables one skilled in the art to make and use the disclosure, describes several embodiments, adaptations, variations, alternatives, and uses of the disclosure, including what is presently believed to be the best mode of carrying out the disclosure. The disclosure is described as applied to a preferred embodiment, namely, systems and methods of injecting feed into a reactor. However, it is contemplated that this disclosure has general application to piping systems in industrial, commercial, and residential applications.
Gasifier 56 converts a mixture of fuel, the oxygen supplied by air separation unit 54, steam, and/or limestone into an output of syngas for use by gas turbine engine 10 as fuel. Although gasifier 56 may use any fuel, in some known IGCC systems 50, gasifier 56 uses coal, petroleum coke, residual oil, oil emulsions, tar sands, and/or other similar fuels. In some known IGCC systems 50, the syngas generated by gasifier 56 includes carbon dioxide. The syngas generated by gasifier 52 may be cleaned in a clean-up device 62 before being channeled to gas turbine engine combustor 14 for combustion thereof. Carbon dioxide may be separated from the syngas during clean-up and, in some known IGCC systems 50, vented to the atmosphere. The power output from gas turbine engine 10 drives a generator 64 that supplies electrical power to a power grid (not shown). Exhaust gas from gas turbine engine 10 is supplied to a heat recovery steam generator 66 that generates steam for driving steam turbine 58. Power generated by steam turbine 58 drives an electrical generator 68 that provides electrical power to the power grid. In some known IGCC systems 50, steam from heat recovery steam generator 66 is supplied to gasifier 52 for generating the syngas.
In the exemplary embodiment, combustion zone 214 is a vertically oriented substantially cylindrical space co-aligned and in serial flow communication with nozzle 210. An outer periphery of combustion zone 210 is defined by a refractory wall 216 comprising a structural substrate, such as an Incoloy pipe 218 and a refractory coating 220 configured to resist the effects of the relatively high temperature and high pressure contained within combustion zone 210. An outlet end 222 of refractory wall 216 includes a convergent outlet nozzle 224 configured to maintain a predetermined back pressure in combustion zone 214 while permitting products of combustion and syngas generated in combustion zone 214 to exit combustion zone 214. The products of combustion include gaseous byproducts, a slag formed generally on refractory coating 220, and fine particular carried in suspension with the gaseous byproducts.
After exiting combustion zone 214, the flowable slag and solid slag fall by gravity influence into a lockhopper 226 in bottom shell 204. Lockhopper 226 is maintained with a level of water that quenches the flowable slag into a brittle solid material that may be broken in smaller pieces upon removal from gasifier 200. Lockhopper 226 also traps approximately ninety percent of fine particulate exiting combustion zone 214.
In the exemplary embodiment, an annular first passage 228 at least partially surrounds combustion zone 214. First passage 228 is defined by refractory wall 216 at an inner periphery and a cylindrical shell 230 coaxially aligned with combustion zone 214 at a radially outer periphery of first passage 228. First passage 228 is closed at the top by a top flange 232. The gaseous byproducts and remaining ten percent of the fine particulate are channeled from a downward direction 234 in combustion zone 214 to an upward direction 236 in first passage 228. The rapid redirection at outlet nozzle 224 facilitates fine particulate and slag separation from the gaseous byproducts.
The gaseous byproducts and remaining ten percent of the fine particulate are transported upward through first passage 228 to a first passage outlet 238. During the transport of the gaseous byproducts through first passage 228, heat may be recovered from the gaseous byproducts and the fine particulate. For example, the gaseous byproducts enter first passage 228 at a temperature of approximately 2500° Fahrenheit and when exiting first passage 228 the temperature of gaseous byproducts is approximately 1800° Fahrenheit. The gaseous byproducts and fine particulates exit first passage 228 through first passage outlet 238 into a second annular passage 240 where the gaseous byproducts and fine particulates are redirected to a downward flow direction. As the flow of gaseous byproducts and the fine particulates is transported through second passage 240, heat may be recovered from the flow of gaseous byproducts and the fine particulates using for example, superheat tubes 242 that remove heat from the flow of gaseous byproducts and the fine particulates and transfer the heat to steam flowing through an inside passage of superheat tubes 242. For example, the gaseous byproducts enter second passage 240 at a temperature of approximately 1800° Fahrenheit and exit second passage 240 at a temperature of approximately 1500° Fahrenheit. When the flow of gaseous byproducts and the fine particulates reach a bottom end 244 of second passage 240 that is proximate bottom shell 204, second passage 240 converges toward lockhopper 226. At bottom end 244, the flow of gaseous byproducts and the fine particulates is channeled in an upward direction through a water spray 246 that desuperheats the flow of gaseous byproducts and the fine particulates. The heat removed from the flow of gaseous byproducts and the fine particulates tends to vaporize water spray 246 and agglomerate the fine particulates such that the fine particulates form a relatively larger ash clod that falls into lower shell 204. The flow of gaseous byproducts and the remaining fine particulates are channeled in a reverse direction and directed to an underside of a perforated plate 448 plate forms an annular tray circumscribing bottom end 244. A level of water is maintained above perforated plate 448 to provide a contact medium for removing additional fine particulate from the flow of gaseous byproducts. As the flow of gaseous byproducts and the remaining fine particulates percolates up through the perforations in perforated plate 448, the fine particulates contact the water and are entrapped in the water bath and carried downward through the perforations into a sump of water in the bottom shell 204. A gap 250 between a bottom of lockhopper 226 and bottom shell 204 permits the fine particulates to flow through to lockhopper 226 where the fine particulates are removed from gasifier 200.
An entrainment separator 254 encircles an upper end of lower shell 204 above perforated plate 248 and the level of water above perforated plate 248. Entrainment separator 254 may be for example, a cyclonic or centrifugal separator comprises a tangential inlet or turning vanes that impart a swirling motion to the gaseous byproducts and the remaining fine particulates. The particulates are thrown outward by centrifugal force to the walls of the separator where the fine particulates coalesce and fall down a wall of the separator bottom shell 204. Additionally, a wire web is used to form a mesh pad wherein the remaining fine particulates impact on the mesh pad surface, agglomerate with other particulates drain off with the aid of a water spray by gravity to bottom shell 204. Further, entrainment separator can be of a blade type such as a chevron separator or an impingement separator. In the chevron separator, the gaseous byproducts pass between blades and are forced to travel in a zigzag pattern. The entrained particulates and any liquid droplets cannot follow the gas streamlines, so they impinge on the blade surfaces, coalesce, and fall back into bottom shell 204. Special features such as hooks and pockets can be added to the sides of the blades to facilitate improving particulates and liquid droplet capture. Chevron grids can be stacked or angled on top of one another to provide a series of separation stages. Impingement separators create a cyclonic motion as the gaseous byproducts and fine particulates pass over curved blades, imparting a spinning motion that causes the entrained particulates and any liquid droplets to be directed to the vessel walls, where the entrained particulates and any liquid droplets are collected and directed to bottom shell 204.
In the exemplary embodiment, entrainment separator is a chevron type separator, although other types of separators are contemplated and may be used in place of or in tandem with chevron type separators.
The flow of gaseous byproducts and any remaining fine particulates enter separator 254 where substantially all of the remaining entrained particulates and any liquid droplets are removed form the flow of gaseous byproducts. The flow of gaseous byproducts exits the gasifier through an outlet 256 for further processing.
During operation, fuel injector 208 provides a feed stream of carbonaceous fuel through conduit 304 and primary and secondary oxidizer flow through conduits 302 and 306. In an alternative embodiment, conduit 304 provides a pumpable liquid phase slurry of solid carbonaceous fuel such as, for example, a coal-water slurry. The oxygen containing gas and carbonaceous slurry stream merge at a predetermined distance beyond the outlet orifice 310 of fuel injector nozzle 210 in close proximity to the nozzle outlet end 308 to form a reaction zone (not shown) wherein the emerging fuel stream self-ignites. Self ignition of the fuel stream is enhanced by the breakup or atomization of the merging fuel streams as they exit from the nozzle outlet orifice 310. Such atomization promotes the product reaction and heat development that is required for the gasification process. As a result, the reaction zone that is in close proximity to the outlet end 308 of the fuel injector nozzle 210 is characterized by intense heat, with temperatures ranging from approximately 2400° F. to 3000° F. To propel the streams sufficiently for the reaction zone to form a distance away from nozzle outlet orifice 310, the streams travel through conduits 302, 304, and 306 at a relatively high velocity. Such relatively high velocities of coal slurry flow and oxygen flow at operating conditions may induce vibrations into conduit 302. Such vibrations tend to cause fatigue failure of various components of fuel injector 208. To facilitate reducing vibrations of conduit 302, a plurality of support members 312 are coupled to a radially outer surface 314 of conduit 302. Support members 312 extend radially outwardly from outer surface 314 to a radially inner surface 316 of conduit 304 in the annular space between outer surface 314 and inner surface 316.
Support members 312 include a length 318 in the direction of fluid flow, a width 320 between outer surface 314 and inner surface 316, and a thickness (not shown in
A set of support members 312 comprising a plurality of support members 312 may be spaced circumferentially about outer surface 314 at a single position along the length of conduit 302. In other embodiments, a plurality of sets of support members 312 may be spaced circumferentially about outer surface 314 spaced axially along the length of conduit 302. Support members 312 or sets of support members 302 may be positioned equidistant along the length of conduit 302 or may be spaced at positions determined to facilitate reducing the vibratory mode or amplitude of conduit 302 and/or conduit 304.
As used herein “fluid” refers to refers to any composition that can flow such as but not limited to semi-solids, pastes, solutions, aqueous mixtures, gels, lotions, creams, dispersions, emulsions, foams, suspensions, microemulsions, and other such compositions.
The above-described methods and systems of injecting feed are cost-effective and highly reliable. The methods and systems facilitate operating a gasifier system using a plurality of streams of feed from separate sources of supply to a common reaction zone in a cost-effective and reliable manner.
While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.
