Coal gasification feed injector shield with integral corrosion barrier

#The present invention relates generally to an improved feed injector nozzle, or burner, for use in a coal gasification apparatus for producing synthesis gas. The feed injector is provided with a threaded heat shield, to prevent corrosion of the feed injector face, and includes a barrier, integral with the face of the feed injector, that prevents the diffusion of corrosive species to the threaded attachment ring of the heat shield. This barrier prolongs the life of the heat shield by blocking the passage of corrosive species that cause the failure of the ring.

#Synthesis gas mixtures essentially comprising carbon monoxide and hydrogen are important commercially as a source of hydrogen for hydrogenation reactions, and as a source of feed gas for the synthesis of hydrocarbons, oxygen-containing organic compounds, and ammonia. One method of producing synthesis gas is by the gasification of coal, which involves the partial combustion of this sulfur-containing hydrocarbon fuel with oxygen-enriched air. In the slagging-type gasifier, a coal-water slurry and oxygen are used as fuel. These two streams are fed to the gasifier through a feed injector, sometimes called a burner, that is inserted in the top of the refractory-lined reaction chamber. The feed injector uses two oxygen and one coal slurry stream, all concentric, which are fed into the reaction chamber through a water-cooled head. The reaction chamber is operated at much higher pressure than the injector water jacket.

#In this process, the reaction components are sprayed under significant pressure, such as about 80 bar, into the synthesis gas combustion chamber. A hot gas stream is produced in the combustion chamber at a temperature in the range of about 700° C. to about 2,500° C., and at a pressure in the range of about 1 to about 300 atmospheres, and more particularly, about 10 to about 100 atmospheres. The effluent raw gas stream from the gas generator typically includes hydrogen, carbon monoxide, and carbon dioxide, and can additionally include methane, hydrogen sulfide, and nitrogen, depending on fuel source and reaction conditions.

#FIG. 1 is a partial sectional view of a synthesis gas generation combustion chamber and burner;

#FIG. 2 is a detail of the combustion chamber gas dynamics at the burner nozzle face;

#FIG. 3 is a partial sectional view of a synthesizing gas burner nozzle constructed according to a preferred embodiment of the invention;

#Referring now to FIG. 1, a partial cut-away view of a synthesis gas generation vessel 10 is illustrated. The vessel 10 includes a structural shell 12 and an internal refractory liner 14 around an enclosed combustion chamber 16. Projecting outwardly from the shell wall is a burner mounting neck 18 that supports an elongated fuel injection burner assembly 20 within the reactor vessel. The burner assembly 20 is aligned and positioned so that the face 22 of the burner is approximately flush with the inner surface of the refractory liner 14. A burner mounting flange 24 secures the burner assembly 20 to a mounting neck flange 19 of the vessel 10 to prevent the burner assembly 20 from becoming ejected during operation.

#Although not wishing to be bound by any theory, it is believed that FIGS. 1 and 2 represent a portion of the internal gas circulation pattern within the combustion chamber. The gas flow depicted as arrows 26 is driven by the high temperature and combustion conditions within the combustion chamber 16. Depending on the fuel and induced reaction rate, temperatures along the reactor core 28 may reach as high as 2,500° C. As the reaction gas cools toward the end of the synthesis gas generation chamber 16, most of the gas is drawn into a quench chamber similar to that of the synthesis gas process described in U.S. Pat. No. 2,809,104, which is incorporated herein by reference. However, a minor percentage of the gas spreads radially from the core 28 to cool against the reaction chamber enclosure walls. The recirculation gas layer is pushed upward to the top center of the reaction chamber where it is drawn into the turbulent downflow of the combustion column. With respect to the model depicted in FIG. 2, at the confluence of the recirculation gas with the high velocity core 28, a toroidal eddy flow 27 is believed to be produced, that turbulently scrubs the burner head face 22, thereby enhancing the opportunity for chemical reactivity between the burner head face material and the highly reactive, corrosive compounds carried in the combustion product recirculation stream.

#Referring to FIGS. 1 and 3, the burner assembly 20 includes an injector nozzle assembly 30 comprising three concentric nozzle shells and an outer cooling water jacket 60. The inner nozzle shell 32 discharges the oxidizer gas that is delivered along upper assembly axis conduit 42 from axial bore opening 33. Intermediate nozzle shell 34 guides the coal slurry delivered to the upper assembly port 44 into the combustion chamber 16. As a fluidized solid, this coal slurry is extruded from the annular space 36 defined by the inner nozzle shell wall 32 and the intermediate nozzle shell wall 34. The outer, oxidizer gas nozzle shell 46 surrounds the outer nozzle discharge annulus 48. The upper assembly port 45 supplies the outer nozzle discharge annulus 48 with an additional stream of oxidizing gas.