FEED INJECTION DEVICE AND METHOD FOR CONTROL OF ACCRETION Background of the Invention Feed injection devices such as lances or tuyeres are commonly used for injecting various feed materials, such as organic compositions, into a molten bath, such as a molten mental bath or molten salt bath Such devices are particularly useful for submerge injection of waste materais into a molten metal reactor at operating conditions which break down the vaste materials into constituent components which can then be formed into useful products. Tuyeres are typically embedded in the refractory wall that lines the reactor interior. In one embodiment, a tuyere is a pipe that extends through the refractory wall to the interior surface oh the refractory wall, with the opening of the tuyere being usually located below the surface of the molten bath, either on the side or the bottom of the reactor wall. Lances are feed injection devices mounted to the top of the reactor which extend~from the reactor headspace into the molten bath to allow for submerge injection of feed. In one embodiment, a mechanical device is provided which allows the lance to be retracted from the bath when feed is not being injecte. As the feed material is directe into the molten bath, a portion of the feed material can crack and cause cooling thst may lead to accretion formation and deposition of cracked materials can form an accretion of feed and purtisily decomposed feed at the opening of the feed injection device which can lead to operational problems and diminish the availability of the system to process waste materials, One attempt to avoid accretion of the feed material about the feed injection inlet is to direct an excessive amount of oxidant, such as oxygen gas, into the feed injection device to burn off the accretion, However, the tip of the device can be exposed to an excessive temperature and oxidation, thereby causing the tip to be burned off, along with a portion of the surrounding refractory lining.
Therefore, a need exists for a new apparats and method for eliminating or minimizing the problems described above.
Summary of the Invention The present invention relates to the submerge injection or a feed material and a reactant, such as an oxidant, into a molten metal bath, More particularly, the present invention relates to a feed injection device and method for the submerge injection of waste material into a molten metal bath in a molten metal reactor to provide effective control of the product quality, typically the quality of the off gas product formed, or of the heat balance at the tip of the feed injection device, or both.
Adjusting the heat balance allows an accretion of metal forming at the feed and reacant passages of the feed injection device to be controlled, while avoiding excessive burn back of the tip of the injection device.
The method of one embodiment of the invention inclues directing a feed material through a first tube of a feed injection device embedded within a refractory lining of a molten metal reactor into a mixing zone located between the outlet end of the feed injection device and the molten metal bath. A reactant, such as an oxidant material, is directe into the mixing zone through a second tube of the feed injection device, Optionally, a co-feed material is directe into the mixing zone through a third tube of the mixing zone. In one preferred embodiment, the tubes are concentrically dispose with respect to one another, wherein ihe first tube is recessed to a distance below the adjacent surface of the molten metal bath to form a mixing zone within the feed injection device, Mixing the feed material and the reactant within the mixing zone forms a mixture that is evenly distributed across the outlet of the feed injection device, Directing the mixture of materials into the moite metal bath by controlling the oxidant-to-feed material ratid provides the ability for effectively controlling the formation of accretion of metal at the tip of the feed injection device from the molten metal at the operating conditions of the feed injection device.
This invention provides several advantages, One avantage is that the feed injection device provides effective controi over accretions at the outlet end of the injection device and can operal-e for extended periods of operation, Another avantage is that the feed tube is recessed sufficiently from the extreme thermal conditions of the molten metal bath to form a mixing zone within the device which allows thorough mixing of the feed material with other compositions within the passage, namely an oxidant and in some cases co-feeds, such as natural gas, water (steam) or propane, In addition to substantial reduction of the growth of accretions, the formation of a pre-injection mixing zone within the feed injection device permits several other avantages in processing waste materials. For example, the heat balance at the outlet of the feed injection device proximate to the molten metal bath, which is a strong function of i-he chemical composition of the feed material, can be adjusted to avoid excessive burn back of the feed injection device and the surrounding refractory. rince waste materials can vary from highly endothermic compound, such as methanol compound, to highly exothermic compound, such as chlorinated organic compound, the present invention affords flexibility in beina able to aliow injection for extended operating periods with either class of compound by simple adjustments to resctor operating conditions. In the case of an endothermic feed, an oxidani may be mixed with the feed or a co-feed material in the pre-injection mixing zone to produce a desired chemical rection with the corresponding heat of rection being controlled by varying the flow of reactunts (i. e. feeds, oxidant and co-feeds when applicable) so that the feed injection device may be used to melt any accretion or other deposit formed on or in the vicinity of the feed injection device. Conversely, for an exothermic feed, reactants (inciuding co- feeds) and lheir flow rates can be correspondingly varied in a manner such that when they are mixed in the mixing zone the rate of burn back of the tip of the feed injection device and the surrounding refractory lining can be effectively controlled, Other specific avantages include the ability to reduce problems associated with injection of oxidants into molten nickel baths, such as the generation of nickel oxide accretions, by pre-mixing carbon-containing feeds with an oxidant to provide a carbon source to reduce the nickel oxides to elemental nickel. Also, an oxygen- containing compound pre-mixed with the vaste feed material promotes a subsequent oxidation rection which reduces the amount of dust generated during processing, Pre-mixing feed and other reactants also avoids pyrolytic cracking which produces deposits on the walls of the feed injection device that may ultimately plug the passageways. Tne ne'i effect of pre-injection mixing within the device is to increase the effective throughput and on stream facfor of the feed injection device by minimizing accretion and plugging problems as well as by optimizing process chemistry which results in optimal production of desired product (s), Brief Description of the Drawings Figure 1 is a cut-away side elevationul view of one embodiment of the apparats of the present invention in a molten metal bath reactor.
Figure 1A is a cut-away side elevational view of the submerge feed injection device shown in Figure 1.
Figure 2 is a cut-away side elevational view of a second embodiment of the feed injection device shown in Figure 1, Figure 3 is a cut-away side elevational view of a third embodiment of the feed injection device shown in Figure 1.
Figure 4 is a cut-away side elevational view of a fourth embodiment of the feed injection device shown in Figure 1.
Figure 5 is a cut-away side elevational view of a fifth embodiment of the feed injection device shown in Figure 1.
Figure 6 is a graph showing the pressure response during injection of feed and reactant materais of the feed injection device shown in Figure 2, Detailed Description of the Invention The features and other details of the apparatus cnd method of the invention will now be more particularly described with reference to the accompanying drawings and pointed out in the claims. The same numeral présent in different figures represents the same item. All parts and percentages are by weight unless otherwise specified. It will be understood that the particular embodiments of the invention are shown by way of illustration and not as limitations of the invention, The principle features of this invention can be employed in various embodiments without departing from tlme scope of the invention. For example, the invention is described herein in the context of submerge injection into a molten metal bath in a refractory-lined reactor through bottom injection by means of a tuyere. However, other feed injection devices, such as lances, can be used and other locations for submerge injection, such as through the side walls, are possible.
The present invention relates generaliy to a method for the submerge injection of waste material into a molten metal contained in a molten metal reactor wherein the waste undergoes a chemical change within the reactor to produce desired product (s). A process and apparats for dissoclating waste in molten maths are disclosed in U. S.
Patents 574,7144, and 602,574,4, issued to Bach/Nagel. The method and apparats described by these patents can destroy poXychlorinated biphenyls and other organic wastes, optionally together with inorganic waste. Both U, S. Patents 574,7144, and 602,5744, are hereby incorporated by reference in their entirety. Another apparats and method for dissociating wsste in a molten metal bath and for forming as an output of the reactor desired gaseous, vitreous and mental products from the waste are disclosed in U, S, Patent 301,620,5, issued to Nagel et al., the teachings of which are hereby incorporated by reference in their entirety.
One embodiment of the invention is illusirated in Figure 1.
Therein, system 10 inclues reactor 12 for containing a molten bath suitzble for dissociating a feed material. Examples of suitable reactors include appropriately modifie steelmaking vessels known in the art, such as K-BOP, Q-BOP, argon-oxygen decarbonization furnaces (AOD), BOF, etc. Reactor 12 inclues upper portion 14 and lower portion 16. Off-gas outlet 18 extends from upper portion 14 and is suitable for conduci-ing an off-gas composition out of reactor 12, Reactor 12 has metal shell 17 and is lined with refractory lining 19. Refractory lining 19 can be, for example, bricks compose of aluminum oxide (AI203) magnesium oxide (MgO), silicon dioxide (SiO2) thorium dioxide (ThO2), zirconium dioxide (ZrO2) or other suitable materials, such as a ceramic. The refractory lining car) be coated with a gas permeable coating, such as sputtered aluminum oxide, Tuyere 20 is located at lower portion 16 of reactor 12 and can be a multiple concentric tuyere, in particular, a friple concentric tuyere.
Tuyere 20, which is a concentric tuyere, inclues feed material tube line 22 for directing a feed materai to feed material tube 32 for injection of the feed material through feed material tube outlet 25 to bath inlet 24, Feed material tube ourlet 25 is recessed from the surface 21 of refractory lining 19 within tuyere 20, For sake of clarity and economics of space, the degree of recess of the various tubes shown in the drawings is not drawn to scale. For example, in one embodiment, feed material tube outlet 25 is at a distance from the bath inlet 24 in the range of between about five to one hundred times, and prefersbly between about 5 to 20 times, the internal diameter of tuyere 20. Line 26 extends between feed material tube line 22 and feed material source 28 for conducting feed material from feed material source 28 by pump 30 to feed material tube 22, Oxidant tube 34 of tuyere 20 is dispose concentrically around feed material tube 32 at bath inlet 24, Feed material tube outlet 25 is sufficiently recessed within oxidant tube 34 to allow feed material and oxidant to mix thoroughly within tuyere 20 before entering the moite metal bath, thereby effectively controlling the formation of accretion of metal on the outlet end of feed tube 32. Line 35 extends between oxidant source 36 and oxidant tube 34 for conducting a suitable oxidant through oxidant tube 34 to oxidant inlet 37. Oxidant can be, for example, oxygen gas or some other gas which can oxidize a portion of the wsste to form a product, such as steam or carbon dioxide, Shroud gas tube 38 of tuyere 20 is dispose concentrically around oxidant tube 34 at bath inlet 24, Line 40 extends between shroud gas tube 38 and shroud gus source 42 for conducting a suitable shroud gas through shroud gus inlet 39, which is the concentric opening between oxidant tube 34 and shroud gas tube 38, at bath inlet 24, Shroud gas can be, for example, an inert gas, such as argon or nitrogen, or a mixture of inert gas and a coolant, wherein the coolant can be a hydrocarbon, such as propane or methane, carbon dioxide or water.
Bottom tupping spout 44 extends from lower portion 16 of reactor 12 and is suitable for removal of metal from reactor 12.. Induction <BR> <BR> <BR> <BR> <BR> <BR> coil 46 is iocaled at lower portion 16 for healing molten mental bath 48 in reactor 12. It is to be understood, alternatively, reactor 12 can be heated by other suilzbie means, such as by an oxyfuel burner, electric arc, etc, <BR> <BR> <BR> <BR> <BR> Molten metal bath 48 is formed within reactor 12, Molten mental<BR> <BR> <BR> <BR> <BR> <BR> <BR> <BR> bath 48 cun include at least one metal or molten sall or metal oxides thereof or maties. Examples of suitable metals include copper, iron, nickel, zinc, etc. Examples of suitable salts include potassium chloride, sodium chloride, etc. Examples of suitzble mattes include iron sulfite, <BR> <BR> <BR> <BR> <BR> nickel sulfide, copper sulfide, etc. Molten bath 48 cun also include more than one metal, For example, molten bath 48 can include a solution of immiscible metals or miscible metals, such as iron and nickel. In one embodiment, molten bath 48 can be forrned substantially of elemental metal, Alternatively, molten bath 48 can be formed substantially of metal salts. Molten bath 48 is formed by at least partially filling reactor 12 with a suitable metal or metal sali*. In another embodiment, molten bath 48 is formed of immiscible metals, These immiscible metals can include first metal 50, such as liron, and second metal 52, such as copper. Molten metal 48 is then heated by a suitable means, such as induction coil 46 or oxyfuel burner, not show, Suitable operating conditions of system 10 inclue, for example, a temperature which is sufficient to at least partially converi-carbonaceous feed by dissociation to elemental carbon and other elemental constituents, Generally, a temperature in the range of between about 1,300 and 1,700°C is suitable, Additionally, reactor 12 can be a pressurizeable vessel capable of operating under positive or negative (vacuum) conditions. In one embodiment, reactor 12 is a closed, pressure-tight vessel that is operated at a pressure range of about 0-10 bars, Vitreous layer 54 is formed on molten bath 48. Vitreous layer 54 is substantially immiscible with molten bath 48. Vitreous layer 54 can have a lower thermal conductivity than that of molten bath 48. Radisnt heat loss from molten bath 48 can thereby be reduced to significantly below the radiant heal loss from mollen bsth 48 where no vitreous layer is pressent.
Typically, vitreous layer 54 can inclue at leasl one metal oxide, Vitreous layer 54 can contain a suitable compound for scrubbing halogens, such as chlorine or fluorine, to prevent formation of hydrogen halide gases, such as hydrogen chloride. In one embodiment, vitreous layer 54 comprises a mental oxide having a free energy of oxidation, at the operation conditions of system 10, which is less than that for the oxidation of atomic carbon to carbon monoxide, such as calcium oxide (CaO).
As can be seen in Figure 1 A, a submerge feed inlet for controlling the formation of accretion 58 inclues a feed material tube outlet 25 recessed from the surface 21 of refractory lining 19 within tuyere 20. In a preferred embodiment, feed material tube outlet 25 is below refractory surface 21 at a distance (d) in the range of between about five to one hundred times the internal diameter of tuyere 20, which is, in one embodiment, the internal diameter of shroud gas tube 38. Also, feed material tube outlet 25 is preferably parallel with refractory surface 21. In a purticularly preferred embodiment, tuyere 20 has an inside diameter of <BR> <BR> <BR> <BR> <BR> about 0.3 inches (0.76 cm) and feed material tube outlet 25 is about five inches (12.7 cm) below refractory surface 21, Mixingzone56canbe formed within tuyere 20 above feed material tube outlet 25 and below surface 21 of refractory lining 19 and below adjacenl surface of moSten bath 48, and within oxidant tube 34 of tuyere 20. Mixing zone 56 allows thorough mixing of the feed material and oxidant prior to interaction with the metal.
Waste material, in the form of a suitzble guseous, liquid or solid feed, is directe into mixing zone 56, from feed msterial source 28 through line 26 and feed material tube line 22 to feed material tube 32 in tuyere 20 towards molten bath 48. Waste material enters mixing zone 56 at feed material outlet 25. A wide variety of waste materials can be used which inclues organic waste. An example of a sultable organic waste is a hydrogen-containing carbonaceous material, such as oil or a waste which include organic compound containing nitrogen, sulfur, oxygen, etc. It is to be understood that the orgunic waste can include inorganic compounds, In addition to carbon and hydrogen, the organic waste can include other constituents, such as halogens, metals, etc. Oxygen gas or another oxidant is directe frorn oxidant source 361hrough line 35 to oxidant tube 34 into mixing zone 56, A suitable shroud gas, such as hydrocarbon or insert gas, is directe from shroud gas source 42 through line 40 to shroud gas tube 38.
As the waste feed material and oxidant are directe into mixing zone 56, the feed material and oxidant sufficiently mix within mixing zone 56 before injection into molten metal bath 48 to cause even ~ distribution of the feed material and oxidant across 1he outlet of tuyere 20, Even distribution of the feed material and reactant can be the result of shear force caused by contact between the feed and reactant, Pre- injection mixing of feed (waste) with oxidant within the injection device has several advantages. First, in waste treatment processes using molten bath reactors the hazards of explosion are greatly minimized when mixing occurs within the injection device as opposed to other locations further upstream of the molten bath. Mixing controls the heat of rection released due to bath material oxidation by lowering the oxygen partial pressure in the immediate vicinity of tuyere 20, This allows the heat balance at the outlet end of tuyere 20 to be adjusted to effectively control the solidification of molten metal on or in the vicinity of the tip of the tuyere 20, a phenomenon more commonly referred to as accretion formation, Additionally, lower partial pressure of oxygen minimizes the risk of metal oxides formation. In general, high local concentration of metal oxides (e, g. Cu20, FeO) in the vicinity of tuyere 20 promotes chemical refractory erosion thereby reducing the life of the tuyere. In other cases, formation of higher melting point metal oxides (e. g. NiO, Fe2O3) in the vicinity of tuyere 20 may lead to the formation of higher melting point accretions and partial plugging of tuyere 20. This situation can be alleviated by adjusting the flow rates of the feed and co-feed materiai and the oxidant accordingly to provide a carbon source for reducing the metal oxides to a lower melting point composition. Alternatively, flow rate adjustment can also raise the heat of rection at the outlet end of the injection device to melt any formed accretion. In this event, care must be taken to avoid excessive reactive heat to minimize the rate of burn back of tuyere 20 and surrounding refractory lining 19. Furthermore, such pre- mixing is also expected to suppress carbonaceous dust formation in reactor 12 by minimizing pyrolysis and by providing mixing of oxygen with feed prior to bubble breakup and exposure to the high temperature environment of molten bath 48. In some cases, e. g. in processing highly chlorinaled wsstes, where tighter control on bath chemistry is desired to suppress metal chloride dust formation by controlling molar H/CI ratio in the gas phase, it may be desirable io direct a co-feed into tuyere 20. For example, mixing of a hydrogen-containing compound as a co-feed with the chlorinated waste feed in mixing zone 56 provides effective control of off-gas chemistry and minimizes the dependence of off-gas chemistry on bath mixing patterns, The injection of pre-mixed feed material and oxidant, and in some cases co-feed material, in a controlled manner also can impact the formation of desired product or products. In one embodiment involving the processing of chlorinated organic waste, it is desired to produce a gaseous stream of hydrogen, carbon monoxide, and hydrochloric acid. It is also desirable to control the ratio of varions gases in the off gas tõ maximize the heai-ing value of these ganses. Pre-mixing and controlling the flow rates of the feed, oxidant and co-feeds, such as water (stem), propane or naturel gas optimizes the production of desired product (s) by effectively shifting the chemical equilibrium to maximize hydrogen chloride yield, Mixing zone 56, which is within tuyere 20, can maintain a rection zone 60 at bath inlet 24, if the flow rates of the waste feed material and oxidant are maintained at a fully expanded Mach number in the range of about 0,2 to 1.2 to avoid burning bacis the tubes of tuyere 20 and the surrounding refractory lining 19 due to the heat of rection, The recession of material feed tube 32 is believed to assist in minimizing the formation of oxides at bath inlet 24 due to a relatively low oxygen partial pressure in the vicinity of buth inlet 24. This modification liminales the need for oxygen injection through feed material tube 32 to open tuyere 20 during the start up of feed injection into molten bath 48 within reactor 12.
Tuyere 20 is formed of materials suitable for use in multiconcentric tuyeres, Examples of suitzble materials inclue copper, tungsten, stainless steel, alumina and graphite.
In Figure 2, a second embodiment of the invention is shown which is particularly useful in creating an exothermic rection zone 60 to control the formation of accretion at the tip of tuyere 20. In this embodiment, mixing oxygen with a co-feed of natural gas in mixing zone 56, and in the presence of high molten bath temperature, creates a frame at the tip of 1uyere 20, which in turn can be controlled to provide removal, or even prevent formation, of high melting poini accretions. This embodiment is also useful in situations where severe accretion formation occurs during process start up due to extreme change in thermal environment, as for example during pre-heating and melting of metal charge prior to injection. In this instance, oxidant tube 34 is recessed to about the same depth as feed material tube 32 and both tubes are recessed from the surface of refractory lining 19 to a distance in the range of between about five to one hundred times the internal diameter of the shroud tube 38. In a preferred embodiment, oxidant tube 34 is recessed from the surface of the refractory lining 19 to a distance in the range of between about five to twenty times the internal diamenter of shroud tube 38, Mixing zone 56 allows thorough mixing of the feed material, oxidant and shroud gas prior to contact with the molten mental, Rection zone 60 is formed in a region above bath inlet 24 where the mixture of feed material, oxidant and shroud gas reacts in the presence of molten buth 48 to form their elemental constituents from which reuction products are formed, for example, hydrogen gas (H2), carbon monoxide, carbon dioxide, and hydrogen chloride (HCI).
Figure 3 shows a third embodiment in which oxidant tube 34 is recessed within tuyere 20 to a depth intermediate thst of feed tube 32 and shroud tube 38. This embodiment is psrticularly useful during the stars of waste feed injection to provide accretion control as the functionality and avantages of both the Figure I A and Figure 2 embodiments are combine in a single device, In Figure 4, a fourth embodiment of the invention is shown which is particularly useful to control burn back of tuyere 20 and refractory lining 19, Feed material tube inlet 25, oxidant inlet 37 and shroud gas inlet 39 are dispose individually and nonconcentrically at the base of tuyere 20, Feed material, oxidant and shroud gus can be directe through feed material tube 32, oxidant tube 34 and shroud gas tube 38, respectively, into mixing zone 56 of tuyere 20, This embodiment is similar in functionality to the Figure 1 A embodiment described above except that this particular embodiment provides added flexibility by allowing the injection of multiple feeds simultaneously. Additionally, the waste feed acceptability criteria are widened by allowing much larger solids to be processed through tuyere 20. This embodiment also provides flexibility by providing the abilily to change feed inlets in case the primary feed outlet tube becomes plugged. Furthermore, simultaneous processing of more than one type of waste feed can be accommodated without the risk of any undesired chemical rection occurring in the event that the feeds are reactive with one another.
Figure 5, shows a fifth embodiment of the invention which is particularly useful to control burn back when highly exothermic vaste materials are injecte into reactor 12, This embodiment is similar to the one shown in Figure 4 except in this case a coolant jacket 62 has been included proximate to tuyere 20 to provide cooling in trie vicinity of tuyere 20. Jacket 62 can be employed to circulate a suitable coolant, such as liquid water, water mist, steam or natural gas around tuyere 20 and thereby maintain a suitably cool temperature at th@ tuyere. Such cooling maintins a desired iemperature range within the vicinity of tuyere 20 and surrounding refractory lining 19. The provision of a cooling source can also be used to freeze bath mai-serial around the inner walls of mixing zone 56 to provide a protective layer.
In the embodiments described above, the method for submerge injection feed(waste)materialutilizingthepre-mixingoffeedanda oxidant (and optionally co-feeds) has been shown to be important for optimizing the quality of desired producl (s) produced, This optimization may be accomplished through effective control of the formation of an accretion of mental to enhance system availability (up-time) or by using pre-mixing to control process chemistry. For purposes herein, both of the foregoing aspects of control are to be encompassed as contributing to product optimization, The Tollowing example illustrates an application of the method of the present invention. <BR> <BR> <BR> <BR> <BR> <P>Example<BR> <BR> <BR> <BR> <BR> <BR> <BR> A stainless steel 1uyere constructed in accordance with the embodiment of Figure 2, in which the inner iwo tubes were inivially recessed from the outermost tube by about 7 times the internal diameter of the outermost tube, was inserted in the bottom refractory block of a molten bath reactor. The reactor was charged with nickel metal which was brought to its molten state by activation of an induc1ion furnace. A chlorinated waste siresm surrogate containing a fifty-fifty mixture by weight of methylene chloride and toluene to be freated by the reactor was injecte beneath the surface of the molten bath of the reactor as feed material through the center most tube of the tuyere, An oxidant comprise of a mixture of oxygen and nitrogen was concurrently injecte through the oxidant tube dispose concentrically aboul the central feed tube. A mixture of natural gas and nitrogen, used as a coolant, was fed through the outermost tube of the luyere. A series of injection runs wss conducted over several hours with the flow rates of feed, oxygen, natural gas and nitrogen being 321b/hr, 211b/hr, 3, 6 Ib/hr and33.51b/hr, respectively. The back pressure of each tube was constan-ily monitored during the injection runs.
Figure 6 is a graph of the pressure response of the feed injection runs described above, For sake of clarity, only lhe pressure response of the feed passage (represented by the thicker line 70) and of the coolant passage (represented by the thinner line 72) are shown, The data corresponding to the pressure response of the oxidant passage were alsc recorde and were found to closely track the responses of the other two passages. Figure 6 demonstrates that once steady-state injection was achieved, the onset of which is indicated by reference numeral 80, the bscl< pressure remained constant for over 3 hours, During this time period, the extent of bottorn refractory block wear (and consequent burn bacs of the outer coolant tube), which was also monitored by means of appropriately positioned thermocouples, and the correlation between various back pressures indicated the existence of a mixing zone within the tuyere, The spike in the bsck pressure of the feed passage, represented by reference numeral 82, corresponds to the point of bottom refractory block wear at which outer coolant tube and the other two inner concentric tubes are all the same height, that is to say the mixing zone within the tuyere is no longer pressent, As shown in the region to the right to pressure spike 82, the pressure response of the two passages no longer track one another and, indicate a tuyere configuration and operational behavior similar to a conventional (flush-type) tuyere design.
Comparing injection throughput, as indicated by the back pressure measurements of Figure 6, shows that after losing the mixing zone and the recessed section of the tuyere it became difficult to operute and maintain a steady state injection condition due to the poor accretion control capability of the conventional, flush-type tuyere design. This ~ example also clearly indicates the superior operating performance when the mixing zone is present as contrusted with results obtained in the absence of a mixing zone.
Equivalents Those skilled in lé art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to specific embodiments of the invention described specifically herein. Such equivalents are intended lo be encompassed in the scope of the followingclaims.
