Gasifier injector

Abstract

A method for gasifying a carbonaceous material includes supplying a main slurry flow to a main cavity of a two-stage slurry splitter, dividing the main slurry flow into secondary slurry flows that flow into secondary cavities extending from the main cavity at distal ends of first stage flow dividers, dividing each secondary slurry flow into tertiary slurry flows that flow into slurry injection tubes extending from each secondary cavity at distal ends or second stage flow dividers, injecting the tertiary slurry flows into a gasification chamber coupled to the injector module, impinging annular shaped sprays of a reactant onto corresponding ones of the tertiary slurry flows within the gasification chamber using annular impinging orifices in a face plate of the injector module, and cooling the face plate to withstand high temperatures and abrasion.

Description

FIELD OF INVENTION

The invention relates generally to gasification of carbonaceous materials, such as coal or petcoke. More particularly, the invention relates to an injection device and method used to achieve a high rate of efficiency in the gasification of such carbonaceous materials.

BACKGROUND OF THE INVENTION

Electricity and electrically powered systems are becoming ubiquitous and it is becoming increasingly desirable to find sources of power. For example, various systems may convert various petrochemical compounds, e.g. carbonaceous materials such as coal and petcoke, into electrical energy. Further, such petrochemical compounds are used to create various other materials such as steam that are used to drive steam powered turbines.

The gasification of carbonaceous material such as coal and petcoke into synthesis gas (syngas), e.g. mixtures of hydrogen and carbon monoxide, is a well-known industrial process used in the petrochemical and gas power turbine industries. Over the last 20 years, entrained flow coal gasifiers have become the leading process in the production of synthesis gas. However, these entrained flow gasifiers fail to make use of rapid mix injector technology. The failure to use such technologies causes gasifier volumes and gasifier capital costs to be much higher than necessary. Rapid mix injector technology is expected to reduce these entrained flow gasifier volumes by about one order of magnitude, i.e. by a factor of 10. Getting the overall capital cost of these coal gasifiers down by significantly reducing gasifier volumes is very desirable.

Since 1975, Rocketdyne has designed and tested a number of rapid mix injectors for coal gasification. Most of these designs and test programs were conducted under U.S. Department of Energy contracts between 1975 and 1985. The primary workhorse injector used on these DOE programs was the multi-element pentad. Each pentad (4-on-1) element used four high velocity gas streams which impinged onto a central coal slurry stream. The four gas stream orifices were placed 90 degrees apart from each other on a circle surrounding the central coal slurry orifice. The impingement angle between a gas jet and the central coal slurry stream was typically 30 degrees. Each pentad element was sized to flow approximately 4-tons/hr (i.e., 100 tons/day) of dry coal so that a commercial gasifier operating at a 3,600 ton/day capacity would use approximately 36 pentad elements.

Generally, known rapid mix injectors or coal gasification that impinge oxygen gas or a mixture of oxygen and steam on a slurry stream are effective, but degrade quickly because of the high coal/oxygen combustion temperatures that occur very close to the injector face under local oxidation environmental conditions. These combustion temperatures can exceed 5,000° F. in many instances. Additionally, such known rapid mix injectors are susceptible to plugging within the coal slurry stream.

BRIEF SUMMARY OF THE INVENTION

A gasifier having a gasification chamber and an injection module that includes a two-stage slurry splitter and an injector face plate with a coolant system incorporated therein is provided, in accordance with a preferred embodiment of the present invention. The injector module is utilized to inject a high pressure slurry stream into the gasification chamber and impinge a high pressure reactant with the high pressure slurry stream within the gasification chamber to generate a gasification reaction that converts the slurry into a synthesis gas.

The two-stage slurry splitter includes a main cavity into which a main slurry flow is provided. The main cavity includes a plurality of first stage flow dividers that divide the main slurry flow into a plurality of secondary slurry flows that flow into a plurality of secondary cavities that extend from the main cavity at distal ends of the first stage flow dividers. Each secondary cavity includes a plurality of second stage flow dividers that divide each secondary slurry flow into a plurality of tertiary slurry flows that 20 flow into a plurality of slurry injection tubes extending from the secondary cavities at distal ends of the second stage flow dividers. The tertiary flows are injected as high pressure slurry streams into the gasification chamber via the slurry injection tubes. The reactant is impinged at high pressure on each high pressure slurry stream via a plurality of annular impinging orifices incorporated into the injector face plate. Each annular impinging orifice surrounds a corresponding one of the slurry injection tubes, which extend through the injector face plate. Particularly, each annular impinging orifice produces a high pressure annular shaped spray that circumferentially impinges the corresponding slurry stream from 360°. That is, the slurry stream has a full 360° of the reactant impinging it.

The resulting gasification reaction generates extremely high temperatures and abrasive matter, e.g. slag, at or near the injector face plate. However, the coolant system incorporated within the injector face plate maintains the injector face plate at a temperature sufficient to substantially reduce or prevent damage to the injector face plate by the high temperature and/or abrasive matter.

The features, functions, and advantages of the present invention can be achieved independently in various embodiments of the present inventions or may be combined in yet other embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from the detailed description and accompanying drawings, wherein;

FIG. 1 is an isometric view of a gasifier system including an injector module and a gasification chamber, in accordance with a preferred embodiment of the present invention;

FIG. 2 is a sectional view of a two-stage slurry splitter included in the injector module shown in FIG. 1;

FIG. 3 is sectional view of the injector module shown in FIG. 1, illustrating one embodiment of a cooling system for an injector face plate of the injector module;

FIG. 4 is an isometric view of a portion of the injector face plate shown in FIG. 3;

FIG. 5 is a sectional view of the injector module shown in FIG. 1, illustrating another embodiment of a cooling system for the injector face plate;

FIG. 6 is an isometric view of a reactant side of a portion of the injector face plate shown in FIG. 5;

FIG. 7 is an isometric view of a gasifier side of a portion of the injector face plate shown in FIG. 5; and

FIG. 8 is a flow chart illustrating a method for gasifying carbonaceous materials utilizing the gasification system shown in FIG. 1.

Corresponding reference numerals indicate corresponding parts throughout the several views of drawings.

DETAILED DESCRIPTION OF THE INVENTION

The following description of the preferred embodiments is merely exemplary in nature and is in no way intended to limit the invention, its application or uses. Additionally, the advantages provided by the preferred embodiments, as described below, are exemplary in nature and not all preferred embodiments provide the same advantages or the same degree of advantages.

FIG. 1 illustrates a gasifier system 10 including an injector module 14 coupled to a gasification chamber 18. The injector module is adapted to inject a high pressure slurry stream into the gasification chamber 18 and impinge a high pressure reactant onto the high pressure slurry stream to generate a gasification reaction within the gasification chamber 18 that converts the slurry into a synthesis gas. More specifically, the injector module 14 mixes a carbonaceous material, such as coal or petcoke, with a slurry medium, such as nitrogen N2, carbon dioxide, CO2 or a synthesis gas, for example, a mixture of hydrogen and CO, to form the slurry.

The injector module 14 then injects the slurry, at a pressure, into the gasification chamber 18 and substantially simultaneously, injects other reactants, such as oxygen and steam, into the gasification chamber 18. Particularly, the injector module 14 impinges the other reactants on the slurry causing a gasification reaction that produces high energy content synthesis gas, for example, hydrogen and carbon monoxide.

The injector module 14, as described herein, and the gasification chamber 18 can each be subsystems of a complete gasification system capable of producing a syngas from a carbonaceous material such as coal or petcoke. For example, the injector module 14 and the gasification chamber 18 can be subsystems, i.e. components, of the compact, highly efficient single stage gasifier system described in a co-pending patent application Ser. No. 11/081,144, titled Compact High Efficiency Gasifier, filed Mar. 16, 2005 and assigned to The Boeing Company, which is incorporated herein by reference. The injector module 14 includes a two-stage slurry splitter 22 and a plurality of slurry injection tubes 26 extending from the two-stage slurry splitter 22 and through an injector face plate 30. In an exemplary 15 embodiment, the injector module 14 includes thirty six slurry injection tubes 26. The slurry injections tubes 26 transport high pressure slurry flows from the injection module 14 and inject the slurry into the gasification chamber 18. More specifically, the slurry injection tubes 26 are substantially hollow tubes; open at both ends to allow effectively unobstructed flow of the slurry. That is, there is no metering of the slurry as it flows through the slurry injection tubes. Additionally, the flow of slurry through the slurry injection tubes 26 is a dense phase slurry flow. The injector face plate 30 includes a cooling system for cooling the face plate 30 so that the face plate 30 will withstand high temperatures and abrasion generated by the gasification reaction. The injector module 14 additionally includes a plurality of annular impinging orifices 34 incorporated into the injector face plate 30. The annular impinging orifices 34 are more clearly shown in FIGS. 4 and 5. Each annular impinging orifice 34 surrounds a corresponding one of the slurry injection tubes 26 and is adapted to impinge the reactant onto the slurry stream 30 injected by the corresponding slurry injection tube 26, thereby generating the gasification reaction.

Referring now to FIG. 2, the two-stage slurry splitter 22 includes a main cavity 38 including a plurality of first stage flow dividers 42 and a plurality of secondary cavities 46 extending from the main cavity 38 at distal ends of the first stage flow dividers 42. The first stage flow dividers 42 divide and direct a main flow of the slurry into a plurality of secondary flows that flow into the secondary cavities 46. Since the slurry stream is a dense phase slurry stream, it is important to not have sudden changes in directional velocity of the slurry stream. Sudden changes in the directional velocity of the slurry stream cause bridging or clogging of the flow paths within the injector module 14, e.g. at the secondary cavities 46.

Particularly, as described herein, proper shaping of the first stage flow dividers 42 (and the second stage flow dividers 50, described below) and sizing of the slurry injection tubes 26 is important due to the Bingham plastic nature of gas/solids or liquid/solids slurries. Carbonaceous slurries are not Newtonian fluids, rather they are better classified as Bingham plastics. Instead of having a viscosity, carbonaceous slurries are characterized by a yield stress and a coefficient of rigidity. Therefore, any time a sheer stress at an interior wall of the two-stage slurry splitter 22 is less than the yield stress of the slurry, the flow will plug the two-stage slurry splitter 22. This is further complicated by the fact that to minimize wall erosion from the abrasive solid particles in the slurry, the slurry flow velocities must be maintained below a predetermined rate, e.g. below approximately 50 feet per second, which in turn produces low wall shear stresses at or near the plastic's yield stress.

Therefore, the first stage flow dividers 42 are designed so that the directional velocity of the slurry stream will not be changed by more than approximately 10° when the slurry stream is divided and directed into the secondary flows. Accordingly, each of the first stage flow dividers 42 forms an angle a with a center line C 1 of the main cavity that is between approximately 5° and 20°. Additionally, the first stage flow dividers 42 join at a point 48 such that the flow paths do not include any rounded or blunt bodies that the slurry particles can impact and cause bridging of the flow paths within the injector module 14, e.g. at the secondary cavities 46. Thus, as the slurry stream is divided, there are no sharp contractions or expansions within the flow paths.

Furthermore, the slurry injection tubes 26 are sized to maintain a desired slurry flow velocity within the slurry injection tubes 26, e.g. approximately 30 feet per second. To ensure good mixing between the slurry and reactant streams flowing from the annular impinging orifices 34, the slurry injection tubes 26 will have a suitable predetermined inside diameter, e.g. below approximately 0.500 inches. However, due to slurry plugging concerns the inside diameter of the slurry injection tubes 26 must be maintained above a minimum predetermined diameter, e.g. above approximately 0.200 inches. If the slurry uses gas, such as C02, N2, or H2, as the slurry transport medium, the annular impinging orifices 34 only need to ensure good mixing between the reactants impinged on the slurry stream and therefore the slurry injection tubes 26 can have larger inside diameters, e.g. approximately 0.500 inches. However, if water is used as the slurry transport medium, the annular impinging orifices 34 must impinge the slurry stream and atomize the slurry into small drops. Therefore, the slurry injection tubes 26 must have smaller inside diameters, e.g. approximately 0.250 inches or less. Thus, for the same slurry feed rates into the gasification chamber 18, if water is used as the transport medium, the injector module 14 will require a greater number of slurry injection tubes 26 and corresponding annular impinging orifices 34 than when gas is utilized as the transport medium.

Each secondary cavity 46 includes a plurality of second stage flow dividers 50 that divide and direct the secondary flows into a plurality of tertiary flows that flow into the slurry injection tubes 26. The slurry injection tubes 26 extend from each of the secondary cavities 46 at distal ends of the second stage flow dividers 50 and inject the slurry, at high pressure, into the gasification chamber 18. Similar to the first stage flow dividers 42, it is important to not have sudden changes in directional velocity of the slurry stream at the second stage flow dividers 50. Therefore, the second stage flow dividers 50 are designed so that the directional velocity of the slurry stream will not be changed by more than approximately 10° when the slurry stream is divided and directed into the tertiary flows. Accordingly, each of the second stage flow dividers 50 forms an angle 13 with a center line C2 of the secondary cavities 46 that is between approximately 5° and 20°. Additionally, the second stage flow dividers 50 join at a point 52 such that the flow paths do not include any rounded or blunt bodies that the slurry particles can impact and cause bridging of the flow paths within the injector module 14, e.g. at the secondary cavities 46.

In an exemplary embodiment, first stage flow dividers 42 divide this this main slurry flow into six secondary flows and direct the six secondary flows into six secondary cavities 46 extending from the main cavity 38. Similarly, each second stage flow divider 50 divides the corresponding secondary slurry flow into six tertiary flows and directs the respective six tertiary flows into six corresponding slurry injection tubes 26 extending from the respective secondary cavities 46. Thus, in this exemplary embodiment, the injector module 14 is a 36-to-1 slurry splitter whereby the main slurry flow is ultimately divided into thirty-six tertiary flows that are directed into thirty-six slurry injection tubes 26.

Referring to FIGS. 3 and 4, in various embodiments the injector face plate 30 is fabricated of a porous metal screen having the annular impinging orifices 34 extending therethrough. In such embodiments, the injector face plate 30 can have any thickness and construction suitable to transpiration cool the injector face plate 30 so that the injector face plate 30 can withstand high gas temperatures, e.g. temperatures of approximately 5000° F. and higher, and abrasion generated by the gasification reaction. For example, the injector face plate 30 can have a thickness between approximately ⅜ and ¾ inches and be constructed of Rigimesh®.

As most clearly shown in Figure, the annular impinging orifices 34 comprise a plurality of apertures 34A that extend from a reactant side 54 of the injector face plate 30 through the injector face plate 30. The apertures 34A converge substantially at a gasifier side 58 of the injector face plate 30 to form an annular opening in the gasifier side 58. The reactants that impinge the slurry stream flowing from the slurry injection tubes 26 are supplied under pressure, e.g. approximately 1200 psi, to a reactant manifold dome 62 of the injector module 14 through a reactant inlet manifold 66. The pressure within the reactant manifold dome 62 forces the reactants through the annular impinging orifices 34 where the reactants impinge the slurry flowing from the slurry injection tubes 26 inside the gasification chamber 18.

The cooling system comprises transpiration of the reactants through the porous metal screen injector face plate 30. More particularly, the porosity of the injector face plate allows the reactants flow through the porous metal screen injector face plate 30, thereby cooling the injector face plate 30. However, the porosity is such that the flow of the reactants through the injector face plate 30 is significantly impeded, or restricted, so that less reactants enter the gasification chamber 18 at a greatly reduced velocity from that at which the reactants flowing through the annular impinging orifices 34, e.g. 20 ft/sec versus 500 ft/sec. For example, between approximately 5% and 20% of the reactant supplied to the reactant manifold dome 62 passes through the porous injector face plate 30, and the remaining approximately 80% to 95% passes unimpeded through the annular impinging orifices 34. Therefore, the injector face plate 30 is transpiration cooled by reactants flowing through the porous injector face plate 30 to temperatures low enough to prevent damage to the injector face plate 30, e.g. temperature below approximately 1000° F. Since the porous injector face plate 30 is transpiration cooled, that is the reactants, e.g. steam and oxygen, flow through the porous injector face plate 30, the material of construction for the face plate 30 only needs to be compatible with reactants rather than all of the other gases generated by the gasification reaction. That is, the flow of reactants through the porous injector face plate 30 prevents the more corrosive and/or abrasive gases and particles created during the gasification reaction from coming into contact with the porous injector face plate 30. In addition, the flow of reactants through the porous injector face plate 30 prevents slag corrosion from occurring on the porous injector face plate 30, because the transpiration flow suppresses all recirculation zones within the gasification chamber 18 that would otherwise bring molten slag into contact with the porous injector face plate 30.

Referring now to FIGS. 5, 6 and 7, in various other embodiments, the injector face plate 30 includes a reactant-side plate 70, a gasifier-side plate 74 and a coolant passage 78 therebetween. The cooling system comprises the coolant passage 78 through which a coolant is pass d at high pressure and moderate velocity, e.g. approximately 1200 psi and 50 ft/sec, to cool the gasifier-side plate 74. More particularly, a coolant, such as steam or water, is supplied to an annular coolant channel inlet portion 82A through a coolant inlet manifold 86. The coolant flows from the annular coolant channel inlet portion 82A to the coolant passage 78 via a coolant inlet transfer passage 90 extending therebetween. The coolant then flows across the coolant passage 78 to an annular coolant outlet portion 828 via a coolant outlet transfer passage 94, where the coolant exits the injector module 14 via a coolant exit manifold (not shown). Generally, the annular coolant channel inlet portion 82A and the annular coolant channel outlet portion 82B form a toroidal coolant channel 82 that is divided in half such that the coolant is forced to flow across the coolant passage 78, via the transfer passages 90 and 94.

In an exemplary embodiment, water is used as the coolant. The water is supplied at approximately 1200 psi at a temperature between approximately 90° F. and 120° F. The water coolant traverses the coolant passage 78 cooling the gasifier-side plate 74 and exits the injector module 14 at a temperature between 250° F. and 300° F.

In one embodiment, the coolant passage 78, i.e. the gap between the reactant-side plate 70 and the gasifier-side plate 74 is between approximately ⅜ and ½ inches thick. The gasifier-side plate 74 can be fabricated from any metal, alloy or composite capable of withstanding ash laden acid gas corrosion and abrasion at temperature below approximately 600° F. generated at the gasifier-side plate 74 by the gasification reaction. For example, the gasifier-side plate 74 can be fabricated from a transition metal such as copper or a copper alloy known as NARloy-Z developed by the North American Rockwell Company. Additionally, the gasifier-side plate 74 can have any thickness suitable to maintain low thermal heat conduction resistances, e.g. between approximately 0.025 and 0.250 inches.

Still referring to FIGS. 5, 6 and 7, the injector module 14 further includes a plurality of impinging conic elements 98 that extend the reactant side plate 70, the coolant passage 73 and the gasifier-side plate 74. The impinging conic elements 98 are fitted within, coupled to and sealed with the reactant-side plate 70 and the gasifier-side plate 74 such that coolant flowing through the coolant passage 78 will not leak into either reactant manifold dome 62 or the gasification chamber 18. Each impinging conic element 98 is fitted around an end of a corresponding one of the slurry injection tubes 26 and includes one of the annular impinging orifices 34. In an exemplary embodiment, the slurry injection tubes 26 are embedded into the impinging conic elements 98 and sealed with metal bore seal rings (not shown). Since any leaks between the slurry injection tubes 26 and the impinging conic elements 98 will only flow additional reactant, e.g. steam and oxygen, from the reactant manifold dome 62 into the gasification chamber 18, it is not necessary that seal between the slurry injection tubes 26 and the impinging conic elements 98 be completely, e.g. 100%, leak-proof.

As most clearly shown in FIGS. 6 and 7, the annular impinging orifices 34 comprise a plurality of apertures 348 that extend from a reactant side 102 of the impinging conic elements 98, through the impinging conic element 98 and converge substantially at a gasifier side 106 of the conic impinging elements 98 to form an annular opening in the gasifier side 106. The reactants that impinge the slurry stream flowing from the slurry injection tubes 26 are supplied under pressure to the reactant manifold dome 62 of the injector module 14 through a reactant inlet manifold 66 (shown in FIG. 3). The pressure within the reactant manifold dome 62 forces the reactants through the annular impinging orifices 34 where the reactants impinge the slurry flowing from the slurry injection tubes 26 inside the gasification chamber 18.

FIG. 8 is a flow chart 200, illustrating a method for gasifying carbonaceous materials utilizing the gasification system 10, in accordance with various embodiments of the present inventions. Initially, a main slurry flow is supplied to the main cavity 38 of the two-stage slurry splitter 22, as indicated at 202. The main slurry stream is then divided into a plurality of secondary slurry flows, via the first stage flow splitter 42, that flow into the secondary cavities 46, as indicated at 204. Each secondary slurry flow is subsequently divided into a plurality of tertiary slurry flows, via the second stage flow splitters 50, that flow into the plurality of slurry injection tubes 26, as indicated at 206. The tertiary slurry flows are then injected into the gasification chamber 18 and impinged by annular shaped sprays of the reactant injected by the annular impinging orifices 34, as indicated at 208. Impinging the reactants on the slurry stream causes the gasification reaction that produces high energy content synthesis gas, for example, hydrogen and carbon monoxide, as indicated at 210. Finally, the injector face plate 30 is cooled so that that the face plate 30 withstand high temperatures and abrasion caused by the gasification reaction generated by impinging the reactant onto the tertiary slurry flows, as indicated at 212.

In various embodiments, the injector face plate 30 is cooled by fabricating the injector face plate 30 of a porous metal, and transpiring the reactant through the porous metal face plate 30. In such embodiments, the annular impinging orifices 34 are formed within the porous injector face plate 30 and the reactant is forced through each of the annular impinging orifices 34.

In various other embodiments, the injector face plate 30 comprises the reactant-side plate 70, the gasifier-side plate 74 and the coolant passage 78 therebetween. The injector face plate 30 is then cooled by passing a coolant through the coolant passage 78 to cool the gasifier-side plate 74. In such embodiments, the annular impinging orifices are fitted within the injector face plate 30 such that each impinging conic element 98 extends through the reactant-side plate 70, the cooling passage 78 and the gasifier-side plate 74. Each conic element 98 includes one of the annular impinging orifices 34 that impinges an annular shaped spray of reactant onto the slurry stream flowing from the corresponding slurry injection tube 26.

Those skilled in the art can now appreciate from the foregoing description that the broad teachings of the present invention can be implemented in a variety of forms. Therefore, while this invention has been described in connection with particular examples thereof, the true scope of the invention should not be so limited since other modifications will become apparent to the skilled practitioner upon a study of the drawings, specification and following claims.

Claims

1. A method for gasifying a carbonaceous material, said method comprising: supplying a main slurry flow to a main cavity of a two-stage slurry splitter of an injection module;dividing the main slurry flow into a plurality of secondary slurry flows that flow into a plurality of secondary cavities extending from the main cavity at distal ends of a plurality of first stage flow dividers;dividing each secondary slurry flow into a plurality of tertiary slurry flows that flow into a plurality of slurry injection tubes extending from each secondary cavity at distal ends or a plurality of second stage flow dividers;injecting the tertiary slurry flows into a gasification chamber coupled to the injector module, via the slurry injection tubes;impinging each of a plurality of annular shaped sprays of a reactant onto a corresponding one of the tertiary slurry flows within the gasification chamber, via a plurality of annular impinging orifices incorporated in a face plate of the injector module, wherein each impinging orifice surrounds a corresponding slurry injection tube; andcooling the face plate so that the face plate will withstand high temperatures and abrasion caused by a gasification reactant generated by impinging the reactant onto the tertiary slurry flows.

2. The method of claim 1, wherein cooling the injector module face plate comprises: fabricating the face plate of a porous metal; andtranspiring the reactant through the porous metal face plate.

3. The method of claim 2, wherein impinging each annular shaped spray of reactant comprises: forming the annular impinging orifices within the porous metal face plate; andforcing the reactant through each annular impinging orifice.

4. The method of claim 1, wherein cooling the injector face plate comprises: constructing the face plate to include a reactant-side plate, a gasifier-side plate and a coolant passage therebetween; andpassing a coolant through the coolant passage to cool the gasifier-side plate.

5. The method of claim 4, wherein impinging each annular shaped spray of reactant comprises: fitting a plurality if impinging conic elements within the injector module face plate such that each impinging conic element extends through the reactant-side plate, the cooling passage and the gasifier-side plate, wherein each conic element includes one of the annular impinging orifices; andforcing the reactant through each annular impinging orifice.