WO2003050209A1

WO2003050209A1 - Expansion gap protection structure for a gasifier

Info

Publication number: WO2003050209A1
Application number: PCT/US2002/036701
Authority: WO
Inventors: John Corwyn Groen; Donald Duane Brooker
Original assignee: Texaco Development Corporation
Priority date: 2001-12-07
Filing date: 2002-11-13
Publication date: 2003-06-19
Also published as: TW200300793A; TW546366B; AU2002343725A1

Abstract

The expansion gap protection structure for a gasifier (10) includes a solid, inflexible, non-compressible annular refractory shoulder (50) extending downwardly into an expansion gap from a metallic flange (36) that is provided at a top neck portion (14) of the gasifier(10). The annular refractory shoulder (50) extends into an annular space between a hotface layer (22) of the refractory lining (16) and the inside surface of the gasifier shell(12). The annular refractory shoulder (50) engages an annular refractory fibrous gasket means (90) on a top edge (20) of a backup layer (18) of the refractory lining (16) of the gasifier(10). An annular coil (82) of refractory rope is provided in an annular clearance space between the annular refractory shoulder (50) and the hotface layer (22) of the refractory lining (19) to plug the clearance space.

Description

EXPANSION GAP PROTECTION STRUCTURE FOR A GASIFIER

BACKGROUND OF THE INVENTION

This invention relates to expansion gap protection structures for refractory lined vessels such as gasifiers, and more particularly to a novel expansion gap protection structure that employs solid refractory material.

Gasifiers are generally used for processing carbonaceous fuels, including coal, petroleum coke, gas and/or oil, to produce gaseous mixtures of hydrogen and carbon monoxide, such as coal gas, synthesis gas, reducing gas and fuel gas.

Partial oxidation gasifiers of the type shown in U.S. Patent No. 2,809,104 and U.S. Patent No. 5,484,554 include a high temperature reaction chamber surrounded by one or more layers of insulating and refractory material, such as fire clay brick, also referred to as refractory brick or refractory lining, and encased by an outer steel shell or vessel. A feed injector such as shown in U.S. Patent No. 4,443,230 and U.S. Patent No. 4,491,456, can be used with gasifiers of the type shown in the previously referred to patents to introduce pumpable slurries of carbonaceous fuel downwardly into the reaction chamber of the gasifier along with oxygen containing gases for partial oxidation.

The feed injector can be supported on an annular plate or flange, also referred to as middle flange, at a top neck portion of the gasifier. The middle flange thus forms a mounting surface for the feed injector. Since the feed injector is located at the neck portion of the gasifier, the neck portion is also referred to as the feed injector neck. As shown in U.S. Patent No. 5,484,559, the feed injector is equipped with a mounting plate or flange that lays on the mounting surface of the middle flange. Under this arrangement, when the feed injector is mounted on the gasifier in operating position, the top neck portion of the gasifier is essentially closed to help maintain a pressurized environment in the gasifier reaction chamber.

With the feed injector in operating position on the gasifier, the feed injector housing extends downwardly from the top neck opening of the gasifier in a centralized position in the neck portion of the gasifier. An annular space is thus defined between the body portion of the feed injector and the surrounding refractory lining of the neck portion of the gasifier.

During operation of the gasifier typical reaction chamber temperatures can range from approximately 2200°F to 3000°F. Operating pressures can range from 10 to 200 atmospheres.

Refractory material, such as refractory brick that lines the reaction chamber, including the neck portion of the gasifier, expands at a different rate from that of the gasifier shell during heat up of the gasifier from ambient temperature to operating temperature. Expansion gaps are usually provided for the refractory lining, particularly at the upper neck portion of the gasifier, to take up the heat expansion of the refractory lining. If an expansion gap is not provided, refractory brick expansion can cause the gasifier shell to rupture, bow or deflect, resulting in damage, destruction or collapse of the refractory lining, especially at an upper dome portion of the gasifier near the gasifier neck. The expansion gap is thus a clearance space defined between the top edge of the gasifier neck that supports the middle flange and feed injector, and the top edge portion of the refractory lining. The expansion gap provides sufficient clearance to prevent the refractory lining from expanding against the middle flange and overstressing both the gasifier shell and the refractory bricks. However, the expansion gap exposes an inner surface of the gasifier shell which, if left unprotected, could result in overheating of the gasifier shell at the expansion gap.

In order to protect the exposed inner surface of the gasifier shell, at the expansion gap, it is known to provide a protective refractory expansion gap assembly in the expansion gap.

One known protective refractory assembly for a gasifier expansion gap employs two to three stacked rings of refractory fiber blanket. The refractory fiber blanket extends between the top edge of the expansible refractory lining and the middle flange that is supported on the gasifier neck. The height of the refractory fiber blanket is sized to fill the expansion gap and is sufficiently compressible to yield to the upward thermal expansion of the refractory lining. For all thermal conditions of gasifier operation the middle flange remains in position on the gasifier neck with the feed injector thereon. The middle flange does not yield to upward expansion of the refractory lining since it is secured to the gasifier neck.

The refractory fiber blanket material that fills the expansion gap reduces the flow or bypassing of hot gas, from the reaction chamber, through the expansion gap and also blocks the transmission of radiant heat through the expansion gap. In this manner the gasifier shell at the neck portion of the gasifier, where the expansion gap is located, is protected from overheating.

A refractory fiber blanket expansion gap assembly has several shortcomings. For example, a preheat burner operation on the gasifier that precedes installation of the feed injector, and the feed injector operation, cause a venturi vacuum in the gasifier at the neck portion. The vacuum can cause the refractory fibrous material of the expansion gap assembly to be drawn by suction forces into the reaction chamber of the gasifier. The loss of refractory fibrous material from the expansion gap enables hot gas from the reaction chamber to bypass the expansion gap and access the gasifier shell, resulting in overheating of the gasifier shell at the expansion gap. Also, fibrous refractory material is not especially mechanically resilient and tends to become damaged or eroded by the movement of materials into and out of the feed injector neck. Further damage to the fibrous refractory material at the expansion gap can occur from the erosive action of hot, particulate bearing syngas that is generated during gasifier operation.

A more recent expansion gap assembly to address these problems is shown in U.S. Patent 6,439,137 Bl, to Groen et al incorporated herein by reference. Groen et al also utilizes fibrous refractory material in the expansion gap. However, the fibrous refractory material is held in place in the expansion gap by one or more coils of relatively incompressible refractory rope which forms a peripheral bulge that extends above the gasifier neck opening before the middle flange is installed on the gasifier neck. A compressive force is thus imposed on the peripheral bulge by the middle flange when it is installed on the gasifier. The securing of the middle flange causes the peripheral rope bulge to bear against the fibrous refractory material. The fibrous refractory material is thus locked in position in the expansion gap. The locking arrangement helps prevent vacuum pull-out of the fibrous refractory material from the expansion gap. The entire expansion gap assembly can be encased in a high temperature alloy mesh to minimize erosive damage to the expansion gap assembly.

However, problems of heat transfer to the gasifier shell at the expansion gap can persist even with the locking arrangement of Groen et al. An occasional problem is that the driving force of by-passing syngas is so strong that the porosity of the fibrous refractory materials at the expansion gap can admit the hot syngas which will then access and heat up the gasifier shell. Consequently, the upper dome area of the gasifier can still encounter excessively high shell temperatures which, if severe enough, can force termination of gasification operations.

It is thus desirable to provide an expansion gap protection structure that blocks passage of hot syngas through the expansion gap toward the gasifier shell and minimizes direct exposure of the gasifier shell and fibrous refractory materials to syngas at the expansion gap.

OBJECTS AND SUMMARY OF THE INVENTION

Among the several objects of the invention may be noted the provision of a novel expansion gap protection structure for a gasifier, a novel expansion gap protection structure for a gasifier that blocks passage of hot syngas through the expansion gap toward the gasifier shell, a novel expansion gap protection structure for a gasifier that includes solid refractory material that blocks passage of syngas through the expansion gap toward the gasifier shell, a novel expansion gap protection structure that includes a solid annular refractory shoulder that depends into the expansion gap to block passage of syngas through the expansion gap toward the gasifier shell, a novel expansion gap protection structure that includes a solid annular refractory shoulder extending into the expansion gap to bear against a compressible fibrous refractory material and substantially block the compressible fibrous refractory material from exposure to syngas from the gasifier, a novel expansion gap protection structure for a gasifier including a solid annular refractory shoulder with a coil of relatively incompressible refractory rope to bear against a compressible fibrous refractory material and substantially block the compressible fibrous refractory material from exposure to syngas from the gasifier, and a novel method of blocking syngas from passing through an expansion gap toward the gasifier shell.

Other objects and features of the invention will be in part apparent and in part pointed out hereinafter.

In accordance with the invention an expansion gap protection structure for a gasifier includes a solid, inflexible, non-compressible annular refractory shoulder in contact with a metallic flange of the gasifier. The annular refractory shoulder, in a preferred embodiment of the invention, depends from the metallic flange into the expansion gap at a top neck portion of the gasifier. Preferably the refractory shoulder extends into a space between a hotface layer of the refractory lining for the gasifier, and the metallic shell of the gasifier. A backup layer of the refractory lining, provided between the hotface layer and the gasifier shell, includes a top end surface that is stepped below the top end surface of the hotface layer to provide a recessed space between the hotface layer and the gasifier shell. The recessed space has the shape of an annular channel above the backup layer between the hotface layer and the inside surface of the gasifier shell.

A compressible annular refractory fibrous gasket means is disposed in the annular channel up to a selected height that enables the annular refractory fibrous gasket means to be engaged by the annular refractory shoulder when the annular refractory shoulder extends into the annular channel.

An annular clearance space is provided between the hotface layer and the annular refractory shoulder. The clearance space is occupied and essentially plugged by an annular coil of refractory rope joined to, and compressed against an outer peripheral surface of the hotface layer.

Thus when the metallic flange with the annular refractory shoulder is positioned on the neck portion of the gasifier the annular refractory shoulder engages the annular refractory fibrous gasket means in the annular channel and the annular coil of refractory rope occupies the clearance space between the annular refractory shoulder and the hotface layer.

Under this arrangement hot gas from the reaction chamber of the gasifier is substantially prevented from bypassing the expansion gap of the gasifier to access the shell of the gasifier. The solid, inflexible, non-compressible nature of the annular refractory shoulder essentially blocks passage of hot gas through the shoulder structure. Furthermore, the annular coil of refractory rope in the narrow space between the annular refractory shoulder and the hotface layer substantially blocks passage of hot gas through the rope structure. The compressible annular refractory fibrous gasket means disposed below the annular refractory shoulder and the annular coil of refractory rope also forms an obstacle to passage of gas from the reaction chamber toward the gasifier shell at the expansion gap.

During operation of the gasifier the hotface layer will heat up and expand. Heat expansion will cause the hotface layer to rise toward the metallic flange to virtually eliminate an ambient temperature expansion gap distance between the top edge of the hotface layer and the metallic flange. The effectiveness of the annular refractory shoulder in cooperation with the annular coil of refractory rope at blocking hot gas from accessing the gasifier shell eliminates the need to provide any gasketing means between the top end of the hotface layer and the metallic flange.

Thus the hotface layer can be expanded during gasifier operation to relatively close proximity with the overlying metallic flange. Such narrowing of the expansion gap between the metallic flange and the top edge of the hotface layer during gasifier operation further reduces the possibility of hot syngas accessing the gasifier shell at the expansion gap. Thus the solid, dense, non-compressible nature of the hotface layer and the solid, dense, non-compressible nature of the annular refractory shoulder moving relatively past one another to substantially close the expansion gap at the hotface layer provide an effective impediment to flow of hot gas through the expansion gap to the gasifier shell. The invention further includes a method of blocking hot gas from the reaction chamber of a gasifier, from bypassing an expansion gap of a refractory lining and accessing the gasifier shell at the expansion gap. The method includes providing a stepped annular expansion gap in the refractory lining below a gasifier neck wherein a hotface layer of the refractory lining extends above the top end portion of a backup layer of the refractory lining. Thus an annular channel is defined above the backup layer between the hotface layer and the gasifier shell. The method further includes filling a selected height of the annular channel with compressible annular refractory fibrous gasket means, and forming a solid, inflexible, non-compressible annular refractory shoulder on a metallic flange for the gasifier neck. The annular refractory shoulder is sized, with a tapered inner surface to fit into the annular channel to a selected depth in the annular channel to engage the selected height of the compressible annular refractory fibrous gasket means.

The method also includes securing the metallic flange with the annular refractory shoulder on the gasifier neck to enable the annular refractory shoulder to extend into the annular channel and engage the compressible annular refractory fibrous gasket means. In addition the method includes providing a selected annular clearance space between the refractory shoulder and the hotface layer. The method still further includes providing a coil of refractory rope in the annular clearance space to plug the annular clearance space.

The invention accordingly comprises the constructions and methods hereinafter described, the scope of the invention being indicated in the claims. DESCRIPTION OF THE DRAWINGS In the drawings,

Fig. 1 is simplified fragmentary sectional view of an upper portion of a gasifier with an expansion gap protection structure that incorporates one embodiment of the invention;

Fig. 2 is an enlarged fragmentary sectional view thereof; Fig. 3 is a simplified perspective view, in upside down position, of a metallic flange of the gasifier, with a solid, inflexible, non- compressible annular refractory shoulder;

Fig. 4 is a fragmentary, partially exploded perspective view of the upper portion of the gasifier as shown in Fig. 1; and

Fig. 5 is a simplified sectional view of the gasifier with a feed injector installed on the metallic flange. Corresponding reference characters indicate corresponding parts throughout the several views of the drawings.

DETAILED DESCRIPTION OF THE INVENTION Referring to the drawings, especially Figs. 1 and 5, a gasifier is generally indicated by the reference number 10. The gasifier 10 includes an outer steel vessel or shell 12 having a top neck portion 14, also known as the gasifier neck 14. The gasifier neck 14 has an opening 13 (Fig. 1) through which a feed injector 38 (Fig. 5) extends. The gasifier shell 12 includes an interior surface 15 with a refractory lining 16 that surrounds a reaction chamber 17 (Fig. 5). The refractory lining 16 includes a backup lining or backup layer 18 (Fig. 2) of refractory brick with a top surface or top edge 20. The backup layer 18 can also be made of any suitable known pourable, castable refractory material.

The refractory lining 16 further includes a lining or layer of hotface brick 22, also known as the hotface layer 22. The hotface layer 22 has a top surface or top edge 24 (Fig. 2) and a hotface 26 that faces the reaction chamber 17.

The top edge 20 of the backup layer 18 is stepped below the top edge 24 of the hotface layer 22 to define an annular channel 30 (Fig. 4). The top edge 20 (Fig. 2) of the backup layer 18 is thus the floor of the annular channel 30. The top edge 20 (Fig. 1) can be approximately 117 mm below the top edge 24 for example, and the annular channel 30 can have a width from the hotface layer 22 to the interior surface 15 of approximately 71 mm, for example.

The dimensions provided herein are intended to exemplify the size magnitudes being dealt with and are a function of the overall size of the gasifier. Dimensions will usually be different for each size gasifier. As most clearly shown in Fig. 2 the top edges 20 and 24 of the backup layer 18 and the hotface layer 22 are recessed below a top edge 32 of the gasifier neck to allow for expansion of the refractory lining 16 when it heats up during operation of the gasifier 10. An interior surface portion 15a (Fig. 2) of the gasifier shell 12, near the top edge 32 of the gasifier neck 14, is thus not covered by the refractory lining.

An annular metallic flange 36 (Fig. 2), also known as a middle flange, is disposed on the top edge 32 of the gasifier neck 14 to provide a mounting surface 34 (Fig. 1) for a feed injector 38 (Fig. 5). The space between the middle flange 36 and the top surfaces 20 and 24 of the backup layer 18 and the hotface layer 22 is referred to as an expansion gap 40 (Fig. 2).

The expansion gap 40 can have a height of approximately 157 mm from the top surface 20 of the backup layer 18 to a lower surface portion 37 (Fig. 2) of the middle flange 36, and a height of approximately 33 mm from the top edge 24 of the hotface layer 22 to the lower surface portion 37.

The exposed interior shell portion 15a of the gasifier 10 at the expansion gap 40 is protected from direct exposure to hot gas and other thermal conditions and chemical reactions in the reaction chamber 17 of the gasifier by a new expansion gap protection structure that includes an annular refractory shoulder 50 (Fig. 2) in contact with the middle flange 36. The annular refractory shoulder 50 is formed of solid, inflexible, noncompressible refractory material such as high density alumina castable material of the type sold under the designation Thermbond Formula 18, by the Stellar Company of Defray, Florida. The annular refractory shoulder 50 is joined to the lower surface portion 37 of the middle flange 36 by metal refractory anchors 54 (Figs. 2 and 3) which can be formed of stainless steel. As most clearly shown in Figs. 2 and 3 the metal anchors 54 are standard footed, double hook castable anchors of the type made by Refractory Anchors Inc. of Broken Arrow, Oklahoma. The anchors 54 include long and short leg portions 56 and 58 that diverge from a foot 60. A bend or hook portion 64 is provided at a free end of the long leg 56 and an opposite bend or hook portion 66 is provided at the free end of the short leg 58. It will be noted that the shorter leg 58 is oriented toward a center line 70 (Fig. 1) of the gasifier.

Some dimensional examples for the anchor 54 include a height of approximately 63 mm for the long leg 56 from the hook portion 64 to the lower face portion 37 of the metallic flange 36. The height of the short leg 58 from the hook portion 66 to the lower surface 37 of the metallic flange 36 can be approximately 50 mm. The thickness of each of the legs 56 and 58 and the foot 60 is approximately 5 mm, and the width of the anchor 54 from the hook portion 64 to the hook portion 66 is approximately 50 mm. The foot 60 of the anchor 54 extends approximately 15 mm in the plane of Fig. 2 and extend approximately 25 mm in a plane perpendicular to the plane of Fig. 2. Thus the extent of the foot 60 of the anchors 54 in a plane perpendicular to the plane of Fig. 2 is approximately 25 mm. The anchors 54 are welded at the foot 60 to the lower surface

37 of the metallic flange 36 and are spaced approximately 100 mm apart along a circular path with an approximate diameter equal to the inner diameter of the neck portion 14 plus the outer diameter of the hotface layer 22 divided by two, plus approximately 4 mm. The metal anchors 54 are thus located for example, along a circular center line having a radius of approximately 275 mm from the center line 70 (Fig. 1).

Under this arrangement approximately twelve anchors 54 are welded to the lower surface portion 37 of the metallic flange 36, although only six of the anchors 54 are shown in Fig. 3. The metal anchors 54 are fillet welded to the surface 37 preferably with Inconel® filler metal and the metallic flange 36 is preferably preheated to approximately 400° F prior to welding. The weld is continuous around the perimeter of the foot 60. Preferably the anchors 54 are oriented such that the plane of the shorter leg 58 for successive anchors 54 is at alternating plus 45° and minus 45° angles with respect to a radial line from the center line 70 of the gasifier 10.

Once the metal anchors 54 have been welded to the metallic flange 36, the annular refractory shoulder 50 (Fig. 3) is formed using a mold (not shown) of any suitable known construction that sits on the surface 37 of an overturned metallic flange 36. The molding operation should provide a profile for the shoulder 50 that projects approximately 75 mm from the lower surface portion 37 with an outer peripheral surface 74 that is substantially vertical and spaced approximately 5 mm from the interior surface 15a of the neck portionl4. The annular refractory shoulder 50 also includes an inner peripheral surface 76 that is sloped slightly toward the outer peripheral surface 74 along a direction toward a free end surface 78 of the shoulder 50.

For example, the free end surface 78 is preferably approximately 6 mm narrower than the opposite surface of the shoulder 50 that contacts the lower surface 37 of the metallic flange 36. The inner peripheral surface is spaced approximately 10 mm from the outer peripheral surface 100 of the hotface layer 22 (Fig. 2).

The inner diameter of the inner peripheral surface 76 of the shoulder 50 at the lower surface portion 37 is, for example, approximately equal to the outer diameter of the hotface layer 22 plus approximately 7 mm. The inner diameter of the inner peripheral surface 76 of the shoulder 50 at the end surface 78 is, for example, approximately equal to the outer diameter of the hotface layer 24 plus approximately 13 mm.

Once the annular refractory shoulder 50 is cured, the metallic flange 36 and the refractory shoulder 50 can be dried out to approximately 400° C which temperature can be maintained, for example, for at least four hours. Alternatively, the metallic flange 36 with the newly cured refractory shoulder 50 can be installed on the gasifier and the dry out procedure may take place following installation of the middle flange 36 onto the gasifier, during preheating of the gasifier. However, the dry out procedure of the annular refractory shoulder 50 during preheating of the gasifier 10 may require the gasifier 10 to be heated up at a slower rate than might otherwise be achieved.

Prior to installing the metallic flange 36 with the refractory shoulder 50 on the gasifier neck 14, a refractory fiber thermal expansion gasket 90 is installed behind the outer peripheral surface 100 of the hotface layer 22. The refractory fiber gasket 90 is positioned in uncompressed form on the backup layer top surface 20. The core of the refractory fiber gasket 90 can include three single piece rings 92, 94 and 96 (Fig. 2) of approximately 25 mm thick refractory blanket rated for at least 1250° C service. The rings 92, 94 and 96 can have an inner diameter, for example, of approximately 1 mm greater than the inner diameter of the backup layer 18, and an outer diameter, for example, of approximately 1 mm less than the inner diameter of the neck portion 14 at the interior surface 15a. The three rings 92, 94 and 96 of refractory fiber blanket are preferably stacked one on top of another and encased in a sheath 98 of approximately 1 mm thick ceramic cloth rated for at least 1250° C service.

Ideally the refractory fiber gasket 90 should be preassembled and installed as single unit into the annular channel 30. It should be noted that the refractory fiber gasket 90 may be subject to damaging frictional stresses at the outer peripheral surface 100 (Fig. 2) of the hotface layer 22. Thus it is desirable that the ceramic cloth 98 be very resilient, and can incorporate high temperature alloy wire fibers such as Inconel®. Also, before the metallic flange 36 with the annular refractory shoulder 50 is installed on the gasifier neck 14, a single coil 82 (Fig. 2) of refractory rope approximately 13 mm in diameter, for example, is attached to, and compressed against the outer peripheral surface 100 of the hotface layer 22 just above the refractory fiber gasket 90. The coil of rope 82 is preferably a single piece extending around the full circumference of the outer peripheral surface 100 of the hotface layer 22 and is held in place with a combustible material such as adhesive tape (not shown) that will compress the coil of rope 82 as much as possible, preferably flattening it out to less than 10 mm. During heatup of the gasifier, the combustible tape will burn away, allowing the coil of rope to expand to its normal uncompressed thickness.

Such compression of the coil of rope 82 is desirable to enable the free end 78 of the refractory shoulder 50 to slip past the rope 82 (Fig. 2) when the refractory shoulder 50 is lowered into the annular channel 30 upon installation of the metallic flange 36 onto the gasifier neck 14. The annular coil of rope thus occupies an annular channel space 102 (Fig. 2) between the inner peripheral surface 76 of the annular refractory shoulder 54 and the outer peripheral surface 100 of the hotface layer 22, to essentially plug the space 102.

As previously indicated the inner peripheral surface 76 of the annular refractory shoulder 50 is sloped slightly toward the free end surface 78. Thus the space 102 must necessarily become narrower in an upward direction from the refractory fiber gasket 90. The sloped peripheral surface 76 is thus intended to prevent the coil of rope 82 from being sucked out of the space 102 since the rope 82 will be compressed when it is rolled upward in the space 102 because of heat expansion of the hotface layer 22.

The metallic flange 36 with the annular refractory shoulder 50 is then precisely positioned on the top of the neck portion 14, as shown in Figs. 1, 2 and 5, after the coil of rope 82 is joined to the outer peripheral surface 100 of the hotface layer 22. Precise positioning of the metallic flange 36 is required to ensure that the annular refractory shoulder aligns with the annular channel 30 and is located therein without interfering with the neck portion 14 or the hotface layer 22.

Under this arrangement, the annular refractory shoulder 50 and the ceramic rope 82, being essentially gas impermeable materials, prevent hot syngas from the reaction chamber 17 from passing through the refractory fiber gasket 90 toward the gasifier shell surface 15a and 15 at the neck portion 14. The gas impermeable refractory shoulder 50 also prevents hot syngas from passing directly through the refractory shoulder 50 toward the gasifier shell surface 15a at the gasifier neck 14. During operation of the gasifier 10, the hotface layer 22 expands in an upward direction toward the metallic flange 36 and thus slides past the refractory shoulder 50 as the gasifier heats up to operating temperature. Ideally, the inner peripheral surface 76 of the refractory shoulder 50 should come as close as possible to the outer peripheral surface 100 of the hotface layer 22. However, since manufacturing and installation tolerances must ensure that there is no interference between the refractory shoulder 50 and the hotface layer 22 the refractory fiber rope 82 is compressed into the clearance space 102 (Fig. 2) between the shoulder 50 and the hotface layer 22, thus significantly limiting the amount of gas that might otherwise pass through.

Once the gasifier is at operating temperature the portion of the expansion gap between the top surface 24 of the hotface layer 22 and the metallic flange 36 can be as small as 3 mm, thereby minimizing the volume of gas that reaches the refractory shoulder 50, thus resulting in a significant reduction in temperature rise of the gasifier shell 12 during operation.

It should be noted that ambient temperature distance measurements between the lower surface 37 of the metallic flange 36 and the top surfaces 20 and 24 of the backup layer and hotface layer can be approximated before the metallic flange 36 is installed. Such approximation is accomplished by taking measurements relative to the top edge 32 of the gasifier neck with a correction for thickness of a compressed gasket that is provided between the metallic flange 36 and the top edge 32 of the gasifier neck. Some advantages of the invention evident from the foregoing description include a protective structure for an expansion gap that is essentially formed of gas impermeable refractory material that blocks passage of hot syngas through the expansion gap toward the gasifier shell. The expansion gap protection structure includes a solid annular refractory shoulder that is non-compressible and inflexible. The refractory shoulder cooperates with a coil of relatively incompressible refractory rope to bear against relatively compressible fibrous refractory material and substantially block the relatively compressible fibrous refractory material from exposure to syngas from the reaction chamber of the gasifier.

A further advantage is that the hotface bricks installed in the gasifier can be installed to a level that provides a substantially smaller gap between the hotface layer and the metallic flange than previously existed because there is no need to provide any fibrous material between the top surface of the hotface layer and the metallic flange. Thus it is possible to obtain substantial closure of the portion of the expansion gap between the top end of the hotface layer and the metallic flange. The portion of the expansion gap between the hotface layer and the metallic flange can thus be minimized. In view of the above it will be seen that the several objects of the invention are achieved and other advantageous results attained. As various changes can be made in the above constructions and methods without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claims

What is claimed is:

1. A gasifier comprising, a) a metallic gasifier shell with an inside surface and a neck opening, b) a metallic flange disposed over the neck opening, c) a reaction chamber within the gasifier shell, d) a refractory lining on the inside surface of the gasifier shell at the reaction chamber, the refractory lining having a top portion below the neck opening such that the inside surface of the gasifier shell above the top portion of the refractory lining is not covered by refractory lining and an expansion gap for the refractory lining is defined above the top portion of the refractory lining, and e) an expansion gap protection structure including an annular refractory shoulder formed of solid, inflexible, non-compressible refractory material in contact with the metallic flange and extending from the metal flange into the expansion gap.

2. The gasifier as claimed in claim 1 wherein the refractory lining includes a hotface layer confronting the reaction chamber, the hotface layer having a first top edge portion at the top portion of the refractory lining, the first top edge portion being spaced below the neck opening, the refractory lining further including a backup layer between the inside surface of the gasifier shell and the hotface layer, the backup layer having a second top edge portion at the top portion of the refractory lining, the second top edge portion being spaced below the first top edge portion whereby an annular channel is defined above the second top edge portion of the backup layer between the hotface layer and the inside surface of the gasifier shell.

3. The gasifier as claimed in claim 2 wherein the annular refractory shoulder extends into the annular channel and includes an inner peripheral surface space from the hotface layer and an outer peripheral surface, spaced from the inside surface of the gasifier shell.

4. The gasifier as claimed in claim 3 wherein the annular channel has a first annular width from the hotface layer to the inner peripheral surface of the annular refractory shoulder, and an annular coil of refractory rope is joined to the outer peripheral surface of the hotface layer wherein the cross-sectional diameter of the coil of refractory rope occupies the first annular width of the annular channel.

5. The gasifier as claimed in claim 4 wherein the annular refractory shoulder has a bottom free end surface and the inner peripheral surface of the annular refractory shoulder is sloped toward the outer peripheral surface in a direction toward the bottom free end surface and the annular coil of refractory rope is joined to the outer peripheral surface of the hotface layer near the bottom free end surface of the annular refractory shoulder.

6. The gasifier as claimed in claim 3 wherein the expansion gap protection structure further includes compressible annular refractory fibrous gasket means disposed in the annular channel, the annular refractory fibrous gasket means and the annular refractory shoulder having selected heights that enable the annular refractory fibrous gasket means to be engaged by the annular refractory shoulder, when the annular shoulder extends into the annular channel.

7. The gasifier as claimed in claim 1 including means for joining the annular refractory shoulder to the metallic flange.

8. The gasifier as claimed in claim 7 wherein the joining means extend into the annular refractory shoulder and include a plurality of spaced metallic anchor members welded to the metallic flange.

9. The gasifier as claimed in claim 1 wherein the expansion gap protection structure further includes compressible annular refractory fibrous gasket means disposed in the expansion gap, the annular refractory fibrous gasket means having a selected height in the expansion gap that permits engagement with the annular refractory shoulder.

10. The gasifier as claimed in claim 9 wherein the annular refractory fibrous gasket means is compressible and has a top surface and the annular refractory shoulder has a bottom surface that contacts and covers a major portion of the area of the top surface of the annular refractory fibrous gasket means.

11. The gasifier as claimed in claim 10 wherein the refractory lining includes a hotface layer having an inner hotface surface confronting the reaction chamber, and an outer surface facing toward the gasifier shell and wherein the annular refractory shoulder has an inner peripheral surface spaced from the outer surface of the hotface layer and wherein an annular coil of refractory rope is joined to the outer peripheral surface of the hotface layer to occupy the space between the inner peripheral surface of the annular refractory shoulder and the outer surface of the hotface layer.

12. A gasifier comprising, a) a metallic gasifier shell with an inside surface, a top portion and an opening at the top portion, b) a metallic flange disposed over the top portion at the opening, c) an interior reaction chamber with a refractory lining on the inside surface of the metallic shell, the refractory lining including a hotface layer with a first annular top edge spaced below the top portion opening, and a backup layer with a second annular top edge spaced below the first annular top edge of the hotface layer, such that the inside surface of the gasifier shell above the first annular top edge of the hotface layer and above the second annular top edge of the backup layer is not covered by refractory lining, and an expansion gap is defined above the first and second annular top edges of the hotface layer and the backup layer, and d) an expansion gap protection structure including a solid inflexible, noncompressible annular refractory shoulder extending downwardly from the metallic flange into an annular space between the hotface layer and the inside surface of the gasifier shell to a depth that is lower than the first annular top edge of the hotface layer and higher than the second annular top edge of the backup layer.

13. The gasifier as claimed in claim 12 wherein the expansion gap protection structure includes compressible annular refractory fibrous gasket means on the second annular top edge of backup layer, the annular refractory fibrous gasket means having an upper surface and a selected height from the second annular top edge that enables the upper surface of the annular refractory fibrous gasket means to be engaged by the annular refractory shoulder.

14. The gasifier as claimed in claim 13 wherein the hotface layer has an outer surface facing toward the gasifier shell and the annular refractory shoulder includes an inner peripheral surface, spaced from the outer surface of the hotface layer and wherein an annular coil of refractory rope is joined to the outer surface of the hotface layer to occupy the space between the inner peripheral surface of the annular refractory shoulder and the outer surface of the hotface layer.

15. The gasifier as claimed in claim 14 wherein the inner peripheral surface of the annular refractory shoulder is sloped away from the outer surface of the hotface layer in a direction toward the fibrous gasket means and the annular coil of refractory rope is joined to the outer surface of the hotface layer at the upper surface of the annular refractory fibrous gasket means.

16. The gasifier as claimed in claim 12 including means for joining the annular refractory shoulder to the metallic flange.

17. The gasifier as claimed in claim 16 wherein the joining means include a plurality of spaced metallic anchor members welded to the metallic flange.

18. A method of blocking hot gas from the reaction chamber of a gasifier from bypassing an expansion gap of a refractory lining and accessing the gasifier shell at the expansion gap comprising, a) providing a stepped annular expansion gap in the refractory lining below a gasifier neck wherein a hotface layer of the refractory lining extends above the top end portion of a backup layer of the refractory lining such that an annular channel is defined above the backup layer between the hotface layer and the gasifier shell, b) filling a selected height of the annular channel with compressible annular refractory fibrous gasket means, c) forming a solid, inflexible, noncompressible annular refractory shoulder on a metallic flange for the gasifier neck and sizing the refractory shoulder to fit into the annular channel to a selected depth in the annular channel to engage the selected height of the compressible annular refractory fibrous gasket means, and d) positioning the metallic flange with the annular refractory shoulder on the gasifier neck to enable the annular refractory shoulder to extend into the annular channel and engage the compressible annular refractory fibrous gasket means.

19. The method of claim 18 including providing a selected annular space between the annular refractory shoulder and the hotface layer and providing an annular coil of refractory rope in the space between the annular refractory shoulder and the hotface layer to plug the annular space.

20. The method of claim 19 including forming a slope on the annular refractory shoulder at an inner peripheral surface of the annular refractory shoulder such that the inner peripheral surface slopes toward the outer peripheral surface in a direction toward the annular refractory fibrous gasket means.