GB2103103A - Multi-zone process and reactor for cracking heavy hydrocarbon feeds - Google Patents

Abstract

In a multiple-zone fluidized bed conversion process and apparatus for producing light distillate liquid and fuel gas products from heavy hydrocarbon feedstocks, the feedstock is introduced into an upper fluidized bed cracking zone 14 maintained at a temperature of 482-760 DEG C (900-1400 DEG F) for cracking reactions, and resulting tars and coke are deposited on and within a particulate carrier material 17 therein. The carrier material descends through a stripping zone 18 to remove tars and then into a lower fluidized bed gasification zone 20, which is maintained at a temperature of 927-1093 DEG C (1700-2000 DEG F) by O2-containing gas and steam introduced therein at 22 to gasify the coke and produce a reducing gas. The stripping zone 18 contains coarse packing material 19 which is supported by a refractory annular- shaped grid 34. The decoked hot particulate carrier is recirculated by a transport gas supplied at 24, upwardly through a central refractory-lined conduit 28 to the upper bed. Such recycle of the carrier solids is controlled by a refractory-lined gas- cooled valve 50. <IMAGE>

Description

SPECIFICATION Multi-zone process and reactor for cracking heavy hydrocarbon feeds This invention relates to an improved multiple zone fluidized bed cracking process for conversion of heavy hydrocarbon feeds to produce lighter hydrocarbon liquids and fuel gas. It relates particularly to such a conversion process and apparatus utilizing multiple zones of a fluidized bed of particulate carrier material to facilitate cracking the feed in the upper zone and gasification of tars and coke deposited on and within the carrier in a lower refractory-lined gasification zone.

Considerable work has previously been done for the multi-stage gasification of heavy oil feeds in fluidized beds, some processes using a particulate carrier material for deposition of carbon, and for the multiple-stage gasification of coal. Some typical pertinent patents include U.S. Patent No.

2,861,943 to Finneran, and U.S. Patent No.

2,885,343 to Woebcke, which disclose the use of a circulating particulate carrierfor coke laydown from crude and residual oil feedstocks. Also, U.S.

Patent No. 2,875,150 to Schuman and U.S.

Patent No. 3,202,603 to Keith disclose a multiplebed hydro-gasification process for residual oils and tar feeds using a particulate carrier material for hydrocracking the heavy oil feed to produce gas and liquid fractions. However, no disclosure is made regarding important process steps and construction features required for a multi-zone reactor vessel of commercial scale.

There has thus been an unfulfilled need for a practical conversion and gasification process for heavy hydrocarbon feeds such as residual oils to produce distillable liquids and fuel gas, and which would also effectively gasify tars and coke evolved from the feed within the same reactor vessel and produce clean fuel gas and liquid products, and provide a reactor design suitable for commercialscale operations.

The present invention provides a process for conversion of a heavy hydrocarbon feedstock to produce lighter hydrocarbon liquids and fuel gases, comprising: (a) introducing the feedstock into a pressurized upper fluidized bed cracking zone maintained at a temperature within the range of 482-7600C (900--14000F), said zone containing a fluidized bed of particulate carrier material which is fluidized by upflowing reducing gases passing therethrough:: (b) passing the carrier material containing coke deposits downwardly through an intermediate stripping zone into a lowerfluidized bed gasification zone to gasify the coke deposits from the carrier material therein; (c) injecting an oxygen-containing gas and steam into the lower gasification zone for reaction with said coke deposited on and within the carrier material and to maintain a temperature within the range of 927-1 0930C (1 700--20000 F) for coke gasification and to produce the reducing gases; (d) passing said reducing gases upwardly successively through said stripping zone and through said fluidized bed in the upper cracking zone to fluidize the bed;; (e) passing the resulting hot decoked particulate carrier material from the lower gasification zone radially inward through passageways to the lower end of a vertical transfer conduit at a point below the oxygencontaining gas injection point, and recycling said solids upwardly through a control valve and the conduit into the upper cracking zone at a controlled rate using a transport gas flowing in said conduit at a velocity sufficient to carry said solids; (f) separating the resultant product gases from said particulate matter above the upper cracking zone and returning said separated particulate matter to the reaction zone for further use; and (g) withdrawing effluent gas and distillable liquid products from said upper cracking zone.

The invention also provides a multi-zone reactor assembly for cracking and conversion of heavy hydrocarbon feedstocks to produce lighter liquid and gas products, comprising: (a) a pressurizable metal reactor vessel; (b) a conversion zone located in the reactor upper end for providing a fluidized bed reaction; (c) means for introducing a hydrocarbon liquid feed into said conversion zone; (d) an annular-shaped gasification chamber located in the reactor lower end for containing a fluidized bed gasification reaction; (e) conduit means for introducing an oxygencontaining gas and steam into said lower gasification reaction zone; (f) a stripping zone located intermediate the upper conversion zone and the lower gasification zone, said stripping zone containing a coarse-sized particulate packing material;; (g) outer refractory-lining means provided within said annular-shaped lower gasification reaction zone, wherein said refractory lining is adapted to allow for differential thermal expansion between the lining and the vessel metal outer wall; (h) an inner cylindrical-shaped refractory wall which is supported from the outer refractory lining; (i) conduit means for circulating a particulate carrier material from the lower gasification zone upwardly to the upper conversion zone, said conduit being refractory-lined and supported from said inner refractory wall; (j) means for introducing a transport gas into the lower end of the said conduit; and (k) means for removing the resultant product gases from the upper portion of said reactor vessel.

According to the invention, a multi-zone reaction process and apparatus are provided for cracking and conversion of heavy hydrocarbon feeds, such as crude oil and residual feedstocks and mixtures of such oils with coal, to produce lighter lower-boiling hydrocarbon liquid and gaseous products. The invention utilises a multi zone reactor vessel having an upper cracking or conversion zone and a lower gasification or combustion zone, separated by an intermediate stripping zone which contains a particulate packing material of sufficient voidage to permit downward passage of particulate carrier material.

The upper and lower zones as well as the stripping zone contain a bed of particulate carrier material, which is continuously circulated through the three zones.

Because of the high temperatures required in the gasification and stripping zones, such as 760-10930C (14002000 F), these zones are entirely lined with refractory materials so as to effectively limit temperature of the metal walls to safe levels, and thus avoid undesirable loss of strength and also prevent corrosion and erosion of the base metals. The reactor design is adapted to utilize the inherent high temperature strength of these refractory materials for structural purposes in unique and advantageous ways. The coarse packing material used in the intermediate stripping zone is supported by an annular-shaped apertured refractory grid member, which preferably has an arch-shaped cross section.This grid is in turn supported at its outer and inner circular edges by the refractory lining structures of the annular-shaped lower gasification chamber or zone.

The hot particulate carrier material is recirculated from the lower gasification or combustion zone upwardly to the upper cracking or conversion zone through a vertical transfer conduit. This conduit comprises a tube of temperature-resistant metal which is refractorylined to prevent erosion by the upflowing particles.

The conduit metal tube is supported entirely from the inner refractory lining or column of the annular-shaped gasification chamber.

Furthermore, the lower end of the refractory-lined central conduit is reduced in diameter and provides the refractory-coated seating surface for a control valve, which controls the recirculation rate of the particulate carrier solids from the lower gasification zone or chamber upward to the cracking or conversion zone. Also, the control valve has a plug member which is refractorycoated to provide erosion protection and long service life. The recirculation of particulate solids is facilitated by a transport gas which is passed upwardly through the valve plug assembly to a point above the valve seat. Also, the valve plug is cooled effectively by the upflowing gas stream, which is preferably steam or a process gas stream provided at temperature not exceeding about 3990C (75O0F).

Reference is now made to the accompanying drawings, in which: Figure 1 is a cross-sectional view of an overall multi-zone reactor configuration according to a preferred embodiment of the invention showing internal details of the reactor assembly, including support details for the refractory lining and grid; Figure 2 is an isometric view of two typical sectors of the annular-shaped apertured refractory grid structure; and Figure 3 is a cross-sectional view showing configuration of the solids recirculation control valve assembly and conduit.

As shown in Figure 1, a feedstream of heavy petroieum crude or residuum oil at 10, such as obtained from previous distillation steps, is pressurized at 12, and preheated as required at 13, such as to 121--316"C (250--6000F) temperature. The preheated stream is introduced through a suitable sparger device 1 4a into the upper primary cracking zone 14 of a multi-zone reactor 1 6. Optionally, oil-coal slurry may be fed directly into the zone 14 through the line 11. The zone 14 contains a fluidized bed 15 of a particulate solid carrier material 17, which is maintained at a temperature within the range of 482-7600C (90O140O0 F) so that the heavy hydrocarbon feed material is further heated and thermally cracked therein.The reactor pressure is usually maintained within the range of 13.8-55 bar gauge (200-800 psig), although higher pressures could be used. The bed 1 5 is fluidized by upflowing reducing gases produced in a lower zone. Some coke produced in the cracking reaction is deposited on and within the carrier material 1 7. The resulting product gas along with some fine particles of carrier material are passed upwardly through a cyclone separator 30 and the gas exits from the reactor.

The majority of the particulate carrier material in zone 14, usually containing 3-25 W % coke deposits and heavy liquid hydrocarbons, descends through the adjacent intermediate packed stripping zone 1 8 where some liquids are stripped from the particles by upflowing gases. The stripped dry solids then descend to the lower gasification zone 20 containing a fluidized bed 21, which is maintained at a temperature within the range of 927-1 0930C (1700--20000F). Here char and coke deposited on and within the carrier material are gasified in the presence of an oxygencontaining gas and steam introduced into the bed 21 at a nozzle 22 through a distributor 23.Some tars formed in the upper fluidized bed 1 5 and deposited on and within the carrier material 17 may be carried to the lower bed 21, where the tars are gasified and removed from the carrier. Some tars may undergo secondary cracking to lighter liquid and gaseous hydrocarbon in the stripping zone 18.

The selection of a suitable particulate carrier material 1 7 with respect to its absorptive characteristics and pore distribution is such as to collect substantially all tars, char and coke from cracked products evolved in the upper zone 14 and bed 1 5. After gasification of tars, char and coke in the lower fluidized bed 21 , the particulate carrier material 1 7 is recirculated to the upper bed with the aid of a transport gas supplied at 24, such as steam or a product recycle gas, and passed through a vertical transfer conduit 28 and control valve assembly 50.

The lower gasification zone 20 is annularshaped and is lined with a refractory material provided on its outer wall 25, in the lower head 1 6b, and inner wall 26, such as Greencast No. 94 obtainable from A. P. Green Co. The inner refractory wall 26 is cylindrical-shaped and is preferably supported from the refractory material lining 1 6b provided in the reactor lower head.

Multiple openings 27 are provided in the lower end of the inner refractory wall 26 for passage of the solid carrier particles 1 7 from the gasification chamber 20 to the lower end of the transfer conduit 28. These openings 27 are preferably provided with tubular liners 27a, composed of a hard refractory material which is more resistant to abrasion and erosion by the flowing solid particles 1 7 than the refractory structure 26b. Alternatively, multiple passages 27 can be provided in the solid refractory material in the lower head 16b.In any event, it is essential that the inlet to the passages 27 be located at a point below the distributor 23 for introducing the oxygen-containing gas into the fluidized bed 20, to prevent any oxygen-containing gas being passed into the vertical conduit 28, which is preferably centrally located in the reactor.

Flow control of the particulate carrier material 1 7 flowing into the transfer conduit 28 at its bottom end is provided by the control valve assembly 50. The carrier material is suspended and lifted to the upper bed 14 by the transport gas supplied at the connection 24. The upper end of the conduit 28 terminates within the fluidized bed 14. Some of the carrier material may be carried by the effluent gas from the zone 14 to the internai cyclone separator system 30, which serves to trap most of the particulate carrier material and return it to the cracking zone 14. Makeup carrier material may be added to the reactor as needed, usually through a pressure-lock hopper system 31. Spent carrier material may be similarly withdrawn through a conduit 32.

The intermediate stripping zone 1 8 contains a coarse solid packing material 1 9 having a size at least about 10 times greater than the particulate carrier material 1 7 and provides sufficient voidage to permit downward passage of the particulate solids. The packing material 19 may comprise ceramic Raschig rings, saddles, or similar materials and shapes. This packing 19 is supported by an annular-shaped apertured grid structure 34. To limit pressure drop across the intermediate stripping section 18, and to facilitate the downward flow of particulate solids 17 therethrough, the packing material 1 9 can have a relatively coarse size, such as 1.3-5.1 cm (0.5-2.0 inch) effective diameter.The apertures 34a provided in sectors 35 of the grid 34 for gas and solids flow are sized to prevent any downflow of the packing 1 9 and can likewise be made relatively large and have various shapes such as circular, square or elongated, as is generally shown in Figure 2.

Depending on the feedstock used, i.e., heavy oil or oil-coal slurry, gas and liquid products, along with the minor amount of small particle size unconverted coke and a large portion of small particle size ash, leave the reactor as a stream 37 and pass to an external cyclone solids separation system 38. This separation step removes any remaining coke and ash particles from the product gas stream as a disposal stream 39. The resulting cyclone effluent stream 40 is then usually quenched at 41, such as by an oil stream, or otherwise cooled to reduce its temperature and limit or prevent further undesired reactions. The cooled gas and liquids are then separated using conventional fractionation means at 44 to provide a product gas stream 45, a light liquid stream 46, and a heavier liquid fraction 47.If desired, a portion 48 of the heavy fraction can be recycled to the cracking zone 1 4 for further reaction.

With further reference to the annular-shaped apertured grid 34 which supports the coarse packing 1 9 in the stripping section 18, it is made of a strong refractory material suitable for withstanding extended temperatures of about 10930C (20000 F), such as Cerox 600 obtainable from C-E Refractories, Inc. The grid has an archshaped cross-section so as to remain tight and in compression to prevent any loss of packing 1 9 from above, even if a crack should develop in the grid. The grid is composed of multiple sectors 35, two of which are typically shown in Figure 2. The use of such radial sectors permits the grid to be installed through a manway opening, such as a manway 33 located at the top of the reactor.

These sectors 35 rest on outer and inner circular shoulder surfaces 25a and 26a, respectively, in the refractory lining 25 and wall 26. The sectors 35 are held in place mainly by the weight of the coarse packing 1 9 located immediately above, and for which they provide support. The apertures 34a are sized to prevent the packing material 1 9 from passing therethrough, and can be made any shape such as circular, square, or elongated. If desired, the upper surface of the grid sectors 35 can be made dimpled so as to prevent pieces of packing material 1 9 from obstructing the grid openings 34a.

Following combustion in the lower gasification zone 20 of the coke deposited on the particulate carrier material 17, the hot decoked carrier solids are passed radially inwardly through the openings 27 and control valve 50, and are thereby transferred from the gasification zone 20 through the updraft conduit 28 by use of the transport gas supplied at 24. This conduit 28 is preferably centrally located in the reactor 16, and comprises a pressure-tight heat-resistant metal tube 29 which has a refractory-lining 29a, which prevents metal erosion by the upflowing particulate carrier solids 17. A suitable refractory lining material is RESCO Cast No. AA-22, produced by RESCO Products, Inc., which is placed within the tube 29.

The updraft conduit assembly 28 is rigidly attached to and supported from the upper end of the inner refractory lining or column 26, and is preferably attached to the refractory column 26 at a point 28a, such as by bolts 28b which are cast into the refractory wall 26.

Figure 3 shows a cross-sectional view of the control valve assembly 50, comprising refractorycoated valve seat 51 and a cooled plug 54 which controls recycle of the hot decoked particulate solids 1 7 from the lower combustion zone 20 to the upper cracking zone 14. The central conduit 28 is reduced in diameter at its lower end 28c sufficient to provide the valve seat member 51. If desired, the seat element 51 can be made removable from the conduit end 28c, such as by a bolted flange joint 52, for the purpose of repair or replacement as needed.

The valve plug assembly 54 comprises a metal tube 55 which has an enlargement portion 56 located intermediate the tube ends, and serves as the valve plug structure mating with the seat member 51. The upper portion of the tube 55 and enlargement 56 are coated with refractory material 57. The enlargement 56 contains a horizontal plate element 58, and also contains multiple openings 58a in the plate 58 and openings 55a in the tube 55, which serve to divert the upward flow of transport gas through the openings to effectively cool the metal portions of the plug assembly 54. Also, the tube 55 and its refractory coating 57 extend above the seating surface 51 by a distance at least equal to the inner diameter of the seat 51, and preferably by 1.5-1 0 times that diameter.Refractory material 59 is also provided around the tube 55 below the enlargement 56 to prevent tube erosion by the solids 1 7 flowing radially inwardly. The gas flowing upward through the tube 55 and its extension 55b facilitates recirculation of the hot carrier solids 1 7 upwardly through the valve seat 51 and conduit 28.

The transport gas used for suspending and transferring the hot particulate solid 1 7 upwardly through the conduit 28 is introduced at the opening 24 and passed upwardly through the tube 55 at a velocity of at least about 1.8 m (6 ft)/sec and preferably at 3.0-12.2 m (10--40 ft)/sec.

This gas flow also serves to cool the valve plug 54.

This transport and cooling gas is preferably a process gas stream, such as steam or recycled product fuel gas having an initial temperature not exceeding about 3990C (75O0F).

A packing gland 60 is provided around the tube 55 to prevent transport gas bypassing the tube and also to prevent particulate carrier solids 1 7 from entering the gas flow passageway 61 around the tube 55. The packing gland 60 is covered by a refractory plate 64 for erosion protection. The valve plug assembly 54 is moved axially as needed using a suitable actuator device (not shown) to control the upward flow of particulate solids 17, by an actuator rod 66, which is connected to the tube 55 by a radial bracket 67 and is pressure sealed by a lower packing gland 68. The entire control valve assembly 54 is removable from the lower and of the central conduit 28 and valve seat 51 by disconnecting a bolted flange 70 and removing the assembly downwardly for inspection or repair.

During start-up of the multi-zone reactor 1 6 from cold or near ambient conditions, the central conduit 28 is heated and expands in a downward direction. The plug assembly 54 is likewise withdrawn by the actuator device (not shown) to prevent any excessive compressive force being developed between the valve plug 54 and seat surface 51. The transport gas supplied at 24 flows upwardly through the tube 55 to facilitate the recirculation of particulate carrier solids 1 7 from the lower gasification zone 20 to the upper cracking zone 14.

Claims (21)

1. A process for conversion of a heavy hydrocarbon feedstock to produce lighter hydrocarbon liquids and fuel gases, comprising: (a) introducing the feedstock into a pressurized upper fluidized bed cracking zone maintained at a temperature within the range of 482-7600C (900--14000F), said zone containing a fluidized bed of particulate carrier material which is fluidized by upflowing reducing gases passing therethrough; (b) passing the carrier material containing coke deposits downwardly through an intermediate stripping zone into a lower fluidized bed gasification zone to gasify the coke deposits from the carrier material therein;; (c) injecting an oxygen-containing gas and steam into the lower gasification zone for reaction with said coke deposited on and within the carrier material and to maintain a temperature within the range of 927--10930C (1700--20000F) for coke gasification and to produce the reducing gases; (d) passing said reducing gases upwardly successively through said stripping zone and through said fluidized bed in the upper cracking zone to fluidize the bed;; (e) passing the resulting hot decoked particulate carrier material from the lower gasification zone radially inward through passageways to the lower end of a vertical transfer conduit at a point below the oxygencontaining gas injection point, and recycling said solids upwardly through a control valve and the conduit into the upper cracking zone at a controlled rate using a transport gas flowing in said conduit at a velocity sufficient to carry said solids; (f) separating the resultant product gases from said particulate matter above the upper cracking zone and returning said separated particulate matter to the reaction zone for further use; and (g) withdrawing effluent gas and distillable liquid products from said upper cracking zone.

2. A process according to claim 1, wherein the recycle of decoked particulate carrier solids to the upper cracking zone is controlled by passing the transport gas upwardly through a hollow plug portion of a control valve assembly and into said transfer conduit, and wherein the upflowing gas velocity in said conduit is at least about 1.8 m (6 ft)/sec.

3. A process according to claim 2, wherein the transport gas is provided at a temperature not exceeding about 399"C (7500 Fl and the control valve plug portion is cooled internally by passing the transport gas upwardly through said plug.

4. A process according to any of claims 1 to 3, wherein said product gases and said particulate matter are separated externally to said reaction zones, the particulate matter is recycled to the reaction vessel, and the clean effluent stream is cooled and passed to a fractionation step for recovery of gas and distillable liquid products.

5. A process according to any of claims 1 to 4, wherein the feedstock includes coal particles, and including the additional step of withdrawing particulate ash from a lower portion of said gasification zone.

6. A process for converting heavy hydrocarbon feedstocks to produce lighter hydrocarbon liquids and fuel gases wherein the feedstock is introduced into an upperfluidized bed cracking zone maintained within a temperature range of 482-76O0C (900--1 4000 F), and coke is deposited on and within a particulate carrier material which is passed downwardly through a packed stripping zone, and wherein oxygencontaining gas and steam are injected into a lower fluidized bed gasification zone to gasify coke deposited on and within a particulate carrier material and produce a reducing gas which passes upwardly to fluidize the reactor zones, wherein the improvement comprises controlling the recirculation rate of the particulate solids flowing from the lower gasification zone to the upper cracking zone by passing a transport gas upwardly through a control valve hollow plug to a point above the valve seat surface.

7. A process according to claim 6, including the additional step of cooling the solids recirculation control valve plug by passing the transport gas at a temperature not exceeding about 3990C (7500F) upwardly through passages in the valve plug.

8. A multi-zone reactor assembly for cracking and conversion of heavy hydrocarbon feedstocks to produce lighter liquid and gas products, comprising: (a) a pressurizable metal reactor vessel; (b) a conversion zone located in the reactor upper end for providing a fluidized bed reaction; (c) means for introducing a hydrocarbon liquid feed into said conversion zone; (d) an annular-shaped gasification chamber located in the reactor lower end for containing a fluidized bed gasification reaction; (e) conduit means for introducing an oxygencontaining gas and steam into said lower gasification reaction zone; (f) a stripping zone located intermediate the upper conversion zone and the lower gasification zone, said stripping zone containing a coarse-sized particulate packing material;; (g) outer refractory-lining means provided within said annular-shaped lower gasification reaction zone, wherein said refractory lining is adapted to allow for differential thermal expansion between the lining and the vessel metal outer wall; (h) an inner cylindrical-shaped refractory wall which is supported from the outer refractory lining; (i) conduit means for circulating a particulate carrier material from the lower gasification zone upwardly to the upper conversion zone, said conduit being refractory-lined and supported from said inner refractory wall; (j) means for introducing a transport gas into the lower end of the said conduit; and (k) means for removing the resultant product gases from the upper portion of said reactor vessel.

9. A reactor assembly according to claim 8, wherein the coarse packing material inthe intermediate stripping zone is supported by an apertured annular-shaped grid made of refractory material and located at the upper end of the gasification reaction zone.

10. A reactor assembly according to claim 9, wherein said grid is arch-shaped and comprises multiple radial sectors which are each supported by the refractory lining of the annular-shaped lower gasification zone, said sectors being removable from the reactor vessel.

11. A reactor assembly according to any of claims 8 to 10, wherein each zone contains a particulate carrier material which is fluidized and is recirculated from said upper conversion zone downwardly through said stripping zone to said lower gasification zone, then returned upwardly through a control valve and central refractorylined conduit to said upper reaction zone.

1 2. A reactor assembly according to any of claims 8 to 11, wherein a refractory-lined phase separation device is provided above the conversion zone to remove particulate carrier material and return it to the reactor vessel.

13. A reactor assembly according to claim 11, wherein the recirculated particulate carrier material passes upwardly through a refractorylined control valve located at the lower end of the central conduit.

14. A reactor assembly according to claim 11, wherein the control valve seating surface is formed by the lower end of the central conduit, and said conduit lower end is refractory-coated on both inner and outer sides.

1 5. A reactor assembly according to claim 14, wherein the valve seating portion is made removable from said central conduit.

1 6. A reactor assembly according to claim 11, wherein the solids control valve plug is coated with a refractory material and has internal flow passages for cooling said plug by the upflowing transport gas.

17. A reactor assembly according to claim 1 6, wherein said valve plug refractory coating extends above the plug surface by a distance at least equal to the valve seat inner diameter.

18. A multi-zone reactor assembly for cracking and conversion of heavy hydrocarbon feedstocks to produce lighter liquid and gas products, comprising: (a) a pressurizable metal reactor vessel; (b) a conversion zone located in the reactor upper end and containing a particulate carrier material for providing a fluidized bed reaction; (c) means for introducing a hydrocarbon liquid feed into said conversion zone; (d) an annular-shaped gasification chamber located in the reactor lower end and containing a particulate carrier material for providing a fluidized bed gasification reaction; (e) conduit means for introducing an oxygen containing gas and steam into said lower gasification reaction zone;; (f) a stripping zone located intermediate the upper conversion zone and the lower gasification zone, said stripping zone containing a coarse mixed particulate packing material supported by an apertured annular-shaped grid made of refractory material and located at the upper end of the gasification reaction zone; (g) outer refractory-lining means provided within said annular-shaped lower gasification reaction zone, wherein said refractory lining is adapted to allow for differential thermal expansion between the lining and the vessel metal outer wall; (h) an inner cylindrical-shaped refractory wall which is supported from the outer refractory lining; ; (i) conduit means for circulating a particulate carrier material from the lower gasification zone upwardly to the upper conversion zone, said conduit being refractory-lined and supported from said inner refractory wall and having a control valve located at the lower end of said conduit; (j) means for introducing a transport gas into the lower end of the said conduit; and (k) means for removing the resultant product gases from the upper portion of said reactor vessel.

19. A reactor assembly according to claim 8, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

20. A process according to claim 1, substantially as hereinbefore described with reference to the accompanying drawings.

21. A hydrocarbon liquid or fuel gas produced by a process according to any of claims 1 to 7 and 20.