Process and apparatus for the production of synthesis gas

Abstract

Reactive diluent fluid (22) is introduced into a stream of synthesis gas (or syngas) produced in a heat-generating unit such as a partial oxidation (POX) reactor (12) to cool the syngas and form a mixture of cooled syngas and reactive diluent fluid. Carbon dioxide and/or carbon components and/or hydrogen in the mixture of cooled syngas and reactive diluent fluid is reacted (26) with at least a portion of the reactive diluent fluid in the mixture to produce carbon monoxide-enriched and/or solid carbon depleted syngas which is fed into a secondary reformer unit (30) such as an enhanced heat transfer reformer in a heat exchange reformer process. An advantage of the invention is that problems with the mechanical integrity of the secondary unit arising from the high temperature of the syngas from the heat-generating unit are avoided.

Claims

1. Apparatus for the production of syngas, comprising: a first reactor configured to exothermically react hydrocarbon-containing fuel with an oxidant gas including molecular oxygen to produce an exothermically-generated syngas product; a first conduit configured to remove an effluent stream of the exothermically-generated syngas product from the first reactor; a combining element configured to combine reactive diluent fluid with the effluent stream to produce a reactive mixture; a second reactor configured to react components of the mixture to produce a reacted syngas product; a second conduit configured to feed a stream of reacted syngas product from the second reactor to a heat exchange reformer; and the heat exchange reformer configured to endothermically reform hydrocarbon-containing fuel gas with steam over a catalyst to produce a heat exchange-reformed syngas product, wherein the heat exchange reformer uses heat generated in the first reactor to drive at least a portion of the reforming.

2. The apparatus of claim 1, the first reactor at least one of a partial oxidation (PDX) reactor, an autothermal reformer (ATR), or a catalytic partial oxidation (CPO) reactor.

3. The apparatus of claim 1, the reactive mixture including carbon dioxide and molecular hydrogen, the second reactor including a reverse water gas shift reaction zone configured to react, over a catalyst, at least a portion of the carbon dioxide and at least portion of the molecular hydrogen in the mixture to produce a carbon monoxide-enriched syngas product.

4. The apparatus of claim 1, the reactive mixture including solid carbon particles, the second reactor including a gasification reaction zone configured to react at least a portion of the solid carbon particles with at least one other component in the mixture to gasify at least a portion of the solid carbon particles.

5. The apparatus of claim 1, the heat exchange reformer comprising a shell and tube style reformer including tubes and a shell side, the tubes configured to endothermically reform hydrocarbon-containing fuel gas with steam over a catalyst, the shell side introduces the reacted syngas product to heat the tubes for the endothermic reforming.

6. The apparatus of claim 1, the reformer comprising an enhanced heat transfer reformer (EHTR).

7. The apparatus of claim 1, the combining element comprising a first combining element, further comprising a second combining element configured to combine a second diluent fluid with a syngas stream after combining the reactive diluent and the exothermically-generated syngas product and prior to recovering heat from the reacted syngas product.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a flowsheet describing one embodiment of the process of the present invention;

(2) FIG. 2 is a flowsheet describing a hydrocarbon conversion process in which the process of FIG. 1 is integrated with a downstream generic syngas conversion process to produce hydrocarbon liquid fuels or other liquid products; and

(3) FIG. 3 is a flowsheet describing another embodiment of the process of the present invention.

(4) Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION

(5) According to one aspect of the present invention, there is provided a process for the production of syngas comprising carbon monoxide and molecular hydrogen, said process comprising:

(6) exothermically reacting hydrocarbon-containing fuel an oxidant gas comprising molecular oxygen in a first reactor to produce an exothermically-generated syngas product;

(7) combining a stream of reactive diluent fluid with a stream of said exothermically-generated syngas product to produce a reactive mixture;

(8) reacting said reactive mixture in a second reactor to produce a reacted syngas product; and

(9) endothermically reforming hydrocarbon-containing fuel gas with steam over a catalyst in a heat exchange reformer to produce a heat exchange-reformed syngas product, wherein at least a portion of the heat required in the generation of said heat exchange-reformed syngas product is obtained by recovering heat from said reacted syngas product thereby cooling said reacted syngas.

(10) The reactive diluent fluid includes any diluent fluid that is capable of cooling syngas by direct heat exchange and comprising at least one component that may react with at least one component of the synthesis gas. The reactive mixture comprises cooled exothermically generated syngas product and reactive diluent fluid. The reacted syngas product includes the product syngas that has undergone a further reaction either to produce further carbon monoxide or to remove solid carbon particles, e.g. soot, produced as a by-product of the oxidation reaction in the primary heat-generating unit. Thus, the present may be used for soot control purposes.

(11) The hydrocarbon fuel may be a solid or liquid fuel but it is preferably a gas. Natural gas is the preferred fuel. Pure molecular oxygen is preferred as the oxidant gas over an oxidant gas comprising molecular oxygen such as air. Water may be present in the reaction to produce exothermnically-generated syngas product (for example, if an ATR process is used). If water is present, it may be used in liquid form in which case it will vaporise immediately upon entry into the first reactor. However, the use of steam is preferred.

(12) An advantage of this invention is that the temperature of the exothermnically-generated syngas product is reduced and may be controlled as required for downstream processing. The downstream mechanical integrity problems that may result from the high levels of heat generated in the primary heat-generating unit may be avoided and process operability may be improved by controlling the reduced temperature of the exothermically-generated syngas product.

(13) Another advantage of this invention that any solid carbon present in the exothermically-generated syngas product can be at least partially gasified mitigating fouling, erosion or plugging of downstream heat exchangers such as HERs, boilers or preheaters.

(14) Where the reactive mixture comprises carbon dioxide, at least a portion of the carbon dioxide may be reacted together with at least a portion of the molecular hydrogen in said mixture over a catalyst in a reverse water gas shift reaction zone to produce a carbon monoxide-enriched syngas product.

(15) Where the reactive mixture comprises solid carbon particles, at least a portion of the particles may be gasified by reaction with at least one other component of the mixture in a gasification zone to produce a solid carbon-depleted syngas product. The gasification reaction preferably occurs on the surface of a gasification reaction support structure and may be catalysed.

(16) The process further comprises endothermically reforming hydrocarbon-containing fuel gas with steam over a catalyst in a heat exchange reformer to produce a heat exchange-reformed syngas product. At least a portion of the heat required in the generation of said heat exchange-reformed syngas product is obtained by recovering heat from said reacted syngas product thereby cooling the reacted syngas product. Use of this heat in this way provides further overall cooling of the syngas. The heat exchange-reformed syngas product may be combined with the reacted syngas product prior to heat recovery.

(17) When the reactive diluent fluid is a gas, the exothermically-generated syngas product is first cooled via sensible heat exchange. When the reactive diluent fluid is a liquid, initial cooling occurs via vaporisation and sensible heat exchange. The reactive diluent fluid may be recovered and recycled from downstream processing of syngas. The reactive diluent fluid may promote the gasification of any solid carbon particles or soot present in the reactive mixture. The reactive diluent fluid may be imported from an external source.

(18) The reactive diluent fluid preferably comprises carbon dioxide. An advantage of using carbon dioxide as the diluent is that it may be readily converted to more useful carbon monoxide via a reverse water-gas shift reaction (see reaction (III)), resulting in more carbon monoxide being available for downstream processing. In addition, if the carbon dioxide has been recycled from downstream processes, the potential emission level of this greenhouse gas is reduced.

(19) The reactive diluent fluid may comprise carbon dioxide separated, e.g. by acid gas recovery and recycled from downstream syngas or recovered and recycled from downstream processing of syngas. Alternately, the residual gas from a GTL reactor comprising carbon dioxide can be recycled without processing in an AGR unit. The reactive diluent may comprise the products of a combustion process which would contain a significant quantity of carbon dioxide. The combustion products may be selected from the group consisting of combustion furnace flue gases and gas turbine exhaust gas. The reactive diluent fluid may comprise carbon dioxide imported from an external source. For certain applications, the reactive diluent fluid may comprise carbon dioxide and methane either alone or together with other hydrocarbon(s) such as ethane, propane, butane, pentane, hexane and/or their isomers. In a typical F-T based GTL process, the diluent may be a residual effluent of the reactor after separation of synfuel and water. In this case, it would comprise of carbon dioxide, unreacted carbon monoxide and molecular hydrogen, low molecular weight paraffins, olefins and oxygenates. The recycling of these gases increases their utilization and increases the overall GTL process efficiency.

(20) The reactive diluent fluid may comprise molecular hydrogen. The injection of hydrogen into the first syngas product pushes the position of the equilibrium in reaction (III) in a reverse water gas shift reaction towards the carbon monoxide product side. This effect is advantageous because it promotes the conversion of carbon dioxide to carbon monoxide.

(21) The use of carbon dioxide or molecular hydrogen as diluent is advantageous as both gases are capable of promoting the gasification of carbon components in the mixture of cooled exothermically-generated syngas product and reactive diluent fluid.

(22) The reactive diluent fluid may comprise water. The water may be in the form of liquid water or steam or may comprise a combination of liquid water and steam. The injection of water is primarily to promote the gasification of carbon components in the mixture of cooled exothermically-generated syngas product and reactive diluent fluid.

(23) The reacted syngas product from the reformer or a syngas mixture derived therefrom is preferably used in a downstream conversion process to produce conversion products selected from the group consisting of hydrocarbon liquid fuels, methanol, DME and oxo-alcohols.

(24) In another embodiment of the present invention, a second diluent fluid is combined with the syngas stream between the point at which the reactive diluent fluid is combined with the exothermically-generated syngas product and the point at which heat is recovered from the reacted syngas product to adjust the temperature and/or change the composition of the relevant gas stream.

(25) The second diluent fluid may change the composition of the gas stream entering the shellside of a heat exchange reformer such that performance of the heat exchange reformer is enhanced. In another arrangement, the second diluent fluid may adjust the temperature of the gas stream entering the shellside of the heat exchange reformer such that the heat exchange reformer operates in a more desired temperature range. Composition change and/or temperature adjustment are achieved through physical/thermal mixing or/and reactions between the said reacted syngas product and the second diluent fluid.

(26) The second diluent fluid may be combined with the reactive mixture in any section of the second reactor or may be combined with the reacted syngas product at any point between the second reactor and the heat exchange reformer. Where the heat exchange reformer is a shell and tube style reformer in which the endothermic reforming reaction occurs within the tubes and the reacted syngas product is introduced to the shell-side, the second diluent fluid is introduced in any section of the shell-side of the heat exchange reformer.

(27) The second diluent fluid may be inert or reactive. The fluid may be selected from the group consisting of water vapor, steam, liquid water, molecular hydrogen, carbon dioxide, methane (and other light (e.g. C2 to C6) hydrocarbons), offgas from downstream processes, and other substances (previously identified) that could enhance the performance of the heat exchange reformer and could adjust its operating temperature.

(28) Water and/or steam may be combined as the second diluent with the reacted syngas product to reduce the amount of metal dusting inside the heat exchange reformer and/or to adjust the temperature of the reacted syngas product. Such injection of water and/or steam increases the water concentration of the gas stream to the shellside of a heat exchange reformer. This increase in the water concentration reduces the severity of metal dusting conditions inside the heat exchange reformer. Water and/or steam can also adjust the temperature of the gas stream to the shellside of a heat exchange reformer to meet requirements of the reformer operation. The temperature, amount, and form of the water or steam (i.e. gaseous or liquid) can be selected to fit the needs of the heat exchange reformer.

(29) Molecular hydrogen may be combined as the second diluent fluid with the reacted syngas product to enhance the heat exchange efficiency inside a heat exchange reformer. A recycle molecular hydrogen stream can be established as the second diluent. Due to the much greater heat conductivity of molecular hydrogen compared to other gases, the resulting hydrogen-rich environment can enhance the heat exchange efficiency inside a heat exchange reformer, thereby reducing the size and capital cost of the reformer.

(30) The selection of the point at which the second diluent is introduced depends on the specific needs of a process. The injection can be made into any section of the second reactor comprising the shift reaction zone and/or the gasification zone, any section of the shellside of a heat exchange reformer, and between the second reactor and the heat exchange reformer. In the arrangement where steam is introduced to mitigate metal dusting inside a heat exchange reactor and adjust the temperature of the gas stream to the reformer, the injection point may be between the exit of the second reactor and the entrance to the shellside of the heat exchange reformer. Alternatively, if the objective of steam injection is only for mitigating metal dusting, steam can be introduced into the section of the heat exchange reformer where metal dusting may occur, namely the section where temperature drops below the carbon precipitation temperature.

(31) The selection of injection point impacts on the performance and cost of a process. By way of comparison, introducing steam to the effluent of the primary reformer or to the tube side of the heat exchange reformer can also reduce metal dusting severity and/or adjust temperature. However, these two introduction points result in additional carbon dioxide in the syngas product due to water gas shift reaction in either the second reactor or inside the tubes of the heat exchange reformer. Increased carbon dioxide concentration results in higher carbon dioxide separation cost and/or negative impact on downstream processes. The injection of steam between the second reactor and the heat exchange reformer, as proposed by the above mentioned arrangement, does not produce additional carbon dioxide.

(32) In a second aspect of the present invention, there is provided a process for the production of syngas comprising carbon monoxide and molecular hydrogen, said process comprising:

(33) exothermically reacting hydrocarbon-containing fuel with an oxidant gas comprising molecular oxygen in a first reactor to produce an exothermically-generated syngas product;

(34) cooling an effluent stream of said exothermically-generated syngas product by combining reactive diluent fluid with said stream to produce a mixture comprising cooled exothermically-generated syngas product and reactive diluent fluid, said mixture further comprising at least one component selected from the group consisting of carbon dioxide and solid carbon particles; said process further comprising:

(35) reacting together carbon dioxide in said mixture with molecular hydrogen in said mixture over a catalyst in a second reactor to produce a reacted syngas product that is enriched in carbon monoxide; and/or

(36) gasifying solid carbon particles in said mixture with at least one other component in said mixture in a second reactor to produce a reacted syngas product that is depleted in solid carbon.

(37) The step of the process to produce solid carbon-depleted syngas can be carried out instead of the step to produce carbon monoxide-enriched syngas and vice versa. Alternatively, the two steps can be carried out either sequentially or simultaneously. Preferably, the reacted syngas product is both enriched in carbon monoxide and depleted in solid carbon.

(38) This process may also comprise endothermically reforming hydrocarbon-containing fuel gas with steam over a catalyst in a heat exchange reformer to produce a heat exchange reformed syngas product wherein at least a portion of the heat generated in the exothermic reaction producing said exothermically generated syngas product is used to drive the endothermic reforming reaction.

(39) In a third aspect of the present invention, there is provided apparatus for the production of syngas comprising carbon monoxide and molecular hydrogen according the process of the first aspect, said apparatus comprising:

(40) a first reactor in which hydrocarbon-containing fuel is reacted exothermically with an oxidant gas comprising molecular oxygen to produce an exothermically-generated syngas product;

(41) conduit means for removing an effluent stream of said exothermically-generated syngas product from the first reactor;

(42) means for combining a stream of reactive diluent fluid with said effluent stream to produce a reactive mixture;

(43) a second reactor in which said reactive mixture reacts to produce a reacted syngas product;

(44) a heat exchange reformer in which hydrocarbon-containing fuel gas is reformed endothermically with steam over a catalyst to produce a heat exchange-reformed syngas product; and

(45) conduit means for feeding a stream of reacted syngas product from the second reactor to the heat exchange reformer, wherein at least a portion of the heat required in the generation of said heat exchange-reformed syngas product is obtained by recovering heat from said reacted syngas product thereby cooling the reacted syngas product.

(46) The first reactor is preferably selected from the group consisting of a POX reactor, an ATR or a CPO reactor.

(47) Where the reactive mixture comprises carbon dioxide, the second reactor preferably has a reverse water gas shift reaction zone in which at least a portion of the carbon dioxide and at least portion of the molecular hydrogen in the reactive mixture are reacted together over a catalyst to produce a carbon monoxide-enriched syngas.

(48) Where the reactive mixture comprises solid carbon particles, the second reactor may have a gasification reaction zone in which at least a portion of the solid carbon particles is gasified by reaction with at least one other component of the reactive mixture to produce a solid carbon-depleted syngas.

(49) The reformer is preferably a shell and tube style reformer in which the endothermic reforming reaction occurs within the tubes and the reacted syngas product is introduced to the shell-side. Most preferably, the reformer is an EHTR.

(50) The apparatus may further comprise means for combining a second diluent fluid with a syngas stream between the point at which the reactive diluent is combined with said exothermically-generated syngas product and the point at which heat is recovered from the reacted syngas product to adjust the temperature and/or change the composition of relevant syngas stream.

(51) In a fourth aspect of the present invention, there is provided apparatus for the production of syngas comprising carbon monoxide and molecular hydrogen according to the process of the second aspect, said apparatus comprising:

(52) a first reactor in which hydrocarbon-containing fuel is reacted exothermically with an oxidant gas comprising molecular oxygen to produce an exothermically-generated syngas product;

(53) a second reactor;

(54) conduit means for feeding an effluent stream of said exothermically generated syngas product from the first reactor to the second reactor;

(55) means for combining reactive diluent gas with said effluent stream to produce a mixture comprising cooled exothermically-generated syngas product and reactive diluent gas, said mixture further comprising at least one component selected from the group consisting of carbon dioxide and solid carbon particles;

(56) said apparatus further comprising:

(57) a reverse water gas shift reaction zone in which carbon dioxide in said mixture is reacted together with molecular hydrogen in said mixture over a catalyst in the second reactor to produce reacted synthesis gas product that is enriched in carbon monoxide; and/or

(58) a gasification reaction zone in which solid carbon particles in said mixture are gasified with at least one other component in said mixture in the second reactor to produce reacted syngas product that is depleted in solid carbon.

(59) The apparatus may further comprise:

(60) a heat exchange reformer in which hydrocarbon-containing fuel gas is reformed endothermically with steam over a catalyst to produce a heat exchange reformed syngas product; and

(61) conduit means for reacted syngas product from the second reactor to the heat exchange reformer, wherein at least a portion of the heat generated in the exothermic reaction producing said exothermically generated syngas product is used to drive the endothermic reforming reaction.

(62) The first reactor is preferably a POX reactor as this reactor produces the highest temperature syngas (when compared with ATR and CPO) and the higher the temperature of the syngas from the primary heat-generating unit, the higher the conversion of carbon dioxide in the reactive diluent and the better the efficiency of downstream HER processing. The POX reactor is preferably used in combination with an EHTR as the heat exchange reformer.

EXAMPLE

(63) Referring to FIG. 1, a stream 2 of natural gas is preheated by indirect heat exchange 8, hydrodesulfurized as required, and divided into a first portion 4 and a second portion 6. The first portion 4 is introduced into a POX reactor 12. A stream 14 of oxygen is pre-heated by indirect heat exchange 16 and the pre-heated oxygen stream 18 is also fed to the POX reactor 12. The natural gas and the oxygen are reacted together in the POX reactor 12 to produce first syngas product. A stream 20 of first syngas product is removed from the POX reactor 12 at a temperature of from 1200 to 1400.degree. C.

(64) A stream 22 comprising carbon dioxide is introduced to and cools the first syngas product stream 20. The cooled stream 24 is fed to a reverse water gas shift reactor 26 in which at least a portion of the carbon dioxide from the cooled stream 24 is reacted with at least a portion of the hydrogen from the cooled stream 24 to produce carbon monoxide and water. The catalytic reaction is endothermic and, thus, a further cooling effect on the syngas is observed. A stream 28 of carbon monoxide-enriched syngas is removed from the reverse water gas shift reactor 26 and introduced to the shell-side of an EHTR 30.

(65) A stream 32 of steam is introduced to the second portion 6 of the natural gas and the combined stream 34 is pre-heated by indirect heat exchange 36. The pre-heated combined stream 38 is introduced to the tube-side of the EHTR 30. The tubes of the EHTR 30 contain conventional steam-methane reforming catalyst and the natural gas and the steam react to form second syngas product. Heat from the shell-side of the EHTR 30 provided at least in part by the carbon monoxide-enriched syngas, is used to drive the endothermic catalytic steam-methane reforming reaction.

(66) The second syngas product leaving the tubes of the EHTR 30 is combined with the first syngas product to form a combined syngas product. A stream 40 of combined syngas product is removed for downstream processing, in particular for the synthesis of hydrocarbon liquid fuels (e.g. by the F-T process), methanol (e.g. by the catalytic hydrogenation of carbon monoxide), oxo-alcohols and DME.

(67) Tables 1 and 2 contains data for the composition of various streams in the process of FIG. 1 calculated in a computer simulation.

(68) TABLE-US-00001 TABLE 1 STREAM ID 2 4 6 18 20 22 STREAM NG FEED NG TO POX NG TO EHTR POX O.sub.2 POX OUT FT OFFGAS Temperature C. (F.) 16 (60) 363 (685) 363 (685) 232 (449) 1343 (2450) 38 (100) Pressure MPa 3.55 (515) 3.41 (494) 3.41 (494) 3.17 (460) 2.84 (412) 4.14 (600) (psia) Mole Flow Kg 8411 (18542) 6564 (14471) 2111 (4653) 4167 (9187) 19693 (43416) 1044 (2301) mol/h (lb mol/hr) Enthalpy 658.8 (625.0) 391.7 (371.6) 126.0 (119.5) 25.6 (24.3) 367.1 (348.3) 412.0 (390.9) MMKJ/h (MMBtu/hr) STEAM ID 24 28 38 40 STREAM QUENCH CATBED OUT EBTR FEED EHTR OUT Temperature C. (F.) 1243 (2270) 1197 (2186) 510 (950) 590 (1094) Pressure MPa 2.84 (412) 2.84 (412) 3.34 (484) 2.84 (412) (psia) Mole Flow Kg 20737 (45717) 20823 (45908) 6577 (14499) 30953 (68238) mol/h (lb mol/hr) Enthalpy 779.1 (739.2) 779.1 (739.2) 1112.0 (1055.0) 1912.0 (1814.0) MMKJ/h (MMBtu/hr)

(69) TABLE-US-00002 TABLE 2 STREAM ID 2 4 6 18 20 22 Mole Flow Kg mol/h (lb mol/hr) H.sub.2 199.8 (440.4) 64.2 (141.6) 11437.0 (25213.8) C1 7967.2 (17564.4) 6028.8 (13290.9) 1938.5 (4273.5) 90.8 (200.1) C2 265.8 (585.9) 201.1 (443.4) 64.7 (142.6) C3 45.4 (100.1) 34.4 (75.8) 11.1 (24.4) C4 15.2 (33.4) 11.5 (25.3) 3.7 (8.1) C5 5.0 (11.1) 3.8 (8.4) 1.2 (2.7) C6 3.4 (7.4) 2.5 (5.6) 0.8 (1.8) CD (CO.sub.2) 59.7 (131.6) 45.2 (99.6) 14.5 (32.0) 336.4 (741.7) 1043.7 (2300.9) CM (CO) 6232.2 (13739.6) WA (H.sub.2O) 1539.2 (3393.3) O.sub.2 4146.2 (9140.6) AR (Ar) 20.8 (45.9) 20.8 (45.9) N.sub.2 48.8 (107.5) 36.9 (81.4) 11.9 (26.2) 36.9 (81.4) Mole percent H.sub.2 3.00% 3.00% 58.10% C1 94.70% 91.80% 91.80% 0.50% C2+ PRESENT PRESENT PRESENT CD (CO.sub.2) 0.70% 0.70% 0.70% 1.70% 100.00% CM (CO) 31.60% WA (H.sub.2O) 7.80% O.sub.2 99.50% AR (Ar) 0.50% 0.10% N.sub.2 0.60% 0.60% 0.60% 0.20% STREAM ID 24 28 38 40 Mole Flow Kg mol/h (lb mol/hr) H.sub.2 11437.0 (25213.8) 10784.3 (23774.9) 64.2 (141.6) 16429.3 (36219.7) C1 90.8 (200.1) 47.3 (104.3) 1938.5 (4273.5) 397.9 (877.1) C2 64.7 (142.6) C3 11.1 (24.4) C4 3.7 (8.1) C5 1.2 (2.7) C6 0.8 (1.8) CD (CO.sub.2) 1380.1 (3042.5) 597.0 (1316.1) 14.5 (32.0) 970.6 (2139.7) CM (CO) 6232.2 (13739.6) 7058.9 (15561.9) 8476.0 (18686.0) WA (H.sub.2O) 1539.2 (3393.3) 2278.8 (5023.9) 4466.1 (9845.9) 4609.8 (10162.6) O.sub.2 AR (Ar) 20.8 (45.9) 20.8 (45.9) 20.8 (45.9) N.sub.2 36.9 (81.4) 36.9 (81.4) 11.9 (26.2) 48.8 (107.5) Mole percent H.sub.2 55.20% 51.80% 1.00% 53.10% C1 0.40% 0.20% 29.50% 1.30% C2+ PRESENT CD (CO.sub.2) 6.70% 2.90% 0.20% 3.10% CM (CO) 30.10% 33.90% 27.40% WA (H.sub.2O) 7.40% 10.90% 67.90% 14.90% O.sub.2 AR (Ar) 0.10% 0.10% 0.10% N.sub.2 0.20% 0.20% 0.20% 0.20%

(70) Referring now to FIG. 2, a syngas generation system 42 of the type depicted in FIG. 1 is fed by a stream 2 of hydrocarbon fuel gas, a stream 14 of oxygen or air and a stream 32 of steam. A stream 40 of syngas is removed from the syngas generation system 42 and fed to a syngas conversion system 44. The syngas conversion system 44 may use an F-T process to synthesize liquid hydrocarbons or involve the synthesis of methanol, DME or oxo-alcohols. A stream 46 of raw conversion product is removed from the syngas conversion system 44 and upgraded and refined 50 to produce the liquid products 52.

(71) A stream 22 of reactive diluent gas is recycled from the syngas conversion system 44 to the syngas generation system 42. A recycle stream 54 may also be taken from the product upgrading and refining process 50.

(72) Referring now to FIG. 3, a stream 14 of oxygen and a stream 10 of natural gas are fed to a reactor 12 in which syngas is generated exothermically. A stream 20 of exothermically generated syngas product is removed from the reactor 12. A stream 22 of a first reactive diluent is injected into the syngas product stream 20 to form a combined stream 24 which is fed to a second reactor 26 in which either or both of a reverse water gas shift reaction and a gasification reaction take place. A stream 28 of reacted syngas product is removed from the second reactor 26 and is combined with a stream 56 of a second diluent fluid to form a combined stream 58 which is fed to a shell-and-tube style heat exchange reformer 30. The second diluent fluid may adjust the temperature of the reacted syngas product and/or change the composition of the reacted syngas product which, inter alia, helps the reformer 30 to operate more efficiently.

(73) A stream 38 of natural gas is fed to the tube side of reformer 40 where it is reacted endothermically in the presence of steam to produce a second syngas product. Combined stream 58 is fed to the shell side of the reformer and, thus, heat originally from the exothermic generation of syngas is used to drive the endothermic syngas generation reaction. A stream 40 of combined syngas product is removed from the reformer 30 and further processed.

(74) Throughout the specification, the term means in the context of means for carrying out a function is intended to refer to at least one device adapted and/or constructed to carry out that function.

(75) It will be appreciated that the invention is not restricted to the details described above with reference to the preferred embodiments but that numerous modifications and variations can be made without departing from the spirit or scope of the invention as defined in the following claims