Plant for the production of synthesis gas

Abstract

A plant for the production of synthesis gas from a hydrocarbon feedstock is described, wherein the plant comprises a heat exchange reformer (HER) including a HER reactor vessel and an autothermal reformer (ATR) including an ATR reactor vessel, wherein the HER and ATR reactor vessels are coupled in series, the plant including: (i) infeed piping for feeding a mixture of the hydrocarbon feedstock and steam to the HER; (ii) primary reformed gas piping for feeding the primary reformed synthesis gas stream from the HER to the ATR; and (iii) secondary reformed gas piping for feeding the secondary reformed synthesis gas steam from the ATR to the HER, the ATR reactor vessel having an outlet nozzle for the secondary reformed synthesis gas stream at one side of the ATR and the HER reactor vessel having an inlet nozzle for the secondary reformed synthesis gas stream at a side of the HER reactor vessel, wherein the inlet nozzle is disposed opposite the outlet nozzle of the ATR reactor vessel, and the secondary reformed gas piping comprises a minimal length straight pipe for conveying the secondary reformed synthesis gas streams directly from the outlet nozzle of the ATR reactor vessel to the inlet nozzle of the HER reactor vessel.

Description

[0001] P102387

[0002] 1

[0003] PLANT FOR THE PRODUCTION OF SYNTHESIS GAS

[0004] TECHNICAL FIELD

[0005] The present invention relates to a plant for the production of synthesis gas.

[0006] BACKGROUND TO INVENTION

[0007] 5

[0008] Synthesis gas is typically generated using a fired steam reformer which reforms a mixture of a hydrocarbon feedstock, such as natural gas or naphtha, and steam by passing it through a plurality of catalyst filled reformer tubes heated directly by the combustion of a fuel gas. In such plants, natural gas is often used for fuel purposes and the combustion of the fuel generates considerable carbon dioxide emissions.

[0009] Alternatively, synthesis gas may be generated by autothermal reforming in which a hot partially combusted hydrocarbon feed mixture gas containing steam is passed through a bed of steam reforming catalyst.

[0010] 15

[0011] One known method of improving energy efficiency in steam reforming is to combine an autothermal reformer (ATR) with a heat exchange reformer (HER) wherein the HER is installed either in series or in parallel with the ATR. 0 In both cases, natural gas is pre-heated and reformed in the HER in a first stage and then passed to the ATR. In the ATR the partially reformed synthesis gas is combusted in the presence of an oxygencontaining gas, raising the temperature of the synthesis gas in the process. The effluent from the ATR is used as a source of heat for the endothermic reforming reaction taking place in the HER. 5 The HER and ATR are conventionally coupled using extended curved pipework to cater for thermal expansion and contraction. This is further complicated where the ATR comprises a cooling water jacket. The extended pipework creates additional engineering difficulties and adds capital cost to the plant.

[0012] It is an object of the present invention to provide a plant and process wherein an ATR and a HER are coupled in a manner which results in an increase in plant efficiency and lower capital costs.

[0013] SUMMARY OF THE INVENTION

[0014] According to a first aspect of the invention, there is provided a plant for the production of synthesis gas 5 from a hydrocarbon feedstock, wherein the plant comprises a heat exchange reformer (HER) including a P102387

[0015] 2

[0016] HER reactor vessel and an autothermal reformer (ATR) including an ATR reactor vessel, wherein the HER and ATR reactor vessels are coupled in series, the plant including:

[0017] (i) infeed piping for feeding a mixture of the hydrocarbon feedstock and steam to the HER where the hydrocarbon feedstock is subjected to steam reforming in a plurality of catalyst-containing tubes in

[0018] 5 indirect heat exchange with a hot effluent synthesis gas from the ATR to form a primary reformed synthesis gas stream;

[0019] (ii) primary reformed gas piping for feeding the primary reformed synthesis gas stream from the HER to the ATR where the primary reformed synthesis gas is autothermally reformed to form a secondary reformed synthesis gas stream; and

[0020] (iii) secondary reformed gas piping for feeding the secondary reformed synthesis gas steam from the ATR to the HER, the ATR reactor vessel having an outlet nozzle for the secondary reformed synthesis gas stream at one side of the ATR and the HER reactor vessel having an inlet nozzle for the secondary reformed synthesis gas stream at a side of the HER reactor vessel, wherein the inlet nozzle is disposed opposite the outlet

[0021] 15 nozzle of the ATR reactor vessel and the secondary reformed gas piping comprises a minimal length straight pipe for conveying the secondary reformed synthesis gas stream directly from the outlet nozzle of the ATR reactor vessel to the inlet nozzle of the HER reactor vessel.

[0022] In the present invention the secondary reformed synthesis gas streams is conveyed by means of a 0 straight, minimal length, section of pipework, from the outlet nozzle of the ATR reactor vessel to the inlet nozzle of the HER reactor vessel. The primary reformed gas piping therefore does not comprise the loops or curves previously required. The primary reformed gas piping minimal length is preferably provided by having the outlet nozzle of the ATR reactor vessel and the inlet nozzle of the HER reactor vessel opposite each other and at about the same level, i.e. where the piping connecting them is 5 horizontal. Accordingly, in preferred arrangements the primary reformed gas piping consists of a straight, horizontal pipe connecting the outlet nozzle of the ATR reactor vessel and the inlet nozzle of the HER reactor vessel.

[0023] The minimal length straight pipework is suitably accommodated by arranging that the HER and ATR are able to move relative to each other to cater for thermal expansion and contraction of the plant.

[0024] The plant therefore preferably further includes a base support structure for mounting a bottom end of the HER reactor vessel to a substrate, the base support structure including a support arrangement permitting displacement of the HER reactor vessel relative to the ATR reactor vessel in order to accommodate 5 thermal expansion of the primary reformed gas piping extending between the ATR and the HER reactor vessel. P102387

[0025] 3

[0026] The support arrangement may comprise a plurality of circumferentially-spaced support lugs which extend radially outwardly from the HER reactor vessel near a lower end region thereof, and complementary abutment members which are mounted to the base support structure, on which the lugs rest in an arrangement providing for sliding support of the HER reactor vessel thereon.

[0027] 5

[0028] Upper sides of the abutment members may include bearing elements on which the lugs rest.

[0029] The ATR reactor vessel may be fixedly attached to the substrate, while the base support structure provides for support of the HER reactor vessel in an arrangement wherein the HER reactor vessel is supported in a spaced arrangement above the substrate. The HER may be supported on wheels or rollers.

[0030] The plant may include a top guide support system disposed near an upper region of the HER reactor vessel providing for guided support of the HER reactor vessel during displacement of the HER reactor

[0031] 15 vessel relative to the ATR reactor vessel.

[0032] The top guide support system may comprise a guide support structure and an annular guide collar which surrounds the HER reactor vessel near an upper end region thereof, the guide structure being fixedly secured to the ground, with an inner side of the guide collar defining an abutment surface providing to 0 abutment with the reactor vessel, the guide collar providing for sufficient clearance between the collar and the reactor vessel to accommodate movement of the HER reactor vessel due to thermal expansion of the pipes extending between the ATR and the HER reactor vessel.

[0033] The HER may be further characterized by the absence of a cooling jacket surrounding a shell of the HER 5 reactor vessel.

[0034] In another embodiment of the invention, the plant may include two HERs each coupled in series to an ATR in an in-line arrangement wherein the ATR is disposed between the HERs. The plant may include infeed piping for feeding a stream of the hydrocarbon feedstock to the HERs, wherein the infeed piping is configured to provide for dividing the mixture of hydrocarbon feedstock and steam between the HERs where the mixture of hydrocarbon feedstock and steam is subjected to steam reforming in a plurality of catalyst-containing tubes in indirect heat exchange with a hot effluent synthesis gas from the ATR to form a primary reformed synthesis gas stream. In this arrangement one or preferably both HERs have support arrangements permitting displacement of the HER reactor vessels relative to the ATR reactor vessel in 5 order to accommodate thermal expansion of the primary reformed gas piping extending between the ATR and the HER reactor vessels. P102387

[0035] 4

[0036] In accordance with a second aspect of the invention, there is provided a process for the production of synthesis gas from a hydrocarbon feedstock, the process including:

[0037] (a) providing a plant for the production of synthesis gas from a hydrocarbon feedstock, wherein the plant includes a heat exchange reformer (HER) including a HER reactor vessel comprising a

[0038] 5 plurality of catalyst-containing tubes and an autothermal reformer (ATR) including an ATR reactor vessel comprising a burner and a bed of steam reforming catalyst, wherein the HER and ATR reactor vessels are coupled in series,

[0039] (b) steam reforming a mixture of the hydrocarbon feedstock and steam in the HER in an endothermic primary reforming stage in indirect heat exchange with a hot effluent synthesis gas recovered from the ATR to form a primary reformed synthesis gas stream;

[0040] (c) feeding the primary reformed synthesis gas stream from the HER to the ATR together with an oxygen-containing stream;

[0041] (d) autothermally reforming the primary reformed synthesis gas stream in the ATR by partially combusting it with the oxygen-containing stream in the burner and passing the partially combusted

[0042] 15 stream through the bed of steam reforming catalyst to form a secondary reformed synthesis gas stream;

[0043] (e) feeding secondary reformed synthesis gas stream as the hot effluent synthesis gas to the HER thereby providing heat for facilitating said indirect heat exchange in the HER; and

[0044] (f) withdrawing a partially cooled secondary reformed synthesis gas after said indirect heat exchange 0 from the HER, wherein the plant includes:

[0045] (i) infeed piping for feeding the mixture of the hydrocarbon feedstock and steam to the plurality of catalyst-containing tubes in the HER;

[0046] (ii) primary reformed gas piping for feeding the primary reformed synthesis gas stream from the 5 HER to the ATR; and

[0047] (iii) secondary reformed gas piping for feeding the secondary reformed synthesis gas steam from the ATR to the HER, the ATR reactor vessel having an outlet nozzle for the secondary reformed synthesis gas stream at one side of the ATR and the HER reactor vessel having an inlet nozzle for the secondary reformed synthesis gas stream at a side of the HER reactor vessel, wherein the inlet nozzle is disposed opposite the outlet nozzle of the ATR reactor vessel, the secondary reformed gas piping comprising a minimal length straight pipe for conveying the secondary reformed synthesis gas streams directly from the outlet nozzle of the ATR reactor vessel to the inlet nozzle of the HER reactor vessel. 5 In another embodiment of the invention, the process may include;

[0048] (a) providing a plant comprising two heat exchange reformers (HERs) each coupled in series to a single autothermal reformer (ATR), wherein the HERs and the ATR are configured in an in-line arrangement, and wherein the ATR is disposed between the HERs; P102387

[0049] 5

[0050] (b) steam reforming the hydrocarbon feedstock in each of the HERs in endothermic primary reforming stages wherein a mixture of the hydrocarbon feedstock and steam is divided and fed to each of the HERs where the mixture of hydrocarbon feedstock and steam is steam reformed in catalyst-containing tubes in indirect heat exchange with a hot effluent synthesis gas recovered

[0051] 5 from the ATR to form a primary reformed synthesis gas stream;

[0052] (c) feeding the primary reformed synthesis gas stream from each of the HERs to the ATR together with an oxygen stream;

[0053] (d) autothermally reforming the primary reformed synthesis gas streams in the ATR by partially combusting them with the oxygen stream and passing the partially combusted stream through a bed of steam reforming catalyst to form a secondary reformed synthesis gas stream;

[0054] (e) dividing the secondary reformed synthesis gas stream into two portions and feeding each portion as the not effluent synthesis gas to the HERs thereby providing heat for facilitating said indirect heat exchange in the HERs; and

[0055] (f) withdrawing a partially cooled secondary reformed synthesis gas after said indirect heat exchange

[0056] 15 from each of the HERs.

[0057] In the process of the invention the hydrocarbon feedstock may be any gaseous or low boiling hydrocarbon feedstock such as natural gas, associated gas, LPG, petroleum distillate or naphtha. It is preferably methane, associated gas or natural gas containing a substantial proportion, e.g. over 85% v / v 0 methane. Natural gas is an especially preferred feedstock. The feedstock is typically compressed to a pressure in the range 10-100 bar abs.

[0058] If the hydrocarbon feedstock contains sulphur compounds, before or after compression, the feedstock is preferably subjected to desulphurisation, e.g. hydrodesulphurisation using Co or Ni catalysts and 5 absorption of hydrogen sulphide using a suitable absorbent, e.g. a zinc oxide bed. To facilitate this and / or reduce the risk of carbon laydown in the reforming process, hydrogen is preferably added to the hydrocarbon feedstock. The amount of hydrogen in the resulting mixed gas stream may be in the range 1-20% vol, but is preferably in the range 1-10%, more preferably in the range 1-5%. In a preferred embodiment a portion of the hydrogen-rich stream is mixed with the hydrocarbon feed stream. The hydrogen stream may be combined with the hydrocarbon upstream and / or downstream of any hydrodesulphurisation stage.

[0059] In steam reforming, the hydrocarbon feedstock is mixed with steam: this steam introduction may be effected by direct injection of steam and / or by saturation of the feedstock by contact of the latter with a 5 stream of heated water in a saturator. One or more saturators may be used. If desired, a portion of the hydrocarbon stream may bypass the steam addition, e.g. the saturator. The amount of steam introduced may be such as to give a steam to carbon ratio of 1 to 3, preferably 1 to 2, i.e. 1 to 2 moles of steam per P102387

[0060] 6 gram atom of hydrocarbon carbon in the feedstock. The amount of steam is preferably minimised as this leads to a lower cost, more efficient process.

[0061] The hydrocarbon / steam mixture is then desirably pre-heated prior to reforming. This may be achieved by

[0062] 5 the use of a feed-effluent heat exchanger, with the mixture being heated by the partially cooled reformed gas mixture. Desirably, the mixed stream is heated to 400-500°C.

[0063] The resultant feedstock / steam mixture is then subjected to reforming in a reforming unit in two stages in series, which may be termed primary steam reforming and secondary or autothermal reforming. The first stage or primary reforming is effected using a HER also termed a gas-heated reformer (GHR). In a preferred type of heat exchange reformer, the catalyst is disposed in tubes extending between a pair of tube sheets through a heat exchange zone. Reactants are fed to a zone above the upper tube sheet and pass through the tubes and into a zone beneath the lower tube sheet. The heating medium is passed through the zone between the two tube sheets. Heat exchange reformers of this type are described in

[0064] 15 GB1578270, WO97 / 05947 and US2009 / 0123348.

[0065] The compressed, heated feedstock / steam mixture is passed through the catalyst-filled tubes in the HER. During passage through the reforming catalyst, the endothermic reforming reaction takes place with the heat required for the reaction being supplied from the second stage or secondary reformed gas flowing 0 past the exterior surface of the tubes. The primary reforming catalyst used in the HER is usually nickel supported on a refractory support such as rings or multi-holed pellets of calcium aluminate cement, alumina, titania, zirconia and the like. Alternatively, a combination of a nickel and precious metal catalyst may be used. For example, a portion of the nickel catalyst may be replaced with a precious metal catalyst, such as a ruthenium-based catalyst. Alternatively, or additionally, a structured steam reforming 5 catalyst in which a wash coat of steam reforming catalyst on a structured, e.g. monolithic, ceramic or metal support may be used.

[0066] The temperature of the secondary reformed gas is preferably sufficient that the gas undergoing primary reforming leaves the primary reformer at a temperature in the range 650-850°C, preferably 720-780°C.

[0067] The primary reformed gas produced by the HER, which comprises methane, hydrogen, steam and carbon oxides, is fed, preferably without any dilution or heat exchange, to an ATR or secondary reformer in which it is subjected to the second stage or secondary reforming. 5 The ATR generally comprises a burner disposed near the top of the reformer to which is fed the primary reformed gas and an oxygen-containing gas, a combustion zone beneath the burner through which, typically, a flame extends, above a fixed bed of particulate steam reforming catalyst. In autothermal or secondary reforming, the heat for the endothermic steam reforming reactions is provided by combustion P102387

[0068] 7 of hydrocarbon and hydrogen in the feed gas. The primary reformed gas is typically fed to the top of the ATR and the oxygen-containing gas fed to the burner, mixing and combustion occur downstream of the burner generating a heated gas mixture which is brought to equilibrium as it passes through the steam reforming catalyst. Whereas some steam may be added to the oxygen containing gas, preferably no

[0069] 5 steam is added so that the low overall steam ratio for the reforming process is achieved. The secondary reforming catalyst is usually nickel supported on a refractory support such as rings or pellets of calcium aluminate cement, alumina, titania, zirconia and the like. In a preferred embodiment, the secondary reforming catalyst comprises a layer of a higher activity Ni and / or Rh on zirconia catalyst over a conventional Ni on alumina catalyst to reduce catalyst support volatilisation.

[0070] The oxygen-containing gas preferably comprises >95% vol. 02, which may be provided by an air separation unit (ASU) or from another oxygen source.

[0071] The amount of oxygen-containing gas required in the ATR is determined by two main considerations, viz.

[0072] 15 the desired composition of the product gas, and the heat balance of the heat exchange reformer. In general, increasing the amount of oxygen, thereby increasing the temperature of the reformed gas leaving the secondary reformer, causes the [H2] I [CO] ratio to decrease and the proportion of carbon dioxide to decrease. Alternatively, if the conditions are arranged such that the product composition and temperature is kept constant, increasing the temperature at which the feedstock is fed to the HER 0 decreases the amount of oxygen required (at a constant oxygen feed temperature).

[0073] The amount of oxygen-containing gas added is preferably such that 40 to 60 moles of oxygen are added per 100 gram atoms of hydrocarbon in the feed to the primary reforming stage. Preferably the amount of oxygen added is such that the secondary reformed gas leaves the ATR at a temperature in the range 5 800-1050°C.

[0074] The secondary reformed gas is then used to provide the heat required for the primary reforming step by using the secondary reformed gas as the hot gas flowing past the tubes of the HER. During this heat exchange the secondary reformed gas cools by transferring heat to the gas undergoing primary reforming. Preferably, the secondary reformed gas cools by several hundred degrees centigrade but of course it will leave the HER at a temperature somewhat above the temperature at which the feedstock / steam mixture is fed to the catalyst-filled tubes in the HER.

[0075] After leaving the HER, the secondary reformed gas is then further cooled in one or more steps of heat 5 exchange. Heat recovered during this cooling may be employed for reactants pre-heating and / or for heating water used to provide the steam employed in the primary reforming step. In a preferred embodiment, the secondary reformed gas mixture exiting the shell side of the HER is used to preheat the feedstock / steam mixture fed to the tubes in the HER. P102387

[0076] 8

[0077] The cooling is performed to lower the temperature of the synthesis gas from the ATR or secondary reformer to below the dew point such that steam present in the synthesis gas condenses. The liquid process condensate may be separated from the synthesis gas by conventional gas-liquid separation equipment.

[0078] 5

[0079] The synthesis gas comprises hydrogen, carbon monoxide, carbon dioxide, and small amounts of unreacted methane, argon and nitrogen. The composition of the synthesis gas may be 10-20 mol% carbon monoxide, 0.5-15 mol% carbon dioxide, 55-85% hydrogen and the balance one or more inert gases, including methane.

[0080] BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Further features of the invention are described hereinafter by way of a non-limiting example of the invention, with reference to and as illustrated in the accompanying diagrammatic drawings. In the

[0082] 15 drawings:

[0083] Figure 1 shows a diagrammatic representation of a prior art arrangement of a HER coupled in series to an ATR; 0 Figure 2 shows a schematic perspective view of the prior art arrangement of the HER coupled to the ATR of Figure 1 , as seen from one side;

[0084] Figure 3 shows a perspective view of the prior art arrangement of the HER coupled to the ATR of Figure 1 , as seen from an opposite side; 5

[0085] Figure 4 shows a top plan view of the prior art arrangement of the HER coupled to the ATR of Figure 1 ;

[0086] Figure 5 shows a diagrammatic representation of plant of the production of synthesis gas from a hydrocarbon feedstock, in accordance with the invention;

[0087] Figure 6 shows a schematic side view of the plant of Figure 5;

[0088] Figure 6A shows an enlarged fragmentary sectional view, as seen along section line A-A of Figure 6; 5 Figure 6B shows an enlarged fragmentary sectional view, as seen along section line B-B of Figure 6;

[0089] Figure 7 shows a schematic opposite side view of the plant of Figure 5; P102387

[0090] 9

[0091] Figure 8 shows a schematic perspective view of the plant of Figure 6;

[0092] Figure 9 shows a schematic perspective view of the plant of Figure 8, as seen from an opposite side of the plant, with the top guide support system and the sliding support arrangement removed for the sake of

[0093] 5 clarity;

[0094] Figure 10 shows a schematic top plan view of the plant of Figure 9;

[0095] Figure 11 shows a diagrammatic representation of another embodiment of a plant of the production of synthesis gas from a hydrocarbon feedstock, in accordance with the invention;

[0096] Figure 12 shows a schematic side view of the plant of Figure 11 ;

[0097] Figure 13 shows a schematic opposite side view of the plant of Figure 11 ; and

[0098] 15

[0099] Figure 14 shows a schematic top plan view of the plant of Figure 11.

[0100] DETAILED DESCRIPTION OF THE DRAWINGS 0 With reference to Figures 1 to 4, a prior art arrangement of a single HER coupled in series to a single ATR, is designated generally by the reference numeral 10. In this arrangement, the HER and ATR are fixed to the ground in a conventional manner such that they are unable to move relative to each other. Referring to the diagrammatic representation of Figure 1 , a natural gas stream 12 is optionally mixed with a carbon-rich stream 14 and steam from line 16 and the resulting mixture fed via line 18 to a plurality of 5 externally-heated, catalyst-filled tubes 20 of a HER 22. Whereas only three tubes are depicted, it will be appreciated that the number of tubes may vary considerably and as such, there may be tens or hundreds of tubes. The hydrocarbons, carbon dioxide and steam react over the catalyst to form a primary reformed gas mixture comprising hydrogen, carbon dioxide, carbon monoxide, steam and unreacted methane. The primary reformed gas mixture is fed from the HER 22 via line 24 to an ATR 26 fed with an oxygen stream 28 in the ATR. The primary reformed gas mixture is partially combusted with the oxygen in a burner mounted near the top of the ATR and the resulting hot, partially-combusted gas brought to equilibrium through a bed of steam reforming catalyst 30 deposed beneath the burner. The resulting secondary reformed synthesis gas stream is fed from the ATR 26 via line 32 to the shell side of the HER 22 where it heats the catalyst-filled tubes 20 and is thereby partially cooled. 5

[0101] The partially cooled synthesis gas is fed from the HER 22 via line 36 to a heat recovery unit 38 comprising one or more heat exchangers, where it is further cooled to below the dew point to condense steam. Process condensate is removed from the cooled gas mixture using gas-liquid separation P102387

[0102] 10 equipment in the heat recovery unit to produce a de-watered synthesis gas. The de-watered synthesis gas is recovered from the heat recovery unit via line 40.

[0103] With reference to Figures 2 to 4, it can be seen that the HER 22 includes an atmospheric boiling water¬

[0104] 5 cooling jacket enclosing the shell 44 of the HER. The jacket cools the shell thereby protecting the shell from overheating which may be caused by internal damage to the refractory lining of the shell. It will be appreciated that the water-cooling jacket comprises a relatively large, heavy structure enclosing the shell of the HER 22.

[0105] The HER 22 and the ATR 26 are fixedly supported using vertical skirt-type supports located between the underside of the vessel bottom heads and the ground. The vessel supports are bolted to civil foundations.

[0106] As both HER and ATR vessels are fixed to the ground, any pipework routed between the vessels vessels must be sufficiently flexible in order to accommodate thermal expansion of pipes and expansion of the

[0107] 15 vessel shells, to the extent that loads on the respective nozzles connecting the pipes to the HER and the ATR are not over stressed. As the piping is refractory lined, the piping is inherently stiff. As can be seen in Figures 2 to 4, the pipe routings for the primary reformed gas 24 and secondary reformed gas 32 are relatively long and include complex expansion loops in order to accommodate thermal expansion. 0 With reference to Figures 5 to 10, plant comprising a HER-ATR arrangement, in accordance with the invention, is designated generally by the reference numeral 50. The plant 50 comprises a HER 52 including a reactor vessel 53 and an ATR 54 including a reactor vessel 55, wherein the HER and ATR reactor vessels are coupled in series in an in-line arrangement. In this arrangement the HER and ATR are able to move relative to each other, 5

[0108] Referring to Figure 5, a feed gas stream 56 is optionally mixed with a carbon-rich stream 58 and steam from line 60 and the resulting mixture is divided and fed via line 62 to extern ally- heated, catalyst-filled tubes 64 of the HER 52. The hydrocarbons, carbon dioxide and steam react over the catalyst to form a primary reformed gas mixture comprising hydrogen, carbon dioxide, carbon monoxide, steam and unreacted methane. The primary reformed gas mixture is fed from the HER 52 via line 66 directly to the ATR 54 which is fed with an oxygen stream 68. In the ATR 54, the primary reformed gas mixture is partially combusted with the oxygen in a burner mounted near the top of the ATR vessel 55 and the resulting hot, partially-combusted gas is brought to equilibrium through a bed of steam reforming catalyst 70 disposed beneath the burner. 5

[0109] The resulting secondary reformed synthesis gas stream is fed from the ATR 54 via line 72 directly and via a minimum length of straight pipe to the shell side of the HER reactor vessel 53 of the HER 52 where the gas stream heats the catalyst-filled tubes 64 via indirect heat exchange and is thereby partially cooled. P102387

[0110] 11

[0111] The partially cooled synthesis gas is fed from the HER 52 via line 74 to a heat recovery unit 76 comprising one or more heat exchangers where it is further cooled to below dew point to condense stream. Process condensate is removed from the cooled gas mixture using gas-liquid separation equipment in the heat recovery unit to produce a de-watered synthesis gas. The de-watered synthesis

[0112] 5 gas is recovered from the heat recovery unit via line 78.

[0113] Schematic views of the plant 50 are shown in Figures 6 to 10. The HER reactor vessel and the ATR reactor vessel 55 are each coupled in series in an in-line arrangement. The hot reformed gas from the ATR 54 is used to heat the HER 52. The ATR 54 is scaled to be fed with the flow of reformed gas from the HER. As is explained above, the partially cooled synthesis gas recovered from the heat exchange reformers is then cooled in the heat recovery unit 76.

[0114] The plant 50 includes infeed piping 80 for feeding the stream 62 of the hydrocarbon feedstock to the HER 52, the infeed piping 80 being configured to feed the hydrocarbon feedstock stream to the HER where the

[0115] 15 hydrocarbon feedstock is subjected to steam reforming in indirect heat exchange with a hot effluent synthesis gas from the ATR to form a primary reformed synthesis gas stream. Pipe 81 is provided at the top of the ATR 54 for feeding the oxygen stream 68 to the ATR.

[0116] The plant 50 includes refractory-lined primary reformed gas piping 82 for feeding the primary reformed 0 synthesis gas stream from the HER 52 to the ATR 54 via stream line 66, where the primary reformed synthesis gas is auto-thermally reformed to form a secondary reformed synthesis gas stream.

[0117] The plant 50 includes a short straight refractory-lined secondary reformed gas pipe 84 for feeding the secondary reformed synthesis gas steams 72 from the ATR 54 to the HER 52. More specifically, the ATR 5 reactor vessel 55 has an outlet nozzle 86 for the secondary reformed synthesis gas stream at one side of the ATR reactor vessel and the HER reactor vessel 53 has an inlet nozzle 88 for the secondary reformed synthesis gas stream at a side of the HER reactor vessel wherein the inlet nozzle is disposed opposite the outlet nozzle of the ATR reactor vessel, the primary reformed gas pipe 84 being connected to the nozzles for conveying the secondary reformed synthesis gas streams directly from the outlet nozzle 86 of the ATR reactor vessel to the inlet nozzle 88 of the HER reactor vessel. The pipe 84 comprises a minimal length straight pipe for conveying the secondary reformed synthesis gas streams 72 from the outlet nozzle 86 of the ATR reactor vessel 55 to the inlet nozzle 88 of the HER reactor vessel 53. In these embodiments, the HER reactor vessel 53 is characterized by the absence of a cooling jacket 85 (shown schematically in Figures 6, 6B and 7 by broken lines 85) which typically surrounds the reactor vessels of 5 conventional HERs as described hereinabove. The absence of a cooling jacket has greatly simplified the design of the HER of the plant 50, and also significantly reduced the weight of the HER when compared to conventional prior art HERs having cooling jackets. Overheating of the HER 52 is preferably managed P102387

[0118] 12 by using infrared monitoring and cessation of heating of the HER in response to an overheating condition being detected.

[0119] The ATR reactor vessel 55 is fixedly attached to the ground 92. More specifically, the ATR reactor vessel

[0120] 5 is supported using vertical skirt-type supports 90 located between the underside of vessel bottom heads and the ground 92. The vessel supports are bolted to civil foundations in the ground 92.

[0121] With specific reference to Figures 6, 6A and 6B, the plant includes a base support structure 94 for the HER for mounting a bottom end of each of the HERs to the ground 92 in an arrangement wherein the reactor vessel 53 is spaced above the ground. The plant further includes a sliding support arrangement 96 permitting sliding displacement of the HERs relative to the ATR in order to accommodate thermal expansion of the pipes 84 extending between the ATR 54 and the HERs 52.

[0122] The sliding support arrangement 96 comprises a number of circumferentially-spaced support lugs 98

[0123] 15 which extend radially outwardly from the outer shell of the HER reactor vessel 53 near a lower end region thereof, and a number of complementary abutment members 100 which are mounted to the base support structure 94, on which the lugs rest in an arrangement providing for sliding support of the lugs and thereby the reactor vessel, thereon. More specifically, the abutment members 100 include bearing elements on which the lugs are supported. Yet more specifically, the bearing elements are in form of ball 0 bearings.

[0124] The plant includes a top guide support system 102 for the HER, providing for guided support of an upper end region of the HER 52, particularly so as to accommodate movement of the HER relative to the ATR. The top guide support system 102 comprises a guide support structure 104 and an annular guide collar 5 106 which surrounds the reactor vessel 53 near an upper end region thereof. The guide structure 104 is fixedly secured (directly or indirectly) to the ground 92. An inner side of the guide collar 106 defines an abutment surface providing for abutment with the outer shell of the HER reactor vessel 53, the collar being configured so as to provide for sufficient clearance between the collar and the shell of the reactor vessel in order to accommodate movement of the HER due to thermal expansion of the pipes 84 extending between the ATR reactor vessel 55 and the HER reactor vessel 53.

[0125] The sliding support arrangement 96 of the HER reactor vessel 53, permitting sliding displacement of the HER relative to the ATR, is facilitated by the absence of a cooling jacket. The sliding support arrangement 96 which accommodates thermal expansion and contraction of the piping extending between the HER 5 and the ATR, allows for less complicated pipework and as a result, lower fabrication and capital costs associated with piping. Simplifying of the piping compared to the piping of prior art conventional plant as exemplified hereinabove, also reduces stresses in the piping and reduces the size and cost of nozzle P102387

[0126] 13 reinforcing structures compared to the size and cost of nozzle reinforcing structures required for prior art conventional HER-ATR arrangements.

[0127] With reference to Figures 6 and 7, the pipes 82 and 84 and the lower sliding support arrangement 96 and

[0128] 5 the top guide support system 102 for the HER, work together as a support system. This system manages the thermal expansion of the ATR-HER arrangement in accordance with the invention, and the pipes along with the resultant pipe stress, to allow for a simplified pipe routing.

[0129] The arrangement provides a more simplified pipe work arrangement comprised of the pipes 82 and 84, where the pipe 84 is a minimum length straight pipe compared to a complex expansion loop of a prior art conventional HER-ATR arrangement as depicted in Figure 3 by the piping 32. This arrangement, simplifies the engineering design and saves space, meaning that the footprint of the plant is beneficially reduced.

[0130] 15 It will also be appreciated that the HER reactor vessel is supported close to the elevation of the nozzles 86 and 88. This leads to reduced vertical (axial) thermal expansion of the nozzle locations and therefore exerts less stress on the connecting pipe 84. This makes nozzle 88 and 86 more closely aligned throughout any vertical thermal expansion allowing the use of a cheaper simpler straight pipe. 0 The horizontal thermal expansion managed by the expansion loop of prior art conventional HER-ATR arrangements (an example of a prior art expansion loop being designated by reference numeral 32 in Figure 3) is allowed to occur and the HER sliding support arrangement 96 enables the HER to slide sideways with the thermal expansion force. 5 With reference to Figures 11 to 14, another embodiment of plant in accordance with the invention is depicted is designated by the reference numeral 150. The plant 150 comprises a HER-ATR arrangement comprising two identical HER’s 52 which are each coupled in series to a single ATR 54 in an in-line arrangement wherein the ATR 54 is disposed between the HERs. The HERs 52 are identical in size and configuration and located equi-distant from the centrally-disposed ATR 54. In Figures 11 to 14, features of the plant 150 which are the same as and / or similar to features of the plant 50 are designated by the same and / or similar reference numerals.

[0131] Referring to Figure 11 , a feed gas stream 56 is optionally mixed with a carbon-rich stream 58 and steam from line 60 and the resulting mixture is divided and fed via line 62 to extern ally- heated, catalyst-filled 5 tubes 64 of the HERs 52. The hydrocarbons, carbon dioxide and steam react over the catalyst to form a primary reformed gas mixture comprising hydrogen, carbon dioxide, carbon monoxide, steam and unreacted methane. The primary reformed gas mixture is fed from each of the HERs 52 via lines 66 directly to the ATR 54 which is fed with an oxygen stream 68. In the ATR 54, the primary reformed gas P102387

[0132] 14 mixture is partially combusted with the oxygen in a burner mounted near the top of the ATR and the resulting hot, partially-combusted gas is brought to equilibrium through a bed of steam reforming catalyst 70 disposed beneath the burner.

[0133] 5 The resulting secondary reformed synthesis gas stream is fed from the ATR 54 via lines 72 directly to the shell sides of each of reactor vessels 53 of the HERs 52 where the gas stream heats the catalyst-filled tubes 64 via indirect heat exchange and is thereby partially cooled.

[0134] The partially cooled synthesis gas is fed from the HERs 52 via lines 74 to a heat recovery unit 76 comprising one or more heat exchangers where it is further cooled to below dew point to condense stream. Process condensate is removed from the cooled gas mixture using gas-liquid separation equipment in the heat recovery unit to produce a de-watered synthesis gas. The de-watered synthesis gas is recovered from the heat recovery unit via line 78. The invention extends to the process described herein with reference to Figure 11 .

[0135] 15

[0136] Schematic views of the plant 150 are shown in Figures 12 to 14. The two HERs 52 are each coupled in series to the ATR 54 in an in-line arrangement wherein the HERs are arranged diametrically opposite each other around the ATR 54. 0 The hot reformed gas from the ATR 54 is divided and used to heat both of the HERs 52. The ATR 54 is scaled to be fed with the flow of reformed gas from the HERs. As is explained above, the partially cooled synthesis gas recovered from each of the heat exchange reformers is combined and cooled in the heat recovery unit 76. 5 The plant 150 includes infeed piping 80 for feeding the stream 62 of the hydrocarbon feedstock to the HERs 52, the infeed piping 80 being configured to provide for dividing the hydrocarbon feedstock stream between the HERs where the hydrocarbon feedstock is subjected to steam reforming in indirect heat exchange with a hot effluent synthesis gas from the ATR to form a primary reformed synthesis gas stream. Pipe 81 is provided at the top of the ATR 54 for feeding the oxygen stream 68 to the ATR.

[0137] The plant 150 includes refractory lined piping 82 for feeding the primary reformed synthesis gas stream from each of the HERs to the ATR via stream lines 66, where the primary reformed synthesis gas is auto- thermally reformed to form a secondary reformed synthesis gas stream. 5 Each HER 52 of the plant 150, includes the top guide support system 102 and the lower sliding support arrangement 96 as described hereinabove, for supporting the reactor vessel 53. P102387

[0138] 15

[0139] It will be appreciated that the absence of a cooling jacket on the HER / HERs of the plant 50 and 150, reduces the operating weight considerably and reduces the amount of connecting piping to the HER. The sliding supports are sensitive to the weight applied to them and have limits for load capacity. By reducing the overall operating weight, the HER is able to more easily slide in response to thermal expansion

[0140] 5 forces. The reduction in the amount of piping connected to the HER also allows the HER to slide unobstructed, without other piping clashing with the support or piping arrangement.

[0141] The top guide support system 102 provides effective support for the HER, resisting overturning moments generated by the operation of the HER-ATR arrangement, wind or seismic forces acting on the HER 10 reactor vessel while still allowing the HER reactor vessel to expand vertically (axially) within the support collar but constrained against rotation.

Claims

P10238716CLAIMS:

1. Plant for the production of synthesis gas from a hydrocarbon feedstock, wherein the plant comprises a heat exchange reformer (HER) including a HER reactor vessel and an autothermal reformer (ATR) including an ATR reactor vessel, wherein the HER and ATR reactor vessels are coupled in series, the plant including:(i) infeed piping for feeding a mixture of the hydrocarbon feedstock and steam to the HER where the hydrocarbon feedstock is subjected to steam reforming in a plurality of catalyst-containing tubes in indirect heat exchange with a hot effluent synthesis gas from the ATR to form a primary reformed synthesis gas stream;(ii) primary reformed gas piping for feeding the primary reformed synthesis gas stream from the HER to the ATR where the primary reformed synthesis gas is autothermally reformed to form a secondary reformed synthesis gas stream; and(iii) secondary reformed gas piping for feeding the secondary reformed synthesis gas steam from the ATR to the HER, the ATR reactor vessel having an outlet nozzle for the secondary reformed synthesis gas stream at one side of the ATR and the HER reactor vessel having an inlet nozzle for the secondary reformed synthesis gas stream at a side of the HER reactor vessel, wherein the inlet nozzle is disposed opposite the outlet nozzle of the ATR reactor vessel, and the secondary reformed gas piping comprises a minimal length straight pipe for conveying the secondary reformed synthesis gas streams directly from the outlet nozzle of the ATR reactor vessel to the inlet nozzle of the HER reactor vessel.

2. Plant as claimed in claim 1 , comprising a base support structure for mounting a bottom end of the HER reactor vessel to a substrate, the base support structure including a support arrangement permitting displacement of the HER reactor vessel relative to the ATR reactor vessel in order to accommodate thermal expansion of the primary reformed gas piping extending between the ATR and the HER reactor vessels.

3. Plant as claimed in claim 2, wherein the support arrangement comprises a plurality of circumferentially-spaced support lugs which extend radially outwardly from the HER reactor vessel near a lower end region thereof, and a number of complementary abutment members which are mounted to the base support structure, on which the lugs rest in an arrangement providing for sliding support of the HER reactor vessel thereon.

4. Plant as claimed in claim 3, wherein upper sides of the abutment members include bearing elements on which the lugs rest.P102387175. Plant as claimed in any one of claims 2 to 4, wherein the ATR reactor vessel is fixedly attached to the substrate, while the base support structure provides for support of the HER reactor vessel in an arrangement wherein the HER reactor vessel is supported in a space arrangement above the substrate.

6. Plant as claimed in any one of claims 2 to 5, which includes a top guide support system disposed near an upper region of the HER reactor vessel providing for guided support of the HER reactor vessel during displacement of the HER reactor vessel relative to the ATR reactor vessel.

7. Plant as claimed in claim 6, wherein the top guide support system comprises a guide support structure and an annular guide collar which surrounds the HER reactor vessel near an upper end region thereof, the guide structure being fixedly secured to the ground, with an inner side of the guide collar defining an abutment surface providing to abutment with the reactor vessel, the guide collar providing for sufficient clearance between the collar and the reactor vessel to accommodate movement of the HER reactor vessel due to thermal expansion of the pipes extending between the ATR and the HER reactor vessels.

8. Plant as claimed in any one of claims 1 to 7, wherein the HER is characterized by the absence of a cooling jacket surrounding a shell of the HER reactor vessel.

9. Plant as claimed in any one of claims 1 to 8, wherein the plant includes two HERs each coupled in series to an ATR in an in-line arrangement wherein the ATR is disposed between the HERs.

10. Plant as claimed in claim 9, wherein the plant includes include infeed piping for feeding a stream of the hydrocarbon feedstock to the HERs, wherein the infeed piping is configured to provide for dividing the hydrocarbon feedstock stream between the HERs where the hydrocarbon feedstock is subjected to steam reforming in indirect heat exchange with a hot effluent synthesis gas from the ATR to form a primary reformed synthesis gas stream.

11. A process for the production of synthesis gas from a hydrocarbon feedstock, the process including the steps of:(a) providing a plant for the production of synthesis gas from a hydrocarbon feedstock, wherein the plant includes a heat exchange reformer (HER) including a HER reactor vessel comprising a plurality of catalyst-containing tubes and an autothermal reformer (ATR) including an ATR reactor vessel comprising a burner and a bed of steam reforming catalyst, wherein the HER and ATR reactor vessels are coupled in series,(b) steam reforming a mixture of the hydrocarbon feedstock and steam in the HER in an endothermic primary reforming stage in indirect heat exchange with a hot effluent synthesis gas recovered from the ATR to form a primary reformed synthesis gas stream;P10238718(c) feeding the primary reformed synthesis gas stream from the HER to the ATR together with an oxygen-containing stream;(d) autothermally reforming the primary reformed synthesis gas stream in the ATR by partially combusting it with the oxygen-containing stream in the burner and passing the partially combusted stream through the bed of steam reforming catalyst to form a secondary reformed synthesis gas stream;(e) feeding secondary reformed synthesis gas stream as the hot effluent synthesis gas to the HER thereby providing heat for facilitating said indirect heat exchange in the HER; and(f) withdrawing a partially cooled secondary reformed synthesis gas after said indirect heat exchange from the HER, wherein the plant includes:(i) infeed piping for feeding the mixture of the hydrocarbon feedstock and steam to the plurality of catalyst-containing tubes in the HER;(ii) primary reformed gas piping for feeding the primary reformed synthesis gas stream from the HER to the ATR; and(iii) secondary reformed gas piping for feeding the secondary reformed synthesis gas steam from the ATR to the HER, the ATR reactor vessel having an outlet nozzle for the secondary reformed synthesis gas stream at one side of the ATR and the HER reactor vessel having an inlet nozzle for the secondary reformed synthesis gas stream at a side of the HER reactor vessel, wherein the inlet nozzle is disposed opposite the outlet nozzle of the ATR reactor vessel, the secondary reformed gas piping comprising a minimal length straight pipe for conveying the secondary reformed synthesis gas streams directly from the outlet nozzle of the ATR reactor vessel to the inlet nozzle of the HER reactor vessel.

12. A process according to claim 11 .comprising(a) providing a plant comprising two heat exchange reformers (HERs) each coupled in series to a single autothermal reformer (ATR), wherein the HERs and the ATR are configured in an in-line arrangement, and wherein the ATR is disposed between the HERs;(b) steam reforming the hydrocarbon feedstock in each of the HERs in endothermic primary reforming stages wherein a mixture of the hydrocarbon feedstock and steam is divided and fed to each of the HERs where the mixture of hydrocarbon feedstock and steam is steam reformed in catalyst-containing tubes in indirect heat exchange with a hot effluent synthesis gas recovered from the ATR to form a primary reformed synthesis gas stream;(c) feeding the primary reformed synthesis gas stream from each of the HERs to the ATR together with an oxygen stream;(d) autothermally reforming the primary reformed synthesis gas streams in the ATR by partially combusting them with the oxygen stream and passing the partially combusted stream through a bed of steam reforming catalyst to form a secondary reformed synthesis gas stream;P10238719(e) dividing the secondary reformed synthesis gas stream into two portions and feeding each portion as the not effluent synthesis gas to the HERs thereby providing heat for facilitating said indirect heat exchange in the HERs; and(f) withdrawing a partially cooled secondary reformed synthesis gas after said indirect heat exchange from each of the HERs.

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