WO2016016251A1

WO2016016251A1 - Integrated sct-cpo/sr process for producing synthesis gas

Info

Publication number: WO2016016251A1
Application number: PCT/EP2015/067289
Authority: WO
Inventors: Luca Eugenio Basini
Original assignee: Eni S.P.A.
Priority date: 2014-07-29
Filing date: 2015-07-28
Publication date: 2016-02-04

Abstract

The present invention relates to an integrated process for producing synthesis gas which comprises the following stages: a) dividing a gaseous hydrocarbon stream into a first and a second stream, preferably comprising natural gas and/or refinery gas, b) sending the first stream, after mixing with steam, to a Steam Reforming section and thereby producing a first stream of synthesis gas, c) sending the second stream to a short contact time -catalytic partial oxidation section, after mixing with a stream containing oxygen, steam and optionally CO₂, and a third stream containing liquid and/or gaseous compounds, in which said gaseous compounds are selected from hydrocarbons other than natural gas and/or refinery gas, or among gaseous compounds deriving from bio-masses, and wherein said liquid compounds are selected from hydrocarbons, or compounds of various nature deriving from bio-masses, or mixtures thereof, and thus producing a second stream of synthesis gas.

Description

INTEGRATED SCT-CPO/SR PROCESS FOR PRODUCING SYNTHESIS GAS.

DESCRIPTION

The present invention relates to a process for producing synthesis gas through a process that integrates Short Contact Time - Catalytic Partial Oxidation (SCT-CPO) technology with Steam Reforming (SR) technology.

In the present patent application, all the operating conditions included in the text must be interpreted as preferred conditions even if this is not expressly stated.

For the purpose of the present text the term "comprise" or "include" also comprises the term "consist of or "essentially consisting of".

For the purpose of the present text the definitions of the intervals always include the extremes unless otherwise specified.

Synthesis gas is produced with Steam Reforming (SR) technology and with Non-Catalytic Partial Oxidation (POx) and AutoThermal Reforming (ATR) technology. A relatively recent variation of the SR process is Gas Heated Reforming (GHR) which at least partially replaces the radiant heat needed for endothermic reactions with a convective source: typically the hot gas produced by combustion reactions and/or the same synthesis gas produced by ATR at a high temperature. In some cases ATR and SR or GHR technologies are integrated within processes known as Combined Reforming (CR). The characteristics of the above-mentioned technologies are described in numerous documents in literature, including:

1 ) "Technologies for large-scale gas conversion" Aasberg-Petersen, K., Bak Hansen, J. -H., Christensen, T. S., Dybkjaer, I., Christensen, P. Seier, Stub Nielsen, C, Winter Madsen, S. E. L, Rostrup-Nielsen, J. R., Applied Catalysis A: General, 221 (1 -2), p.379, Nov 2001 ;

2) "Synthesis Gas production by Steam Reforming", Dybkjaer, lb; Seier Christtensen P.; Lucassen Hansen V.; Rostrup-Nielsen J.R., EP1097105A1 ; 3) J.R. Rostrup-Nielsen, J. Sehested and J.K. Noskov, Adv. Catal. 47 (2002), pp. 65- 139;

4) "Catalytic Steam Reforming"; Rostrup-Nielsen J.R.; pg 1 -1 17, Catalysis Vol. 5, Edited by John R. Anderson and Michel Boudart, 5) "Issues in H₂ and synthesis gas technologies for refinery, GTL and small and distributed industrial needs"; Basini, Luca, Catalysis Today, 106 (1-4), p.34, Oct 2005.

Short Contact Time - Catalytic Partial Oxidation (SCT-CPO) technology is also described in numerous documents in literature including: WO 201 1151082, WO 2009065559, WO 201 1072877, US 2009127512, WO 2007045457, WO 2006034868, US 200521 1604, WO 2005023710, DE 10232970, WO 9737929, EP 0725038, EP 0640559 e L.E. Basini e A. Guarinoni, "Short Contact Time Catalytic Partial Oxidation (SCT-CPO) for Synthesis Gas Processes and Olefins Production", Ind. Eng. Chem. Res. 2013, 52, 17023-17037. Synthesis gas is used in a large number of industrial processes including Ammonia and Urea synthesis, production of H₂ for refining and obtaining fuels, synthesis of Methanol and its derivatives and synthesis of liquid hydrocarbons with the Fischer-Tropsch (F-T) process. Synthesis gas is also used in fine chemical processes and in the electronic, metal refining, glass and food industries. These numerous industrial uses require the synthesis gas to be produced with very different compositions from one another so as to minimize recycling and improve overall yields.

Table 1 shows the main reactions involved in the synthesis gas production processes and Table 2 the compositional characteristics of the synthesis gas required for its main uses. Table 1 ΔΗ' 298 Κ

Steam - C0₂ Reforming

CH₄ + H₂0 = CO + 3 H₂ 206 [1 ]

CO + H₂0 = C0₂ + H₂ -41 [2]

CH₄ + C0₂ = 2CO + 2 H₂ 247 [3]

Non-Catalytic Partial Oxidation (POx)

CH₄ + 3/2 0₂ = CO + 2 H₂0 -520 [4]

CO + H₂0 = C0₂ + H₂ -41 [5]

Autothermal Reforming (ATR)

CH₄ + 3/2 0₂ = CO + 2 H₂0 -520 [4]

CH₄ + H₂0 = CO + 3 H₂ 206 [1 ]

CO + H₂0 = C0₂ + H₂ -41 [5]

Catalytic Partial Oxidation (CPO)

CH₄ + ½ 0₂ = CO + H₂ -38 [6]

CO + H₂0

Table 2

EP 2142467 describes a combined process in which a gaseous hydrocarbon mixture reacts with steam in an endothermic adiabatic pre-reformer and the pre-reformed product is split into three streams fed to a Steam Methane Reformer (SMR), to a Gas Heated Reformer (GHR) and to an Autothermal Reformer (ATR) that operate in parallel.

EP 1622827 describes a process for the production of synthesis gas starting from carbonaceous material, preferably comprising a gaseous hydrocarbon feedstock of Natural Gas, refinery gas and more generally gaseous streams containing compounds that have up to 4 carbon atoms, which envisages:

(a) a partial oxidation stage of the carbonaceous material performed in a reactor in which there is a burner in the top part (hence an ATR or POx reactor) thus obtaining a first mixture of hydrogen and carbon monoxide;

(b) a catalytic Steam Reforming stage of the carbonaceous material in a tubular

Convective Steam Reforming Reactor (CSR), in which the tubes contain a catalyst and in which the molar ratio between steam and carbon is less than 1 , to separately produce a second product;

(c) feeding the product obtained in (b) to the head of the partial oxidation reactor to mix it with that obtained in (a);

(d) using the mixture obtained in (d) to provide heat to the CSR.

These conditions lead to the production in the CSR of a stream of synthesis gas at relatively low temperatures and with high residual methane content (between 5 - 30% mole/mole).

EP 1403216 describes a procedure for the production of synthesis gas by catalytic steam reforming in parallel in an AutoThermal Steam Reformer in series. The heat required by the SR steps is, also in this case, provided by the combination of effluents from the different SR and ATR. The final mixture of effluents obtained by adding the synthesis gas produced by the convectively heated SR and ATR processes has a H₂/CO ratio comprised between 1 .8 and 2.3 v/v.

WO 2008017741 describes a process for the production of liquid hydrocarbons starting from biomasses, coal, lignite and crude oil residues that boil at a temperature of over 340°C, said process comprising at least:

one partial oxidation stage of the heavy feedstocks in the presence of oxygen for producing a first synthesis gas, potentially purified, with a H₂/CO ratio less than 1 ; a Steam Reforming stage of the light feedstocks having fewer than 10 atoms of carbon for producing a second synthesis gas, potentially purified, with a H₂/CO ratio greater than 3;

a Fischer-Tropsch (FT) stage for the conversion of the synthesis gas formed from the mixture of at least a part of the first and the second synthesis gas into proportions such that H₂/CO varies between 1.2 and 2.5;

a hydrocracking stage of at least one portion of the hydrocarbons produced with FT that boil over 150°C, wherein the light hydrocarbons produced in FT have fewer than 10 atoms of carbon.

Endothermic adiabatic "pre-reforming" reactors are often inserted upstream of the SR and ATR reactors. These reactors are described in various documents in literature including "T.S. Christensen, Appl. Catal. A: 138(1996)285" and "I. Dybkjaer, Fuel Process. Techn. 42(1995)85". The pre-reformers allow the C2+ hydrocarbons contained in the gaseous hydrocarbon streams to be converted at relatively low temperatures (about 550°C) into CO, H₂ and CH₄ reducing the possibility of parasite reactions taking place forming coal [7- 9] in the subsequent SR or ATR steps. In particular in the endothermic pre-reforming reactors reactions [10 - 1 1] occur together with the Water Gas Shift (WGS) reaction [5]. C_nH_m=nC+m/2H₂ ΔΗ^ο>0 [7] CH₄= C + 2H2 ΔΗ°= 75 kJ/mole [8]

2CO=C + C02 ΔΗ°= -173 kJ/mole [9]

CnH_m+nH₂0=nCO+(n+m/2)H₂ ΔΗ^ο>0 [10]

CO+3H₂=CH₄+H₂0 AH°=-206kJ/mole [11]

CO+H₂0=C0₂+H₂ AH°=-41 kJ/mole [5]

Endothermic adiabatic pre-reforming reactors are typically fed with a mixture of gaseous reagents and steam pre-heated in an oven to about 550°C. In the endothermic adiabatic pre-reforming reactor a Ni based catalyst is used (in most cases) for completing reactions [10] . The pre-reformed gas mixture is then sent to the reforming reactor and has a lower thermodynamic affinity to reactions forming carbonaceous residues through reactions [7- 9]. This allows the steam/carbon (Steam/C v/v) and/or Oxygen/Carbon (0₂/C) ratios fed to the SR or ATR reactors to be reduced, improving the energy efficiency (W.D. Verduijin Ammonia Plant Saf. 33(1993)165). The use of pre-reforming units also allows the flexibility of the SR and ATR technologies to be increased with respect to the composition of the feedstock; for example, it allows feedstock to be used that range from refinery gases to naphtha. Finally, the use of endothermic adiabatic pre-reforming technology can increase the production capacity of plants without requiring significant changes to the characteristics of the reforming unit. As already highlighted, synthesis gas production technologies are used in a large number of industrial procedures to produce different products. It is therefore appropriate to be able to have a flexible synthesis gas production procedure available both with respect to production capacity and with respect to the quality of synthesis gas produced. At the same time it is very important to use high energy efficiency procedures, with low carbon dioxide emissions and that require lower capital costs with respect to traditionally exploited technologies.

For that purpose, the present patent application relates to an integrated process for producing synthesis gas which combines Short Contact Time - Catalytic Partial Oxidation (SCT-CPO) technology with Steam Reforming (SR) technology.

Hence the applicant has developed an integrated process for producing synthesis gas which comprises the following stages:

a) dividing a gaseous hydrocarbon stream into a first and a second stream, preferably comprising natural gas and/or refinery gas,

b) sending the first stream, after mixing with steam, to a Steam Reforming section and thereby producing a first stream of synthesis gas,

c) sending the second stream to a short contact time catalytic partial oxidation section, after mixing with a stream containing oxygen, steam and optionally CO₂, and a third stream containing liquid and/or gaseous compounds, in which said gaseous compounds are selected from hydrocarbons other than natural gas and/or refinery gas, or among gaseous compounds also deriving from bio-masses, and wherein said liquid compounds are selected from hydrocarbons, or compounds of various nature deriving from bio-masses, or mixtures thereof, and thus producing a second stream of synthesis gas.

This configuration therefore exploits the possibilities offered by SCT-CPO technology to use, while maintaining the high energy efficiency typical of catalytic transformations, different types of feedstocks, both liquid and gaseous, which cannot be used in SR technologies and then use them for producing synthesis gas. This process configuration therefore combines an SCT-CPO stage with an SR stage, so as to allow the use of compounds that SR technology cannot transform for producing synthesis gas, and in particular liquid and gaseous hydrocarbons, and compounds deriving from bio-masses also mixed together which could not be used by SR processes or by ATR processes. Although POx technology is also able to treat a very wide feedstock range, its energy consumptions are, in fact, higher since its non-catalytic reactions are less selective and take place at 300°C-600°C higher temperatures than the temperatures envisaged by catalytic technologies and in particular SCT-CPO technology which does not use either a burner or a combustion chamber.

The integrated process according to the present patent application offers the following advantages:

I. Increasing the flexibility of catalytic processes for producing synthesis gas by

allowing the combined use of gaseous hydrocarbons and liquid hydrocarbons and compounds deriving from bio-masses

I. Increasing the compositional flexibility of the synthesis gas produced for optimal integration with the processes that use it, such as the following processes: a) production of NH₃/Urea, b) production of H₂ for refining and other various uses (refining metals, glass, electronics, food industries), c) production of Methanol and its derivatives, d) Fischer Tropsch synthesis for GTL transformations, e) hydroformylation and fine chemistry processes.

III. Improving the overall energy efficiency of production chains and using synthesis gas, hence reducing greenhouse gas emissions and potentially removing and reusing most of the C0₂ produced,

IV. Building plants with large production capacity,

V. Reducing the capital costs of supply chains "via synthesis gas",

VI. debottlenecking the production capacity of already existing plants.

Further objects and advantages of the present invention will appear more clearly from the following description and enclosed figures, provided by way of non-limitative example. Figures 1-9 describe preferred embodiments of the present invention and will be described in detail below. DETAILED DESCRIPTION

The present invention relates to an integrated process for producing synthesis gas which comprises the following stages:

c) sending the second stream to a short contact time catalytic partial oxidation section, after mixing with a stream containing oxygen, steam and optionally C0₂, and a third stream containing liquid and/or gaseous compounds, in which said gaseous compounds are selected from hydrocarbons other than natural gas and/or refinery gas, or among gaseous compounds also deriving from bio-masses, and wherein said liquid compounds are selected from hydrocarbons, or compounds of various nature deriving from bio-masses, or mixtures thereof, and thus producing a second stream of synthesis gas.

The stream containing oxygen may be oxygen, air or enriched air.

In a preferred embodiment of the process a further pre-reforming stage is envisaged upstream either of the SCT-CPO section or the SR section, or both sections.

In a preferred embodiment said pre-reforming stage may be exothermic adiabatic or endothermic adiabatic, and in particular the following combinations are described herein:

Exothermic adiabatic pre-reformer upstream of SR and upstream of SCT-CPO, or Endothermic adiabatic pre-reformer upstream of SR and upstream of SCT-CPO, or Exothermic adiabatic pre-reformer upstream of SR and endothermic adiabatic pre- reformer upstream of SCT-CPO, or

Endothermic adiabatic pre-reformer upstream of SR and exothermic adiabatic pre- reformer upstream of SCT-CPO, or

The first and the second hydrocarbon gaseous stream, preferably selected from natural gas and/or refinery gas, can be fed to either an exothermic adiabatic pre-reformer or to an endothermic adiabatic pre-reformer. This is independent of the fact that these pre- reformers are upstream either of SR or SCT-CPO.

The third stream containing gaseous compounds, wherein said gaseous compounds are selected from different hydrocarbons from natural gas and/or refinery gas, can be fed either to an exothermic adiabatic pre-reformer or to an endothermic adiabatic pre- reformer placed upstream of a SCT-CPO.

The third stream containing liquid compounds wherein said liquid compounds are selected from hydrocarbons, or compounds of various nature deriving from bio-masses, or mixtures thereof, can be fed only to an exothermic adiabatic pre-reformer placed upstream of an ST-CPO.

When the third stream contains both liquid compounds and gaseous compounds, they can be fed only to an exothermic adiabatic pre-reformer placed upstream of an SCT- CPO.

The pre-reforming stage generates a reformed stream that is subsequently fed to the SCT-CPO and/or SR sections.

An exothermic adiabatic pre-reforming reactor exploits the same principles as the SCT- CPO process, as described for example in ITMI20120418.

The pre-reforming sections can be distinguished and positioned each upstream of the SR and SCT-CPO sections.

In fact, the exothermic adiabatic pre-reforming process also allows liquid hydrocarbon and gaseous feedstock to be pre-treated even with high olefin content and/or feedstock obtained from bio-masses that cannot be treated by endothermic adiabatic pre-reforming processes since they would cause:

i) the deactivation of their catalytic systems, and

ii) the formation of carbonaceous residues which would make it impossible to handle industrial reactors.

After the SR and SCT-CPO stages, the first and second stream of synthesis gas produced can be sent separately to a single heat exchange device for cooling to a temperature below 400°C generating co-production of steam; or can be mixed and the resulting mixture is sent to a single heat exchange device for cooling to temperature values below 400°C and for generating steam.

The steam generated can be used partly as a reagent in the SR section and partly fed to the SCT-CPO section.

If the gaseous hydrocarbon stream contains sulfured compounds, it can be subjected to a hydro-desulfurization treatment before being sent to the pre-reforming sections, or before being sent to the Steam Reforming and SCT-CPO sections. If necessary, the impurities that could poison the processes downstream of the synthesis gas production reactors can also be removed after the production of synthesis gas by the SCT-CPO reactor.

Preferably the heat exchange device that cools the synthesis gas in the process according to the present invention is a syngas cooler which comprises:

• at least one vertically oriented tank containing a cooling fluid bath and having a collecting space of the vapor phase generated above said bath of cooling fluid,

• at least one vertical tubular element inserted internally of said tank, open at the ends and coaxial to said tank,

• at least one spiral duct which rotates around the axis of the tank, inserted in said coaxial tubular element,

• at least one outlet for the vapor phase generated on the head of said tank, said exchanger having at the lower part of the vertical tank at least one transfer line for feeding the hot gases to said tank, said transfer line being open at the two ends one of which is connected with the vertical tank and the other free and external to said tank, said transfer line being tubular shaped and projecting laterally outside said exchanger, said transfer line containing at least one central internal duct having an external jacket in which a coolant fluid circulates, said central internal duct being fluidly connected to the spiral duct and extending vertically along the tubular element inserted in the vertical tank.

• a single apparatus having an area immersed in a fluid bath and a free space in the head where a vapor phase accumulates,

• at least a cavity open at both ends placed inside of said apparatus and completely immersed in the fluid bath,

• one or more heat exchange surfaces,

• at least an inlet nozzle for one or more flows of cold matter coming from a cold external source and at least one inlet nozzle for one or more flows of a hot matter from a hot external source,

• at least one outlet nozzle for at least a flow of cooled matter and at least one outlet for at least one flow of matter heated by said heat exchange surfaces,

said device containing in a single apparatus all the heat exchange surfaces and said surfaces being completely immersed in the fluid bath and being fluidly connected to the hot and cold sources external to said system through flows of matter.

If it is decided to convert all or part of the carbon monoxide contained in the synthesis gas and to increase the hydrogen content, after cooling, the synthesis gas streams can be sent separately to Water Gas Shift (WGS) sections in which reaction [2] of Table 1 can take place, or the cooled mixture of synthesis gas can be sent to a single WGS section, hence forming in both cases a gas stream mainly containing H₂, CO and C0₂from which through a separation/purification process an H₂ stream with a high degree of purity can be obtained.

The stream of gas containing H₂, CO and C0₂ can be cooled generating steam which is used in part to feed the sections of SR and SCT-CPO and partly can be exported for other uses.

The synthesis gas produced both by SR and by SCT-CPO can be used in a process for the synthesis of methanol, for the synthesis of ammonia and urea, or for Fischer-Tropsch synthesis, or for producing Hydrogen to be dedicated to refining processes or for other various uses such as, for example, the reduction of ferrous minerals, hydroformylations and different processes in the "fine chemistry", electronics, glass and food industries. Integration between SR and SCT-CPO sections allows operational and economic advantages in the production of synthesis gas and in the processes that use it. In particular said configuration allows both to increase the limits of the production capacity of the many existing plants and to use reagents with different compositions and to obtain synthesis gas mixtures suitable for the different production chains. The adiabatic oxidative "pre-reforming" stages allow to reduce the energy consumptions of the subsequent reaction stages and they increase further the flexibility of the synthesis gas production processes. Furthermore, exothermic pre-reformers also allow to treat complex gaseous hydrocarbon feedstock rich in olefins such as some refinery gases and in general gaseous, liquid feedstocks and oxygenated compounds that an endothermic pre- reformer or an SR would otherwise not be able to process, since they would cause the deactivation of catalytic systems and the formation of carbonaceous deposits.

The integrated process described and claimed also requires less pre-heating of reagents hence preventing using large pre-heating ovens with high associated C0₂ emissions that are difficult to recover; it also offers the possibility to integrate the use of gaseous and/or liquid hydrocarbon feedstocks also mixed together, with compounds deriving from bio- masses increasing the "bio" share in products of different industrial processes such as refining and hydrocarbon fuel production processes.

More in detail Figures 1 - 9 describe some preferred embodiments according to the present invention.

In Figure 1 a liquid stream containing liquid hydrocarbons or compounds deriving from bio-masses, or mixtures thereof (3) is mixed with oxygen, or air, or enriched air (4) and steam (5). A stream containing refinery gas or natural gas, or mixtures thereof (2), is desulfurized in a hydro-desulfurization treatment (6) and subsequently mixed with steam (1 ). Said mixture is separated into two parts and sent partly to an SR, partly mixed with the mixture containing the liquid reagents to be fed to an SCT-CPO reactor. The SR and CPO reactors each produce a synthesis gas that is cooled in two heat exchangers (8,9) generating steam which is sent for feeding (1 , 12) or exported for other uses (13).

Figure 2 reproduces the diagram of Figure 1 in part, with the difference that the synthesis gas streams produced are mixed and cooled in a single heat exchanger (8) generating steam that is sent for feeding the reactors (1 , 12) or exported for other uses (13).

Figure 3 reproduces in part the same diagram as Figure 1. The synthesis gas produced by the SR and by SCT-CPO is cooled (7, 8) generating steam. The two streams of synthesis gas are then mixed and made to react in a water gas shift section (WGS 14). The "shifted" synthesis gas is cooled (15) generating steam.

Figure 4 reproduces in part the diagram of Figure 3 but the streams of synthesis gas produced in S and SCT-CPO are cooled in (7, 8) and sent to two WGS reactors (14, 16). Then the products from WGS are mixed and further cooled in a single exchanger (15) generating steam which in part can be exported (13), and bringing the synthesis gas (9) to the suitable temperature for the subsequent stages in the processes that use it. In Figure 5 a liquid stream containing liquid hydrocarbons or compounds deriving from bio-masses, or mixtures thereof (3), is mixed with oxygen, or air, or enriched air (4) and steam (5). A stream containing refinery gas or natural gas, or mixtures thereof (2), is desulfurized in a hydro-desulfurization treatment (6) and subsequently separated into two parts. One part is mixed with the mixture containing the liquid reagents to be fed to an exothermic pre-reformer reactor (9) positioned upstream of SCT-CPO. The other part is mixed with steam (1 ) and is sent to an endothermic pre-reformer (8), positioned upstream of SR. The SR and SCT-CPO units each produce a synthesis gas that is cooled in two separate waste heat boiler heat exchangers (7,8) generating steam. The steam is in part recirculated for feeding (12,1 ) and in part is steam for external uses (13). The cooled synthesis gas is then joined into a single stream (11 ).

In Figure 6 a stream of refinery gas or natural gas, or mixtures thereof (2) is hydro- desulfurized (6). The stream thus treated is separated into two parts and sent in part to an SR after being mixed with steam (1 ); in part it is mixed with a stream containing oxygen, air or enriched air (4) and to a liquid stream containing liquid hydrocarbons or compounds deriving from bio-masses, or mixtures thereof (3); such a mixture is then fed to an SCT-CPO reactor.

SR and SCT-CPO each produce a synthesis gas that is cooled in two heat exchangers (8,7) which may be waste heat boiler (WHB) type, or a syngas cooler (SGC) as described in this text. Both generate steam which is exported (19) for other purposes. The two streams of synthesis gas appropriately cooled, are sent to a WGS reactor (14) which produces a shifted gas rich in H₂ (20) which is further cooled in the heat exchange device (8). The synthesis gas (9) thus obtained is made available for different uses.

Figure 7 reproduces the diagram of Figure 1 and in addition the synthesis gas (11 ) is compressed (24) and sent to a Methanol synthesis reactor (23). The product obtained is purified in a distillation step (22).

Figure 8 starts from the diagram of Figure 1 and is integrated with a section for producing ammonia. The cooled synthesis gas (1 1 ) is made to react in a WGS section (14). The stream thus obtained is sent to a carbon dioxide removal unit (26) and then to a

Methanation unit (27) for removing the residual CO content before being compressed (28) and sent to an Ammonia synthesis reactor (29). As well as Ammonia (31 ), the process provides CO₂ (30) and the ratios between the flows of both streams can be optimized to be used in a Urea synthesis stage which is not indicated in the process diagram of Figure 8.

Figure 9 starts from the diagram of Figure 1 and is integrated with a Fischer Tropsch section. The synthesis gas obtained (1 1 ) has a compositional ratio in which H₂/CO is about 2 v/v, and is sent to a Fischer - Tropsch synthesis reactor (32) obtaining a product that is subject to a hydro-treatment (33) in the presence of H₂ (34) for maximizing the yield of "middle distillates". A part (24) of the recycling gas (36) of the Fischer - Tropsch process is sent to the SCT-CPO reactor.

Claims

An integrated process for producing synthesis gas which comprises the following stages:

a. dividing a gaseous hydrocarbon stream into a first and a second stream, preferably comprising natural gas and/or refinery gas,

b. sending the first stream, after mixing with steam, to a Steam Reforming

section and thereby producing a first stream of synthesis gas,

c. sending the second stream to a short contact time catalytic partial oxidation section, after mixing with a stream containing oxygen, steam and optionally CO₂, and a third stream containing liquid and/or gaseous compounds, in which said gaseous compounds are selected from hydrocarbons other than natural gas and/or refinery gas, or among gaseous compounds also deriving from bio-masses, and wherein said liquid compounds are selected from hydrocarbons, or compounds of various nature deriving from bio-masses, or mixtures thereof, and thus producing a second stream of synthesis gas.

The process according to claim 1 which further comprises a pre-reforming step upstream or of a section of the short contact time catalytic partial oxidation section, or of the Steam Reforming section, or both the sections.

The process according to claim 2 wherein said pre-reforming step is exothermic adiabatic or endothermic adiabatic.

The process according to claim 2 wherein the first and the second hydrocarbon gaseous stream, preferably selected from natural gas and/or refinery gas, are fed to either an exothermic adiabatic pre-reformer or to an endothermic adiabatic pre- reformer.

The process according to claim 2 wherein the third stream containing gaseous compounds, wherein said gaseous compounds are selected from hydrocarbons different from natural gas and/or refinery gas, or among gaseous compounds also derived from biomasses, is fed either to an exothermic adiabatic pre-reformer or to an endothermic adiabatic pre-reformer.

6. The process according to claim 2 wherein the third stream containing liquid

compounds, selected from hydrocarbons, compounds of various nature deriving from bio-masses, or mixtures thereof, is fed to an exothermic adiabatic pre-reformer placed upstream of a short contact time catalytic partial oxidation section.

7. The process according to claim 2 wherein the third stream containing both liquid compounds and gaseous compounds is fed to an exothermic adiabatic pre-reformer placed upstream of a section of a short contact time catalytic partial oxidation section.

8. The integrated process for the production of synthesis gas according to any one of claims 1 to 7 wherein the first and the second stream of synthesis gas are each sent separately to a single heat exchange device for cooling to a temperature less than 400 °C, generating a co-production of steam, or are mixed and the resulting mixture is sent to a single heat exchange device for cooling to temperatures below 400 °C and for the steam generation.

9. The integrated process according to claim 8 wherein the steam generated is used in part as a reactant in the Steam Reforming section, in part is fed to the Catalytic Partial Oxidation section.

10. The process according to any one of claims 1 to 9 wherein the gaseous

hydrocarbon stream contains sulfur compounds and is subjected to a hydro- desulfurization treatment before being sent to the pre-reforming sections or to Steam Reforming sections and short contact time oxidation catalytic partial section.

1 1. The integrated process according to any one of claims 8 to 10 wherein the heat exchange device that cools the synthesis gas comprises:

i. at least one vertically oriented tank containing a cooling fluid bath and having a collecting space of the vapor phase generated above said bath of cooling fluid,

ii. at least one vertical tubular element inserted internally of said tank, open at the ends and coaxial to said tank,

iii. at least one spiral duct which rotates around the axis of the tank, is inserted in said coaxial tubular element,

iv. at least one outlet for the vapor phase generated on the head of said tank, said heat exchanger having in the lower part of the vertical tank at least one transfer line for supplying hot gases to said tank,

said transfer line being open at the two ends of which is connected with the vertical tank and the other free and external to said tank,

said transfer line being tubular in shape and protruding laterally out from said exchanger,

said transfer line containing at least one central duct interior having an external jacket in which circulates a coolant fluid,

said central conduit being fluidly connected to the internal spiral duct and developing vertically along the tubular element inserted into the vertical tank.

12. The integrated process according to any one of claims 8 to 10 wherein the heat exchange device that cools the synthesis gas comprises:

o a single apparatus having an area immersed in a fluid bath and a free space in the head where a vapor phase accumulates,

o at least a cavity open at both ends placed inside of said apparatus and completely immersed in the fluid bath,

o one or more heat exchange surfaces,

o at least one inlet nozzle for one or more flows of cold matter coming from a cold external source and at least one inlet nozzle for one or more flows of hot matter from a hot external source,

o at least one outlet nozzle for at least a flow of cooled matter and at least one outlet for at least one flow of heated matter by said heat exchange surfaces, said device containing in a single apparatus all the heat exchange surfaces and said surfaces being completely immersed in the fluid bath and being fluidly connected to the hot and cold sources to said external system through flows of matter.

13. The integrated process according to any one of claims 1 to 12 which further

comprises a step in which the synthesis gas produced both by Steam Reforming and by Short Contact Time Catalytic Partial Oxidation is used in a process for the methanol synthesis.

14. The integrated process according to any one of claims 1 to 13 wherein the

synthesis gas produced by both Steam Reforming and Short Contact Time Catalytic Partial Oxidation is used in a process for the Ammonia and Urea synthesis.

15. The integrated process according to any one of claims 1 to 14 in which the

synthesis gas produced by both Steam Reforming and by Short Contact Time Catalytic Partial Oxidation is used in a process for Fischer-Tropsch synthesis.

16. The integrated process according to any one of claims 1 to 15 wherein after cooling the streams of synthesis gas are sent separately to separate Water Gas Shift sections, or the mixture of cooled synthesis gas is sent to a single Water Gas Shift section, thus forming in both cases a gas stream containing primarily H₂, CO and C0₂ from which it is possible with a process of separation / purification to obtain a H₂ stream with a high degree of purity.

17. The integrated process according to any one of claims 1 to 16 wherein the gas stream containing H₂, CO and C0₂ is cooled generating steam that is used in part to feed the Steam Reforming and short time contact Catalytic Partial Oxidation sections.