WO2016016256A1

WO2016016256A1 - Integrated sct-cpo/atr process for the production of synthesis gas

Info

Publication number: WO2016016256A1
Application number: PCT/EP2015/067297
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

This invention relates to an integrated process for the production of synthesis gas comprising the following stages: a) dividing a gaseous hydrocarbon stream, preferably comprising natural gas and/or refinery gas, into a first and a second stream, b) sending the first stream, after mixing with steam and a stream containing oxygen, to an Autothermal Reformer section to form a first stream of synthesis gas, c) sending the second stream to a short contact time partial catalytic oxidation section after mixing it with a stream containing oxygen, steam and optionally CO₂, and a third stream containing liquid and/or gaseous compounds, in which the said gaseous compounds are selected from hydrocarbons other than natural gas and/or refinery gas, or from those gaseous compounds which can also be derived from biomass, and in which the said liquid compounds are selected from hydrocarbons or compounds of various kinds deriving from biomass, or mixtures thereof, thus producing a second stream of synthesis gas.

Description

DESCRIPTION

This invention relates to a process for the production of synthesis gas through a process integrating short contact time Catalytic Partial Oxidation (CPO) technology with

AutoThermal Reforming (ATR) technology.

In this patent application all the operating conditions reported in the text are to be understood to be preferred conditions even if that is not expressly stated.

For the purposes of this description the terms "comprises" or "includes" also comprise the terms "consists of" or "essentially consists of".

For the purposes of this description the definitions of intervals always include the end members unless specified otherwise.

Synthesis gas is produced by Steam Reforming (SR) technology and by Non-catalytic Partial Oxidation (POx) and Autothermal Reforming (ATR) technologies. A relatively recent variant of the SR process is Autothermal Reforming (ATR) which at least partly replaces the radiant heat required for the endothermic reactions with a convective source - typically the hot gas produced by combustion reactions and/or the synthesis gas itself produced by an ATR at high temperature. In some cases the ATR and SR or ATR technologies are integrated into schemes known as Combined Reforming (CR).

The characteristics of the abovementioned technologies are described in numerous documents in the literature, among which we would cite:

1 ) "Technologies for large-scale gas convers/on "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.; pp 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 many documents in the literature among which we would cite:

WO 201 1 151082, WO 2009065559, WO 201 1072877, US 2009127512, WO

2007045457, WO 2006034868, US 200521 1604, WO 2005023710, DE 10232970, WO 9737929, EP 0725038, EP 0640559 and L.E. Basini and 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 many industrial processes, among which we would mention the synthesis of ammonia and urea, the production of H₂ for refining and fuels production, the synthesis of methanol and its derivatives, and the synthesis of liquid hydrocarbons by the Fischer-Tropsch (F-T) process. Synthesis gas is also used in fine chemical processes, and in the electronics, metal refining, glass and food industries. These many industrial uses require the synthesis gas to be produced in very different compositions in order to minimize recycling and improve overall yields.

Table 1 describes the main reactions involved in the processes for the production of synthesis gas and Table 2 shows the compositional characteristics of the synthesis gas required by their main uses. Table 1 ΔΗ°₂98 K

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 = C0₂ + H₂ -41 [5]

Table 2

EP 2142467 describes a combined process in which a gaseous hydrocarbon mixture reacts with steam in an endothermal adiabatic pre-reformer and the product, the pre- reformate, is divided into three streams fed to a Steam Methane Reformer (SMR), a Gas Heated Reformer (GHR) and an Autothermal Reformer (ATR) operating in parallel. EP 1622827 describes a process for the production of synthesis gas from carbon- containing material, preferably comprising natural gas or gaseous hydrocarbon feedstock, refinery gas and more generally gas streams containing compounds having up to 4 carbon atoms, which provides for:

(a) a stage of partial oxidation of the carbon-containing material performed in a reactor in which a burner is present in the upper part (therefore an ATR or POx reactor) thus obtaining a first mixture of hydrogen and carbon monoxide;

(b) a stage of catalytic Steam Reforming of the carbon-containing material in a tubular Convective Steam Reforming (CSR) Reactor, 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 top of a 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 result in producing a stream of synthesis gas in the CSR at relatively low temperatures and with a high residual methane content (between 5-30% mole/mole). EP 1403216 describes a process for the production of synthesis gas in which a series of catalytic steam reforming units are in parallel with an AutoThermal Reforming unit. The heat required by the SR passages is again in this case provided by combustion of the outflows from the various SR and ATR. The final mixture of outflows obtained by adding the synthesis gas produced by the convectively heated SR processes and ATR processes has an H₂/CO ratio of between 1 .8 and 2.3 v/v.

WO 2008017741 describes a process for the production of liquid hydrocarbons from biomass, coal, lignite and petroleum residues boiling at a temperature over 340°C, the said process comprising at least:

a stage of partial oxidation of the heavy feedstocks in the presence of oxygen to produce a first synthesis gas, which may be purified, which has an H₂/CO ratio of less than 1 ;

a stage of Steam Reforming of the light feedstocks having at least 10 carbon atoms for the production of a second synthesis gas, which may be purified, having a H₂/CO ratio of more than 3;

a Fischer-Tropsch (FT) stage to convert the synthesis gas formed by mixing at least part of the first and second synthesis gases in proportions such that H₂/CO lies between 1 .2 and 2.5;

a stage of hydrocracking of at least one portion of the hydrocarbons produced by FT boiling above 150°C in which the light hydrocarbons produced in FT have fewer than 10 carbon atoms.

Adiabatic endothermic "pre-reforming" reactors are often inserted upstream of the SR and ATR reactors. These reactors are described in various documents in the literature, including "T.S. Christensen, Appl. Catal. A: 138(1996)285" e "I. Dybkjaer, Fuel Process. Techn. 42(1995)85". The "pre-reformers" make it possible to convert the C2+ carbons present in the gaseous hydrocarbon streams into CO, H₂ and CH₄ at relatively low temperatures (approximately 550°C), reducing the possibility of the occurrence of other parasitic formation reactions [7-9] in the subsequent passes through SR or ATR. In particular reactions [10-1 1] which accompany the Water Gas Shift (WGS) reaction [5] take place in the endothermic "pre-reforming" reactors.

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]

C_nH_m + nH₂0 = nCO + (n+m/2)H₂ ΔΗ^ο>0 [10]

CO + 3H 2= CH₄ + H₂0 AH°=-206kJ/mole [1 1 ]

CO + H₂0 = C0₂ + H₂ AH°=-41 kJ/mole [5]

The adiabatic endothermic "pre-reforming" reactors are typically fed with a mixture of gaseous reagents and steam preheated in a furnace at approximately 550°C. A catalyst based on Ni is (in most cases) used to complete reactions [10-1 1 ] in the adiabatic endothermic "pre-reforming" reactor. The mixture of pre-reformed gas is then passed to the reforming reactor and has lesser thermodynamic affinity towards the reactions forming carbon-containing residues through reactions [7-9]. This makes it possible to reduce the steam/carbon (Steam/C v/v) and/or Oxygen/Carbon (0₂/C) ratios in the feeds to the SR or ATR reactors, increasing their energy efficiency (W.D. Verduijin Ammonia Plant Saf. 33(1993)165). The use of "pre-reforming" units also makes it possible to increase the flexibilities of SR and ATR technologies in relation to the composition of the feedstock; for example it makes it possible to use feedstocks from refinery gases to naphthas. Finally the use of adiabatic endothermic "pre-reforming" technology can increase the production capacity of plants without requiring significant changes in the characteristics of the reforming unit. As already mentioned, the technologies for the production of synthesis gas are used in many industrial processes to produce different products. It is therefore desirable to be able to have a process for the production of synthesis gas which is flexible with regard to both the composition of the reagent feedstock, production capacity, and the quality of the synthesis gas produced. At the same time it is very important to use processes having high energy efficiency with low carbon dioxide emissions, and that require smaller capital costs with respect to the conventionally used technologies.

With this purpose this patent application provides an integrated process for the production of synthesis gas which combines Short Contact Time Partial Catalytic Oxidation (SCT-CPO) technology with AutoThermal Reforming (ATR) technology.

The Applicant has developed an integrated process for the production of synthesis gas comprising the following stages:

a) dividing a gaseous hydrocarbon stream, preferably comprising natural gas and/or refinery gas, into a first and a second stream, b) sending the first stream, after mixing with steam and a stream containing oxygen, to an AutoThermal Reformer section to form a first stream of synthesis gas, c) sending the second stream to a short contact time partial catalytic oxidation section after mixing it with a stream containing oxygen, steam and optionally C0₂, and a third stream containing liquid and/or gaseous compounds, in which the said gaseous compounds are selected from hydrocarbons other than natural gas and/or refinery gas, or from those gaseous compounds which can also be derived from biomass, and in which the said liquid compounds are selected from hydrocarbons or compounds of various kinds deriving from biomass, or mixtures thereof, thus producing a second stream of synthesis gas.

This configuration therefore makes use of the possibility offered by SCT-CPO technology to use different types of feedstock, both liquid and gaseous, which cannot be used in ATR technologies, maintaining the high energy efficiency characteristics of catalytic conversions and thus using them in the production of synthesis gas. This process configuration therefore utilizes a SCT-CPO stage and a ATR stage in parallel in such a way to allow the use of compounds which ATR technology is incapable of converting for the production of synthesis gas, in particular liquid and gaseous hydrocarbons, and compounds deriving from biomass, also mixed together, which cannot be used in either SR processes or ATR processes.

Although POx technology is capable of dealing with quite a broad range of feedstock, its energy consumption is higher since its non-catalytic reactions are less selective and take place at temperatures of 300°C-600°C higher than the temperatures envisaged for catalytic technologies, and in particular, for SCT-CPO technology which uses neither a burner nor a combustion chamber.

The integrated process to which this patent application relates offers the following advantages:

I. increasing the flexibility of catalytic processes for the production of synthesis gas making it possible to use of gaseous and liquid hydrocarbons and compounds deriving from biomass in combination,

II. increasing the compositional flexibility of the synthesis gas produced for an

optimum integration with the processes using it, such as for example, the processes of: a) production of NH₃/urea, b) production of H₂ for refining and for other various uses (metals refining, glass, electronics, food industries, etc.), c) the production of methanol and its derivatives, d) Fischer-Tropsch synthesis for GTL conversions, and e) hydroformylation and fine chemicals processes.

III. improving the overall energy efficiency of synthesis gas production and use

systems, thus reducing "greenhouse gas" emissions and possibly removing and reusing most of the C0₂ produced,

IV. construction of plants having high production capacity,

V. reducing the capital costs of "via-synthesis gas" systems,

VI. debottlenecking production capacity in existing plants.

Further objects and advantages of this invention will be more apparent from the following non-limiting descriptions and appended figures provided purely by way of example.

Figures 1 -7 describe preferred embodiments of this invention and will be described in detail below.

DETAILED DESCRIPTION

This patent application relates to an integrated process for the production of synthesis gas comprising the following stages:

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

In a preferred embodiment this process provides a further pre-reforming stage upstream of either the SCT-CPO section or the ATR section, or both.

In a preferred embodiment the said pre-reforming stage upstream of the SCT-CPO section may be either exothermic adiabatic or endothermic adiabatic.

In a preferred embodiment the said pre-reforming stage upstream of the ATR section may be either exothermic adiabatic or endothermic adiabatic.

More preferably this invention includes the following combinations:

adiabatic endothermic pre-reformer upstream of the ATR and upstream of the SCT- CPO, or

adiabatic exothermic pre-reformer upstream of the ATR and upstream of the SCT- CPO, or

adiabatic endothermic pre-reformer upstream of the ATR and adiabatic exothermic pre-reformer upstream of the SCT-CPO, or

adiabatic exothermic pre-reformer upstream of the ATR and adiabatic endothermic pre-reformer upstream of the SCT-CPO.

The first hydrocarbon gas stream, preferably selected from natural gas and/or refinery gas, may be fed to either an adiabatic endothermic pre-reformer or an exothermic adiabatic pre-reformer.

The second gaseous hydrocarbon stream, preferably selected from natural gas and/or refinery gas, may be fed to an adiabatic endothermic pre-reformer or an adiabatic exothermic pre-reformer located upstream of a short contact time catalytic partial oxidation section.

The third stream containing gaseous compounds, in which the said gaseous compounds are selected from hydrocarbons other than natural gas and/or refinery gas or from gaseous compounds which can also be obtained from biomass, can preferably be fed to an adiabatic exothermic pre-reformer located upstream of a short contact time catalytic partial oxidation section.

The third stream containing liquid compounds in which the said liquid compounds are selected from hydrocarbons or compounds of various nature deriving from biomass, or mixtures thereof, may be fed to only one adiabatic exothermic pre-reformer located upstream of a short contact time catalytic partial oxidation section.

When the third stream contains both liquid compounds and gaseous compounds these can be fed to only one adiabatic exothermic pre-reformer located upstream of a SCT- CPO.

The pre-reforming stage gives rise to a flow of reformate which is subsequently fed to the SCT-CPO and/or ATR sections.

An adiabatic exothermic pre-reforming reactor benefits from the same principles as the SCT-CPO process as described for example in ITM I20120418.

The pre-reforming sections may be separate and each located upstream of the ATR and SCT-CPO sections.

The adiabatic exothermic pre-reforming process makes it possible to pre-treat even liquid and gaseous hydrocarbon feedstock having a high olefin content and/or feedstock obtained from biomass which cannot be treated by adiabatic endothermic pre-reforming processes because they would bring about:

i) deactivation of their catalytic systems, and

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

After the ATR and SCT-CPO stages the first and second synthesis gas streams can be sent separately to a single heat exchanger device to cool them to a temperature below 400°C giving rise to the co-production of steam, or may be mixed, and the resulting mixture passed to a single heat exchange device for cooling to temperatures below 400°C and for the generation of steam.

Part of the steam generated may be used as a reagent in the ATR section and part may be fed to the SCT-CPO section.

If the first gaseous hydrocarbon stream contains sulfur-containing compounds, it may undergo hydrodesulfurisation treatment before being sent to the endothermic pre- reforming section, or before being sent to the ATR and SCT-CPO sections. If necessary, impurities which might poison processes downstream of the synthesis gas production reactors may also be removed after production of the synthesis gases from the SCT-CPO reactor.

Preferably the heat exchange device which cools the synthesis gas in the process according to this invention is a syngas cooler (SGC) comprising:

• at least one vertically orientated tank containing a bath of cooling fluid and having a space above the said cooling bath for collection of the vapour phase generated, • at least one vertical tubular element inserted within the said tank, which is open at the ends and coaxial with the said tank,

• at least one spiral conduit which rotates about the axis of the tank inserted into the said coaxial tubular element,

• at least one outlet for the vapour phase generated at the top of the said tank, the said exchanger having in the lower part of the vertical tank at least one transfer line for feeding hot gases to the said tank, the said transfer line being open at both ends, one of which is connected to the vertical tank and the other is free and outside the said tank, the said transfer line being of tubular shape and projecting laterally outside the said exchanger, the said transfer line containing at least one internal central conduit having an outer jacket through which cooling fluid circulates, the said internal central conduit being in fluid connection with the spiral conduit and extending vertically along the tubular element inserted into the vertical tank.

Preferably the heat exchange device which cools the synthesis gas in the process according to this invention is a syngas cooler comprising:

• a single device having a zone immersed in a fluid bath and a free head space in which a vapour phase accumulates,

• at least one intermediate layer open at both ends located within the said apparatus and completely immersed in the fluid bath,

• one or more heat exchange surfaces,

• at least one inlet opening for one or more flows of cold material originating from an external cold source and at least one inlet opening for one or more flows of hot material originating from an external hot source,

• at least one outlet opening for at least one flow of cooled material and at least one opening for at least one flow of material heated by the heat exchange surfaces, the said device comprising all the heat exchange surfaces in a single apparatus and the said surfaces being completely immersed in the fluid bath and being in fluid connection with the hot and cold sources external to the said system through flows of material.

If it is decided to convert all or part of the carbon monoxide present in the synthesis gas and increase its hydrogen content, after cooling the synthesis gas streams may be sent separately to separate Water Gas Shift (WGS) sections in which reaction [2] in Table 1 will be performed. Alternatively the cooled synthesis gas mixture may be sent to a single WGS section, thus in both cases forming a stream of gas containing mainly H₂, CO and C0₂ from which it is possible to obtain a stream of H₂ having a high degree of purity by means of a separation/purification process.

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

The synthesis gas produced in the two ATR and SCT-CPO sections may be used for the synthesis of liquid hydrocarbons via Fischer Tropsch.

The synthesis gas produced by either the ATR or the SCT-CPO may be used in a process for the synthesis of methanol.

The integrated production of synthesis gas by means of ATR and SCT-CPO may also be used in many other processes via synthesis gas, such as for example the reduction of ferrous minerals, hydroformylations, and the synthesis of acetic acid.

In some preferred cases the synthesis gas produced from the ATR and the SCT-CPO may also be sent to one or more water gas shift (WGS) reactors and become enriched in hydrogen which can then be separated off and used in various refining or hydrotreatment processes.

Integration between the ATR and SCT-CPO sections offers operating and economic advantages in the production of synthesis gas and in the processes which use it. In particular, said configuration allows both to increase the production capacity in existing ATR plants, and to utilize reagents of different composition and to obtain synthesis gas mixtures suitable for different production systems. Adiabatic oxidative "pre-reforming" stages allow to reduce energy consumption in subsequent reaction stages and to increase further process flexibility for the production of synthesis gas. In addition to this the exothermic pre-reformers also make it possible to process complex gaseous hydrocarbon feedstock rich in olefins present in some refinery gases and in general those gaseous and liquid feedstock and oxygenated compounds which it would not otherwise be possible to use in an endothermic pre-reformer because they would cause

deactivation of the catalytic systems and the formation of carbonaceous deposits.

The process described and claimed in this text also requires less preheating of the reagents which are fed to SCT-CPO. SCT-CPO technology does not in fact require the major pre-heating furnaces which are used for ATR technology, these furnaces determine high C0₂ emissions which are difficult to recover. Integration between SCT-CPO technology and ATR technology also offers the possibility of using in the production of synthesis gas, both gaseous and/or liquid hydrocarbon feedstock, which may also be mixed together, with oxygenated compounds and compounds deriving from biomass, increasing the "bio" quota in products from different industrial processes, in particular in GTL conversions by means of the Fischer-Tropsch processes and methanol synthesis processes.

In greater detail Figures 1 -7 describe some preferred embodiments of this invention. In Figure 1 a first gaseous stream, preferably refinery gas or natural gas, or mixtures thereof, (2), is desulfurised in a hydrodesulfurisation treatment unit (6) and is

subsequently mixed with steam (1 ). The said mixture is separated into two parts. One part is mixed with a stream containing oxygen (4) and passed to an ATR, one part is mixed with a stream containing oxygen (4), with steam (5) and with a third stream containing liquid and/or gaseous compounds in which the said gaseous compounds are hydrocarbons other than natural gas and/or refinery gas or are even gaseous compounds which can be derived from biomass, and in which the said liquid compounds are of the hydrocarbon type, or compounds of various kinds deriving from biomass, or their mixtures, in order to be fed to a SCT-CPO reactor. The ATR and SCT-CPO reactors each produce a synthesis gas which is cooled in two heat exchangers (7, 8) giving rise to steam which is delivered as a feed (1 , 5) or exported for other uses (13).

Figure 2 partly reproduces the diagram in Figure 1 , but the synthesis gas produced by ATR and SCT-CPO is combined into a single stream and cooled in a single heat exchanger (7) generating steam which is delivered as a feed (1 , 5) or exported for other uses (13).

Figure 3 partly reproduces the diagram in Figure 1 and the synthesis gas produced by ATR and SCT-CPO is cooled (7, 8), generating steam. The two cooled synthesis gas streams are then mixed and reacted in a water gas shift - WGS - section (15). The "shifted" synthesis gas is cooled (16), generating steam.

Figure 4 partly reproduces the diagram in Figure 1 but the reagents are sent to two adiabatic pre-reformers, the first pre-reformer is endothermic and adiabatic (17) and located upstream of the ATR, the second pre-reformer is exothermic and adiabatic and is located upstream of the SCT-CPO.

Figure 5 partly reproduces Figure 1. In addition the streams of synthesis gas produced are cooled (8, 7) in two technologically different heat exchangers. One of the two (7) is a heat exchanger of the waste heat boiler (WHB) type, the other (8) is a heat exchanger known as a syngas cooler (SGC) as described in this text. Both give rise to streams of steam which are delivered to the feed stream (1 ) to the synthesis gas production reactors or exported (12, 13) for other purposes. The two suitably cooled streams of synthesis gas are passed to a WGS reactor (15) which produces a shift gas rich in H₂ (17), which is further cooled in the SGC device (8). The synthesis gas (1 1 ) obtained in this way is available for different applications.

Figure 6 reproduces the scheme of Figure 1 integrated in a methanol synthesis process. The synthesis gas produced is compressed (19) and passed to a methanol synthesis reactor (20) with recycling of the synthesis gas (21 ). The methanol is then purified after a distillation step (22, 23).

Figure 7 reproduces the scheme of Figure 1 integrated in a Fischer Tropsch (F-T) synthesis process (24) with recycling loop (25) from which products rich in mineral distillates are obtained after hydrotreatment (26). The scheme provides for that part of the recycled gas from the F-T reactor is sent to the SCT-CPO reactor.

Claims

An integrated process for the production of synthesis gas which comprises the following steps:

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

b) sending the first stream, after mixing with steam and a stream containing oxygen, to an AutoThermal Reformer section to form a first stream of synthesis gas,

c) sending the second stream to a short contact time catalytic

partial oxidation section after mixing it with a stream containing oxygen, steam and optionally C0₂, and a third stream containing liquid and/or gaseous compounds, in which the said gaseous compounds are selected from hydrocarbons other than natural gas and/or refinery gas, or from those gaseous compounds which can also be derived from biomass, and in

which the said liquid compounds are selected from hydrocarbons or

compounds of various kinds deriving from biomass, or mixtures thereof, thus producing a second stream of synthesis gas.

A process according to claim 1 characterised in that a pre-reforming step is provided upstream of the short contact time catalytic partial oxidation section, or upstream of the AutoThermal Reforming section, or both.

A process according to claim 2 characterised in that the pre-reforming step upstream of the short contact time catalytic partial oxidation section is adiabatic exothermic or endothermic adiabatic.

4. A process according to claim 2 characterised in that the pre-reforming step upstream of the AutoThermal Reforming section is adiabatic exothermic or endothermic adiabatic.

5. A process according to claim 2 characterised in that a endothermic adiabatic pre- reforming step is provided upstream of an AutoThermal Reforming section and upstream of a short contact time catalytic partial oxidation section.

6. A process according to claim 2 characterised in that an endothermic adiabatic pre- reforming step is provided upstream of an AutoThermal Reforming section and an exothermic adiabatic pre-reforming step is provided upstream the short contact time catalytic partial oxidation section.

7. A process according to claim 2 characterised in that an exothermic adiabatic pre- reforming step is provided upstream of an AutoThermal Reforming section and an exothermic adiabatic pre-reforming step is provided upstream of short contact time catalytic partial oxidation section.

8. A process according to claim 2 characterised in that an exothermic adiabatic pre- reforming step is provided upstream of an AutoThermal Reforming (ATR) section and an endothermic adiabatic pre-reforming upstream of a short contact time catalytic partial oxidation section.

9. A process according to claim 2 in which part of the first gaseous hydrocarbon

stream, preferably selected from natural gas and/or refinery gas, is fed to an endothermic adiabatic pre-reformer or to an exothermic adiabatic pre-reforming placed upstream of an AutoThermal Reforming reactor.

10. A process according to claim 2 characterised in that the second gaseous

hydrocarbon stream, preferably selected from natural gas and/or refinery gas, is fed to an endothermic adiabatic pre-reformer or an exothermic adiabatic pre-reformer arranged upstream of a short contact time catalytic partial oxidation section.

1 1 . A process according to claim 2 characterised in that the third stream containing gaseous compounds, characterised in that said gaseous compounds are selected from hydrocarbons from natural gas and/or refinery gas, or even from those gaseous compounds which can be derived from biomass, is fed to a pre-reformer or to an exothermic adiabatic pre-reformer or to an endothermic adiabatic pre-reformer placed upstream of a short contact time catalytic partial oxidation section.

12. A process according to claim 2 characterised in that the third stream containing liquid compounds in which said liquid compounds are of the hydrocarbon type, or compounds of various kinds deriving from biomass, or mixtures thereof, is only fed to an exothermic adiabatic pre-reformer placed upstream of a short contact time catalytic partial oxidation section.

13. A process according to claim 2, characterised in that if the third stream contains both liquid compounds and gaseous compounds these are fed only to an exothermic adiabatic pre-reformer placed upstream of a short contact time catalytic partial oxidation section.

14. The integrated process for the production of synthesis gas according to any one of claims 1 to 13 characterised in that the first and the second stream of synthesis gas are sent separately each to a single heat-exchange device to be cooled, yielding up part of the heat of reaction to generate steam.

15. The integrated process according to claim 14 characterised in that part of the steam generated is used as a reactant in the AutoThermal Reforming section, and part is fed to the short contact time catalytic partial oxidation sections.

16. A process according to any one of claims 1 to 15 characterised in that if the gaseous hydrocarbon stream contains sulfur compounds it is subjected to hydro- desulfurisation treatment before being sent to the pre-reformer or to the

AutoThermal Reforming (ATR) section and short contact time catalytic partial oxidation sections.

17. An integrated process according to any one of claims 1 to 16 characterised in that the synthesis gas produced in both the AutoThermal Reforming (ATR) and short contact time catalytic partial oxidation sections is used for methanol synthesis.

18. An integrated process according to any one of claims 1 to 16 characterised in that the synthesis gas produced in both the AutoThermal Reforming (ATR) and short contact time catalytic partial oxidation sections is used for the synthesis of liquid hydrocarbons via Fischer Tropsch synthesis.