WO2018099692A1 - Method for the production of a syngas from a stream of light hydrocarbons and from a gas feed comprising co2, n2, o2 and h2o and originating from an industrial plant comprising a combustion furnace - Google Patents

Abstract

The invention relates to a method for the production of a syngas containing CO and H₂ from a stream of light hydrocarbons and from a gas feed (70) originating from an industrial plant comprising a combustion furnace (100) and a means (200) for discharging the gas feed, said gas feed comprising CO₂, N₂, O₂ and H₂O, but no hydrogen, said method comprising the following steps: removing the gas feed (101) obtained in the industrial plant upstream of the gas-feed discharge means (300); preparing a reaction flow (113) comprising a stream of light hydrocarbons (110) including methane and the gas feed (101); and conveying the reaction flow (113) into a tri-reforming reactor (1009) in order to produce a syngas (114).

Description

Process for producing a synthesis gas from a light hydrocarbon stream and a gaseous feedstock comprising CO ₂ , N ₂ , O ₂ and H ₂ O industrial unit comprising a combustion furnace Technical field

 The present invention relates to the field of production of synthesis gas by tri-reforming reaction by means of a gaseous feedstock from an industrial unit comprising a combustion furnace. The synthesis gas obtained makes it possible to produce paraffinic or olefinic hydrocarbons, which are bases of high quality liquid fuels (diesel cutters with a high cetane number, kerosene, etc.) or petrochemical bases, which can be obtained more particularly at by means of a Fischer-Tropsch synthesis step.

State of the art

Several processes are known for producing synthesis gas from carbonaceous materials, in particular the partial oxidation reaction and the reforming of methane.

Partial oxidation, or partial oxidation gasification (known by the acronym POX which comes from the English word "partial oxidation" which means partial oxidation), consists in forming under combustion under sub-stoichiometric conditions a mixture at high temperature, generally between 1000 ^° C and 1600 ° C, carbon material on the one hand and air or oxygen on the other hand, to oxidize the carbonaceous material and obtain a synthesis gas. Partial oxidation is compatible with all forms of carbon feedstock, including heavy loads. The partial oxidation reaction corresponds to the balance equation (1) below:

½ 0 ₂ + CH ₄ <=> CO + 2H ₂ (1)

Methane reforming is a chemical reaction that consists of producing hydrogen from methane. There are two types of methane reforming process.

The reforming with steam (or steam reforming) known under the acronym SMR which comes from the English "steam methane reforming" which means "reforming methane with steam, consists in reacting the charge, typically a natural gas or light hydrocarbons , on a catalyst in the presence of steam to obtain a synthesis gas which contains mainly, out of steam, a mixture of carbon monoxide and hydrogen. Steam reforming is an endothermic reaction whose H ₂ / CO molar ratio is close to 3. Steam reforming satisfies the following balance equation (2):

CH ₄ + H ₂ 0 <=> CO + 3H ₂ (2) Moreover, the dry reforming is a highly endothermic reaction whose molar ratio H ₂ / CO is close to 1. The dry reforming corresponds to the following balance equation (3):

C0 ₂ + CH ₄ <=> 2CO + 2H ₂ (3)

However, the H ₂ / CO ratio of the synthesis gas produced during dry reforming or steam reforming is unsatisfactory for the production of fuels which require an H ₂ / CO molar ratio of the order of 2. The combination of these two processes provides rations closer to those desired, but the resulting production of carbon ("coke") on the catalyst is a major drawback.

A solution proposed in the prior art consists in combining three catalytic reactions: dry reforming, steam reforming and the partial oxidation reaction, these three reactions being all carried out in the same reactor. This reaction combination is called catalytic tri-reforming. Catalytic tri-reforming is of interest for the formation of synthesis gas. Indeed, Song et al. (Chemical Innovation, 31 (2001) 21-26) disclose a method for reacting at high temperature a gas comprising CH ₄ , CO ₂ , ΓO ₂ and H ₂ O in the presence of a catalyst for produce CO and H ₂ in controlled ratios.

Document US2008 / 0260628 discloses a process for producing synthesis gas comprising a methane reforming reaction step by supplying a mixture of carbon dioxide, water vapor and oxygen and using a catalyst based on of nickel.

Document US2015 / 0031922 describes a process for producing synthesis gas by catalytic tri-reforming using a mixture of hydrocarbons, CO ₂ , H ₂ O and O ₂ . C0 ₂ comes from combustion gases of various industrial processes obtained after a separation step, in particular by separation with amine washing.

In particular, catalytic tri-reforming makes it possible to recover C0 ₂ from combustion fumes (here also referred to as combustion gas or gaseous feedstock) from power plants (Song et al., Prepr Pap.Am.Chem Soc, Div. Fuel Chem., 2004, 49 (1), 128). The synthesis gas thus obtained can then be recovered by Fischer-Tropsch reaction, in particular for the production of synthetic fuels.

Thus, it is known from the state of the art to use a combustion gas from an industrial unit in tri-reforming reactions. However, the flue gases are taken out of the chimneys of the furnaces, and therefore have a low temperature, ie about 150 ° C [cf. Song et al., Prepr. Pap.-Am. Chem. Soc. Div. Fuel Chem., 2004, 49 (1), 128]. Therefore, it is necessary to heat the combustion gases to the temperature of the tri-reforming reaction, ie a temperature typically between 650 and 900 ° C. Moreover, the relatively low temperature of the combustion gases at the outlet of chimneys can cause the condensation of water vapor contained in the combustion gases and therefore can substantially modify the H ₂ O / Hydrocarbon (HC) ratio, which will no longer be optimal. for the catalytic tri-reforming reaction.

The Applicant has developed a new process for producing a synthesis gas obtained from a tri-reforming catalytic reaction using directly, preferably without intermediate steps of separation of C0 _2, combustion gas from d industrial units comprising a combustion furnace upstream of the combustion gas exhaust stacks, and more particularly units of the hydrogen production unit type by steam methane reforming, ammonia production unit, unit of production of lime, glass production unit, or thermal power plant supplied with gas, oil or coal. Indeed, the combustion gases (also called here combustion fumes or gaseous filler) from such units have the advantage of having high concentrations of C0 ₂ , allowing a synthesis gas production with better energy efficiency, lower greenhouse gas emissions, and high carbon yield.

Objects of the invention

The present invention relates to a process for producing a synthesis gas containing CO and H ₂ from a light hydrocarbon stream and a gaseous feedstock from an industrial unit comprising at least one furnace and at least one means for evacuating the gaseous charge to the outside of said industrial unit, said gaseous feed comprising CO ₂ , N ₂ , ΓO ₂ and H ₂ O, optionally CO 2 the exclusion of a gaseous feedstock from a cement clinker production unit, but not including hydrogen, which process comprises the following steps:

a) at least a portion of said gaseous feedstock obtained in said industrial unit is taken upstream of said means for discharging the gaseous feed, said gaseous feedstock being taken at a temperature of between 180 and 800 ° C .;

b) optionally, said gaseous feedstock obtained in step a) is treated;

c) preparing a reaction stream comprising a stream of light hydrocarbons comprising methane and said gaseous feedstock obtained in step a) or said treated gaseous feedstock obtained in step b) and; d) said reaction stream is sent to a tri-reforming reactor to obtain a synthesis gas, said tri-reforming reactor operating at a temperature between 650 and 900 ° C, a pressure of between 0.1 and 10 MPa, and a VVH between 0.1 and

200 Nm ³ /h.kg _cata i _yse ur.

In a particular embodiment of the invention, the gaseous feed further comprises CO.

 Process according to Claim 2, characterized in that the reaction flow comprises:

a 0 ₂ / HC volume ratio of between 0.02 and 0.3;

a C0 ₂ / HC volume ratio of between 0.10 and 0.5;

a H ₂ 0 / HC volume ratio of between 0.2 and 0.9;

a volume ratio N ₂ / HC of between 0.1 and 3.0.

 a CO / HC volume ratio of between 0.005 and 0.5.

 Advantageously, said industrial unit is chosen from a thermal power plant fed with coal or a lime production unit.

Process according to any one of Claims 1 to 4, characterized in that a step is carried out between step a) and b) or c) of said process in which the gaseous feedstock, optionally treated, is filtered.

 In another embodiment of the invention, the gaseous feedstock does not contain CO, excluding gaseous feedstocks from cement clinker production units. Preferably, the reaction flow comprises:

a 0 ₂ / HC volume ratio of between 0.02 and 0.3;

a C0 ₂ / HC volume ratio of between 0.10 and 0.5;

a H ₂ 0 / HC volume ratio of between 0.2 and 0.9;

a volume ratio N ₂ / HC of between 0.1 and 3.0.

Advantageously, the industrial unit is chosen from a hydrogen production unit by steam methane reforming, a glass production unit, or a thermal plant fed with gas or fuel oil.

Advantageously, said gaseous feedstock comprises a CO ₂ content of between 5 and 50% by volume.

Preferably, the sampling of the gaseous feedstock in step a) is carried out either directly at the outlet of the combustion furnace, or after at least one step of purifying said gaseous feedstock from the combustion furnace, said purification step being carried out by means of an absorber-neutralizer.

 In a preferred embodiment, the step b) of treating said gaseous feed obtained in step a), said step b) comprising the following substeps:

i) cooling said gaseous charge taken in step a); ii) sending said cooled gaseous feed into a first separation tank to obtain a first gaseous effluent and a first liquid effluent;

iii) sending the first gaseous effluent into a first compressor to obtain a first gaseous effluent compressed;

iv) cooling the first compressed gaseous effluent to obtain first cooled compressed gaseous effluent;

v) sending the first cooled compressed gaseous effluent to a second separation tank to obtain a second gaseous effluent (and a second liquid effluent;

vi) the second effluent gas is sent into a second compressor to obtain second compressed gaseous effluent;

vii) contacting the second compressed gaseous effluent obtained in step vi) with at least a portion of said second liquid effluent obtained in step v) to form said gaseous feed treated.

 Advantageously, said gaseous feed is cooled in step i) to a temperature between 60 and 80 ° C.

 Advantageously, said first gaseous effluent is cooled in step iv) to a temperature between 30 and 60 ° C.

 Advantageously, the reaction stream is preheated to a temperature between 500 and 850 ° C.

Advantageously, said light hydrocarbon stream is a natural gas or a liquefied petroleum gas.

 Preferably, a steam and / or oxygen booster is provided between step a) and d) of said method.

 Advantageously, the tri-reforming reactor comprises at least one supported catalyst comprising an active phase comprising at least one metal element in oxide form or in metallic form chosen from groups VIIIB, IB, MB, alone or as a mixture.

Description of the figure

 Figure 1 is a simplified schematic representation of an industrial installation comprising a combustion furnace 100 and a flue gas discharge device 200 from the combustion furnace.

 Figure 2 is a simplified schematic representation of the method according to the invention.

FIG. 3 is a schematic representation of a particular embodiment of the method according to the invention, in which the gaseous charge 70 taken from the industrial unit (step a) is treated (step b) before being put in contact with each other; with a hydrocarbon stream 110 (step c) to form the reaction stream 113 of the catalytic tri-reforming reaction (step d).

Detailed description of the invention

Definitions

In the following, groups of chemical elements are given according to the CAS classification (CRC Handbook of Chemistry and Physics, publisher CRC press, editor in chief DR Lide, 81 ^st edition, 2000-2001). For example, group VIII according to the CAS classification corresponds to the metals of columns 8, 9 and 10 according to the new IUPAC classification.

The textural and structural properties of the support and the catalyst described below are determined by the characterization methods known to those skilled in the art. The total pore volume and the porous distribution are determined in the present invention by nitrogen porosimetry as described in the book "Adsorption by powders and porous solids. Principles, methodology and applications "written by F. Rouquérol, J. Rouquérol and K. Sing, Academy Press, 1999.

Specific surface area is understood to mean the BET specific surface area (S _B AND in m ² / g) determined by nitrogen adsorption in accordance with the ASTM D 3663-78 standard established from the BRUNAUER-EMMETT-TELLER method described in the periodical. "The Journal of the American Society", 1938, 60, 309.

In the context of the present invention, the term "light hydrocarbons" denotes hydrocarbon compounds comprising between 1 and 4 carbon atoms (C1-C4).

Process description

The present invention relates to a process for producing a synthesis gas containing CO and H ₂ from a light hydrocarbon stream and a gaseous feed comprising CO ₂ , N ₂ , CO _{2 and} CO _2. 0 ₂ and H ₂ 0, and optionally CO, said gaseous feed being derived from an industrial unit comprising at least one combustion furnace and at least one means for evacuating the gaseous charge to the outside of said industrial unit. Preferably, the industrial unit is chosen from a hydrogen production unit by steam methane reforming, an ammonia production unit, a lime production unit, a glass production unit, or a central unit. heat supplied with gas, fuel oil or coal.

As with any industrial process, the person skilled in the art is constantly confronted with the problems of increasing the production and productivity of industrial installations. That is why the Applicant has developed a method of producing a synthesis gas containing CO and H ₂ from a light hydrocarbon stream and a gaseous feedstock comprising CO ₂ , N ₂ , O ₂ and H ₂ O, and possibly CO, from an industrial unit comprising at least one combustion furnace and at least one means for evacuating the gaseous charge to the outside of said industrial unit.

Referring to Figure 1, schematically illustrating an industrial unit, a combustible material 10 is sent to the combustion furnace 100 (also referred to herein as a calcination furnace). The product resulting from the combustion in the combustion furnace 100 is evacuated via the line 20. The gaseous feed 70 (also called combustion fumes) coming from the combustion furnace 100 is for its part sent towards the outside of the industrial unit by means of a flue gas evacuation device 200, such as chimneys.

The combustible material 10 may be any conventional fuel, such as natural gas, fuel oil, coal, or unconventional fuel, such as biomass or carbonaceous waste (used oil, solvents, tires, sewage sludge). , ...).

According to the synthesis gas production method according to the invention, the gaseous feed 70 obtained after transformation of the combustible material 10 in the combustion furnace 100 is taken upstream of the flue gas discharge means 200 and is then put into operation. contact with a stream of light hydrocarbons to form a reaction stream, the latter being sent to a tri-reforming reactor to obtain the synthesis gas.

More particularly, with reference to FIG. 2, the process for producing a synthesis gas from a light hydrocarbon stream and a gaseous feedstock comprising CO ₂ , N ₂ , ΓO ₂ and H ₂ O, and optionally CO, derived from an industrial unit comprising at least one combustion furnace 100 and at least one means for evacuating the gaseous charge 200 to the outside of said industrial unit, comprises the following steps :

a) said gaseous feed 70 obtained in said industrial unit is taken upstream of said means for evacuating the gaseous feed 200, preferably without performing an intermediate separation step, said gaseous feed 70 being taken at a temperature of between 180 and 800 ° C, preferably between 200 and 500 ° C, and even more preferably between 250 and 500 ° C;

b) optionally, said gaseous charge 70 taken in step a) is treated to obtain a treated gaseous feed 101; c) a reaction stream 113 comprising a stream of light hydrocarbons 110 comprising methane and said gaseous feed 70 obtained in step a), or optionally said treated gaseous feed 101 obtained in step b) and;

d) said reaction stream 113 is sent to a tri-reforming reactor 1009 to obtain a synthesis gas 114, said tri-reforming reactor 1009 operating at a temperature of between 650 and 900 ° C., a pressure of between 0.1 and 5 MPa, and a VVH between 0.1 and 200 Nm ^{3 /} h.kg _ca.

Steps a) to d) are described in more detail below.

Step a)

 In step a), the gaseous feed 70 from the combustion furnace 100 is taken upstream of the means for evacuating the gaseous feedstock 200 towards the outside of the industrial unit, preferably without performing a separation step intermediate.

All or part of the gaseous feed 70 can be implemented. The flow rate of the gaseous feed 70 taken in step a) is between 10,000 to 2,000,000 Nm ³ / h, preferably 20,000 to 1,000,000 Nm ³ / h.

In a first embodiment according to the invention, the gaseous feed 70 taken in step a) comprises CO ₂ , N ₂ , O ₂ and H ₂ O, CO, but does not include no H ₂ . More particularly, the gaseous feed 70 comprises between 2% to 60% by volume of CO ₂ , preferably between 5% and 50% by volume.

When the industrial unit is a coal-fired thermal power plant, the gaseous feedstock 70 comprises between 2% to 30% by volume of C0 ₂ , preferably between 5% and 25% by volume, and even more preferably between 5% and 20% by volume. % in volume.

When the industrial unit is a lime production unit, the gaseous feedstock 70 comprises between 10% to 60% by volume of C0 ₂ , preferably between 15% and 50% by volume, and even more preferably between 20% and 50% by volume.

More particularly, the gaseous feed 70 comprises between 30% to 80% by volume of N ₂ , preferably between 30% and 70% by volume.

When the industrial unit is a thermal power plant supplied with coal, the gaseous feed 70 comprises between 50% to 80% by volume of N ₂ , preferably between 55% and 75% by volume, and even more preferably between 65% and 75% by volume. % in volume.

When the industrial unit is a lime production unit, the gaseous feedstock 70 comprises between 30% to 80% by volume of N ₂ , preferably between 30% and 70% by volume, and still more preferably between 35% and 65% by volume. More particularly, the gaseous feedstock comprises between 0.5% to 20% by volume of O ₂ , preferably between 1% and 15% by volume.

When the industrial unit is a thermal power plant supplied with coal, the gaseous feedstock 70 comprises between 0.5% to 15% by volume of O ₂ , preferably between 1% and 10% by volume, and even more preferably between 2% by volume. % and 10% by volume.

When the industrial unit is a lime production unit, the gaseous feedstock 70 comprises between 1% to 20% by volume of O ₂ , preferably between 1% and 15% by volume, and even more preferably between 2%. and 10% by volume.

More particularly, the gaseous feedstock comprises between 0.5% to 30% by volume of CO, preferably between 1% and 30% by volume.

 When the industrial unit is a coal-fired thermal power plant, the gaseous filler 70 comprises between 1% to 30% by volume of CO, preferably between 2% and 30% by volume, and even more preferably between 2% and 25% by weight. in volume.

When the industrial unit is a lime production unit, the gaseous feedstock 70 comprises between 0.5% to 20% by volume of CO, preferably between 1% and 15% by volume, and even more preferably between 1%. and 10% by volume. More particularly, the gaseous feedstock comprises from 2% to 25% by volume H ₂ 0, preferably from 5% to 25% by volume, and even more preferably between 5% and 20% by volume.

In another embodiment according to the invention, the gaseous feed 70 taken in step a) comprises CO ₂ , N ₂ , ΓO ₂ and H ₂ O, but does not include H ₂ and does not include CO, excluding gaseous feeds from the manufacture of cement clinker.

More particularly, the gaseous feed 70 comprises between 7% to 40% by volume of CO ₂ , preferably between 15% and 35% by volume.

When the industrial unit is a unit for producing hydrogen, the gaseous feedstock 70 comprises between 10% to 35% by volume of C0 ₂ , preferably between 10% and 30% by volume, and even more preferably between 15% and 25% by volume.

When the industrial unit is a glass production unit, the gaseous feedstock 70 comprises between 20% to 60% by volume of C0 ₂ , preferably between 25% and 50% by volume, and even more preferably between 30% and 50% by volume. When the industrial unit is a thermal power plant supplied with gas or oil, the gaseous feedstock 70 comprises between 2% to 30% by volume of C0 ₂ , preferably between 5% and 25% by volume, and even more preferably between 5% and 20% by volume. More particularly, the gaseous feedstock comprises between 20% to 80% by volume of N ₂ , preferably 25% to 75% by volume.

When the industrial unit is a unit for producing hydrogen, the gaseous feedstock 70 comprises between 40% to 80% by volume of N ₂ , preferably between 45% and 75% by volume, and even more preferably between 50%. and 70% by volume.

When the industrial unit is a glass production unit, the gaseous feedstock 70 comprises between 20% to 80% by volume of N ₂ , preferably between 25% and 70% by volume, and even more preferably between 30% and 65% by volume.

When the industrial unit is a thermal power plant supplied with gas or fuel oil, the gaseous feedstock 70 comprises between 50% to 80% by volume of N ₂ , preferably between 55% and 75% by volume, and even more preferentially between 65% and 75% by volume.

More particularly, the gaseous feedstock comprises from 0.5% to 20% by volume of O ₂ , more preferably from 1% to 10% by volume.

When the industrial unit is a unit for producing hydrogen, the gaseous feed 70 comprises between 0.5% to 15% by volume of O ₂ , preferably between 0.5% and 10% by volume, and more preferably between 1% and 5% by volume.

When the industrial unit is a glass production unit, the gaseous feedstock 70 comprises between 1% to 20% by volume of O ₂ , preferably between 1% and 15% by volume, and even more preferably between 2%. and 10% by volume.

When the industrial unit is a thermal power plant supplied with gas or fuel oil, the feed gas 70 comprises between 0.5% to 15% by volume of 0 _2, most preferably between 1% and 10% by volume, and still more preferably between 1, 5% and 5% by volume.

More particularly, the gaseous feedstock comprises from 2% to 25% by volume of H ₂ O, preferably from 5% to 20% by volume.

When the industrial unit is a hydrogen production unit, the gaseous feedstock 70 comprises between 2% to 25% by volume of H ₂ 0, preferably between 5% and 25% by volume, and even more preferentially between 5% and 25% by volume. % and 20% by volume.

When the industrial unit is a glass production unit, the gaseous feedstock 70 comprises between 2% to 25% by volume of H ₂ 0, preferably between 5% and 25% by volume, and even more preferentially between 5% and 20% by volume. When the industrial unit is a thermal power plant supplied with gas or fuel oil, the gaseous feedstock 70 comprises between 5% to 25% by volume of H ₂ 0, preferably between 7% and 25% by volume, and even more preferentially between 8% and 20% by volume. The temperature of the gaseous feed 70 taken in step a) is between 180 ° C and 800 ° C, preferably between 200 ° C and 500 ° C, very preferably between 250 ° C and 500 ° C.

In the particular embodiment in which the industrial unit is chosen from a lime-producing unit or a coal-fired thermal power plant, a step of filtering the combustion fumes 70 taken in step a) is advantageously carried out in order to reduce the dust content of combustion fumes. For example, the filtration step can be performed by means of bag filters or ceramic filters. Preferably, the dust content in the combustion fumes 70 after the filtration step is less than 1000 mg / m ³ , very preferably less than 100 mg / m ³ .

Preferably, the gaseous feed 70 taken in step a) undergoes a desulfurization step to reduce the content of H ₂ S, COS, mercaptans or other sulfur compounds possibly present in said gaseous feed. This desulfurization step can be carried out by any method known to those skilled in the art, for example by a step of hydrogenation of the sulfur compounds followed by a step of fixing H ₂ S. During the hydrogenation step the sulfur compounds (COS, mercaptans, etc.) are converted into H ₂ S by reaction with the hydrogen contained in said gaseous feedstock to be treated. The reaction is carried out at a temperature of about 350 to 400 ° C in the presence of a hydrogenation catalyst. Generally, the hydrogenation catalyst employed comprises as active phase at least one Group VIB metal, such as molybdenum, and at least one Group VIIIB metal, preferably selected from cobalt or nickel. The catalyst further comprises a support comprising a refractory oxide, preferably alumina. Advantageously, the catalyst used is in sulphurized form. The second step of fixing the H ₂ S is generally carried out at a temperature of between 200 and 400 ° C. in the presence of a capture mass comprising a compound of metal, oxide, zeolite or even carbonate type, and at least one member selected from the group consisting of Ca, Mg, Mn, Fe, Ni, Cu, Zn, Ag, Sn, La, Ce. Preferably, the capture mass comprises Zn in oxide form (ZnO) at a content of between 85% by weight and 100% by weight in oxide form relative to the total weight of the capture mass. Binders may be used such as silica, alumina or an alumina precursor, clays such as bentonite, kaolinite, montmorillonite, alone or as a mixture, in order to impart sufficient mechanical strength to the shaped solid. The capture mass may be in the form of preferably cylindrical or multilobed extrudates, spheres or pellets.

Step b) (optional)

 In a particular embodiment of the process according to the invention, a step b) is carried out for treating the gaseous feed 70 taken in step a). This step allows a condensation adjustment of the amount of water required for the catalytic tri-reforming reaction as well as a reduction in the electrical power consumed by decreasing the aspirated volume flow rate.

 In step b) of the process according to the invention, the gaseous feed 70 obtained in step a) is treated to obtain a treated gaseous feed 101.

 Referring to FIG. 3, when step b) of treating the gaseous feed 70 taken in step a), step b) comprises the following sub-steps:

 i) cooling the gaseous charge 70 taken in step a);

 ii) the cooled gaseous feed 102 is fed into a first separation tank 1002 to obtain a first gaseous effluent 103 and a first liquid effluent 118;

 iii) the first gaseous effluent 103 is sent into a first compressor 1003;

 iv) cooling the first compressed gaseous effluent 104;

 v) sending the first cooled compressed gaseous effluent 105 into a second separation tank 1005 to obtain a second gaseous effluent 106 and a second liquid effluent 108;

 vi) the second gaseous effluent 106 is sent to a second compressor 1006;

 vii) contacting the second compressed gaseous effluent 107 obtained in step vi) with at least a portion of said second liquid effluent 108 obtained in step v) to form the treated gaseous feed 101.

The temperature of the gaseous feed 70 taken in step a) is between 180 ° C and 800 ° C, preferably between 200 ° C and 500 ° C, very preferably between 250 ° C and 500 ° C. The pressure of the gaseous charge 70 taken in step a) is of the order of between 0.05 and 0.20 MPa (0.5 and 2.0 bar), preferably between 0.08 and 0.15. MPa (0.8 and 1.5 bar).

In step i), the gaseous feed 70 is cooled to a temperature between 60 and 80 ° C by yielding its calories to the flow 113 in a first exchanger 1001. The cooled gaseous feed 102 is sent into a guard balloon 1002 to obtaining a first gaseous effluent 103 and a first liquid effluent 118 (step ii)). The pressure of the first gaseous effluent 103 is increased between 0.1 and 0.2 MPa (1 and 2 bar) by a first compressor 1003 (step iii) from which emerges a first compressed gaseous effluent 104 which is cooled to a temperature between 30 and 60 ° C by a water exchanger 1004 (step iv).

The first cooled compressed gaseous effluent 105 is sent to a separator tank 1005 to obtain a second gaseous effluent 106 and a second liquid effluent 108 composed essentially of condensed water (step v).

 The pressure of the second gaseous effluent 106 from the separator 1005 is increased between 0.1 and 0.5 MPa (1 and 5 bar) by a second compressor 1006 from which a second compressed gaseous effluent 107 emerges (step vi).

 Finally, at least a portion of the second compressed gaseous effluent 107 obtained in step vi) is brought into contact with at least a portion of said second liquid effluent 108 obtained in step v) (via line 109) to form the charge. treated gaseous 101 (step vii). The other part of the second liquid effluent is removed from the process via line 119, preferably at a flow rate of the order of 15 to 25% by volume relative to the total flow rate of the second liquid effluent 108. Preferably, said at least a portion second liquid effluent 109 passes through a pump 1007 before being mixed with the second compressed gaseous effluent 107.

Step c)

According to step c) of the process, a reaction stream 113 comprising a stream of light hydrocarbons 110 comprising methane and the gaseous feed 70 taken in step a) (see FIG. 2) or the treated gaseous feed 101 is prepared. (see Figure 3) of step b). The reaction flow 113 is then sent to the tri-reforming reactor 1009. Preferably the hydrocarbon source is a natural gas or a liquefied petroleum gas, very preferably the hydrocarbon source is a natural gas comprising at least 50% by volume of methane, preferably at least 60% by volume of methane, and more preferably at least 70% by volume of methane. In the particular embodiment in which the method according to the invention comprises a step of treatment of the combustion fumes taken in step a) (ie when step b) is carried out), the reaction flow 113 is obtained by setting in contact with the second liquid effluent 108, the second compressed gaseous effluent 107 and the light hydrocarbon stream. Advantageously, the reaction stream 113 is heated in an exchanger 1001 by combustion fumes 70 taken in step a) of the process. The reaction flow resulting from this exchanger 1001 can then be brought to a temperature close to that of the catalytic tri-reforming reaction, at a temperature between 500 and 850 ° C, preferably at a temperature between 750 ° C and 850 ° C, via the heat exchanger 1008. The reaction flow 113 is then sent to tri-reforming reactor 1009. Oxygen bonds are made in all proportions to obtain a reaction flow 113 with the desired volume ratio between the reagent 0 ₂ and the hydrocarbon source (HC). These additions can be made together or separately, and before or after mixing the gaseous feedstock with the hydrocarbon source. In particular, these additions may be carried out either by a stream 116 added directly to the gaseous feed 70 taken in step a), or added by a stream 117 added to the reaction stream 113 before or after passage through the exchanger 1001.

The oxygen source may preferably be atmospheric air or an oxygen stream coming either from a cryogenic air separation (ASU) process, or from a pressure swing adsorption (PSA) process, or a vacuum swing adsorption (VSA) process. When a steam filling is performed, any source of water vapor or steam generation process may be used.

Preferably the CO ₂ / HC volume ratio of the reaction stream 113 is between 0.1 and 0.5, very preferably between 0.1 and 0.4.

Preferably, the volume ratio H ₂ O / HC of the reaction stream 113 is between 0.2 and 0.9, very preferably between 0.4 and 0.9.

Preferably, the volume ratio N ₂ / HC of the reaction stream 113 is between 0.1 and 3.0, very preferably between 0.2 and 1.5.

Preferably the volume ratio O ₂ / HC of the reaction stream 113 is between 0.02 and 0.3, very preferably between 0.05 and 0.2.

 When the reaction stream comprises CO, the volume ratio CO / HC of the reaction stream 113 is between 0.005 and 0.5, very preferably the volume ratio CO / HC is between 0.01 and 0.4.

Depending on the composition of the gaseous feed 70 taken in step a) or the treated gaseous feed 101 obtained in step b), it is possible to add water vapor in all proportions to obtain a reaction flow. 113 with the desired volume ratio between the H ₂ 0 reagent and the hydrocarbon source (HC). These supplements can be made together or separately, and before or after mixing the gaseous feedstock with the hydrocarbon source. In particular, these supplements can be made either by a flow

116 added directly to the gaseous charge 70 taken in step a), is added by a stream

117 added to the reaction stream 113.

Step d)

In step d), the feed containing the light hydrocarbons, CO ₂ , N ₂ , O ₂ and H ₂ O, optionally CO, but not including H ₂ , is sent to a catalytic reactor 1009 so as to transform said charge and obtain an effluent containing carbon monoxide and hydrogen.

The catalytic tri-reforming reactor 1009 may be any type of reactor suitable for transforming the gaseous feedstock. Preferably, the catalytic reactor will be a fixed bed reactor or a fluidized bed reactor. The reaction zone is filled with a heterogeneous catalyst having an active phase in oxide or metal form composed of at least one element chosen from groups VIII, IB, MB, alone or as a mixture. The catalyst comprises an active phase content expressed in% by weight of elements relative to the total mass of the catalyst of between 0.1% and 60%, preferably between 1% and 30%. Advantageously, the catalyst used comprises a mass content of between 20 ppm and 50%, expressed in% by weight of element relative to the total mass of the catalyst, preferably between 50 ppm and 30% by weight, and very preferably between 0.01% and 5% by weight of at least one doping element chosen from groups VIIB, VB, IVB, IIIB, IA (alkaline element), MA (alkaline-earth element), NIA, VIA, alone or in combination with mixed. The catalyst comprises a support containing a matrix of at least one refractory oxide based on elements such as Mg, Ca, Ce, Zr, Ti, Al, Si, alone or as a mixture. The support on which said active phase is deposited, as well as any dopants, may have a morphology in the form of beads, extrudates (for example of trilobed or quadrilobic form), pellets, or perforated cylinders, or a morphology under powder form of variable particle size.

When the active phase of the catalyst is in metallic form, a temperature activation step under a reducing gas can be carried out before the injection of the reaction flow 113 into the reactor 1009. In the reaction zone, the reaction flow is brought to a temperature of 650 ° C to 900 ° C and a pressure of 0.1 and 10.0 MPa (1 bar and 100 bar), preferably between 0.1 and 1.0 MPa (1 and 10 bar). The hourly volume velocity of the reaction stream is between 0.1 and 200 Nm ^{3 /} h.kg _Ca catalyst, preferably between 1 and 100 Nm ^{3 /} h.kg _cata i _yse ur, very preferably between 1 and 50 Nm ³ /h.kg _cata i _yseU r. The effluent 114 from the reactor 1009 comprising carbon monoxide and hydrogen in a volume ratio H ₂ / CO of between 1 and 3, preferably between 1.5 and 2.7, very preferably between 1, 7 and 2.7. Preferably, this effluent does not comprise more than 50% by volume of N ₂ , very preferably not more than 30% by volume.

Advantageously, the effluent 114 passes through a heat exchanger (heat exchanger 1008 in the embodiment as illustrated in FIG. 3) in order to obtain a cooled effluent 115 between 120 and 250 ° C. which can be used directly by all the routes known to those skilled in the art. Indeed, the effluent obtained according to the invention has the characteristics of a synthesis gas and can be exploited directly by all the routes known to those skilled in the art. Preferably, the effluent comprising carbon monoxide is recovered in Fischer Tropsch synthesis for the production of synthetic fuels. Before recovery of the effluent it may be advantageous to carry out a purification step, especially De-Nox and / or De-Sox by any method known to those skilled in the art.

The invention is illustrated by the following examples, which in no way present a limiting character.

Examples

 Example 1 Conversion of a Hydrogen Production Unit Combustion Effluent into a Gaseous Composition Comprising Carbon Monoxide and Hydrogen (According to the Invention)

A gaseous combustion effluent from a hydrogen production unit is taken at the furnace outlet containing 18% volume of C0 ₂ , 17% volume of H ₂ 0, 1, 5% volume of 0 ₂ and 64% volume of N ₂ . The temperature of this gas flow is 200 ° C. Additions of water vapor and oxygen (from atmospheric air), as well as a flow of natural gas are added to this ex-unit hydrogen gas flow to obtain the volume ratios. next: N ₂ / HC = 1.41; H ₂ O / HC = 0.66; CO ₂ / HC = 0.32; O ₂ / HC = 0.10.

The reaction mixture is heated to 850 ° C under a pressure of 0.25 MPa (2.5 bar), in the presence of a nickel-based catalyst (HiFUEL® R10, Johnson Matthey Pic, Alfa Aesar). The hourly volume velocity of the load is 8 Nm ^{3 /} h. Kg _cata l _y The effluent obtained contains 23% by volume of CO, 46% by volume of dihydrogen, 1, 3% by volume of CO ₂ , 2.8% by volume of H ₂ O, traces of hydrocarbons as well as 27% in volume of N ₂ .

The molar ratio H ₂ : CO is of the order of 2, which is acceptable for use as a feed of a fuel production unit by the Fischer-Tropsch process.

Conversions in C0 ₂ and hydrocarbons are respectively 79% and 96%. The carbon yield of the reaction relative to the hydrocarbons introduced is calculated at 121%. Example 2 Conversion of an Furnace Effluent from a Coal-Fired Thermal Power Plant to a Gaseous Composition Comprising Carbon Monoxide and Dihydrogen (According to the Invention)

A gaseous furnace effluent from a thermal power station fed with coal is taken out of the furnace after the electrostatic filtration step containing 15% CO ₂ volume, 10% H ₂ 0 volume, 5% CO ₂ volume, 5% CO 2 volume. 0 ₂ and 65% volume of N ₂ . The temperature of this gas flow is 250 ° C. Additions of water vapor and oxygen (by addition of atmospheric air), as well as a flow of natural gas are added to this flow of ex-thermal power gas to obtain the following volume ratios: N ₂ / HC = 1, 16; H ₂ O / HC = 0.69; CO ₂ / HC = 0.26; CO / HC = 0.09; O ₂ / HC = 0.10.

The reaction mixture is heated to 850 ° C under a pressure of 0.25 MPa (2.5 bar), in the presence of a commercial nickel catalyst (HiFUEL® R10, Johnson Matthey Pic, Alfa Aesar). The hourly volume velocity of the charge is 8 Nm3 / h.kgcatalyst. The effluent obtained contains 24% by volume of CO, 48% by volume of dihydrogen, 1% by volume of hydrocarbons, 1, 2% by volume of C0 ₂ and 2.7% by volume of H ₂ O as well as 23% by volume of N ₂ .

The molar ratio H ₂ : CO is of the order of 2, which is acceptable for use as a feed of a fuel production unit by the Fischer-Tropsch process.

Conversions in C0 ₂ and hydrocarbons are respectively 76% and 95%. The carbon yield of the reaction relative to the hydrocarbons introduced is calculated at 123%.

Other synthesis gas production processes with a molar ratio H ₂ / CO close to 2, such as partial oxidation, steam reforming or autothermal reforming, do not allow to achieve higher carbon yields of the reaction. 100% with respect to the introduced hydrocarbons (a part of the CO coming from CO ₂ ). Thus, by the best carbon yields, the process according to the invention allows a production less costly synthesis gas. In fact, less hydrocarbon is consumed per volume of synthesis gas produced at a given molar ratio H ₂ / CO.

Claims

Process for producing a synthesis gas containing CO and H ₂ from a light hydrocarbon stream and a gaseous feed (70) from an industrial unit comprising at least one combustion furnace (100) and at least one means (200) for evacuating the gaseous charge to the outside of said industrial unit, said gaseous feed comprising CO ₂ , N ₂ , O ₂ and H ₂ 0, optionally CO, excluding a gaseous feedstock from a cement clinker production unit, but not including hydrogen, which process comprises the following steps: a) at least a portion of said gaseous feedstock (101) obtained in said industrial unit is taken upstream of said means for discharging the gaseous feed, said gaseous feedstock being taken at a temperature of between 180 and 800 ° C .; b) optionally, treating said gaseous feedstock (101) obtained in step a); c) a reaction stream (1 13) comprising a stream of light hydrocarbons (1 10) comprising methane and the said gaseous feedstock (101) obtained in step a) or the said treated gaseous feedstock obtained in step b is prepared ) and; d) sending said reaction stream (1 13) into a tri-reforming reactor (1009) to obtain a synthesis gas (1 14), said tri-reforming reactor (1009) operating at a temperature of between 650 and 900 ° C, a pressure between 0.1 and 10 MPa, and a VVH between 0.1 and 200 Nm ^{3 /} h.kg _ca catalyst Process according to claim 1, characterized in that the gaseous feed additionally comprises CO. Process according to Claim 2, characterized in that the reaction stream (1 13) comprises: a 0 ₂ / HC volume ratio of between 0.02 and 0.3; a C0 ₂ / HC volume ratio of between 0.10 and 0.5; a H ₂ 0 / HC volume ratio of between 0.2 and 0.9; a volume ratio N ₂ / HC of between 0.1 and 3.0.  a CO / HC volume ratio of between 0.005 and 0.5. Process according to any one of Claims 1 to 3, characterized in that the said industrial unit is chosen from a thermal power station fed with coal or a lime production unit. 5. Method according to any one of claims 1 to 4, characterized in that between step a) and b) or c) of said method is carried out a step in which the gaseous feed, optionally treated, is filtered. 6. Process according to claim 1, characterized in that the gaseous feedstock does not contain CO and is not a gaseous feedstock from a cement clinker production unit. 7. Process according to claim 6, characterized in that the reaction stream (1 13) comprises: a 0 ₂ / HC volume ratio of between 0.02 and 0.3; a C0 ₂ / HC volume ratio of between 0.10 and 0.5; a H ₂ 0 / HC volume ratio of between 0.2 and 0.9; a volume ratio N ₂ / HC of between 0.1 and 3.0. 8. Process according to claim 6 or 7, characterized in that the industrial unit is chosen from a hydrogen production unit by reforming methane with steam, a glass production unit, or a thermal power station supplied with gas or in fuel. 9. Method according to any one of claims 1 to 8, characterized in that said gaseous feed (101) comprises a content of CO ₂ between 5 and 50% by volume. 10. Method according to any one of claims 1 to 9, characterized in that the sampling of the gaseous feed (101) in step a) is carried out either directly at the outlet of the combustion furnace, or after at least one step purifying said gaseous feedstock from the combustion furnace, said purification step being carried out by means of an absorber-neutralizer. 1 1. Process according to any one of claims 1 to 10, wherein step b) of treating said gaseous feed obtained in step a), said step b) comprising the following substeps: i) cooling said gaseous charge (101) taken in step a); ii) sending said cooled gaseous charge (102) into a first separation tank (1002) to obtain a first gaseous effluent (103) and a first liquid effluent (1 18);  iii) sending the first gaseous effluent (103) into a first compressor (1003) to obtain a first compressed gaseous effluent (104);  iv) cooling the first compressed gaseous effluent (104) to obtain first cooled compressed gaseous effluent (105);  v) sending the first cooled compressed gaseous effluent (105) to a second separation tank (1005) to obtain a second gaseous effluent (106) and a second liquid effluent (108);  vi) sending the second gaseous effluent (106) into a second compressor (1006) to obtain second compressed gaseous effluent (107);  vii) contacting the second compressed gaseous effluent (107) obtained in step vi) with at least a portion of said second liquid effluent (108) obtained in step v) to form said gaseous feed treated. 12. The method of claim 1 1, characterized in that said gaseous feed (101) is cooled in step i) at a temperature between 60 and 80 ° C. 13. The method of claims 1 1 or 12, characterized in that said first gaseous effluent (104) is cooled in step iv) at a temperature between 30 and 60 ° C. 14. A method according to any one of claims 1 to 13 characterized in that the reaction stream (1 13) is preheated to a temperature between 500 and 850 ° C. 15. Process according to any one of claims 1 to 14, characterized in that said light hydrocarbon stream (1 10) is a natural gas or a liquefied petroleum gas. 16. A method according to any one of claims 1 to 15, characterized in that makes a booster water vapor and / or oxygen between step a) and d) of said method. 17. Process according to any one of Claims 1 to 16, characterized in that the tri-reforming reactor (1009) comprises at least one supported catalyst comprising an active phase comprising at least one metal element in oxide form or in metallic form. selected from groups VIIIB, IB, MB, alone or in admixture.