EP1508609A1 - Method for treating the middle fraction of a steam cracking effluent - Google Patents

Abstract

The process involves the separation of effluents from a catalytic cracking unit to obtain an intermediate fraction comprising a 5 - 9C fraction with a final boiling point less than 310[deg]C, which is subjected to hydrotreatments. The process comprises the stages (1) separation of the effluents to produce an intermediate fraction consisting mainly of a pyrolytic petrol with mostly 5C+ compounds an with a final boiling point less than 310[deg]C; (2) a primary hydrotreatment of the intermediate fraction; (3) fractionation of the effluent from the primary unit to produce a C5 cut and a C6+ cut; (4) fractionation of the C6+ cut to produce a 6 - 8C and C9+ cut; (5) a second hydrotreatment of the 6 - 8C cut to produce a hydrotreated 6 - 8C cut; (6) a third hydrotreatment of the C9+ cut, and optionally part of the 6 - 8C or hydrotreated 6 - 8C cut, to saturate at least 20% vol of the aromatics, using the escess hydrogen produced in the cracking unit. The final product obtained from the third hydrotreatment consists of solvents comprising less than 5% aromatics, kerosene, gasoil or domestic fuel cuts, or bases for the preparation of these products. An independent claim is also included for the final product obtained from the process.

Description

The present invention relates to a method for treating effluents from steam cracking of hydrocarbons. The steam cracking process is a process well-known petrochemicals, at the base of the production of the major intermediaries, particularly ethylene and propylene. Steam cracking produces, in addition to ethylene and propylene, significant quantities of co-products less recoverable, including aromatic pyrolysis gasoline, which is noticeable amount when you love propane or butane, and more when you crack naphtha or diesel.

The crude pyrolysis gasoline is often hydrotreated in two stages, with a intermediate fractionation to typically produce a C5 cut, a cut C6-C7-C8, and a C9 + cut.

By definition, a Cn cut is a cut composed essentially of hydrocarbons with n carbon atoms, and a Cn + cut is a section composed essentially of hydrocarbons having at least n carbon atoms.

• Soit on produit une coupe C6-C8 utilisée comme base de production d'aromatiques, et l'on a évidemment intérêt à préserver au maximum ces aromatiques,
• Soit on produit une coupe C6-C8, ou C5+, ou C6+ utilisée comme base d'essence, et il faut également préserver au maximum les aromatiques pour maximiser l'indice d'octane de l'essence.

The C5 cut is generally recycled to the steam cracker, the C6-C7-C8 cut, subsequently denoted C6-C8 (essentially composed of hydrocarbons with 6, 7 or 8 carbon atoms), used as a base for producing aromatics , and the C9 + cut used as a motor gasoline base. The entire C5 + or C6 + cut can also be used as a motor gasoline base, after having undergone a first hydrolysis of dedienization (selective hydrogenation). Typically, the hydrotreatments carried out on the fractions that may contain aromatics are made by preserving these aromatics as much as possible, the content of which is hardly modified. This technical philosophy results from the following facts:

• Either a C6-C8 cut is used as a base for the production of aromatics, and it is obviously advantageous to preserve these aromatics as much as possible.
• Either a C6-C8, or C5 +, or C6 + cut is used as a gasoline base, and it is also necessary to preserve the aromatics as much as possible in order to maximize the octane number of the gasoline.

Pyrolysis gasolines also typically have sulfur contents especially that of the C9 + cut, which is often of the order of 300 ppm weight. However, this sulfur content becomes incompatible with the evolution of the standards the maximum sulfur content of gasoline which tends to fall below 50 ppm, or 30 ppm or even 10 ppm weight.

The high sulfur content of pyrolysis gasoline is therefore a problem delicate technique to the steam cracking industry, for the valorization of these species.

1) Modifier les deux unités d'hydrotraitement existantes pour accroítre fortement la désulfuration. Des catalyseurs de désulfuration adéquats existent, les plus utilisés étant principalement des catalyseurs à base de nickel et molybdène, ou nickel et tungstène ou cobalt et molybdène, sur support alumine.

2) rajouter une troisième unité de désulfuration finale sur la fraction vendue comme essence. Ces deux voies conduisent à des investissements supplémentaires notables, sans gain sur la valorisation des produits, qui restent des bases d'essence de qualité assez médiocre. De plus, la désulfuration poussée s'accompagne d'une réduction limitée de la teneur en aromatiques, que l'on cherche à minimiser, mais qui reste défavorable pour l'indice d'octane de l'essence, et donc sa valorisation. Elle s'accompagne également d'une certaine réduction des oléfines, également défavorable pour l'indice d'octane de l'essence, et donc sa valorisation. La désulfuration poussée conduira donc à une perte de valorisation, par rapport à la situation actuelle.

3) céder la fraction essence telle que produite à une raffinerie de pétrole qui réalisera une désulfuration finale. Cette option conduit à une moins value importante sur le prix de l'essence ainsi cédée.

Three ways are currently being implemented or envisaged to deal with this situation, in particular for existing steam crackers:

1) Modify the two existing hydrotreating units to greatly increase desulphurization. Suitable desulphurisation catalysts exist, the most commonly used catalysts being mainly based on nickel and molybdenum, or nickel and tungsten or cobalt and molybdenum, supported on alumina.

2) add a third unit of final desulfurization on the fraction sold as gasoline. These two routes lead to significant additional investments, with no gain on the valuation of products, which remain fuel bases of rather poor quality. In addition, the extensive desulphurization is accompanied by a limited reduction of the aromatics content, which is sought to minimize, but which remains unfavorable for the octane number of gasoline, and therefore its valuation. It is also accompanied by a certain reduction in olefins, which is also unfavorable for the octane number of gasoline, and therefore its recovery. The high level of desulphurization will therefore lead to a loss of valuation, compared to the current situation.

3) yield the gasoline fraction as produced to an oil refinery that will achieve final desulphurization. This option leads to a significant reduction in the price of gasoline thus sold.

The object of the invention is to find a technically simple solution to the problem above, by requiring a minimum or no modification of the existing units, and allowing a high valuation of products.

a) la séparation de ces effluents pour produire notamment une fraction intermédiaire comprenant la plus grande partie au moins (c'est à dire 50% poids au moins) de l'essence de pyrolyse comprise dans ces effluents, et composée dans sa plus grande partie au moins par des hydrocarbures ayant au moins 5 atomes de carbone et un point d'ébullition final inférieur à 310 °C,

b) un premier hydrotraitement de cette fraction intermédiaire dans une unité HD1,

c) un fractionnement d'une partie au moins de l'effluent de l'unité HD1, pour produire une coupe C5 et une coupe C6+,

d) un fractionnement d'une partie au moins de la coupe C6+, pour produire une coupe C6-C8 et une coupe C9+,

e) un deuxième hydrotraitement d'une partie au moins de la coupe C6-C8 dans une unité HD2, pour produire une coupe C6-C8 hydrotraitée,

f) un troisième hydrotraitement d'une charge comprenant une partie au moins de la coupe C9+, et optionnellement une partie au moins de la coupe C6-C8 ou de la coupe C6-C8 hydrotraitée, dans une unité HD3 pour saturer au moins 20%, généralement au moins 25%, et typiquement au moins 35% volume des aromatiques compris dans la charge de l'unité HD3 avec, en partie ou de préférence en totalité, de l'hydrogène excédentaire produit par ledit vapocraquage. On peut alors produire en sortie de HD3 au moins un produit final du groupe constitué par: les solvants comprenant moins de 5% volume d'aromatiques, les coupes kérosène, ou gazole, ou fuel domestique, ou les bases pour la fabrication de ces produits. Les produits de ce groupe ont une valorisation élevée, qui n'est pas liée au maintien d'une teneur élevée en aromatiques ni en oléfines, contrairement à l'essence pour laquelle l'indice d'octane, lié à la teneur en aromatiques et oléfines, est un paramètre essentiel. Il est donc possible d'obtenir des produits de haute valeur, sans pénalité pour la réduction d'aromatiques et d'oléfines, quel que soit le niveau de désulfuration recherché. Au contraire, la réduction notamment de la teneur en aromatiques augmente la qualité des produits considérés (pureté des solvants, point de fumée du kérosène, indice de cétane des gazoles, aptitude à la combustion du fuel domestique).

To this end, the invention proposes a process for treating hydrocarbon steam cracking effluents, comprising:

a) the separation of these effluents to produce in particular an intermediate fraction comprising at least the major part (ie at least 50% by weight) of the pyrolysis gasoline included in these effluents, and composed for the most part at least by hydrocarbons having at least 5 carbon atoms and a final boiling point of less than 310 ° C,

b) a first hydrotreatment of this intermediate fraction in an HD1 unit,

c) a fractionation of at least a portion of the effluent of the unit HD1, to produce a C5 cut and a C6 + cut,

d) a fractionation of at least a portion of the C6 + cut, to produce a C6-C8 cut and a C9 + cut,

e) a second hydrotreatment of at least a portion of the C6-C8 cut in a unit HD2, to produce a hydrotreated C6-C8 cut,

f) a third hydrotreatment of a feed comprising at least a portion of the C9 + cut, and optionally at least a portion of the C6-C8 cut or hydrotreated C6-C8 cut, in an HD3 unit to saturate at least 20% , generally at least 25%, and typically at least 35% of the aromatics included in the feed of the unit HD3 with, in part or preferably all of the excess hydrogen produced by said steam-cracking. It is then possible to produce at the output of HD3 at least one final product from the group consisting of: solvents comprising less than 5% volume of aromatics, kerosene or diesel cuts, or heating oil, or bases for the manufacture of these products . The products in this group have a high valuation, which is not related to the maintenance of a high content of aromatics and olefins, unlike gasoline for which the octane number, related to the content of aromatics and olefins, is an essential parameter. It is therefore possible to obtain products of high value, without penalty for the reduction of aromatics and olefins, whatever the desired level of desulphurisation. On the contrary, the reduction in particular of the aromatics content increases the quality of the products under consideration (purity of the solvents, kerosene smoke point, cetane number of diesel fuels, combustion capacity of domestic fuel oil).

Preferably, the charge rate of the unit HD3 is limited, and / or the degree of saturation of aromatics in this unit, so that hydrogen consumption in HD3 is less than or equal to the amount of excess hydrogen produced by steam cracking, and that the hydrogen feeding HD3 (and preferably hydrogen feeding HD1, HD2 and HD3) is provided in full by this hydrogen surplus.

The invention therefore makes it possible to move away from the conventional technical philosophy of preserving the aromatics of the pyrolysis gasoline, to use Excess hydrogen from the steam cracker to change the spectrum of co-products steam cracker, and produce one or more new products for recovery high, which are no longer gasoline, and which remove the technical problem related to the amount of sulfur contained in the pyrolysis gasoline.

It is possible in particular to produce a solvent or a solvent base at the outlet of HD3. having not less than 60% by volume of naphthenes, not more than 5%, and preferably not more than 3% % of aromatics, and at most 10 ppm by weight of sulfur. We can also produce at the output of HD3 a kerosene or a light diesel fuel or a kerosene base or diesel, having less than 30%, or less than 20%, of aromatics, not more than 300 ppm weight of sulfur, and a distillation interval (ASTM) included inside of the range [120 ° C-310 ° C]. It is also possible to produce a domestic fuel oil in aromatics generally less than 50% by volume, or 30% by volume or even at 20% volume, with a sulfur content typically less than 300 ppm by weight, ASTM distillation interval typically within the range [120 ° C-310 ° C].

Preferably, the unit HD3 uses at least one catalyst comprising platinum and palladium deposited on a support. It has been found that such catalysts, used in the refinery, but not in the steam cracking industry, effective and compatible with the specific compounds present in the species pyrolysis.

Particularly advantageously, the unit HD3 uses at least one catalyst comprising 0.1 to 0.30% by weight of platinum, and 0.2 to 1% and preferably 0.4 at 0.7% by weight of palladium, deposited on a fluorinated alumina, comprising from 1 to 5% by weight of fluorine. This catalyst makes it possible to operate at high speeds hourly space velocities (VVH), including between 1 and 6 on these charges pyrolysis species. One can also optionally use, in bed of guard, or first reactor in the same unit HD3, a conventional catalyst, by LD 145, a NiMo catalyst (nickel / molybdenum) marketed by the Axens company. Finally, we can, especially when we are not looking for production of de-aromatised solvents, use hydrorefining catalysts in HD3 such as Ni-Mo, Co-Mo (for example type CoMo HR406, HR306C (marketed by Axens) with a guard bed of NiMo type catalyst LD145 (marketed by Axens). We can also use in a guard bed a catalyst at least partially saturating the olefins, for example for example a CoMo hydrodesulfurization catalyst on alumina. We can saturate for example at least 70%, or at least 90%, or at least 95% weight or plus olefins present in the charge of HD3. Residual content of olefins products derived from HD3, according to the invention, in particular solvent, or kerosene, or gas oil, or heating oil, or the base of any of these products, may be reduced to less than 5% by weight, or preferably less than 1% by weight, or very preferred less than 0.5% by weight, or even substantially zero.

According to a variant of the invention, explained below, the intermediate fraction produced in step a), and the charge of the HD3 unit are not limited to the essence of pyrolysis, and may have an ASTM endpoint between 230 and 310 ° C, and preferably between 250 and 280 ° C.

La figure 1 représente la partie principale d'une installation selon le procédé de l'invention, cette partie principale représentant l'installation de traitement d'essence de pyrolyse, ou de la fraction intermédiaire comprenant de l'essence de pyrolyse. La partie amont permettant le fractionnement primaire des effluents de vapocraquage n'est pas représentée. La figure 1 est par ailleurs une représentation simplifiée, comprenant des unités d'hydrotraitement qui n'ont pas été détaillées (notamment les recyclages éventuels de charge hydrotraitée, et les appoints d'hydrogène ne sont pas représentés).

La figure 2 représente une représentation plus détaillée d'une unité d'hydrotraitement de l'installation de la figure 1.

The invention will be explained more specifically in the description of FIGS. 1 and 2.

FIG. 1 represents the main part of an installation according to the process of the invention, this main part representing the pyrolysis gasoline processing plant, or the intermediate fraction comprising pyrolysis gasoline. The upstream part allowing the primary fractionation of the steam cracking effluents is not represented. FIG. 1 is also a simplified representation, comprising hydrotreatment units that have not been detailed (notably the possible recycling of hydrotreated feedstock, and hydrogen additions are not shown).

FIG. 2 represents a more detailed representation of a hydrotreatment unit of the installation of FIG. 1.

According to FIG. 1, the charge, also called intermediate fraction, according to the invention is fed by line 1 and treated in a hydrotreatment unit HD1 to realize in particular a preliminary dediénisation. The dedienized charge circulates through line 2 and is fractionated in a distillation column 3 into a fraction C5 flowing through line 4, typically recycled to steam cracking, and a C6 + section flowing through line 5. This C6 + cut is split in the column 6 in a C6-C8 fraction (C6-C7-C8), feeding via line 7 a second hydrotreatment unit HD2 which carries out a thorough desulfurization of the C6-C8 cut, and a deep conversion of olefins. For example, we can use a type of catalyst LD 265 marketed by the company Axens. The C6-C8 cut treated, evacuated via line 9 may have for example less than 1 ppm weight of sulfur and less than 50 ppm by weight of olefins. We generally seek to minimize the loss of aromatics in the unit HD2, to maximize their recovery higher. The C9 + cut coming out of the bottom of the column 6 by the line 8 then feeds a third hydrotreatment unit HD3 to produce a desulphurized section at low aromatic content evacuated by line 11. The cut produced is according to the invention typically is a kerosene or a diesel fuel (or a kerosene base or diesel), the aromatic content of which is less than 30% by volume, generally less than 20% by volume, either a solvent or a solvent base, Aromatic content is less than 5% volume. When the cut produced is a solvent (or solvent base), this may optionally include substantial amounts of C6-C8 hydrocarbons also fed to the HD3 unit via the line 10. The cut produced at the output of HD3 can also be a fuel domestic fuel oil or base, of aromatic content typically less than 50% volume, generally less than 30% volume, or even less than 20% volume.

According to FIG. 2, representing in more detail the hydrotreating unit HD3, the C9 + cut fed by line 8 is added with a recycled fraction of hydrotreated product, circulating in line 8f, and a stream of recycle gas rich in hydrogen, circulating in line 8c. This stream includes hydrogen booster powered by a line not shown. The overall current from the mixture then feeds the hydrotreating reactor R3. The effluent of R3 circulates in the line 8a or it is cooled by means not shown, and enters the balloon separator S3. The gas separated in S3 is mainly recycled by line 8c, a fraction being purged by the line 8d. The liquid product from S3 circulates in the line 8b, to be partially recycled by line 8e and partially evacuated by the line 11. The hydrotreated product discharged through line 11, which can typically be a solvent, or a cut or base of kerosene or diesel fuel or domestic fuel, is typically stabilized (in means not shown) prior to storage, for remove light fractions and H2S. Some of the recycled liquid in the line 8e is injected interbed in the reactor R3, as a quenching liquid.

According to the invention, the unit HD3 comprises at least one catalyst enabling to achieve very efficiently, in a single unit the specifications in sulfur and sought after aromatics.

According to one of the variants of the invention, the catalyst of the unit HD3 comprises in particular at least one bed of platinum / palladium catalyst on a support of the type fluorinated alumina. The support can be composed essentially of gamma-alumina and comprise from 1 to 10, preferably from 1 to 7, and very preferably from 3 to and 5% by weight of fluorine. The unit HD3 can therefore include such a catalyst on fluorinated alumina support arranged in one or more beds and optionally first bed, or guard bed with a conventional catalyst of Ni / Mo type acting in pretreatment.

This platinum / palladium catalyst may preferably comprise between 0.10 and 0.30%, preferably between 0.15 and 0.30%, and very preferably between 0.20 and 0.30% by weight of platinum, as well as usually from 0.2 to 1.0%, and preferably between 0.4 and 0.7% by weight of palladium. The molar ratio of palladium to platinum can in particular be between 3 and 8, preferably between 3.5 and 6.

According to another variant of the invention, the end point of the cut treated is modified, and increased compared to a conventional cut of pyrolysis gasoline, the end point is often between 205 and 220 ° C. The end point of the cut treated in this variant of the invention may be higher because the C9 + cut is then typically intended to be transformed into products other than gasoline. Indeed, some solvents, as well as fractions kerosene, diesel or fuel oil, may have final distillation points (ASTM distillation) above 220 ° C.

The fraction treated can therefore be a long fraction going beyond gasoline, having a final distillation point greater than 220 ° C, for example between 230 and 310 ° C, especially between 240 and 280 ° C. This can be achieved by modifying the fractionation of steam cracking effluents in primary distillation, the cutting point between the petrol fraction and the fuel fraction of pyrolysis, to leave fractions boiling above about 220 ° C in the so-called "gasoline" fraction, which becomes an intermediate fraction "gasoline + middle distillate".

We can reduce from 5 to 50%, and often from 10 to 40% the amount of fuel oil pyrolysis produced. This is interesting when you crack naphtha or condensate, and even more when cracking heavier loads.

• un solvant (ou une base de solvant), d'intervalle de distillation ASTM typiquement compris à l'intérieur, environ, de l'intervalle [65°C-250°C], ou de l'intervalle [90°C-240°C] ou de l'intervalle [130°C-230°C], de taux d'aromatiques très bas, généralement inférieur à 5% volume, ou à 3% volume ou même à 1% volume, de teneur en soufre typiquement inférieure à 10 ppm poids, voire à 5 ppm ou même à 1 ppm.
• un kérosène ou un gazole (ou une base de kérosène ou de gazole), d'intervalle de distillation ASTM typiquement compris à l'intérieur de l'intervalle [120°C-310°C], ou de l'intervalle [130°C-280°C], ou de l'intervalle [140°C-250°C], de taux d'aromatiques très bas, généralement inférieur à 30% volume, ou même à 20% volume, de teneur en soufre typiquement inférieure à 300 ppm poids, notamment inférieure à 50 ppm poids, voire inférieure à 10 ppm poids,
• un fuel domestique (ou une base de fuel domestique), d'intervalle de distillation ASTM typiquement compris à l'intérieur de l'intervalle [120°C-310°C], ou de l'intervalle [130°C-280°C], ou de l'intervalle [140°C-250°C], de taux d'aromatiques généralement inférieur à 50% volume, ou à 30% volume ou même à 20% volume, de teneur en soufre typiquement inférieure à 300 ppm poids, notamment inférieure à 50 ppm poids.

The method according to the invention therefore makes it possible to produce in particular one or more of the following products:

• a solvent (or a solvent base) of ASTM distillation range typically within about the range [65 ° C-250 ° C], or the range [90 ° C-240 ° C] or the range [130 ° C-230 ° C], very low aromatics, generally less than 5% volume, or 3% volume or even 1% volume, typically sulfur content less than 10 ppm by weight, or even 5 ppm or even 1 ppm.
• a kerosene or a gas oil (or a kerosene or diesel base) of ASTM distillation range typically within the range [120 ° C-310 ° C], or the range [130 ° C-280 ° C], or the range [140 ° C-250 ° C], very low aromatics, generally less than 30% volume, or even 20% volume, typically lower sulfur content at 300 ppm weight, especially less than 50 ppm by weight, or even less than 10 ppm by weight,
• a domestic fuel (or a heating oil base) of ASTM distillation range typically within the range [120 ° C-310 ° C], or the range [130 ° C-280 ° C], or the range [140 ° C-250 ° C], of aromatics content generally less than 50% volume, or 30% volume or even 20% volume, sulfur content typically less than 300 ppm weight, especially less than 50 ppm by weight.

These products are intended for explicit uses and are therefore not bases of gasoline, nor products intended to be sold for of gasoline, for example by additional desulfurization. This production new investment requires, but allows new opportunities and important, for high recovery products, for which a reduction significant content of aromatics and olefins does not present disadvantages, and is even desirable, and can typically be achieved through hydrogen surplus steam cracker.

EXAMPLES

The following examples explain, in a non-limiting way, catalysts and operating conditions that can be used in the process according to the invention:

Example 1 Treated load:

Steam cracking effluents of naphtha are fractionated in a plant of treatment of these effluents, comprising a primary distillation, to produce including a pyrolysis gasoline cut, including the C5 cut and heavier hydrocarbons to an ASTM endpoint of 210 ° C.

Intervalle de distillation ASTM : 20 - 219 °C

Densité : 0,82

Teneur en soufre : 400 ppm poids

Composition (%poids) :

mono-aromatiques: 65%

di-aromatiques: 1%

di-oléfines (composés dièniques): 15%

mono-oléfines: 6%

composés saturés: solde.

This section is the "intermediate fraction" of the process according to the invention, and has the following characteristics:

ASTM distillation interval: 20 - 219 ° C

Density: 0.82

Sulfur content: 400 ppm by weight

Composition (% weight):

mono-aromatic: 65%

di-aromatic: 1%

di-olefins (dienic compounds): 15%

mono-olefins: 6%

saturated compounds: balance.

This pyrolysis gasoline charge is treated according to the process scheme described in Figure 1. The feed fed to the hydrotreating unit HD3 is the C9 + feed, without C6 / C8 cutting from HD2, line 10 not being used.

Catalyst and operating conditions of the first hydrotreatment unit HD1:

Catalyst: palladium on alumina catalyst, comprising 0.30% by weight of palladium.

Température de sortie réacteur: 110°C

Pression sortie réacteur: 3,0 MPa

VVH (vitesse spatiale horaire): 2,4 h^-1

The catalyst is placed in two beds in a reactor, with a device for injecting a fluid intended in particular to cool the reaction mixture between the two beds.

Reactor outlet temperature: 110 ° C

Reactor outlet pressure: 3.0 MPa

VVH (hourly space velocity): 2.4 h ^-1

Hydrogen content (total reactor inlet gas): 90 Nm ³ of hydrogen / m ³ of feedstock. The unused gas is separated and sent as an add-on to the second unit HD2.

Recycle rate of the load: 2 (we recycle 2 volumes of hydrotreated product leaving of HD1 for a fresh charge volume fed to HD1, to limit the increase in temperature due to the exothermicity of the reaction).

Catalyst and operating conditions of the second hydrotreating unit HD2:

Température de sortie réacteur : 300 °C

Pression sortie réacteur 2,5 MPa

VVH (vitesse spatiale horaire): 2 h-¹

Catalyst: 2 catalyst beds are used. The first bed contains a catalyst of the Ni / Mo type on alumina: LD 145, marketed by AXENS. The second bed contains a catalyst of Co / Mo type on alumina: HR 306 C, sold by AXENS.

Reactor outlet temperature: 300 ° C

2.5 MPa reactor outlet pressure

VVH (hourly space velocity): 2 hr ^-1

Additional hydrogen content: 40 Nm ³ / m ³ load, hydrogen recycle rate 400 Nm ³ / m ³ gas No intermediate cooling is performed.

Catalyst and operating conditions of the third hydrotreatment unit HD3:

La charge de HD3 a la composition suivante:

Intervalle de distillation ASTM : 145 - 218 °C

Densité : 0,9

Teneur en soufre : 500 ppm poids

Composition : 53 % poids d'aromatiques dont 3 % de diaromatiques, 35% d'oléfines ,le reste étant des composés saturés.

Catalyseur : de type platine/palladium sur alumine fluorée, contenant en % poids: 0,2% de platine; 0,4% de palladium; 1,1% de chlore; 4,0% de fluor.

Advanced treatment of the HD3 feed is carried out to obtain in a single step a cut with a very low aromatic content, having the specifications of a commercial solvent.

The charge of HD3 has the following composition:

Distillation range ASTM: 145 - 218 ° C

Density: 0.9

Sulfur content: 500 ppm

Composition: 53% by weight of aromatics including 3% of diaromatics, 35% of olefins, the rest being saturated compounds.

Catalyst: platinum / palladium on fluorinated alumina, containing% by weight: 0.2% platinum; 0.4% palladium; 1.1% chlorine; 4.0% of fluorine.

Température d'entrée du réacteur : 290°C,

Température de sortie du réacteur : 330 °C,

Pression sortie réacteur : 4,0 MPa

VVH: 2 h^-1

Methods for preparing platinum / palladium catalysts on fluorinated alumina are described in European Patent Application EP 1 099 477 A1.

Reactor inlet temperature: 290 ° C,

Reactor outlet temperature: 330 ° C,

Reactor outlet pressure: 4.0 MPa

VVH: 2 h ^-1

Recycling hydrogen content including make-up hydrogen (hydrogen-rich total gas: inlet + quench): 400 Nm ³ / m ³ of charge of unit HD3.

Recycling rate of the unit: 5 (recycling of liquid effluent in mass ratio by relation to the charge). 90% of the recycling is mixed with the load, and 10% is injected in catalytic inter-beds in order to adjust the thermal profile. Recycling liquid is indeed required by the heat released during hydrogenation.

On obtient un solvant de teneur en aromatiques égale à 5% volume, et d'intervalle de distillation: 143 - 208 °C.

Teneur en soufre du solvant : <10 ppm poids.

The results after hydrotreating in unit HD3 are as follows:

A solvent having an aromatic content of 5% by volume and a distillation range of 143-208 ° C. is obtained.

Sulfur content of the solvent: <10 ppm by weight.

Example 2

Example 1 is repeated but with a long charge, end point ASTM 250 ° C. This is achieved by modifying the operating parameters of the effluent treatment of steam cracking, so that the fractionation leaves with the pyrolysis gasoline fractions a little heavier than gasoline.

In particular, it is possible to use a slightly higher temperature in the tower of primary fractionation and / or increase the stripping.

Température d'entrée du réacteur : 290 °C,

Température de sortie du réacteur : 330 °C,

Pression sortie réacteur : 4,0 MPa

VVH : 4 h^-1

We can then increase the C9 + fraction feeding HD3, and use, with the same catalyst, milder conditions than in Example 1, in particular:

Reactor inlet temperature: 290 ° C,

Reactor outlet temperature: 330 ° C,

Reactor outlet pressure: 4.0 MPa

VVH: 4 h ^-1

Recycle hydrogen content including make-up hydrogen (hydrogen-rich total gas: inlet + quench): 400 Nm ³ / m ³ of charge of unit HD3.

Recycling rate (liquid effluent recycling with the load and between beds to adjust the thermal profile): 3 en masse, of which 0.45 in inter-beds.

Teneur en aromatiques du produit obtenu: 19,5% volume.

Intervalle de distillation ASTM: 144 - 241 °C

Teneur en soufre : <10 ppm poids.

The results after hydrotreating in unit HD3 are as follows:

Aromatic content of the product obtained: 19.5% volume.

ASTM Distillation Interval: 144 - 241 ° C

Sulfur content: <10 ppm by weight.

It is thus possible to obtain a base of kerosene, diesel or heating oil, and reduce the production of pyrolysis fuel.

The invention may also use other hydrotreatment catalysts, and / or other operating conditions, or other undescribed characteristics but obvious to the skilled person.

Claims (10)

A process for treating hydrocarbon steam cracking effluents, comprising: a) the separation of these effluents to produce an intermediate fraction comprising at least the major part of the pyrolysis gasoline contained in these effluents, and composed for the most part of compounds having at least 5 carbon atoms and a point d final boiling below 310 ° C, b) a first hydrotreatment of this intermediate fraction in an HD1 unit, c) a fractionation of at least a portion of the effluent of the unit HD1, to produce a C5 cut and a C6 + cut, d) a fractionation of at least a portion of the C6 + cut, to produce a C6-C8 cut and a C9 + cut, e) a second hydrotreatment of at least a portion of the C6-C8 cut in a unit HD2, to produce a hydrotreated C6-C8 cut, f) a third hydrotreatment of a feed comprising at least a portion of the C9 + cut, and optionally at least a portion of the C6-C8 cut or hydrotreated C6-C8 cut, in an HD3 unit to saturate at least 20% the volume of aromatics included in the feed of unit HD3 with, in part or in full, excess hydrogen produced by said steam-cracking, and producing at the output of HD3 at least one final product from the group consisting of solvents comprising less than 5% of aromatics, kerosene or diesel cuts, or domestic fuel, or bases for the manufacture of these products. The method of claim 1 wherein the load flow rate of the unit is limited HD3, and / or the degree of saturation of the aromatics in this unit, so that the hydrogen consumption in HD3 is less than or equal to the amount excess hydrogen produced by steam cracking, and that hydrogen feeding HD3 is provided in full by this excess hydrogen. Process according to one of Claims 1 and 2, in which the output of HD3 a solvent or a solvent base having at least 60% by volume of naphthenes, not more than 5% by volume of aromatics, and not more than 10 ppm by weight of sulfur. Process according to one of Claims 1 and 2, in which the output of HD3 a kerosene or a diesel or a base of kerosene or diesel having less 30% by volume of aromatics, not more than 300 ppm by weight of sulfur, and a range of ASTM distillation within the range [120 ° C-310 ° C]. Process according to one of Claims 1 and 2, in which the output of HD3 a domestic fuel oil or a heating oil base with less than 50% volume of aromatics, not more than 300 ppm by weight of sulfur, and a range of ASTM distillation within the range [120 ° C-310 ° C]. Method according to one of claims 1 to 6, wherein the unit HD3 uses the minus a catalyst comprising platinum and palladium deposited on a support. The method of claim 6, wherein the HD3 unit uses at least one catalyst comprising from 0.10 to 0.30% by weight of platinum and from 0.2 to 1% by weight of palladium deposited on a fluorinated alumina, comprising from 1 to 5% by weight of fluorine. Process according to one of Claims 1 to 6, in which the intermediate fraction produced in step a), and the load of the HD3 unit have an ASTM endpoint included between 230 and 310 ° C. Method according to one of the preceding claims, wherein said final product has an olefin content of less than 1% by weight. Final product of the group consisting of solvents comprising less than 5% aromatics, kerosene, diesel or domestic fuel oil, or for the manufacture of these products, this final product having been obtained by the process according to one of claims 1 to 9.

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