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    • 专利摘要:
    The present invention describes a process for producing high octane gasoline by isomerization of a light naphtha fraction comprising two separation stages located downstream of the reaction stage which make it possible to improve the energy efficiency of said process.
    公开号:FR3020374A1
    申请号:FR1453841
    申请日:2014-04-29
    公开日:2015-10-30
    发明作者:Jerome Pigourier；Isabelle Prevost；Laurent Watripont；Pierre-Yves Martin
    申请人:Axens SA；
    IPC主号:
    专利说明:

    [0001] FIELD OF THE INVENTION The invention relates to the field of producing high octane gasoline. Naphthas from the atmospheric distillation of petroleum usually consist mainly of hydrocarbons comprising from 5 to 10 carbon atoms (sections 05-010). These naphthas are usually split into a light Naphtha (cut 05-06) and heavy Napa (07010) cut. Heavy naphtha cutting is usually sent in a catalytic reforming process. The light naphtha fraction, which essentially comprises hydrocarbons having 5 or 6 carbon atoms (05 and 06) but may additionally comprise hydrocarbons with 4 or 7 or even 8 carbon atoms (04, 07, 08), is generally isomerized in order to increase the proportion of branched hydrocarbons which have a higher octane number than linear hydrocarbons. The isomerate and the reformate obtained are then sent to the gasoline pool with other bases or additives (catalytic cracking gasoline, alkylates, etc.). Given the gradual decrease in the maximum content of aromatic compounds allowed in gasolines (less than 35% volume in the Euro 5 specification for example), and significant aromatics contents of catalytic reforming gasolines, the isomerate which do not contain of aromatic compounds, are becoming increasingly important in the gasoline pool. It is therefore important to have efficient isomerization processes, both in terms of yield and octane number. These processes must also be economically attractive in terms of level of investment and operating costs. It is therefore important to optimize the operation of both the isomerization reaction section and the fractionation sections of the feedstock or effluent. EXAMINATION OF THE PRIOR ART Patent FR 2,828,205 describes a process for isomerizing a cut 05-08 in which said cut is fractionated into a section 05-06 and a section 07-08 which are each isomerized separately in specific conditions for each cut.
    [0002] U.S. Patent 2,905,619 discloses an isomerization process in which the C5-C6 cut from a gasoline cut is separated into different fractions which are isomerized in two isomerization sections operated under specific conditions. US Pat. No. 7,223,898 describes an isomerization process comprising in its fractionation section only a stabilization or stripping and a deisohexanizer producing 2 to 4 different slices. These process schemes do not include deisopentaninser (DiP) and / or depentanizer (DP). GB Patent 1,056,517 describes a process for isomerizing a C5-C6 cut comprising a deisopentanizer (DiP), isomerization of the isopentane-depleted fraction (150M), and separation of the isomerized effluent to recover n-pentane. (DP) which is recycled with the feedstock at the inlet of the deisopentanizer and a branched hydrocarbon separation (deisohexanizer, DiH) for recovering high octane branched C 6 hydrocarbons, the balance being recycled to the reactor of isomerization. This diagram DiP / ISOM / DP / DiH corresponds to Figure 1 (according to the prior art) of this application. SUMMARY DESCRIPTION OF THE FIGURES FIG. 1 represents a diagram of the process according to the closest prior art. This diagram shows the de-isopentanizer column [3], the isomerization reaction section [1], the stabilization column [2], the de-pentanizer column [4] and the de-isohexanizer column [5]. ]. These numbers are kept in the figures according to the invention to designate the same equipment. FIG. 2 represents the method according to the invention in which the block denoted (3 + 4) represents the first separation step, and the block [5] the second separation step. FIG. 3 represents a first variant of the method according to the invention in which the columns [3] and [4] are connected in series. FIG. 4 represents a second variant of the method according to the invention in which the columns [3] and [4] are grouped in a single column [3] allowing a fractionation into 3 sections.
    [0003] FIG. 5 represents a third variant of the method according to the invention in which the columns [3] and [4] are in the reverse order, that is to say that it is the top flow of the column [4] which feeds the column [3]. FIG. 6 represents an example of thermal integration between the condenser of a first column and the reboiler of another column. Equipment is marked with numbers in square brackets and flows by numbers between 10 parentheses. The numbers of the conduits conveying the flows are the same as those of the flows conveyed. SUMMARY DESCRIPTION OF THE INVENTION The invention relates to the field of producing high octane gasoline. Naphthas from the atmospheric distillation of petroleum usually consist mainly of hydrocarbons comprising from 5 to 10 carbon atoms (cut 05-010). The process according to the present invention processes a filler of the light naphtha type and preferentially a cut 05 and 06 (cut of hydrocarbons comprising 5 or 6 carbon atoms), and aims at maximizing the branched molecules relative to the linear (or normal) molecules. . However, these fillers may optionally comprise other hydrocarbons, for example hydrocarbons comprising 4 or 7 or even 8 carbon atoms (sections 04, 07, 08). However, it will preferably be sought to limit the amount of these hydrocarbons via, for example, a prior separation. As regards the hydrocarbons at 04, they can also be largely separated in the stabilization column 2. The process according to the invention is more particularly applicable to fillers whose iso-pentane content is less than and preferably less than at 20%.
    [0004] The process according to the invention comprises an isomerization section [1], a stabilization of the isomerized effluent 2] (denoted STAB), a separation of iso-pentane (denoted DiP), a separation of n-pentane ( denoted by DP), (represented by block 3q4) and a separation of the remaining products, in particular compounds branched at 06 (denoted DiH) (represented by block 5), according to the ISOM / STAB / DiP / DP / DiH sequence. In the process according to the invention, the separation of iso-pentane and n-pentane can also be carried out in the same column allowing a fractionation in 3 sections according to the ISOM / STAB / DiP / DiH sequence according to FIG. The process according to the invention is therefore distinguished from the process according to the prior art (FIG. 1) in that it comprises the successive separation of iso-pentane, n-pentane and branched compounds in the order of FIG. 3, or the simultaneous separation of n-pentane and iso-pentane in the same fractionation column according to FIG. 4, followed by the separation of the branched compounds at 06, or the separation of a section 05, then that of n-pentane and iso-pentane and that of the compounds branched at 06 according to FIG. 5. In the process according to the invention, said separations are all located downstream of the isomerization section [1], and more precisely downstream of the stabilization column [2], contrary to the processes of the prior art which have only one column of DiH (de-isohexanizer), or 3 fractionation columns, but with the DiP (de-isopentanizer) column located upstream of the isomerization section according to In a more precise manner, the present invention can be described as a process for the isomerization of a light naphtha, or preferentially a cut essentially 05-06, the said process comprising two stages of separation by distillation downstream of the isomerization step: a first distillation separation step (block 3q4) to separate the 5-carbon hydrocarbons from the heavier compounds sent to the second separation section [5]. This first separation step consists in producing the following 3 cuts: a) an iso-pentane enriched cut (15) which is a product of the process, b) an enriched n-pentane cut (16) which is recycled to the section reaction [1], and c) a heavier hydrocarbons enriched fraction than pentanes (17) which is directed to a second separation step [5], a second separation step [5] consisting of a separation column whose top and bottom products are products of the unit, namely a head stream (19) rich in 06 branched compounds, a bottom stream (18), and an intermediate cut (20) enriched in n-hexane , withdrawn at the side, which is recycled to the reaction section [1]. According to a first variant of the method according to the invention, represented by FIG. 3, the first separation step comprises two columns (3 and 4) arranged in series, that is to say that the de-isopentanizer bottom flow [3] feeds the de-pentanizer [4] as shown in FIG. 3. The isopentane stream (15) leaves the top of the column [3] and the hydrocarbon stream heavier than the pentanes (17) leaves at the bottom of the column [4] to feed the second fractionation step [5]. According to a second variant of the process according to the invention, represented by FIG. 4, the deisopentanizer and the depentanizer are combined into a single column allowing fractionation into 3 streams (denoted [3] in FIG. 4). The isopentane stream (15) exits at the top of the column [3], and the heavier hydrocarbon stream than the pentanes (17) leaves at the bottom of said column to feed the second fractionation step [5]. An intermediate stream stream 16) is recycled to the isomerization unit [1]. According to a third variant of the method according to the invention, represented by FIG. 5, the first separation step comprises the two columns [4] and 3] arranged in series in this order. That is to say that the flow (12) coming from the bottom of the stabilization column [2] feeds the de-pentanizer [4] from which the flow (21) which supplies the de-isopentanizer [3] . The bottom flow (17) of the depentanizer [4] feeds the de-isohexanizer [5]. The de-isopentanizer [3] produces the isopentane-rich stream (15) at the top and the normal pentane-rich stream (16), which is recycled to the isomerization [1]. According to other variants of the method, it is possible to use the available calories in the condenser of one of the columns [3], 4] or [5] to bring calories to the reboiler of one of the columns [3], [ 4] or [5]. For example, according to the variant illustrated in FIG. 6, it is possible to carry out a heat exchange between the de-pentanizer condenser [4] and the de-isopentanizer reboiler 3]. DETAILED DESCRIPTION OF THE INVENTION In the process according to the invention, the feedstock (10) generally consists of a light naphtha, preferentially a section 05-06, which may optionally contain heavier hydrocarbons. This feed is sent to a catalytic isomerization section [1], and the effluent (11) is fractionated in a fractionation section comprising the following steps: a stabilization [2] of the isomerized effluent which consists of separating at the top the lighter compounds than the pentanes (stream 13), and in the bottom a stabilized effluent (12) a first stage of separation by distillation (block 3q4) making it possible to separate the hydrocarbons with 5 carbon atoms from the heavier compounds sent towards the second separation section [5]. This first separation step consists in producing the following 3 cuts: a) an iso-pentane enriched cut (15) which is a first product of the process, b) an enriched n-pentane cut (16) which is recycled to the reaction section [1], and c) a hydrocarbon enriched fraction heavier than pentanes (17) which is directed to a second separation step [5], a second separation step [5] consisting of a separation column of which the top and bottom products are the products of the unit, namely a head stream (19) rich in 06 branched compounds, a bottom stream (18), and an intermediate cut (20) enriched in hexane, withdrawn at the side of the tank and recycled to the reaction section [1]. The iso-pentane-enriched cut (15) resulting from the first separation step as well as the head (19) and bottom (18) streams coming from the second separation step may optionally be subsequently mixed to provide the product or products. of the process.
    [0005] Description of Figure 1 According to the Prior Art: Fig. 1 shows the prior art process scheme which may be considered as closest to the present invention.
    [0006] The charge (10) is fed into a de-isopentanizer [3] which makes it possible to leave an isopentane stream (15) at the head. The bottom stream (14) of the de-isopentanizer [3] is sent to the isomerization reaction section [1] via line 14.
    [0007] The operating conditions of the reaction section [1] are chosen so as to promote the conversion of n-paraffins of low octane number (n-pentane, n-hexane) to iso-paraffins of higher octane numbers. (Isopentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane).
    [0008] The isomerization reaction section [1] is generally operated in the presence of an acid catalyst. The effluent of the isomerization section [1], once stabilized by separation of the light compounds (13) in the stabilization column [2], is directed via line (12) to a de-pentanizer [4]. The head stream (16) of the de-pentanizer [4] is recycled to the column [3] of the de-isopentanizer. The recycling of n-pentane, the de-pentanizer top product [4], via line 16 to the deisopentanizer [3], makes it possible to increase the proportion of isomerized n-pentane in the isomerization section [1], and therefore obtain higher octane products. The stream (16) can be recycled to the de-isopentanizer [3], either by introducing it alone directly into the de-isopentanizer [3] (according to FIG. 1), or in admixture with the filler 10 (not shown). ). The stream (16) also contains isopentane formed in the isomerization section which is separated in the de-isopentanizer [3]. The products (18) and (19) are respectively derived from the bottom and the head of the de-isohexanizer [5] which is fed by the bottom stream (17) from the de-pentanizer [4]. Isopentane is substantially absent from these two streams, being essentially present in stream 15.
    [0009] The process of FIG. 1 has the disadvantage of mixing a recycled isopentane enriched fluid via the pipe (16) with the charge (10) resulting from the pipe 10, either before its admission into the deisopentanizer [3], or, as represented in FIG. 1, inside said de-isopentanizer [3]. This mixture entails significant investment and operating costs since it is then necessary to separate this isopentane again during the isopentane / n-pentane separation of the deisopentanizer [3], and during the separation of n-pentane / compounds. heavier de-pentanizer [4]. This is particularly disadvantageous when the feed contains little iso-pentane. The method according to the invention makes it possible, among other things, to circumvent this problem.
    [0010] Description of the Figures According to the Invention (FIGS. 2, 3, 4 and 5) In its most general form, the process according to the invention comprises: a) a catalytic isomerization section [1] operated under the conditions described more far, b) a stabilization of the isomerized effluent (11) in a stabilization column [2] which consists in separating at the top the lighter compounds than the pentanes, and in bottom a stabilized effluent (12), C) a first separation step carried out in the distillation block (3q4) for separating the 5-carbon hydrocarbons from the heavier compounds sent to the second separation section. This first separation step consists, by the use of one or two fractionation columns, in producing the following 3 cuts: a cut enriched in iso-pentane which is a product of the process (15), a cut enriched in n-pentane (16) which is recycled to the reaction section [1] and - a cut enriched in hydrocarbons heavier than the pentanes (17), which is directed to the second separation step [5]. A second separation step [5] which can be carried out preferably by means of a deisohexanizer consisting of a separation column whose top product (19) is rich in 06 branched compounds, and an intermediate cut (20). enriched in n-hexane, withdrawn by lateral withdrawal, is recycled to the reaction section [1]. The iso-pentane enriched stream (14), bottom product (18) and overhead product (19) can be blended to form the product (s) of the process.
    [0011] The isomerization reaction is preferably carried out on a high-activity catalyst, such as for example a chlorinated alumina and platinum catalyst, operating at low temperature, for example between 100 and 300 ° C., preferably between 110 and 300 ° C. 240 ° C, at high pressure, for example from 2 to 35 bar (1 bar = 0.1 MPa), and with a low molar ratio hydrogen / hydrocarbons, for example between 0.1 / 1 and 1/1. The known catalysts that can be used preferably consist of an alumina and / or high purity support preferably containing 2 to 10% by weight of chlorine, 0.1 to 0.40% by weight of platinum, and optionally of other metals. These catalysts can be used with a space velocity of 0.5 to 10 h -1, preferably 1 to 4 h -1. Maintaining the rate of chlorination of the catalyst generally requires the continuous addition of a chlorinated compound such as injected carbon tetrachloride mixed with the filler at a concentration of from 50 to 600 parts per million by weight. The isomerization catalysts of the process according to the invention may preferably be included in the group consisting of: the catalysts supported, most often by a mineral support, typically an oxide (for example an oxide of aluminum or silicon or their mixture), and containing at least one halogen and a group VIII metal. zeolitic catalysts containing at least one Group VIII metal, Friedel and Crafts type catalysts, acid or super acid catalysts, for example of the type heteropolyanions (HPA) on zirconia, the oxides of tungsten on zirconia, the sulphated zirconias. . The isomerization reaction is preferably carried out in the presence of a high activity catalyst, such as for example a chlorinated alumina and platinum catalyst, operating at low temperature, for example between 100 and 300 ° C., preferably between 110 and 240 ° C, at high pressure, for example between 2 and 35 bar (1bar = 0.1 MPa), and with a low molar ratio hydrogen / hydrocarbons, for example between 0.1 / 1 and 1/1 . The preferentially usable catalysts consist of a carrier of high purity alumina 10 preferably containing 2 to 10% by weight of chlorine, 0.1 to 0.40% by weight of platinum and possibly other metals. They can be implemented with a space velocity of between 0.5 and 10 h -1, preferably of between 1 and 4 h -1. Maintaining the rate of chlorination of the catalyst generally requires the continuous addition of a chlorinated compound such as injected carbon tetrachloride mixed with the filler at a concentration of preferably between 50 and 600 parts per million by weight. Other catalysts with comparable acidity to these catalysts can also be used. According to a first variant of the process according to the invention (represented by FIG. 3), the feedstock is sent to the isomerization section [1] via line 10. The conditions of the isomerization section [1] are chosen in order to promote the conversion of low octane n-paraffins (n-pentane, n-hexane) to iso-paraffins of higher octane numbers (isopentane, 2,2-dimethylbutane, 2,3 dimethylbutane, 2-methylpentane, 3-methylpentane). The effluent of the isomerization section (11), once stabilized by separation of the light compounds in the stabilization column [2], is then directed via line (12) to a de-isopentanizer [3] so as to recovering, via the pipe (15), a stream enriched in isopentane and in the bottom via the line (14) an isopentane-depleted fluid. The de-isopentanizer fractionation conditions [3] are preferably such that the isopentane recovery rate at the top (isopentane flow at the top of the de-isopentanizer divided by the isopentane flow rate in the de-isopentanizer feedstock). ) is typically greater than 70%. The npentane content in the top product (15) is then typically less than 15% by weight, preferably less than 10% by weight. The bottom of the de-isopentanizer [3] is directed via line (14) to a de-pentanizer [4] so as to recover at its head (stream 16) a fluid enriched in n-pentane and containing little isopentane, which is recycled to the isomerization reaction section [1] via line (16). A stream (17) containing mainly hydrocarbons containing 6 or more carbon atoms (cut 06+) which feeds the de-isohexanizer [5] is recovered in the bottom via line (17). The de-isohexanizer [5] consists of a separation column whose top product (19) is rich in 06 branched compounds, and an intermediate cut (20) enriched in n-hexane, taken off at the side withdrawal, is recycled to the reaction section [1]. The iso-pentane enriched stream (14), the de-isohexanizer bottoms product [5], and the de-isohexanizer overhead product (19) can be blended to form the process product (s). The sizing of the fractionation column [4] and the fractionation conditions are preferably such that the overall recovery rate of n-pentane (n-pentane flow at the depentanizer head [4] divided by the flow rate of n-pentane pentane at the outlet of the isomerization reaction section [1] is typically greater than 80%, the content of hydrocarbons with 6 or more carbon atoms at the top of the de-pentanizer [4] is typically less than 15%, preferably less than 10% by weight Compared with the state of the art illustrated in FIG. 1, this first variant reduces the energy consumption of the process because the isopentane produced in the isomerization reactor [1] is not vaporized. only once before being exported, and the de-isopentanizer [3] splits an i05 enriched cut 05, which facilitates said separation.
    [0012] According to a second variant of the method according to the invention (represented by FIG. 4), the depentanizer [4] and the de-isopentanizer [3] are replaced by a single column [3] which is a deisopentanizer with 3 sections making it possible to separate also n-pentane. the head product (15) is an isopentane-enriched fluid, the intermediate stream (16) withdrawn laterally via line (16) is a fluid enriched in n-pentane, and the bottom product (17) is a fluid depleted in iso and n-pentane containing essentially hydrocarbons with more than 6 carbon atoms. This bottom flow (17) feeds the de-isohexanizer [5]. The second separation step in the de-isohexanizer is performed identically to the first variant of the invention. According to a third variant of the process according to the invention (represented by FIG. 5), the effluent of the isomerization reaction section [1], once stabilized by separation of the light compounds in the stabilization column [2], is directed via the pipe (12) to the de-pentanizer [4] so as to recover at the head, via the pipe (21), a cut 05 depleted at 06, and bottom via the pipe (17), a fluid containing mainly hydrocarbons with 6 or more carbon atoms, which feeds the de-isohexanizer [5]. The second separation step in the deisohexanizer is performed identically to the first variant according to the invention.
    [0013] The cut 05 feeds, through the pipe (21), the de-isopentanizer [3] which allows to withdraw at the top of column iso-pentane (15), and bottom n-pentane (16) which is recycled to the reaction section [1]. Thermal Integration As in the prior art, the invention has other variants according to various thermal integrations. The principle of these thermal integrations consists in choosing the operating pressure of a first column so that the condensing temperature at the top of this column is greater than the reboiling temperature of one or more other columns of the process.
    [0014] The exchange of heat between the top condenser of the first column to be cooled, and the bottom reboiler of another column to be heated, then replaces at least part, if not all, of the utility consumption. cold used at the top of the first column to ensure its cooling, and the hot utility used in the bottom of the second column to ensure its warming. The terms "first column" and "other column" are generic since it is the choice of the column having the highest condenser temperature that defines it as the first column.
    [0015] Thus, FIG. 6 shows an example of a mode of thermal integration between the de-pentanizer [4], considered as the first column and the de-isopentanizer [3] considered as the other column, according to the first variant (represented by FIG. FIG. 3) of the process according to the invention.
    [0016] FIG. 6 thus shows a heat exchange between the condenser of the column [4] (depentanizer) and the reboiler of the other column [3] (de-isopentanizer). Any other pair of columns could be envisaged, for example an integration between the de-isohexanizer condenser [5] and the depentanizer reboiler [4] or between the de-isohexanizer condenser [5] and the deisopentanizer reboiler [ 3] or between the condenser of the deisohexanizer [5] and the two reboilers of depentanizer [4] and de-isopentanizer [3]. One of these columns may also include an intermediate withdrawal (fractionation column in 3 sections). In summary, the invention relates to a process for the isomerization of a light naphtha, said process comprising an isomerization reaction step [1], followed by a stabilization step [2] of the reaction effluents, and two separation steps. by distillation of the bottom stream resulting from the stabilization step [2]: 1-a first step of separation by distillation (block 3q4) making it possible to separate the hydrocarbons with 5 carbon atoms from the heavier compounds sent to the second section of separation [5], said first separation step producing the following 3 cuts: a) an iso-pentane enriched cut (15) which is a product of the process, b) an n-pentane enriched cut (16) which is recycled to the reaction section [1], and c) a heavier oil-enriched fraction than pentanes (17) which is directed to a second separation step [5], 2- a second separation step [5] consisting of a column of separation of which the top and bottom products are the products of the unit, namely a head stream (19) rich in 06 branched compounds, a bottom stream (18), and an intermediate cut (20) enriched in n-hexane, taken off at the side and recycled to the reaction section [1]. In a preferred manner, in the isomerization process according to the invention, the first separation step comprises two columns, a de-isopentanizer [3] and a de-pentanizer [4] arranged in series, that is to say say that the bottom stream (14) of the de-isopentanizer [3] feeds the de-pentanizer [4], the isopentane stream (15) comes out of the column [3], a stream enriched with heavier hydrocarbons the pentanes (17) exit at the bottom of the column [4] and supply the de-isohexanizer [5], and the top stream (16) of the column [4] is recycled to the isomerization unit [1] ]. According to another preferred variant of the isomerization process according to the invention, the first separation step comprises only one column [3], in which the flow of isopentane (15) leaves at the top of the column [3] , the stream enriched in heavier hydrocarbons than the pentanes (17) leaving at the bottom of said column [3] feeds the de-isohexanizer column [5], and the intermediate withdrawal (stream 16) is recycled to the unit of isomerization [1]. According to another preferred variant of the isomerization process according to the invention, the first separation step comprises the two columns [4] and [3] arranged in series in this order, in which the flow (12) coming from the column of stabilization [2] feeds the de-pentanizer [4], the flow (21) of which feeds the de-isopentanizer [3], and in which the bottom stream enriched with hydrocarbons heavier than pentanes (17) de-pentanizer [4] feeds the de-isohexanizer [5], the deisopentanizer [3] producing the isopentane-rich stream (15) at the top, and the normal pentane-rich stream (16) at the bottom, which is recycled to the isomerization unit [1].
    [0017] According to another variant of the isomerization process according to the invention, a heat exchange is carried out between the condenser of one of the columns [3], [4] or [5] and the reboiler of one of the columns [3] , [4] or [5]. According to a first embodiment of this variant, the heat exchange is carried out between the de-isohexanizer condenser [5] and either the de-pentanizer reboiler [4] or the de-isopentanizer reboiler [3], either both. According to a second embodiment, the heat exchange is carried out between the de-pentanizer condenser [4] and the re-isopentanizer reboiler [3].
    [0018] EXAMPLES ACCORDING TO THE INVENTION EXAMPLE 1 This example is based on the feedstock (10), the composition of which is detailed in Table 1 below: Table 1: composition of the feedstock Mass flow kg / hr 37 249 isobutane% wt 0% n -butane% wt 0% lsopentane% wt 3% n-pentane wt% 27% 2,2-dimethyl-butane% wt 1% 2,3-dimethyl-butane wt% 3% 2-methyl-pentane wt% 15% 2 -methylhexane% by weight 12% n-hexane% by weight 27% cyclopentane% by weight 2% methylcyclopentane% by weight 5% benzene% by weight 2% cyclohexane% by weight 2% The reaction section consists of 2 isomerization reactors operating in series. The inlet temperature of the two reactors is 120 ° C. The inlet pressure of reactor 1 is 35 bar absolute. The inlet pressure of the second reactor is 33 bar absolute.
    [0019] The catalyst used consists of an alumina support containing 7% by weight of chlorine, and 0.23% by weight of platinum and optionally other metals.
    [0020] The space velocity is 2.2h-1. The molar ratio of hydrogen to hydrocarbon is 0.1 / 1. The operating pressures of the columns are chosen so that the head temperature is compatible with the cooling means usually available (cooling water or air at room temperature).
    [0021] The pentane recycle rate is defined as the flow rate of the recycled n-pentane-enriched fluid to the isomerization reaction section divided by the fresh charge rate. The hexanes recycle rate is defined as the flow rate of the recycled n-hexane enriched fluid to the isomerization reaction section divided by the fresh charge rate. For both the process according to the prior art shown in FIG. 1, and for the process according to the invention represented by FIGS. 3 and 4, the recycling rates of the pentanes and of the hexanes are chosen so as to obtain a flow rate. constant at the isomerization reaction section [1], which corresponds to the same amount of catalyst for a given space velocity in the isomerization reactor [1]. The products (or outputs) of the processes are defined as the mixture of the top products (19) and bottom (18) of the de-isohexanizer [5], and the top product (15) of the de-isopentanizer [3] enriched in isopentane. The compositions of the products obtained are summarized in Tables 2 to 4 which follow: Table 2: composition of the product from stream 19 (DiH head) Figure 1 Figure 3 Figure 4 Mass flow kg / hr 21890 21855 21875 i-pentane% wt 0 0 n-pentane% wt 2 2 1 2,2-dimethylbutane% wt 56 58 55 2,3-dimethylbutane% wt 12 12 13 2-methylpentane wt% 23 22 24 2-methyl-hexane% wt 4 4 5 cycloPentane% wt 2 2 2 Table 3: composition of the product from stream 18 (bottom DiH) Figure 1 Figure 3 Figure 4 Mass Flow kg / hr 3166 3166 3166 n-hexane% wt 5 5 methyl-cyclopentane% w 10 10 10 cyclohexane% wt 50 51 52 07+% wt 35 34 32 Table 4: composition of the product resulting from the flow 15 (DiP head) Figure 1 Figure 3 Figure 4 Mass flow kg / hr 11 244 11 255 11 288 butanes% wt 3 2 2 iso-pentane% wt 94 94 92 n-pentane% wt 3 3 Table 5 below compares the results obtained with the various scheme variants according to the prior art and according to the invention. In Table 5, the following concepts are used: 1: Efficiency defined as mass flow rate of product divided by fresh feed rate. 2: heat exchange with the bottom of the stabilization column 3: the supply and withdrawal trays are identified by their order number, all 10 trays being numbered from 1 from top to bottom.
    [0022] Table 5: Comparison of the different diagrams Figure 1 Figure 3 Figure 4 (Invention) (Invention) (Invention) Stabilization column [2] Number of theoretical plates 19 19 19 Feed plate [3] 7 7 7 Rewind power . (MW) 4.9 4.9 4.8 Reflux / Flow rate distillate 2.9 2.9 2.9 Upper section diameter (mm) 1250 1250 1250 Lower section diameter (mm) 2450 2450 2450 De-isohexanizer [5] Number of theoretical plates 62 62 62 Food tray 20 20 20 Required power at the reboiler. (MW) 10.8 10.8 10.8 Required power at intermediate reboiler (MW, plate 41) [2] 2.6 2.6 2.6 Reflux / distillate ratio 5.9 5.6 6.0 Tray Intermediate withdrawal 38 38 38 Diameter. (mm) 3500 3500 3500 De-pentanizer [4] Number of theoretical plates 27 27 N / A Feeding plate 13 13 N / A Required reboiler power. (MW) 7.63 6.8 N / A Reflux / distillate ratio 4.5 11.1 N / A Diameter. (mm) 2900 2750 N / A De-isopentanizer [3] Number of theoretical plates 52 42 59 Feed trays [3] 23/50 29 42 Power required by the reboiler. (MW) 9.2 9.2 9.3 Reflux / distillate ratio 5.8 9.0 9.1 Intermediate withdrawal trays [3] N / A N / A 29 Diameter. (mm) 2450 2750 2900 Pentane recycle rate 0.67 0.67 0.60 Hexane recycling rate 0.49 0.20 0.26 Octane indices Product searches 89.68 89.87 89.52 Yield [ 1] 0.975 0.974 0.975 Mass flow rate at the isomerization reactor (kg / hr) 70388 70659 70298 Total reboiling power (MW) 32.5 31.6 24.9 The following conclusions can be drawn from Table 5: 1. The diagram With a de-isopentanizer and a de-pentanizer according to the invention (FIG. 3) compared with the prior art with these same columns (FIG. 1), the column dimensions and the needs for lower utilities are lower. This necessarily leads to lower investment and operating costs. In addition, the octane number obtained is better. 2. The diagram according to the invention of FIG. 4, with a single column [3] fulfilling the role of deisopentanizer and de-pentanizer, and 3 sections extracted from said column, presents an advantage in terms of investment compared to the implementation in two separate columns, and demonstrates, for an octane number and a yield close to the prior art, a sharp decrease in requirements for hot utilities. EXAMPLE 2 The operating conditions of the reaction section are unchanged with respect to Example 1.
    [0023] Table 6 below presents the results of a thermal integration between the de-isohexanizer [5] and the de-isopentanizer [3] and de-pentanizer [4] according to the invention. In the diagram of FIG. 3, the de-isohexanizer [5] is operated at a pressure of 8 bar absolute, the condensation temperature of the column head is then 127 ° C. A heat exchange is then possible between this column head and the de-pentanizer reboiler [4] operated at 87 ° C and the de-isopentanizer reboiler [3] operated at 109 ° C. In the diagram of FIG. 4, the de-isohexanizer [5] is operated at a pressure of 8 bar, the condensation temperature of the column head is then 127 ° C. A heat exchange is then possible between this column head and the de-isopentanizer reboiler [3] operated at 115 ° C. Table 6: Results of thermal integration according to Example 2 Figure 3 Figure 4 with integration with thermal thermal integration DiH with DiP 3 sections DiH with DP and DiP (invention) (invention) Stabilization column [2] Number of trays Theoretical 19 19 Power required for the reboiler. (MW) 4.9 4.8 Reflux / distillate ratio 2.9 2.9 Upper section diameter (mm) 1250 1250 Lower section diameter (mm) 2450 2450 De-isohexanizer [5] Number of theoretical plates 87 87 27 27 Required power at the reboiler. (MW) 16.5 15.3 Required power at intermediate reboiler (MW, plate 59) Pi 0.8 0.9 Reflux / distillate ratio 8.5 8.5 Intermediate rack 56 56 Diam. (mm) 3500 3500 De-pentanizer [4] Number of theoretical plates 27 N / A Feeding plate 13 NIA Power required by the reboiler. (MW) Pl 6.8 NIA Reflux / distillate ratio 11.2 NIA Diam. (mm) 2750 NIA Isopentanizer [3] Number of theoretical plates 42 59 Feed tray 30 42 Power required by the reboiler. (MW) Pl 8.1 10.2 Reflux / distillate ratio 9.7 11.3 Intermediate withdrawal trays NIA 29 Diam. (mm) 2900 3200 Pentane recycle rate 0.67 0.59 Hexane recycling rate 0.19 0.27 Octane indices Product search 89.64 89.50 Yield [2] 0.974 0.976 Mass flow rate at reactor isomerization (kg / hr) 70600 70597 Total reboiling power (MW) 21.4 20.1 In table 6 the following concepts are used: 1: need covered by condensation of the de-isohexanizer head [5] without the use of a hot utility. 2: Efficiency defined as product mass flow divided by fresh feed rate 3: heat exchange with the bottom of the stabilization column [2] The hot utility requirements of the scheme according to Figure 3 are reduced by 10.2 MW (31 , 6 MW to 21.4 MW).
    [0024] The requirements for hot utilities of the scheme according to Figure 4 are reduced by 4.8 MW (24.9 MW to 20.1 MW). With moderate over-investment for the DIH column [5], these thermal integrations make it possible to significantly reduce the operating costs without altering the performance of the unit.
    [0025] EXAMPLE 3 The operating conditions of the reaction section [1] are unchanged with respect to Example 1. The flow diagram is that of FIG. 3 supplemented by the thermal integration detailed in FIG.
    [0026] The de-pentanizer [4] is operated at a pressure of 11 bar absolute, the condensation temperature of the column head is then 123 ° C. A heat exchange is then possible between this column head and the de-isopentanizer reboiler [3] operated at 109 ° C. Table 7 details the results obtained. In Table 7 we use the following concepts: 1: 7.5MW covered by the condensation of de-isohexanizer head without the use of a hot utility. 2: need covered by condensation at the head of de-isohexanizer without resorting to hot utility. 3: heat exchange with the bottom of the stabilization column Table 7: results of the thermal integration according to example 3 Figure 3 + 6 with thermal integration DiP with PD (Invention) Stabilization column [2] Number of theoretical plates 19 Plateau power 7 Power required at the reboiler. (MW) 4.9 Reflux / Distillate Rate 2.9 Upper Section Diameter (mm) 1250 Lower Section Diameter (mm) 2450 De-Isohexanizer [5] Number of Theoretical Trays 62 Feed Tray 20 Reboiler power requirement. (MW) 9.7 Intermediate reboiler (Tray 40) [3] 2.6 Reflow / Distillate rate 6.5 Intermediate racking trays 38 Diameter. (mm) 3700 De-pentanizer [4] Number of theoretical plates 43 Feeding plate 21 Power required by the reboiler. (MW) 9.8 Reflux / Distillate Rate 12.5 Diameter. (mm) 3000 De-isopentanizer [3] Number of theoretical plates 42 Feed trays 29 Power required by the reboiler. (MW) 9.1 [1] Reflux / Distillate ratio 9.0 Intermediate rack N / A Diameter. (mm) 2750 Pentane recycle rate 0.67 Hexane recycle rate 0.20 Indices Octane product research 89.52 Yield 12] 0.975 Mass flow rate at the isomerization reactor (kg / hr) 70787 Total reboiling power ( MW) 26.0 The requirement for hot utilities in Figure 6 is reduced by 5.6 MW (31.6 MW to 26.0 MW). With a moderate over-investment for the de-pentanizer [4], this thermal integration allows, without altering the performance of the unit, to significantly reduce its operating cost.
    权利要求:
    Claims (2)
    [0001]
    REVENDICATIONS1. A process for the isomerization of a light naphtha, said process comprising an isomerization reaction step [1], followed by a stabilization step [2] of the reaction effluents and two steps of separation by distillation of the bottom stream from the stabilization step [2]: 1-a first step of separation by distillation (block 3q4) making it possible to separate the hydrocarbons with 5 carbon atoms from the heavier compounds sent to the second separation section [5], said first step separator producing the following 3 cuts: a) an iso-pentane enriched cut which is a product of the process, b) an enriched n-pentane cut (16) which is recycled to the reaction section [1], and c) a cut enriched in heavier hydrocarbons than pentanes (17) which is directed to a second separation step [5],
    [0002]
    2-a second separation step [5] consisting of a separation column whose top and bottom products are the products of the unit, namely a head stream (19) rich in branched compounds at 06, a flow bottom end (18), and an intermediate cut (20) enriched in n-hexane, taken off at the side and which is recycled to the reaction section [1]. The process for the isomerization of a light naphtha according to claim 1, wherein the first separation step comprises two columns a de-isopentanizer [3] and a de-pentanizer [4] arranged in series, that is to say that the bottom stream (14) of the de-isopentanizer [3] feeds the depentanizer [4], the isopentane stream (15) leaves the top of the column [3], a stream enriched in hydrocarbons more heavy that the pentanes (17) exit at the bottom of the column [4] and feed the deisohexanizer [5], and the top stream (16) of the column [4] is recycled to the isomerization unit [1] . A process for the isomerization of a light naphtha according to claim 1, wherein the first separation step comprises only one column [3], in which the isopentane stream 15) leaves at the top of the column [3] , the stream enriched in heavier hydrocarbons than the pentanes (17) leaving at the bottom of said column [3] feeds the de-isohexanizer column [5], and the intermediate withdrawal (stream 16) is recycled to the unit of isomerization [1] .4) Process for the isomerization of a light naphtha according to claim 1, wherein the first separation step comprises the two columns [4] and [3] arranged in series in this order, the flow (12 ) from the stabilization column [2] feeds the de-pentanizer [4] whose flow (21) which supplies the de-isopentanizer [3] and the bottom flow of the de-pentanizer [4] enriched in hydrocarbons heavier than pentanes (17) feeds the de-isohexanizer [5], the de-isopentanizer [3] producing head the flow (15), rich in isopentane, and bottom flow (16), rich in normal pentane, which is recycled to the isomerization unit [1]. 5) Process for the isomerization of a light naphtha according to claim 1, wherein a heat exchange is carried out between the condenser of one of the columns [3], [4] or [5] and the reboiler of one of the columns [3], [4] or [5]. 6) Process for the isomerization of a light naphtha according to claim 5, wherein a heat exchange is carried out between the condenser of the de-isohexanizer [5] and either the depentanizer reboiler [4] or the reboiler of the de-isohexanizer [5] and isopentanizer [3], or both. 7) Process for the isomerization of a light naphtha according to claim 5, wherein a heat exchange is carried out between the de-pentanizer condenser [4] and the de-isopentanizer reboiler [3].
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    CN106661460B|2020-04-03|
    WO2015165763A1|2015-11-05|
    US20170044447A1|2017-02-16|
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    US10113121B2|2018-10-30|
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    CN111500317A|2020-04-24|2020-08-07|河北新启元能源技术开发股份有限公司|Production process of isomerized gasoline|
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    2015-10-30| PLSC| Publication of the preliminary search report|Effective date: 20151030 |
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    优先权:
    申请号 | 申请日 | 专利标题
    FR1453841A|FR3020374B1|2014-04-29|2014-04-29|PROCESS FOR PRODUCTION OF GASOLINE COMPRISING AN ISOMERIZATION STEP FOLLOWED BY AT LEAST TWO STEPS OF SEPARATION|FR1453841A| FR3020374B1|2014-04-29|2014-04-29|PROCESS FOR PRODUCTION OF GASOLINE COMPRISING AN ISOMERIZATION STEP FOLLOWED BY AT LEAST TWO STEPS OF SEPARATION|
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    PCT/EP2015/058498| WO2015165763A1|2014-04-29|2015-04-20|Petrol production method comprising an isomerisation step followed by at least two separation steps|
    US15/307,593| US10113121B2|2014-04-29|2015-04-20|Gasoline production process comprising an isomerization step followed by at least two separation steps|
    EP15719168.5A| EP3137583B1|2014-04-29|2015-04-20|Petrol production method comprising an isomerisation step followed by at least two separation steps|
    SA516380157A| SA516380157B1|2014-04-29|2016-10-27|Gasoline Production Process Comprising an Isomerization Step Followed By at Least Two Separation Steps|
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