Classifications

• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G45/00—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds
  • C10G45/58—Refining of hydrocarbon oils using hydrogen or hydrogen-generating compounds to change the structural skeleton of some of the hydrocarbon content without cracking the other hydrocarbons present, e.g. lowering pour point; Selective hydrocracking of normal paraffins
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G61/00—Treatment of naphtha by at least one reforming process and at least one process of refining in the absence of hydrogen
  • C10G61/02—Treatment of naphtha by at least one reforming process and at least one process of refining in the absence of hydrogen plural serial stages only
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G7/00—Distillation of hydrocarbon oils
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L1/00—Liquid carbonaceous fuels
  • C10L1/04—Liquid carbonaceous fuels essentially based on blends of hydrocarbons
  • C10L1/06—Liquid carbonaceous fuels essentially based on blends of hydrocarbons for spark ignition
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
  • C10G2300/10—Feedstock materials
  • C10G2300/1037—Hydrocarbon fractions
  • C10G2300/104—Light gasoline having a boiling range of about 20 - 100 °C
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2300/00—Aspects relating to hydrocarbon processing covered by groups C10G1/00 - C10G99/00
  • C10G2300/10—Feedstock materials
  • C10G2300/1037—Hydrocarbon fractions
  • C10G2300/1044—Heavy gasoline or naphtha having a boiling range of about 100 - 180 °C
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10G—CRACKING HYDROCARBON OILS; PRODUCTION OF LIQUID HYDROCARBON MIXTURES, e.g. BY DESTRUCTIVE HYDROGENATION, OLIGOMERISATION, POLYMERISATION; RECOVERY OF HYDROCARBON OILS FROM OIL-SHALE, OIL-SAND, OR GASES; REFINING MIXTURES MAINLY CONSISTING OF HYDROCARBONS; REFORMING OF NAPHTHA; MINERAL WAXES
  • C10G2400/00—Products obtained by processes covered by groups C10G9/00 - C10G69/14
  • C10G2400/02—Gasoline
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2200/00—Components of fuel compositions
  • C10L2200/04—Organic compounds
  • C10L2200/0407—Specifically defined hydrocarbon fractions as obtained from, e.g. a distillation column
  • C10L2200/0415—Light distillates, e.g. LPG, naphtha
  • C10L2200/0423—Gasoline
• • C—CHEMISTRY; METALLURGY
  • C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
  • C10L—FUELS NOT OTHERWISE PROVIDED FOR; NATURAL GAS; SYNTHETIC NATURAL GAS OBTAINED BY PROCESSES NOT COVERED BY SUBCLASSES C10G, C10K; LIQUEFIED PETROLEUM GAS; ADDING MATERIALS TO FUELS OR FIRES TO REDUCE SMOKE OR UNDESIRABLE DEPOSITS OR TO FACILITATE SOOT REMOVAL; FIRELIGHTERS
  • C10L2290/00—Fuel preparation or upgrading, processes or apparatus therefore, comprising specific process steps or apparatus units
  • C10L2290/54—Specific separation steps for separating fractions, components or impurities during preparation or upgrading of a fuel
  • C10L2290/543—Distillation, fractionation or rectification for separating fractions, components or impurities during preparation or upgrading of a fuel

Definitions

• the invention relates to the field of producing high octane gasoline.
• Naphthas from the atmospheric distillation of petroleum usually consist mainly of hydrocarbons comprising 5 to 10 carbon atoms (C5-C10 cuts). These naphthas are generally fractionated into a light naphtha cut (C5-C6 cut) and a heavy naphtha cut (C7-C10). 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 (C5 and C6) but may in addition comprise hydrocarbons having 4 or 7 or even 8 carbon atoms (C4, C7, C8), 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.).
• catalytic cracking gasoline, alkylates, etc. are then sent to the gasoline pool with other bases or additives.
• other bases or additives catalytic cracking gasoline, alkylates, etc.
• Patent FR 2,828,205 describes a process for isomerizing a C5-C8 cut in which said cut is fractionated into a C5-C6 cut and a C7-C8 cut which are each isomerized separately in specific conditions for each cut.
• 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.
• GB Patent 1,056,517 describes a process for the isomerization of a C5-C6 cut comprising a deisopentanizer (DiP), isomerization of the isopentane depleted cut (ISOM), a separation of the isomerized effluent to recover n-pentane (DP) which is recycled with the feedstock at the inlet of the deisopentanizer and a separation of the branched C6 hydrocarbons (deisohexanizer, DiH) for recovering branched high octane C 6 hydrocarbons, the balance being recycled to the reactor of isomerization.
• DiP / ISOM / DP / DiH corresponds to Figure 1 (according to the prior art) of this application.
• 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]. ].
• 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 together in a single column [3] allowing fractionation into 3 sections.
• 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 in parentheses.
• the numbers of the conduits conveying the flows are the same as those of the flows conveyed.
• the invention relates to the field of producing high octane gasoline.
• the naphthas resulting from the atmospheric distillation of petroleum usually consist mainly of hydrocarbons comprising from 5 to 10 carbon atoms (C5-C10 cut).
• the process according to the present invention processes a filler of the light naphtha type and preferentially a C5 and C6 cut (hydrocarbon cut comprising 5 or 6 carbon atoms), and aims at maximizing the branched molecules relative to the linear (or normal) molecules.
• these fillers may optionally comprise other hydrocarbons, for example hydrocarbons comprising 4 or 7 or even 8 carbon atoms (C4, C7 and C8 cuts).
• the process according to the invention is more particularly applicable to fillers whose iso pentane content is less than 25% and preferably less than 20%.
• 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 the 3 + 4 block) and a separation of the remaining products, in particular C6 branched compounds (denoted DiH) (represented by block 5), according to the sequence ISOM / STAB / DiP / DP / IHL.
• 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 thus distinguished from the process according to the prior art (FIG.
• said separations are all located downstream of the isomerization section [1], and more precisely downstream of the stabilization column [2], unlike the methods of the prior art which do not 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 the diagram of FIG.
• the present invention can be described as a process for the isomerization of a light naphtha, or preferentially of a C5-C6 essentially, said process comprising two distillation separation stages located downstream of the isomerization step: - a first distillation separation step (3 + 4 block) 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 branched C 6 compounds, a flow of bottom (18), and an intermediate cut (20) enriched in n-hexane, taken off at the side and recycled to the reaction section [1].
• the first separation step comprises two columns (3 and 4) arranged in series, that is to say that the bottom flow of the isopentanizer [3] feeds the de-pentanizer [4] as shown in figure 3.
• the de-isopentanizer 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].
• Intermediate withdrawal (stream 16) is recycled to the isomerization unit [1].
• the first separation step comprises the two columns [4] and [3] arranged in series in this order.
• 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] fed 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].
• the charge (10) is generally constituted by a light naphtha, preferably a C5-C6 cut, which may optionally contain heavier hydrocarbons.
• This feedstock 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 in separating at the top the lighter compounds than the pentanes (stream 13), and in bottom a stabilized effluent (12) - a first step of separation by distillation (block 3 + 4) to separate the hydrocarbons with 5 carbon atoms of 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 first product of the process, b) an enriched n-pentane cut (16) which is recycled to the reaction section [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 the products of the unit, namely a head stream (19) rich in branched C6 compounds, a stream of bottom (18), and an intermediate cut (20) enriched in n-hexane, taken off at the side and recycled to the reaction section [1].
• the iso-pentane-enriched cut (15) from the first separation step and the head (19) and bottom (18) streams from the second separation step may optionally be subsequently mixed to provide the product or products. of the process. Description of Figure 1 according to the prior art:
• FIG. 1 shows the prior art scheme which may be considered as closest to the present invention.
• 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 flow (14) of the de-isopentanizer [3] is sent to the isomerization reaction section [1] via line 14.
• the operating conditions of the reaction section [1] are chosen so as to promote the conversion of n-paraffins of low octane number (li-pentane, n-hexane) to iso-paraffins of higher octane numbers. (Isopentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane).
• 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 flow (16) of the de-pentanizer [4] is recycled to the column [3] of the de-isopentanizer.
• 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 mixed with the load 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 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.
• 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 it is admitted into the de-isopentanizer [3] or as shown in FIG. 1, inside said de-isopentanizer [3].
• the method according to the invention comprises:
• This first separation step consists, by the use of one or two fractionation columns, in producing the following 3 sections: an iso-pentane enriched cut which is a product of the process (15),
• a second separation step [5] which can preferably be carried out by means of a de-isohexanizer consisting of a separation column whose top product (19) is rich in branched C6 compounds, and an intermediate cut ( 20), enriched in n-hexane, taken off at the side, 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.
• 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.
• Suitable known catalysts preferably comprise an alumina support and / or high purity preferably containing 2 to 10% by weight of chlorine, 0.1 to 0.40% by weight of platinum, and possibly other metals. These catalysts can be used with a space velocity of 0.5 to 10 h -1 , preferably 1 to 4 h -1 .
• the isomerization catalysts of the process according to the invention may be preferentially included in the group consisting of:
• 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.
• the catalysts that are preferentially usable consist of a carrier of high purity alumina preferably containing 2 to 10% by weight of chlorine, 0.1 to 0.40% by weight of
• the feed is sent to the isomerization section [1] via line 10.
• the conditions of the isomerization section [1] are chosen so as to promote the conversion of low octane n-paraffins (n-pentane, n-hexane) to iso-paraffins of higher octane numbers. high (isopentane, 2,2-dimethylbutane, 2,3-dimethylbutane, 2-methylpentane, 3-methylpentane).
• 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 n-pentane 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 with 6 or more carbon atoms (C6 + cut) is fed into the bottom via line (17) and feeds the de-isohexanizer [5].
• the de-isohexanizer [5] consists of a separation column whose top product (19) is rich in branched C 6 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 (flow rate of n-pentane at the top of the condenser [4] divided by the flow rate of n -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.
• this first variant reduces the energy consumption of the process since the isopentane produced in the isomerization reactor [1] is vaporized only once before to be exported, and the de-isopentanizer [3] splits a C5-enriched C5 cut, which facilitates said separation.
• the de-pentanizer [4] and the de-isopentanizer [3] are replaced by a single column [3] which is a de-isopentanizer with 3 cuts to separate the n-pentane.
• the head product (15) is a fluid enriched in isopentane
• the intermediate stream (16) withdrawn laterally, via line (16), is a fluid enriched in n-pentane
• the bottom product (17) is a fluid depleted in iso and n-pentane containing essentially hydrocarbons for more of 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.
• 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 C5 cut C6 depleted, 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 de-isohexanizer is performed identically to the first variant of the invention.
• the cut C5 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].
• 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.
• 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.
• 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.
• 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 column coupling 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 reboiler of the de-isohexanizer [5]. isopentanizer [3] or between the condenser of the deisohexanizer [5] and the two reboilers depentanizer [4] and de-isopentanizer [3].
• One of these columns may also include an intermediate withdrawal (fractionation column in 3 sections).
• the invention relates to a process for the isomerization of a light naphtha.
• This process comprises 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 from the stabilization stage [2]:
• a first step of separation by distillation (block 3 + 4) making it possible to separate the hydrocarbons with 5 carbon atoms from the heavier compounds sent to the second separation section [5], said first separation step producing the 3 slices the following: 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 reaction section [1], and c) an enriched cut in hydrocarbons heavier than pentanes (17) which is directed to a second separation step [5], 2 - 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 branched C6 compounds, a bottom stream (18), and an intermediate cut (20) enriched in n-hexane, taken off at the side rack which is recycled to the reaction section [1].
• 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] ].
• 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].
• 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] whose flow (21) which feeds the de-isopentanizer [3], and in which the bottom stream: enriched in hydrocarbons heavier than pentanes (17 ) of the de-pentanizer [4] feeds the de-isohexanizer [5], the de-isopentanizer [3] producing the isopentane-rich stream (15) at its head, and the flow (16), rich in normal pentane, in the background , which is recycled to the isomerization unit [1].
• 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].
• 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.
• the heat exchange is carried out between the de-pentanizer condenser [4] and the re-isopentanizer reboiler [3].
• 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.
• 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.
• the space velocity is 2.2h -1 .
• the hydrogen to hydrocarbon molar ratio 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).
• 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 feed rate.
• the hexane recycle rate is defined as the flow rate of the recycled n-hexane enriched fluid to the isomerization reaction section divided by the fresh feed rate.
• 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:
• the feeding and racking trays are identified by their order number, all trays being numbered from 1 from top to bottom.
• FIG. 3 The diagram with a de-isopentanizer and de-pentanizer according to the invention (FIG. 3) compared with the prior art with these same columns (FIG. 1) has a lower column size and needs for hot utilities. This necessarily leads to lower investment and operating costs. In addition, the octane number obtained is better.
• 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.
• 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.
• Example 1 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. 6.
• 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.

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• 2014
  • 2014-04-29 FR FR1453841A patent/FR3020374B1/fr not_active Expired - Fee Related
• 2015
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  • 2015-04-20 CN CN201580023209.2A patent/CN106661460B/zh active Active
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• 2016
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