|Title of Invention||
REACTOR WITH A PLURALITY OF FIXED OR MOVING BED ZONES AND A PROCESS FOR OLIGOMERISATION OF AN OLEFIN CUT
|Abstract||The present invention concerns a reactor with staged zones of the axial flow type for carrying out highly endothermic or exothermic reactions. The reactor includes a contraction in the catalytic bed between an upper zone Za and a lower zone Zb, allowing a heat exchanger to be housed in the reactor for intermediate heating or cooling of effluents. A chemical conversion process using said reactor for exothermic or endothermic reactions in a gas and/or liquid phase is described, in particular for oligomerizing C2 to C12 cuts to produce a diesel cut.|
Field of the invention
The present invention relates to a reactor inside which at least one catalytic reaction having a large thermal effect is carried out, generally release of heat (exothermic reactions), or sometimes, absorption of heat (endothermic reactions).
It also relates to a process for oligomerizing olefinic feeds (i.e. polymerization or addition limited to essentially 2 to 6 monomers or base molecules). In particular, it relates to reactions for adding an olefin to another compound present in the feed, for example an olefin, a sulphur-containing compound, a nitrogen-containing compound, an aromatic molecule, said addition reactions being aimed at increasing the molecular weight of that compound.
More particularly, it relates to oligomerization reactions from olefinic hydrocarbon cuts containing 2 to 12 carbon atoms, preferably 3 to 7 carbon atoms, and more particularly 4 to 6 carbon atoms, to oligomerization reactions which can produce a gasoline, diesel or lubricant cut,, and more particularly diesel cut hydrocarbons.
The invention concerns a reactor with a plurality of reaction zones, stacked vertically and separated by at least one heat exchange zone in a contraction in the passage of the catalyst between the reaction zones. Examination of prior art
In the prior art, it is known to carry out chemical reactions, in particular to refine oil or hydrocarbon fractions, in catalytic reactors using a granular bed. In general, grains of catalyst with a characteristic dimension in the range 0.5 to 5 mm are used. Said grains of catalyst are frequently substantially spherical in shape to facilitate their flow. However, they may be shaped differently, for example if they are produced by extrusion. The catalysts employed in the reactor of the invention are all catalysts with a characteristic dimension (for example diameter) in the range 0.5 to 5 mm in diameter, preferably in the range 1 to 4 mm.
In general, catalyst deactivation, for example that of catalysts comprising a zeolite used to produce diesel cuts by oligomerization, is rapid. Thus, the catalyst has to be replaced regularly to maintain reactor performance as regards selectivity and yield.
Two techniques are routinely used in this regard:
In the "fixed bed" technique, all of the catalyst contained in the reactor is changed at the end of a cycle, when the catalyst is assumed to be used. Typically, then, the operation is interrupted, the reactor is emptied, then it is re-filled with fresh and/or regenerated catalyst.
A further technique is used for catalytic reactions with movement (continuous or semi-continuous) and regeneration (continuous or semi-continuous) of the catalyst: the "moving bed" technique is constituted by a stack of grains of catalysts contained in the reactor, like in a fixed
bed, but said grains are displaced (at a very slow mean rate, continuously or discontinuously) from the top to the bottom of the reactor under gravity. A small quantity of used catalyst is withdrawn continuously or discontinuously from the bottom of the reactor, and the same quantity of fresh and/or regenerated catalyst is introduced to the head of the reactor. As an example, a suitable quantity of catalyst may be withdrawn and re-introduced every 4 to 8 hours, so that the overall activity of the catalyst remains constant. The used withdrawn catalyst is typically regenerated then recycled, except optionally for a small quantity of catalyst which is eliminated and replaced by fresh catalyst.
The reactor of the invention may be used in fixed and in moving bed mode, but the second variation represents the preferred variation.
Further, for highly endothermic or exothermic reactions, means for exchanging heat with the reaction fluid (furnace or heat exchanger) are sometimes used, inside or outside the reactor, to maintain the temperature difference between the inlet and outlet of the reactor within the desired limits and/or to re-establish the temperature of the reaction fluid between 2 or more reactors in series.
United States patent US-A1-2002/0011428 describes a multi-stage moving bed reactor intended to carry out hydrotreatment reactions. A system forming the subject matter of other patents (in particular US-A 5 076 908) allows catalyst to be added and withdrawn continuously or semi-continuously from each stage of the reactor. The feed flows from one stage to another. In contrast, the catalyst from one stage does not flow to the next stage. It has been discovered that such a system can also be used to carry out an oligomerization reaction. However, the described system cannot effectively control the temperature profile within each reaction section.
International patent WO-A 02/04575 describes an oligomerization process using a zeolite and a tube type reactor, in a fixed bed, or any other reactor which may be used to carry out the oligomerization reaction. The patent describes a method which can add and withdraw catalyst from the reactor continuously or semi-continuously. However, the problem with controlling the exothermicity of the reaction is not addressed.
European patent EP-A1-0 1 236 506 describes a thin bed multi-stage reactor with an internal heat exchanger used principally in the context of long chain paraffin dehydrogenation. That system can accurately control the temperature in each reaction section. However, it is not suitable for large quantities of catalyst, as it is adapted to thin beds. The catalyst replenishing rate in the reactor in that case is very low.
Thus, the above patent applications, which describe superimposed or multi-stage reactors, do not describe means that can use both large quantities of catalyst and employ integrated thermal means.
The present invention describes a reactor and a process for chemical conversion of hydrocarbons using said reactor, which can overcome the problems connected with employing highly exothermic or endothermic reactions, in particular oligomerization reactions. It can employ a compact reactor with a large capacity as regards the quantity of catalyst present, but having a large internal volume to integrate a heat exchanger. Brief description of the invention
The present invention will be illustrated in the particular case of an exothermic reaction for oligomerizing olefins in an olefinic feed (frequently comprising 20% to 100% by weight of olefins). However, its field of application is wider and it concerns all exothermic or endothermic reactions in the gas and/or liquid phase for which a large catalytic volume and a thermal control are typically essential, in particular reactions for adding an olefin to another compound present in the feed, for example an olefin, a sulphur-containing compound, a nitrogen-containing compound, an aromatic molecule, said addition reactions being aimed at increasing the molecular weight of said compound.
In particular, the present reactor is particularly suited to carrying out a reaction for oligomerizing olefinic hydrocarbon cuts containing 2 to 12 carbon atoms, preferably 3 to 7 carbon atoms, more preferably 4 to 6 carbon atoms, to obtain hydrocarbons in the gasoline, diesel or lubricating oil ranges, and more particularly diesel cut hydrocarbons, with a typical distillation interval in the range 160°C to 370°C, in particular 200°C to 365°C.
For this chemical reaction, it is advisable to avoid large disparities in catalytic activity between the various reaction zones, as they generate conversion losses.
Further, the oligomerization reaction is highly exothermic. Too high a temperature encourages cracking of the oligomerized compounds and is thus undesirable.
Too low a temperature in certain reaction zones limits the desired conversion of sufficiently heavy compounds in the composition of a diesel cut. Thus, it is advisable to accurately control the temperatures in the various reaction zones. In particular, it is important to adjust the temperature in a catalytic reaction zone as a function of the activity of the catalyst in said zone.
For these various reasons, it is desirable to use a plurality of successive reaction zones, preferably with large catalyst volumes, and to install heat exchange means to adjust the temperature of the reaction fluid between 2 successive zones.
To overcome the technical problems cited above, the invention proposes a reactor having a substantial or large catalytic volume, integrated heat exchange means, at a contraction for the passage of catalyst. In a preferred variation, the reactor of the invention comprises means allowing moving bed mode operation.
Optionally, the reactor may comprise means, typically at the inlet to each reaction zone, for adding fresh or regenerated catalyst to mix it with at least a portion of the (partially) used catalyst from the upstream reaction zone.
The invention also proposes a process for carrying out chemical reactions in said reactor, in particular a process for oligomerizing olefinic feeds. Brief description of the figures
Figure 1 shows a view of a reactor in accordance with the invention in its basic configuration.
Figure 2 shows a view of a reactor in accordance with the invention in a variation comprising injection of an additional reaction fluid between two reaction zones. Detailed description of the invention
The invention will be better understood from Figures 1 and 2, which illustrate different embodiments of the invention without in any way limiting its scope.
The invention is shown in its basic configuration in Figure 1.
In general, the invention concerns a reactor which is elongate along a substantially vertical axis, said reactor comprising, in the same shell, a plurality of vertically staged catalytic reaction zones, said reactor being adapted to axial motion of a reaction fluid in series in each of said zones, and comprising means 100 for introducing and means 101 for evacuating said reaction fluid, means 102 for supplying fresh or regenerated catalyst to the reactor head, and means 105 for evacuating used catalyst from the lower portion of the reactor, said reactor comprising in particular: an upper reaction zone Za (3 a) filled with granular catalyst, with a cross section (in a horizontal plane) which is substantially identical to that of the shell over part of its height, connected directly via a contracted zone to a reaction zone Zb (3 b) which is also filled with granular catalyst and with a cross section that is substantially identical to that of the shell over part of its height, located just below the upper reaction zone Za, said reaction zones Za and Zb being two successive reaction zones connected directly via a passage for reaction effluents, and via a passage for catalyst from the zone Za to the zone Zb through said contracted zone, zone Za being directly or indirectly connected at its upper portion to said means 102 for supplying fresh or regenerated catalyst, zone Zb being directly or indirectly connected at its lower portion to said means 105 for evacuating used catalyst, the reactor also comprising, disposed at the contracted zone between said contracted zone and the shell of the reactor, a heat exchanger 8 for heating or cooling reaction fluid moving between zones Za and Zb.
Zones Za and Zb are filled with granular catalyst over a cross section substantially identical to that of the shell of the reactor over part of its height; thus their high catalytic volume
is high. However, there exists a contracted zone which allows catalyst to pass and houses an exchanger integrated into the reactor at that zone. It is typically annular.
Preferably, zone Za comprises, at its lower portion, a substantially conical convergent comprising perforations for the passage of reaction fluid, connected to a channel 2b with a i reduced diameter with respect to that of the reactor, said channel defining at least a portion of the contracted zone in which the catalyst can flow (at the end of each fixed bed cycle, continuously or semi-continuously as a moving bed). Said channel 2b typically has a diameter in the range 1% to 50% of the diameter of the reactor at the contracted zone, preferably in the range 1% to 30% and more preferably in the range 2% to 20%.
This produces a large space between the contracted zone and the shell, which is advantageously used to install the heat exchanger 8. Compared with the prior art, this combines two advantages: that linked to the use of large volumes of catalyst (the reaction zones having the diameter of the reactor, in combination with axial reactor type reaction zones, in which the reaction fluid flows principally in a manner substantially parallel to the vertical axis of the reactor), and that of nevertheless being able to house an integral heat exchanger because of the contraction. Typically, the heat exchanger 8 is disposed around the passage for the catalyst at the contraction.
The invention may concern both a fixed bed reactor and a moving bed reactor, although the moving bed option is preferred. In the case of a fixed bed reactor, all of the reaction zones are completely filled with regenerated and/or fresh catalyst, and the reactor is completely emptied of catalyst when, after an operational cycle (fixed bed), it has been used to a point which necessitates its replacement.
According to the invention, zones Za and Zb are successive reaction zones, which means that the effluents from one of said zones supplies the other zone without traversing another reaction zone.
In a variation of the invention, which can be used as a moving bed, the reactor shown in Figure 1 comprises means 104 for withdrawing and evacuating a portion of the used catalyst from the upper reaction zone Za connected to collecting means. This can eliminate a portion (for example 10% to 70%, usually 15% to 50%) of used catalyst, before introducing regenerated and/or fresh catalyst.
Then, the mean activity of the mixed catalyst supplying Zb is increased without generally substantially increasing the total flow rate of the catalyst entering into Zb, and even keeping constant the flow rate of the catalyst moving in Za and in Zb. At a constant total flow rate of fresh and/or regenerated catalyst, the invention can to a certain extent re-equilibrate the catalytic activity between the various reaction zones.
Said makeup of regenerated and/or fresh catalyst may also, for example, represent 10% to 70%, and usually 15% to 50% of catalyst supplying Za at the reactor head, or supplying Zb.
Typically, the two successive reaction zones Za and Zb are connected via a circuit for moving reaction fluid traversing the heat exchanger 8 to heat or cool said reaction fluid, said circuit typically being located essentially around the contracted zone, between said zone and the shell of the reactor, in an intermediate zone located between the two successive reaction zones Za and Zb.
Optionally, in a variation shown in Figure 2, the intermediate zone comprises means (10) for introducing one or more additional reaction fluids 106, and for mixing the fluid or fluids with the reaction fluid moving between the successive reaction zones Za and Zb. In particular, it may be useful to add a new chemical reagent, to carry out a reaction subsequent to that carried out in the upstream zone, for example a reaction for alkylation of an aromatic molecule or a mixture of aromatic compounds, and/or to introduce a hydrogen-rich recycle gas (comprising more than 50% and usually more than 70% molar of H2), to increase the quantity of hydrogen present. Said gas may also have a thermal, heating or more frequently a cooling effect on the effluents before they enter the downstream reaction zone.
The reactor of the invention and all variations as described in the present application may be used in the context of a chemical hydrocarbon conversion process, and in particular a process for oligomerizing olefinic feeds containing 2 to 12 carbon atoms, said process or processes constituting a further aspect of the invention.
In such a process, in particular oligomerization, the following typical conditions are employed: the pressure is in the range 0.1 to 10 MPa, preferably in the range 0.3 to 7 MPa, the temperature is in the range 40°C to 600°C, preferably in the range 60°C to 400°C, the hourly space velocity HSV is in the range 0.01 to 100 h"1 and preferably in the range 0.4 to 30 h"1, and the catalyst moves in each reaction zone at a (mean) rate in the range 1 cm/hour to 200 cm/hour, preferably in the range 2 cm/hour to 100 cm/hour.
The invention is particularly suitable to processes in which the operating conditions are selected: temperature, pressure, HSV, to limit the variation in temperature in each of the reaction zones to one or more values in the range 2°C to 50°C. The heat exchanger 8 may typically cool the reaction fluid (or heat it for an endothermic process) by 2°C to 50°C, preferably 10°C to 50°C. Detailed description of the figures
Reference will now be made to Figure 1. In the reactor shown, the catalyst passes through all of the reaction zones in a descending stream, and the feed (the reaction fluid) also passes through all of the reaction zones, but counter-current to the catalyst. The reaction zones
shown are of the axial reactor type. However, a configuration in which the reaction fluid moves
counter-current to the catalyst, i.e. from top to bottom, is also perfectly possible in the context of
the invention. Further, the reaction zones may be of the radial reactor type. However, the axial
reactor configuration is preferred.
Fresh and/or regenerated catalyst is supplied, principally in general, to the head of the
reactor via the line 102, then the line 2a. This catalyst flows slowly, continuously or discontinuously in a zone Za, reference number 3a in Figure 1, which is the upper reaction zone. At the bottom portion of said zone, it is collected in a collection zone 4a, and then flows in the chamber 5. A fraction of said catalyst, partially used, is withdrawn via the line 104, typically for regeneration. The chamber 5 may be provided with means (not shown) to facilitate extraction of a granular product such as the catalyst, for example an extracting screw, or by pneumatic transport, or a fluidized bed or any other means known to the skilled person. It is also possible to use a line 104 which is inclined by at least 60° with respect to the horizontal and optional injections of catalyst aeration gas (for example nitrogen) to facilitate evacuation of the catalyst.
The portion of the catalyst present in the chamber 5 which is not extracted flows into the mixing chamber 7 for mixing with a further portion of fresh and/or regenerated catalyst, introduced via line 103, via a valve 6. It is possible to use a line 103 inclined by at least 60° to the horizontal, including its terminal portion, and optional injections of catalyst aeration gas (for example nitrogen) to facilitate the introduction of fresh and/or regenerated catalyst.
The mixing chamber 7 may be provided with means (not shown) to facilitate mixing of the fresh/regenerated catalyst and partially used catalyst. In particular, a rotary basket may be used to stir the catalyst in the zone 7, or stirring paddles disposed in the zone 7, driven by an external motor. It is also possible to use a fluidized bed or any other known system for mixing granules.
The mixture of catalysts thus formed has an increased catalytic activity compared with that of the catalyst from the zone Za. Said mixture traverses a contracted passage 2b, then supplies the zone Zb, reference number 3b in Figure 1, which is immediately below Za (as regards the reaction zones).
The used catalyst from zone Zb, 3b, moves in a withdrawal line 4b, and is then evacuated from the reactor via the line 105 on which the valve 9 can be found. It is then sent to a regeneration zone (not shown) via a system for transporting particles by means of a liquid or gaseous transport fluid (for example nitrogen), using techniques which are known to the skilled person concerning the moving bed. In particular, it is possible to use, at the line 105 or below the valve 9, a drum for receiving used catalyst allowing a predetermined quantity of catalyst to
be stored prior to subsequent evacuation by pneumatic transport, generally using a primary catalyst aeration fluid, and a secondary transport fluid.
Techniques allowing introduction, mixing or transport of granular products are generic techniques which are well known to the skilled person, and do not form part of the invention.
The catalyst regeneration zone, not shown, may be provided with an elutriator or any other means for separating the fine particles produced during the various catalyst transport operations. The regenerated catalyst (in particular after controlled oxidation of carbonaceous deposits) is typically recycled via lines 102 and 103 with a makeup of fresh catalyst. A fraction of the catalyst from the loop (usually used catalyst) is generally evacuated to allow a makeup of fresh catalyst, keeping the total quantity of catalyst employed constant.
The reaction fluid, for example a feed of C4-C6 olefinic hydrocarbons (essentially containing 4 to 6 carbon atoms), is supplied via the line 100 to supply chamber 1, traverses the initial reaction zone Zb, 3b, filled with catalyst, then the intermediate zone 22 containing no catalyst, returns to the final reaction zone Za, 3a, filled with catalyst, then enters the chamber 23 before being evacuated via the line 101. The upper and lower portions of the reaction zones Za and Zb are advantageously provided with perforated screens (shown in the figures as dotted lines) to allow the passage of a reaction fluid. Said screens may be inclined at an angle of 60° or more, at the lower portion, to facilitate catalyst flow. A heat exchanger 8 with circulating thermal fluid is disposed inside the reactor, in the intermediate zone 22 (which is itself inside the reactor), to carry out heat exchange with the reaction fluid passing between Zb and Za. Said heat exchanger is advantageously disposed in the contraction 2b for passage of the catalyst, because space is freed up inside the reactor at this location.
Said heat exchanger generally uses a thermal fluid for heating or cooling which moves in tubes, the tube assembly forming, for example, one or more rods which are immersed in the reaction fluid in the intermediate zone 22. The exchanger may, however, be of any type known to the skilled person, for example a plate exchanger, or a finned tube exchanger, or an exchanger with tubes which are bare, straight or wound about the vertical axis of the reactor (and typically that of the contracted zone); the invention is not limited to a particular type of said exchanger.
A variety of fluids under pressure may be used as a thermal heating or cooling fluid: steam, air, water, hydrogen or hydrogen-rich recycle gas, nitrogen, molten salts, aromatic oils, the feed itself, etc.
Figure 2 shows a further reactor in accordance with the present invention, comprising the same elements as those shown in Figure 1. It also comprises a line 106 for supplying an additional reaction fluid, to make up reagent and/or hydrogen. Said fluid is distributed into the intermediate zone 22 via a distribution rack 10 to facilitate homogeneous mixing with the
reaction fluid from zone Zb. Mixing is also encouraged by the fact that the intermediate zone 22 is free of catalyst.
The advantages of the reactor(s) of the present invention over prior art reactors are as follows:
• a substantial improvement in performance (conversion, selectivity, yield);
• greater reliability of the facility due to the simplicity and compactness of the means used, in particular the heat exchange means employed;
• the cost of the reactor, and its installation costs, are also reduced because of its compactness.
The type of reactor shown in Figure 1 functions as follows: the flow rate of the regenerated catalyst or, optionally, the fresh catalyst, is defined so as to maintain a predetermined activity level on each reaction zone. As an example, said catalyst makeup may be defined as a function of one characteristic of the reaction fluid at the reaction zone outlet. Said characteristic may be temperature, composition, conversion, or any other physico-chemical characteristic which can be measured on-line. The correlations which connect one or more of these parameters which are measurable on line and the activity of the catalyst depend on the reaction carried out, the type of catalyst and its rate of movement. A simple manner is to monitor the conversion in the zone Zb or the variation in temperature (delta T) of the reaction fluid in said zone, or the temperature at the outlet from said zone, by acting on the regenerated and/or fresh catalyst makeup flow rate: if the measured value of delta T is lower than the predetermined value (typically dependent on the initial composition of the feed), or if the temperature at the outlet from the zone corresponds to insufficient reaction, the flow rate to said zone of the regenerated and/or fresh catalyst makeup is increased, and conversely, the makeup is reduced if the conversion in said zone (deduced from delta T or the outlet temperature) is too high. Simultaneously, the same quantity of used catalyst as the makeup added may be evacuated before mixing, to maintain constant the overall flow rate of catalyst in zone Zb.
The flow rate of the makeup catalyst may thus be completely automated. As an alternative, it may be adjusted by the operator at various times (for example once or twice a day), as a function of said temperatures and/or delta T.
Heating or cooling of the reaction fluid in the exchanger 8 (delta T) may be controlled by means of the flow rate or the temperature of the thermal fluid moving in the exchanger 8.
The reactor of Figure 2 functions in an analogous manner. In this reactor, a makeup of reagents and/or hydrogen supplied via line 106 is used. Said makeup is typically with controlled flow rate and temperature.
The catalyst moving in the reactor of the invention may be of a variety of types. In the case of an oligomerization reactor, any type of acid catalyst allowing oligomerization may be used, for example an amorphous silica-alumina type catalyst or a solid phosphoric acid type catalyst or an ion exchange type resin, or a catalyst having form selectivity, for example a zeolitic catalyst, such as a zeolitic catalyst with structure type MFI, FER, EUO, TON, LTL, MOR, MIT, MEL, MWW, MTW or NU-86, NU-87, NU-88 or IM-5 zeolites.
Said zeolitic acid catalysts may be used as is or after modifications, said modifications preferably affecting the catalyst acidity. The term "acidity" designates both the strength of the acidic sites and the concentration of acidic sites.
Said modifications may affect the framework of the zeolite, for example, if it concerns dealumination by steam treatment or by acidic treatment, and/or it may affect the surface of the zeolite, for example (i) by proton exchange with alkaline type cations, (ii) by depositing an inert phase on the surface of the zeolites.
The preferred operating conditions are those in routine use for oligomerizing olefins by solid acid type catalysts:
• a temperature in the range 100°C to 300°C;
• a pressure in the range 0.1 to 7 MPa;
• an HSV (hourly space velocity, expressed as the ratio of the volume feed flow rate to the volume of catalyst contained in the reaction zone) in the range 0.01 to 100
The reactor of the invention is particularly suitable for olefin oligomerization reactions, but it may more generally be used for any type of exothermic or endothermic reaction, occurring in the gas and/or liquid phase, which necessitates fine control of the temperature profile in each reaction zone, in particular reactions for addition of an olefin to another compound present in the feed, for example an olefin, a sulphur-containing compound, a nitrogen-containing compound, an aromatic molecule, said addition reactions being aimed at increasing the molecular weight of said compound, in particular the alkylation of thiophene compounds by olefins, and olefin metathesis. The reactor of the invention may also be used for skeletal isomerization of light olefins such as olefins, containing 4 or 5 carbon atoms.
In the case of exothermic reactions, the thermal cooling fluid (refrigerant) may be any fluid that can carry out heat exchange under good conditions, in particular by keeping a mean temperature difference between the reaction fluid and the cooling fluid of at least 5°C and preferably at least 10°C.
The invention is not connected to a particular cooling fluid or heating fluid.
EXAMPLE, in accordance with the invention
This example concerns oligomerizing an unsaturated C3 cut on a bed in a reactor in accordance with the invention such as that shown in Figure 1.
The reactor comprised two reaction zones Zb (initial zone 3b) and Za (final zone 3a) in series, separated by an intermediate zone comprising the water cooling system constituting the heat exchanger 8.
The feed and catalyst moved in counter-current mode.
A dealuminated mordenite type zeolite with a Si/Al molar ratio of 57 was tested for the propene oligomerization reaction after forming into beads with an alumina binder. The catalyst used was formed into 3 mm diameter spherical beads.
The feed used for said test was a feed derived from steam cracking which contained 94% by weight of propene and 6% by weight of propane.
The conditions were selected to optimize formation of the diesel cut in the product oligomerate.
The volume flow rate of feed per volume of catalyst (HSV) was calculated as a function of the total mass of catalyst in the two reaction zones. Fresh and regenerated catalyst was made up so as to maintain stable conversion in the two reaction zones.
20% of the used catalyst from the upper reaction zone was withdrawn and replaced with an identical quantity of regenerated catalyst to increase the catalyst activity in the lower reaction zone.
The temperature of the cooling liquid was adjusted so that the reaction temperature at the inlet to the second reaction zone was 210°C. The cooling fluid used was water, introduced at 25°C.
The results obtained are shown in Table 1.
Using the reactor of the present invention, in particular for oligomerizing C3 - C6 olefinic feeds, provides several major advantages:
• the reactor is compact but the catalytic volume is high, and the heat exchanger is
integral. Its cost and its installation costs are relatively low;
• in a variation, makeup of fresh or regenerated catalyst at zone Zb produces at least partial re-equilibration of the catalytic activity between the reaction zones, which favours the diesel cut yield;
• in a variation the system for continuous regeneration of part of the catalyst can allow operation without having to stop the unit to change the catalyst;
• the heat exchange zone located between the two reaction zones can improve the
temperature homogeneity in the two reaction zones.
1. A reactor which is elongate along a substantially vertical axis, said reactor comprising, in the same shell, a plurality of vertically staged catalytic reaction zones, said reactor being adapted to axial motion of a reaction fluid in series in each of said zones, and comprising means (100) for introducing and means (101) for evacuating said reaction fluid, means (102) for supplying fresh or regenerated catalyst to the reactor head, and means (105) for evacuating used catalyst from the lower portion of the reactor, said reactor comprising in particular: an upper reaction zone Za (3 a) filled with granular catalyst, with a cross section which is substantially identical to that of the shell over part of its height, connected directly via a contracted zone to a reaction zone Zb (3b) which is also filled with granular catalyst and with a cross section that is substantially identical to that of the shell over part of its height, located just below the upper reaction zone Za, said reaction zones Za and Zb being two successive reaction zones connected directly via a passage for reaction effluents, and via a passage for catalyst from the zone Za to the zone Zb through said contracted zone, zone Za being directly or indirectly connected at its upper portion to said means (102) for supplying fresh or regenerated catalyst, zone Zb being connected at its lower portion, directly or indirectly, to said means (105) for evacuating used catalyst, the reactor also comprising, disposed at the contracted zone between said contracted zone and the shell of the reactor, a heat exchanger (8) for heating or cooling reaction fluid moving between zones Za and Zb.
2. A reactor according to claim 1, in which zone Za comprises, at its lower portion, a substantially conical convergent comprising perforations for the passage of reaction fluid, connected to a channel (2b) with a reduced diameter with respect to that of the reactor, said channel defining at least a portion of the contracted zone.
3. A reactor according to claim 2, in which said channel (2b) has a diameter in the range 1% to 50% of the diameter of the reactor at the contracted zone.
4. A process for chemical conversion of hydrocarbon feeds in a reactor according to any one of claims 1 to 3.
5. A process according to claim 4 for oligomerizing olefinic feeds containing 2 to 12 carbon atoms.
6. A process according to claim 5, in which the pressure is in the range 0.1 to 10 MPa, the temperature is in the range 40°C to 600°C, the hourly space velocity HSV is in the range 0.01 to 100 h-1 and in which the catalyst moves in each reaction zone at a rate in the range 1 cm/hour to 200 cm/hour.
7. A process according to any one of claims 4 to 6, m which the operating conditions: temperature, pressure, HSV, are selected in a manner that limits the variation in temperature in each of the reaction zones to one or more values in the range 2°C to 50°C.
|Indian Patent Application Number||1629/CHE/2005|
|PG Journal Number||44/2011|
|Date of Filing||09-Nov-2005|
|Name of Patentee||INSTITUT FRANCAIS DU PETROLE|
|Applicant Address||1 & 4, AVENUE DE BOIS-PREAU F-92852 RUEIL MALMAISON CEDEX|
|PCT International Classification Number||C07C51/25|
|PCT International Application Number||N/A|
|PCT International Filing date|