EP1242569A1

EP1242569A1 - Method and device for catalytic cracking comprising in parallel at least an upflow reactor and at least a downflow reactor

Info

Publication number: EP1242569A1
Application number: EP00983393A
Authority: EP
Inventors: Renaud Pontier; Patrick Leroy; Jean-Paul Lepage; Marcellin Espeillac
Original assignee: IFP Energies Nouvelles IFPEN
Current assignee: IFP Energies Nouvelles IFPEN
Priority date: 1999-12-14
Filing date: 2000-11-28
Publication date: 2002-09-25
Anticipated expiration: 2020-11-28
Also published as: MXPA02005794A; WO2001044409A1; ZA200204751B; JP2003517088A; US7220351B1; EP1242569B1; FR2802211A1; ES2359623T3; FR2802211B1; JP4671089B2; ATE497527T1; DE60045600D1

Abstract

An apparatus and a process for catalytic cracking of a hydrocarbon feed is described, carried out in at least two reaction zones, one ( 30 ) operating in catalyst riser mode, wherein the feed and catalyst from regeneration zone ( 3 ) are circulated from bottom to top, the first gases produced are separated from the coked catalyst in a first separation zone ( 38 ), the catalyst is stripped ( 40 ), a first cracking and stripping effluent ( 42 ) is recovered and the coked catalyst is recycled ( 45 ) to the regeneration zone. Catalyst ( 12 ) from regeneration zone ( 3 ) and a hydrocarbon feed ( 19 ) are introduced into the upper portion of a dropper reaction zone ( 16 ), the catalyst and feed being circulated from top to bottom, the coked catalyst is separated from the second gases produced in a second separation zone ( 20 ), the second gases ( 24 ) produced are recovered and the coked catalyst is recycled ( 25 ) to the regeneration zone.

Description

CATALYTIC CRACKING PROCESS AND DEVICE INCLUDING PARALLEL AT LEAST ONE ASCENDING FLOW REACTOR AND AT LEAST ONE DESCENDING FLOW REACTOR.

The present invention relates to a process and a catalytic cracking device (FCC) in entrained bed comprising reactors in parallel comprising at least one downflow reactor (dropper) and at least one upward catalyst reactor (commonly called riser) from at least one regeneration zone.

The evolution of refining is marked more and more by the flexibility required of the units from the point of view of the loads to be treated but also by the versatility of the effluents produced.

This is how the FCC had to evolve to accept increasingly heavy loads (conradson carbon up to 10 and d ¹⁵ up to 1.0, for example) and that at the same time it was asked to increase its yield in petrol cutting, but also in propylene, the need for which increased in petrochemicals.

The specific characteristics of catalytic cracking units comprising a double regeneration with injection of the charge in the form of fine droplets met the need to work on heavy cuts.

More recently, and in the same direction, has been added to this unit a heat extraction module (catcooler exchanger), allowing by its extraction of calories to treat loads without high limit of conradson carbon. Still with the same objective of processing heavy load, the concept of a descending reactor with a short residence time (0.1 to 1 second) has been developed and patented, making it possible to achieve severe cracking conditions (for example high temperature up to at 650 ° C and high catalyst circulation - mass ratio of catalyst to charge or C / O from 10 to 20 -) The severe cracking conditions make it possible to maximize the conversion. However, in order to obtain good selectivity, it becomes essential to control and limit the residence time of the hydrocarbons in the reactor to prevent thermal degradation reactions from becoming preponderant (excessive production of coke, loss of recovered products by over-etching) . The contacting of the hydrocarbons with the catalyst must be carried out correctly with a limited contact time between the catalyst and the hydrocarbons. The descending reactor, combined with a appropriate mixing system, as described in patent PCT / FR97 / 01627, makes it possible to optimize selectivities in upgraded products (LPG, gasolines) by minimizing the non-upgraded products such as coke and dry gases compared to a technology conventional.

To meet the objective of flexibility, the idea then appeared to combine a traditional riser with a dropper with short residence time. Patent application FT98 / 14319 describes a chain of a dropper and a riser in series. It describes in detail the advantages of a second reactor which is operated under very different conditions in temperature and C / O of the main riser: in particular, this second reactor advantageously represents an additional capacity for treating a heavy load in producing a minimal amount of coke compared to a conventional reactor; it also becomes possible to crack certain cuts (called recycles) from the main riser that are not desirable (low recovery or cuts that do not meet certain specifications such as sulfur or aromatic contents) in order to maximize the yield of recovered cuts (LPG, petrol) . In an example of this patent, the fresh charge is introduced at the bottom of the riser and it is the LCO produced from the riser which is introduced as the charge for the dropper. Such a configuration makes it possible to maximize the gasoline yield by exhausting the LCO under relatively severe cracking conditions. But the drawback of this system with a dropper and a riser in series is that for a large load capacity at the dropper, the ascending reactor works with a non-negligible amount of catalyst partially deactivated by its passage through the dropper (deactivation coming from the deposit of coke on the catalyst). This results in a reduced efficiency which does not allow to draw the full potential of this association. The other configuration patented by Stone and Webster is that of installing two risers in parallel by working from regenerated catalyst in a common regeneration zone. Several types of recycle interconnections are possible between the two risers, but these are substantially similar cracking conditions (C / O, outlet temperature and residence time) which do not allow one of the risers to be treated really refractory cut and subject to cracking under severe conditions (for example, HCO). Thus, according to US patent 5009769 there is described a unit comprising two catalytic reactors with ascending flow operating in parallel, in which circulates regenerated catalyst in a regeneration zone comprising two regenerators. This unit would be suitable for treating a wide variety of feeds, but it operates under substantially identical catalyst circulation conditions (C / O = 5 to 10 and residence time 1 to 4 s for the first reactor and C / O = 3 to 12 and residence time 1 to 5 s for the second reactor). Under these conditions, the range of products obtained by each of the two reactors is substantially the same. US Patent 4116814 also illustrates the case of two reactors with upward flow in parallel, connected to a particle regenerator.

The idea that is presented in this patent is to draw the full potential of a parallel association of a riser working under conventional cracking conditions (for example, C / O from 5 to 7; outlet temperature of 510 at 530 ° C; residence time 1 to 2 s) and a dropper working under severe cracking conditions (for example, C / O from 10 to 20; exit temperature from 560 to 620 ° C; stay from 0.2 to 0.5 s). This association makes it possible to recycle HCO or LCO produced at riser when dropped, which are refractory charges difficult to crack in order to maximize gasoline production. But it also makes it possible to maximize the production of olefins and in particular of propylene by recycling to dropper the petrol or even only a fraction of the petrol (heavy or light) produced at the riser.

An object of the invention is to remedy the drawbacks of the prior art.

Another object is to crack both heavy and light hydrocarbons under reaction conditions which are severe, in a reactor adapted to this type of conditions, the dropper or downflow reactor and much less severe in a riser or reactor. upward flow so as to favor the formation of very different products meeting the specificities of each type of reactor.

It has been found that it is thus possible to obtain simultaneously, for example more propylene by means of a downflow reactor operating in severe catalytic cracking conditions and more gasoline thanks to an upward flow reactor operating in less severe cracking conditions, economically, from a cracking unit comprising at least one catalyst regeneration stage and the combination said reactors implemented in parallel on at least one regenerator.

More specifically, the invention relates to a process for catalytic cracking in a entrained or fluidized bed of at least one charge of hydrocarbons in at least two reaction zones, at least one of which is of upward flow, into which the charge is introduced and catalyst from at least one regeneration zone in the lower part of the upward flow reaction zone, the charge and the catalyst are circulated from bottom to top in said zone, the first gases produced from the coke catalyst are separated in a first separation zone, the catalyst is stripped by means of a stripping gas, a first cracking and stripping effluent is recovered and the coke catalyst is recycled in the regeneration zone and it is at least partly regenerated by means of '' an oxygen-containing gas, the process being characterized in that catalyst is introduced from at least one regeneration zone and a hydrocarbon charge e in the upper part of at least one reaction zone with downward flow, the catalyst and said charge are circulated there from top to bottom under appropriate conditions, the coke catalyst is separated from the second gases produced in a second separation zone, the second gases produced are recovered and the coke catalyst is recycled to the regeneration zone.

According to one characteristic of the process, the temperature of the catalyst leaving the descending reactor can be higher than that leaving the ascending reactor.

According to another advantageous characteristic, the catalyst originating from the second separation zone can be stripped by means of a recycling gas which is usually steam and the resulting hydrocarbons are generally recovered with the cracking gases. It is preferable to regenerate the coke catalyst in two consecutive regeneration zones, each of which has its own combustion gas discharge resulting from the regeneration of the coke catalyst. The catalyst to be regenerated from the first separation zone is introduced into a first regeneration zone operating at an appropriate temperature, the catalyst thus at least partially regenerated being sent to the second regeneration zone operating at a higher temperature and the catalyst regenerated from the second regeneration zone is introduced into the upward flow reaction zone and into the downflow reaction zone.

The coke catalyst from the second separation zone can be recycled in the first regeneration zone either by gravity flow, generally in the dense zone, or by flow by means of a riser comprising fluidizing air as engine ( lift), usually in the diluted area of the first regeneration area.

It may be advantageous to recycle the catalyst originating from the second separation zone into the second regeneration zone by means of a lift, either in its dense zone or in its diluted zone.

The hydrocarbon feedstock or each of the feedstocks, if they are different, can be introduced into the upward reaction zone and into the downward reaction zone by a co-current injection of the catalyst flow or against the current, or against the current. current for one and co-current for the other. However, an injection against the current in the two zones seems preferable for better vaporization of the droplets introduced.

The operating conditions for catalytic cracking of the charges are usually as follows:

- In the ascending reaction zone (RA): • catalyst temperature (RA outlet): 480 ° -600 ° C and preferably 500-550 ° C.

• catalyst / feed (C / O): 4-9 and preferably 5-7.

• residence time: 0.5-4 s, preferably 1 -2 s

- In the descending reaction zone (RD): • catalyst temperature (RD outlet) = 500-650 ° C, preferably 560-620 ° C;

. C / O: 8-20, preferably 10-15;

• residence time ; 0.1-2 s, preferably 0.2-1 s The charge supplying each of the reaction zones can be a so-called fresh charge, a recycle of part of the products from a downstream fractionation or a mixture of of them.

The charge of one of the reaction zones can be either heavier or lighter than that circulating in the other zone. More particularly, the charge of the upward flow reaction zone can be a vacuum distillate or an atmospheric residue or a recycle of part of the products from the downward reaction zone and the charge of the downflow zone is a non-charge. cracked or recycled part of the products from the bottom-up reaction zone and preferably a petrol cut or an LCO cut.

According to a characteristic of the process, the feed rate and for example of recycle flow (LCO cut, HCO or gasoline) circulating in the descending reactor can represent less than 50% by weight of the feed rate to be converted in the upward reaction zone.

The advantages of the configuration according to the present invention are as follows:

- The possibility of processing by the dropper loop any fresh or recycled load under severe cracking conditions independent of the cracking conditions of the riser.

- The operational simplicity of the dropper loop since it is independent of the riser loop.

- The simplicity of implementation of the dropper loop since it can be placed anywhere around the regenerator, provided that the pressure balance is satisfied. This would be practically impossible to achieve with a second riser, parallel to the first because the pressure balance imposes in this case a minimum height, therefore a residence time which cannot drop to the typical values of a dropper (less than the second). In other words, it is very difficult in practice to really differentiate the cracking conditions of two risers operating in parallel. - The dropper loop can be adapted to most existing cracking units, to one or two regenerators and / or with a technology of separation, stripping and transfer of the catalyst best suited to the requirements of the client. - Optimization of the selectivities in upgraded products (LPG, gasolines) thanks to the technology of the descending reactor by minimizing the selectivities in non-upgraded products such as coke and dry gases compared to a conventional technology while maximizing the conversion thanks to obtaining very severe severity conditions when dropped. - Each reactor (dropper, riser) works with freshly regenerated catalyst.

- There is independence of the operating conditions of each reactor, in particular in terms of C / O, which is not the case in the series configuration. - There is no problem in regulating the cracking conditions specific to each reactor in terms of reactor outlet temperature since there is no longer coupling as in the series reactor configuration.

- The production of a catalyst cooling effect due to the dropper loop. Indeed, for a given charge, there is from a certain level of circulation in the dropper (C / O) a heat extraction effect, that is to say a decrease in temperatures at the regenerator, or to the first or to the second regenerator if it is a double-stage regeneration structure depending on the regenerator to which the return of the coke catalyst from the dropper takes place. In fact, the technology of the descending reactor makes it possible to minimize the amount of coke formed. This therefore results in a much lower coke content on the catalyst than in an equivalent ascending reactor. Combined with suitable operating conditions where the catalyst circulation is higher compared to the same amount of feed (high C / O), the coke content is therefore reduced very significantly so that the amount of heat given off by the combustion of this additional coke in the regenerator (s) is much less than the quantity of heat consumed by the vaporization of the feedstock and the heat of reaction in the dropper reactor. Overall, the catalyst on the regeneration side is cooled compared to the previous situation comprising only one traditional riser.

This heat extraction effect, which can be obtained in an equivalent manner by a regeneration side heat exchanger (catcooler) or by the vaporization of an almost chemically inert recycle (TCM) downstream of the charge injection into the direction of flow of the catalyst in a riser or dropper reactor, makes it possible either to treat charges with a higher carbon Conradson, or to increase the charge rate, or to take advantage of the decrease in temperature at the regenerator (s) ) to increase the circulation of catalyst (C / O) at the riser and the dropper. In fact, the heat necessary for the reaction and for vaporization on the reaction side is supplied by the regenerated catalyst, heated by combustion of the coke to the regenerator (s). In order to maintain a constant reactor outlet temperature, the heat extraction effect requires increasing the circulation of catalyst at a constant charge rate and therefore benefiting from better catalytic activity (more active sites). We can also treat more refractory charges in the dropper.

For all these reasons, the combination of a riser and a dropper in parallel on a common regeneration device is very interesting, both in the renovation of existing units (revamping) and in the construction of new units.

The invention also relates to a catalytic cracking device in a entrained or fluidized bed of a hydrocarbon feedstock comprising: - At least one substantially vertical ascending reactor having a lower inlet and an upper outlet:

a first means for supplying regenerated catalyst connected to at least one coke catalyst regenerator and connected to said lower inlet; - a first means for supplying the load disposed above the lower inlet of the ascending reactor;

a first enclosure for separating the coke catalyst and a first gaseous phase connected to the upper outlet of the ascending reactor, said separation enclosure comprising a chamber for stripping the catalyst and having an upper outlet for a gaseous phase and an outlet lower of coke and stripped catalyst, said lower outlet being connected to the catalyst regenerator via first means for recycling the catalyst; the device being characterized in that it comprises at least one substantially vertical descending reactor having an upper inlet and a lower outlet;

a second means for supplying regenerated catalyst connected to said coke catalyst regenerator and connected to said upper inlet of the descending reactor; a second means for supplying the load disposed below the second supply means;

a second enclosure for separation of the coke catalyst from a second gas phase connected to the lower outlet of the descending reactor and having an outlet from the second gas phase and an outlet from the coke catalyst, and second means for recycling the coke catalyst connected to said catalyst outlet from the second separation enclosure and connected to the regenerator.

According to a variant of the device, the second enclosure for separating the catalyst from the cracking effluents may not include a stripping chamber. In this case, prestripage means for example by water vapor can be introduced into the separation enclosure and the evacuation of the vapor can be carried out with the cracking and prestripage effluents.

According to another variant, the second separation enclosure comprises a catalyst stripping chamber with injection of stripping vapor, in communication with it, like that described for example in the patent application of the Applicant FR 98 / 09.672 incorporated as reference. Cracking and stripping effluents are generally removed by common means.

According to another advantageous characteristic of the device, it can comprise two superposed regenerators of coke catalyst, the second being located above the first, means for circulating the catalyst from the first regenerator to the second regenerator. The said first and second catalyst supply means are connected to the second regenerator and the lower outlet of the first separation enclosure is connected to the first regenerator via the first recycling means.

The invention will be better understood from the attached figure which illustrates a particularly advantageous embodiment of the device comprising two superimposed coke catalyst regenerators, connected in parallel to two catalytic cracking reactors, one with upward flow (riser) and the another with downward flow of catalyst (dropper). According to the figure, a regeneration zone (1) of the coke catalyst comprises two regeneration chambers (2) and (3) superimposed in which the catalyst is regenerated in a fluidized bed, air being introduced at the base of each chamber by means not shown in the figure. Each enclosure has its own dedusting means (4, 5) (cyclones) and evacuation (9, 10) of the coke combustion effluents. The pressure in each enclosure (2) and (3) can be controlled by valves located on the lines allowing the evacuation of the combustion effluents at least partially dusted. The catalyst is transported between the two enclosures by means of a lift column (6). Air, generally introduced at the base by an injector (7), at a sufficient speed makes it possible to transport the catalyst between the two enclosures. Typically, the proportion of air required for regeneration is 30 to 70% in the lower enclosure (2) operating at a lower temperature (670 ° C for example) and 15 to 40% in the upper enclosure (3 ) operating at a higher temperature (770 ° C for example), 5 to 20% of air circulating in the lift to transport the catalyst. A valve on solid (8), of the plug valve type makes it possible to control the flow of circulation between the chambers (2) and (3). The substantially regenerated catalyst from the second regenerator located above the first (3) is sent from a dense bed (11) into a disengagement well (13) by a conduit (12) inclined at an angle usually between 30 and 70 degrees from the horizontal. In the well (13), the circulation of the catalyst is slowed down to allow any gas bubbles to be evacuated towards the second regeneration enclosure (3) through a pressure equalization line (14). The catalyst is then accelerated and descends through a transfer tube (15) to the entry of a downflow reactor (16). Throughout its journey from the regeneration enclosure, the catalyst is kept in the fluidized state by the addition of small quantities of gas throughout the transport. If the catalyst is thus maintained in the fluidized state, this makes it possible to obtain a pressure at the inlet of the dropper greater than that of the fumes from the external cyclones (5).

The dropper (16) comprises means for introducing the regenerated catalyst (17) which can be a valve on solid, an orifice or simply the opening of a conduit, in a contacting zone (18) located under the valve (17), where the catalyst meets countercurrent for example, the hydrocarbon charge, introduced by injectors (19), generally consisting of atomizers where the charge is finely divided into droplets thanks to the introduction of auxiliary fluids such as water vapor. The means for introducing the catalyst are located above the means for introducing the charge. Between the contacting zone (18) and the means for separating the hydrocarbons from the catalyst (20), it is possible optionally to have a reaction zone (21), of substantially elongated shape, shown vertically in the figure but this condition is not exclusive. The average residence time of the hydrocarbons in zones (18) and (21) will, for example, be less than 650 ms, preferably between 50 and 500 ms. The dropper effluents are then separated in the separator (20), for example as described in application FR98 / 09672 incorporated as a reference where the residence time must be limited as much as possible. The gaseous effluents (cracked gases) from the separator can then undergo an additional dusting step through cyclones, for example external cyclones (22) arranged downstream on a line (23). These gaseous effluents (cracked gases) are discharged through a line (24). It is also possible to cool the gaseous effluents, in order to limit the thermal degradation of the products, by injecting for example liquid hydrocarbons in the effluent leaving for example cyclones (22) by the line (24) or directly at the outlet of the cracked gases from the separator (20) upstream of said cyclones. The catalyst separated in the separator (20) is then either reinjected directly at the base of a riser (25) through a conduit (26), a valve (27) of which controls the flow rate in relation to the outlet temperature of the dropper. , or introduced into a fluidized bed (28) of stripping through a conduit or an opening (30). The catalyst in the fluidized bed (28) then undergoes stripping (contact with a light gas such as water vapor, nitrogen, ammonia, hydrogen or even hydrocarbons, the number of carbon atoms is less than 3) by means which are well described in the prior art before being transferred to the riser (25) through the conduit (26). The stripping gas effluents are generally evacuated from the fluidized bed (28) through the same means (23, 22) which allow the evacuation of the gaseous effluents from the dropper (16) by the line (24). The coke catalyst is raised by a fluidizing gas (29) in the dense fluidized bed of the second regenerator (3).

The riser reaction zone (30) is a substantially elongated tubular zone, many examples of which are described in the prior art. In the example given in the figure, the hydrocarbon charge is introduced by means (31), generally consisting of atomizers where the charge is finely divided into droplets, generally using the introduction of auxiliary fluids such as water vapor, introduced through the means (31). The means for introducing the catalyst are located below the means for introducing the charge. The feed introduction is located above the catalyst inlet.

These means for introducing the catalyst into the riser (30) comprise a withdrawal well (32) conforming to that (13) which supplies the dropper, connected to the dense bed of the second catalyst regenerator (3) by a conduit (33). inclined at substantially the same angle as that of the conduit (12). The well (32) is furthermore connected to the diluted fluidized bed by a pressure equalization line (34). At the base of the well, a line (35) first vertical then inclined is connected to the lower part of the riser. A control valve (36) arranged on the line (35) regulates the flow rate of regenerated catalyst at the inlet of the riser as a function of the catalyst outlet temperature and of the effluents at the top of the riser. Fluidizing gas introduced at the base of the riser by injection means (37) circulates the catalyst cocurrently with the charge in the riser. According to a variant not shown, the charge could have been injected against the current of the downward flow of the riser. Above the charge injectors, an injection of a light cut of hydrocarbons or a heavier cut (LCO or HCO for example), coming from a distillation downstream of the riser cracking effluents, can be carried out in this riser. The cut introduced can represent 10 to 50% by weight of the load introduced into the riser and can contribute to maximizing the production of gasoline. The cracking reaction takes place in the riser. The cracked effluents are then separated in a separator (38), for example as described in PCT application FR 98/01866 incorporated as a reference. The catalyst resulting from the separation is then introduced into a fluidized bed (39) of a stripping chamber (40) located below the separator, through conduits (41) or openings. The catalyst in the chamber (39, 40) is then stripped (contact with a light gas such as water vapor, nitrogen, ammonia, hydrogen or even hydrocarbons with a number of carbon atoms less than 3) by means not shown in the figure. The stripped catalyst is then transferred to the dense bed of the first regeneration enclosure (2) by a conduit (45). The gaseous effluents from cracking and stripping separated in the separator (38) are discharged through a conduit (42) to a secondary separator (43) such as a cyclone, for example internal to the chamber (39, 40) before be directed to the downstream fractionation section by a conduit (44).

By way of example and to illustrate the invention, a comparison has been made of the results obtained by an industrial unit provided with a conventional ascending reactor treating a heavy load and equipped with a double regeneration system as described in the figure with the results obtained by inserting a descending reactor in parallel, this new reactor then being supplied by two sections, different in each example, produced by the ascending reactor.

The results of this comparison are based on industrial results obtained with the unit with the riser and pilot tests of ^'cracking the reporting cut. The new conditions enabling the thermal balance of the unit as a whole to be satisfied are recalculated with a process model.

The fresh charge (vacuum distillate) has the following characteristics: - Density d ¹⁵ : 0.937 - Sulfur content: 0.5%

- Conradson carbon: 5.8%

It is injected at the base of a riser which is supplied with catalyst from a double regeneration device, in accordance with the figure presented in the present invention. This catalyst, based on Y zeolite has the following characteristics:

- Grain size: 70 micrometers

- BET surface (m ² / g): 146

- Zeolitic area Y (m ² / g): 1 1 1 - Area of the matrix (m ² / g): 35

The catalyst comes from the second regenerator.

The cracked effluents are distilled and part of the HCO cut obtained as well as all of a heavy gasoline cut (170 ° C-200 ° C) are recycled into the riser. This recycle, consisting of 49.3% HCO and 50.7% of heavy petrol cut, represents 27.1% by weight of the fresh charge at the riser. An additional cut is recycled as feed to the dropper which is in turn fed with catalyst from the second regenerator.

The coke catalyst from the stripper connected to the riser is recycled in the dense phase of the first regenerator while that from the stripper connected to the dropper is recycled by means of a lift in the dense phase of the second regenerator.

Example 1:

In this first example, 23.4% by weight of the gasoline cut produced at the riser, or 10% by weight relative to the fresh charge at the riser, is recycled as charge in the dropper.

The conditions are maintained at the riser (ROT and recycles) by increasing the C / O of the riser.

We note: RA = ascending reactor (residence time: 1 s)

RD = descending reactor (residence time: 0.4 s) REG1 = first regeneration enclosure REG2 = second regeneration chamber

It is found that propylene can be produced in substantial quantity (53% more) by a really severe cracking with a dropper, while maintaining a satisfactory fuel yield. In addition, the temperature of the second regenerator dropped by 21 ° C (catcooler effect). A gain in conversion of the fresh charge of 1.9% is obtained by exhausting the LCO and slurry.

Example 2:

In this second example, 99.7% by weight of the HCO cut (or slurry), or

10% weight compared to the fresh load, is recycled as a load in the dropper.

We note: RA = rising reactor

RD = descending reactor

REG1 = first regeneration chamber

REG2 = second regeneration chamber

It can be seen that the HCO (slurry) can be converted substantially (57% conversion) by a really severe cracking with the dropper, while keeping the overall coke yield of the unit quite low. Furthermore, the temperature of the second regenerator dropped by 11 ° C (catcooler effect), a gain in conversion of the fresh charge of 4.8% is obtained by exhausting the slurry, leading to better yields of recoverable products (more than 1.5% of LPG and 2.3% more petrol),

Claims

1 - Process for catalytic cracking in a entrained or fluidized bed of at least one charge of hydrocarbons in at least two reaction zones, at least one (30) being of upward flow, into which the charge (31) is introduced and catalyst (35) coming from at least one regeneration zone (3) in the lower part of the upward-flow reaction zone, the charge and the catalyst are circulated from bottom to top in said zone, the first gases are separated coke catalyst products in a first separation zone (38), the catalyst is stripped (40) by means of a stripping gas, a first effluent (42) from cracking and stripping is recovered and the (45) is recycled catalyst coke in the regeneration zone and it is regenerated at least in part by means of an oxygen-containing gas, the process being characterized in that catalyst (12) is introduced from at least one zone ( 3) regeneration and charge (19) hydrocarbon in the upper part of at least one reaction zone (16) with downward flow, the catalyst and said charge are circulated there from top to bottom under appropriate conditions, the coke catalyst is separated from the second gases produced, in a second separation zone (20), the second gases (24) produced are recovered and the coke catalyst is recycled (25) in the regeneration zone,

2 - Process according to claim 1, in which the temperature at the outlet of the descending reactor is higher than that at the outlet of the ascending reactor,

3 - Method according to one of claims 1 and 2 wherein the catalyst from the second separation zone is stripped by means of a stripping gas,

4 - Method according to one of claims 1 to 2, wherein the catalyst is regenerated in two consecutive regeneration zones, the catalyst to be regenerated from the first separation zone is introduced into a first regeneration zone operating at an appropriate temperature , the catalyst thus at least partially regenerated being sent to the second regeneration zone operating at a higher temperature and the regenerated catalyst coming from the second regeneration zone is introduced into the upward flow reaction zone and into the downflow reaction zone,

5 - Process according to claim 4 in which the catalyst from the second separation zone is recycled in the first regeneration zone,

6 - Process according to claim 5 in which the catalyst is recycled in the dense zone of the first regeneration zone,

7 - Process according to claim 5, in which the catalyst is recycled in the diluted zone of the first regeneration zone by means of a lift,

8 - Process according to claim 4, in which the catalyst from the second separation zone is recycled into the second regeneration zone by means of a lift,

9 - Method according to one of claims 1 to 8, in which the charges are introduced into the upward reaction zone and into the downward reaction zone by an injection against the flow of the catalyst flow,

10 - Method according to one of claims 1 to 9, in which the operating conditions are the following:

- in the ascending reaction zone (AR):

• catalyst temperature (RA outlet): 480 ° -600 ° C and preferably 500-550 ° C,

• catalyst / feed (C / O): 4-9 and preferably 5-7, • residence time: 0.5-4 s, preferably 1 -2 sec,

- in the descending reaction zone (RD):

• catalyst temperature (RD outlet) = 500-650 ° C, preferably 560-620 ° C;

• C / O: 8-20, preferably 10-15; • residence time: 0.1-2 s, preferably 0.2-1 sec, 11 - Method according to one of claims 1 to 10, wherein the charge feeding each of the reaction zones is a non-cracked charge called fresh, a recycle of part of the products from a fractionation downstream or a mixture of the two ,

12 - Process according to claim 1 1 in which the charge of the reaction zone with ascending flow is a vacuum distillate or an atmospheric residue or a recycle of part of the products from a fractionation downstream and in which the charge of the downflow zone is an uncracked charge or a recycle of part of the products from a downstream fractionation and preferably a gasoline cut or an LCO cut,

13 - Device for catalytic cracking in a entrained or fluidized bed of a hydrocarbon charge comprising:

- at least one substantially vertical rising reactor (30) having a lower inlet and an upper outlet:

- a first means (35) for supplying regenerated catalyst connected to at least one regenerator (3) of coke catalyst and connected to said lower inlet;

- a first means (31) for supplying the load disposed above the lower inlet of the ascending reactor;

- A first enclosure (38) for separating coke catalyst and a first gas phase connected to the upper outlet of the rising reactor (30), said separation enclosure comprising a chamber (40) for stripping the catalyst and having an upper outlet a gaseous phase and a lower outlet for coke and stripped catalyst, said lower outlet being connected to the catalyst regenerator via first means (45) for recycling the catalyst, the device being characterized in that it comprises:

- at least one substantially vertical descending reactor (16) having an upper inlet and a lower outlet;

- a second means (12) for supplying regenerated catalyst connected to said regenerator (3) of coke catalyst and connected to said upper inlet of the descending reactor; - a second means (19) for supplying the load disposed below the second means (12) for supplying;

- A second enclosure (20) for separating the coke catalyst from a second gas phase connected to the lower outlet of the descending reactor and having an outlet from the second gaseous phase and an outlet from the coke catalyst;

- and second means (25) for recycling the coke catalyst connected to said catalyst outlet of the second separation enclosure and connected to the regenerator,

14 - Device according to claim 13, in which the second separation enclosure comprises a catalyst stripping chamber in communication with the latter,

15 - Device according to one of claims 13 and 14 comprising two regenerators (2, 3) of consecutive coke catalyst, means for circulating the catalyst from the first regenerator (2) to the second regenerator (3) characterized in that said first and second means for supplying catalyst (35, 12) are connected to the second regenerator (3) and in that said lower outlet of the first separation enclosure is connected to the first regenerator via the first recycling means (45),

16 - Device according to claim 15, in which the second recycling means (2, 5) comprise a lift (29) connected to the second regenerator,

17 - Device according to one of claims 13 to 16, wherein the first and second catalyst recycling means each comprise a valve (27, 36) for adjusting the flow controlled by means of measuring the temperature of the catalyst in outlet of the ascending reactor and the descending reactor.