KR100281750B1 - Method and apparatus for preparing low molecular weight olefins - Google Patents

Abstract

The present invention is directed to a method and apparatus for catalytic conversion of hydrocarbons to low molecular weight olefins in a short catalytic circulating fluidized bed apparatus. The process of the present invention comprises supplying a hydrocarbon feedstock into the reaction zone 1 containing a solid catalyst, supplying the hydrocarbon in the reaction zone 1 under conditions that favor the catalytic conversion of hydrocarbons to low molecular weight olefins. Contacting the raw material with the catalyst, separating the reaction product obtained from the reaction zone 1 after the catalyst conversion, recovering the catalyst, and regenerating the deactivated catalyst in the regenerator 3. According to the invention, the hydrocarbon feedstock is contacted with the catalyst in a circulating fluidized bed reactor for a residual time of 0.1 to 3 seconds. The process of the present invention is used to produce propylene, butylene and pentene and higher octane, lower benzene gasoline fractions by catalytic conversion of LG0, HGO, VGO or naphtha using conventional or improved FCC catalysts. The process of the present invention is also used to produce propylene, isobutylene or isoamylene rich products by catalytic dehydrogenation from propane, isobutane or naphtha, respectively, using conventional or improved dehydrogenation catalysts for fluid bed feed. do.

Description

Method and apparatus for preparing low molecular weight olefins

Several commercially available methods for producing propylene, butylene or amylene from various petroleum based hydrocarbon feedstocks are now known. These methods include steam cracking, fluid bed catalyst cracking and dehydrogenation. Conventional methods suffer from some of the disadvantages presented below: Steam cracking: The main product of the steam cracking method is ethylene. Propylene and high molecular weight olefins are the most important byproducts and their yields cannot be substantially increased by changing operating conditions. Other by-products include fuel gases, aromatic tars and coke, which are harmful to the process and will have little or no value in use.

Conventional Fluidized Bed Catalyst Cracking (FCC): The yield of low molecular weight olefins and the main product component, FCC gasoline, is poor for future requirements due to low octane number, high benzene content, and high molecular weight olefins. In order to increase the formation of low molecular weight olefins, high temperatures and short residence times are required, but as described below, they are not practical in the reactor of the present invention. When the temperature is increased, the reaction becomes more endothermic and the temperature difference between the reactor and the regenerator decreases because the regenerator temperature cannot be increased without damaging the catalyst. In order to supply all the necessary energy, the ratio of catalyst to oil must be increased, or part of the energy must be transferred in other ways.

Catalytic Dehydrogenation: Hydrogenation of hydrocarbons occurs at relatively high temperatures. Dehydrogenation is a highly endothermic reaction that requires high and carefully controlled heat input into the reaction zone. This makes the reactor / regenerator design complicated and expensive.

Reactor types used in the hydrocarbon conversion process can be classified as follows:

1. Fixed bed reactor and

2. Fluidized bed reactor.

At very high fluidization rates, the bed surface is no longer clearly defined and is replaced by some area where the solids content decreases slowly with height. If the particles are fine, this leads to rapid fluidization, in which case solid entrainment occurs at a rate such that the fast fluidized bed is generally so fast that it can only be maintained by recycling of entrained solids through cyclones. This type of system is called a circulating fluidized bed (CFB).

One of the most widely used reactor systems is the FCC system, the main components of which are risers operating in the fast flow flow zone, high capacity reactors operating in the thin suspended phase and regenerators operating in the fluidized bed zone. Typically, this type of reactor system has a higher riser (30-40 m) compared to the regenerator, allowing the regenerator to be connected to the riser-reactor combination at a point located between the reactor top and the riser bottom. The riser must be clearly higher than the regenerator to ensure fluid vitality of the system. This establishes constraints on the method caused by residence time and equipment design. These limitations are not particularly desirable if the reactor requires short residence times and high solids concentrations. This sets limits on residence time and solids concentrations, and very short residence times or high solids concentrations cannot be achieved with FCC systems.

U.S. Patent No. 4,980,053 describes a process that uses a high molecular weight hydrocarbon fraction, such as vacuum gas oil, as a feedstock under milder operating conditions than the FCC's operating conditions and under relaxed operating conditions than steam cracking. Propylene and butylene are produced in higher yields than ethylene. This process, known as a deep catalyst cracking process (DCC), has been studied in pilot units and commercially adapted FCC units. This unit is an FCC unit that uses substantially different operating parameters and modified catalysts.

By using low hydrocarbon partial pressures, zeolite catalysts and reaction temperatures of 500 to 700 ° C., a process for converting saturated hydrocarbons to low molecular weight olefins, in particular propylene, is described in EP patent application 395,345. In the embodiment of the application, the method is carried out using a fixed bed reactor, so that the residence time can be kept short. However, the method can also be performed in a fluidized bed system. Conventional methods are claimed to be less expensive and more selective for propylene and butylene than conventional steam cracking.

However, the above mentioned reactor systems are severely limited in that their usefulness is limited, particularly in reactors, in methods where short residence times and high solids content are required. In this way, the riser should be in a lower position compared to the regenerator. At the same time, when the pressure difference between the regenerator and the riser is large, the problem becomes more serious. In this case, the regenerator cannot be connected to the riser cyclone. Instead, a complex system for circulating the catalyst is required. In practice, the reactor riser must be designed impractically high, in which case the gas velocity is so fast that the catalyst volume fraction in the riser is too low for optimum process conditions. FCC systems have a limitation that the catalyst volume fraction cannot be freely controlled without affecting other process variables.

The present invention relates to the preparation of low molecular weight olefins. In particular, the present invention provides for the preparation of low molecular weight olefins such as propylene, butylene and amylene from hydrocarbon feedstocks comprising, for example, low molecular weight, high molecular weight and vacuum gas oils, naphtha, propane, butane or low molecular weight condensates. The invention relates to a method according to the preamble of claim 1. The invention also relates to an apparatus according to the preamble of claim 17, which is suitable for producing low molecular weight olefins from said hydrocarbon feedstock.

The accompanying drawings are schematic diagrams of simplified processes for preferred embodiments of the present invention.

It is therefore an object of the present invention to solve the above mentioned drawbacks of the prior art and to provide a novel process and reactor system for the production of low molecular weight olefins from hydrocarbon feedstocks.

The present invention is based on the concept of performing catalytic conversion of hydrocarbon feedstock in a circulating fluidized bed (CFB) reactor using a short residence time. Preferably, the spent catalyst is also regenerated in a circulating fluidized bed (CFB) regenerator, and all the thermal energy required for the endothermic conversion reaction is supplied by recycled regenerated catalyst particles.

More specifically, the method according to the invention is characterized in that it is defined in the characterizing part of claim 1.

The reactor system according to the invention comprises one or more circulating fluidized bed units (reactors) for catalytic conversion of hydrocarbons, provided with feed nozzles for hydrocarbon feedstock and recycled catalyst particles. The CFB reactor is also provided with a cyclone or similar separator for separating spent catalyst from the product stream, which has a product outlet for low molecular weight olefins and a solids outlet for separated catalyst particles. The reactor system also includes one or more circulating fluidized bed units for catalyst regeneration by combustion provided with feed nozzles for spent catalyst to be regenerated, and a cyclone or similar separator for separating regenerated catalyst from flue gas of the combustion process. Include. The feed nozzle of the regenerator unit is connected to the solids outlet of the cyclone of the reactor unit.

More specifically, the reactor system according to the invention is characterized in that it is mainly defined in the features of claim 17.

[Justice]

Within the scope of the present invention, the terms "consumed catalyst" and "deactivated catalyst" are used interchangeably to refer to precipitated catalyst particles with coke or other impurities that lower catalytic activity.

The abbreviation “CFB” is used to denote a “circulating fluidized bed” that carries solids vertically by a high velocity gas stream in a vertical pipe. It is preferred that the CFB be equipped with a cyclone in which the solids separate from the gas stream. Often, a return pipe is also connected to the cyclone to recycle the solids. Such a return pipe represents a preferred embodiment of the CFB according to the invention, but the CFB unit described below can be operated without the return pipe. Surface gas velocities in the CFB reactor are typically from about 2 to about 10 m / s. The throughput of solids (catalyst particles) is very large at this gas velocity, minimizing the reactor diameter required. The surface gas velocity in the CFB regenerator is not critical because the catalyst can be recycled to achieve the desired residence time for catalyst regeneration.

"Low molecular weight olefin" means an olefin comprising 1 to 6 carbon atoms, preferably ethylene, propylene, butylene and pentene.

The term "short contact" when used in connection with feedstock to catalyst contact means a residence time of 0.1 to 3 seconds. Residence times of less than 2 seconds or less than 1 second, in particular less than 0.5 seconds are possible.

[Process Description]

Processes for catalytically converting hydrocarbons into low molecular weight olefins include the conventional steps of feeding a hydrocarbon feedstock into a reaction zone containing a solid catalyst. In the reaction zone, the hydrocarbon is contacted with the catalyst under conditions in which the hydrocarbon is advantageously catalytically converted to low molecular weight olefins. After the reaction, the resulting low molecular weight olefins and unreacted feedstock are separated from the catalyst particles. The spent and deactivated catalyst is recovered and regenerated in the regenerator by burning coke precipitated on the catalyst particles.

According to the invention, the hydrocarbon feedstock is contacted with the catalyst in a circulating fluidized bed (CFB reactor) and the residence time is between 0.1 and 3 seconds. The CFB system according to the invention is characterized in that: 1) the high capacity reactor is replaced by a riser equipped with a small external cyclone, and the reaction takes place only in the riser pipe; 2) It differs from conventional FCC systems in that the bubbling layer regenerator is replaced by a CFB regenerator. Both of these improvements provide enhanced residence time control and improved reactor configuration.

To date, circulating fluidized bed reactors (CFBR) have been used primarily in noncatalytic processes. However, also in the prior art, a circulating fluidized bed reactor (CFB) is known which produces maleic anhydride based on the catalytic oxidation of butane [Pugsley, T. et al., Ind. Eng. Chem. Res. 31 (1992), 2652-2660. As a drawback of the known CFB construction, it should be mentioned that the catalyst volume fraction of the reactor cannot be freely controlled without affecting other process variables. In addition, the prior art does not mention whether the same equipment can be used for cracking reactions or for preparing low molecular weight olefins.

According to the invention, the spent catalyst is separated from the product and hydrocarbon feedstock in an external cyclone connected to a CFB reactor. Preferably the regenerator comprises components similar to the reactor, such that regeneration of the spent catalyst can be carried out in the second circulating fluidized bed. However, other types of regenerators may be used.

According to the invention, two (or more) reactors can be arranged in series by using the product stream of the previous reactor as feed for subsequent reactors. The reactor of this embodiment can be operated at different temperatures and pressures, which allows the method of the present invention to be applied to a wide variety of hydrocarbon feedstocks.

According to one particularly preferred embodiment, in which the reactor system comprises a CFB reactor and a CFB regenerator, at least a portion of the separated deactivated catalyst comprises a first pipe ("exhausted catalyst pipe") connected to the lower end of the regenerator. Through the regenerator. The supply of deactivated catalyst into the regenerator is controlled by a valve connected to the feed nozzle of the pipe, preferably in such a way that at least a minimum amount of catalyst is present in the pipe to keep the pipe essentially airtight. The "plug" formed by the catalyst in the pipe will prevent all gas released from the reaction zone from entering the regenerator. This will eliminate the risk of explosion.

Within the scope of the present invention, all separated deactivated catalysts can be introduced into the regenerator without any internal reactor recycle.

The deactivated catalyst is advantageously regenerated by introducing hot flue gases from hot air and optionally addition fuel into the regenerator, thereby burning coke collected on the surface of the catalyst in the second circulating fluidized bed at 650 to 800 ° C. do. As mentioned above, other types of regenerators may also be used, such as conventional bubbling layer regenerators.

An important advantage of the reactor system of the present invention, which will be described in more detail below, is that the concentration of catalyst in the reactor can be maintained at a high level to ensure that the large catalyst surface is in contact with the hydrocarbon reactant. Thus, the reactor system according to the invention is preferably equipped with a second pipe ("catalyst recycle pipe") for recycling the separated catalyst back to the reactor by cyclone.

The flow ratio of the spent side solvents recycled and recycled depends on the hydrocarbon feedstock, feed rate, catalyst used and process conditions.

As in the case of using a CFB reactor, preferably a portion of the catalyst is recycled back to the CFB regenerator via the recycle pipe, while the remaining catalyst, ie the regenerator, is passed through the catalyst recycle pipe connected to the base of the CFB reactor. Flow to.

The present invention can be used to convert hydrocarbons to low molecular weight olefins under dehydrogenation conditions in addition to cracking conditions. The hydrocarbon feedstock used in the catalyst cracking in the present invention may be composed of low molecular weight gas oil (LGO), high molecular weight gas oil (HGO), vacuum gas oil (VGO) or naphtha. Steam or another gas may be used as the diluent. The resulting low molecular weight olefins include ethylene, propylene, butylenes, amylenes, and higher octane, lower benzene gasoline fractions. As the solid catalyst, conventional (FCC) cracking catalysts and improved cracking catalysts are used. Catalyst types may be representative of natural and synthetic aluminum silicates, zeolites, clays and the like. Conventional zeolites are possible, including X and Y zeolites that can be stabilized with rare earth metals. As process conditions for catalyst cracking in a reactor system according to the invention, the reaction temperature is between 520 and 700 ° C .; The pressure is 105 to 500 kPa; The residence time is 0.1 to 3 seconds, in particular 0.2 to 1 second. Residence times of less than 0.5 seconds (eg, 0.2 seconds to 0.49 seconds) are possible.

The invention may also be used to dehydrogenate hydrocarbon feedstocks such as propane, isobutane and low molecular weight condensates to convert the feedstocks to propylene, isobutylene and mixed butylene, respectively. The reaction temperature is typically 580 to 750 ° C. The same residence time as mentioned above can be used. Dehydrogenation catalysts known in the art such as chromium / alumina can be used.

According to the invention, air can be supplied into the reactor to enhance the reaction, with an air supply of 0 to 50%. When additional air is supplied in the reactor, the feed amount is preferably about 0.1 to about 50%, in particular 10 to 40%, based on the weight of the hydrocarbon.

Compared with the known methods, the most important advantages of the present invention are as follows: For the delivery of catalyst from one unit to another, short residence times and high catalysts without the use of complex mechanical or pneumatic transport systems Volume fractions can be maintained.

All the heat required for catalytic conversion of the hydrocarbon feedstock is a circulating fluidized bed except when air is also injected into the reactor and the oxidation of the resulting hydrocarbon feedstock and reaction product caused by the air injection provides some heat into the reactor. Supplied by recycled catalyst which is regenerated in the regenerator.

The catalyst volume fraction in the reactor can be fixed to the desired value by internal catalyst recycle regardless of other flows in the process.

The pressure levels in the reactor and regenerator can be controlled independently of each other. This also offers the possibility of combining one common regenerator with one or more reactors operated on inherent optimal process parameters and feedstock.

Compared with the conventional cracking process, the process of the present invention provides high low molecular weight olefin yield, good gasoline fraction, high conversion and simple and inexpensive reactor design.

Compared with current dehydrogenation methods, the present invention provides a very simple and inexpensive reactor / regenerator design.

Compared to the FCC type unit, the regenerator of the present invention is compact and has a lower catalyst load. This, by appropriate design, offers the possibility of avoiding current heavy fire resistant assemblies and using an easy to maintain, lightweight, simple, inexpensive, externally insulated configuration.

The average cracking temperature across the CFB reactor can be increased without increasing the reactor inlet temperature, and consequently, the yield of low molecular weight olefins can cause Is increased by using.

The accompanying drawings show preferred embodiments of the invention. Short contact reactor / regenerator systems are used to obtain the desired process conditions. The basic principle of controlling the interaction of two CFB units is described in more detail in Finnish patent application 924438 (Einco 0y, Finland).

According to the invention, the hydrocarbon feedstock mixed with the heated catalyst is cracked in the short contact CFB reactor 1 at 520-700 ° C. Hydrocarbon is supplied through the feed nozzle 24. The operating pressure of the reactor is 105 to 500 kPa (a) and the residence time is 0.1 to 3 seconds, preferably 0.2 to 2 seconds. The catalyst to oil ratio can be 1 to 120, preferably 10 to 50. The partial pressure of the hydrocarbon feed may be reduced by the addition of steam or other diluent gas, such as recycle gas, from the unit, but the use of diluent gas is not a precondition for the operation of the process. Feedstock is introduced from pipe 17 and pre-fluidizing gas is injected through pipe 18.

After the cracking reaction, the spent catalyst is separated from the product in a cyclone 2 located outside of the fluidized bed reactor. The hydrocarbon adsorbed to the spent catalyst may remain in the spent catalyst and burn in the regenerator 3 or may be stripped by steam 21 in the stripping region below the cyclone if the stripping is economically reasonable. The product exits through pipe 19. Some of the spent catalyst travels from the cyclone 2 to the regenerator 3 through the spent catalyst pipe 16, the flow of catalyst particles being in close proximity to the feed nozzle 8 ′ connected to the base of the regenerator 3. Controlled by a valve 8 on the pipe. Some of the spent catalyst can be returned to the reactor as internal recirculation through control valve 6 on catalyst recirculation pipe 12. By controlling the catalyst recycle rate with valve 6, the catalyst volume fraction and temperature profile in the reactor can be adjusted. To prevent mixing of the reactor and regenerator gases, the valve 8 controls the catalyst particle flow in such a way that the pipe 16 is always filled with catalyst. Surface level control is indicated by L.

Regenerator 3 is essentially a circulating fluidized bed reactor. The regenerator serves the following two purposes: The heat for the endothermic cracking reaction is supplied to the reactor by a catalyst heated in the regenerator, so that coke precipitated on the spent catalyst particles is burned. Regeneration of the catalyst takes place at 650 to 800 ° C. by blowing preheated air through the air inlet pipe 22 and injecting additional fuel through the pipe 23 to the bottom of the regenerator. Alternatively, the additional fuel may be combusted in a separate combustion chamber from which hot fuel gas enters the bottom of the regenerator via pipe 22. The regenerated high temperature catalyst is separated from the combustion gas discharged through the outlet pipe 20 in the regenerator cyclone 4, and the regenerated catalyst is returned to the reactor 1 through the regenerated catalyst pipe 15 and flow Is controlled by the control valve 9. The remaining regenerated catalyst is returned to the regenerator as internal recycle via the catalyst recycle pipe 14.

Under steady state conditions, the catalyst flow rates through pipes 15 and 16 are the same. The catalyst is added to the system via a valve 5 which is controlled by the pressure difference between the top and the base of the regenerator.

One or more reactors may be arranged in line with the hydrocarbon stream, or one or more reactors may be arranged in parallel with each having its own source.

The product separated from the catalyst in the reactor cyclone can be further processed into intermediate product fractions using standard or modified FCC method product recovery systems.

As exemplifying embodiments of the invention, the test results of an intermediate test plant for the conversion of gas oil to olefins are described below.

Example 1

The system consisted of one CFB reactor and one CFB regenerator. The regenerated catalyst entering the reactor was prefluidized with nitrogen. Low molecular weight gas oil (LGO) was fed into the reactor through the nozzle with a small flow of distributed air in the reactor. No internal catalyst recycle was used in this test. The main parameters are as follows:

Reactor:

Height 1.85 m

0.030 m in diameter

Oil mass flow rate 1.13 g / s

External catalyst / oil ratio 27 g / g

Internal catalyst / oil ratio 0%

Catalyst Volume Fraction 2-7%

0.25 m height of the prefluidized pipe

Diameter of prefluidized pipe 0.018 m

Regenerator:

Height 3.1 m

0.08 m in diameter

0 ₂ concentration of exhaust gas 4-5%

Catalyst volume fraction 4%

Example 2

The reactor configuration and feedstock are the same as in Example 1 except that the internal and external catalyst / oil ratios are both about 15. The internal catalyst recycle inlet on the reactor is directly above the oil injection point.

Example 3

The reactor configuration and feedstock were the same as in Example 2, except that no air was used for feed distribution and the internal catalyst recycle fraction was about 8.

Example 4

The reactor configuration and feedstock were the same as in Example 1 above except that air was used for prefluidization but no feed distribution gas was used. The riser diameter in this example was 0.042 m.

The present invention provides a novel method and reactor system for producing low molecular weight olefins from hydrocarbon feedstocks.

Claims (18)

Feeding the hydrocarbon feedstock into the reaction zone 1 containing the solid catalyst, Contacting the hydrocarbon feedstock in the reaction zone (1) with a catalyst under conditions favorable for catalytic conversion of hydrocarbons to low molecular weight olefins, Separating the reaction product obtained after the catalytic conversion from the reaction zone 1, Recovering the catalyst, and Catalytically converting hydrocarbons to low molecular weight olefins, comprising the step of regenerating the deactivated catalyst in the regenerator (3), wherein the hydrocarbon feedstock is charged in a circulating fluidized bed reactor (1) with a residence time of 0.1 to 3 seconds. Contact with the catalyst. The process according to claim 1, wherein the regenerator comprises a circulating fluidized bed (3), Draining part or all of the spent catalyst from the circulating fluidized bed reactor 1 and feeding the discharged catalyst into the circulating fluidized bed regenerator 3 for regeneration by combustion, and Recycling the regenerated catalyst into the circulating fluidized bed reactor (1), providing all the heat required for catalytic conversion of the hydrocarbon feedstock by the recirculating catalyst regenerated in the circulating fluidized bed regenerator (3). Way. 3. Process according to claim 2, characterized in that all spent catalyst from the circulating fluidized bed reactor (1) is discharged and fed into the regenerator (3) for regeneration by combustion. The process according to claim 1, wherein the spent catalyst is separated from the circulating fluidized bed reactor 1 in an external cyclone 2 connected to the reactor, and part or all of the separated catalyst is circulated fluidized bed regenerator 3. To the regenerator (3) via a spent catalyst pipe (16) connected to the bottom of the shell. 5. Process according to claim 4, characterized in that all the separated catalyst is directed to the regenerator (3). 5. The spent catalyst flow through the spent catalyst pipe 16 into the regenerator 3 is always filled with catalyst to prevent the spent catalyst pipe 16 from intermixing the reactor and regenerator gases. Controlled by a valve (8) on the spent catalyst pipe (16). 4. The process according to claim 3, wherein the concentration in the reactor and the temperature profile across the reactor (1) are controlled by adjusting the rate of catalyst recycle to the reactor through the catalyst recycle pipe (12). 3. The catalyst recirculation pipe (14) according to claim 1, wherein the regenerated catalyst is separated from the circulating fluidized bed regenerator (3) in a cyclone (4) external to the circulating fluidized bed regenerator (3) and a portion of the catalyst is recycled to the catalyst recycle pipe (14). Is recycled to the circulating fluidized bed regenerator (3) and the remaining catalyst is led to the lower end of the reactor (1) via a pipe (15) for the regenerated catalyst. The process of claim 1 wherein the hydrocarbon feedstock selected from the group consisting of low molecular weight gas oils, high molecular weight gas oils, vacuum gas oils and naphtha is subjected to catalytic cracking conditions using no diluent gas or using steam or other gas as the diluent. Processed under a process such that the hydrocarbon feedstock is converted to low molecular weight olefins selected from the group consisting of propylene, butylene, amylene, and gasoline with a high octane number and a low benzene content. 10. The process according to claim 9, wherein a solid catalyst which can be a conventional cracking catalyst or an improved cracking catalyst is used. 3. The feedstock according to claim 1 or 2, characterized in that the feedstock is contacted with the catalyst in the circulating fluidized bed reactor 1 at a temperature of 520 to 700 ° C, a pressure of 105 to 500 kPa and a residence time of 0.1 to 3.0 seconds. Way. The method of claim 1, characterized in that the hydrocarbon feedstock selected from the group consisting of propane, isobutane and low molecular weight condensates is processed under dehydrogenation conditions in the presence of a dehydrogenation catalyst to be converted to propylene, butylene or amylene. Way. 13. Process according to claim 12, characterized in that the feedstock is contacted with the catalyst in the circulating fluidized bed reactor (1) with a residence time of 0.1 to 3.0 seconds at a temperature of 580 to 750 ° C. 3. Process according to claim 1 or 2, characterized in that from 0.1 to 50% by weight of air, based on the weight of the hydrocarbon feedstock, is fed into the reactor (1). 3. Process according to claim 1 or 2, characterized in that the deactivated catalyst is regenerated by burning coke precipitated on the surface of the catalyst in a circulating fluidized bed regenerator (3) by hot air at 650 to 800 ° C. . The method of claim 1 wherein the residence time is between 0.2 and 2 seconds. At least one circulating fluidized bed reactor (1), A nozzle 24 for feeding hydrocarbon feedstock and recycled catalyst 6 'to the bottom of the circulating fluidized bed reactor 1, A cyclone 2 for catalyst separation, located on the outlet of the fluidized bed reactor 1 to separate the spent catalyst from the product stream of the reactor, and having a product outlet 19 and a solids outlet 12, 16 for the catalyst, One circulating fluidized bed unit regenerator 3 for catalyst regeneration, A nozzle 6 'for the spent catalyst to be regenerated located below the second circulating fluidized bed regenerator 3, and An apparatus for catalytic conversion of hydrocarbons to low molecular weight olefins comprising a cyclone (4) for separating catalyst for separating the regenerated catalyst from the regenerator flue gas. Process according to claim 15, characterized in that the deactivated catalyst is regenerated by burning coke precipitated on the surface of the catalyst in the circulating fluidized bed regenerator (3) at between 650 and 800 ° C. by hot air and additional fuel.