CN105349172A - Naphtha raw material catalysis cracking method - Google Patents

Abstract

The invention relates to a method for catalytic cracking of naphtha raw materials, the method comprising: (1) contacting and reacting naphtha raw materials with a first catalytic cracking catalyst in a first reaction zone to obtain a first oil agent mixture; (2) make the C4 rich in olefins contact and react with the second catalytic cracking catalyst in the second reaction zone to obtain the second oil mixture; (3) combine the first oil mixture and the second oil The catalyst mixture is introduced into a third reaction zone for reaction, wherein the reaction temperature of the third reaction zone is higher than the reaction temperature of the first reaction zone, and the temperature of the second catalytic cracking catalyst is higher than that of the first catalytic cracking catalyst. catalyst temperature. According to the catalytic cracking method of naphtha raw material provided by the present invention, the yield of non-ideal products hydrogen, methane and coke can be kept unchanged or reduced while increasing the yield of ethylene and propylene.

Description

Catalytic cracking method of naphtha raw material

technical field

The invention relates to a method for catalytic cracking of naphtha raw materials, in particular to a method for catalytic cracking of naphtha raw materials which reduces the yield of non-ideal products.

Background technique

Modern petroleum processing technology pays more attention to reducing energy consumption per unit of raw material processing and reducing carbon emissions while pursuing the yield of high-value products (such as ethylene, propylene, and C8 aromatics). Hydrogen, methane, and coke, which are by-products of petroleum hydrocarbon processing in modern refineries, are often disposed of through combustion, which is the main source of carbon emissions in refineries, which greatly reduces the economics of atomic processing.

Patent application CN102746888A discloses a method for producing ethylene propylene by fluidized catalytic cracking. In this invention, under the conditions of 600-750°C, water-to-oil weight ratio of 4-0.5:1 and catalyst/raw material weight ratio of 1-40:1, the first riser carries out catalytic cracking reaction of fresh naphtha, and the second riser The reaction product is separated to obtain the catalytic cracking reaction of C4-C12 components without aromatic hydrocarbons, and the products obtained by the first and second riser reactions are separated to obtain ethylene and propylene. This invention adopts ZSM-5 and beta zeolite as the active components of catalytic cracking fluidized bed catalyst, and through the introduction of rare earth, phosphorus or iron element oxides, the acid center of the catalyst can be modified, and the density and acidity of the acid center of the catalyst can be adjusted. Strength, so as to achieve the purpose of inhibiting hydrogen transfer reaction and carbon deposition reaction, and improve the selectivity of the catalyst and the yield of ethylene propylene. The C4-C12 components in the reactants that do not contain aromatics can be further converted through the second riser, thereby increasing the conversion rate of naphtha and the yield of ethylene propylene. The disadvantage of this invention is that the structure of the two riser reactors is the same, and the reaction conditions are similar. Using the same catalyst, the C4～C12 components that do not contain aromatics in the reactants can be combined with fresh naphtha. The catalytic cracking reaction is carried out in the first riser, which simplifies the structure. Naphtha with 40-162°C, 65.18% alkane content, 28.44% naphthene content, 6.21% aromatics content, and 0.17% olefin content as raw material, at a reaction temperature of 600°C, a water-to-oil weight ratio of 0.3 and a catalyst/raw material weight When the ratio is 1, the yield of ethylene+propylene is 24.8%; when the reaction temperature is 650°C, the water-oil weight ratio is 1.0, and the catalyst/raw material weight ratio is 25, the yield of ethylene+propylene is 52.3%.

Patent application CN101759513A discloses a method for utilizing naphtha. The method comprises: (1) separating the naphtha into components rich in normal paraffins and components rich in non-normal paraffins; (2) cutting the components rich in normal paraffins obtained in step 1 into C5/6 fraction and C7+ fraction; (3) isomerizing the C5/6 fraction obtained in step (2) to obtain C5/6 isoparaffins; (4) catalytically cracking the C7+ fraction obtained in step 2 to obtain Ethylene and propylene; (5) reforming the component rich in non-normal paraffins obtained in step (1) to obtain aromatics or high-octane blending components. Compared with the C5/6 fraction, the activation energy required for the catalytic cracking of the C7+ fraction is lower, so the required reaction temperature is lower, and the yield of ethylene propylene is higher.

Patent application CN1753973A discloses the production of propylene from naphtha feed fractionation and further cracking of the C6 fraction. Selective methods for the production of C3 olefins from catalytically cracked or thermally cracked naphtha streams include fractionating the naphtha feed to obtain at least a C6-rich fraction (containing at least 50% heavy C6 fraction) and a C6-depleted fraction, the C6-rich fraction being The C6-lean fraction is fed downstream to the reaction stage, minimizing its residence time. The reaction stage consists of one or more fixed bed reactors or reaction zones. It can be that naphtha is first fractionated into C6-rich fraction and C6-poor fraction, followed by staged cracking; it can also be that naphtha is cracked first, and the product stream is further fractionated into C6-rich fraction and C6-lean fraction, which is further staged and re-refined. The method of this patent application is comparatively applicable to the naphtha that is rich in C6 fraction.

The method of the above patent application mainly focuses on improving the yield of ethylene and propylene in the catalytic cracking product of naphtha, and does not involve how to increase the yield of ethylene and propylene while making the non-ideal product hydrogen in the catalytic cracking product of naphtha , methane, and coke yields remain unchanged or decrease.

Contents of the invention

The purpose of the present invention is to provide a new catalytic cracking method for naphtha raw materials, so as to improve the yields of ethylene and propylene while keeping or reducing the yields of non-ideal products hydrogen, methane, and coke.

In the traditional catalytic cracking method of naphtha feedstock, a riser reactor or a riser plus fluidized bed composite reactor is used. One of the main characteristics of these catalytic cracking methods is that the temperature in the reactor changes with the flow direction of the reactant Gradually decrease, that is, the temperature at the bottom of the reactor is the highest, and along the direction of reactant flow, the temperature of the stream decreases step by step, to the outlet of the riser (for the riser reactor) or the outlet of the fluidized bed (for the combination of the riser and the fluidized bed) Composite reactor) has the lowest temperature. Different hydrocarbon components in naphtha can be divided into easy-to-crack components (mainly olefins and some cycloalkanes) and difficult-to-crack components (mainly alkanes) according to their cracking properties. The components are more prone to catalytic cracking, and the reaction temperature required for the reaction is lower and the reaction time is shorter. In the traditional cracking method of naphtha raw material, the easily cracked component firstly undergoes catalytic cracking due to contact with high-temperature catalyst at the initial stage of reaction. As the reaction progresses, the temperature of the reactant stream in the middle and late stage of the reaction decreases significantly, which makes the refractory components in the naphtha lack of reaction heat, and it is difficult to undergo catalytic cracking, so the conversion rate of the naphtha is low; at the same time, the lower stream temperature in the middle and late stages of the reaction It will also cause the generated propylene to undergo a reconversion reaction, and the yield of ethylene and propylene in the product is low. On the other hand, in order to increase the conversion rate of naphtha, a large amount of high-temperature regenerated catalyst is mainly introduced into the bottom of the riser, but the easily cracked components such as olefins in naphtha initially contact a large amount of high-temperature regenerated catalyst, and the thermal cracking reactions that occur increase. , resulting in high yields of hydrogen, methane, and coke in the product. Therefore, there is a contradiction between increasing the conversion rate of naphtha and reducing the yield of non-ideal products hydrogen, methane and coke in the traditional process.

In addition, the traditional catalytic cracking reaction of naphtha feedstock adopts riser reactor, and the catalyst density in the riser is low, usually less than 100kg/m ³ , so the conversion rate of easily cracked components such as olefins in naphtha into ethylene and propylene is low ; The catalyst density in the reactor is high, greater than 500kg/cm ³ , the conversion rate of easily cracked components is improved, but it is also easy to cause hydrogen transfer reaction and coke formation reaction of olefins, and the yield of hydrogen and methane is high, and the yield of coke is also high.

In order to improve the yield of ethylene and propylene while keeping the yield of non-ideal products hydrogen, methane and coke unchanged or reduced, the invention provides a method for catalytic cracking of naphtha raw material, the method comprising:

(1) making the naphtha raw material and the first catalytic cracking catalyst contact and react in the first reaction zone to obtain the first oil mixture;

(2) making C4 rich in olefins contact and react with the second catalytic cracking catalyst in the second reaction zone to obtain the second oil mixture;

(3) introducing the first oil agent mixture and the second oil agent mixture into the third reaction zone for reaction, and subjecting the obtained oil agent mixture to oil agent separation to obtain unborn catalyst and reaction oil gas, from the reaction Gasoline, diesel and C1-C4 components are separated from oil and gas, and ethylene, propylene and olefin-rich C4 are further separated from the C1-C4 components, and the separated olefin-rich C4 is at least partially injected into the second Recycle in the second reaction zone;

Wherein, the reaction temperature of the third reaction zone is higher than the reaction temperature of the first reaction zone, and the temperature of the second catalytic cracking catalyst is higher than the temperature of the first catalytic cracking catalyst.

In the catalytic cracking method of naphtha feedstock provided by the present invention, according to the characteristics of hydrocarbons in the naphtha feedstock and the difference in the reaction conditions required for the high-selectivity catalytic conversion of different hydrocarbons into ethylene and propylene, three reactions Based on the composite reactor composed of different zones, a cascade catalytic cracking method suitable for the highly selective conversion of naphtha feedstock into ethylene and propylene was constructed, so that the non-ideal products hydrogen, methane and coke could be made while increasing the yield of ethylene and propylene The yield remains unchanged or decreases, which improves the economy of atom utilization in the naphtha catalytic cracking process. Specifically, the present invention has the advantages compared with the traditional naphtha feedstock catalytic cracking method:

(a) Compared with the traditional method, the naphtha raw material reacts at a lower temperature first, so that the easily cracked components in the naphtha raw material are preferentially converted into ethylene and propylene, and the formed oil mixture is then reacted at a higher temperature. Continued reaction at high temperature can further transform the hard-to-crack components and C4 hydrocarbons in naphtha. In this way, on the one hand, it avoids a large amount of easily cracked components such as olefins in the naphtha raw material to directly react at a higher reaction temperature to cause a large number of thermal cracking reactions, resulting in non-ideal products such as hydrogen, methane, and coke. On the other hand, through Carrying out the second-step catalytic cracking reaction at a higher temperature can provide sufficient heat of reaction for the cracking reaction of difficult-to-crack components and C4 hydrocarbons to continue, and improve the total conversion rate of naphtha raw materials.

(b) In one embodiment of the present invention, when the first reaction zone adopts a fluidized bed reactor, the fluidized bed reactor has a higher bed catalyst density, which is beneficial to the easy cracking components in the naphtha raw material It can be converted into ethylene and propylene with high selectivity within a short reaction time, and at the same time, the aromatization reaction occurs as little or as little as possible to generate new aromatic components, so that the refractory components entering the third reaction zone can be retained as much as possible There is less aromatic hydrocarbon, so as to avoid the condensation reaction of aromatic hydrocarbon components under the high-temperature catalyst in the third reaction zone to generate coke, hydrogen, methane, etc.

(c) Generally, the lower the temperature of the stream in the middle and later stages of the catalytic cracking reaction of naphtha feedstock, the greater the probability of propylene reconversion reaction. In the method provided by the present invention, the higher reaction temperature and lower catalyst density in the third reaction zone can greatly reduce the probability of reconversion reaction of propylene produced in the first reaction zone and the second reaction zone.

(d) In the method provided by the present invention, the first oil agent mixture from the first reaction zone contains a large amount of carbanions, which provides a carbanion trigger for the catalytic cracking reaction of the hard-to-crack product in the third reaction zone. agent, reducing the reaction severity of the third reaction zone.

According to the cracking reaction performance of different hydrocarbon molecules in naphtha, the present invention constructs three reaction zones suitable for different stages of naphtha cracking reaction, so that the selective and efficient conversion of components with different cracking properties in naphtha is different from traditional methods Compared with this method, the yields of ethylene and propylene are greatly improved, while the yields of hydrogen, methane, and coke in non-ideal products remain unchanged or decrease.

Other features and advantages of the present invention will be described in detail in the detailed description that follows.

Description of drawings

The accompanying drawings are used to provide a further understanding of the present invention, and constitute a part of the description, together with the following specific embodiments, are used to explain the present invention, but do not constitute a limitation to the present invention. In the attached picture:

Fig. 1 is the schematic flow sheet of a kind of embodiment of the catalytic cracking method of naphtha raw material provided by the present invention;

Fig. 2 is the schematic flow sheet of another embodiment of the catalytic cracking method of naphtha raw material provided by the present invention;

Fig. 3 is a structural schematic diagram of a fluidized bed reactor used as the first reaction zone in the catalytic cracking method for naphtha feedstock provided by the present invention.

Explanation of reference signs

1-First reaction zone

4- Regenerator

5-Second reaction zone

6- The third reaction zone

7- Stripper

8-settler

11-Product separation system

13-The second regenerated catalyst inclined tube

14- Inclined tube for spent catalyst

15-The first regenerated catalyst inclined tube

16,17-(injection of high-temperature regenerated catalyst into the external heat extractor 100) pipeline

20-(for injecting naphtha raw material) pipeline

23-light gasoline

24-(introduce reaction oil gas to product separation system 11) pipeline

25-(dry gas is drawn from the product separation system 11) pipeline

26-(Liquefied gas is drawn out from the product separation system 11) pipeline

27-(gasoline drawn from product separation system 11) pipeline

28-(Diesel oil is drawn from the product separation system 11) pipeline

29-heavy gasoline

30-(inject olefin-rich C4 into the third reaction zone) pipeline

31-(inject olefin-rich C4 into the second reaction zone) pipeline

41-(inject atomized steam into the first reaction zone) pipeline

42-(inject atomized steam into the third reaction zone) pipeline

43-(injection of pre-lift medium into the second reaction zone) pipeline

45-(injection of pre-lift medium into the first reaction zone) pipeline

47-(inject stripping steam into stripper) pipeline

50-(injecting oxygen-containing gas into the regenerator) pipeline

51-(Lead out regeneration flue gas) pipeline

100-external heater

101-Light and heavy gasoline separation system

detailed description

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

All ranges disclosed herein are inclusive of endpoints and are independently combinable. Neither the endpoints of the ranges nor any values disclosed herein are limited to that precise range or value, and these ranges or values are understood to include values approaching these ranges or values.

The catalytic cracking method of the described naphtha raw material provided by the invention comprises:

(1) making the naphtha raw material and the first catalytic cracking catalyst contact and react in the first reaction zone to obtain the first oil mixture;

(2) making C4 rich in olefins contact and react with the second catalytic cracking catalyst in the second reaction zone to obtain the second oil mixture;

(3) introducing the first oil agent mixture and the second oil agent mixture into the third reaction zone for reaction, and subjecting the obtained oil agent mixture to oil agent separation to obtain unborn catalyst and reaction oil gas, from the reaction Gasoline, diesel and C1-C4 components are separated from oil and gas, and ethylene, propylene and olefin-rich C4 are further separated from the C1-C4 components, and the separated olefin-rich C4 is at least partially injected into the second Recycle in the second reaction zone;

Wherein, the reaction temperature of the third reaction zone is higher than the reaction temperature of the first reaction zone, and the temperature of the second catalytic cracking catalyst is higher than the temperature of the first catalytic cracking catalyst.

In the method provided by the present invention, the catalytic cracking reaction in the first reaction zone is carried out at a relatively low reaction temperature, which can convert easily cracked components in the naphtha raw material into C1-C4 small molecular hydrocarbons The unreacted refractory components (C5+ components) in the naphtha raw material in the first reaction zone continue to undergo catalytic cracking reactions in the subsequent third reaction zone.

In the present invention, the first reaction zone is preferably a fluidized bed reactor. Since the fluidized bed reactor has a higher bed catalyst density, it is conducive to the highly selective conversion of easily cracked components in naphtha raw materials into ethylene and propylene within a short reaction time, and at the same time, as little or no aromatization occurs as possible Chemical reaction to generate new aromatic components, so that the refractory components entering the third reaction zone retain as little aromatics as possible, thereby avoiding the condensation reaction of aromatic components under the high-temperature catalyst in the third reaction zone to generate coke and hydrogen , methane, etc.

In the present invention, the fluidized bed reactor as the first reaction zone can be selected from fixed fluidized bed reactors, scattered fluidized bed reactors, bubbling bed reactors, turbulent bed reactors, fast bed reactors One or more of reactors, transport bed reactors and dense phase fluidized beds. The fluidized bed reactor can be a fluidized bed structure with equal diameters or a fluidized bed structure with variable diameters. Preferably, the fluidized bed reactor has a fluidized bed structure with an expanding diameter (as shown in FIG. 3 ). Further preferably, the ratio of the diameter a of the lower end, the diameter b of the upper end, and the height c of the fluidized bed structure with expanding diameter is 1:1.5-10:10-30.

In the method provided by the present invention, the reaction conditions in the first reaction zone may include: the temperature is 520-630°C, preferably 560-620°C; the agent-to-oil (weight) ratio is 5-25, preferably 10 -15; the weight hourly space velocity is 4-20h ^-1 , preferably 4-16h ^-1 .

In the method provided by the present invention, steam can also be injected into the first reaction zone, and the weight ratio of the injected steam to naphtha can be 0.01-1:1, preferably 0.1-0.5 :1.

In the method provided by the present invention, the catalytic cracking catalyst with a relatively high temperature is introduced through the second reaction zone, and the second reaction zone is used as an auxiliary reaction zone of C4 rich in olefins, which can realize the separation of Reuse of olefin-rich C4 components.

In the present invention, the second reaction zone may be a catalyst delivery pipe. The reaction time of the second reaction zone may be less than 1 second, preferably 0.1-1 second, more preferably 0.1-0.3 second.

In the method provided by the present invention, in the third reaction zone, the first oil agent mixture (comprising C1-C4 small molecule hydrocarbons, refractory components in naphtha feedstock) from the first reaction zone and catalyst) and the second oil agent mixture from the second reaction zone further undergo catalytic cracking reaction therein. Because the temperature of the second catalytic cracking catalyst from the second reaction zone is relatively high, the reaction temperature of the third reaction zone is obviously higher than that of the first reaction zone, preferably, the reaction temperature of the third reaction zone is higher than that of the first reaction zone The reaction temperature is 10°C or higher, more preferably 20°C or higher, and more preferably 20-150°C.

In the method provided by the present invention, the third reaction zone can be any one or more of a riser reactor, a fluidized bed reactor, a downlink conveyor line reactor and an uplink conveyor line reactor A combination, most preferably a riser reactor. The riser reactor may be selected from at least one of riser reactors with equal diameters, riser reactors with constant linear velocity and riser reactors with variable diameters. In the present invention, for the riser reactor, the reaction temperature refers to the outlet temperature of the riser reactor.

In the method provided by the present invention, the reaction conditions in the third reaction zone may include: a temperature of 630-700°C, preferably 630-675°C; an agent-to-oil (weight) ratio of 10-40, preferably 15 -30; time is 0.1-3 seconds, preferably 1-2.5 seconds; pressure is 0.1-0.4MPa, preferably 0.15-0.35MPa. In the present invention, pressure refers to absolute pressure.

In the method provided by the present invention, water vapor can also be injected into the third reaction zone, and the weight ratio of the injected water vapor to naphtha can be 0.01-0.5:1, preferably 0.1-0.5 :1.

In the method provided by the present invention, the first reaction zone, the second reaction zone and the third reaction zone preferably constitute a composite reactor, wherein the outlet of the first reaction zone and the The outlets of the second reaction zone are respectively connected to the lower part of the third reaction zone. During operation, the naphtha raw material and the first catalytic cracking catalyst are injected at the bottom of the first reaction zone, and the olefin-rich C4 and the second catalytic cracking catalyst are injected at the lower part of the second reaction zone. The first oil mixture and the second oil mixture from the second reaction zone are injected into the lower part of the third reaction zone.

In the method provided by the present invention, the olefin-rich C4 separated from the reaction oil gas can be partially or completely injected into the second reaction zone for recycling, or a part can be injected into the first reaction zone and/or the third reaction zone Participate in the reaction in the zone to realize recycling. In one embodiment, the olefin-rich C4 that is injected into the second reaction zone for recycling may account for more than 20% by weight, preferably 50% by weight, of the total amount of olefin-rich C4 separated from the reaction oil gas above.

According to one embodiment of the present invention, the catalytic cracking method of the naphtha raw material may also include: performing charring regeneration on the spent catalyst separated in the oil agent separation process of step (3) to obtain a high-temperature regenerated catalyst, Cooling a part of the high-temperature regenerated catalyst and recycling the cooled regenerated catalyst as the first catalytic cracking catalyst, while recycling another part of the high-temperature regenerated catalyst as the second catalytic cracking catalyst.

The regeneration process can be carried out according to the conventional catalyst regeneration method in the art, for example, the regeneration method can include: introducing oxygen-containing gas (such as air) from the bottom of the regenerator, after the oxygen-containing gas is introduced into the regenerator, the catalyst to be regenerated Contact with oxygen for coke regeneration, and the flue gas generated after catalyst coke regeneration is separated from gas and solid in the upper part of the regenerator, and the flue gas can enter the subsequent energy recovery system. Generally, in order to ensure the regeneration effect and provide sufficient reaction heat to the reaction system, heating is required during the regeneration process. The heating can be carried out by conventional methods, for example, fuel oil can be injected into the regenerator. In a preferred case, the regeneration temperature in the regenerator may be 660-800°C.

The method of cooling the high-temperature regenerated catalyst can be realized by injecting the high-temperature regenerated catalyst into a cooler and cooling it to a required temperature.

In the method provided by the present invention, the first catalytic cracking catalyst usually adopts a cooled regenerated catalyst, and the second catalytic cracking catalyst usually directly adopts a high-temperature regenerated catalyst. Preferably, the temperature of the first catalytic cracking catalyst is 560-650°C, the temperature of the second catalytic cracking catalyst is 660-760°C, and the temperature of the second catalytic cracking catalyst is higher than that of the first catalytic cracking catalyst The temperature of the cracking catalyst is 10-150°C higher.

In the method provided by the present invention, the used catalytic cracking catalyst (including the first catalytic cracking catalyst and the second catalytic cracking catalyst) preferably contains zeolite with an average pore diameter of less than 0.7 nm. The zeolite with an average pore diameter of less than 0.7nm may be at least one of zeolite, ferrierite, chabazite, cyclolite, erionite, A zeolite, columnar zeolite and zeolite with MFI structure. The zeolite with the MFI structure is at least one of ZSM-5 and ZRP series zeolites. The zeolite with the MFI structure can also be ZSM-5 and ZRP series modified by one or more elements such as rare earth (RE), P, Fe, Co, Ni, Cu, Zn, Mo, Mn, Ga, Sn, etc. at least one of zeolites.

In the present invention, the naphtha raw material can be at least one of straight run naphtha, catalytic cracking naphtha, steam cracking naphtha, coking naphtha and Fischer-Tropsch synthetic naphtha, preferably Catalytically cracked naphtha. For catalytically cracked naphtha, its final boiling point is preferably not higher than 110°C, more preferably 55-88°C. The catalytically cracked naphtha preferably contains 30-90% by weight of olefins, more preferably not less than 35% by weight of olefins, further preferably not less than 50% by weight of olefins.

In the catalytic cracking method of the naphtha feedstock provided by the present invention, the first oil mixture leaving the first reaction zone contains the C1-C4 hydrocarbons generated by the reaction and unreacted refractory components in the naphtha feedstock (C5+ components). The refractory component may contain 70-90% by weight of alkanes and small amounts of olefins and aromatics. Preferably, the refractory component contains less than 20% by weight of olefins, more preferably less than 10% by weight; contains less than 15% by weight of aromatics, more preferably less than 5% by weight, and most preferably contains no aromatics.

In the present invention, the content of olefins in the olefin-rich C4 injected into the second reaction zone may be more than 60% by weight, preferably 70-90% by weight. Further preferably, the content of aromatics in the olefin-rich C4 is less than 10% by weight, preferably less than 5% by weight, and most preferably contains no aromatics. Further preferably, the content of alkanes in the olefin-rich C4 is less than 30% by weight, preferably less than 25% by weight.

In the method provided by the present invention, the oil agent separation process and the product separation process in step (3) can be implemented according to conventional methods in the art, and will not be repeated here.

According to a specific embodiment of the present invention, the catalytic cracking method of the naphtha feedstock comprises: introducing a stream of high-temperature regenerated catalyst from the regenerator into the bottom of the fluidized bed reactor after cooling down, and contacting with the naphtha feedstock And react, the easily cracked components in the naphtha raw material undergo a cracking reaction to generate C1-C4 small molecule hydrocarbons. C1-C4 small molecule hydrocarbons, unreacted refractory components (C5+ components) in the naphtha raw material and catalytic cracking catalyst form the first oil agent mixture, which is drawn out from the top of the fluidized bed reactor. The first oil mixture is introduced into the lower part of the third reaction zone (riser reactor) which is closely connected with the fluidized bed reactor without separation. Another stream of high-temperature regenerated catalyst from the regenerator is introduced into the lower part of the second reaction zone (catalyst delivery pipe), reacts with C4 rich in olefins, and is quickly introduced into the lower part of the third reaction zone, and further combined with the first reaction zone from the first reaction zone. The oil mixture is mixed, and the hard-to-crack components and C4 hydrocarbons continue to undergo secondary cracking reactions in the third reaction zone. The oil mixture from the outlet of the third reaction zone is separated by oil to obtain the raw catalyst and reaction oil gas, and the reaction oil gas is introduced The product separation system (fractionation device) fractionates and separates gasoline, diesel and C1-C4 gas products, and C1-C4 gas products are further separated to obtain ethylene, propylene, and olefin-rich C4, etc., and the olefin-rich C4 is injected into the second reaction recycled in the area. The separated raw catalyst is stripped by the stripper and then introduced into the regenerator for regeneration. Part of the regenerated catalyst is introduced into the lower part of the second reaction zone as the second catalytic cracking catalyst for recycling, and part of the regenerated catalyst is taken by the catalyst external heat collector After heating and cooling, it is introduced into the bottom of the first reaction zone as the first catalytic cracking catalyst for recycling.

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings.

Fig. 1 is the schematic flow sheet of a kind of embodiment of the catalytic cracking method of naphtha raw material provided by the present invention, wherein, the first reaction zone 1 is a fluidized bed reactor, the second reaction zone 5 is a catalyst delivery pipe, the third Reaction zone 6 is a riser reactor, the fluidized bed reactor and the riser reactor are closely connected coaxially, the catalyst conveying pipe is arranged side by side with the fluidized bed reactor, the outlet of the catalyst conveying pipe is vertically connected with the lower part of the riser, and the three reaction zone constitutes a composite reactor.

The high-temperature regenerated catalyst from the regenerator 4 is injected into the external heat collector 100 through the pipeline 16 and the pipeline 17 for heat exchange and cooling, and the first catalytic cracking catalyst obtained after cooling is introduced into the fluidized bed reaction through the first regenerated catalyst inclined tube 15 The pre-lift section at the lower part of the device 1, and the upward flow is accelerated under the action of the pre-lift medium injected from the pipeline 45. The naphtha is injected into the bottom of the fluidized bed reactor 1 through the pipeline 20 under the action of the atomized steam from the pipeline 41, and contacts and reacts with the first upward catalytic cracking catalyst, and the oil gas carries the catalyst upward in the gradually expanding reaction zone. The reacted first oil agent mixture is introduced into the lower part of the riser reactor 6 through the outlet at the top of the fluidized bed reactor 1 . The second catalytic cracking catalyst from the regenerator 4 enters the lower part of the catalyst delivery pipe 5 through the second regenerated catalyst inclined pipe 13, and flows upward under the action of the pre-lift medium injected by the pipeline 43, and the C4 rich in olefins is injected into the catalyst through the pipeline 31 The lower part of the delivery pipe 5 contacts and reacts with the second upward catalytic cracking catalyst, and the high-temperature catalyst carried by the oil gas enters the lower part of the riser reactor 6 from the outlet of the catalyst delivery pipe 5. The first oil agent mixture is further contacted and reacted. The reaction oil gas carries the catalyst and flows upwards along the riser reactor 6. The catalyst and reaction oil gas are introduced into the settler 8 through the outlet of the riser and separated by the rapid separation device. The oil gas is collected by the cyclone separation system at the top of the settler and introduced into the product separation through the pipeline 24 System 11. The spent catalyst separated by the fast separation device is introduced into the stripper 7, and the stripping steam injected into the pipeline 47 in the stripper 7 is in countercurrent contact with the spent catalyst, and the reaction oil gas carried by the spent catalyst is stripped as much as possible. The clean, stripped gas stream flows into settler 8 and is introduced into product separation system 11 via line 24 along with other gas streams. The spent catalyst after stripping is sent to the regenerator 4 through the inclined tube 14 of the spent catalyst to be burnt for regeneration. Oxygen-containing gas such as air is injected into the regenerator 4 through the pipeline 50, and the regenerated flue gas is drawn out through the pipeline 51.

The reaction oil gas (introduced through pipeline 24) from riser 6 is separated into dry gas (derived from pipeline 25), liquefied gas (derived from pipeline 26), gasoline (derived from pipeline 27) and diesel oil (derived from pipeline 27) in product separation system 11. Line 28 leads). The dry gas from line 25 can be separated and refined to obtain ethylene, ethane, hydrogen and methane, etc.; the liquefied gas drawn from line 26 can be obtained from polymer grade propylene and olefin-rich C4 after subsequent product separation and purification. , the olefin-rich C4 is recycled to the lower part of the catalyst delivery pipe 5 through the pipeline 31 or recycled to the lower part of the riser 6 through the pipeline 30 for re-cracking reaction. The pyrolysis gasoline drawn from line 27 can be used as a clean gasoline blending component, or as a raw material for aromatics extraction; the cracked light oil drawn from line 28 can be used as clean fuel oil or as a clean diesel blending component. The pyrolysis gasoline drawn from the pipeline 27 can also be further separated into heavy gasoline 29 and light gasoline 23 through the light and heavy gasoline separation system 101, and the light gasoline 23 can be circulated back to the fluidized bed 1 for further reaction under the action of the pre-lift steam injected through the pipeline 45.

Fig. 2 is the schematic flow sheet of another embodiment of the catalytic cracking method of naphtha feedstock provided by the present invention, wherein, the first reaction zone 1 is a fluidized bed reactor, the second reaction zone 5 is a catalyst delivery pipe, and the second reaction zone 5 is a catalyst delivery pipe. The third reaction zone 6 is a riser reactor, the catalyst conveying pipe is coaxially closely connected with the riser reactor, the fluidized bed reactor and the catalyst conveying pipe are arranged side by side, and the outlet of the fluidized bed is vertically connected with the lower part of the riser reactor, three The reaction zone constitutes a composite reactor.

The high-temperature regenerated catalyst from the regenerator 4 is injected into the external heat collector 100 through the pipeline 16 and the pipeline 17 for heat exchange and cooling, and the first catalytic cracking catalyst obtained after cooling is introduced into the fluidized bed reaction through the first regenerated catalyst inclined tube 15 The pre-lift section at the lower part of the device 1, and the upward flow is accelerated under the action of the pre-lift medium injected from the pipeline 45. The naphtha is injected into the bottom of the fluidized bed reactor 1 through the pipeline 20 under the action of the atomized steam from the pipeline 41, and contacts and reacts with the first upward catalytic cracking catalyst, and the oil gas carries the catalyst upward in the gradually expanding reaction zone. The reacted first oil agent mixture is vertically introduced into the lower part of the riser reactor 6 through the outlet at the top of the fluidized bed reactor 1 . The second catalytic cracking catalyst from the regenerator 4 enters the lower part of the catalyst delivery pipe 5 through the second regenerated catalyst inclined pipe 13, and flows upward under the action of the pre-lift medium injected by the pipeline 43, and the C4 rich in olefins is injected into the catalyst through the pipeline 31 The lower part of the delivery pipe 5 contacts and reacts with the second upward FCC catalyst, and the oil gas carries the high-temperature catalyst and continues vertically upward into the lower part of the riser reactor 6. The oil mixture is further contacted and reacted, and the oil and gas carry the catalyst to flow upwards along the riser reactor 6. The catalyst and the reacted oil and gas are introduced into the settler 8 through the outlet of the riser and separated by the rapid separation device. The oil and gas are collected by the cyclone separation system on the top of the settler , into the product separation system 11 through line 24. The raw catalyst separated by the fast separation device is introduced into the stripper 7, and the stripping steam injected by the pipeline 47 in the stripper 7 is in countercurrent contact with the catalyst, and the reaction oil gas carried by the raw catalyst is stripped as clean as possible. The stripped oil gas flows into the settler 8 and is introduced into the product separation system 11 through the pipeline 24 together with other oil gas. The spent catalyst after stripping is sent to the regenerator 4 through the inclined tube 14 of the spent catalyst to be burnt for regeneration. Oxygen-containing gas such as air is injected into the regenerator 4 through the pipeline 50, and the regenerated flue gas is drawn out through the pipeline 51.

The reaction oil gas (introduced through pipeline 24) from riser 6 is separated into dry gas (derived from pipeline 25), liquefied gas (derived from pipeline 26), gasoline (derived from pipeline 27) and diesel oil (derived from pipeline 27) in product separation system 11. Line 28 leads). The dry gas from line 25 can be separated and refined to obtain ethylene, ethane, hydrogen and methane, etc.; the liquefied gas drawn from line 26 can be obtained from polymer grade propylene and olefin-rich C4 after subsequent product separation and purification. , the olefin-rich C4 is recycled to the lower part of the catalyst delivery pipe 5 through the pipeline 31 or recycled to the lower part of the riser 6 through the pipeline 30 for re-cracking reaction. The pyrolysis gasoline drawn from line 27 can be used as a clean gasoline blending component, or as a raw material for aromatics extraction; the cracked light oil drawn from line 28 can be used as clean fuel oil or as a clean diesel blending component. The pyrolysis gasoline drawn from the pipeline 27 can also be further separated into heavy gasoline 29 and light gasoline 23 through the light and heavy gasoline separation system 101, and the light gasoline 23 can be circulated back to the fluidized bed 1 for further reaction under the action of the pre-lift steam 45.

The pre-lifting medium is well known to those skilled in the art, and can be selected from one or more of steam, C1-C4 hydrocarbons or conventional catalytic cracking dry gas.

The present invention will be further described below by way of examples and comparative examples.

The specific properties of the naphtha raw materials (including naphtha 1 and naphtha 2) and olefin-rich C4 used in the following examples and comparative examples are shown in Table 1. The catalyst used is a cracking catalyst with the brand name MMC-2 produced by Sinopec Catalyst Qilu Branch. Its specific properties are shown in Table 2. The catalyst contains ZRP zeolite with an average pore size of less than 0.7 nm.

Table 1

project name Naphtha 1 Naphtha 2 Olefin-rich C4 Hydrocarbon composition/wt% Olefin 50.39 69.33 79.80 Aromatics 0.00 9.91 0.00 alkanes 49.61 20.76 20.10 total 100.00 100.00 100.00 Distillation range/℃ HK 29.50 32.00 5% 32.50 39.10 10% 33.00 45.20 30% 34.40 49.70 50% 36.20 54.50 70% 39.20 65.50 90% 47.90 76.00 95% 55.60 80.10 EP 60.70 86.10

Table 2

Example 1

This example is to illustrate the catalytic cracking effect of the method provided by the present invention after the raw material naphtha 1 is sequentially entered into three reaction zones and under respective reaction conditions.

The experiment was carried out on a catalytic cracking unit with a medium-sized fluidized bed and a riser. As shown in Figure 1, the fluidized bed reactor 1 in this medium-sized device is a fluidized bed reactor gradually expanding in diameter, and its lower end internal diameter is 16 millimeters, and the upper end internal diameter is 104 millimeters, height 392 millimeters, riser reactor 6 The inner diameter is 16 mm and the length is 3200 mm. The lower part of the riser reactor is coaxially connected with the upper outlet of the fluidized bed reactor. mm, the inner diameter of the catalyst conveying pipe 5 is 16 mm, and the length is 600 mm, and its outlet is vertically connected with the lower part of the riser reactor. The test is operated in a single-pass manner.

After exchanging heat with the external heat extractor, the first catalytic cracking catalyst whose temperature has dropped to 645°C is introduced into the pre-lift section through the first regeneration inclined pipe 15, and flows upward into the bottom of the fluidized bed reaction zone 1 under the action of the pre-lift medium . After the naphtha 1 is preheated to 300°C and mixed with atomized water vapor, it enters the bottom of the fluidized bed reaction zone 1 through the feed nozzle, contacts with the first catalytic cracking catalyst after cooling down and catalytically cracks, and reacts the mixture of oil gas and catalyst Up, and enter the lower part of the riser reactor from the top of the fluidized bed reactor. The second catalytic cracking catalyst at 660°C from the regenerator is introduced into the lower part of the catalyst delivery pipe 5 from the regenerator 4 through the second regeneration inclined pipe 13, and the C4 rich in olefins is preheated to 300°C and mixed with atomized steam, and then passed through the The material nozzle enters the lower part of the catalyst conveying pipe to contact with the high-temperature catalyst, and the mixture of reaction oil gas and high-temperature catalyst goes up, and enters the lower part of the riser reaction zone 6 from the outlet, and further mixes, contacts and catalytically cracks with the oil agent from the fluidized bed reaction zone , the mixture of all reaction oil gas and catalyst goes up, and the gas-solid separation is carried out through the rapid separation equipment at the outlet. The reaction oil gas is introduced into the settler and then introduced into the product separation system 11 to be separated into gas and liquid products, and the unborn catalyst falls into the stripper due to gravity 7. Stripping The water vapor strips the adsorbed hydrocarbon products on the raw catalyst and enters the settler for gas-solid separation. The stripped raw catalyst enters the regenerator 4 through the inclined pipe 14 of the raw catalyst, and contacts with air at 680 ° C. High temperature scorched regeneration. The regenerated catalyst returns to the fluidized bed and the catalyst conveying pipe for recycling through the regenerated inclined pipe. The operating parameters and product analysis results in the experiment are shown in Table 3.

Example 2

Catalytic cracking of naphtha 1 is carried out according to the method of embodiment 1, the experimental device adopted is the same as embodiment 1, the difference is that the reaction temperature of the riser reactor is increased to 645 ° C, and the regeneration temperature of the regenerator is increased simultaneously to 710°C without olefin-rich C4 feed. The operating parameters and product analysis results in the experiment are shown in Table 3.

Comparative example 1

This comparative example illustrates the results of the reaction of Naphtha 1 on a conventional riser reactor catalytic cracking unit.

The experiment was carried out in a medium-sized riser catalytic cracking unit. The medium-sized plant riser reactor has an inner diameter of 16 mm and a height of 3800 mm. The test is operated in a single-pass manner. The high-temperature catalytic cracking catalyst at 675°C is introduced into the bottom of the riser reaction zone from the regenerator through the regenerated inclined pipe, and flows upward under the action of the pre-lift medium. After the naphtha 1 is preheated to 300°C and mixed with atomized water vapor, it enters the lower part of the riser reaction zone through the feed nozzle and contacts with the upward catalytic cracking catalyst for catalytic conversion reaction. Gas-solid separation is carried out through the rapid separation equipment at the outlet, and the reaction oil gas is introduced into the settler and then introduced into the product separation system to be separated into gas and liquid products. The raw catalyst flows into the stripper for stripping due to gravity, and the stripped water vapor strips the hydrocarbon products adsorbed on the raw catalytic catalyst and then flows into the settler for gas-solid separation. The stripped raw catalyst passes through the raw inclined tube Enter the regenerator, contact with air for 695 ℃ high-temperature burnt regeneration. The regenerated catalyst is returned to the reaction zone of the riser through the regenerated inclined pipe for recycling. The operating parameters and product analysis results in the experiment are shown in Table 3.

Example 3

Catalytic cracking of naphtha 1 is carried out according to the method of embodiment 1, the experimental device adopted is the same as embodiment 1, the difference is that the reaction temperature of the fluidized bed reactor is 560 ℃, simultaneously to the lower part of the riser reactor Complementary injection of nebulizing steam. The operating parameters and product analysis results in the experiment are shown in Table 3.

table 3

By comparing Example 1 with Comparative Example 1, it can be seen that the ethylene yield of Example 1 has increased by 4.55 percentage points, the propylene yield has increased by 10.81 percentage points, and the sum of the productive rates of (hydrogen+methane+coke) simultaneously fell by 1.10 percentage points.

By comparing Example 2 with Comparative Example 1, it can be seen that the ethylene yield of Example 2 has increased by 4.32 percentage points, the propylene yield has increased by 7.30 percentage points, and the yield of (hydrogen+methane+coke) is equivalent.

By comparing Example 3 with Comparative Example 1, it can be seen that the ethylene yield of Example 3 has increased by 4.12 percentage points, the propylene yield has increased by 9.26 percentage points, and the sum of the productive rates of (hydrogen+methane+coke) simultaneously fell by 0.23 percentage points.

Comparative example 2

Catalytic cracking of naphtha 1 is carried out according to the method of embodiment 1, and the experimental device adopted is the same as embodiment 1, and the difference is that C4 and naphtha 1 rich in olefins are jointly injected into the lower part of the riser reactor Participate in reactions. The operating parameters and product analysis results in the experiment are shown in Table 4.

Embodiment 4 and Embodiment 5

Naphtha 1 is catalytically cracked according to the method of Example 1, the experimental device adopted is the same as that of Example 1, the difference is that Naphtha 1 undergoes catalytic cracking under more severe reaction conditions, and is rich in olefins at the same time The C4 is injected into the lower part of the riser reactor. The operating parameters and product analysis results in the experiment are shown in Table 4.

Comparative example 3

The experimental device is the same as that of Comparative Example 1. This comparative example illustrates the reaction result of naphtha 1 in a conventional riser reactor catalytic cracking unit, and the reaction conditions of the riser reactor are more severe. The operating parameters and product analysis results in the experiment are shown in Table 4.

Table 4

By comparing Example 3 with Comparative Example 2, it can be seen that the ethylene yield of Example 3 has increased by 2.62 percentage points, the propylene yield has increased by 5.21 percentage points, and the sum of the productive rates of (hydrogen+methane+coke) simultaneously down 1.53 percentage points.

By comparing Example 4 with Comparative Example 3, it can be seen that the ethylene yield of Example 4 has increased by 5.26 percentage points, the propylene yield has increased by 7.45 percentage points, and the sum of the productive rates of (hydrogen+methane+coke) simultaneously A drop of 5.05 percentage points.

By comparing Example 5 with Comparative Example 3, it can be seen that the ethylene yield of Example 5 has increased by 4.31 percentage points, the propylene yield has increased by 5.32 percentage points, and the sum of the productive rates of (hydrogen+methane+coke) simultaneously A decrease of 4.37 percentage points.

Embodiment 6 and Embodiment 7

Catalytic cracking is carried out to naphtha 1 according to the method for embodiment 1, and the experimental device that adopts is identical with embodiment 1, and difference is, the raw material that enters fluidized bed reactor 1 is naphtha 2, further adjusts two simultaneously. The respective reaction conditions of each reaction zone, the C4 that is rich in olefins in example 6 is injected into the lower part of the riser reactor, and the C4 that is rich in olefins in example 7 is injected into the lower part of the catalyst delivery pipe. The operating parameters and product analysis results in the experiment are shown in Table 5.

Comparative example 4

The experimental device is the same as that of Comparative Example 1. This comparative example illustrates the reaction result of naphtha 2 in a catalytic cracking unit in a conventional riser reaction zone. The operating parameters and product analysis results in the experiment are shown in Table 5.

table 5

By comparing Example 6 with Comparative Example 4, it can be seen that the ethylene yield of Example 6 has increased by 2.78 percentage points, and the propylene yield has increased by 12.59 percentage points, while the sum of the productive rates of (hydrogen+methane+coke) A decrease of 2.48 percentage points.

By comparing Example 7 with Comparative Example 4, it can be seen that the ethylene yield of Example 7 has increased by 1.62 percentage points, the propylene yield has increased by 14.14 percentage points, and the sum of the productive rates of (hydrogen+methane+coke) simultaneously A decrease of 3.80 percentage points.

It can be seen that, according to the catalytic cracking method of the naphtha raw material provided by the present invention, the yield of non-ideal products hydrogen, methane, and coke can be kept unchanged or reduced while increasing the yield of ethylene and propylene.

Claims (16)

1. a catalytic cracking method for feed naphtha, the method comprises:

(1) make feed naphtha and the first catalytic cracking catalyst contact in the first reaction zone and react, obtain the first oil agent mixture;

(2) make the C4 being rich in alkene contact in second reaction zone with the second catalytic cracking catalyst and react, obtain the second oil agent mixture;

(3) described first oil agent mixture and described second oil agent mixture are introduced the 3rd reaction zone to react, the oil agent mixture obtained is carried out finish to be separated to obtain reclaimable catalyst and reaction oil gas, gasoline, diesel oil and C1-C4 component is isolated from described reaction oil gas, and from described C1-C4 component, isolate ethene, propylene further and be rich in the C4 of alkene, the isolated C4 being rich in alkene is injected second reaction zone at least partly and recycles;

Wherein, the temperature of reaction of described 3rd reaction zone is higher than the temperature of reaction of described first reaction zone, and the temperature of described second catalytic cracking catalyst is higher than the temperature of described first catalytic cracking catalyst.

2. method according to claim 1, wherein, described first reaction zone is fluidized-bed reactor.

3. method according to claim 2, wherein, described fluidized-bed reactor has the fluidized-bed structure in flaring footpath, and lower end diameter a, the upper end diameter b of the fluidized-bed structure in this flaring footpath and the ratio of high c are 1:1.5-10:10-30.

4. according to the method in claim 1-3 described in any one, wherein, the reaction conditions of described first reaction zone comprises: temperature is 520-630 DEG C, and agent-oil ratio is 5-25, and weight hourly space velocity is 4-20h ^-1.

5. method according to claim 4, wherein, the reaction conditions of described first reaction zone comprises: temperature is 560-620 DEG C, and agent-oil ratio is 10-15, and weight hourly space velocity is 4-16h ^-1.

6. method according to claim 1, wherein, described second reaction zone is catalyst transport.

7. the method according to claim 1 or 6, wherein, the reaction times of described second reaction zone is less than 1 second.

8. method according to claim 1, wherein, the reaction conditions of described 3rd reaction zone comprises: temperature is 630-700 DEG C, and agent-oil ratio is 10-40, and the time is 0.1-3 second, and pressure is 0.1-0.4MPa.

9. method according to claim 8, wherein, the reaction conditions of described 3rd reaction zone comprises: temperature is 630-675 DEG C, and agent-oil ratio is 15-30, and the time is 1-2.5 second, and pressure is 0.15-0.35MPa.

10. according to the method in claim 1,8 and 9 described in any one, wherein, described 3rd reaction zone is any one or the multiple combination in riser reactor, fluidized-bed reactor, downstriker transfer limes reactor and upstriker transfer limes reactor.

11. methods according to claim 1, wherein, described method also comprises: described reclaimable catalyst is carried out coke burning regeneration to obtain high-temperature regenerated catalyst, a part of high-temperature regenerated catalyst is cooled, and the circulation of the regenerated catalyst of cooling is used as described first catalytic cracking catalyst, the circulation of another part high-temperature regenerated catalyst is used as described second catalytic cracking catalyst simultaneously.

12. methods according to claim 1 or 11, wherein, the temperature of described first catalytic cracking catalyst is 560-650 DEG C, the temperature of described second catalytic cracking catalyst is 660-760 DEG C, and the temperature of described second catalytic cracking catalyst is than the temperature height 10-150 DEG C of described first catalytic cracking catalyst.

13. according to the method in claim 1,11 and 12 described in any one, and wherein, described first catalytic cracking catalyst and the second catalytic cracking catalyst are all less than the zeolite of 0.7nm containing aperture.

14. methods according to claim 1, wherein, described feed naphtha is at least one in virgin naphtha, cat cracked naphtha, steam cracking petroleum naphtha, coking naphtha and F-T synthesis petroleum naphtha.

15. methods according to claim 14, wherein, described feed naphtha is cat cracked naphtha, and its final boiling point is not higher than 110 DEG C.

16. methods according to claim 15, wherein, the olefin(e) centent in described cat cracked naphtha is 30-90 % by weight.