Inferior heavy oil catalytic cracking device with ultra-large catalyst-oil ratio and use method of inferior heavy oil catalytic cracking device

Abstract

The invention relates to the technical field of heavy oil catalytic cracking, in particular to an inferior heavy oil catalytic cracking device with an ultra-large catalyst-oil ratio and a use method thereof, which comprise a regenerator and a downer reactor which are coaxially and vertically arranged, and a catalyst flow controller, a regenerant distributor and a regenerant distribution pipe are sequentially and downwards connected between the regenerator and the downer reactor; a quick separator is arranged at the bottom of the downer reactor, a reaction cyclone separator is arranged in a settler, an outlet of the reaction cyclone separator is connected with a switchable parallel filter arranged outside the settler, reaction oil gas subjected to three-time gas-solid separation is separated by an oil-gas separation system, and a part of dry gas is returned to the downer reactor from a dry gas distributor after being pressurized by a circulating compressor. The invention solves the problems of low catalyst particle concentration in the reactor, poor adaptability to inferior heavy oil, low treatment capacity and low target product yield in the existing downer catalytic cracking device, and widens the application range of the downer reactor in the field of catalytic lightening of heavy inferior raw oil.

Description

Technical Field

[0001] The invention relates to the technical field of heavy oil catalytic cracking, and in particular to a low-quality heavy oil catalytic cracking device with a super-large catalyst-to-oil ratio and a use method thereof. Background Art

[0002] The catalytic cracking unit is a very important heavy oil lightening equipment in the refinery, and it is also the core device to measure the heavy oil conversion capacity and economic benefits of the refinery. However, with the continuous heaviness and inferiority of crude oil resources, the traditional catalyst-oil co-current upward riser reactor has exposed many drawbacks during operation. The main problems include: the riser reaction time is too long, resulting in severe secondary reactions and high coking rate; the catalyst slips and mixes due to gravity during the upward process; the catalyst-oil ratio cannot be too large due to choking problems during the upward process; the heat load limitation and the risk of coking and blockage at the feed part of the riser make the residual carbon value of the crude oil not too high, making it impossible to process heavy and inferior crude oil.

[0003] Compared with the traditional riser reactor, the feed and catalyst of the down-flow reactor both move downward in a nearly plug flow manner along the direction of the gravity field, and have the following advantages: good contact between the feed and the catalyst, uniform distribution of particle concentration and gas-solid velocity, small axial back-mixing, short gas-solid contact time, and few secondary reactions. These characteristics make the down-flow reactor show good application prospects in the fields of petrochemicals, coal chemical industry and biomass pyrolysis. However, due to the limitations of its own structure, the existing down-flow reactor has a low concentration of catalyst particles in the bed, which makes it difficult to cope with the operating conditions of super-large catalyst-to-oil ratio. This defect greatly limits the processing capacity of the down-flow reactor and its adaptability to heavy and inferior raw materials, and also restricts its industrial application in the field of catalytic cracking of heavy and inferior oil. Therefore, it is particularly necessary to develop a super-large catalyst-to-oil ratio catalytic cracking unit suitable for inferior heavy oil.

[0004] The Chinese invention patent (CN114410344B) discloses a method for catalytic conversion of inferior oil products, which can directly use heavy inferior crude oil to produce light olefins and aromatics. The method preheats the crude oil and sprays it into the first downer reactor to contact with the catalyst for the first reaction, then introduces the first reaction product and the catalyst flow into a reactor with an expanded diameter for the second reaction, and then introduces the oil and gas and the catalyst in the expanded diameter reactor into the second downer reactor for the third reaction. A quenching agent is introduced into the outlet of the second downer reactor. After the reaction is completed, the oil and gas products and the coked and deactivated catalyst to be regenerated are obtained by separation of the oil agent. The oil and gas products enter the fractionation tower, and the regenerated catalyst is recycled after regeneration. After the reaction products are separated, light olefins and aromatics are obtained, and some light components are introduced into the riser reactor to contact with the catalyst for the fourth reaction, and the semi-regenerated catalyst in the fourth reactor is sent to the expanded diameter reactor. The invention is suitable for catalytic conversion of inferior intermediate crude oil with low hydrogen content, high asphaltene, heavy metal and residual carbon content to produce light olefins and aromatic products, and has the characteristics of strong raw material adaptability and high yield of light olefins and aromatic products. However, the operating process of the invention has a low catalyst-to-oil ratio (the maximum catalyst-to-oil ratio is 30), which cannot provide a large number of reaction active centers for the catalytic cracking reaction, resulting in a complex process and low reaction efficiency.

[0005] The Chinese invention patent (CN114410340B) discloses a method for maximizing the production of light olefins and aromatics from crude oil, wherein the crude oil is preheated and sprayed into the first expansion reaction section of the descending reaction bed to contact with the catalytic cracking catalyst for a moderate catalytic cracking reaction, and then the oil obtained in the first expansion reaction section of the descending reaction bed is introduced into the second expansion reaction section for a moderate catalytic cracking reaction, and the product oil is introduced into the third expansion reaction section of the descending reaction bed for a deep catalytic cracking reaction to obtain oil and gas products and a catalyst to be regenerated. The oil and gas products are separated by a separation unit to obtain high-value chemical raw materials, and the catalyst to be regenerated is sent to a coke regenerator for catalyst regeneration after the residual oil and gas products are eluted by water vapor, and the regenerated catalyst is recycled. The method of the present invention is suitable for processing raw materials such as crude oil of various properties, vacuum wax oil, atmospheric residue oil and vacuum residue oil, and can maximize the production of light olefins and aromatics, with high selectivity for light olefins and light aromatics, low dry gas and coke yields, almost no fuel oil, simple process flow and low production cost. However, its shortcomings are the same as those of the invention patent CN114410344B mentioned above.

[0006] Chinese invention patent (CN116769506A) discloses a catalytic cracking downer reaction system and method, including a downer reactor and a quick separation device located at the outlet of the downer reactor. The downer reactor includes a return tube, a straight body and a booster. The inlet of the straight body is located inside the return tube, for receiving the catalyst output from the return tube, and the outlet of the straight body is located outside the return tube, for outputting the catalyst and oil gas in the straight body after the catalytic cracking reaction. The outlet of the booster passes through the top of the return tube and extends to the inlet of the straight body, for inputting a booster gas flow to push the catalyst from the return tube to the straight body. The present invention realizes high-throughput operation of catalyst particles in the downer and improves the production capacity of the downer reaction system. However, in order to increase the concentration of catalyst particles in the downer reactor, a large amount of fluidizing steam and booster gas / steam are introduced, which will correspondingly reduce the feed amount of crude oil, reduce the processing capacity of the downer reactor, and also reduce the temperature of the catalyst entering the downer reactor, so that the reaction efficiency is further reduced.

[0007] The Chinese invention patent (CN1390916A) discloses a method for catalytic thermal cracking of hydrocarbons using a down-going bed reactor, wherein the crude oil is heated to 350°C and then sprayed into the down-going bed reactor under the action of atomized steam, and the crude oil is contacted with the catalyst uniformly entering the top of the reactor in the oil-agent mixing zone, and the cracking reaction is carried out at 600-800°C and flows downward, and the weight ratio of the catalyst to the crude oil is 10-40. The gas-solid mixture is quickly separated in the gas-solid rapid separation device at the end of the down-going bed reactor, and then cooled to obtain gas and liquid products, and the deactivated catalyst is reused after regeneration. The invention can process heavy raw materials and adjust the ratio of ethylene and propylene by adjusting the process conditions. However, the invention does not specify how to achieve uniform distribution of the catalyst in the down-going bed, nor does it involve solutions to overcome the shortcomings of low catalyst density in the down-going bed reactor, as well as the degree of adaptability to inferior raw materials.

[0008] In summary, the existing catalytic cracking units have many deficiencies in processing heavy and inferior crude oil, and the development of a super-large catalyst-to-oil ratio catalytic cracking unit suitable for inferior heavy oil has important practical significance. By optimizing the layout and connection mode of the regenerator and the reactor, setting a volumetric catalyst flow controller, using the circulating dry gas to achieve short-range rectification of the catalyst, and improving the separation efficiency of the gas-solid two-phase flow, the circulation efficiency of the catalyst and the catalyst concentration in the reactor can be significantly improved, the secondary reaction and coke generation can be reduced, the yield of the target product can be increased, and the application of the down-flow bed reactor in the field of catalytic lightening of heavy and inferior crude oil can be broadened. Summary of the invention

[0009] In order to overcome the deficiencies in the background technology, the present invention discloses a low-quality heavy oil catalytic cracking device with a super-large catalyst-to-oil ratio and a method of using the same.

[0010] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0011] A low-quality heavy oil catalytic cracking device with a super-large catalyst-to-oil ratio comprises a regenerator and a descending bed reactor which are coaxially and vertically connected. A nozzle for introducing crude oil into the interior is arranged at the top of the upper section of the descending bed reactor, and a dry gas distributor for obliquely jetting upward is arranged above the corresponding nozzle. The lower section of the descending bed reactor is sealed in a reaction settler, and a quick separator is arranged at the outlet of the lower section of the descending bed reactor, comprising a quick separator expansion section with a trumpet-shaped structure, the large end of the quick separator expansion section is connected to an ellipsoidal quick separator head through a connecting rib sheet, and the spherical surface of the ellipsoidal quick separator head points to the smaller end of the trumpet of the quick separator. The bottom of the reaction settler is connected to a catalyst lifting pipe to be produced through an inclined pipe to be produced, and the outlet end of the catalyst lifting pipe to be produced is connected to the regenerator.

[0012] Preferably, the regenerator comprises a regenerator settling section, a regenerator charring section and a regenerator gas stripping section which are connected from top to bottom; the outlet end of the regenerator lifting pipe is connected to the regenerator settling section; the regenerator gas stripping section is connected to a regenerator distributor through a regenerator flow controller, and a plurality of regenerator distribution pipes for correspondingly connecting to the down-bed reactor are provided at annular intervals at the bottom of the regenerator distributor, and the outlet end of the regenerator distribution pipe is higher than the gas outlet of the dry gas distributor.

[0013] Preferably, the regeneration agent distribution pipe has an arc-shaped structure, and its inlet end and outlet end are evenly arranged along the outer side of the lower cone of the regenerator distributor and the upper outer side of the down-flow bed reactor respectively; the number of the regeneration agent distribution pipes is not less than 2.

[0014] Preferably, the dry gas distributor is annular in structure, and a plurality of gas distribution holes with a diameter of 1 to 6 mm are provided on an inner annular surface of which the horizontal plane is inclined upward at an angle of 50 to 85 degrees with the central axis of the down-flow bed reactor.

[0015] Preferably, the reaction settler comprises a reaction settling section and a reaction stripping section connected from top to bottom; a reaction cyclone is installed in the reaction settling section; a filter is provided on the outside of the reaction settler, the filter comprises a reaction filter a and a reaction filter b installed in parallel, and the lateral air inlets of the reaction filter a and the reaction filter b are both connected to the gas phase outlet of the reaction cyclone; the bottom solid outlet line of the filter is connected to the waste agent tank, and the top gas phase outlet line is connected to the oil-gas separation system; the oil-gas separation system is connected to a dry gas circulation compressor, and the dry gas circulation compressor gas circuit is divided into two circuits, one of which is connected to the dry gas distributor, and the other is used as an external dry gas K outlet device.

[0016] Preferably, the reaction filter a and the reaction filter b can be a single filter respectively, or a group of filters connected in parallel, each group of filters is connected to the back-blowing air H, and valves are provided on the gas phase inlet and outlet lines and the solid phase outlet lines of each group of filters. When one group of filters is working, the other group of filters can cut out the back-blowing, and filtering and back-blowing can be performed alternately.

[0017] Preferably, the pore size of the reaction filter a and the reaction filter b is no greater than 5µm.

[0018] Preferably, the lower outlet of the reaction stripping section is connected to the regenerated inclined tube through a regenerated agent flow controller; the regenerated agent flow controller and the regeneration agent flow controller rely on externally driven volumetric solid fine powder flow control equipment to control the amount of catalyst fine powder passing through the controller by changing the rotation speed of the internal volumetric metering component, and the rotation speeds of the two are cascade controlled with the regenerated catalyst level of the regenerator stripping section and the regenerated catalyst level of the regenerated agent stripping section, respectively.

[0019] The method of the low-quality heavy oil catalytic cracking unit with a super large catalyst-to-oil ratio is characterized by comprising the following steps:

[0020] S1. Catalyst cycle:

[0021] S11, the fresh catalyst and the catalyst to be regenerated are mixed and then burnt in a regenerator to remove carbon deposits, followed by gas stripping to restore catalyst activity;

[0022] S12, accurately controlling the catalyst flow rate through a regeneration agent flow controller, and evenly distributing the catalyst into the down-flowing bed reactor through a regeneration agent distributor and a distribution pipe;

[0023] S13, using circulating dry gas to perform short-range rectification on the catalyst to make it evenly distributed, and then reacting with the crude oil to produce a cracking reaction;

[0024] S14, the reacted catalyst is separated by a quick separator, a cyclone separator and a filter, and then enters the spent catalyst stripping section for stripping, and then returns to the regenerator through the spent catalyst flow controller and the riser to complete the catalyst cycle;

[0025] S2. Oil and gas processing:

[0026] S21, the oil gas and catalyst mixture generated by the reaction is subjected to gas-solid separation in a quick separator, and the separated solid catalyst enters the spent catalyst stripping section;

[0027] S22, the oil and gas after the primary separation and a small amount of catalyst fine powder carried by the stripping oil and gas enter the reaction cyclone for secondary gas-solid separation, and the separated catalyst particles enter the spent catalyst stripping section along the feed leg of the reaction cyclone;

[0028] S23, the oil and gas after the secondary separation enter the reaction filter for tertiary gas-solid separation, the filtered catalyst fine powder enters the waste agent tank, and the oil and gas pass through the filter and enter the oil and gas separation system;

[0029] S24. In the oil-gas separation system, the oil and gas are separated into gas and liquid, and the separated liquefied product is led out of the device, and the dry gas that cannot be liquefied is introduced into the dry gas circulation compressor; after the dry gas circulation compressor pressurizes the dry gas, a part of it is used as the external dry gas leading device, and the other part is returned to the down-flowing bed reactor from the dry gas distributor for short-range rectification of the catalyst.

[0030] Preferably, in step S11, the charred regenerated catalyst enters the stripping section of the regenerator and contacts the regenerated stripping gas in reverse direction for stripping; in step S12, the rotation speed of the flow controller is cascade-controlled with the catalyst level in the stripping section of the regenerator; in step S13, the regenerated catalyst is evenly distributed in different quadrants of the down-going bed reactor through the regeneration agent distribution pipe; in step S14, the preheated heavy and inferior crude oil is mixed with atomized steam, sprayed downward into the down-going bed reactor through a nozzle, contacts the rectified catalyst and undergoes a cracking reaction; the stripped catalyst to be regenerated enters the inclined pipe to be regenerated through the regeneration agent flow controller, and then ascends through the regeneration agent lifting pipe to enter the settling section of the regenerator to complete the catalyst circulation.

[0031] Due to the adoption of the above-mentioned technical solution, the present invention has the following beneficial effects:

[0032] The present invention significantly improves the catalyst circulation efficiency and catalyst concentration in the reactor by optimizing the arrangement and connection mode of the regenerator and the downer reactor, and at the same time realizes short-range rectification of the catalyst by circulating dry gas, improves the uniformity of oil-agent contact, inhibits over-cracking and coking reaction, and improves the yield of the target product. The specific beneficial effects are as follows:

[0033] (1) Optimize the layout of the regenerator and reactor:

[0034] Height difference design: The regenerator is coaxially arranged just above the down-bed reactor, forming a sufficient height difference, which increases the downward power and flow rate of the catalyst and creates conditions for achieving ultra-large catalyst-to-oil ratio operation.

[0035] Catalyst flow control: A volumetric regeneration catalyst flow controller is set up to avoid the problem of poor downward flow caused by factors such as catalyst particle flow resistance and bridging in traditional slide valves and L valves, thereby increasing the catalyst delivery capacity.

[0036] Catalyst distribution: The regenerated catalyst is quickly and evenly distributed in different quadrants of the down-flow reactor through the regenerator distributor and the regenerator distribution pipe to avoid coking and blockage caused by catalyst deviation.

[0037] Catalyst flow control: A spent catalyst flow controller is set between the spent catalyst stripping section and the spent catalyst inclined tube to achieve rapid and accurate transfer of catalyst between the regenerator and the downer reactor, ensuring the relative stability of the catalyst storage in the reaction and regeneration system.

[0038] (2) Using circulating dry gas to achieve short-range rectification of catalyst:

[0039] Dry gas circulation: The dry gas generated in the down-bed catalytic cracking reaction process is separated and pressurized by the dry gas circulation compressor. One part is used in the low-pressure gas system, and the other part is introduced into the down-bed reactor from the dry gas distributor to achieve short-range rectification of the catalyst.

[0040] Rectification effect: Through the dispersion effect of dry gas, the regenerated catalyst is evenly distributed in the bed space, improving the uniformity of oil-agent contact, reducing coke formation, and increasing the yield of the target product.

[0041] Chemical balance adjustment: The introduction of circulating dry gas changes the chemical balance of the catalytic cracking reaction, reduces the yield of low value-added dry gas components, and makes the reaction more conducive to the production of high value-added liquefied products.

[0042] (3) Improve the separation efficiency of gas-solid two-phase flow:

[0043] Quick separator design: Use a quick separator with simple structure and good separation effect to perform primary gas-solid separation, inhibit the occurrence of secondary reactions, and reduce the amount of coke produced.

[0044] Cyclone separation: After the primary separation, the reaction oil and gas and the stripping oil and gas enter the reaction cyclone for secondary separation to further improve the separation efficiency.

[0045] Filtration separation: The oil and gas after secondary separation enter two sets of parallel and switchable filters to achieve precise separation of ultrafine catalysts, extending the service life of the filters and the operating cycle of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic diagram of the framework structure of the present invention;

[0047] Figure 2 This is a schematic diagram of the structure of the fast divider.

[0048] In the figure: 1, regenerator; 101, regenerator settling section; 102, regenerator reaction section; 103, regenerator stripping section; 2, regeneration agent flow controller; 3, regeneration agent distributor; 4, regeneration agent distribution pipe; 5, nozzle; 6, downer reactor; 61, dry gas distributor; 62, quick separator; 621, quick separator expansion section; 622, ellipsoidal quick separator head; 623, connecting ribs; 7, reaction settling device; 701 reaction stripping section; 702, reaction settling section; 703, reaction Should be cycloned; 704, reaction filter a; 705, reaction filter b; 706, waste agent tank; 8, oil-gas separation system; 9, dry gas circulation compressor; 10, flow controller of regenerated agent; 11, inclined pipe to be regenerated; 12, lifting pipe of regenerated agent; A, dosing line; B, regeneration main air; C, regeneration agent gas stripping air; D, atomizing steam; E, crude oil; F, regenerated agent steam stripping gas; G, regenerated agent lifting air; H, backblowing air; J, liquefied product; K, external exhaust dry gas; L, regeneration flue gas line. DETAILED DESCRIPTION

[0049] The present invention can be explained in detail through the following embodiments. The purpose of disclosing the present invention is to protect all technical improvements within the scope of the present invention. In the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "front", "back", "left", "right", etc. indicating directions or positional relationships, they only correspond to the drawings of the present application for the convenience of describing the present invention, and do not indicate or imply that the device or element referred to must have a specific direction.

[0050] Embodiment 1, in combination with Figures 1-2 A catalytic cracking device for inferior heavy oil with a super large catalyst-to-oil ratio and a method for using the same, wherein the regenerator 1 is coaxially arranged and is located directly above the down-going bed reactor 6.

[0051] It should be noted that the regenerator and reactor of the traditional riser catalytic cracking unit and downer catalytic cracking unit are generally arranged in two ways: high-low parallel and coaxial. The high-low parallel arrangement is that the two devices are arranged horizontally and parallel, and the height difference between the regenerator and the reactor in the vertical direction is small; the coaxial reactor settling section is partially inserted into the regenerator, and the height difference between the two devices is also limited; therefore, the driving force for the circulation of the catalyst between the two devices mainly comes from the operating pressure difference rather than the height difference.

[0052] The present invention arranges the regenerator 1 coaxially just above the down-flowing bed reactor 6, and the two are completely separated in the vertical direction, which forms a sufficient height difference between the regenerator and the reactor. In addition to the traditional operating pressure difference between the two vessels, the circulation driving force of the catalyst also increases the static pressure difference of the catalyst formed by the height difference. Under the same operating pressure, more downward power can be provided for the catalyst, that is, under the same operating conditions and flow area, more catalyst flow can be provided for the down-flowing bed reactor, creating good conditions for achieving ultra-large catalyst-to-oil ratio operation.

[0053] A fresh catalyst dosing line A and a regeneration flue gas line L are provided at the top of the regenerator 1 to facilitate the addition of fresh catalyst and the discharge of flue gas. The regenerator 1 is divided into three parts from top to bottom: a regenerator settling section 101, a regenerator regeneration section 102 and a regenerator stripping section 103. The smooth flow of the catalyst is achieved through a connecting structure between the parts.

[0054] At the bottom of the regenerator stripping section 103, a regenerator flow controller 2, a regenerator distributor 3 and a regenerator distribution pipe 4 are connected in sequence from top to bottom. The arrangement of these components is intended to accurately control the flow of the regenerated catalyst and evenly distribute it to the down-flowing bed reactor 6, and the down-flow of the catalyst is proportional to the rotation speed of the controller. In addition, a reaction settler 7, a regenerator flow controller 10 and a regenerator inclined pipe 11 are also connected, wherein the outlet of the regenerator inclined pipe 11 is connected to the regenerator settling section 101 through a lifting pipe 12, forming a circulation channel that can control the flow of the catalyst, ensuring efficient circulation of the catalyst in the system.

[0055] It is worth noting that since the rotation of the flow controller 2 is driven by external power, the problem of poor downward flow caused by factors such as flow resistance and bridging of catalyst particles in traditional sliding valves and L valves is avoided, and the catalyst delivery rate from the regenerator 1 to the downward bed reactor 6 is increased.

[0056] Catalyst cycle process:

[0057] When the device is started or fresh catalyst needs to be added, the fresh catalyst enters the regenerator settling section 101 through the dosing line A. Here, it is mixed with the catalyst to be regenerated returned from the catalyst to be regenerated lifting pipe 12, and then falls down into the regeneration section 102 of the regenerator. In the regeneration section 102 of the regenerator, the catalyst contacts the regeneration main air B preheated to a certain temperature in reverse direction, and is charred in a fluidized state. This process can effectively remove the carbon deposits on the surface and pores of the catalyst to be regenerated, so that its activity is fully restored and ready for subsequent catalytic reactions.

[0058] After the charred regenerated catalyst flows out of the regenerator stripping section 103, it flows downward through the regenerator flow controller 2 and enters the regenerator distributor 3. In order to ensure the effective isolation of the oxygen environment of the regeneration system and the hydrocarbon environment of the reaction system, the regenerator stripping section 103 needs to maintain a sufficient material level. The cascade control between the catalyst material level of the regenerator stripping section and the regenerator flow control valve can ensure that the regenerator stripping section has a sufficient catalyst material level, and effectively achieves the effective isolation between the oxygen environment of the regenerator and the hydrocarbon environment of the down-bed reactor.

[0059] Multiple arc-shaped regeneration agent distribution pipes 4 are evenly arranged on the outer side of the lower cone of the regeneration agent distributor 3 and the outer side of the upper part of the down-bed reactor 6. By adjusting the number and cross-sectional area of ​​the regeneration agent distribution pipes 4, the regenerated catalyst can flow quickly and evenly downward from the regeneration agent distributor 3 into different quadrants of the down-bed reactor 6. Such a design not only improves the uniformity of catalyst distribution, but also enhances the concentration of catalyst in the reactor, providing more active centers for catalytic cracking reactions; and avoids coking and blockage at the raw material nozzle of the down-bed reactor due to catalyst deviation, which affects the flow of catalyst.

[0060] Setting of dry gas distributor and feed nozzle:

[0061] The connection position between the regeneration agent distribution pipe 4 and the down-flow reactor 6 should be appropriately higher than the installation position of the dry gas distributor 61, and the number should be no less than 2. The dry gas distributor 61 is a circular hollow tube installed close to the inner wall of the down-flow reactor 6. On its inner annular surface with an angle of 50 to 85 degrees between the horizontal plane and the center axis of the reactor, there are several gas distribution holes with a diameter of 1 to 6 mm. The preferred opening angle is 60 to 75 degrees, and the diameter of the distribution hole is 2-4 mm. Its installation position should be between the regeneration agent distribution pipe 4 and the lower outlet of the feed nozzle 5.

[0062] The feed nozzle 5 passes through the center of the top cover of the down-bed reactor 6 and extends downward to below the installation position of the dry gas distributor 61. Through the combination of the structural form, relative position and operation process of the above-mentioned regeneration agent distribution pipe 4, dry gas distributor 61 and feed nozzle 5, the following four purposes can be achieved: first, multiple large-flux downward channels are provided for the regenerated catalyst to prevent catalyst bridging and blockage; second, the regenerated catalyst is evenly distributed in different quadrants of the down-bed reactor 6 to increase the average concentration of catalyst particles in the reactor; third, the regenerated catalyst entering the down-bed is blown obliquely upward to the top of the reactor by utilizing the dispersing effect of the circulating dry gas, and short-range rectification is achieved after rebound, creating good conditions for full mixing of the oil agent; fourth, the oil agent mixing effect is improved, more active centers are provided for the catalytic cracking reaction of the crude oil, secondary reactions and coke yield are reduced, and the adaptability to heavy and inferior crude oil and the stability of the device operation are improved.

[0063] Cracking reaction of crude oil and oil-gas separation:

[0064] After the heavy and inferior crude oil E preheated to a certain temperature is mixed with the atomized steam D, it is sprayed downward from the nozzle 5 into the descending bed reactor 6. Here, the crude oil is fully in contact with the regenerated catalyst that enters from the regeneration agent distribution pipe 4 and is short-circuited by the circulating dry gas sprayed from the dry gas distributor 61, and a cracking reaction occurs while descending. When the catalyst and the oil-gas mixture descend to the quick separator 62 located at the bottom outlet of the descending bed reactor 6, the downward catalyst is greatly decelerated by the collision effect, realizing the first rapid separation of the catalyst and the oil and gas. This process can effectively inhibit the occurrence of secondary reactions and prevent the separated catalyst from fluidizing again.

[0065] The quick separator 62 is located in the reaction settler 7, and is composed of a quick separator expansion section 621, an ellipsoidal quick separator head 622 and a connecting rib 623. The connecting rib 623 fixes the ellipsoidal quick separator head 622 to the inner wall of the quick separator expansion section 621, and the quick separator expansion section 621 is a trumpet-shaped structure that is small at the top and large at the bottom. The ellipsoidal quick separator head 622 is a horizontally placed semi-ellipsoidal shape, located at the bottom center of the quick separator expansion section 621, and its spherical surface points to the smaller end of the trumpet of the quick separator 62. The major axis diameter d2 of the ellipsoidal quick separator head 622 is smaller than the inner diameter d3 of the quick separator expansion section 621, but larger than the inner diameter d1 of the down-flowing bed reactor 6. Wherein d1, d2 and d3 satisfy , preferably .

[0066] After the reaction, the catalyst is separated once and then slides down into the spent catalyst stripping section 702. Here, the catalyst contacts the spent catalyst stripping gas F entering from the lower part of the spent catalyst stripping section 702 in reverse direction, stripping out the catalyst particles and the oil and gas in the pores. The stripping oil and gas, the reaction oil and gas and a small amount of catalyst powder entrained therein enter the reaction cyclone 703 for secondary gas-solid separation. The separated catalyst particles enter the spent catalyst stripping section 701 along the feed leg of the reaction cyclone 703 to maximize the recovery of available catalyst.

[0067] The oil and gas flowing out of the gas phase outlet line of the reaction cyclone 703 continues to go up and enter one of the parallel reaction filters a704 or reaction filters b705 for three gas-solid filtration separations. The reaction filter a704 or the reaction filter b705 performs switching operations according to the pressure difference. For example, when the reaction filter a704 is in operation and the reaction filter b705 is in standby mode, if the operating pressure difference of the reaction filter a704 is greater than 5KPa, the gas phase flowing out of the reaction cyclone 703 can be cut into the reaction filter b705 by switching the corresponding valve. The catalyst attached to the filter cartridge of the reaction filter a704 is blown off by back-blowing H, so that its pressure difference drops below 0.1KPa for standby. Similarly, when the operating pressure difference of the reaction filter b705 reaches 5KPa, the back-blowing standby of the reaction filter b705 is realized by performing similar operations. Repeatedly, the continuous operation of the reaction filter can be realized.

[0068] It is worth noting that when the reaction oil gas and catalyst mixture flows downward to the quick separator 62, it collides with the ellipsoidal quick separator 622, and the downward speed of the solid catalyst particles is greatly reduced, and they slide along the ellipsoidal quick separator 622 into the reaction settler 7. The speed of the gas phase product does not change much, and it continues to flow out along the annular gap between the expansion section and the ellipsoidal quick separator 622. The gas and solid phases are quickly separated, and the occurrence of secondary reactions is suppressed. Since the speed of the catalyst sliding down from the ellipsoidal quick separator 622 is low, it can be avoided that it produces secondary fluidization in the reaction settler 7, which greatly reduces the subsequent gas-solid separation. The impact of the facilities; in order to further improve the separation degree of the reaction oil and gas and the catalyst, the reaction oil and gas and the stripping oil and gas after the primary separation carry a small amount of catalyst fine powder and enter the reaction cyclone for secondary separation to recover as much catalyst as possible; the oil and gas after the secondary separation are drawn out of the reaction settler 7 and enter two sets of filters that are connected in parallel and can be switched with each other to achieve the precise separation of the ultrafine catalyst. The separated catalyst is too small in particle size and belongs to Class C particles, which is not suitable for fluidized catalytic cracking reaction, so it is collected in the waste agent tank 706 as waste catalyst; the precise separation of the ultrafine catalyst is achieved. The filter cartridge pore size of the reaction filter a704 and the reaction filter b705 is not greater than 5µm, preferably not greater than 3µm. The oil and gas after the tertiary separation are introduced into the oil and gas separation system, which ensures the stable operation of the separation system and the dry gas circulation compressor; in addition, since the filter is arranged outside the reaction settler 7, it is convenient to reduce the temperature of the reaction oil and gas, and further reduce the secondary reaction of unstable components; at the same time, it is convenient to overhaul and replace the filter without stopping, extending the service life of the filter and the operation cycle of the device.

[0069] Oil and gas separation and circulation:

[0070] The oil and gas passing through the reaction filter a704 or the reaction filter b705 enter the oil and gas separation system 8 for gas-liquid separation. The separated liquefied product J is led out of the device, while the dry gas that cannot be liquefied is introduced into the dry gas circulation compressor 9. After being pressurized, a part of the dry gas is led out of the device as the external exhaust dry gas K, and the other part is introduced into the dry gas distributor 61, which is used to perform short-range rectification on the regenerated catalyst entering the down-bed reactor 6 and inhibit excessive cracking reaction. Since the circulating dry gas contains more hydrogen and methane, its introduction changes the chemical balance and product distribution of the catalytic cracking reaction, significantly reduces the yield of low-value-added dry gas such as hydrogen and methane, increases the yield of high-value-added liquefied products, reduces the coke generation in the down-bed catalytic cracking process, and creates good conditions for the heavy and inferior quality of the crude oil.

[0071] It should be noted that the catalytic cracking process will generate dry gas equivalent to 3% to 5% of the total feed amount and varying amounts of coke due to factors such as catalyst contamination, deterioration of raw materials, poor contact with oil agents, and harsh operating conditions. These are low-value-added products that are not desired to be generated in the catalytic cracking process. The present invention separates the dry gas generated in the down-going bed catalytic cracking reaction process, and after being pressurized by the dry gas circulation compressor 9, a part of it enters the low-pressure gas system after desulfurization, and the other part is introduced into the down-going bed reactor from the dry gas distributor 61 installed between the regeneration agent distribution pipe 4 and the outlet of the feed nozzle 5, and is sprayed upward at an angle of 50 to 85 degrees to the central axis of the reactor, blowing the regenerated catalyst flowing into the down-going bed reactor 6 along the regeneration agent distribution pipe 4 to the top of the reactor, and rebounding from the inside of the top cover and falling evenly along the cross-section of the bed, thereby achieving the purpose of rectifying the down-going catalyst in a shorter bed space; since the rectified catalyst is evenly distributed throughout the bed space, The heavy and inferior raw material droplets sprayed from the atomizing nozzle can evenly contact the catalyst and undergo cracking reaction, which increases the number of reactive centers, correspondingly increases the yield of the target product, and reduces the formation of coke; at the same time, due to the introduction of circulating dry gas into the reaction system, the chemical balance of the catalytic cracking reaction is changed, and the yield of low-value-added dry gas components such as hydrogen and methane is significantly reduced, making the catalytic cracking reaction develop in a direction that is more conducive to the generation of high-value-added liquefied products; in addition, due to the increase in the concentration of catalyst particles in the down-going bed reactor, it can also prevent the raw oil from being sprayed onto the reactor wall to cause coking and blockage, creating good conditions for the heavy and inferior quality of the raw oil.

[0072] Catalyst flow control and circulation:

[0073] The catalyst to be regenerated that has been stripped in the stripping section 701 of the regenerated catalyst moves downward and is metered by the flow controller 10 of the regenerated catalyst, and then slides along the inclined tube 11 to the connection between the inclined tube 11 and the rising tube 12 of the regenerated catalyst. Here, under the action of the rising wind G of the regenerated catalyst, the catalyst to be regenerated moves upward along the rising tube 12 of the regenerated catalyst and enters the settling section 101 of the regenerator 1. The flow controller 10 of the regenerated catalyst is a volumetric catalyst powder metering device that rotates by external drive, and its flow rate is proportional to the rotation speed. The higher the rotation speed, the greater the flow rate of the catalyst passing through, and vice versa. In order to achieve the balance of the catalyst in and out of the descending bed reactor 6, and at the same time achieve the isolation between the reaction separation system in the hydrocarbon-facing area and the catalyst lifting and regeneration system in the oxygen-facing area, the catalyst bed in the stripping section 701 of the regenerated catalyst must maintain a sufficient height, that is, the material level. The material level and the rotation speed of the regenerated catalyst flow controller 10 are cascade regulated.

[0074] So far, the recycling regeneration of the catalyst in the entire down-bed catalytic cracking unit and the catalytic cracking reaction process of heavy and low-quality crude oil have been completed. This process not only improves the utilization efficiency of the catalyst, but also provides a strong guarantee for the efficient conversion of heavy and low-quality crude oil.

[0075] Embodiment 2, in combination with Figures 1-2 , a low-quality heavy oil catalytic cracking unit with a super-large catalyst-to-oil ratio and a method of using the same, which is different from Example 1 in that, on the basis of Example 1, the super-large catalyst-to-oil ratio catalytic cracking unit of the present invention is used as a pilot plant, and its catalyst storage capacity is 150kg.

[0076] During the test, the catalyst balance agent or aging agent is added into the regenerator 1 along the catalyst addition line A, and the corresponding fluidized medium is opened to allow the catalyst entering the regenerator to circulate and preheat in the device.

[0077] The specific implementation process is as follows:

[0078] Turn on the heaters in various parts to preheat the equipment, raw materials, main air, etc.

[0079] The regenerator 1, the regenerator flow controller 2, the regenerator distributor 3 and the regenerator distribution pipe 4 are all preheated to 650°C, and the pressure at the top of the regenerator is 0.175MPa; the down-flow bed reactor 6 is preheated to 520°C; the reaction settler 7, the regenerated agent flow controller 10, the regenerated inclined pipe 11 and the regenerated agent lifting pipe 12 are all preheated to 490°C, and the pressure at the top of the reaction settler is 0.150MPa; the reaction filter a704 and the reaction filter 705 and their auxiliary systems are preheated to 350°C, and the filter backwash pressure difference is set to 5KPa. When the pressure difference is greater than this set value, the two filters will automatically switch for backwashing; the outlet pressure of the circulating dry gas compressor is set to 0.50MPa; the fluidizing air B and the regenerated agent lifting air G are all preheated to 200°C; the regenerated gas stripping gas C, the atomizing steam D, the crude oil E and the regenerated agent stripping gas F are all preheated to 350°C.

[0080] During the preheating process of the device, the catalyst entering the regenerator flows downward along the settling section 101 of the regenerator 1, and flows through the regenerator regeneration section 102, the regenerator stripping section 103, the regeneration agent flow controller 2, the regeneration distributor 3, the regeneration distributor 4, the downer bed reactor 6, the quick separator 62, the reaction settler 7, the regenerated agent flow controller 10 and the regenerated inclined pipe 11 in sequence, and then goes up along the regenerated agent lifting pipe 12 under the action of the regenerated agent lifting wind G and enters the regenerator 1 from the regenerated agent settling section 101, completing the catalyst circulation in the device. During the catalyst circulation heating process, the regeneration stripping gas C, the atomizing steam D, the feedstock oil E, the regenerated agent stripping gas F, the regenerated agent lifting wind G, the back-blowing wind H and the circulating dry gas are all replaced by air, and their pressure and dosage are adjusted at any time according to the operation of the device.

[0081] When the crude oil, various process media and various parts of the device have reached the set temperature, the regeneration stripping gas C, the spent catalyst lifting air G and the back-blowing air H are switched to nitrogen, and the atomizing steam D and the spent catalyst stripping gas F are switched to water vapor. The replacement is carried out for at least 10 minutes. After the hydrocarbon area is basically free of oxygen, the crude oil E is switched from air to crude oil. The amount of atomizing steam is 5% of the mass of the crude oil feed amount. The crude oil is vacuum residue oil with a density of 0.985g / cm 3 , the residual carbon value is 22.7%, the feed rate is 1.0kg / h; the micro-reaction activity of the catalyst used in the experiment is 66, the catalyst flow rate of the regeneration agent flow controller 2 and the regeneration agent flow controller 10 are both set to 50kg / h, that is, the catalyst-oil ratio is set to 50. The conversion rate of the raw material in the experimental process is 56.62m%, and the light oil yield is 59.33m%.

[0082] Embodiment 3, in combination with Figures 1-2A catalytic cracking device of inferior heavy oil with super large catalyst-to-oil ratio and its use method, based on Example 1 or 2, the regenerator 1, the regeneration agent flow controller 2, the regeneration distributor 3 and the regeneration distribution pipe 4 are all preheated to 680°C, and the downer reactor 6 is preheated to 540°C; the raw oil is atmospheric residue oil with a density of 0.962g / cm 3 , the residual carbon value is 9.3%, the feed rate is 1.2kg / h; the micro-reaction activity of the catalyst used in the experiment is 62, the catalyst flow rate of the regeneration agent flow controller 2 and the catalyst flow controller 10 are both set to 150kg / h, that is, the catalyst-oil ratio is set to 125. The conversion rate of the experimental process is 68.47m%, and the light oil yield is 71.06m%. Other conditions and processes are the same as those in Example 1.

[0083] Embodiment 4, in combination with Figures 1-2 A catalytic cracking device of inferior heavy oil with super large catalyst-oil ratio and its use method, based on any one of embodiments 1 to 3, the regenerator 1, the regeneration agent flow controller 2, the regeneration distributor 3 and the regeneration distribution pipe 4 are all preheated to 670°C, and the downer reactor 6 is preheated to 525°C; the raw oil is circulating oil with a density of 1.10 g / cm 3 , the residual carbon value is 11.4%, the feed rate is 1.5kg / h; the micro-reaction activity of the catalyst used in the experiment is 60, the catalyst flow rate of the regeneration agent flow controller 2 and the regeneration agent flow controller 10 are both set to 100kg / h, that is, the catalyst-oil ratio is set to 66.7. The conversion rate of the experimental process is 44.18m%, and the light oil yield is 55.20m%. Other conditions and processes are the same as those in Example 1.

[0084] The parts of the present invention that are not described in detail are prior art. It is obvious to those skilled in the art that the present invention is not limited to the details of the above-mentioned exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic characteristics of the present invention; therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and it is intended that all changes that fall within the meaning and scope of equivalent elements are included in the present invention.

Claims

1. A catalytic cracking unit for inferior heavy oil with a super large catalyst-oil ratio, characterized by: The invention comprises a regenerator and a descending bed reactor which are coaxially and vertically connected. A nozzle for introducing crude oil into the interior is arranged at the top of the upper section of the descending bed reactor, and a dry gas distributor for obliquely jetting upward is arranged above the corresponding nozzle. The lower section of the descending bed reactor is sealed in a reaction settler, and a quick separator is arranged at the outlet of the lower section of the descending bed reactor, which comprises a quick separator expansion section with a trumpet-shaped structure, and the large end of the quick separator expansion section is connected to an ellipsoidal quick separator head through a connecting rib sheet, and the spherical surface of the ellipsoidal quick separator head points to the smaller end of the trumpet of the quick separator. The bottom of the reaction settler is connected to a raw material lifting pipe through a raw material inclined pipe, and the outlet end of the raw material lifting pipe is connected to the regenerator.

2. The low-quality heavy oil catalytic cracking unit with a super large catalyst-to-oil ratio as claimed in claim 1 is characterized by: The regenerator comprises a regenerator settling section, a regenerator charring section and a regenerator gas stripping section which are connected from top to bottom; the outlet end of the regenerator lifting pipe is connected to the regenerator settling section; the regenerator gas stripping section is connected to a regenerator distributor through a regenerator flow controller, and a plurality of regenerator distribution pipes for correspondingly connecting to the down-bed reactor are arranged at intervals along the annular direction at the bottom of the regenerator distributor, and the outlet end of the regenerator distribution pipe is higher than the gas outlet of the dry gas distributor.

3. The low-quality heavy oil catalytic cracking unit with a super large catalyst-to-oil ratio as claimed in claim 2 is characterized by: The regeneration agent distribution pipe is an arc-shaped structure, and its inlet end and outlet end are evenly arranged along the outer side of the lower cone of the regenerator distributor and the outer side of the upper part of the descending bed reactor respectively; The number of regeneration agent distribution pipes shall not be less than 2.

4. The low-quality heavy oil catalytic cracking unit with a super large catalyst-to-oil ratio as claimed in claim 1 is characterized by: The dry gas distributor is annular in structure, and a plurality of gas distribution holes with diameters of 1 to 6 mm are provided on the inner annular surface of which the horizontal plane is inclined upward at an angle of 50 to 85 degrees with the central axis of the down-flowing bed reactor.

5. The low-quality heavy oil catalytic cracking unit with a super large catalyst-to-oil ratio as claimed in claim 1 is characterized by: The reaction settler comprises a reaction settling section and a reaction stripping section which are connected from top to bottom; a reaction cyclone is installed in the reaction settling section; a filter is arranged on the outside of the reaction settler, the filter comprises a reaction filter a and a reaction filter b which are installed in parallel, and the lateral air inlets of the reaction filter a and the reaction filter b are both connected to the gas phase outlet of the reaction cyclone; the bottom solid outlet line of the filter is connected to the waste agent tank, and the top gas phase outlet line is connected to the oil-gas separation system; the oil-gas separation system is connected to a dry gas circulation compressor, and the dry gas circulation compressor gas circuit is divided into two circuits, one of which is connected to a dry gas distributor, and the other is used as an external dry gas K outlet device.

6. The low-quality heavy oil catalytic cracking unit with a super large catalyst-to-oil ratio as claimed in claim 5 is characterized by: The reaction filter a and the reaction filter b can be a single filter or a group of filters connected in parallel. Each group of filters is connected to the back-blowing air H. Valves are provided on the gas phase inlet and outlet lines and the solid phase outlet lines of each group of filters. When one group of filters is working, the other group of filters can cut out the back-blowing, and filtering and back-blowing can be performed alternately.

7. The low-quality heavy oil catalytic cracking unit with a super large catalyst-to-oil ratio as claimed in claim 6 is characterized by: The pore size of the reaction filter a and the reaction filter b is no greater than 5 μm.

8. The low-quality heavy oil catalytic cracking unit with a super large catalyst-to-oil ratio as claimed in claim 7 is characterized by: The lower outlet of the reaction stripping section is connected to the regenerated inclined pipe through a regenerated agent flow controller; the regenerated agent flow controller and the regeneration agent flow controller rely on externally driven volumetric solid fine powder flow control equipment, and control the amount of catalyst fine powder passing through the controller by changing the rotation speed of the internal volumetric metering component, and the rotation speeds of the two are cascade controlled with the regenerated catalyst material level of the regenerator stripping section and the regenerated catalyst material level of the regenerated agent stripping section.

9. A method for using a low-quality heavy oil catalytic cracking unit with a super-large catalyst-to-oil ratio as claimed in any one of claims 1 to 8, characterized in that: The following steps are involved: S1. Catalyst cycle: S11, the fresh catalyst and the catalyst to be regenerated are mixed and then burnt in a regenerator to remove carbon deposits, followed by gas stripping to restore catalyst activity; S12, accurately controlling the catalyst flow rate through a regeneration agent flow controller, and evenly distributing the catalyst into the down-flowing bed reactor through a regeneration agent distributor and a distribution pipe; S13, using circulating dry gas to perform short-range rectification on the catalyst to make it evenly distributed, and then reacting with the crude oil to produce a cracking reaction; S14, the reacted catalyst is separated by a quick separator, a cyclone separator and a filter, and then enters the spent catalyst stripping section for stripping, and then returns to the regenerator through the spent catalyst flow controller and the riser to complete the catalyst cycle; S2. Oil and gas processing: S21, the oil gas and catalyst mixture generated by the reaction is subjected to gas-solid separation in a quick separator, and the separated solid catalyst enters the spent catalyst stripping section; S22, the oil and gas after the primary separation and a small amount of catalyst fine powder carried by the stripping oil and gas enter the reaction cyclone for secondary gas-solid separation, and the separated catalyst particles enter the spent catalyst stripping section along the feed leg of the reaction cyclone; S23, the oil and gas after the secondary separation enter the reaction filter for tertiary gas-solid separation, the filtered catalyst fine powder enters the waste agent tank, and the oil and gas pass through the filter and enter the oil and gas separation system; S24. In the oil-gas separation system, the oil and gas are separated into gas and liquid, the separated liquefied product is led out of the device, and the dry gas that cannot be liquefied is introduced into the dry gas circulation compressor; After the dry gas circulation compressor pressurizes the dry gas, a part of it is used as the external dry gas outlet device, and the other part returns to the down-flowing bed reactor from the dry gas distributor for short-range rectification of the catalyst.

10. The method for using the low-quality heavy oil catalytic cracking unit with a super-large catalyst-to-oil ratio as claimed in claim 9, characterized in that: In the step S11, the charred regenerated catalyst enters the stripping section of the regenerator and contacts the regenerated stripping gas in reverse direction for stripping; in the step S12, the rotation speed of the flow controller is cascade-controlled with the catalyst level in the stripping section of the regenerator; in the step S13, the regenerated catalyst is evenly distributed in different quadrants of the down-going bed reactor through the regeneration agent distribution pipe; in the step S14, the preheated heavy and low-quality crude oil is mixed with the atomized steam, sprayed downward into the down-going bed reactor through the nozzle, contacts with the rectified catalyst and undergoes a cracking reaction; the stripped catalyst to be regenerated enters the inclined pipe to be regenerated through the regenerated agent flow controller, and then goes up through the regenerated agent lifting pipe to enter the settling section of the regenerator to complete the circulation of the catalyst.

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