A dual-catalyst catalytic cracking unit and method for improving the yield of low-carbon olefins and gasoline / diesel.
By using different catalysts in risers and fluidized bed reactors in the catalytic cracking unit, the problem of mismatch between heavy oil catalysts and light oil catalysts was solved, which improved the yield of low-carbon olefins and gasoline and diesel, and reduced energy consumption and catalyst consumption.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- PETROCHINA CO LTD
- Filing Date
- 2022-06-22
- Publication Date
- 2026-05-26
AI Technical Summary
In existing catalytic cracking technologies, the active components of heavy oil catalysts and light oil catalysts are mismatched, resulting in incomplete cracking of heavy oil products, high yields of dry gas and coke, high catalyst consumption, high energy consumption, high heat consumption of riser units, and low overall efficiency.
A dual-catalyst catalytic cracking unit is adopted, including a riser reactor and a fluidized bed reactor, which use different catalysts to carry out cracking in their respective reaction zones. The catalysts are separated and regenerated by a cyclone separator and a settling tank, and the reaction conditions are optimized to improve the yield of low-carbon olefins and gasoline and diesel.
It improves catalyst utilization efficiency, reduces dry gas and coke yields, reduces energy consumption, and increases the yields of low-carbon olefins and gasoline/diesel. The catalysts perform at their maximum capacity in their respective reaction zones, avoiding mutual interference.
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Figure CN117304972B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalytic cracking technology, specifically relating to a dual-catalyst catalytic cracking device and method for improving the yield of low-carbon olefins and gasoline / diesel. Background Technology
[0002] my country's refining capacity exceeds 100 million tons, and the growth rate of refined oil demand has slowed significantly. While refining capacity is excessive, my country's consumption of ethylene and propylene is increasing year by year, while low-carbon olefins, as basic organic chemical raw materials, remain in significant shortage. Due to my country's refining overcapacity and low-carbon olefin shortage, the transformation of refining enterprises towards low-carbon olefin production is an inevitable trend. Given the current overcapacity and insufficient processing capacity of refining units, fully utilizing existing catalytic cracking units to achieve the transformation from refining to chemical production undoubtedly has broad and attractive application prospects.
[0003] Petroleum resources are becoming increasingly heavier and of lower quality, mainly manifested in the increased density and viscosity of crude oil, as well as higher levels of heavy metals, sulfur, gums, and asphaltenes. Consequently, the residue oil after atmospheric and vacuum distillation is also showing an increasingly heavy trend. How to extract more and better products, such as gasoline, diesel, and low-carbon olefins, from low-quality heavy oil and maximize its economic value has been a key issue that researchers have long studied.
[0004] Currently, the vast majority of low-carbon olefins originate from petroleum resources. Over 95% of ethylene and over 60% of propylene are derived from steam cracking processes using naphtha as the primary feedstock, consuming a large amount of high-quality light hydrocarbon feedstock annually. Developing catalytic cracking for low-carbon olefin production will address the tight feedstock supply issue and provide the necessary raw material conditions for expanding low-carbon olefin production capacity. Therefore, research and development of new low-carbon olefin technologies suitable for cheaper petroleum hydrocarbon feedstocks are crucial.
[0005] The production of low-carbon olefins using catalytic cracking can utilize different types of feedstocks, resulting in lower costs, wider applicability to feedstocks, and a wider range of feedstock sources. Changing feedstocks does not require shutdowns; only the catalytic cracking catalyst needs to be replaced during production.
[0006] CN1393508A discloses a catalytic conversion method for increasing the production of diesel and low-carbon olefins, employing a riser reactor containing an oil-solvent mixing chamber. It includes a pre-riser, internal and external delivery pipes, three riser medium distributors, and two hydrocarbon-oil distributors. This allows the gasoline to react under a more ideal atmosphere, thereby increasing the yield of the target product.
[0007] CN110317629B discloses a dual-catalyst zoned catalytic cracking method and apparatus. This method and apparatus utilize two catalysts with different properties to address the challenge of a single catalyst simultaneously achieving multiple performance requirements. The two regenerated catalysts are separated using a catalyst vortex separator, and then transported to different reaction zones. Different feedstocks are matched to each reaction zone, and different process conditions are applied based on thermodynamic properties. This achieves a high degree of matching between the catalyst, feedstock, and process conditions, enhancing the catalytic performance of each catalyst and ensuring its full utilization. It also avoids the negative impact of one catalyst on another when using catalysts in combination.
[0008] CN102690680A discloses a catalytic cracking method and apparatus for producing propylene. The method involves contacting a heavy feedstock with a first catalytic cracking catalyst, primarily composed of Y-type zeolite, in a first riser reactor. The catalyst is then stripped and regenerated for reuse. Light hydrocarbons are then contacted with a second catalytic cracking catalyst, primarily composed of shape-selective zeolite with an average pore size of less than 0.7 nm, at a temperature of 550–690°C in the second riser reactor. This second catalyst is then introduced into a fluidized bed reactor connected in series with the second riser reactor. The catalyst is stripped and regenerated for reuse. The apparatus employs a combined reactor configuration of a double riser and a fluidized bed. The stripper is divided into two independent stripping zones by a baffle plate, and a heat extraction device is also provided to cool the regenerated second catalyst.
[0009] CN104145005A discloses a process for improving the yield of ethylene and propylene from light naphtha feedstock. The process includes obtaining a light naphtha feedstock from a main cracking zone containing a cracking catalyst. The light naphtha feedstock is then contacted with an olefin catalyst in an olefin production zone to produce ethylene- and propylene-rich streams. After reaction with the olefin catalyst, the olefin catalyst is separated from the ethylene- and propylene-rich streams in a separator zone. At least a portion of the olefin catalyst is regenerated by burning coke deposited on its surface in an oxygen-containing environment, and at least a portion of the olefin catalyst is heated.
[0010] CN104419457A discloses a dual-riseer catalytic cracking method and apparatus. Two risers are used for heavy oil catalytic cracking and light hydrocarbon catalytic reforming, respectively. The contact time between the heavy oil catalytic cracking fuel and the fuel is 0.2–1.5 s. The two reaction streams are separated by their respective dedicated cyclone separators. The spent catalyst, after stripping, enters the first turbulent bed regenerator and contacts the main air flow of the first turbulent bed regenerator in a co-current manner to burn off 40%–50% of the generated coke. The first-stage semi-regenerated catalyst is lifted by the flue gas generated by the first turbulent bed regenerator into a tubular regenerator and contacts the flue gas generated by the first turbulent bed regenerator in a co-current manner to burn off 40%–50% of the generated coke. The second-stage semi-regenerated catalyst enters the second turbulent bed regenerator and contacts the main air flow of the second turbulent bed regenerator in a counter-current manner to burn off the remaining generated coke. The regenerated catalyst is returned to the two risers for recycling.
[0011] CN104342197A discloses a dual-riseer catalytic cracking method and apparatus. Two risers are used for heavy oil catalytic cracking and light hydrocarbon catalytic reforming, respectively. The contact time between the oil and catalyst in the heavy oil catalytic cracking is 0.2–1.5 s. The two reaction streams undergo gas-solid separation by their respective dedicated cyclone separators. The two reaction oil-gas streams are fractionated by their respective dedicated fractionation towers. The spent catalyst generated by the two risers is stripped and then enters a first turbulent bed regenerator, where it comes into countercurrent contact with the flue gas from a second turbulent bed regenerator to burn off more than 90% of the generated coke. The semi-regenerated catalyst enters the second turbulent bed regenerator and comes into countercurrent contact with the main air to burn off the remaining generated coke and undergo heat exchange and cooling. The cooled regenerated catalyst is returned to the two risers for recycling. During the regeneration process, only the main air is directly supplied to the second turbulent bed regenerator.
[0012] CN112469805A discloses a system and method for producing light olefins and aromatics from light naphtha. Light naphtha is fed into a first catalyst riser to crack C5 to C7 hydrocarbons in the light naphtha stream. The cracked naphtha stream is fractionated to produce a stream primarily containing C4 to C6 hydrocarbons or a stream primarily containing C5 to C12 hydrocarbons. When the stream primarily containing C4 to C6 hydrocarbons is fed into a second catalyst riser, the product stream from the second catalyst riser contains light olefins as the main product. When the stream primarily containing C5 to C12 hydrocarbons is fed into the second catalyst riser, the product stream from the second riser contains aromatics as the main product.
[0013] The above technologies share some common drawbacks, as follows:
[0014] (1) Because the active components of heavy oil catalyst and light oil catalyst are different, the heavy oil is not fully cracked in the riser, resulting in more dry gas and coke.
[0015] (2) The pyrolysis time of macromolecules and small molecules in the pyrolysis feedstock is different. Small molecules require a longer time, a larger agent-to-oil ratio, and a relatively higher temperature. Ordinary risers cannot meet these reaction conditions.
[0016] (3) The oil yield is low and the overall efficiency of the riser settling device is not high.
[0017] (4) The entire pipeline through which the catalyst passes is long and the catalyst linear velocity is high, resulting in high catalyst consumption and poor catalyst thermal stability.
[0018] (5) The riser device has a large heat consumption and a high overall energy consumption, making it difficult for the riser outlet temperature to reach a high temperature. Summary of the Invention
[0019] The purpose of this invention is to provide a dual-catalyst catalytic cracking unit that improves the yield of low-carbon olefins and gasoline / diesel. This unit can significantly improve thermal efficiency and catalyst conversion efficiency, and can be used to produce more low-carbon olefins and gasoline / diesel using heavy feedstock as direct feedstock.
[0020] The present invention also aims to provide a dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline and diesel.
[0021] To achieve the above objectives, the present invention provides a dual-catalyst catalytic cracking unit for improving the yield of low-carbon olefins and gasoline / diesel, comprising:
[0022] A riser reactor, comprising a first reaction zone, a second reaction zone, and a cyclone separator, wherein the first reaction zone is located at the bottom of the riser reactor, the second reaction zone is located above the first reaction zone and has a larger diameter than the first reaction zone, and the cyclone separator is located at the top of the riser reactor;
[0023] A fluidized bed reactor, wherein the fluidized bed reactor and the riser reactor are arranged side by side;
[0024] A settling device is located above the riser reactor and the fluidized bed reactor, with its bottom sealed to both reactors. A vertically upward-facing baffle divides the settling device into two independent parts. The outlets of both the riser reactor and the fluidized bed reactor are located inside the settling device and on either side of the baffle. A first catalyst outlet is located on the sidewall of the settling device on the riser reactor side and is connected to a first regenerator via a pipe. The bottom outlet of the first regenerator is connected to the bottom inlet of the riser reactor via a pipe. A second catalyst outlet is located on the sidewall of the settling device on the fluidized bed reactor side and is connected to a second regenerator via a pipe. The bottom outlet of the second regenerator is connected to the bottom inlet of the fluidized bed reactor via a pipe. A gas outlet is located at the top of the settling device.
[0025] The fractionation tower is connected to the gas outlet of the settling tank.
[0026] The dual-catalyst catalytic cracking device for improving the yield of low-carbon olefins and gasoline / diesel according to the present invention has a diameter ratio of the second reaction zone to the diameter of the first reaction zone of 2 to 5:1, preferably 2 to 3:1.
[0027] The dual-catalyst catalytic cracking device for improving the yield of low-carbon olefins and gasoline / diesel, as described in this invention, has a diameter ratio of the fluidized bed reactor to the diameter of the first reaction zone of 3 to 10:1, preferably 3 to 5:1.
[0028] The dual-catalyst catalytic cracking unit for improving the yield of low-carbon olefins and gasoline / diesel described in this invention has a fluidized bed reactor with a quarter-circular outlet that is horizontally oriented towards the center of the baffle. That is, the outlet of the fluidized bed reactor is elbow-shaped. When using this unit for catalytic cracking, the catalyst flow rate is relatively low, and the elbow-shaped outlet achieves a simple separation effect.
[0029] The dual-catalyst catalytic cracking unit for improving the yield of low-carbon olefins and gasoline / diesel described in this invention features a baffle plate that is linear, S-shaped, or zigzag-shaped. Different catalysts are placed on either side of the baffle plate. The riser reactor preferably contains a Y-type catalyst capable of cracking heavy oil macromolecules, while the fluidized bed reactor preferably contains a selective catalyst with good ethylene-propylene selectivity, such as ZSM-5, but is not limited to these two catalysts. The baffle plate completely prevents the mixing of the two catalysts. The baffle plate can be made of heat-resistant materials such as stainless steel or ceramic, preferably materials with good thermal conductivity.
[0030] To achieve the above objectives, the present invention also provides a dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel, using the above-mentioned apparatus, comprising the following steps:
[0031] Preheated low-quality heavy oil feedstock is fed into the first reaction zone of the riser reactor to undergo the first catalytic cracking reaction with hot catalytic cracking catalyst and water. Then it enters the second reaction zone for the second catalytic cracking reaction. After the reaction, the material is separated into oil and gas by a cyclone separator. The oil and gas enter the fractionation tower for fractionation through the gas outlet at the top of the settler. The catalyst settles in the settler by gravity and then enters the first regenerator for regeneration. The regenerated catalyst is then recycled back to the riser reactor.
[0032] The light oil fraction from the fractionation tower enters the fluidized bed reactor to react with the catalyst and water. The reacted material enters the settling tank for separation. The oil and gas enter the fractionation tower for further fractionation through the gas outlet at the top of the settling tank. The catalyst settles in the settling tank by gravity and then enters the second regenerator for regeneration. The regenerated catalyst is then recycled back to the fluidized bed reactor.
[0033] The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel described in this invention comprises the following catalytic cracking reaction conditions in the first reaction zone: a water-to-low-quality heavy oil feedstock weight ratio of 0.1–0.5:1, preferably 0.2–0.3:1; a reaction temperature of 500–580°C, preferably 540–580°C; a reaction time of 0.1–20 seconds, preferably 0.2–5 seconds; and a catalyst-to-low-quality heavy oil feedstock weight ratio of 2–30:1, preferably 6–22:1.
[0034] The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel described in this invention has the following catalytic cracking reaction conditions in the second reaction zone: the weight ratio of water to low-quality heavy oil feedstock is 0.1–0.5:1, preferably 0.2–0.3:1; the reaction temperature of the low-quality heavy oil feedstock and catalyst is 500–580°C, preferably 520–540°C; the reaction time is 0.1–20 seconds, preferably 0.2–6 seconds; and the weight ratio of catalyst to low-quality heavy oil feedstock is 2–20:1, preferably 6–15:1.
[0035] The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel described in this invention comprises the following catalytic cracking reaction conditions in a fluidized bed reactor: a water-to-light oil component weight ratio of 0.1–0.5:1, preferably 0.2–0.3:1; a reaction temperature of 500–600°C, preferably 560–580°C; a reaction time of 0.1–20 seconds, preferably 3–6 seconds; and a catalyst-to-light oil component weight ratio of 10–30:1, preferably 15–25:1.
[0036] The regeneration temperature of the catalytic cracking catalyst of the present invention is 600-800℃, preferably 680-700℃.
[0037] The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel described in this invention uses low-quality heavy oil feedstocks that are distillate oils with a boiling range of 100–550°C, such as vacuum wax oil, atmospheric residue, vacuum residue, coking wax oil, solvent deasphalted oil, crude oil, and mixtures thereof.
[0038] The beneficial effects of this invention are:
[0039] (1) The main function of the riser reactor is to crack low-quality heavy oil to produce light gasoline, C4, gasoline and diesel, etc., which requires a long reaction time. In order to reduce the height of the unit and save on modification costs, a second reaction zone with an enlarged diameter is added above the first reaction zone, which is beneficial to the yield of ethylene, propylene and low carbon olefins. The enlarged diameter of the second reaction zone compensates for the height of the riser, which is beneficial to the secondary modification of the existing riser. Due to the compact structure, it can effectively reduce the amount of fuel to be added in the regenerator and reduce energy consumption. In the device of this invention, in the riser reactor, relatively heavy raw materials are converted into larger molecules and low carbon olefins such as ethylene and propylene under high temperature, short contact time and low fuel oil ratio reaction conditions. After the reaction in the riser reactor is completed, they leave the riser immediately, which reduces the yield of dry gas and coke and avoids unfavorable secondary reactions.
[0040] (2) In the fluidized bed reactor, light gasoline and C4 cracking react under high temperature, high catalyst-to-oil ratio, and long reaction time conditions, and the catalyst matched is completely different from that of the riser reactor, which is more conducive to the formation of ethylene, propylene, and butene. The device also has the advantage of convenient catalyst replacement. In addition, the riser reactor and the fluidized bed reactor share a settling tank, which is beneficial to the utilization of heat and the increase of the reactor outlet temperature, thereby reducing the overall energy consumption of the device.
[0041] (3) Two completely different catalysts are used to meet the needs of two types of cracking that cannot be achieved with a single catalyst. The two regenerated catalysts are then transported to different reaction zones, each matched with different feedstocks, to achieve a high degree of matching between the catalyst, feedstock, and process conditions. The settling tank and heat are comprehensively utilized within the riser, allowing each catalyst in the system to maximize its performance. This avoids interference between different catalysts when they are mixed, thus improving catalyst utilization efficiency. Attached Figure Description
[0042] Figure 1 This is a schematic diagram of the dual-catalyst catalytic cracking unit for improving the yield of low-carbon olefins and gasoline / diesel as described in this invention.
[0043] In the attached figures, the following labels are used:
[0044] 1. Raw material input;
[0045] 2. Riser reactor;
[0046] 3. Settling device;
[0047] 4. Cyclone separator;
[0048] 5. Gas outlet;
[0049] Pipes 6, 7, 10, and 12;
[0050] 8. First regenerator;
[0051] 9. Light oil inlet;
[0052] 11. Second regenerator;
[0053] 13. Fluidized bed reactor outlet;
[0054] 14. Partitions;
[0055] A. First reaction zone;
[0056] B. Second reaction zone;
[0057] C. Fluidized bed reactor reaction zone. Detailed Implementation
[0058] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.
[0059] like Figure 1As shown, the dual-catalyst catalytic cracking unit for improving the yield of low-carbon olefins and gasoline / diesel according to the present invention includes a riser reactor 2, a fluidized bed reactor, a settling tank 3, and a fractionating tower (not shown in the figure). The riser reactor 2 includes a first reaction zone A, a second reaction zone B, and a cyclone separator 4. The first reaction zone A is located at the bottom of the riser reactor 2, and the feed inlet 1 is connected to the first reaction zone A. The second reaction zone B is located above the first reaction zone A and has a larger diameter than the first reaction zone A. The cyclone separator 4 is located at the top of the riser reactor 2. The fluidized bed reactor is arranged side by side with the riser reactor 2. The settling tank 3 is located above the riser reactor 2 and the fluidized bed reactor, and its bottom is sealed to the riser reactor 2 and the fluidized bed reactor. The settling tank 3 is vertically mounted on its bottom plate. A partition 14 divides the settling tank 3 into two independent parts. The outlets of the riser reactor 2, namely the cyclone separator 4 and the fluidized bed reactor outlet 13, are both inside the settling tank 3 and located on both sides of the partition 14. A first catalyst outlet is provided on the side wall of the settling tank 3 on the side of the riser reactor 2 and is connected to the first regenerator 8 through a pipe 6. The bottom outlet of the first regenerator 8 is connected to the bottom inlet (raw material inlet 1) of the riser reactor 2 through a pipe 7. A second catalyst outlet is provided on the side wall of the settling tank 3 on the side of the fluidized bed reactor and is connected to the second regenerator 11 through a pipe 12. The bottom outlet of the second regenerator 11 is connected to the bottom inlet (light oil inlet 9) of the fluidized bed reactor through a pipe 10. A gas outlet 5 is provided at the top of the settling tank 3. The gas outlet 5 is connected to the fractionation tower.
[0060] Preheated low-quality heavy oil feedstock is fed into the first reaction zone A of riser reactor 2 to undergo the first catalytic cracking reaction with the hot catalytic cracking catalyst. Then it enters the second reaction zone B for the second catalytic cracking reaction. After the reaction, the material is separated into oil and gas by cyclone separator 4. The oil and gas enter the fractionation tower for fractionation through the gas outlet 5 at the top of settling tank 3. The catalyst settles in settling tank 3 by gravity and then enters the first regenerator 8 for regeneration. The regenerated catalyst is recycled to riser reactor 2.
[0061] The light gasoline and C4 distilled from the fractionation tower enter the fluidized bed reaction zone C of the fluidized bed reactor through the light oil inlet 9 for reaction. The reacted material enters the settling tank 3 for separation. The oil and gas enter the fractionation tower for fractionation through the gas outlet 5 at the top of the settling tank 3. The catalyst settles in the settling tank 3 by gravity and then enters the second regenerator 11 for regeneration. The regenerated catalyst is recycled to the fluidized bed reactor.
[0062] Example 1
[0063] use Figure 1The dual-catalyst catalytic cracking unit shown has a diameter ratio of 2 between the second and first reaction zones, and a diameter ratio of 3 between the fluidized bed reactor and the first reaction zone. The baffles are of a straight line shape. Experimental conditions: The feedstock is the Lanzhou Petrochemical 300W heavy oil catalytic cracking feedstock listed in Table 1. The riser uses the conventional heavy oil catalyst LDO75-YN. The fluidized bed reactor uses the low-carbon olefin-specific catalyst PCA-OD, with a catalyst-to-oil ratio of 10. In the first reaction zone of the riser reactor, the reaction temperature is 520℃, the water-to-feedstock weight ratio is 0.25:1, the reaction time is 5s, and the catalyst-to-feedstock weight ratio is 7.5. In the second reaction zone of the riser reactor, the reaction temperature is 520℃, the water-to-feedstock weight ratio is 0.3:1, the reaction time is 5s, and the catalyst-to-feedstock weight ratio is 12. In the fluidized bed reactor, the reaction temperature is 530℃, the water-to-light gasoline / C4 weight ratio is 0.3:1, and the reaction time is 5s. During the heating process of the riser reactor, the fluidizing gas is nitrogen. After the reactor reaches the set temperature, the fluidizing gas is high-temperature water vapor, the fluidization auxiliary gas is nitrogen, and the regeneration is air regeneration.
[0064] Table 1 Properties of feedstock for Lanzhou Petrochemical's 300W heavy catalytic cracking unit
[0065]
[0066] Comparative Example 1
[0067] Compared to Example 1, Comparative Example 1 reduced the amount of light gasoline and C4 recycled by 50%, while other operating parameters remained the same. The resulting product distribution is shown in Table 2. Table 2 shows that Example 1 had a liquefied petroleum gas yield of 30.20%, a coke yield of 3.24%, and an ethylene + propylene + butene yield of 27.37%. This indicates that the reactor can effectively perform catalytic cracking reaction performance evaluation tests at this temperature.
[0068] Table 2 Product distribution of Comparative Example 1 and Example 1
[0069] Product distribution (m%) Comparative Example 1 Example 1 dry air 4.99 3.65 Liquefied gas 27.78 30.20 C5 gasoline 41.49 47.00 diesel fuel 17.79 14.05 heavy oil 2.99 1.87 coke 4.96 3.24 Product Selectivity Conversion rate 79.22 84.08 Light oil yield 59.28 61.05 Total liquid yield 87.06 91.25 Gas composition (m%) H2 0.06 0.05 H2S 0.17 0.16 CH4 1.18 0.76 C2H4 2.75 2.09 C2H6 0.83 0.59 C3H8 1.43 1.30 C3H6 13.16 13.89 iC4H10 3.27 2.98 nC4H10 0.59 0.64 iC4H8+nC4H8 5.95 7.12 t-C4H8 1.95 2.51 c-C4H8 1.43 1.77 ≥C5 4.75 5.14
[0070] The yields of ethylene, propylene, butene, and triolefins are shown in Table 3.
[0071] Table 3 Triene Yields of Comparative Example 1 and Example 1
[0072] Product distribution (m%) Comparative Example 1 Example 1 ethylene 2.75 2.09 propylene 13.16 13.89 Butene 9.33 11.40 Trienes 25.23 27.37 propylene + butene selectivity, % 80.94 83.72
[0073] Example 2
[0074] use Figure 1The dual-catalyst catalytic cracking unit shown has a diameter ratio of 4 between the second reaction zone and the first reaction zone, and a diameter ratio of 8 between the fluidized bed reactor and the first reaction zone. The baffles are in a straight line. Experimental conditions: The feedstock was Lanzhou Petrochemical 300W heavy catalytic cracking feedstock (same as in Example 1). The riser used conventional heavy oil catalyst LDO75-YN. The fluidized bed reactor used PCA-OD catalyst for low-carbon olefins, with a catalyst-to-oil ratio of 27. In the first reaction zone of the riser reactor, the reaction temperature was 550℃, the water-to-feedstock weight ratio was 0.5:1, the reaction time was 2s, and the catalyst-to-feedstock weight ratio was 18. In the second reaction zone of the riser reactor, the reaction temperature was 550℃, the water-to-feedstock weight ratio was 0.1:1, the reaction time was 2s, and the catalyst-to-light oil component weight ratio was 5. In the fluidized bed reactor, the reaction temperature was 560℃, the water-to-light gasoline / C4 weight ratio was 0.5:1, and the reaction time was 4s. During the heating process of the riser reactor, the fluidizing gas is nitrogen. After the reactor reaches the set temperature, the fluidizing gas is high-temperature water vapor, the fluidization auxiliary gas is nitrogen, and the regeneration is air regeneration.
[0075] Comparative Example 2
[0076] Compared to Example 2, Comparative Example 2 reduced the amount of light gasoline and C4 recycled by 80%, while other operating parameters remained the same. The resulting product distribution is shown in Table 4. Table 4 shows that the LPG yield was 27.97%, the coke yield was 6.03%, and the ethylene + propylene + butene yield was 23.01%. This indicates that the reactor can effectively perform catalytic cracking reaction performance evaluation tests at this temperature, with significant results.
[0077] Table 4 Product distribution of Comparative Example 2 and Example 2
[0078] Product distribution (m%) Comparative Example 2 Example 2 dry air 5.15 3.90 Liquefied gas 25.78 27.97 C5 gasoline 47.25 45.18 diesel fuel 13.95 14.58 heavy oil 2.28 2.35 coke 5.59 6.03 Product Selectivity Conversion rate 83.77 83.07 Light oil yield 61.20 59.76 Total liquid yield 86.97 87.72 Gas composition (m%) H2 0.08 0.06 H2S 0.08 0.21 CH4 1.84 1.11 C2H4 2.02 1.78 C2H6 1.13 0.73 C3H8 2.02 1.47 C3H6 9.68 10.87 iC4H10 4.15 4.37 nC4H10 1.13 0.90 iC4H8+nC4H8 5.22 5.63 t-C4H8 1.93 2.74 c-C4H8 1.66 1.99 ≥C5 4.96 6.44
[0079] The yields of ethylene, propylene, butene, and triolefins are shown in Table 5.
[0080] Table 5. Triene yields of Comparative Example 2 and Example 2
[0081] Product distribution (m%) Comparative Example 2 Example 2 ethylene 2.02 1.78 propylene 9.68 10.87 Butene 8.80 10.35 Trienes 20.51 23.01 propylene + butene selectivity, % 71.70 75.88
[0082] Example 3
[0083] use Figure 1The dual-catalyst catalytic cracking unit shown has a diameter ratio of 2.5 between the second reaction zone and the first reaction zone, and a diameter ratio of 3.5 between the fluidized bed reactor and the first reaction zone. The baffles are of a straight line type. Experimental conditions: The feedstock is Lanzhou Petrochemical 550Y crude oil, with properties shown in Table 6. The riser uses conventional heavy oil catalyst LDO75-YN. The fluidized bed uses PCA-OD catalyst specifically for low-carbon olefins, with a catalyst-to-oil ratio of 19. In the first reaction zone of the riser reactor, the reaction temperature is 580℃, the water-to-feedstock weight ratio is 0.1:1, the reaction time is 20s, and the catalyst-to-feedstock weight ratio is 25. In the second reaction zone of the riser reactor, the reaction temperature is 580℃, the water-to-feedstock weight ratio is 0.5:1, the reaction time is 20s, and the catalyst-to-light oil component weight ratio is 18. In the fluidized bed reactor, the reaction temperature is 580℃, the water-to-light gasoline / C4 weight ratio is 0.1:1, and the reaction time is 18s. During the heating process of the riser reactor, the fluidizing gas is nitrogen. After the reactor reaches the set temperature, the fluidizing gas is high-temperature water vapor, the fluidization auxiliary gas is nitrogen, and the regeneration is air regeneration.
[0084] Table 6 Properties of Lanzhou Petrochemical 550Y Crude Oil
[0085]
[0086] Comparative Example 3
[0087] Compared to Example 3, the diameter of the fluidized bed reactor in Comparative Example 3 was 1.5 times the diameter of the first reaction zone, and other operating parameters were the same as in Example 3.
[0088] The product distributions obtained in Example 3 and Comparative Example 3 are listed in Table 7. As can be seen from Table 7, the liquefied petroleum gas yield in Example 3 was 29.98%, the coke yield was 5.20%, and the yield of ethylene + propylene + butene was 27.47%. This indicates that the reactor can effectively perform catalytic cracking reaction performance evaluation tests at this temperature.
[0089] Table 7 Product distribution of Comparative Example 3 and Example 3
[0090] Product distribution (m%) Comparative Example 3 Example 3 dry air 5.07 4.23 Liquefied gas 28.41 29.98 C5 gasoline 40.68 39.47 diesel fuel 17.78 17.98 heavy oil 2.98 3.14 coke 5.08 5.20 Product Selectivity Conversion rate 79.23 78.88 Light oil yield 58.46 57.44 Total liquid yield 86.87 87.43 Gas composition (m%) H2 0.07 0.06 H2S 0.15 0.18 CH4 1.20 0.94 C2H4 2.82 2.38 C2H6 0.83 0.67 C3H8 1.62 1.26 C3H6 13.54 13.42 iC4H10 3.32 2.95 nC4H10 0.65 0.68 iC4H8+nC4H8 5.77 6.95 t-C4H8 2.04 2.66 c-C4H8 1.47 2.07 ≥C5 5.08 5.89
[0091] The yields of ethylene, propylene, butene, and triolefins are shown in Table 8.
[0092] Table 8. Triene yields of Comparative Example 3 and Example 3
[0093] Product distribution (m%) Comparative Example 3 Example 3 ethylene 2.82 2.38 propylene 13.54 13.42 Butene 9.28 11.67 Trienes 25.64 27.47 propylene + butene selectivity, % 80.33 83.68
[0094] As can be seen from Examples 1 to 3, this process achieves good yields of low-carbon olefins and gasoline / diesel, and a relatively low yield of dry gas / coke. The two catalysts each leverage their respective advantages, resulting in a high yield of low-carbon olefins. The shared use of the settler reduces the overall energy consumption of the unit. The settler and heat are comprehensively utilized within the riser, maximizing the performance of each catalyst in the entire system. This avoids interference between different catalysts when using them in combination.
[0095] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.
Claims
1. A dual-catalyst catalytic cracking unit for improving the yield of low-carbon olefins and gasoline / diesel, characterized in that, include: A riser reactor, comprising a first reaction zone, a second reaction zone, and a cyclone separator, wherein the first reaction zone is located at the bottom of the riser reactor, the second reaction zone is located above the first reaction zone and has a larger diameter than the first reaction zone, and the cyclone separator is located at the top of the riser reactor; A fluidized bed reactor, wherein the fluidized bed reactor and the riser reactor are arranged side by side; A settling device is located above the riser reactor and the fluidized bed reactor, with its bottom sealed to both reactors. A vertically upward-facing baffle divides the settling device into two independent parts. The outlets of the riser reactor and the fluidized bed reactor are both inside the settling device and located on either side of the baffle. A first catalyst outlet is located on the sidewall of the settling device on the riser reactor side and is connected to a first regenerator via a pipe. The bottom outlet of the first regenerator is connected to the bottom inlet of the riser reactor via a pipe. A second catalyst outlet is located on the sidewall of the settling device on the fluidized bed reactor side and is connected to a second regenerator via a pipe. The bottom outlet of the second regenerator is connected to the bottom inlet of the fluidized bed reactor via a pipe. A gas outlet is located at the top of the settling device. A fractionation tower is connected to the gas outlet of the settler; The diameter ratio of the second reaction zone to the diameter of the first reaction zone is 2~5:1; The diameter ratio of the fluidized bed reactor to the diameter of the first reaction zone is 3~10:
1.
2. The dual-catalyst catalytic cracking unit for improving the yield of low-carbon olefins and gasoline / diesel according to claim 1, characterized in that, The diameter ratio of the second reaction zone to the diameter of the first reaction zone is 2~3:
1.
3. The dual-catalyst catalytic cracking unit for improving the yield of low-carbon olefins and gasoline / diesel according to claim 1, characterized in that, The diameter ratio of the fluidized bed reactor to the diameter of the first reaction zone is 3~5:
1.
4. The dual-catalyst catalytic cracking unit for improving the yield of low-carbon olefins and gasoline / diesel according to claim 1, characterized in that, The outlet of the fluidized bed reactor is a quarter circle and the outlet direction is horizontal towards the center of the baffle.
5. The dual-catalyst catalytic cracking unit for improving the yield of low-carbon olefins and gasoline / diesel according to claim 1, characterized in that, The partition can be straight, S-shaped, or zigzag-shaped.
6. A dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel, characterized in that, Using the apparatus according to any one of claims 1-5 includes the following steps: Preheated low-quality heavy oil feedstock is fed into the first reaction zone of the riser reactor to undergo the first catalytic cracking reaction with hot catalytic cracking catalyst and water. Then it enters the second reaction zone for the second catalytic cracking reaction. After the reaction, the material is separated into oil and gas by a cyclone separator. The oil and gas enter the fractionation tower for fractionation through the gas outlet at the top of the settler. The catalyst settles in the settler by gravity and then enters the first regenerator for regeneration. The regenerated catalyst is then recycled back to the riser reactor. The light oil fraction from the fractionation tower enters the fluidized bed reactor to react with the catalyst and water. The reacted material enters the settling tank for separation. The oil and gas enter the fractionation tower for further fractionation through the gas outlet at the top of the settling tank. The catalyst settles in the settling tank by gravity and then enters the second regenerator for regeneration. The regenerated catalyst is then recycled back to the fluidized bed reactor.
7. The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel according to claim 6, characterized in that, The catalytic cracking reaction conditions in the first reaction zone are as follows: the weight ratio of water to low-quality heavy oil feedstock is 0.1 to 0.5:1; the reaction temperature of low-quality heavy oil feedstock and catalyst is 500 to 580°C; the reaction time is 0.1 to 20 seconds; and the weight ratio of catalyst to low-quality heavy oil feedstock is 2 to 30:
1.
8. The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel according to claim 6, characterized in that, The catalytic cracking reaction conditions in the first reaction zone are as follows: the weight ratio of water to low-quality heavy oil feedstock is 0.2 to 0.3:1; the reaction temperature of low-quality heavy oil feedstock and catalyst is 540 to 580°C; the reaction time is 0.2 to 5 seconds; and the weight ratio of catalyst to low-quality heavy oil feedstock is 6 to 22:
1.
9. The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel according to claim 6, characterized in that, The catalytic cracking reaction conditions in the second reaction zone are as follows: the weight ratio of water to low-quality heavy oil feedstock is 0.1 to 0.5:1; the reaction temperature of low-quality heavy oil feedstock and catalyst is 500 to 580°C; the reaction time is 0.1 to 20 seconds; and the weight ratio of catalyst to low-quality heavy oil feedstock is 2 to 20:
1.
10. The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel according to claim 6, characterized in that, The catalytic cracking reaction conditions in the second reaction zone are as follows: the weight ratio of water to low-quality heavy oil feedstock is 0.2 to 0.3:1; the reaction temperature of low-quality heavy oil feedstock and catalyst is 520 to 540°C; the reaction time is 0.2 to 6 seconds; and the weight ratio of catalyst to low-quality heavy oil feedstock is 6 to 15:
1.
11. The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel according to claim 6, characterized in that, The catalytic cracking reaction conditions in the fluidized bed reactor are as follows: the weight ratio of water to light oil component is 0.1 to 0.5:1; the reaction temperature of light oil component and catalyst is 500 to 600℃, and the reaction time is 0.1 to 20 seconds; the weight ratio of catalyst to light oil component is 10 to 30:
1.
12. The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel according to claim 6, characterized in that, The catalytic cracking reaction conditions in the fluidized bed reactor are as follows: the weight ratio of water to light oil component is 0.2 to 0.3:1; the reaction temperature of light oil component and catalyst is 560 to 580℃, and the reaction time is 3 to 6 seconds; the weight ratio of catalyst to light oil component is 15 to 25:
1.
13. The dual-catalyst catalytic cracking method for improving the yield of low-carbon olefins and gasoline / diesel according to claim 6, characterized in that, Inferior heavy oil feedstock consists of distillate oil with a boiling range of 50–550℃.