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FDFCC-Ⅲ process technology FDFCC-Ⅲ process technology is a further development of the FDFCC-Ⅰ process. Its production goals are to improve product distribution, further increase propylene yield, and reduce the sulfur content and olefin content of gasoline. The core of this process technology is to optimize the operation of the heavy oil riser reactor, using low oil agent instantaneous contact temperature, high reaction temperature, large agent oil ratio, and short reaction time operation to further increase the propylene yield and reduce the sulfur content and olefin content of gasoline. This technology achieves the above goals by utilizing the relatively low temperature and high residual activity of the regeneration agent in the gasoline riser settler, returning it to the bottom of the heavy oil riser to mix with the regeneration agent, increasing the agent-oil ratio of the heavy oil riser, and reducing the instantaneous contact temperature of the oil agent to reduce dry gas and coke yields, increase total liquid recovery, and improve product distribution. At present, the regeneration temperature of the catalyst in the catalytic cracking unit is generally higher than 650°C. Due to the high temperature of the regenerated catalyst, the catalyst oil ratio is small due to the limitation of the heat balance of the unit. The size of the agent-oil ratio is directly related to the number of active centers per unit weight of the raw material contacting the catalytic cracking reaction, which has a great impact on the product distribution and product properties of the catalytic cracking. When the ratio of agent to oil is large, the selectivity of the product is good; otherwise, the selectivity of the product becomes poor. Generally, the method of increasing the catalyst-to-oil ratio can be by lowering the temperature of the regenerated catalyst or lowering the temperature of the catalytic cracking feed oil. However, the viscosity of heavy oil is greatly affected by temperature. When the temperature is higher, the viscosity is smaller, and vice versa. Therefore, in order to ensure a certain atomization effect, the atomization preheating temperature of the raw material for catalytic cracking of heavy oil should not be too low. Therefore, although the method of lowering the preheating temperature of catalytic cracking feed oil is simple and easy to implement, its impact on increasing the agent-oil ratio is limited. Lowering the temperature of the regenerated catalyst is also an effective way to increase the catalyst-to-oil ratio. Increase the moment when the regenerant and the raw oil start to contact. Due to uneven heat transfer, local overheating will inevitably occur, causing the temperature of some raw oil molecules to exceed 600°C. Excessively high temperature will increase the degree of thermal cracking reaction, increase the yield of dry gas and coke, and decrease the yield of light oil. Therefore, using the method of reducing the temperature of the regenerated catalyst to increase the agent-oil ratio is of heavy oil significance for improving the product distribution and product quality of the catalytic cracking reaction. The FDFCC-Ⅲ process technology takes advantage of the technical advantages of the FDFCC double riser process to achieve the purpose of optimizing the operation of the heavy oil riser reactor. Compared with conventional FCC, this process technology not only has the advantages of FDFCC process technology, but also can achieve the same conversion rate, reduce the dry gas and coke yield of the device by more than 1 percentage point, greatly improve product distribution, and reduce the energy consumption of the device. Technical characteristics of the reaction part 1) Adopt double riser and double settler design. 2) A specially designed pre-lift section of the heavy oil riser is used to mix the regenerated catalyst with the gasoline to-be-generated catalyst to reduce the temperature of the regenerant and increase the agent-to-oil ratio. 3) The raw oil nozzle of the heavy oil riser is a CS-type nozzle with a special design, good atomization effect, and has been proven to be effective through practical applications. It uses an appropriate raw material preheating temperature to reduce the viscosity of the raw material feed nozzle as much as possible to ensure the atomization effect of the raw material and the oil contact effect. 4) The two risers are designed with optimized reaction times to create good conditions for reducing gasoline olefins and increasing propylene production. 5) There are quenching oil facilities at the back of the two riser tubes (not used under normal circumstances, but used under special circumstances) to control the reaction outlet temperature. 6) The reaction is quickly terminated at the outlet of the two riser tubes. The outlet of the riser tube is equipped with a coarse cyclone and a fast separation system to quickly separate the oil and gas from the catalyst. The coarse cyclone lift tube is softly connected to the inlet of the single-stage cyclone of the settler to quickly terminate the secondary reaction and reduce the residence time of the reacted oil and gas in the settler to reduce the occurrence of secondary reactions and thermal cracking reactions. At the same time, it improves the separation efficiency and reduces the loss of the catalyst. 7) The stripping section adopts high-efficiency stripping technology ； Among them, the heavy oil stripping section utilizes old materials, and the gasoline stripping section adopts packing-type high-efficiency stripping technology. The technological features of the fractionation part adopt a double fractionation tower design. The oil and vapor in the heavy oil riser enter the main fractionation tower, and the oil and vapor in the gasoline riser enter the auxiliary fractionation tower. The cooling systems at the top of the fractionation tower are independent. The crude gasoline that enters the gasoline riser only comes from the main fractionation tower and undergoes single-pass conversion, which has a good olefin reduction effect. The amount of gasoline required to be recycled to achieve the same olefin content is small and the energy consumption is low. This device consists of reaction-regeneration part, main air unit part, fractionation part, air compressor part, and absorption stabilization part. Except for the heavy oil prompt pipe shift and update, the addition of the gasoline riser reaction part and the auxiliary fractionator part, the original process remains unchanged. Only the modified part of the process flow is described below. Reaction part: In the reaction part of the heavy oil riser, the vacuum residual oil, vacuum wax oil and coking wax oil from outside the device are mixed and enter the raw oil buffer tank. After being boosted by the raw oil pump, the oil slurry - the raw oil is heated to about 175°C and divided into 4 paths through the raw oil nozzle and enter the lower part of the riser reactor (R-101A). The recycled oil from the fractionation part enters the riser. In the middle part, it comes into contact with the high-temperature catalyst that has been sorted into plug flow through the pre-lifting section to complete the temperature rise and vaporization reaction of the raw materials. The reaction oil and gas and the to-be-produced catalyst are rapidly separated by coarse rotation at the outlet of the riser, and then enter the settler for single-stage cyclone separation through the riser. After further removing the carried catalyst fines, the reaction oil and gas leave the settler and enter the fractionation tower. The regenerated catalyst from the regeneration inclined tube of the heavy oil riser and the gasoline regeneration catalyst from the gasoline regeneration circulation inclined tube are organized into plug flow through the specially designed pre-lift section. The crude gasoline from the crude gasoline outlet of the reaction part of the gasoline riser enters the gasoline riser (R201A) in four ways. The reaction oil and gas of R201A are quickly separated at the outlet of the riser through a rough cyclone. The oil and gas further remove the carried catalyst fine powder through a single cyclone, and finally leave the gasoline settler and enter the auxiliary fractionation tower. The catalyst from the R201A rough spin and the single-stage cyclone recovery of the gasoline settler enters the gasoline stripping section, where it contacts the steam in countercurrent to strip the oil and gas carried by the catalyst. After stripping, a part of the catalyst enters the upper part of the dense-phase bed of the regenerator (R-101C) through the gasoline to-be-generated inclined tube and the gasoline to-be-generated slide valve, where it is fully regenerated in countercurrent flow. ； The other part of the catalyst enters the pre-lift section at the bottom of the heavy oil riser reactor (R-101A) from the gasoline regeneration circulation inclined pipe through the gasoline regeneration circulation slide valve, and is mixed with the regenerated catalyst. The regenerated catalyst enters the bottom of the riser reactor (R-101A) and gasoline riser reactor (R201A) through their respective regeneration risers and regeneration single-action slide valves. Under the pre-lifting action of steam or dry gas, the catalyst is accelerated and dispersed, and then comes into contact with the atomized raw materials. The reaction oil and gas from the gasoline riser reactor through the gasoline settler enters the bottom of the auxiliary fractionation tower, contacts the oil slurry from the main fractionation tower through the herringbone baffle in countercurrent, washes the catalyst in the reaction fish group and removes superheat, and then enters the upper part of the auxiliary fractionation tower for fractionation. The oil and gas at the top of the sub-fractionating tower exchange heat through the oil-gas-hot water heat exchanger (E2201/1-4) at the top of the sub-fractionating tower, and then are cooled to 40°C by the oil-gas cooler (E2202/1-4) at the top of the sub-fractionating tower, and then enter the oil-gas separator (V-2) at the top of the sub-fractionating tower. 201), the separated crude gasoline is divided into two paths after being passed through the auxiliary crude gasoline pump (P2201AB), one path is returned to the top of the auxiliary fractionation tower as cold reflux, and the other path enters the absorption tower. If the 2# catalytic crude gasoline is recycled, there is one path that returns to the 2# catalytic gas. Acid water is self-pressurized to the inlet of the acid water pump ； The rich gas passes through the butterfly valve and is mixed with the rich gas at the top of the main fractionating tower before entering the air compressor. The excess heat in the sub-fractionating tower is taken away from the middle section of the sub-fractionating tower. The sub-middle section circulation pump draws out the heat from the sub-fractionating tower. It is boosted by the sub-fractionating tower middle section pump (P206/1-2) and then divided into two paths. One path passes through the reboiler (E3) at the bottom of the light and heavy gasoline separation tower. 17) The temperature of the reboiler at the bottom of the desorption tower (E-304/2) and the circulating oil-hot water heat exchanger (E2203) in the middle section of the secondary fractionation tower returns to the secondary fractionation tower after the temperature drops to 145°C. The other path is sent to the entrance of the fractionation tower as light diesel oil. The oil slurry at the bottom of the auxiliary fractionating tower is self-pressurized to the fractionating tower. The effect and product distribution of FDFCC-3 has been improved. The FDFCC-Ⅲ process has significantly improved the product structure of the device. The liquefied gas production rate has increased by more than 6 percentage points compared with the FDFCC-Ⅰ process. The propylene mass yield has reached more than 10%, while the dry gas and coke production rates have dropped by more than 0.5 percentage points. The value-added effect is obvious. Product quality is improved. The FDFCC-Ⅲ process has a very significant effect on the modification of catalytic gasoline.: The effect of reducing olefins is significant. The olefin content calibration and statistical results of FDFCC-Ⅲ process refined gasoline can reach below 18v%, reaching Euro III standards. The sulfur reduction effect is obvious. Statistical results show that the sulfur reduction effect of gasoline is more than 45%, and the calibration results show that the sulfur reduction rate is more than 40%. The octane number and induction period of gasoline are greatly improved. The MON and RON of calibrated refined gasoline reach above 84 and above 94 respectively, and the octane number increases by more than two units. The induction period of calibrated refined gasoline exceeds 990 minutes. The benzene content of gasoline is within the quality index range. The quality of FDFCC-Ⅲ process diesel is equivalent to FDFCC-Ⅰ. The energy saving and consumption reduction effect is remarkable. Although the energy consumption of a single FDFCC-III unit is high, for the branch, due to its obvious sulfur reduction effect, the sulfur content of refined gasoline has met the requirements of gasoline quality indicators. Therefore, after the start of the unit transformation, two sets of catalytic unit light and heavy gasoline separation systems and a 300,000 tons/year catalytic heavy gasoline hydrogenation unit were stopped. Both of them can reduce the energy consumption of the entire plant by more than two units. Converted to the energy consumption of the catalytic unit, the energy consumption can be reduced by more than 8 units, and the energy saving effect is significant. The effect of cost reduction and fee reduction is obvious. Due to the improvement of gasoline quality, the catalytic heavy gasoline hydrogenation device was stopped, which saved the cost of hydrogen and reduced the loss of octane number caused by hydrogenation. At the same time, its own octane number is high, so it can * * Reduce gasoline blending costs. The environmental protection effect is good. From the analysis of regeneration flue gas, the SOX content in the flue gas has dropped significantly compared with FCC. Both calibration and conventional analysis are below 500 mg/m3, which better solves the problem of high SOX content in the flue gas of FCC equipment processing sulfur-containing raw materials. Considering long-term development, for an economy and society with increasingly strict environmental protection requirements, the SOX content of flue gas will drop significantly, and the cost of flue gas desulfurization will drop significantly. 6. Mature technology and reliable operation. From the perspective of production operations, since the FDFCC-Ⅲ process was put into operation, the operation is stable, the adjustment is free, and the operation flexibility is large. It is a very mature and reliable advanced process technology. It has broad promotion value. To sum up, the FDFCC-III process jointly developed by Sinopec Luoyang Engineering Company and Changling Branch has achieved major technological breakthroughs and solved the three major problems of traditional FCC, namely, high dry gas and coke yields in heavy oil risers, high gasoline olefin and sulfur content, and excessive SOX content in flue gas. The transformation has achieved the expected results. Industrial application of FDFCC-III technology in Changling Branch In order to reduce the olefin content of catalytic gasoline and increase propylene production, the No. 1 catalytic cracking unit of Sinopec Changling Branch underwent FDFCC-I process technology transformation in May 2003. This process uses double riser technology, that is, a gasoline riser is added to the original FCC process to upgrade catalytic gasoline. The heavy oil riser and gasoline riser share the settler and fractionation tower. Taking into account the upgrading efficiency, the crude gasoline from the No. 2 catalytic cracking unit is used as the feed to the riser. After the transformation, the average volume content of gasoline olefins in the two sets of catalytic cracking units dropped to about 35%, the liquid hydrocarbon yield increased by 2 to 3 percentage points, and the propylene yield reached more than 6.5m%, but the dry gas and coke yields of the units were relatively high. In order to further improve the product structure of the device, meet the demand for high-yield liquefied gas, especially propylene, and improve the quality of gasoline products, the FDFCC-III process modification was carried out on the device in March 2006. In order to examine the effect of the FDFCC-III process technology on increasing propylene production, reducing the olefin content and sulfur content of catalytic gasoline, and the changes in energy consumption after the device modification, the device was calibrated twice after the device started normal operation and ran smoothly for one month. The results are as follows: (1) Product distribution is improved. The FDFCC-III process has significantly improved the product structure of the device. The liquefied gas yield has increased by more than 6 percentage points compared with the FDFCC-I process. The propylene mass yield has reached more than 10%, while the dry gas and coke yields have dropped by more than 0.5 percentage points. The value-added effect is obvious. (2) Product quality has been improved. The FDFCC-III process has a very significant effect on the modification of catalytic gasoline.: ①The effect of reducing olefins is significant. The olefin volume content calibration and statistical results of FDFCC-III refined gasoline can reach more than 18%, reaching Euro III standards. ②The sulfur reduction effect is obvious. Statistical results show that the sulfur reduction effect reaches more than 45%, and the calibration results show that the sulfur reduction rate is more than 40%. ③The octane number and induction period of gasoline have been greatly improved. The MON and RON of calibrated refined gasoline have reached above 84 and 94 respectively, and the octane number has increased by more than 2 units. The induction period of calibrated refined gasoline exceeds 990 minutes. ④The benzene content of gasoline is within the quality index range. (3) Significant energy saving and consumption reduction effect. Although the energy consumption of the FDFCC-III single unit is slightly higher, for the whole branch, due to its obvious sulfur reduction effect, the sulfur content of refined gasoline has met the requirements of gasoline quality indicators. Therefore, after the start of the unit transformation, two sets of catalytic unit light and heavy gasoline separation systems and a 300kt/a catalytic heavy gasoline hydrogenation unit were stopped. Both of these can reduce the energy consumption of the entire plant by 2 More than one unit, converted into the energy consumption of the catalytic cracking unit, can reduce energy consumption by more than 8 units, and the energy saving effect is significant. (4) The effect of cost reduction and fee reduction is obvious. Due to the improvement of gasoline quality, the catalytic heavy gasoline hydrogenation device has been stopped, which saves hydrogen costs and reduces the loss of octane number caused by hydrogenation. At the same time, its own octane number is high, so it can * * Reduce gasoline blending costs. (5) Good environmental protection effect. Judging from the analysis results of regenerated flue gas, the SO2 content in the flue gas has dropped significantly compared with FCC. Both calibration and conventional analysis are below 500mg/m3, which has better solved the problem of high SOx content in the flue gas of FCC equipment processing sulfur-containing raw materials. (6) The process is mature and the operation is reliable. Since the FDFCC-III process was put into operation, the operation is stable, the adjustment is free, and the operation is flexible.