JPH0512399B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a fluid catalytic cracking method for heavy hydrocarbon oils, and more specifically, the present invention relates to a fluid catalytic cracking method for heavy hydrocarbon oil, and more specifically, a reusable catalyst is separated from the catalyst discharged from a catalytic cracking unit based on the difference in specific gravity. This relates to a fluid catalytic cracking method in which the catalytic cracking process involves sorting the catalytic crackers and recycling them to a catalytic cracking device. [Prior Art] In the fluid catalytic cracking method of hydrocarbons, a catalytic cracking apparatus basically consisting of a reaction tower and a regeneration tower is generally used. In this device, the catalyst loses its activity due to carbon precipitated on its surface when it comes into contact with hydrocarbon oil in the reaction tower, but the catalyst with carbon deposited loses its activity due to carbon burning in the regeneration tower. Since it regains its activity, the cycle of supplying it to the reaction tower is repeated. However, although the catalyst is regenerated by carbon burning, it gradually loses its activity and selectivity over time, so it is necessary to remove a portion of the catalyst from the equipment and replenish it with a corresponding amount of new catalyst. Strategies are usually employed to maintain the overall activity of the catalyst within the apparatus at a desired constant level by periodic operation. In this case, the new catalyst replenished into the equipment circulates through the equipment harmoniously with the existing catalyst in the equipment, and only deactivated catalysts are sorted out from the equipment. Therefore, the catalyst taken out from the device usually contains fresh catalyst that was replenished earlier or catalyst that is still active. Therefore, the catalyst extracted from the device is
It can be said that it would be a shame to dispose of it as before. Particularly, when the raw material hydrocarbon oil to be subjected to catalytic cracking is heavy, the amount and frequency of catalyst removal increases, which further increases the uneconomical nature of discarding the extracted catalyst. In order to improve this uneconomical situation,
Japanese Patent No. 157486 proposes separating the catalyst extracted from the catalytic cracking device into magnetized and non-magnetized materials, and returning the non-magnetized material to the catalytic cracking device.
This proposal focuses on the fact that one cause of catalyst deactivation other than carbon deposition is the deposition of metals on the catalyst, and the catalyst with more deposited metals has poorer activity.
Taking advantage of the fact that catalysts with more deposited metal are more likely to stick to magnets, the extracted catalysts are divided into magnetized and non-magnetized catalysts, and non-magnetized catalysts with less deposited metal are likely to remain active. It is intended for reuse. [Problems to be Solved by the Invention] The present invention solves the uneconomical nature of directly disposing of the catalyst extracted from the catalytic cracker by means different from the invention of JP-A-56-157486. This is something that we are trying to improve. [Means for Solving the Problems] The present invention is characterized in that the catalyst extracted from the catalytic cracking device is divided into heavy catalyst and light catalyst based on the difference in specific gravity, and the light catalyst is returned to the catalytic cracking device. shall be. [Operation] During the operation of the catalytic cracking device, metal is deposited on the catalyst extracted from the device, but the amount of metal is not necessarily uniform for each catalyst particle. In general, catalyst particles used in a catalytic cracking apparatus usually have substantially uniform specific gravity in the absence of carbon precipitation or metal deposition. Therefore, the above-mentioned difference in the amount of deposited metal between particles appears as a difference in specific gravity between individual catalyst particles, and naturally the catalyst with a larger amount of deposited metal has a larger specific gravity.
Generally, the activity of the catalyst is poorer as the amount of deposited metal increases. Therefore, by classifying the catalyst extracted from the device into heavy catalysts and light catalysts based on the difference in specific gravity, catalysts with less deposited metal, in other words, catalysts that still maintain their activity, can be selected as light catalysts. It is possible. When selecting catalysts using the difference in specific gravity,
Known means such as gravity beneficiation can be appropriately employed. For example, if a liquid with a desired specific gravity is prepared, such as in heavy liquid beneficiation, and a extracted catalyst is supplied to it, the catalyst with a large amount of deposited metal will settle, and the catalyst with a relatively small amount of deposited metal will float or float in the liquid. , only those catalysts that still maintain their activity can be recovered. In this case, the amount of catalyst that settles depends on the specific gravity of the liquid used as the separation medium, so
It is possible to adjust the specific gravity of the liquid while taking into consideration the activity level of the catalyst to be returned to the catalytic cracker. Gases such as air can also be used as the sorting medium. [Example] A portion of the fluidized catalyst was randomly extracted from an operating hydrocarbon oil catalytic cracking apparatus and subjected to specific gravity selection. 1,1,2,2-tetrabromotaene (specific gravity =
2.959g/ml) and 1,1,2,2-tetrachloroethane (specific gravity = 1.600g/ml) to obtain a specific gravity of 2.6.
g/ml solution, add a part of the catalyst (referred to as A) extracted from the actual device, and stir it. The catalyst will be separated into those that float and those that settle. ) and precipitation catalyst (C
−1) were collected. Next, both catalysts were washed with carbon tetrachloride, dried, and calcined to remove the solution, and then the amount of deposited metal was measured and the activity of each catalyst was evaluated. In addition, two types of solutions with different specific gravity by changing the mixing ratio of the halogenated hydrocarbons were prepared, and two types of floating catalysts (B -2 and B-3) and two types of precipitated catalysts (referred to as C-2 and C-3) were obtained. For each of these catalysts, the amount of precipitated metal was measured and the activity was evaluated. The results are summarized in Table-1. In addition, an ASTM MAT device was used to evaluate the activity.
The following reaction conditions were adopted. Raw material DSVGO Reaction temperature 482℃ WHSV 16 1/hr Catalyst/oil ratio 3

【table】

[Table] As can be seen from Table 1, the light catalysts B-1, B-2, and B-3, which were separated based on the difference in specific gravity, had a smaller amount of metal deposit than the original extracted catalyst A, and had a higher conversion rate. , high gasoline yield. Further, by adjusting the specific gravity of the liquid used for specific gravity separation, the activity of the floating catalyst can be adjusted as desired. Furthermore, all of the above-mentioned light catalysts B-1, B-2, and B-3 can be returned to the catalytic cracker and reused. [Effects] The effects when the light catalyst separated by the difference in specific gravity is returned to the apparatus and reused according to the method of the present invention will be specifically explained. Now, feed oil with a metal content of 2 ppm and a specific gravity of 331 lb/BBL is supplied to a fluid catalytic cracker at a rate of 20,000 BBL/day, and the amount of metal (V+Ni) deposited on the catalyst in the equipment is measured.
In order to maintain the 5000 ppm level and continue operation, 0.13 lb/BBL of catalyst must be periodically removed from the equipment and a corresponding amount of new catalyst must be replenished into the equipment. , instead of the new catalyst of 0.13 lb/BBL supplied to the apparatus, a mixture of catalyst B-3 of the above example and new catalyst in a weight ratio of 3:7 was supplied to the apparatus, and the metal of the catalyst in the apparatus was replenished. Consider the case where the amount of deposition is maintained at the same level as above. In this case, catalyst B-3 with a metal deposition amount of 3070 ppm is mixed with new catalyst at a ratio of 3:7, so the average metal deposition amount of the catalyst (mixture) supplied to the device is
920 ppm, and the allowable amount of metal deposition from feedstock for this catalyst is (5000−920) ppm, approximately
It becomes 4100ppm. By the way, the relationship between the metal content of feedstock oil and the amount of metal deposited on the equilibrium catalyst is determined by DGThiel.[O&GJ.,
Aug. 18 (1980)], the amount of metal deposited on the equilibrium catalyst (ppm) = the amount of feedstock oil supplied (lb/
day) × Metal content of feedstock oil (ppm) / Catalyst replenishment amount (lb
/day). Therefore, when calculating the amount of replenishment when mixing catalyst B-3 and new catalyst and replenishing the equipment from the above relational expression, the amount of catalyst replenishment = 20000 (BBL/day) x 311 (lb/BBL) x 2
(ppm)/4100 (lb/day), which is equivalent to 0.16 lb/BBL. In other words, when maintaining the amount of metal deposited on the catalyst in the equipment at a level of 5000 ppm, if all the catalyst to be supplied to the equipment is supplied with new catalyst, 0.13 lb/BBL
of new catalyst is required, whereas the amount of new catalyst required when catalyst B-3 is used in combination at the above mixing ratio is
0.16×0.7=0.11 lb/BBL, approximately 15% (0.02
lb/BBL).

Claims (1)

[Claims] 1 In a method of catalytically cracking heavy hydrocarbon oil in the presence of a fluidized catalyst, the catalyst discharged from the catalytic cracker is divided into heavy catalysts and light catalysts based on the difference in specific gravity, and the light catalyst is subjected to catalytic cracking. A fluid catalytic cracking method for heavy hydrocarbon oil, which is characterized by returning it to the equipment for reuse.