JPS5951338B2 - Method for preventing bogging of coke-adhered catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing hogging in a catalyst regeneration device when simultaneously producing light oil and hydrogen from heavy oil.

Atmospheric distillation residue oil: A method for lightening heavy oil by catalytic cracking has been developed in recent years, and the present inventors also investigated the existence of a catalyst containing 30 to 60% iron by weight of heavy oil. We have discovered a method in which the catalyst, which is made lighter by catalytic cracking and coated with coke, is reduced and then brought into contact with steam to produce hydrogen-rich gas.

The actual operating system of this method is as shown in FIG.

In the figure, heavy feedstock oil is transported through pipe 1 to the lower part of cracking tower 2 at a temperature of 450 to 600°C and 0 to 15 kgZcm2.
into a fluidized bed maintained at a pressure of G.

In the fluidized bed, a catalyst containing 30 to 60% by weight of granular iron is fluidized by a fluidizing gas introduced through tube 3.

Note that although steam is usually used as the fluidizing gas, decomposed exhaust gas may also be used.

In the cracking tower 2, the heavy oil is catalytically cracked by the catalyst to produce cracked oil and coke.

Heavy metals have been removed and the lightened cracked oil is taken out in gaseous form from the pipe 4 together with the fluidizing gas.

On the other hand, coke adheres to the catalyst and is sent to the regeneration tower 6 via the transfer pipe 5.

The regeneration tower 6 has a temperature of 750 to 950°C and a pressure of 0 to 15 kg/c.
A part of the coke deposited on the catalyst is partially combusted by the air maintained at a pressure of m2G and supplied from the pipe 7 according to the following formulas (1) and (2) to supply heat for the entire system, Reduces iron in the catalyst.

At this time, if the amount of coke deposited on the catalyst is insufficient to reduce iron and supply heat to the entire system, the regeneration tower 6
An auxiliary fuel such as a hydrocarbon may be directly supplied to the fuel for partial combustion.

Fe3O4+C-+FeO+CO+CO2...(1)
FeO+C-+Fe+CO+CO2'' (2) Exhaust gas containing carbon dioxide and carbon monoxide produced by the reaction between iron oxide and coke and the reaction between coke and oxygen is discharged from pipe 8.

The catalyst particles heated to 750 to 950°C are sent to the decomposition tower 2 and gasification tower 11 via pipes 9 and 10, respectively.

The catalyst containing reduced iron passes through a transfer pipe 10 to a gasification tower 11
There, the iron is oxidized by the steam supplied from the pipe 12 as shown in equations (3) to (4) below to generate hydrogen.

Fe1H20→FeO+H2...(3) FeO+H2
0-) Fe304+H2... (4) Note that gasification tower 1
Temperature in 1 is 600~800℃ and O~15kg/c
The pressure is maintained at m2G.

Since the oxidation reaction of iron mainly occurs in the gasification tower 11, the hydrogen concentration in the generated gas from the gasification tower 11 taken out from the pipe 13 is extremely high, and is usually 80% by volume or more on a dry basis.

The oxidized catalyst is recycled to the cracking column 2 via pipe 14.

The above-mentioned catalyst may be a catalyst obtained by crushing, granulating, and calcining iron-based natural ores such as laterite or magnetite, or
A synthetic iron-based catalyst containing 0% by weight and the remainder containing refractories such as alumina, silica, and magnesia, with a particle size range of 60 to 5.
It is possible to use a material with a diameter of 00μ.

As shown in FIG.
A catalyst with coke attached thereto is supplied from a transfer pipe 5 by a lift gas from a cracking tower 2, and a fluidized bed is formed by an oxygen-containing gas such as air supplied from a pipe 7.

As described above, the coke deposited on the catalyst or the hydrocarbons supplied as an auxiliary charge are partially combusted, and the iron in the catalyst is further reduced.

With respect to the height L of the fluidized bed of the regeneration tower 6, the transfer pipe 5 is connected at a position of 1 to about 173 L or more from the distribution plate 61 at the bottom of the fluidized bed.

Since the oxygen concentration is high directly above the dispersion plate, the heat of coke combustion is large. However, if there is a supply port for the catalyst transferred from the cracking tower at the above position, the low-temperature catalyst from the cracking tower 2 ( 540°C) cannot be expected, and the lift gas from the transfer pipe 5, which becomes part of the fluidizing gas, cannot contribute to the linear velocity directly above the dispersion plate, and the linear velocity directly above the dispersion plate is becomes smaller.

(For example, superficial velocity: 26.8 cm directly above the dispersion plate /
sec, fluidized bed average 37.0 cm/5 ec) Therefore, directly above the dispersion plate, FeO and Fe, which have relatively low melting points, partially melt and sinter to form coarse particles, so-called hogging (bo
gging) phenomenon, which makes the fluidized state of the fluidized bed unstable and prevents smooth circulation of the catalyst.

In the very early stage, this hogging phenomenon is caused by the coarse particles being small and few in number, and the effect of the catalyst particles being mutually weak, but within a short period of time it becomes coarse and causes the flow to stop, and eventually the entire particle bed is affected. forms a strong sintered body.

Therefore, when hogging occurs in the regenerator, a passage is created for blowing gas from above the distribution plate to the lower part of the fluidized bed, resulting in a decrease in pressure loss in the fluidized bed section.

Therefore, the occurrence of hogging can be known by monitoring changes in pressure loss in the fluidized bed section.

To prevent such hogging from occurring, it is effective to physically suppress it by lowering the temperature in the area where hogging is likely to occur, that is, directly above the dispersion plate, or by increasing the movement of particles. It turned out to be the most effective.

The present invention was developed with the aim of preventing the occurrence of hogging in regeneration towers based on the above-mentioned findings. In a fluidized bed apparatus in which a catalyst containing 30 to 60% by weight of iron is combusted under reducing conditions by contacting with an insufficient amount of oxygen-containing gas to completely burn coke, and at the same time reducing the catalyst, This method is characterized in that the coke-adhered catalyst is supplied from the bottom of the fluidized bed at a position 0 to 0.3 times the height of the fluidized bed.

In the illustrated apparatus system, the coke-adhered catalyst supply port from the cracking tower 2 is measured from the bottom of the fluidized bed with respect to the height L of the fluidized bed of the regeneration tower 6, and is 1=LX (0 to 0.3). It should be set within the range of .

The supply port may be located in the tower wall as shown in FIG. 3a, or may be opened directly through the distribution plate as shown in FIG.

In the latter case, the opening position is preferably located closer to the tower wall than the center of the distribution plate in order to avoid erosion of the tower wall W facing the supply side.

Furthermore, as shown in FIG. 4, the dispersion plate may be removed, the lower part of the fluidized bed may be made into a tapered structure, and the coke-adhered catalyst may be supplied from the transfer pipe 5 at the lower part.

In this case, the oxygen-containing gas is supplied from a pipe 7 provided on the side surface of the tapered part, but it is preferable that this pipe 7 is placed as far down as possible below the tapered part, and moreover, a plurality of pipes 7 may be provided (
tube 7').

Further, in order to enhance the effect of preventing hogging, it is more preferable to install the pipe 7 so that the particle movement causes a swirling flow.

As described above, according to the method of the present invention, a relatively low-temperature catalyst is supplied near areas where hogging is likely to occur, thereby lowering the temperature at the bottom of the fluidized bed and further increasing the movement of particles. Therefore, the occurrence of hogging in the regeneration tower can be effectively prevented by a very simple means.

The effects will be described below with reference to Examples.

Example 1 Column diameter 15. ICm, column length 180cm, fluidized bed height 50
In the regeneration tower of cm, the coke-adhered laterite I catalyst (Fe44.3wt%, Nil, 9%, Mg07.5
%, 510210.0, AI.

O35.7%, Na201.9%) was processed using the method of the present invention and the conventional method at a regeneration tower temperature of 950°C and a molar ratio of O2/C of 0.
．． The results of playback in step 4 are shown below.

Incidentally, the occurrence of hogging was determined based on the presence or absence of a decrease in pressure loss in the fluidized bed section within the tower.

As shown in the table above, the linear velocity directly above the dispersion plate is 26.8 cm/sec.
In this case, if the position of the coke-adhered catalyst supply port was 0.3 or less with respect to the height of the fluidized bed, hogging did not occur.

Example 2 A column with a diameter of 15.1 mm as shown in Figure 4 was designed so that the height of the tapered section and the fluidized bed section above the tapered section were the same.
cm, the coke adhesion rate was 4.0% by weight, the catalyst temperature at the inlet of the regeneration tower was approximately 300°C, and the coke adhesion catalyst from the cracking tower (composition was the same as in Example 1) was transported by air flow from the cracking tower to the regeneration tower. .

The gas linear velocity at the regeneration tower population of 5 was approximately 7 m/sec.

The location of the oxygen-containing gas inlet to the regeneration tower is a part of the taper.
It was 10 cm.

Although the experiment was conducted at an average linear velocity of 37 cm/sec for the fluidized main part, no decrease in pressure loss in the fluidized bed part in the regeneration tower was observed, and no hogging was observed.

[Brief explanation of drawings]

Figure 1 is a flow sheet for lightening heavy oil using a three-unit circulating fluidized bed apparatus, Figure 2 shows the structure of a conventional regeneration tower, and Figures 3 and 4 respectively. This shows a specific example of the present invention.

Claims (1)

[Claims] 1. In a fluidized bed apparatus in which a catalyst to which coke is attached and which contains 30 to 60% by weight of iron is brought into contact with an oxygen-containing gas insufficient to completely burn the coke to be combusted under reducing conditions, and at the same time the catalyst is reduced. A method for preventing hogging of a coke-adhered catalyst, characterized in that the coke-adhered catalyst is supplied at a position 0 to 0.3 times the height of the fluidized bed from the lower part of the fluidized bed.