JP2002241765A - Fluid catalytic cracking of heavy oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluid catalytic cracking method for fluid catalytic cracking of heavy oil at high temperature and short contact time to obtain light olefins such as propylene and butene in high yield. . SOLUTION: This is a fluid catalytic cracking method for heavy oil, which produces a light olefin using a fluid catalytic cracking reactor having a reaction zone 1, a gas-solid separation zone 2, a stripping zone 3, and a catalyst regeneration zone 4, Reaction zone outlet temperature is 550
~ 630 ° C, hydrocarbon residence time in the reaction zone is 0.0
1 to 1.0 second, and the heavy oil has a hydrogen partial pressure of 7.84.
A fluidized catalytic cracking method for heavy oil, characterized in that it is a reduced pressure gas oil that has been hydrotreated under the conditions of MPa (80 kg / cm ² ) or more.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid catalytic cracking method for heavy oil, and more particularly to a fluid catalytic cracking method for obtaining light olefins such as propylene and butene from heavy oil in high yield.

[0002]

2. Description of the Related Art In conventional catalytic cracking, petroleum hydrocarbons are decomposed by contact with a catalyst to obtain gasoline as a main product, a small amount of LPG, cracked gas oil, and the like. The catalyst is circulated and reused by burning off with air. However, recently, there has been a movement to utilize a fluid catalytic cracking unit not as a gasoline production unit but as a light olefin (particularly propylene) production unit as a petrochemical raw material. On the other hand, propylene and butene are raw materials for alkylate and methyl-t-butyl ether (MTBE) which are high octane gasoline base materials. The use of such a fluid catalytic cracking unit has a particular economic advantage in a refinery where petroleum refining and petrochemical plants are highly connected. As a method for producing a light olefin by fluid catalytic cracking of heavy oil, for example, a method of shortening the contact time between a catalyst and a feed oil (US Pat. No. 4,419,221)
No., U.S. Pat.No. 3,074,878, U.S. Pat.No. 5,462,652,
European Patent No. 315,179A), a method in which the reaction is carried out at a high temperature (US Pat. No. 4,980,053), a method using a pentasil type zeolite (US Pat. No. 5,326,465, published patent publication 7).
-506389) and the like.

However, even in these methods, the selectivity of light olefins has not yet been sufficiently increased.
For example, in a method using a high-temperature reaction, unnecessary dry gas yield increases due to simultaneous thermal decomposition, and the yield of useful light olefins is sacrificed accordingly. In addition, the high temperature reaction has the disadvantage that the quality of gasoline obtained with light olefins is deteriorated due to the increased production of diene. In the method of shortening the contact time, the hydrogen transfer reaction can be suppressed, and the rate of conversion of light olefins to light paraffin can be reduced, but the conversion cannot be increased.
Light olefin yields are still inadequate. Further, a method has been proposed in which thermal decomposition is suppressed by combining these high-temperature reactions, high catalyst / oil ratio, short contact time and other techniques, and a high conversion is achieved (Japanese Patent Laid-Open No. 10-60453). However, the light olefin yield is not yet sufficient. In addition, in the method using pentasil-type zeolite, gasoline is only decomposed to increase the light olefin yield, so that the light olefin yield is not sufficiently increased and the gasoline yield is significantly reduced. . Therefore, it is difficult to obtain a light olefin from a heavy oil in a high yield by these methods.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an improved heavy oil that can produce a small amount of dry gas due to thermal cracking and obtain a high light olefin yield by limiting the reaction conditions and the starting heavy oil. An object of the present invention is to provide a fluid catalytic cracking method for high quality oil.

[0005]

SUMMARY OF THE INVENTION The present inventors have developed a fluid catalytic cracking process for obtaining light olefins such as propylene and butene by subjecting heavy oil to fluid catalytic cracking at a high temperature for a short contact time. As a result of diligent research focused on obtaining light olefins, it was found that the purpose was achieved by fluid catalytic cracking using specific heavy oil and under specific conditions, and reached the present invention. It is. That is, the present invention is a method for fluid catalytic cracking of heavy oil for producing light olefins using a fluid catalytic cracking reactor having a reaction zone, a gas-solid separation zone, a stripping zone and a catalyst regeneration zone, comprising a reaction zone outlet. Temperature 550-630
° C, the residence time of hydrocarbons in the reaction zone is 0.01-1.
0 seconds and the heavy oil has a hydrogen partial pressure of 7.84 MPa.
(80 kg / cm ² ) The present invention relates to a method for catalytic cracking of heavy oil, characterized in that it is a reduced pressure gas oil which has been hydrotreated under conditions of 80 kg / cm ² or more.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in more detail. The present invention is a method for fluid catalytic cracking of heavy oil for producing light olefins using a fluid catalytic cracking reactor having a reaction zone, a gas-solid separation zone, a stripping zone and a catalyst regeneration zone. In the present invention, fluidized catalytic cracking is a process in which heavy oil is continuously brought into contact with a catalyst held in a fluidized state to crack heavy oil into light hydrocarbons mainly composed of light olefins and gasoline. .

The usual fluid catalytic cracking method employs a so-called riser-reaction zone in which both the catalyst particles and the feed oil rise in the tube. However, when a normal riser reaction zone is used, back mixing occurs, locally increasing the residence time of the gas, and causing thermal decomposition. In particular, when the reaction temperature is higher than that of the ordinary fluid catalytic cracking method as in the present invention, the degree of thermal decomposition due to back mixing increases. Thermal cracking is not preferred because it increases the generation of unnecessary dry gas and decreases the yield of the target light olefin and gasoline. In the present invention, the type of the reaction zone is not particularly limited, but a downflow type (downer) reaction zone in which both the catalyst particles and the feed oil descend in the tube is preferably employed to avoid back mixing.

[0008] The cracking reaction mixture, which is a mixture of the cracking reaction product, the unreacted product and the spent catalyst, which has undergone the fluid catalytic cracking, is then sent to a gas-solid separation zone, where the cracking reaction product, unreacted product is separated from the catalyst particles. Most of the hydrocarbons such as substances are removed. In some cases, the decomposition reaction mixture is quenched immediately before or immediately after the gas-solid separation zone in order to suppress unnecessary thermal decomposition or excessive decomposition.

The spent catalyst from which most of the hydrocarbons have been removed is further sent to a stripping zone, where the stripping gas removes hydrocarbons that could not be completely removed in the gas-solid separation zone. After the spent catalyst and hydrocarbons are separated in this way, the spent catalyst to which the carbonaceous material and some heavy hydrocarbons are attached is regenerated from the stripping zone in order to regenerate the spent catalyst. Sent to the band. In the catalyst regeneration zone, the spent catalyst is subjected to an oxidation treatment to remove and regenerate carbonaceous substances and heavy hydrocarbons deposited and adhered on the catalyst. The catalyst regenerated after the oxidation treatment is sent again to the reaction zone and continuously circulated.

FIG. 1 shows an example of a fluid catalytic cracking reaction apparatus used in the present invention. In this example, a fluid catalytic cracking reactor having a downflow type reaction zone is shown. Figure 1
In, the heavy oil as the raw material is supplied to the mixing area 7 through the line 10 and mixed with the regenerated catalyst circulated from the catalyst storage tank 6. The mixture flows down in the reaction zone 1 in a parallel flow, during which the raw heavy oil and the catalyst are brought into contact with each other at high temperature for a short time to carry out the cracking reaction of the heavy oil. The cracked reaction mixture from reaction zone 1 flows down to gas-solid separation zone 2 located below reaction zone 1, where the spent catalyst is separated from the cracked reaction products and unreacted raw materials and dipreg 9 is removed. Through the stripping zone 3.

The hydrocarbon gas from which most of the spent catalyst has been removed is then led to a secondary separator 8. Here, a small amount of used catalyst remaining in the gas is removed, and the hydrocarbon gas is extracted out of the system and collected. As the secondary separator 8, a tangential cyclone is preferably used.

From the spent catalyst in the stripping zone 3, hydrocarbons adhering and remaining on the surface of the spent catalyst and between the catalysts are removed by the stripping gas introduced from the line 11. As the stripping gas, an inert gas such as steam generated by a boiler or nitrogen pressurized by a compressor or the like is used.

The stripping conditions include a temperature of 500 to 900 ° C., preferably 500 to 700 ° C., and a residence time of the catalyst particles of 1 to 10 minutes. In the stripping zone 3, cracking reaction products and unreacted raw materials adhering to the used catalyst and unreacted raw materials are removed, and the stripping gas and the line 12 at the top of the stripping zone 3 are removed.
, And guided to the recovery system. On the other hand, the spent catalyst which has been subjected to the stripping treatment is supplied to the first flow controller 13
Is supplied to the catalyst regeneration zone 4 through a line provided with.

The gas superficial velocity in stripping zone 3 is:
Usually, it is preferable to keep the pressure in the range of 0.05 to 0.4 m / s, so that the fluidized bed in the stripping zone can be a bubble fluidized bed. In the bubble fluidized bed, since the gas velocity is relatively low, the consumption of the stripping gas can be reduced, and since the bed density is relatively large, the pressure control width of the first flow rate controller 13 can be increased. Therefore, the transfer of the catalyst particles from the stripping zone 3 to the catalyst regeneration zone 4 becomes easy. Stripping band 3
In order to improve the contact between the used catalyst and the stripping gas and improve the stripping efficiency, a horizontal perforated plate or other inserts can be provided in multiple stages.

The catalyst regeneration zone 4 is defined by a vessel having an upper region having a conical shape and a lower region having a cylindrical shape, and the upper conical portion thereof communicates with an upright conduit (riser-type regeneration tower) 5. In the catalyst regeneration zone 4, the apex angle of the upper conical portion is usually 30 to 90.
Preferably, the height of the upper conical portion is in the range of 1/2 to 2 times the diameter of the lower cylindrical portion. The spent catalyst supplied from the stripping zone 3 to the catalyst regeneration zone 4 is regenerated by a regeneration gas (typically an oxygen-containing gas such as air) introduced from the bottom of the catalyst regeneration zone 4.
While being fluidized, substantially all of the carbonaceous materials and heavy hydrocarbons attached to the catalyst surface are burned off and regenerated. The regeneration conditions are usually at a temperature of 600 to 10
00 ° C, preferably 650-750 ° C, catalyst residence time 1
~ 5 minutes is adopted, and the gas superficial velocity is usually 0.4 ~
1.2 m / s is preferably adopted.

The regenerated catalyst that has been regenerated in the catalyst regeneration zone 4 and has jumped out from the upper part of the turbulent fluidized bed is transferred from the upper conical portion to the riser type regeneration tower 5 together with the used regeneration gas. The diameter of the riser-type regeneration tower 5 communicating with the upper conical portion of the catalyst regeneration zone 4 is one of the diameter of the lower cylindrical portion.
/ 6 to 1/3. By doing this,
The gas superficial velocity of the fluidized bed in the catalyst regeneration zone 4 can be maintained in a range of 0.4 to 1.2 m / s suitable for forming a turbulent fluidized bed. Tower speed,
The range of 4 to 12 m / s suitable for ascending transfer of the regenerated catalyst can be maintained.

The regenerated catalyst that has risen inside the riser type regeneration tower 5 is carried to a catalyst storage tank 6 installed at the top of the riser type regeneration tower. The catalyst storage tank 6 also functions as a gas-solid separator, and the used regeneration gas containing carbon dioxide gas and the like is separated from the regeneration catalyst here and discharged outside the system via the cyclone 15.

On the other hand, the regenerated catalyst in the catalyst storage tank 6 is supplied to the mixing area 7 via a downflow pipe provided with a second flow controller 17. If necessary, a part of the regenerated catalyst in the catalyst storage tank 6 is regenerated through a bypass conduit provided with a third flow controller 16 in order to facilitate control of the amount of catalyst circulated in the riser type regenerator 5. You can change it back to 4. As described above, the catalyst passes through the reaction zone 1, the gas-solid separation zone 2, the stripping zone 3, the catalyst regeneration zone 4, the riser type regeneration tower 5, the catalyst storage tank 6, and the mixing zone 7, and then again into the reaction zone 1. Circulating in the system.

In the present invention, the reaction zone outlet temperature refers to the outlet temperature of a riser or a downer reactor, and is a temperature immediately before a decomposition reaction product is separated from a catalyst, or is quenched immediately before a gas-solid separation zone. In this case, it is the temperature immediately before quenching. In the present invention, the reaction zone outlet temperature is 55
It is 0-630 degreeC, Preferably it is 580-620 degreeC. If the temperature is lower than 550 ° C., a light olefin cannot be obtained in a high yield, and if the temperature is higher than 630 ° C., thermal decomposition becomes remarkable and the amount of dry gas generated is not preferable. The hydrocarbon residence time referred to in the present invention is the time from when the regenerated catalyst comes into contact with the feed oil until the catalyst and the decomposition reaction product are separated at the reaction zone outlet, or when quenched before the separation zone. Indicates the time until quenching. In the present invention, the residence time is from 0.01 to 1.0 second, preferably from 0.05 to 0.8 second, and more preferably from 0.1 to 0.6 second. When the residence time of the hydrocarbon in the reaction zone is shorter than 0.01 second, the cracking reaction becomes insufficient and a light olefin cannot be obtained with a high yield. If the residence time is longer than 1.0 second, the contribution of thermal decomposition increases, which is not preferable.

There are no particular restrictions on the operating conditions of the fluid catalytic cracking reactor of the present invention other than those described above.
Usually, the reaction pressure is 196 to 392 kPa (1 to 3 kg / c
m ² G), regeneration zone temperature 600-1000 ° C., preferably 650-750 ° C., catalyst / oil ratio 8-40 weight / weight,
It is preferably operated at 12 to 30 weight / weight. Here, the catalyst / oil ratio means the catalyst circulation amount (ton /
h) and the feed rate (ton / h) of the feedstock.

The heavy oil, which is the feedstock oil used in the present invention, is reduced-pressure gas oil (distillate from a reduced-pressure distillation unit) which has been treated by a hydrotreatment unit. The partial pressure needs to be 7.84 MPa (80 kg / cm ² ) or more, and preferably 9.8 MPa (100 kg / cm ² ).
kg / cm ² ) or more. By treating vacuum gas oil under such a high hydrogen partial pressure, not only nitrogen compounds which are poisons of the fluid catalytic cracking catalyst are removed, but also aromatic components in the vacuum gas oil are hydrogenated to become saturated components. Therefore, the decomposition reactivity of the vacuum gas oil becomes extremely high. If the hydrogen partial pressure of the hydrotreating device is less than 7.84 MPa (80 kg / cm ² ), the hydrogenation of aromatics in the vacuum gas oil does not proceed sufficiently. A high olefin yield cannot be obtained by catalytic cracking.

The other operating conditions in the hydrotreating apparatus are not particularly limited, but usually, the reaction temperature is 35.
0-430 ° C, LHSV 0.5-4, hydrogen / oil ratio 1,
It is preferably operated at 000 to 4,000 scf / bbl. Preferred properties of the vacuum gas oil used as a feed oil in the fluid catalytic cracking method of the present invention include a hydrogen content:
13% by mass or more, preferably 13.5% by mass or more, nitrogen content: 0.01% by mass or less, preferably 0.005% by mass
Or less, sulfur content: 0.1% by mass or less, specific gravity (15 ° C.):
0.80 to 0.85 g / cm ³ , aniline point: 100 to
130 ° C. The preferable distillation properties of the vacuum gas oil are as follows: 10% distillation point: 250 to 470 ° C, preferably 34%
0-420 ° C, 50% distillation point: 300-520 ° C, preferably 400-500 ° C, 90% distillation point: 340-56.
0 ° C., preferably 470-550 ° C.

The catalyst used in the fluid catalytic cracking method of the present invention comprises zeolite as an active component and a matrix as a supporting base thereof. The main component of the zeolite is ultra-stable Y
It is a type zeolite. The content of the zeolite in the catalyst is preferably 5 to 50% by mass, more preferably 15 to 40% by mass. As the catalyst used in the fluid catalytic cracking method of the present invention, in addition to the ultra-stable Y-type zeolite, crystalline aluminosilicate zeolite or silicoaluminophosphate (SA) having a smaller pore diameter than Y-type zeolite is used.
PO). Such zeolites or SAPOs include ZSM-5, β, Omega, SA
PO-5, SAPO-11 and SAPO-34 can be exemplified. These zeolites or SAPOs may be contained in the same catalyst particles as the catalyst containing the ultra-stable Y-type zeolite, or may be different particles. The bulk density of the catalyst used in the fluid catalytic cracking method of the present invention is 0.5 to
1.0 g / ml, average particle size 50-90 μm, surface area 50-350 m ² / g, pore volume 0.05-0.5 m
It is preferably in the range of 1 / g.

[0024]

Next, embodiments of the present invention will be described, but the present invention is not limited thereto.

Example 1 Using a downer type FCC pilot device, heavy oil was
Fluid catalytic cracking was performed. The equipment scale is the inventory
5 kg, feed rate 1 kg / h.
Actor outlet temperature 600 ° C, reaction pressure 196kPa
(1.0kg / cm ^TwoG), catalyst / oil ratio of 15.5 weight /
Weight and regeneration tower temperature are 720 ° C. At this time the reactor
The hydrocarbon residence time in the reactor was 0.4 seconds. Catalyst used
Is a commercially available fluid catalytic cracking catalyst (manufactured by Catalyst Chemical Industry Co., Ltd.
Harmorex). Equipped with a fluid catalytic cracking catalyst
100% steam at 810 ° C for 6 hours before filling
And steamed. Heavy oil used as feedstock
Bianlite vacuum gas oil was converted to hydrogen partial pressure of 14.7 MPa (1
50kg / cm^Two), Reaction temperature 400 ° C, LHSV 1
Under the conditions described above. Hydrotreated
The properties of the vacuum gas oil obtained were as follows: specific gravity (15 ° C): 0.828 g
/ Cm^Three, Aniline point: 118 ° C, hydrogen content: 14.1
%, Nitrogen: 0.003 mass%, sulfur: 0.02
%, And the distillation property is 10%. Distillation point: 387
° C, 50% distillation point: 445 ° C, 90% distillation point: 512 ° C
Met. Table 1 shows the results of the decomposition reaction.

Comparative Example 1 The fluid catalytic cracking of heavy oil was carried out using the same apparatus and the same catalyst as in Example 1. The operating conditions are: reactor outlet temperature 6
00 ° C., reaction pressure 196 kPa (1.0 kg / cm
² G), a catalyst / oil ratio 14.9 wt / wt, regenerator temperature 7
20 ° C. The heavy oil used as the feed oil was a Arabian light vacuum gas oil with a hydrogen partial pressure of 6.37 MPa (65 kg).
/ Cm ² ), a hydrogenation treatment at a reaction temperature of 400 ° C. and an LHSV of 2. The properties of the hydrotreated vacuum gas oil are as follows: specific gravity (15 ° C): 0.897 g / c
m ³ , aniline point: 77.9 ° C., hydrogen content: 12.6 mass%, nitrogen content: 0.04 mass%, sulfur content: 0.13 mass%
The distillation properties were as follows: 10% distillation point: 384 ° C, 5
The 0% distillation point was 462 ° C and the 90% distillation point was 556 ° C. Table 1 shows the results of the decomposition reaction.

[0027]

[Table 1]

[0028]

As described above, by performing fluid catalytic cracking by limiting the reaction conditions and the raw material heavy oil, the amount of dry gas generated by thermal cracking is small, and light olefins such as propylene and butene can be produced with high yield. Obtainable.

[Brief description of the drawings]

FIG. 1 is an example of a fluid catalytic cracking reactor used in the present invention.

[Description of Signs] 1 Downflow type reaction zone 2 Gas-solid separation zone 3 Stripping zone 4 Regeneration zone 5 Riser type regeneration tower 6 Catalyst storage tank 7 Mixing area 8 Secondary separator 9 Dip-reg

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshiaki Okuhara, Saudi Arabia, Daharan 31261, Petroleum Industry Activation Center New FC C Saudi Branch Office (72) Inventor, Takashi Ino Kingdom of Saudi Arabia, Dahran 31261, Petroleum Industry Activation Center New FC C Saudi Branch Office (72) Inventor Harim Hamid Redwi Saudi Arabia, Dahlan 31261, King Fahd University of Petroleum and Minerals (72) Inventor Mohammad Abulhamael Saudi Arabia, Dahran 31261, King Fahd University of Petroleum and Minerals (72) Inventor Abdullah Aitani Dahran 3, Kingdom of Saudi Arabia 1261, King Fahd University of Petroleum and Minerals (72) Inventor Abdulgadel Magravi Saudi Arabia, Dahlan 31261, King Fahd University of Petroleum and Minerals F-term (reference) 4H029 BA12 BB03 BC04 BC03 DA08

Claims (1)

[Claims] 1. A method for fluid catalytic cracking of heavy oil in which a light olefin is produced using a fluid catalytic cracking reactor having a reaction zone, a gas-solid separation zone, a stripping zone and a catalyst regeneration zone, comprising a reaction zone outlet. Temperature is 550-630
° C, the residence time of hydrocarbons in the reaction zone is 0.01-1.
0 seconds and the heavy oil has a hydrogen partial pressure of 7.84 MPa.
(80 kg / cm ² ) A method for fluid catalytic cracking of heavy oil, which is a reduced pressure gas oil hydrotreated under conditions of not less than 80 kg / cm ² .