JPS594475B2 - Catalytic cracking method and equipment for heavy oil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for catalytic cracking of heavy oil, including heavy crude oil such as China's Daqing crude oil and Shengli crude oil, atmospheric distillation residue, vacuum distillation residue, tar sand oil, A low-activity catalyst is added to heavy oil such as Sierre oil and similar heavy hydrocarbons, and catalytic cracking is carried out at varying temperatures in at least two stages to convert the heavy oil into a kerosene-rich oil fraction. The purpose of the present invention is to provide a method and apparatus for catalytic cracking of heavy oil, which can be cracked into light oil and petrochemical raw material gas rich in olefins with good yield, and which does not produce tar or pitch as by-products.

Since the oil crisis of 1973, the diversification of Japan's crude oil supply sources has been promoted, and the global demand for light crude oil is increasing, so Japan's imported crude oil has become increasingly heavier.

On the other hand, demand for petroleum products is increasing, with demand for kerosene and diesel oil distillates increasing.
Petroleum products are following a trend toward lighter petroleum products, and there is a need for cracking technology that can accommodate heavier crude oil and lighter petroleum products.

Conventionally, FCC (FluidCa) has been used as a crude oil catalytic cracking method.
There is a (ralyfic cracking) law, but
This process uses hydrocarbons such as kerosene, which has a relatively narrow boiling point range, as a raw material, and uses a large amount of highly active catalysts such as synthetic silica alumina or zeolite. The aim is to collect a large amount of gasoline fraction through one-time catalytic cracking.

In this method, the yield of the gasoline fraction is as high as 50 wt% or more, but the unsaturated components undergo thermal polymerization, resulting in an increase in tar-like heavy oil, and the middle distillate below 330°C, so-called white oil, increases. Yield is low.

Furthermore, even if heavy oil is catalytically cracked by the conventional FCC method using a catalyst with low activity, the operating control range is relatively narrow.
It is difficult to increase the yield of white oil using the CC method.

Furthermore, when heavy oil is heated to a high temperature of 500°C, tar-like or solid decomposition residues adhere to and accumulate on the inner walls of pipes due to thermal polymerization of decomposed unsaturated substances, clogging the pipes and forcing the operation to be interrupted. However, it is not easy to heat heavy and light oil to high temperatures.

Furthermore, when heavy oil is heated to high temperatures, a large amount of by-products such as tar and pitch are produced, which poses problems in terms of their use and use.

The present invention solves the above problems and produces heavy oil that does not produce tar or pitch as a by-product and has an overwhelmingly high yield of light oil rich in middle distillates such as kerosene and gas oil, for which demand is expected to increase. The present invention provides a catalytic cracking method and apparatus.

The method for catalytic cracking of heavy and light oil according to the present invention begins with a catalyst ratio of 0.
．． A catalyst with a low activity of 0.05 to 0.5, such as colloid or allophane, is added to and mixed with heavy oil, and heated to about 350 to 500°C in a primary cracking furnace with an externally heated tubular furnace structure. Perform primary catalytic cracking.

Although catalytic cracking is started at a relatively low temperature of about 350° C. or higher, the decomposition residue adheres to the surface of the catalyst particles and does not adhere to the inner wall surface of the pipe and clog the pipe.

Next, the same catalyst is added to the remaining gas produced by the first catalytic cracking at a catalyst ratio of about 4 to 10.
The second catalytic cracking is carried out by heating at a temperature higher than the first catalytic cracking and about 400 to 600°C.

This second catalytic cracking is slightly different from the first catalytic cracking method and is carried out in a fluidized manner.

That is, heavy oil, etc. from the primary cracking furnace is placed in the upper part of the secondary cracking furnace, which consists of a vertical fluidized bed in which catalysts, etc. are fluidized in multiple stages with high-temperature steam of about 500 to 800°C. The second catalytic cracking is carried out while the gas is introduced and fluidized to the lower part, and the heating temperature at this time is lower in the upper part, and the lower crosspiece decomposition temperature is raised.

That is, the initial stage of the second catalytic cracking is carried out at a low temperature, and as the catalytic cracking progresses, the temperature is raised.

Then, the gas produced by decomposition at each temperature is taken out at any time.

Therefore, in secondary catalytic cracking, heavy oil adheres to the catalyst in the liquid phase and is subjected to catalytic cracking to produce gaseous decomposition products, which are then immediately removed from the cracking system without being overly decomposed, and undecomposed products are removed from the cracking system. In the next fluidized bed, it undergoes catalytic decomposition by receiving heat from high-temperature steam, etc., gradually becoming solid, and finally becomes decomposed carbon that adheres to the surface of the catalyst particles.

As a result, in the second catalytic cracking, no tar or pitch is produced as a by-product, and light oil rich in kerosene components can be produced.

Next, a heavy oil catalytic cracking apparatus according to the present invention will be explained.

In FIG. 1, 1 is a primary cracking furnace, 2 is a secondary cracking furnace, 3 is a regeneration furnace, 4 is a heating furnace, 5 is a reflux device, 6 is a cooler,
7 is a rectification column, 8 is a lifter, 9 is a catalyst mixer, io, i
i is a control valve.

The primary cracking furnace 1 has an external heating type tubular furnace structure, and can burn the waste gas containing flammable gas from the regeneration furnace 3 to heat the heavy oil in the pipe. .

The heavy oil Fo is mixed with the catalyst from the regeneration furnace 3 at a catalyst ratio of 0.05 to 0.5 in the catalyst mixer 9, and is then supplied to the primary cracking furnace 1.

Then, in the primary cracking furnace 1, the heavy oil is heated to about 350 to 500℃.
The first catalytic cracking is carried out.

At this time, low-molecular-weight hydrocarbons that are part of the heavy oil are catalytically cracked at a temperature of about 350° C. or higher, and decomposition residues generated during the cracking adhere to the surface of the catalyst particles.

Therefore, in the first catalytic cracking, decomposition residues do not adhere to and accumulate on the inner wall surface of the pipe, and the pipe line is not blocked.

The heavy oil, gaseous cracking products, catalyst, and cracking residue that have undergone the first catalytic cracking are supplied from the first cracking furnace 1 to the upper part of the second cracking furnace 2 .

The secondary cracking furnace 2 has a vertical fluidized bed structure with a plurality of fluidized beds, for example, 2 to 6 stages, and the catalyst is supplied from the regeneration furnace 3 to the upper fluidized bed, and then in the heating furnace 4 about 50
It is fluidized by steam or the like heated to 0 to 800°C, and is sent from the upper fluidized bed to the lower fluidized bed.

This secondary cracking furnace 2 with a vertical fluidized bed structure is shown in Figs.
As shown in Figures a to f, each part of the cylindrical body 20 is divided by a partition plate 21, and a perforated plate 22 is attached to each divided part. A partition plate 23 is attached to the plate 22.

Further, a pipe 24 is attached to the partition plate 21 to communicate the parts divided by the partition plate 21.

The structure of this divided interior may be the same, but it may also be of a different structure. For example, in the section A, the perforated plate 22 is configured flat, and the partitions are of the same height. Board 2
3 is attached in parallel to the wall of the cylindrical body 20, and in the section B, the perforated plate 22 is configured flat, and the partition plate 23 of the same height is attached only at one end. Cylindrical body 20
It is connected to the wall and is installed parallel to the wall so that the contacting parts are alternate. It was installed in a stair-like manner, and the divisions were as follows:
The perforated plates 22 are installed at an angle, and the partition plates 23 are installed in a stepped manner.

In the part F, the perforated plate 22 is attached flat and the partition plate 23 is attached in a substantially spiral shape.

The configurations of these divisions A to F each have their own characteristics.For example, in the structure of division A, the structure is simple and can be manufactured at low cost, and the catalyst etc. supplied to one end are separated from the partition plate 2.
3 overflows and moves in a fluid manner as shown by the arrow, so the moving speed of the catalyst, etc. can be made uniform, and there is no drawback that only some catalysts, etc. reach the other end quickly. There is a drawback that a part of the catalyst etc. returns in the opposite direction at a time, but in the structure of Section B, the moving speed of the catalyst etc. can be made uniform, making it easier to compensate for the concentration difference of heavy oil. In the structure of section C, the drawbacks of the structure of section A can be eliminated, but the structure becomes that much more complicated.
In addition, in the structure of the partition, the movement of the catalyst has the same characteristics as that of the partition C, and the structure is simple, but the perforated plate 22
Since the partition plate 23 is sloped, the height of the fluidized bed is not uniform and there is a drawback that flow sag tends to occur.The structure of sections E and F has the same features as section B, but It has the characteristic that it is troublesome to install.

Therefore. When implementing the process, the type of partition structure to be adopted is determined based on the heavy oil decomposition time, temperature, catalyst movement speed, mixing speed of the catalyst and heavy oil, and other design conditions.

The heavy oil supplied to section A of the secondary cracking furnace 2 is
Next, the gaseous decomposition products produced by catalytic cracking are separated,
This gaseous decomposition product Hc is sent to the reflux device 5.

On the other hand, the residual heavy oil, the catalyst of the first catalytic cracking, and the cracked residue attached thereto are added to and mixed with the high temperature catalyst supplied from the regeneration furnace 3, and the second catalytic cracking is performed.

This second catalytic cracking has a catalyst ratio of 4 to 10 and a temperature of about 4
It is carried out at a temperature of 00 to 600°C and above the temperature during the first catalytic cracking.

The heavy oil adheres to the particle surface of the catalyst, flows together with the catalyst by high-temperature steam, and receives decomposition heat from the sensible heat of the catalyst and the sensible heat of the high-temperature steam, and undergoes catalytic cracking.

Gaseous decomposition products from catalytic cracking are taken out together with water vapor, and these are sent to the reflux vessel 5, while the remainder is sent to section B.
It is sent through pipe 24 to section A, and catalytic cracking is carried out in the same manner as section A.

However, the temperature during catalytic cracking in section B is the same as section A.
The temperature is kept about 20 to 50°C higher than the temperature during catalytic cracking.

Furthermore, catalytic cracking is performed in sections C, D, E, and F in the same manner.

In this case, the temperature during catalytic cracking is higher in section C than in section B, higher in section C than in section C, higher in section E than in section E, and higher in section F than in section E. The temperatures at 1 and 2 are about 20 to 50°C higher, respectively.

Then, gaseous decomposition products H generated in each section are
c is taken out together with water vapor, the entrained catalyst is separated by a cyclone 25 provided in section A, and the catalyst is cooled to about 350° C. or lower through a reflux device 5 and a cooler 6, and then supplied to a rectification column 7. Ru.

In the final section F, the heavy oil becomes decomposed carbon, which is a decomposition residue, and only adheres to the surface of the catalyst particles, and these materials are taken out from the secondary cracking furnace.

The reaction time in this second catalytic cracking is different from that in the first catalytic cracking, and is relatively long, for example, about 5 to 3
It is 0 minutes.

In this way, the secondary catalytic cracking of heavy oil is carried out using a catalyst with relatively low activity, such as allophane, and the gaseous decomposition products produced by the cracking are immediately taken out, and the unsaturated products caused by overcracking are removed. In addition to preventing condensation polymerization of hydrocarbons, the decomposition temperature of undecomposed heavy oil is gradually increased, and catalytic cracking is performed over a relatively long period of time to completely decompose the heavy oil and convert the decomposition residue into decomposed carbon. By attaching it to a catalyst and removing it from the cracking system, heavy oil can be catalytically cracked without producing tar or pitch as by-products, and the cracked product is a light oil containing a large amount of middle distillate from kerosene and gas oil fractions. and,
It becomes a cracked gas suitable for petrochemical feedstocks rich in olefins.

Note that nitrogen, hydrogen, and other low-molecular hydrocarbons can also be used instead of the steam that flows the catalyst and supplies the heat of decomposition, but these must not contain oxygen. .

The use of hydrogen is particularly desirable because it prevents dehydrogenation reactions during decomposition and is non-condensable.

Finally, in the rectification column 7, the cracked gas and gasoline fraction N
P, kerosene and light oil fraction Kr, and heavy oil fraction Ho.

Note that, if necessary, a part of the high boiling point fraction of the gaseous decomposition products in the reflux vessel 5 is liquefied and separated and returned to the second cracking furnace 2 for catalytic cracking.

The catalyst with decomposed carbon attached thereto taken out from the secondary cracking furnace is sent to the regeneration furnace 3 by steam St via a lifter 8 via a control valve 11.

This regeneration furnace 3 has a fluidized bed structure in which the catalyst is fluidized with air Ar, and the spent catalyst is fluidized with air to burn off attached decomposed carbon at about 550 to 800°C, and to perform catalytic cracking. revitalize and regenerate.

The decomposed carbon becomes CO and CO2, and these gases are taken out by separating the entrained catalyst in the cyclone 3'.
It is sent to a primary decomposition furnace 1 and a heating furnace 4, where combustible components such as CO are burned and used as part of the heat source.

The catalyst regenerated in the regeneration furnace 3 is sent to the secondary cracking furnace 2 at a temperature of about 550 to 8000 C via the control valve 10 and used for secondary catalytic cracking, and a portion is sent to the catalyst mixer 9. and used for primary catalytic cracking.

In addition, to compensate for the amount of catalyst lost in the system, the regeneration furnace 3 is replenished with new catalyst Cat.

Next, an example of catalytic cracking according to the present invention using China's Daqing crude oil as heavy oil and allophane as a catalyst will be shown.

Tables 1 and 2 show the characteristics of heavy oil and catalyst, respectively, and Table 3
Tables 4 and 5 show the properties of cracked oil, Table 6 shows the properties of cracked gas, and Table 7 shows the yield of cracked products.

From the above, the present invention has the following features.

■ Since a relatively low activity catalyst such as colloid or allophane is used, heavy oil can be efficiently catalytically cracked and lightened.

■ A catalyst with a catalyst ratio of approximately 0.05 to 0.5 is added to heavy oil, and primary catalytic cracking is performed for a short period of time at approximately 350 to 500°C, which prevents troubles such as pipe blockages caused by cracked residues. .

■ A catalyst is added to the heavy oil that has been subjected to the first catalytic cracking at a catalyst ratio of approximately 4 to 10, and the second stage is carried out at a temperature higher than the temperature during the first catalytic cracking and approximately 400 to 600°C. This secondary catalytic cracking is carried out in several stages by changing the temperature, so the gaseous decomposition products produced can be taken out without over-decomposition, and without producing tar or pitch as by-products. The decomposition residue can be decomposed into decomposed carbon without any problem, and the gaseous decomposition products become oil rich in kerosene and gas oil fractions and petrochemical raw material gas rich in olefins.

■ Catalysts with decomposed carbon attached can be easily regenerated.
Can be reused as a catalyst for repeated catalytic cracking.

■ By burning decomposed carbon, the combustion heat can be used as a heat source for catalytic cracking.

■ The heavy oil catalytic cracking equipment is divided into a primary cracking furnace, a secondary cracking furnace, and a secondary cracking furnace, and the interior of the secondary cracking furnace is divided into multiple chambers, so the temperature during catalytic cracking is controlled. can be changed in stages, catalytic cracking can be carried out efficiently, and heavy oil can be cracked into kerosene and gas oil fractions into oil-rich components and olefin-rich gases without producing tar or pitch as by-products. The decomposition residue can now be removed together with the catalyst.

■ As the heat required for catalytic cracking, the heat from burning the decomposition residue can also be used, resulting in energy savings.

■ The heat required for catalytic cracking of heavy oil is supplied by external heat in the first catalytic cracking, and by the sensible heat of the catalyst and sensible heat of steam in the second catalytic cracking, so it has good thermal efficiency. .

Further, in the second catalytic cracking, the decomposition temperature can be easily controlled.

Therefore, it is easy to set conditions for catalytic cracking that correspond to the characteristics of heavy oil and the light oil to be obtained by cracking.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of an embodiment of the heavy oil catalytic cracking apparatus according to the present invention, Fig. 2 is an explanatory diagram of a secondary cracking furnace, Fig. 2 a=f
are sections A, B, and C of the primary cracking furnace. It is a top view of D, E, and F. 1...Primary decomposition furnace, 2...Second decomposition furnace, 3...Regeneration furnace, 4...Heating furnace,
7... Rectification tower.

Claims (1)

[Scope of Claims] 1. After adding a catalyst with low activity to heavy oil and performing primary catalytic cracking at a temperature of about 350°C or higher, a catalyst with low activity is added again to increase the temperature to a temperature higher than the temperature during the first catalytic cracking. A method for catalytic cracking of heavy oil, which comprises performing secondary catalytic cracking while increasing the temperature stepwise in a temperature range of about 400° C. or higher, and removing gaseous cracking products. 2. The method for catalytic cracking of heavy oil according to claim 1, wherein the amount of catalyst added during the first catalytic cracking is such that the weight ratio of the catalyst to the heavy oil is about 0.05 to 0.5. 3. The method for catalytic cracking of heavy oil according to claim 1, wherein the amount of catalyst added during the second catalytic cracking is such that the weight ratio of the catalyst to the heavy oil is about 4 to 10. 4. The method for catalytic cracking of heavy oil according to claim 1, wherein the catalyst with low activity is colloid. 5. The method for catalytic cracking of heavy oil according to claim 1, wherein the catalyst with low activity is allophane. 6. The method for catalytic cracking of heavy oil according to claim 1, wherein the time for the first catalytic cracking is shorter than the time for the second catalytic cracking. 7 A primary cracking furnace consisting of an externally heated tubular structure, a secondary cracking furnace consisting of multiple compartmented rooms, a regeneration furnace that regenerates the spent catalyst, and a heating furnace that supplies high-temperature gas. It consists of a rectification column that separates the gas produced by decomposition into each fraction, a primary cracking furnace, a secondary cracking furnace, a secondary cracking furnace and a rectification tower, a secondary cracking furnace and a regeneration furnace. A heavy oil catalytic cracking apparatus characterized in that a furnace, a secondary cracking furnace and a heating furnace, a primary cracking furnace and a regeneration furnace, and a regeneration furnace and a heating furnace are connected to each other. 8. The heavy oil catalytic cracking apparatus according to claim 7, wherein the regeneration furnace has a fluidized bed structure in which the spent catalyst sent therein is fluidized by oxidizing gas. 9. The heavy oil catalytic cracking apparatus according to claim 7, wherein the heating furnace heats steam, nitrogen gas, hydrogen gas, or low molecular hydrocarbon gas to about 500 to 800°C. 10. The heavy oil catalytic cracking apparatus according to claim 7, wherein the secondary cracking furnace is provided with a perforated plate on each fluidized bed and a partition plate attached thereto. 11. The heavy oil catalytic cracking apparatus according to claim 7 or 10, wherein the secondary cracking furnace has a vertical structure.