JPH0643585B2 - End-to-end FCC stripping device with baffle skirt with stripping gas inlet - Google Patents

Description

FIELD OF THE INVENTION The present invention relates generally to hydrocarbon conversion processes and apparatus. More particularly, the present invention relates to an apparatus and method for stripping hydrocarbons occluded from spent catalyst in a fluidized bed cracking process.

[Prior arts and problems to be solved by the invention]

A fluidized bed catalytic cracking (commonly referred to as FCC) process was developed in the 1940s to increase the yield of naphthalene boiling range hydrocarbons obtained from crude oil. The fluidized bed cracking process is now widely used commercially in petroleum refineries to produce light boiling hydrocarbons from heavy feedstocks such as atmospheric distillation bottoms or vacuum crudes. This process has been used to lower the average molecular weight of various petroleum derived feeds, resulting in economically valuable gas oils from heavy fractions. The feedstock for the FCC process is usually petroleum derivative feedstock, but liquids obtained from tar sands, oil shale or coal liquefaction can also be used for the FCC process. Nowadays,
Various FCC processes can also be used to crack heavy oil and distillate residue. Although the FCC process is often used for distillate bottoms conversion, the term FCC herein also applies to heavy oil cracking.

FCC Devices of Various Designs May 15, 1972, in The Oli & Gas Journal
It is described in the article on page 102 of the Japanese issue and page 65 of October 8, 1973.

Another example of an FCC process is US Pat. No. 4,364,905
No. 4,051,013 (by Strother); 3,894,932 (by Owen); and 4,419,221 (by Castagons Jr.), and other FCC patents discussed herein. You can find out by reference.

In the most common design of FCC processes, the feedstock in the reaction zone is contacted with a finely divided solid catalyst that causes a fluidized medium to airflow through the reaction zone. The fluidized medium includes steam, light oil, and a vaporized raw material component which is converted by being brought into contact with a catalyst. The catalyst is described as being in a fluid state, because the catalyst behaves as a fluid when moving by the fluid medium. When the catalyst particles come into contact with the feedstock, the catalyst is covered with a hydrocarbon-like substance called coke. Coke is a by-product of the cracking reaction and contains carbon, hydrogen, and other substances in the feed, such as sulfur. The coke blocks the decomposition site of the catalyst and deactivates the catalyst. Such a catalyst is usually called a waste catalyst. Therefore, after passing through the reaction zone, the spent catalyst is transferred to the regeneration zone, where the coke is burned and separated from the catalyst. The oxygen-containing gas, which is typically air, is mixed with a catalyst in a regenerator at a sufficiently high temperature to oxidize the adhering coke into carbon monoxide and carbon dioxide. Oxidation removes coke and reactivates the catalyst to remove it from the regenerator and return it to the reactor, thereby completing the continuous operation of the FCC unit.

Ballistic trajectory of large amounts of hydrocarbon vapors in contact with the catalyst in the reaction zone
Separation from solid particles by ballistic and / or centrifugation methods. However, the catalyst particles used in the FCC process have a large surface area because they have a very large number of pores. As a result, the catalyst material occludes hydrocarbons in and on the pores. And while the amount of hydrocarbons retained by individual catalyst particles is extremely small, the amount of catalysts commonly used in modern FCC processes is large and the circulation rate is very fast, so that hydrocarbons can react. The catalyst is occluded and removed from the zone.

Therefore, it is common to separate or strip the stored hydrocarbons from the spent catalyst before passing it through the regeneration zone. Removal of stored hydrocarbons from spent catalyst is both process and economically important. First, the occluded hydrocarbons entering the regenerator increase the carbon combustion load, which causes the regenerator temperature to rise too high. The product hydrocarbons can also be recovered by stripping the hydrocarbons from the catalyst. Avoiding unnecessary combustion of hydrocarbons is especially important when processing heavy (relatively high molecular weight) feedstocks. This is because the treatment of these feedstocks increases the amount of coke deposited on the catalyst during the reaction (compared to the treatment of lighter feedstocks) and increases the combustion load in the regeneration zone. Higher combustion loads also lead to higher temperatures, which can catalyze catalysts or violate the metallurgical design limits of regenerators.

The most common method of stripping the catalyst is to pass a stripping gas (usually using steam) counter-currently to the downward flowing catalyst stream. Although the efficiency of steam stripping operations varies, in order to strip hydrocarbon gas from the catalyst that removes the hydrocarbons that are entrained in the catalyst and stored in the catalyst, simply contact the catalyst with the stripping catalyst. Good. This contact is made according to U.S. Pat.
This can be done with a simple open container as shown in 481,103.

Previously, to increase the efficiency of catalyst stripping,
A series of baffles were provided on the stripping device and cascaded from side to side as the catalyst fell through the device. Horizontal movement of the catalyst increases contact between the catalyst and the stripping medium, and increased contact between the catalyst and stripping medium results in greater separation of hydrocarbons from the catalyst.

It has been known since 1944 to use angled guides to augment the catalyst and catalyst of the stripping medium, as shown in US Pat. No. 2,440,625. With such a device, the catalyst is provided with a complex flow path by a series of baffles installed at various heights. Contact between the catalyst and the gas is increased by this structure, and the main cross-section of the stripping device is free of vertical hollow passages. An example of a similar stripping device for FCC devices is US Pat.
2,440,620, 2,612,438, 3,894,932, 4,414,100 and 4,364,905. These references include a stripper tank and a frustum that directs the catalyst inward toward one of a series of centrally located conical or frustrated baffles that diverges the catalyst onto the outer baffles. / A representative stripper is shown having a series of baffles with a conical shaped cross section. The stripping medium enters below the lower baffles in series and continues to rise from the bottom of one baffle to the bottom of the next baffle. Variants of baffles include U.S. Pat.
A skirt added near the trailing edge of the baffle as shown in 994,659, or multiple linear at various baffle heights as shown in FIG. 3 of US Pat. No. 4,500,423. There are some that use the baffle cross section. A variation of introducing stripping media is shown in U.S. Pat. No. 2,541,801, where a large amount of flowing gas is introduced from a number of discrete locations.

In the example of a gas-solid contactor disclosed in U.S. Pat. No. 2,460,151 (Thinclair), an upflow reactant or vapor can be collected at the bottom of a series of troughs and exhausted from the sides of the trough through a series of louvers. . However, this device does not function like the stripping device described above because there is a checkboard-like vertical passageway through all trough levels. In said US Pat. No. 2,460,151 there is no particular importance to the design or equipment of the trough.

In order to achieve good stripping of the catalyst, increased product yield and associated good operation of the regenerator, a relatively large amount of stripping medium has heretofore been required. For steam, the most common stripping medium, the average steam requirement in the industry is well above 1.5 kg per 1000 kg of catalyst for catalyst stripping. The cost of adding this fluid medium is significant, in the case of steam, the costs include capital costs and utility costs associated with water removal from the steam supply and downstream separation equipment. Therefore, any steam savings required to achieve good catalyst stripping are of substantial economic benefit to the FCC process.

It has now been discovered that good catalytic stripping can be achieved with less than half of the stripping media previously used by utilizing conventional FCC stripping methods and equipment. These results can be achieved by modifying the grid of the stopper according to the invention.

[Means for Solving the Problems]

The present invention is an FCC stripper that redistributes the fluidized medium at each grid level to increase penetration of the fluidized medium across a downward flowing catalyst stream. At the bottom of each grid, carefully sized and spaced holes are used to inject a flowing medium across a descending column of catalyst. By injecting the fluidizing medium, the contact between the fluidizing medium and the catalyst particles is further improved, so that the fluidizing medium becomes more efficient in removing hydrocarbons from the catalyst. The improved stripping efficiency reduces the amount of stripping gas required to remove a certain level of hydrocarbons, or the addition of a certain level of stripping media improves hydrocarbon removal. Those skilled in the art will appreciate that the former saves utilities and facilities,
It can be seen that the latter increases the product yield and also improves the regeneration operation.

In one embodiment, the invention is an invention of a stripping device for an FCC unit that removes stored hydrocarbons from a particulate catalyst by contacting a stripping gas.
The stripping device has a vertically extending vessel and has a cross-section open to the flow of catalyst from the top in and out from the bottom. 2 in the same container
Baffle system with one or more grids. The grid has horizontal projections so that the catalyst moves downward from side to side in the container while moving downward. The horizontal projection surface of each grid is smaller than the cross section of the container. The horizontal projections of the grid cover most of the cross section. Stripping gas is added below the bottom of the grid and is contacted with the catalyst in an ascending manner. A gas collection space created by the bottom surface of each grid and one or more sidewalls collects the upward flow and stripping gas. There is at least one skirt on the side wall of each grid,
This isolates the gas collection space from the downward flow catalyst. Each skirt has two or more sets of gas inlets or holes, which are examples of evenly spaced horizontal holes. Each set of holes is sized to produce a jet of gas and jets and distributes stripping gas from the gas collection space into the downward flow of the catalyst. The holes in each set differ in size, so that the jet length is different and the stripping gas is spread over the entire width of the downward flow of the catalyst.

To explain the FCC process in more detail, FCC
The feedstock to the device is typically oil such as light oil or vacuum gas oil. Another petroleum derived feed for FCC units is a mixture of heavy hydrocarbons such as diesel boiling range hydrocarbons or distillation bottoms. The feedstock preferably has a boiling point above about 232 ° C, and more preferably above about 288 ° C, as measured by the appropriate ASTM test method. It is becoming more and more common to use FCC type equipment, RCC (residual crude oil cracking) equipment, or residual oil cracking equipment for processing heavy feedstocks such as atmospheric distillate residue.

The FCC process equipment consists of a reaction zone and a catalyst regeneration zone. In the reaction zone, the feed stream is contacted with the finely divided fluid catalyst at high temperature and medium pressure. The contact between the feedstock and the catalyst takes place in a relatively large fluidized bed. However, the reaction zone in modern FCC units usually consists of a vertical conduit or riser as the main reaction section, and the discharge from the conduit enters a large volume process vessel, which is a separation vessel. The residence time of the catalyst and hydrocarbons in the riser required for the decomposition reaction to be almost complete is only a few seconds. The flowing vapor / catalyst stream leaving the riser enters the solid / vapor separator in the separation tank from the riser, or
Alternatively, it is possible to directly enter the separation tank without going through an intermediate separation device. In the absence of an intermediate separator, much of the catalyst flow falls off the flowing vapor / catalyst stream as it enters the separation vessel from the riser. One or more additional solids /
The vapor separator is most often a cyclone separator, but is usually in a large separation tank or at the top. The reaction products are separated from some of the catalyst carried by the vapor stream by the cycloan or cyclones. The steam is then exhausted from the cyclone and separation zone. The spent catalyst falls toward the bottom of the separation tank. The stripper may have a reaction zone (or separation tank) at the bottom, or the spent catalyst can be passed from the reaction riser or separation tank to the stripper. After passing through the stripping device, the catalyst is transferred to a separate regeneration zone.

The rate of feed conversion in the reaction zone is controlled by adjusting temperature, catalyst activity, and the amount of catalyst retained in the reaction zone (ie catalyst / oil ratio).
The most common way to control the temperature of the reaction zone is by controlling the rate of circulation of the catalyst from the regeneration zone to the reaction zone, which simultaneously changes the catalyst / oil ratio. That is, when it is desired to increase the conversion rate in the reaction zone, the catalyst flow rate from the regeneration zone to the reaction zone is increased. By doing so, even if the same amount of oil is charged, more catalyst will be present in the reaction zone. In normal operation, the temperature of the regeneration zone is considerably higher than the temperature of the reaction zone. Therefore, increasing the circulation rate of the catalyst from the regeneration zone to the reaction zone increases the temperature of the reaction zone.

The chemical composition and structure of the feedstock used in the FCC unit affects the amount of coke deposited on the catalyst in the reaction zone. Usually, the molecular weight of the raw material, Conradson carbon (Conrads
The higher the on carbon), heptane insolubles, and carbon / hydrogen ratio, the higher the coke concentration on the spent catalyst. Also, a high concentration of bound nitrogen, such as found in shale-derived oil, results in more coke on the spent catalyst. Heavy feedstock, eg deasphalted oil, or atmospheric residual oil from a feedstock fractionator (usually,
Processing of heavy feedstocks (such as distillate residuals) increases some or all of these factors. As used herein, the term "waste catalyst" is intended to refer to the catalyst used in the reaction zone which is transferred to the regeneration zone to remove adhering coke. The term does not mean that the catalytic activity of the catalyst particles is completely lost. The term "waste catalyst" shall have the same meaning as "spent catalyst".

Due to the widespread use of vertical annular conduits, the reaction zone, commonly referred to as the "rise tube", is maintained at elevated temperatures, typically around 42
Above 7 ° C, it is preferred to keep the reaction zone in the cracking conditions at a temperature of about 482 ° C to about 593 ° C and a pressure of 69 to 517 kPa (ga), although the pressure is preferably less than about 276 kpa (ga). The catalyst / oil ratio can be increased up to 20: 1 based on the weight of catalyst and feed hydrocarbons entering the bottom of the riser, but is preferably about 4: 1 to 10: 1. Hydrogen is usually not added to the riser, but hydrogenation is known in the art. Optionally steam can be passed through the riser. The average residence time of the catalyst in the riser is preferably less than about 5 seconds. The type of catalyst used in this process can be selected from many commercially available catalysts, with zeolite-based catalysts being preferred. Moreover, it can be used if an older type of amorphous catalyst is required. Further information regarding the operation of the FCC reaction zone can be obtained from U.S. Pat. Nos. 4,541,922, 4,541,922 and the Seki patent.

In some FCC processes, the catalyst is continuously circulated from the reaction zone to the regeneration zone and then back to the reaction zone. The catalyst thus acts as a carrier that carries heat from zone to zone and at the same time provides the required catalytic activity. The catalyst withdrawn from the regeneration zone is called the "regenerated" catalyst. As mentioned above, the catalyst charged to the regeneration zone is contacted with an oxygen-containing gas, such as air or oxygen-enriched air, which causes the coke to burn. As a result, the temperature of the catalyst rises and a large amount of hot gas is generated from the regeneration zone as a gas stream called the flue gas stream. The regeneration zone normally operates at about 593 ° C to about 788 ° C. FC
Further information on C reaction and regeneration zone operation can be found in US Pat.
431,749, 4,419,221 (quoted above) and 4,220,623
Obtained from the issue.

The catalyst regeneration zone is preferably about 34 to about 517 kPa (ga).
Operate at the pressure of. About 0.2 of spent catalyst is charged in the regeneration zone
To about 5 wt% coke. Coke preferentially contains carbon and contains from about 5 to about 15 weight percent hydrogen, and sulfur and other elements. Oxidation of coke normally produces carbon dioxide, carbon monoxide and water as combustion products. As is well known to those skilled in the art, there is some structure in the regeneration zone and regeneration is done in one or more steps. Further step variants are possible because the fluidized catalyst can be regenerated in the regeneration zone as a dilute or concentrated phase. The term "diluted phase" shall mean that the catalyst / gas mixture has a density of less than 320 kg / m, likewise the term "concentrated phase" means that the catalyst gas mixture is
It shall have a density of 320 kg / m or more. Typical dilute phase operating conditions are catalyst / gas mixture densities around
Often 16 to about 160 kg / m.

〔Example〕

The present invention will be further described with reference to the drawings, which are intended to illustrate particular embodiments of the invention and are not intended to limit the general scope of the invention described in the claims.

FIG. 1 illustrates one type of reaction zone that can be used to carry out the FCC process. The reaction zone consists of a riser 5, a separation phase 1 and a stripper 2 (or stripping tank 2). The stripping tank 2 is attached to the bottom of the separation tank 1 and the riser pipe 5 passes through the center of the stripper to enter the separation phase. The catalyst and hydrocarbons rise while flowing in the riser pipe 5, but reference numeral 7 indicates the inside of the riser pipe 5. The location where the catalyst and hydrocarbon vapors are introduced into the riser 5 is not shown. The fluid mixture flows out of the riser 5 and most of the catalyst is a cyclone 13.
Is separated from the gas stream at. This catalyst falls to the lower part of the separation tank 1 above the stripper part. Reference number 10 indicates the height of the catalyst in the lower part. Steam and some catalyst exit the top of cyclone 13 and enter cyclone 11 with the steam from the stripper. Fine powder, that is, fine catalyst particles, are entrained in the vapor flow, separated by the cyclone 11, and fall downward. The vapor stream of hydrocarbons leaves the cyclone 11 via conduit 12. The hydrocarbon product in conduit 12 flows to a suitable product recovery unit (not shown), which typically consists of a fractionation column, commonly referred to as the main column, and another separation unit commonly referred to as the gas concentrator. Other than the two cyclones shown in FIG. 1, the vapor / solid separation device inside the separation tank 1 has various configurations.

The waste catalyst enters the stripping tank 2 from the lower region of the separation tank 1 downward. The stripping vessel 2 is oriented in a substantially vertical direction so that a weight flow passes the catalyst into the stripper vessel. Due to its elongated shape, a vertical distance is created and the catalyst remains in the stripping vessel for the desired time. The outer wall of the riser 5 and the inside of the vessel 2 create an annular space through which the catalyst is flowed with reference numeral 8. The annular space open to this catalyst stream is more commonly referred to as the cross sectional area. The catalyst is moved from the bottom of the stripper 2 by means of a conduit 4 whereby it is withdrawn and sent to a regeneration zone (not shown) for coke removal.

FIG. 1 shows a series of baffles located in the annular space. The baffle is made up of grid members 18, 20 and 14 and each grid is fitted with a skirt 19, 21 and 15. The term "grid" is an ordinary term in industry and is therefore referred to herein as "grid" or "grid member". The terms "grid" or "grid member" are related to the means by which the catalyst is cascaded left to right as it flows down in the stripper under the influence of weight. The grid may be one of a variety of geometric shapes, but various shapes of grids are shown in this figure. For example, the grid 14 extends completely horizontally around the stripper and is attached to the inner wall around the entire circumference of the stripper.
The grid 20 extends completely around the stripper and is attached to the outer wall of the riser along the entire perimeter of the riser. The grids 18, 20 and 14 are all frustrated / conical in shape and extend downward in an annular space. The three grid members depicted in Figure 1 have skirts 19, 21 and 15 to form the baffle.
Moreover, it is attached to the lowest edge of the grid and extends downward. The skirt is shaped to fit the curvature of the bottom edge of the grid with which it is attached. For example, each skirt in FIGS. 1 and 2 has a cylindrical shape. As shown in FIG. 3, each grid projects horizontally across the annular space.

FIG. 3 shows the stripper 2 and a concentric rising pipe 5 on the outer plate of the stripper 2. Reference numeral 7 is a riser pipe 5.
Shows the inside of. The cross section of FIG. 3 is drawn so that the skirt 15 can be seen. The dotted line shows the position of the skirt 24. The diameter of the skirt 24 is slightly smaller than the diameter of the skirt 24, including the other skirts on the grid 5 associated with the riser tube 5, and the other skirts on the grid associated with the outer wall are noted and raised. The assembly consisting of the grid member and the skirt associated with the pipe 5 and the riser pipe 5 can be pulled upwards.

Obviously, the horizontal projection area of each grid should be much smaller so as not to cover the entire annulus where the catalyst flows. The sum of all the horizontal projections of each grid is usually 40 to 80 percent of the cross section. Collectively, the horizontal projections of the grid substantially cover the cross-sectional area. The grid augments the catalyst and stripping gas catalyst as it substantially covers the annular cross-sectional area. The placement of the grid allows the catalyst to move from end to end, eliminating the unimpeded vertical passage of the catalyst and stripping gas. Recognizing the usual stripper construction in which the inner grids 20 and 27 are attached to the riser pipe prior to inserting the riser pipe 5 into the stripper, the grid arrangement is designed to substantially cover the passage. In order to insert the riser pipe and the inner grid later, the outer diameter of the inner grid is made slightly smaller than the inner diameter of the outer grid. This creates an annular open space between the skirts 15 and 24, as shown in FIG. 3, between the grids. Third
The figure usually shows a 2.5 to 5.0 mm gap exaggerated. Since the stripping tank usually has a total diameter of more than 1.5 meters, the direct flow area for this gap is quite large.

1 and 2 depict the space below the grid members when no catalyst is filled. This space is named 9, 22, 23 and 29 and has grid 20,
27, 14 and 26. These spaces are gas collection spaces and collect the rising stripping gas in the manner described below. The gas collection spaces 23 and 29 are formed by the lower surface of the grid and a pair of side surfaces having a skirt on one side and a container wall on the other side. The gas collection spaces 9 and 22 are formed by the lower surface of the grid and a pair of side surfaces formed by the outside of the container wall and the rising pipe 5.

Grid member 14 may be used as an example of a portion of a grid group that includes grids 18 and 26. We name these outer grids. It extends 360 degrees around the stripper and is tightly mounted inside the wall of the stripper tank so that gas and catalyst cannot pass between the edges of the grid member 14 and the stripper inner wall. Reference numeral 28 in FIGS. 2 and 4 designates a mounting point.
Since FIG. 4 is a cross-sectional view, the installation is continuous, that is, 360 degrees around the stripping vessel. The grid member 27 can be used as an example of a part of the grid group including the grid 20. It attaches to the outside of the riser pipe 5 and extends 360 degrees around the riser pipe 5. Skirts 19, 21, 15, 24, and 25 are shown in FIGS. 1 and 2. Although the total number of grids shown in Figures 1 and 2 was chosen arbitrarily, it should be noted that less or more grid members are actually needed.

Stripping gas is added to the stripping tank from below the lowest grid. Steam is the most frequently used stripping gas. After the stripping gas contacts the catalyst, it is mixed with the hydrocarbon vapor stripped from the catalyst. The term "stripping gas" refers to the gas injected in the riser and the mixture of hydrocarbons and the gas injected found high up in the stripper. The catalyst is shown in the left-hand part of the annular space 8 in FIG. 2 and is also present in the right-hand part, but is not shown in the drawing. Arrows are drawn in the right-hand portion of FIG. 2 to indicate the direction of stripping gas flow outside the holes in the skirt having a series of holes and through the catalyst. FIG. 4 is a vertical sectional view showing the grid member 26 and the skirt 25 with the ring 17 omitted. The skirt 26 has stripping gas distribution holes and is designated by reference numerals 30, 31, and 32 in FIG.
Each skirt shown in FIGS. 1 and 2 has a number of holes, which are omitted for simplicity of drawing. You can see that the catalyst moves down from one end to the other as it falls under the force of gravity. The gas collection spaces 19, 22, 23, and 9 are relatively depleted of catalyst because the catalyst cannot flow upward. The angle at which the catalyst falls from the bottom of the skirt, that is, the angle at which the substance remains as a lump is called the resting angle. The slip angle is a related concept and can be defined as the minimum angle at which a substance starts to move from a stationary state on an inclined surface. Each grid member is shown to have a descending slope greater than the slip angle. This tilt causes the catalyst to
It is possible to prevent accumulation on the top of the grid in (inclined bank).

The gas distribution holes distribute the stripping gas evenly so that the gas is in substantial contact with all of the catalyst adjacent each grid and skirt. It therefore contacts all the catalyst in the stripper. Referring again to FIG. 2, the stripping gas enters the distribution pipe 17 via the pipeline 3. Pipeline 3 is re-illustrated in FIGS. Distribution pipe
17 is 36 around the stripper under the grid members
It forms a ring over 0 degrees. The distribution pipe penetrates to evenly distribute the steam into the annular space 29,
It is below the grid 26 and is attached by a skirt 25. However, it is not necessary to use a ring-shaped gas distribution means. Any device that distributes steam into the space under the lowest grid and skirt can be used. Stripping gas (steam) flows through holes in the skirt 25 (not shown) and then through the catalyst as shown by the arrow on the right hand side of FIG. The steam and hydrocarbons stripped from the catalyst adjacent the grid 26 and skirt 25 flow into the space 22 under the grid member 27 and surrounded by the skirt 24. The gas is then redistributed through the holes in skirt 24, through the catalyst adjacent skirt 24 and into space 23 below grid member 14. Then Gas has a skirt 15
Through the holes in and through the rest of the stripper.
The hydrocarbon vapor leaving the stripping gas section is
Through the catalyst at the bottom of the tank into the free space of tank 1 and leaving tank 1 via cyclone 11 with the hydrocarbon product of the FCC unit.

5 and 6 show the means for diverging the catalyst within the cylindrical stripping zone. FIG. 6 is a plan sectional view taken along the sectional view arrow of FIG. In this case, the grid member is a flat plate and has no segments to flow the catalyst down. The plate mounts the catalyst at an angle greater than the slip angle. Reference numeral 70 designates the cylindrical skin of the stripper. Skirts 75 and 73 are attached to grid members 76 and 74. In this embodiment of the invention, the skirt is not curved, as can be seen from the skirt 75 in FIG. 6, but is rectangular. The dotted line in FIG. 6 shows the skirt 73. The stripping gas is supplied by a pipeline 71 to a distributor 72 where it is distributed and flows evenly through holes (not shown) in the skirt 73. In this embodiment of the invention, the distributor 72 need not be ring-shaped, but a straight pipe is sufficient. The gas passes through the catalyst adjacent to the skirt 73 and enters the space 78 under the grid 76,
Then, it passes through a hole (not shown) in the skirt 75. Similarly, the gas passes through the rest of the stripper before entering a separation vessel similar to vessel 1 in FIG.

7 and 8 show another type of catalyst spreading means in a cylindrical container. The outer grid member, such as grid 57, is the same as the outer grid member, such as outer grid 14 shown in FIGS. As shown in FIGS. 1 and 2, the outer grid member of FIG. 7 extends horizontally 360 degrees around the stripping tank 50. The skirt shown in FIG. 7, eg skirt 58, is the same as the skirt shown in FIGS. 1 and 2 attached to the outer grid.
The stripping gas is also carried by the pipeline 51 to the stripper and is distributed by the distribution ring 52 as in the case of FIG. 2 (pipeline 3 and distributor 17). A central grid member, indicated by reference numerals 56 and 60, is located within stripper 50. Each central grid member is a hollow cone inside the base, and a skirt attached to its bottom edge
Has a skirt like 55. Each skirt is a vertical hollow cylinder with a short height. Legs (not shown) extending from each central grid member to the outer grid members support the central grid. FIG. 8 shows the stripper's cylindrical skin 50 and skirt 59.
The dotted line in FIG. 8 shows the position of the skirt 58 attached to the grid 57. Gas from the distributor 52 passes through holes (not shown) in the skirt 53 and through the catalyst (not shown) adjacent the skirt 53 and the grid 54 into the space below the grid 56, which is designated by reference numeral 61. To do. The gas then passes through holes in the skirt 55 (not shown) and ascends through the skirt 55 and a catalyst (not shown) adjacent the grid 56 into the space below the grid 57 indicated by reference numeral 63. From there, the gas passes through holes (not shown) in the skirt 58 and into the space 62 under the grid 60, which is surrounded by the skirt 59.

The height of the skirt and the number and size of the gas distribution holes in the skirt have many factors, such as the stripper geometry.
It depends on the catalyst throughput, operating pressure, stripping gas flow rate, etc. A person skilled in the art, if not carrying out the invention,
The stripping gas flow rate for a particular device can be determined. The determination of this flow rate relies primarily on experience with stripping equipment as there is no exact calculation method. The required stripping gas flow rate in the absence of practice of the invention is the starting point for determining the parameters of the invention. Half of this flow velocity is regarded as the design flow velocity, and the size of the hole is determined by this design flow velocity. Those skilled in the chemical industry and hydrocarbon processing technology can calculate the pressure drop as a gas passes through an orifice or bed of particles. The placement and size of the holes are determined by trial and error. The total pressure drop across the stripper is then calculated. If this pressure drop is unsatisfactory, select different pore characteristics and repeat the process. The height of the skirt depends mainly on the characteristics of the holes, but should not be less than 10 cm.

FIG. 4 shows the dimensions of a typical grid member and skirt. The skirt is 30.48 cm high and has three rows of holes with three rows, each row being horizontal and extending 360 degrees along the skirt. The more rows of holes, the more completely the stripping gas is distributed and the more effective the invention is. However, the present invention is effective if there are two rows of holes. The vertical distance between each row of holes is 7.5 cm. There are 24 holes in each row, opened 15 degrees, so all holes are evenly spaced. These holes vary in size because they change the length of the jet produced by each row of holes. As an example of gas distribution holes with different dimensions, the diameter of each hole in the row with holes 30 is 1.27 cm, the diameter of the holes in the row with holes 31 is 1.9 cm, and the hole in the row with holes 32. Has a diameter of 2.5
It is 4 cm. This change in diameter improves the catalyst coverage area because the stripping gas covers more catalyst flow as the gas jet length varies. Referring again to FIGS. 1 and 2, the lowermost group of arrows on the right hand side of FIG. 2 are marked with dashes corresponding to the holes in FIG. The gas passing through the 1.27 cm hole flows in a horizontal direction for a short distance before going upward. The gas from the large hole, hole 31, flows horizontally further as shown by arrow 31. The gas from the largest hole flows the longest horizontal distance as indicated by the arrow 32. The horizontal distance of the gas flow associated with a hole depends on the size of the hole, if all other parameters are the same.

In addition to improving hydrocarbon yields by burning with coke to remove hydrocarbons, the present invention allows for a small amount of stripping steam. For example, for processes that require about 1.5 kg of steam for 1000 kg of catalyst without the invention, the present invention provides satisfactory results with 0.7 kg of steam for 1000 kg of catalyst. It turned out by experiment.

As an example of stripper size, 200,000bpd (132.
A relatively small FCC unit with a raw material of 48 m / hr) has a stripper with a nominal diameter of 198.12 cm and a nominal diameter of 76.2 cm.
With riser. Therefore, the width of the radial annular space is
It is 60.96 cm. Referring to FIG. 2, the radial annular space below the grid 14 has a width of 22.86 cm and the inner grid has a width of 35.56 cm. And it is necessary to use different widths. This is because it is desirable to maintain a horizontal area so that the catalyst moves end to end and flows relatively constantly. This can be understood by referring to FIGS. 2 and 3, which shows that in FIGS. 2 and 3 the inside of the catalyst is first surrounded by the members with the reference numbers 15 and 5. This is because it can be seen to flow through the annulus and then through the outer annulus surrounded by the members with reference numbers 2 and 74.

It is desirable to increase the size of the holes in the skirt above the stripper to accommodate the stripped hydrocarbons. The size of the pores varies from the smallest of the smallest to the largest of the pores. For example, to accommodate hydrocarbons passing through the holes in skirt 21, the skirt of FIG.
The holes in 21 are larger than the holes in the skirt 25 of FIG. It can be seen that substantially no hydrocarbons pass through the holes in the skirt 25, and the amount of hydrocarbons passing through the holes increases as the height above the steam distributor increases.

[Brief description of drawings]

FIG. 1 shows a schematic view of the FCC process reaction and a front view of a stripping tank having a lower portion as a stripping tank or a stripping section. The inside of the tank is shown by a dotted line. Two partial cross sections are shown as cutouts. FIG. 2 is a partial vertical sectional view of the stripping portion of FIG. FIG. 3 is a plan view of the stripper of FIG. 2 taken at section 3-3. FIG. 4 is an enlarged view of one of the grid members of FIG. 5 and 7 are side cross-sectional views of stripping devices having alternate baffle configurations. 6 and 8 are sectional views corresponding to the stripping apparatus of FIGS. 5 and 7. The symbols in the figure are as follows. 1 ... Separation tank, 2 ... Stripping tank 3, 4, 12 ... Conduit, 5 ... Ascending pipe 7 ... Inside of ascending pipe, 8 ... Annular space 10 ... Height of catalyst, 11, 13 ...... Cyclone 17 …… Distribution pipes, 14,18,20,27 …… Grid 15,19,21,24 …… Skirts corresponding to the above grids 9,22,23,29 …… Space formed by the grid 30,31,32 …… Skirt 15 hole, 50 …… Stripping tank 51 …… Pipeline, 52 …… Distribution ring 56,60 …… Grid 55,59 …… Skirts corresponding to each of the above grids 61 …… Space under grid 56, space under grid 60 63 Space under grid 57 70 Cylindrical skin of stripper 71 Pipeline, 72 Distributor 74,76 Grid 73,75 …… Skirts corresponding to each of the above grids

Claims (4)

[Claims] 1. An F designed to remove stored hydrocarbons from a fluidized particle catalyst by continuously circulating steam by contacting with stripping gas.
In a CC stripping device: (a) elongated shape, predominantly vertical alignment, cross-section open to descending catalyst flow, apex communicating with source [5] of catalyst particles, and catalyst particles A vessel [2] having a lowest part in communication with the means [5] for withdrawing; [b] a frust / conical shape and an outer diameter portion fixed to the inside of the container at the initial locus. An outer grid (18) extending inwardly and downwardly from the initial position towards the inner diameter portion, and at least partially having a conical shape and at least substantially the outer grid. It consists of at least one inner grid (20) having an outer diameter part equal to the size of the inner diameter of (18), so that both the inner grid (20) and the outer grid (18) have a cross section of Substantially covered, The outer grid [18] extending inwardly and upwardly toward the means [5] for supporting the inner grid from its outer diameter portion, and all said inner and outer grids. A set of baffles [18] located in the tank [2], in which the catalyst flows are vertically juxtaposed alternately and a flow of the catalyst flows down the tank [2] to the left and right. 20 and 14]; (c) means [3,17] for feeding stripping gas to the tank [2] below the lowest grid and stripping gas from the highest end of the tank [2] Means [11, 12]; (d) In the outer grid skirt [19] which is cylindrical and has the highest portion fixed to the inner diameter portion of the outer grid [18], the outer grid skirt [19] ,
The outer grid skirt [1], wherein the outer grid [18] and the vessel [2] form an outer gas collection space having an open bottom for receiving stripping gas.
9]; (e) In the inner grid skirt [21] which is cylindrical and has a highest portion fixed to each outer diameter portion of the inner grid [20], the inner grid skirt [2
1], said inner grid [20] and said means [5] for supporting said grid are inner gas collection space [9]
The inner grid skirt [21]; and (f) in at least two sets of gas injection holes defined by each skirt [19, 21], each set of holes having a uniform hole size. , With uniform hole spacing and common vertical height, with each hole in each set having a horizontal centerline protrusion and a diameter sufficient to obtain a jet of gas reaching the flow path [8] for catalyst flow. , And one of the at least two sets of holes has a different size hole than the other set of holes, so that a gas jet extending from the at least two different sets of holes is The FCC stripping device, characterized in that at least two sets of gas injection holes [30, 31] having different injection lengths are combined. 2. Each grid skirt defines at least three sets of holes [30, 31 and 32], and the maximum hole diameter dimension is the length of the flow path [8] through which the gas injection is for catalyst flow. Device according to claim 1, characterized in that it is sized to reach at least 2/3. 3. FCC for removing occluded hydrocarbons from a particulate catalyst by contacting with a stripping gas.
In the stripping device of the device, said stripping device comprises: (a) an elongated shape, a predominantly vertical arrangement, a cross section open to the descending catalyst stream, the highest end communicating with the source of catalyst particles. Section and a vessel having a lowest end in communication with the means for withdrawing catalyst particles [70]; (b) located downwardly and inwardly from opposite vertical surfaces of the vessel In at least two grids (76, 74), each grid extends inwardly by more than about half of the cross-section, so that both grids substantially cover the cross-section and both grids At least two grids [76,74] vertically aligned to provide a flow path from end to end while the catalyst flows down the vessel; (c) stripping gas Both of the above Means (71) for feeding the tank below the bottom of the lid; (d) in the vertical skirts (75, 73) at the bottom of each grid (76, 74), the grid, the skirt and the Said vertical skirts [75,73] forming a gas collection space [78] under each grid for receiving stripping gas; (e) at least in each skirt [75,73] In both sets of gas injection holes [30, 31], each set of holes has a uniform hole size, uniform hole spacing and common vertical height, and each set of holes has a horizontal centerline projection. And having a limited size, which results in a jet of gas extending into the flow path, where the holes in the lowest set of holes in each skirt have a maximum diameter and thereby a longest injection length. And at least two sets of gas injection holes [30, 31], Wherein the combining, the FCC stripper. 4. At least three sets of holes [30, 31 and 32] are defined by each skirt [75, 73], and the gas injection of the largest holes is at least 2 of said flow path distances for catalyst flow. Device according to claim 3, characterized in that it also reaches / 3.