CN2439330Y - Nozzle for atomizing feed of catalytic cracker - Google Patents

Abstract

A feed atomizing nozzle for a catalytic cracking unit in an oil refinery, consisting of a steam distribution hole 4, a steam distributor 5, a nozzle 10, etc., a nozzle 9 is provided at one end of an outer pipe 6, and a nozzle 10 is opened at the front end of the nozzle 9. There is a steam distributor 5 inside the tube 6, and there are steam distribution holes 4 on the steam distributor 5, which can form very uniform and fine liquid droplets, so as to fully contact with the catalyst. To increase the yield of light oil and reduce coke formation, the dense phase flow of the catalyst in the feed section of the riser can have a certain penetrating power, so that the spray jet can reach the middle of the riser, and the spray jet has a flat fan shape. The cross-section of the riser has good coverage, reducing back-mixing.

Description

Feed Atomization Nozzles for Catalytic Cracking Units

The utility model relates to a feed atomizing nozzle used for a catalytic cracking device in an oil refinery.

The task of the feed atomizing nozzle is to atomize the raw oil (heavy oil or residual oil or its mixture) and the re-refined oil of the catalytic cracking unit into fine droplets and spray them into the riser. At the temperature in the riser, the raw oil is vaporized and The cracking reaction occurs under the action of the catalyst, and then passes through the separation device to separate oil, gas and chemicals and enter the next process.

General feed atomization nozzles are composed of a mixing chamber and a spray section. In the mixing chamber, the atomized liquid meets the auxiliary atomized steam, shears and tears each other to form a two-phase flow mixed with each other, and then the two-phase flow is ejected through the nozzle of the ejection section. These nozzles basically use the flow stability theory of fluid dynamics to generate the largest possible vapor (gas)-liquid two-phase velocity difference in the mixing chamber to achieve the purpose of tearing and breaking the liquid, but the effect is often not It is very ideal, because the nozzle based on this principle cannot make reasonable use of the energy of atomized steam.

The early atomizing nozzles used at home and abroad are throat nozzles. The steam is directly sprayed into the liquid in the nozzle mixing chamber through a pipe, and the liquid is torn by shearing between the steam and the liquid. The nozzle is generally circular. The jet nozzle has poor atomization effect and cannot produce the flat fan-shaped spray jet required by the catalytic process. The average particle size of the atomization is mostly 80-100 μm, which is called the first generation feed nozzle.

After improvement, the second generation of feed nozzles has been produced, such as foreign target nozzles and domestic pre-film nozzles, as well as some other nozzles. The average atomization particle size of these nozzles is mostly 60-80μm. Since a huge vapor (gas)-liquid two-phase velocity difference is required to achieve the purpose of tearing and breaking the liquid, a very large steam (gas) inlet velocity must be used, and some even reach or exceed the speed of sound, and the energy consumption is relatively high. large and pulsating. If this speed cannot be reached, the nozzle will be difficult to work normally, the atomization effect will deteriorate sharply, and the operating flexibility will also be affected. These nozzles also have difficulty producing the flat fan-shaped spray jets required for catalytic processes.

After entering the 1990s, foreign oil companies intensified the research on feed nozzles. Mobil and Kellog began to cooperate in the development and research of new feed atomization nozzles in 1990, and developed a new type in 1994. Feed nozzle Atomax; UOP company developed a new type of nozzle OPtimix in 1995; these nozzles adopt their own different steam distribution structures and different nozzle forms in their mixing chambers, and the average particle size of the atomization is about 60 μm; Shell company In 1998, a new type of feed nozzle was developed and applied for the invention patent 98192423.3 in China. This nozzle is an external mixing feed nozzle. In this nozzle, steam and raw oil are mixed at the nozzle. The high speed of the steam drives the raw material oil to spray out from the nozzle; the above-mentioned nozzle can produce the flat fan-shaped spray jet required by the catalytic process, which is called the third-generation new atomizing feed nozzle.

The task of the present invention is to provide a kind of can form very uniform fine liquid droplet, thus fully contacts with catalyst, under the temperature in riser, feedstock oil is vaporized rapidly, makes cracking reaction carry out in gaseous state, can improve liquid hydrocarbon (gasoline) , diesel) production rate, reduce coke, so that the spray jet produced by the nozzle has a certain initial velocity, and the dense phase flow of the catalyst in the feed section of the riser can have a certain penetrating power, so that the spray jet can reach the middle of the riser , the spray jet has the shape of a flat fan, which has a good coverage of the riser section, reduces back-mixing, and the speed of the spray jet can be rapidly weakened, so as not to hit the wall of the riser opposite the nozzle, causing coking in the riser Feed atomization nozzles for catalytic cracking units.

Task of the present utility model is achieved in that:

The utility model comprises a steam inlet 1, a raw material oil inlet 2, a steam distribution hole 4, a steam distributor 5, an outer pipe 6, an annular space mixing chamber 7, a front end 8 of the mixing chamber, a nozzle 9, a nozzle 10, and one end of the outer pipe 6 There is a steam inlet 1, a raw material oil inlet 2 on the outer pipe 6, a nozzle 9 at the other end of the outer pipe 6, and a nozzle 10 at the front end of the nozzle 9, a steam distributor 5 inside the outer pipe 6, and the outer pipe 6 and the steam distributor There is an annular space mixing chamber 7 and a front end 8 of the mixing chamber between the 5, and steam distribution holes 4 are arranged on the steam distributor 5.

The utility model also adopts following implementation scheme:

The front end of the steam distributor 5 can be flat or spherical, and it constitutes the core tube of the atomizing nozzle, on which 1 to 30 rows of steam distribution holes 4 are evenly distributed.

The number of steam distribution holes 4 on the end of the steam distributor 5 can also be 1 to 30 circles.

On the entire circular pipe section of the steam distributor 5, there are 1 to 90 rows of steam distribution holes 4 evenly distributed along the circumference.

The steam distribution holes 4 may be uniformly distributed or dispersed along the length direction of the steam distributor 5 .

The diameter of the steam distribution hole 4 is 1-10 mm.

The ratio of the sum of the areas of the steam distribution holes 4 to the cross-sectional area of the core pipe of the steam distributor 5 is between 0.1 and 5.

The ratio of the diameter of the core pipe of the steam distributor 5 to the diameter of the outer pipe 6 is between 0.2 and 0.95.

The distance between the front of the steam distributor 5 and the nozzle 10 is between 0.1 and 20 times the diameter of the outer pipe 6 .

Several rows of steam distribution holes 4 at the front of the steam distributor 5 may correspond to the spouts 10 .

The nozzle 9 can be spherical or ellipsoidal.

There may be one spout 10 or more than one spout.

The shape of the spout 10 is long and narrow.

The divergence angle α of the nozzle 10 ranges from 10° to 180°, and the width δ of the nozzle 10 ranges from 2 to 20 mm.

The spouts 10 can be arranged in parallel or at an angle β, the range of β is between 0°-45°, and the distance B between the spouts 10 is between 3-50 mm.

The included angle ¢ between the bisector of the included angle between the nozzles 10 and the nozzle axis is between 0°～±60°.

The angle γ between the raw oil inlet 2 and the outer pipe 6 is between 10° and 90°.

The new nozzle provided by the utility model is an atomizing nozzle based on the principle of internal mixing atomization. There is a special gas distributor inside the mixing chamber. Through this gas distributor, the two phases of gas and liquid are in the mixing chamber Contacting and crushing in a better way can make reasonable use of the energy of the atomized steam. The steam does not have to have a high speed. When the steam passes through this specially designed distributor, a small pressure drop is generated, and it can be sprayed in the nozzle mixing chamber. A fine gas-liquid two-phase flow is formed inside, and the vapor phase exists in the liquid phase in the form of small bubbles; a fine gas-liquid two-phase flow is formed in the mixing chamber; there are one or several A narrow spout. Accelerated ejection through the nozzle, the gas-liquid two-phase produces a very large shear in a small area, making the droplet smaller; at the same time, due to the pressure relief after ejection from the nozzle, the volume of the bubbles in the vapor-liquid (gas-liquid) two-phase flow The rapid expansion (burst) further refines the droplet size. And this nozzle runs smoothly without pulsation.

Because the shape of the nozzle is flat, it can form a flat fan-shaped jet, which can cover the entire cross-section of the riser; at the same time, the catalyst can pass through the layered oil mist jet at one time, and will not form a thick layer on the surface of the catalyst due to the excessive travel through the oil mist area. The oil layer affects product selectivity. Therefore, the shape of the spray jet produced by this nozzle also meets the requirements of the catalytic cracking process.

Fig. 1 is the structural representation of the utility model;

Fig. 2 is a schematic structural view of the flat end face of the steam distributor 5 of the present invention;

Fig. 3 is a schematic structural view of the spherical end surface of the steam distributor 5 of the present invention;

Fig. 4 is an arrangement diagram of the steam distribution holes 4 of the present invention;

Fig. 5 is the arrangement diagram of 4 circles of steam distribution holes of the utility model;

Fig. 6 is a schematic diagram of the diffusion angle α of the nozzle 10 of the present invention;

Fig. 7 is the schematic diagram of the included angle ¢ of the spout 10 of the utility model;

Fig. 8 is a schematic diagram of the angle β, distance B, and width δ of the open nozzle 10 of the utility model.

Below in conjunction with accompanying drawing, the utility model is further described:

As shown in Figure 1, it includes steam inlet 1, raw oil inlet 2, steam distribution hole 4, steam distributor 5, outer pipe 6, annular space mixing chamber 7, mixing chamber front end 8, nozzle 9, nozzle 10, outer pipe 6 There is a steam inlet 1 at one end of the outer pipe 6, a raw material oil inlet 2 on the outer pipe 6, a nozzle 9 at the other end of the outer pipe 6, and a nozzle 10 at the front end of the nozzle 9, a steam distributor 5 inside the outer pipe 6, and the outer pipe 6 and There is an annular space mixing chamber 7 and a front end 8 of the mixing chamber between the steam distributors 5 , and the steam distribution holes 4 are arranged on the steam distributor 5 .

As shown in Figures 2 and 3, the steam distributor 5 has 1 to 30 circles (rows) of evenly distributed steam distribution holes 4 on the circular tube near the front. The front part can be flat or spherical. , which constitutes the core tube of the atomizing nozzle, with evenly distributed holes 4 in the flat or spherical head, and its front end can also be a hollow tube, on the entire circular tube section of the core tube type steam distributor 5 There are 1 to 90 rows of steam distribution holes 4 uniformly distributed along the circumference. These holes 4 can be uniformly or unevenly distributed along the direction of the core pipe of the steam distributor 5. The diameter of the holes 4 is 1 ~10mm, the ratio of the sum of the areas of all steam distribution holes 4 to the cross-sectional area of the core tube 3 of the steam distributor 5 is between 0.1 and 5, and the ratio of the diameter of the core tube 3 to the diameter of the outer tube 6 is between 0.2 and 0.95 The distance between the front of the steam distributor 5 and the spout 10 is between 0.1 and 20 times the diameter of the outer pipe 6, and the rows of steam distribution holes 4 at the front of the steam distributor 5 can also correspond to the spout 10.

The length of the nozzle or the length of the outer pipe is determined according to the needs of the site. The diameter of the outer pipe is related to the processing capacity of the nozzle. The design principle is that the flow rate of the raw material oil in the annular space is kept between 0.1-9 m/s.

As shown in Figures 6 to 8, the nozzle 9 and the nozzle 10 of the new atomizing feed nozzle can be spherical or ellipsoidal, and one or several long and narrow nozzles 10 are opened at its front end. When there are more than two spouts 10, each spout can be arranged in parallel or not, but at a certain angle β between each other, and the range of β is between 0° and 45°. The distance B between each spout 10 Then it depends on the needs, between 3～50mm; the variation range of the diffusion angle α of the spout 10 is between 10°～180°; the width δ of the spout 10 is between 2～20mm; the overall layout of each spout 10 and The nozzle axes can be distributed asymmetrically, that is, the angle between the bisector of the angle between the nozzles 10 and the nozzle axis is between 0°～±60°.

The distance between the front of the steam distributor 5 and the spout 10 is between 0.1 and 5 times the diameter of the outer pipe 6 . The diameter of the raw oil inlet 2 should make the flow velocity of the inner raw oil lower than 10 m/s, and the angle γ between the raw oil inlet 2 and the outer pipe 6 is between 10° and 90°.

The raw oil enters the annular space 7 and the front end 8 of the mixing chamber through the raw oil inlet 2, and flows toward the nozzle 9; the atomized steam enters the steam distributor 5 at the center through the steam inlet 1, and flows through the core tube steam A plurality of steam distribution holes 4 evenly distributed along the circumference of the distributor 5 spray outwards, spray into the raw material oil evenly, continuously and steadily, and mix with the raw material oil evenly. Since the holes 4 are evenly distributed on the circumference of the core pipe of the steam distributor 5 and are located at the positions where the raw oil must pass, when the raw oil flows through these positions, it is naturally broken by the ejected steam, and the steam ejected through the holes 4 The direction of movement is basically perpendicular to the direction of movement of the raw material oil, forming a large relative speed, cutting and breaking the raw material oil into small droplets, and due to the large number of action points and large contact area, the steam and the raw material oil are mixed in the mixing chamber 7 A fine vapor-liquid two-phase flow is formed inside, thus completing the first stage of atomization. After that, the fine vapor-liquid two-phase flow in the mixing chamber 7 moves to the nozzle 9, sprays out at a high speed through the nozzle 10, collides and shears violently with the surrounding medium, and atomizes the liquid into fine droplets. Complete the secondary atomization; at the same time, due to the sudden drop in pressure after being ejected from the nozzle 10, the volume of the bubbles in the even fine vapor-liquid two-phase flow suddenly explodes (expands), and the droplets are further broken into extremely small droplets, thereby Complete the entire atomization process.

Through the above process, it can be seen that due to the special design of the nozzle mixing chamber, the energy of the steam can be fully utilized, and a very uniform distribution of fine vapor-liquid mixture can be formed in the mixing chamber with a small pressure drop. Phase flow, so that the atomized droplets are fine and uniform, and there are no large droplets. And through the special design of the nozzle, the bubble atomization principle is used to further atomize the droplets, and at the same time, different shapes of spray jets can be formed, such as flat fan, magnesium, cone, etc.

FCC riser technology requires the ability to form a flat fan-shaped spray jet to cover the entire riser section, so that the feedstock oil and the catalyst can be in contact quickly and fully; at the same time, the atomized droplets are required to have a small average particle size and a narrow distribution , to improve product selectivity. The multi-layer semicircular nozzle proposed by the invention can generate the required flat fan-shaped spray jet, and the jet divergence angle can be adjusted as required, which can fully meet the requirements of the riser technology on the spray shape. Combining a special distributor with a specially designed nozzle can produce a spray jet with fine droplets and a shape that meets the requirements.

Through the test of the Malvern laser particle size tester, under the industrial scale flow rate (30 tons/hour), the nozzle proposed by the present invention can atomize the liquid with a viscosity of 5 centipoise into small droplets with a SMD particle size of 50 um. The SMD particle size of the atomized droplets of various nozzles currently in use in the industry is 60-80um.

The shape and position of the nozzle have certain requirements. To form the spray jet of the required shape, there is a corresponding shape of the nozzle. At the same time, the area of the nozzle has a certain matching relationship with the mixing chamber and the processing capacity to achieve the critical atomization state. Even if the processing capacity is the same, when the nozzle shape changes, the matching relationship between its area and processing capacity will also change. In order to ensure long-term operation, the surface of the nozzle and the nozzle should be treated with wear resistance.

When multiple rows of flat nozzles are used, they can be arranged in parallel or not. In the embodiment, there is a certain included angle between the two rows of nozzles. Two rows of parallel liquid mist are ejected from two adjacent nozzles arranged in parallel. Due to the small relative velocity between the two rows of liquid mist, the liquid mist is easy to converge into large droplets, thereby affecting the atomization effect. The advantage of having a certain angle between the nozzles is that the liquid mist ejected from two adjacent rows of nozzles moves forward at a certain angle apart from each other, and will not condense into large droplets due to convergence, and the droplets can obtain further mist. After a certain distance, after the droplets are well atomized, due to the outward movement of the two adjacent rows of liquid mist, the pressure between the two rows of liquid mist is relatively low, and under the relatively high pressure outside the two rows of liquid mist , each row of liquid mist is still combined into a row of liquid mist, which is a fan-shaped spray jet. The included angle between each row of nozzles is 0°-30°.

The divergence angle of the spray jet can be designed as required to adjust the coverage angle of the spray jet.

This atomizing feed nozzle has a good atomizing effect and is suitable for liquids with high viscosity, such as heavy oil or residual oil. This atomizing feed nozzle has good operating flexibility, and its processing capacity can vary between 70% and 130%. This nozzle is used in refinery catalytic cracking unit.

Claims (17)

1. Feed atomization nozzle of catalytic cracking unit, including steam inlet (1), raw oil inlet (2), steam distribution hole (4), steam distributor (5), outer pipe (6), annular space mixing chamber (7 ), the front end of the mixing chamber (8), the nozzle (9), the spout (10), one end of the outer pipe (6) has a steam inlet (1), and there is a raw material oil inlet (2) on the outer pipe (6), which is characterized in that : the other end of the outer pipe (6) has a nozzle (9), the front end of the nozzle (9) has a spout (10), the outer pipe (6) has a steam distributor (5), the outer pipe (6) and the steam distributor There is an annular space mixing chamber (7) and the front end (8) of the mixing chamber between (5), and steam distribution holes (4) are arranged on the steam distributor (5). 2. The feed atomizing nozzle of the catalytic cracking unit according to claim 1, characterized in that: the front end of the steam distributor (5) can be flat or spherical, and it constitutes the core pipe of the atomizing nozzle 1 to 30 rows of evenly distributed steam distribution holes (4) are opened on it. 3. The feed atomizing nozzle of a catalytic cracking unit according to claim 2, characterized in that the steam distribution holes (4) on the end of the steam distributor (5) can also be 1 to 30 circles. 4. The feed atomizing nozzle of the catalytic cracking unit according to claim 1, characterized in that: on the entire circular pipe section of the steam distributor (5), there are 1 to 90 rows of steam distribution holes (4) uniformly distributed along the circumference . 5. The feed atomizing nozzle of a catalytic cracking unit according to claim 4, characterized in that: the steam distribution holes (4) can be distributed uniformly or scattered along the length direction of the steam distributor (5). 6. The feed atomizing nozzle of a catalytic cracking unit according to claim 1, characterized in that the diameter of the steam distribution hole (4) is 1-10mm. 7. The feed atomizing nozzle of the catalytic cracking unit according to claim 1, characterized in that: the ratio of the sum of the areas of the steam distribution holes (4) to the cross-sectional area of the core pipe of the steam distributor (5) is between 0.1 and 5 . 8. The feed atomizing nozzle of a catalytic cracking unit according to claim 1, characterized in that the ratio of the diameter of the core tube of the steam distributor (5) to the diameter of the outer tube (6) is between 0.2 and 0.95. 9. The feed atomizing nozzle of catalytic cracking unit according to claim 1, characterized in that: the distance between the front part of the steam distributor (5) and the nozzle (10) is 0.1-20 of the diameter of the outer pipe (6) between times. 10. The feed atomizing nozzle of a catalytic cracking unit according to claim 2, characterized in that the rows of steam distribution holes (4) at the front of the steam distributor (5) can correspond to the nozzles (10). 11. The feed atomizing nozzle of a catalytic cracking unit according to claim 1, characterized in that: the nozzle (9) can be spherical or ellipsoidal. 12. The feed atomizing nozzle of a catalytic cracking unit according to claim 1, characterized in that: there may be one nozzle (10) or more than one nozzle. 13. The feed atomizing nozzle of a catalytic cracking unit according to claim 1, characterized in that: the shape of the nozzle (10) is long and narrow. 14. The feed atomizing nozzle of the catalytic cracking unit according to claim 1, characterized in that: the range of the diffusion angle α of the nozzle (10) is 10°～180°, and the width δ of the nozzle (10) is between 2～20mm between. 15. The feed atomizing nozzle of the catalytic cracking unit according to claim 1, characterized in that: each nozzle (10) can be arranged in parallel or at an angle β, and the range of β is between 0°～45°, each The distance B between the spouts (10) is between 3 and 50 mm. 16. The feed atomizing nozzle of the catalytic cracking unit according to claim 1, characterized in that: the angle ¢ between the bisector of the angle between the nozzles (10) and the axis of the nozzle is between 0°～±60°. 17. The feed atomizing nozzle of the catalytic cracking unit according to claim 1, characterized in that: the angle γ between the raw oil inlet (2) and the outer pipe (6) is between 10° and 90°.

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