External heat extractor and its applications, catalytic cracking unit and its method

Abstract

The present application relates to a kind of external heat exchanger and its application, a kind of catalytic cracking device and its method.The external heat exchanger includes: cylinder, the inside of the cylinder is provided with N vertical heat exchange tube bundle, N is natural number and N≥10, and double loop tube distributor, the double loop tube distributor is arranged below the vertical heat exchange tube bundle and is annularly arranged around the central axis of the cylinder;Wherein, when the double loop tube distributor injects booster wind, by the structure of the double loop tube distributor is arranged, so that the booster wind that is injected through the double loop tube distributor forms demarcation line in the cylinder, for the inside of the cylinder is divided into center area and annular area.The external heat exchanger provided by the present application not only has better gas distribution uniformity and heat extraction performance, but also can ensure the smooth flow of particle and the stable operation of external heat exchanger in the greater particle circulation flow rate range, so that external heat exchanger has high heat transfer efficiency and operation stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of petroleum chemical technology, in particular to an external heat exchanger and application thereof, a catalytic cracking device containing the external heat exchanger and a method thereof. BACKGROUND

[0002] In the process of catalytic cracking reaction and catalyst regeneration, maintaining the heat balance of the system is one of the most important process requirements, that is, the heat required by the endothermic cracking reaction process is provided by the exothermic coke burning regeneration process. With the heavy and poor quality of catalytic cracking raw materials, the amount of coke generated by the device increases, causing the heat released by the coke burning regeneration to increase continuously, which has exceeded the heat required by the reaction system. Therefore, a heat extraction device needs to be installed in the regeneration system to achieve the heat balance of the system.

[0003] Due to the flexible, adaptive and more reliable heat extraction load adjustment, the fluidized bed heat exchanger (hereinafter referred to as external heat exchanger) arranged outside the regenerator has been more widely used. There are many types of external heat exchangers used in industry, among which the dense phase external heat exchanger with low gas velocity is the most widely used, mainly because it has the advantages of high heat extraction efficiency, less fluidization gas consumption, flexible load adjustment, etc.

[0004] Compared with the internal heat exchanger built into the dense phase bed layer of the regenerator, the external heat exchanger can more flexibly adjust the load of heat extraction. Since the properties of raw materials and product demand of industrial catalytic cracking devices are often changing, such external heat exchanger with more easily adjustable load has been more widely used in refineries.

[0005] Generally, there are three methods to adjust the load of the external heat exchanger: (a) adjusting the superficial gas velocity, aiming to change the heat transfer coefficient between the heat extraction tube and the bed material; (b) adjusting the bed material level, aiming to increase the heat transfer area; (c) adjusting the particle circulation flow rate, changing the heat transfer temperature difference by changing the residence time of hot catalyst particles. Compared with methods (a) and (b), method (c) is more frequently used in industrial devices on site because of its convenient operation.

[0006] In order to achieve efficient heat transfer between the bed material in the fluidized bed and the wall surface of the whole heat transfer tube, the most important thing is to promote the frequent update of particles on the wall surface of the heat transfer tube, and avoid the phenomena of particle accumulation (loss of fluidization) and emptying (long-time static cavities) on the wall surface of the heat transfer tube for a long time, that is, the whole bed layer must maintain good fluidization quality. Due to the existence of the heat transfer tube bundle, the best way for the external heat exchanger to improve the fluidization quality and heat transfer is to use a gas distributor with more uniform gas distribution. On the other hand, due to the requirement of heat extraction load adjustment, the particle circulation flow rate of many external heat exchangers often changes frequently within a large range.

[0007] Considering the high particle mass flow rate in the external heat exchanger, only two types of gas distributors, i.e. loop distributor and dendritic distributor, can be used in the external heat exchanger. At present, the gas distributor used in most external heat exchangers is a single loop distributor. However, the loop distributor has the disadvantages of single structure, uneven gas distribution, large dead zone, etc. For the external heat exchanger with large diameter, these problems are more prominent.

[0008] There are also some external heat exchangers using dendritic gas distributors. Although the dendritic gas distributor has better gas distribution uniformity than the loop distributor, the dendritic distributor has a complex structure, and the minimum flow area ratio at the installation position is often small. When the particle circulation flow rate in the external heat exchanger is large, the phenomenon of "liquid flooding" similar to that in the gas-liquid packed tower is likely to occur. This phenomenon is also called "solid flooding" in the study of fluidization. "Solid flooding" is caused by the local particle downward velocity being greater than the bubble upward velocity. The occurrence of "solid flooding" hinders the smooth downward flow of catalyst particles, affects the gas-solid two-phase contact effect, and further causes problems such as local dead bed, unstable operation, large decrease in heat removal load, etc. in the external heat exchanger. In severe cases, it may even cause unplanned shutdown of the device. SUMMARY

[0009] The purpose of the present application is to overcome the above technical problems, and to provide an external heat exchanger and its application, a catalytic cracking device and its method, which has high heat transfer efficiency and heat removal capacity, thereby ensuring the long-term safe and stable operation of the catalytic cracking device containing the external heat exchanger.

[0010] In order to achieve the above-mentioned purpose, the first aspect of the present application provides an external heat exchanger, comprising: a cylinder, the inside of the cylinder is provided with N vertical heat exchange tube bundles, N is a natural number and N≥10, and a double loop distributor, the double loop distributor is arranged below the vertical heat exchange tube bundles and is arranged annularly around the central axis of the cylinder.

[0011] When the double loop distributor injects the pressurized air, the structure of the double loop distributor is adjusted so that the pressurized air injected through the double loop distributor forms a demarcation line in the cylinder, which is used to divide the inside of the cylinder into a central region and an annular region.

[0012] Preferably, the double loop distributor is selected from small loop distributors and large loop distributors with different heights, and the small loop distributors and the large loop distributors are respectively provided with first nozzles and second nozzles for downward injection.

[0013] Preferably, the vertical distance between the small loop distributor and the large loop distributor is 0.3-0.8 m.

[0014] Preferably, the cross-sectional area S of the central zone and the cross-sectional area S' of the annular zone have a ratio of 1:1-3.

[0015] The second aspect of the present application provides an application of the external heat exchanger provided by the first aspect in a catalytic cracking process or a coal chemical process.

[0016] The third aspect of the present application provides a catalytic cracking device, which comprises a reactor, a regenerator and the external heat exchanger provided by the first aspect connected in sequence.

[0017] The reactor is used to contact and react an oil product and a catalyst to obtain an oil gas product and spent catalyst; the regenerator is used to regenerate the spent catalyst to obtain regenerated catalyst; and the external heat exchanger is used to exchange heat between the regenerated catalyst and a heat exchange medium in a uniform distribution atmosphere of the pressurized air to obtain the regenerated catalyst after heat exchange.

[0018] The fourth aspect of the present application provides a catalytic cracking method, which is performed in the catalytic cracking device provided by the third aspect; and the method comprises the following steps:

[0019] (1) contacting and reacting an oil product and a catalyst to obtain an oil gas product and spent catalyst;

[0020] (2) regenerating the spent catalyst to obtain regenerated catalyst;

[0021] (3) exchanging heat between the regenerated catalyst and a heat exchange medium in a uniform distribution atmosphere of the pressurized air to obtain the regenerated catalyst after heat exchange.

[0022] Preferably, in step (3), the superficial gas velocity of the pressurized air is ≥0.2 m / s, preferably 0.2-0.8 m / s; and the particle circulation flow rate of the regenerated catalyst is ≤100 kg / (m 2 ·s), preferably 0-100 kg / (m 2 ·s).

[0023] Compared with the prior art, the present application has the following advantages:

[0024] (1) The external heat exchanger provided by the present application has better gas distribution uniformity and heat extraction performance by arranging a double-ring pipe distributor below the vertical heat exchange pipe bundle, and can ensure the stable flow of particles and the stable operation of the external heat exchanger in a larger particle circulation flow rate range, so that the external heat exchanger has high heat transfer efficiency and operation stability; especially by adjusting the vertical distance between the small ring pipe distributor and the large ring pipe distributor in the double-ring pipe distributor and the cross-sectional area ratio of the central zone and the annular zone, the gas distribution uniformity and the heat transfer coefficient of the pressurized air are further improved, and the operation stability is improved.

[0025] (2) The external heat exchanger provided by the present invention is used in a catalytic cracking unit. By improving the heat transfer efficiency and heat extraction capacity of the external heat exchanger, the long-term safe and stable operation of the catalytic cracking unit is ensured. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of an external heat exchanger provided by the present invention, wherein the arrow indicates the distribution direction of the pressurized air, and the dashed line indicates the central axis of the external heat exchanger;

[0027] Figure 2 This is a schematic diagram of another external heat exchanger provided by the present invention, wherein the arrow indicates the distribution direction of the pressurized air, and the dashed line indicates the central axis of the external heat exchanger;

[0028] Figure 3(a) is a schematic diagram of the central region and the annular region of an external heat exchanger provided by the present invention;

[0029] Figure 3(b) is a top view of a double-loop pipe distributor in an external heat exchanger provided by the present invention;

[0030] Figure 4 This is a schematic diagram of the structure of the first nozzle provided by the present invention, which is disposed on a small ring tube distributor;

[0031] Figure 5(a) is a top view of a single-loop pipe distributor;

[0032] Figure 5(b) is a top view of the dendritic distributor;

[0033] Figure 5(c) is a top view schematic diagram of a dual-ring pipe distributor provided by the present invention.

[0034] Explanation of reference numerals in the attached figures

[0035] Detailed Implementation

[0036] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0037] In this invention, unless otherwise specified, the terms "first" and "second" do not indicate a sequence or limit the specific steps or materials used; they are merely used to distinguish between different materials or steps. For example, "first nozzle" and "second nozzle" are simply used to indicate that they are not the same step.

[0038] In the present application, the top of the container refers to the 0-10% position from top to bottom of the container, the upper part of the container refers to the 10-40% position from top to bottom of the container, the middle part of the container refers to the 40-60% position from top to bottom of the container, the lower part of the container refers to the 60-90% position from top to bottom of the container, and the bottom of the container refers to the 90-100% position from top to bottom of the container.

[0039] The present application provides a structure diagram of an external heat exchanger. Figure 1 As shown in FIG. 3, the external heat exchanger comprises a cylinder body 1, an inside of the cylinder body 1 is provided with N vertical heat exchange pipe bundles 2, N is a natural number and N≥10, and a double-ring pipe distributor is arranged below the vertical heat exchange pipe bundles 2 and annularly around the central axis of the cylinder body 1. Figure 1

[0040] When the double-ring pipe distributor injects the pressurized air, the pressurized air sprayed through the double-ring pipe distributor forms a demarcation line 14 in the cylinder body 1, which is used to divide the inside of the cylinder body into a central area and an annular area, by adjusting the structural arrangement of the double-ring pipe distributor.

[0041] In the present application, the demarcation line is essentially non-existent, and only the limit formed by the pressurized air sprayed through the double-ring pipe distributor serves as the demarcation line, without special circumstances.

[0042] In the present application, the pressurized air refers to compressed air, without special circumstances.

[0043] In the present application, the number of the vertical heat exchange pipe bundles is adjusted according to specific working conditions, which is not described herein.

[0044] According to the present application, preferably, the vertical heat exchange pipe bundles are used to exchange heat between the particles to be exchanged and the heat exchange medium to obtain the particles after heat exchange, and the double-ring pipe distributor is used to uniformly distribute the pressurized air in the central area and the annular area.

[0045] In the present application, the heat exchange medium refers to saturated water, and in the heat exchange process, after the heat exchange medium in the vertical heat exchange pipe bundle absorbs heat from the particles to be exchanged outside the vertical heat exchange pipe bundle, part of the saturated water is converted into saturated steam, and the temperature of the particles to be exchanged is reduced, i.e., the particles after heat exchange are obtained.

[0046] In one specific embodiment of the present application, as shown in FIG. 2, the vertical heat exchange pipe bundles 2 are uniformly distributed at the top of the cylinder body 1. Figure 1

[0047] ​​According to the present application, as shown in Figure 1 Preferably, the double-loop distributors are selected from small-loop distributors 3 and large-loop distributors 4 with different heights, and the small-loop distributors 3 and large-loop distributors 4 are respectively provided with first nozzles and second nozzles for downward spraying.

[0048] In the present application, without special circumstances, the double-loop distributors selected from small-loop distributors and large-loop distributors with different heights refer to the height of the outer heat extractor cylinder. The double-loop distributors can be divided into small-loop distributors arranged on the top and large-loop distributors arranged on the bottom, or large-loop distributors arranged on the top and small-loop distributors arranged on the bottom.

[0049] In the present application, in order to avoid the gas jet of the small-loop distributors arranged on the top from washing the large-loop distributors arranged on the bottom, the large-loop distributors arranged on the bottom should not belong to the jet influence area of the small-loop distributors arranged on the top. Preferably, the vertical distance between the small-loop distributors and the large-loop distributors is ≥0.3m, preferably 0.3-0.8m, for example, 0.3m, 0.4m, 0.5m, 0.6m, 0.7m, 0.8m, and any value in the range composed of any two numerical values. In the present application, the specific vertical distance depends on the size of the nozzles of the small-loop distributors arranged on the top and the size of the jet speed. When the size of the nozzles and the jet speed are small, the vertical distance is small, and vice versa.

[0050] In the present application, without special circumstances, the center diameter of the small-loop distributors is < the center diameter of the large-loop distributors, and the outer diameter of the small-loop distributors is < the inner diameter of the large-loop distributors; wherein the center diameter of the small-loop distributors is the average of the inner diameter and the outer diameter of the small-loop distributors; similarly, the center diameter of the large-loop distributors is the average of the inner diameter and the outer diameter of the large-loop distributors.

[0051] In some embodiments of the present application, preferably, the center diameter of the small-loop distributors < the diameter of the center area < the center diameter of the large-loop distributors < the inner diameter of the cylinder.

[0052] In some embodiments of the present application, preferably, the ratio of the center diameter of the small-loop distributors to the diameter of the center area is 0.4-0.8:1, for example, 0.4:1, 0.5:1, 0.6:1, 0.65:1, 0.7:1, 0.8:1, and any value in the range composed of any two numerical values, preferably 0.6-0.7:1. The purpose is to inject the pressurized air flowing out of the first nozzles of the small-loop distributors into the center area as evenly as possible, so as to realize the uniform contact of the pressurized air with the particles after heat exchange in this area.

[0053] In some embodiments of the present application, preferably, the ratio of the average of the inner diameter of the cylinder and the diameter of the central zone to the central diameter of the large annular tube distributor is 1:0.9-1.1, preferably 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1, and any value in the range between any two of the values, preferably 1:0.95-1.05. Again, the purpose of this is to inject the pressurized air from the second nozzle of the large annular tube distributor into the annular zone as evenly as possible, again in order to achieve uniform contact between the pressurized air and the heat-exchanged particles in this zone.

[0054] In some embodiments of the present application, preferably, the shortest distance between the vertical heat exchange tube bundle 2 and the annular tube distributor disposed thereon is ≥0.2m, preferably 0.2-1m.

[0055] In some embodiments of the present application, preferably, the ratio of the cross-sectional area S of the central zone to the cross-sectional area S' of the annular zone is 1:1-3, for example, 1:1, 1:2, 1:3, and any value in the range between any two of the values.

[0056] In the present application, the flow rate of the pressurized air into the double annular tube distributor is proportional to the cross-sectional area of the central zone / annular zone. Preferably, the flow rate Q of the pressurized air into the small annular tube distributor satisfies Q=a×S, where a>0, and the cross-sectional area S of the central zone; the flow rate Q' of the pressurized air into the large annular tube distributor satisfies Q'=a'×S', where a'>0, and the cross-sectional area S' of the annular zone.

[0057] In some embodiments of the present application, preferably, the flow rate Q of the pressurized air into the small annular tube distributor satisfies Q=a×S, where a is selected from 0.1-0.5, and the cross-sectional area S of the central zone; the flow rate Q' of the pressurized air into the large annular tube distributor satisfies Q'=a'×S', where a' is selected from 0.1-0.5, and the cross-sectional area S' of the annular zone.

[0058] In some embodiments of the present application, preferably, the flow rate Q of the pressurized air into the small annular tube distributor, the flow rate Q' of the pressurized air into the large annular tube distributor, the cross-sectional area S of the central zone, and the cross-sectional area S' of the annular zone satisfy: .

[0059] In the present application, the flow rate of the pressurized air into the double annular tube distributor is proportional to the number of first nozzles / second nozzles. Preferably, the flow rate Q of the pressurized air into the small annular tube distributor satisfies Q=b×N, where b>0, and the number N of first nozzles; the flow rate Q' of the pressurized air into the large annular tube distributor satisfies Q'=b'×N', where b'>0, and the number N' of second nozzles.

[0060] In the present application, without special circumstances, along the height of the cylinder, the small ring pipe distributor can be arranged above or below; similarly, the large ring pipe distributor can be arranged above or below.

[0061] In some embodiments of the present application, preferably, as shown in Figure 1 When the small ring pipe distributor 3 is arranged above the large ring pipe distributor 4, the small ring pipe distributor 3 is provided with the first nozzles inclined inwardly, and the large ring pipe distributor 4 is provided with the second nozzles inclined inwardly and outwardly. In this way, under the premise of ensuring the high supercharged air distribution uniformity and high heat transfer efficiency, the erosion and wear of the small ring pipe distributor arranged below are avoided.

[0062] In a specific embodiment of the present application, when the small ring pipe distributor is arranged above the large ring pipe distributor, a circle of the first nozzles inclined inwardly and downwardly is uniformly arranged on the circumference of the small ring pipe distributor; a circle of the second nozzles inclined inwardly and downwardly and a circle of the second nozzles inclined outwardly and downwardly are uniformly arranged on the circumference of the large ring pipe distributor; wherein the second nozzles inclined inwardly and the second nozzles inclined outwardly are arranged alternately.

[0063] In some embodiments of the present application, preferably, as shown in Figure 2 When the large ring pipe distributor 4 is arranged above the small ring pipe distributor 3, the large ring pipe distributor 4 is provided with the second nozzles inclined outwardly, and the small ring pipe distributor 3 is provided with the first nozzles inclined inwardly and outwardly. In this way, under the premise of ensuring the high supercharged air distribution uniformity and high heat transfer efficiency, the erosion and wear of the large ring pipe distributor arranged below are avoided.

[0064] In another specific embodiment of the present application, when the large ring pipe distributor is arranged above the small ring pipe distributor, a circle of the second nozzles inclined outwardly and downwardly is uniformly arranged on the circumference of the large ring pipe distributor; a circle of the first nozzles inclined inwardly and downwardly and a circle of the first nozzles inclined outwardly and downwardly are uniformly arranged on the circumference of the small ring pipe distributor; wherein the first nozzles inclined inwardly and the first nozzles inclined outwardly are arranged alternately.

[0065] In the present application, without special circumstances, inclined inwardly means that the extension line of the nozzle axis points to the central axis of the cylinder; inclined outwardly means that the extension line of the nozzle axis points to the inner wall of the cylinder.

[0066] In some embodiments of the present application, preferably, the inclination angle α of the first nozzles is 20-50°, and the inclination angle α' of the second nozzles is 20-50°. Wherein the inclination angle refers to the angle between the nozzle axis and the plumb line.

[0067] In some embodiments of the present application, preferably, the first nozzle and the second nozzle respectively penetrate the small ring pipe distributor and the large ring pipe distributor.

[0068] In the present application, in order to ensure the uniformity of air distribution, preferably, the first nozzle and the second nozzle are each independently a double-diameter nozzle; further preferably, along the flow direction of the pressurized air, the first nozzle and the second nozzle each independently comprise: a small-diameter section, an optional diameter-expanding section and a large-diameter section.

[0069] In the present application, in order to ensure the uniformity of air distribution and inhibit particle abrasion, the air velocity of the pressurized air through the small-diameter section is 30-70 m / s, and the air velocity of the pressurized air through the large-diameter section is 10-30 m / s.

[0070] In the present application, without special circumstances, the first nozzle and the second nozzle arranged on the double-ring pipe distributor are uniformly distributed on the cross section of the external heat exchanger, avoiding the occurrence of a large area without nozzles.

[0071] In some embodiments of the present application, preferably, the inner diameter ratio of the small-diameter section and the large-diameter section is 1:1.3-2.5, for example, 1:1.3, 1:1.5, 1:1.8, 1:2, 1:2.5, and any value in the range composed of any two numerical values; the length ratio of the small-diameter section and the large-diameter section is 1:2-10, for example, 1:2, 1:4, 1:5, 1:6, 1:8, 1:10, and any value in the range composed of any two numerical values.

[0072] In some embodiments of the present application, preferably, the taper angle of the diameter-expanding section is >90°, preferably 120-180°, for example, 120°, 150°. Wherein, the taper angle of the diameter-expanding section refers to the included angle between the diameter-expanding section and the large-diameter section.

[0073] A structure diagram of a first nozzle provided on a small ring pipe distributor according to the present application is shown in Figure 4 As shown in Figure 4 It can be seen that the first nozzle 9 penetrates the small ring pipe distributor, and the first nozzle 9 is a double-diameter nozzle; along the flow direction of the pressurized air, the first nozzle 9 comprises: a small-diameter section 10, a diameter-expanding section 11 and a large-diameter section 12.

[0074] According to the present application, preferably, as shown in Figure 1 The external heat exchanger further comprises: a particle feeding pipe 5 and a gas discharging pipe 6 arranged at the top of the cylinder body 1, and a particle discharging pipe 8 arranged at the bottom of the cylinder body 1.

[0075] According to the present application, preferably, as shown in Figure 1As shown, the external heat exchanger further comprises: 2 gas feed pipes 7 arranged on the side wall of the cylinder 1, and the gas feed pipes 7 are connected with the double-loop pipe distributors. That is, the gas feed pipes 7 are connected with the small-loop pipe distributor 3 and the large-loop pipe distributor 4 respectively.

[0076] The second aspect of the present application provides an application of the external heat exchanger provided in the first aspect in a catalytic cracking process or a coal chemical process.

[0077] The third aspect of the present application provides a catalytic cracking device, which comprises: a reactor, a regenerator and the external heat exchanger provided in the first aspect connected in sequence.

[0078] The reactor is used for contacting and reacting an oil product and a catalyst to obtain an oil gas product and spent catalyst; the regenerator is used for regenerating the spent catalyst to obtain regenerated catalyst; and the external heat exchanger is used for heat exchanging the regenerated catalyst and a heat exchange medium in a uniform distribution atmosphere of pressurized air to obtain heat-exchanged regenerated catalyst.

[0079] According to the present application, preferably, the external heat exchanger is further connected with the regenerator for regulating the temperature of the regenerator.

[0080] The fourth aspect of the present application provides a catalytic cracking method, which is performed in the catalytic cracking device provided in the third aspect; and the method comprises the following steps:

[0081] (1) contacting and reacting an oil product and a catalyst to obtain an oil gas product and spent catalyst;

[0082] (2) regenerating the spent catalyst to obtain regenerated catalyst;

[0083] (3) heat exchanging the regenerated catalyst and a heat exchange medium in a uniform distribution atmosphere of pressurized air to obtain heat-exchanged regenerated catalyst.

[0084] In some embodiments of the present application, preferably, the heat-exchanged regenerated catalyst obtained in step (3) is returned to step (2) for regulating the temperature of the regeneration.

[0085] In some embodiments of the present application, preferably, in step (3), the superficial gas velocity of the pressurized air is ≥0.2 m / s, preferably 0.2-0.8 m / s; and the particle circulation flow rate of the regenerated catalyst is ≤100 kg / (m 2 ·s), preferably 0-100 kg / (m 2 ·s).

[0086] In this invention, unless otherwise specified, the apparent gas velocity parameter refers to the ratio of the total volumetric flow rate under booster conditions to the cross-sectional area of ​​the external heat exchanger; the particle circulation rate parameter refers to the mass of particles (e.g., regenerator) flowing through a unit cross-sectional area of ​​the external heat exchanger per unit time.

[0087] According to a particularly preferred embodiment of the present invention, an external heat exchanger includes: a cylindrical body, wherein N vertical heat exchange tube bundles are disposed inside the cylindrical body, where N is a natural number and N≥10; and a double-ring tube distributor, wherein the double-ring tube distributor is disposed below the vertical heat exchange tube bundles and is arranged in a ring around the central axis of the cylindrical body.

[0088] When the double-ring pipe distributor injects pressurized air, by adjusting the structural settings of the double-ring pipe distributor, the pressurized air injected by the double-ring pipe distributor forms a dividing line in the cylinder, which is used to divide the interior of the cylinder into a central area and an annular area.

[0089] The dual-ring pipe distributor is selected from small-ring pipe distributors and large-ring pipe distributors with different heights, and the small-ring pipe distributor and the large-ring pipe distributor are respectively provided with a first nozzle and a second nozzle for downward spraying.

[0090] The vertical distance between the small ring pipe distributor and the large ring pipe distributor is 0.3-0.8m.

[0091] The ratio of the center diameter of the small ring pipe distributor to the diameter of the central area is 0.4-0.8:1; the ratio of the average value of the inner diameter of the cylinder and the diameter of the central area to the center diameter of the large ring pipe distributor is 1:0.9-1.1.

[0092] Preferably, the ratio of the cross-sectional area S of the central region to the cross-sectional area S' of the annular region is 1:1-3.

[0093] The present invention will be described in detail below through embodiments.

[0094] Example 1

[0095] A schematic diagram of an external heat exchanger provided by this invention is shown below. Figure 1 As shown, by Figure 1 It can be seen that the external heat exchanger includes: a cylinder 1, a particle feed pipe 5 and a gas discharge pipe 6 set at the top of the cylinder 1, two gas feed pipes set on the side wall of the cylinder 1, a particle discharge pipe 8 set at the bottom of the cylinder 1, and 12 vertical heat exchange tube bundles 2 (outer diameter of 40mm), a small ring tube distributor 3 and a large ring tube distributor 4 arranged sequentially from top to bottom in the cylinder 1;

[0096] The shortest distance between the vertical heat exchange tube bundle 2 and the small ring pipe distributor 3 arranged above is greater than or equal to 0.2 m;

[0097] The vertical distance between the small ring pipe distributor 3 and the large ring pipe distributor 4 is 0.3-0.8 m;

[0098] The ratio of the center diameter of the small ring pipe distributor 3 to the diameter of the center area is 0.4-0.8:1; the ratio of the average value of the inner diameter of the cylinder 1 and the diameter of the center area to the center diameter of the large ring pipe distributor 4 is 1:0.9-1.1;

[0099] The circumference of the small ring pipe distributor 3 is uniformly provided with a circle of first nozzles 9 which spray downward and are inclined inward, and the circumference of the large ring pipe distributor 4 is uniformly provided with a circle of second nozzles 13 which spray downward and are inclined inward, and a circle of second nozzles 13 which spray downward and are inclined outward, and the second nozzles which are inclined inward and outward are arranged alternately;

[0100] The inclination angle of the first nozzles is 20-50°, and the inclination angle of the second nozzles is 20-50°;

[0101] The first nozzles and the second nozzles are each independently a double-diameter nozzle; along the flow direction of the pressurized air, the first nozzles and the second nozzles each include a small-diameter section, an expanding-diameter section and a large-diameter section, wherein the ratio of the inner diameters of the small-diameter section and the large-diameter section is 1:1.3-2.5, and the ratio of the lengths is 1:2-10; the taper angle of the expanding-diameter section is 120-180°;

[0102] The ratio of the cross-sectional area S of the center area to the cross-sectional area S' of the annular area is 1:3; the ratio of the pressurized air flow Q into the small ring pipe distributor to the pressurized air flow Q' into the large ring pipe distributor is 1:3; the air speed of the pressurized air through the small-diameter section of the first nozzles and the second nozzles is 35-60 m / s, and the air speed of the pressurized air through the large-diameter section of the first nozzles and the second nozzles is 13-22 m / s.

[0103] Example 2

[0104] Another structure diagram of the external heat exchanger provided by the application is shown in the figure, and different from example 1, the large ring pipe distributor 4 is arranged above, and the small ring pipe distributor 3 is arranged below; Figure 2

[0105] The circumference of the large ring pipe distributor 4 is uniformly provided with a circle of second nozzles which spray downward and are inclined outward; the circumference of the small ring pipe distributor 3 is uniformly provided with a circle of first nozzles which spray downward and are inclined inward, and a circle of first nozzles which spray downward and are inclined outward, and the first nozzles which are inclined inward and outward are arranged alternately;

[0106] ​The cross-sectional area S of the central area and the cross-sectional area S' of the annular area are in a ratio of 1:1; the flow rate Q of the blast air into the small ring pipe distributor and the flow rate Q' of the blast air into the large ring pipe distributor are in a ratio of 1:1.

[0107] Example 1

[0108] A structural schematic diagram of the external heat exchanger provided by the application is shown in Figure 1 As can be seen from Figure 1 The external heat exchanger comprises a cylinder 1, a particle feeding pipe 5 and a gas discharging pipe 6 arranged at the top of the cylinder 1, two gas feeding pipes arranged on the sidewall of the cylinder 1, a particle discharging pipe 8 arranged at the bottom of the cylinder 1, and 12 vertical heat exchange pipe bundles 2 (with an outer diameter of 40 mm), a small ring pipe distributor 3 and a large ring pipe distributor 4 arranged in the cylinder 1 in sequence from top to bottom;

[0109] As shown in Fig. 5 (c), the circumference of the small ring pipe distributor 3 is uniformly provided with a circle of 10 first nozzles 9 which spray downward and are inclined inward, the circumference of the large ring pipe distributor 4 is uniformly provided with a circle of 15 second nozzles 13 (see the o mark in the figure) which spray downward and are inclined inward, and a circle of 15 second nozzles 13 (see the ⊕ mark in the figure) which spray downward and are inclined outward, and the second nozzles which are inclined inward and outward are arranged alternately;

[0110] The inclination angle a of the first nozzles is 45°, the inner diameter ratio of the small diameter section to the large diameter section in the first nozzles is 1:1.5, and the included angle b between the diameter expansion section and the large diameter section is 150°; the inclination angle a' of the second nozzles is 45°, the inner diameter ratio of the small diameter section to the large diameter section in the second nozzles is 1:1.7, and the included angle b between the diameter expansion section and the large diameter section is 150°;

[0111] The shortest distance between the vertical heat exchange pipe bundle and the small ring pipe distributor 3 arranged thereon is 0.2 m;

[0112] The cross-sectional area S of the central area and the cross-sectional area S' of the annular area are in a ratio of 1:3; the flow rate Q of the blast air into the small ring pipe distributor and the flow rate Q' of the blast air into the large ring pipe distributor are in a ratio of 1:3; the gas velocity of the blast air through the small diameter section of the first nozzles and the second nozzles is 35-60 m / s, and the gas velocity of the blast air through the large diameter section of the first nozzles and the second nozzles is 13-22 m / s.

[0113] Comparative Example 1

[0114] According to the external heat exchanger of Example 1, except that a single ring pipe distributor is arranged inside the external heat exchanger, and a top view schematic diagram of the single ring pipe distributor is shown in Fig. 5 (a);

[0115] The single-ring pipe distributor has a diameter of 280 mm, is provided with 24 downwardly spraying and outwardly tilting nozzles, the tilting angle of the nozzles is 45°, the nozzles are double-diameter nozzles, the inner diameter ratio of the small-diameter section and the large-diameter section of the nozzles is 1:1.7, and the included angle β between the expanded section and the large-diameter section is 150°.

[0116] Comparative Example 2

[0117] According to the external heat exchanger of Example 1, except that a tree-shaped distributor is arranged inside the external heat exchanger, and a top view of the tree-shaped distributor is shown in Fig. 5(b).

[0118] The tree-shaped distributor is provided with 45 vertical downward openings.

[0119] Test Example 1

[0120] The external heat exchangers arranged in Example 1 and Comparative Examples 1-2 are tested for heat transfer performance and operating performance, and the test results are shown in Table 1.

[0121] Table 1

[0122]

[0123] From the data in Table 1, it can be seen that, compared with the single-ring pipe gas distributor in Comparative Example 1 and the tree-shaped distributor in Comparative Example 2, the heat transfer coefficient is higher, and the improvement is on average 15-25%. The heat transfer performance of the double-ring pipe distributor in Example 1 is not only higher than that of Comparative Example 1, but also higher than that of Comparative Example 2, that is, compared with Comparative Example 2, the average heat transfer system of Example 1 is further improved by 5%.

[0124] At the same time, within the range of the apparent gas velocity tested, when the particle circulation flow rate is increased to 40-50 kg / (m 2 ·s), the external heat exchanger with the tree-shaped distributor in Comparative Example 2 often has the phenomenon of particle bridging and emptying below the distributor, and at this time, the device operation will have a large and violent fluctuation. In contrast, the external heat exchanger with the single-ring pipe distributor in Comparative Example 1 and the external heat exchanger with the double-ring pipe distributor in Example 1 do not have this problem within the range of the maximum particle circulation flow rate (0-100 kg / (m 2 ·s) that can be reached in the experiment.

[0125] Therefore, the external heat exchanger with the double-ring pipe distributor provided by the present application can simultaneously achieve good heat transfer performance and operating stability.

[0126] Test Example 2

[0127] The external heat exchangers with the distributors of Figs. 5(a), 5(b) and 5(c) respectively are used in a catalytic cracking device for heat removal load performance test.

[0128] The industrial catalytic cracking unit with a processing capacity of 800,000 tons per year originally has a dense phase down-flow type external heat exchanger with an inner diameter of 2.3 m, which adopts 42 densely arranged vertical heat exchange tube bundles, and a circular tube distributor with a circumferential diameter of 1.8 m is arranged at the bottom of the external heat exchanger, and 104 nozzles that spray obliquely downward and outward are arranged on the distributor, as shown in Fig. 5(a). During the operation of the unit, the maximum heat removal load of the external heat exchanger is far lower than the original design value, and the temperature measured by the local temperature measurement in the external heat exchanger can reach 100-200 ℃, which is often accompanied by the intensification of vibration of the external heat exchanger and the significant decrease of the heat removal load. It is preliminarily judged that the internal local dead bed or flow loss occurs, which causes the decrease of the performance and the operation stability of the external heat exchanger.

[0129] In order to solve the above problems, the gas distributor at the bottom of the external heat exchanger is transformed into a dendritic distributor similar to the regenerator of the catalytic cracking unit, as shown in Fig. 5(b). After the transformation, the phenomenon of dead bed and vibration in the external heat exchanger is significantly alleviated when the catalyst circulation amount is low, but when the catalyst particle circulation amount increases to a certain stage, the problems of dead bed and vibration still occur.

[0130] The gas distributor of the external heat exchanger is further transformed, and a double ring tube distributor structure shown in Fig. 5(c) is adopted, the small ring tube distributor has a diameter of 0.6 m and is provided with 42 gas nozzles that spray obliquely downward and inward, the large ring tube distributor has a diameter of 1.8 m and is provided with 122 nozzles that spray obliquely downward and inward or obliquely downward and outward, and the double ring tube distributor has a height difference of 0.4 m. During the one-year operation of the external heat exchanger with the double ring tube distributor, not only the maximum heat removal load of the external heat exchanger is increased by 30% compared with the original design value, but also the problems of serious dead bed and vibration do not occur again regardless of the change of the particle circulation amount, which indicates that the heat removal performance and the operation stability of the external heat exchanger are significantly improved.

[0131] The above describes the preferred embodiments of the present application in detail, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as the disclosed content of the present application and belong to the protection scope of the present application.

Claims

1. An external heat extractor, characterized in that, The external heat exchanger includes: a cylindrical body, inside which are arranged N vertical heat exchange tube bundles, where N is a natural number and N≥10; and a double-ring pipe distributor, which is arranged below the vertical heat exchange tube bundles and arranged in a ring around the central axis of the cylindrical body; it also includes a particle feed pipe and a gas discharge pipe arranged at the top of the cylindrical body. The dual-ring pipe distributor is selected from small-ring pipe distributors and large-ring pipe distributors with different heights, and the small-ring pipe distributor and the large-ring pipe distributor are respectively provided with a first nozzle and a second nozzle that spray downwards; when the small-ring pipe distributor is located above the large-ring pipe distributor, the small-ring pipe distributor is provided with a first nozzle that is inclined inwards, and the large-ring pipe distributor is provided with a second nozzle that is inclined inwards and an outwards; or, when the large-ring pipe distributor is located above the small-ring pipe distributor, the large-ring pipe distributor is provided with a second nozzle that is inclined outwards, and the small-ring pipe distributor is provided with a first nozzle that is inclined inwards and an outwards. The vertical distance between the small ring pipe distributor and the large ring pipe distributor is 0.3-0.8m. When the dual-ring pipe distributor injects pressurized air, by adjusting the structural settings of the dual-ring pipe distributor, the pressurized air injected by the dual-ring pipe distributor forms a dividing line in the cylinder, which is used to divide the interior of the cylinder into a central area and an annular area, and the ratio of the cross-sectional area S of the central area to the cross-sectional area S' of the annular area is 1:1-3. The ratio of the center diameter of the small ring pipe distributor to the diameter of the central area is 0.4-0.8:1; the ratio of the average value of the inner diameter of the cylinder and the diameter of the central area to the center diameter of the large ring pipe distributor is 1:0.9-1.

1.

2. The external heat extractor of claim 1, wherein, The center diameter of the small ring pipe distributor is less than the diameter of the central area, which is less than the center diameter of the large ring pipe distributor and less than the inner diameter of the cylinder. And / or, the ratio of the center diameter of the small ring pipe distributor to the diameter of the central area is 0.6-0.7:1; the ratio of the average value of the inner diameter of the cylinder and the diameter of the central area to the center diameter of the large ring pipe distributor is 1:0.95-1.

05.

3. The external heat extractor of claim 1, wherein, The shortest distance between the vertical heat exchange tube bundle and the ring tube distributor installed on it is ≥0.2m; And / or, the vertical heat exchange tube bundle is used to exchange heat between the particles to be heat exchanged and the heat exchange medium to obtain heat-exchanged particles; the dual-ring pipe distributor is used to uniformly distribute the pressurized air in the central area and the annular area.

4. The external heat extractor of claim 3, wherein, The shortest distance between the vertical heat exchange tube bundle and the ring tube distributor installed on it is 0.2-1m.

5. The external heat extractor of claim 1, wherein, The pressurized airflow Q introduced into the small loop distributor satisfies the following relationship with the cross-sectional area S of the central area: Q = a × S, where a > 0; the pressurized airflow Q' introduced into the large loop distributor satisfies the following relationship with the cross-sectional area S' of the annular area: Q' = a' × S', where a' > 0; And / or, the booster air flow rate Q into the small annular duct distributor, the booster air flow rate Q' into the large annular duct distributor, the cross-sectional area S of the central zone, and the cross-sectional area S' of the annular zone satisfy: ; And / or, the booster airflow Q introduced into the small loop distributor satisfies the following relationship with the number of first nozzles N: Q = b × N, where b > 0; the booster airflow Q' introduced into the large loop distributor satisfies the following relationship with the number of second nozzles N': Q' = b' × N', where b' > 0.

6. The external heat extractor of claim 5, wherein, a is 0.1-0.5; a' is 0.1-0.

5.

7. The external heat extractor of claim 1, wherein, The tilt angle α of the first nozzle is 20-50°, and the tilt angle α' of the second nozzle is 20-50°.

8. The external heat extractor of claim 7, wherein, The first nozzle and the second nozzle respectively penetrate the small ring tube distributor and the large ring tube distributor; The first nozzle and the second nozzle are each independently a dual-diameter nozzle.

9. The external heat extractor of claim 8, wherein, Along the flow direction of the pressurized air, the first nozzle and the second nozzle each independently include: a small-diameter section, an expanded-diameter section, and a large-diameter section; The ratio of the inner diameter of the smaller diameter segment to the larger diameter segment is 1:1.3-2.5; the ratio of the length of the smaller diameter segment to the larger diameter segment is 1:2-10. Wherein, the cone angle of the expanded diameter section is >90°.

10. The external heat extractor of claim 9, wherein, The cone angle of the expanded diameter section is 120-180°.

11. The external heat extractor of any one of claims 1-10, wherein, The external heat exchanger also includes: a particle discharge pipe disposed at the bottom of the cylinder; And / or, the external heat exchanger further includes: two gas feed pipes disposed on the side wall of the cylinder, and the gas feed pipes are connected to the dual-ring pipe distributor.

12. The application of the external heat exchanger according to any one of claims 1-11 in catalytic cracking processes and coal chemical processes.

13. A catalytic cracking unit, characterized in that, The catalytic cracking unit comprises: a reactor, a regenerator, and an external heat exchanger as described in any one of claims 1-11, connected in sequence. The reactor is used to contact and react oil and catalyst to obtain oil and gas products and a pre-regenerating agent; the regenerator is used to regenerate the pre-regenerating agent to obtain a regenerating agent; the external heat exchanger is used to exchange heat between the regenerating agent and the heat exchange medium in a pressurized air uniformly distributed atmosphere to obtain a heat-exchanged regenerating agent. The external heat exchanger is also connected to the regenerator and is used to regulate the temperature of the regenerator.

14. A method for catalytic cracking, characterized in that, The method is carried out in the catalytic cracking apparatus of claim 13; wherein the method includes the following steps: (1) The oil and catalyst are brought into contact and reacted to obtain oil and gas products and a catalyst; (2) The regenerating agent is regenerated to obtain a regenerating agent; (3) In a pressurized air uniformly distributed atmosphere, the regenerator and the heat exchange medium are heat exchanged to obtain the heat-exchanged regenerator.

15. The method according to claim 14, wherein, In step (3), the superficial gas velocity of the pressurized air is ≥ 0.2 m / s; and the particle circulation flow rate of the regenerant is ≤ 100 kg / (m 2 ·s).

16. The method according to claim 15, wherein, In step (3), the apparent gas velocity of the pressurized air is 0.2-0.8 m / s; the particle circulation flow rate of the regenerant is 0-100 kg / (m 2 ·s).

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