CN114100539A - Intraductal enhanced heat transfer plug-in components and pyrolysis furnace - Google Patents
Intraductal enhanced heat transfer plug-in components and pyrolysis furnace Download PDFInfo
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- CN114100539A CN114100539A CN202111289500.8A CN202111289500A CN114100539A CN 114100539 A CN114100539 A CN 114100539A CN 202111289500 A CN202111289500 A CN 202111289500A CN 114100539 A CN114100539 A CN 114100539A
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F1/00—Tubular elements; Assemblies of tubular elements
- F28F1/10—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses
- F28F1/40—Tubular elements and assemblies thereof with means for increasing heat-transfer area, e.g. with fins, with projections, with recesses the means being only inside the tubular element
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Abstract
The utility model provides an intraductal heat transfer plug-in components and pyrolysis furnace of reinforceing, intraductal heat transfer plug-in components include body and a plurality of flight, and the body is used for inserting to locate in the boiler tube, and closely laminates with the boiler tube, and a plurality of flights are connected in the inner wall of body. The heat transfer enhancing plug-in unit in the tube can effectively improve the heat exchange efficiency through the spiral sheet, reduce the coking phenomenon in the furnace tube, reduce the self deformation, and simultaneously meet the pressure loss through adjusting the combination mode of the spiral sheet in the plug-in unit.
Description
Technical Field
The invention belongs to the technical field of fluid heat transfer and chemical equipment manufacturing, and particularly relates to an in-pipe enhanced heat transfer plug-in unit and a cracking furnace.
Background
According to the Fourier theorem of the heat transfer process, the heat transfer quantity is related to the heat transfer coefficient, the heat exchange area and the logarithmic mean temperature difference. The enhanced heat transfer technology can be divided into active enhancement and passive enhancement according to whether external power is consumed or not, and the passive enhancement technology is generally adopted in the industry due to the reasons of energy conservation, emission reduction, stability improvement and the like. The passive strengthening technology does not need external power and is mainly realized by increasing the heat exchange area, increasing the temperature difference of heat exchange materials and improving the heat exchange coefficient. Taking heat exchange equipment of a heat exchange tube as an example, wherein the heat exchange area can be increased by arranging fins inside and outside the heat exchange tube or reducing the diameter of the heat exchange tube so as to increase the heat exchange area of materials in unit volume; the increase of the temperature difference is mainly realized by changing the temperature difference between the inside and the outside of the heat exchange tube; the heat transfer coefficient can be increased by changing the material of the heat exchange tube, countercurrent, increasing the flow velocity in the tube, reducing the boundary layer of fluid in the tube, reducing the scale in the tube and the like.
The cracking furnace is one of indispensable equipment in the chemical industry field, and its main function is to heating the raw materials that decompose to realize the cracking reaction. Because the increase of the heat exchange area and the increase of the temperature difference of heat exchange materials are restricted by the volume of equipment and the process flow, the heat transfer of the cracking furnace is enhanced mainly by improving the heat exchange coefficient. In the prior art, a twisted sheet is commonly used as an inner insert for enhancing heat transfer, the twisted sheet is fixed in a furnace tube, and fluid in the tube can generate circumferential motion of the furnace tube when passing through the twisted sheet, so that the mixing degree of the fluid is enhanced, and a boundary layer on the inner wall of the tube is reduced, thereby achieving the effect of enhancing heat transfer. Although the twisted piece has a certain enhanced heat transfer effect, the twisted piece is longer and fixed with the heat exchange tube, so that the twisted piece is easy to break or fall off due to deformation caused by fluid impact and thermal stress, and the service life of the furnace tube is influenced. Furthermore, twisting the sheets over an angle of rotation can increase fluid pressure loss within the tube, thereby affecting process requirements or increasing consumption. Therefore, there is a need for an in-tube enhanced heat transfer insert that can improve heat exchange efficiency, minimize pressure loss, and improve heat exchange tube stability and service life.
Disclosure of Invention
The invention aims to provide an in-tube enhanced heat transfer plug-in and a cracking furnace, which can improve the heat exchange efficiency, reduce the pressure loss to the maximum extent, improve the stability of a heat exchange tube and prolong the service life of the heat exchange tube.
In order to achieve the above object, the present invention provides an in-tube enhanced heat transfer insert, which includes a tube body and a plurality of spiral sheets, wherein the tube body is inserted into a furnace tube and is tightly attached to the furnace tube, and the plurality of spiral sheets are connected to an inner wall of the tube body.
Preferably, the tube body and the furnace tube are both straight tubes, and the length of the tube body is 0.01-0.06 times of the length of the furnace tube; the wall thickness of the tube body is 0.05-1 times of that of the furnace tube.
Preferably, the height h1 of each spiral sheet along the axial direction of the pipe body is 0.05-0.1 times of the length h2 of the pipe body, and the axial heights of the spiral sheets are the same or different; the thickness of each spiral piece is 0.5-1 times of the wall thickness of the pipe body.
Preferably, a plurality of the flight centers on the center pin spiral setting of body on the transverse section of body, the projection of flight is the segmental arc, the outline of segmental arc includes inboard arc, outside arc and a pair of side, two adjacent form the arc clearance between the projection of flight, form first contained angle a between the both sides in arc clearance, first contained angle a is less than 60.
Preferably, a plurality of the spiral pieces are spirally arranged around a central axis of the pipe body, in a transverse cross section of the pipe body, a projection of each spiral piece is an arc-shaped section, an outer contour of each arc-shaped section comprises an inner arc, an outer arc and a pair of side edges, and projection parts between at least one pair of adjacent spiral pieces are overlapped.
Preferably, a second included angle b is formed between the spiral sheet and the axial direction of the pipe body, and the range of the second included angle b is 15-165 degrees.
Preferably, the arc length of the outer arc is 0.01-0.99 times of the inner circumference of the pipe body.
Preferably, the outer side arc of the spiral piece is connected to the inner wall of the pipe body, and the distance between the inner side arc and the outer side arc is 0.1-0.49 times of the inner diameter of the pipe body.
Preferably, each of the flights comprises an upstream face and a downstream face, the tubular body comprising a fluid inlet and a fluid outlet, the upstream face being disposed towards the fluid inlet and the downstream face being disposed towards the fluid outlet.
Preferably, the inner periphery of at least one of the spiral pieces is provided with a folded edge, the folded edge is folded upwards relative to the spiral piece and forms a fourth included angle with the upstream face, or the folded edge is folded downwards relative to the spiral piece and forms a fifth included angle with the downstream face.
Preferably, the inner circumference of the spiral sheet is corrugated.
Preferably, at the joint of the spiral piece and the inner wall of the pipe body, a third included angle c is formed between the spiral piece and the inner wall of the pipe body, and the range of the third included angle c is 30-150 °.
Preferably, the surface of at least one of the spiral sheets is provided with a through hole.
Preferably, the edges of the spiral sheet are provided with chamfers.
Preferably, the spiral sheet is made of a hard material, and the section of the spiral sheet in the thickness direction is rectangular or elliptical.
The invention also provides a cracking furnace, which comprises a radiation chamber, wherein at least one furnace tube is arranged in the radiation chamber, and the heat transfer enhancing plug-in the tube is arranged in the furnace tube.
The invention relates to an in-pipe enhanced heat transfer insert, which has the beneficial effects that: the spiral sheet can effectively improve the heat exchange efficiency, reduce the coking phenomenon in the furnace tube, reduce the deformation of the spiral sheet, and simultaneously, the pressure loss can be met by adjusting the spiral sheet combination mode in the plug-in unit.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings, in which like reference numerals generally represent like parts throughout.
FIG. 1 shows a schematic structural view of an enhanced heat transfer insert within a tube according to an exemplary embodiment of the present invention;
FIG. 2 is a schematic diagram illustrating a spiral flight in an enhanced heat transfer insert within a tube according to an exemplary embodiment of the present invention;
FIG. 3 is a schematic diagram illustrating the construction of the flights in the enhanced heat transfer insert within the tube according to another exemplary embodiment of the present invention;
FIG. 4 illustrates a cross-sectional view of an enhanced heat transfer insert within a tube according to an exemplary embodiment of the present invention;
FIG. 5 illustrates a top view of an enhanced heat transfer insert within a tube according to an exemplary embodiment of the present invention;
FIG. 6 illustrates a layout of a plurality of flights in a enhanced heat transfer insert within a tube in accordance with an exemplary embodiment of the present invention;
FIG. 7 illustrates a cross-sectional view of an enhanced heat transfer insert within a tube according to another exemplary embodiment of the present invention;
FIG. 8 illustrates a top view of the enhanced heat transfer insert within the tube of FIG. 7;
FIG. 9 illustrates a layout of a plurality of flights in the enhanced heat transfer insert within the tube of FIG. 7.
Description of reference numerals:
1. the device comprises a pipe body, 2 spiral pieces, 3 through holes, 4 upstream faces, 5 spiral piece folded edges, 6 backside faces, 10 fluid inlets and 20 fluid outlets.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the invention.
In order to solve the problems in the prior art, the invention provides an in-tube enhanced heat transfer insert, as shown in fig. 1 to 9, fig. 1 shows a three-dimensional structure diagram of the in-tube enhanced heat transfer insert of the invention, which comprises a tube body 1 and a plurality of spiral sheets 2, wherein the tube body 1 is used for being inserted into a furnace tube and is tightly attached to the furnace tube, and the plurality of spiral sheets 2 are connected to the inner wall of the tube body 1.
The heat transfer enhancement plug-in unit in the tube can effectively improve the heat exchange efficiency through the spiral sheet 2, reduce the coking phenomenon in the furnace tube, reduce the self deformation, and simultaneously meet the pressure loss through adjusting the combination mode of the spiral sheet 2 in the plug-in unit.
Fig. 2 and 3 show a specific structure of the flight 2, fig. 4, 5, and 6 show an arrangement of the flight 2, and fig. 7, 8, and 9 show another arrangement of the flight 2, and the specific structure of the present invention will be described below.
The furnace tube can be a furnace tube of a cracking furnace, and can also be applied to other heat exchangers, as shown in fig. 1, the tube body 1 and the furnace tube are both straight tubes, and the length of the tube body 1 is 0.01-0.06 times of the length of the furnace tube; the wall thickness of the tube body 1 is 0.05-1 times of that of the furnace tube.
The outer diameter of the pipe body 1 is the same as the inner diameter of the furnace pipe to be installed, no gap is formed between the inner wall of the furnace pipe and the pipe body 1, the pipe body 1 can be fixed on the inner wall of the furnace pipe in a welding or clamping mode and the like, and is preferably installed in front of and behind the welding seam of the furnace pipe. The pipe body 1 is made of hard material, and preferably, the material of the pipe body 1 is the same as that of a furnace tube of the cracking furnace.
One end of the pipe body 1 is a fluid inlet 10, the other end of the pipe body 1 is a fluid outlet 20, the plurality of spiral pieces 2 are arranged in the pipe body 1 in a sectional mode, when fluid in a furnace pipe passes through an insert, the fluid which originally only has axial speed collides with the spiral pieces 2, so that the flow direction of the fluid is changed, the circumferential flow speed is generated, the thickness of a boundary layer is reduced while mixed flow is formed, the turbulence intensity of the fluid is increased, and the purposes of strengthening heat transfer and preventing scale formation and deposition are achieved.
In one embodiment of the present invention, as shown in fig. 4 to 6, a plurality of spiral sheets 2 are spirally arranged around a central axis of a pipe body 1, and in a transverse cross section of the pipe body 1, that is, a cross section perpendicular to an axial direction of the pipe body 1, a projection of each spiral sheet 2 is an arc-shaped segment, an outer contour of the arc-shaped segment includes an inner arc, an outer arc and a pair of side edges, an arc-shaped gap is formed between projections of two adjacent spiral sheets 2, and a first included angle a is formed between two sides of the arc-shaped gap, and the first included angle a is smaller than 60 °. Viewed in a transverse cross section of the pipe body 1, the plurality of spiral pieces 2 are arranged along the circumferential direction, and therefore, the interval between two spiral pieces 2 adjacent to each other in the circumferential direction can be represented by an angle, namely, a first included angle a.
The plurality of spiral blades 2 are formed in a clockwise or counterclockwise direction as viewed from the fluid inlet 10 of the pipe body 1. The arrangement direction of each spiral sheet 2 can be different according to actual requirements.
The height h1 of each spiral piece 2 along the axial direction of the pipe body 1 is 0.05 to-0.1 time of the length h2 of the pipe body 1, and the axial heights of the spiral pieces 2 are the same or different; the thickness of each spiral piece 2 is 0.5-1 times of the wall thickness of the pipe body 1.
Can adjust 1 length of body and thickness according to heat transfer effect, loss of pressure and technological requirement etc. and the longer heat transfer effect of length is more obvious, nevertheless can increase loss of pressure correspondingly, and the increase of thickness of body 1 can lead to flow area to reduce, also can increase loss of pressure when increasing the heat transfer effect.
A second included angle b is formed between each spiral sheet 2 and the axial direction of the pipe body 1, and the range of the second included angle b is 15-165 degrees. As shown in fig. 1 and 4, the spiral piece 2 forms a certain angle with the central axis direction of the tube 1, which can be understood as that one side of the fixed spiral piece 2 is fixed and the other side is lifted or lowered for a certain distance along the axis direction of the tube 1, so that the fluid forms clockwise or counterclockwise rotation when impacting the spiral piece. The spiral piece 2 may be a plane structure or a curved structure, as shown in fig. 4, the second included angle b may also be regarded as an inclined direction of the spiral piece 2 relative to the central axis of the tube 1, that is, an inclined direction of the spiral piece 2 and the central axis of the tube 1 are included angles with the lower end of the spiral piece 2 and the central axis of the tube 1 as an intersection point.
As shown in FIG. 2, the arc length of the outer arc of the projection of the spiral piece 2 on the transverse section of the pipe body 1 is 0.01 to 0.99 times the inner circumference of the pipe body 1.
The outer arc of each spiral piece 2 is connected to the inner wall of the pipe body 1, and the distance between the inner arc and the outer arc is 0.1-0.49 times of the inner diameter of the pipe body 1. The distance from the outer arc of the spiral piece 2 to the center of the pipe body 1 is the same as the inner diameter of the pipe body 1, and the distance between the inner arc and the outer arc, namely the extension length of the spiral piece 2 from the inner wall of the pipe body 1 to the direction of the central axis.
Each helical blade 2 comprises a water facing surface 4 and a water backing surface 6, the pipe body 1 comprises a fluid inlet 10 and a fluid outlet 20, the water facing surface 4 is arranged towards the fluid inlet 10, the water backing surface 6 is arranged towards the fluid outlet 20, the water facing surface 4 and the water backing surface 6 can be planes or curved surfaces, and the curved surfaces can be corrugated surfaces.
As shown in fig. 4 to 6, in the present embodiment, 6 spiral sheets 2 are uniformly distributed in the tube body 1 in a spiral shape, and the distance between each spiral sheet 2 in the axial direction and the transverse direction of the tube body 1 is a constant value. It is also understood that 6 flights are obtained by: the ribbon with certain width is coiled into a ring shape and sleeved into the fluid inlet 10 of the tube body 1, then one end of the ring is fixed, the other end of the ring is translated towards the fluid outlet 20, the ring is formed into a spiral ribbon, finally, a fan-shaped object is moved along the axial direction along the inner diameter of the straight tube 1, and the part intersected with the ribbon-shaped object is cut off. Wherein, the included angle of the central axis direction of the helical piece 2 and the pipe body 1 is determined by the ascending or descending distance of one section of the belt-shaped object, the width of the belt-shaped object is the outward extending length of the helical piece 2 to the central axis direction of the pipe body 1, and the angle of the fan-shaped object is the included angle of the helical piece 2 along the circumferential direction of the pipe body 1. After fluid enters from the fluid inlet 10, only fluid with axial flow velocity originally impacts the upstream surface of the first spiral piece 2, and because the spiral pieces 2 and the fluid outlet 20 form an included angle of 45 degrees in the direction from the fluid inlet 10, namely the central axis direction of the pipe body 1, the fluid moves clockwise along the pipe body 1, the fluid can impact the pipe wall to reduce the thickness of a boundary layer, meanwhile, a part of the fluid which flows through from the central axis is driven to move towards the pipe wall direction, mixed flow is formed in the whole pipeline, and the other part of the fluid flows through a circumferential gap between the central axis and the spiral pieces 2, so that pressure loss is reduced. And in the process of continuously flowing the fluid, the process is continuously repeated, and finally the effects of enhancing heat exchange and reducing pressure loss are achieved.
In the above embodiment, different heat exchange requirements can be achieved by changing the shape of the spiral sheet 2. Under the condition that other conditions are not changed, when the included angle between the spiral piece 2 and the central shaft direction of the pipe body 1, namely the second included angle b, is an acute angle or a corresponding obtuse angle, the heat exchange effect is approximately the same, and the difference is that the fluid only increases clockwise flow or anticlockwise flow. When the included angle is 90 degrees, the impact force of the fluid is the largest, the mixing effect is the best, but the corresponding pressure loss is also the largest, and meanwhile, the service life is also the smallest due to the largest stress of the spiral piece 2. In addition, the length of the helical fin 2 extending from the inner wall of the pipe body 1 to the central axis direction, that is, the distance between the inner arc and the outer arc of the helical fin 2 can also change the heat exchange effect. This distance directly affects the through flow area of the fluid in the pipe body 1, the longer the distance, the smaller the flow area. When the distance is equal to the radius of the inner wall of the pipe body 1, the area of the central axis of the pipe body 1 is completely sealed, all fluid can only move in the spiral direction of the spiral piece 2 at the moment, the mixing degree is low, and the pressure drop is small; when the distance is smaller, namely the impact surface of the fluid and the spiral piece 2 is smaller, the flow area of the central axis area of the pipe body 1 is larger, most of the fluid directly flows through the penetration area, the mixing degree is lower, and the pressure drop is smaller. Therefore, when the distance between the inner arc and the outer arc of the spiral piece 2 is 0.15-0.3 times of the inner diameter of the pipe body 1, the mixing effect and the pressure loss both achieve the appropriate effect, and meanwhile, the stress condition of the spiral piece 2 also meets the strength requirement.
In this embodiment, at the joint between the helical fin 2 and the inner wall of the tube body 1, a third included angle c is formed between the helical fin 2 and the inner wall of the tube body 1, and the third included angle c is 30 ° to 150 °. As shown in fig. 7, a plurality of spiral pieces 2 are spirally arranged in the tube body 1, therefore, a single spiral piece 2 is obliquely arranged, the surface of the spiral piece 2 can be a plane or a curved surface, when the surface of the spiral piece 2 is a plane, the third included angle c is the included angle between the surface of the spiral piece 2 and the inner wall of the tube body 1, and when the surface 2 of the spiral piece 2 is a curved surface, the curvature can be ignored, and the plane where at least most of the spiral piece 2 is located, or the included angle between the approximate plane where the spiral piece 2 is located and the tube body 1 is the third included angle c.
In other embodiments of the invention, the surface of at least one of the spiral sheets 2 is provided with through holes 3, through which holes 3 fluid can pass. The through holes 3 may be set according to the heat exchange effect and the pressure loss of actual needs, including the number, the arrangement position, the diameter, and the like. The edge of flight 2 is equipped with the chamfer, and this chamfer can be the fillet, and the internal periphery, periphery or the side of flight 2 all can set up the chamfer. The inner circumference of the spiral sheet 2 may be corrugated.
The surface of the spiral blade 2 facing the fluid inlet 10 is a water facing surface 4, and the surface facing the fluid outlet 20 is a water backing surface 6; at least one flight 2's interior week is equipped with hem 5, and hem 5 turns over to turn over and forms the fourth contained angle with upstream face 4, or, hem 5 turns over to turn over downwards and forms the fifth contained angle with surface of a backing 6, and fourth contained angle and fifth contained angle are acute angle, right angle or obtuse angle, and the scope of fourth contained angle and fifth contained angle is greater than 0 promptly, is less than 180.
In the embodiment shown in fig. 3, the inner arc of the spiral sheet 2 is provided with a folded edge, and the folded edge 5 is folded upwards and arranged at an acute angle with the upstream surface 4.
In another embodiment of the present invention, as shown in fig. 7 to 9, a plurality of spiral sheets 2 are spirally arranged around a central axis of a pipe body 1, and in a transverse cross section of the pipe body 1, a projection of the spiral sheet 2 is an arc-shaped segment, an outer contour of the arc-shaped segment includes an inner arc, an outer arc and a pair of side edges, and projection portions between at least one pair of adjacent spiral sheets 2 are overlapped. Compared with the embodiment shown in fig. 4 to 6, the present embodiment has the difference that the axial included angle between the spiral piece 2 and the pipe body 1, i.e. the second included angle b, is 30 °, the impact force of the spiral piece 2 to the fluid is larger, and the mixing effect is better. The length of the outer circumference of the spiral piece 2 is 0.0625 times of the circumference of the inner circumference of the pipe body 1, compared with the above embodiment, the single spiral piece 2 is less impacted by fluid and has longer service life. In addition, the arrangement of the respective spiral pieces 2 is different from that described above, thereby changing the area of the gap between the adjacent spiral pieces 2 in the transverse section of the tubular body 1. In this embodiment, the impact force of the fluid on the single spiral blade 2 is significantly reduced due to the small outer arc length, but a strong mixing effect is still formed by changing the arrangement of the individual spiral blades 2.
From the above, it can be seen that the shape of the single spiral sheet 2 and the arrangement of the spiral sheets 2 affect the heat exchange effect and the pressure loss, but the service life is more affected by the shape of the single spiral sheet 2. Therefore, preferably reach the less atress effect of flight 2 through the axial contained angle that changes flight 2 and body 1, the contained angle of second contained angle b, flight 2 and the inner wall direction of body 1, third contained angle c, flight 2 outside arc length and the distance between inboard arc and the outside arc to maximize increase of service life. And then, the arrangement mode of each spiral piece 2 is changed, so that a better heat exchange effect and pressure loss are achieved. Specifically, it is possible to vary the gap between the projections of the respective spiral pieces 2 on the transverse section of the tubular body 1 and the height h1 in the axial direction of the tubular body 1.
In the invention, the spiral sheet 2 is made of hard material, preferably the same material as the furnace tube, and the section of the spiral sheet 2 along the thickness direction can be rectangular or oval and other irregular shapes.
The heat transfer enhancement insert in the pipe can change the heat exchange effect and the pressure loss by changing a first included angle a between projections of the spiral plate 2 on the transverse section of the pipe body 1, the height h1 along the axial direction of the pipe body 1, the length and the thickness of an outer arc, the distance between the inner arc and the outer arc, a third included angle c, the number, the diameter and the arrangement position of the through holes 3 arranged on the surface and the through holes 3, an inner arc chamfer, the shape of an inner arc end, the folded edge 5 and the included angle between the folded edge 5 and the upstream surface 4, and the following specific description refers to.
In the first embodiment of the invention, the length and the thickness of the tube body 1 are respectively 0.01 times and 0.05 times of that of the straight tube section furnace tube, the second included angle b between the spiral sheets 2 and the axial direction of the tube body 1 is 30 degrees, and the outer arc length of the spiral sheets 2 is 0.15 times of the inner circumference of the tube body 1. The height h1 of each spiral sheet 2 in the axial direction of the pipe body 1 and the gap between two adjacent spiral sheets 2 projected on the transverse section of the pipe body 1 are the same. When a first included angle a of a gap between the spiral sheets 2 on the transverse section of the pipe body 1 is smaller, namely the area of the gap is smaller, the passing amount of fluid is smaller, the degree of fluid turbulence is increased, the boundary layer is reduced, the heat exchange effect is better, but the pressure loss of the fluid is correspondingly larger; when the first included angle a between the spiral sheets 2 on the transverse section of the pipe body 1 is larger, namely the area of the gap is larger, the passing amount of the fluid is larger, the turbulence degree of the fluid is reduced, the heat exchange effect is poorer, and the pressure loss of the fluid is smaller. When the first included angle a is between 15 and 45 degrees, both the heat exchange effect and the pressure loss reach a proper range.
In the second embodiment of the invention, the length and the thickness of the tube body 1 are respectively 0.01 time and 0.05 time of that of the straight tube section furnace tube, the outer arc length of the spiral piece 2 is 0.15 time of the inner circumference of the tube body 1, the first included angle a of the gap between two adjacent spiral pieces 2 projected on the transverse section of the tube body 1 is 15 degrees, and the second included angle b between the spiral piece 2 and the axial direction of the tube body 1 is 15 degrees to 165 degrees. When the second included angle b is smaller, the impact force between the fluid and the spiral piece 2 is smaller, the turbulence degree is smaller, and therefore the heat exchange effect is poorer, and the pressure loss is lower. When the second included angle b is 90 degrees, the fluid impact force is the largest, the turbulence degree is the largest, the heat exchange effect is the best, and the pressure loss is also the largest. When the second included angle b is larger, the impact force of the fluid colliding with the spiral sheet 2 is smaller, the turbulence degree is smaller, the heat exchange effect is poorer, and the pressure loss is lower. Therefore, when the second included angle b is about 30 ° and about 150 °, both the heat exchange effect and the pressure loss reach appropriate ranges.
In the third embodiment of the invention, the length and the thickness of the tube body 1 are respectively 0.01 times and 0.05 times of that of the straight tube section furnace tube, a first included angle a of a gap between two adjacent spiral sheets 2 projected on the transverse section of the tube body 1 is 15 degrees, a second included angle b between the spiral sheets 2 and the axial direction of the tube body 1 is 30 degrees, and the outer arc length of each spiral sheet 2 is 0.01-0.991 times of the inner circumference of the tube body 1. When the arc length of the outer side of the spiral piece 2 is small, the water-facing area of the spiral piece 2 is small, the impact force between fluid and the spiral piece 2 is small, the turbulence degree is small, the heat exchange effect is poor, and the pressure loss is low. When the outside arc length of flight 2 is great, flight 2 is faced the water area great, and fluid and flight 2 impact is great, and the torrent degree is great, and consequently the heat transfer effect is better, but loss of pressure is great, and stress deformation is great. Therefore, when the arc length of the outer side of the spiral piece 2 is 0.15 to 0.3 times of the circumference of the inner circumference of the pipe body 1, the heat exchange effect and the pressure loss reach a proper range.
The heat transfer enhancing plug-in the tube can increase the turbulence degree of fluid in the tube, reduce the generation of a boundary layer and increase the heat exchange effect of the furnace tube; because the flow direction of the fluid in the pipe is changed and the circumferential movement of the fluid is increased, the fluid continuously impacts the spiral piece 2 and the pipe wall, and the possibility of dirt deposition on the surface of the spiral piece 2 and the inner wall of the pipe is reduced; because the mixed flow degree of the fluid in the tube is increased, the time for the fluid in the tube to stay on the inner wall of the furnace tube is greatly reduced, and the coking phenomenon caused by overhigh temperature is avoided; by changing the included angle between the single spiral piece 2 and the upstream face 4, namely a second included angle b between the single spiral piece 2 and the axial direction of the pipe body 1, the length and thickness of the outer arc, a third included angle c between the single spiral piece 2 and the inner wall of the pipe body 1, the sectional shape of the thickness direction, the number and the diameter of the openings of the through holes 3, the angle of the folded edge 5 and the inner arc shape, the impact force between the fluid in the pipe and the single spiral piece 2 can be changed, so that the heat exchange effect and the pressure loss are changed, and different requirements are met; by changing the first included angle a of the interval between each spiral piece 2 projected on the transverse section of the pipe body 1, the height h1 along the axial direction of the pipe body 1, and the distance between the inner side arc and the outer side arc, different arrangement modes of the spiral pieces 2 can be formed, and different flow areas are caused, so that different heat exchange effects and pressure losses are met.
The invention also provides a cracking furnace, which comprises a radiation chamber, wherein at least one furnace tube is arranged in the radiation chamber, and the inside of the furnace tube is provided with the heat transfer enhancing plug-in unit.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (16)
1. The utility model provides an intraductal heat transfer plug-in components that strengthen, characterized in that, includes body (1) and a plurality of flight (2), body (1) are used for inserting locate in the boiler tube, and with the boiler tube is closely laminated, and is a plurality of flight (2) connect in the inner wall of body (1).
2. The enhanced heat transfer insert in tube according to claim 1, wherein the tube body (1) and the furnace tube are both straight tubes, and the length of the tube body (1) is 0.01-0.06 times of the length of the furnace tube; the wall thickness of the tube body (1) is 0.05-1 times of that of the furnace tube.
3. The enhanced heat transfer insert in pipe according to claim 1, wherein the height h1 of each spiral sheet (2) along the axial direction of the pipe body (1) is 0.05-0.1 times the length h2 of the pipe body (1), and the axial heights of the spiral sheets (2) are the same or different; the thickness of each spiral sheet (2) is 0.5-1 times of the wall thickness of the pipe body (1).
4. The enhanced heat transfer insert according to claim 1, wherein a plurality of said spiral fins (2) are spirally arranged around a central axis of said pipe body (1), and in a transverse cross section of said pipe body (1), a projection of said spiral fins (2) is an arc-shaped segment, an outer contour of said arc-shaped segment comprises an inner arc, an outer arc and a pair of side edges, an arc-shaped gap is formed between the projections of two adjacent spiral fins (2), and two sides of said arc-shaped gap form a first included angle a, and said first included angle a is smaller than 60 °.
5. The enhanced heat transfer insert in pipe according to claim 1, wherein a plurality of said spiral sheets (2) are spirally arranged around a central axis of said pipe body (1), and a projection of said spiral sheets (2) is an arc-shaped segment in a transverse cross section of said pipe body (1), an outer contour of said arc-shaped segment comprises an inner arc, an outer arc and a pair of side edges, and a projection of at least one pair of adjacent spiral sheets (2) is overlapped.
6. The enhanced heat transfer insert in tube according to claim 4 or 5, wherein a second included angle b is formed between the spiral sheet (2) and the axial direction of the tube body (1), and the second included angle b ranges from 15 ° to 165 °.
7. The enhanced heat transfer insert in pipe according to claim 4 or 5, wherein the arc length of the outer arc is 0.01-0.99 times the inner circumference of the pipe body (1).
8. The enhanced heat transfer insert in pipe according to claim 4 or 5, wherein the distance between the inner arc and the outer arc is 0.1-0.49 times the inner diameter of the pipe body (1).
9. The enhanced heat transfer insert in tubes according to claim 4 or 5, wherein each of the spiral fins (2) comprises a water facing surface (4) and a water backing surface (6), the tube body (1) comprising a fluid inlet (10) and a fluid outlet (20), the water facing surface (4) being disposed towards the fluid inlet (10) and the water backing surface (6) being disposed towards the fluid outlet (20).
10. The enhanced heat transfer insert in pipe according to claim 9, wherein the inner periphery of at least one of said spiral fins (2) is provided with a folded edge (5), said folded edge (5) being folded upwards and forming a fourth angle with said upstream surface (4), or said folded edge (5) being folded downwards and forming a fifth angle with said downstream surface (6).
11. The enhanced heat transfer insert in tubes according to claim 4 or 5, wherein the inner circumference of the spiral sheet (2) is corrugated.
12. The enhanced heat transfer insert in pipe according to claim 1, wherein a third included angle c is formed between the spiral sheet (2) and the inner wall of the pipe body (1) at the joint of the spiral sheet (2) and the inner wall of the pipe body (1), and the third included angle c ranges from 30 ° to 150 °.
13. The enhanced heat transfer insert in tubes according to claim 1, wherein the surface of at least one of said spiral sheets (2) is provided with through holes (3).
14. The enhanced heat transfer insert in tubes according to claim 1, wherein the edges of the spiral sheet (2) are chamfered.
15. The enhanced heat transfer insert in pipe according to claim 1, wherein the spiral sheet (2) is made of hard material, and the section of the spiral sheet (2) in the thickness direction is rectangular or elliptical.
16. A cracking furnace comprising a radiant chamber, wherein at least one furnace tube is disposed within the radiant chamber, wherein an in-tube enhanced heat transfer insert as claimed in any one of claims 1 to 15 is disposed within the furnace tube.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111289500.8A CN114100539A (en) | 2021-11-02 | 2021-11-02 | Intraductal enhanced heat transfer plug-in components and pyrolysis furnace |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111289500.8A CN114100539A (en) | 2021-11-02 | 2021-11-02 | Intraductal enhanced heat transfer plug-in components and pyrolysis furnace |
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| CN114100539A true CN114100539A (en) | 2022-03-01 |
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| CN202111289500.8A Pending CN114100539A (en) | 2021-11-02 | 2021-11-02 | Intraductal enhanced heat transfer plug-in components and pyrolysis furnace |
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