CN103791483B - Styrene heating furnace and application thereof in chemical field - Google Patents
Styrene heating furnace and application thereof in chemical field Download PDFInfo
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- CN103791483B CN103791483B CN201210424587.XA CN201210424587A CN103791483B CN 103791483 B CN103791483 B CN 103791483B CN 201210424587 A CN201210424587 A CN 201210424587A CN 103791483 B CN103791483 B CN 103791483B
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Abstract
The invention discloses a styrene heating furnace, which comprises a radiation section, wherein the radiation section is provided with a heat exchange tube (10), an enhanced heat transfer element is arranged in the heat exchange tube (10), the enhanced heat transfer element comprises a twisted piece, and the twisted piece is provided with a hole. The invention also provides application of the styrene heating furnace in the chemical field. Through the technical scheme, the enhanced heat transfer element is arranged in the heat exchange tube of the radiation section of the styrene heating furnace, so that the flow form of fluid in the heat exchange tube is changed, the intensity of turbulent flow is increased, the original boundary layer of heat transfer is thinned, the heat transfer performance of the styrene heating furnace is improved, and the overall performance of the styrene heating furnace is improved.
Description
Technical Field
The invention relates to the field of chemical industry, in particular to a styrene heating furnace and application thereof in the field of chemical industry.
Background
Styrene is an important basic organic chemical raw material and is the derivative with the largest benzene consumption. At present, ethylbenzene is mainly used for producing styrene by an ethylbenzene gas-phase catalytic dehydrogenation process, superheated steam is added into the ethylbenzene serving as a raw material, and dehydrogenation reaction is carried out by adopting an adiabatic bed (which is more industrially applied) or a tubular isothermal bed reactor under the action of catalysts such as iron chromium oxide or zinc oxide and the like to prepare the styrene.
Styrene production requires large amounts of superheated steam, which is supplied by a furnace. The radiation section of the styrene heating furnace is generally arranged vertically and is provided with a bottom burner, and a heat transfer enhancement device is additionally arranged on a furnace tube, so that the efficiency can be improved, and the fuel can be saved.
Many of the currently applied heat transfer enhancement technologies are developed for enhancing convection heat transfer so as to improve the total heat transfer coefficient K from the tube wall of the furnace tube to the material in the furnace tube and the heat intensity q of convection heat transfer, and the formula is as follows:
wherein, δf、δeRespectively the tube wall thickness of the furnace tube, the thickness of the viscous flow boundary layer and the thickness of the coking boundary layer, lambda and lambdaf、λe、αtRespectively the heat conductivity coefficient of the tube wall of the furnace tube, the heat conductivity coefficient of the stagnant flow boundary layer, the heat conductivity coefficient of the coking boundary layer and the heat conductivity coefficient of the material, TWAnd TtThe temperature of the tube wall of the furnace tube and the temperature of the materials in the tube are respectively.
At present, the tubular heat transfer enhancement device mainly increases the degree of fluid turbulence and expands the heat transfer area by the shape of a heat transfer surface or adding a member in the tube so as to improve the heat transfer efficiency and save energy. Compared with the commonly used tubular enhanced heat transfer device, fins are arranged in the tubular enhanced heat transfer device, the inner finned tube is processed by a special welding process and equipment, the heat exchange process of fluid in the tube is unidirectional forced convection heat exchange, and the welding and processing of the fins have great influence on heat transfer; the other is to insert an insert in the pipe, and the insert in the pipe can play a good role in enhancing the heat transfer of gas, low Reynolds number fluid or high viscosity fluid under the working condition of low Reynolds number or high viscosity fluid heat transfer of the heat transfer device with the structure; the other type is a contraction and expansion pipe which is composed of a plurality of sections of gradually reducing sections and gradually expanding sections which are sequentially alternated, and the contraction and expansion pipe enables the fluid pressure to be periodically changed through the contraction and expansion of the pipe wall to generate violent vortexes to wash a fluid boundary layer so as to thin the boundary layer and increase the heat transfer coefficient.
Although the tubular enhanced heat transfer device has a wide variety of applications, the existing devices have high difficulty in processing and manufacturing, high cost and long-term operation as a bottleneck.
Disclosure of Invention
The invention aims to provide a styrene heating furnace, which has better heat exchange effect by strengthening a heat transfer element.
In order to achieve the above object, the present invention provides a styrene heating furnace comprising a radiation section having a heat exchange tube, wherein the heat exchange tube is provided therein with a heat transfer enhancement element comprising a twisted piece having a hole.
Preferably, at least one of a first enhanced heat transfer element, a second enhanced heat transfer element, a third enhanced heat transfer element, a fourth enhanced heat transfer element and a fifth enhanced heat transfer element is arranged in the heat exchange tube, wherein,
the first enhanced heat transfer element comprises a first twisted piece having a vertical hole formed therethrough from an upper side to a lower side of the first twisted piece in an axial direction of the heat exchange tube;
the second enhanced heat transfer member includes the first twisted piece and a first sleeve disposed in the first twisted piece, an inner edge of the first twisted piece being connected to an outer surface of the first sleeve;
the third intensive heat transfer element includes a second twisted piece having a cross hole whose edge is closed formed through a surface of the second twisted piece;
the fourth intensive heat transfer element includes the first twisted pieces and/or the second twisted pieces arranged perpendicular to each other in cross section;
the fifth enhanced heat transfer member includes two first twisted pieces arranged perpendicular to each other in cross section, and a second sleeve arranged among the two first twisted pieces, and an inner edge of at least one of the two first twisted pieces is connected to an outer surface of the second sleeve.
Preferably, the first and/or second and/or third and/or fourth and/or fifth enhanced heat transfer elements are symmetrical about the centerline of the heat exchange tube.
Preferably, the first sleeve and/or the second sleeve are cylindrical tubes, and the center lines of the cylindrical tubes coincide with the center line of the heat exchange tube.
Preferably, a section of the second twisted piece is made at the center of the cross hole, and a projection of the cross hole on the section is circular.
Preferably, the number of the heat transfer enhancement elements arranged in the heat exchange tube is 1-24.
Preferably, the number of the heat transfer enhancement elements is 2-10
Preferably, a plurality of the heat transfer enhancement elements are arranged in the heat exchange tube, and the axial distance between every two adjacent heat transfer enhancement elements is greater than or equal to 15D and less than or equal to 75D.
Preferably, the axial distance between the adjacent heat transfer enhancement elements is greater than or equal to 25D and less than or equal to 50D
Preferably, the diameter of the vertical hole of the first enhanced heat transfer element is 0.05D or more and 0.95D or less.
Preferably, the diameter of the vertical hole of the first enhanced heat transfer element is 0.05D or more and 0.8D or less.
Preferably, the diameter of the second enhanced heat transfer element vertical hole and/or the diameter of the first sleeve and/or the second sleeve is greater than or equal to 0.05D and less than or equal to 0.95D.
Preferably, the diameter of the second enhanced heat transfer element vertical hole and/or the diameter of the first sleeve and/or the second sleeve is greater than or equal to 0.05D and less than or equal to 0.8D.
Preferably, the ratio of the area of the cross hole to the area of the entire second twisted piece is 0.05 or more and 0.95 or less, and preferably 0.05 or more and 0.8 or less.
Preferably, the ratio between the axial length of the enhanced heat transfer element along the heat exchange tube and the diameter of the heat exchange tube is 1 to 10.
Preferably, the ratio between the axial length of the enhanced heat transfer element along the heat exchange tube and the diameter of the heat exchange tube is 1 to 6.
Preferably, the rotation angle of the heat transfer enhancement element is 90-1080 °.
Preferably, the rotation angle of the heat transfer enhancement element is 120-360 °.
Preferably, the heat transfer enhancement element and the heat exchange tube are cast or welded or forged.
Preferably, the heat transfer enhancement element is the same material as the tubes of the heat exchange tubes, or the heat transfer enhancement element is a material that is more thermally conductive than the tubes of the heat exchange tubes.
The invention also provides the application of the styrene heating furnace in the chemical field.
Through the technical scheme, the enhanced heat transfer element is arranged in the heat exchange tube of the radiation section of the styrene heating furnace, so that the flow form of fluid in the heat exchange tube is changed, the intensity of turbulent flow is increased, the original boundary layer of heat transfer is thinned, and the heat transfer performance of the styrene heating furnace is improved. Meanwhile, the overall performance of the styrene heating furnace is improved.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings:
FIG. 1 is a cross-sectional view of a heat exchange tube having a first enhanced heat transfer element;
FIG. 2 is a side view of the heat exchange tube shown in FIG. 1, wherein the heat exchange tube is assumed to be transparent so that a structural view of the first enhanced heat transfer element within the heat exchange tube can be seen;
FIG. 3 is a cross-sectional view of a heat exchange tube having a second enhanced heat transfer element;
FIG. 4 is a side view of the heat exchange tube as shown in FIG. 3, wherein the heat exchange tube is assumed to be transparent so that the structural view of the second enhanced heat transfer element within the heat exchange tube can be seen;
FIG. 5 is a cross-sectional view of a heat exchange tube having a third enhanced heat transfer element;
FIG. 6 is a side view of the heat exchange tube as shown in FIG. 5, wherein the heat exchange tube is assumed to be transparent so that a structural view of the third enhanced heat transfer element within the heat exchange tube can be seen;
FIG. 7 is a schematic view of an ethylene heating furnace according to the present invention.
Description of the reference numerals
1 first twisted piece 2 second twisted piece
3 first sleeve 10 heat exchange tube
20 chimney 21 convection section
22 radiant section 23 burner
Detailed Description
The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
In the present invention, the use of the terms of orientation such as "upper, lower, left and right" in the case where no description is made to the contrary generally refers to the orientation of the heat exchange tube and the styrene heating furnace of the present invention in the operating condition, that is, the orientation shown in the drawings.
The invention provides a styrene heating furnace, which comprises a radiation section, wherein the radiation section is provided with a heat exchange tube 10, an enhanced heat transfer element is arranged in the heat exchange tube 10, the enhanced heat transfer element comprises a twisted piece, and the twisted piece is provided with a hole.
In a styrene furnace, as shown in FIG. 7, a radiant section 22 is used to heat the feedstock. In general, the twisted piece can be understood as a curved surface of a trajectory through which a line segment in a horizontal direction rotates about its own midpoint while translating upward or downward in a vertical direction, and in a cross section of a portion of a tube section of the heat exchange tube 10 where the twisted piece is disposed, a cross section of the twisted piece is always a diameter of a section circle of the heat exchange tube 10. The twisted piece includes a pair of upper and lower sides parallel to each other, which are equal to the diameter of the heat exchange tube 10, and a pair of twisted sides, which are always in contact with the tube wall of the heat exchange tube 10.
The heat exchange tube 10 provided with the enhanced heat transfer element comprising the twisted piece can reduce the boundary layer of the fluid by utilizing the rotation of the fluid, so as to achieve the purpose of enhanced heat transfer. In the heat exchange tube 10 of the radiation section of the styrene heating furnace of the present invention, the twisted piece has a hole, so that the heat transfer effect is improved, the resistance to the fluid flowing through the heat exchange tube 10 is reduced, and the coke cleaning is convenient.
In combination with the above formulas (1) and (2), after the heat exchange tube 10 of the radiation section of the styrene heating furnace is provided with the enhanced heat transfer element, the fluid flow form in the tube is changed from piston flow to rotational flow, so that a great tangential velocity is generated, a strong scouring force is applied to a boundary layer, a stagnant flow boundary layer is reduced, and the coking amount of a furnace tube is reduced. Wherein deltafAnd deltaeThe value of (a) decreases, so the value of the overall heat transfer coefficient K increases.
Through the technical scheme, the enhanced heat transfer element is arranged in the heat exchange tube of the radiation section of the styrene heating furnace, so that the flow form of fluid in the heat exchange tube is changed, the intensity of turbulent flow is increased, the original boundary layer of heat transfer is thinned, and the heat transfer performance of the styrene heating furnace is improved. Meanwhile, the rate of forming dirt on the tube wall is reduced, the cleaning period of the furnace tube is prolonged, the coke cleaning operation can be conveniently carried out, and the overall performance of the styrene heating furnace is improved.
Preferably, at least one of a first enhanced heat transfer element, a second enhanced heat transfer element, a third enhanced heat transfer element, a fourth enhanced heat transfer element and a fifth enhanced heat transfer element is disposed in the heat exchange tube 10, wherein,
the first enhanced heat transfer element comprises a first twisted piece 1, the first twisted piece 1 having a vertical hole formed therethrough from an upper side to a lower side of the first twisted piece 1 in an axial direction of the heat exchange tube 10;
the second enhanced heat transfer member includes the first twisted piece 1 and a first sleeve 3 disposed in the first twisted piece 1, an inner edge of the first twisted piece 1 being connected to an outer surface of the first sleeve 3;
the third intensive heat transfer element comprises a second twisted piece 2, wherein the second twisted piece 2 is provided with a cross hole with closed edges formed through the surface of the second twisted piece 2;
the fourth intensive heat transfer element comprises the first twisted piece 1 and/or the second twisted piece 2 arranged perpendicular to each other in cross section;
the fifth enhanced heat transfer member includes two first twisted pieces 1 arranged perpendicular to each other in cross section and a second sleeve arranged among the two first twisted pieces 1, and an inner edge of at least one of the two first twisted pieces 1 is connected to an outer surface of the second sleeve.
According to different arrangement modes of the holes on the twisted piece, a first enhanced heat transfer element, a second enhanced heat transfer element, a third enhanced heat transfer element, a fourth enhanced heat transfer element and a fifth enhanced heat transfer element are provided in the invention, and the five enhanced heat transfer elements are respectively described below.
The first enhanced heat transfer element comprises a first twisted piece 1, as shown in fig. 1 and 2, the first twisted piece 1 is provided with a first vertical hole penetrating from the upper side to the lower side of the first twisted piece 1 in the axial direction of the heat exchange tube 10, so that the first twisted piece 1 is divided into two twisted portions by being cut from the middle, that is, in the cross section of the tube section of the portion of the heat exchange tube 10 where the first enhanced heat transfer element is provided, the cross section of the first twisted piece 1 is two line segments connecting the circumference on the diameter of the cross section circle of the heat exchange tube 10.
For a common heat exchange tube, the main thermal resistance of fluid heat exchange in the tube is concentrated in a low-speed area at the bottom layer of a laminar flow, but for the heat exchange tube provided with the first enhanced heat transfer element, the piston flow of the fluid in the tube is converted into a rotating flow, so that the tangential speed is improved, the original laminar flow layer is damaged, the boundary layer is thinned, the heat transfer coefficient is increased, and the heat transfer effect of the heat exchange tube is improved.
And, because the first twisted piece 1 is provided with vertical holes, a hydraulic coke cleaning head and a descaling head can be inserted into the heat exchange tube to perform mechanical coke cleaning and descaling.
Therefore, by adopting the technical scheme, the vertical hole can reduce the resistance and improve the heat transfer coefficient, and can be used for mechanical decoking, so that the heat transfer efficiency of the styrene heating furnace is enhanced, the coking rate and the scaling rate of the radiation section of the styrene heating furnace are reduced, the mechanical decoking and descaling can be carried out under the condition of stopping, and the practicability of the industrial process is ensured.
The second enhanced heat transfer member includes a first twisted piece 1 and a first sleeve 3, and as shown in fig. 3 and 4, an outer surface of the first sleeve 3 is connected to an inner edge of the first twisted piece 1 of the second enhanced heat transfer member. That is, the first sleeve 3 is disposed inside the heat exchange tube 10, and a partially twisted piece separated by a vertical hole is connected between the heat exchange tube 10 and the first sleeve 3.
The second heat transfer enhancement element is equivalent to the first sleeve 3 arranged in the first heat transfer enhancement element, so the principle of enhancing the heat transfer efficiency is the same, and the second heat transfer enhancement element also has the effect of reducing the coking rate and the structure rate. The first sleeve 3 mainly plays a role in enhancing the strength of the framework, and prevents the heat exchange tube 10 from damaging the twisted piece after long-term use.
The third intensive heat transfer element includes a second twisted piece 2, and the second twisted piece 2 is provided with a closed-edge cross hole formed through the surface of the second twisted piece 2, as shown in fig. 5 and 6.
The opening direction of the transverse hole in the second twisted piece 2 of the third reinforced heat transfer element is different from that of the vertical hole in the first twisted piece 1, and the transverse hole can pass through fluid flowing in the axial direction and can also pass through fluid flowing in the radial direction, so that the flow direction of the fluid can be changed, the original laminar flow is damaged, the heat transfer coefficient is increased, and the heat transfer effect of the heat exchange tube is improved. And the transverse holes on the twisted pieces can vertically correspond along the axial direction, so that the transverse holes can be communicated along the axial direction, and the mechanical decoking and hydraulic decoking operations are facilitated.
The fourth intensive heat transfer element includes two first twisted pieces 1, or two second twisted pieces 2, or one first twisted piece 1 and one second twisted piece 2, which are arranged perpendicular to each other in cross section. In all the cross sections of the portion of the heat exchange tube 10 where the fourth intensive heat transfer element is disposed, the straight lines where the sectional lines of the two first twisted pieces 1 are located are perpendicular to each other.
It should be noted that, when the fourth intensive heat transfer element includes two first twisted pieces 1 arranged perpendicular to each other in cross section, the diameters of the vertical holes of the two first twisted pieces 1 are not necessarily the same, and the positions where the vertical holes are arranged are not necessarily the same. That is, the two first twisted pieces 1 in the fourth intensive heat transfer element are not necessarily the same.
The fifth enhanced heat transfer member includes two first twisted pieces 1 arranged perpendicular to each other in cross section and a second sleeve arranged among the first twisted pieces 1, and an inner edge of at least one of the two first twisted pieces 1 is connected to an outer surface of the second sleeve.
Since the diameters of the vertical holes of the two first twisted pieces 1 are not necessarily the same and the positions where the vertical holes are arranged are not necessarily the same, the diameter and the position of the second sleeve may be such that the inner edge of at least one of the two twisted pieces is connected to the outer surface of the second sleeve.
It should be noted that, in the heat exchange tube 10 of the present invention, the heat transfer enhancement element is preferably at least one of a first heat transfer enhancement element, a second heat transfer enhancement element, a third heat transfer enhancement element, a fourth heat transfer enhancement element and a fifth heat transfer enhancement element, so the number of the heat transfer enhancement elements in the heat exchange tube 10 is at least two, and the two heat transfer enhancement elements may be any two of the first heat transfer enhancement element, the second heat transfer enhancement element, the third heat transfer enhancement element, the fourth heat transfer enhancement element and the fifth heat transfer enhancement element. When the number of the heat transfer enhancement elements in the heat exchange tube 10 is more than two, the number of the heat transfer enhancement elements is only required to be more than two, the type and the arrangement sequence of the specific heat transfer enhancement elements are not limited, and the intervals between the heat transfer enhancement elements are not necessarily the same, and can be set arbitrarily according to the needs.
Moreover, the heat exchange tube with the heat transfer enhancement element is integrally formed by vacuum metallurgy investment casting, or is processed into two parts by adopting a forging method, or is processed by adopting a welding method, and the strength requirement of the heat exchange tube in practical application can be met.
Preferably, the first and/or second and/or third and/or fourth and/or fifth enhanced heat transfer elements are symmetrical with respect to the center line of the heat exchange tube 10.
In the present preferred embodiment, the remaining portion after the hole is formed on the twisted piece of one or more of the first, second, third, fourth and fifth enhanced heat transfer elements is symmetrical with respect to the center line of the heat exchange tube 10. That is, for the first and second twisted pieces 1 and 2, the remaining portions after the formation of the vertical holes and the transverse holes are separated from each other and symmetrical, and for the second and fifth enhanced heat transfer elements, the remaining portions after the formation of the corresponding holes are connected together by the first sleeve 3 or the second sleeve, wherein the center of the vertical hole is on the center line of the heat exchange tube 10, and the vertical hole is also symmetrical with respect to the center line. Such a symmetrical structure enables each enhanced heat transfer element in the heat exchange tube 10 to be uniformly subjected to the force of the fluid.
Preferably, the first sleeve 3 and/or the second sleeve is a cylindrical tube, and the center line of the cylindrical tube coincides with the center line of the heat exchange tube 10.
More preferably, for the second and fifth enhanced heat transfer elements, the first and/or second sleeves 3, preferably are cylindrical tubes, that is to say the vertical bores are circular in a top view of the heat exchange tube 10.
Preferably, a section of the second twisted piece 2 is made at the center of the cross hole, and the projection of the cross hole on the section is circular.
For the cross hole of the third intensive heat transfer element, the edge of the cross hole is not on a plane because the second twisted piece 2 is a curved surface. In a preferred embodiment, the cross-section of the twisted piece is made at the center of the cross-hole, and the projection of the cross-hole on the cross-section is circular.
Preferably, the number of the heat transfer enhancement elements arranged in the heat exchange tube 10 is 1-24. More preferably, the number of the heat transfer enhancement elements is 2-10. Preferably, a plurality of the heat transfer enhancement elements are arranged in the heat exchange tube 10, and the axial distance between adjacent heat transfer enhancement elements is greater than or equal to 15D and less than or equal to 75D. More preferably, the axial distance between adjacent heat transfer enhancement elements is 25D or more and 50D or less.
The heat transfer enhancement elements may be disposed over the entire length of the heat exchange tube 10, or may be disposed on the heat exchange tube 10 in sections, and the heat transfer enhancement elements may be uniformly disposed or non-uniformly disposed according to the requirement, which is not limited in the present invention. The axial distance between the adjacent heat transfer enhancement elements is more than or equal to 15D and less than or equal to 75D. More preferably, the axial distance between adjacent heat transfer enhancement elements is 25D or more and 50D or less. The fluid in the pipe is changed from piston flow to rotary flow in a subsection mode, and heat transfer efficiency is improved. The preferred embodiment is provided in accordance with the general scope of the length of the heat exchange tube 10, the invention is not limited thereto, and any number of the enhanced heat transfer elements and the axial spacing thereof in accordance with the length of the heat exchange tube 10 are within the scope of the invention.
Moreover, it should be noted that, since the enhanced heat transfer element in the heat exchange tube 10 of the present invention is preferably at least one of the first enhanced heat transfer element, the second enhanced heat transfer element, the third enhanced heat transfer element, the fourth enhanced heat transfer element and the fifth enhanced heat transfer element, the number of the enhanced heat transfer elements in the heat exchange tube 10 is at least two, and the two enhanced heat transfer elements may be any two of the first enhanced heat transfer element, the second enhanced heat transfer element, the third enhanced heat transfer element, the fourth enhanced heat transfer element and the fifth enhanced heat transfer element. When the number of the heat transfer enhancement elements in the heat exchange tube 10 is more than two, the number of the heat transfer enhancement elements is only required to be more than two, the type and the arrangement sequence of the specific heat transfer enhancement elements are not limited, and the intervals between the heat transfer enhancement elements are not necessarily the same, and can be set arbitrarily according to the needs.
Preferably, the diameter of the vertical hole of the first enhanced heat transfer element is 0.05D or more and 0.95D or less. More preferably, the diameter of the vertical hole of the first enhanced heat transfer element is 0.05D or more and 0.8D or less. Preferably, the diameter of the vertical hole of the second enhanced heat transfer element and/or the diameter of the first sleeve 3 and/or the second sleeve is 0.05D or more and 0.95D or less. More preferably, the diameter of the second enhanced heat transfer element vertical hole and/or the diameter of the first sleeve 3 and/or the second sleeve is 0.05D or more and 0.8D or less. Preferably, the ratio of the area of the cross hole to the area of the entire second twisted piece is 0.05 or more and 0.95 or less, and preferably 0.05 or more and 0.8 or less.
In the preferred embodiment, preferred numerical ranges for the diameters of the vertical bores of the first enhanced heat transfer elements, the vertical bores of the second enhanced heat transfer elements, the first jacket tube 3, the second jacket tube and the transverse bore are given. The numerical range of the above diameter is set according to general experience. Because mechanical cleaning and descaling is to be performed, the minimum value of the diameter of the hole should be such that the cleaning and descaling heads can extend into the heat exchange tube 10. For example, the diameter of the existing minimum coke cleaning head is e.g. 5mm, i.e. the corresponding hole diameter is 5 mm.
Preferably, the ratio between the axial length of the enhanced heat transfer element along the heat exchange tube 10 and the diameter of the heat exchange tube 10 is 1 to 10, preferably 1 to 6. Preferably, the rotation angle of the heat transfer enhancement element is 90-1080 degrees, preferably 120-360 degrees.
Generally, the ratio of the axial length to the diameter of the twisted piece twisted by 180 ° is a twist ratio which determines the length of each enhanced heat transfer element, and the rotation angle of the enhanced heat transfer element determines the degree of twist of the enhanced heat transfer element, thereby affecting the heat transfer efficiency. The twist ratio of the heat transfer enhancing element can be adjusted according to actual conditions, and the preferred range in the normal case is given only and the protection scope of the invention is not limited. The rotation angle of the heat transfer enhancement element has an influence on the degree of the fluid rotating flow in the pipe, and the larger the rotation angle is, the larger the tangential velocity of the fluid is under the premise of the same torsion ratio. The invention is not limited to the above-mentioned values of the rotation angle, however, and any suitable value of the rotation angle may be used in the invention.
Preferably, the heat transfer enhancement element and the heat exchange tube 10 are cast or welded or forged. That is, in the preferred embodiment of the present invention, the enhanced heat transfer element and the heat exchange tube 10 may be integrally formed or may be coupled to each other, and the present invention does not limit the method of integrally forming or coupling the enhanced heat transfer element and the heat exchange tube 10.
Preferably, the material of the enhanced heat transfer element is the same as that of the tube body of the heat exchange tube 10, or the material of the enhanced heat transfer element is more thermally conductive than that of the tube body of the heat exchange tube 10. The materials of the enhanced heat transfer element and the heat exchange tube 10 are not limited in the present invention, but in the present preferred embodiment, the enhanced heat transfer element is made of a material having a thermal conductivity better than or equal to that of the tube body of the heat exchange tube 10.
The invention also provides the application of the styrene heating furnace in the chemical field. The following examples are given.
Example 1
Taking a styrene heating furnace of 8.5 ten thousand tons/year as an example, the radiation section of the styrene heating furnace comprises an A section and a B section, the A section and the B section have the same function, but the positions in the styrene heating furnace are different; the structures are basically the same and slightly different in size. The styrene furnace is modified according to a preferred embodiment of the present invention. Under the same process conditions, a comparative experiment was carried out using a styrene heating furnace according to the prior art (no twisted piece was provided in the heat exchange tube of the radiant section) and a styrene heating furnace according to the present invention, and the process data of the experimental results are shown in table 1, from which it can be seen that the outlet temperature increased after using a styrene heating furnace according to the present invention.
Table 1 data of comparative experiments
Example 2
Still using the apparatus used in example 1, the experimental results of this time without changing the inlet and outlet temperatures of the furnace tube, compared to the styrene furnace according to the prior art (without twisted pieces in the heat exchange tubes of the radiant section) and the styrene furnace according to the present invention, the process data are shown in table 2, and it can be seen from table 2 that the throughput is improved with the styrene furnace according to the present invention.
The preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications can be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.
It should be noted that the various technical features described in the above embodiments can be combined in any suitable manner without contradiction, and the invention is not described in any way for the possible combinations in order to avoid unnecessary repetition.
In addition, any combination of the various embodiments of the present invention is also possible, and the same should be considered as the disclosure of the present invention as long as it does not depart from the spirit of the present invention.
Claims (22)
1. A styrene heating furnace comprising a radiant section having a heat exchange tube (10), characterized in that the heat exchange tube comprises a twisted sheet tube section, the heat exchange tube (10) is provided therein with a heat transfer enhancement element comprising a first heat transfer enhancement element provided inside the twisted sheet tube section, the first heat transfer enhancement element is a first twisted sheet (1), the first twisted sheet (1) is a trace curved surface through which a line segment in a horizontal direction rotates about its own midpoint while also translating upward or downward in a vertical direction of the heat exchange tube (10), and in a cross section of a portion of the tube section of the heat exchange tube (10) provided with the first twisted sheet, a cross section of the first twisted sheet is always an inner diameter of a cross-sectional circle of the heat exchange tube (10), wherein the first twisted sheet (1) comprises a pair of upper and lower side edges which are parallel to each other, and a pair of twisted sides having an upper side and a lower side equal to the diameter of the heat exchange tube (10), both of the twisted sides being in contact with the inner wall of the heat exchange tube (10) at all times, the first twisted piece (1) having a vertical hole formed therethrough from the upper side to the lower side of the first twisted piece (1) in the axial direction of the heat exchange tube (10) to divide the first twisted piece (1) into two twisted portions, wherein the heat exchange tube has a diameter D.
2. The styrene heating furnace according to claim 1, wherein the heat transfer enhancement member further comprises at least one of a second heat transfer enhancement member, a third heat transfer enhancement member, a fourth heat transfer enhancement member, and a fifth heat transfer enhancement member, wherein,
the second enhanced heat transfer element comprises the first twisted piece (1) and a first sleeve (3) arranged in the first twisted piece (1), wherein the inner edge of the first twisted piece (1) is connected with the outer surface of the first sleeve (3);
the third enhanced heat transfer element comprises a second twisted piece (2), wherein the second twisted piece (2) is provided with a cross hole which is formed through the surface of the second twisted piece (2) and is closed at the edge;
the fourth intensive heat transfer element comprises the first twisted piece (1) and/or the second twisted piece (2) arranged perpendicular to each other in cross section;
the fifth enhanced heat transfer element comprises two first twisted pieces (1) arranged perpendicular to each other in cross section and a second sleeve arranged among the two first twisted pieces (1), and the inner edge of at least one of the two first twisted pieces (1) is connected with the outer surface of the second sleeve.
3. The styrene heating furnace according to claim 2, wherein at least one of the first, second, third, fourth and fifth enhanced heat transfer elements is symmetrical with respect to a center line of the heat exchange pipe (10).
4. A styrene heating furnace according to claim 3, characterized in that the first sleeve (3) and/or the second sleeve is a cylindrical tube and the centre line of the cylindrical tube coincides with the centre line of the heat exchange tube (10).
5. A styrene heating furnace according to claim 2 or 3, characterized in that a section of said second twisted piece (2) is made at the center of said cross hole, and the projection of said cross hole on said section is circular.
6. The styrene heating furnace according to any one of claims 1 to 3, wherein the number of the heat transfer enhancement elements provided in the heat exchange tube (10) is 1 to 24.
7. The styrene heating furnace according to claim 6, wherein the number of the heat transfer enhancement elements provided in the heat exchange tube (10) is 2 to 10.
8. The styrene heating furnace according to claim 7, wherein the heat exchange tube (10) is provided with a plurality of the heat transfer enhancement elements, and an axial distance between adjacent heat transfer enhancement elements is 15D or more and 75D or less.
9. The styrene heating furnace according to claim 8, wherein an axial distance between adjacent ones of the heat transfer enhancement elements is 25D or more and 50D or less.
10. The styrene heating furnace according to claim 1, wherein the diameter of the vertical hole of the first enhanced heat transfer member is 0.05D or more and 0.95D or less.
11. The styrene heating furnace according to claim 10, wherein the diameter of the vertical hole of the first enhanced heat transfer member is 0.05D or more and 0.8D or less.
12. The styrene heating furnace according to claim 2, wherein at least one of the diameter of the second enhanced heat transfer element vertical hole provided in the heat exchange tube, the diameter of the first sleeve (3) and the diameter of the second sleeve is 0.05D or more and 0.95D or less.
13. The styrene heating furnace according to claim 12, wherein at least one of the diameter of the second enhanced heat transfer element vertical hole provided in the heat exchange tube, the diameter of the first sleeve (3) and the diameter of the second sleeve is 0.05D or more and 0.8D or less.
14. The styrene heating furnace according to claim 5, wherein a ratio of an area of the cross hole to an area of the entire second twisted piece is 0.05 or more and 0.95 or less.
15. The styrene heating furnace according to claim 14, wherein a ratio of an area of the cross hole to an area of the entire second twisted piece is 0.05 or more and 0.8 or less.
16. The styrene heating furnace according to claim 1, wherein the ratio between the axial length of the enhanced heat transfer element along the heat exchange tube (10) and the diameter of the heat exchange tube (10) is 1 to 10.
17. The styrene heating furnace according to claim 16, wherein the ratio between the axial length of the enhanced heat transfer element along the heat exchange tube (10) and the diameter of the heat exchange tube (10) is 1 to 6.
18. The styrene heating furnace according to claim 1, wherein the rotation angle of the enhanced heat transfer member is 90 to 1080 °.
19. The styrene heating furnace as claimed in claim 18, wherein the rotation angle of the enhanced heat transfer element is 120-360 °.
20. A styrene heating furnace according to claim 1 or 2, characterized in that the heat transfer enhancing element and the heat exchange tube (10) are cast or welded or forged.
21. The styrene heating furnace according to claim 1 or 2, wherein the heat transfer enhancing element is the same material as the tube body of the heat exchange tube (10) or the heat transfer enhancing element is more thermally conductive than the tube body of the heat exchange tube (10).
22. Use of a styrene furnace according to any one of claims 1 to 21 in the chemical industry.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210424587.XA CN103791483B (en) | 2012-10-30 | 2012-10-30 | Styrene heating furnace and application thereof in chemical field |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210424587.XA CN103791483B (en) | 2012-10-30 | 2012-10-30 | Styrene heating furnace and application thereof in chemical field |
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| CN103791483A CN103791483A (en) | 2014-05-14 |
| CN103791483B true CN103791483B (en) | 2020-02-18 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201210424587.XA Active CN103791483B (en) | 2012-10-30 | 2012-10-30 | Styrene heating furnace and application thereof in chemical field |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN109724448B (en) * | 2017-10-27 | 2021-04-13 | 中国石油化工股份有限公司 | Enhanced heat transfer tube, cracking furnace and atmospheric and vacuum heating furnace |
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| US4455154A (en) * | 1982-04-16 | 1984-06-19 | The United States Of America As Represented By The United States Department Of Energy | Heat exchanger for coal gasification process |
| CN202063878U (en) * | 2010-12-04 | 2011-12-07 | 卓然(靖江)设备制造有限公司 | Novel twisted slice tube of heating furnace |
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| US4163474A (en) * | 1976-03-10 | 1979-08-07 | E. I. Du Pont De Nemours And Company | Internally finned tube |
| JPH07284642A (en) * | 1994-04-19 | 1995-10-31 | Hisao Kojima | Mixing element and production therefor |
| CN1133862C (en) * | 1998-09-16 | 2004-01-07 | 中国石油化工集团公司 | Heat exchange pipe and its manufacture method and application |
| CN100473936C (en) * | 2005-03-17 | 2009-04-01 | 西安交通大学 | Forced heat exchange tube |
| EP2133644B1 (en) * | 2007-03-28 | 2019-08-07 | China Petroleum & Chemical Corporation | A tube type cracking furnace |
| CN101846469A (en) * | 2009-03-26 | 2010-09-29 | 中国石油化工股份有限公司 | Heat exchanger with twisted sheet |
| CN101893396B (en) * | 2009-05-21 | 2012-10-24 | 中国石油化工股份有限公司 | Quenching boiler provided with enhanced heat transfer member |
| CN102095332A (en) * | 2011-02-24 | 2011-06-15 | 华东理工大学 | Heat exchange tube internally provided with spiral fins and application thereof |
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| US4455154A (en) * | 1982-04-16 | 1984-06-19 | The United States Of America As Represented By The United States Department Of Energy | Heat exchanger for coal gasification process |
| CN202063878U (en) * | 2010-12-04 | 2011-12-07 | 卓然(靖江)设备制造有限公司 | Novel twisted slice tube of heating furnace |
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| CN103791483A (en) | 2014-05-14 |
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