An industrial furnace with a high-efficiency, low-resistance tube sheet

Abstract

This invention relates to the field of petrochemical industrial furnace technology, specifically to an industrial furnace with a high-efficiency, low-resistance tube sheet, comprising a furnace wall, end tube sheets, intermediate tube sheets, and coils. The intermediate tube sheet is a high-efficiency tube sheet with the function of reducing flue gas resistance, comprising vertical plates, horizontal plates, frame plates, and supports. Multiple horizontal plates are arranged longitudinally on the side walls of the vertical plates, the frame plates are fixed to the sides of the vertical plates, and the supports are fixed to the frame plates, thereby supporting the vertical plates in the furnace chamber. A flow-forward arc structure is provided at the intersection corner between the lower sides of the vertical plates and the horizontal plates. The flow-forward arc structure is staggered from the furnace tubes. The flow-forward arc structure guides the flue gas smoothly from bottom to top through the horizontal plates, avoiding the vertical impact of the flue gas on the horizontal plates, reducing the swirl of the flue gas, and reducing energy consumption. The surface of the flow-forward arc structure is provided with spaced-distributed ridged flanges, which have the function of guiding the flue gas horizontally to the lower part of the furnace tubes, improving the heat exchange effect.

Description

Technical Field

[0001] This invention relates to the field of petrochemical industrial furnace technology, and more particularly to equipment for heat exchange of fluid media in petroleum refining, petrochemical, coal chemical and other chemical processes, specifically to an industrial furnace with a high-efficiency, low-resistance tube sheet. Background Technology

[0002] (1) Structural design and function of traditional heating furnaces

[0003] The heating furnace is the heart of oil refining and petrochemical plants. The function of the tubular heating furnace is to heat the medium (oil or gas) inside the tube to the temperature required by the process.

[0004] The furnace body is surrounded by tall furnace walls forming the furnace chamber. These walls are constructed from I-beams and other shaped steel frames topped with welded steel plates. Insulation nails are welded onto the steel plates, and heat-insulating and wear-resistant materials are cast between these nails. Lugs installed on the side furnace walls support the tube sheets. The furnace tubes pass through the tube sheets with support holes and are supported by the tube sheets. The oil to be heated flows inside the furnace tubes. Outside the furnace tubes, a mixture of high-temperature flue gas and hot air blown by a large fan flows vertically upwards (or horizontally from left to right or right to left) within the furnace chamber. Heat is transferred to the oil inside the tubes through the tube walls. Generally, to fully balance and utilize various heat sources, a heating furnace typically consists of a bottom radiant section, an upper convection section, a top chimney, and surrounding auxiliary facilities. The convection section is composed of multiple identical modules stacked vertically. To save internal space and reduce the overall height of the heating furnace, the convection section modules are usually rectangular in shape. The distance B between the tube sheet lugs on both sides of the furnace wall is also the span of the tube sheet. n tube sheets with a thickness (width) of b are supported on a corresponding pair of lugs.

[0005] In order to increase the pressure head of the flue gas flowing from bottom to top in the furnace cavity, the chimneys at the top of the furnace are becoming increasingly taller. The lower air pressure at the top of the chimney increases the suction force on the flue gas and maintains the kinetic energy of the flue gas. This kinetic energy loss has a significant impact on the operating cost and production efficiency of industrial furnaces, but it is also limited by various factors to a certain extent.

[0006] (2) Tube sheets of traditional heating furnaces and their problems

[0007] With the long-term development of the social economy, on the one hand, the quality of extracted crude oil is becoming increasingly inferior, and refining and chemical processes are developing towards high-temperature and high-pressure deep processing. Industrial furnaces are transitioning from heating to reaction functions, and the temperatures experienced by the tube sheets are increasing. On the other hand, energy demand is surging, and industrial furnaces are developing towards large-scale production. Existing regulations strictly prohibit the construction of new atmospheric and vacuum distillation furnaces with a capacity of less than 10 million tons / year and naphtha cracking to ethylene production with a capacity of less than 800,000 tons / year. Similar requirements exist for the lower capacity limits of other petrochemical plants. Large-scale production requires increasingly larger industrial furnaces. Large-span furnace chambers require wide tube sheets to support the furnace tubes. The overall stress characteristics of wide tube sheets in the width direction are compressive stress at the top and tensile stress at the bottom. Traditional tube sheet designs cannot meet the requirements of economical construction. In 2015, the article "High-level Development of Large Heating Furnaces Promotes the Progress of Modular Manufacturing Technology [J]. Petrochemical Equipment Technology, 2015, 36(1): 28-33" reported that there were already domestic casting tube sheets with a width of 4.6m, a height of 2.0m, and a horizontal arc plate height of 0.25m on each side. The length of such furnace tubes is not less than 24m. According to the usual regulations, a tube sheet with a vertical plate thickness of 0.03m is arranged at a 4m interval, requiring a total of 5 tube sheets. When the flue gas flowing from the bottom of the industrial furnace encounters such a large-sized intermediate tube sheet, it will impact the structure at the bottom of the tube sheet with a total area of ​​B×b×n. The total area is calculated to be 4.6m×[(2×0.25m)+0.03m]×5=12.19m. 2 This area already occupies 4.6m × 24m = 110.4m² of the inner cross-sectional area of ​​the furnace cavity. 2 It's more than 11%. Besides the bottom area of ​​the tube sheet, the sidewalls of each layer of furnace tube support holes on the vertical plate are usually equipped with horizontal plates, which also create significant resistance to the flow of flue gas. Such a large obstructing area results in a non-negligible increase in the kinetic energy and pressure head lost during flue gas flow.

[0008] Therefore, improving the existing tube sheet structure can not only reduce its impact on flue gas resistance and lower equipment operating costs, but also improve the casting conditions of the casting process, save equipment manufacturing costs, and improve the economic efficiency of industrial furnaces, which has strong practical significance. Summary of the Invention

[0009] In view of the above-mentioned technical problems in the existing technology, the present invention provides an industrial furnace with a high-efficiency, low-resistance tube sheet.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] An industrial furnace with a high-efficiency, low-resistance tube sheet is provided, comprising a furnace wall, end tube sheets, intermediate tube sheets, and coils. The end tube sheets are fixed to both ends of the furnace wall to form the furnace chamber. Multiple intermediate tube sheets are arranged separately in the furnace chamber. The coils include multiple furnace tubes and multiple elbows. The furnace tubes pass through support holes supported by the intermediate tube sheets and end tube sheets. The elbows connect the multiple furnace tubes. The two ends of the furnace tubes extend out of the furnace chamber. The furnace wall is provided with a flue gas inlet and a flue gas outlet to allow flue gas to flow from bottom to top in the furnace chamber.

[0012] Each central tube sheet includes a vertical panel, horizontal panels, a frame plate, and supports. Multiple horizontal panels are arranged longitudinally on the side wall of the vertical panel, and the horizontal panels are staggered from the support holes of the central tube sheet. The frame plate is fixed to the side of the vertical panel, and the supports are fixed to the frame plate, thereby supporting the vertical panel in the furnace. Its characteristic is:

[0013] At the intersection corner between the lower sides of the vertical plate and the horizontal plate, there is a flow-through arc structure. The flow-through arc structure is staggered from the furnace tube. The surface of the flow-through arc structure is provided with spaced ridged flanges to guide the heat exchange fluid from bottom to top to the furnace tube on the side.

[0014] As a preferred embodiment, the frame plate is fixed to the lateral side of the vertical plate and offset from the bottom of the vertical plate, and the bottom of the vertical plate is provided with a wedge-shaped windward end that is thinner at the bottom and thicker at the top.

[0015] As a preferred embodiment, the wedge-shaped windward end is integrally cast into the vertical plate.

[0016] As a preferred embodiment, the wedge-shaped windward end assembly is fixed to the vertical banner.

[0017] As a preferred embodiment, the frame plate is also arranged on top of the horizontal banner plate, and the downstream arc structure is also provided between the frame plate and the vertical banner plate at this position.

[0018] As a preferred embodiment, the surface of the angular flange is provided with a flow guide groove.

[0019] As a preferred embodiment, the downstream arc structure has an arc shape that curves inward toward the corner.

[0020] As a preferred embodiment, the downstream arc structure, the horizontal plate, and the vertical plate are integrated into a single structure, or they are welded together, or they are assembled.

[0021] As a preferred embodiment, the frame plate is integrally cast onto the banner plate; or the frame plate is formed by welding steel plates onto the banner plate.

[0022] As a preferred embodiment, the thickness of the vertical banner gradually changes from top to bottom, and / or the width of the horizontal plate at the bottom of the vertical banner is smaller than the width of the horizontal plate at the top.

[0023] The beneficial effects of this invention are:

[0024] This invention discloses an industrial furnace with a high-efficiency, low-resistance tube sheet, which, compared with existing technologies, has the following advantages: The co-current arc structure guides the flue gas smoothly upwards through the horizontal plate, avoiding vertical impact on the horizontal plate and reducing energy consumption. The angular arc flange, while ensuring the flue gas flows upwards, also guides the flue gas horizontally to the lower part of the furnace tubes, improving heat exchange efficiency. Furthermore, the angular arc flange significantly strengthens the original vertical and horizontal plates.

[0025] Further striking effects:

[0026] (1) Structurally refined: On the one hand, the two major local structures that hinder the flow of flue gas are improved: the vertical plate is only equipped with frame plates at both ends near the left and right furnace walls, and the top and bottom of the vertical plate are no longer equipped with frame plates. On the other hand, four major local structures that reduce the resistance of flue gas are added: the wedge-shaped windward end at the bottom of the intermediate tube plate, the downstream arc structure under the horizontal plate, the intermittently distributed ridged arc flange guiding structure on the downstream arc structure, and the guiding groove reinforcement structure on the surface of the ridged arc flange.

[0027] (2) Functional Aspects: The flue gas flowing upwards from the bottom of the industrial furnace does not strongly impact the bottom plane of the large-size intermediate tube plate, nor does it impact the horizontal plates and top frame. Instead, under the action of the wedge-shaped windward end at the bottom of the intermediate tube plate, it smoothly flows through both sides of the intermediate tube plate. Continuing upwards, when encountering each layer of horizontal plates, the downstream arc structure, and its ridged flanges, it does not generate strong impact vortices. Instead, under the action of the downstream arc structure, it continues to flow smoothly upwards. Simultaneously, under the guiding structure of the ridged flanges on the downstream arc structure, the flue gas flows smoothly towards the lower part of the furnace tubes, further enhancing the heat exchange effect. Therefore, it has both low resistance and high-efficiency heat exchange. Furthermore, the ridged flanges have a significant structural strengthening effect on the original vertical and horizontal plates.

[0028] (3) Quality: The new structure can also improve the casting conditions of the casting process. The structure that allows the flue gas to flow smoothly can also allow the high-temperature molten steel to flow smoothly during the casting process, reduce casting defects, improve the quality of cast steel pipe plates and the service life of long-term use at high temperatures.

[0029] In summary, the improvement of the existing intermediate tube sheet structure has significant effects and multiple benefits: it mainly improves the adverse effects on flue gas resistance, maintains the kinetic energy and pressure of flue gas, reduces equipment operating costs, extends the operating cycle of industrial furnaces, and saves equipment manufacturing costs, thereby improving the economic efficiency of industrial furnaces and having strong practical significance. Attached Figure Description

[0030] Figure 1This is a schematic diagram of a set of modules of the industrial furnace in the embodiment.

[0031] Figure 2 This is a schematic diagram of an intermediate tube sheet in an embodiment, which is the same as the existing conventional tube sheet structure.

[0032] Figure 3 This is a schematic diagram of a structure of the improved intermediate tube sheet in the embodiment.

[0033] The bottom of the banner panel has no frame plate, only an integrated wedge-shaped windward end.

[0034] Figure 4 for Figure 3 A partial structural schematic diagram of the intermediate tube sheet in the embodiment.

[0035] Figure 5 for Figure 3 Another partial structural diagram of the intermediate tube sheet in the embodiment.

[0036] Figure 6 This is a schematic diagram of another structure of the intermediate tube sheet in the embodiment.

[0037] Figure 7 for Figure 6 A partial structural diagram of the intermediate tube sheet in the embodiment shows that the top and bottom of the vertical plate have no frame plates, and the bottom has an integrated wedge-shaped windward section.

[0038] Figure 8 for Figure 3 or Figure 6 Another partial structural diagram of the intermediate tube sheet in the embodiment, another structure of DD, the vertical plate is provided with a downstream arc structure under the horizontal plate on only one side, as well as a ridge arc flange and a flow guide groove on the flange surface that play a guiding role. The small arrow bundle in the figure indicates the flow direction of the flue gas after downstream flow, guidance and enhancement.

[0039] Figure 9 This is a schematic diagram of another partial structure in the embodiment. The top and bottom of the vertical panel have no frame plates, and the bottom has a combined wedge-shaped windward end. Detailed Implementation

[0040] The present invention will be described in detail below with reference to specific embodiments and accompanying drawings.

[0041] The industrial furnace in this embodiment, such as Figure 1As shown, the furnace includes a furnace wall 1, end tube sheets 3, intermediate tube sheets 5, and coils 2. The end tube sheets 3 are fixed to both ends of the furnace wall 1, thus forming the furnace chamber. Multiple intermediate tube sheets 5 are arranged separately within the furnace chamber. The coils 2 include multiple furnace tubes 4 and multiple elbows 6. The furnace tubes 4 pass through support holes supported by the intermediate tube sheets 5 and end tube sheets 3. The elbows 6 connect the multiple furnace tubes 4, and both ends of the furnace tubes 4 extend out of the furnace chamber. The furnace wall 1 has flue gas inlets and outlets to allow flue gas to circulate from bottom to top within the furnace chamber. Figure 2 As shown, each central tube plate 5 includes a vertical plate 51, a horizontal plate 53, a frame plate 56 located on the lateral side of the vertical plate 51, a frame plate 54 located on the top of the vertical plate 51, and a support 57. Multiple horizontal plates 53 are arranged longitudinally on the side wall of the vertical plate 51, and the horizontal plates 53 are staggered from the support holes 52 of the vertical plate 51. The frame plate 56 is fixed to the side of the vertical plate 51, and the support 57 is fixed to the frame plate 56, thereby supporting the vertical plate 51 in the furnace.

[0042] During operation, the fluid to be heated flows evenly into each furnace tube 4 through a header. After flowing back and forth several times within the furnace tube 4, it is heated by the high-temperature flue gas inside the furnace, and then collected in another header before flowing out of the furnace. The above is the basic structure of an existing industrial furnace. This embodiment represents an improvement:

[0043] Combination Figure 3 and Figure 4 As shown, the intermediate tube sheet 5 is a low-resistance tube sheet. A downstream arc structure 55 is provided between the bottom surface of the frame plate 54 at the top of the vertical plate 51 and the side wall of the vertical plate 51. A downstream arc structure 531 is provided at the intersection corner between the lower side of the horizontal plate 53 and the side wall of the vertical plate 51. The downstream arc structure 531 is staggered from the support holes 52 supporting the furnace tubes to avoid interference with the arrangement of the furnace tubes 4. The downstream arc structures 531 / 55 are concave arc shapes towards the corner. The downstream arc structure 531 guides the flue gas to flow smoothly from bottom to top through the horizontal plate, avoiding vertical impact of the flue gas on the horizontal plate 53 and reducing energy consumption.

[0044] The surface of the flow-through arc structure 531 is provided with spaced-apart ridged flanges 532, which are raised and ridged arc-shaped, used to guide the heat exchange fluid from bottom to top to the side furnace tubes. The ridged flanges 532 on the sidewall of the vertical plate 51 where there are no support holes and at the intersection of the horizontal plate 53 and the flow-through arc structure 531, in addition to ensuring the flue gas flows from bottom to top, also guide the flue gas horizontally to the lower part of the furnace tube 4, improving the heat exchange effect. Furthermore, the ridged flanges 532 significantly strengthen the original vertical and horizontal plates. Figure 5 and Figure 8As shown, the surface of the angular flange 532 has guide grooves 533, which direct the flue gas to the bottom of the furnace tube 4, further enhancing the heat exchange effect. The small arrows in the figure indicate the flow direction of the flue gas after co-flow, guidance, and enhancement. In particular, according to engineering needs, the structural orientation of the guide grooves 533 on the surface of the angular flange 532 can be standardized, and the flue gas in the furnace can be guided to have an overall flow direction, forming a synergistic effect of various local structures, and maximizing co-flow, guidance, and enhancement.

[0045] Figure 3 and Figure 4 In this embodiment, frame plates 54 / 56 are fixed to the lateral sides and top of the vertical banner plate 51, but offset from the bottom of the vertical banner plate 51. That is, there is no frame plate at the bottom of the vertical banner plate 51. The absence of a frame plate at the bottom avoids obstructing the upward flow of smoke and reduces energy consumption. Alternatively, the bottom of the vertical banner plate 51 is provided with a wedge-shaped windward end 58, which is thinner at the bottom and thicker at the top. The wedge-shaped windward end 58 can minimize obstruction to the upward flow of smoke and reduce energy consumption. In practice, it can also be modified as follows... Figure 6 and Figure 7 As shown, removing the top frame plate of the vertical panel 51 also avoids the top frame plate obstructing the upward flow of smoke and further reduces energy consumption.

[0046] In actual manufacturing, it can be like Figure 3 and 4 As shown, the wedge-shaped windward end 58 is integrally cast into the vertical plate 51; it can also be modified as follows: Figure 9 As shown, the wedge-shaped windward end 58 is assembled and fixed to the bottom of the vertical plate 51 by bolts 59.

[0047] In practice, the downstream arc structure 55 / 531, the horizontal plate 53, and the vertical plate 51 are either an integrated structure, welded together, or assembled with bolts. The material and manufacturing method of the intermediate tube sheet are determined according to different working conditions to reduce costs.

[0048] In practice, the frame plate can be cast integrally with the banner plate; or the frame plate can be assembled and welded from steel plates to the banner plate.

[0049] In other embodiments, the thickness of the vertical plate 51 gradually changes from top to bottom, preferably gradually increasing; and / or the width of the horizontal plate 53 at the lower part of the vertical plate 51 is smaller than the width of the horizontal plate 53 at the upper part, where the width refers to the degree to which the horizontal plate 53 protrudes beyond the vertical plate 51. The flue gas velocity and pressure head at the lower part of the vertical plate 51 are relatively high, and the narrow horizontal plate can reduce the vertical impact of the flue gas on the horizontal plate, saving energy. The reduction in the width of the horizontal plate slightly weakens its strength in bearing the thrust of the furnace tube, but this can be compensated for by the addition of a downstream arc structure and an angular flange. The specific reduction in width can be calculated by the method of equal strength area reinforcement.

[0050] In the description of this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] All standard parts used in this invention can be purchased from the market, and irregular parts can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art, and the circuit connection adopts conventional connection methods in the prior art, which will not be described in detail here.

[0052] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An industrial furnace with a high-efficiency, low-resistance tube sheet, comprising a furnace wall, end tube sheets, intermediate tube sheets, and coils. The end tube sheets are fixed to both ends of the furnace wall to form a furnace chamber. Multiple intermediate tube sheets are arranged separately in the furnace chamber. The coils include multiple furnace tubes and multiple elbows. The furnace tubes pass through support holes supported by the intermediate and end tube sheets. The elbows connect the multiple furnace tubes. The two ends of the furnace tubes extend out of the furnace chamber. The furnace wall is provided with a flue gas inlet and a flue gas outlet to allow flue gas to flow from bottom to top in the furnace chamber. Each central tube sheet includes a vertical panel, horizontal panels, a frame plate, and supports. Multiple horizontal panels are arranged longitudinally on the side wall of the vertical panel, and the horizontal panels are staggered from the support holes of the central tube sheet. The frame plate is fixed to the side of the vertical panel, and the supports are fixed to the frame plate, thereby supporting the vertical panel in the furnace. Its characteristic is: At the intersection corner between the lower sides of the vertical plate and the horizontal plate, there is a flow-through arc structure. The flow-through arc structure is staggered from the furnace tube. The surface of the flow-through arc structure is provided with spaced ridged flanges to guide the heat exchange fluid from bottom to top to the furnace tube on the side.

2. An industrial furnace with a high-efficiency, low-resistance tube sheet according to claim 1, characterized in that: The frame plate is fixed to the lateral side of the vertical plate and offset from the bottom of the vertical plate, and the bottom of the vertical plate is provided with a wedge-shaped windward end that is thinner at the bottom and thicker at the top.

3. An industrial furnace with a high-efficiency, low-resistance tube sheet according to claim 2, characterized in that: The wedge-shaped windward end is integrally cast into the vertical plate.

4. An industrial furnace with a high-efficiency, low-resistance tube sheet according to claim 2, characterized in that: The wedge-shaped windward end assembly is fixed to the vertical plate.

5. An industrial furnace with a high-efficiency, low-resistance tube sheet according to claim 1, characterized in that: The frame plate is also arranged on the top of the horizontal plate, and the downstream arc structure is also provided between the frame plate and the vertical plate at this position.

6. An industrial furnace with a high-efficiency, low-resistance tube sheet according to claim 1, characterized in that: The surface of the ridge flange has a flow guide groove.

7. An industrial furnace with a high-efficiency, low-resistance tube sheet according to claim 1, characterized in that: The downstream arc structure has an arc shape that curves inward toward the corner.

8. An industrial furnace with a high-efficiency, low-resistance tube sheet according to claim 1, characterized in that: The aforementioned downstream arc structure, horizontal plate, and vertical plate are either an integrated structure, welded together, or assembled.

9. An industrial furnace with a high-efficiency, low-resistance tube sheet according to claim 1, characterized in that: The frame plate is integrally cast onto the vertical banner plate; or the frame plate is formed by welding steel plates onto the vertical banner plate.

10. An industrial furnace with a high-efficiency, low-resistance tube sheet according to claim 1, characterized in that: The thickness of the vertical banner gradually changes from top to bottom; and / or the width of the horizontal plate at the bottom of the vertical banner is smaller than the width of the horizontal plate at the top.

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