Composite drainage closed type spiral baffle plate heat exchanger

Abstract

A composite drainage closed type spiral baffle plate heat exchanger comprises an upper sealing head, an upper tube plate, a shell, baffle plates, heat exchange tubes, pull rods, purging branch tubes, a lower tube plate, a lower sealing head and a purging main tube. The upper sealing head, the upper tube plate, the shell, the lower tube plate and the lower sealing head are sequentially connected from top to bottom to form a main body structure of the heat exchanger. In the shell, the baffle plates are obliquely arranged, the multiple baffle plates are sequentially connected end to end in the circumferential direction from top to bottom to form an axial space closed type spiral flow channel, and the heat exchange pipes sequentially penetrate through the upper pipe plate, heat exchange pipe holes in the baffle plates and the lower pipe plate and are fixed to the upper pipe plate and the lower pipe plate. A tangential steam inlet is formed in the side face of the upper portion of the shell, the air inlet rotating direction is consistent with the rotating direction of the spiral flow channels of the baffle plates, the purging header pipe is arranged at the central axis position of the heat exchanger, the lower end is blocked, the upper end penetrates through the upper pipe plate and the side wall of the upper sealing head, and purging branch pipes are arranged at the included angle between the sector face of each baffle plate and the upper baffle plate in the axial direction of the heat exchanger.

Description

Technical Field

[0001] This application relates to the field of heat exchanger technology, and in particular to a composite flow-guiding closed spiral baffle heat exchanger. Background Technology

[0002] Compared to traditional bow-shaped baffle tube heat exchangers, spiral baffle tube heat exchangers offer advantages such as high heat exchange area utilization, low flow resistance, and high heat transfer coefficient, leading to widespread attention and application in industrial heat exchange. However, in applications involving organic vapor condensation, such as reboilers in direct-pressure heat pump distillation systems, condensers in Freon refrigeration heat pump systems, tail coolers in ORC waste heat power generation, and alkylation reactors, experimental results show that the performance difference between spiral baffle heat exchangers and conventional bow-shaped baffles is not significant. This is because traditional spiral baffles are constructed from fan-shaped plates, resulting in triangular leakage zones between adjacent baffles. These leakage zones cause short-circuiting and back-mixing of fluids in adjacent spiral channels, reducing the effective utilization of the heat exchange area. Furthermore, the secondary eddies generated when the leakage fluid mixes with the main fluid significantly increase the flow resistance of the heat exchanger. Patents CN101598510B, CN2622651Y, and CN103105075A all suffer from the aforementioned triangular leakage area problem, which affects the actual application effect of the spiral baffle.

[0003] Organic compounds have relatively low latent heat, only 15% to 40% of that of water. Therefore, their condensation produces a large amount of condensate. The condensate film near the heat exchanger tube wall significantly increases the heat transfer resistance of the heat exchanger. According to tests, when the ethanol vapor condenses, the heat transfer coefficient decreases by more than 30% when the condensate film thickness exceeds 2 mm. Compared with traditional arc-shaped baffles, the inclination angle between the spiral baffle and the heat exchanger tube helps the condensate to flow under gravity, reducing the thickness of the condensate film outside the tube to some extent. However, due to the theoretical gap between the spiral baffle tube orifice and the heat exchanger tube, under the combined effects of condensate column static pressure, flow relaxation time, and condensate drainage resistance, condensate will still leak in the annular gap between the baffle and the heat exchanger tube, resulting in severe condensate accumulation on the outer wall of the lower heat exchanger tube. Patent CN2622651Y proposes to create a venting groove on the baffle plate. However, due to the limited thickness of the baffle plate, when the condensate volume is large, the condensate will overflow from the venting groove, causing the flow to fail. Furthermore, the structure described herein cannot solve the leakage problem in the annular gap between the baffle plate and the heat exchange tube. Summary of the Invention

[0004] The present invention aims to provide a composite flow-guiding closed spiral baffle heat exchanger to overcome the shortcomings of the prior art. The technical problem to be solved by the present invention is achieved through the following technical solution.

[0005] A composite flow-guiding closed spiral baffle heat exchanger includes an upper head, an upper tube sheet, a shell, baffles, heat exchange tubes, a tie rod, a purge branch pipe, a lower tube sheet, a lower head, and a purge main pipe; The heat exchanger has a vertical cylindrical structure. The upper end cap, upper tube sheet, shell, lower tube sheet, and lower end cap are connected sequentially from top to bottom to form the main structure of the heat exchanger. The baffle plate consists of three planar structures: a fan-shaped surface, an upper baffle, and a lower baffle. Inside the shell, the baffle plate is inclined and multiple baffle plates are connected sequentially from top to bottom to form an axial spatial closed spiral flow channel. There is a gap between the outer edge of the fan-shaped surface and the shell so that the condensate can flow down the inner wall of the shell through the gap. The heat exchange tube passes through the heat exchange tube holes on the upper tube sheet, the baffle plate, and the lower tube sheet in sequence and is fixed to the upper tube sheet and the lower tube sheet. The tie rod is set between the upper tube sheet and the lower tube sheet, passes through the tie rod hole on the baffle plate, and is fixedly connected to the upper tube sheet, the baffle plate, and the lower tube sheet. A tangential steam inlet is provided on the upper side of the shell, and the steam inlet vortex direction is consistent with the spiral flow direction of the baffle plate. The purge main pipe is located at the central axis of the heat exchanger, with the lower end sealed and the upper end penetrating through the upper tube sheet and the side wall of the upper head. The purge branch pipe is provided at the angle between the fan-shaped surface of each baffle plate and the upper baffle along the axial direction of the heat exchanger. The purge main pipe is connected to the purge branch pipe, and the purge branch pipe is provided with purge holes along the inclined direction of the baffle plate.

[0006] Preferably, the upper edge of the baffle plate is a triangular upper baffle that bends upward along the heat exchanger axis, and the lower edge of the baffle plate is a triangular lower baffle that bends downward along the heat exchanger axis. The upper edge of the upper baffle plate is flush with the highest point of the outer edge of the baffle plate, and the lower edge of the lower baffle plate is flush with the lowest point of the outer edge of the baffle plate. When multiple baffles are connected, the bottom edge of the lower baffle of the baffle completely overlaps with the top edge of the upper baffle of the baffle connected below it. The inner edge projection circle diameter of the fan-shaped surface is equal to the outer diameter of the purge manifold. A flow-guiding weir plate is welded on the upper surface of the baffle plate. The flow-guiding weir plate is parallel to the lower edge of the fan-shaped surface of the baffle plate in the radial direction of the heat exchanger and parallel to the heat exchange tube in the height direction. Adjacent flow-guiding weir plates and the fan-shaped surface form a U-shaped flow channel for condensate.

[0007] Preferably, the heat exchange tube holes of the baffle plate are circular, and the heat exchange tubes are arranged in an equilateral triangle or a square.

[0008] Preferably, the upper end cap is provided with a first material inlet at the top, a spray head is provided below the first material inlet, the lower end cap is provided with a second material inlet at the bottom, and a condensate outlet is provided on the lower side of the shell.

[0009] Preferably, the inclination angle of the baffle plate is 5° to 45°.

[0010] Preferably, the top-view projection length of the purge branch pipe is 0.7 to 0.8 times the shell radius, the diameter of the purge main pipe is 0.15 to 0.2 times the shell diameter, and the axial length of the top-view projection of the baffle plate is 0.4 to 0.425 times the shell diameter.

[0011] Preferably, the spacing between the heat exchange tubes of the baffle plate is not less than 1.4 times the diameter of the heat exchange tubes.

[0012] Preferably, the height of the flow-guiding weir plate on the baffle plate is 0.5 to 1.5 times the diameter of the heat exchange tube.

[0013] Preferably, the purging branch pipe is a round pipe, square pipe, rectangular pipe or special-shaped pipe, and the purging hole size is 0.1 to 0.4 times the diameter of the heat exchange tube.

[0014] Preferably, the tangential steam inlet is provided with one or more, and each baffle has no less than three tie rod holes.

[0015] The composite flow-guiding closed spiral baffle heat exchanger of the present invention has the following beneficial effects: 1. Steam purging significantly reduces the relaxation time and residence time of condensate flowing on the surface of the baffle plate. The steam purging film layer effectively blocks the condensate leakage path at the heat exchange tube holes of the baffle plate. The "U"-shaped channel formed by steam purging and the diversion weir plate works together to accelerate the flow of condensate to the inner wall of the shell, improve the diversion efficiency of condensate, and effectively avoid the problem of liquid film accumulation in the heat exchange tubes.

[0016] 2. When the baffles overlap circumferentially, the bottom edge of the lower baffle completely overlaps with the top edge of the upper baffle below, forming a complete seal for the triangular leakage area. This avoids the short-circuit flow problem of leakage in the triangular area of ​​conventional spiral baffles, and improves the heat exchanger area and the effective utilization efficiency of the fluid.

[0017] 3. The shell adopts a tangential air intake design, with the air intake swirl direction consistent with the spiral flow channel swirl direction, forming a pre-swirling flow, which enhances the turbulence intensity of the spiral plunger flow in the spiral flow channel and improves the heat transfer effect of the heat exchanger baffle plate; this invention can meet the high-efficiency heat exchange requirements of the chemical and petrochemical fields, and is especially suitable for organic vapor condensation related applications. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the overall structure of the heat exchanger of the present invention; Figure 2 This is a top view of the heat exchanger of the present invention; Figure 3 This is a schematic diagram of the baffle structure of the present invention; Figure 4 This is a front view of the baffle plate of the present invention; Figure 5 This is a top view of the baffle plate of the present invention; Figure 6 This is a side view of the baffle plate of the present invention; Figure 7 This is a schematic diagram of the assembly of the baffle plate of the present invention; Figure 8 This is a schematic diagram of the purging branch pipe installation of the present invention; Figure 9 This is a schematic diagram of the external shape of the purging branch pipe of the present invention; Figure 10 The graph shows the test results of the heat transfer pressure drop of the heat exchanger of this invention. Figure 11 This is a schematic diagram of the overall structure of the heat exchanger in another embodiment of the present invention.

[0019] In the diagram: 1. Upper head, 2. Upper tube sheet, 3. Shell, 4. Baffle plate, 5. Heat exchange tube, 6. Tie rod, 7. Purge branch pipe, 8. Lower tube sheet, 9. Lower head, 10. Purge main pipe, 11. First material inlet, 31. Tangential steam inlet, 32. Condensate outlet, 41. Upper baffle, 42. Lower baffle, 43. Heat exchange tube hole, 44. Drainage weir plate, 45. Tie rod hole, 46. Sector-shaped surface, 81. Second material inlet. Detailed Implementation

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed when in use. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0025] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; 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; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0026] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] A composite flow-guiding closed spiral baffle heat exchanger includes an upper head 1, an upper tube sheet 2, a shell 3, baffles 4, heat exchange tubes 5, a tie rod 6, a purge branch pipe 7, a lower tube sheet 8, a lower head 9, and a purge main pipe 10.

[0028] The heat exchanger has a vertical cylindrical structure. The upper end cap 1, upper tube sheet 2, shell 3, lower tube sheet 8, and lower end cap 9 are connected sequentially from top to bottom to form the main structure of the heat exchanger. The upper end cap 1 is provided with a first material port 11 at the top, and the lower end cap 9 is provided with a second material port 81 at the bottom.

[0029] The baffle 4 is composed of three planar structures: a fan-shaped surface 46, an upper baffle 41, and a lower baffle 42. Inside the shell 3, the baffle 4 is inclined, with an inclination angle of 5° to 45°. The axial length of its top-view projection is 0.4 to 0.425 times the shell diameter. Multiple baffles 4 are connected sequentially from top to bottom circumferentially to form an axially closed spiral flow channel. There is a gap between the outer edge of the fan-shaped surface 46 and the shell 3, allowing the condensate to flow through this gap along the inner wall of the shell 3. Below, the heat exchange tube 5 passes through the heat exchange tube hole 43 on the upper tube sheet 2 and the baffle plate 4 in sequence and is fixed to the upper tube sheet 2 and the lower tube sheet 8. The heat exchange tube hole 43 is circular, and the heat exchange tube is arranged in an equilateral triangle or square pattern with a tube spacing of not less than 1.4 times the diameter of the heat exchange tube. The tie rod 6 is set between the upper tube sheet 2 and the lower tube sheet 8, passes through the tie rod hole 45 on the baffle plate 4, and is fixedly connected to the upper tube sheet 2, the baffle plate 4, and the lower tube sheet 8. Each baffle plate has no less than 3 tie rod holes.

[0030] The upper side of the shell 3 is provided with a tangential steam inlet 31, and one or more tangential steam inlets 31 are provided. The lower side is provided with a condensate outlet 32. The steam inlet vortex direction is consistent with the spiral flow direction of the baffle 4. The purge main pipe 10 is located at the central axis of the heat exchanger, with a diameter of 0.15 to 0.2 times the shell diameter. The lower end is sealed, and the upper end penetrates the upper tube sheet 2 and the side wall of the upper head 1. The purge branch pipe 7 is provided at the angle between the fan-shaped surface 46 of each baffle 4 and the upper baffle 41 along the axial direction of the heat exchanger. The top projection length of the purge branch pipe is 0.7 to 0.8 times the shell radius. The shape can be set as a round pipe, square pipe, rectangular pipe or special-shaped pipe. The purge hole size is 0.1 to 0.4 times the heat exchange tube diameter. The purge main pipe 10 is connected to the purge branch pipe 7. The purge branch pipe 7 is provided with purge holes along the inclined direction of the baffle 4.

[0031] The upper edge of the fan-shaped surface 46 of the baffle plate 4 is a triangular upper baffle 41 that bends upward along the heat exchanger axis, and the lower edge of the fan-shaped surface is a triangular lower baffle 42 that bends downward along the heat exchanger axis. The upper edge of the upper baffle 41 is flush with the highest point of the outer edge of the fan-shaped surface 46, and the lower edge of the lower baffle 42 is flush with the lowest point of the outer edge of the fan-shaped surface 46.

[0032] When multiple baffles 4 are connected, the bottom edge of the lower baffle 42 of the baffle 4 completely overlaps with the top edge of the upper baffle 41 of the baffle 4 connected below it. The inner edge projection circle diameter of the fan-shaped surface 46 is equal to the outer diameter of the purge main pipe 10. A flow-guiding weir plate 44 is welded on the upper surface of the baffle 4, with a height of 0.5 to 1.5 times the diameter of the heat exchange tube. The flow-guiding weir plate 44 is parallel to the lower edge of the fan-shaped surface 46 of the baffle 4 in the radial direction of the heat exchanger, and parallel to the height of the flow-guiding weir plate 44 in the height direction of the heat exchange tube 5. Adjacent flow-guiding weir plates 44 and fan-shaped surfaces 46 form a U-shaped flow channel for condensate.

[0033] The work process is as follows: The cold medium enters the heat exchange tubes through the first material inlet. The hot steam splits into two parts: a small portion enters the main purge pipe and each purge branch pipe, while the majority of the steam enters the heat exchanger shell through the tangential steam inlet. The purge steam continuously sweeps across the upper surface of the fan-shaped surfaces of each baffle plate through the purge holes of the purge branch pipes, forming a high-speed flowing gas film layer. The steam entering the heat exchanger through the tangential steam inlet spirals downwards along the spiral flow channel formed by the baffle plates, exhibiting a spiral plunger-like flow. During the steam flow, it continuously heats the cold medium inside the heat exchange tubes. The condensate flows downwards along the outer wall of the heat exchange tubes. When the condensate falls near the baffle plates, it detaches from the outer wall of the heat exchange tubes under the action of the purge steam and enters the U-shaped flow channel formed by the guide weir plate and the fan-shaped surfaces of the baffle plates. Under the combined action of the purge steam and the gravitational component of the condensate in the direction of the baffle plates, it flows rapidly to the inner wall of the heat exchanger shell and falls onto the lower tube sheet, and then exits the heat exchanger through the condensate outlet.

[0034] Example 1: This embodiment uses the top condenser of an ethanol indirect compression heat pump distillation column as an example to illustrate the structural principle and working method of the composite flow-inducing closed spiral baffle heat exchanger of the present invention.

[0035] The heat exchanger's hot side carries ethanol vapor at a temperature of 80°C, a pressure of 108 kPa (a), and a flow rate of 20 t / h; the cold side carries water evaporation at a temperature of 75°C and a pressure of 39 kPa (a). The heat exchanger's heat load is 4710 kW; the composite closed-loop helical baffle heat exchanger described in this invention operates in a vertical tube falling film mode.

[0036] like Figure 1 and Figure 2 As shown, the composite flow-guiding closed spiral baffle heat exchanger of this embodiment includes: an upper head 1, an upper tube sheet 2, a shell 3, baffles 4, heat exchange tubes 5, a tie rod 6, a purge branch pipe 7, a lower tube sheet 8, a lower head 9, and a purge main pipe 10. The heat exchanger is vertically installed, and the upper head, upper tube sheet, shell, lower tube sheet, and lower head are connected sequentially. The heat exchange tubes 5 have a specification of φ38mm×9000mm; the inner diameter of the shell is 1500mm. A tangential steam inlet 31 is provided on the upper part of the outer wall of the shell, and a condensate outlet 32 ​​is provided on the lower part of the outer wall of the shell. The upper head 1 has a first material port 11 and an inlet of the purge main pipe 10, and the lower head has a second material port 81.

[0037] like Figures 3-6 As shown, the baffle plate 4 is composed of three planes bent together: a fan-shaped surface 46, an upper baffle 41, and a lower baffle 42. The upper edge of the fan-shaped surface is a triangular upper baffle 41 that bends upward along the heat exchanger axis, and the lower edge of the fan-shaped surface is a triangular lower baffle 42 that bends downward along the heat exchanger axis. The upper edge of the upper baffle is flush with the highest point of the outer edge of the fan-shaped surface, and the lower edge of the lower baffle is flush with the lowest point of the outer edge of the fan-shaped surface.

[0038] When the baffles overlap circumferentially, the bottom edge of the lower baffle 42 of the baffle completely overlaps with the top edge of the upper baffle 41 of the connected baffle below, and they are fixed together by spot welding, thereby achieving complete closure of the triangular leakage zone. The inner edge projection circle diameter of the sector surface 46 is equal to the outer diameter of the purge main pipe 10. The composite flow-guiding closed spiral baffle heat exchanger has heat exchange tube holes 43 and tie rod holes 45. The heat exchange tube holes 43 are circular, and the heat exchange tubes are arranged in an equilateral triangle or square pattern. The flow-guiding weir plate 44 is welded to the upper surface of the baffle plate. The flow-guiding weir plate is parallel to the lower edge of the sector surface of the baffle in the radial direction of the heat exchanger shell, and parallel to the heat exchange tube 5 in the height direction. The height of the flow-guiding weir plate is 40 mm and the thickness is 2 mm. Adjacent flow-guiding weir plates and the sector surface form a U-shaped flow channel for condensate.

[0039] Depend on Figure 7 As shown, a spiral flow channel is formed by multiple baffles overlapping circumferentially, creating an axially closed spatial structure. Viewed from above, the flow channel rotates counter-clockwise. The baffles have an inclination angle of 10°, a circumferential radius of six-tenths of an inch, a spiral channel pitch of 780 mm, and a projected circle radius of 680 mm. Heat exchange tubes 5 pass through the spiral baffle assembly and are fixed to the upper tube sheet 2 and lower tube sheet 8, respectively.

[0040] The purge manifold 10 is located at the central axis of the heat exchanger, with its lower end sealed and its upper end penetrating the upper tube sheet and the side wall of the upper head. The purge manifold 10 has a diameter of 250 mm and a length of 8.5 m. Figure 8 As shown, the purging branch pipe 7 is installed at the "L"-shaped angle between the fan-shaped surface 46 of each baffle 4 and the upper baffle 41. Figure 9 As shown, the purge branch pipe 7 is provided with purge holes / slits along the inclined direction of the baffle plate. In this embodiment, the purge branch pipe 7 is a 50mm×50mm square tube with a length of 600mm, and purge holes with a spacing of 25mm and a diameter of 5mm are opened on the purge branch pipe.

[0041] The working method of this embodiment is as follows: Water at 75℃ enters the heat exchanger through the first material inlet 11 of the upper head 1, passes through the upper tube sheet 2, and enters the heat exchange tube 5, exhibiting a falling film flow pattern from top to bottom. The total flow rate of ethanol vapor at 80℃ on the hot side is 20t / h, of which 18t enters the shell-side spiral flow channel of the heat exchanger through the tangential steam inlet 31, forming a pre-swirling flow in the same direction as the spiral flow channel, and then enters the spatial closed spiral flow channel formed by the baffles. The remaining 2t of ethanol vapor is supplied as purge steam to the purge manifold 10. The purge steam sweeps the upper surface of the fan-shaped surface of the baffles at high speed through the purge holes of the purge branch pipe 7. The 80℃ ethanol vapor heats the water in the heat exchange tube. After being heated, the water in the tube partially vaporizes, and the ethanol releases heat and continuously condenses. On average, about 2.2t / h of ethanol condensate is produced per meter of heat exchange tube. A large amount of condensate flows downward along the outer wall of the heat exchange tube. When the condensate flows to the vicinity of the baffle plate, it is separated from the outer wall of the heat exchange tube by the action of the purge steam and enters the "U"-shaped flow channel formed by the flow weir plate 44 and the baffle plate fan-shaped surface 46. Under the dual action of the purge steam and the gravity component of the condensate along the direction of the baffle plate, it flows rapidly to the inner wall of the heat exchanger shell and falls onto the lower tube sheet. Then it is discharged from the heat exchanger through the condensate outlet 32.

[0042] Because ethanol has a relatively low latent heat of vaporization, the amount of ethanol vapor condensate is about three times larger than that of water vapor condensate under the same operating conditions. Improving the ethanol condensate drainage velocity and efficiency is crucial for enhancing the overall heat transfer performance of the heat exchanger. In this embodiment, steam purging significantly reduces the relaxation time and residence time of the condensate on the baffle plate surface. With the synergistic effect of steam purging and the U-shaped channel of the drainage weir plate, the ethanol condensate is rapidly diverted. The steam purging film layer effectively blocks the condensate leakage path at the baffle plate tube holes, effectively avoiding the problem of condensate accumulation on the outer wall of the lower heat exchange tubes and improving the overall heat transfer performance of the heat exchanger. Furthermore, using baffles to construct a closed spiral flow channel avoids the triangular leakage problem present in conventional spiral baffles, improving the utilization efficiency of the heat exchange tubes. Simultaneously, it avoids the adverse effects of secondary eddies caused by triangular leakage on the heat exchanger's flow resistance, significantly reducing the shell-side flow resistance. The heat transfer pressure drop test results of the composite drainage spiral baffle heat exchanger in this embodiment are as follows: Figure 10 As shown, the average heat transfer coefficient of the heat exchanger is approximately 1500 W / m². 2 At ℃, the average shell-side pressure drop is approximately 4 kPa.

[0043] Comparative Example 1: This comparative example uses a conventional bow-shaped baffle heat exchanger. The operating parameters of the heat exchanger are the same as those in Example 1, namely: the hot side is for ethanol condensation, with an ethanol vapor temperature of 80℃, a pressure of 108 kPa (a), and a flow rate of 20 t / h; the cold side is for water evaporation, with a cold side evaporation temperature of 75℃ and a pressure of 39 kPa (a). The heat load of the heat exchanger is 4710 kW; it operates in the mode of a vertical tube falling film heat exchanger.

[0044] The heat exchanger tubes in this comparative example have a specification of φ38mm×9000mm; the heat exchanger shell adopts a center steam inlet method, and the arc-shaped baffle is a 25% notched fan-shaped flat plate. The baffle has no steam condensate diversion or steam purging structure design. All 20t / h of ethanol vapor is introduced into the shell side of the heat exchanger and heats the water in the heat exchanger tubes. The relevant data comparison between Comparative Example 1 and Example 1 is shown in Table 1.

[0045] Compared to the conventional arc-shaped baffle used in Example 1, there is a serious problem of condensate accumulation outside the tubes. The arc-shaped baffle, perpendicular to the heat exchange tubes, cannot effectively drain the condensate outside the tubes, resulting in a thicker liquid film outside the tubes at the bottom, which increases the heat transfer resistance and the heat transfer coefficient of the heat exchanger is low. In addition, the shell-side fluid of the arc-shaped baffle heat exchanger flows in a "Z" shape, resulting in a large shell-side resistance and a large decrease in the effective heat transfer temperature difference. In contrast, the composite drainage closed spiral baffle used in Example 1 has a certain inclination angle between the baffle and the heat exchange tubes. When the condensate outside the tubes falls onto the surface of the baffle, under the action of gravity along the inclined surface of the spiral baffle and the purge air, the condensate outside the tubes can be effectively drained and removed from the outer wall of the heat exchange tubes, effectively reducing the thickness of the liquid film of condensate on the outer wall of the lower heat exchange tubes, thereby improving the overall heat transfer performance of the heat exchanger. Engineering practice has shown that, under the same processing load conditions, the area of ​​the composite flow-guiding spiral baffle heat exchanger described in Example 1 is reduced by about 30% compared to the heat exchange area of ​​the conventional spiral baffle in Comparative Example 1.

[0046] Table 1

[0047] Example 2: This embodiment uses a reboiler in the bottom of a chlorotoluene heat pump distillation column as an example to illustrate the structural principle and working method of the composite flow-inducing closed spiral baffle heat exchanger of the present invention.

[0048] The reboiler in this embodiment operates using a thermosiphon rising film method. The hot side of the heat exchanger contains 105°C chlorotoluene vapor, and the cold side contains a 70% concentration chlorotoluene aqueous solution at 85°C.

[0049] like Figure 11 As shown, the composite flow-guiding baffle reboiler of this embodiment includes: an upper head 1, an upper tube sheet 2, a shell 3, baffles 4, heat exchange tubes 5, a tie rod 6, a purge branch pipe 7, a lower tube sheet 8, a lower head 9, a purge main pipe 10, and a spray head A. The heat exchanger is vertically installed, and the upper head, upper tube sheet, shell, lower tube sheet, and lower head are connected sequentially. The heat exchange tubes 5 have a specification of φ25mm×6000mm, and the inner diameter of the shell is 1200mm. The upper part of the outer wall of the shell is provided with a tangential steam inlet 31, and the lower part of the outer wall of the shell is provided with a condensate outlet 32. The upper head is provided with a first material port 11 and an inlet of the purge main pipe 10, and the lower head is provided with a second material port 81. The structure and installation method of the baffles 4 and the purge main pipe 10 in this embodiment are similar to those in Embodiment 1, and will not be described again here. In this embodiment, the baffle plate has an inclination angle of 12°, a circumferential division of 1 / 4, a diversion weir plate height of 30mm, a diversion weir plate thickness of 1.5mm, and a DN25 round pipe for the purging branch pipe 7. Purging holes with a spacing of 10mm and a diameter of 3mm are opened on the purging branch pipe.

[0050] The working method of this embodiment is as follows: In this embodiment, the reboiler operates using a thermosiphon rising film method. On the hot side, chlorotoluene vapor flows through the shell side of the heat exchanger, while on the cold side, the chlorotoluene aqueous solution flows through the tube side. The shell-side medium flow process is as follows: a portion of the chlorotoluene vapor at 105°C enters the shell-side spiral flow channel of the heat exchanger through the tangential steam inlet 31, while a smaller portion is supplied as purge steam to the purge manifold 10. The chlorotoluene vapor flows downwards along the spiral flow channel, continuously heating the liquid inside the heat exchange tubes. The chlorotoluene condensate is rapidly diverted by the synergistic effect of the spiral baffles, purge steam, and the U-shaped channel of the diversion weir, reducing the condensate film thickness on the outer surface of the lower heat exchange tubes and improving the heat transfer film coefficient of the shell-side fluid. The process flow of the tube-side medium is as follows: through the siphon effect of the liquid film in the distillation column bottom, the immersion height of the liquid in the heat exchange tube is maintained at about 1.5m. After being heated, part of the solution in the heat exchange tube evaporates and vaporizes. The generated secondary steam carries the liquid upward along the inner wall of the heat exchange tube. The secondary steam drags the liquid and spreads into a film on the inner wall of the heat exchange tube. The gas-liquid mixture is discharged from the heat exchanger through the first material port 11 of the upper head 1.

[0051] Conventional technologies suffer from a thick accumulated liquid film at the bottom of the heat exchange tubes, resulting in low heat flux in the rising film generation section. The amount of secondary steam generated by evaporation inside the tubes is insufficient to drag the liquid inside the tubes to form a film, and the upper heat exchange tubes suffer from severe dry wall problems, preventing the heat exchanger from achieving stable and continuous rising film operation. This embodiment uses a composite flow-guiding spiral baffle heat exchanger as a thermosiphon rising film reboiler. The synergistic effect of the spiral baffle, purge steam, and flow-guiding weir effectively avoids the condensate accumulation problem in the lower heat exchange tubes, improving the heat transfer performance of the submerged section of the tube bundle. The high heat flux density of the submerged section ensures the generation of secondary steam and the sustainability of the rising film process, guaranteeing a high heat transfer coefficient for the heat exchanger during rising film operation.

[0052] It should be noted that the above detailed descriptions are exemplary and intended to provide further explanation of this application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0053] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments described in this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0054] It should be noted that the terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented in sequences other than those illustrated or described herein.

[0055] Furthermore, the terms “comprising” and “having”, and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to those steps or units that are explicitly listed, but may include other steps or units that are not explicitly listed or that are inherent to such process, method, product, or apparatus.

[0056] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways, such as rotated 90 degrees or in other orientations, and the spatial relative descriptions used herein will be interpreted accordingly.

[0057] In the detailed description above, reference has been made to the accompanying drawings, which form part of this document. In the drawings, similar symbols typically identify similar parts unless the context otherwise indicates otherwise. The illustrated embodiments described in the detailed specification, drawings, and claims are not intended to be limiting. Other embodiments may be used and other changes may be made without departing from the spirit or scope of the subject matter presented herein.

[0058] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A composite flow-guiding closed-loop spiral baffle heat exchanger, characterized in that: It includes an upper head, upper tube sheet, shell, baffles, heat exchange tubes, tie rods, purge branch pipes, lower tube sheet, lower head, and purge main pipe; The heat exchanger has a vertical cylindrical structure. The upper end cap, upper tube sheet, shell, lower tube sheet, and lower end cap are connected sequentially from top to bottom to form the main structure of the heat exchanger. The baffle plate consists of three planar structures: a fan-shaped surface, an upper baffle, and a lower baffle. Inside the shell, the baffle plate is inclined and multiple baffle plates are connected sequentially from top to bottom to form an axial spatial closed spiral flow channel. There is a gap between the outer edge of the fan-shaped surface and the shell so that the condensate can flow down the inner wall of the shell through the gap. The heat exchange tube passes through the heat exchange tube holes on the upper tube sheet, the baffle plate, and the lower tube sheet in sequence and is fixed to the upper tube sheet and the lower tube sheet. The tie rod is set between the upper tube sheet and the lower tube sheet, passes through the tie rod hole on the baffle plate, and is fixedly connected to the upper tube sheet, the baffle plate, and the lower tube sheet. A tangential steam inlet is provided on the upper side of the shell, and the steam inlet vortex direction is consistent with the spiral flow direction of the baffle plate. The purge main pipe is located at the central axis of the heat exchanger, with the lower end sealed and the upper end penetrating through the upper tube sheet and the side wall of the upper head. The purge branch pipe is provided at the angle between the fan-shaped surface of each baffle plate and the upper baffle along the axial direction of the heat exchanger. The purge main pipe is connected to the purge branch pipe, and the purge branch pipe is provided with purge holes along the inclined direction of the baffle plate.

2. The composite flow-guiding closed spiral baffle heat exchanger according to claim 1, characterized in that: The upper edge of the baffle plate is a triangular upper baffle that bends upward along the heat exchanger axis, and the lower edge of the baffle plate is a triangular lower baffle that bends downward along the heat exchanger axis. The upper edge of the upper baffle plate is flush with the highest point of the outer edge of the baffle plate, and the lower edge of the lower baffle plate is flush with the lowest point of the outer edge of the baffle plate. When multiple baffles are connected, the bottom edge of the lower baffle of the baffle completely overlaps with the top edge of the upper baffle of the baffle connected below it. The inner edge projection circle diameter of the fan-shaped surface is equal to the outer diameter of the purge manifold. A flow-guiding weir plate is welded on the upper surface of the baffle plate. The flow-guiding weir plate is parallel to the lower edge of the fan-shaped surface of the baffle plate in the radial direction of the heat exchanger and parallel to the heat exchange tube in the height direction. Adjacent flow-guiding weir plates and the fan-shaped surface form a U-shaped flow channel for condensate.

3. The composite flow-guiding closed spiral baffle heat exchanger according to claim 1, characterized in that: The heat exchange tube holes of the baffle plate are circular, and the heat exchange tubes are arranged in an equilateral triangle or square pattern.

4. The composite flow-inducing closed-loop spiral baffle heat exchanger according to claim 1, characterized in that: The upper end cap is provided with a first material inlet at the top, a spray head is provided below the first material inlet, the lower end cap is provided with a second material inlet at the bottom, and a condensate outlet is provided on the lower side of the shell.

5. The composite flow-guiding closed spiral baffle heat exchanger according to claim 1, characterized in that: The inclination angle of the baffle plate is 5°~45°.

6. The composite flow-guiding closed spiral baffle heat exchanger according to claim 5, characterized in that: The top-view projection length of the purge branch pipe is 0.7 to 0.8 times the shell radius, the diameter of the purge main pipe is 0.15 to 0.2 times the shell diameter, and the axial length of the top-view projection of the baffle plate is 0.4 to 0.425 times the shell diameter.

7. The composite flow-guiding closed spiral baffle heat exchanger according to claim 6, characterized in that: The spacing between the heat exchange tubes of the baffle plate shall not be less than 1.4 times the diameter of the heat exchange tubes.

8. The composite flow-guiding closed spiral baffle heat exchanger according to claim 7, characterized in that: The height of the flow-guiding weir plate on the baffle plate is 0.5 to 1.5 times the diameter of the heat exchange tube.

9. The composite flow-guiding closed spiral baffle heat exchanger according to claim 1, characterized in that: The purging branch pipe is a round pipe, square pipe, rectangular pipe or special-shaped pipe, and the purging hole size is 0.1 to 0.4 times the diameter of the heat exchange tube.

10. The composite flow-guiding closed spiral baffle heat exchanger according to claim 1, characterized in that: The tangential steam inlet is provided with one or more, and each baffle has no less than three tie rod holes.

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