Composite drainage closed helical baffle heat exchanger

Abstract

The composite drainage closed spiral baffle heat exchanger comprises an upper head, an upper tube plate, a shell, baffle plates, heat exchange tubes, pull rods, blowing branch pipes, a lower tube plate, a lower head and a blowing main pipe. The upper head, the upper tube plate, the shell, the lower tube plate and the lower head are sequentially connected from top to bottom to form the main body structure of the heat exchanger. In the shell, the baffle plates are arranged in an inclined manner, a plurality of the baffle plates are sequentially connected in a circumferential direction from top to bottom, and an axial space closed spiral flow channel is formed, the heat exchange tubes sequentially pass through the heat exchange tube holes in the upper tube plate and the lower tube plate and are fixed with the upper tube plate and the lower tube plate. A tangential steam inlet is arranged on the upper side of the shell, the gas rotation direction is consistent with the spiral flow channel rotation direction of the baffle plates, the blowing main pipe is arranged at the central axis position of the heat exchanger, the lower end is blocked, the upper end penetrates the side wall of the upper tube plate and the upper head, and the blowing branch pipes are arranged at the included angle between the sector surface of each baffle plate and the upper baffle plate in the axial direction of the heat exchanger.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat exchangers, in particular to a composite drainage closed spiral baffle heat exchanger. BACKGROUND

[0002] Compared with the traditional segmental baffle heat exchanger, the spiral baffle heat exchanger has the characteristics of high heat exchange area utilization rate, small flow resistance and high heat transfer coefficient, and has been widely concerned and applied in the field of industrial heat exchange. However, in the application occasions of organic vapor condensation, such as the reboiler of direct pressure type heat pump rectification system, the condenser of freon refrigeration heat pump system, the tail cooler of ORC waste heat power generation, and the alkylating reactor, the experimental results show that the performance difference between the spiral baffle heat exchanger and the conventional segmental baffle is not obvious. The reason is that the traditional spiral baffle is made of fan-shaped plates, and there will be a triangular leakage area between adjacent baffles. The existence of the triangular leakage area will cause short circuit and back mixing of the fluid in adjacent spiral flow channels, thereby reducing the effective utilization rate of the heat exchange area. The secondary vortex generated when the leakage flow mixes with the main flow will also cause the flow resistance of the heat exchanger to increase significantly. The patents CN101598510B, CN2622651Y and CN103105075A all have the above-mentioned triangular leakage area problem, which affects the actual application effect of the spiral baffle.

[0003] The latent heat of organic matter is small, only 15% to 40% of that of water, so a large amount of condensate will be produced during condensation. The condensate film near the wall of the heat exchange tube will significantly increase the heat transfer resistance of the heat exchanger. According to the test, when the thickness of the liquid film is more than 2mm during the condensation of ethanol vapor, the heat transfer coefficient will decrease by more than 30%. Compared with the traditional segmental baffle, the inclination angle between the spiral baffle and the heat exchange tube helps to drain the condensate by gravity, to some extent, reducing the thickness of the liquid film outside the tube. However, due to the existence of a certain theoretical gap between the spiral baffle heat exchange tube hole and the heat exchange tube, under the multiple 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 exchange tube, causing serious condensate accumulation on the outer wall of the lower heat exchange tube. Patent CN2622651Y provides a drainage groove on the baffle. However, due to the thickness of the baffle, when the amount of condensate is large, the condensate will overflow from the drainage groove, causing drainage failure, and the structure cannot solve the leakage problem of the annular gap between the baffle and the heat exchange tube. SUMMARY

[0004] The present application aims to provide a composite drainage closed spiral baffle heat exchanger to solve the problems existing in the prior art. The technical problems solved by the present application are solved by the following technical solutions.

[0005] The composite drainage closed helical baffle heat exchanger comprises an upper head, an upper tube plate, a shell, baffle plates, heat exchange tubes, pull rods, purge branch pipes, a lower tube plate, a lower head and a purge main pipe;

[0006] The heat exchanger is a vertical cylindrical structure, and the upper head, the upper tube plate, the shell, the lower tube plate and the lower head are sequentially connected from top to bottom to form the main body structure of the heat exchanger.

[0007] The baffle plate is composed of a sector, an upper baffle and a lower baffle, and is arranged obliquely in the shell. A plurality of baffle plates are sequentially connected in a circumferential direction from top to bottom to form an axially closed helical flow channel. A gap is formed between the outer edge of the sector and the shell to allow the condensate to flow down along the inner wall of the shell. The heat exchange tube sequentially passes through the heat exchange tube hole in the upper tube plate and the lower tube plate and is fixed to the upper tube plate and the lower tube plate. The pull rod is arranged between the upper tube plate and the lower tube plate, passes through the pull rod hole in the baffle plate and is fixedly connected to the upper tube plate, the baffle plate and the lower tube plate.

[0008] A tangential steam inlet is arranged on the upper side of the shell, and the inlet gas rotation direction is consistent with the rotation direction of the helical flow channel of the baffle plate. The purge main pipe is arranged at the central axis of the heat exchanger, is blocked at the lower end and penetrates the side wall of the upper tube plate and the upper head at the upper end. The purge branch pipe is arranged at the included angle between the sector and the upper baffle of each baffle plate in the axial direction of the heat exchanger. The purge main pipe is in communication with the purge branch pipe. The purge branch pipe is provided with a purge hole in the oblique direction of the baffle plate.

[0009] Preferably, the upper edge of the sector of the baffle plate is a triangular upper baffle which is bent upward along the axis of the heat exchanger, and the lower edge of the sector is a triangular lower baffle which is bent downward along the axis of the heat exchanger. The upper edge of the upper baffle is flush with the highest point of the outer edge of the sector, and the lower edge of the lower baffle is flush with the lowest point of the outer edge of the sector.

[0010] When a plurality of baffle plates are connected, the bottom edge of the lower baffle of the baffle plate completely overlaps the top edge of the upper baffle of the baffle plate connected below the baffle plate. The diameter of the projection circle of the inner edge of the sector is equal to the outer diameter of the purge main pipe. A drainage weir plate is welded to the upper surface of the baffle plate. The drainage weir plate is parallel to the lower edge of the sector of the baffle plate in the radial direction of the heat exchanger, and is parallel to the heat exchange tube in the height direction of the drainage weir plate. Adjacent drainage weir plates and the sector form a U-shaped drainage channel for the condensate.

[0011] Preferably, the heat exchange tube hole of the baffle plate is circular, and the heat exchange tube is arranged in a triangular or square pattern.

[0012] Preferably, a first material inlet is arranged at the top of the upper head, a spray head is arranged below the first material inlet, a second material inlet is arranged at the bottom of the lower head, and a condensate outlet is arranged on the side of the lower part of the shell.

[0013] Preferably, the baffle plate has an inclination angle of 5° to 45°.

[0014] Preferably, the baffle plate has an inclination angle of 5° to 45°.

[0015] Preferably, the baffle plate has an inclination angle of 5° to 45°.

[0016] Preferably, the baffle plate has an inclination angle of 5° to 45°.

[0017] Preferably, the baffle plate has an inclination angle of 5° to 45°.

[0018] Preferably, the baffle plate has an inclination angle of 5° to 45°.

[0019] The composite drainage closed spiral baffle heat exchanger of the present application has the following beneficial effects:

[0020] 1. Steam sweeping significantly reduces the relaxation time and residence time of condensate flowing on the surface of the baffle plate, and the steam sweeping gas film layer effectively blocks the condensate leakage path at the baffle plate heat exchange tube hole; the steam sweeping and the "U" shaped channel formed by the drainage weir plate cooperate to accelerate the flow of condensate to the inner wall of the shell, improve the drainage efficiency of the condensate, and effectively avoid the problem of liquid film accumulation in the heat exchange tube.

[0021] 2. When the baffle plate is circumferentially overlapped, the bottom edge line of the lower baffle plate completely overlaps the top edge line of the upper baffle plate, completely sealing the triangular leakage area and avoiding the short circuit flow problem of the conventional spiral baffle triangular area, thereby improving the effective utilization efficiency of the heat exchanger area and the fluid.

[0022] 3. The shell is designed with tangential gas inlet, the gas inlet rotation direction is consistent with the spiral flow channel rotation direction, and a pre-rotation flow is formed, which enhances the spiral plug flow turbulence intensity of the fluid in the spiral flow channel and improves the heat transfer enhancement effect of the baffle plate of the heat exchanger; the present application can meet the high-efficiency heat exchange demand in the chemical and petrochemical fields, and is especially suitable for organic steam condensation related application occasions. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a schematic diagram of the overall structure of the heat exchanger of the present application;

[0024] Figure 2 is a top view of the heat exchanger of the present application;

[0025] Figure 3The structure diagram of the baffle plate of the present application;

[0026] Figure 4 The front view of the baffle plate of the present application;

[0027] Figure 5 The top view of the baffle plate of the present application;

[0028] Figure 6 The side view of the baffle plate of the present application;

[0029] Figure 7 The assembly diagram of the baffle plate of the present application;

[0030] Figure 8 The installation diagram of the purge branch pipe of the present application;

[0031] Figure 9 The shape diagram of the purge branch pipe of the present application;

[0032] Figure 10 The heat transfer pressure drop test result diagram of the heat exchanger of the present application;

[0033] Figure 11 The overall structure diagram of the heat exchanger in another embodiment of the present application.

[0034] In the figure: 1, upper head, 2, upper tube sheet, 3, shell, 4, baffle plate, 5, heat exchange tube, 6, pull rod, 7, purge branch pipe, 8, lower tube sheet, 9, lower head, 10, purge main pipe, 11, first material port, 31, tangential steam inlet, 32, condensate outlet, 41, upper baffle, 42, lower baffle, 43, heat exchange tube hole, 44, flow guide weir plate, 45, pull rod hole, 46, sector, 81, second material port. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be described in further detail below with the help of the accompanying drawings and embodiments.

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be described clearly and completely below with the help of the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. The components of the embodiments of the present application described and shown in the accompanying drawings can be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed present application, but only represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present application.

[0038] It should be noted that similar reference numerals and letters refer to like items in the accompanying drawings, and once an item is defined in one drawing, it need not be further defined and explained in subsequent drawings.

[0039] In the description of the present application, it should be noted that the terms "upper", "lower", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of the present application is usually placed, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0040] In the description of the present application, it should also be noted that unless otherwise explicitly specified and limited, the terms "arranged", "mounted", "connected" should be understood broadly, for example, can be fixedly connected, can be detachably connected, or integrally connected; can be mechanically connected, can be electrically connected; can be directly connected, can be indirectly connected through an intermediate medium, or can be connected internally between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0041] The embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0042] A composite drainage closed spiral baffle heat exchanger, comprising an upper head 1, an upper tube plate 2, a shell 3, a baffle 4, a heat exchange tube 5, a pull rod 6, a purge branch pipe 7, a lower tube plate 8, a lower head 9 and a purge main pipe 10.

[0043] The heat exchanger is a vertical cylindrical structure, and the upper head 1, the upper tube plate 2, the shell 3, the lower tube plate 8 and the lower head 9 are connected in sequence from top to bottom to form the main body structure of the heat exchanger. The upper head 1 is provided with a first material port 11 at the top, and the lower head 9 is provided with a second material port 81 at the bottom.

[0044] The baffle 4 is composed of three planar structures of sector face 46, upper baffle 41 and lower baffle 42, and is arranged obliquely inside the shell 3, with an inclination angle of 5°-45° and an axial length of 0.4-0.425 times the diameter of the shell in the overhead projection, and a plurality of baffle plates 4 are connected in sequence from top to bottom and circumferentially to form an axially closed spiral flow channel, and the outer edge of the sector face 46 has a gap with the shell 3 to allow the condensate to flow down along the inner wall of the shell 3, and the heat exchange tube 5 passes through the heat exchange tube hole 43 on the upper tube plate 2 and the lower tube plate 8 and is fixed with the upper tube plate 2 and the lower tube plate 8, and the heat exchange tube hole 43 is circular, and the heat exchange tube is arranged in a triangular or square pattern with a spacing of not less than 1.4 times the diameter of the heat exchange tube, and the pull rod 6 is arranged between the upper tube plate 2 and the lower tube plate 8, passes through the pull rod hole 45 on the baffle plate 4 and is fixedly connected with the upper tube plate 2, the baffle plate 4 and the lower tube plate 8, and the pull rod hole of each baffle plate is not less than 3.

[0045] The shell 3 is provided with a tangential steam inlet 31 on the upper side, and a condensate outlet 32 on the lower side, and the inlet gas rotation direction is consistent with the spiral flow direction of the baffle plate 4, and the sweeping main pipe 10 is arranged at the center axis of the heat exchanger, with a diameter of 0.15-0.2 times the diameter of the shell, and is sealed at the lower end and penetrates the side wall of the upper tube plate 2 and the upper head 1 at the upper end, and the sweeping branch pipe 7 is arranged at the angle between the sector face 46 and the upper baffle 41 of each baffle plate 4 in the axial direction of the heat exchanger, and the length of the sweeping branch pipe in the overhead projection is 0.7-0.8 times the radius of the shell, and the shape can be set as a circular pipe, a square pipe, a rectangular pipe or a special-shaped pipe, and the sweeping hole size is 0.1-0.4 times the diameter of the heat exchange tube, and the sweeping main pipe 10 is communicated with the sweeping branch pipe 7, and the sweeping branch pipe 7 is provided with a sweeping hole along the inclination direction of the baffle plate 4.

[0046] The upper edge of the sector face 46 of the baffle plate 4 is a triangular upper baffle 41 bent upward along the axis of the heat exchanger, and the lower edge of the sector face is a triangular lower baffle 42 bent downward along the axis of the heat exchanger, and the upper edge of the upper baffle 41 is flush with the highest point of the outer edge of the sector face 46, and the lower edge of the lower baffle 42 is flush with the lowest point of the outer edge of the sector face 46.

[0047] When a plurality of baffle plates 4 are connected, the bottom edge of the lower baffle 42 of the baffle plate 4 is completely overlapped with the top edge of the upper baffle 41 of the baffle plate 4 connected below, and the projection circle diameter of the inner edge of the sector face 46 is equal to the outer diameter of the sweeping main pipe 10, and a flow guide weir plate 44 is welded on the upper surface of the baffle plate 4, with a height of 0.5-1.5 times the diameter of the heat exchange tube, and the flow guide weir plate 44 is parallel to the lower edge of the sector face 46 of the baffle plate 4 in the radial direction of the heat exchanger, and the height direction of the flow guide weir plate 44 is parallel to the heat exchange tube 5, and the adjacent flow guide weir plate 44 and the sector face 46 form a U-shaped flow guide channel for the condensate.

[0048] The working process is as follows:

[0049] The cold medium enters the heat exchange tube through the first material port, the hot steam is divided into two parts, a small part of the steam enters the purging main pipe and each purging branch pipe, and the remaining part of the steam enters the heat exchanger shell through the tangential steam inlet. The purging steam continuously sweeps the upper surface of the sector surface of each baffle through the purging holes of the purging branch pipe, forming a high-speed gas film layer. The steam entering the heat exchanger through the tangential steam inlet spirally flows downward along the spiral flow channel formed by the baffles, showing a spiral plunger type flow. The steam continuously heats the cold medium in the heat exchange tube in the process of flowing, and the condensate flows downward along the outer wall of the heat exchange tube. When the condensate flows to the vicinity of the baffle, the condensate is separated from the outer wall of the heat exchange tube under the action of the purging steam, enters the U-shaped flow guide channel formed by the flow guide weir plate and the sector surface of the baffle, and quickly flows to the inner wall of the heat exchanger shell and falls to the lower tube plate under the double actions of the purging steam and the gravity component of the condensate in the baffle direction. After that, the condensate is discharged from the heat exchanger through the condensate outlet.

[0050] Example 1

[0051] This embodiment takes a certain ethanol indirect compression type heat pump rectifying column top condenser as an example to describe the structure principle and working method of the composite flow guide closed spiral baffle heat exchanger.

[0052] The hot side of the heat exchanger is ethanol steam, the ethanol steam temperature is 80℃, the pressure is 108kPa (a), and the flow rate is 20t / h; the cold side is water evaporation, the cold side evaporation temperature is 75℃, and the pressure is 39kPa (a). The heat load of the heat exchanger is 4710kW; the composite closed flow guide spiral baffle heat exchanger is used, and the vertical tube falling film mode is used.

[0053] As shown in Figure 1 and Figure 2 , the composite flow guide closed spiral baffle heat exchanger of this embodiment comprises: an upper head 1, an upper tube plate 2, a shell 3, a baffle 4, a heat exchange tube 5, a pull rod 6, a purging branch pipe 7, a lower tube plate 8, a lower head 9, and a purging main pipe 10. The heat exchanger is vertically installed, and the upper head, the upper tube plate, the shell, the lower tube plate, and the lower head are sequentially connected. The heat exchange tube 5 has a heat exchange tube specification of φ38mm×9000mm; and the shell has an inner diameter of 1500mm. 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 1 is provided with a first material port 11 and an inlet of the purging main pipe 10, and the lower head is provided with a second material port 81.

[0054] As shown in Figures 3-6As 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] The working method of this embodiment is as follows:

[0059] Water at 75℃ enters the heat exchanger from the first material port 11 of the upper head 1, enters the heat exchange tube 5 after passing through the upper tube plate 2, and presents a downward falling film flow pattern inside the tube. The total flow of ethanol steam at a hot side temperature of 80℃ is 20t / h, of which 18t enters the heat exchanger shell side spiral flow channel from the tangential steam inlet 31, forming a pre-rotation flow consistent with the rotation direction of the spiral flow channel, and then entering the space closed spiral flow channel formed by the baffle, and the remaining 2t ethanol steam is supplied as a purge steam to the purge manifold 10, and the purge steam sweeps the upper surface of the baffle sector at high speed through the purge holes of the purge branch 7; the 80℃ ethanol steam heats the water inside the heat exchange tube, and after the water is heated, part of it is gasified, and the ethanol continuously condenses after heat release, and the heat exchange tube generates about 2.2t / h of ethanol condensate per meter on average; 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, the condensate is separated from the outer wall of the heat exchange tube under the action of the purge steam, enters the "U"-shaped flow guide channel formed by the flow guide weir plate 44 and the baffle sector 46, and quickly flows to the inner wall of the heat exchanger shell and falls to the lower tube plate under the dual action of the purge steam and the gravity component of the condensate along the baffle direction, and then is discharged from the heat exchanger through the condensate outlet 32.

[0060] Due to the small latent heat of ethanol gasification, the amount of ethanol steam condensate is about 3 times larger than that of water condensate when water vapor is used as the heat source under the same working conditions. Improving the flow guide speed and efficiency of ethanol condensate plays a crucial role in improving the overall heat transfer performance of the heat exchanger. In this embodiment, the steam purge significantly reduces the relaxation time and residence time of the condensate flowing on the surface of the baffle. Under the synergistic action of the steam purge and the "U"-shaped channel of the flow guide weir plate, the ethanol condensate is quickly guided, the steam purge gas film effectively blocks the condensate leakage path at the baffle tube hole, effectively avoids the condensate accumulation problem on the outer wall of the lower heat exchange tube of the heat exchanger, and improves the overall heat transfer performance of the heat exchanger. In addition, the closed spiral flow channel is formed by splicing the baffles, which avoids the triangular leakage problem of the conventional spiral baffle, improves the utilization efficiency of the heat exchange tube of the heat exchanger, and at the same time avoids the adverse effects of secondary vortex flow on the flow resistance of the heat exchanger, significantly reducing the shell side flow resistance of the heat exchanger. The heat transfer pressure drop test results of the composite flow guide type spiral baffle heat exchanger of this embodiment are shown in Figure 10 2 The average heat transfer coefficient of the heat exchanger is about 1500W / m

[0061] Comparative Example One

[0062] ​The comparative example adopts a conventional segmental baffle heat exchanger, and the operating condition parameters of the heat exchanger are the same as those of Example One, that is, the hot side is ethanol condensation, the ethanol vapor temperature is 80°C, the pressure is 108 kPa (a), and the flow rate is 20 t / h; the cold side is water evaporation, the cold side evaporation temperature is 75°C, and the pressure is 39 kPa (a). The heat exchanger heat load is 4710 kW; and the heat exchanger is operated in the vertical tube falling film heat exchanger mode.

[0063] The heat exchange tube specification of the comparative example is φ38 mm x 9000 mm; the heat exchanger shell adopts a middle steam inlet mode, the segmental baffle is a 25% gap-shaped sector plate, the baffle has no steam condensate drainage and steam purging structure design, and 20 t / h of ethanol vapor is all introduced into the shell side of the heat exchanger and heats the water in the heat exchange tube. The relevant data of Comparative Example One and Example One are shown in Table 1.

[0064] The conventional segmental baffle adopted by Comparative Example One has a serious problem of condensate accumulation outside the tube, the segmental baffle perpendicular to the heat exchange tube cannot effectively drain the condensate outside the tube, the liquid film at the bottom of the heat exchange tube is thick, the heat transfer thermal resistance is increased, the heat exchanger heat transfer coefficient is low, in addition, the shell side fluid of the segmental baffle heat exchanger flows in a "Z" shape, the heat exchanger shell side resistance is large, and the effective heat transfer temperature difference of the heat exchanger is greatly attenuated; in comparison, the composite drainage closed spiral baffle adopted by Example One has a certain inclination angle with the heat exchange tube, when the condensate outside the tube falls on the surface of the baffle, under the action of the gravity component of the condensate along the inclined surface of the spiral plate and the purging gas, the condensate outside the tube can be effectively drained and separated from the outer wall of the heat exchange tube, the liquid film thickness of the condensate outside the lower heat exchange tube is effectively reduced, and the overall heat transfer performance of the heat exchanger is improved. Engineering practice has proved that under the same treatment load conditions, the area of the composite drainage spiral baffle heat exchanger described in Example One is reduced by about 30% compared with the heat exchange area of the conventional spiral baffle of Comparative Example One.

[0065] Table 1

[0066]

[0067] Example Two

[0068] This example takes a chloromethyl benzene heat pump rectifying column reboiler as an example to describe the structure principle and working method of the composite drainage closed spiral baffle heat exchanger of the present application.

[0069] The reboiler of this example operates in a thermosyphon rising film mode. The hot side of the heat exchanger is 105°C chloromethyl benzene vapor, and the cold side is 70% concentration chloromethyl benzene aqueous solution with a temperature of 85°C.

[0070] As Figure 11As shown, the composite baffle reboiler of the embodiment comprises: an upper head 1, an upper tube sheet 2, a shell 3, a baffle 4, a heat exchange tube 5, a pull 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, the upper tube sheet, the shell, the lower tube sheet, and the lower head are sequentially connected. The heat exchange tube 5 has a specification of φ25mm×6000mm, and the shell has an inner diameter of 1200mm. The outer wall of the shell is provided with a tangential steam inlet 31 at the upper portion and a condensate outlet 32 at the lower portion. 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 baffle 4 and the structure and installation mode of the purge main pipe 10 of the embodiment are similar to those of the first embodiment, and are not described herein again. The inclination angle of the baffle of the embodiment is 12°, the baffle is circumferentially divided into four parts, the height of the drainage weir plate is 30mm, the thickness of the drainage weir plate is 1.5mm, and the purge branch pipe 7 is a DN25 round pipe. The purge branch pipe is provided with purge holes with a spacing of 10mm and a diameter of 3mm.

[0071] The working method of the embodiment is as follows:

[0072] The reboiler of the embodiment operates in a thermosyphon climbing film mode. The hot side chloromethylbenzene steam passes through the shell side of the heat exchanger, and the cold side chloromethylbenzene aqueous solution passes through the tube side of the heat exchanger. The working process of the shell side medium is as follows: chloromethylbenzene steam at a temperature of 105℃ enters the spiral flow channel of the heat exchanger shell side through the tangential steam inlet 31. A small part of the chloromethylbenzene steam is supplied to the purge main pipe 10 as purge steam. The chloromethylbenzene steam flows downward along the spiral flow channel, continuously heating the liquid in the heat exchange tube. The chloromethylbenzene condensate is quickly drained under the synergistic action of the spiral baffle, the purge steam, and the U-shaped channel of the drainage weir plate, thereby reducing the thickness of the condensate film on the outer surface of the lower heat exchange tube and improving the heat transfer film coefficient of the shell side fluid of the heat exchanger.

[0073] The conventional technology causes the heat flux of the evaporating section of the heat exchange tube to be small due to the thick liquid film accumulated at the lower part of the heat exchange tube, and the amount of the secondary steam generated by the evaporation in the tube is insufficient to drag the film of the material liquid in the tube, so that there is a serious dry wall problem at the upper heat exchange tube, which causes the heat exchanger to be unable to stably and continuously operate in the evaporating mode. The composite drainage type helical baffle heat exchanger is used as the thermosyphon evaporating reboiler in the embodiment, and the synergistic effect of the helical baffle, the purging steam and the drainage weir plate effectively avoids the condensate accumulation problem of the lower heat exchange tube, which is beneficial to improve the heat transfer performance of the submerged section of the tube bundle of the heat exchanger, and the high heat flux density of the submerged section of the tube bundle ensures the generation of the secondary steam and the sustainability of the evaporating process, so that the heat exchanger can have a high heat transfer coefficient in the evaporating mode.

[0074] It should be noted that the above detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as those ordinarily used by a person of ordinary skill in the art to which the present application pertains.

[0075] It should be noted that the terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the exemplary embodiments described according to the present application. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise. In addition, it should be understood that when the terms "comprise" and / or "include" are used in the specification, they refer to the presence of a feature, step, operation, device, component, and / or combinations thereof.

[0076] It should be noted that the terms "first", "second", and the like in the specification and claims of the present application and the above-described drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or sequence. It should be understood that the terms used in this way can be interchanged as appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0077] In addition, the terms "comprise" and "have" 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 does not have to be limited to only those steps or units clearly listed, but can include other steps or units that are not clearly listed or inherent to the process, method, product or apparatus.

[0078] For purposes of the description hereinafter, the terms "upper", "lower", "right", "left", "rear", "front", "vertical", "horizontal", and derivatives thereof shall relate to the application as it is oriented in the drawing figures. The terms "on", "above", "under", "below" and derivatives thereof shall relate to the application as it is oriented in the drawing figures. Where, for purposes of clarity, directional terms are used in the description, it should be understood that relative terms such as "above" and "below" and "up" and "down" are used to describe the relative positions of the components as oriented in the drawings. The above terms are used only to explain the orientation of the components in the drawings. The above terms do not indicate or imply necessary or required orientations of the components in use or operation, unless otherwise indicated or implied by context. The terms "front" and "back", "forward" and "backward", "up" and "down" and "top" and "bottom" are not specifically referring to any particular feature of the device, unless otherwise indicated or implied by context. The terms "coupled" and "connected", along with derivatives thereof, are used to indicate that two elements, modules, components, devices, or the like cooperate or interact with each other. The term "coupled" or "connected" does not necessarily mean that the two elements are in direct physical or electrical contact with each other. The terms "coupled" and "connected" can mean that two or more elements, modules, components, devices, or the like co-operate, interact, or are assigned to work together.

[0079] In the detailed description above, reference is made to the accompanying drawings, which form a part hereof. In the drawings, similar symbols typically identify similar components, unless context dictates otherwise. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments can be used, and other changes can be made, without departing from the spirit or scope of the subject matter presented herein.

[0080] The above description is embodied in the context of preferred embodiments of the application. The application is not restricted to the details of the foregoing illustrative embodiments. The application can be practiced with modification and alteration and can have other uses within the scope of the disclosure. Any modifications or changes that are made to the described embodiments are considered to be within the scope of the application.

Claims

1. A composite drain closed helical baffle heat exchanger characterized by: The heat exchanger comprises an upper head, an upper tube plate, a shell, a baffle, a heat exchange tube, a pull rod, a purge branch pipe, a lower tube plate, a lower head and a purge main pipe. The heat exchanger is a vertical cylindrical structure, and the upper head, the upper tube plate, the shell, the lower tube plate and the lower head are sequentially connected to form a main body structure of the heat exchanger. The baffle comprises a sector, an upper baffle and a lower baffle, and is arranged in an inclined manner in the shell. A plurality of baffles are sequentially connected in a circumferential direction from top to bottom to form an axially closed spiral flow channel. A gap is formed between the outer edge of the sector and the shell to allow the condensed liquid to flow down along the inner wall of the shell. The heat exchange tube sequentially passes through the heat exchange tube hole in the upper tube plate and the lower tube plate and is fixed to the upper tube plate and the lower tube plate. The pull rod is arranged between the upper tube plate and the lower tube plate, passes through the pull rod hole in the baffle and is fixed to the upper tube plate, the baffle and the lower tube plate. A tangential steam inlet is arranged on the upper side of the shell. The inlet gas rotation direction is consistent with the spiral flow channel of the baffle. The purge main pipe is arranged at the central axis of the heat exchanger, is blocked at the lower end and penetrates the side wall of the upper tube plate and the upper head at the upper end. The purge branch pipe is arranged at the angle between the sector and the upper baffle of each baffle in the axial direction of the heat exchanger. The purge main pipe is in communication with the purge branch pipe. The purge branch pipe is provided with a purge hole in the inclined direction of the baffle. The upper edge of the upper baffle of the sector is flush with the highest point of the outer edge of the sector. The lower edge of the lower baffle is flush with the lowest point of the outer edge of the sector. When a plurality of baffles are connected, the bottom edge of the lower baffle of the baffle is completely overlapped with the top edge of the upper baffle of the baffle connected below. The diameter of the projection circle of the inner edge of the sector is equal to the outer diameter of the purge main pipe. A flow guide weir plate is welded on the upper surface of the baffle. The flow guide weir plate is parallel to the lower edge of the sector in the radial direction of the heat exchanger and is parallel to the heat exchange tube in the height direction. Adjacent flow guide weir plates and the sector form a U-shaped flow guide channel for the condensed liquid.

2. The composite drain closed spiral plate heat exchanger according to claim 1, characterized in that: The heat exchange tube hole of the baffle is circular, and the heat exchange tube is arranged in a triangular or square manner.

3. The composite drain closed spiral plate heat exchanger according to claim 1, characterized in that: A first material port is arranged on the top of the upper head. A spray head is arranged below the first material port. A second material port is arranged on the bottom of the lower head. A condensed liquid outlet is arranged on the lower side of the shell.

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

5. The composite drain closed spiral plate heat exchanger according to claim 4, characterized in that: The length of the purge branch pipe in the top view is 0.7-0.8 times the radius of the shell. The diameter of the purge main pipe is 0.15-0.2 times the diameter of the shell. The axial length of the baffle in the top view is 0.4-0.425 times the diameter of the shell.

6. The composite drain closed spiral plate heat exchanger according to claim 5, characterized in that: The arrangement spacing of the heat exchange tube on the baffle is not less than 1.4 times the diameter of the heat exchange tube.

7. The composite drain closed spiral plate heat exchanger according to claim 6, characterized in that: The height of the flow guide weir plate on the baffle is 0.5-1.5 times the diameter of the heat exchange tube.

8. The composite drain closed spiral plate heat exchanger according to claim 1, characterized in that: The purge branch pipe is a circular pipe, a square pipe, a rectangular pipe or a special-shaped pipe. The size of the purge hole is 0.1-0.4 times the diameter of the heat exchange tube.

9. The composite drain closed spiral plate heat exchanger according to claim 1, characterized in that: One or more tangential steam inlets are arranged. The number of pull rod holes of each baffle is not less than 3.

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