A shell-and-tube heat exchanger with a hollow cavity baffle

Abstract

The present invention provides a shell-and-tube heat exchanger with a baffle plate having a hollow cavity. The baffle plate has a hollow cavity structure. Each heat exchange tube is divided into multiple segments, including a side heat exchange tube segment and a middle heat exchange tube segment. One end of the side heat exchange tube segment is connected to the front tube sheet or the rear tube sheet to communicate with the front head and the rear head, and the other end communicates with the hollow cavity of the baffle plate. Both ends of the middle heat exchange tube segment respectively communicate with the hollow cavities of adjacent baffle plates. In the present invention, the baffle plate is changed to a cavity structure, so that the tube-side fluid can be filled in the baffle plate, increasing the heat exchange area between the tube-side fluid and the shell-side fluid and further enhancing heat transfer.

Description

Technical Field

[0001] The present invention relates to a shell-and-tube heat exchanger, and more particularly to a shell-and-tube heat exchanger provided with baffles. Background Art

[0002] A heat exchanger is an indispensable device for realizing heat exchange and transfer in the chemical production process. In the fields of petrochemical industry, cryogenic refrigeration, air separation, seawater desalination, etc., it is often necessary to heat a low-temperature fluid or cool a high-temperature fluid, vaporize a liquid into steam or condense steam into a liquid. These processes are all closely related to heat transfer and can thus be completed by a heat exchanger.

[0003] Common heat exchangers include shell-and-tube heat exchangers and plate heat exchangers. Most traditional shell-and-tube heat exchangers use smooth tubes as the tubes for the heat exchanger. This traditional shell-and-tube heat exchanger has many disadvantages compared with various new types of plate heat exchangers. For example, the heat transfer efficiency is low and the volume of the heat exchanger is large. However, the shell-and-tube heat exchanger also has many advantages of its own, such as simple manufacturing, high temperature and high pressure resistance, and convenient maintenance. Therefore, it is urgent to develop a double-sided enhanced high-efficiency heat exchanger based on the traditional shell-and-tube heat exchanger. At present, there have emerged some high-efficiency heat exchangers in China that are secondarily developed based on smooth tubes, but the effect of enhancing heat transfer is not ideal.

[0004] So far, traditional high-efficiency heat exchangers mostly adopt a single heat transfer enhancement method. One is to use a rough surface enhanced heat transfer tube to form a detached eddy current by improving the design of the wall surface shape, so as to break the boundary layer and improve the heat transfer performance in the boundary layer. For example, transversely ribbed tubes, helically ribbed tubes, longitudinally ribbed tubes, corrugated tubes, positive spiral tubes, and finned tubes, etc. The other is to use a far-wall turbulence element to generate continuous eddy currents, and under the influence of centrifugal force, the fluid in the center of the tube and the fluid in the wall boundary layer are fully mixed. However, the heat transfer effect of a single method is not ideal.

[0005] In traditional baffle shell-and-tube heat exchangers, generally segmental baffles are used to support the tube bundle, and the materials used for the segmental baffles are steel plates or stainless steel plates. Traditional heat exchangers are all provided with baffles. For example, segmental baffles are provided to avoid fluid short-circuiting to achieve the purpose of enhancing heat transfer. However, although only using segmental baffles can achieve the purpose of enhancing heat transfer to a certain extent, it can still be further improved to achieve further enhancement of heat transfer. Summary of the Invention

[0006] In order to overcome the defects and deficiencies existing in the prior art, the present invention provides a shell-and-tube heat exchanger with a hollow cavity baffle, wherein the baffle is set as a hollow cavity structure, and the contact area between the two fluids is increased through the cavity, the heat transfer area is increased, the convective heat transfer coefficient of the shell side of the heat exchanger can be improved, and thus the heat transfer efficiency can be effectively improved.

[0007] To achieve the above object, the technical solution of the present invention is as follows:

[0008] A shell-and-tube heat exchanger with a hollow cavity baffle, the shell-and-tube heat exchanger comprising a shell, heat exchange tubes, a tube-side inlet pipe, a tube-side outlet pipe, a shell-side inlet nozzle and a shell-side outlet nozzle; a heat exchange tube bundle composed of a plurality of parallel heat exchange tubes is connected to a front tube sheet and a rear tube sheet; the front end of the front tube sheet is connected to a front head, and the rear end of the rear tube sheet is connected to a rear head; a baffle is arranged in the shell, and the heat exchange tubes pass through the baffle; characterized in that the baffle is of a hollow cavity structure, each heat exchange tube is divided into multiple segments, including a side heat exchange tube segment and a middle heat exchange tube segment, wherein one end of the side heat exchange tube segment is connected to the front tube sheet or the rear tube sheet to communicate with the front head and the rear head, and the other end communicates with the hollow cavity of the baffle, and both ends of the middle heat exchange tube segment respectively communicate with the hollow cavities of adjacent baffles.

[0009] As an improvement, the heat exchange fluids in the tube side and the shell side flow countercurrently. Along the flow direction of the fluid in the tube side, from the tube-side inlet to the middle position of the tube side, the volume of the hollow cavity of the baffle continuously decreases, and then from the middle position of the tube side to the tube-side outlet, the volume of the hollow cavity of the baffle continuously increases.

[0010] As an improvement, along the flow direction of the fluid in the tube side, from the tube-side inlet to the middle position of the tube side, the decreasing amplitude of the volume of the hollow cavity of the baffle continuously increases, and then from the middle position of the tube side to the tube-side outlet, the increasing amplitude of the volume of the hollow cavity of the baffle 11 continuously decreases.

[0011] As an improvement, the shell-and-tube heat exchanger is a horizontal shell-and-tube heat exchanger, the baffle is arranged in the up-down direction, and a sewage outlet is arranged at the lower end of the baffle.

[0012] As an improvement, the sewage outlet is connected to a sewage pipe, and the sewage pipe extends to the outside through the shell.

[0013] As an improvement, the tube-side inlet pipe is arranged on the rear head; the tube-side outlet pipe is arranged on the front head; the shell-side inlet nozzle and the shell-side outlet nozzle are both arranged on the shell.

[0014] As an improvement, the heat exchange tubes are connected to the baffle by welding.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] 1) The present invention changes the baffle to a cavity structure, so that the baffle can be filled with the tube-side fluid, increasing the heat exchange area between the tube-side fluid and the shell-side fluid and further strengthening heat transfer.

[0017] 2) The heat transfer area through the baffle cavity changes continuously with the flow of the fluid in the tube side, further enhancing heat transfer and improving the overall heat exchange efficiency.

[0018] 3) By setting the cavity structure, impurities in the tube-side fluid can be continuously removed, allowing the impurities to accumulate in the cavity and then being regularly discharged through the blowdown pipe, achieving the purpose of removing impurities in the circulating fluid.

[0019] 4) By setting the upper and lower heads, the fluids in the upper and lower heads are different, which can cause the fluid in the baffle cavity to form a disturbance.

[0020] 5) Regularly changing the fluid flow rates of the upper and lower heads causes the fluid in the baffle to form a circulating disturbance, thereby further enhancing heat transfer.

[0021] 6) By making the flow direction of the fluid entering the baffle cavity extend downward, it can further impact the bottom fluid flow in the baffle cavity, thereby forming a turbulent flow and achieving the purpose of enhancing heat transfer. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of a shell-and-tube heat exchanger of the prior art;

[0023] Figure 2 is a schematic structural diagram of the heat exchange tubes of a shell-and-tube heat exchanger with a hollow cavity baffle provided by the present invention;

[0024] Figure 3 Schematic structural diagram of a shell-and-tube heat exchanger with upper and lower heads provided by the present invention. Detailed Embodiments

[0025] The following will describe in detail the specific embodiments of the present invention with reference to the drawings.

[0026] In this article, if not otherwise specified, for formulas, " / " represents division, and "×", "*" represent multiplication.

[0027] It should be noted that if not otherwise specified, the two-phase flow mentioned in the present invention is a gas-liquid two-phase flow, and the gas here is an insoluble or poorly soluble gas, that is, during the heat exchange process, the gas will not dissolve in the liquid.

[0028] Figure 1Shown is a shell-and-tube heat exchanger in the prior art. The shell-and-tube heat exchanger includes a shell 1, heat exchange tubes 8, a tube-side inlet pipe 9, a tube-side outlet pipe 10, a shell-side inlet nozzle 2, and a shell-side outlet nozzle 3. A heat exchange tube bundle composed of a plurality of parallel heat exchange tubes 8 is connected to a front tube sheet 6 and a rear tube sheet 7. The front end of the front tube sheet 6 is connected to a front head 4, and the rear end of the rear tube sheet 7 is connected to a rear head 5. The tube-side outlet pipe 10 is arranged on the rear head 5. The tube-side inlet pipe 9 is arranged on the front head 4. The shell-side inlet nozzle 2 and the shell-side outlet nozzle 3 are both arranged on the shell 4. The tube-side fluid enters from the tube-side inlet pipe 9, exchanges heat with the fluid in the shell-side through the heat exchange tubes, and exits from the tube-side outlet pipe 10.

[0029] Figure 2 The present invention is shown in Figure 1 a shell-and-tube heat exchanger with a hollow cavity baffle improved on this basis. As Figure 2 shown, the shell-and-tube heat exchanger includes a shell 1, heat exchange tubes 8, a tube-side inlet pipe 9, a tube-side outlet pipe 10, a shell-side inlet nozzle 2, and a shell-side outlet nozzle 3. A heat exchange tube bundle composed of a plurality of parallel heat exchange tubes 8 is connected to a front tube sheet 6 and a rear tube sheet 7. The front end of the front tube sheet is connected to a front head 4, and the rear end of the rear tube sheet is connected to a rear head 5. A baffle 11 is arranged in the shell, and the heat exchange tubes 8 pass through the baffle 11. The remaining structures not described are Figure 1 the same.

[0030] Compared with Figure 1 the heat exchanger, as Figure 2 shown, the baffle 11 is of a hollow cavity structure, and each heat exchange tube 8 is divided into multiple sections, including side heat exchange tube sections 81, 82 and a middle heat exchange tube section 83. As Figure 2 shown, the front end of the side heat exchange tube section 81 is connected to the front tube sheet 6, communicates with the front head 4 through the front tube sheet 6, and the rear end communicates with the hollow tube cavity of the adjacent baffle 11. The rear end of the side heat exchange tube section 82 is connected to the rear tube sheet 7, communicates with the rear head 5 through the rear tube sheet 7, and the front end of the rear tube sheet communicates with the hollow tube cavity of the adjacent baffle 11. The two ends of the middle heat exchange tube section 83 respectively communicate with the hollow cavities of the adjacent baffles.

[0031] The present invention changes the baffle into a cavity structure, so that the baffle can be filled with the tube-side fluid, increasing the heat exchange area between the tube-side fluid and the shell-side fluid and further strengthening heat transfer. At the same time, because the cavity structure of the present invention increases the flow space of the tube-side, the flow resistance is further reduced.

[0032] As an improvement, as Figure 2 shown, the cavity structure in the baffle is an integrally continuous and connected cavity structure, so that the heat exchange tubes of the connected cavity structure are also connected to each other. For example Figure 2The middle upper and lower part is a cavity, and all the heat exchange tubes are connected to the cavity structure. Through the above-mentioned integrally connected cavity structure, the fluid pressure inside the heat exchange tubes can be redistributed, so that the internal fluid pressure is balanced, and the heat exchange effect is further improved.

[0033] As an improvement, the shell-and-tube heat exchanger is a horizontal shell-and-tube heat exchanger, the baffle plate 11 is arranged in the up-and-down direction, and a sewage outlet is arranged at the lower end of the baffle plate. As an improvement, the sewage outlet is connected to a sewage pipe, and the sewage pipe extends to the outer end through the shell.

[0034] By setting the cavity of the baffle plate in the present invention, while achieving enhanced heat transfer, the flow area of the tube-side fluid suddenly increases, so that impurities can be deposited at the bottom of the cavity, and then removed through impurity removal measures. Thus, the technical effect of removing impurities is achieved.

[0035] Preferably, the baffle plate is an arc-shaped baffle plate.

[0036] As an improvement, the heat exchange fluids in the tube side and the shell side flow countercurrently. Along the flow direction of the fluid in the tube side, from the tube side inlet to the middle position of the tube side, the volume of the hollow cavity of the baffle plate 11 (the length along the height direction and / or the width along the extending direction of the heat exchange tube 8) continuously decreases, and then from the middle position of the tube side to the tube side outlet, the volume of the hollow cavity of the baffle plate 11 continuously increases. Because in the countercurrent process, the heat exchange amount per unit length of the shell side and the tube side along the fluid flow process is relatively uniform, so that the overall heat exchange effect is the best. However, it is found in experiments and simulations that the heat exchange amount in the middle is significantly greater than that at the tube side inlet and outlet. Therefore, through the change of the volume of the hollow cavity, the heat exchange area between the tube-side fluid and the shell-side fluid in the hollow cavity also changes, and the heat exchange area also increases and decreases with the increase and decrease of the volume. Therefore, the uneven heat exchange amount is compensated through the area change, so as to further improve the heat exchange efficiency.

[0037] As an improvement, along the flow direction of the fluid in the tube side, from the tube side inlet to the middle position of the tube side, the decreasing amplitude of the volume of the hollow cavity of the baffle plate 11 (the length along the height direction and / or the width along the extending direction of the heat exchange tube 8) continuously increases, and then from the middle position of the tube side to the tube side outlet, the increasing amplitude of the volume of the hollow cavity of the baffle plate 11 continuously decreases. The above-mentioned amplitude change can make the heat exchange amount per unit length of the whole fluid movement more uniform, and further improve the heat exchange efficiency.

[0038] As an improvement, along the flow direction of the fluid in the tube side, from the tube side inlet to the middle position of the tube side, the number of baffle plates distributed per unit length continuously decreases. Then from the middle position of the tube side to the tube side outlet, the number of baffle plates distributed per unit length continuously increases.

[0039] As an improvement, along the flow direction of the fluid inside the tube pass, from the tube pass inlet to the middle position of the tube pass, the decreasing amplitude of the number of baffles distributed per unit length continuously increases. Then, from the middle position of the tube pass to the tube pass outlet, the increasing amplitude of the number of baffles distributed per unit length continuously decreases.

[0040] For the technical effects of the above changes in the number of baffle distributions, refer to the technical effects of the volume changes of the baffles mentioned above.

[0041] As an improvement, the inlet head 4 is divided into upper and lower parts 41 and 42 by a partition plate 12. Among them, the upper heat exchange tubes 111 are connected to the upper head 41, and the lower heat exchange tubes 112 are connected to the lower head 42. The upper head 41 and the lower head 42 are respectively provided with an upper inlet 91 and a lower inlet 92. The fluid flow rates of the upper inlet 91 and the lower inlet 92 can be controlled separately, preferably controlled by a controller. As an improvement, the fluid flow rates of the upper head 41 and the lower head 42 are different, so that the fluid flow rates entering the upper heat exchange tubes 111 and the lower heat exchange tubes 112 are different.

[0042] By setting the upper and lower heads so that the fluid flow rates of the upper and lower heads are different, the heat exchange tubes with more fluid can form a greater impact on the inside of the cavity, so that the fluid in the baffle cavity forms an upward or downward disturbance, and thus a circulating flow is formed inside, further strengthening heat transfer.

[0043] As an improvement, within a period T, within 0 - T / 2, the flow rate of the upper head is V1, and the flow rate of the lower head is V2, where V1 is greater than V2, so that the fluid flow rate in the upper heat exchange tubes is greater than that in the lower heat exchange tubes. Within T / 2 - T, the flow rate of the lower head is V1, and the flow rate of the upper head is V2, so that the fluid flow rate in the lower heat exchange tubes is greater than that in the upper heat exchange tubes. Regularly changing the fluid flow rates of the upper and lower heads makes the fluid in the baffle form a circulating disturbance, and the circulating disturbance regularly changes the direction of the circulating impact, thereby further strengthening heat transfer.

[0044] Preferably, the period T can be 30 - 50 minutes.

[0045] Preferably, V1 is 3 - 5 times of V2.

[0046] As an improvement, the fluids entering the upper head and the lower head are pulsating flows with continuously changing flow velocities. By continuously impacting the fluid in the baffle cavity with the pulsating flows, the fluid is continuously disturbed.

[0047] Preferably, within one period T, from 0 to T / 2, the flow velocity of the upper head continuously increases from 0 to V, and the velocity of the lower head continuously decreases from V to 0; within T / 2 to T, the flow velocity of the lower head continuously increases from 0 to V, and the velocity of the upper head continuously decreases from V to 0. By continuously changing the flow velocity of the fluid passing through the upper and lower heads, the direction of fluid disturbance is continuously changed, thereby promoting further heat transfer.

[0048] As an improvement, the inlet of the heat exchange tube connected to the lower end of the baffle plate is inclined downward. By making the flow direction of the fluid entering the baffle cavity extend downward, the bottom fluid flow in the baffle cavity can be further impacted, thereby forming a turbulent flow and achieving the purpose of enhancing heat transfer.

[0049] Preferably, the included angle between the inlet and the horizontal direction is 45 - 80°, preferably 60°.

[0050] As an improvement, the inlet pipe of the tube side is arranged on the rear head; the outlet pipe of the tube side is arranged on the front head; the inlet nozzle and the outlet nozzle of the shell side are both arranged on the shell, and the heat exchange tubes are connected to the baffle plate by welding.

[0051] Although the present invention has been disclosed above with preferred embodiments, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A shell-and-tube heat exchanger with a hollow cavity baffle, the shell-and-tube heat exchanger comprising a shell, heat exchange tubes, a tube-side inlet pipe, a tube-side outlet pipe, a shell-side inlet nozzle and a shell-side outlet nozzle; a heat exchange tube bundle composed of a plurality of parallel heat exchange tubes is connected to a front tube sheet and a rear tube sheet; the front end of the front tube sheet is connected to a front head, and the rear end of the rear tube sheet is connected to a rear head; a baffle is arranged in the shell, and the heat exchange tubes pass through the baffle; characterized in that, The baffle plate is of a hollow cavity structure. Each heat exchange tube is divided into multiple sections, including a side heat exchange tube section and a middle heat exchange tube section. One end of the side heat exchange tube section is connected to the front tube sheet or the rear tube sheet to communicate with the front head and the rear head, and the other end communicates with the hollow cavity of the baffle plate. Both ends of the middle heat exchange tube section communicate with the hollow cavities of adjacent baffle plates respectively.

2. The shell-and-tube heat exchanger with a hollow cavity baffle as claimed in claim 1, characterized in that, The heat exchange fluids in the tube side and the shell side flow countercurrently. Along the flow direction of the fluid in the tube side, from the tube side inlet to the middle position of the tube side, the volume of the hollow cavity of the baffle plate continuously decreases, and then from the middle position of the tube side to the tube side outlet, the volume of the hollow cavity of the baffle plate continuously increases.

3. The shell-and-tube heat exchanger with a hollow cavity baffle as claimed in claim 2, wherein Along the flow direction of the fluid in the tube side, from the tube side inlet to the middle position of the tube side, the decreasing amplitude of the volume of the hollow cavity of the baffle plate continuously increases, and then from the middle position of the tube side to the tube side outlet, the increasing amplitude of the volume of the hollow cavity of the baffle plate continuously decreases.

4. The shell-and-tube heat exchanger with a hollow cavity baffle as claimed in claim 1, wherein The shell-and-tube heat exchanger is a horizontal shell-and-tube heat exchanger. The baffle plates are arranged in the up-down direction, and a sewage discharge port is arranged at the lower end of the baffle plate.

5. The shell-and-tube heat exchanger with a hollow cavity baffle as claimed in claim 4, wherein The sewage discharge port is connected to a sewage discharge pipe, and the sewage discharge pipe extends to the outer end through the shell.

6. The shell-and-tube heat exchanger with a hollow cavity baffle as claimed in claim 4, wherein, The tube side inlet pipe is arranged on the rear head; the tube side outlet pipe is arranged on the front head; the shell side inlet nozzle and the shell side outlet nozzle are both arranged on the shell.

7. The shell-and-tube heat exchanger with a hollow cavity baffle as described in claim 1, characterized in that, The heat exchange tubes are connected to the baffle plates by welding.

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