A shell-and-tube heat exchanger for vapor-liquid mixed heat exchange and a heat exchange method thereof

Abstract

The application provides a shell-and-tube heat exchanger for vapor-liquid mixed heat exchange and a heat exchange method thereof. The shell-and-tube heat exchanger comprises a shell, a heat exchange tube, a liquid inlet connecting pipe, an inlet head and an outlet head. The first end and the second end of the heat exchange tube are fixedly connected to an inlet tube plate and an outlet tube plate respectively, wherein the first end is communicated with the inlet head, and the second end is not communicated with the outlet head. The heat exchange tube wall is provided with a vapor outlet hole for vapor outflow. The outlet tube plate is provided with through holes communicated with the shell and the outlet head. The shell-and-tube heat exchanger is a horizontal shell-and-tube heat exchanger. The through holes are provided in multiple numbers, and the distribution density of the through holes is increasingly large along the height direction from bottom to top. The application provides a shell-and-tube heat exchanger for direct vapor-liquid direct mixing. Through the change of the distribution density of the through holes in the up-down direction, the vapor-liquid heat exchange effect can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of two fluids direct mixing heat exchanger, especially relates to a kind of vapor-liquid mixing heat exchange tube and shell heat exchanger. BACKGROUND

[0002] Tube and shell heat exchanger is widely used in chemical industry, petroleum, refrigeration, nuclear power and power industry, due to the world energy crisis, in order to reduce energy consumption, the demand for heat exchanger in industrial production is also more and more, the quality requirement of heat exchanger is also more and more high.In recent decades, although compact heat exchanger (plate, plate fin, pressure welding plate heat exchanger, etc.), heat pipe heat exchanger, direct contact heat exchanger has been rapid development, but due to the tube and shell heat exchanger has high reliability and wide adaptability, it still occupies the dominant position of yield and amount, according to relevant statistics, at present, the amount of tube and shell heat exchanger in industrial device still accounts for about 70% of the total amount of heat exchanger.

[0003] At present, people usually use heat exchanger to heat water, in various tube and shell, plate heat exchanger, steam and water are in different channels, and heat exchange is realized by good conductor, water flow channel is generally coiled, tortuous setting, to increase the contact area with steam, so that it can be fully heated, thus there are complex structure, slow heating speed, vibration noise, low thermal efficiency and other defects, although through the installation of silencer can reduce noise to a certain extent, but must limit the flow and velocity of steam, there is still slow heating speed, low thermal efficiency.

[0004] The prior art also has some related inventions of vapor-liquid direct mixing heat exchange, for example, CN101532784A discloses a steam heating water bath type gasifier, which comprises a water storage cavity, a fluid outlet, a fluid inlet, a steam inlet, a heat exchange coil and an annular steam input pipe, a plurality of steam injection devices are arranged on the annular steam input pipe, the steam injection device comprises an elbow, one end of the elbow is communicated with the annular steam input pipe, the other end of the elbow is provided with a nozzle, a plurality of radial water suction holes are arranged on the elbow and communicated with the inner cavity of the nozzle, and the direction of the nozzle is consistent with the tangent direction of the annular steam input pipe. The steam injection device is used to replace the original straight pipe, so that the noise and vibration are reduced to the maximum, the service life of the gasifier is prolonged, the noise pollution is reduced, the water circulation disturbance caused during use can make the heat exchange efficiency of the gasifier higher and more sufficient, and almost no water temperature stratification phenomenon occurs. CN101988806A discloses a conical core steam-water mixer, characterized in that the upper end and the lower end of the cylinder body are connected with the upper cone body and the lower cone body respectively to form a hollow cavity, a steam diffusion pipe is arranged in the cylinder body, the steam diffusion pipe is conical in shape, and a plurality of steam diffusion holes are uniformly arranged on the side wall of the steam diffusion pipe and form a 45-degree angle with the steam diffusion pipe. Through the above arrangement, the cold water can be uniformly heated and the noise can be reduced.

[0005] In the prior art, there are many problems in steam and liquid mixing heat exchange, such as single heat exchange pipe, small heat exchange area of steam and liquid mixing heat exchange and the like. The present application adopts the structure of a tubular heat exchanger, expands the heat exchange area, increases the mixing area, and makes the mixing effect better through the distribution of the openings of the tube sheet. SUMMARY

[0006] In order to overcome the defects and deficiencies in the prior art, the present application provides a tubular heat exchanger for vapor-liquid mixing heat exchange and a heat exchange method thereof, which can expand the heat exchange area, increase the mixing area, and make the mixing effect better through the distribution of the openings of the tube sheet, so as to effectively improve the heat transfer efficiency.

[0007] In order to achieve the above-mentioned purpose, the technical scheme of the present application is as follows:

[0008] A shell-and-tube heat exchanger for vapor-liquid mixed heat exchange, comprising a shell, a heat exchange tube, a liquid inlet pipe, an inlet head and an outlet head, the liquid inlet pipe being arranged on the shell, the inlet head and the outlet head being respectively provided with a steam inlet pipe and a fluid outlet pipe; an inlet tube plate is arranged between the inlet head and the shell, and an outlet tube plate is arranged between the outlet head and the shell, the heat exchange tube being arranged in the shell, the first end and the second end of the heat exchange tube being fixedly connected to the inlet tube plate and the outlet tube plate respectively, wherein the first end is communicated with the inlet head, and the second end is not communicated with the outlet head; the heat exchange tube is provided with a steam outlet hole on the tube wall, and the outlet tube plate is provided with a through hole communicated with the shell and the outlet head, characterized in that the shell-and-tube heat exchanger is a horizontal shell-and-tube heat exchanger, and a plurality of through holes are arranged, and the distribution density of the through holes becomes smaller and smaller along the height direction from bottom to top.

[0009] As an improvement, the amplitude of the distribution density of the through holes becoming smaller and smaller along the height direction from bottom to top is continuously increased.

[0010] As an improvement, the liquid inlet pipe is arranged on the side close to the inlet head.

[0011] As an improvement, a plurality of baffles are arranged in the shell, the baffles comprising lower baffles arranged at the lower part of the shell and upper baffles arranged at the upper part of the shell, and the lower baffles and the upper baffles are distributed at intervals.

[0012] As an improvement, the liquid inlet pipe is arranged at the lower part of the shell.

[0013] As an improvement, the steam enters the heat exchange tube through the inlet head from the steam inlet pipe, and then comes out through the steam outlet hole of the heat exchange tube, and is mixed with the liquid entering through the liquid inlet pipe for heat exchange, and the heat-exchanged fluid enters the outlet head through the through hole of the outlet tube plate, and then flows out from the fluid outlet pipe.

[0014] As an improvement, the steam is water vapor, the liquid is cold water, and the heat-exchanged fluid is hot water.

[0015] As an improvement, a plurality of baffles are arranged in the shell, the baffles comprising lower baffles arranged at the lower part of the shell and upper baffles arranged at the upper part of the shell, and the lower baffles and the upper baffles are distributed at intervals.

[0016] As an improvement, the liquid inlet pipe is arranged at the lower part of the shell, and the baffle close to the liquid inlet pipe is the lower baffle.

[0017] As an improvement, the baffle close to the outlet tube plate is the lower baffle.

[0018] Compared with the prior art, the shell-and-tube heat exchanger has the following advantages:

[0019] The application sets multiple through holes on the outlet tube plate, and the distribution density of the through holes becomes smaller and smaller along the height direction from bottom to top. The first aspect can avoid a large amount of steam directly discharged without passing through the mixing and heat exchange because of small density and passing through the upper through hole upward. The second aspect also avoids the steam too much gathered in the upper part to cause the heat exchange effect to be poor, so that the steam flows from the lower part, and the liquid is also more in the lower part because of the gravity, so that the liquid and the steam are fully mixed in the lower part, and the steam gathering in the upper part is reduced, the heat exchange is uniform as a whole, the pressure in the tube shell is reduced, and the purpose of fully mixing and heat exchange is further achieved. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a structural schematic diagram of the tube shell heat exchanger of the application;

[0021] Figure 2 is a cross-sectional schematic diagram of the heat exchange pipe structure of the heat exchanger of the application;

[0022] Figure 3 is a longitudinal cross-sectional schematic diagram of the heat exchange pipe structure of the heat exchanger of the application. DETAILED DESCRIPTION

[0023] The specific embodiments of the application will be described in detail below with reference to the accompanying drawings.

[0024] In this paper, if not specially stated, the " / " represents division, and the "x", "*" represents multiplication.

[0025] A tube shell heat exchanger for mixing and heat exchange of steam and liquid, as shown in Figure 1 The tube shell heat exchanger includes a tube shell 1, a heat exchange pipe 2, a liquid inlet pipe 3, an inlet head 4 and an outlet head 5. The liquid inlet pipe 3 is arranged on the tube shell, the inlet head 4 and the outlet head 5 are respectively provided with a steam inlet pipe 6 and a liquid outlet pipe 7. An inlet pipe plate 8 is arranged between the inlet head 6 and the tube shell 1, and an outlet pipe plate 9 is arranged between the outlet head 7 and the tube shell 1. The heat exchange pipe 2 is arranged in the tube shell 1, and the first end 21 and the second end 22 of the heat exchange pipe are respectively fixedly connected to the inlet pipe plate 8 and the outlet pipe plate 9. The first end 21 is communicated with the inlet head 4, and the second end 22 is not communicated with the outlet head 5. The steam outlet hole 23 is arranged on the wall of the heat exchange pipe 2, and the through hole 10 is arranged on the outlet pipe plate to communicate the tube shell and the outlet head.

[0026] The steam enters the heat exchange tube 2 through the steam inlet pipe 6 and the head 4, and then flows out through the steam outlet hole 23 of the heat exchange tube 2. Since the second end of the heat exchange tube is a closed structure, the steam cannot directly enter the outlet head 5 through the second end, and thus must flow out through the steam outlet hole 23. The liquid flows in from the liquid inlet pipe 3, and then directly mixes and exchanges heat with the steam flowing out of the steam outlet hole 23 in the tube shell 1. The heat-exchanged fluid enters the outlet head through the through hole of the outlet tube plate, and then flows out from the fluid outlet pipe.

[0027] The present application provides a tube shell heat exchanger structure for direct mixing and heat exchange of steam and water. The heat exchanger can provide an expanded heat exchange area, increase the mixing area, and because of the tube shell heat exchanger, the steam in the heat exchange tube can also exchange heat with the liquid in the tube, so that the steam can exchange heat with the liquid both inside and outside the tube, prolonging the length and area of heat exchange, and allowing more heat exchange area to be distributed in a unit volume.

[0028] As an improvement, the tube shell heat exchanger is a horizontal tube shell heat exchanger, and the through holes 10 are arranged in multiple numbers, and the distribution density of the through holes 10 gradually decreases along the height direction from the bottom to the top. The purpose of arranging through holes with varying densities is to change the flow area of the heat-exchanged fluid, so that the flow area gradually decreases from the bottom to the top. The main purposes are as follows. First, because the steam has a small density, the discharged steam does not exchange heat in time, and thus may accumulate in the upper part, causing the pressure to increase, and the steam may directly flow out through the through holes in the upper part without mixing and heat exchange, thus reducing the short circuit of heat exchange. Second, if the through holes are not arranged, the liquid will be difficult to mix in the upper part due to the excessive steam, and thus small-flow through holes need to be arranged to reduce the pressure, while the flow area of the through holes is as small as possible to ensure the heat exchange effect. Third, because the flow area in the upper part is small, the steam flows from the lower part, and the liquid is more in the lower part due to gravity, so that the liquid and steam are fully mixed in the lower part, and the accumulation of steam in the upper part is reduced, so that the overall heat exchange is uniform, the pressure in the tube shell is reduced, and the purpose of full mixing and heat exchange is further achieved.

[0029] As an improvement, the distribution density of the through holes 10 gradually decreases along the height direction from the bottom to the top, and the amplitude of the decrease is continuously increased. By changing the amplitude of the distribution density of the through holes, that is, changing the amplitude of the flow area, the overall heat exchange can be further uniform, the pressure in the tube shell can be reduced, and the purpose of full mixing and heat exchange can be further achieved.

[0030] As an improvement, multiple baffles 11 are arranged in the tube shell, including a lower baffle in the lower part of the tube shell and an upper baffle in the upper part of the tube shell, and the lower baffle and the upper baffle are arranged at intervals. By arranging the baffles, the liquid flows tortuously, and the heat exchange effect is improved.

[0031] As an improvement, the liquid inlet pipe 3 is located on the side close to the inlet head 4. This arrangement ensures that the steam flow and liquid flow are in the same direction, thereby reducing flow resistance.

[0032] As an improvement, such as Figure 1 As shown, the liquid inlet connector is located at the lower part of the tube shell, and the lower baffle is located near the liquid inlet connector baffle. This arrangement ensures that the inlet fluid must flow upwards, preventing it from flowing through the lower part due to gravity, thereby improving heat exchange efficiency.

[0033] As an improvement, the steam is water vapor, the liquid is cold water, and the heat-exchanged fluid is hot water.

[0034] As an improvement, the distribution density of the steam outlet holes 23 of the heat exchange tubes increases from the inlet end cap 4 to the outlet end cap 5. This arrangement increases the flow area of ​​the steam outlet holes 23 along the direction of steam flow within the tubes. This improves the heat exchange efficiency. The heat exchange between the liquid and steam is divided into two parts: indirect heat exchange through the heat exchange tubes and heat exchange through the mixing of steam and liquid at the outlet holes 23. Since the steam inlet and liquid inlet are in the same direction, for example… Figure 1 The above approach aims to reduce flow resistance. However, this is essentially co-current heat exchange, which suffers from poor heat transfer efficiency. Furthermore, because the pressure is higher near the steam inlet, steam is more easily discharged, leading to uneven steam distribution. Therefore, further improvements are needed. By varying the distribution density of the steam outlet holes, the steam distribution can be improved, resulting in a more uniform distribution of steam at the rear compared to the front, or even a larger steam volume at the rear. Moreover, as the flow continues, the temperature difference between the hot and cold fluids gradually decreases. By increasing the steam flow rate at the rear, the overall heat transfer per unit area becomes more uniform.

[0035] As an improvement, the distribution density of the steam outlet holes 23 of the heat exchange tubes increases progressively from the inlet end cap 4 to the outlet end cap 5, thereby gradually increasing the steam output per unit length of the heat exchange tube. With continuous flow, the temperature difference between the hot and cold fluids gradually decreases. By increasing the steam output per unit length of the heat exchange tube, the steam flow rate is increased. This increased flow rate reduces the decrease in heat exchange caused by the shrinking temperature difference, resulting in a more uniform heat exchange per unit length. This overcomes the problem of uneven heat exchange in co-current heat exchangers, thus achieving the technical effect of improving heat exchange efficiency.

[0036] As an improvement, such as Figure 3As shown, the area of the through hole of the steam outlet hole 23 of the heat exchange tube is getting larger from the inlet head 4 to the outlet head 5. By so arranging, the flow area of the steam outlet hole 23 of the heat exchange tube is getting larger along the flow direction of the steam in the tube. By so arranging, the heat exchange effect can be improved. Because the heat exchange between the liquid and the steam is divided into two parts, one part is the indirect heat exchange through the heat exchange tube, and the other part is the mixed heat exchange of the steam and the liquid through the steam outlet hole 23. Because the steam inlet and the liquid inlet are in one direction, for example Figure 1 The above case is to reduce the flow resistance. However, the above case is actually equivalent to the downstream heat exchange, and there is the problem of poor heat exchange effect. Moreover, because the pressure near the steam inlet is larger, the steam is easier to be discharged, which also leads to the uneven distribution of the steam outlet quantity before and after. Therefore, further improvement is needed. By arranging the change of the distribution density of the steam outlet hole, the steam distribution can be improved, so that the steam distribution of the rear part is relatively uniform with the steam distribution of the front part, or the steam distribution quantity of the rear part is more, and the temperature difference between the cold and hot fluids is gradually reduced along the continuous flow. By increasing the steam flow of the rear part, the overall unit area heat exchange quantity is relatively uniform.

[0037] As an improvement, the area of the through hole of the steam outlet hole 23 of the heat exchange tube is getting larger from the inlet head 4 to the outlet head 5, and the increasing rate is continuously increasing, so that the steam outlet quantity of the unit length of the heat exchange tube is gradually increasing from the inlet head 4 to the outlet head 5. Along the continuous flow, the temperature difference between the cold and hot fluids is gradually reduced, and by gradually increasing the steam outlet quantity of the unit length of the heat exchange tube, the steam flow is increased, the heat exchange quantity caused by the temperature difference reduction due to the flow increase is reduced, so that the overall unit length heat exchange quantity is relatively uniform, overcoming the problem of uneven heat exchange quantity of the downstream heat exchanger, so as to achieve the technical effect of improving the heat exchange effect.

[0038] As an improvement, as shown in Figure 1 The baffle plate near the outlet tube plate is a lower baffle plate. Moreover, further improvement is made that the height of the baffle plate near the outlet tube plate is larger than the height of other baffle plates. Preferably, the height of the baffle plate near the outlet tube plate is 0.75-0.85 times the diameter of the shell 1, and is 1.2-1.3 times the height of other baffle plates. By arranging the height of the outlet baffle plate, the liquid can pass through the upper part as much as possible, and flush the steam in the upper part to avoid the steam gathering in the outlet tube plate. Moreover, the height of the baffle plate is matched with the change of the distribution density of the through hole 10, so that the liquid and the steam are fully mixed in the lower part, and the steam gathering in the upper part is reduced, so that the overall heat exchange is uniform, the pressure in the shell is reduced, and the purpose of fully mixed heat exchange is further achieved.

[0039] As an improvement, the spacing between the lower baffle plate near the outlet tube plate and the outlet tube plate is smaller than the spacing between the lower baffle plate near the outlet tube plate and the adjacent baffle plate. By reducing the spacing, the liquid flow is made to flow quickly, flushing the steam accumulated on the upper part of the baffle plate and other positions, reducing the upper steam accumulation, making the overall heat exchange uniform, reducing the pressure in the shell, and further achieving the purpose of sufficient mixing and heat exchange.

[0040] As an improvement, the height of the lower baffle plate gradually increases from the inlet head 4 to the outlet head 5. As the steam and liquid continuously exchange heat and flow, the steam, due to its small density, will increasingly accumulate in the upper part, causing the pressure in the upper part to increase. Because of the accumulation of steam in the upper part, the heat exchange effect is deteriorated, and therefore the continuous impact of the liquid is needed to disperse and mix the steam. Because the liquid has a large density, it is not easy to impact the upper part, and therefore by gradually increasing the height of the lower baffle plate, the flow of the liquid to the upper part is increased, so that the impact force increases along the flow direction, and compared to a baffle plate of the same height, the flow resistance is not large, and the steam and liquid are fully mixed, improving the heat exchange effect.

[0041] As an improvement, the height of the lower baffle plate gradually increases from the inlet head 4 to the outlet head 5. By the above arrangement, the steam and liquid are further fully mixed, and the heat exchange effect is improved.

[0042] As an improvement, the spacing between the adjacent baffle plates 11 gradually increases from the inlet head 4 to the outlet head 5. Because the steam continuously flows out as the fluid continuously flows, the fluid mixed with steam and liquid becomes more and more, and therefore the flow rate continuously increases. Especially because of the presence of steam, the steam-water mixture may exist, so that the flow rate increases during the flow process, and the noise continuously increases. By gradually increasing the spacing between the adjacent baffle plates, the flow speed is balanced, and large noise is avoided.

[0043] As an improvement, the spacing between the adjacent baffle plates 11 gradually increases from the inlet head 4 to the outlet head 5. The flow speed is further balanced, and the noise is further reduced.

[0044] As an improvement, the baffle plate is an arc-shaped baffle plate.

[0045] Although the present application has been disclosed with reference to the preferred embodiments, the present application 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 application, and therefore the scope of protection of the present application should be defined by the scope defined in the claims.

Claims

1. A shell-and-tube heat exchanger for vapor-liquid mixing heat exchange, the shell-and-tube heat exchanger comprising a shell, heat exchange tubes, a liquid inlet pipe, an inlet end cap, and an outlet end cap, wherein the liquid inlet pipe is disposed on the shell, and a steam inlet pipe and a fluid outlet pipe are respectively disposed on the inlet end cap and the outlet end cap; an inlet tube sheet is disposed between the inlet end cap and the shell, and an outlet tube sheet is disposed between the outlet end cap and the shell, wherein the heat exchange tubes are disposed in the shell, and a first end and a second end of the heat exchange tubes are respectively fixedly connected to the inlet tube sheet and the outlet tube sheet, wherein the first end communicates with the inlet end cap, and the second end is not communicated with the outlet end cap; a steam outlet hole is provided on the tube wall for gas outflow, and a through hole is provided on the outlet tube sheet for communicating with the shell and the outlet end cap, characterized in that... Steam enters the heat exchange tube through the steam inlet pipe and end cap, then exits through the steam outlet of the heat exchange tube, mixing and exchanging heat with the liquid entering through the liquid inlet pipe. The heat-exchanged fluid enters the outlet end cap through the through holes of the outlet tube sheet, and then flows out from the fluid outlet pipe. The shell-and-tube heat exchanger is a horizontal shell-and-tube heat exchanger, and multiple through holes are provided, with the density of the through holes decreasing from bottom to top.

2. The shell-and-tube heat exchanger for vapor-liquid mixing heat exchange as described in claim 1, characterized in that, Along the vertical direction from bottom to top, the rate at which the distribution density of the through holes decreases continuously increases.

3. The shell-and-tube heat exchanger as described in claim 1, characterized in that, The liquid inlet pipe is located on the side near the inlet cap.

4. The shell-and-tube heat exchanger as described in claim 1, characterized in that, Multiple baffles are installed inside the tube shell, including a lower baffle located at the bottom of the tube shell and an upper baffle located at the top of the tube shell, with the lower baffles and upper baffles distributed at intervals.

5. The shell-and-tube heat exchanger as described in claim 1, characterized in that, The liquid inlet connector is located at the bottom of the casing.

6. A heat exchange method for a shell-and-tube heat exchanger for vapor-liquid mixing heat exchange, wherein the shell-and-tube heat exchanger includes a shell, heat exchange tubes, a liquid inlet pipe, an inlet end cap, and an outlet end cap. The liquid inlet pipe is disposed on the shell, and a steam inlet pipe and a fluid outlet pipe are respectively disposed on the inlet end cap and the outlet end cap. An inlet tube sheet is disposed between the inlet end cap and the shell, and an outlet tube sheet is disposed between the outlet end cap and the shell. The heat exchange tubes are disposed in the shell, and a first end and a second end of the heat exchange tubes are respectively fixedly connected to the inlet tube sheet and the outlet tube sheet, wherein the first end communicates with the inlet end cap, and the second end communicates with the outlet end cap. The end is not connected to the outlet head; the heat exchange tube wall is provided with a steam outlet hole for gas outflow, and the outlet tube sheet is provided with a through hole connecting the shell and the outlet head. The shell-and-tube heat exchanger is a horizontal shell-and-tube heat exchanger. Multiple through holes are provided, and the distribution density of the through holes decreases along the height direction from bottom to top; steam enters the heat exchange tube from the steam inlet pipe through the head, and then exits through the steam outlet hole of the heat exchange tube, mixing and exchanging heat with the liquid entering through the liquid inlet pipe. The heat-exchanged fluid enters the outlet head through the through hole of the outlet tube sheet, and then flows out from the fluid outlet pipe.

7. The heat exchange method for a shell-and-tube heat exchanger as described in claim 6, characterized in that, The steam is water vapor, the liquid is cold water, and the fluid after heat exchange is hot water.

8. The heat exchange method for a shell-and-tube heat exchanger as described in claim 6, characterized in that, Multiple baffles are installed inside the tube shell, including a lower baffle located at the bottom of the tube shell and an upper baffle located at the top of the tube shell, with the lower baffles and upper baffles distributed at intervals.

9. The heat exchange method for a shell-and-tube heat exchanger as described in claim 8, characterized in that, The liquid inlet connector is located at the bottom of the tube shell, and the lower baffle is located near the liquid inlet connector baffle.

10. The heat exchange method for a shell-and-tube heat exchanger as described in claim 8, characterized in that, The baffle plate near the outlet tube sheet is the lower baffle plate.

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