Multi-tube-pass shell-and-tube heat exchanger

Abstract

The invention provides a multi-tube-pass shell-and-tube heat exchanger. The multi-tube-pass shell-and-tube heat exchanger comprises a tube shell, heat exchange tubes, end sockets, a shell pass inlet connecting tube and a shell pass outlet connecting tube. The tube shell comprises a first tube shell and a second tube shell, the heat exchange tube comprises a first heat exchange tube and a second heat exchange tube, the sealing head comprises a first sealing head, a middle sealing head and a second sealing head, the first sealing head, the first tube shell, the middle sealing head, the second tube shell and the second sealing head are sequentially connected, and the first tube shell is communicated with the second tube shell through a connecting tube. The fluid flows of the tube passes at different positions can be controlled through the valves, so that the temperature of the tube pass outlet is controlled.

Description

Technical Field

[0001] The invention relates to a shell and tube heat exchanger, in particular to a shell and tube heat exchanger with controllable tube-pass output temperature. Background Art

[0002] Shell and tube heat exchangers are widely used in industries such as chemical, petroleum, refrigeration, nuclear energy and power. Due to the global energy crisis, in order to reduce energy consumption, the demand for heat exchangers in industrial production is increasing, and the quality requirements for heat exchangers are also getting higher and higher. In recent decades, although compact heat exchangers (plate, plate-fin, press-welded plate heat exchangers, etc.), heat pipe heat exchangers, direct contact heat exchangers, etc. have developed rapidly, shell and tube heat exchangers still dominate production and usage due to their high reliability and wide adaptability. According to relevant statistics, the use of shell and tube heat exchangers in industrial devices still accounts for about 70% of all heat exchangers.

[0003] The shell and tube heat exchanger used in the heat exchange of hot and cold fluids, if using a conventional structure with only one tube outlet, has the following problems in heat exchange with the heat source or cold source. First, because the heat exchange area of ​​the tube bundle in the conventional shell and tube heat exchanger is basically fixed, it is difficult to control the temperature of the heat exchange medium at the tube outlet when the medium temperature and flow rate at the tube inlet and the heat exchange medium temperature and flow rate at the shell inlet remain unchanged. If the temperature of the heat source or cold source is too high or too low, the heat exchanger is prone to temperature instability, which has a great impact on the service life of the heat exchanger; second, because the different input fluid temperatures lead to different output temperatures, and because the flow rates are fixed, it is impossible to make timely adjustments or additional components need to be set separately.

[0004] However, traditional heat exchangers also have the above problems. Under the new energy-saving and emission-reduction situation, their development is greatly restricted. Therefore, in view of these shortcomings, a simple shell and tube heat exchanger is developed, which can dynamically adjust the output temperature of the heat exchanger tube, so that the heat exchange area and heat exchange efficiency can be effectively improved, which is of great significance to industrial production and energy-saving and emission-reduction. Summary of the invention

[0005] In order to overcome the defects and shortcomings in the prior art, the present invention provides a shell and tube heat exchanger with a novel structure, which can effectively control the output temperature of the tube pass, thereby effectively improving the heat transfer efficiency.

[0006] In order to achieve the above object, the technical solution of the present invention is as follows:

[0007] A multi-tube shell and tube heat exchanger, the heat exchanger comprises a tube shell, a heat exchange tube, a head, a shell side inlet pipe and a shell side outlet pipe; characterized in that the tube shell comprises a first tube shell and a second tube shell, the heat exchange tube comprises a first heat exchange tube and a second heat exchange tube, the head comprises a first head, an intermediate head and a second head, the first head, the first tube shell, the intermediate head, the second tube shell and the second head are connected in sequence, and the first tube shell and the second tube shell are connected through a connecting pipe; the first heat exchange tube is arranged in the first shell, the second heat exchange tube is arranged in the second shell, the shell side inlet pipe is arranged at one end of the second shell close to the second head, the shell side outlet pipe is at one end of the first shell close to the first head, the tube side inlet is arranged in the first head, the tube side outlet comprises a first outlet and a second outlet, wherein the first outlet is arranged in the intermediate head, the second outlet is arranged in the second head, the first outlet pipe is connected to the first outlet, the second outlet pipe is connected to the second outlet, the first outlet pipe and the second outlet pipe are connected to the main outlet pipe, the first outlet pipe is provided with a first outlet valve, and the second outlet pipe is provided with a second outlet valve.

[0008] As an improvement, a first temperature sensor is provided at the first outlet pipe, a second temperature sensor is provided at the second outlet pipe, and a third temperature sensor is provided at the main outlet pipe. The controller controls the opening of the first outlet valve and the second outlet valve according to the temperatures monitored by the first temperature sensor, the second temperature sensor and the third temperature sensor, thereby controlling the outlet temperature to reach a predetermined temperature.

[0009] As an improvement, the tube side is the heat source and the shell side is the cold source. When the temperature detected by the third temperature sensor is lower than the predetermined temperature, the controller controls the opening of the first outlet valve to increase and the opening of the second outlet valve to decrease.

[0010] As an improvement, when the temperature detected by the third temperature sensor is higher than a predetermined temperature, the controller controls the opening of the first outlet valve to decrease and the opening of the second outlet valve to increase.

[0011] As an improvement, a shell-side valve is arranged on the connecting pipe, an output pipe is arranged on the connecting pipe between the shell-side valve and the first shell, and an output valve is arranged on the output pipe.

[0012] As an improvement, the controller includes a display, which displays the temperatures detected by the first temperature sensor, the second temperature sensor, and the third temperature sensor.

[0013] As an improvement, the heat exchanger is a horizontal heat exchanger, the inlet is located at the lower part of the heat exchanger, and the first outlet and the second outlet are located at the upper part of the heat exchanger.

[0014] Compared with the prior art, the present invention has the following advantages:

[0015] The present invention sets two outlets through the pipe, and the two outlets are at different positions, so that the fluids output from the two outlets participate in different areas of heat exchange, the second outlet participates in the entire heat exchange, and the first outlet participates in a part of the heat exchange, thus resulting in different temperatures of the fluids output from the two outlets. By setting two outlet valves, the output fluid flow of the first outlet and the second outlet is controlled, so that the temperature of the mixed fluids with different temperatures in the total outlet pipe can be controlled, so that different output temperatures are controlled when the output flow remains unchanged, avoiding the shortcomings of a single output temperature in the past, or controlling the output temperature by changing the output flow, and ensuring the fluid quantity and fluid temperature of the fluid output. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a structural schematic diagram of the shell and tube heat exchanger of the present invention.

[0017] Figure 2 It is another structural schematic diagram of the shell and tube heat exchanger of the present invention. DETAILED DESCRIPTION

[0018] The specific implementation modes of the present invention are described in detail below with reference to the accompanying drawings.

[0019] In this article, unless otherwise specified, “ / ” represents division, and “×” and “*” represent multiplication.

[0020] Figure 1 The shell and tube heat exchanger of the present application is disclosed. Figure 1 As shown, a multi-tube shell and tube heat exchanger, the heat exchanger includes a tube shell, a heat exchange tube, a head, a shell-side inlet pipe and a shell-side outlet pipe; the tube shell includes a first tube shell 1 and a second tube shell 2, the heat exchange tube includes a first heat exchange tube 3 and a second heat exchange tube 4, the head includes a first head 5, an intermediate head 6 and a second head 7, the first head 5, the first tube shell 1, the intermediate head 6, the second tube shell 2 and the second head 7 are connected in sequence, and the first tube shell 1 and the second tube shell 2 are connected through a connecting pipe 8; the first heat exchange tube 3 is arranged in the first shell 1, the second heat exchange tube 4 is arranged in the second shell 2, the shell-side The inlet 9 pipe is arranged at one end of the second shell body close to the second head 7, the shell side outlet 10 pipe is arranged at one end of the first shell body 1 close to the first head 5, the tube side inlet 11 is arranged at the first head 5, and the tube side outlet includes a first outlet 12 and a second outlet 13, wherein the first outlet 12 is arranged on the middle head, and the second outlet 13 is arranged on the second head, the first outlet pipe 14 is connected to the first outlet, the second outlet pipe 15 is connected to the second outlet, the first outlet pipe and the second outlet pipe are connected to the main outlet pipe 16, the first outlet pipe is provided with a first outlet valve 17, and the second outlet pipe is provided with a second outlet valve 18.

[0021] The first heat exchange tube is fixedly connected to the fixed tube sheets of the first head and the middle head, and the second heat exchange tube is fixedly connected to the fixed tube sheets of the second head and the middle head.

[0022] The present invention sets two outlets through the pipe, and the two outlets are at different positions, so that the fluids output from the two outlets participate in different areas of heat exchange, the second outlet participates in the entire heat exchange, and the first outlet participates in a part of the heat exchange, thus resulting in different temperatures of the fluids output from the two outlets. By setting two outlet valves, the output fluid flow of the first outlet and the second outlet is controlled, so that the temperature of the mixed fluids with different temperatures in the total outlet pipe can be controlled, so that different output temperatures are controlled when the output flow remains unchanged, avoiding the shortcomings of a single output temperature in the past, or controlling the output temperature by changing the output flow, and ensuring the fluid quantity and fluid temperature of the fluid output.

[0023] Preferably, the first outlet fluid exchanges heat with one third to two thirds of the shell side area, and the second outlet fluid exchanges heat with 100% of the shell side area. As an improvement, the first outlet fluid participates in the heat exchange of one half of the tube side area.

[0024] As an improvement, the connecting pipe 8 may be arranged in the middle head, preferably arranged on the side opposite to the first outlet of the middle head, for example Figure 1 The lower part of the.

[0025] As an improvement, the connecting pipe 8 can be arranged outside the middle head, preferably, one end of the first shell near the middle head extends out of the shell, and then connects to one end of the second shell near the middle head, for example Figure 2 The lower part of the.

[0026] A shell valve is provided on the connecting pipe, and an output pipe is provided on the connecting pipe between the shell valve and the first shell. The heat exchange fluid can be directly output by providing the output pipe, and the valve can control the amount of output fluid. For example, if the valve opening is large, the output is small, and if the valve opening is small, the output is large.

[0027] For improvement, a first temperature sensor is set at the first outlet pipe 14, a second temperature sensor is set at the second outlet pipe 15, and a third temperature sensor is set at the main outlet pipe 16. The controller controls the opening size of the first outlet valve 17 and the second outlet valve 18 according to the temperatures monitored by the first temperature sensor, the second temperature sensor and the third temperature sensor, thereby controlling the outlet temperature to reach a predetermined temperature.

[0028] The tube side is the heat source, and the shell side is the cold source. Both the heat source and the cold source are water.

[0029] As an improvement, when the temperature detected by the third temperature sensor is lower than the predetermined temperature, the controller controls the first outlet valve 17 to increase the opening degree and the second outlet valve 18 to decrease the opening degree. By increasing the flow rate of the high-temperature fluid at the first outlet and reducing the flow rate of the low-temperature fluid at the second outlet, the output temperature is increased to reach the predetermined temperature as soon as possible.

[0030] As an improvement, when the temperature detected by the third temperature sensor is higher than the predetermined temperature, the controller controls the first outlet valve 17 to decrease the opening degree and the second outlet valve 18 to increase the opening degree. By reducing the flow rate of the high-temperature fluid and increasing the flow rate of the low-temperature fluid, the output temperature is reduced to reach the predetermined temperature as soon as possible.

[0031] As an improvement, the controller is provided with a display, and the display displays the temperatures detected by the first temperature sensor, the second temperature sensor and the third temperature sensor. By displaying the temperatures, the user can make adjustments based on the temperatures.

[0032] As an improvement, the controller is provided with a human-computer interaction module, and the user can set the predetermined temperature through the human-computer interaction module. The user can input the temperature to be adjusted according to actual needs. By displaying the detected temperature, the user can also determine the achievable temperature, for example, the temperature of the first outlet is the highest temperature, and the temperature of the second outlet is the lowest temperature. Avoid users inputting unrealistic temperatures, such as lower than the lowest temperature or higher than the highest temperature.

[0033] As an improvement, a first pipe 19 connected to the first outlet pipe is provided between the first outlet valve and the first outlet, and a second pipe 20 connected to the second outlet pipe is provided between the second outlet valve and the second outlet. A first valve 21 is provided on the first pipe 19, and a second valve 22 is provided on the second pipe 20. Through the control of the first pipe, the second pipe and the valve, the function of directly outputting low-temperature and high-temperature fluids can be realized.

[0034] As an improvement, the heat exchanger is a horizontal heat exchanger, the inlet is located at the upper part of the heat exchanger, and the first outlet and the second outlet are located at the upper part of the heat exchanger.

[0035] A baffle 23 is provided in the shell to allow the fluid to flow through the entire pipe path to avoid short circuit problems.

[0036] As an improvement, the shell side and the tube side are countercurrent flows. In the first shell and / or the second shell, along the flow direction of the fluid in the tube side, the spacing of the baffles increases continuously from the tube side inlet to the middle of the tube side. Then from the middle of the tube side to the tube side outlet, the spacing of the baffles decreases continuously. Because in the countercurrent process, the heat exchange of the shell side and the tube side per unit length along the flow process of the fluid is relatively uniform, so that the overall heat exchange effect is the best. However, it was found in experiments and simulations that the heat exchange in the middle is significantly greater than the heat exchange at the tube side inlet and outlet. Therefore, by changing the spacing between the baffles, the heat exchange area between the tube side fluid and the shell side fluid in the baffles also changes. Therefore, the uneven heat exchange is compensated by the change in area, thereby further improving the heat exchange efficiency.

[0037] As an improvement, along the flow direction of the fluid in the tube, from the tube entrance to the middle of the tube, the distance between the baffles increases continuously. Then, from the middle of the tube to the tube exit, the distance between the baffles decreases continuously. The above changes in the range can make the heat exchange per unit length of the entire fluid movement more uniform, further improving the heat exchange efficiency.

[0038] The baffles are arranged in the vertical direction, including baffles located at the upper part and baffles located at the lower part, and the upper baffles and the lower baffles are arranged at intervals; in the first shell and / or the second shell, along the flow direction of the liquid in the shell side, the vertical height of the lower baffle extending upward from the bottom shell side inner wall gradually increases, and the vertical length of the upper baffle extending downward from the upper shell side inner wall gradually decreases.

[0039] During the research process, it was found that the heat exchange of the baffles of the traditional heat exchanger is uneven in the cross section in the direction of fluid flow. As the distance from the inlet increases, the density of the heat exchange liquid in the lower part of the shell is large, so the liquid flows downward, which significantly increases the heat exchange liquid in the lower part. Therefore, it is necessary to design a heat exchange structure for improvement. In the present invention, the height of the upper baffle and the lower baffle changes along the flow direction of the fluid, so that the liquid in the shell gradually moves closer to the center as it flows, so that the heat exchange tubes around the shell and tube center strengthen the heat exchange, which changes the previous heat exchange method, enhances the heat exchange efficiency at different positions, makes the heat exchange uniform as a whole, and further achieves the purpose of enhanced heat transfer.

[0040] As an improvement, in the first shell and / or the second shell, along the flow direction of the fluid in the shell side, the vertical height of the lower baffle extending upward from the bottom shell side inner wall gradually increases, and the vertical length of the upper baffle extending downward from the upper shell side inner wall gradually decreases. Through the above-mentioned amplitude changes, the overall heat exchange can be further uniform, and the purpose of enhancing heat transfer can be further achieved.

[0041] Although the present invention has been disclosed as 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, so the protection scope of the present invention shall be subject to the scope defined by the claims.

Claims

1. A multi-pass shell and tube heat exchanger, comprising a shell and tube, a heat exchange tube, a head, a shell-side inlet pipe and a shell-side outlet pipe; characterized in that: The tube shell includes a first tube shell and a second tube shell, the heat exchange tube includes a first heat exchange tube and a second heat exchange tube, the head includes a first head, an intermediate head and a second head, the first head, the first tube shell, the intermediate head, the second tube shell and the second head are connected in sequence, and the first tube shell and the second tube shell are connected through a connecting pipe; the first heat exchange tube is arranged in the first shell, the second heat exchange tube is arranged in the second shell, the shell side inlet pipe is arranged at one end of the second shell close to the second head, the shell side outlet pipe is at one end of the first shell close to the first head, the tube side inlet is arranged in the first head, the tube side outlet includes a first outlet and a second outlet, wherein the first outlet is arranged in the intermediate head, and the second outlet is arranged in the second head, the first outlet pipe is connected to the first outlet, the second outlet pipe is connected to the second outlet, the first outlet pipe and the second outlet pipe are connected to the main outlet pipe, the first outlet pipe is provided with a first outlet valve, and the second outlet pipe is provided with a second outlet valve.

2. The shell and tube heat exchanger according to claim 1, characterized in that: A first temperature sensor is provided at the first outlet pipe, a second temperature sensor is provided at the second outlet pipe, and a third temperature sensor is provided at the main outlet pipe. The controller controls the opening of the first outlet valve and the second outlet valve according to the temperatures monitored by the first temperature sensor, the second temperature sensor and the third temperature sensor, thereby controlling the outlet temperature to reach a predetermined temperature.

3. The heat exchanger according to claim 2, characterized in that The tube side is a heat source and the shell side is a cold source. When the temperature detected by the third temperature sensor is lower than a predetermined temperature, the controller controls the opening of the first outlet valve to increase and the opening of the second outlet valve to decrease.

4. The heat exchanger according to claim 3, characterized in that When the temperature detected by the third temperature sensor is higher than a predetermined temperature, the controller controls the opening of the first outlet valve to decrease and the opening of the second outlet valve to increase.

5. The heat exchanger according to claim 1, characterized in that A shell-side valve is arranged on the connecting pipe, and an output pipe is arranged on the connecting pipe between the shell-side valve and the first shell.

6. The heat exchanger according to claim 1, characterized in that The first outlet fluid exchanges heat with one third to two thirds of the shell side area, and the second outlet fluid exchanges heat with 100% of the shell side area.

7. The heat exchanger according to claim 6, characterized in that The first outlet fluid participates in the heat exchange of one-half of the tube side area.

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