A vertical evaporator

Abstract

The present invention relates to a vertical evaporator, comprising a vertically arranged cylindrical evaporator shell, a cover above the upper end tube sheet; a cavity is formed between the cover and the upper end tube sheet, a vertical upward suction pipe is arranged at the center of the cover, and the cavity of the cover is connected with the refrigerant inlet and outlet through the heat exchange tube to form a refrigerant circuit; a support plate assembly for supporting and connecting the heat exchange tube is arranged in the evaporator shell below the suction port, and the support plate assembly includes at least one heat exchange tube support plate connected and fixed by a vertical tie rod and at least one air baffle arranged at intervals and located above the heat exchange tube support plate. Compared with the prior art, the vertical evaporator of the present invention has a simple structure, high heat exchange efficiency, and reduces the risk of liquid in the suction air.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial refrigeration heat exchange, and in particular relates to a vertical evaporator structure for a chiller. Background Art

[0002] Heat exchangers are common equipment in chemical, petroleum, power, food and many other industrial sectors, and they play an important role in production. In chemical production, heat exchangers can be used as heaters, coolers, condensers, evaporators and reboilers, and are more widely used.

[0003] Heat exchangers can be divided into two types in form: horizontal heat exchangers and vertical heat exchangers. The main differences between them are:

[0004] Horizontal heat exchanger: stable and safe, able to withstand higher working pressure and temperature; occupies a large area, the net height requirement for installation space is not high, maintenance and cleaning are convenient, and generally no platform is required; the hot and cold fluids can flow countercurrently and concurrently; the heat transfer coefficient is medium, the heating residence time is short, and the heat exchange effect is medium.

[0005] Vertical heat exchanger: stable and safe, needs to be laid vertically, usually adopts a tower structure; occupies less space, has high requirements for the net height of the installation space, has a compact structure, and is easy to pipe; the cold and hot fluids generally flow in countercurrent; the heat transfer coefficient is large, the heating residence time is short, and the heat exchange effect is better.

[0006] The evaporator is a device that evaporates liquid refrigerant into gas. The liquid refrigerant will boil violently during the heat exchange process. Usually, a certain space height is reserved between the liquid and gas refrigerants to ensure that the evaporator does not carry liquid when sucking air. For horizontal shell and tube evaporators, in order to ensure such a space height, no tubes are usually laid in the upper half of the tube sheet section (the tube laying rate is not high, about 50%), resulting in the disadvantages of large heat exchanger volume and high material cost. The vertical evaporator structure not only occupies a small area, but also can greatly improve the tube sheet tube laying rate (increased to 80% to 95%), reduce the heat exchanger volume, and reduce material costs. However, the existing vertical evaporator structure is rarely used due to the following technical disadvantages:

[0007] 1) The shell medium of the flooded evaporator is refrigerant. The air intake port 3 and the liquid refrigerant inlet 4 are both set horizontally. In order to avoid the compressor from sucking liquid, the refrigerant liquid level 2 needs to be lowered to a position below the air intake port 3, causing part of the heat exchange tube 1 to be exposed in the gaseous refrigerant. The heat exchange tube 1 cannot be fully used for heat exchange, resulting in low heat exchange efficiency of the evaporator. Figure 1 shown.

[0008] 2) The height of the refrigerant liquid level in the evaporator is mainly affected by the position of the air inlet and the pipe layout; in places where the heat exchange tubes 1 are arranged more densely and more, a large amount of gas-liquid mixture will gather due to evaporation and boiling, pushing up the liquid level; the closer to the air inlet 3, the higher the liquid level will be due to the influence of the suction pressure. Conventional vertical heat exchangers set the air inlet 3 on one side of the shell, so that the closer to the air inlet, the higher the liquid level, and the higher the risk of suction liquid. Figure 1 shown. Summary of the invention

[0009] In order to solve the above technical problems, the present invention provides a vertical evaporator with simple structure, high heat exchange efficiency and reduced risk of liquid inhalation.

[0010] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0011] A vertical evaporator comprises a vertically arranged cylindrical evaporator shell, wherein the upper and lower ends of the evaporator shell are respectively provided with an upper tube sheet and a lower tube sheet for arranging heat exchange tubes, and a cover is provided above the upper tube sheet; a heat exchange tube is arranged in the evaporator shell; the characteristics are as follows: a cavity is formed between the cover and the upper tube sheet, a vertical upward suction pipe is arranged at the center of the cover, a suction port is provided at the center of the upper tube sheet, heat exchange tubes are arranged around the suction port, the cavity of the cover is connected with the refrigerant inlet and outlet respectively through the heat exchange tube to form a refrigerant circuit; a refrigerant inlet is provided in the evaporator shell below the suction port A support plate assembly for supporting and connecting heat exchange tubes, the support plate assembly includes at least one heat exchange tube support plate connected and fixed by a vertical pull rod and at least one air baffle plate arranged at intervals and located above the heat exchange tube support plate, air vents are provided in the center and around the heat exchange tube support plate, heat exchange tube holes are arranged on the surface of the heat exchange tube support plate outside the central air vent, and the air baffle plate is arranged at intervals from the air intake port; the evaporator shell is connected to the refrigerant inlet, and the refrigerant after heat exchange and vaporization includes at least one flow path: after horizontal deflection through the air baffle plate, it finally flows out through the vertical intake pipe.

[0012] In the above technical scheme, the flow direction of the refrigerant airflow after heat exchange and vaporization includes at least two paths. One path rises vertically through the air vents around the heat exchange tube support plate, then passes through the upper end tube plate baffle and converges to flow out through the vertical intake pipe. The other path goes upward through the central air vent of the heat exchange tube support plate, passes through the horizontal baffle of the air baffle, rises, passes through the double-end tube plate baffle and converges to flow out through the vertical intake pipe.

[0013] In the above technical solution, the area of ​​the air baffle is greater than or equal to the area of ​​the air intake port.

[0014] In the above technical solution, an air intake port is opened at the center of the upper tube plate.

[0015] In the above technical solution, a partition is arranged in the cavity between the cover and the upper tube sheet, and the heat exchange tube forms different sections through the partition to be connected with the refrigerant inlet and outlet respectively to form a refrigerant circuit.

[0016] In the above technical solution, at least one layer of heat exchange tube support plate is arranged in the shell of the tubular evaporator, and the air vents are arranged at intervals around the heat exchange tube support plate.

[0017] In the above technical solution, the heat exchange tube support plate is directly welded and fixed to the inner wall of the shell; or a gap is left between the heat exchange tube support plate and the inner wall of the shell and the heat exchange tube support plate is welded and fixed via a boss.

[0018] In the above technical solution, the liquid inlet is arranged above the lower end tube plate and located in the space below the lowest layer of support plate.

[0019] In the above technical solution, the air baffle has micro holes or no holes.

[0020] The working principle of the present invention is as follows:

[0021] After the liquid refrigerant enters the evaporator shell through the liquid inlet pipe, it exchanges heat with the refrigerant in the heat exchange tube. The refrigerant gas generated by the heat exchange rises through the support plate. Since the support plate has a vent hole in the center and vent gaps (a type of vent hole) on all sides, an air baffle is provided between the support plate and the upper tube sheet. After evaporation, part of the gaseous refrigerant flows upward along the four sides of the cylinder to the top, and then gathers to the center of the tube sheet (intake port position), and the other part passes through the central vent hole of the support plate and is deflected by the air baffle to reach the intake port, thereby increasing the contact time between the refrigerant airflow and the heat exchange tube and improving the heat exchange efficiency. Since the intake position is located at the center of the tube sheet, it has a higher utilization rate and heat exchange efficiency of the heat exchange tube, and at the same time, it also makes the gas flow rate at the top of the evaporator more uniform, and the liquid level is relatively consistent with the intake port position, reducing the risk of liquid in the intake air.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] A unique tube sheet and head structure is designed. An air intake port is opened in the center of the upper tube sheet. Pipes are laid in the annular area between the air intake port and the cylinder (the pipe laying rate is about 85%). Since the air intake port is located on the tube sheet, a higher utilization rate of heat exchange tubes can be achieved, thereby improving heat exchange efficiency. At the same time, the air intake pipe located in the center of the tube sheet makes the air flow at the top of the evaporator more uniform, reducing the risk of liquid inhalation.

[0024] A heat exchange tube support plate group structure is designed, in which the support plate and the air baffle plate are fixed into an integral support plate group structure by a pull rod, and air vents are opened around and in the center of the support plate. An air baffle plate is provided between the support plate and the upper tube plate, and / or between the support plates, so that a part of the evaporated gaseous refrigerant flows upward along the four sides of the cylinder to the top, and then gathers to the center of the tube plate (the position of the air intake port), and the other part is repeatedly deflected through the center of the cylinder. This method increases the contact time between the refrigerant airflow and the heat exchange tube, and improves the heat exchange efficiency; at the same time, the air baffle plate located at the top can block the airflow in the center of the cylinder to prevent the airflow from directly entering the air intake pipe, thereby reducing the risk of liquid in the air intake.

[0025] The specific heat exchange tube support plate group structure and the upper end tube plate and head structure of the present invention have a gas phase space height that does not affect the tube layout of the tube plate (relative to the horizontal evaporator), thereby improving the heat exchange efficiency of the evaporator; under the same heat exchange area, the cylinder size can be reduced and the material consumption can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic diagram of the structure of a vertical evaporator in the prior art.

[0027] Figure 2 It is a schematic diagram of the structure of a vertical evaporator implemented according to the present invention.

[0028] Figure 3 for Figure 2 Perspective structure diagram.

[0029] Figure 4 for Figure 3 B-B section view.

[0030] Figure 5 for Figure 2 A perspective view from above.

[0031] Figure 6 for Figure 2 A perspective view of another embodiment, looking down.

[0032] Figure 7 This is a structural diagram of the support plate used in the present invention.

[0033] Figure 8 It is a three-dimensional schematic diagram of the support plate assembly structure of the present invention.

[0034] Fig. 9 Schematic diagram of gas flow in the present invention. DETAILED DESCRIPTION

[0035] According to the vertical evaporator implemented in the present invention, Figure 2-9As shown; it mainly includes: an evaporator shell 12, a lower end tube box assembly 13 connected to the bottom of the shell, and a cover 14 on the top of the shell, a lower end tube sheet 9, an upper end tube sheet 3, a heat exchange tube 1 connected to the lower end tube sheet 9 and the upper end tube sheet 3 respectively, at least one heat exchange tube support plate 7 for supporting the heat exchange tube 1, and a coolant inlet 10 and an outlet 11 connected to the heat exchange tube 1 (the coolant inlet and outlet or the inlet and outlet water pipes are all arranged in the lower end tube box (inlet from the bottom and outlet from the bottom). According to actual needs, the number of baffles can be adjusted to make the inlet and outlet water into a bottom-in and top-out mode. This adjustment belongs to the present invention. The known technology known to those skilled in the art can be adjusted according to common experience, and is not limited to the bottom-in and bottom-out embodiments given in the present invention); a liquid inlet pipe 6 is also provided on the shell 12, and the liquid inlet pipe 6 is connected to the space inside the shell 12; a vertical air intake pipe 5 is provided at the center of the cover 14, and the cover 14 is sealed and fixed to the upper end tube sheet 3 by a fixing device 4; an air baffle 8 is provided above the heat exchange tube support plate 7; the area of ​​the air baffle 8 is equal to or slightly larger than the inlet area of ​​the air intake pipe 5 to prevent the air flow from directly entering the air intake pipe 5 vertically from the bottom of the air intake pipe. After the liquid preparation enters the interior of the evaporator shell 12 through the liquid inlet pipe 6, it exchanges heat with the coolant in the heat exchange tube 1. The refrigerant gas generated by the heat exchange is deflected between the heat exchange tube support plate 7 and the air baffle 8, and then converges to the center and finally rises vertically from the air intake pipe 5 in the center of the cover 14 to the outside of the evaporator, realizing the function of heat exchange inside and outside the vertical evaporator tube.

[0036] Usually, a liquid balancing plate can be arranged behind the liquid inlet pipe 6 (see Appendix 1 of this application). Figure 3 The purpose is to distribute the liquid from the liquid inlet, reduce the flow rate, avoid the heat exchange tubes, and avoid directly flushing some heat exchange tubes. The liquid balancing plate can be selected and set according to containers of different specifications, which is not necessary for the present invention.

[0037] The upper tube sheet 3 is a special tube sheet structure, with an air intake port in the center of the tube sheet for placing and fixing the air intake pipe 5. A through hole is opened in the annular area between the air intake port or the air intake pipe 5 (with the same diameter) and the inner wall of the evaporator shell 12 to arrange the heat exchange tube 1 (the tube laying rate is about 85%). The cavity formed between the annular area of ​​the upper tube sheet 3 and the cover 14 can refer to the prior art to select the partition 15 to form a heat exchange circuit connected with the heat exchange tube 1 and the refrigerant inlet 10 and outlet 11. Since the air intake pipe 5 is located on the tube sheet, it has a higher heat exchange tube utilization rate and heat exchange efficiency; at the same time, the air intake pipe 5 located in the center of the tube sheet makes the airflow at the top of the evaporator more uniform, reducing the risk of air intake with liquid, such as Figure 2-4 shown.

[0038] like Figure 6The figure shows another embodiment of the air baffle 8', in which the air baffle 8' is provided with micro-through holes. This method can increase the flow area of ​​the gaseous refrigerant at the top of the cylinder and reduce the air flow rate, but it will increase the risk of liquid carryover. The risk can be reduced by adding a filter screen or other device to filter out the droplets according to the air flow rate. The heat exchange tube support plate 7 also forms a special structure of the support plate group structure (such as Figure 4-9 The heat exchange tube support plate 7 and the air baffle plate 8 are fixed to an integral support plate group structure by a pull rod 16. The heat exchange tube support plate 7 has an air vent 12-2 in the center and air gaps around it (such as the first type of air gap 12-3 and the second type of air gap 12-4, which can be fan-shaped, rectangular, arc-shaped quadrilateral or other easily formed shapes, and can be arranged in the same shape or in different shapes at intervals). An air baffle plate 8 is provided between the heat exchange tube support plates 7 and the uppermost heat exchange tube support plate 7. The air baffle 8 is provided to allow part of the evaporated gaseous refrigerant to flow upward along the channel between the evaporator shell 12 and the heat exchange tube support plate 7 to the top, and then gather to the center of the tube plate (the air inlet position), while the other part passes through the air vent 12-2 in the center of the evaporator shell 12 and is repeatedly deflected by the air baffle 8. This method increases the contact time between the refrigerant airflow and the heat exchange tube, and improves the heat exchange efficiency. At the same time, the air baffle 8 at the top can block the airflow in the center of the cylinder to prevent the airflow from directly entering the air intake pipe 5, reducing the risk of liquid in the air intake. Fig. 9 shown.

[0039] A certain circumferential gap may or may not be left between the heat exchange tube support plate 7 and the inner wall of the cylinder of the evaporator shell 12. If a circumferential gap is left, the diameter of the heat exchange tube support plate 7 is smaller than the inner diameter of the cylinder, and a boss may be provided on the outer wall of the heat exchange tube support plate 7, which is spot-welded to the inner wall of the evaporator shell 12 through the boss; if no circumferential gap is left, the heat exchange tube support plate 7 and the inner wall of the cylinder can be directly welded.

Claims

1. A vertical evaporator, comprising a vertically arranged cylindrical evaporator shell, wherein an upper tube sheet and a lower tube sheet for arranging heat exchange tubes are respectively arranged at the upper and lower ends of the evaporator shell, and a cover is provided above the upper tube sheet; a heat exchange tube is arranged in the evaporator shell; and the characteristics are as follows: A cavity is formed between the cover and the upper tube sheet, a vertical upward air intake pipe is arranged at the center of the cover, an air intake port is opened at the center of the upper tube sheet, heat exchange tubes are arranged around the air intake port, and the cavity of the cover is connected with the refrigerant inlet and outlet respectively through the heat exchange tubes to form a refrigerant circuit; a support plate assembly for supporting and connecting the heat exchange tubes is arranged in the evaporator shell below the air intake port, the support plate assembly includes at least one heat exchange tube support plate connected and fixed by a vertical pull rod and at least one air baffle plate arranged at intervals and located above the heat exchange tube support plate, air vents are opened in the center and around the heat exchange tube support plate, heat exchange tube holes are arranged on the surface of the heat exchange tube support plate around the central air vent, and the air baffle plate is arranged at intervals from the air intake port; the evaporator shell is connected with the refrigerant inlet, and the refrigerant after heat exchange and vaporization includes at least one flow path: after horizontal deflection through the air baffle plate, it finally flows out through the vertical intake pipe.

2. The vertical evaporator according to claim 1, characterized in that: The refrigerant gas flow direction after heat exchange vaporization includes at least two paths. One path rises vertically through the air vents around the heat exchange tube support plate, then passes through the upper end tube plate baffle to converge and flows out through the vertical suction pipe. The other path goes upward through the central air vent of the heat exchange tube support plate, passes through the horizontal baffle of the air baffle, rises, passes through the double-end tube plate baffle to converge and flows out through the vertical suction pipe.

3. The vertical evaporator according to claim 1, characterized in that: The area of ​​the air baffle is greater than or equal to the area of ​​the air intake port.

4. The vertical evaporator according to claim 1, characterized in that: An air intake port is provided in the center of the upper tube plate.

5. The vertical evaporator according to claim 1, characterized in that: A partition is arranged in the cavity between the cover and the upper end tube sheet, and the heat exchange tube forms different sections through the partition to be connected with the refrigerant inlet and outlet respectively to form a refrigerant circuit.

6. The vertical evaporator according to claim 1, characterized in that: At least one layer of heat exchange tube support plate is arranged in the shell of the drum-type evaporator, and air vents are arranged at intervals around the heat exchange tube support plate.

7. The vertical evaporator according to claim 1, characterized in that: The heat exchange tube support plate is directly welded to the inner wall of the shell; or a gap is left between the heat exchange tube support plate and the inner wall of the shell and the support plate is welded to the shell through a boss.

8. The vertical evaporator according to claim 1, characterized in that: The liquid inlet is arranged above the lower end tube plate and in the space below the lowest layer of support plates.

9. The vertical evaporator according to claim 1, characterized in that: The air baffle has micro-holes or no holes.

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