Falling film evaporator

Abstract

The invention belongs to the technical field of evaporation heat exchangers, and discloses a falling film evaporator. The falling film evaporator comprises an evaporator cylinder, a liquid inlet for refrigerant liquid to enter is formed in the evaporator cylinder, a plurality of gas outlets for refrigerant gas evaporated out to be discharged are formed in the upper end of the evaporator cylinder, and an oil outlet is formed in the bottom of the evaporator cylinder. A liquid baffle is horizontally arranged below the liquid inlet so as to divide the refrigerant liquid; a plurality of liquid distribution discs are horizontally arranged below the liquid baffles, a liquid spraying disc is horizontally arranged below the last liquid distribution disc, and a plurality of falling film type tube bundles are arranged below the spraying disc. According to the falling film evaporator, refrigerant filling can be reduced, the heat transfer efficiency is improved, meanwhile, a falling film can be formed more easily, a uniform liquid film is formed, and the dry evaporation phenomenon is avoided.

Description

Technical Field

[0001] The invention relates to the technical field of evaporative heat exchangers, and in particular to a falling film evaporator. Background Art

[0002] The centrifugal chiller is a unit composed of a centrifugal refrigeration compressor as the main body, an evaporator, a condenser, a throttling device and an economizer auxiliary equipment. During the operation of the unit, the refrigerant passes through the evaporator, where the refrigerant absorbs heat from the refrigerant and boils and evaporates, transporting the cooled refrigerant to the terminal equipment, absorbing heat from the air, and the heated refrigerant returns to the evaporator to complete the reflux of the refrigerant. The refrigerant vapor generated by boiling in the evaporator is sucked into the compressor, and the rotating impeller increases its pressure and temperature and discharges it into the condenser. The condensed refrigerant is discharged from the condenser into the liquid return pipe, and the liquid refrigerant flows to the evaporator after passing through the throttling device to complete the refrigerant reflux. Based on the above, it can be seen that the heat exchange efficiency of the evaporator is one of the important factors affecting the operation of the unit. Improving the efficiency of the evaporator is conducive to improving the overall efficiency of the unit.

[0003] At present, there are two main types of evaporators used in the prior art: one is a flooded evaporator and the other is a falling film evaporator. Among them, the flooded evaporator has a simple structure and is easy to maintain, but requires a large amount of refrigerant and has a general heat transfer effect. Because the liquid pool has a certain height, the evaporating bubbles need to overcome a certain liquid pressure during the rising process. For example, the flooded evaporator disclosed in the prior art CN201921012469.1, and the structural schematic diagram of the flooded evaporator provided by it is as follows Figure 1 The falling film evaporator has the characteristics of only needing to fill a small amount of refrigerant, the evaporation efficiency is improved, and the heat transfer effect is better, but it is difficult to control the formation of a uniform liquid film. For example, the prior art CN201620976953.6 discloses a distributed falling film evaporator, and the structural schematic diagram of the distributed falling film evaporator provided by it is shown as follows Figure 2 shown. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides a falling film evaporator.

[0005] A falling film evaporator of the present invention is realized by the following technical scheme:

[0006] The invention provides a falling film evaporator, comprising an evaporator cylinder, a liquid inlet, a plurality of gas outlets, a liquid baffle, a plurality of liquid distribution plates, a liquid spray plate, a plurality of falling film tube bundles and an oil outlet.

[0007] It should be noted that the evaporator cylinder of the present invention has a cavity inside.

[0008] The present invention does not limit the specific location of the liquid inlet, which can be set according to actual conditions. In some preferred embodiments of the present invention, the liquid inlet is arranged at the upper end of the evaporator cylinder to allow the refrigerant liquid to enter the evaporator cylinder.

[0009] In the present invention, a plurality of gas outlets are arranged at the upper end of the evaporator cylinder for discharging evaporated refrigerant gas.

[0010] In the present invention, the liquid baffle is horizontally arranged below the liquid inlet to divert and slow down the refrigerant liquid input through the liquid inlet, thereby preventing liquid splashing and allowing the liquid to enter the uppermost liquid distribution plate more smoothly.

[0011] In the present invention, a plurality of the liquid distribution plates are horizontally arranged below the liquid baffle plate, so that the liquid diverted by the liquid baffle plate can enter the uppermost liquid distribution plate more smoothly.

[0012] The present invention does not limit the specific number of liquid distribution plates, and the number of liquid distribution plates can be flexibly adjusted according to the cylinder diameter and the heat exchange effect. In some preferred embodiments of the present invention, the centers of several liquid distribution plates are located on the same axis, and the width of each liquid distribution plate is greater than the width of the previous liquid distribution plate adjacent to it, so as to ensure that the liquid distribution plate can completely receive the liquid from the previous liquid distribution plate adjacent to it. At the same time, since the area is increased compared to the previous liquid distribution plate, it is beneficial to increase the laying area of ​​the refrigerant liquid, thereby improving the uniformity of the distribution of the refrigerant liquid.

[0013] In some preferred embodiments of the present invention, a plurality of diversion tubes are arranged in each of the liquid distribution plates, and the plurality of diversion tubes are arranged in parallel, so that the liquid diverted by the liquid baffle plate can enter the topmost liquid distribution plate more smoothly, so that the plurality of diversion tubes are evenly immersed in the liquid of the liquid distribution plate, and then as the amount of liquid gradually increases, it overflows from both sides and flows into the liquid distribution plate below.

[0014] In the present invention, the liquid spray plate is horizontally arranged below the last liquid distribution plate, and the width of the liquid spray plate is greater than the width of the last liquid distribution plate; and a plurality of falling film tube bundles are horizontally arranged below the liquid spray plate, so that the refrigerant liquid treated by the liquid spray plate can produce a uniform liquid film on the surface of the falling film tube bundle below to achieve the optimal heat exchange mode, thereby improving the heat exchange efficiency and reducing the amount of refrigerant.

[0015] In the present invention, the center of the liquid spray plate and the center of the last liquid distribution plate are located on the same axis, so that the falling film evaporator of the present invention can work normally under a certain tilt condition.

[0016] In the present invention, the oil outlet is arranged at the bottom of the evaporator cylinder, so that the excess refrigerant and lubricating oil mixture can be discharged at the oil outlet for separation, and the lubricating oil is recovered and re-input into the compressor to form an oil circuit circulation part.

[0017] In some preferred embodiments of the present invention, the liquid distribution plate is at a low height, and the refrigerant liquid vaporized at the bottom is more likely to rise to the liquid surface and overflow. Since refrigerant continuously enters the distribution plate, the distribution plate is closer to the liquid inlet, the refrigerant flow therein is enhanced, and the heat exchange efficiency is improved.

[0018] In some preferred embodiments of the present invention, a plurality of liquid spray holes are evenly distributed on the liquid spray plate, so that a uniform liquid film is generated on the surface of the falling film tube bundle below to achieve an optimal heat exchange mode, thereby improving the heat exchange efficiency and reducing the amount of refrigerant. The size of the liquid spray hole is flexibly designed according to the cooling capacity of the evaporator.

[0019] In some preferred embodiments of the present invention, the falling film evaporator also includes a plurality of gas-liquid separation devices, which are all arranged in the evaporator cylinder, and are respectively located at the bottom of the corresponding gas outlet. The evaporated refrigerant gas is discharged from the gas outlet. The gas-liquid separation device can effectively separate the liquid entrained in the refrigerant gas to prevent the compressor from inhaling liquid.

[0020] In some preferred embodiments of the present invention, two gas outlets are provided, and the two gas outlets are arranged in mirror symmetry along the central axis of the liquid inlet to improve the stability and efficiency of gas outlet.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The falling film evaporator of the present invention comprises an evaporator cylinder, the evaporator cylinder is provided with a liquid inlet for refrigerant liquid to enter, and the upper end of the evaporator cylinder is provided with a plurality of gas outlets for refrigerant gas to be discharged from the evaporated state, and the bottom of the evaporator cylinder is provided with an oil outlet; a liquid baffle is horizontally provided below the liquid inlet to divert the refrigerant liquid; a plurality of liquid distribution plates are horizontally provided below the liquid baffle, a liquid spray plate is horizontally provided below the last liquid distribution plate, and a plurality of falling film tube bundles are provided below the spray plate. Among them, the present invention can divert and reduce the speed of the refrigerant liquid input through the liquid inlet by horizontally arranging the liquid baffle plate below the liquid inlet, thereby preventing the refrigerant liquid from splashing and allowing the refrigerant liquid to enter the uppermost liquid distribution plate more smoothly. Since the liquid distribution plate of the present invention includes several liquid distribution plates, and the centers of the several liquid distribution plates are all located on the same axis, and the width of the liquid distribution plate is greater than the width of the previous liquid distribution plate adjacent to it, the liquid distribution plate can completely receive the refrigerant liquid from the previous liquid distribution plate adjacent to it. At the same time, since the area is increased compared to the previous liquid distribution plate, it is beneficial to increase the laying area of ​​the refrigerant liquid, thereby improving the uniformity of the distribution of the refrigerant liquid. In addition, the present invention greatly improves the uniformity of the distribution of the refrigerant liquid on the same horizontal plane by horizontally arranging the liquid spray plate below the last liquid distribution plate, and after the several liquid distribution plates are laid and distributed in sequence, the refrigerant liquid treated by the last liquid distribution plate can produce a uniform liquid film on the surface of the falling film tube bundle below it, thereby greatly increasing the heat exchange contact surface of the refrigerant liquid through the formation of a uniform liquid film, thereby achieving the best heat exchange mode, thereby reducing the amount of refrigerant while improving the heat exchange efficiency.

[0023] The falling film evaporator of the present invention can reduce the refrigerant filling, improve the heat transfer efficiency, and make the falling film easier to form and form a more uniform liquid film, thereby avoiding the occurrence of the "dry evaporation" phenomenon. In addition, the present invention can control the distribution uniformity of the liquid film by controlling the number of liquid distribution plates and the number of shunt pipes on each liquid distribution plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a structural schematic diagram of the flooded evaporator of the prior art CN201921012469.1.

[0025] Figure 2 This is a structural schematic diagram of the distributed falling film evaporator of the prior art CN201620976953.6.

[0026] Figure 3 It is a schematic diagram of the internal structure of the falling film evaporator of the present invention.

[0027] Figure 4 It is a schematic structural diagram of the liquid spray holes on the liquid spray plate of the present invention.

[0028] Figure 5 It is a schematic diagram of the overall structure of the falling film evaporator of the present invention. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below.

[0030] The present invention analyzes the flooded evaporator provided by the prior art CN201921012469.1 and finds that Figure 1 As shown, the prior art CN201921012469.1 provides a flooded evaporator including a cylinder, an upper cavity and a lower cavity. The upper cavity and the lower cavity are formed in the internal space of the cylinder, and the upper cavity and the lower cavity are separated and arranged up and down, and the upper cavity is connected to the lower cavity; an upper baffle member and a lower baffle member, the upper baffle member divides the upper cavity into a tortuous flow channel, and the lower baffle member divides the lower cavity into a tortuous flow channel; a heat exchange tube, the heat exchange tube is arranged in the cylinder; an air outlet and a liquid inlet; and an oil return port. The oil concentration of the flooded evaporator of the prior art CN201921012469.1 is highest at the oil return port, which reduces the accumulation of lubricating oil in the flooded evaporator and improves the heat exchange performance; the position of the evaporator outlet is flexible, and the outlet does not have to be placed in the center, which is convenient for structural design; under the action of the baffle, the refrigerant maintains a certain flow rate and fully exchanges heat with the heat exchange tube to improve the heat exchange performance; it can provide an independent evaporator solution for a refrigeration system in the application of multiple compressors.

[0031] Based on the above, it can be known that the flooded evaporator of the prior art CN201921012469.1 allows the refrigerant liquid to enter the evaporator at a certain flow rate and flow under the action of the baffle, and finally collects the lubricating oil brought out by the compressor at the oil return port. To a certain extent, the heat exchange effect between the refrigerant and the refrigerant inside the evaporator is strengthened, and the heat exchange is enhanced. However, the amount of refrigerant required for the flooded evaporator is large and the heat transfer effect is average. Because the liquid pool has a certain height, the evaporating bubbles need to overcome a certain liquid pressure during the rising process.

[0032] The present invention analyzes the distributed falling film evaporator provided by the prior art CN201620976953.6 and finds that Figure 2As shown, the distributed falling film evaporator provided by the prior art CN201620976953.6 has a refrigerant distribution device provided in the horizontal direction inside, and the refrigerant distribution device includes N refrigerant spray pipes and a refrigerant distribution plate, the refrigerant spray pipes are passed through the upper part of the refrigerant distribution plate, and the refrigerant distribution plate is divided into N refrigerant spraying areas along the length direction of the distributed falling film evaporator; M refrigerant distribution plate partitions are also provided at the bottom of the refrigerant distribution plate, and the refrigerant distribution plate partitions divide the refrigerant distribution plate into (M+1) independent refrigerant liquid storage areas along the length direction of the distributed falling film evaporator, wherein M>N, and a refrigerant distribution plate partition is provided directly below each of the refrigerant spray pipes.

[0033] Based on the above, it can be known that although the distributed falling film evaporator provided by the prior art CN201620976953.6 can reduce the filling amount of refrigerant, the evaporation efficiency is improved, and the heat transfer effect is better, it is difficult to control the formation of a uniform liquid film.

[0034] Example 1

[0035] This embodiment provides a falling film evaporator.

[0036] See also Figure 3-Figure 5 The falling film evaporator of this embodiment includes an evaporator cylinder 1, a liquid inlet 2, a plurality of gas outlets 3, a liquid baffle 4, two liquid distribution plates 5, a liquid spray plate 6, a plurality of falling film tube bundles 7 and an oil outlet 8.

[0037] See also Figure 3 In this embodiment, the liquid inlet 2 is opened at the upper end of the evaporator cylinder 1, and a liquid baffle plate 4 is arranged below the liquid inlet 2, so that the refrigerant liquid falls on the liquid baffle plate 4 after entering the cylinder from the liquid inlet 2. Since the liquid baffle plate 4 is horizontally arranged below the liquid inlet, the horizontal laying area of ​​the falling refrigerant liquid can be increased, thereby realizing the diversion and deceleration of the refrigerant liquid, thereby preventing the refrigerant liquid from splashing.

[0038] See also Figure 3 In this embodiment, the two liquid distribution plates 5 are arranged below the liquid baffle plate 4 in sequence from top to bottom. After the refrigerant liquid is diverted and decelerated by the liquid baffle plate 4, it can enter the top liquid distribution plate more smoothly, so that the top liquid distribution plate 5 can not only completely receive the refrigerant liquid from the liquid baffle plate 4, but also the width of the top liquid distribution plate 5 is increased relative to the width of the liquid baffle plate 4, and the area is increased compared to the liquid baffle plate 4, which is beneficial to increase the laying area of ​​the refrigerant liquid on the horizontal plane, thereby improving the uniformity of the distribution of the refrigerant liquid.

[0039] In addition, a plurality of diversion tubes 51 are arranged in the top liquid distribution plate 5 of the present embodiment, and the plurality of diversion tubes 51 are arranged in parallel so that a plurality of the diversion tubes 51 are evenly immersed in the liquid of the liquid distribution plate 5. Then, as the amount of liquid gradually increases, it overflows from both sides and flows into the liquid distribution plate 5 below.

[0040] The width of the bottom liquid distribution plate 5 is also increased relative to the top liquid distribution plate 5, so that after the falling refrigerant liquid is processed by the bottom liquid distribution plate 5, the laying area of ​​the refrigerant liquid on the horizontal plane is further increased, thereby improving the distribution uniformity of the refrigerant liquid, so that the refrigerant liquid processed by the last liquid distribution plate can form a uniform liquid film on the surface of the falling film tube bundle below it, thereby greatly increasing the heat exchange contact area of ​​the refrigerant liquid through the formation of a uniform liquid film, thereby achieving the optimal heat exchange mode, and further reducing the refrigerant consumption while improving the heat exchange efficiency.

[0041] In this embodiment, a plurality of branch pipes 51 immersed in the refrigerant in each liquid distribution plate 5 continuously exchange heat with the refrigerant, thereby reducing the amount of refrigerant used.

[0042] See also Figure 3 In this embodiment, a liquid spray plate 6 is horizontally arranged below the last liquid distribution plate 5, and the width of the liquid spray plate 6 is greater than the width of the last liquid distribution plate 5. The center of the liquid spray plate 6 and the center of the last liquid distribution plate 5 are located on the same axis, so that the falling film evaporator of this embodiment can work normally under a certain tilt condition.

[0043] See also Figure 4 In this embodiment, the liquid spray plate 6 is evenly distributed with a plurality of liquid spray holes 61, so that a uniform liquid film is generated on the surface of the falling film tube bundle 7 below to achieve an optimal heat exchange mode, thereby improving the heat exchange efficiency and reducing the amount of refrigerant.

[0044] The size of the liquid spray hole 61 is flexibly designed according to the cooling capacity of the evaporator. The liquid spray hole 61 is not only used to spray the refrigerant, but also can play a role in gas-liquid separation, separating the refrigerant gas generated after the refrigerant liquid undergoes heat exchange, and the separated refrigerant gas is discharged through two gas outlets 3 located below the two sides of the liquid inlet 2.

[0045] See also Figure 3In this embodiment, a gas-liquid separation device 9 is provided at the bottom of the two gas outlets 3, so that the evaporated refrigerant gas is first separated into solid and liquid by the gas-liquid separation device 9 before being discharged from the gas outlet 3, so as to separate the refrigerant liquid entrained in the refrigerant gas, thereby preventing the discharged refrigerant gas from being sucked with liquid when entering the subsequent compressor. The excess refrigerant and lubricating oil mixture in the evaporator cylinder 1 is discharged through the oil outlet 8 provided at the bottom of the evaporator cylinder 1, so as to facilitate the subsequent recovery of the lubricating oil and re-input into the compressor, forming the oil circuit circulation part.

[0046] The falling film evaporator of this embodiment can reduce the amount of refrigerant filling, thereby saving costs. In addition, during use, the falling film evaporator of this embodiment is arranged in sequence from top to bottom through the liquid inlet 2, the liquid baffle 4, a plurality of liquid distribution plates 5, the liquid spray plate 6 and a plurality of falling film tube bundles 7, so that the refrigerant liquid entering through the liquid inlet continuously flows, thereby strengthening the heat transfer convection. At the same time, the refrigerant part in the liquid distribution plate 5 is continuously updated, thereby improving the heat transfer efficiency. The falling film evaporator of this embodiment is provided with a plurality of liquid distribution plates between the liquid inlet and the liquid spray plate, thereby reducing the liquid spray height, realizing the formation of a film of the refrigerant liquid on the outer surface of the tube bundle and maintaining a uniform film thickness, thereby reducing the risk of "dry evaporation".

[0047] In a preferred embodiment of the present invention, the two gas outlets 3 are arranged in mirror symmetry along the central axis of the liquid inlet 2 to improve the stability and efficiency of gas outlet.

[0048] Obviously, the above embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A falling film evaporator, characterized in that: include: An evaporator cylinder (1) has a cavity inside; A liquid inlet (2) is arranged on the evaporator cylinder (1) and is used for allowing refrigerant liquid to enter the evaporator cylinder (1); A plurality of gas outlets (3) are arranged at the upper end of the evaporator cylinder (1) and are used to discharge evaporated refrigerant gas; A liquid baffle (4) is horizontally arranged below the liquid inlet (2) and is used to divert the refrigerant liquid input through the liquid inlet (2); A plurality of liquid distribution plates (5) are horizontally arranged below the liquid baffle plate (4); The liquid spray plate (6) is horizontally arranged below the last liquid distribution plate (5); and the center of the liquid spray plate (6) and the center of the last liquid distribution plate (5) are located on the same axis; A plurality of falling film tube bundles (7) are horizontally arranged below the liquid spray plate (6); The oil outlet (8) is arranged at the bottom of the evaporator cylinder (1).

2. The falling film evaporator according to claim 1, characterized in that A plurality of flow distribution pipes (51) are arranged in each of the liquid distribution plates (5), and the plurality of flow distribution pipes (51) are arranged in parallel.

3. The falling film evaporator according to claim 1, characterized in that The centers of the plurality of liquid distribution plates (5) are all located on the same axis, and the width of each of the liquid distribution plates (5) is greater than the width of the previous adjacent liquid distribution plate (5).

4. The falling film evaporator according to claim 1, characterized in that: The width of the liquid spray plate (6) is greater than the width of the last liquid distribution plate (5).

5. The falling film evaporator according to claim 1, characterized in that: A plurality of liquid spray holes (61) are evenly distributed on the liquid spray plate (6).

6. The falling film evaporator according to claim 1, characterized in that: The falling film evaporator further comprises a plurality of gas-liquid separation devices (9), wherein the plurality of gas-liquid separation devices (9) are all arranged in the evaporator cylinder (1), and the plurality of gas-liquid separation devices (9) are respectively located at the bottom of the corresponding gas outlet (3).

7. The falling film evaporator according to claim 1, characterized in that: Two gas outlets (3) are provided, and the two gas outlets (3) are arranged in mirror symmetry along the central axis of the liquid inlet (2).

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