Falling film evaporator

Abstract

The utility model discloses a falling film evaporator which comprises a shell and an evaporation unit located in the shell, and the evaporation unit comprises a film distributor and a heat exchange tube located below the film distributor. According to the heat exchange tube, the protruding parts are arranged on the heat exchange tube, on one hand, the protruding parts can present a siphon effect when a liquid film is distributed, liquid is rapidly distributed on the surface of the heat exchange tube, and dry burning caused by uneven film distribution of the heat exchange tube is prevented; on the other hand, the heat exchange area is increased through the arrangement of the protruding parts, and the evaporation efficiency is improved.

Description

Technical Field

[0001] The utility model relates to the technical field of evaporators, in particular to a falling film evaporator. Background Art

[0002] The horizontal tube falling film evaporator is an evaporation equipment used in the chemical, environmental protection, pharmaceutical, water treatment and other industries. It is divided into two types: single-effect and multi-effect. The principle of falling film evaporation is to add the feed liquid from the upper tube box of the falling film evaporator heating chamber, and evenly distribute it to each heat exchange tube through the liquid distribution and film forming device. Under the action of gravity, vacuum induction and airflow, it flows from top to bottom in a uniform film. The spray density, spray structure and heat exchange tube array layout of the liquid distributor are the main factors affecting the uniform distribution of the liquid. If the film is unevenly distributed, it will cause dry burning. In addition, the heat exchange tubes of the horizontal tube falling film evaporator are usually smooth heat exchange tubes made of stainless steel. Smooth heat exchange tubes are not conducive to heat exchange, resulting in low heat utilization and poor evaporation effect.

[0003] Therefore, it is necessary to provide a new film evaporator to solve the defects of uneven film distribution and low heat exchange efficiency that affect the evaporation effect by improving the structure of the heat exchange tube. Utility Model Content

[0004] The utility model provides a falling film evaporator, which solves the defects of uneven film distribution and low heat exchange efficiency, which affect the evaporation effect, by improving the structure of the heat exchange tube.

[0005] To achieve the above purpose, the scheme of the utility model is as follows:

[0006] The falling film evaporator comprises a shell and an evaporation unit arranged inside the shell; the evaporation unit comprises a film distributor and a heat exchange tube arranged transversely below the film distributor; the heat exchange tube is provided with a protrusion.

[0007] Furthermore, the area where the protrusion is arranged at least covers the upper half of the heat exchange tube.

[0008] Furthermore, the raised portion is annular and concentric with the heat exchange tube.

[0009] Preferably, the interior of the protrusion is hollow and communicates with the heat exchange tube, and the cross-section of the protrusion is approximately rectangular or wavy.

[0010] Furthermore, there are multiple evaporation units, which are arranged in sequence along the axial direction of the shell; the evaporation space of the evaporation unit located on the left is connected to the heat exchange tube located on the right.

[0011] Preferably, the shell is provided with a steam pipe connected to the leftmost heat exchange tube.

[0012] More preferably, there are three evaporation units; a vertical partition is provided at the bottom of the shell between adjacent evaporation units; a material output pipe is provided on the left side of the partition, and an exhaust steam return pipe is provided on the right side.

[0013] Compared with the prior art, the utility model has the following beneficial effects:

[0014] The falling film evaporator provided by the utility model has a protrusion arranged on the heat exchange tube. On the one hand, the protrusion can present a siphon effect when the liquid film is distributed, so that the liquid quickly covers the surface of the heat exchange tube, thereby preventing the heat exchange tube from drying out due to uneven film distribution. On the other hand, the provision of the protrusion increases the heat exchange area and improves the evaporation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is an overall schematic diagram of the falling film evaporator described in the utility model.

[0016] Figure 2 This is a partial enlarged view of the axial cross section of a heat exchange tube.

[0017] Figure 3 This is a partial enlarged view of the axial cross section of another type of heat exchange tube.

[0018] Wherein: 1. Shell; 2. Evaporation unit; 11. Steam inlet pipe; 12. Steam return pipe; 13, 14. Discharge pipes; 15. Exhaust steam return pipe; 21. Film distributor; 22. Heat exchange tube; 221. Protrusion. DETAILED DESCRIPTION

[0019] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0020] It should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside", "left", "right", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0021] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "install", "connect", "connect", "fix", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two components or the interaction relationship between two components. For ordinary technicians in this field, the specific meanings of the above terms in this utility model can be determined according to specific circumstances.

[0022] In one embodiment, Figure 1-3 As shown, a falling film evaporator is proposed, including a shell 1 and an evaporation unit 2 arranged inside the shell; the evaporation unit 2 includes a film distributor 21 and a heat exchange tube 22 arranged laterally below the film distributor 21; the heat exchange surface of the heat exchange tube 22 is provided with a protrusion 221.

[0023] The falling film evaporator is provided with a protrusion 221 on the heat exchange tube. On the one hand, since the protrusion 221 protrudes from the smooth surface of the heat exchange tube 22, it can present a siphon effect when the liquid film is distributed, and the liquid is quickly spread all over the surface of the heat exchange tube 22, thereby preventing the heat exchange tube 22 from being dry-burned due to uneven film distribution; on the other hand, the provision of the protrusion 221 increases the heat exchange area and improves the evaporation efficiency.

[0024] In a preferred embodiment, the protrusion 221 covers at least the upper half of the heat exchange tube 22 in the setting area of ​​the heat exchange tube 2. The film spreading liquid of the film spreading device 21 located above can pass through the protrusion 221 and quickly spread over the surface of the heat exchange tube 22, thereby improving the film spreading effect. The setting mode of the protrusion 221 includes but is not limited to the dot matrix type, continuous type, ring type, etc. The protrusion 221 is preferably a hollow structure connected to the inside of the heat exchange tube 22.

[0025] In a preferred embodiment, Figure 2-3 As shown, the protrusion 221 is an annular protrusion, which is concentrically arranged with the heat exchange tube 22, and adjacent protrusions 221 are arranged at a certain distance, so that the heat exchange tube 22 forms a corrugated tube structure. Figure 2 The heat exchange tube 22 shown is an axial cross-sectional view of a corrugated tube structure, in which the waist of the annular protrusion maintains a constant width, forming a cross-section that is approximately rectangular; the protrusion 221 of this shape has a stronger siphon effect and a better film-forming effect. Figure 3 The heat exchange tube 22 shown in the figure is another axial cross-sectional view of a corrugated tube structure. The annular protrusion shrinks from the bottom to the top to form a cross-section that is approximately wavy. The heat exchange tube 22 having the shape of the protrusion 221 is easy to manufacture and has a low cost.

[0026] In a preferred embodiment, Figure 1As shown, there are three evaporation units 2, which are arranged in sequence from left to right along the axial direction of the shell 1 to form a three-effect evaporation system. The evaporation unit 2 is arranged in the shell 1 to form the evaporation space of the shell side. The left shell side is connected to the heat exchange tube 22 located on the right side, so that the exhaust steam formed by the evaporation of the left liquid enters the right heat exchange tube 22 for further heating and evaporation. A steam inlet pipe 11 is provided at the upper left side of the shell 1, and a steam recovery pipe 12 is provided at the corresponding position below. Specifically, after the external steam enters the shell 1 from the top, it enters the right heat exchange tube 22 for heat exchange. After the steam is cooled, it forms return water and is discharged from the steam inlet pipe 11.

[0027] In a more preferred embodiment, for each evaporation unit 2, a material output pipe 14 is provided below the heat exchange tube 22, and the material enters from the upper film distributor 21 and evaporates through the heat exchange tube 22 and is discharged from the bottom material output pipe 14. In addition, a vertical partition 13 is provided between two adjacent evaporation units 2; the material output pipe 14 is located on the left side of the partition 13, and an exhaust steam return pipe 15 is provided on the right side. The function of the partition 13 is to separate the material and the exhaust steam condensation return water at the bottom.

[0028] In the above embodiment, by providing the protrusion 221 on the heat exchange tube 22, the dual functions of film spreading and improving the heat exchange efficiency are achieved; by providing a plurality of evaporation units 2, the leftmost evaporation unit uses external steam, and the two evaporation units on the right use the exhaust steam generated on the left side for heating and evaporation respectively, and by adjusting the upper liquid feed amount, three-effect evaporation is achieved, thereby improving the energy utilization rate and evaporation effect, and having broad industrial promotion value.

[0029] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A falling film evaporator, comprising a shell (1) and an evaporation unit (2) arranged inside the shell; characterized in that: The evaporation unit (2) comprises a film distributor (21) and a heat exchange tube (22) arranged transversely below the film distributor (21); the heat exchange tube (22) is provided with a protrusion (221).

2. The falling film evaporator according to claim 1, characterized in that The area where the protrusion (221) is arranged at least covers the upper half of the heat exchange tube (22).

3. The falling film evaporator according to claim 1, characterized in that The raised portion (221) is annular and is arranged concentrically with the heat exchange tube (22).

4. The falling film evaporator according to claim 3, characterized in that: The interior of the raised portion (221) is hollow and communicates with the heat exchange tube (22); the cross section of the raised portion (221) is approximately rectangular or wavy.

5. The falling film evaporator according to claim 1, characterized in that There are multiple evaporation units (2), which are arranged in sequence along the axial direction of the shell (1); the evaporation space of the evaporation unit (2) located on the left side is connected to the heat exchange tube (22) located on the right side.

6. The falling film evaporator according to claim 5, characterized in that The shell (1) is provided with a steam pipe connected to the leftmost heat exchange tube (22).

7. The falling film evaporator according to claim 5 or 6, characterized in that: There are three evaporation units (2); a vertically arranged partition (13) is provided between adjacent evaporation units (2) at the bottom of the shell (1); a material output pipe (14) is provided on the left side of the partition (13), and an exhaust steam return pipe (15) is provided on the right side.

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