A vertical tube external falling film evaporator and evaporation method thereof

Abstract

The present invention relates to the technical field of heat exchangers, and discloses a vertical outer tube falling film evaporator and an evaporation method thereof, comprising: an outer shell; a heating steam inlet is provided on the top of the outer shell; a material inlet, a secondary steam outlet, a material outlet and a drain outlet are provided on the side wall of the outer shell; a non-condensing steam outlet is provided at the bottom of the outer shell; a downdraft pan and a falling film evaporation unit are provided in sequence inside the outer shell along the downward direction of the heating steam inlet; the falling film evaporation unit comprises a first tube sheet, a second tube sheet and at least one heat exchange tube. The present invention can set different numbers of downdraft pans according to the length of the heat exchange tube, and the flow guide on the downdraft pan can timely collect the liquid film outside the tube behind the downdraft pan for re-filming, so that the uniformity of the liquid film is not affected by the length of the heat exchange tube. In addition, due to the larger space in the shell side, the overflow of separation steam generated during the flow of the feed liquid has less impact on the liquid film outside the heat exchange tube than on the film formed inside the tube.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchangers, and in particular to a vertical outer tube falling film evaporator and an evaporation method thereof. Background Art

[0002] As a highly efficient evaporation device, the falling film evaporator, with its unique advantages, is widely used in the petrochemical, metallurgical, light industry, food processing, pharmaceutical, seawater desalination, and wastewater treatment industries. Currently, the predominant falling film evaporator is the in-tube falling film evaporator. Its operating principle is generally that the material is added through the upper tube box of the falling film evaporator's heating chamber. The material is then evenly distributed throughout the heat exchange tubes through a liquid distribution and film-forming device. Under the influence of gravity, vacuum induction, and airflow, the material forms a uniform film that flows downward. While the film-forming device forms a reasonable film within the upper portion of the heat exchange tube, the film's continuity and uniformity are poor in the lower portion, particularly in slender heat exchange tubes. Due to the limited internal space, the overflow of steam from the tube further affects the uniformity of the liquid film. Furthermore, installing a film-forming device within the heat exchange tube is very difficult. Therefore, developing an evaporator that can form a continuous and uniform liquid film while the material is flowing is crucial. Summary of the Invention

[0003] In view of the above-mentioned technical deficiencies, the technical problem to be solved by the present invention is to provide a vertical outer tube falling film evaporator and an evaporation method thereof, aiming to solve the problem of poor liquid film uniformity of the existing falling film evaporator.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solution: The present invention provides a vertical tube external falling film evaporator, comprising: an outer shell; a heating steam inlet is formed on the top of the outer shell;

[0005] The side wall of the outer shell is provided with a material inlet, a secondary steam outlet and a material outlet;

[0006] The bottom of the outer shell is provided with a non-condensable steam outlet;

[0007] The interior of the outer shell is provided with a downdraft pan and a falling film evaporation unit in sequence along the downward direction of the heating steam inlet;

[0008] The falling film evaporation unit includes a first tube sheet, a second tube sheet and at least one heat exchange tube.

[0009] Furthermore, the downcomers are evenly arranged along the longitudinal direction of the heat exchange tubes.

[0010] Furthermore, the downcomer includes a draft tube, a steam riser and a tray body;

[0011] The flow guide pipe is arranged outside the heat exchange pipe, and the steam riser is passed through the disc body. At the same time, the steam riser is spaced apart from the heat exchange pipe along the longitudinal direction of the disc body.

[0012] Furthermore, the guide pipe includes an upper liquid collecting cone pipe, an overflow port and a lower guide cone pipe.

[0013] Furthermore, the upper liquid collecting cone tube and the lower guide cone tube are symmetrical in vertical direction, and the overflow port is arranged between the upper liquid collecting cone tube and the lower guide cone tube.

[0014] Furthermore, the heat exchange tube passes through the first tube sheet and the second tube sheet.

[0015] Furthermore, at least two distance tubes are provided inside the outer shell;

[0016] Wherein, the distance tube is arranged longitudinally parallel to the heat exchange tube;

[0017] The distance tube is arranged between the first tube plate and the downcomer.

[0018] Furthermore, the distance pipe passes through the downcomer and is arranged on the first tube sheet.

[0019] Furthermore, the material inlet and the secondary steam outlet are arranged between the first tube sheet and the downcomer;

[0020] The material outlet and the drain port are arranged between the second tube plate and the downcomer.

[0021] An evaporation method for a vertical outer tube falling film evaporator, comprising:

[0022] The material liquid to be treated is added from the upper part of the shell side;

[0023] Under the action of gravity, the material liquid flows downward and flows through the multi-layer downcomer arranged inside the shell side;

[0024] A guide pipe is provided on each layer of the downcomer, and the material liquid is evenly distributed on the outer wall of each heat exchange tube through the guide pipe to form a continuous liquid film;

[0025] The distance between the downcomers is fixed by distance pipes to ensure that the material liquid can descend stably and evenly;

[0026] Heating steam is introduced into the heat exchange tube to heat the liquid film formed on the outer wall of the heat exchange tube to generate secondary steam;

[0027] As the heating process proceeds, the material liquid evaporates and concentrates while flowing downward along the outer wall of the heat exchange tube, and the concentrated material liquid is obtained at the bottom of the shell side.

[0028] The beneficial effects of the present invention are:

[0029] 1. The present invention can set different numbers of downcomers according to the length of the heat exchange tube. The guide on the downcomer can timely collect the liquid film outside the tube behind the downcomer for re-filming, so that the uniformity of the liquid film is not affected by the length of the heat exchange tube.

[0030] 2. In the present invention, since the space of the shell side is larger, the overflow of separation steam generated during the flow of the feed liquid has less impact on the liquid film outside the heat exchange tube than on the film formed inside the tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 A schematic structural diagram of a vertical tube falling film evaporator provided in an embodiment of the present invention.

[0033] Figure 2 Schematic diagram of the downcomer structure.

[0034] Figure 3 for Figure 2 Middle AA cross-section.

[0035] Figure 4 Schematic diagram of the guide tube structure;

[0036] Explanation of the reference numerals: 1. outer shell; 2. heating steam inlet; 3. tube box; 4. first tube sheet; 5. second tube sheet; 6. material inlet; 7. secondary steam outlet; 8. heat exchange tube; 9. downcomer; 10. distance tube; 91. guide tube; 92. steam riser; 93. tray; 912. upper liquid collecting cone; 913 overflow port; 914. lower guide cone; 11. material outlet; 12. drain port; 13. non-condensable steam outlet; 14. condensate outlet. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] Example 1

[0039] like Figures 1 to 4As shown, this embodiment provides a vertical tube external falling film evaporator, including an outer shell 1; Figure 1 As shown, a heating steam inlet 2 is provided on the top of the outer shell 1; a pipe box 3 is provided below the heating steam inlet 2; a material inlet 6, a secondary steam outlet 7, a material outlet 11 and a drain port 12 are provided on the side wall of the outer shell 1; a non-condensable steam port 13 and a condensed water outlet 14 are provided at the bottom of the outer shell 1; a downcomer 9 and a falling film evaporation unit are sequentially provided inside the outer shell 1 along the downward direction of the heating steam inlet 2; the falling film evaporation unit includes a first tube sheet 4, a second tube sheet 5 and at least one heat exchange tube 8; the downcomer 9 is evenly arranged along the longitudinal direction of the heat exchange tube 8.

[0040] Specifically, such as Figure 2 As shown, the downcomer 9 includes a guide pipe 91, a steam riser 92 and a plate body 93; Figure 3 As shown, the guide pipe 91 is arranged outside the heat exchange tube 8, and the steam riser 92 is passed through the disc 93. At the same time, the steam riser 92 is spaced apart from the heat exchange tube 8 along the longitudinal direction of the disc 93; Figure 4 As shown, the guide pipe 91 includes an upper liquid collecting cone 912, an overflow port 913 and a lower guide cone 914; the upper liquid collecting cone 912 and the lower guide cone 914 are symmetrical in the upper and lower directions, and the overflow port 913 is arranged between the upper liquid collecting cone 912 and the lower guide cone 914; the heat exchange tube 8 passes through the first tube sheet 4 and the second tube sheet 5; at least two distance tubes 10 are also arranged inside the outer shell 1; wherein the distance tube 10 is arranged longitudinally parallel to the heat exchange tube 8; the distance tube 10 is arranged between the first tube sheet 4 and the downcomer 9; the distance tube 10 passes through the downcomer 9 and is arranged on the first tube sheet 4; the material inlet 6 and the secondary steam outlet 7 are arranged between the first tube sheet 4 and the downcomer 9; the material outlet 11 and the drain port 12 are arranged between the second tube sheet 5 and the downcomer 9.

[0041] Example 2

[0042] Based on Example 1, this embodiment further provides an evaporation method of a vertical external tube falling film evaporator, comprising:

[0043] The material liquid to be treated is added from the material inlet 6;

[0044] Under the action of gravity, the material liquid flows downward and flows through the multi-layer downcomer 9 arranged inside the shell side;

[0045] Each downcomer 9 is provided with a guide pipe 91, through which the material liquid is evenly distributed on the outer wall of each heat exchange tube 8, forming a continuous liquid film;

[0046] The distance between the downcomers 9 is fixed by the distance pipes 10 to ensure that the material liquid can descend stably and evenly;

[0047] Heating steam is introduced into the heat exchange tube 8 to heat the liquid film formed on the outer wall of the heat exchange tube 8 to generate secondary steam which is discharged through the secondary steam outlet 7;

[0048] As the heating process proceeds, the material liquid evaporates and concentrates while flowing downward along the outer wall of the heat exchange tube 8 , and the concentrated material liquid is obtained at the bottom of the shell side and discharged through the material outlet 11 .

[0049] When the equipment is cleaned or maintained, the residual material or cleaning liquid in the shell side is discharged through the drain port 12 set on the side wall of the outer shell; the non-condensable gas in the system is discharged through the non-condensable steam port 13 set at the bottom of the outer shell; the water formed by the condensation of the heating steam is discharged through the condensate outlet 14 set at the bottom of the outer shell.

[0050] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A vertical tube falling film evaporator, characterized in that: include: outer shell; A heating steam inlet is provided on the top of the outer shell; The side wall of the outer shell is provided with a material inlet, a secondary steam outlet and a material outlet; The bottom of the outer shell is provided with a non-condensable steam outlet; The interior of the outer shell is provided with a downdraft pan and a falling film evaporation unit in sequence along the downward direction of the heating steam inlet; The falling film evaporation unit comprises a first tube sheet, a second tube sheet and at least one heat exchange tube; The downcomers are evenly arranged along the longitudinal direction of the heat exchange tubes; The downcomer includes a draft pipe, a steam riser and a downcomer body; The guide pipe is arranged outside the heat exchange tube, and the steam riser is arranged on the disk body. At the same time, the steam riser is arranged at intervals from the heat exchange tube along the longitudinal direction of the disk body. The guide pipe includes an upper liquid collecting cone pipe, an overflow port and a lower guide cone pipe; The upper liquid collecting cone tube and the lower flow guiding cone tube are symmetrical in vertical direction, and the overflow port is arranged between the upper liquid collecting cone tube and the lower flow guiding cone tube; The heat exchange tubes pass through the first tube sheet and the second tube sheet; At least two distance tubes are also provided inside the outer shell; Wherein, the distance tube is arranged longitudinally parallel to the heat exchange tube; The distance tube is arranged between the first tube sheet and the downcomer; The distance pipe passes through the downcomer and is arranged on the first tube plate.

2. A vertical tube falling film evaporator according to claim 1, characterized in that: The material inlet and the secondary steam outlet are arranged between the first tube sheet and the downcomer; The material outlet and the drain port are arranged between the second tube plate and the downcomer.

3. The evaporation method based on the vertical outer tube falling film evaporator according to claim 1 is characterized in that: include: Add the material liquid to be treated from the material inlet; Under the action of gravity, the material liquid flows downward and flows through the multi-layer downcomer arranged inside the outer shell; A guide pipe is provided on each layer of the downcomer, and the material liquid is evenly distributed on the outer wall of each heat exchange tube through the guide pipe to form a continuous liquid film; The distance between the downcomers is fixed by distance pipes to ensure that the material liquid can descend stably and evenly; Heating steam is introduced into the heat exchange tube through the heating steam inlet, heating the liquid film formed on the outer wall of the heat exchange tube to generate secondary steam which is then discharged through the secondary steam outlet provided on the side wall of the outer shell; As the heating process proceeds, the material liquid evaporates and concentrates while flowing downward along the outer wall of the heat exchange tube, and the concentrated material liquid is obtained at the bottom of the shell side and discharged through the material outlet.

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