A falling film reboiler

Abstract

The utility model provides a falling film reboiler relates to rectification equipment technical field, including the casing, the casing is installed with feed pipe, primary distribution disc, secondary distribution disc, heat exchange tube plate, partition tube plate and a plurality of falling film tube, falling film tube top is installed with falls into the film tube spare, film forming tube spare includes film forming tube, film forming support and negative pressure gas cover, film forming tube with the inner wall between falling film tube is provided with film forming gap, film forming support extends to the upper edge of film forming tube, negative pressure gas cover is established fixedly in film forming support top, the upper side of support fixed is provided with the flow baffle, negative pressure gas cover and flow baffle form the negative pressure channel of lower opening between. In the utility model, through negative pressure channel, the upper side of liquid level forms continuous negative pressure suction, accelerates the breakage of air bubble, avoids the air bubble to enter falling film tube and causes liquid film to break.

Description

Technical Field

[0001] This utility model relates to the field of distillation equipment technology, specifically a falling film reboiler. Background Technology

[0002] In distillation processes, falling film evaporators are typically used as reboilers. Their core function is to pump the bottom liquid material to the top of the reboiler, where it forms a uniform liquid film on the heating tube wall via a serrated distributor. Under gravity, the liquid film flows downward along the heating surface of the vertical heat exchange tubes. The heat from the heating medium is conducted to the liquid film through the heat exchange tube wall, enabling rapid evaporation of the liquid material. This provides the distillation column with high-purity, low-superheat rising steam while preventing the decomposition of heat-sensitive materials.

[0003] In the existing technology, the liquid material pumped to the top of the reboiler enters the distribution plate from the inlet pipe and falls onto the falling film assembly by a cascading method. The cascading liquid material impacts the lower liquid material to generate a foam layer. The foam layer enters the heat exchange tube along with the liquid material in the falling film assembly, adheres to the surface of the heat exchange tube, causes liquid film rupture, and results in scaling on the dry wall of the heat exchange tube. At the same time, the foam layer reduces heat exchange efficiency and causes a loss of effective heat transfer area. Utility Model Content

[0004] (a) Technical problems to be solved

[0005] To address the shortcomings of existing technologies, this invention provides a falling film reboiler that solves the problems mentioned in the background section.

[0006] (II) Technical Solution

[0007] To achieve the above objectives, this utility model provides the following technical solution:

[0008] A falling film reboiler includes a shell, within which a feed pipe, a primary distribution plate, a secondary distribution plate, a heat exchange tube sheet, a separator tube sheet, and a plurality of falling film tubes are installed. A separation chamber is formed between the lower side of the shell and the separator tube sheet. An exhaust port is connected to the side wall of the separation chamber. The feed pipe is disposed inside the shell. The primary and secondary distribution plates are fixed directly below the feed pipe. A plurality of falling film holes are formed on the heat exchange tube sheet. The falling film tubes are welded and fixed into the falling film holes. A falling film forming fitting is installed on the top of each falling film tube. The device includes a film-forming tube, a film-forming support, and a negative pressure hood. The film-forming support is fixed to a heat exchange tube sheet. The film-forming tube is concentrically inserted into the top of a falling film tube. A film-forming gap is provided between the film-forming tube and the inner wall of the falling film tube. The film-forming tube is fixed in the middle of the film-forming support. The middle of the film-forming support extends upward from the film-forming tube to a point higher than the upper edge of the film-forming tube. The negative pressure hood is fixed to the top of the film-forming support. A flow guide baffle is provided on the upper side of the support. A negative pressure channel with an opening at the bottom is formed between the negative pressure hood and the flow guide baffle. The negative pressure channel is connected to the falling film tube.

[0009] Preferably, the lower end of the film-forming tube is outwardly expanding, and its outer diameter is smaller than the inner diameter of the falling film tube.

[0010] Preferably, the bottom of the film-forming support is provided with a weir ring, which is welded and fixed to the upper side of the heat exchange tube sheet, and the weir ring is concentrically covered on the outside of the falling film hole.

[0011] Preferably, the middle part of the film-forming support has a bubble-blocking sleeve extending downward, the lower edge of the bubble-blocking sleeve extending to the lower side of the upper edge of the weir ring, and the upper side of the bubble-blocking sleeve has a plurality of pressure relief holes.

[0012] Preferably, the outer edge of the negative pressure hood is provided with a plurality of overflow holes, the height of which is higher than the upper edge of the film-forming tube.

[0013] Preferably, a floating ring is slidably fitted on the outer wall of the negative pressure hood, the upper side of the floating ring is blocked outside the overflow hole, the lower side of the floating ring has a connecting hole corresponding to the overflow hole, a number of floating blocks are fixed on the outer edge of the floating ring, and a return spring is connected between the upper side of the floating ring and the negative pressure hood.

[0014] (III) Beneficial Effects

[0015] This invention provides a falling film reboiler. It has the following beneficial effects:

[0016] 1. In this utility model, liquid material is poured onto the heat exchange tube plate through the feed pipe, primary distribution plate, and secondary distribution plate. A continuous liquid film is formed in the film-forming gap between the inner wall of the film-forming tube and the falling film tube. The liquid film falls along the falling film tube and exchanges heat with it to generate steam, which then flows downward into the separation chamber for separation and extraction.

[0017] 2. In this utility model, under the action of the negative pressure pump, the pressure at the bottom of the falling film tube will be lower than the pressure at the top, that is, a continuous micro negative pressure suction can be formed on the lower side of the negative pressure hood, forming a pressure gradient at the top of the shell. The negative pressure suction on the lower side of the negative pressure channel acts on the liquid surface of the liquid phase material at the outer edge of the falling film tube. Through negative pressure suction, the bubbles in the liquid phase material float to the surface and burst, preventing the bubbles from entering the heat exchange tube with the liquid phase material in the falling film assembly, adhering to the surface of the heat exchange tube, causing liquid film rupture, and causing scale buildup on the dry wall of the heat exchange tube. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of a falling film reboiler according to the present invention;

[0019] Figure 2 for Figure 1 Enlarged view of a portion of point A in the middle;

[0020] Figure 3 This is a schematic diagram of the film-forming tube in this utility model.

[0021] In the diagram: 1. Shell; 2. Inlet; 3. Heat exchanger tube sheet; 4. Falling film tube; 5. Primary distribution plate; 6. Secondary distribution plate; 7. Film-forming tube; 8. Film-forming support; 9. Negative pressure hood; 10. Weir ring; 11. Bubble-blocking sleeve; 12. Pressure relief hole; 13. Flow guide baffle; 14. Overflow hole; 15. Floating ring; 16. Return spring; 17. Connecting hole; 18. Floating block. Detailed Implementation

[0022] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0023] This utility model embodiment provides a falling film reboiler, such as Figure 1As shown, the system includes a shell 1, with a feed inlet 2 connected to the top of the shell 1. A heat exchange tube sheet 3 and a partition tube sheet are fixedly spaced in the middle of the shell 1. A film-forming chamber is formed between the heat exchange tube sheet 3 and the top of the shell 1. A separation chamber is formed between the lower side of the shell 1 and the partition tube sheet. A heat exchange cavity is formed between the heat exchange tube sheet 3 and the partition tube sheet. Several corresponding falling film holes are formed on the heat exchange tube sheet 3 and the partition tube sheet. Falling film tubes 4 are welded and fixed within the falling film holes. The upper and lower ends of the falling film tubes 4 are connected to the film-forming chamber and the separation chamber, respectively. A secondary distribution plate 6 is concentrically fixed on the heat exchange tube sheet 3. The secondary distribution plate 6 has several distribution holes, which correspond to the falling film holes. A primary distribution plate 5 is fixed on the upper side of the secondary distribution plate 6. The primary distribution plate 5 is located directly below the feed pipe. The side wall of the heat exchange chamber is connected to a heat source inlet and a heat source outlet for connecting to an external heat source and exchanging heat with the falling film tube 4. The side wall of the separation chamber is provided with a liquid outlet and an exhaust outlet. A negative pressure pump is connected to the exhaust outlet. The negative pressure pump can provide negative pressure to the shell 1, so that the pressure at the lower end of the falling film tube 4 is lower than the pressure at the upper end, which can ensure that the steam generated in the falling film tube 4 can flow smoothly downward and enter the separation chamber.

[0024] like Figure 2-3 As shown, a falling film forming fitting is installed on the top of the falling film tube 4. The falling film forming fitting includes a falling film forming tube 7, a falling film forming support 8, and a negative pressure air hood 9.

[0025] A weir ring 10 is provided on the lower side of the film-forming support 8. The weir ring 10 is welded and fixed to the upper side of the heat exchange tube sheet 3. The weir ring 10 is concentrically covered on the outside of the falling film hole, which can maintain a certain liquid level of the liquid material on the upper side of the heat exchange tube sheet 3, so that the bubbles generated by the leaching can be separated from the liquid material. A bubble-blocking sleeve 11 extends downward from the middle of the film-forming support 8. The lower edge of the bubble-blocking sleeve 11 extends to the lower side of the upper edge of the weir ring 10. Several pressure relief holes 12 are opened on the upper side of the bubble-blocking sleeve 11. The bubble-blocking sleeve 11 can extend below the liquid surface of the liquid material, which can block the bubbles that are separated from the liquid material and prevent the bubbles from entering the falling film tube 4. The bottom liquid material can enter the falling film tube 4 through the gap between the lower end of the bubble-blocking sleeve 11 and the weir ring 10 to form a film and fall down.

[0026] The film-forming tube 7 is fixed in the middle of the film-forming support 8. The film-forming tube 7 is concentrically inserted into the top of the falling film tube 4. The lower end of the film-forming tube 7 is outwardly expanding and its outer diameter is smaller than the inner diameter of the falling film tube 4. A film-forming gap is provided between the film-forming tube 7 and the inner wall of the falling film tube 4. The liquid phase material separated from the bubbles enters the film-forming gap and forms a continuous liquid film on the inner wall of the falling film tube 4 along the lower end of the film-forming tube 7 to exchange heat with the falling film tube 4, forming steam. Under the action of negative pressure, the steam is drawn into the separation chamber.

[0027] The middle part of the film-forming support 8 extends upward from the film-forming tube 7 to a height above the upper edge of the film-forming tube 7. The negative pressure hood 9 is fixed on the top of the film-forming support 8. A flow guide baffle 13 is provided on the upper side of the support 8. A negative pressure channel with an opening at the bottom is formed between the negative pressure hood 9 and the flow guide baffle 13. The negative pressure channel is connected to the falling film tube 4. The negative pressure generated by the negative pressure pump will form a continuous negative pressure in the negative pressure channel. Due to the distribution of negative pressure, there is a pressure gradient, which makes the negative pressure suction force near the negative pressure channel the maximum. The negative pressure suction force acts on the outer side of the bubble blocking sleeve 11 above the bubble, which can make the bubbles in the liquid phase material float up quickly and make the bubbles easier to break, so as to achieve the purpose of defoaming, avoid bubble accumulation, and effectively prevent bubbles from entering the falling film tube 4.

[0028] Further settings, such as Figure 3 As shown, the outer edge of the negative pressure hood 9 is provided with a concave annular groove. Several overflow holes 14 are arranged circumferentially around the middle of the inner wall of the concave annular groove. The height of the overflow holes 14 is higher than the upper edge of the film-forming tube 7. Several vertical strips are arranged on the inner wall of the concave annular groove. A floating ring 15 is slidably fitted inside the concave annular groove. A vertical groove is provided on the inner upper part of the floating ring 15 to slide and cooperate with the vertical strips. A return spring 16 is connected between the upper sidewall of the concave annular groove and the upper side of the floating ring 15. The upper side of the ring 15 is blocked outside the overflow hole 14. The lower side of the floating ring 15 is provided with a connecting hole 17 corresponding to the overflow hole 14. Several floating blocks 18 are fixed on the outer edge of the floating ring 15. The above technical solution can be set so that when the film-forming gap is blocked, as the liquid level of the liquid phase material gradually rises, the floating ring 15 rises under the action of buoyancy, and the connecting hole 17 connects with the overflow hole 14. The liquid phase material can enter the top of the self-forming tube 7 and fall, avoiding damage caused by dry burning of the heat exchange tube.

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

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