CN215962177U - Shell-and-tube falling film evaporator and film distributor - Google Patents

Abstract

The utility model discloses a shell-and-tube falling-film evaporator and a film distributor, and relates to the technical field of falling-film evaporators. The film distributor comprises a pipe body, a central column and an intercepting blade; the pipe body is of a reducing pipe structure, and axial spacing seams are uniformly distributed on the side wall of the lower middle part of the pipe body; the central column is fixed at the axial center in the pipe body, and a cut-off blade group is fixed on the side wall of the central column positioned below the pipe body; the intercepting blade group comprises an upper fan blade, a middle fan blade and a lower fan blade, the upper fan blade, the middle fan blade and the lower fan blade are respectively fixed on the three directions of the side wall of the central column according to the upper height position, the middle height position and the lower height position, the three fan blades are spliced into a whole circular structure, and the fan blades extend downwards from the fixed end. The film distributor for repeatedly distributing the alkali liquor is arranged in the falling film pipe, and the alkali liquor falling into the central area of the falling film pipe is collected and intercepted, so that the alkali liquor flows to the inner wall of the falling film pipe for film forming again, the heat transfer efficiency of equipment is improved, the steam consumption in the evaporation process is effectively reduced, and the service life of the falling film evaporator is prolonged.

Description

Shell-and-tube falling film evaporator and film distributor

Technical Field

The utility model relates to the technical field of falling film evaporators, in particular to a shell-and-tube falling film evaporator and a film distributor.

Background

Most manufacturers in the field of potassium hydroxide alkali liquid evaporation and solid alkali at present adopt a falling film evaporation process form, and the core equipment of the falling film evaporation process form is a falling film evaporator in a device. The core function of the falling-film evaporator is to heat the alkali liquor under a certain pressure to achieve a boiling state, and then to carry out vapor-liquid separation so as to realize the purpose of potassium hydroxide alkali liquor concentration. The film forming effect of the falling-film evaporator in operation directly determines the steam consumption of the evaporation unit and the service life of the evaporator. The film forming effect of the alkali liquor in the falling film pipe is good, the heat transfer efficiency is high, meanwhile, the temperature of the alkali liquor is uniformly distributed in the falling film pipe in the falling process, the concentration of the alkali liquor is gradually increased, and the good film forming effect can enable the falling film evaporator to achieve the best operation effect. If the film forming effect of the alkali liquor in the falling film tube is poor, the overall heat transfer efficiency in the falling film evaporation process is low. Even part of the alkali liquor does not participate in film formation and directly passes through the heat exchange tube of the evaporator, so that the film-forming alkali liquor can be mixed with the part of the alkali liquor to ensure that the concentration of the alkali discharged from the evaporator is qualified. The higher alkali concentration increases the temperature of the film-forming alkali liquor in the falling film tube, increases the corrosion of the falling film tube and shortens the service life of the evaporator.

The film forming effect of the alkali liquor in the falling film pipe mainly depends on the film distributor above the falling film pipe, the current film distributor is of a single pipe body structure, the pressure fluctuation at the overflow port is large, part of the alkali liquor at the contact part of the film distributor and the falling film pipe directly falls into the central area of the falling film pipe, the part of the alkali liquor directly falls into the lower liquid collecting box, the concentration is lower, the concentration of the film forming alkali liquor needs to be increased for the product quality to reach the standard, the concentration of the film forming alkali liquor needs to be increased by using larger steam for heating, the steam consumption in the production process is increased, and the service life of equipment is also shortened.

SUMMERY OF THE UTILITY MODEL

In order to solve the technical problems, the utility model provides a film distributor of a falling film evaporator, which collects and intercepts part of alkali liquor which falls into the central area of a falling film pipe and cannot form a film, so that the alkali liquor flows to the inner wall of the falling film pipe to form the film again, the heat transfer efficiency of equipment is improved, and the steam unit consumption is reduced.

In order to realize the technical purpose, the film distributor adopts the following scheme: the film distributor of the falling film evaporator comprises a pipe body, a central column and intercepting blades; the pipe body is of a reducing pipe structure, the diameter of the lower section of the pipe body is smaller than that of the upper section of the pipe body, a concave notch is formed in the side wall of the upper port of the pipe body, and axial spacing seams are uniformly distributed in the side wall of the lower section of the pipe body; the central column is fixed at the axial center in the pipe body, and a cut-off blade group is fixed on the side wall of the central column positioned below the pipe body; the intercepting blade group comprises an upper blade, a middle blade and a lower blade, the upper blade, the middle blade and the lower blade are respectively fixed on the side wall of the central column in three directions according to the upper height position, the middle height position and the lower height position, the three blades are spliced into a whole circular structure, and the blades are downwards inclined and extended from the fixed end.

Compared with the prior art, the film distributor has the beneficial effects that: the central column with the fan blades is added in the center of the tube body, and the alkali liquor falling into the central area of the membrane distributor is subjected to membrane distribution for multiple times, so that the membrane forming effect is improved, and the steam unit consumption is effectively reduced; and a plurality of annular and uniformly distributed spacing gaps are arranged at the lower section of the pipe body, so that the alkali liquor flows down to the inner wall of the falling film pipe along the spacing gaps, and the film forming effect is improved.

In order to realize the technical purpose, the falling film evaporator adopts the following scheme: a shell-and-tube falling-film evaporator comprises a falling-film tube and the film distributor, wherein the film distributor is inserted in the falling-film tube, and a secondary film forming channel for alkali liquor to flow through is reserved between the outer edge of a fan blade of an interception blade group and the inner wall of the falling-film tube.

Compared with the prior art, the falling film evaporator has the beneficial effects that: the film distributor for repeatedly distributing the alkali liquor is arranged in the falling film pipe, and the alkali liquor falling into the central area of the falling film pipe is collected and intercepted, so that the alkali liquor flows to the inner wall of the falling film pipe for film forming again, the heat transfer efficiency of equipment is improved, the steam consumption in the evaporation process is effectively reduced, and the service life of the falling film evaporator is prolonged.

The preferred scheme of the falling film evaporator is as follows:

the membrane falling tube comprises a tube body, and is characterized by further comprising an upper tube plate, a lower tube plate and the tube body, wherein the upper tube plate and the lower tube plate are respectively fixed on the upper portion and the lower portion in the tube body, the upper tube plate and the lower tube plate are respectively provided with a plurality of round holes, and the upper end and the lower end of each membrane falling tube respectively penetrate through the round holes of the upper tube plate and the lower tube plate and are fixed in the tube body.

An alkali liquor inlet pipe is arranged on the side wall of the barrel body positioned at the upper part of the upper tube plate, a gas discharge valve and a steam inlet pipe are arranged on the side wall of the middle upper part of the barrel body, and a baffle plate is arranged at an outlet of the steam inlet pipe positioned in the barrel body and used for changing the flow direction of steam, homogenizing the steam temperature and prolonging the service life of equipment; and a condensate outlet pipe is arranged on the side wall of the cylinder body positioned at the upper part of the lower tube plate and is used for discharging condensed high-temperature liquid.

The barrel inner wall of alkali lye import pipe top is fixed with cylindric alkali lye distribution ring, and the alkali lye level gets into the jar internal, collides the alkali lye distribution ring, changes the flow direction, and it is downflow along the section of thick bamboo wall of alkali lye distribution ring, has reduced the undulant range of alkali lye, is favorable to the better membrane forming of alkali lye.

The device also comprises an upper sealing head and a lower sealing head, wherein the upper sealing head and the lower sealing head are respectively connected with the upper port and the lower port of the cylinder body through flanges, and the bottom of the lower sealing head is provided with a balance pipe for draining alkali liquor during equipment maintenance.

Drawings

FIG. 1 is a front sectional view of a film distributor according to an embodiment of the present invention;

FIG. 2 is a bottom view of side A-A of FIG. 1;

FIG. 3 is a top view taken along line B-B of FIG. 1;

FIG. 4 is a schematic front view of a tube according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of a shell and tube falling-film evaporator provided by an embodiment of the utility model;

labeled as: 1. a film distributor; 101. a pipe body; 102. an overflow port; 103. spacing seams; 104. a central column; 105. a connecting rod; 106. an upper fan blade; 107. a middle fan blade; 108. a lower fan blade; 2. a barrel; 3. an alkali liquor inlet pipe; 4. a gas discharge valve; 5. an alkali liquor distribution ring; 6. an upper tube sheet; 7. a membrane lowering pipe; 8. an upper end enclosure; 9. a lower tube plate; 10. a baffle plate; 11. a lower end enclosure; 12. a balance tube; 13. a steam inlet pipe; 14. a baffle plate; 15. a condensate outlet pipe.

Detailed Description

The present invention will be described in detail with reference to the following embodiments in order to fully understand the objects, features and effects of the utility model, but the present invention is not limited thereto.

Referring to fig. 1 to 4, the film distributor 1 is composed of a pipe body 101, a central column 104 and a cut-off blade set, wherein a concave notch is formed in the side wall of the upper port of the pipe body 101 to form an alkali liquor overflow port 102, so that alkali liquor can flow into the film distributor 1 conveniently. The tube body 101 is a reducing tube structure, the outer diameter of the upper section of the tube body 101 is the same as the outer diameter of the falling film tube 7, the outer diameter of the lower section of the tube body 101 is the same as the inner diameter of the falling film tube 7, six to eight axial spacing slits 103 are uniformly arranged in the circumferential direction of the side wall of the middle lower part of the tube body 101, and the spacing slits 103 are communicated with the lower port of the tube body 101, so that most of alkali liquor flows to the inner wall of the falling film tube 7 along the spacing slits 103, the film forming effect is improved, and meanwhile, the lower section of the tube body 101 is convenient to shrink and insert into the upper end of the falling film tube 7, as shown in fig. 4. The port of the pipe body 101 is a slope surface, which is more beneficial to the film formation of the alkali liquor. The central column 104 is a solid column structure, a plurality of connecting rods 105 are welded to the upper end of the central column 104 in the circumferential direction, and the other ends of the connecting rods 105 are welded to the inner wall of the pipe body 101, so that the central column 104 is fixed on the axial center line of the pipe body 101, as shown in fig. 2. A plurality of cut-off blade sets are fixed on the side wall of the central column 104 below the tube body 101, each cut-off blade set is composed of an upper fan blade 106, a middle fan blade 107 and a lower fan blade 108, the upper fan blade, the middle fan blade and the lower fan blade are respectively welded on the side wall of the central column 104 in three directions according to the relative height positions of the upper fan blade, the middle fan blade and the lower fan blade, and the three fan blades form an approximate whole circle structure when viewed from a top view angle, as shown in fig. 3. The upper fan blade, the middle fan blade and the lower fan blade respectively extend to the position close to the inner wall of the falling film tube 7 from the fixed ends in a downward inclined mode, and a film forming channel for flowing and passing of alkali liquor is reserved between the outer edge of each fan blade and the inner wall of the falling film tube 7.

Referring to fig. 5, the shell-and-tube falling film evaporator is composed of an upper end enclosure 8, a cylinder 2, an upper tube plate 6, a lower tube plate 9, a lower end enclosure 11, a falling film tube 7, a film distributor 1 and the like, wherein flanges are respectively welded to the lower port of the upper end enclosure 8, the upper port of the lower end enclosure 11 and two ports of the cylinder 2, and the upper end enclosure and the lower end enclosure are respectively fixedly connected with two ends of the cylinder 2 through bolts and flanges. The bottom of the lower end enclosure 11 is connected with a balance pipe 12 for draining alkali liquor during equipment maintenance.

The upper tube plate 6 is welded on the inner wall of the upper part of the cylinder body 2 and is combined with the upper end enclosure 8 to form an upper alkali liquor inlet box structure. The side wall of the cylinder 2 above the upper tube plate 6 is connected with an alkali liquor inlet pipe 3 for conveying alkali liquor into the falling film evaporator. The inner wall of the cylinder body 2 above the upper tube plate 6 is also welded with a cylindrical alkali liquor distribution ring 5, and the diameter of the alkali liquor distribution ring 5 is smaller than that of the cylinder body 2 and larger than that of the total membrane-reducing tube 7. When the alkali liquor horizontally enters the alkali liquor inlet box through the alkali liquor inlet pipe 3, the alkali liquor collides with the cylinder wall of the alkali liquor distribution ring 5, the flowing direction is changed, and the alkali liquor flows downwards along the cylinder wall of the alkali liquor distribution ring 5, so that the fluctuation range of the alkali liquor is reduced, and the alkali liquor can be better formed into a film. The side wall of the cylinder 2 below the upper tube plate 6 is provided with a gas discharge valve 4 for discharging non-condensable gas so as to ensure the heat transfer area of the falling film evaporator. The middle upper part of the cylinder body 2 is provided with a steam inlet pipe 13, and a baffle plate 14 is fixed on the side wall of the cylinder body 2 at the outlet position of the steam inlet pipe 13 and used for changing the flow direction of steam, avoiding local overhigh heating and prolonging the service life of equipment.

The lower tube plate 9 is welded on the inner wall of the lower part of the cylinder body 2 and is combined with the lower end enclosure 11 to form an alkali liquor evaporation box structure at the lower part. The side wall of the cylinder 2 above the lower tube plate 9 is provided with a condensate outlet pipe 15 for conveying condensate. The inner side wall of the cylinder 2 is provided with a baffle plate 10.

The upper tube plate 6 and the lower tube plate 9 are respectively provided with a plurality of round holes corresponding in position for inserting and fixing the membrane falling tube 7. The upper end and the lower end of each membrane falling tube 7 are respectively inserted on the upper tube plate and the lower tube plate, and the membrane distributor 1 is inserted on the membrane falling tubes 7.

The working process is as follows:

firstly, a low-concentration potassium hydroxide solution enters the barrel body 2 through the alkali liquor inlet pipe 3, and the alkali liquor forms an annular space between the barrel body 2 and the alkali liquor distribution ring 5 for buffering and then enters the upper surface of the upper pipe plate 6.

Along with the rising of the liquid level of the alkali liquor, when the liquid level reaches the upper end overflow port 102 of the film distributor 1, the alkali liquor flows down along the inner wall of the film distributor 1 of the overflow port 102, most of the liquid flows down through the spacing seam 103 in the downward flowing process to form a film at the contact part of the film distributor 1 and the falling film pipe 7 and flows down along the inner wall of the falling film pipe 7, because the pressure fluctuates at the overflow port 102, part of the alkali liquor at the contact part of the membrane distributor 1 and the membrane falling pipe 7 directly flows into the central area of the membrane falling pipe 7, when the alkali liquor falls downwards, the alkali liquor is intercepted and collected by a secondary membrane distributing device, namely an intercepting blade group, positioned in the center of the falling film and is sent to the inner wall of the falling film pipe 7 to form a membrane again, after circulation of the alkali liquor is established, steam is introduced into the shell pass of the evaporator through a steam inlet pipe 13, high-temperature steam is baffled in the cylinder 2 for multiple times through the baffle plate 10 and heating of alkali liquor is completed, and the high-temperature steam is condensed into high-temperature liquid and then flows out of a condensate outlet pipe 15 for recycling. The temperature of the alkali liquor flowing downwards in the falling film pipe 7 gradually rises, the alkali liquor finally reaches a boiling state, the concentration of the alkali liquor gradually rises in the boiling process, and the concentration of the alkali liquor finally reaches the product quality requirement. The alkali liquor boiled at high temperature flows out of the lower tube plate 9 and then enters the gas-liquid separation tank through the alkali liquor outlet pipe to carry out gas-liquid separation.

Finally, it is noted that: the above-mentioned list is only the preferred embodiment of the present invention, and naturally those skilled in the art can make modifications and variations to the present invention, which should be considered as the protection scope of the present invention provided they are within the scope of the claims of the present invention and their equivalents.

Claims (6)

1. A film distributor of a falling film evaporator comprises a pipe body, a central column and intercepting blades; it is characterized in that the preparation method is characterized in that,

the pipe body is of a reducing pipe structure, the diameter of the lower section of the pipe body is smaller than that of the upper section of the pipe body, a concave notch is formed in the side wall of the upper port of the pipe body, and axial spacing seams are uniformly distributed in the circumferential direction on the side wall of the middle lower part of the pipe body;

the central column is fixed at the axial center in the pipe body, and a cut-off blade group is fixed on the side wall of the central column positioned below the pipe body;

the intercepting blade group comprises an upper blade, a middle blade and a lower blade, the upper blade, the middle blade and the lower blade are respectively fixed on the side wall of the central column in three directions according to the upper height position, the middle height position and the lower height position, the three blades are spliced into a whole circular structure, and the blades are downwards inclined and extended from the fixed end.

2. A shell-and-tube falling-film evaporator comprises a falling-film tube and the film distributor of the falling-film evaporator as claimed in claim 1, wherein the film distributor of the falling-film evaporator is inserted into the falling-film tube, and a film-forming channel for alkali liquor to flow through is reserved between the outer edge of a fan blade of an intercepting blade group and the inner wall of the falling-film tube.

3. A shell and tube falling film evaporator as claimed in claim 2 further comprising an upper tube plate, a lower tube plate and a cylinder, wherein the upper tube plate and the lower tube plate are respectively fixed at the upper part and the lower part in the cylinder, the upper tube plate and the lower tube plate are respectively provided with a plurality of round holes, and the upper end and the lower end of each falling film tube respectively penetrate through the round holes of the upper tube plate and the lower tube plate and are fixed in the cylinder.

4. A shell and tube falling film evaporator as claimed in claim 3 wherein the side wall of the barrel at the upper part of the upper tube plate is provided with an alkali liquor inlet tube, the side wall of the middle upper part of the barrel is provided with a gas discharge valve and a steam inlet tube, and the outlet of the steam inlet tube is provided with a baffle plate; and a condensate outlet pipe is arranged on the side wall of the cylinder body positioned at the upper part of the lower pipe plate.

5. A shell and tube falling film evaporator as claimed in claim 3 wherein a cylindrical lye distribution ring is fixed to the inner wall of the cylinder above the lye inlet tubes.

6. A shell and tube falling film evaporator as claimed in claim 3 further comprising an upper and a lower head, the upper and lower head are respectively connected with the upper and lower ports of the cylinder body through flanges, and the bottom of the lower head is provided with a balance tube.

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