JP2912141B2 - Liquid disperser installed in heat transfer tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical pipe-type falling film type multi-tube heat exchanger, heater, cooler, evaporator, condenser, etc.
The present invention relates to a liquid disperser provided on an upper tube of a heat transfer tube used for an absorber or the like.

[0002]

2. Description of the Related Art Conventionally, a vertical type falling film type multi-tube heat exchanger, a heater, a cooler, an evaporator, a condenser, an absorber, etc. are required to form a liquid film in a tube. Usually, a liquid disperser as shown in FIG. 4 is widely used at the top of a heat transfer tube.

FIG. 4 shows a method in which a liquid film collected on a tube sheet is overflown from the top without providing a liquid disperser 1, thereby forming a falling liquid film. In this case, in order to uniformly distribute the liquid to the plurality of heat transfer tubes 2, it is necessary to make the height of the top of each tube the same, to achieve high manufacturing accuracy and high verticality when installing the equipment. Is required. In this method, when the flow rate of the liquid is small, the liquid flows down not only from the entire periphery of the top portion of the heat transfer tube but only from a part thereof, so that a uniform falling liquid film is not formed. FIG. 5 shows a liquid disperser 1 in which a tube having an outer diameter smaller than the inner diameter of the heat transfer tube 2 is inserted at the top of the heat transfer tube 2 for the purpose of assisting the formation of a falling liquid film in the type of FIG. is there. The supplied liquid flows down the gap between the liquid disperser 1 and the heat transfer tube 2 to form a falling liquid film. In this case, the thickness of the flowing liquid film to be formed in the circumferential direction depends on the size of the gap between the liquid disperser 1 and the heat transfer tube 2, so that the centers of the liquid disperser 1 and the heat transfer tube 2 match as much as possible. In addition, it is necessary to install the liquid disperser 1 with high accuracy.

FIG. 6 shows a liquid disperser 1 provided with a plurality of triangular notches in order to overcome the disadvantages of FIGS. In this case, in order to uniformly distribute the liquid to the plurality of heat transfer tubes 2 by the plurality of liquid dispersers 1, the production accuracy and the installation accuracy of the apparatus as shown in FIG. 4 are not necessary, but since there is a triangular cutout. In addition, at a certain height below the liquid disperser 1, there is a disadvantage that the thickness of the formed submerged liquid film in the circumferential direction is not constant.

FIGS. 7 and 8 show a plurality of rectangular holes or circular holes formed in the tangential direction in the circumferential direction of the liquid disperser 1 in order to overcome the disadvantages of FIGS. 111 (hereinafter,
It is called an opening. ). This opening 11
By setting the opening area appropriately, 1 can create an appropriate resistance to the flow of liquid, and as a result, the liquid level on the tube sheet can be maintained at an appropriate height above the opening 111, so that a plurality of Uniform distribution to the heat transfer tubes 2 becomes possible. In addition, since the opening 111 is opened in the tangential direction of the circumference, the liquid flows down to the spiral strip due to the force of forcibly flowing in the circumferential direction at a certain height below the liquid disperser 1. Therefore, the thickness of the falling liquid film in the circumferential direction is more uniform than in the case of FIGS. 4, 5, and 6, and a good liquid liquid film is formed even when the liquid flow rate is small. In addition to FIGS. 4 to 8, for example, a combination of the liquid disperser 1 having a plurality of openings 111 opened in the radial direction in FIG. 5 is also used.

[0006]

As described above, FIG.
The conventional liquid disperser 1 shown in FIG. 8 has the following problems to be solved. (1) In any type of liquid disperser 1, the heat transfer tube 2 is placed to some extent (10 m) above the tube plate upper surface in order to install itself.
m to 50 mm) (hereinafter, referred to as a tube end protruding portion). Therefore, when welding a plurality of densely packed heat transfer tubes and a tube sheet, the range in which the welding rod can be operated is narrow, and a high level of skill is required for the welding operation, which is troublesome. Naturally, it was impossible to use an automatic welding machine or the like. In some cases, for the sole purpose of ensuring the welding workability, the interval between the heat transfer tubes must be wider than is necessary for the performance of the equipment, and as a result, the diameter of the equipment must be increased. Was. (2) Since the heat transfer tube 2 protrudes 10 mm to 50 mm above the tube sheet, the heat transfer tube 2 is welded to the tube sheet at the time of periodic inspection of this device (because the disperser is removed during the inspection and the inspection is performed). Visual inspection and inspection of the part were troublesome. (3) Since the liquid disperser 1 is fixed only at the protruding portion of the tube end of about 10 mm to 50 mm, it is difficult to install the liquid disperser 1 vertically with respect to the tube sheet (parallel to the heat transfer tube 2).
There was a slight inclination and rattling. In order to maximize the performance of the liquid disperser 1, the portion where the liquid disperser 1 is in contact with the pipe end protruding portion is sealed by packing or the like.
It is necessary to prevent the liquid from leaking. However, if the liquid disperser 1 is installed in an imperfect form for the above-mentioned reason, the seal becomes insufficient and the liquid per one heat transfer tube 2 becomes insufficient. In some cases, the flow rate becomes non-uniform for each pipe, or the formation of a falling film in the pipe is adversely affected, resulting in a decrease in equipment performance. In the case of the liquid disperser 1 of the type shown in FIG. 5, in addition, the gap between the liquid disperser 1 and the inner wall of the heat transfer tube 2 is not constant in the circumferential direction when the liquid disperser 1 is installed at an angle, and There was also a problem that the thickness became uneven. (4) The steel pipe used in the multi-tube heat exchanger usually has a manufacturing error of up to about 5% in the inner diameter. For example, in the case of the heat transfer pipe 2 having an inner diameter of 50 mm, the liquid dispersion of the type shown in FIGS. In the vessel 1, a step of about 1.25 mm at the maximum occurs between the outer wall and the inner wall of the heat transfer tube 2. There is a problem that the flow of the falling liquid film is disturbed at the step. (5) When the liquid forming the falling liquid film is corrosive, the inner wall of the heat transfer tube 2 is always in contact with this liquid, so that it is inevitable that the inner wall of the heat transfer tube 2 is subject to constant corrosion. In doing so, it is necessary to consider the corrosion rate and the like. On the other hand, if the seal of the seal portion between the liquid disperser 1 and the heat transfer tube 2 becomes defective once for the above-mentioned reason (3), the tube end protruding portion of the heat transfer tube 2 is corroded from the outside. This leads to poor sealing due to the reduced wall thickness of the protruding portion of the tube end, which promotes poor installation of the liquid disperser 1. Since it is virtually impossible to repair the heat transfer tube 2 in which the wall thickness of the tube end protruding portion has been extremely advanced, if the heat transfer tube 2 is found by a periodic inspection or the like, it must be dealt with by blacking the heat transfer tube 2. Therefore, a reduction in performance or a reduction in processing capacity is inevitable. In the case of the liquid disperser 1 of the type shown in FIGS. 6 to 8, the contact portion between the liquid disperser 1 and the heat transfer tube 2 can be sealed by packing or the like. 2
The liquid forming the falling liquid film is sealed from the boundary of the inner wall of the
It is inevitable to invade the seal portion, which contributes to corrosion of the seal portion at the protruding portion of the pipe end.

[0007] The liquid disperser provided in the heat transfer tube of the present invention has a superior liquid dispersing performance as compared with the prior art, and also solves the above-described problem of eliminating the need to provide a tube end protruding portion on the tube sheet. It is an object of the present invention to provide a liquid disperser for a falling-film type multi-tube heat exchanger flowing in a mold tube.

[0008]

In order to solve the above-mentioned problems, a liquid disperser provided in a heat transfer tube according to the present invention comprises a liquid disperser provided at an upper end of a heat transfer tube for a vertical film falling-down film type heat exchanger or the like. In the disperser, the liquid disperser includes a protrusion protruding from the upper end of the heat transfer tube, a flange protruding outward at the upper end of the heat transfer tube, and a leg inscribed in the heat transfer tube, and A liquid disperser provided in a heat transfer tube, wherein the protrusion has a plurality of openings opened in a tangential direction of a circumference.

[0009]

The operation and effect will be described in detail based on the embodiment of the liquid disperser provided in the heat transfer tube of the present invention shown in FIG. 1. The liquid disperser 1 has a protrusion 11 protruding from the upper end of the heat transfer tube 2 and a transfer member. The upper end of the heat pipe 2 is composed of a flange 12 projecting to the outer periphery and a leg 13 inscribed in the heat transfer tube 2, and the protrusion 11 uniformly distributes the supply liquid for each heat transfer tube 2, And, in the liquid supply unit for forming a uniform falling liquid film,
In a vertical falling-film liquid-film multi-tube heat exchanger having a circular hole or a rectangular opening 111 formed in the tangential direction of the circumference, a heat transfer tube 2 having an inner diameter of 20 to 70 mm is usually used. However, depending on the inner diameter, the heat transfer tube 2
The diameter of the circular opening portion 111 of the liquid dispersion device 1 is 2 mm to 4 mm, and the number thereof can be 3 to 8 although it depends on the processing amount per one. In the rectangular opening 111 of the liquid disperser 1, a width of 0.5 mm to 5 mm, a height of 10 mm to 100 mm, and a number of 3 to 8 can be used. FIG. 1 shows, as an example of the liquid disperser provided in the heat transfer tube of the present invention, an example in which a seal portion 122 is used below the upper surface of the tube sheet in addition to the seal portion 121. Thus, the sealing performance can be improved. Depending on the conditions of use, commercially available seal materials such as Vulka packing and Teflon packing can be used.

The heat transfer tube 2 and the tube sheet 3 are welded on the upper surface of the tube sheet 3 as shown in FIG.
In order to further improve the sealing performance, it is preferable that the welded portion and the heat transfer tube tip are machined flat so as to form the same horizontal plane. In order to prevent the liquid disperser 1 from dropping into the heat transfer tube 2, a flange 12 is provided around the liquid disperser 1. The vertical cross-sectional shape of the legs installed so as to cover the inner surface of the inner wall of the heat transfer tube 2 extends parallel to the heat transfer tube 2 as shown in the enlarged view of the legs in FIG. 1 from the viewpoint of the dispersion performance of the falling liquid film. And a tapered portion 132 which is obliquely cut at an angle θ so that the portion closer to the heat transfer tube 2 becomes longer. The angle θ of the tapered portion 132 which is cut obliquely is desirably 5 degrees or more and 30 degrees or less with respect to the vertical from the viewpoint of the dispersion performance of the falling liquid film. 3
If it exceeds 0 degree, the degree of non-uniformity of the falling liquid film increases as shown in Comparative Example 1 described below, which is not preferable. If the angle is less than 5 degrees, the formation of the liquid film is not a problem, but the length of the leg becomes longer than necessary. The tip of the taper portion 132 may be sharp, but in consideration of the safety of the worker at the time of transportation and installation, the prevention of bending of the sharp portion of the tip at the time of falling, and the dispersibility of the falling liquid film, It may be used by shaving to have a thickness of 0.3 to 1.5 mm, preferably 0.3 to 0.75 mm. The shape of the tip after shaving may be flat or round. Even if the thickness after shaving is less than 0.3 mm, there is no problem in dispersion of the falling liquid film.
There are problems such as the safety of workers after installation and bending of the tip when dropped. On the other hand, if it exceeds 1.5 mm, there is no problem with the safety of the worker at the time of transportation / installation after manufacture and the bending of the tip part at the time of dropping, but the dispersion of the falling liquid film as shown in Comparative Example 2 described later. Gets worse. 20 mm below the upper surface of the tube sheet 3
Since the portion up to the extent has been subjected to thermal distortion due to welding of the heat transfer tube 2 and the tube plate 3, if the liquid forming the falling liquid film is corrosive, it is desirable that the liquid does not directly come into contact with this liquid.
The tip of the leg of the liquid distributor 1 is at least three times higher than the upper surface of the tube sheet.
It is desirable to be located about 0 mm below. Liquid disperser 1
The length of the leg 13 is better to be vertically installed with high accuracy, and it depends on the inner diameter of the heat transfer tube 2. However, in practice, the length is about 30 mm to 200 mm. As the material of the liquid disperser 1, ordinary carbon steel, stainless steel, or the like can be used depending on the purpose of use. In addition, as described in Examples described below, as an evaluation method of the uniformity of the falling liquid film,
At the outlet of the heat transfer tube 2, the pipe was partitioned into eight equal parts in the circumferential direction, the outflow amount at each partition was measured, and a variable X defined by the following equation (1) was used. The smaller X indicates that the falling liquid film is formed more uniformly in the circumferential direction. X = σ / ω (1) where, σ: standard deviation of flow rate for each partition ω: average flow rate for each partition

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a liquid disperser provided in a heat transfer tube according to the present invention will be described below with reference to FIGS. 1, 2 and 3. FIG. In the liquid disperser 1 provided at the upper end, the liquid disperser 1 has a protrusion 11 protruding from the upper end of the heat transfer tube 2, a flange 12 protruding outward at the upper end of the heat transfer tube 2, and Leg 1 to touch
3, and the projecting portion 11 has a plurality of openings 111 opened in a tangential direction of the circumference, and the leg portion 13 is provided with the heat transfer tube. 2 and a taper portion 132 angled so that the portion closer to the heat transfer tube 2 as it approaches the tip becomes longer. A liquid disperser to be provided;
Is a liquid disperser provided on the heat transfer tube, wherein a seal portion 121 is provided at a contact portion with the upper end of the heat transfer tube 2.

Embodiment 1 The material of the vertical heat transfer tube is stainless steel, the inner diameter is 26 mm,
A single piece having a length of 2000 mm was prepared, and after welding to a tube sheet, a liquid disperser provided in the heat transfer tube of the present invention while being kept vertical was installed. This liquid disperser was provided with six holes having a diameter of 3.0 mm and opened in the tangential direction of the circumference. The angle of the leg was cut at an angle of 5 degrees, and the tip was flattened to a thickness of 0.3 mm. The tip of the leg was located 100 mm below the top of the tubesheet. A commercially available Teflon was used as the seal material. Liquid flow rate is 301 / h to 2001 / h
It was done in the range. At the outlet of the heat transfer tube, the pipe is divided into eight equal parts, the outflow at each partition is measured, and using equation (1),
The circumferential flow rate distribution of the falling liquid film was evaluated. Table 1 shows the results
Example 2 The flow of the liquid film in the circumferential direction of the falling liquid film was performed in the same manner as in Example 1 except that the angle of the legs of the liquid disperser of Example 1 was changed from 5 degrees to 30 degrees. The distribution was evaluated. Table 1 shows the results. Example 3 The thickness of the tip of the leg of the liquid disperser of Example 1 was 0.3 mm.
The procedure was performed in the same manner as in Example 1 except that the flow rate was changed to 1.5 mm, and the flow rate distribution in the circumferential direction of the falling liquid film was evaluated. Table 1 shows the results. Example 4 A test vertical vertical tube falling film multi-tube heating tube equipped with a duplex stainless steel heat transfer tube having the same dimensions as in Example 1 and a liquid disperser of the same material according to the present invention was manufactured. The corrosion test was conducted at the urea plant under the same conditions as those of a normal vertical pipe falling film high pressure stripper under the following conditions. Liquid composition: urea 30 to 40% by weight Free ammonia 20 to 40% by weight Ammonium carbamate 20 to 25% by weight (the rest is water) Temperature: 180 ° C to 200 ° C Pressure: 140 to 180 bar Test period: 1 year Test result : No corrosion was found in the weld between the heat transfer tube and the tube sheet, and no evidence of defective sealing of the liquid disperser and the heat transfer tube was found. The corrosion rate of the inner wall of the heat transfer tube covered by the legs of the disperser was negligible compared to other parts. Dirt on the heat transfer surface due to poor liquid film formation was not observed. Reference Example 1 In place of the liquid disperser of Example 1, a liquid disperser according to the prior art having the same diameter and the number of holes formed in the tangential direction of the circumference was implemented except that a disperser of the type shown in FIG. 8 was installed. The test was performed under the same conditions as in Example 1 to evaluate the flow rate distribution in the circumferential direction of the falling liquid film. Comparative Example 1 The same operation as in Example 2 was carried out except that the angle of the obliquely cut portion of the leg of the liquid disperser of Example 2 was changed from 30 degrees to 45 degrees, and the circumferential direction of the falling liquid film in the circumferential direction was changed. The flow distribution was evaluated. Table 1 shows the results. Comparative Example 2 The thickness of the tip of the leg of the liquid disperser of Example 3 was 1.5 mm.
The same procedure as in Example 1 was carried out except that the thickness was changed to 2.5 mm, and the flow rate distribution in the circumferential direction of the falling liquid film was evaluated. Table 1 shows the results.

[0013]

The liquid disperser provided on the heat transfer tube of the present invention is constructed so that the legs of the liquid disperser can be extended as necessary and inserted into the heat transfer tube without providing a tube end protruding portion. Therefore, the following effects are obtained. (1) Since there is no pipe end protruding portion, the welding workability between the heat transfer tube and the tube sheet is remarkably improved, and an automatic welding machine can be applied. In addition, inspection and repair of welds during periodic inspections have become easier. (2) Since the legs of the liquid disperser can be extended and inserted into the heat transfer tube and fixed, the verticality of the liquid disperser can be maintained with high accuracy and the seal can be stably installed. The short path of the liquid and the defective formation of the liquid film were prevented, the performance of the equipment was improved, and the contamination of the heat transfer surface was prevented. (3) Since there is no tube end protruding portion of the heat transfer tube and the upper portion of the heat transfer tube is completely covered with the flange portion and the leg portion of the liquid distributor,
Corrosion of the portion where the liquid disperser is installed and the seal portion was significantly reduced, and the life of the heat exchanger was extended. (4) The tip of the leg of the liquid disperser has an appropriate angle and has a tapered shape that spreads in the direction of the inner wall of the heat transfer tube as it goes down. Has an inertial force that tends to flow outward, that is, toward the heat transfer tube wall side. Therefore,
Even if there was a step due to the manufacturing tolerance of the heat transfer tube, a stable and uniform falling liquid film was formed as compared with the prior art, and the performance of the equipment was improved and the heat transfer surface was prevented from being stained.

[Brief description of the drawings]

FIG. 1 is a side sectional view of a liquid disperser provided in a heat transfer tube of the present invention.

FIG. 2 is a perspective view of the liquid disperser provided in the heat transfer tube of the present invention.
It is a sectional view taken on line A.

FIG. 3 is a partially enlarged view of a side sectional view of a liquid disperser provided in the heat transfer tube of the present invention.

FIG. 4 is a side sectional view of a conventional overflow type liquid disperser.

FIG. 5 is a side sectional view of a conventional double-tube liquid disperser.

FIG. 6 is a side sectional view of a conventional notch type liquid disperser.

FIG. 7A is a side sectional view of a conventional slot type liquid disperser, and FIG. 7B is a plan sectional view taken along line AA of FIG.

8A is a side sectional view of a conventional hole type liquid disperser, and FIG. 8B is a plan sectional view taken along line AA of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid disperser 11 ... Projection part 111 ... Opening part 12 ... Flange part 121 ... Seal part 13 ... Leg part 131 ... Parallel part 132 ... Te -Paper part 2 ... Heat transfer tube 3 ... Tube sheet 4 ... Welded part.

Claims (2)

(57) [Claims] 1. A liquid disperser provided at the upper end of a heat transfer tube for a vertical film falling liquid film heat exchanger or the like, wherein the liquid disperser has a protruding portion projecting from the upper end of the heat transfer tube and an upper end of the heat transfer tube. At the contact part with the upper end of the heat transfer tube protruding to the outer periphery.
And a plurality of openings that are opened in the connecting direction of the protrusion or the circumference, comprising a flange provided with a metal part and a leg inscribed in the heat transfer tube. Liquid disperser installed in the heat transfer tube. 2. A method according to claim 1, wherein the leg portion has a parallel portion extending in parallel with the heat transfer tube, and a leg closer to the heat transfer tube as approaching the tip.
The liquid disperser provided in a heat transfer tube according to claim 1, comprising a tapered portion angled so as to be longer.