Shell and tube heat exchanger

Abstract

A fluid heat exchange mixing device in a shell-and-tube heat exchanger capable of efficiently transferring heat to a fluid to be treated and agitating, mixing and transporting the fluid to be treated is provided. [Solution] A configuration in which multiple tubes 102 are arranged parallel to each other inside the shell, and a strip member 200 is arranged inside the tube, the strip member 200 having a width no larger than the inner diameter of the tube, punched holes on all sides, a corrugated shape in the longitudinal direction, and a spiral shape.

Description

[Technical field]

[0001] The present invention relates to a shell-and-tube heat exchanger, and more particularly to a shell-and-tube heat exchanger that efficiently transfers heat to a fluid to be treated and agitates, mixes, and transports the fluid to be treated. [Background technology]

[0002] (Conventional technology and problems) It is widely practiced to cool or heat a fluid to be treated by flowing the fluid through a pipe made of a material with high thermal conductivity and contacting a refrigerant or a high-temperature fluid around the pipe. In order to efficiently perform the cooling and heating process, it is also common to cool or heat the fluid to be treated in advance so that the temperature is close to the temperature after cooling and heating.

[0003] For example, when producing polymer products such as polyethylene and polypropylene, polymers adhere to the inner walls of a polymer reactor in which a catalyst and propylene are reacted in a solvent such as normal hexane to produce polypropylene. In addition, in a post-treatment device for transferring a mixed solution of a solvent and a polymerization product from the polymer reactor to pelletization or the like, polymers deposit and adhere to the inner walls of a transfer means, i.e., a tube, while cooling the solution, thereby causing so-called polymer fouling.

[0004] In some cases, a shell-and-tube heat exchanger is used as a transport means for transporting the polymer-solvent mixed solution from the polymer reactor to a post-treatment device for pelletization, etc., while cooling it. In this case, the polymer contained in the coolant and the solvent precipitates during the cooling step, and some of the precipitates adhere to and accumulate on the inner wall of the metal tube, resulting in the so-called fouling phenomenon.

[0005] The polymer deposits that adhere to and accumulate have a thermal conductivity that is about two orders of magnitude lower than that of metal pipes, and therefore the polymer deposits significantly reduce the removal of the reaction heat, i.e., the cooling efficiency. At the same time, the effective pipe diameter becomes smaller and the pressure increases, which increases the load on the transport pump, causing damage to the transport pump and reducing production efficiency due to a reduced flow rate.

[0006] In the polymerization of polypropylene, etc., the polymerization reaction in the polymerization reactor generates reaction heat. If this reaction heat is not efficiently removed, i.e., cooled, the operating conditions cannot be controlled, and the physical properties of the polymerization reactants change significantly, which may force the reactor to be shut down.

[0007] For the above reasons, it is strongly desired to suppress the occurrence of the fouling phenomenon and to ensure efficient heat exchange and transport of the treated fluid.

[0008] For this reason, it has been proposed to arrange a shell-and-tube structure inside an outer tubular body, and a plurality of elements are fixed to the outer circumferential surface of the inner tubular body in a spiral shape, and a heat medium is made to flow in a spiral manner through the spiral elements in the space between the outer circumferential surface of the inner tubular body and the inner circumferential surface of the outer tubular body, thereby exchanging heat (see, for example, Patent Document 1). This technology has been in use for many years. However, the fluid to be treated flowing inside the inner tubular body continues to flow through the center part and the peripheral part over the entire length of the inner tubular body, so that the center part of the tube is difficult to cool, and the heat exchange efficiency is low. In addition, there is a problem that it is difficult to form a spiral body and arrange it in the space, and to clean the space.

[0009] As another prior art technique for suppressing the occurrence of fouling and stirring, mixing and transferring the treated fluid, a method has been proposed in which a spiral body is placed in the treated fluid flow path where heat is transferred by a heat medium, and the treated fluid moves in a spiral manner within the flow path to efficiently exchange heat with the treated fluid (see, for example, Patent Document 2). The spiral body is made by corrugating a flat metal band or an embossed metal band in the longitudinal direction, so that the side ends of the metal band are more likely to extend in the longitudinal direction than the center. It has also been proposed to configure the metal band with a net (mesh) band (see Patent Document 2).

[0010] By configuring the spiral in this way, it is easy to form the spiral. However, if the thickness of the metal flat strip is reduced or a metal with low rigidity is used to weaken the force required to form the spiral, the force that keeps the spiral straight is weakened, and when the spiral is inserted into a heat exchange tube, the spiral is bent and the spiral cannot be extended over the entire length of the heat exchange tube. If the metal strip is configured as a net (mesh) strip, it is difficult to deform the spiral into a spiral shape due to the high rigidity of the wire in the net (mesh) strip structure. In addition, the spiral is not formed straight when deformed into a spiral shape, and the problem that the spiral is bent and the spiral cannot be extended over the entire length of the heat exchange tube when the spiral is inserted into the heat exchange tube is greater than that in the case of a flat metal strip or an embossed metal strip.

[0011] As a configuration for arranging a spiral in another conventional heat exchange tube, it has been proposed to cut the spiral in half in the width direction alternately and advance the rotation direction of the spiral downstream of the cut part by 90 degrees to ensure stirring, mixing, and transporting the treated fluid and to perform efficient heat exchange (see, for example, Patent Document 3). According to this technology, the treated fluid is mixed more reliably than when a spiral made of a flat metal strip or an embossed metal strip is used, but the straightness of the cut parts of the spiral is weak, and it is difficult to insert the spiral into the heat exchange tube while maintaining its straightness. In other words, it is impossible to select the type and thickness of the metal material of the strip-shaped member so that the spiral can be distributed over the entire length of the heat exchange tube without bending, while maintaining its straightness while maintaining its corrugated or spiral shape. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Japanese Patent Application Publication No. 10-309451 [Patent Document 2] JP 2016-148459 A [Patent Document 3] Patent No. 6675132 Summary of the Invention

[0013] (Purpose of the invention) The present invention has been developed in consideration of the above-mentioned problems of the conventional art related to shell-and-tube heat exchangers, and has an object to provide a shell-and-tube heat exchanger that can efficiently transfer heat to the treated fluid and agitate, mix, and transport the treated fluid. Another object of the present invention is to provide a shell-and-tube heat exchanger device including a spiral body that maintains the formed corrugated or spiral shape with high rigidity, has a moderate rigidity that allows the spiral body to be inserted into the heat exchange tube and extend over the entire length of the heat exchange tube, is robust overall, and allows the spiral body to be easily cleaned or replaced. It is another object of the present invention to provide a shell-and-tube heat exchanger device which can be bent as desired. Another object of the present invention is to provide a shell-and-tube heat exchanger which can be used continuously for a long period of time with extremely little fouling occurring during heat exchange, mixing and transport of the fluid to be treated. [Means for solving the problem]

[0014] The present invention is a shell-and-tube heat exchanger in which multiple tubes are arranged parallel to each other inside a shell, This is a shell-and-tube heat exchanger characterized in that a strip member having a width not larger than the inner diameter of the tube, punched holes on all sides, corrugated in the longitudinal direction, and spiral shape is disposed inside the tube.

[0015] The embodiments of the present invention are as follows. The band plate member is fixed so as not to move or rotate within the tube.

[0016] The strip member is made of any one of stainless steel, titanium, copper, and aluminum.

[0017] The punched holes are generally circular.

[0018] The punched holes are generally hexagonal.

[0019] The width of the band plate member is at least 5% smaller than the inner diameter of the heat exchange tube.

[0020] The strip member is characterized in that it is electrolytically polished.

[0021] The strip member is characterized in that burrs are removed by sound blasting.

[0022] The punch porosity of the strip member is greater than 20% and not greater than 40%.

[0023] The punch porosity of the strip member is uniform throughout the strip member.

[0024] The punch porosity of the band plate member is larger in the peripheral portion than in the central portion in the width direction of the band plate member.

[0025] The strip member has a tip fixed to the vicinity of the inlet of the heat exchange tube.

[0026] The length of the band plate member is not longer than the length of the heat exchange tube. Effect of the Invention

[0027] According to the present invention, it is possible to provide a shell-and-tube heat exchanger that can efficiently transfer heat to a fluid to be treated and can agitate, mix, and transport the fluid to be treated.

[0028] The present invention also provides a shell-and-tube heat exchanger device including a spiral that maintains the realized corrugated or spiral shape with high rigidity, has a moderate rigidity that allows the spiral to be inserted into the heat exchange tube and extend over the entire length of the heat exchange tube, is robust overall, and allows the spiral to be easily cleaned or replaced.

[0029] The present invention also provides a shell-and-tube heat exchanger device that can be bent.

[0030] The present invention also provides a shell-and-tube heat exchanger including a spiral that can maintain the formed corrugated or spiral shape with high rigidity and also maintain linearity with high rigidity, allowing the spiral to run along the entire length of the tube, and further allowing the spiral to be easily cleaned and replaced.

[0031] Furthermore, the present invention provides a shell-and-tube heat exchanger that can be used continuously for a long period of time without causing industrially problematic fouling in the heat exchange, mixing, and transport of fluids. [Brief description of the drawings]

[0032] [Figure 1] 1 is a partially cut-away front view of a shell-and-tube heat exchanger according to an embodiment of the present invention, in which the heat exchange tubes are enlarged and shifted in position to facilitate understanding of the configuration and operation of the shell-and-tube heat exchanger; [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II in FIG. [Diagram 3] FIG. 2 is a cross-sectional view taken along the centerline of a tube of an embodiment of a shell-and-tube heat exchanger. [Figure 4A] FIG. 2 is a plan view showing the processing state of the strip member of the shell-and-tube heat exchanger of the embodiment, showing the strip member after punch holes are processed. [Figure 4B] FIG. 1 is a perspective view showing the processing state of a band plate member of a shell-and-tube heat exchanger according to an embodiment, in which a corrugated processing is performed on a band plate member on which punch holes have been processed. [Figure 4C] FIG. 13 is a perspective view showing the processing state of a strip member of a shell-and-tube heat exchanger according to an embodiment, in which a strip member that has been subjected to punch hole processing and corrugation processing and then spiral processing is performed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] (Example) The shell-and-tube heat exchanger according to the embodiment of the present invention will be described with reference to the drawings. All numerical values ​​in the description of the embodiment are merely examples.

[0034] The shell-and-tube heat exchanger 1 according to the embodiment of the present invention is a shell-and-tube type device having a heat exchange, mixing and transport function, and used for a pressure vessel for carrying out a low pressure polyethylene polymerization process. There are three types of shell-and-tube heat exchangers known: fixed tube plate type, floating head type, and U-tube type. The shell-and-tube heat exchanger 1 is of the floating head type, and the expansion and contraction of the long heat exchange tubes caused by the high temperature and pressure of the heat exchange fluid is absorbed by the movement of the floating head.

[0035] 1, the shell-and-tube heat exchanger 1 has a body, i.e., a shell 10, which is divided by a tube support plate 12 to form a solution region 14 and a heat transfer region 16. Inside the shell 10, for example, about 2000 tubes 102 are arranged in parallel to each other.

[0036] 1, the solution area 14 that contains the solution R is protected by covering both ends of the shell 10 with shell covers 20. The solution R flows in from a solution inlet R1 on the lower side of the shell 10, passes through a discrimination mechanism 101 and a tube 102, and flows out from a solution outlet R2 on the upper side of the shell 10. The tube 102 has a floating head 34 that absorbs thermal expansion of the tube 102 of the shell 10. A mixed solution of normal hexane and a polymer is exemplified as the solution R. The discrimination mechanism 101 sends the solution R that has flowed in to a tube 102, and sends only the solution R that has passed through the tube 102 to a solution outlet R2.

[0037] The refrigerant region 16, which contains a refrigerant W such as cooling water, is formed so that the refrigerant W flowing in from a refrigerant inlet W1 provided on the upper side of the shell 10 flows around the tubes 102. The refrigerant W having passed around the tubes 102 flows out from a refrigerant outlet W2 provided on the lower side of the shell 10.

[0038] The length of the refrigerant flowing portion of tube 102 is approximately 10 m, with an outer diameter of 29.0 mm, a wall thickness of 2.0 mm, and an inner diameter of 25.0 mm.

[0039] 3, a spiral-shaped band member 200 is disposed within the tube 102. The tube 102 is fixed by welding 206 to a tube support plate 202 fixed to the inside of the shell 10 near the inlet end. The end of the band member 200 on the tube support plate 202 side is fixed to the inlet end of the tube 102, preventing the band member 200 from moving and rotating within the tube 102.

[0040] 4A, the band plate member 200 is formed by cutting a punched plate material having a thickness of 0.5 mm, in which punched circular holes 210 having a diameter di of 3.0 mm are arranged in a staggered pattern with a widthwise interval dw of 5.0 mm and a longitudinal interval dl of 8.0 mm, into a band-shaped flat plate having a width of 22.0 mm along length cutting lines 203l and width cutting lines 203w, and then deforming the cut plate. Instead of stainless steel SUS305, any of titanium, copper, and aluminum may be used.

[0041] The punch hole ratio of this strip plate member 200 is calculated. The punch hole ratio is the total area of ​​the punch holes within a given area, divided by the given area, and multiplied by 100. The area of ​​the strip plate member 200 with a width of 21 mm and a length of 10,000 mm is 210,000 mm. 2 The area of ​​one punch hole is 7.11 mm 2 Since the number of punch holes is 4379, the total area of ​​the punch holes is 31135 mm 2Therefore, the punch porosity is (31135 ÷ 210000 × 100 ≒) 15.0%. The punch porosity is preferably 5 to 95%, more preferably 10 to 40%, and even more preferably 12 to 20%.

[0042] The band-shaped flat plate member 200 is deformed into a waveform having a wavelength wl of 6 mm and a height (distance from the lower base to the upper top) wh of 2.6 mm, as shown in FIG. 4B.

[0043] The band plate member 200 deformed into a corrugated shape is deformed into a spiral shape with a pitch wp of 160.0 mm, as shown in FIG. 4C. The band plate member 200 deformed into a corrugated and spiral shape has no change in the wave height at the widthwise center, but the wave height wh is reduced from 2.6 mm to 2.0 mm and the thickness of the band plate member 200 is reduced from 0.5 mm to 0.4 mm at the widthwise end portions. This change is due to the fact that neither the wave height nor the thickness of the plate member is changed at the widthwise center, but the wave height is reduced at the widthwise end portions, i.e., the band plate member is flattened and the thickness of the band plate member is reduced, thereby realizing the spiral deformation. Due to the reduction in thickness at the widthwise end portions of the band plate member 200, the punch holes 210 are naturally elongated in the longitudinal direction and become elliptical.

[0044] Theoretically, the strip member 200 can be deformed into a helical shape by either punching the circular holes 210 or corrugating the strip member. However, if an available metal having sufficient chemical resistance, temperature resistance, pressure resistance, impact resistance, etc. for a fluid heat exchange, mixing, and transporting device is used, the strip member will not maintain its straightness and will meander, making it impossible to insert the strip member into the tube 102. In order to realize a helical strip member 200 using a currently available metal, it is necessary to punch the circular holes and corrugate the strip member.

[0045] Within the tube 102, turbulence is generated in the solution R due to the effect of the corrugation of the strip member 200 on the entire solution R and the effect of some of the solution R passing through the punch holes 210 of the strip member 200, so the present invention also has the effect of reducing the occurrence of fouling. The punched holes may be hexagonal.

[0046] The tube 102 described above has an inner diameter of 25.0 mm, and a strip member with a width of 21.0 mm is inserted into it, so there is a space of 2.0 mm between the tube 102 and the spiral strip member 200. This space allows the tube 102 to be bent while maintaining efficient heat transfer to the fluid being treated, and stirring, mixing, and transport of the fluid being treated. If the tube 102 is used in a straight line, the inner diameter of the tube 102 and the width of the strip member 200 may be the same.

[0047] The band plate member 200 cut from the punched plate material described above generates burrs due to punching and cutting. These burrs can be removed by deburring with a file or sandblasting to make the member safe to handle. Furthermore, if the deburring is performed by electrolytic polishing, the member can be made beautiful in addition to being safe. [Explanation of symbols]

[0048] R solution W Refrigerant 1. Shell and tube heat exchanger 10 Shell 12 Tube support plate 14 Solution Room 16 Refrigerant chamber 20 Refrigerant chamber cover 102 Tube 200 Strip material 206 Welding 210 Punch Circular Hole

Claims

1. A fluid heat exchange, mixing, and transporting device having a plurality of tubes arranged parallel to each other inside a shell, A fluid heat exchange, mixing and transport device characterized in that a strip member having a width not larger than the inner diameter of the heat exchange tube, punched holes on its entire surface, corrugated in the longitudinal direction, and spiral is disposed inside the heat exchange tube.

2. 2. The fluid heat exchange, mixing and transporting device according to claim 1, wherein said band plate member is fixed so as not to move or rotate within said heat exchange tube.

3. 2. The fluid heat exchanging, mixing and transporting device according to claim 1, wherein said strip member is made of any one of stainless steel, titanium, copper and aluminum.

4. 2. The fluid heat exchanging, mixing and transporting device of claim 1, wherein said punched holes are generally circular.

5. 2. The fluid heat exchanging, mixing and transporting device of claim 1, wherein said punched holes are generally hexagonal in shape.

6. 2. A fluid heat exchange, mixing and transporting device according to claim 1, wherein the width of said band member is smaller than the inner diameter of said heat exchange tube by 5% or more.

7. 2. The fluid heat exchanging, mixing and transporting apparatus according to claim 1, wherein said strip member is electropolished.

8. 2. The fluid heat exchanging, mixing and transporting apparatus of claim 1, wherein said strip member is deburred by sound blasting.

9. 2. The fluid heat exchanging, mixing and transporting device according to claim 1, wherein the punch porosity of said strip member is greater than 20% and less than or equal to 60%.

10. 2. The fluid heat exchanging, mixing and transporting apparatus of claim 1, wherein the punch porosity of said strip member is uniform throughout said strip member.

11. 2. A fluid heat exchanging, mixing and transporting device according to claim 1, wherein the punch porosity of said strip member is greater in the peripheral portion than in the central portion in the width direction of said strip member.

12. 2. A fluid heat exchange, mixing and transporting device according to claim 1, wherein a tip of said strip member is fixed to the vicinity of an inlet of said heat exchange tube.

13. 2. The fluid heat exchanging, mixing and transporting apparatus according to claim 1, wherein the length of said strip member is shorter than the length of said heat exchange tubes.

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