CN114963803A - Heat exchanger with two-way pull rod assembly - Google Patents

Heat exchanger with two-way pull rod assembly Download PDF

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Publication number
CN114963803A
CN114963803A CN202210594298.8A CN202210594298A CN114963803A CN 114963803 A CN114963803 A CN 114963803A CN 202210594298 A CN202210594298 A CN 202210594298A CN 114963803 A CN114963803 A CN 114963803A
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China
Prior art keywords
tube
pull rod
plates
heat exchange
plate
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CN202210594298.8A
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Chinese (zh)
Inventor
陈孙艺
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Challenge Petrochemical Machinery Corp
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Challenge Petrochemical Machinery Corp
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Priority to CN202210594298.8A priority Critical patent/CN114963803A/en
Publication of CN114963803A publication Critical patent/CN114963803A/en
Priority to PCT/CN2022/126341 priority patent/WO2023226288A1/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
    • F28D7/00—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
    • F28D7/16—Heat-exchange apparatus having stationary tubular conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the conduits being arranged in parallel spaced relation
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02—Header boxes; End plates
    • F28F9/04—Arrangements for sealing elements into header boxes or end plates
    • F28F9/06—Arrangements for sealing elements into header boxes or end plates by dismountable joints
    • F28F9/10—Arrangements for sealing elements into header boxes or end plates by dismountable joints by screw-type connections, e.g. gland
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/02—Header boxes; End plates
    • F28F9/04—Arrangements for sealing elements into header boxes or end plates
    • F28F9/16—Arrangements for sealing elements into header boxes or end plates by permanent joints, e.g. by rolling
    • F28F9/18—Arrangements for sealing elements into header boxes or end plates by permanent joints, e.g. by rolling by welding
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F28—HEAT EXCHANGE IN GENERAL
    • F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
    • F28F9/00—Casings; Header boxes; Auxiliary supports for elements; Auxiliary members within casings
    • F28F9/24—Arrangements for promoting turbulent flow of heat-exchange media, e.g. by plates
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/10—Process efficiency

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Fluid Mechanics (AREA)
  • Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)

Abstract

The invention relates to the technical field of shell-and-tube heat exchangers, in particular to a heat exchanger with a bidirectional pull rod assembly, which comprises a tube shell, a tube bundle and a tube box, wherein the tube bundle comprises tube plates, a plurality of inner plates (baffle plates or support plates) and a plurality of heat exchange tubes, the tube plates at the two ends of the tube shell are respectively provided with a pull rod, a left pull rod connected with the tube plate at the left end tensions the inner plates towards the left, and a right pull rod connected with the tube plate at the right end tensions the inner plates towards the right, so that the inner plates connected with the left pull rod and the right pull rod are simultaneously tensioned leftwards and rightwards, the inner plates are firmly positioned at fixed positions on the tube bundle, the integral strength and rigidity of the tube bundle are obviously improved, the impact of a medium flowing from left to right can be borne under the reinforcement of the left pull rod, the impact of the medium flowing from right to left can be borne under the reinforcement of the right pull rod, compared with the traditional unidirectional pull rod tube bundle, the inner plates and the pull rods cannot vibrate, abrade or bend and destabilize the heat exchange tubes under the impact of the medium flowing reversely, the tube bundle has simple structure, high quality and long service life.

Description

Heat exchanger with two-way pull rod assembly
Technical Field
The invention relates to the technical field of shell-and-tube heat exchangers in petrochemical equipment engineering, in particular to a heat exchanger with a bidirectional pull rod assembly, which is specially used for heat exchange of petrochemical industry, coal chemical industry, chemical fertilizer industry, air-conditioning refrigeration and electric power facilities.
Background
In the prior art, a shell-and-tube heat exchanger is the most widely used heat exchanger, and is also called a shell-and-tube heat exchanger or a shell-and-tube condenser, and is widely applied to heat exchange and condensation processes of heat exchange of liquid-liquid, vapor-vapor and vapor-liquid in the fields of chemical industry, petroleum, medicine, food, light industry, metallurgy, coking and the like, and vapor condensation, liquid evaporation and heat transfer and the like.
A common structure of a shell-and-tube heat exchanger in the prior art is shown in fig. 1 and mainly comprises a tube bundle 1, a shell 2, a tube box 3 and other main components, wherein the tube bundle 1 is a core component of the shell-and-tube heat exchanger, the tube bundle 1 usually comprises heat exchange tubes 1-1, support plates (or baffle plates) 1-2, distance tube pull rod assemblies 1-3 and tube plates 1-4, rows of the heat exchange tubes 1-1 are supported by the support plates (or baffle plates) 1-2, and two ends of the heat exchange tubes penetrate into tube holes of the tube plates and are fixedly connected with the tube plates, so that the sealing performance and the strength of a joint are ensured, and two ends of the heat exchange tubes are communicated with the tube box.
As shown in fig. 1, only one end of the tube plate of the conventional tube bundle is fixed with a pull rod, and the other end of the tube plate is not fixed with a pull rod. As the name suggests, the pull rod only has the function of bearing axial tension, and when the pull rod is under the action of axial pressure, the slender round rod is easy to bend.
On the one hand, along with the development of social economy, the petrochemical plant has larger and larger construction scale, and a strict energy efficiency constraint promotion energy-saving carbon reduction action scheme (2021 + 2025) in key industries of petrochemical industry is specially issued in the field of petrochemical industry, so that atmospheric and vacuum pressures of less than 1000 ten thousand tons/year are strictly forbidden to be newly built, ethylene is prepared by cracking naphtha of less than 80 ten thousand tons/year, and similar requirements are also provided for the lower limit of capacity of other petrochemical plants. The structural size of the newly-built heat exchanger not only breaks through the limitation that the nominal diameter does not exceed 4000mm in the GB/T151-2014 Heat exchanger standard, but also is integrated with a reactor to form an ethylene oxide reactor, a propylene oxide reactor and the like, and the treatment capacity is increased more and more. The processing capacity of an old heat exchanger of an old device is required to be operated in an overload mode sometimes, a heat exchanger tube bundle vibrates under the impact of a large-flow strong fluid medium in a shell pass, vibration impact not only produces noise to pollute the environment, but also abrades and destroys a heat exchange tube to cause internal leakage of equipment, so that the production and the quality of chemical products are influenced, and even the environment is polluted by outward leakage.
On the other hand, with the development of energy-saving and environment-friendly technology, the deep processing temperature of the petrochemical technology is higher and higher, the index of fully utilizing waste heat is stricter and stricter, and the thin tube plate is more and more common in lightweight design to replace a thick-wall large-forging-price tube plate, but the pressure bearing capacity of the thin tube plate is deficient, and the structure needs to be specially strengthened.
It is therefore of engineering interest to improve upon the problems of the prior art described above.
Disclosure of Invention
In view of the above technical problems in the prior art, the present invention provides a heat exchanger with a tie rod assembly.
In order to realize the purpose, the invention provides the following technical scheme:
the tube bundle comprises tube plates, a plurality of inner plates and a plurality of heat exchange tubes, the tube plates are fixed at two ends of the tube shell and jointly enclose a shell pass, the tube box and the tube plates are fixed and jointly enclose a tube pass, and the plurality of heat exchange tubes are parallelly positioned in the shell pass and penetrate through the tube plates to be communicated with the tube pass; the inner plates are one or both of the baffle plate and the support plate, and the inner plates are distributed along the length direction of the heat exchange tube; the tube plates at the two ends of the tube shell are respectively provided with a pull rod, the left pull rod connected with the tube plate at the left end pulls the inner plate leftwards, and the right pull rod connected with the tube plate at the right end pulls the inner plate rightwards, so that the inner plates which are connected with the left pull rod and the right pull rod are simultaneously tensioned leftwards and rightwards.
This inner panel is firmly fixed position on the tube bank, is showing the bulk strength and the rigidity that has improved the tube bank by two-way taut tube sheet and inner panel, both can bear the impact of flowing the medium from a left side to the right under the enhancement of left pull rod, also can bear the impact of flowing the medium from the right side to the left under the enhancement of right pull rod, compare with traditional one-way pull rod tube bank, the inner panel can not be under the impact of reverse flowing medium vibration wear heat exchange tube or crooked unstability, the tube bank has simple structure, high quality and long service life's characteristics.
As a further specific scheme, the connecting modes between the pull rod and each inner plate and between the pull rod and the tube plate are threaded connection, welding or a combination of the two connecting modes.
As a further specific scheme, the number of the pull rods fixed on the same tube plate is multiple, and the end parts of the pull rods are distributed along the whole circle area or the non-whole circle area of the corresponding tube plate.
As a further specific scheme, the pull rod is of a full-length whole-strip structure, or the pull rod is of a segmented combined structure.
As a further specific scheme, the cross-sectional shape and the size of the pull rod along the length direction are changed, and the cross section of the pull rod close to the tube plate is increased.
As a further specific scheme, the heat exchange tube is a straight tube bundle, and two ends of the heat exchange tube are respectively connected with tube boxes at two ends of a tube shell; or the heat exchange tube is a U-shaped tube bundle, the heat exchange tube passes through the two tube plates in a circuitous way, and the end ports of the heat exchange tube are communicated with the same tube box, so that the two straight tubes of the heat exchange tube are positioned in the same tube shell; or the heat exchange tube is a U-shaped tube bundle, and two sections of straight tubes of the heat exchange tube are positioned in different tube shells.
As a further specific scheme, all the inner plates in the inner plates are simultaneously tensioned by the left pull rod and the right pull rod.
As a further specific scheme, only part of the inner plates in the inner plates are simultaneously tensioned by the left pull rod and the right pull rod, and the rest of the inner plates are only tensioned by the left pull rod or the right pull rod.
As a further specific scheme, the thicknesses of the two tube plates positioned at the two ends of the tube shell are not equal.
As a further specific scheme, a distance tube is arranged in the pull rod in a penetrating manner; or the pull rod is a rod body without a distance tube, a distance piece is arranged in the tube shell, and two end parts of the distance piece are respectively connected with the two tube plates.
The invention has the beneficial effects that:
compared with the traditional one-way draw bar tube bundle, the heat exchanger with the two-way draw bar assembly has the following advantages:
(1) the inner plate (baffle plate or support plate) has strong vibration resistance. The same baffle or support plate is tensioned by both the left end tube sheet and the right end tube sheet, and the inner plate is securely positioned in one location on the tube bundle.
(2) The tube bundle has high overall strength and rigidity. The tube plates at the two ends of the tube bundle are connected with pull rods, the inner plates are tensioned to the left by the pull rods connected with the tube plates at the left ends, the inner plates are tensioned to the right by the pull rods connected with the tube plates at the right ends, the overall strength and rigidity of the tube bundle are obviously improved by the two-way tensioned inner plates, and the tube bundle can better keep the original structural size precision in the processes of assembling into a shell or extracting for maintenance in the process of loading, transporting, hanging and unloading.
(3) The tube bundle has wide application range and is particularly suitable for thin tube plates.
First, the flow regime is suitable for media impingement. The left pull rod and the right pull rod can bear the impact of flowing media from left to right under the reinforcement of the left pull rod, and can also bear the impact of flowing media from right to left under the reinforcement of the right pull rod, and the inner plate and the pull rod cannot vibrate to wear the heat exchange tube or bend unstably under the impact of reverse flowing media.
And secondly, the heat exchanger is structurally suitable for heat exchanger structures such as a steam generator, a waste heat boiler, a cooler and the like with a large-diameter shell, a thin tube plate and an ultra-long heat exchange tube. The two-way pull rod assembly consisting of the left pull rod and the right pull rod is equivalent to the support of the heat exchange tube to the tube plate on the support of the tube plate, so that the diameter of an imaginary circle for calculating the thickness of the tube plate in the tube plate distribution area can be obviously reduced, and the thickness of the tube plate is reduced in the same proportion according to the reduction degree of the diameter of the imaginary circle.
And thirdly, the method is technically suitable for the occasions of large shell-side flow, unstable flow state and high elasticity of gas-liquid mixed two-phase flow or airflow.
(4) The tube bundle has a high-temperature self-tightening function. When the tube pass temperature of the tube bundle is higher than the shell pass temperature, the thermal extension of the heat exchange tube is slightly longer than that of the pull rod made of the same steel, and the bidirectional pull rod is driven by the heat exchange tube to have the tendency of relative displacement towards the two ends of the tube bundle respectively, so that the effect of tensioning the baffle plate or the supporting plate is generated. Conversely, when the tube side temperature of the tube bundle is lower than the shell side temperature, the bidirectional pull rod has the effect of pushing the baffle plate or the support plate tightly.
(5) The tube bundle has high cost performance. The tube bundle can obtain good performance only by adding a plurality of pull rods which are common traditional parts, and has the characteristics of simple structure, high quality and long service life.
Drawings
The present application is further explained by means of the attached drawings, but the embodiments in the attached drawings do not constitute any limitation to the present application, and for a person skilled in the art, other drawings can be obtained from the following drawings without inventive effort.
Fig. 1 is a schematic structural diagram of a shell-and-tube heat exchanger in the prior art.
FIG. 2 is a first schematic view of a tube bundle of a heat exchanger having a tie rod assembly according to the present application.
FIG. 3 is a schematic view of a second configuration of a tube bundle of a heat exchanger having a tie rod assembly according to the present application.
FIG. 4 is a schematic view of a third configuration of a tube bundle of a heat exchanger having a tie rod assembly according to the present application.
Detailed Description
The present invention will be described in detail below with reference to specific embodiments and the accompanying drawings.
The heat exchanger with the tie rod assembly of the present embodiment includes the conventional structure: the tube bundle comprises tube plates, a plurality of inner plates and a plurality of heat exchange tubes, the tube plates are fixed at two ends of the tube bundle and jointly enclose a shell pass, the tube bundle is fixed with the tube plates and jointly encloses a tube pass, the plurality of heat exchange tubes are parallelly located in the shell pass and penetrate through the tube plates to be communicated with the tube pass, the heat exchange tubes are welded and fixed with the tube plates, and the heat exchange tubes are in clearance fit with the inner plates. The inner plates are a baffle plate and a support plate, the inner plates are distributed along the length direction of the heat exchange tube, and each inner plate is arranged along the radial direction of the tube shell or is obliquely arranged with the axis of the tube shell. The improvement of this application is:
as shown in fig. 2 to 4, the left tube plate 11 and the right tube plate 12 at the two ends of the tube shell are respectively provided with a pull rod, and the left pull rod 13 fixedly connected to the left tube plate 11 sequentially passes through and fixes the left inner plate 152, the plurality of middle inner plates 151 and the right inner plate 153, and then is screwed in the nut for locking, so that the left pull rod 13 pulls the plurality of inner plates to the left based on the left tube plate 11. Right pull rod 14 of right-hand member tube sheet 12 fixed connection passes in proper order and fixes right-hand member inner panel 153, screw in nut locking behind inner panel 151 and the left end inner panel 152 in the middle of the polylith, thereby make right pull rod 14 turn right the polylith inner panel taut based on right tube sheet 11, make the inner panel that all connects left pull rod 13 and right pull rod 14 receive the tension from left and right sides simultaneously above, this inner panel is firmly fixed position on the tube bank, the tube sheet and the inner panel that are strained by two-way have shown the bulk strength and the rigidity that have improved the tube bank, both can bear the impact of flowing medium from left to right under left pull rod 13's the enhancement, also can bear the impact of flowing medium from right to left under right pull rod 14's the enhancement, left pull rod 13 and right pull rod 14 stagger arrangement. Compared with the traditional one-way pull rod tube bundle, the inner plate can not vibrate and wear the heat exchange tube or bend and lose stability under the impact of a reverse flowing medium, and the tube bundle has the characteristics of simple structure, high quality and long service life.
The bidirectional pull rod reinforced tube bundle structure shown in fig. 2 is characterized in that tube pass fluid enters a heat exchange tube 16 from the arrow direction at the left end and leaves the tube bundle from the arrow direction at the right end after heat exchange of the heat exchange tube 16, the left end of a left pull rod 13 with distance tubes in the figure is fixed at the shell pass side of a left tube plate 11 and can bear the impact action of the shell pass fluid from left to right, and the right end of a right pull rod 14 with distance tubes is fixed at the shell pass side of a right tube plate 14 and can bear the impact action of the shell pass fluid from right to left and can bear the axial vibration of the shell pass fluid.
In practice, the connection mode between the pull rod and each inner plate of the block, the connection mode between the pull rod and the tube plate are threaded connection, welding or a combination of the two connection modes, and the combination means that part of the pull rod is in threaded connection with the inner plate, part of the pull rod is welded with the inner plate, and so on. The connection of the pull rod and the tube plate is usually in threaded connection, the connection of the pull rod with the distance tube and the inner plate (the baffle plate or the supporting plate) can be in fastening connection by end threads, and the connection of the pull rod without the distance tube and the inner plate shown in figure 3 can be in welded connection.
In practice, the number of the tie rods fixed on the same tube plate is multiple, and the end portions of the tie rods are distributed along the whole circle area or the non-whole circle area of the corresponding tube plate, depending on the tube arrangement area on the tube plate.
In actual manufacturing, the pull rod is of a full-length whole-strip structure or a segmented combined structure. The cross-sectional shape and size of the tie rods varies along the length, and the cross-section of the tie rods increases proximate the tube sheet.
Optionally, all the inner plates in the plurality of inner plates are simultaneously tensioned by the left pull rod and the right pull rod, so that the inner plates are applicable to the structure of a large-diameter thin tube plate of the shell, and each baffle plate or support plate is reinforced by the capacity of the pull rods for bearing shell-side internal pressure on the thin tube plate. In addition, only part of the inner plates in the inner plates are simultaneously tensioned by the left pull rod and the right pull rod, and the other inner plates are only tensioned by the left pull rod or the right pull rod, wherein the structure that the inner plates in the middle of the tube bundle are tensioned in two directions is particularly suitable for the conditions that the fluid outlet is arranged in the middle of the tube shell and the fluid inlets are arranged at two ends of the tube shell.
As an alternative scheme, as shown in fig. 3, the heat exchange tube 16 is a straight tube bundle, and two ends of the heat exchange tube are respectively connected to tube boxes at two ends of a tube shell; or as shown in fig. 4, the heat exchange tube 16 is a U-shaped tube bundle, and the heat exchange tube passes through two tube plates in a roundabout manner, and the port of the heat exchange tube is communicated with the same tube box, so that two straight tubes of the heat exchange tube are positioned in the same tube shell; or the heat exchange tube is a U-shaped tube bundle, and two sections of straight tubes of the heat exchange tube are positioned in different tube shells. As shown in fig. 4, the equivalent right tube plate 12 is actually equivalent to a thicker baffle plate or support plate, and the tube plate distance members 17 have sufficient strength and rigidity to allow the equivalent right tube plate 12 to serve as a foundation for the right tie rods to tighten the inner plate.
As an optional scheme, the two tube plates at the two ends of the tube shell have unequal thicknesses, so that the tube bundle belongs to a flexible thin tube plate or a bracing tube plate, the thin tube plate is suitable for the end with larger fluid temperature difference at the two sides of the tube plate, and the thick tube plate is suitable for the end with smaller fluid temperature difference at the two sides of the tube plate.
As an alternative scheme, as shown in fig. 2, a plurality of sections of distance pipes are arranged outside the pull rod in a penetrating manner, and two adjacent inner plates or the inner plates and the tube plate are fixed through the distance pipes; or as shown in fig. 3 or 4, the pull rod is a rod body without a distance tube, a distance piece 17 is arranged in the tube shell, and two end parts of the distance piece are respectively connected with the two tube plates.
Bundle feasibility analysis with tie bar assembly:
the thermal expansion extension of the heat exchange tube in the high-temperature operation of the tube bundle of the traditional one-way pull rod assembly is only restrained by the shell and cannot be restrained by the pull rod, and the heat exchange tube and the pull rod are free.
However, in the tube bundle of the present embodiment, the heat exchange tubes and the tie rods are mutually constrained, as shown in fig. 2. In the tube bundle, the temperature of the heat exchange tube is slightly higher than that of the adjacent pull rod, the thermal expansion of the heat exchange tube and the adjacent pull rod is basically coordinated, if the temperature of the heat exchange tube is much higher than that of the adjacent pull rod, the thermal expansion of the heat exchange tube is limited by the adjacent pull rod, the pull rod is not enough except for the thermal expansion elongation of the pull rod, and the thermal expansion elongation of the heat exchange tube is also prolonged, so that the reliability check is carried out on the thermal self-tightening. Meanwhile, the structural self-tightening and the thermal stress check caused by thermal expansion are two aspects of the protection design. From the technical reliability, the thermal stress of the two structures should be checked, if the thermal stress is large and the check can pass, the requirements of the two aspects are met at the same time, and if the thermal stress is large and the check cannot pass, a countermeasure for reducing the thermal stress should be taken.
1) Safety check of tie rod
After the tube bundle is assembled at the normal temperature of 20 ℃, the thermal expansion extension difference between the heat exchange tube and the adjacent pull rod at the average operating temperature is as follows:
△L＝L m -L j ＝β m ×△T m ×L－β j ×△T j ×L (1)
in the formula: delta L is the maximum thermal expansion difference in operation between the heat exchange tube with the full length of L and the pull rod, and is mm;
β m the linear expansion coefficient of the heat exchange tube at the average operating temperature is 1.324 multiplied by 10 when the rare extreme high temperature of 350 ℃ is adopted for carbon steel and chromium molybdenum steel -5 mm/(mm·℃)；
△T m The average operating temperature of the heat exchanger tube and the temperature at which it is manufactured and assembled (generally 20 ℃)Poor, 330 deg.C;
L m -maximum expansion of the heat exchange tubes, mm;
β j the linear expansion coefficient of the pull rod at the average operating temperature is 1.29 multiplied by 10 when the pull rod is set to be lower than the temperature of the heat exchange tube beside the pull rod by 20 ℃ for the high temperature of the carbon steel and the chromium molybdenum steel and the operation is carried out at 300 DEG C -5 mm/(mm·℃)；
△T j The difference between the average operating temperature of the tie-rod and the temperature at which it is manufactured and assembled (generally taken at 20 ℃), 280 ℃;
L j minimum expansion of the tie rod, mm.
The relevant values are calculated by substituting formula (1):
△L＝[1.324×10 -5 (350-20)L]－[1.29×10 -5 (300-20)L]
＝(436.92-361.2)10 -5 L
＝7.572×10 -4 L (2)
no matter how long the heat exchange tube is, the thermal strain epsilon obtained by dividing the thermal expansion difference Delta L by L is 7.572 multiplied by 10 -4 mm/mm, the compressive stress to which it is subjected to all thermal strains is:
σ y ＝εE (3)
in the formula: sigma y -the thermal strain tensile stress to which the tie rod is subjected, MPa;
ε -thermal strain, 7.57X 10 -3 mm/mm；
E-elastic modulus of the pull rod material is 1.83 multiplied by 10 when the carbon steel and the chromium molybdenum steel run at the high temperature of 300 DEG C 5 MPa; the relevant numerical values are substituted into the formula (3) to calculate:
σ y ＝7.572×10 -4 ×1.83×10 5 ＝138.6MPa (4)
since the thermal stresses are self-limiting and localized, the stresses drop immediately upon yielding, it being possible here to relax the permissible value of the carbon steel, taking
Figure BDA0003667122760000061
The tensile stress of the formula (4) is only half of the allowable stress value 270MPa of the pull rod, and the allowable value of the chromium-molybdenum steel is higher. Therefore, the elastic elongation of the pull rod can eliminate the influence of the thermal stress, the pull rod cannot be broken, and the pull rod is safe.
2) Influence of extension of the tie rod on the displacement of the cross-flow plate
The length L of the commonly used heat exchange tube is about 6000mm, and the thermal expansion elongation difference between the heat exchange tube and the adjacent pull rod is calculated by substituting formula (2):
△L＝7.572×10 -4 ×6000≈4.5mm (6)
on the one hand, the typical spacing between the baffles or support plates is 400mm, for a heat exchange tube with a length L of about 6000mm, at least five baffles or support plates are arranged to form six equal intervals, the average spacing between the baffles or support plates is 1000mm, even for a heat exchange tube with a length of 12000mm, the average spacing between the baffles or support plates will not increase, and the difference in thermal expansion elongation to be harmoniously digested between every two baffles or support plates is:
4.5/6≈0.75mm (7)
because the baffle plate or the supporting plate is uneven, the pull rod is not straight enough and gaps exist among parts when the tube bundle is assembled, the tiny thermal expansion extension difference is easily coordinated and digested by displacement within the range of 1000mm of each interval, and the phenomenon that the baffle plate or the supporting plate is pulled by the pull rod distance tube to be distorted and deformed can not occur.
On the other hand, as a result of the calculation and check of equation (4), it is found that the influence of the thermal displacement can be coordinated with the elastic extension of the tie rod, and the tie rod is not broken, and in short, the baffle plate or the support plate is not distorted by the tie rod spacer.
3) Control of the difference in thermal expansion elongation between the heat exchange tube and its adjacent tie rod
Firstly, the objective existence of the thermal expansion extension difference between the heat exchange tube and the adjacent pull rod under the operation state is fully utilized to achieve the main purpose of fastening the integral structure of the tube bundle, and secondly, the harmfulness when the thermal expansion extension difference is overlarge is controlled through calculation and check.
If the thermal expansion extension difference between the heat exchange tube and the adjacent pull rod is large, the pull rod can be made of a material with a linear thermal expansion coefficient larger than that of the heat exchange tube so as to reduce the thermal expansion extension difference.
Structurally, countermeasures can be taken, such as elimination of a distance tube and adoption of a pull rod only, the pull rod is enabled to be in contact with a shell side medium more directly, heat is absorbed from medium heat transfer and radiation of an adjacent heat exchange tube, the temperature is increased, and the thermal expansion elongation difference is also reduced.
An elastic washer can be additionally arranged between the fastening nut at the end part of the pull rod and the baffle plate or the supporting plate, and the deformation of the elastic washer is used for coordinating the thermal expansion elongation difference of digestion.
4) Strategy for controlling the average temperature difference between a heat exchange tube and its adjacent tie rod
Based on the principle of the formula (2), the strategy for reducing the action of the heat exchange tube thermal expansion tensile stress on the pull rod can control the thermal expansion elongation difference between the heat exchange tube and the adjacent pull rod, and also can control the average temperature difference between the heat exchange tube and the adjacent pull rod. Specifically, on the basis of the stress allowable value of the formula (5), the stress calculation value of the formula (4) is reversely deduced, then the strain calculation value of the formula (3) is reversely deduced, and finally the temperature difference calculation value of the formula (2) is reversely deduced, so that the temperature difference is controlled by adjusting the flow rate, the flow velocity or the structure of the tube bundle and the heat exchange tube.
In general, the bi-directional pull rod has significant advantages, little or no harmful effects under the general petrochemical process.
During actual manufacturing, for the fixed tube-plate heat exchanger, the tube bundle which is assembled in the figures 2 and 3 and is qualified in inspection is conveyed into the tube shell from one end, the diameter of the excircle of the tube plate at the right end of the tube bundle is slightly smaller than that of the excircle at the left end of the tube bundle, and the excircle of the tube plate at the right end of the tube bundle is welded with the tube shell to form a sealed shell pass after the other end of the tube shell is exposed; for the floating head type heat exchanger, the floating head cover can be assembled on the excircle of the tube plate at the right end.
For the U-shaped tube bundle heat exchanger, the tube bundle which is assembled and qualified in inspection is conveyed into the heat exchanger shell by one end of the U-shaped section at the right end of the tube bundle.
In the description of the present invention, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral part; can be mechanically or electrically connected; either directly or indirectly through intervening media, either internally or in any other relationship. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The standard parts used in the invention can be purchased from the market, the special-shaped parts can be customized according to the description of the specification and the accompanying drawings, the specific connection mode of each part adopts conventional means such as bolts, rivets, welding and the like mature in the prior art, the machines, the parts and equipment adopt conventional models in the prior art, and the circuit connection adopts the conventional connection mode in the prior art, so that the detailed description is omitted.
Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes, modifications, substitutions and alterations can be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the protection scope of the present invention, although the present invention is described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that modifications or equivalent substitutions can be made on the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims (10)

1. A heat exchanger with a two-way pull rod assembly comprises a tube shell, a tube bundle and a tube box, wherein the tube bundle comprises tube plates, a plurality of inner plates and a plurality of heat exchange tubes, the tube plates are fixed at two ends of the tube shell and jointly enclose a shell pass, the tube box and the tube plates are fixed and jointly enclose a tube pass, and the plurality of heat exchange tubes are parallelly positioned in the shell pass and penetrate through the tube plates to be communicated with the tube pass; the inner plates are one or both of the baffle plate and the support plate, and the inner plates are distributed along the length direction of the heat exchange tube; the method is characterized in that:
the tube plates at the two ends of the tube shell are respectively provided with a pull rod, the left pull rod connected with the tube plate at the left end pulls the inner plate leftwards, and the right pull rod connected with the tube plate at the right end pulls the inner plate rightwards, so that the inner plates which are connected with the left pull rod and the right pull rod are simultaneously tensioned leftwards and rightwards.
2. The heat exchanger with the tie rod assembly of claim 1, wherein: the connecting modes between the pull rod and each inner plate and between the pull rod and the tube plate are threaded connection, welding or the combination of the two connecting modes.
3. The heat exchanger with the tie rod assembly of claim 1, wherein: the number of the pull rods fixed on the same tube plate is multiple, and the end parts of the pull rods are distributed along the whole circle area or the non-whole circle area of the corresponding tube plate.
4. The heat exchanger with the tie rod assembly of claim 1, wherein: the pull rod is of a full-length whole-strip structure, or the pull rod is of a segmented combined structure.
5. The heat exchanger with the tie rod assembly of claim 1, wherein: the cross-sectional shape and size of the tie rods varies along the length, and the cross-section of the tie rods increases proximate the tube sheet.
6. The heat exchanger with the tie rod assembly of claim 1, wherein: the heat exchange tube is a straight tube bundle, and two ends of the heat exchange tube are respectively connected with tube boxes at two ends of the tube shell; or the heat exchange tube is a U-shaped tube bundle, the heat exchange tube passes through the two tube plates in a circuitous way, and the end ports of the heat exchange tube are communicated with the same tube box, so that the two straight tubes of the heat exchange tube are positioned in the same tube shell; or the heat exchange tube is a U-shaped tube bundle, and two sections of straight tubes of the heat exchange tube are positioned in different tube shells.
7. The heat exchanger with the tie rod assembly of claim 1, wherein: in the inner plates, all the inner plates are simultaneously tensioned by the left pull rod and the right pull rod.
8. The heat exchanger with the tie rod assembly of claim 1, wherein: in the inner plates, only part of the inner plates are simultaneously tensioned by the left pull rod and the right pull rod, and the rest of the inner plates are only tensioned by the left pull rod or the right pull rod.
9. The heat exchanger with the tie rod assembly of claim 1, wherein: the thicknesses of the two tube plates at the two ends of the tube shell are not equal.
10. The heat exchanger with the tie rod assembly of claim 1, wherein: a distance tube is arranged in the pull rod in a penetrating way; or the pull rod is a rod body without a distance tube, a distance piece is arranged in the tube shell, and two end parts of the distance piece are respectively connected with the two tube plates.
CN202210594298.8A 2022-05-27 2022-05-27 Heat exchanger with two-way pull rod assembly Pending CN114963803A (en)

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CN202210594298.8A CN114963803A (en) 2022-05-27 2022-05-27 Heat exchanger with two-way pull rod assembly
PCT/CN2022/126341 WO2023226288A1 (en) 2022-05-27 2022-10-20 Heat exchanger with bidirectional pull rod assembly

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ITUB20150576A1 (en) * 2015-04-24 2016-10-24 Hexsol Italy Srl HEAT EXCHANGER WITH BUNDLE TUBE AND IMPROVED STRUCTURE
CN205940231U (en) * 2016-08-26 2017-02-08 沈阳鼓风机集团压力容器有限公司 Two shell side bouble -bow baffling board shell and tube type heat exchanger
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Publication number Priority date Publication date Assignee Title
WO2023226288A1 (en) * 2022-05-27 2023-11-30 茂名重力石化装备股份公司 Heat exchanger with bidirectional pull rod assembly

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