RU2238501C1 - Shell-and-tube heat exchanger and method for its assembly - Google Patents

Abstract

FIELD: applicable for manufacture of heat exchangers, mainly for internal combustion engines of transport facilities.

SUBSTANCE: the shell-and-tube heat exchanger has a shell positioned in which is a bank of heat-exchange tubes with cooling ribs fastened by the ends of the tubes in the through holes of the tube plates, the ends of the tubes project outside the limits of the tube plate, and the interplate space is divided by transversal partitions forming the refrigerated cube with inlet and outlet connections of the intertube medium, and the intratube medium feed and discharge connections connected to the shell flanges on both sides of the heat exchanger, one of the tube plates is fixed between the shell flange and the header, and the other is positioned hermetically inside the shell for longitudinal motion at temperature variations of the bank length of the heat-exchange tubes, mounted by the terminal parts of the tubes in the through holes of the tube plates by mandrelling, the through holes in the tube plates are step-shaped, at least on the side of the end of the heat-shaped, at least on the side of the end of the heat-exchange tube, besides, the length of connection of the heat-exchange tube to the tube plate is selected from conduction 0,5d_hole<T<2,0d_hole , where T- the length of connection of the heat-exchange tube to the tube plate, d_hole - the diameter of the through hole of the tube plate. The method for assembly of the shell-and-tube heat exchanger consists in sealing of the terminal parts of the heat-exchange tubes in the through holes of the tube plates, to this end, the tube ends are driven through the tube plate through the through holes of the walls and sealed in the through holes by mandrelling, after which the flexible material of the wall of the through hole squeezes the outside and inside diameters of the heat-exchange tube at the length of engagement with the tube plate by the value of flexible expansion of the through hole, caused by mandrelling of the plastic terminal part of the heat-exchange tube at longitudinal motion of the cylindrical mandrel relative to the tube plate, the through holes in the tube plates are worked with the wall roughness within 6.3 to 25mkμ, and mandrelling of the terminal parts of the heat-exchange tube in the through holes of the tube plates is conducted up to the increase of the outside diameter of the terminal part of the tube to a dimension at least exceeding the diameter of the through hole to the depth of the roughness at a longitudinal motion of the mandrel maximum diameter over a length equal to the thickness of the tube plate.

EFFECT: enhanced reliability of connection of tubes to the tube plate, reduced force of mandrelling during assembly of the heat exchanger.

Description

The invention relates to the field of heat transfer and can be used in the manufacture of heat exchangers mainly for internal combustion engines of vehicles.

Known heat exchanger containing a casing in which are placed fixed in the tube sheets of the heat exchanger tubes, equipped with expansion joints temperature expansion. Heat-exchange pipes are made of integral autonomous pipe sections installed with a gap, having inner cylindrical grooves at the free ends, and the compensator is made in the form of a pair of spring rings inserted into each other with diametrically opposite longitudinal sections. (Aut. St. USSR No. 1562656 A1. Shell-and-tube heat exchanger. - MKI 5: F 28 D 7/16, Bull. No. 17, 05/07/1990). A disadvantage of the known heat exchanger is the low reliability and adaptability of the design.

Known heat exchanger containing a casing in which a bundle of heat exchange tubes with cooling fins is placed, fixed by the ends of the tubes in the through holes of the tube plates, the ends of the tubes protruding beyond the boards. The annulus is divided by transverse partitions forming a cooling circuit with nozzles for supplying and discharging the annulus. On the flanges of the casing on both sides of the heat exchanger are connected manifolds for supplying and discharging the in-pipe medium (Aut. St. USSR No. 1632729 A1. A method of manufacturing a shell-and-tube heat exchanger - MKI 5: V 23 P 15/26, Bull. No. 9, 03.03.1991) . This heat exchanger is taken as a prototype.

A disadvantage of the known heat exchanger, taken as a prototype, is the complexity of its assembly, because the external contour of the transverse partitions is formed by sintering on the tubes of ferromagnetic particles between themselves, forming a monolithic partition between the tubes, the external contour of which requires additional processing to the size of the casing directly on the tube bundle, which has low structural rigidity, as well as the absence of longitudinal fixation of the tube plates in the heat exchanger casing.

A known method of assembling a shell-and-tube heat exchanger, comprising sealing the end parts of the heat exchange tubes in the through holes of the tube sheets. To do this, the ends of the tubes are inserted into the through holes of the tube sheet with high wall strength. Then, the ends of the tubes in the through holes are sealed with a mandrel, in which the elastic material of the hole wall compresses the outer and inner diameters of the tube along the length of contact with the tube sheet due to the elastic expansion of the hole through the mandrel of the plastic end portion of the heat exchange tube during longitudinal movement of the cylindrical mandrel relative to the tube sheet. (US patent No. 4,456,059. Tubular heat exchanger and method of assembly. MKI 5: F 28 F 9/04, Bull. No. 415.029, 06/26/1984). This method is adopted as a prototype.

The disadvantages of the method adopted for the prototype are the technological complexity of the assembly, requiring large efforts of burning out, and the insufficient density of the connection of the tube with the tube sheet due to the non-optimal ratio of the parameters of the mating parts and modes of burning.

The main task, which is claimed by the claimed shell-and-tube heat exchanger and method of assembly, is to increase the reliability of the connection of the tubes with the tube sheet and to reduce the burning force during assembly of the heat exchanger.

A single technical result achieved in the implementation of the claimed group of inventions is to reduce the cost and increase the operational reliability of the shell-and-tube heat exchanger.

The specified technical result is achieved by the fact that in a known heat exchanger containing a casing in which a bundle of heat exchange tubes with cooling fins is located, fixed by the ends of the tubes in the through holes of the tube sheets, the ends of the tubes protruding outside the grate, and the annular space is divided by transverse partitions forming a cooling a circuit with nozzles for supplying and removing the annular medium, and manifolds for supplying and removing the in-pipe medium, connected to the flanges of the casing on both sides of the heat exchange nnik, according to the proposed technical solution:

one of the tube sheets is pinched between the flange of the casing and the collector, and the other is placed hermetically inside the case with the possibility of longitudinal movement with temperature changes in the length of the bundle of heat transfer tubes mounted by the end parts of the tubes into the through holes of the tube sheets by mandrels;

the connection length of the heat exchange tube with the tube sheet is at least more than half, but less than two diameters of the through hole of the tube sheet;

the through holes in the tube sheets are chamfered, at least from the side of the end of the heat exchange tube, with a size in the range 0.1 ... 0.2 of the diameter of the through hole;

through holes in the tube sheets are stepped, at least from the end of the heat exchange tube;

tube sheets are made of steel, and heat transfer tubes are made of brass;

the tube sheets and heat transfer tubes are made of aluminum alloy, while the tube sheets are hardened, and the heat transfer tubes are tempered, at least their ends are longer than the thickness of the tube sheet.

The specified technical result is achieved by the fact that in the known method of assembling a shell-and-tube heat exchanger, comprising sealing the end parts of the heat-exchange tubes in the through holes of the tube sheets, for which the ends of the tubes are passed through the tube through the through holes with high wall strength and are sealed in the through holes of the tube sheets by burning, after which the elastic material of the wall of the through hole compresses the outer and inner diameters of the heat exchange tube along the length of contact with the tube sheet minutes the amount of elastic expansion of the through hole caused by burnishing plastic end portion of the heat exchange tube with longitudinal displacement of the cylindrical mandrel relative to the tube sheet, according to the proposed technical solution:

the through holes in the tube sheets are treated with a wall roughness in the range R _z = 6.3 ... 25.0 μm, and the end parts of the heat exchange tubes in the through holes of the tube sheets are burned until the outer diameter of the tube end portion is increased to a size of at least , exceeding the diameter of the through hole to the depth of roughness, with longitudinal movement of the largest diameter of the mandrel at a length equal to the thickness of the tube sheet;

the through holes in the tube sheets are made with a diameter greater than the outer diameter of the heat exchanger tube by the total tolerance consisting of the sum of the tolerances for the outer diameter and wall thickness of the heat transfer tube and the diameter of the through hole in the tube sheet;

the end parts of the heat exchange tubes in the through holes of the tube sheets are burned in several consecutive transitions, while the diameter of the mandrel for the first transition is taken to be larger than the internal diameter of the heat transfer tube equal to the total tolerance, and the diameters of the mandrels for other transitions are increased by each subsequent transition by a value of at least not more than half the wall thickness of the heat transfer tube;

the crown of the mandrel is performed with a taper within 3 ... 9 °;

the through holes in the tube sheets are conical with a diameter difference at the levels of the surfaces of the tube sheet of not more than the total tolerance, with a smaller diameter on the surface of the tube sheet with the end of the heat exchange tube;

in the through holes of the tube sheets, annular or helical grooves are made in the form of, for example, a fine module thread.

The analysis of the prior art by the applicant made it possible to establish that there are no analogues that are characterized by sets of features identical to all the features of the declared shell-and-tube heat exchanger. Therefore, each of the claimed technical solutions meets the condition of patentability “novelty”.

The search results for known solutions in the art in order to identify features that match the distinctive features of the prototypes of each of the proposed technical solutions have shown that they do not follow explicitly from the prior art. From the prior art determined by the applicant, the influence of the transformations provided for by the essential features of each of the claimed technical solutions on the achievement of the specified technical result has not been revealed. Therefore, each of the claimed technical solutions meets the condition of patentability “inventive step”.

In the present application for the grant of a patent, the requirement of the unity of the invention is met, since the shell-and-tube heat exchanger and the method of its assembly solve the same problem — ensuring reliable connection of the tubes to the tube sheet at low costs for the assembly of the heat exchanger.

Figure 1 shows a heat exchanger, a General view; figure 2 is a section aa in figure 1; figure 3 - diagram of the installation of the tube into the hole with chamfers on the tube sheet; figure 4 - stepwise execution of the holes in the tube sheet; figure 5 - diagram of the installation of the tube in the conical hole of the tube sheet; figure 6 - mandrel, General view; in Fig.7 - the first transition of burnishing; on Fig - the second transition of burnishing; figure 9 - connection of tubes with a tube plate; figure 10 is a diagram of the installation of tubes in the holes of tube boards with annular grooves; figure 11 is a third transition burnishing.

The heat exchanger consists of a casing 1, in which a bundle of heat exchange tubes 2 with cooling fins 3 is placed, fixed by the ends of the tubes 2 in the tube sheets 4 and 5 (Fig. 1). The annular space is divided by transverse partitions 6, forming a cooling circuit with the nozzles of the supply 7 and the outlet 8 of the annular medium. The tube sheet 4 is pinched between the flange 9 and the inlet pipe manifold 10 by means of gaskets 11, and the tube sheet 5 is sealed inside the casing 1 using rubber rings 12. The in-pipe medium collector 13 is connected to the flange 14 of the casing 1. The end parts of the heat exchange tubes 2 are mounted in the through holes 15 of the tube sheets 4 and 5 by a mandrel (FIG. 2). Openings 15 in tube plates 4 and 5 are made with chamfers 16, the height h of which is selected from the conditions _{of holes} 0,1d <h <0.2 d _{of holes} (3). The holes 15 can be made stepped (figure 4). The length of the heat exchange tubes T compounds 2 to tube sheets 4 and 5 is chosen from the condition 0,5d _holes <T <2,0d _holes.

The Assembly of the heat exchanger according to the claimed method is as follows.

The tubesheets 4 and 5, openings 15 operate diameter d _{of holes} = d _tr + Σδ, where d _tr - the outer diameter of the heat exchange tubes 2, Σδ - value cumulative tolerance: Σδ = δ _mp + δ _holes + δ _t, consisting of the sum of tolerances an outer tube diameter d _tr - δ _Tp on the hole diameter d _{of holes} in the tubesheet - δ _holes and the thickness of the tube wall t - δ _t The openings 15 operate with a roughness in the range R _z = 6,3 ... 25,0 microns which makes it possible to fill the microreliefs 17 of the roughnesses of the surfaces of the holes 15 in the tube sheets 4 and 5 when drilling the plastic metal of the tubes 2; holes 15 in t ubnyh lattices allowed to perform within Σδ cone with the smaller diameter d hole _1otv equal to d _tr, on the surface of the tube sheet with the heat exchanging tube end 2 (Figure 5). The package of cooling ribs 3 and the transverse partitions 6 are assembled with tubes 2, which are installed with a beam in the holes 15 of the tube sheets 4 and 5. Installation of the ends of the tubes 2 in the tube sheets 4 and 5 is performed by mandrels in three transitions using mandrel 17 (Fig.6) . At the first transition, the diameter d _{1 of the} mandrel 17 is chosen equal (Fig. 7):

d ₁ = (d _tr + Σδ) -2t,

where t is the tube wall thickness. Moreover, the angle α of the crown 18 of the mandrel 17 at a length B is made in the range of 3-9 °, which creates a large radial force and requires little effort along the axis of its movement during burning. The first transition of the mandrel selects the gap between the diameters of the tubes 2 and the holes 15 and presses the outer surface of the end part of the tube 2 to the surface of the hole 15 in the tube sheet. For the second transition burnishing diameter d ₂ mandrel 17 is chosen equal (Fig):

d ₂ = (d _tr + Σδ) -0.5t.

The angle α of the crown cone of the mandrel 17 also perform in the range of 3-9 °. When performing the second transition, the surface of the end part of the tube 2 is finally pressed into the surface of the hole 15 of the tube sheet at the height of macro and microroughness obtained due to the surface roughness in the hole 15 (Fig. 9). The same effect is obtained when performing the surface of the holes 15 with annular or helical grooves, for example, in the form of a fine module thread (Fig. 10). The third, final transition of the burnishing is carried out by the mandrel 17, the diameter d _{ok of} which is determined by the following formula:

d _ok = (d ₂ + Σδ) -0.5t.

The third transition creates an additional seal between the surface of the end of the tube 2 and the surface of the hole 15 in the tube sheets with the occurrence of diffusion between them (Fig. 11). In this case, the elastic material of the tube sheet through the through hole 15 compresses the outer and inner diameters of the heat transfer tube 2 by the amount of elastic expansion of the through hole 15 caused by the force from the burning of the plastic end part of the heat transfer tube 2, which is pressed into the roughness of the solid surface of the hole 15 of the tube sheet, providing reliable connection among themselves. At the same time, the tube 2 expands in the area of the chamfers 16 or the steps of the hole 15 due to the permanent deformation of the tube 2 after the final burnishing, in which the ends of the tubes can protrude by the value L or sink at the level of the surface of the tube sheet, which creates a reliable connection between the tube and the tube sheet. Reliability of the connection is improved when manufacturing a tube sheet from steel, and a heat transfer tube from brass, or during the manufacture of a tube sheet and tubes from aluminum alloys, while the tube is subjected to high tempering before installation, and the tube sheet is quenched. After burning, the bundle of tubes 2 connected to the tube sheets is inserted into the tube sheet 5 with rubber rings 12 in the casing 1 of the heat exchanger. The tube sheet 4 is fixed between the flange 9 and the inlet pipe manifold 10 by means of gaskets 11. The inlet pipe outlet manifold 13 is connected to the flange 14 of the casing 1. This design of the heat exchanger allows the heat exchanger to be disassembled and cleaned, for example, cooling fins 3 of the heat exchange tubes 2 .

The heat exchanger operates as follows.

The in-tube space medium is supplied to the manifold 10, flows through the heat exchange tubes 2, exchanging heat with the annulus, and then through the collector 13 is removed from the heat exchanger. The annular space medium enters through the pipe 7, and then, enveloping the transverse partitions 6, flows along the cooling circuit between the pipes 2, enters the pipe 8. The temperature expansion of the pipes 2 is compensated by the displacement of the pipe lattice 5 in the casing 1 to ensure tightness with the rubber rings 12. During operation heat exchanger in the design of the internal combustion engine, the selected length T of the connection of the heat exchange tubes 2 with the tube sheets 4 and 5 in combination with the mandrel allows to perceive thermal, vibrational and shock loads, both axial and radial, while maintaining the strength of their connection.

The proposed method of assembling a heat exchanger allows, due to optimization of the parameters of the elements of the mating parts before assembly and durning conditions, to obtain a reliable connection of the heat exchange tubes to the tube sheet when the tube is pressed into the surface of the holes in the tube boards in several transitions, forming macro-and microroughnesses of the hole in the tube material and connecting materials at the molecular level. The small axial force does not push the tubes out of the openings of the tube sheets and allows the entire beam bundle to be burned at the same time. This connection of the tube with the tube sheet withstands a long time of exposure to radial and axial forces, has a high vibrational strength and perceives thermal load.

For the proposed shell-and-tube heat exchanger and the method of its assembly, technical documentation has been developed, prototypes have been manufactured and tested.

Claims (9)

1. Shell-and-tube heat exchanger containing a casing in which a bundle of heat-exchange tubes with cooling fins is placed, fixed by the ends of the tubes in the through holes of the tube sheets, the ends of the tubes protruding outside the grate, and the annular space is divided by transverse partitions forming a cooling circuit with inlet and outlet pipes annular medium, and manifolds for supplying and discharging the internal annular medium connected to the flanges of the casing on both sides of the heat exchanger, characterized in that one of the pipe sieve to is pinched between the casing flange and the collector, and the other is sealed inside the casing with the possibility of longitudinal movement with temperature changes in the length of the bundle of heat transfer tubes mounted by the end parts of the tubes into the through holes of the tube sheets by mandrels, and the through holes in the tube sheets are made stepwise, at least end side of the heat exchange tube further connection length of the heat exchange tubes with the tube sheet selected from the conditions _{of holes} 0,5d <T <2,0d _holes where T - length connected Ia exchanger tube with tubesheet, d _{of holes} - hole diameter of the through tubesheet. 2. Shell and tube heat exchanger according to claim 1, characterized in that the through openings in the tubesheets operate with chamfers, the chamfers being chosen height from the condition 0,1d _holes <h <0,2d _holes, where h - height of the chamfers, d _holes - diameter through holes. 3. Shell and tube heat exchanger according to claim 1, characterized in that the tube sheets are made of steel, and the heat transfer tubes are made of brass. 4. The shell-and-tube heat exchanger according to claim 1, characterized in that the tube sheets and heat transfer tubes are made of aluminum alloy, the tube sheets are hardened and the heat transfer tubes are tempered at least for a length greater than the thickness of the tube sheet. 5. A method of assembling a shell-and-tube heat exchanger, comprising sealing the end parts of the heat exchange tubes in the through holes of the tube sheets, for which the ends of the tubes are passed through the tube through the through holes of the walls and close the holes through the holes with an elastic, after which the elastic material of the wall of the through hole compresses the outer and inner diameters heat transfer tube at the length of contact with the tube sheet by the amount of elastic expansion of the through hole caused by the burning of the plastic end h parts of the heat transfer tube during longitudinal movement of the cylindrical mandrel relative to the tube sheet, characterized in that the through holes in the tube sheets are processed with a wall roughness ranging from 6.3 to 25.0 μm, and the end parts of the heat exchange tubes in the through holes of the tube sheets are burned up to increasing the outer diameter of the end of the tube to a size at least greater than the diameter of the through hole to the depth of roughness, with longitudinal movement of the largest diameter of the mandrel by Line equal to the thickness of the tube sheet. 6. The method according to claim 5, characterized in that the through holes in the tube sheets are made with a diameter greater than the outer diameter of the heat exchange tube by the total tolerance consisting of the sum of the tolerances for the outer diameter and wall thickness of the heat transfer tube and the diameter of the through hole in the tube . 7. The method according to any one of claims 5 or 6, characterized in that the end parts of the heat exchange tubes are burned in the through holes of the tube sheets in several consecutive transitions, while the diameter of the mandrel for taking the first transition is taken to be larger than the internal diameter of the heat transfer tube by an amount equal to the total tolerance, and the diameters of the mandrels to perform other transitions increase with each subsequent transition by at least no more than half the wall thickness of the heat transfer tube. 8. The method according to claim 5, characterized in that the through holes in the tube sheets are conical with a diameter difference at the surface levels of the tube sheet of not more than the total tolerance. 9. The method according to any one of paragraphs.5, 6 and 8, characterized in that in the through holes of the tube sheets an annular or helical grooves are made in the form, for example, of a fine module thread.

Images