Heat exchange tube, heat exchanger and heat exchange method

Abstract

The application provides a heat exchange tube, a heat exchanger and a heat exchange method. The heat exchange tube comprises a first hollow tube and a second hollow tube, the first hollow tube comprises an open first end and a second end, the second hollow tube comprises an open end and a closed end, the ratio of the length of the second hollow tube cross section along the long axis direction to the width along the short axis direction is greater than 5:1, the first hollow tube is embedded in the second hollow tube, and a gap is formed between the first hollow tube and the second hollow tube, the first end of the first hollow tube extends out of the open end of the second hollow tube, and the second end of the first hollow tube is spaced apart from the inner wall of the closed end of the second hollow tube. The first end of the first hollow tube, the hollow interior, the second end, the gap between the first hollow tube and the second hollow tube and the open end of the second hollow tube define a fluid passage. The heat exchange tube, the heat exchanger and the heat exchange method according to the application can improve the heat exchange efficiency while avoiding deformation and damage caused by thermal expansion during the heat exchange process.

Description

TECHNICAL FIELD

[0001] The present application relates to an improved heat exchange tube with improved heat exchange efficiency, and more particularly to a heat exchange tube for flue gas waste heat recovery of a heating furnace in petrochemical, power and other industries. The present application also relates to a heat exchanger and a heat exchange method using the heat exchange tube. BACKGROUND

[0002] Gas-gas heat exchangers are widely used in petroleum, chemical, metallurgical, power, mechanical and other industries. Heat exchange between high and low temperature gases is achieved through the heat exchanger, so as to heat the low temperature gas or cool the high temperature gas.

[0003] The shell-and-tube heat exchanger is the most widely used type of gas-gas heat exchanger. In the shell-and-tube heat exchanger, the low temperature gas flows in the tube, and the high temperature gas flows outside the tube. During the heat exchange process, both the heat exchange tube and the shell will expand. In order to solve the difference in thermal expansion between the heat exchange tube and the shell, and to avoid the problem of weld cracking caused by the different expansion amounts of the two, an expansion joint is generally provided between the shell and the tube sheet (sealing plate), and the heat exchange tube is directly welded to the two end tube sheets. However, in the high temperature section of the gas-gas heat exchanger, due to the high temperature of the gas, the thermal expansion amount is large. Even if an expansion joint is provided on the shell, when the flow direction or flow rate of the cold and hot media is uneven, it is difficult to ensure that the wall temperature of each heat exchange tube is the same, thereby causing a difference in expansion amount between the heat exchange tubes, which causes a large non-uniform expansion stress between the heat exchange tube and the tube sheet. This stress can cause the tube sheet to twist and deform, and even cause the weld between the two to crack, resulting in flue gas leakage and cross contamination, reduced heat exchange efficiency, and in severe cases, equipment damage and shutdown.

[0004] Therefore, it is of great significance to develop a new type of heat exchange tube that can solve the problem of twisting and deformation of the heat exchange tube (sealing plate) caused by the difference in expansion amount of the heat exchange tube, as well as a gas-gas heat exchanger and a heat exchange method using the same. SUMMARY

[0005] The present application aims to provide an improved heat exchange tube, as well as a gas-gas heat exchanger and a heat exchange method using the same, to solve the above problems.

[0006] According to a first aspect of the present application, there is provided a heat exchange tube comprising a first hollow tube and a second hollow tube, the first hollow tube comprising an open first end and a second end, the second hollow tube comprising an open end and a closed end, the second hollow tube having a cross-sectional shape defining a major axis and a minor axis, a ratio of a length along the major axis to a width along the minor axis being greater than 5:1, wherein the first hollow tube is nested in the second hollow tube, a gap is formed between an outer wall of the first hollow tube and an inner wall of the second hollow tube, and the first end of the first hollow tube extends beyond the open end of the second hollow tube, the second end of the first hollow tube is spaced apart from the inner wall of the closed end of the second hollow tube, the first end of the first hollow tube, a hollow interior of the first hollow tube, the second end, the gap between the first hollow tube and the second hollow tube, and the open end of the second hollow tube define a fluid passage.

[0007] The heat exchange tube according to the present application adopts the second hollow tube structure with a ratio of a length along the major axis to a width along the minor axis being greater than 5:1, and has a larger heat exchange area, and at the same time, since the heat exchange tube form is adopted that the first hollow tube is nested in the second hollow tube, not only the heat exchange between the heat exchange medium in the gap between the inner wall of the second hollow tube and the outer wall of the first hollow tube and the heat exchange medium outside the second hollow tube exists, but also the heat exchange between the heat exchange medium in the interior of the first hollow tube and the heat exchange medium in the gap between the inner wall of the second hollow tube and the outer wall of the first hollow tube exists, and the heat exchange efficiency is improved.

[0008] Preferably, at least part of the outer wall of the first hollow tube abuts against the inner wall of the second hollow tube to form the gap between the outer wall of the first hollow tube and the inner wall of the second hollow tube, and to avoid the first hollow tube from shaking relative to the second hollow tube.

[0009] The first hollow tube and the second hollow tube are floatingly held by the cooperation of the cross-sectional shapes of the first hollow tube and the second hollow tube, and the first hollow tube is avoided from shaking relative to the second hollow tube, wherein the cross-sectional shape of the first hollow tube can be any shape, including oblong or circular.

[0010] Preferably, the cross-sectional shape of the first hollow tube defines a major axis and a minor axis, a ratio of a length along the major axis to a width along the minor axis being greater than 5:1, the major axis coincides with the major axis of the cross-section of the second hollow tube, and part of the outer wall of the end portion along the major axis of the first hollow tube abuts against part of the inner wall of the end portion along the major axis of the second hollow tube.

[0011] The cross-sectional shape of the first hollow tube can be an oblong shape coinciding with the major axis of the cross-section of the second hollow tube, and the floating holding of each other is achieved by part of the outer wall of the end portion along the major axis abutting against part of the inner wall of the end portion along the major axis of the second hollow tube.

[0012] Preferably, the outer wall of the first hollow tube is supported on the inner wall of the second hollow tube by a mechanical spacer to form a gap between the outer wall of the first hollow tube and the inner wall of the second hollow tube and to avoid the first hollow tube from shaking relative to the second hollow tube.

[0013] In the present application, in addition to the floating retention of the first hollow tube and the second hollow tube by the cross-sectional shape cooperation, a mechanical spacer can also be used to floatingly retain the first hollow tube and the second hollow tube relative to each other.

[0014] Preferably, the mechanical spacer is a stud passing through the tube wall of the first hollow tube and retained by a nut mounted on the outer wall of the first hollow tube, the end of the stud abutting against the inner wall of the long axis side of the second hollow tube.

[0015] Preferably, a plurality of openings are uniformly arranged on the tube wall of the second end of the first hollow tube on the long axis side to reduce the resistance of the diverted flow of the first gaseous heat exchange medium.

[0016] According to a second aspect of the present application, a heat exchanger is provided, comprising:

[0017] a housing, the housing being provided with an inlet and an outlet for the first gaseous heat exchange medium and an inlet and an outlet for the second gaseous heat exchange medium;

[0018] a plurality of heat exchange tubes as described above arranged in the housing, the fluid passage at least partially defining a first gaseous heat exchange medium flow channel for receiving the first gaseous heat exchange medium;

[0019] a first sealing plate and a second sealing plate mounted on the housing, the first sealing plate and the second sealing plate being respectively provided with a plurality of through holes for the first hollow tube and the second hollow tube, the first end of the first hollow tube of the heat exchange tube being sealingly mounted on the first sealing plate through the through hole on the first sealing plate, and the open end of the second hollow tube being sealingly mounted on the second sealing plate through the through hole on the second sealing plate,

[0020] the heat exchanger further comprising a second gaseous heat exchange medium flow channel arranged in the housing and separated from the first gaseous heat exchange medium flow channel for receiving the second gaseous heat exchange medium,

[0021] the first gaseous heat exchange medium flow channel being defined by the inlet for the first gaseous heat exchange medium provided on the housing, the first end of the first hollow tube, the hollow interior of the first hollow tube, the second end of the first hollow tube, the gap between the first hollow tube and the second hollow tube, the space enclosed by the first sealing plate, the second sealing plate and the housing, and the outlet for the first gaseous heat exchange medium provided on the housing, the tube wall of the second hollow tube of the heat exchange tube extending in the second gaseous heat exchange medium flow channel to achieve heat exchange between the first gaseous heat exchange medium and the second gaseous heat exchange medium.

[0022] The heat exchanger according to the present application adopts the heat exchange tube as described above, and by sealing and fixing only one end of the first hollow tube and one end of the second hollow tube in the heat exchange tube to the corresponding sealing plate, the other end of the first hollow tube and the other end of the second hollow tube can freely extend in the axial direction when thermal expansion, so that the thermal expansion stress and deformation caused by the difference in thermal expansion of the heat exchange tube due to uneven temperature during the heat exchange process are avoided, and thus the thermal expansion stress in the corresponding components in the heat exchanger and the deformation and damage caused by the thermal expansion stress are avoided.

[0023] Preferably, the long axis of the overcross section of the second hollow tube and the plane of the tube axis are parallel to the second gaseous heat exchange medium entering direction.

[0024] In the case that the long axis of the overcross section of the outer tube of the heat exchange tube and the plane of the tube axis are parallel to the heat exchange medium entering direction, the flow resistance of the heat exchange medium is the smallest.

[0025] Preferably, the long axis of the overcross section of the second hollow tube and the plane of the tube axis form an angle with the second gaseous heat exchange medium entering direction, and the angle is greater than 0 and less than or equal to 60 degrees.

[0026] In the case that the long axis of the overcross section of the outer tube of the heat exchange tube and the plane of the tube axis form an angle with the heat exchange medium entering direction, and the angle is greater than 0 and less than or equal to 60 degrees, the heat exchange medium can be guided to flow by the outer wall of the heat exchange tube or turbulence can be caused by the outer wall of the heat exchange tube, so as to improve the heat exchange efficiency.

[0027] Preferably, the distance between the closed end of the second hollow tube of the heat exchange tube and the inner wall of the shell or other internal components is greater than the maximum expansion amount of the second hollow tube.

[0028] This arrangement can avoid the heat exchange tube interfering with the inner wall of the heat exchanger shell or other internal components due to thermal expansion, so that even at high temperature or high temperature difference, the second hollow tube can expand without damaging the internal components.

[0029] Preferably, at least two outlets for the first gaseous heat exchange medium are symmetrically arranged on the shell.

[0030] This arrangement can make the first gaseous heat exchange medium more evenly distributed.

[0031] Preferably, a flow direction distribution plate is further arranged between the second gaseous heat exchange medium outlet and the second gaseous heat exchange medium inlet, and the flow direction distribution plate is provided with distribution holes for guiding the flow of the second gaseous heat exchange medium.

[0032] The flow direction distribution plate can not only fix the heat exchange tube to avoid shaking of the heat exchange tube in the air flow disturbance state, but also guide the flow of the second gaseous heat exchange medium to make the second gaseous heat exchange medium more evenly distributed and improve the heat exchange efficiency.

[0033] Preferably, the heat exchanger is provided with a flow guide plate near the second gaseous heat exchange medium inlet and / or outlet for guiding the airflow to turn and making the second gaseous heat exchange medium more evenly distributed.

[0034] Preferably, the heat exchanger further comprises another heat exchange tube arranged upstream of the first end of the first hollow tube in the direction of the first gaseous heat exchange medium and downstream of the second hollow tube in the direction of the second gaseous heat exchange medium.

[0035] The other heat exchange tube can further utilize the waste heat of the second gaseous heat exchange medium at low temperature to further improve the heat exchange efficiency.

[0036] According to a third aspect of the present application, a heat exchange method is provided, comprising the following steps:

[0037] A plurality of heat exchange tubes are arranged in the housing, each heat exchange tube comprising a first hollow tube and a second hollow tube, the first hollow tube comprising an open first end and a second end, the second hollow tube comprising an open end and a closed end, the second hollow tube having a cross-sectional shape defining a long axis and a short axis, the ratio of the length along the long axis to the width along the short axis being greater than 5:1;

[0038] The first hollow tube is built inside the second hollow tube so that a gap is formed between the outer wall of the first hollow tube and the inner wall of the second hollow tube, and the first end of the first hollow tube is arranged to protrude out of the open end of the second hollow tube, the second end of the first hollow tube is spaced apart from the inner wall of the closed end of the second hollow tube, the first end of the first hollow tube, the hollow interior of the first hollow tube, the second end, the gap between the first hollow tube and the second hollow tube, and the open end of the second hollow tube at least partially define a first gaseous heat exchange medium flow channel;

[0039] The tube wall of the second hollow tube is arranged in a second gaseous heat exchange medium flow channel, and the plane of the long axis of the cross-section of the second hollow tube and the tube axis is arranged to be parallel to the second gaseous heat exchange medium entering direction or to form an angle with the second gaseous heat exchange medium entering direction, the angle being greater than 0 and less than or equal to 60 degrees;

[0040] The environment air is introduced into the first gaseous heat exchange medium flow channel as the first gaseous heat exchange medium by a fan, and the high-temperature flue gas is introduced into the second gaseous heat exchange medium flow channel as the second gaseous heat exchange medium, the environment air introduced by the fan and the high-temperature flue gas are in contact through the tube wall of the second hollow tube, heat exchange between the environment air and the high-temperature flue gas is realized, the temperature of the high-temperature flue gas is reduced, and the temperature of the introduced environment air is increased.

[0041] The heat exchange method according to the present application can improve the efficiency of gas-gas heat exchange, avoid deformation and damage between the heat exchange tube and related components due to thermal expansion, and improve the energy recycling rate.

[0042] In summary, the heat exchange tube, the heat exchanger using the same and the heat exchange method according to the present application are suitable for heat exchange under the condition that the wall temperature of the heat exchange tube is high and the thermal expansion amount is large, and can avoid deformation and damage caused by large thermal expansion during the heat exchange process while improving the heat exchange efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0043] Other features, objects, and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments thereof as read in conjunction with the accompanying drawings:

[0044] Figure 1 is a perspective view of a heat exchange tube according to an embodiment of the present application;

[0045] Figure 2 is a cross-sectional view of a heat exchange tube according to Figure 1 ;

[0046] Figures 3 to 8 is a cross-sectional view of a heat exchange tube according to an embodiment of the present application;

[0047] Figures 9 to 11 is a cross-sectional view of a first hollow tube according to an embodiment of the present application, showing different second end structures of the first hollow tube;

[0048] Figs. 12 to 14 are cross-sectional views of a second hollow tube according to an embodiment of the present application, showing different closed end structures of the second hollow tube;

[0049] Figure 15 is a perspective view of a heat exchanger according to a first embodiment of the present application with a front face panel removed;

[0050] Figure 16 is a front view of the heat exchanger according to the embodiment shown in Figure 15 , with a front face panel removed, showing the front face of the heat exchanger;

[0051] Figure 17 is a cross-sectional view of the heat exchanger according to the embodiment shown in Figure 15 , taken along a plane parallel to the front face;

[0052] Figure 18 is a top view of the heat exchanger according to the embodiment shown in Figure 15 ;

[0053] Figure 19 is a left view of the heat exchanger according to the embodiment shown in Figure 15 ;

[0054] Figure 20 is a perspective view of a heat exchanger according to a second embodiment of the present application with a front face panel removed;

[0055] Figure 21 is a front view of the heat exchanger of the embodiment shown in FIG. 1, with the front face panel removed, showing the front face of the heat exchanger; Figure 20

[0056] Figure 22 is a cross-sectional view of the heat exchanger of the embodiment shown in FIG. 1, taken along a plane parallel to the front face; Figure 20

[0057] Figure 23 is a top view of the heat exchanger of the embodiment shown in FIG. 1; Figure 20

[0058] Figure 24 is a cross-sectional view of the heat exchanger of the embodiment shown in FIG. 1, taken along a plane parallel to the top face and between the second seal plate and the baffle plate; Figure 20

[0059] Figure 25 is a left view of the heat exchanger of the embodiment shown in FIG. 1; Figure 20

[0060] Figure 26 is a right view of the heat exchanger of the embodiment shown in FIG. 1; Figure 20

[0061] Figure 27 is a front view of the heat exchanger of the embodiment shown in FIG. 2, with the front face panel removed, showing the front face of the heat exchanger;

[0062] Figure 28 Figure 27 is a left view of the heat exchanger of the embodiment shown in FIG. 2;

[0063] Figure 29 Figure 27 is a right view of the heat exchanger of the embodiment shown in FIG. 2; and

[0064] Figure 30 Figure 27 is a top view of the heat exchanger of the embodiment shown in FIG. 2.

[0065] Figure 31 Figure 27 is a top view of the heat exchanger of the embodiment shown in FIG. 2. DETAILED DESCRIPTION

[0066] The application will be further described with reference to the drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the application and that the terms "front", "top", "bottom", "left", "right", "up" and "down" are used only on the basis of the orientation of the figures shown in the drawings and are not intended to limit the application. It is also to be understood that only the parts relevant to the application are shown in the drawings. ​​​​​​​​​

[0067] Figure 1 This is a perspective view of a heat exchange tube according to an embodiment of the present invention. Figure 2 It is based on Figure 1 A cross-sectional view of a heat exchange tube is shown in the figure. The heat exchange tube includes a first hollow tube 1 and a second hollow tube 2. The first hollow tube 1 includes an open first end 101 and a second end 102. The second hollow tube 2 includes an open end 201 and a closed end 202. The first hollow tube 1 is built into the second hollow tube 2. A gap is formed between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2. The first end 101 of the first hollow tube 1 extends beyond the open end 201 of the second hollow tube 2. The second end 102 of the first hollow tube 1 is spaced apart from the inner wall of the closed end 202 of the second hollow tube 2. The first end 101 of the first hollow tube 1, the hollow interior of the first hollow tube 1, the second end 102, the gap between the first hollow tube 1 and the second hollow tube 2, and the open end 201 of the second hollow tube 2 define a fluid channel.

[0068] As a heat exchange tube, during use, the first gaseous heat exchange medium can enter from the first end 101 of the first hollow tube 1, pass through the hollow interior of the first hollow tube 1, flow out from the second end 102 of the first hollow tube 1 and enter the closed end 202 of the second hollow tube 2, then turn at the closed end 202 of the second hollow tube 2 and enter the gap between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2, and finally flow out from the open end 201 of the second hollow tube 2. In this process, heat exchange can be carried out between the first gaseous heat exchange medium entering the interior of the first hollow tube 1 and the first gaseous heat exchange medium entering the gap between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2, and also between the first gaseous heat exchange medium in the gap between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2 and the second fluid medium outside the second hollow tube 2. Therefore, the heat exchange efficiency can be improved.

[0069] Figures 3 to 8 This is a cross-sectional view of a heat exchange tube according to an embodiment of the present invention. As can be seen from the figure, the cross-sections of the first hollow tube 1 and the second hollow tube 2 are both flat and elongated, and the first hollow tube 1 and the second hollow tube 2 are combinations of various flat and elongated shapes.

[0070] The elongated shape mentioned in this specification refers to the cross-sectional profile of the first hollow tube 1 and the second hollow tube 2, where the ratio of the major axis width to the minor axis width is greater than 5:1. Usually, a symmetrical shape is adopted for the cross-section in order to achieve uniform heat exchange. In this specification, the major axis is defined as the axis of symmetry with a longer cross-sectional profile, and the minor axis is defined as the axis of symmetry with a shorter cross-sectional profile. In the case of an asymmetrical cross-section, the major axis refers to the axis along the length of the cross-section, and the minor axis refers to the axis along the width of the cross-section.

[0071] The hollow tube with oblong cross section is used as the heat exchange tube in the present application. Compared with the traditional round tube heat exchange tube, the hollow tube with oblong cross section can be arranged more closely, has high space utilization, and has increased heat exchange area and improved heat exchange efficiency. Compared with the plate heat exchanger, the structure is simple, easy to manufacture, and low in cost. Meanwhile, due to the hollow structure of the hollow tube with oblong cross section, the mass and volume of the heat exchanger can be reduced under the premise of the same heat exchange efficiency.

[0072] Therefore, although Figures 3 to 8 The first hollow tube 1 and the second hollow tube 2 are both shown as the hollow tube with oblong cross section in the figure, but in the present application, as long as the second hollow tube 2 is implemented as the hollow tube with oblong cross section, the advantages of the hollow tube with oblong cross section can be obtained, and therefore the cross section shape of the first hollow tube 1 can be any shape that forms a gap with the inner wall of the second hollow tube 2, such as a circular shape.

[0073] The gap between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2 can be formed in various ways. The embodiments of forming the gap by mechanical spacers, by the cooperation of the cross section shapes of the first hollow tube 1 and the second hollow tube 2, and by fixing one end of the first hollow tube 1 and one end of the second hollow tube 2 respectively are described in detail below.

[0074] Figures 3 to 5 The embodiment of floatingly supporting the outer wall of the first hollow tube 1 on the inner wall of the second hollow tube 2 by mechanical spacers to form a gap is schematically shown. In the shown embodiment, the mechanical spacers are double-headed bolts 3 passing through the tube wall of the first hollow tube 1 and retained by nuts installed on the outer wall of the first hollow tube 1, and the ends of the double-headed bolts 3 abut against the inner wall of the second hollow tube 2 in the direction of the long axis. In this way, the first hollow tube 1 can be supported in the second hollow tube 2 to avoid the first hollow tube 1 from shaking under the action of the first gaseous heat exchange medium, so that a gap is formed between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2; and the first hollow tube 1 can move axially relative to the second hollow tube 2. The ends of the double-headed bolts are usually provided as smooth ends, so that friction and wear of the inner wall of the second hollow tube by the ends of the double-headed bolts during movement can be avoided.

[0075] Referring back to Figure 2 The number and arrangement of the double-headed bolts 3 are not limited to Figure 2The embodiments shown in the drawings can achieve any manner of forming a gap between the first hollow tube 1 and the second hollow tube 2, not shaking relative to each other but moving axially relative to each other, within the protection scope of the present application. Generally, the first hollow tube 1 is supported on the inner wall of the second hollow tube 2 in the direction of the long axis by a plurality of studs 3 and nuts, ensuring that the first hollow tube 1 and the second hollow tube 2 are coaxially arranged, avoiding the first hollow tube 1 shaking in the second hollow tube 2 under the action of the first gaseous heat exchange medium, resulting in uneven airflow distribution in the gap between the first hollow tube 1 and the second hollow tube 2, affecting the heat exchange efficiency.

[0076] The mechanical spacer is also not limited to Figures 3 to 5 The stud 3 shown in the drawings can be achieved in various ways, such as spring clips, rib plates or ribs.

[0077] Figures 6 to 8 The embodiments shown schematically by the first hollow tube 1 supported on the inner wall of the second hollow tube 2 by the outer wall of the end portion of the first hollow tube 1 in the direction of the long axis, forming a gap between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2.

[0078] Specifically, Figure 6 In the drawings, the first hollow tube 1 is fixed relative to the second hollow tube 2 by the outer wall of the end portion of the first hollow tube 1 in the direction of the long axis abutting the inner wall of the end portion of the second hollow tube 2 in the direction of the long axis. Figure 7 and Figure 8 In the drawings, the first hollow tube 1 is fixed relative to the second hollow tube 2 not only by the outer wall of the end portion of the first hollow tube 1 in the direction of the long axis abutting the inner wall of the end portion of the second hollow tube 2 in the direction of the long axis, but also by the outer wall of the portion of the first hollow tube 1 between the end portions in the direction of the long axis abutting the inner wall of the portion of the second hollow tube 2 between the end portions in the direction of the long axis. Such a fixed manner of the first hollow tube 1 and the second hollow tube 2 forms a gap between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2, and avoids the first hollow tube 1 shaking under the action of the first gaseous heat exchange medium, while also allowing the first hollow tube 1 to move axially relative to the second hollow tube 2 when thermal expansion occurs during use as a heat exchange tube, avoiding the stress generated by the relative fixation of the first hollow tube 1 and the second hollow tube 2 due to thermal expansion.

[0079] When the first hollow tube 1 has a circular cross-sectional shape, it can be held relatively together by the radial outer wall of the first hollow tube 1 along the direction perpendicular to the long axis of the second hollow tube 2 against the inner wall of the second hollow tube 2 in a direction approximately along the long axis, forming a gap between the first hollow tube 1 and the second hollow tube 2. This prevents the first hollow tube 1 from swaying under the action of the first gaseous heat exchange medium. At the same time, when thermal expansion occurs during use as a heat exchange tube, the first hollow tube 1 is allowed to move relative to the second hollow tube 2, avoiding the stress caused by the interaction of the first hollow tube 1 and the second hollow tube 2 due to thermal expansion when they are fixed relative to each other.

[0080] exist Figures 6 to 8 In the case shown, the cross-sectional shape of the first hollow tube 1 is typically also elongated, defining its major and minor axes. The ratio of its length along the major axis to its width along the minor axis is greater than 5:1. The major and minor axes coincide with the major and minor axes of the cross-section of the second hollow tube 2. A portion of the outer wall of the end of the first hollow tube 1 along its major axis abuts against a portion of the inner wall of the end of the second hollow tube 2 along its major axis. In practical applications, depending on the actual heat exchange conditions, the major and minor axes of the cross-section of the first hollow tube 1 can be set to not completely coincide with the major and minor axes of the cross-section of the second hollow tube 2.

[0081] The gap between the first hollow tube 1 and the second hollow tube 2 can also be widened by fixing the first hollow tube 1 and the second hollow tube 2 respectively as shown in Figure 14. Figure 30 The gap between the first hollow tube 1 and the second hollow tube 2 can be achieved on the first sealing plate 5 and the second sealing plate 6 in the heat exchanger shown. That is, when the first hollow tube 1 and the second hollow tube 2 are fixed to the first sealing plate 5 and the second sealing plate 6 respectively, the gap between the first hollow tube 1 and the second hollow tube 2 can be achieved even without the use of mechanical spacers and without the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2 abutting against each other.

[0082] Figures 9 to 11 This is a cross-sectional view of the first hollow tube 1 through the axis according to an embodiment of the present invention, showing different second-end structures of the first hollow tube 1. The first gaseous heat exchange medium enters the inner wall of the first hollow tube 1 from the first end 101, and then flows out from the second end 102 of the first hollow tube 1 into the gap between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2. At this time, due to the change in flow direction, flow resistance is caused. In order to reduce the large pressure difference caused by the flow resistance, openings 103 of regular or irregular uniform distribution are opened on the surface of the first hollow tube 1 near the second end 102 along the circumferential direction or only on the long axis side of the tube wall. Figure 9 As can be seen, the first hollow tube 1 has multiple rows of small circular openings 103 arranged along the circumferential direction or only on the long axis side of the tube wall near the second end 102. The multiple rows are arranged along the axial direction, and each small circular opening in each row is oriented radially. Figure 10 and Figure 11As can be seen, the first hollow tube 1 has multiple rows of strip-shaped openings 103 arranged circumferentially or only on the long axis side of the tube wall near the second end 102. The strip-shaped openings 103 are oriented axially, and the multiple rows are evenly distributed along the outer periphery of the second end 102 or only on the long axis side of the tube wall. Figure 10 The opening in the middle does not penetrate the edge of the second end 102 of the first hollow tube 1. Figure 11 The opening extends through the edge of the second end 102 of the first hollow tube 1. The shape of the opening can be any possible shape, and it is usually evenly distributed to ensure that the first gaseous heat exchange medium enters the gap between the first hollow tube and the second hollow tube evenly.

[0083] Figures 12 to 14 are cross-sectional views of a second hollow tube according to an embodiment of the present invention, showing different closed end structures of the second hollow tube. In Figure 12, the closing base plate of the closed end 202 of the second hollow tube 2 is flush with the lower end face of the tube wall. In Figure 13, the closing base plate of the closed end 202 of the second hollow tube 2 is fastened inside the tube wall by welding. In Figure 14, the closing base plate of the closed end 202 of the second hollow tube 2 is enclosed outside the tube wall. It should be understood that the form of the closed end of the second hollow tube 2 is not limited to the above three types, and other forms that can achieve a closed end are also within the scope of the present invention.

[0084] Figure 15 This is a perspective view of a heat exchanger according to a first embodiment of the present invention with the front panel removed. In order to clearly show the internal structure of the heat exchanger, the front panel of the shell is removed in this perspective view. Figure 16 yes Figure 15 The front view of the heat exchanger in the illustrated embodiment, with the front panel removed, shows the front of the heat exchanger. Figure 17 yes Figure 15 The heat exchanger of the illustrated embodiment is shown in a cross-sectional view taken along a plane parallel to the front. Also refer to... Figures 15 to 17 As shown in the figure, the heat exchanger includes a shell 4, on which inlet and outlet are provided for a first gaseous heat exchange medium and an inlet and outlet for a second gaseous heat exchange medium. A first sealing plate 5 and a second sealing plate 6 are mounted on the shell 4, along with multiple heat exchange tubes as described above. In this embodiment, the inlet for the first gaseous heat exchange medium is the opening at the first end 101 of the first hollow tube 1, and the outlets are outlets 401 and 402 on the left and right panels of the shell 4. The inlet for the second gaseous heat exchange medium is inlet 403 on the left panel of the shell 4, and the outlet is outlet 404 on the right panel of the shell 4. The first sealing plate 5 and the second sealing plate 6 are respectively provided with through holes for receiving the first hollow tube 1 and the second hollow tube 2. In this embodiment, the heat exchange tubes of the heat exchanger are composed of a first hollow tube 1 and a second hollow tube 2 forming a nested sleeve.

[0085] In the shown embodiment, the second hollow tube 2 is sealed and fixed on the second sealing plate 6 through the through hole on the second sealing plate 6, the first hollow tube 1 is built inside the second hollow tube 2 through the through hole on the first sealing plate 5, and is sealed and fixed on the first sealing plate 5, Figure 15 and Figure 17 The first gaseous heat exchange medium outlets 401 and 402 shown in

[0086] In actual use, the first gaseous heat exchange medium (usually ambient air or other low-temperature gas) is delivered by a fan to a gas collecting box connected to the top of the heat exchanger, enters the hollow interior of the first hollow tube 1 from the opening of the first end 101 of the first hollow tube 1 on the first sealing plate 5, flows downward along the first hollow tube 1, flows out of the second end 102 of the first hollow tube 1 and turns, flows upward along the gap between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2, flows out of the opening of the open end 201 of the second hollow tube 2, enters the space surrounded by the first sealing plate 5, the second sealing plate 6, and the shell between the first sealing plate 5 and the second sealing plate 6, and finally flows out of the outlets 402 and 401 provided on the two side panels of the shell 4, enters the furnace to participate in combustion, and further utilizes the heat absorbed by the first gaseous heat exchange medium.

[0087] Figure 18 is a top view of the heat exchanger of the embodiment shown in Figure 15 Figure 19 is a side view of the heat exchanger of the embodiment shown in Figure 15 Figure 18 It can be clearly seen from Figure 19 The outlets 401 of the first gaseous heat exchange medium and the inlets 403 of the second gaseous heat exchange medium can be seen. The symmetrical arrangement of the outlets 401 and 402 of the first gaseous heat exchange medium on the shell can make the first gaseous heat exchange medium flow out uniformly, improve the heat exchange performance, and the number of outlets of the first gaseous heat exchange medium is not limited to two, and multiple outlets can be arranged symmetrically.

[0088] Continuing to refer to Figures 15 to 19 ​​Furthermore, it can be seen that an inlet 403 and an outlet 404 for the second gaseous heat exchange medium are provided on the left and right panels located below the second sealing plate 6. The flow channel of the second gaseous heat exchange medium is formed by the inlet 403, the space enclosed by the shell 4 below the second sealing plate 6, and the outlet 404. The inlet 403 and the outlet 404 are at the same height. After the second gaseous heat exchange medium enters the flow channel from the inlet 403, it flows essentially along... Figure 17 The medium flows from right to left through the second gaseous heat exchange medium channel and then flows out from outlet 404. The second hollow tube 2 extends in the second gaseous heat exchange medium channel. During the process of the second gaseous heat exchange medium passing through the second gaseous heat exchange medium channel, heat exchange between the first gaseous heat exchange medium and the second gaseous heat exchange medium is realized.

[0089] In the heat exchanger of this embodiment, the second gaseous heat exchange medium enters the second gaseous heat exchange medium flow channel formed in the shell 4 through the inlet 403 of the second gaseous heat exchange medium in a direction that is substantially perpendicular to the side panel of the shell 4, and then flows out through the outlet 404 of the second gaseous heat exchange medium. At this time, the direction of the second gaseous heat exchange medium is generally perpendicular to the direction of the first gaseous heat exchange medium inside the first hollow tube 1 and in the gap between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2, forming a cross-flow heat exchange.

[0090] Therefore, in the heat exchanger of this embodiment, there is not only cross-flow heat exchange between the first gaseous heat exchange medium and the second gaseous heat exchange medium through the tube wall of the second hollow tube 2, but also counter-flow heat exchange between the first gaseous heat exchange medium inside the first hollow tube 1 and the first gaseous heat exchange medium between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2. The heat exchange area is increased. Therefore, compared with the case where the heat exchange tube is not the sleeve type of the present invention, in which there is only heat exchange between the first gaseous heat exchange medium and the second gaseous heat exchange medium through the tube wall of the heat exchange tube, the heat exchange efficiency of the heat exchanger of this embodiment is improved.

[0091] The heat exchanger of the embodiment not only improves the heat exchange efficiency, but also solves the problems of deformation and expansion stress caused by thermal expansion under the condition of high wall temperature of the heat exchange pipe. In the heat exchanger of the embodiment, the first hollow pipe 1 is only fixed at the first end 101 on the first sealing plate 5, and the second end 102 is set as a free end. The second hollow pipe 2 is only fixed at the open end 201 on the second sealing plate 6, and the closed end 202 is set as a free end. Therefore, even when thermal expansion occurs under high temperature, the first hollow pipe 1 and the second hollow pipe 2 can freely elongate along the central axis direction, and the plurality of first hollow pipes 1 or the plurality of second hollow pipes 2 are not simultaneously constrained by the first sealing plate 5 and / or the second sealing plate 6. The different expansion amounts of different heat exchange pipes caused by different temperatures due to uneven heat exchange will not cause the stress deformation or even tearing of the weld on the sealing plate. Therefore, good sealing performance can be provided, and the heat exchanger is suitable for high heat exchange pipe wall temperature and large wall temperature difference.

[0092] In actual use, the second gaseous heat exchange medium is usually high-temperature flue gas with low pollution. After heat exchange in the heat exchanger, the heat of the high-temperature flue gas can be recovered and utilized, and the flue gas with reduced temperature can be directly discharged into the atmosphere through a chimney. For high-temperature flue gas with pollution, it is sent to a subsequent treatment system after heat exchange in the heat exchanger, and is discharged after meeting the environmental protection standards.

[0093] The first gaseous heat exchange medium, which is usually ambient air introduced into the heat exchanger by a fan, has a temperature rise after heat exchange with the second gaseous heat exchange medium, and can be used as combustion-supporting air into a heating furnace to improve the thermal efficiency of the heating furnace. The first gaseous heat exchange medium with a temperature rise after heat exchange with the second gaseous heat exchange medium can also be used for other purposes, such as drying materials.

[0094] It should be noted that since the outer wall of the second hollow pipe 2 of the heat exchange pipe usually needs to contact the second gaseous heat exchange medium with a high temperature, the expansion amount of the second hollow pipe 2 is large, and the closed end 202 of the second hollow pipe 2 should be spaced apart from the bottom wall 405 of the shell 4 or other internal components located at the bottom of the shell 4. The spacing distance should be greater than the maximum expansion amount of the second hollow pipe 2, so as to avoid mutual interference between the second hollow pipe 2 and the bottom wall 405 of the shell 4 or other internal components located at the bottom of the shell 4 under high temperature or large temperature difference. Therefore, even under high temperature or large temperature difference, the second hollow pipe 2 with a large expansion amount will not damage the internal components.

[0095] In this embodiment, the long axis of the overcross section of the second hollow tube 2 and the plane of the tube axis are parallel to the direction of the second gaseous heat exchange medium entering the shell 4, which is referred to as the second gaseous heat exchange medium entering direction. At this time, the heat exchange tube has the minimum resistance to the second gaseous heat exchange medium. The long axis of the overcross section of the second hollow tube 2 and the plane of the tube axis can also be arranged at an angle to the second gaseous heat exchange medium entering direction. A proper angle can make the outer surface of the second hollow tube 2 guide the second gaseous heat exchange medium, or introduce proper disturbance to the second gaseous heat exchange medium, which is more helpful to improve the heat exchange efficiency. The angle is preferably greater than 0 and less than or equal to 60 degrees.

[0096] Figure 20 is a front panel removed perspective view of the heat exchanger according to the second embodiment of the present application, in which the front panel of the shell is removed for clearly showing the internal structure of the heat exchanger; Figure 21 is Figure 20 is a front panel removed front view of the heat exchanger of the embodiment shown in Figure 23 is Figure 20 is a top view of the heat exchanger of the embodiment shown in Figure 24 is Figure 20 is a sectional view of the heat exchanger of the embodiment shown in Figure 20 , Figure 21 , Figure 23 and Figure 24 As can be seen from Figures 15 to 19 , the overall structure of the heat exchanger in this embodiment is the same as that of the heat exchanger shown in Figures 15 to 19 , and the heat exchange tube and the flow channel structure of the first gaseous heat exchange medium are the same as those shown in Figures 15 to 19 , which will not be described in detail herein. The difference between the heat exchanger of this embodiment and the heat exchanger in is mainly in the structure of the second gaseous heat exchange medium flow channel, which will be described in detail below.

[0097] Figure 22 is a sectional view of the heat exchanger of the embodiment shown in Figure 20 , taken along a plane parallel to the front face. As can be seen from Figure 22As can be seen, the shell 4 has an inlet 403 for the second gaseous heat exchange medium located on the right side panel, immediately below the second sealing plate 6, and an outlet 404 for the second gaseous heat exchange medium located at the bottom of the left side panel. The inlet 403 is positioned higher than the outlet 404. Therefore, in this embodiment, after the second gaseous heat exchange medium enters the flow channel through the inlet 403, it needs to flow from top to bottom to pass through the flow channel and exit through the outlet 404. The downward flow direction of the second gaseous heat exchange medium is parallel to and opposite to the upward flow direction of the first gaseous heat exchange medium in the gap between the inner wall of the second hollow tube 2 and the outer wall of the first hollow tube 1, forming counter-current heat exchange. Figures 15 to 19 Compared with the cross-flow heat transfer between the first gaseous heat transfer medium and the second gaseous heat transfer medium in the embodiment shown, the counter-flow heat transfer efficiency between the first gaseous heat transfer medium and the second gaseous heat transfer medium in this embodiment is higher, thus further improving the heat transfer efficiency of the heat exchanger.

[0098] Figure 25 yes Figure 20 Left view of the heat exchanger in the embodiment shown; Figure 26 yes Figure 20 The right view of the heat exchanger in the embodiment shown is compared. Figure 25 and 26 It can be clearly seen that the inlet 403 and outlet 404 of the second gaseous heat exchange medium in this embodiment are at different heights.

[0099] Continue to refer to Figure 21 and Figure 22 Preferably, in order to evenly distribute the second gaseous heat exchange medium and guide its flow from top to bottom, a flow distribution plate 7 is also provided in the flow channel of the second gaseous heat exchange medium inside the shell 4, fixed to the inner wall of the shell 4. The flow distribution plate 7 is provided with distribution holes, through which the second hollow tube 2 passes. A ventilation gap is formed between the outer wall of the second hollow tube 2 and the edge of the distribution hole to guide the second gaseous heat exchange medium to flow through. During the process of passing through the ventilation gap, the second gaseous heat exchange medium is evenly distributed and can generate efficient countercurrent heat exchange with the first gaseous heat exchange medium in the second hollow tube 2, improving the heat exchange efficiency of the heat exchanger. Moreover, the flow distribution plate 7 can also float and support the outer wall of the second hollow tube 2 to avoid vibration when the heat exchange tube is long, thus improving the operational stability of the heat exchanger. The form and number of flow distribution plates 7 are not limited to those shown in this embodiment. Any form and number of flow distribution plates that can realize the function of the flow distribution plate 7 are within the protection scope of this invention.

[0100] The second gaseous heat exchange medium is prone to deflection and other phenomena when it is diverted from flowing from right to left to flowing from top to bottom or from flowing from top to bottom to flowing from right to left, and therefore it is further preferred that, near the inlet 403 and the outlet 404 of the second gaseous heat exchange medium, a flow guide plate 8 is further provided, the flow guide plate 8 is used to uniformly distribute the second gaseous heat exchange medium while guiding the diversion of the second gaseous heat exchange medium, the flow guide plate 8 is usually fixed on the inner wall of the shell 4, and includes a portion extending in the left-right direction and a portion extending in the up-down direction, as well as a diversion portion connecting the two portions, the number and form of the flow guide plate 8 are not limited to those shown in the present embodiment, and any form and number of flow guide plates that can achieve the function of the flow guide plate 8 are within the protection scope of the present application.

[0101] Figure 27 is a front panel removed perspective view of the heat exchanger according to the third embodiment of the present application, in which the front panel of the shell is removed in order to clearly show the internal structure of the heat exchanger; Figure 28 is Figure 27 is a front panel removed front view of the heat exchanger of the embodiment shown in

[0102] Meanwhile, reference is made to Figure 27 and Figure 28As can be seen from the view of the same parts in the first embodiment and the second embodiment, the heat exchanger comprises a housing 4, a first sealing plate 5 and a second sealing plate 6 are installed on the housing 4, and the first sealing plate 5 and the second sealing plate 6 are respectively provided with through holes for receiving the first hollow tube 1 and the second hollow tube 2. The heat exchange tube of the heat exchanger in the present embodiment not only comprises the heat exchange tube composed of the first hollow tube 1 and the second hollow tube 2 forming a nested sleeve tube, but also comprises a heat exchange tube 10 located below the closed end 202 of the second hollow tube 2 at the bottom of the housing, and a sealing plate sealingly connected to both ends of the heat exchange tube 10. The heat exchanger according to the present embodiment further comprises an inlet 407 of the first gaseous heat exchange medium arranged at the lower part of the right side panel of the housing 4, and a medium conversion elbow box 9 connecting the lower part of the left side panel and the top panel of the housing 4, the upper end gas collecting box 901 of the medium conversion elbow box 9 is in fluid communication with the first end 101 of the first hollow tube 1 sealingly fixed on the first sealing plate 5, and the lower end gas collecting box 902 of the medium conversion elbow box 9 is in fluid communication with the left end opening of the heat exchange tube 10, the first gaseous heat exchange medium enters the hollow interior of the heat exchange tube 10 through the inlet 407, and the outlet 401 and 402 of the first gaseous heat exchange medium are symmetrically arranged at the upper parts of the left side panel and the right side panel of the housing 4. Therefore, the heat exchange tube 10 is arranged upstream of the first end 101 of the first hollow tube 1 along the flow direction of the first gaseous heat exchange medium, and the first gaseous heat exchange medium flow channel in the third embodiment is defined by the inlet 407 of the first gaseous heat exchange medium, the interior of the heat exchange tube 10, the interior of the medium conversion elbow box 9, the gap between the first end 101 of the first hollow tube 1, the interior of the first hollow tube 1, the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2, the space surrounded by the first sealing plate 5, the second sealing plate 6 and the housing 4, and the outlets 401 and 402 of the first gaseous heat exchange medium arranged on the housing 4.

[0103] In actual use of the third embodiment, the first gaseous heat exchange medium (usually ambient air or other low-temperature gas) is delivered to the inlet 407 of the first gaseous heat exchange medium through a fan, enters the hollow interior of the first hollow tube 1 from the opening of the first end 101 of the first hollow tube 1 on the first sealing plate 5 through the heat exchange tube 10 and the medium conversion elbow box 9, flows downward along the first hollow tube 1, flows out from the second end 102 of the first hollow tube 1 into the closed end 202 of the second hollow tube 2, and turns at the closed end 202 of the second hollow tube 2 to flow upward along the gap between the outer wall of the first hollow tube 1 and the inner wall of the second hollow tube 2, flows out through the opening of the open end 201 of the second hollow tube 2, enters the space surrounded by the first sealing plate 5, the second sealing plate 6 and the housing between the first sealing plate 5 and the second sealing plate 6, and finally flows out from the outlets 402 arranged on the left side panel and the outlets 401 arranged on the right side panel of the housing 4 to be further utilized in a heating furnace.

[0104] In the heat exchanger of the present embodiment, an outlet gas collecting box 11 for the second gaseous heat exchange medium is arranged at the bottom of the shell 4, the second gaseous heat exchange medium enters the shell 4 substantially from the inlet 403, and needs to flow in the direction from top to bottom to flow out from the outlet gas collecting box 11 of the second gaseous heat exchange medium after passing through the heat exchange tube composed of the first hollow tube 1 and the second hollow tube 2, the flow direction of the second gaseous heat exchange medium from top to bottom is parallel and opposite to the flow direction of the first gaseous heat exchange medium from bottom to top in the gap between the inner wall of the second hollow tube 2 and the outer wall of the first hollow tube 1, forming counter-flow heat exchange, and then flowing through the heat exchange tube 10 in the direction substantially perpendicular to the extension direction of the heat exchange tube 10 from top to bottom, so it can be seen that the heat exchange tube 10 is arranged downstream of the second hollow tube 2 in the flow direction of the second gaseous heat exchange medium, and forms cross-flow heat exchange with the heat exchange tube 10, so compared with the first and second embodiments, the heat exchange between the first gaseous heat exchange medium and the second gaseous heat exchange medium in the third embodiment not only includes counter-flow heat exchange at the heat exchange tube composed of the first hollow tube 1 and the second hollow tube 2, but also includes cross-flow heat exchange at the heat exchange tube 10, so the heat exchange efficiency of the heat exchanger is further improved.

[0105] It should be noted that at the heat exchange tube 10, the second gaseous heat exchange medium (usually flue gas) at a lower temperature after heat exchange with the heat exchange tube composed of the first hollow tube 1 and the second hollow tube 2 further performs cross-flow heat exchange with the first gaseous heat exchange medium (usually ambient air) at normal temperature, so that the waste heat of the second gaseous heat exchange medium at a lower temperature is further utilized, and the temperature of the first gaseous heat exchange medium at normal temperature is also increased to a certain extent; at this time, although the temperature of the first gaseous heat exchange medium is increased compared with the normal temperature, the second gaseous heat exchange medium (usually flue gas) is at a higher temperature at the heat exchange tube composed of the first hollow tube 1 and the second hollow tube 2, and the temperature of the first gaseous heat exchange medium is still at a lower temperature compared with the second gaseous heat exchange medium at a higher temperature, so that through counter-flow heat exchange, the heat of the second gaseous heat exchange medium at a higher temperature is fully recovered and utilized, and the temperature of the first gaseous heat exchange medium at a lower temperature is further increased.

[0106] Continuing to refer to Figure 27 and Figure 28 , preferably, in order to uniformly distribute the second gaseous heat exchange medium and guide the second gaseous heat exchange medium to flow in the direction from top to bottom, a flow direction distribution plate 7 is further arranged in the second gaseous heat exchange medium flow channel in the shell 4, which is the same as the flow direction distribution plate 7 described in the second embodiment, and will not be described in detail here.

[0107] When the second gaseous heat exchange medium is diverted from flowing right to left to flowing top to bottom through the heat exchange tube composed of the first hollow tube 1 and the second hollow tube 2, the phenomenon of deflection and the like is likely to occur, and therefore, further preferably, a flow guide plate 8 is arranged near the inlet 403 of the second gaseous heat exchange medium, the flow guide plate 8 being used to uniformly distribute the second gaseous heat exchange medium while guiding the diversion of the second gaseous heat exchange medium, the flow guide plate 8 having the same structure as the flow guide plate in the second embodiment, and therefore, no further detailed description is given herein.

[0108] Figure 29 is a left view of the heat exchanger of the embodiment shown in Figure 27 Figure 30 is a right view of the heat exchanger of the embodiment shown in Figure 27 Figure 29 and 30 , it can be clearly seen that the outlet 401 and 402 of the first gaseous heat exchange medium, the inlet 403 and outlet header 11 of the second gaseous heat exchange medium, the inlet 407 of the first gaseous heat exchange medium and the medium diversion elbow header 9 in the embodiment, it can be seen from the figure that the positions of the inlet 403 and outlet header 11 of the second gaseous heat exchange medium are at different heights, and it can also be seen that the lower end header 902 of the medium diversion elbow header 9 is combined with the lower part of the left side panel of the shell 4.

[0109] Figure 31 is a top view of the heat exchanger of the embodiment shown in Figure 27

[0110] It should also be noted that the second gaseous heat exchange medium (usually flue gas) contains components that are corrosive to conventional metals (carbon steel or stainless steel), and when the temperature is low enough to reach the acid dew point temperature, acid dew point corrosion will occur. For the heat exchange tube composed of the first hollow tube 1 and the second hollow tube 2, there is no acid dew point corrosion when in use because the temperature of the second gaseous heat exchange medium is relatively high, so the heat exchange tube can be made of conventional carbon steel or stainless steel metal material; while for the heat exchange tube 10, the temperature of the gaseous heat exchange medium is relatively low when in use, in order to avoid the occurrence of acid dew point corrosion while being able to fully recover and utilize the heat of the second gaseous heat exchange medium, the heat exchange tube 10 is preferably made of glass material. The heat exchange tube 10 can be selected to have any shape of hollow tube structure, such as the structure of the flat cross-section heat exchange tube of the second hollow tube 2 in the present application.

[0111] Although the first gaseous heat exchange medium is described as ambient air and the second gaseous heat exchange medium is described as high-temperature flue gas in the present specification, in fact, the first gaseous heat exchange medium and the second gaseous heat exchange medium can be any form of high-temperature or low-temperature gaseous medium.

[0112] ​​​It should also be noted that although the outlet 401 and 402 of the first gaseous heat exchange medium, the inlet 403 and outlet 404 of the second gaseous heat exchange medium in the first and second embodiments of the heat exchanger, and the outlet 401 and 402 of the first gaseous heat exchange medium, the inlet 403 of the second gaseous heat exchange medium and the inlet 407 of the first gaseous heat exchange medium in the third embodiment are described as being implemented on the panel of the housing 4, this is merely an example, the inlets or outlets are not limited by the specific implementation described, and can all be provided as inlets or outlets leading out of or leading into the panel of the housing 4, such as tubes extending out of or into the panel of the housing 4 or being implemented in other ways.

[0113] The above description is merely preferred embodiments of the present application and a description of the technical principles of the application. It should be understood by those skilled in the art that the scope of the application disclosed in the present application is not limited to the technical solutions formed by the specific combinations of the technical features described above, and should also cover other technical solutions formed by any combinations of the technical features described above or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above-described features and the technical features disclosed in the present application (but not limited to) having similar functions.

Claims

1. A heat exchange tube for gaseous heat exchange medium, characterized by, The heat exchanger comprises: a first hollow tube and a second hollow tube, the first hollow tube comprising an open first end and a second end, the second hollow tube comprising an open end and a closed end, the second hollow tube having a cross-sectional shape defining a long axis and a short axis, a length along the long axis being greater than 5:1 of a width along the short axis, wherein the first hollow tube is built-in the second hollow tube, a gap is formed between an outer wall of the first hollow tube and an inner wall of the second hollow tube, and the first end of the first hollow tube extends out of the open end of the second hollow tube, the second end of the first hollow tube is spaced apart from the inner wall of the closed end of the second hollow tube, the first end of the first hollow tube, a hollow interior of the first hollow tube, the second end, the gap between the first hollow tube and the second hollow tube, and the open end of the second hollow tube define a fluid passage for the gaseous heat exchange medium; the cross-sectional shape of the first hollow tube defines a long axis and a short axis, wherein a plurality of openings are uniformly arranged on the second end long axis side tube wall of the first hollow tube for reducing the turning flow resistance of the first gaseous heat exchange medium.

2. The heat exchange tube according to claim 1, wherein At least part of the outer wall of the first hollow tube abuts against the inner wall of the second hollow tube to form the gap between the outer wall of the first hollow tube and the inner wall of the second hollow tube, and to avoid the first hollow tube from shaking relative to the second hollow tube.

3. The heat exchange tube according to claim 2, wherein The length along the long axis of the first hollow tube is greater than 5:1 of the width along the short axis, the long axis coincides with the long axis of the cross-section of the second hollow tube, and part of the outer wall of the end portion along the long axis of the first hollow tube abuts against part of the inner wall of the end portion along the long axis of the second hollow tube.

4. The heat exchange tube of claim 1, wherein The outer wall of the first hollow tube is floatingly supported on the inner wall of the second hollow tube by mechanical spacers to form the gap between the outer wall of the first hollow tube and the inner wall of the second hollow tube, and to avoid the first hollow tube from shaking relative to the second hollow tube.

5. The heat exchange tube according to claim 4, wherein The mechanical spacers are studs passing through the tube wall of the first hollow tube and retained by nuts mounted on the outer wall of the first hollow tube, the ends of the studs abutting against the inner wall of the long axis side of the second hollow tube.

6. A heat exchanger, characterized by The heat exchanger comprises: a housing, the housing being provided with an inlet and an outlet for a first gaseous heat exchange medium and an inlet and an outlet for a second gaseous heat exchange medium; a plurality of heat exchange tubes as claimed in any one of claims 1-5 arranged in the housing, the fluid passage at least partially defining a first gaseous heat exchange medium flow channel for receiving the first gaseous heat exchange medium; first and second sealing plates mounted on the housing, the first and second sealing plates being respectively provided with a plurality of through holes for the first and second hollow tubes, the first end of the first hollow tube of the heat exchange tube being sealingly mounted on the first sealing plate through the through hole on the first sealing plate, and the open end of the second hollow tube being sealingly mounted on the second sealing plate through the through hole on the second sealing plate, the heat exchanger further comprising a second gaseous heat exchange medium flow channel arranged in the housing and separated from the first gaseous heat exchange medium flow channel for receiving the second gaseous heat exchange medium, the heat exchanger further comprising a second gaseous heat exchange medium flow channel arranged in the housing and separated from the first gaseous heat exchange medium flow channel for receiving the second gaseous heat exchange medium, The first gaseous heat exchange medium flow channel is defined by the inlet for the first gaseous heat exchange medium, the first hollow tube first end, the hollow interior of the first hollow tube, the first hollow tube second end, the gap between the first hollow tube and the second hollow tube, the space enclosed by the first sealing plate, the second sealing plate and the shell, and the outlet for the first gaseous heat exchange medium provided on the shell, and the second hollow tube of the heat exchange tube extends in the second gaseous heat exchange medium flow channel to achieve heat exchange between the first gaseous heat exchange medium and the second gaseous heat exchange medium.

7. The heat exchanger of claim 6, wherein The plane of the long axis of the overcross-sectional area of the second hollow tube and the tube axis is parallel to the second gaseous heat exchange medium entering direction.

8. The heat exchanger of claim 6, wherein The plane of the long axis of the overcross-sectional area of the second hollow tube and the tube axis forms an angle with the second gaseous heat exchange medium entering direction, and the angle is greater than 0 and less than or equal to 60 degrees.

9. The heat exchanger of claim 6, wherein The distance between the closed end of the second hollow tube of the heat exchange tube and the inner wall of the shell or other internal components is greater than the maximum expansion amount of the second hollow tube.

10. The heat exchanger of claim 6, wherein At least two outlets for the first gaseous heat exchange medium are symmetrically provided on the shell.

11. The heat exchanger of claim 6, wherein A flow direction distribution plate is further provided between the second gaseous heat exchange medium outlet and the second gaseous heat exchange medium inlet, and the flow direction distribution plate is provided with distribution holes for guiding the flow of the second gaseous heat exchange medium.

12. The heat exchanger of claim 11, wherein, The heat exchanger is provided with a flow guide plate near the second gaseous heat exchange medium inlet and / or outlet for guiding the flow of the second gaseous heat exchange medium to change direction and make the distribution of the second gaseous heat exchange medium more uniform.

13. The heat exchanger according to claim 11 or 12, characterized in that The heat exchanger further comprises another heat exchange tube arranged upstream of the first end of the first hollow tube in the direction of the first gaseous heat exchange medium and arranged downstream of the second hollow tube in the direction of the second gaseous heat exchange medium.

14. A heat exchange method, characterized by, The method comprises the following steps: A plurality of heat exchange tubes are arranged in the shell, each heat exchange tube comprising a first hollow tube and a second hollow tube, the first hollow tube comprising an open first end and a second end, the second hollow tube comprising an open end and a closed end, the cross-sectional shape of the second hollow tube defining a long axis and a short axis, the ratio of the length in the direction of the long axis to the width in the direction of the short axis being greater than 5:1, the cross-sectional shape of the first hollow tube defining a long axis and a short axis, and a plurality of openings being uniformly provided on the tube wall on the side of the second end of the first hollow tube in the direction of the long axis; The first hollow tube is arranged inside the second hollow tube so that a gap is formed between the outer wall of the first hollow tube and the inner wall of the second hollow tube, and the first end of the first hollow tube is arranged to protrude out of the open end of the second hollow tube, the second end of the first hollow tube is spaced apart from the inner wall of the closed end of the second hollow tube, and the first end of the first hollow tube, the hollow interior of the first hollow tube, the second end, the gap between the first hollow tube and the second hollow tube, and the open end of the second hollow tube at least partially define a first gaseous heat exchange medium flow channel; The tube wall of the second hollow tube is arranged in a second gaseous heat exchange medium flow channel, and the plane of the long axis of the overcross-sectional area of the second hollow tube and the tube axis is arranged to be parallel to the second gaseous heat exchange medium entering direction or forms an angle with the second gaseous heat exchange medium entering direction, and the angle is greater than 0 and less than or equal to 60 degrees. The fan is used to introduce the ambient air as the first gaseous heat exchange medium into the first gaseous heat exchange medium flow channel, and the high-temperature flue gas is introduced as the second gaseous heat exchange medium into the second gaseous heat exchange medium flow channel, the ambient air introduced by the fan is contacted with the high-temperature flue gas through the pipe wall of the second hollow pipe, the heat exchange between the ambient air and the high-temperature flue gas is realized, the temperature of the high-temperature flue gas is reduced, and the temperature of the introduced ambient air is increased.

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