Connecting structure of metal tube and tube plate
By using clad metal pipes and pipe plates with broken holes and slots in the connection structure between metal pipes and pipe plates, the problems of poor corrosion and wear resistance of traditional metal pipe heat exchangers in high sulfur environments are solved, and higher stability and safety are achieved.
Patent Information
- Application Number
- CN202421496073.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-27
- Publication Date
- 2025-05-02
- Estimated Expiration
- 2034-06-27
AI Technical Summary
Traditional metal tube heat exchangers cannot be used stably for a long time in environments with high sulfur content, and fluoroplastic heat exchangers have poor wear resistance and are prone to deformation, and are prone to rupture due to friction or improper operation, which affects the stability and safety of the heat exchangers.
A connection structure between a metal tube and a tube plate is adopted, where the outer wall of the metal tube is covered with an inner membrane and an outer membrane, and the outer membrane can be extended to form a limiting ring to avoid relative displacement caused by different expansion coefficients; tube holes are provided on the tube plate, with broken holes at both ends, and slot holes are installed in the center to avoid frictional loss and medium penetration.
Effectively prevent direct contact between flue gas and metal pipes, avoid low-temperature corrosion, simplify welding processes, reduce production workload, improve operational reliability, reduce safety hazards, and enhance sealing.
Smart Images
Figure CN222824896U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of connection structures, in particular to a connection structure between a metal tube and a tube plate. Background Art
[0002] The peak load modification of boilers generally involves low-temperature heat exchangers. This type of heat exchanger is usually installed in front of the desulfurization tower to reduce the flue gas temperature entering the desulfurization tower at the tail of the boiler, and extract the waste heat of the flue gas in front of the desulfurization tower for other places where heat is needed. This reduces the heat loss of flue gas and thus reduces fuel consumption.
[0003] However, lowering the flue gas temperature at the desulfurization tower inlet will reduce the water dew point of the flue gas. The reduction of the flue gas water dew point will increase the low-temperature corrosion of the flue gas. Traditional metal tube heat exchangers are often not suitable for this situation. In an environment with a slightly higher sulfur content, duplex stainless steel such as 2205 cannot be used stably for a long time.
[0004] In order to address this situation, the use of non-metallic heat exchangers is increasing. They effectively solve the corrosion problem of high HCL and SO2 in flue gas on traditional metal heat exchangers, so that they can still be used normally when the media on both sides of the heat exchanger have high corrosion capacity.
[0005] However, the heat exchange tubes used in fluoroplastics are made of fluoroplastics. They have good corrosion resistance, but poor wear resistance and are easy to deform compared to metal heat exchange tubes. In environments with high dust content in the flue gas or large particles, the heat exchange tubes are prone to friction and leakage; or improper operation causes the heat exchange tubes to stretch, reducing their own strength. To solve the above problems, coated metal heat exchange tube heat exchangers came into being. Coating the metal tube with a layer of fluoroplastic film can not only prevent the corrosion of the heat exchange tube by low-temperature flue gas, but also avoid the impact of the fluoroplastic's own strength problem on the smooth operation of the heat exchanger.
[0006] In the above environment, although the structure of the coated metal tube heat exchanger is similar to that of the traditional metal heat exchanger, it still has its own unique internal structure. However, the current metal coated tube heat exchanger still has the following structural problems:
[0007] 1) The coated metal tube is generally composed of two parts. The internal heat exchange tube is made of metal tube, and the heat exchange tube is coated with a layer of fluoroplastic (or other highly corrosion-resistant materials). Due to the different expansion coefficients of metal and fluoroplastic, when the temperature inside and outside the heat exchange tube changes, the expansion amount of the two materials is different, and a gap may occur between the coating layer and the end of the metal tube, affecting its normal and stable use.
[0008] 2) Heat exchange tubes are generally made of metal tubes, and the outer coating of the heat exchange tubes is generally made of fluoroplastics (or other highly corrosion-resistant materials). Metal tubes are generally connected by welding, which will generate extremely high temperatures. The external fluoroplastic coating generally has poor heat resistance, and the internal metal tube connection is easy to affect the external fluoroplastic coating.
[0009] 3) There is a certain gap between the heat exchanger tube sheet and the heat exchanger tube. The traditional welding process has a large workload and there are still incomplete welding and gaps at the connection between the heat exchange tube and the tube sheet in places where the tubes are densely packed. It is easy to cause the flue gas outside the heat exchanger tube to mix with the medium inside the tube, increase the pollutant content in the exhaust gas at the tail of the boiler, and reduce the stability of the heat exchanger, increasing safety hazards.
[0010] 4) The heat exchanger is installed on the flue when in use, because the installation location is generally close to the induced draft fan. Affected by its vibration, there is a certain friction between the heat exchange tube and the tube sheet. Long-term friction can easily cause the fluoroplastic layer on the outside of the heat exchange tube to rupture, and the metal tube to be directly exposed to the flue gas, so that the outer wall of the metal tube is corroded by the flue gas, increasing the safety hazard of the heat exchanger.
[0011] Therefore, we proposed a connection structure between metal tube and tube sheet to solve the problem. Utility Model Content
[0012] The utility model aims to provide a connection structure between a metal tube and a tube sheet, which solves the problems in the above-mentioned background technology.
[0013] In order to achieve the above-mentioned purpose, the utility model provides the following technical solutions: a connection structure between a metal tube and a tube sheet, comprising:
[0014] A metal tube is arranged longitudinally, wherein the outer wall of the metal tube is respectively covered with an inner membrane and an outer membrane, and the outer membrane is arranged outside the inner membrane;
[0015] A tube sheet, the top surface of which has tube holes arranged thereon;
[0016] Wherein, the metal tube is inserted into the tube hole on the tube plate.
[0017] Preferably, the inner membrane is a fluoroplastic layer.
[0018] Preferably, the outer film is made of a fluoroplastic layer. By setting the outer film, its own ductility can be utilized, and the outer end can be extended to a limiting ring to prevent the metal tube and the inner film from having different expansion coefficients and relative displacement under the influence of temperature, resulting in falling off.
[0019] Preferably, both ends of the tube hole are provided with a break, and two slots are provided at the center of the tube hole, and the two slots are chamfered. By providing the break at both ends of the tube hole, the loss of the outer membrane due to friction between the metal tube and the tube sheet can be effectively avoided. By providing the slot at the center of the tube hole, the metal tube can be expanded, which effectively avoids the mutual penetration of the media on both sides of the heat exchanger and effectively prevents the discharge of pollutants.
[0020] The utility model provides a connection structure between a metal tube and a tube sheet. The connection structure between a metal tube and a tube sheet has the following beneficial effects:
[0021] (1) The utility model utilizes the coating form of inner film and outer film to effectively prevent direct contact between flue gas and metal tubes, thereby avoiding low-temperature corrosion of the heat exchange tubes.
[0022] (2) The utility model adopts a connection method between metal heat exchange tubes and tube sheets, which replaces the welding work required by the original heat exchanger, greatly simplifies the connection form of the heat exchanger tubes, reduces the workload required for the manufacture of the heat exchanger, and simplifies the connection method between the heat exchanger tube sheet and the heat exchanger tubes. The operation is simple and not prone to human deviation, which effectively increases the reliability of the heat exchanger operation.
[0023] (3) The utility model slots holes at the tube holes of the tube sheet and adds grooves to reduce the friction between the metal tube sheet and the fluoroplastic film on the outer layer of the metal tube, thereby preventing the outer layer of the metal tube from rupturing and damaging the metal cladding tube. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 The utility model is a schematic diagram of a planar cross-sectional structure of a connection structure between a metal tube and a tube sheet.
[0025] In the figure: 1. metal tube, 2. inner membrane, 3. outer membrane, 4. tube hole, 5. tube plate, 6. slot hole. DETAILED DESCRIPTION
[0026] In order to have a clearer understanding of the technical features, purposes and effects of the utility model, the specific implementation methods of the utility model are now described with reference to the accompanying drawings.
[0027] A preferred embodiment of the connection structure between a metal tube and a tube sheet provided by the utility model is as follows Figure 1 As shown:
[0028] A connection structure between a metal tube and a tube sheet, comprising:
[0029] The metal tube 1 is arranged longitudinally, and the outer wall of the metal tube 1 is respectively covered with an inner film 2 and an outer film 3, and the outer film 3 is arranged outside the inner film 2. Here, the inner film 2 and the outer film 3 are both made of fluoroplastic layer, and the specific film thickness is determined according to the use conditions;
[0030] The tube sheet 5 has a tube hole 4 on the top surface, both ends of the tube hole 4 have a break, and two slots 6 are arranged at the center of the tube hole 4, and the two slots 6 have a chamfered arrangement;
[0031] The metal tube 1 is inserted into the tube hole 4 on the tube plate 5 .
[0032] In the specific implementation process, the tube hole 4 is opened on the tube sheet 5, and the two ends of the tube hole 4 are beveled to avoid the inner film 2 and the outer film 3 outside the metal tube 1 from being damaged when the heat exchanger is used, thereby reducing the service life of the heat exchanger. The surface of the tube hole 4 is provided with a slot 6, and here, the slot 6 is divided into two places, and each slot 6 is provided with a chamfer at both ends. Here, the slot 6 is mainly used to expand the inner film 2 and the outer film 3 to the slot 6 when the metal tube 1 is expanded, so as to achieve a sealing effect, so as to prevent the heating medium outside the metal tube 1 from invading the external environment along the tube sheet 5 and affecting the environment, and to play a certain degree of limiting role, so as to prevent the inner film 2 and the outer film 3 from swinging and falling off due to the impact of flue gas when the heat exchanger is normally used, thereby affecting the stability of the use of the heat exchanger;
[0033] Here, the inner film 2 is coated on the metal tube 1 by a coating process and is used as a coated metal heat exchange tube. In other locations where friction may occur with the metal tube sheet, support plate, etc., the inner film 2 may be broken due to friction, resulting in direct contact between the flue gas and the metal tube, causing corrosion. Therefore, an outer film 3 is added at a location prone to friction with the outside world to enhance the stability of the inner film 2. The outer edge of the outer film 3 extends to form a barrier core, further reducing the impact of the flue gas on the surrounding environment along the pores. Then, the metal tube 1 coated with the inner film 2 and the outer film 3 is Figure 1 Inserted into the tube hole 4 on the tube sheet 5, both ends of the tube hole 4 are provided with a break to prevent the metal tube 1 covered with the inner membrane 2 and the outer membrane 3 from scratching the inner membrane 2 and the outer membrane 3 outside the metal tube 1 when inserted, causing them to fall off or create a gap. After the metal tube 1 is inserted into the tube sheet, the outer membrane 3 uses the extension characteristics of the fluoroplastic itself to form a barrier ring on the outside of the tube sheet to prevent smoke from invading the surrounding environment through the hole gap. At the same time, it can also play a limiting role to prevent the metal tube 1, the inner membrane 2, and the outer membrane 3 from being displaced from each other during expansion and operation. At the same time, it can reduce the influence of the heat generated when the metal tube end is beveled or welded on the inner membrane 2;
[0034] After the above steps are completed, the metal tube 1 is expanded and deformed, and the connection with the tube sheet 5 is completed. The new connection method has a simple structure and is easy to operate, which can effectively avoid the occurrence of "tube drop" due to operational problems; and enhances the sealing between the metal tube 1 and the tube sheet 5. After the metal tube 1 is connected to the tube sheet 5, it can be welded with other equipment without affecting the integrity of the original metal tube coating film.
[0035] The above description is only an illustrative specific implementation method of the utility model, and is not intended to limit the scope of the utility model. Any equivalent changes and modifications made by any technician in this field without departing from the concept and principle of the utility model should fall within the scope of protection of the utility model. It should also be noted that the various components of the utility model are not limited to the above-mentioned overall application. The various technical features described in the specification of the utility model can be selected for use alone or in combination according to actual needs. Therefore, the utility model should naturally cover other combinations and specific applications related to the utility model points of this case.
Claims
1. A connection structure between a metal tube and a tube sheet, characterized in that: include: A metal tube (1) is arranged longitudinally, the outer wall of the metal tube (1) is respectively covered with an inner membrane (2) and an outer membrane (3), and the outer membrane (3) is arranged outside the inner membrane (2); A tube sheet (5) having tube holes (4) arranged on the top surface; The metal tube (1) is inserted into the tube hole (4) on the tube plate (5).
2. The connection structure of a metal tube and a tube sheet according to claim 1, characterized in that: The inner membrane (2) is a fluoroplastic layer.
3. The connection structure of a metal tube and a tube sheet according to claim 1, characterized in that: The outer film (3) is a fluoroplastic layer.
4. The connection structure of a metal tube and a tube sheet according to claim 1, characterized in that: The two ends of the tube hole (4) are provided with broken openings, and two slots (6) are provided at the center of the tube hole (4), and the two slots are chamfered.