Sealing structure of floating head type heat exchanger

Abstract

The invention discloses a floating head type heat exchanger sealing structure which comprises a floating tube plate, a main bolt, a main nut, a sealing gasket, a double-cone ring, a supporting ring, a floating head flange and a spherical crown-shaped sealing head. An annular boss is arranged on the floating tube plate, a boss side oblique cone sealing face is machined on the inner side of the annular boss, a flange side oblique cone sealing face symmetrical to the boss side oblique cone sealing face is machined on the inner side of the floating head flange, and a double-cone ring is arranged between the boss side oblique cone sealing face and the flange side oblique cone sealing face. Sealing gaskets are arranged between the two conical sealing surfaces of the double-conical ring and the corresponding boss-side oblique conical sealing surface and the flange-side oblique conical sealing surface, and the double-conical ring is supported by a supporting ring; the floating tube plate and the floating head flange are connected through the main bolt and the main nut. The floating head type heat exchanger effectively solves the problem that the floating head type heat exchanger is extremely prone to leakage in high-temperature, high-pressure and pressure and temperature fluctuation occasions, the sealing structure is good in reliability, and installation and overhaul are convenient.

Description

Technical Field

[0001] This invention belongs to the field of heat exchangers in industries such as petrochemicals, coal chemicals, fine chemicals, and power, and specifically relates to a floating head heat exchanger sealing structure. Background Technology

[0002] Floating head heat exchangers are a widely used type of heat exchange equipment. The tube bundle of a floating head heat exchanger consists of two tube sheets. One end of the tube sheet is fixed by a flange and fasteners, called the fixed end, while the other end can float freely within the shell, called the floating head end. The floating head end structure includes components such as the floating tube sheet, hook ring, floating head flange, floating head cover, floating head bolts, and floating head gaskets.

[0003] The main characteristics of floating head heat exchangers include: 1) the tube bundle can be extracted for easy cleaning and maintenance; 2) the tube bundle can expand freely within the shell, suitable for applications with large temperature differences between the shell and tube sides; 3) suitable for applications with severe tube-side corrosion; and 4) low tube-side pressure drop. The main disadvantages of floating head heat exchangers include: 1) potential leakage at the floating head end seal; 2) relatively complex structure and higher cost; and 3) the impact of the medium on the sealing performance of the floating head end must be carefully considered when shell-side corrosion is severe.

[0004] The sealing between the tube side and shell side of a floating head heat exchanger is achieved through a gasket between the floating head flange and the tube sheet. The floating head gasket is usually a corrugated composite gasket or a spiral wound gasket. Under conditions of high pressure and temperature, large heat exchanger diameter, or pressure and temperature fluctuations, a higher gasket sealing pressure is required. However, under these conditions, the sealing and resilience performance of such gaskets is insufficient, resulting in insufficient sealing pressure on the surface of the floating head gasket. This leads to seal failure and leakage between the tube side and shell side, which can cause equipment shutdown in severe cases. Summary of the Invention

[0005] To address the problem of insufficient sealing pressure on the surface of the floating head gasket in existing technologies, which leads to seal failure and leakage between the tube side and the shell side, this invention provides a sealing structure for a floating head heat exchanger.

[0006] The floating head heat exchanger sealing structure provided by this invention includes a floating tube sheet, main bolts and main nuts, sealing gaskets, double cone rings, support rings, a floating head flange, and a spherical head. An annular boss is provided on the floating tube sheet, with a boss-side oblique cone sealing surface machined on the inner side of the annular boss. A flange-side oblique cone sealing surface symmetrical to the boss-side oblique cone sealing surface is machined on the inner side of the floating head flange. A double cone ring is provided between the boss-side oblique cone sealing surface and the flange-side oblique cone sealing surface. Sealing gaskets are provided between the two conical sealing surfaces of the double cone ring and their respective corresponding boss-side oblique cone sealing surfaces and flange-side oblique cone sealing surfaces. The double cone ring is supported by a support ring. The floating tube sheet and the floating head flange are connected by main bolts and main nuts.

[0007] The double-cone seal is a semi-self-tightening seal with radial self-tightening action. In use, tightening the main bolts causes the gasket lining the conical sealing surface of the double-cone ring to contact and press against the oblique conical sealing surfaces of the boss and flange sides. Supported by the support ring, the double-cone ring maintains sufficient rigidity, ensuring the gasket on the conical sealing surface achieves sufficient sealing pressure and provides a good seal. Simultaneously, the double-cone ring undergoes radial contraction, pressing tightly against the outside of the support ring. When the pressure increases, the floating head assembly, composed of the floating flange and the spherical head, tends to lift upwards under the pipe-side pressure, causing the sealing pressure on the conical sealing surface to decrease. Under internal pressure, the double-cone ring rebounds due to the radial contraction during pre-tightening, increasing the pressure on the conical sealing surface. The sealing pressure maintained on the conical sealing surface should exceed the sealing pressure required for the gasket's operation.

[0008] The sealing gasket can be a soft gasket or a soft metal wire. Soft gaskets include soft metal gaskets (copper, aluminum, stainless steel, etc.) and non-metallic gaskets such as flexible graphite.

[0009] The material of the double cone ring can be different from or the same as that of the floating tube sheet and the floating head flange.

[0010] The support ring and the floating head flange can be an integral structure or separate independent structures.

[0011] The main bolt can be tightened by extending it out of the floating tube plate and adding a nut, or by not extending it out of the floating tube plate and opening a screw hole on the tube plate.

[0012] As an improvement, a support ring is provided on the left side of the support ring. The support ring is fixed to the support ring by a positioning bolt and plays a positioning role for the double cone ring.

[0013] As an improvement, the two conical sealing surfaces of the double conical ring are provided with semi-circular or triangular grooves, the surface roughness Ra of the conical sealing surface is not greater than 3.2, and the number of grooves is preferably 1 to 3.

[0014] As an improvement, longitudinal grooves are formed on the outer cylindrical surface of the support ring, preferably 2 to 4 grooves.

[0015] As an improvement, the gap between the inner cylindrical surface of the double-conical ring and the support ring is controlled to be 0.075% to 0.125% of the diameter of the inner cylindrical surface of the double-conical ring.

[0016] Preferably, the annular boss structure of the floating tube sheet has an outer cylindrical surface that is slightly smaller than the inner diameter of the bolt hole.

[0017] This invention patent has the following advantages:

[0018] The adopted double-cone sealing structure possesses pressure-self-tightening sealing characteristics, effectively solving the problem of easy leakage in floating head heat exchangers under high temperature, high pressure, and pressure-temperature fluctuation conditions. The new sealing structure has high reliability and is easy to install and maintain. The double-cone sealing structure is relatively simple, not difficult to process, and easy to install and remove, making it suitable for high temperature, high pressure, and pressure-temperature fluctuation conditions. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of the present invention.

[0020] Figure 2 yes Figure 1 A partially enlarged schematic diagram of the double-cone sealing structure.

[0021] In the diagram: 1-Floating tube sheet, 2-Main bolt, 3-Main nut, 4-Sealing gasket, 5-Washer ring, 6-Double cone ring, 7-Floating head flange, 8-Positioning bolt, 9-Support ring, 10-Support ring, 11-Spherical crown head, 12-Heat exchange tube, 13-Annular boss, 14-Heat exchanger shell side, 15-Semi-circular groove. Detailed Implementation

[0022] See Figures 1-2 The floating head heat exchanger sealing structure of the present invention is located inside the shell-side shell 14 of the heat exchanger and includes a floating tube sheet 1, main bolts 2, main nuts 3, sealing gaskets 4, washers 5, double cone rings 6, a floating head flange 7, positioning bolts 8, support rings 9, support rings 10, and a spherical crown-shaped end cap 11. The floating head flange 7 and the spherical crown-shaped end cap 11 together constitute the floating head cover. Heat exchange tubes 12 are provided on the floating tube sheet 1.

[0023] An annular boss 13 is provided on the floating tube sheet 1. The annular boss 13 is formed by integral forging of the floating tube sheet 1 and then machining, or it is welded onto the floating tube sheet 1 as a part to form an integral structure. The inner side of the annular boss 11 is machined with a boss-side oblique cone sealing surface, and the roughness of the sealing surface is controlled to be no greater than Ra3.2. The inner side of the floating head flange 7 is machined with a flange-side oblique cone sealing surface, and the roughness of the sealing surface is controlled to be no greater than Ra3.2.

[0024] A double-cone ring 6 is installed between the symmetrically arranged oblique conical sealing surfaces of the boss side and the flange side. Sealing gaskets 4 are installed between the two conical sealing surfaces of the double-cone ring 6 and their respective corresponding oblique conical sealing surfaces of the boss side and flange side. Semi-circular grooves 15 are provided on the conical sealing surfaces. The double-cone ring 6 is supported by a support ring 10. The floating tube sheet 1 and the floating head flange 7 are connected by main bolts 2, washers 5, and main nuts 3. The roughness of the conical sealing surface of the double-cone ring 6 is controlled to be no greater than Ra3.2, and the flatness of the top and bottom planes of the double-cone ring is controlled.

[0025] The gap between the inner cylindrical surface of the double-cone ring 6 and the support ring 10 is controlled to be 0.075% to 0.125% of the diameter of the inner cylindrical surface of the double-cone ring 6. The support ring 9 is connected to the support ring 10 using positioning bolts 8, and the flatness of the support ring 9 is controlled so that its side is flush with and in contact with the adjacent side of the double-cone ring 6. An annular gap is left between the support ring 10 and the floating head flange 7, or the support ring 10 and the floating head flange 7 can be manufactured as an integral forging.

[0026] The floating tube sheet 1, double cone ring 6, and floating head flange 7 are connected and tightened by the main bolt 2, main nut 3, and washer 5. The required preload is formed on the conical sealing surface of the double cone ring 6. The required preload is calculated to form an effective seal between the tube side and the shell side of the heat exchanger floating head end.

Claims

1. A seal structure for a floating head heat exchanger, characterized by: The sealing gasket is a soft gasket or a soft metal wire.

2. The seal structure for a floating head heat exchanger according to claim 1, characterized by: The soft gasket is a soft metal gasket or a non-metal gasket flexible graphite.

3. The seal structure of a floating head heat exchanger according to claim 2, characterized by: The double-tapered ring is made of the same material as the floating tube plate and the floating head flange.

4. The seal structure of a floating head heat exchanger according to claim 1, characterized by: The support ring and the floating head flange are in an integral structure or are independent structures.

5. The seal structure of a floating head heat exchanger according to claim 1, characterized by: The support ring is provided with a supporting ring on the left side.

6. The seal structure of a floating head heat exchanger according to claim 1, characterized by: The double-tapered ring is provided with semicircular or triangular grooves on the two tapered sealing surfaces.

7. The seal structure for a floating head heat exchanger according to any one of claims 1 to 6, characterized by: The support ring is provided with a longitudinal groove on the outer cylindrical surface.

8. The seal structure for a floating head heat exchanger according to any one of claims 1 to 6, characterized by: The gap between the inner cylindrical surface of the double-tapered ring and the support ring is 0.075% to 0.125% of the diameter of the inner cylindrical surface of the double-tapered ring.

9. The seal structure for a floating head heat exchanger according to any one of claims 1 to 6, characterized by: The roughness Ra of the tapered sealing surface of the double-tapered ring is not greater than 3.

2.

10. The seal structure for a floating head heat exchanger according to any one of claims 1 to 6, characterized by: ​

Images