Flat glass tube type air preheater for ultralow-temperature flue gas waste heat recovery

Abstract

The utility model relates to a flat glass tube type air preheater for ultralow temperature flue gas waste heat recovery, which comprises an air preheater shell, a flat glass tube bundle and a limit support rod assembly are arranged in the air preheater shell, the flat glass tube bundle is in a flat key shape, and the limit support rod assembly is arranged in the middle of the flat glass tube bundle. According to the ultra-low temperature air preheater, the section of the glass heat exchange tube in the air preheater is designed into the flat key type flat tube shape, the limiting supporting rod assembly is arranged in the middle of the flat glass tube bundle, and the double-layer sealing structure is arranged between the flat glass tube bundle and the metal tube plate, so that the ultra-low temperature air preheater obtains better sealing performance and anti-seismic performance, and the service life of the ultra-low temperature air preheater is prolonged. And meanwhile, the air preheater can stably operate for a long time when the flue gas temperature is lower than the acid dew point temperature.

Description

Technical Field

[0001] The utility model relates to the technical fields of petroleum refining, petrochemical industry and coal chemical industry, and specifically relates to a flat glass tube air preheater for recovering waste heat from ultra-low temperature flue gas, which is applied to waste heat recovery systems of heating furnaces in the petroleum refining, petrochemical industry and coal chemical industry. Background Art

[0002] With the tightening of national environmental protection policies, the exhaust temperature of heating furnaces is required to be designed as low as possible. Most requirements now reduce the exhaust temperature of heating furnaces to 100°C or even below 100°C. The lower the exhaust temperature of the heating furnace, the higher its thermal efficiency. Ultra-low temperature air preheaters are generally used under operating conditions where the flue gas temperature is below 100°C. However, when the exhaust temperature is lower than the flue gas acid dew point, a large amount of acidic condensate containing dilute sulfuric acid will precipitate from the flue gas. This acidic condensate will corrode the air preheater, affecting the long-term stable operation of the air preheater and even the entire device.

[0003] At present, the ultra-low temperature air preheaters used in the domestic petroleum refining, petrochemical and coal chemical industries mostly use glass round tubes, which have the following defects:

[0004] The heat exchange area is small and the resistance along the way is large;

[0005] The glass tube is only assembled with the tube sheet at its two ends, and there is no support in the middle of the glass tube. Under conditions of strong vibration, the glass tube is easy to break;

[0006] The end of the glass round tube and the tube sheet cannot be sealed by welding, and the sealing performance is poor. Utility Model Content

[0007] The purpose of the present utility model is to overcome the above-mentioned shortcomings and provide a flat glass tube air preheater for ultra-low temperature flue gas waste heat recovery. By designing the cross-section of the glass heat exchange tube inside the air preheater into a flat tube shape of a flat key type, a special-shaped glass tube with high strength, large heat exchange area, small resistance along the way and simple installation process is obtained. At the same time, the end sealing structure and the limit support structure of the special-shaped glass tube are innovated, so that the ultra-low temperature air preheater obtains better sealing performance and seismic resistance, and at the same time ensures that the air preheater can operate stably for a long time when the flue gas temperature is lower than the acid dew point temperature.

[0008] The purpose of this utility model is achieved in this way:

[0009] A flat glass tube air preheater for ultra-low temperature flue gas waste heat recovery comprises an air preheater shell, wherein a flat glass tube bundle and a limit support rod assembly are arranged in the air preheater shell, wherein a plurality of flat glass tube bundles are arranged in an array in the air preheater shell, wherein both ends of the flat glass tube bundle are supported and fixed in the air preheater shell by metal tube plates, wherein the flat glass tube bundle is in a flat key shape, wherein a limit support rod assembly is arranged in the middle of the flat glass tube bundle, wherein the limit support rod assembly comprises supporting square steel, a metal tie rod and a PTFE sleeve, wherein a metal tie rod is arranged between each two adjacent rows of flat glass tube bundles, wherein the metal tie rod with the PTFE sleeve is vertically inserted into the supporting square steel, and both ends are locked and fixed to the supporting square steel with nuts and washers, and the supporting square steel is fixed to the air preheater shell.

[0010] Preferably, a plurality of supporting square steels are provided in the air preheater shell at intervals along the height direction, and the supporting square steels are provided with circular holes corresponding to the metal pull rods.

[0011] Preferably, the supporting square steel is arranged horizontally and longitudinally, and is perpendicular to the length direction of the flat glass tube bundle.

[0012] Preferably, a double-layer sealing structure is provided between the flat glass tube bundle and the metal tube sheet, and the double-layer sealing structure includes a flexible graphite rope, a high-temperature sealant and a pressure plate. The end of the flat glass tube bundle extends out of the corresponding metal tube sheet, and the metal tube sheet is provided with a step hole corresponding to the flat glass tube bundle. Flexible graphite rope and high-temperature sealant are installed in the large-diameter hole section outside the step hole. The pressure plate is pressed outside the high-temperature sealant and is tightened and fixed to the metal tube sheet by screws.

[0013] Preferably, the metal tube sheet is welded together by an inner tube sheet and an outer tube sheet, both the inner and outer tube sheets have holes, and the hole size of the outer tube sheet is larger than that of the inner tube sheet, thereby forming a stepped hole with a large outer aperture.

[0014] The beneficial effects of the utility model are:

[0015] By designing the cross section of the glass heat exchange tube inside the air preheater into a flat tube shape, a special-shaped glass tube with high strength, large heat exchange area, small resistance along the way and simple installation process is obtained;

[0016] A metal tie rod is installed between each two adjacent rows of flat glass tube bundles to limit and support the flat glass tube bundles, reducing the vibration of the weak side strength direction of the glass tubes during the operation of the air preheater. The metal tie rod is made of metal and is covered with a PTFE sleeve to ensure non-rigid contact between the metal tie rod and the flat glass tube bundle, avoiding the risk of the flat glass tube bundle being broken during the operation of the air preheater. This composite structure has both high strength and high corrosion resistance.

[0017] A double-layer sealing structure is set between the flat glass tube bundle and the metal tube sheet. The flexible graphite rope is pressed into the large-diameter hole section of the step hole to form the first layer of sealing. The outside of the flexible graphite rope is coated with high-temperature sealant to form the second layer of sealing. The pressure plate is pressed outside the high-temperature sealant and is tightened to the metal tube sheet by screws. The pressure plate protects and compresses the sealing filler in the step hole, so that the ultra-low temperature air preheater obtains better sealing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a schematic diagram of the appearance and structure of a flat glass tube air preheater for ultra-low temperature flue gas waste heat recovery in the utility model.

[0019] Figure 2 for Figure 1 side view.

[0020] Figure 3 This is a schematic diagram of the internal structure of a flat glass tube air preheater for ultra-low temperature flue gas waste heat recovery in the utility model.

[0021] Figure 4 for Figure 3 Top view of .

[0022] Figure 5 for Figure 3 sectional view of .

[0023] Figure 6 Schematic diagram of the double-layer sealing structure at the end of the flat glass tube bundle.

[0024] Figure 7 Schematic diagram of the structure of the pressure plate.

[0025] in:

[0026] Air preheater shell 1; flat glass tube bundle 2; limit support rod assembly 3; support square steel 3.1; metal pull rod 3.2; PTFE sleeve 3.3; nut 3.4; washer 3.5; metal tube sheet 4; inner tube sheet 4.1; outer tube sheet 4.2; flexible graphite rope 5; high-temperature sealant 6; pressure plate 7; tube bundle through hole 7.1; screw 8. DETAILED DESCRIPTION

[0027] See also Figure 1-7The utility model relates to a flat glass tube air preheater for ultra-low temperature flue gas waste heat recovery, comprising an air preheater shell 1, wherein a flat glass tube bundle 2 and a limiting support rod assembly 3 are arranged in the air preheater shell 1, wherein a plurality of flat glass tube bundles 2 are arranged in an array in the air preheater shell 1, wherein the flat glass tube bundle 2 is in a flat key shape and has two mutually parallel planes, which has a larger heat exchange area and a smaller resistance along the way, wherein the two ends of the flat glass tube bundle 2 are supported and fixed in the air preheater shell 1 by a metal tube sheet 4, a limiting support rod assembly 3 is provided in the middle of the flat glass tube bundle 2, and a double-layer sealing structure is provided between the flat glass tube bundle 2 and the metal tube sheet 4, wherein the limiting support rod assembly 3 comprises a supporting square steel 3.1, a metal tie rod 3.2 and a PTFE sleeve 3.3, and a metal tie rod 3.2 is provided between each two adjacent rows of flat glass tube bundles 2, and the metal tie rod 3.2 The air preheater housing 1 is provided with a plurality of support square steels 3.1 spaced along the height thereof to limit and secure the ends and middle of the metal tie rods 3.2. The support square steels 3.1 are arranged horizontally and longitudinally, perpendicular to the lengthwise direction (horizontally) of the flat glass tube bundle 2. The support square steels 3.1 are provided with circular holes corresponding to the metal tie rods 3.2. The metal tie rods 3.2 are covered with PTFE sleeves 3.3. The PTFE sleeves 3.3 ensure non-rigid contact between the metal tie rods 3.2 and the flat glass tube bundle 2, thereby preventing the risk of breakage of the flat glass tube bundle 2 during operation of the air preheater. The metal tie rods 3.2, covered with PTFE sleeves 3.3, are vertically inserted into the circular holes of the support square steels 3.1 and secured to the support square steels 3.1 at both ends with nuts 3.4 and washers 3.5.

[0028] The double-layer sealing structure includes a flexible graphite rope 5, a high-temperature sealant 6, and a pressure plate 7. The ends of the flat glass tube bundle 2 extend out of the corresponding metal tube sheet 4. The metal tube sheet 4 is provided with a stepped hole corresponding to the flat glass tube bundle 2. The flexible graphite rope 5 and the high-temperature sealant 6 are installed in the large-diameter hole section outside the stepped hole. The flexible graphite rope 5 is pressed into the large-diameter hole section of the stepped hole to form a first layer of sealing. The high-temperature sealant 6 is applied to the outside of the flexible graphite rope 5 to form a second layer of sealing. The pressure plate 7 is pressed outside the high-temperature sealant 6 and is tightened to the metal tube sheet 4 by screws 8. The pressure plate protects and compresses the sealing filler in the stepped hole.

[0029] The pressing plate 7 is provided with a tube bundle through hole 7 . 1 corresponding to the flat glass tube bundle 2 , and the tube bundle through hole 7 . 1 matches the cross section of the flat glass tube bundle 2 .

[0030] A plurality of pressing plates 7 are provided at the ends of the flat glass tube bundles 2 , and each row of flat glass tube bundles 2 shares one pressing plate 7 .

[0031] The metal tube sheet 4 is welded together from an inner tube sheet 4.1 and an outer tube sheet 4.2. Both inner and outer tube sheets 4.1 and 4.2 have openings, with the opening in the outer tube sheet 4.2 being larger than that in the inner tube sheet 4.1, thus forming a stepped hole with a larger outer diameter. Because the flat glass tube bundle 2 has a flat key-shaped cross-section, the openings can be laser-cut to the cross-sectional dimensions of the flat glass tube bundle. This not only reserves space for installing sealing packing but also reduces the difficulty of machining the metal tube sheet.

[0032] In addition to the above embodiments, the present invention also includes other implementation methods. Any technical solutions formed by equivalent transformation or equivalent replacement should fall within the scope of protection of the claims of the present invention.

Claims

1. A flat glass tube air preheater for ultra-low temperature flue gas waste heat recovery, comprising an air preheater housing, a flat glass tube bundle and a limit support rod assembly disposed within the air preheater housing, a plurality of flat glass tube bundles arranged in an array within the air preheater housing, and both ends of the flat glass tube bundles supported and fixed within the air preheater housing by metal tube sheets, characterized in that: The flat glass tube bundle is flat-key shaped, and a limit support rod assembly is provided in the middle of the flat glass tube bundle. The limit support rod assembly includes supporting square steel, a metal tie rod and a PTFE sleeve. A metal tie rod is provided between each two adjacent rows of flat glass tube bundles. The metal tie rod with the PTFE sleeve is vertically inserted into the supporting square steel, and both ends are locked and fixed to the supporting square steel with nuts and washers. The supporting square steel is fixed to the air preheater shell.

2. The flat glass tube air preheater for ultra-low temperature flue gas waste heat recovery according to claim 1, characterized in that: A plurality of supporting square steels are arranged in the air preheater shell at intervals along the height direction, and the supporting square steels are provided with round holes corresponding to the metal pull rods.

3. The flat glass tube air preheater for ultra-low temperature flue gas waste heat recovery according to claim 1 or 2, characterized in that: The supporting square steel is arranged horizontally and longitudinally, and is perpendicular to the length direction of the flat glass tube bundle.

4. The flat glass tube air preheater for ultra-low temperature flue gas waste heat recovery according to claim 1, characterized in that: A double-layer sealing structure is provided between the flat glass tube bundle and the metal tube sheet. The double-layer sealing structure includes a flexible graphite rope, a high-temperature sealant, and a pressing plate. The ends of the flat glass tube bundle extend out of the corresponding metal tube sheet. The metal tube sheet is provided with a stepped hole corresponding to the flat glass tube bundle. Flexible graphite rope and high-temperature sealant are installed in the large-diameter hole section outside the stepped hole. The pressing plate is pressed outside the high-temperature sealant and is tightened to the metal tube sheet by screws.

5. The flat glass tube air preheater for ultra-low temperature flue gas waste heat recovery according to claim 4, characterized in that: The metal tube sheet is welded together by an inner tube sheet and an outer tube sheet. Both the inner and outer tube sheets have holes, and the hole size of the outer tube sheet is larger than that of the inner tube sheet, thereby forming a stepped hole with a large outer diameter.

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