Improved boiler lower-stage air preheater

Abstract

The utility model discloses an improved boiler lower-stage air preheater, which belongs to the technical field of boiler equipment and comprises an upper-group tube box structure and a lower-group tube box structure. Wherein the upper-group tube box structure is formed by connecting a plurality of upper-group tube boxes, a plurality of upper-group heat exchange tubes are vertically mounted in the upper-group tube boxes, the upper-group heat exchange tubes penetrate through the top ends and the bottom ends of the upper-group tube boxes, the upper-group heat exchange tubes are made of Cowden steel, partition plates are welded in the upper-group tube boxes, and the partition plates are vertically arranged. The lower-group tube box structure is formed by connecting a plurality of lower-group tube boxes, a plurality of lower-group heat exchange tubes are horizontally installed in the lower-group tube boxes, the two ends of each lower-group heat exchange tube are communicated with the air inlet and the air communicating tube respectively, and the lower-group heat exchange tubes are enamel coton tubes. The utility model solves the problems that the lower-stage air preheater of the boiler is easy to generate resonance noise and the heat exchange tube is easy to damage.

Description

Technical Field

[0001] The utility model relates to the technical field of boiler equipment, in particular to an improved boiler lower-stage air preheater. Background Art

[0002] Sugar refinery boilers are designed to use bagasse as fuel. During the crushing season, they primarily burn the pith of the crushed sugarcane, generating high-temperature superheated steam that powers the turbine-generator. The back-pressure steam from this generation is then used entirely for sugar production. During the crushing season, self-generated electricity can meet sugar production needs and even generate a surplus. Therefore, the safety and cost-effectiveness of sugar refinery bagasse boilers play a critical role in the safety and cost-effectiveness of sugar production.

[0003] The air preheater is one of the important components of the boiler system equipment. Severe leakage and damage will directly affect the safe and economical operation of the boiler, significantly reduce the boiler's operating output and combustion thermal efficiency, and at the same time increase the energy consumption of the induced draft equipment, affecting the boiler's flue gas emission standards, and also affecting the normal operation of the supporting bag dust removal equipment.

[0004] Traditional tubular air preheaters generally include an upper air preheater and a lower air preheater. The lower air preheater further includes a lower upper group air preheater pipe box and a lower lower group air preheater pipe box. The cold air inlet is connected to the lower lower group air preheater pipe box, which is connected to the lower upper group air preheater pipe box. The lower upper group air preheater pipe box is connected to the upper air preheater to achieve air flow conduction. The lower upper group air preheater pipe box is arranged vertically and is equipped with multiple pipe boxes, each of which contains a number of heat exchange tubes. The lower lower group air preheater pipe box is arranged horizontally and is equipped with multiple pipe boxes, each of which contains a number of heat exchange tubes.

[0005] However, the above-mentioned boiler downstream air preheater has the following defects: (1) The heat exchange tubes are generally thin-walled and made of metal, which is easily damaged by low-temperature corrosion and perforation, reducing the service life of the air preheater; (2) It is easy to resonate with the tail flue, generating loud noise; vibration of tubular air preheaters is a common phenomenon, and the air pressure vibration caused by the Karman vortex effect is the root cause of the vibration of tubular air preheaters. Therefore, it is necessary to improve the above-mentioned boiler downstream air preheater. Utility Model Content

[0006] The utility model provides an improved boiler lower-stage air preheater to solve the problems that the boiler lower-stage air preheater is prone to generate resonance noise and the heat exchange tube is easily damaged.

[0007] In order to achieve the above-mentioned purpose, the technical solution adopted by the present utility model is:

[0008] An improved boiler lower-stage air preheater comprises an upper tube box structure and a lower tube box structure, wherein the upper tube box structure is located directly above the lower tube box structure, the upper tube box structure adopts a vertical tube box arrangement, and the lower tube box structure adopts a horizontal tube box arrangement; one side of the lower tube box structure is an air inlet, and the other side is connected to one side of the upper tube box structure via an air connecting pipe; the other side of the upper tube box structure is an air outlet; the top end of the upper tube box structure is a flue gas inlet, and the bottom end is connected to the top end of the lower tube box structure via a flue; the bottom end of the lower tube box structure is a flue gas outlet;

[0009] The upper tube box structure is composed of a plurality of upper tube boxes connected together. A plurality of upper heat exchange tubes are vertically installed in each of the upper tube boxes. The upper heat exchange tubes pass through the top and bottom ends of the upper tube boxes. The material of the upper heat exchange tubes is Corten steel. Partitions are welded in each of the upper tube boxes and are vertically arranged.

[0010] The lower group tube box structure is composed of multiple lower group tube boxes connected together, and a number of lower group heat exchange tubes are horizontally installed in the lower group tube boxes. The two ends of the lower group heat exchange tubes are respectively connected to the air inlet and the air connecting pipe. The lower group heat exchange tubes are enameled Corton tubes.

[0011] Furthermore, a first pipe box expansion joint is provided at the smoke inlet of the upper pipe box structure.

[0012] Furthermore, a second pipe box expansion and contraction joint is provided at the air inlet of the lower pipe box structure.

[0013] Furthermore, a third pipe box expansion and contraction joint is provided on the top of the lower pipe box structure.

[0014] Furthermore, the outer enamel thickness of the enameled Corton tube is 0.2-0.5 mm.

[0015] Furthermore, the box body materials of the upper group pipe box and the lower group pipe box are both A3 steel.

[0016] Furthermore, the upper group of heat exchange tubes is fixedly installed in the upper group tube box through at least two first orifice plates, the first orifice plates are arranged horizontally, and the lower group of heat exchange tubes is fixedly installed in the lower group tube box through at least two second orifice plates, the second orifice plates are arranged vertically.

[0017] Furthermore, the gaps between the upper group of heat exchange tubes and the first orifice plate and the gaps between the lower group of heat exchange tubes and the second orifice plate are sealed by welding.

[0018] Furthermore, 1-2 partitions are welded inside the upper tube box.

[0019] Furthermore, the air inlet is located directly below the air outlet and is arranged parallel to the air outlet.

[0020] Due to the adoption of the above technical solution, the utility model has the following beneficial effects:

[0021] 1. The upper heat exchange tubes of this utility model are made of Corten steel, which forms a dense, stable rust layer in atmospheric environments, preventing further corrosion. This provides excellent atmospheric corrosion resistance and extends the service life of the upper heat exchange tubes. The lower heat exchange tubes are made of enameled Corten steel, which significantly improves low-temperature corrosion resistance compared to ordinary carbon steel tubes, more than doubling their service life. At a price only approximately 50% higher than ordinary carbon steel tubes, this design offers excellent overall cost-effectiveness.

[0022] 2. The present invention incorporates vertically mounted baffles within each upper tube box, dividing the entire upper tube box structure into multiple air chambers. This increases the natural frequency of each chamber, preventing the frequency of the Karman vortex and the natural frequency of the chamber from coinciding, thereby avoiding acoustic resonance and effectively eliminating vibration. Furthermore, the present invention incorporates first, second, and third tube box expansion joints at the flue gas inlet, air inlet, and top of the lower tube box structure, respectively, to reduce the transmission of equipment vibration to surrounding structures. This design not only eliminates vibration but also reduces noise, ensuring efficient, long-term, safe, and stable operation of the air preheater. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of the improved boiler lower-stage air preheater proposed in an embodiment of the utility model;

[0024] Figure 2 A schematic diagram showing the connection between the upper and lower pipe box structures according to an embodiment of the present invention;

[0025] Figure 3 This is a schematic structural diagram of three pipe-box expansion and contraction joints proposed in an embodiment of the present utility model;

[0026] Among them, the markings in the accompanying drawings are: 1-upper group side pipe box, 2-upper group middle pipe box, 3-lower group side pipe box, 4-lower group middle pipe box, 5-first pipe box expansion and contraction joint, 6-second pipe box expansion and contraction joint, 7-third pipe box expansion and contraction joint, 8-air inlet, 9-air outlet, 10-air connecting pipe, 11-smoke inlet, 12-smoke outlet, 13-partition. DETAILED DESCRIPTION

[0027] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0028] Example

[0029] like Figure 1-3 As shown, an improved boiler lower-stage air preheater includes an upper tube box structure and a lower tube box structure. The upper tube box structure is located directly above the lower tube box structure. The upper tube box structure adopts a vertical tube box layout, and the lower tube box structure adopts a horizontal tube box layout.

[0030] One side of the lower pipe-box structure is an air inlet 8, and the other side is connected to one side of the upper pipe-box structure via an air connection pipe 10. The other side of the upper pipe-box structure is an air outlet 9. In this embodiment, the air inlet 8 is located directly below and parallel to the air outlet 9. The top of the upper pipe-box structure is a flue gas inlet 11, and the bottom is connected to the top of the lower pipe-box structure via a flue. The bottom of the lower pipe-box structure is a flue gas outlet 12.

[0031] The smoke inlet 11 of the upper pipe box structure is provided with a first pipe box expansion joint 5, the air inlet 8 of the lower pipe box structure is provided with a second pipe box expansion joint 6, and the top of the lower pipe box structure is provided with a third pipe box expansion joint 7. The first pipe box expansion joint 5, the second pipe box expansion joint 6 and the third pipe box expansion joint 7 have the same structure. The specific structure is as follows Figure 3 The arrangement of three pipe box expansion joints can reduce the transmission of equipment vibration to surrounding structures.

[0032] The upper tube box structure consists of multiple connected upper tube boxes, each of which houses a number of upper heat exchange tubes vertically mounted. Specifically, the upper heat exchange tubes are secured within the upper tube box via at least two horizontally positioned first orifice plates. The upper heat exchange tubes extend through the top and bottom ends of the upper tube box. The upper heat exchange tubes are constructed of Corten steel, and the first orifice plates are constructed of A3 steel. Vertically mounted baffles 13 are welded to the upper tube box. Preferably, one to two baffles 13 are welded to the upper tube box.

[0033] In this embodiment, the upper pipe box structure is composed of four connected upper pipe boxes. The four upper pipe boxes are: two upper side pipe boxes 1 located on either side, and two upper middle pipe boxes 2 located in the center. The internal length of the upper side pipe box 1 is 2240 mm, and the internal length of the upper middle pipe box 2 is 2320 mm. Each of the two upper side pipe boxes 1 is provided with a partition 13, and each of the two upper middle pipe boxes 2 is provided with two partitions 13, dividing the entire upper pipe box structure into seven air chambers. The spacing between the partition 13 in the upper side pipe box 1 and the closest partition 13 in the adjacent upper middle pipe box 2 is 1570 mm, the spacing between the two partitions 13 in the upper middle pipe box 2 is 1440 mm, and the spacing between the adjacent partitions 13 in the two upper middle pipe boxes 2 is 1250 mm.

[0034] The lower group tube box structure is composed of multiple lower group tube boxes connected together. The box materials of the upper group tube box and the lower group tube box are all A3 steel. Several lower group heat exchange tubes are horizontally installed in the lower group tube box. Specifically, the lower group heat exchange tubes are fixedly installed in the lower group tube box through at least two second orifice plates, and the second orifice plates are vertically arranged. The gap between the upper group heat exchange tubes and the first orifice plate and the gap between the lower group heat exchange tubes and the second orifice plate are sealed by welding. The two ends of the lower group heat exchange tubes are respectively connected to the air inlet 8 and the air connecting pipe 10. The lower group heat exchange tubes are enameled Corton tubes, and the outer enamel thickness of the enameled Corton tubes is 0.2-0.5mm. Preferably, the thickness is 0.3mm.

[0035] In this embodiment, the lower pipe box structure consists of four connected lower pipe boxes, each of which is vertically opposed to the four upper pipe boxes. The four lower pipe boxes are: two lower side pipe boxes 3 located on either side, and two lower middle pipe boxes 4 located in the center. The internal length of the lower side pipe boxes 3 is 2241 mm, and the internal length of the lower middle pipe box 4 is 2324 mm.

[0036] The upper heat exchange tubes of this utility model are made of Corten steel, which forms a dense, stable rust layer in atmospheric environments, preventing further corrosion. This provides excellent atmospheric corrosion resistance and extends the service life of the upper heat exchange tubes. The lower heat exchange tubes are made of enameled Corten steel, which significantly improves low-temperature corrosion resistance compared to ordinary carbon steel tubes, more than doubling their service life. At a price only approximately 50% higher than ordinary carbon steel tubes, the overall cost-effectiveness is excellent.

[0037] During operation, the flue gas inlet 11 introduces high-temperature flue gas, and the air inlet 8 introduces low-temperature air. After heat exchange between the upper side pipe box 1 and the upper middle pipe box 2, the high-temperature flue gas is introduced through the flue duct into the lower side pipe box 3 and the lower middle pipe box 4 for heat exchange, ultimately passing through the flue gas outlet 12 to the boiler's tail flue. The low-temperature air, after absorbing waste heat from the flue gas through the lower side pipe box 3 and the lower middle pipe box 4, is introduced through the air connecting pipe 10 into the upper side pipe box 1 and the upper middle pipe box 2 for heat exchange, ultimately passing through the air outlet 9 to the upper-stage air preheater.

[0038] When the air preheater is in operation, the airflow flowing around the heat exchange tube bundle will generate Karman vortices. The alternating shedding of these vortices will cause vibrations in the air preheater. When the shedding frequency of the vortices is close to or consistent with the acoustic standing wave vibration frequency of the tube box, it will induce strong acoustic standing wave vibrations of the tube box, causing the air preheater to resonate, thereby causing vibration problems. The utility model is provided with partitions 13 vertically installed in each upper tube box, dividing the entire upper tube box structure into multiple air chambers, thereby increasing the natural frequency of the air chambers. In this way, the frequency of the Karman vortices and the natural frequency of the air chambers will not overlap, thereby avoiding the generation of acoustic resonance and effectively eliminating vibrations. The utility model not only eliminates vibrations, but also reduces noise, ensuring the efficient, long-term, safe and stable operation of the air preheater.

[0039] The above description is a detailed description of the preferred embodiments of the present invention, but the embodiments are not intended to limit the scope of the patent application of the present invention. All equivalent changes or modifications completed under the technical spirit suggested by the present invention should fall within the patent scope covered by the present invention.

Claims

1. An improved boiler lower-stage air preheater, comprising an upper tube box structure and a lower tube box structure, wherein the upper tube box structure is located directly above the lower tube box structure, the upper tube box structure adopts a vertical tube box arrangement, and the lower tube box structure adopts a horizontal tube box arrangement, characterized in that: One side of the lower tube box structure is an air inlet, and the other side is connected to one side of the upper tube box structure via an air connecting pipe. The other side of the upper tube box structure is an air outlet. The top of the upper tube box structure is a smoke inlet, and the bottom is connected to the top of the lower tube box structure via a flue. The bottom end of the lower tube box structure is a smoke outlet. The upper tube box structure is composed of a plurality of upper tube boxes connected together. A plurality of upper heat exchange tubes are vertically installed in each of the upper tube boxes. The upper heat exchange tubes pass through the top and bottom ends of the upper tube boxes. The material of the upper heat exchange tubes is Corten steel. Partitions are welded in each of the upper tube boxes and are vertically arranged. The lower group tube box structure is composed of multiple lower group tube boxes connected together, and a number of lower group heat exchange tubes are horizontally installed in the lower group tube boxes. The two ends of the lower group heat exchange tubes are respectively connected to the air inlet and the air connecting pipe. The lower group heat exchange tubes are enameled Corton tubes.

2. The improved boiler lower-stage air preheater according to claim 1, characterized in that: A first pipe box expansion joint is provided at the smoke inlet of the upper pipe box structure.

3. The improved boiler lower-stage air preheater according to claim 2, characterized in that: A second pipe box expansion joint is provided at the air inlet of the lower pipe box structure.

4. The improved boiler lower-stage air preheater according to claim 3, characterized in that: A third pipe box expansion joint is provided on the top of the lower pipe box structure.

5. The improved boiler lower-stage air preheater according to claim 1, characterized in that: The outer enamel thickness of the enameled Corton tube is 0.2-0.5 mm.

6. The improved boiler lower-stage air preheater according to claim 1, characterized in that: The box bodies of the upper and lower pipe boxes are both made of A3 steel.

7. The improved boiler lower-stage air preheater according to claim 1, characterized in that: The upper group of heat exchange tubes is fixedly installed in the upper group tube box through at least two first orifice plates, and the first orifice plates are arranged horizontally. The lower group of heat exchange tubes is fixedly installed in the lower group tube box through at least two second orifice plates, and the second orifice plates are arranged vertically.

8. The improved boiler lower-stage air preheater according to claim 7, characterized in that: The gaps between the upper group of heat exchange tubes and the first orifice plate and the gaps between the lower group of heat exchange tubes and the second orifice plate are sealed by welding.

9. The improved boiler lower-stage air preheater according to claim 1, characterized in that: One to two partitions are welded inside the upper tube box.

10. The improved boiler lower-stage air preheater according to claim 1, characterized in that: The air inlet is located directly below the air outlet and is arranged in parallel with the air outlet.

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