Pipe box type air preheating system convenient to regulate and control

Abstract

The utility model discloses a tube box type air preheating system convenient to regulate and control, which comprises a last-stage tube box, a plurality of middle-stage tube boxes and a first-stage tube box, the last-stage tube box is independently arranged, the rest of the plurality of stages of tube boxes are stacked together, and the stacking parts of the adjacent tube boxes are separated by partition plates; the dry burning mechanism comprises a plurality of independent channels which are formed by dividing the interiors of the last-stage tube box, the middle multi-stage tube box and the first-stage tube box and an air channel into a plurality of independent channels through a plurality of baffles, and a plurality of dry burning baffle doors are correspondingly arranged on an air inlet channel of the last-stage tube box; the device further comprises a branch pipeline, the head end of the branch pipeline is communicated with the primary air outlet channel of the first-stage channel, the tail end of the branch pipeline is communicated with the air channel of the last-stage channel, the tail end of the branch pipeline is located on the downstream of the dry burning baffle door, and a fan and a valve are arranged on the branch pipeline. According to the utility model, ammonium bisulfate blockage caused by leakage of the pipe wall of the final-stage pipe box can be effectively avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of air preheating, and in particular relates to a tube-box type air preheating system which is easy to regulate. Background Art

[0002] In order to realize the waste heat recovery of flue gas, air preheaters are usually arranged in the vertical flue at the tail of the boiler. The flue gas flows from top to bottom, and the air enters the air preheater pipe box in the form of countercurrent. The reason for the lateral scouring of flue gas outside the existing horizontally arranged tubular air preheater is that there are always mechanical problems that cannot be solved by low-load dust accumulation and high-load wear. Once the heat exchange tubes are blocked, it is difficult to clear. In the actual application process of the existing tube-box air preheating system, there is still the problem of air leakage in the tube-box air preheating system, especially when the heat exchange tubes of the last-stage tube box leak, it will cause the primary and secondary air to enter the heat exchanger from the leakage point and mix with the heat medium (flue gas). Once this happens, the last-stage tube box still has the problem of ammonium bisulfate blockage. Utility Model Content

[0003] The utility model aims to provide a pipe-box type air preheating system which is easy to regulate. The adoption of this scheme can at least effectively avoid the blockage of ammonium bisulfate in the final-stage pipe box, and is conducive to reducing the risk of wear and dust accumulation as much as possible, thereby ensuring the performance of the air preheating system.

[0004] The technical solution adopted by the utility model is as follows.

[0005] A pipe-box type air preheating system which is easy to regulate comprises a final-stage pipe box, several intermediate-stage pipe boxes and a first-stage pipe box, wherein adjacent pipe boxes are connected in series through air ducts, smoke is introduced from the first-stage pipe box and finally led out from the final-stage pipe box, and air is introduced from the final-stage pipe box and finally led out from the first-stage pipe box; the final-stage pipe box is arranged separately, and the remaining several-stage pipe boxes are stacked together, and the stacked parts of adjacent pipe boxes are separated by partitions; the system also comprises a dry-burning mechanism, which comprises a plurality of independent channels formed by dividing the interior of the final-stage pipe box, several intermediate-stage pipe boxes and the first-stage pipe box and the air channel by a plurality of baffles, and a plurality of dry-burning baffle doors are correspondingly arranged in the air inlet channel of the final-stage pipe box; the system also comprises a branch pipeline, the head end of the branch pipeline is connected to the primary air outlet channel of the first-stage pipe box, the tail end of the branch pipeline is connected to the air channel of the final-stage pipe box, and the tail end of the branch pipeline is located downstream of the dry-burning baffle door, and a fan and a valve are arranged on the branch pipeline. Furthermore, the tail end of the branch pipeline is connected to the last-stage pipe box on the secondary air side, and the tail end of the branch pipeline is connected to the last-stage pipe box on the primary air side.

[0006] In order to further improve the stability of the pipe-box type air preheating system, support structures are provided at the bottom of the last-stage pipe box and several intermediate-stage pipe boxes.

[0007] As a preferred solution, the upper ends of the supporting structures of the middle several stages of pipe boxes are fixedly connected to the tube sheets at the bottoms of the middle several stages of pipe boxes.

[0008] In order to facilitate maintenance and overhaul, there is a separation space between the middle-stage pipe boxes and the final-stage pipe box.

[0009] Furthermore, the middle several levels of pipe boxes include a secondary pipe box and a tertiary pipe box.

[0010] As a preferred solution, in the lateral direction, a plurality of pipe box units are arranged side by side in each level of pipe box.

[0011] Beneficial effect: Compared with the prior art, the utility model can effectively avoid the blockage of ammonium bisulfate in the final tube box. The cleverness lies in that the disadvantage of "the leakage point of the heat exchange tube of the final tube box" is used as an advantage. The aforementioned branch pipeline structure can introduce the high-temperature primary air at the outlet of the first-stage tube box into the final tube box on the secondary air side. The high-temperature primary air pressurized by the fan can also be smoothly introduced into the final tube box on the primary air side, thereby increasing the metal wall temperature of the heat exchange tube of the final tube box. In this case, even if air enters the flue from the leakage point, it will not cause blockage of ammonium bisulfate. By adopting the scheme of the utility model, the horizontally arranged tubular air preheater can be conveniently changed to a vertical arrangement, which can minimize the wear and dust accumulation of the heat exchange tube, facilitate the unblocking of the blocked heat exchange tube, ensure the heat exchange performance of the air preheating system, and improve the safety and economy of the system. By adopting the scheme of the utility model, the space occupied by the tube box air preheating system can be reduced, which has the advantages of saving energy consumption and convenient regulation. At the same time, there is no need to arrange a soot blower, which reduces the facility cost and maintenance cost of the entire system. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 , Figure 2 This is a schematic diagram of the main structure of the tube-box type air preheating system in Example 1;

[0013] Figure 3 It is a schematic diagram of the lateral structure of the tube-box type air preheating system in Example 1;

[0014] Figure 4 , Figure 5 This is a cross-sectional schematic diagram of the tube-box type air preheating system in Example 1. DETAILED DESCRIPTION

[0015] The following is a further detailed description of the scheme of the utility model in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the utility model and are not used to limit the utility model. Example 1

[0016] Combination Figures 1 to 5As shown, a tube-box type air preheating system which is easy to regulate comprises a final tube box 1, several intermediate tube boxes and a first tube box 2. The final tube box 1, several intermediate tube boxes and the first tube box 2 are arranged in sequence from bottom to top, and the adjacent tube boxes are connected in series through an air duct 3. Smoke is introduced from the first tube box 2 and finally led out from the final tube box 1, and air is introduced from the final tube box 1 and finally led out from the first tube box 2. The final tube box 1 is arranged separately, and the remaining several tube boxes are stacked together, and the stacked parts of the adjacent tube boxes are separated by partitions 4. It also comprises a dry burning mechanism arranged at the entrance of the final tube box 1, and the dry burning mechanism comprises a plurality of independent channels which are divided into the interior and air passage of the final tube box 1, several intermediate tube boxes and the first tube box by a plurality of baffles 7, and a plurality of dry burning baffle doors 8 are arranged correspondingly in the air inlet passage of the final tube box 1. The baffle doors 8 of the dry burning mechanism are arranged as shown in FIG. Figure 4 As shown, a plurality of partitions 7 are provided in the air duct 3, and the arrangement thereof is as follows Figure 5 As shown; it also includes a branch pipeline 15, the head end of the branch pipeline 15 is connected to the primary air outlet channel of the first-stage pipe box 2, and the tail end of the branch pipeline 15 is connected to the air channel of the final-stage pipe box 1 (specifically: the second half of the branch pipeline 15 has two branches, one of the branches of the branch pipeline 15 is connected to the final-stage pipe box on the secondary air side, and the other branch of the branch pipeline 15 is connected to the final-stage pipe box on the primary air side), and the tail end of the branch pipeline 15 is located downstream of the dry-burning damper door 8, and a fan 13 and a valve 14 are arranged on the branch pipeline 15, and the fan adopts a variable frequency fan. In this embodiment, a support structure 5 is arranged at the bottom of the final-stage pipe box 1 and the middle-stage pipe boxes, and the upper end of the support structure 5 is fixedly connected to the tube sheet at the bottom of the middle-stage pipe boxes. In this scheme, the cleverness lies in using the disadvantage of "the leakage point of the final tube box" as an advantage. The aforementioned branch pipeline structure can introduce the high-temperature primary air at the outlet of the first-stage tube box 2 into the final tube box 1 on the secondary air side, and the high-temperature primary air pressurized by the fan is introduced into the final tube box on the primary air side, thereby increasing the metal wall temperature of the final tube box. In this case, even if air enters the flue from the leakage point, it will not cause ammonium bisulfate blockage, thereby effectively avoiding ammonium bisulfate blockage of the heat exchange tube of the final tube box 1. In addition, the opening and closing state of the branch pipeline can be flexibly adjusted according to needs.

[0017] In this embodiment, there is a separation space 6 between the intermediate pipe boxes and the final pipe box 1, and the intermediate pipe boxes include a secondary pipe box 11 and a tertiary pipe box 12. In the lateral direction, each pipe box has multiple pipe box units arranged side by side. Figure 4 In the application scheme shown, the final stage pipe box 1 is arranged with a plurality of pipe box units.

[0018] In this embodiment, a three-dimensional variable fin tube is used in the inlet area of ​​the tube box. The heat transfer is enhanced by processing fins on the flue gas side of the heat exchange tube, and the heat transfer thermal resistance on the flue gas side is reduced by not processing fins on the air side, thereby ensuring that the minimum tube wall temperature is not lower than 70°C and reducing the risk of low-temperature corrosion.

[0019] In this embodiment, the air side of the final tube box 1 and the entire inlet and outlet air duct and the tube box are separated into multiple independent channels by a dry burning mechanism, that is, a partition 7 is used to separate the air side of the final tube box 1 and the entire inlet and outlet air duct and the tube box into multiple independent channels, and multiple dry burning baffle doors 8 are correspondingly arranged at the air inlet channel of the final (low temperature section) tube box 1. During operation, the flue gas is formed by cutting off the air circulation in sequence, in turn, and partially to dry burn the tube box. Since the heat capacity of air is small and there is no phase change, the air in the heat exchange tube can be quickly heated up, and finally the metal wall temperature reaches a temperature close to that of the inlet flue gas. As long as the metal wall temperature is higher than the gasification temperature of ammonium bisulfate, the ammonium bisulfate deposited on the surface of the heat exchanger can be removed. The high-temperature flue gas discharged during dry burning can be mixed with a large amount of low-temperature flue gas that is not dry burned, so that the temperature of the mixed flue gas is quickly reduced to below 147°C, so that the ammonium bisulfate enters the dust collector in the form of crystals to prevent the secondary condensation of ammonium bisulfate.

[0020] By adopting the scheme in the embodiment, the horizontally arranged tubular air preheater can be easily changed to a vertical arrangement, which can minimize the wear and dust accumulation of the heat exchange tubes, facilitate the unblocking of the blocked heat exchange tubes, ensure the heat exchange performance of the air preheating system, and improve the safety and economy of the system. By adopting this scheme, the floor space of the tube box air preheating system can be reduced (compared with the same specification system mentioned in the background technology, the floor space height can be reduced by at least about 1 / 2, which has the advantages of saving energy and convenient regulation. At the same time, there is no need to arrange a soot blower, which reduces the facility cost and maintenance cost of the entire system. Example 2

[0021] A tube-box type air preheating system that is easy to control, referring to Example 1, the main difference between it and Example 1 is that:

[0022] It comprises two independent branch pipelines 15, the head end of the first branch pipeline 15 is connected to the primary air outlet channel of the first-stage pipe box 2, and the tail end of the first branch pipeline 15 is connected to the final-stage pipe box on the secondary air side; the head end of the second branch pipeline 15 is connected to the primary air outlet channel of the first-stage pipe box 2, and the tail end of the second branch pipeline 15 is connected to the final-stage pipe box on the primary air side; the tail end of each branch pipeline 15 is located downstream of the dry-burning baffle door 8, and a fan 13 and a valve 14 are arranged on each branch pipeline 15. Example 3

[0023] A tube-box type air preheating system that is easy to control, referring to Example 1, the main difference between it and Example 1 is that:

[0024] It includes two independent branch pipelines 15, the head end of the first branch pipeline 15 is connected to the primary air outlet channel of the first-stage pipe box 2, and the tail end of the first branch pipeline 15 is connected to the final-stage pipe box on the secondary air side; the head end of the second branch pipeline 15 is connected to the primary air outlet channel of the first-stage pipe box 2, and the tail end of the second branch pipeline 15 is connected to the final-stage pipe box on the primary air side; the tail end of each branch pipeline 15 is located downstream of the dry-burning baffle door 8, a valve 14 is arranged on each branch pipeline 15, and a fan 13 is arranged on the second branch pipeline 15.

Claims

1. A pipe-box type air preheating system that is easy to control, comprising a final-stage pipe box (1), a plurality of intermediate-stage pipe boxes and a first-stage pipe box (2), wherein adjacent pipe boxes are connected in series via an air duct (3), smoke is introduced from the first-stage pipe box (2) and finally led out from the final-stage pipe box (1), and air is introduced from the final-stage pipe box (1) and finally led out from the first-stage pipe box (2); characterized in that: The final stage pipe box (1) is arranged separately, and the remaining several stage pipe boxes are stacked together, and the stacked parts of adjacent pipe boxes are separated by partitions (4); it also includes a dry burning mechanism, which includes using several baffles (7) to divide the air channel of the final stage pipe box (1) into multiple independent channels, and a plurality of dry burning baffle doors (8) are correspondingly arranged in the air inlet channel of the final stage pipe box (1); it also includes a branch pipeline (15), the head end of the branch pipeline (15) is connected to the primary air outlet channel of the first stage pipe box (2), the tail end of the branch pipeline (15) is connected to the air channel of the final stage pipe box (1), and the tail end of the branch pipeline (15) is located downstream of the dry burning baffle door (8), and a fan (13) and a valve (14) are arranged on the branch pipeline (15).

2. The tube-box type air preheating system according to claim 1 is characterized in that: Support structures (5) are provided at the bottoms of the middle-stage pipe boxes and the final-stage pipe box (1).

3. The tube-box type air preheating system according to claim 1, characterized in that: The upper end of the supporting structure (5) of the middle several stages of pipe boxes is fixedly connected to the tube sheet at the bottom of the middle several stages of pipe boxes.

4. The tube-box type air preheating system according to claim 1, characterized in that: A separation space (6) is provided between the middle-stage pipe boxes and the final-stage pipe box (1).

5. The tube-box type air preheating system according to any one of claims 1 to 4, characterized in that: The middle several stages of pipe boxes include a secondary pipe box (11) and a tertiary pipe box (12).

6. The tube-box type air preheating system according to claim 5, characterized in that: In the lateral direction, a plurality of pipe box units are arranged side by side in each level of the pipe box.

7. The tube-box type air preheating system according to claim 6, characterized in that: One of the branches at the tail end of the branch pipeline (15) is connected to the final stage pipe box (1) on the secondary air side, and the other branch tail end of the branch pipeline (15) is connected to the final stage pipe box (1) on the primary air side.

Images