Waste heat boiler dense tube panel and internal maintenance method

Abstract

The invention discloses a waste heat boiler dense tube panel and an internal maintenance method, the waste heat boiler dense tube panel comprises a plurality of tube panel groups which are arranged at intervals, a header assembly, an anti-vibration device and a connecting assembly, and each tube panel group comprises a plurality of heat exchange tubes which are arranged in sequence and communicate with one another and a plurality of connecting tubes used for communicating the heat exchange tubes in the same tube panel group; a flue gas barrier plate is arranged between every two adjacent tube panel sets, the header assembly comprises an upper header and a lower header which are arranged at the upper end and the lower end of each tube panel set respectively, and the anti-vibration device comprises first anti-vibration pieces arranged at the tops of the tube panel sets respectively and at least one second anti-vibration piece arranged at the bottoms of the tube panel sets. The connecting assembly comprises a plurality of first connecting plates arranged on the side faces of all the tube panel sets in parallel and second connecting plates arranged at the bottoms of all the tube panel sets, the situation that the unit equipment efficiency is sacrificed can be effectively avoided, the maintenance cost is saved, and the construction period is guaranteed.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas unit maintenance, and more specifically relates to a concentrated tube panel of a waste heat boiler and an internal maintenance method. Background Art

[0002] In recent years, a large number of new gas-fired power plants have been built, and the waste heat boilers they support generally have the problem of difficult maintenance of the tube panels in the furnace. With the continuous improvement of the steam parameters of waste heat boilers, for example, the pressure of the waste heat boiler supporting the H-class gas turbine is 17.1Mpa, and the temperature reaches 603℃, the probability of overheating and bursting of the tube panel header also increases.

[0003] At present, the tube panels inside the waste heat boilers supporting gas units are arranged very densely, and the factory design does not take into account the inspection and maintenance conditions of the tube panels, resulting in the existing maintenance-free design of the waste heat boiler tube panels being unable to meet the actual production and operation and maintenance needs.

[0004] At present, there are two common methods for dealing with problems such as tube screen leakage or even tube burst: one is to block the leaking tube and isolate it; the other is to kill the tubes in pieces and enter the internal processing and then gradually reinstall and weld them. However, the above two maintenance methods are not only difficult to ensure the integrity of the tube screen fin tubes, but also have high maintenance costs and construction difficulties. Summary of the invention

[0005] The main purpose of the present invention is to provide a concentrated tube panel of a waste heat boiler and an internal maintenance method, which can avoid sacrificing the efficiency of gas unit equipment and save maintenance costs and construction period.

[0006] To achieve the above object, the technical solution of the present invention is:

[0007] A concentrated tube panel of a waste heat boiler comprises a plurality of tube panel groups arranged at intervals, a header assembly, a shockproof device, and a connecting assembly, wherein the tube panel group comprises a plurality of heat exchange tubes arranged in sequence and connected to each other, and a plurality of connecting tubes for connecting the heat exchange tubes in the same tube panel group, and flue gas baffles are respectively arranged between adjacent tube panel groups, the header assembly comprises an upper header and a lower header respectively arranged at the upper and lower ends of each tube panel group, and the upper header and the lower header are respectively arranged along the length direction of the corresponding tube panel group, the shockproof device comprises a first shockproof member respectively arranged at the top of the tube panel group and at least one second shockproof member arranged at the bottom of the tube panel group, and the connecting assembly comprises a plurality of first connecting plates respectively arranged in parallel on the sides of each tube panel group and a second connecting plate arranged at the bottom of each tube panel group.

[0008] According to the first aspect of the embodiment of the present invention, the connection assembly further includes a plurality of fixing pins for connecting the second connection plate and the lower header, and the plurality of fixing pins are respectively disposed between adjacent connection pipes.

[0009] According to the first aspect of the present invention, a deaerator is provided above the upper header, and the deaerator comprises a deaerator body and a low-pressure steam drum connected to the deaerator body, and the low-pressure steam drum is connected to the corresponding tube panel groups respectively.

[0010] According to the first aspect of the present invention, a medium-pressure steam drum and a high-pressure steam drum are provided on one side of the low-pressure steam drum, and the medium-pressure steam drum and the high-pressure steam drum are respectively connected to the corresponding tube panel group below.

[0011] According to the first aspect of the present invention, a plurality of first straight water down pipes are sequentially connected below the low-pressure drum, and the other end of each of the first straight water down pipes is connected to the corresponding tube panel group.

[0012] According to the first aspect of the present invention, a plurality of second straight water down pipes are sequentially connected below the intermediate-pressure drum, and the other end of each of the second straight water down pipes is connected to the corresponding tube panel group.

[0013] According to the first aspect of the present invention, a plurality of third straight water down pipes are sequentially connected below the high-pressure steam drum, and the other end of each of the third straight water down pipes is connected to the corresponding tube panel group.

[0014] According to an embodiment of the first aspect of the present invention, adjacent first connecting plates are arranged at equal intervals, and cylindrical blocks for connecting the heat exchange tubes are respectively provided at the front end and the rear end of the first connecting plate.

[0015] According to a second aspect of the present invention, the method for performing internal maintenance on the concentrated tube panel of the waste heat steam drum comprises the following steps:

[0016] 1) Mark the part to be repaired, and cut the weld of the connecting pipe corresponding to the lower header to disconnect the connection;

[0017] 2) De-energize the lower headers at the marked positions one by one;

[0018] 3) Disassemble the anti-vibration device at the bottom of the lower header, separate the lower header and the second anti-vibration component, and take them out in sequence;

[0019] 4) Partially disconnecting the first connecting plate at the position where the tube panel group is marked, so that adjacent heat exchange tubes can move horizontally;

[0020] 5) Partially disassemble the smoke baffle plate on one side of the tube panel group so as to observe the part to be repaired from the side;

[0021] 6) The heat exchange tube is bent at a degree of 10:1, that is, it is displaced by X length in the horizontal direction and 10X length in the vertical direction, so that the length of the tube panel group corresponding to the decoupling is sufficient to support the space required for maintenance.

[0022] One of the above technical solutions of the present invention has at least one of the following advantages or beneficial effects:

[0023] The present invention arranges a plurality of tube panel groups consisting of interconnected heat exchange tubes and connecting tubes at intervals, and arranges an upper header and a lower header at the upper and lower ends of each tube panel group, respectively, so as to improve heat exchange efficiency and thermal economy; and by arranging a shockproof device that is easy to disassemble, it is avoided to sacrifice the efficiency of the unit equipment during maintenance operations, thereby saving maintenance costs and construction period. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present invention will be further described below in conjunction with the accompanying drawings and embodiments;

[0025] Attached Figure 1 is an overall structural diagram of an embodiment of the present invention;

[0026] Attached Figure 2 It is a cross-sectional view along the AA direction of one embodiment of the present invention;

[0027] Attached Figure 3 A BB-direction cross-sectional view of an embodiment of the present invention;

[0028] Attached Figure 4 A cross-sectional view taken along the CC direction of an embodiment of the present invention;

[0029] Attached Figure 5 This is an enlarged view of point H of an embodiment of the present invention. DETAILED DESCRIPTION

[0030] The embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions from beginning to end. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0031] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0032] In the description of the present invention, "several" means one or more, "more" means more than two, "greater than", "less than", "exceed" etc. are understood as not including the number itself, and "above", "below", "within" etc. are understood as including the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0033] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include one or more features.

[0034] In the description of the present invention, it should be noted that, unless otherwise clearly stipulated and limited, the term "connection" should be understood in a broad sense. For example, it can be a fixed connection or a movable connection, a detachable connection or a non-detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, and it can be internal connection between two elements, indirect connection, or an interactive relationship between two elements.

[0035] The following disclosure provides many different embodiments or examples for implementing different solutions of the present invention.

[0036] Refer to the attached Figure 1 To Attachment Figure 5 As shown, a concentrated tube panel of a waste heat boiler comprises a plurality of tube panel groups 1 arranged at intervals, a header assembly, a shockproof device and a connecting assembly 4, flue gas baffles are respectively provided between adjacent tube panel groups 1, and the tube panel group 1 comprises a plurality of heat exchange tubes 11 arranged in sequence and interconnected with each other and a plurality of connecting tubes for connecting the heat exchange tubes 11 in the same tube panel group 1.

[0037] In one embodiment of the present invention, the header assembly includes an upper header 21 and a lower header 22 respectively disposed at the upper and lower ends of each tube panel group 1 , and the upper header 21 and the lower header 22 are respectively disposed along the length direction of the corresponding tube panel group 1 .

[0038] In one embodiment of the present invention, a deaerator is provided above the upper header 21, and the deaerator includes a deaerator body and a low-pressure steam drum connected to the deaerator body, and the low-pressure steam drum is respectively connected to the corresponding tube panel group 1. A medium-pressure steam drum and a high-pressure steam drum are provided on one side of the low-pressure steam drum, and the medium-pressure steam drum and the high-pressure steam drum are respectively connected to the corresponding tube panel group 1 below.

[0039] In one embodiment of the present invention, a plurality of first straight water pipes are sequentially connected to the lower part of the low-pressure steam drum, and the other end of each first straight water pipe is respectively connected to the corresponding tube panel group 1. A plurality of second straight water pipes are sequentially connected to the lower part of the medium-pressure steam drum, and the other end of each second straight water pipe is respectively connected to the corresponding tube panel group 1. A plurality of third straight water pipes are sequentially connected to the lower part of the high-pressure steam drum, and the other end of each third straight water pipe is respectively connected to the corresponding tube panel group 1.

[0040] In one embodiment of the present invention, the shockproof device includes a first shockproof member 31 disposed at the top of the tube panel group 1 and a second shockproof member 32 disposed at the bottom of the tube panel group 1 , and adjacent first shockproof members 31 are disposed in parallel.

[0041] In one embodiment of the present invention, the connection assembly 4 includes a plurality of first connection plates 41 respectively arranged in parallel on the sides of each tube panel group 1, a second connection plate 42 arranged at the bottom of each tube panel group 1, and a plurality of fixing pins 43 for connecting the second connection plate 42 and the lower header 22. The plurality of fixing pins 43 are respectively arranged between adjacent connecting tubes, and the adjacent first connection plates 41 are arranged at equal intervals. The front end and the rear end of the first connection plate 41 are respectively provided with cylindrical blocks for connecting the heat exchange tube 11.

[0042] In one embodiment of the present invention, in order to ensure the manufacturing quality of the tube panel group 1, we take the following process measures in manufacturing: 1. The tube assembly box adopts a rigid fixation and anti-deformation process, and reserves welding shrinkage margin. According to the drawing dimensions and the analysis of possible welding deformation, the assembly frame is designed and manufactured. Since the welds on the header assembly are dense, the two ends shrink and bend after welding. According to the experience of tests and production practice, appropriate anti-deformation is adopted before welding the header assembly, and the anti-deformation amount is controlled at 1.5mm / m according to empirical data. The center distance between the two upper headers 21 of the frame is pre-added with twice the anti-deformation amount of the header. Choose a reasonable assembly and welding sequence.

[0043] Second, due to the dense welds of the tube panel group 1 structure and the large welding shrinkage deformation, in order to minimize the welding deformation of the header assembly, a construction process of two welders on each header welding symmetrically from the middle to both ends is adopted. This can partially offset the welding deformation.

[0044] 3. Choose a welding method with low welding line energy. The greater the line energy used in the welding process, the greater the thermal compression plastic deformation, so the welding deformation increases. Choosing a welding method with low line energy and welding specifications can effectively prevent and reduce deformation, such as using small diameter electrodes, small currents, and small swing multi-layer and multi-pass welding.

[0045] In one embodiment of the present invention, the control of the welding process, that is, the preheating before welding, the dehydrogenation immediately after welding, the heat treatment after welding and other processes must be strictly controlled when the heat exchange tube 11 is made, including the following steps: the first step is preheating before welding. Preheating is one of the most effective measures to prevent cold cracking. The purpose and function of preheating is to slow down the cooling rate of the welded joint, reduce the hardened structure, reduce the internal stress, and also facilitate the escape of hydrogen. And for P91 / T91 materials, in order to prevent the occurrence of delayed cracks, it is necessary to preheat above 200°C. The second step is to strictly control the interlayer temperature. The interlayer temperature is controlled at 200°C to 280°C, which prevents cold cracks on the one hand and prevents excessive coarse grains on the other hand; the third step is to dehydrogenate immediately after welding. Delayed cracks are mainly related to the diffusion and aggregation of hydrogen. If the cooling is too fast after welding, hydrogen will not have time to escape from the weld, which will cause serious delayed cracks. Dehydrogenation immediately after welding can make the diffused hydrogen fully escape from the weld, which has a significant effect on preventing the occurrence of delayed cracks. The dehydrogenation treatment temperature is controlled at 275°C and the time is more than 2 hours.

[0046] In one embodiment of the present invention, a method of preheating, welding and dehydrogenation treatment can be adopted. A crawler-type ceramic electric heating hood is used for preheating, and the preheating temperature is above 200°C (an infrared temperature measuring gun is used for spot checks to verify the correctness of the automatic temperature measuring instrument). When the heating temperature reaches the preheating temperature and welding begins, the heating hood can be appropriately moved away for welding. After welding is completed, the heating hood continues to heat the header assembly and controls the temperature at 275°C. To achieve the purpose of dehydrogenation. After welding is completed, the heating hood control program should be set to continue heating for 2 hours, and the temperature should be controlled at 275°C.

[0047] In addition, considering the delayed crack tendency of P91 / T91 steel welding and the structural form of tube panel group 1, magnetic particle non-destructive testing should be carried out before and after heat treatment of the header assembly weld to ensure the quality of the weld. The flaw detection after heat treatment is generally carried out 24 hours later.

[0048] In one embodiment of the present invention, a method for internal maintenance of a waste heat boiler dense tube panel not only avoids sacrificing the efficiency of the unit equipment, but also saves maintenance costs and construction period and ensures the integrity of the tube panel fin tubes, and specifically includes the following steps:

[0049] First, mark the part to be repaired, cut the welding joint of the connecting pipe at the corresponding lower header 22, and then disconnect the lower header 22 at the marked part in turn;

[0050] Secondly, the anti-vibration device at the bottom of the lower header 22 is disassembled, and the lower header 22 and the second anti-vibration member 32 are disassembled and taken out in sequence;

[0051] Further, the first connecting plate 41 in the middle of the tube panel group 1 at the marked position and below is partially disconnected, so that the adjacent heat exchange tubes 11 can move horizontally;

[0052] Further, the smoke baffle plate on one side of the tube panel group 1 at the marked position is partially disassembled to observe the part to be repaired from the side;

[0053] Finally, the heat exchange tube 11 is bent at a ratio of 10:1, that is, it is displaced 1 meter in the horizontal direction and 10 meters in the vertical direction, so that the length of the corresponding tube panel group 1 is decoupled to support the space required for maintenance.

[0054] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A concentrated tube panel for a waste heat boiler, characterized in that: include: A plurality of tube panel groups (1) arranged at intervals, wherein the tube panel groups (1) comprise a plurality of heat exchange tubes (11) arranged in sequence and connected to each other and a plurality of connecting tubes for connecting the heat exchange tubes (11) in the same tube panel group (1), and smoke baffles are respectively provided between adjacent tube panel groups (1); A header assembly, the header assembly comprising an upper header (21) and a lower header (22) respectively arranged at the upper and lower ends of each tube panel group (1), the upper header (21) and the lower header (22) respectively being arranged along the length direction of the corresponding tube panel group (1); A shockproof device, the shockproof device comprising a first shockproof member (31) respectively arranged at the top of the tube panel group (1) and at least one second shockproof member (32) arranged at the bottom of the tube panel group (1); A connection assembly (4), comprising a plurality of first connection plates (41) respectively arranged in parallel on the sides of each tube panel group (1) and a second connection plate (42) arranged at the bottom of each tube panel group (1).

2. The concentrated tube panel of waste heat boiler according to claim 1, characterized in that: The connection assembly (4) further comprises a plurality of fixing pins (43) for connecting the second connection plate (42) and the lower header (22); the plurality of fixing pins (43) are respectively arranged between adjacent connection pipes.

3. The concentrated tube panel of waste heat boiler according to claim 1, characterized in that: A deaerator is provided above the upper header (21), and the deaerator comprises a deaerator body and a low-pressure steam drum connected to the deaerator body, and the low-pressure steam drum is respectively connected to the corresponding tube panel group (1).

4. The concentrated tube panel of waste heat boiler according to claim 3, characterized in that: A medium-pressure steam drum and a high-pressure steam drum are arranged at one side of the low-pressure steam drum, and the medium-pressure steam drum and the high-pressure steam drum are respectively connected to the corresponding tube panel group (1) below.

5. The concentrated tube panel of waste heat boiler according to claim 3, characterized in that: A plurality of first straight water down pipes are sequentially connected below the low-pressure steam drum, and the other end of each of the first straight water down pipes is connected to the corresponding tube panel group (1).

6. The concentrated tube panel of waste heat boiler according to claim 3, characterized in that: A plurality of second straight water down pipes are sequentially connected below the medium-pressure drum, and the other end of each of the second straight water down pipes is respectively connected to the corresponding tube panel group (1).

7. The concentrated tube panel of waste heat boiler according to claim 3, characterized in that: A plurality of third straight water pipes are sequentially connected below the high-pressure steam drum, and the other end of each of the third straight water pipes is connected to the corresponding tube panel group (1).

8. The concentrated tube panel of waste heat boiler according to claim 1, characterized in that: Adjacent first connecting plates (41) are arranged at equal intervals, and cylindrical blocks for connecting the heat exchange tubes (11) are respectively provided at the front end and the rear end of the first connecting plate (41).

9. A method for internal maintenance using the concentrated tube panel of a waste heat boiler according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: 1) Mark the part to be repaired, and cut the weld joint of the connecting pipe corresponding to the lower header (22) to disconnect the connection pipe; 2) Sequentially disconnect the lower headers (22) at the marked positions; 3) disassembling the anti-vibration device at the bottom of the lower header (22), disassembling the lower header (22) and the second anti-vibration component (32), and taking them out in sequence; 4) Partially disconnect the first connecting plate (41) at the position marked on the tube panel group (1); so that adjacent heat exchange tubes (11) can move horizontally; 5) Partially disassemble the smoke baffle plate on one side of the tube panel group (1) so as to observe the part to be inspected from the side; 6) The heat exchange tube (11) is bent at a degree of 10:1, that is, it is displaced by X length in the horizontal direction and 10X length in the vertical direction, so that the length of the tube panel group (1) is corresponding to the length of the tube panel group (1) to support the space required for maintenance.

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