A method for plugging leakage of a tantalum bayonet tube heat exchanger

Abstract

The application provides a leakage plugging method for a tantalum bayonet tube heat exchanger, and belongs to the technical field of sulfuric acid concentration in nitration process.The leakage plugging method for the tantalum bayonet tube heat exchanger comprises the following steps: extracting the bayonet tube, inserting a limiting plate between the bayonet tubes during the extraction process, and limiting the bayonet tube; for the leaked heating tantalum tube, grinding the weld joint between the heating tantalum tube and the outer layer sealing tantalum tube, and extracting the heating tantalum tube; inserting the plugging tantalum tube with the same outer diameter specification as the heating tantalum tube into the outer layer sealing tantalum tube, and expanding and connecting; removing the corresponding bayonet tube, and plugging; loading the remaining bayonet tube into the heating tantalum tube along the original path, and removing the limiting plate set.The leakage plugging method for the tantalum bayonet tube heat exchanger can be used for on-site maintenance and leakage plugging, greatly reduces the influence on production, and saves the maintenance cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of sulfuric acid concentration in nitration process, and particularly relates to a method for plugging leakage of a tube bank of a tantalum-made bayonet tube heat exchanger. BACKGROUND

[0002] Sulfuric acid is a raw material used in a recycling manner in a nitration process, and in a process flow, concentrated sulfuric acid is changed into dilute sulfuric acid after absorbing water, and the dilute sulfuric acid is concentrated into concentrated sulfuric acid after denitration and dehydration, so as to realize recycling use of the sulfuric acid. The concentrated sulfuric acid is a strong corrosive material, and currently, a common heating equipment used for heating the sulfuric acid is a glass-lined kettle reboiler, and a heating element in the kettle reboiler is a tantalum-made bayonet tube heater. The tantalum-made bayonet tube heater comprises heating tantalum tubes, a large tube plate, bayonet tubes and a small tube plate. The heating tantalum tubes serve as outer tubes and are in contact with the sulfuric acid material. The bayonet tubes are stainless steel tubes and are arranged inside the heating tantalum tubes for heating. The bayonet tubes are internally connected to heating steam as a heat source. One end of the bayonet tube is arranged on the small tube plate, and the other end of the bayonet tube penetrates into the heating tantalum tube. The large tube plate is composed of a low-alloy pressure-bearing plate and a corrosion-resistant lining plate. The corrosion-resistant lining plate is made of tantalum material. A plurality of heating tantalum tubes penetrate through the large tube plate. An outer sealing tantalum tube is arranged at a position where the heating tantalum tube penetrates through the large tube plate. The outer sealing tantalum tube penetrates through the large tube plate and is sealed by double tantalum tube welding. The heating tantalum tube is arranged in the outer sealing tantalum tube. The heating tantalum tube and the outer sealing tantalum tube are welded together at a position away from the corrosion-resistant lining plate. The other end of the outer sealing tantalum tube is folded and welded to the corrosion-resistant lining plate of the large tube plate. The heating tantalum tube and the outer sealing tantalum tube are expanded and connected to the large tube plate. Tantalum is a high-melting-point metal, and its melting point is 2996 DEG C. Tantalum has the characteristics of fast heat conduction, easy oxidation and brittleness, and difficult welding forming control. The welding of tantalum material faces three key technical difficulties: first, the welding of tantalum material is difficult due to the high melting point of tantalum material; second, the welding quality of tantalum material is extremely high due to the fact that tantalum material is generally applied in extreme environments such as strong acid and ultrahigh temperature; and third, tantalum is extremely easy to react with oxygen and nitrogen in the air in a high-temperature state to form a brittle tantalum compound weld. Therefore, it is extremely difficult to obtain a reliable tantalum weld. Although the heating tantalum tube has extremely strong corrosion resistance and generally does not leak due to corrosion, the heating tantalum tube may leak due to various factors such as manufacturing quality. Once the heating tantalum tube leaks, the sulfuric acid medium outside the heating tantalum tube will enter the inside of the heating tantalum tube, and then enter the outside of the large tube plate, thereby corroding and damaging the low-alloy pressure-bearing plate. Due to the connection form of the heating tantalum tube and the large tube plate and the welding performance of tantalum material, once the heating tantalum tube leaks, the leakage cannot be plugged by using a general plugging method of a heat exchanger, and generally, the heating tantalum tube needs to be removed as a whole and repaired in a factory. The repair time is long, the repair cost is high, and the safety production of the device is seriously affected. SUMMARY

[0003] The application aims to provide a method for plugging leakage of a tube bank of a tantalum-made bayonet tube heat exchanger.

[0004] To achieve the above object, the technical scheme adopted by the present application is as follows: a method for plugging leakage of a tube of a tantalum bayonet tube heat exchanger, comprising the following steps:

[0005] S1, extracting the bayonet tube, and inserting a limiting plate between the bayonet tube bundles to limit the bayonet tube during the extraction of the bayonet tube;

[0006] S2, for the leaking heating tantalum tube, grinding the weld between the heating tantalum tube and the outer layer sealing tantalum tube, separating the heating tantalum tube and the outer layer sealing tantalum tube after the weld is ground clean, and extracting the heating tantalum tube;

[0007] S3, inserting a plugging tantalum tube with the same outer diameter specification as the heating tantalum tube into the outer layer sealing tantalum tube, and expanding the plugging tantalum tube and the outer layer sealing tantalum tube using a tube expander;

[0008] S4, removing the bayonet tube corresponding to the leaking heating tantalum tube, and plugging the tube holes of the small tube plate after the bayonet tube is removed;

[0009] S5, loading the remaining bayonet tube into the heating tantalum tube in the original way, and removing the limiting plate.

[0010] In a possible implementation, in step S1, the width of the limiting plate is equivalent to the spacing of the bayonet tube.

[0011] In a possible implementation, in step S1, a plurality of limiting plates located at the same position in the length direction of the bayonet tube form a limiting plate group, and at least one limiting plate group is inserted at each installation position along the length direction of the bayonet tube.

[0012] In a possible implementation, in step S1, the limiting plates in the same limiting plate group are arranged in parallel with each other.

[0013] In a possible implementation, in step S1, the limiting plates at adjacent installation positions in the length direction of the bayonet tube have an angle difference.

[0014] In a possible implementation, in step S1, a limiting plate group is arranged at a distance of 250-350 mm from the free end of the bayonet tube.

[0015] In a possible implementation, in step S2, when the leaking heating tantalum tube is located on the outer side of all the heating tantalum tube bundles, the leaking heating tantalum tube on one side of the corrosion-resistant lining plate is cut before the heating tantalum tube is extracted.

[0016] In a possible implementation, in step S3, the plugging tantalum tube comprises a plugging straight cylinder with two open ends and a plugging cylinder bottom, the plugging cylinder bottom is arranged at one end of the plugging straight cylinder, and the plugging cylinder bottom is located on the corrosion-resistant lining plate side of the large tube plate.

[0017] In a possible implementation, in step S3, after the heating tantalum tube is extracted, the inner wall of the outer layer sealing tantalum tube is inspected and cleaned.

[0018] In a possible implementation, in step S3, the length of the plugging tantalum tube exceeds the thickness of the large tube plate by more than 20 mm.

[0019] The method has the following advantages:

[0020] Compared with the prior art, when the bayonet tube bundle is extracted, the limiting plates are inserted between the bayonet tube bundles to limit the bayonet tubes, so that the bayonet tubes can be accurately inserted into the heating tantalum tube when the bayonet tube bundle is reloaded, the bayonet tubes are prevented from being bent and disordered due to the absence of baffle plates and support plates, and the difficulty of maintenance is reduced. After the leaking heating tantalum tube is separated from the outer layer sealing tube, the plugging tantalum tube is used to plug at the position where the heating tantalum tube is removed, the plugging tantalum tube is inserted into the outer layer sealing tantalum tube, the plugging tantalum tube and the outer layer sealing tantalum tube are expanded and connected, the leaking position is plugged, and on-site welding is avoided. The heating tantalum tube bundle does not need to be removed as a whole, and the heating tantalum tube bundle is sent back to the manufacturer for maintenance, thereby solving the problem of plugging the tantalum bayonet tube heat exchanger, enabling on-site maintenance and leakage plugging, greatly reducing the influence on production, and saving maintenance costs. BRIEF DESCRIPTION OF DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0022] Figure 1 The structure diagram of the tantalum bayonet tube heat exchanger used in the embodiments of the present application is shown in the figure.

[0023] Figure 2 The structure diagram of the bayonet tube and the limiting plate used in the embodiments of the present application is shown in the figure.

[0024] Figure 3 The structure diagram of the bayonet tube and the limiting plate used in the embodiments of the present application is shown in the figure. Figure 2 The side view structure diagram of the bayonet tube and the limiting plate is shown in the figure.

[0025] Figure 4 The structure diagram of the plugging tantalum tube used in the embodiments of the present application is shown in the figure.

[0026] In the figure: 1, bayonet tube; 2, small tube plate; 3, limiting plate; 4, heating tantalum tube; 5, outer layer sealing tantalum tube; 6, large tube plate; 7, corrosion-resistant lining plate; 8, plugging tantalum tube; 801, plugging straight cylinder; 802, plugging cylinder bottom. DETAILED DESCRIPTION

[0027] In order to make the technical problems to be solved by the present application, technical solutions and beneficial effects more clear and explicit, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0028] Please refer to Figures 1 to 4 , a specific embodiment of a tantalum bayonet tube heat exchanger tube leakage plugging method provided by the present application will be described, including the following steps:

[0029] S1, the bayonet tube 1 is extracted, the bayonet tube 1 is uniformly arranged on the small tube plate 2, in the process of extracting the bayonet tube 1, due to the influence of the weight of the bayonet tube 1, since there is no baffle and support plate similar to other heat exchanger tube bundle to support the bayonet tube 1, the part of the bayonet tube 1 away from the small tube plate 2 will sag, after the bayonet tube 1 is extracted, deformation will inevitably occur, the limiting plate 3 is inserted between the bayonet tube bundle 1 to limit the bayonet tube 1, to avoid the relative displacement between the bayonet tube 1 after the bayonet tube 1 is extracted, the width of the limiting plate 3 is equivalent to the spacing of the bayonet tube 1, which is convenient for positioning the bayonet tube 1, otherwise the gap between the bayonet tube 1 is inconsistent with the original one, the deformation is large and is not conducive to the reloading, at least three different groups of limiting plates are selected along the length direction of the bayonet tube 1 to insert a group of limiting plates to limit, the stability of the limiting is increased, the limiting plates 3 of the same group of limiting plate groups located at the same mounting position of the bayonet tube 1 are arranged in parallel, which is convenient for inserting the limiting plate 3 and avoiding the mutual influence of the limiting plates 3 of the same group during the insertion process, the limiting plates 3 located at adjacent mounting positions in the length direction of the bayonet tube 1 have an angle difference, the angle is selected according to the arrangement mode of the bayonet tube bundle, which is generally 60°. The bayonet tube 1 is limited in multiple directions, a group of limiting plate groups are arranged at a distance of 250-350 mm from the free end of the bayonet tube 1, preferably a group of limiting plate groups are arranged at a distance of 300 mm from the free end of the bayonet tube 1, the free end of the bayonet tube 1 is limited, which is convenient for the reloading of the bayonet tube 1;

[0030] S2, for the leaking heating tantalum tube 4, polish the weld between the heating tantalum tube 4 and the outer layer sealing tantalum tube 5, polish the weld clean so that the heating tantalum tube 4 is separated from the outer layer sealing tantalum tube 5, separate the heating tantalum tube 4 from the outer layer sealing tantalum tube 5, draw out the heating tantalum tube 4, retain the outer layer sealing tantalum tube 5, and do not damage the outer layer sealing tantalum tube 5, such as the leaking heating tantalum tube 4 is located at the outer layer of the heating tantalum tube bundle, the exposed part of the heating tantalum tube 4 on one side of the corrosion-resistant lining plate 7 of the large tube plate 6 is cut off first, which is beneficial to the drawing of the heating tantalum tube 4 from the tube plate, and if the leaking heating tantalum tube 4 is located at the inner side of the heating tantalum tube bundle, the leaking heating tantalum tube 4 needs to be drawn out completely. When drawing out the leaking heating tantalum tube 4, attention should be paid to not damaging the outer layer sealing tantalum tube 5. The outer layer sealing tantalum tube 5 is expanded and connected with the large tube plate 6, and the outer layer sealing tantalum tube 5 is welded with the corrosion-resistant lining plate 7. Once the outer layer sealing tantalum tube 5 is damaged, the sealing property of the device will be affected;

[0031] S3, after the heating tantalum tube 4 is drawn out, the inner wall of the outer layer sealing tantalum tube 5 is checked and cleaned to avoid impurities affecting the installation and sealing of the plugging tantalum tube 8. The plugging tantalum tube 8 with the same outer diameter specification as the heating tantalum tube 4 is inserted into the outer layer sealing tantalum tube 5, the tube expander is used to expand and connect the plugging tantalum tube 8 with the outer layer sealing tantalum tube 5, the strength expansion is adopted for expansion to avoid the plugging tantalum tube 8 from being pulled out due to the pressure of the sulfuric acid medium during operation, the plugging tantalum tube 8 does not need to be welded with the outer layer sealing tantalum tube 5, and the operation difficulty is reduced. The plugging tantalum tube 8 includes a plugging straight cylinder 801 with two open ends and a plugging cylinder bottom 802, the plugging cylinder bottom 802 is arranged at one end of the plugging straight cylinder 801, one end of the plugging cylinder bottom 802 of the plugging tantalum tube 8 penetrates into the outer layer sealing tantalum tube 5, the opening of the plugging tantalum tube 8 is located at the end of the outer layer sealing tantalum tube 5, and the plugging cylinder bottom 802 of the plugging tantalum tube 8 is located at one side of the corrosion-resistant lining plate 7 of the large tube plate 6, and the length of the plugging tantalum tube 8 exceeds the thickness of the large tube plate 6 by more than 20 mm. During the plugging process, attention should be paid to not damaging the outer layer sealing tantalum tube 5 and the weld between the outer layer sealing tantalum tube 5 and the corrosion-resistant lining plate 7, otherwise the damage of the weld may cause leakage;

[0032] S4, remove the bayonet tube 1 corresponding to the leaking heating tantalum tube 4, and plug the tube hole of the small tube plate 2 after removing the bayonet tube 1. The plugging at the bayonet tube 1 adopts the conventional plugging method of the heater tube bank;

[0033] S5, the remaining bayonet tube 1 is reloaded into the heating tantalum tube 4 in the original way. After the free ends of all the bayonet tubes 1 penetrate into the heating tantalum tube 4 during the reloading process, the limiting plate group closest to the free end is removed to avoid displacement of the bayonet tube 1 during the reloading process and improve the reloading efficiency;

[0034] S6, each limiting plate group is removed gradually with the bayonet tube 1 inserted into the heating tantalum tube 4, the limiting plate 3 is removed gradually, and the bayonet tube 1 is gradually reassembled, which is beneficial to improve the reassembly efficiency, avoid the bayonet tube 1 from being bent due to its own weight, and reduce the reassembly difficulty.

[0035] The method provided by the application can separate the leaked heating tantalum tube 4 from the outer sealing tube, plug the tantalum tube 8 at the position of the removed heating tantalum tube 4, insert the plugged tantalum tube 8 into the outer sealing tantalum tube 5, expand the plugged tantalum tube 8 and the outer sealing tantalum tube 5, plug the leakage position, avoid on-site welding, and greatly reduce the influence on production and the maintenance cost.

[0036] The above is only a preferred embodiment of the application, and is not used to limit the application, and any modification, equivalent replacement, improvement, etc. within the spirit and principle of the application should be included in the protection scope of the application.

Claims

1. A method for plugging leakage of a tantalum bayonet tube heat exchanger tube, characterized in that, The application discloses a bayonet tube heater for tantalum material, which comprises a heating tantalum tube, a large tube plate, a bayonet tube and a small tube plate. The heating tantalum tube is in contact with sulfuric acid material as an outer tube, the bayonet tube is used for heating, the bayonet tube is internally connected with a heating steam as a heat source, one end of the bayonet tube is arranged on the small tube plate, and the other end of the bayonet tube penetrates into the heating tantalum tube. The large tube plate comprises a low alloy pressure-bearing plate and a corrosion-resistant lining plate, the corrosion-resistant lining plate is made of tantalum material, a plurality of heating tantalum tubes penetrate through the large tube plate, an outer sealing tantalum tube is arranged at the position where the heating tantalum tube penetrates through the large tube plate, the outer sealing tantalum tube penetrates through the large tube plate, the outer sealing tantalum tube is expanded and connected with the large tube plate, the heating tantalum tube is arranged in the outer sealing tantalum tube, one end of the heating tantalum tube away from the corrosion-resistant lining plate is welded and connected with the outer sealing tantalum tube, and the other end of the outer sealing tantalum tube close to the corrosion-resistant lining plate is folded and welded and connected with the corrosion-resistant lining plate of the large tube plate. S1, the bayonet tube is drawn out, and the bayonet tube is uniformly distributed on the small tube plate in the process of drawing out the bayonet tube; the limiting plates are inserted between the plurality of bayonet tubes to limit the plurality of bayonet tubes; S2, for the leaked heating tantalum tube, the welding seam between the heating tantalum tube and the outer sealing tantalum tube is polished, the welding seam is polished clean, the heating tantalum tube is separated from the outer sealing tantalum tube, the heating tantalum tube is drawn out, and the outer sealing tantalum tube is reserved; S3, after the heating tantalum tube is drawn out, the inner wall of the outer sealing tantalum tube is checked and cleaned, the plugging tantalum tube with the same outer diameter specification as the heating tantalum tube is inserted into the outer sealing tantalum tube, the plugging tantalum tube comprises a plugging straight cylinder and a plugging cylinder bottom, the plugging cylinder bottom is arranged at one end of the plugging straight cylinder, the opening of the plugging tantalum tube is located at the end of the outer sealing tantalum tube, the plugging cylinder bottom is located on one side of the corrosion-resistant lining plate of the large tube plate, the plugging tantalum tube and the outer sealing tantalum tube are expanded and connected by using a pipe expander, and the expansion is of high strength, and the plugging tantalum tube and the outer sealing tantalum tube do not need to be welded; S4, the bayonet tube corresponding to the leaked heating tantalum tube is removed, and the pipe hole of the small tube plate after the bayonet tube is removed is plugged; S5, the remaining bayonet tubes are reloaded into the heating tantalum tube in the original way, and in the reloading process, the limiting plates are gradually removed, and the bayonet tubes are gradually reloaded.

2. The method for plugging leakage of a tantalum bayonet tube heat exchanger tube according to claim 1, characterized in that, In step S1, the width of the limiting plate is equivalent to the spacing of the bayonet tubes.

3. The method for plugging leakage of a tantalum bayonet tube heat exchanger tube according to claim 1, characterized in that, In step S1, the limiting plates at the same position in the length direction of the bayonet tube form a limiting plate group, and at least one limiting plate group is inserted into each mounting position along the length direction of the bayonet tube.

4. The method for plugging leakage of a tantalum bayonet tube heat exchanger tube according to claim 3, characterized in that, In step S1, the limiting plates in the same limiting plate group are arranged in parallel with each other.

5. The method for sealing leakage in the tubes of a tantalum bayonet-shaped heat exchanger as described in claim 4, characterized in that, In step S1, the limiting plates at adjacent mounting positions in the length direction of the bayonet tube have an angle difference.

6. The method for plugging leakage of a tantalum bayonet tube heat exchanger tube according to claim 5, characterized in that, In step S1, a limiting plate group is arranged at a position 250-350 mm away from the free end of the bayonet tube.

7. The method of plugging leakage of a tube of a tantalum bayonet tube heat exchanger according to claim 1, wherein In step S2, when the leaked heating tantalum tube is located outside all the heating tantalum tubes, the leaked heating tantalum tube on one side of the corrosion-resistant lining plate is cut before the heating tantalum tube is drawn out.

8. The method for sealing leakage in the tubes of a tantalum bayonet-shaped heat exchanger as described in claim 1, characterized in that, In step S3, the length of the plugging tantalum tube exceeds the thickness of the large tube plate by more than 20 mm.

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