Double-sleeve structure rapid heat exchange tube bundle welding positioning tool and welding method

Abstract

The application discloses a double-sleeve structure rapid heat exchange pipe bundle welding positioning tool and a welding method. In the operation process, the inner pipe bears high temperature, the inner pipe is elongated and bent, the gap between the sleeves is reduced, the flow of the cooling water is reduced, and the inner pipe is easily unevenly heated; the inlet cone is subjected to heat treatment after being welded with the lower connecting piece, and the inlet cone is easily cracked by heat. The application is composed of a supporting base (1), a traveling track (2) and a plurality of boosting trolleys (3). The boosting trolleys are arranged in the traveling track, the traveling track is supported by the supporting base, and a side positioning support frame (4) is fixed to the supporting base. The application is used for welding the double-sleeve structure rapid heat exchange pipe bundle.

Description

TECHNICAL FIELD

[0001] The application relates to a double-sleeve structure rapid heat exchange tube bundle welding positioning tool and a welding method. BACKGROUND

[0002] The rapid cooling heat exchanger is a key equipment in an ethylene cracking device, and mainly functions to rapidly cool high-temperature cracking gas at about 800 DEG C to a temperature below a secondary reaction temperature, reduce olefin loss, and recover high-level heat energy of the cracking gas. The double-sleeve structure rapid heat exchange tube bundle comprises an inner tube with a diameter of 73*7.1, a material of 13CrMo4-5, and a length of L=19980mm; an outer tube with a diameter of 114.3*11.13, a material of SA-106MGr.B, and a length of L=19760mm; an upper and lower connecting piece of SA-336MF22CL3; and an inlet cone of InColoy800HT. The inner and outer tubes are connected into a double-sleeve structure through the upper and lower connecting pieces, the inlet cone is connected with the lower connecting piece through ring joint butt joint, the inner tube medium is high-temperature cracking gas at 800 DEG C, and the interlayer medium between the inner and outer sleeves is cooling water. Due to high temperature and high thermal intensity of the cracking gas, the inner tube and the ring joint splicing position of the lower connecting piece have the most severe operation condition; the inner and outer tube bundles have long length and great flexibility, the gap between the inner and outer tube bundles is 9.3mm, there is a group of support blocks with a height of 8.5mm every 250mm, the net gap is only 0.8mm, and it is difficult to pass the tube; in the operation process, the inner tube bears high temperature, after the inner tube is elongated and bent, the sleeve gap is reduced, the cooling water flow is reduced, and the inner tube is easily subjected to uneven heating; after the welding of the inlet cone and the lower connecting piece (the material is SA-336MF22CL3) is completed, heat treatment is needed, and the inlet cone is easily subjected to thermal cracks. How to ensure the product quality of the double-sleeve structure is an urgent problem to be solved. SUMMARY

[0003] The application aims to solve the problems that the inner tube bears high temperature in the operation process, after the inner tube is elongated and bent, the sleeve gap is reduced, the coolingwater flow is reduced, the inner tube is easily subjected to uneven heating, after the welding of the inlet cone and the lower connecting piece is completed, heat treatment is needed, and the inlet cone is easily subjected to thermal cracks, and provides a double-sleeve structure rapid heat exchange tube bundle welding positioning tool and a welding method which reduce the welding amount, improve the welding quality, avoid post-welding heat treatment, and reduce the welding stress of dissimilar steel.

[0004] The above purpose is achieved by the following technical scheme.

[0005] A double-sleeve structure rapid heat exchange tube bundle welding positioning tool, which comprises a support base, a traveling track and a plurality of boost trolleys, the plurality of boost trolleys are placed in the traveling track, the traveling track is supported by the support base, and a side positioning support frame is fixed on the support base.

[0006] The welding method of the double sleeve structure rapid heat exchange tube bundle welding positioning tool, the method comprises the following steps:

[0007] Step one: inner tube pre-stretching;

[0008] The built-in resistance heating device is set, the heating temperature and heating time are controlled by the temperature control cabinet, and the elongation of the pipe after heating is calculated by the elongation calculation formula of the pipe: ΔL=L×a(T2-T1);

[0009] Wherein: T2 is the heating temperature of the pipe, T1 is the initial temperature of the pipe, α is the linear expansion coefficient, L is the heating length of the pipe, and ΔL is the elongation of the pipe;

[0010] The inner tube heating length L is determined as 2 m, the heating temperature is 320 DEG C, the holding time is 30 min, and the inner tube elongation is 4 mm;

[0011] Step two: inner and outer tube bundle sleeving;

[0012] When the pipe is inserted, a plurality of booster trolleys are installed on the running track, the inner tube is placed on the booster trolley, the front end of the inner tube is mechanically pulled, the rear end is assisted by the booster trolley to advance, the inner tube is pulled up and advances with the inner tube, so that the end of the inner tube always enters the outer tube horizontally, the track side positioning support is used to prevent the inner tube from rotating, and the guide sleeve is installed at the end of the outer tube;

[0013] Step three: inner hole welding positioning;

[0014] The inner hole welding positioning tool is used to ensure that the inner tube and the lower connecting piece are aligned, the inner hole welding positioning tool is a semicircular ring structure, a reserved welding groove is formed in the inside, and the groove depth is the height of the back weld;

[0015] Step four: inner tube and lower connecting piece welding;

[0016] The inner tube and the lower connecting piece are U-shaped grooves, and the inner tube and the lower connecting piece are non-isosceles angle structures;

[0017] Step five: inner tube and upper connecting piece welding;

[0018] The inner tube and the upper connecting piece are combined welds of groove welds and fillet welds, the groove is a single V-shaped groove, the angle is 40 DEG, and the single-sided gap between the inner tube and the upper connecting piece is 3 mm;

[0019] Step six: lower connecting piece and lower cone welding;

[0020] The lower connecting piece and the lower cone adopt a nickel-based isolation layer by surfacing.

[0021] The welding method of the welding positioning fixture for the rapid heat exchange tube bundle with double tube structure, wherein the inner hole welding positioning fixture in step three is a semi-circular ring structure, and a reserved welding groove is opened inside, the groove depth being the height of the back weld foot.

[0022] The welding method of the welding positioning fixture for the double-tube rapid heat exchange tube bundle, wherein the U-shaped bevel between the inner tube and the lower connector in step four is a full penetration structure, specifically: the bevel angle of the U-shaped bevel is 90°, the angle between the upper slope and the horizontal plane is 15°, the inner slope is a vertical surface with a thickness of 2mm between it and the inner diameter of the inner tube, and there is a rounded corner with a radius of 2mm between the upper slope and the inner slope.

[0023] The welding method of the welding positioning fixture for the double-tube rapid heat exchange tube bundle is described, wherein the contact end between the inner tube and the lower connecting bevel positioning fixture and the weld is a copper pad.

[0024] Beneficial effects:

[0025] 1. This invention changes the butt joint bevel type of the inner sleeve and the lower connector to an inner U-shaped bevel, which expands the welding visibility range and ensures full penetration of the weld; the assembly tooling of the inner and outer tube bundles ensures the tube bundle insertion effect.

[0026] 2. In order to reduce the thermal stretching of the inner tube during operation, the inner tube is pre-stretched during the manufacturing process. Combined with the hot deformation test of 13CrMo4-5 material, the deformation law is summarized and the bevel form of the inner tube and the upper connecting part is determined to improve the welding quality.

[0027] 3. In order to reduce welding stress of dissimilar steels and avoid post-weld heat treatment of the inlet cone, the present invention improves the bevel type of the lower connector and overlays a nickel-based isolation layer. Attached image description:

[0028] Appendix Figure 1 Main view of the internal and external tube bundle structure and the tooling assembly;

[0029] Appendix Figure 2 A three-dimensional view of the internal and external tube bundle structure and the tooling assembly;

[0030] Appendix Figure 3 Schematic diagram of the positioning fixture for the inner tube and the lower connecting piece;

[0031] Appendix Figure 4 A schematic diagram of the improved inner hole welding structure;

[0032] Appendix Figure 5 This is a schematic diagram of the bevel structure between the inner tube after pre-stretching and the upper connector.

[0033] Appendix Figure 6 This is a drawing showing the weld overlay dimensions of the lower connector;

[0034] AppendixFigure 7 The schematic diagram of the inner hole welding structure before improvement;

[0035] In the figure: 1, support chassis; 2, running track; 3, booster trolley; 4, side positioning support frame; 5, inner tube. DETAILED DESCRIPTION:

[0036] Example 1:

[0037] A double-sleeve structure rapid heat exchange tube bundle welding positioning tool, the double-sleeve structure rapid heat exchange tube bundle welding positioning tool includes a support chassis 1, a running track 2 and a plurality of booster trolleys 3, a plurality of said booster trolleys are placed in said running track, said running track is supported by a support chassis, said support chassis is fixed with a side positioning support frame 4.

[0038] Example 2:

[0039] A welding method of a double-sleeve structure rapid heat exchange tube bundle welding positioning tool, the method comprises the following steps:

[0040] Step one: inner tube pre-stretching;

[0041] Set the built-in resistance heating device, control the heating temperature and heating time with the temperature control cabinet, and use the elongation formula of the pipe after heating, ΔL=L×a(T2-T1);

[0042] Wherein: T2 is the pipe heating temperature, T1 is the initial temperature of the pipe, α is the linear expansion coefficient, L is the pipe heating length, and ΔL is the elongation of the pipe;

[0043] The inner tube heating length L is determined to be 2m, the heating temperature is 320℃, the holding time is 30min, and the inner tube elongation is 4mm;

[0044] Step two: inner and outer tube bundle sleeving;

[0045] When threading the pipe, a plurality of booster trolleys are installed on the running track, the inner tube is placed on the booster trolley, the front end of the inner tube is mechanically pulled, the rear end is assisted by the booster trolley to advance, the inner tube is pulled up and advances with the inner tube, so that the end of the inner tube always maintains horizontal entry when entering the outer tube, the track side positioning support is used to prevent the inner tube from rotating, and the guide sleeve is installed at the end of the outer tube to prevent the inner tube accessories from knocking the outer tube groove during threading;

[0046] Step three: inner hole welding positioning;

[0047] The inner hole welding positioning tool is used to ensure the alignment of the inner tube and the lower connecting piece, and the inner hole welding positioning tool is a semi-circular ring structure, and a reserved welding groove is formed in the inner hole welding positioning tool, the depth of the groove is the height of the back welding leg, which ensures the alignment of the inner tube and the lower connecting piece during assembly, ensures that the welding is not misaligned, and the contact end of the welding seam is a copper pad, which is not fused with the welding seam, a reserved welding groove is formed in the copper pad, the depth of the groove is the height of the back welding leg, which can ensure the quality of single-sided welding and double-sided forming of the welding seam, and greatly improves the welding seam qualification rate;

[0048] Step four: welding of the inner tube and the lower connecting piece;

[0049] The inner tube and the lower connecting piece are U-shaped grooves, and the inner tube and the lower connecting piece are non-isosceles angle structures, which expand the visible range during welding, and the inner hole welding seam is completed by M-GTAW welding, which ensures full penetration and improves the welding quality;

[0050] Step five: welding of the inner tube and the upper connecting piece;

[0051] The welding seam between the inner tube and the upper connecting piece after pre-stretching is a combined welding seam of a groove weld and a fillet weld, the groove is a single V-shaped groove, the angle is 40°, and the single-sided gap between the inner tube and the upper connecting piece is 3mm;

[0052] Step six: welding of the lower connecting piece and the lower cone;

[0053] The lower connecting piece and the lower cone adopt a nickel-based isolation layer by surfacing, the material of the lower connecting piece is SA-336MF22CL3, and the material of the lower cone is Incoloy800HT, in order to reduce the welding stress of dissimilar steel and avoid post-weld heat treatment, the lower connecting groove is changed, the groove and surfacing size are determined, the nickel-based isolation layer is surfaced at the groove position, and after the overall heat treatment of the inner and outer tube bundles, the same steel is welded with the lower cone, thereby improving the welding quality.

[0054] Example 3

[0055] According to the welding method of the double-sleeve structure rapid heat exchange tube bundle welding positioning tool of example 2, the inner hole welding positioning tool in step three is a semi-circular ring structure, and a reserved welding groove is formed in the inner hole welding positioning tool, the depth of the groove is the height of the back welding leg.

[0056] Example 4

[0057] According to the welding method of the double-sleeve structure rapid heat exchange tube bundle welding positioning tool of example 2, the U-shaped groove of the inner tube and the lower connecting piece in step four is a full penetration structure, specifically: the groove angle of the U-shaped groove is 90°, the included angle between the upper slope surface and the horizontal plane is 15°, and the inner slope surface has a thickness of 2mm between the vertical surface and the inner diameter of the inner tube, and a round corner with a radius of 2mm is formed between the upper slope surface and the inner slope surface.

[0058] Example 5

[0059] According to the welding method of the double-cannula structure quick heat exchange pipe bundle welding positioning tooling described in Embodiment 2, the inner pipe and the lower connecting groove positioning tooling are in contact with the copper pad at the welding seam end.

Claims

1. A welding method for a welding positioning fixture for a double-tube rapid heat exchange tube bundle, characterized in that: The welding and positioning fixture for the double-tube rapid heat exchange tube bundle includes a support base, a travel track, and multiple push trolleys. The multiple push trolleys are placed in the travel track, which is supported by the support base. A side positioning support frame is fixed on the support base. The welding method includes the following steps: Step 1: Pre-stretching of the inner tube; An internal resistance heating device is installed, and the heating temperature and heating time are controlled by a temperature control cabinet. The elongation of the tube after heating is calculated using the formula △L=L×a(T2-T1). Where: T2 is the heating temperature of the tube, T1 is the initial temperature of the tube, α is the coefficient of linear expansion, L is the heating length of the tube, and ΔL is the elongation of the tube; The heating length of the inner tube was determined to be L=2m, the heating temperature to be 320℃, the holding time to be 30min, and the inner tube to be extended by 4mm. Step 2: Inner and outer tubing assembly; During the pipe threading process, multiple trolleys are installed on the travel track. The inner tube is placed on the trolleys. The front end of the inner tube is mechanically pulled, and the rear end is assisted by the trolleys to move forward, pulling up the inner tube and moving forward with it. This ensures that the end of the inner tube enters the outer tube horizontally. The track side positioning support is used to prevent the inner tube from rotating, and a guide sleeve is installed at the end of the outer tube. Step 3: Weld positioning of the inner hole; An internal hole welding positioning fixture is used to ensure that the bevels of the inner tube and the lower connector are aligned. The internal hole welding positioning fixture is a semi-circular ring structure with a reserved welding groove inside, the groove depth of which is the height of the back weld foot. Step 4: Weld the inner tube to the lower connector; The bevel between the inner tube and the lower connector is a U-shaped bevel, and the bevel between the inner tube and the lower connector is a non-equiangular structure; Step 5: Weld the inner tube to the upper connector; The weld between the inner tube and the upper connector after pre-stretching is a combination of bevel weld and fillet weld. The bevel is a single V-shaped bevel with an angle of 40°. The gap between the inner tube and the upper connector on one side is 3mm. Step Six: Weld the lower connector to the lower cone; The lower connector and the lower cone are separated by a nickel-based overlay weld.

2. The welding method of the welding positioning fixture for the double-tube rapid heat exchange tube bundle according to claim 1, characterized in that: The inner hole welding positioning fixture in step three is a semi-circular ring structure with a reserved welding groove inside, the groove depth being the height of the back weld foot.

3. The welding method of the welding positioning fixture for the double-tube rapid heat exchange tube bundle according to claim 2, characterized in that: The U-shaped bevel between the inner tube and the lower connector in step four is a fully penetrated weld structure. Specifically, the bevel angle of the U-shaped bevel is 90°, the angle between the upper slope and the horizontal plane is 15°, the inner slope is a vertical surface with a thickness of 2mm between it and the inner diameter of the inner tube, and there is a rounded corner with a radius of 2mm between the upper slope and the inner slope.

4. The welding method of the welding positioning fixture for the double-tube rapid heat exchange tube bundle according to claim 3, characterized in that: The contact end between the inner tube and the lower connecting bevel positioning fixture and the weld seam is a copper pad.

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