A burner outer nozzle, a burner and a processing method of the burner outer nozzle

Abstract

The present invention provides an outer nozzle of a burner, a burner and a processing method of the outer nozzle of the burner. The outer nozzle includes an outer end cover (1), a short straight cooling water pipe (2), asbestos (3), a collar (4), a middle section (5) and a tail section (6); the outer end cover and the middle section are welded to form a head circulating water cavity. After the circulating water cavity is drilled, it is inserted into the short straight pipe and connected by a fillet weld. The collar is welded to the outer end cover and asbestos is filled between the collar and the short straight pipe. In the present invention, a collar or a baffle is added to the fire-facing side of the fillet weld between the outer end cover and the short straight pipe of the outer nozzle to protect the inserted fillet weld on the fire-facing side, so that the circulating water cavity is not easily leaked, thereby improving the reliability and safety of the operation of the process burner.

Description

Technical Field

[0001] The present invention belongs to the technical field of coal chemical industry of pressurized coal water slurry gasification, and particularly relates to an outer nozzle of a burner, a burner, and a processing method of the outer nozzle of the burner. Background Art

[0002] The coal water slurry process burner is a key component of the pressurized coal water slurry gasification technology, and it works in an environment of high temperature of 1300 °C and high pressure. The known structure of the coal water slurry process burner is composed of an inner nozzle, a middle nozzle, and an outer nozzle which are coaxially sleeved from the inside to the outside and have a streamlined front closing end, and it is a three-flow internal and external mixing atomization form. The outer flow channel of the outer nozzle and the inner flow channel of the inner nozzle transport high-pressure oxygen, the middle flow channel of the middle nozzle transports high-pressure coal water slurry, after the oxygen in the inner flow channel and the coal slurry in the middle flow channel are semi-premixed, they are further mixed and atomized evenly with the outer ring oxygen at the nozzle; there is a cooling water cavity at the head of the outer nozzle of the outer nozzle, and an external cooling water coil is connected to cool and protect the outer nozzle of the process burner.

[0003] The process burner usually works under harsh conditions of high temperature and high pressure. After the process burner operates in a high-temperature furnace above 1000 °C for a period of time, the deformation of the outer ring oxygen channel causes the furnace flame to move upward, and the high temperature causes the head of the outer nozzle to be prone to high-temperature oxidation corrosion cracks; under the scouring of the furnace flame and materials, the cooling water cavity of the outer nozzle often has a leakage risk. The traditional outer nozzle of the process burner is connected to the coil through a fillet weld after being inserted. This fillet weld is located on the fire-facing surface of the process burner. It is often eroded by the flame and materials for a long time, and cracks are prone to appear at this fillet weld, resulting in leakage of the process burner. In the light case, it will cause a shutdown and furnace reversal, and in the heavy case, the refractory brick of the gasifier will be quenched and spalled, and the synthesis gas will leak and explode, affecting the continuous operation of the factory. Summary of the Invention

[0004] In order to overcome the deficiencies in the prior art, the inventors of the present invention have conducted intensive research and provided an outer nozzle of a burner, a burner, and a processing method of the outer nozzle of the burner. Through the structural design of the outer nozzle of the burner, the fillet weld on the fire-facing surface is protected, avoiding the radiation of high-temperature gas flow to the fillet weld and the erosion of materials, improving the operation reliability of the process burner, and the processing scheme has a low cost and is conducive to industrialization promotion, thus completing the present invention.

[0005] The technical solutions provided by the present invention are as follows:

[0006] In a first aspect, an outer nozzle of a burner includes an outer end cover, a short cooling water straight pipe, asbestos, a collar, a middle section, and a tail section;

[0007] The outer end cap and the middle section are welded to form the circulating water cavity of the outer nozzle head. The cooling water in the circulating water cavity is circulated through the short straight cooling water pipe. The collar is sleeved outside the short straight cooling water pipe and welded to the outer end cap, surrounding the inserted fillet weld between the outer end cap and the short straight cooling water pipe, and asbestos is filled between the collar and the short straight cooling water pipe. The middle section is welded to the tail section to form the cavity of the outer nozzle.

[0008] In a second aspect, a burner includes an inner nozzle and an outer nozzle coaxially sleeved, or an inner nozzle, a middle nozzle and an outer nozzle coaxially sleeved, and the outer nozzle is the outer nozzle described in the first aspect.

[0009] In a third aspect, a processing method for the outer nozzle of a burner is used to process the outer nozzle of the burner described in the first aspect, and includes the following steps:

[0010] Step (1): Use a lathe to finish machining the circulating water cavity on one side of the outer end cap. Among them, the thickness of the fire-facing surface of the outer end cap is 5 mm to 10 mm.

[0011] Step (2): Use a lathe to finish machining the inner wall of the circulating water cavity on one side of the middle section, and then use a lathe to finish turning the middle section and the tail section.

[0012] Step (3): Splice the outer end cap, the middle section and the tail section by welding, and complete the combined machining of the inner profile of the outer nozzle.

[0013] Step (4): Finish machining the nozzle orifice and the outer shape of the outer nozzle according to the drawing dimensions.

[0014] Step (5): Use a milling machine to finish machining the short straight pipe insertion holes and the short straight pipe welding grooves on the outer wall surface of the outer end cap at an interval of 180°. The short straight pipe insertion holes and the short straight pipe welding grooves are used for inserting and mating with the short straight cooling water pipe.

[0015] Step (7): Fix the short straight cooling water pipe in the insertion hole of the outer end cap by welding.

[0016] Step (8): Machine the collar with a lathe. The wall thickness of the collar is 2 mm to 5 mm, the length is 15 mm to 30 mm, the annular gap between the collar and the short straight cooling water pipe is 3 mm to 4 mm, and an arc-shaped groove is opened at the bottom to match the cylindrical surface of the outer end cap.

[0017] Step (9): Fix the collar on the outer end cap by welding.

[0018] According to the outer nozzle of a burner, the burner and the processing method for the outer nozzle of a burner provided by the present invention, the following beneficial effects are achieved:

[0019] (1) A burner outer nozzle, a burner, and a processing method of the burner outer nozzle provided by the present invention protect the inserted fillet weld between the short straight pipe and the outer nozzle by welding a collar and filling asbestos or a baffle, reducing the leakage probability of the cooling water chamber of the process burner and improving the reliability and safety of the operation of the process burner; after adding a protective collar to the outer nozzle of the process burner in a certain project according to the present invention, the service life of the process burner is increased from about 40 days to about 60 days, greatly improving the operation stability of the process burner and the gasifier, and further enhancing the continuous operation ability of the factory and increasing production capacity;

[0020] (2) A burner outer nozzle, a burner, and a processing method of the burner outer nozzle provided by the present invention. The burner outer nozzle is processed in a split manner, which reduces the cost compared with the integrated forming scheme of the short straight pipe at the burner head and the outer end cover. At the same time, it reduces the outer dimension of the coiled pipe, facilitating the installation and removal of the burner on the gasifier and reducing the occurrence of coiled pipe fracture. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is a schematic structural diagram of a burner outer nozzle in an embodiment of the present invention;

[0022] Figure 2 is Figure 1 a schematic structural diagram of the collar in

[0023] Figure 3 is a schematic structural diagram of a burner outer nozzle in another embodiment of the present invention.

[0024] DESCRIPTION OF THE REFERENCE NUMERALS IN THE DRAWINGS

[0025] 1 - outer end cover; 2 - short cooling water pipe; 3 - asbestos; 4 - collar; 5 - middle section; 6 - tail section; 7 - arc groove; 8 - baffle. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The present invention will be described in detail below, and the features and advantages of the present invention will become clearer and more definite with these descriptions.

[0027] In order to solve the problem that the fillet weld is prone to cracks resulting in leakage of the process burner, the structure of the outer nozzle is redesigned. A collar is added outside the inserted fillet weld between the short straight pipe and the burner outer nozzle, and asbestos heat insulation is added inside the collar to protect the fillet weld, reducing the leakage problem of the circulating water chamber caused by the failure of this weld, thereby improving the reliability and safety of the operation of the process burner.

[0028] Specifically, according to the first aspect of the present invention, a burner outer nozzle is provided, as Figure 1 shown, including: an outer end cover 1, a short cooling water pipe 2, asbestos 3, a collar 4, a middle section 5, and a tail section 6;

[0029] The outer end cover 1 and the middle section 5 are welded to form a circulating water cavity at the head of the external nozzle, and the cooling water circulation of the circulating water cavity is implemented through the short straight cooling water pipe 2; the collar 4 is sleeved on the outside of the short straight cooling water pipe 2 and welded to the outer end cover 1, enclosing the plug-in fillet weld between the outer end cover 1 and the short straight cooling water pipe 2, and filling asbestos 3 between the collar 4 and the short straight cooling water pipe 2; the middle section 5 and the tail section 6 are welded and connected to form the cavity of the external nozzle.

[0030] In the present invention, considering the influence of material strength and thermal stress, the thickness of the fire-facing surface of the outer end cover 1 is 5 mm to 10 mm.

[0031] In the present invention, the material used for the collar 4 is a high-temperature alloy such as UMCo50 or Haynes188, with a wall thickness of 2mm to 5mm and a length of 15mm to 30mm. After research, the inventors found that because the collar 4 needs to face the flames and material erosion above 1000°C in the furnace, ordinary materials cannot withstand long-term use and will be burned, so high-temperature alloys such as UMCo50 or Haynes188 are required; the collar 4 needs to have sufficient strength to face the flames and material erosion, but due to the limited operating space, the wall thickness is selected to be 2mm to 5mm; the operating space in the length direction of the welding collar is limited, and if it is too long, it cannot be coaxial with the short straight cooling water pipe 2 to ensure a uniform gap between the two, and if it is too short, the protective effect is reduced, so the length is determined to be 15mm to 30mm.

[0032] In the present invention, the annular gap between the collar 4 and the short straight cooling water pipe 2 is 3mm to 4mm. The weld angle height between the short straight cooling water pipe 2 and the outer end cover 1 is about 3mm to 4mm. The annular gap of 3mm to 4mm can minimize the adverse effects such as repeated heating and stress concentration caused by the weld between the collar 4 and the outer end cover 1 on the weld between the short straight cooling water pipe 2 and the outer end cover 1.

[0033] In the present invention, Figure 2 As shown, the connection surface between the collar 4 and the outer end cover 1 is arc-shaped, and the arc-shaped groove 7 is 35° to 55°. In order to fully protect the fillet weld between the short straight cooling water pipe 2 and the outer end cover 1, the bottom connection of the collar 4 is processed into an arc that matches the cylindrical surface of the outer end cover 1, and then a 35° to 55° groove is cut on this arc surface. This groove prevents the inner wall of the collar 4 from overlapping with the plug-in fillet weld due to excessive angle height of the plug-in fillet weld without increasing the size of the collar, while ensuring a small gap at the root of the weld.

[0034] In the present invention, the weld between the collar 4 and the outer end cover 1 is full weld or intermittent weld. When the weld between the collar 4 and the outer end cover 1 is full weld, the welding method is tungsten inert gas shielded welding, the welding current is 120±5A, the nozzle diameter is Φ12mm, the shielding gas is high-purity 99.99% argon, the argon flow rate is 12±1L / min, and the welding wire diameter is 100mm. Welding speed: 10 - 12 cm / min;

[0035] When the weld between the ferrule 4 and the outer end cap 1 is intermittent welding, the welding method is tungsten inert gas shielded welding. Weld 1 / 4 circle on the fire-facing side, and the intermittent welding length of the remaining 3 / 4 circle is 5 mm - 10 mm, with an interval of 15 mm - 20 mm. Welding current: 120 ± 5 A, nozzle diameter: Φ12 mm. The shielding gas uses high-purity 99.99% argon, argon gas flow rate: 12 ± 1 L / min, wire diameter Welding speed: 5 - 6 cm / min.

[0036] In the present invention, in addition to using ferrules and asbestos for protection, the inserted fillet weld can also directly weld a baffle 8 (made of high-temperature alloys such as UMCo50 or Haynes188) on the outer end cap towards the fire-facing side before the inserted fillet weld. The thickness is 2 mm - 5 mm, as Figure 3 shown. This baffle can block the frontal erosion and radiation received by the fillet weld, and the rest is exactly the same as the ferrule scheme. This method can, to a certain extent, reduce the failure probability of this fillet weld, extend the service life of the process burner, and improve the operation reliability of the process burner.

[0037] According to the second aspect of the present invention, there is provided a burner, including an inner nozzle and an outer nozzle coaxially sleeved, or an inner nozzle, a middle nozzle and an outer nozzle coaxially sleeved, and the outer nozzle selects the outer nozzle described in the first aspect.

[0038] According to the third aspect of the present invention, there is provided a processing method for the outer nozzle of a burner, used for processing the outer nozzle of the burner described in the first aspect, including the following steps:

[0039] Step (1), use a lathe to finish machining the circulating water cavity on one side of the outer end cap 1, wherein the thickness of the fire-facing side of the outer end cap 1 is 5 mm - 10 mm;

[0040] Step (2), use a lathe to finish machining the inner wall of the circulating water cavity on one side of the middle section 5, and then use a lathe to finish turning the middle section 5 and the tail section 6;

[0041] Step (3), use welding to splice the outer end cap 1, the middle section 5 and the tail section 6, and complete the combined machining of the inner profile of the outer nozzle;

[0042] Step (4), finish machining the nozzle and the outer shape of the outer nozzle according to the drawing dimensions;

[0043] Step (5), use a milling machine to finish machining the short straight pipe insertion holes and the short straight pipe welding grooves on the outer wall of the outer end cap 1 at an interval of 180°. The short straight pipe insertion holes and the short straight pipe welding grooves are used for inserting and mating with the cooling water short straight pipe 2;

[0044] Step (7), fix the short straight cooling water pipe 2 in the socket hole of the outer end cover 1 by welding;

[0045] Step (8), machine the collar 4 on a lathe. The wall thickness of the collar 4 is 2 mm to 5 mm, the length is 15 mm to 30 mm, the annular gap between it and the short straight cooling water pipe 2 is 3 mm to 4 mm, and an arc-shaped groove is opened at the bottom to match the cylindrical surface of the outer end cover 1. The bottom gap should be as small as possible;

[0046] Step (9), fix the collar 4 on the outer end cover 1 by welding.

[0047] In the present invention, in step (3), the thickness of the shell between the circulating water cavity and the outer nozzle cavity is generally 5 mm to 10 mm; thus, effective thin-wall welding needs to be carried out between the outer end cover 1 and the middle section 5 to avoid leakage of the circulating water cavity at the weld. For this reason, research on the welding of this thin-wall structure has been carried out, and the tungsten inert gas shielded welding method is determined. The welding process parameters are: tungsten inert gas shielded welding, welding current 130 ± 5 A, nozzle diameter Φ12 mm, the shielding gas uses high-purity 99.99% argon, argon gas flow rate 12 ± 1 L / min, wire diameter Welding speed 10 - 12 cm / min.

[0048] In step (3), the welding of the middle section 5 and the tail section 6 should ensure that they meet the dimensional requirements of the coaxiality tolerance on the drawing. The welding method of the middle section 5 and the tail section 6 is determined to be tungsten inert gas shielded welding. The welding process parameters are: welding current 150 ± 5 A, nozzle diameter Φ12 mm, the shielding gas uses high-purity 99.99% argon, argon gas flow rate 12 ± 1 L / min, wire diameter Welding speed 10 - 12 cm / min.

[0049] In the present invention, in step (9), the weld between the collar 4 and the outer end cover 1 is full weld or intermittent weld. When the weld between the collar 4 and the outer end cover 1 is full weld, the welding method is tungsten inert gas shielded welding, welding current 120 ± 5 A, nozzle diameter Φ12 mm, the shielding gas uses high-purity 99.99% argon, argon gas flow rate 12 ± 1 L / min, wire diameter The welding speed is 10 - 12 cm / min. Through practical research, it is found that if the welding current is too small, it is difficult to strike an arc and the arc is unstable, which easily causes defects such as incomplete penetration and slag inclusion. If it is too large, it is easy to cause defects such as burn-through and undercut. If the welding speed is too fast, the molten pool temperature is insufficient, which is likely to cause defects such as incomplete penetration, lack of fusion, and poor weld formation. If it is too slow, the high-temperature residence time increases, the width of the heat-affected zone increases, the grains of the welded joint become coarser, the mechanical properties decrease, and at the same time, the deformation amount increases. If the argon gas flow rate is too large, the protective layer will have irregular flow, causing air to be involved and reducing the protection effect. If the argon gas flow rate is too small, air will invade the molten pool, reducing the gas protection effect. If the nozzle diameter is too small, the protected area will decrease. If it is too large, it will affect the operator's line of sight.

[0050] When the weld between the collar 4 and the outer end cover 1 is intermittent welding, the welding method is tungsten inert gas shielded welding. Weld 1 / 4 circle on the fire-facing side, and the intermittent welding length of the remaining 3 / 4 circle is 5 mm - 10 mm, and the interval is 15 mm - 20 mm. The welding current is 120 ± 5 A, the nozzle diameter is Φ12 mm, the shielding gas uses high-purity 99.99% argon, the argon gas flow rate is 12 ± 1 L / min, and the wire diameter The welding speed is 5 - 6 cm / min. The difference between this intermittent welding and the full welding is that the intermittent welding reduces the welding speed. While ensuring the firm welding of the collar 4 and the outer end cover 1, it reduces the influence of the heat generated by this weld on the performance of the inserted fillet weld. Other welding process parameters are basically the same as those in full welding. The welding parameters of the collar 4 and the outer end cover 1 are conducive to ensuring the stability of the installation position of the collar, such as the stability of the gap between the collar and the short straight cooling water pipe, and improving the protection degree of the inserted fillet weld between the outer nozzle and the coil.

[0051] In the present invention, steps (8) and (9) are replaced with: Fix the baffle 8 on the outer end cover 1 by welding. The material of the baffle 8 is a high-temperature alloy such as UMCo50 or Haynes188, and the thickness is 2 mm - 5 mm. The welding method is tungsten inert gas shielded welding, the welding current is 130 ± 5 A, the nozzle diameter is Φ12 mm, the shielding gas uses high-purity 99.99% argon, the argon gas flow rate is 12 ± 1 L / min, and the wire diameter The welding speed is 10 - 12 cm / min. This weld only needs to satisfy the firm welding of the baffle 8 and the outer end cover 1. Therefore, only increase the welding current on the basis of the full welding process parameters of the collar 4.

[0052] Using the method of the present invention to process the outer nozzle of the burner reduces the cost compared with the integrated forming scheme of the short straight pipe of the burner head and the outer end cover. At the same time, it reduces the external dimension of the coil, which is convenient for the installation and removal of the burner on the gasifier and reduces the occurrence of coil fracture.

[0053] The present invention has been described in detail in connection with specific embodiments and exemplary examples, but these descriptions should not be construed as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications or improvements can be made to the technical solutions of the present invention and their implementation manners, and these all fall within the scope of the present invention. The protection scope of the present invention shall be subject to the appended claims.

[0054] The content not detailedly described in the specification of the present invention belongs to the well-known technology of those skilled in the art.

Claims

1. A burner outer nozzle, characterized in that, Comprising: An outer end cap (1), a short straight cooling water pipe (2), asbestos (3), a collar (4), a middle section (5) and a tail section (6); The outer end cap (1) is welded to the middle section (5) to form a circulating water cavity for the cooling water of the outer nozzle head. The cooling water circulation of the circulating water cavity is implemented through the short straight cooling water pipe (2). The collar (4) is sleeved outside the short straight cooling water pipe (2) and welded to the outer end cap (1), surrounding the inserted butt weld between the outer end cap (1) and the short straight cooling water pipe (2), and asbestos (3) is filled between the collar (4) and the short straight cooling water pipe (2); The middle section (5) is welded to the tail section (6) to form the cavity of the outer nozzle; The material used for the collar (4) is a high-temperature alloy such as UMCo50 or Haynes188, with a wall thickness of 2 mm to 5 mm and a length of 15 mm to 30 mm; The connecting surface between the collar (4) and the outer end cap (1) is arc-shaped, and the arc-shaped groove (7) is 35° to 55°.

2. The outer nozzle of the burner according to claim 1, characterized in that, The thickness of the fire-facing surface of the outer end cap (1) is 5 mm to 10 mm.

3. The outer nozzle of the burner according to claim 1, characterized in that, The annular gap between the collar (4) and the short straight cooling water pipe (2) is 3 mm to 4 mm.

4. The external nozzle of the burner according to claim 1, characterized in that The weld between the collar (4) and the outer end cap (1) is a full weld, and the welding process parameters are: tungsten inert gas shielded welding is adopted, the welding current is 120 ± 5 A, the nozzle diameter is Φ12 mm, the shielding gas is high-purity 99.99% argon, the argon gas flow rate is 12 ± 1 L / min, the wire diameter is φ2.5 mm, and the welding speed is 10 to 12 cm / min; and / or When the weld between the collar (4) and the outer end cap (1) is an intermittent weld, 1 / 4 of a circle is welded on the fire-facing surface, and the length of the intermittent weld for the remaining 3 / 4 of a circle is 5 mm to 10 mm, and the interval is 15 mm to 20 mm. The welding process parameters are: tungsten inert gas shielded welding is adopted, the welding current is 120 ± 5 A, the nozzle diameter is Φ12 mm, the shielding gas is high-purity 99.99% argon, the argon gas flow rate is 12 ± 1 L / min, the wire diameter is φ2.5 mm, and the welding speed is 5 to 6 cm / min.

5. A burner, characterized in that, Comprising an inner nozzle and an outer nozzle coaxially arranged, or an inner nozzle, a middle nozzle and an outer nozzle coaxially arranged, and the outer nozzle selects the outer nozzle described in any one of claims 1 to 4.

6. A processing method for an outer nozzle of a burner, characterized in that, For machining the burner outer nozzle described in any one of claims 1 to 4, the following steps are included: Step (1), use a lathe to finish machining the circulating water cavity on one side of the outer end cap (1), wherein the thickness of the fire-facing surface of the outer end cap (1) is 5 mm to 10 mm; Step (2), use a lathe to finish machining the inner wall of the circulating water cavity on one side of the middle section (5), and then use a lathe to finish turning the middle section (5) and the tail section (6); Step (3), splice the outer end cap (1), the middle section (5) and the tail section (6) by welding, and complete the combined machining of the inner profile of the outer nozzle; Step (4), finish machining the nozzle orifice and the outer shape of the outer nozzle according to the drawing dimensions; Step (5), use a milling machine to complete the machining of the short straight pipe insertion holes and the short straight pipe welding grooves on the outer wall surface of the outer end cap (1) at an interval of 180°. The short straight pipe insertion holes and the short straight pipe welding grooves are used for inserting and mating with the short straight cooling water pipe (2); Step (7), fix the short cooling water straight pipe (2) in the insertion hole of the outer end cover (1) by welding; Step (8), machine the collar (4) on a lathe. The wall thickness of the collar (4) is 2 mm to 5 mm, the length is 15 mm to 30 mm, the circumferential gap between it and the short cooling water straight pipe (2) is 3 mm to 4 mm, and an arc-shaped groove is opened at the bottom to match the cylindrical surface of the outer end cover (1); Step (9), fix the collar (4) on the outer end cover (1) by welding.

7. The processing method according to claim 6, wherein In step (3), the welding method between the outer end cover (1) and the middle section (5) is tungsten inert gas shielded welding. The welding process parameters are: welding current 130 ± 5 A, nozzle diameter Φ12 mm, the shielding gas is high-purity 99.99% argon, argon gas flow rate 12 ± 1 L / min, wire diameter φ2.5 mm, welding speed 10 - 12 cm / min; and / or The welding method for the middle section (5) and the tail section (6) is tungsten inert gas shielded welding. The welding process parameters are: welding current 150 ± 5 A, nozzle diameter Φ12 mm, the shielding gas is high-purity 99.99% argon, argon gas flow rate 12 ± 1 L / min, wire diameter φ2.5 mm, welding speed 10 - 12 cm / min.

8. The processing method according to claim 6, wherein In step (9), when the weld between the collar (4) and the outer end cover (1) is a full weld, the welding method is tungsten inert gas shielded welding, welding current 120 ± 5 A, nozzle diameter Φ12 mm, the shielding gas is high-purity 99.99% argon, argon gas flow rate 12 ± 1 L / min, wire diameter φ2.5 mm, welding speed 10 - 12 cm / min; and / or When the weld between the collar (4) and the outer end cover (1) is an intermittent weld, the welding method is tungsten inert gas shielded welding. Weld 1 / 4 of a circle on the fire-facing side, and the length of the intermittent weld for the remaining 3 / 4 of the circle is 5 mm to 10 mm, the interval is 15 mm to 20 mm, welding current 120 ± 5 A, nozzle diameter Φ12 mm, the shielding gas is high-purity 99.99% argon, argon gas flow rate 12 ± 1 L / min, wire diameter φ2.5 mm, welding speed 5 - 6 cm / min.

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