KR101153878B1 - Method for manufacturing fin tube using in the heat recovery steam generator - Google Patents

Abstract

The present invention relates to a method for manufacturing a fin tube for HRSG, comprising: roughing an outer surface of a pipe-shaped long tube (100) made of 347H material; Root 210 and the root made of any one of the material of C / S, T409, 304H, T410 on the outer surface and the tube (100) welded to the outer surface at the same time to rotate the rough processing In the HRSG fin tube manufacturing method for manufacturing a fin tube for waste heat recovery boiler by the high-frequency welding while winding the strip-shaped fin 200 comprising a plurality of segments 220 extending from 210; The outer diameter of the tube 100 is limited to 26.9 ~ 76mm, the segment height (SH) of the pin 200 is maintained at 8 ~ 25.4mm, the thickness (T) of the pin 200 is 0.8 ~ 1.5mm Segment width (SW) is maintained at 3.8 ~ 4.4mm, height RH excluding segment height (SH) from the pin 200 is maintained at 5 ~ 7mm, the interval between the pins 200 (D) is maintained at 2.5 ~ 6.6 inches, the welding conditions when welding the pin 200, welding speed 100 ~ 300rpm, output 120KW, input current 300A, anode voltage 9 ~ 10KV, anode current 16 ~ 17A, grating The current is maintained at 3.0 to 3.2A.
The present invention has the effect of improving the precision, preventing welding defects, and always maintaining a constant product quality when equipped with a specific welding conditions according to the material when the continuous welding while winding a thin strip-shaped pin spirally on the outer peripheral surface of the tube on the pipe Can be obtained.

Description

METHOD FOR MANUFACTURING FIN TUBE USING IN THE HEAT RECOVERY STEAM GENERATOR}

The present invention relates to a method for manufacturing a fin tube for HRSG, and more particularly, it is possible to stably weld while maintaining a sufficient bonding strength during high frequency welding coupling of a plurality of fins arranged relatively narrowly outside the tube, and durability and efficiency It relates to a method for manufacturing a fin tube for HRSG using a 347H type tube.

In general, a heat recovery steam generator (Heat Recovery Steam Generator) is applied in a cogeneration plant and the like to improve the thermal efficiency, which is referred to as "HRSG".

In general, when power is produced through a gas turbine in a power plant or the like, the exhaust gas generates high heat of approximately 200-550 ° C., thus, the exhaust gas itself may be considered to contain a significant amount of energy.

Therefore, when such exhaust gas is discharged to the atmosphere as it is, a considerable amount of energy is lost, resulting in energy loss. Recently, various methods for recovering energy from the emitted exhaust gas and using it for other purposes have been proposed. This HRSG is one of them.

The waste heat recovery boiler system (HRSG) generates steam by using exhaust gas to be discharged into the atmosphere, and is used to generate another energy, which is another energy by driving a steam turbine with the generated steam.

At this time, the waste heat recovery boiler is provided with a plurality of heat exchangers to obtain steam through heat exchange from the exhaust gas of the gas turbine, the heat exchanger is a fin tube having a zigzag shape is applied.

The fin tube structure of the heat exchanger generally has a hollow tube and a plurality of fins having a predetermined area on the outside of the tube. The reason for coupling the fin to the tube is known as a thermal contact surface. This is to maximize heat exchange efficiency.

A typical fin tube may be a spiral finned tube, which has a merit in that the process can be continuously maintained without disconnection by forming a spiral wound around the outer circumferential surface of the tube.

However, there is a problem that wrinkles occur in manufacturing on the fin of the conventional helical fin tube, and this wrinkle has the disadvantage of rapidly increasing the flow resistance on the air side passing through the heat exchanger, and fin welding must be performed to reduce the contact resistance between the fin and the tube. In addition, there is a problem in that the spiral surface treatment at the position where the pin is attached, and the productivity is lowered than expected.

In addition, the outer circumferential surface of the tube was treated with a rust preventive agent or smoothly when the pin is coupled to the outside of the tube, so that the welding is not easy when welding. Although the work is polished with paper, etc., the performance is degraded and there is a problem that pollutes the environment due to the excessive consumption of the belt paper and the cost increase and the re-use after disposal is not possible. There has been a problem that the indoor working environment is vulnerable.

Accordingly, the productivity is greatly improved, the heat transfer area can be sufficiently secured, and a new type of heat exchanger that is advantageous in terms of flow resistance is required, and a production method and apparatus thereof are urgently required, and as a part of the three researches completed by the present inventors A finned tube of the rate solid type has been disclosed.

However, since such fin tubes are specially used, carbon, silicon, manganese, phosphorus, sulfur, aluminum, copper, chromium, nitrogen, nickel, molybdenum, vanadium, niobium, cobalt, tungsten, boron, titanium, etc. Because of the high level of manufacturing technology required, physical properties can reach the design strength, that is, the desired bonding strength, depending on how the raw materials, high frequency welding conditions, structural specifications of the fins, and processing specifications are controlled. It depends on whether you are present or not.

However, up to now, such conditions are not limited, and according to the skill of the operator, the quality difference occurs for each product, resulting in low stability and efficiency, and high defective rate.

The present invention was created in view of the above-mentioned problems in the prior art, and was created to solve this problem. In order to standardize the fin tube and the fin coil made of special materials in an optimal state and maintain the same quality characteristics, the specification of the raw materials The main object of the present invention is to provide a manufacturing method capable of manufacturing a fin tube for HRSG having uniform and uniform characteristics by clearly defining the back and the like.

The present invention is a means for achieving the above object, the present invention is to rough the pipe-shaped long tube outer surface made of 347H material; Rotating the roughened tube and at the same time the outer surface of the material made of any one of C / S, T409, 304H, T410, including a route welded to the tube and a plurality of segments extending from the route In the HRSG fin tube manufacturing method for manufacturing a fin tube for waste heat recovery boiler by high frequency welding while winding the fin of the shape in a spiral; The outer diameter of the tube is limited to 26.9 ~ 76mm, the segment height (SH) of the fin is maintained at 8 ~ 25.4mm, the thickness (T) of the fin is limited to 0.8 ~ 1.5mm, the segment width (SW) Is maintained at 3.8 ~ 4.4mm, the height (RH) excluding the segment height (SH) from the pin is maintained at 5 ~ 7mm, the spacing (D) between the pins is maintained at 2.5 ~ 6.6 inches, Welding conditions during welding are characterized in that the welding speed is maintained at 100 ~ 300rpm, output 120KW, input current 300A, anode voltage 9 ~ 10KV, anode current 16 ~ 17A, grid current 3.0 ~ 3.2A.

According to the present invention, it is equipped with a specific welding conditions according to the material when welding continuously while winding a thin strip-shaped pin spirally on the outer peripheral surface of the pipe on the pipe to improve the precision, prevent welding failure, and always maintain a constant product quality The effect can be obtained.

1 is a schematic diagram of a fin tube manufactured by the manufacturing method according to the present invention.
Figure 2 is a cross-sectional view of the main portion of the fin tube manufactured by the manufacturing method according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram of a fin tube according to the present invention, Figure 2 is a cross-sectional view of the main part according to the present invention.

As shown in Figure 1 and 2, the fin tube according to the present invention is utilized as a heat exchange means for waste heat recovery boiler that is applied to improve the thermal efficiency in cogeneration plants and the like.

Finned tube according to the present invention is composed of a tube 100 of the pipe-shaped, a band-shaped fin 200 is wound high frequency while spirally wound along the outer peripheral surface of the tube (100).

A very important technical condition in the production of the fin tube used in the waste heat recovery boiler (HRSG) is how long the tube 100 extends in the longitudinal direction in order to improve thermal efficiency than a general design product within a predetermined period. More pins 200 can be continuously welded with high frequency automatically.

In order to produce a fin tube requiring such a high production condition, it is necessary to be able to weld the fin 200 to the tube 100 in a constant and vertical manner under mechanical operating conditions and high frequency welding conditions.

In particular, the material of the tube 100 and the pin coil for manufacturing the pin 200 used in the present invention is a special material (C, Si, Mn, P, S, Al, Cu, Cr, Ni, Mo, V, Nb / Cb). , Co, N, W, B, Ti)), it is required to accurately grasp the characteristics of these materials and to have welding conditions, raw material standards, etc. accordingly.

However, the quality characteristics of the product were uneven because until now, welding has been performed according to the skill of the operator without accurately grasping such material characteristics.

Moreover, the field to which the present invention belongs is the surface of the tube 100, which is a welding base material, because it is manufactured by rotating the tube 100, which is a metal material, at a constant speed, by welding the band-shaped pin 200 in a spiral manner on its outer circumferential surface, Despite the fact that there are many factors that have a significant impact on the final quality, such as the thickness of the pin 200, the welding conditions, the rotational speed of the tube 100, and the pitch of the spiral coil 200 spirally wound up to now, There was no standardization of working conditions.

The present invention is applied to the pre- filed serrate and solid type method, this method is the outer peripheral surface of the tube 100 by unwinding the pin 200 wound on the take-up roll while continuously transferring the heat-treated tube 100 after roughing the material It is made in the form of high frequency welding while winding in a spiral.

At this time, rough grinding (Rough Grinding) refers to a method of roughly processing the material, by making the outer surface of the material somewhat roughened it becomes easy to manufacture a pin tube of the serrate type (Serrated Type).

When the present invention fin tube is manufactured in this manner, the tube 100 preferably uses 347H, and the fin coil constituting the fin 200 is carbon steel (Carbon Steel), C / S, stainless steel (SUS). As T409, 304H, T410 is preferably used.

Here, the symbol of the metal material is in accordance with JIS classification.

In addition, the pin 200 should be fused to the tube 100 while receiving a constant pressure, and the voltage, output, welding speed, separation distance from the welding point W to the energization point of the high frequency welding machine for high frequency welding, etc., are of final quality. Is a very important factor that directly affects.

This is because the pin 200 released from the take-up roll (not shown) on the outside of the tube 100 continuously rotated should be stably automatically welded to the outer circumferential surface of the tube 100.

In addition, to summarize the terminology for each part of the fin tube shape of this type, as shown in Figure 2 (a), the pin 200 is a root (root) 210 is welded to the tube 100, and the root ( A segment 220 having an incision extending from 210, the length (or width) of the length of the root 210, ie, the distance (or width) from the tube 100 surface to the start of the segment 220. The height (hereinafter referred to as 'root height') (RH), and the length of the segment 220 is called the segment height (SH), the segment width (SW) of each segment is kept constant While spirally wound.

In addition, as shown in (b) of FIG. 2, the depth WD of the welding spot, the thickness T of the fin 200, and the spacing D between the fins 200 are determined based on the welding spot W. FIG. Can be done.

At this time, the welding point (W) is the position of the tube 100 to which the pin 200 is attached, and the conduction point refers to the position where the conductor of the high frequency welder is arranged for energization.

In the present invention, the outer diameter (OD) of the tube 100 is specifically limited to the size of 26.9 ~ 76mm.

The reason for limiting the outer diameter of the tube 100 is because it is the outer diameter most suitable for manufacturing the serrate solid type fin tube proposed by the present inventor, and there is no special limitation reason. The present invention is not limited to the aperture other than this, and provides only a manufacturing method through a standard applied to the tube 100 in the aperture.

The pin 200 protrusion height, that is, the segment height SH which is most suitable for the outer diameter of the tube 100 according to the present invention is maintained at 8 to 25.4 mm that is most suitable for smooth operation while excluding interference with the spiral high frequency automatic welding machine. do.

If out of the above range protrudes lower than 8mm, the heat exchange efficiency is lowered, and if it exceeds 25.4mm, workability is lowered because it is hindered during welding.

In addition, the thickness (T) of the fin 200 should be limited to 0.8 ~ 1.5mm, if the thickness of less than 0.8mm, heat is easily supersaturated during heat transfer, the heat exchange efficiency is lowered, if the heat transfer rate exceeds 1.5mm Since it lowers the thermal effect efficiency as well, it should be limited to the above range.

In addition, the segment width (SW) is preferably 3.8 to 4.4mm, and should be a solid type.

In addition, the height RH excluding the segment height SH from the fin 200 should be maintained at 5 to 7 mm to maintain the maximum heat transfer efficiency, which is the thickness T and the spacing D of the fin 200. And considering the height (SH) of the segment is calculated in contrast.

In addition, the spacing (D) of the fin 200, that is, the pitch should be maintained at 6.6 inches or less, if it exceeds this is advantageous for welding work, but the spacing is too wide to reduce the heat exchange efficiency to maintain the maximum range At least 2.5 inches should be maintained in consideration of welding workability and mass productivity.

On the other hand, the welding conditions required for high-frequency welding, according to the specifications of the raw materials described above, the welding speed is 100 ~ 600rpm, output 100 ~ 200KW, input current 300 ~ 350A, anode voltage 9 ~ 12KV, anode current 16 ~ 20A, lattice current should be maintained at 3.0 ~ 3.5A.

Here, the reason for this limitation is serrated and solid fin tube welding, especially in the case of the above-mentioned special materials, when the welding speed is 100 rpm or less, the welding point becomes wider and the fusion property is lowered, and 600 rpm If it is exceeded it should be limited to the above range because the welding failure may occur due to the cosmetic contact, the material of the tube 100 having the welding speed and the serrate type surface in the case of the input current and the anode voltage or current, including the welding output and This is because it is the most reasonable range in consideration of the thickness of the pin 200 and the like.

When welding through such a condition, as shown in FIG. 2 (b), it is possible to complete a fin tube having a stable welding point (W).

In particular, the serrate and solid type fin tubes can be manufactured to have a more durable and always even and uniform product quality.

In summary, referring to the composition of the raw material of the tube 100 and the pin 200 according to the composition of the ingredients are shown in Table 1 below.

At this time, the composition ratio of 347H may have a slight difference depending on the characteristics, which is considered as a reference.

In addition, the welding conditions of the 347H described above are comprehensively described.

T ... tube F ... pin
W .... welding

Claims (1)

Roughing the outer surface of the pipe-shaped long tube 100 made of 347H material; Root 210 and the root made of any one of the material of C / S, T409, 304H, T410 on the outer surface and the tube (100) welded to the outer surface at the same time to rotate the rough processing In the HRSG fin tube manufacturing method for manufacturing a fin tube for waste heat recovery boiler by the high-frequency welding while winding the strip-shaped fin 200 comprising a plurality of segments 220 extending from 210;
The tube 100 is limited to an outer diameter of 26.9 ~ 76mm,
Segment height (SH) of the pin 200 is maintained at 8 ~ 25.4mm,
The thickness T of the pin 200 is limited to 0.8 ~ 1.5mm,
Segment width (SW) stays between 3.8 and 4.4 mm,
The height RH excluding the segment height SH from the pin 200 is maintained at 5 to 7 mm,
The spacing D between the pins 200 is maintained at 2.5 to 6.6 inches,
Welding conditions for the welding of the pin 200, the welding speed 100 ~ 300rpm, output 120KW, input current 300A, anode voltage 9 ~ 10KV, anode current 16 ~ 17A, characterized in that the grid current is maintained at 3.0 ~ 3.2A Fin tube manufacturing method using HR347 tube.

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