A triangular prism groove heater device and preheating method

Abstract

The present invention relates to a triangular prism groove heater device and a preheating method, which belongs to the technical field of preheating electric heating before welding of thick-walled welds. The device of the present invention comprises a heater and a wire ring net, wherein the heater is fixed on the easily deformable wire ring net, and the heater comprises a high-temperature resistant ceramic string, a resistance wire, a crimping joint, a conductive copper wire and a quick connector, wherein the resistance wire is crimped and connected with the conductive copper wire equipped with a quick connector through the crimping joint, and the high-temperature resistant ceramic string is a ceramic part of the ceramic electric heater. The present invention has a simple and reasonable structural design, is safe and reliable, reduces the time required for preheating, saves production and construction costs, has strong versatility, and has a high thermal utilization rate, and realizes targeted electric heating preheating of the groove of the butt weld.

Description

Technical Field

[0001] The invention relates to a device and a preheating method, in particular to a triangular prism groove heater device and a preheating method, which belongs to the technical field of preheating electric heating before thick-walled welds, and is used to solve the problem of difficulty in preheating the groove root temperature during on-site bottom welding of thick-walled pipe welds, and provides a new device and method for preheating P91 / P92 on-site welds such as high-temperature headers and four large pipelines for ultra-supercritical units with a temperature of 630°C or above before welding. Background Art

[0002] In recent years, with the increase in the capacity of thermal power units, the wall thickness of the high-temperature headers and four major pipelines on the thermal power units has gradually increased. Effective electric preheating of such pipelines before welding can reduce the residual stress of welding, prevent the occurrence of welding defects, and improve the structure and performance of the weld.

[0003] For preheating of pressure pipes before welding, electric heaters are usually arranged on the outer surfaces of both sides of the pipe groove. However, using only this heating method consumes a lot of energy, and the heater efficiency at the root of the groove is low. For example, the main steam pipe (parameters are P92 / ID292×108mm) weld needs to be preheated before welding. The conventional method is to use a crawler heater to electrically preheat the outer walls of the welding groove on both sides. If the process temperature of the root of the welding groove is 150℃, the temperature of the outer wall of the pipe needs to reach 400℃ to conduct the heat required by the root, which will make it impossible for welders to weld close, affecting the welding quality of the weld. Alternatively, flame preheating is used to preheat the root. This heating method has low heating efficiency at the root of the groove, uneven heating area, long heating time, high labor intensity for workers, and wastes energy.

[0004] The Chinese patent with publication date of September 28, 2016 and publication number of CN104923995B discloses an invention patent entitled "a device for preheating the groove of a straight seam submerged arc welded pipe". The patent includes a gantry frame, a lifting mechanism, a suspension device, a heating device and a rotating roller device. The lifting mechanism is provided on the crossbeam of the gantry frame, and the lifting mechanism includes multiple sets of synchronously operated worm gear elevators. The suspension device is provided with a long beam along the longitudinal direction of the gantry frame. The upper part of the long beam is connected to the lifting screw in the worm gear elevator and can be lifted and lowered accordingly. The ceramic heater in the heating device is longitudinally arranged below the long beam of the suspension device; and multiple rotating roller devices are provided on the ground below the gantry frame. Although the patent can preheat the groove of the straight seam submerged arc welded pipe online and is easy to adjust, it still cannot solve the problem of difficulty in preheating the root of the groove when the base welding of the thick-walled pipe weld is performed on site, so it still has the above-mentioned defects.

[0005] A Chinese patent with a publication date of May 14, 2014 and a publication number of CN102994723B discloses an invention patent entitled "A New Type of Fan-Shaped Heater". The patent includes a furnace body formed by two fan-shaped furnace shells connected to each other, with openings on the upper and lower sides of the furnace body, and a header pipe is arranged in the opening. A mounting plate is arranged in each of the two fan-shaped furnace shells, and the mounting plate is connected to a ceramic electric heater. Although the patent can achieve targeted heat treatment of the header short pipe joint and the loose pipe butt weld, it is energy-saving and flexible in operation, but the heating method consumes a lot of energy, the heater at the root of the groove is inefficient and costly, so it still has the above-mentioned defects.

[0006] Therefore, it is particularly necessary to provide a triangular prism groove heater device that can electrically preheat the groove root of the weld, reduce the time required for preheating, and save production and construction costs. Summary of the invention

[0007] The purpose of the present invention is to overcome the above-mentioned shortcomings in the prior art and to provide a triangular prism groove heater device and preheating method which has a simple and reasonable structural design, is safe and reliable, can electrically preheat the root of the weld groove, reduces the time required for preheating, saves production and construction costs, has strong versatility, and has high thermal utilization.

[0008] The technical solution adopted by the present invention to solve the above-mentioned problem is: the triangular prism groove heater device includes a heater and a wire ring net, and is characterized in that: the heater is fixed on the wire ring net that is easy to deform, and the heater includes a high-temperature resistant ceramic string, a resistance wire, a crimping joint, a conductive copper wire and a quick connector. The resistance wire is crimped and connected with the conductive copper wire equipped with a quick connector through the crimping joint, and the high-temperature resistant ceramic string is the ceramic part of the heater.

[0009] Preferably, the present invention further comprises a heat insulating layer, wherein an aluminum silicate fiber needle-punched blanket is laid inside the heat insulating layer.

[0010] Preferably, the present invention further comprises an armored thermocouple for temperature control and temperature measurement, wherein the armored thermocouple is arranged at the root of the groove.

[0011] Preferably, the heater of the present invention is a ceramic electric heater, and the high temperature resistant ceramic string of the ceramic electric heater is a 96% Al2O3 ceramic string.

[0012] Preferably, the wire ring net of the present invention adopts flexible high temperature resistant wire rings, and the flexible wire ring net is made of iron wire with a wire diameter of 2 mm and a circular ring with a diameter of 10 mm.

[0013] Preferably, the crimping joint of the present invention is a stainless steel crimping joint.

[0014] Preferably, the resistance wire of the present invention is Cr20Ni80 resistance wire.

[0015] Preferably, the heater of the present invention includes heater 2 and heater 1, heater 2 has a column length of 918 mm, a bottom surface is an isosceles triangle, a waist length of 80 mm, and a power of 7.5 kW; heater 1 has a column length of 612 mm, a bottom surface is an isosceles triangle, a waist length of 80 mm, and a power of 5 kW.

[0016] The present invention also provides a preheating method for a triangular prism groove heater device, comprising the following steps: (1) installing the heater, arranging an armored thermocouple, and laying a heat insulation layer; (2) connecting the heater to a heat treatment device, setting preheating parameters, and starting the heat treatment device; (3) when the preheating temperature reaches the process parameters, removing the triangular prism groove heater and performing welding.

[0017] Compared with the prior art, the present invention has the following advantages and effects: (1) The overall structural design is simple and reasonable, safe and reliable, and can electrically preheat the root of the weld groove, reducing the time required for preheating and avoiding the use of flame preheating. The preheating temperature record can be automatically generated without the need for manual recording, thus saving production costs; (2) The heating device can completely fit and cover the weld groove and the steel pipe preheating area, and adopts a triangular prism groove heater, which has a fast heating speed, high thermal utilization rate, significant energy saving, and is safe and reliable to use; (3) The operation and adjustment are convenient, the versatility is strong, and it can adapt to the preheating of welds of different pipe diameters, greatly saving construction costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of the structure of a triangular prism groove heater according to an embodiment of the present invention.

[0019] Figure 2 The cross section of the arrangement of the welding groove heater in Example 1 of the present invention Figure 1 .

[0020] Figure 3 The cross section of the arrangement of the welding groove heater in Example 1 of the present invention Figure 2 .

[0021] Figure 4 The cross section of the arrangement of the welding groove heater in Example 2 of the present invention Figure 1 .

[0022] Figure 5 The cross section of the arrangement of the welding groove heater in Example 2 of the present invention Figure 2 .

[0023] In the figure: heater 1, iron wire ring network 2, thermal insulation layer 3, armored thermocouple 4; high temperature resistant ceramic string 11, resistance wire 12, crimping connector 13, conductive copper wire 14, quick connector 15; heater one 1-1, heater two 1-2. DETAILED DESCRIPTION

[0024] The present invention will be further described in detail below with reference to the accompanying drawings and by way of examples. The following examples are intended to explain the present invention but the present invention is not limited to the following examples.

[0025] See also Figures 1 to 5 The triangular prism groove heater device of this embodiment mainly includes a heater 1, a wire ring mesh 2 and a heat insulation layer 3. The heater 1 is fixed on the easily deformable wire ring mesh 2 and can be close to the inner wall of the weld groove.

[0026] The heater 1 of this embodiment includes a high-temperature resistant ceramic string 11, a resistance wire 12, a crimping joint 13, a conductive copper wire 14 and a quick connector 15. The resistance wire 12 is crimped and connected to the conductive copper wire 14 equipped with the quick connector 15 through the crimping joint 13. The high-temperature resistant ceramic string 11 is a ceramic component of the ceramic electric heater.

[0027] In this embodiment, an aluminum silicate fiber needle-punched blanket is laid inside the thermal insulation layer 3; its size can be adjusted according to the size of the groove, and it has excellent thermal insulation performance, and can withstand temperatures up to 1000°C. The fibers are naturally compressed, very sealed and firm, and its thickness is about 40mm. It is light in weight, has high thermal efficiency, is easy to install, and has a long service life.

[0028] The heater 1 of this embodiment is a ceramic electric heater, and the high temperature resistant ceramic string 11 of the ceramic electric heater is a 96% Al2O3 ceramic string 1; it has the characteristics of high temperature resistance, high strength, high wear resistance, good insulation performance, and no brittle cracking. The ceramic body has excellent penetration performance and the high resistance electric heating alloy multi-strand Cr20Ni80 resistance wire 12 is formed into a wire cable. It has good oxidation resistance, high temperature resistance, and high load. With reasonable component structure parameter design, it can ensure a very high service life and the temperature resistance can reach 1000℃. The Cr20Ni80 resistance wire 12 is crimped and connected to the conductive copper wire 14 equipped with a quick connector 15 through a crimping joint 13, and is connected to the heat treatment equipment through the quick connector 15 that can match the heat treatment conductive copper wire 14. The heater is mainly used to heat the lower half of the inner wall of the groove on both sides.

[0029] The wire ring net 2 of this embodiment adopts flexible high temperature resistant wire rings, and the wire ring net 2 is made of iron wire with a wire diameter of 2 mm and a circular ring with a diameter of 10 mm.

[0030] In this embodiment, the armored thermocouple 4 is used for temperature control and temperature measurement, and the armored thermocouple 4 is arranged at the root of the groove.

[0031] In this embodiment, the crimping connector 13 is made of stainless steel; the resistance wire 12 is made of Cr20Ni80 resistance wire.

[0032] The heater 1 of this embodiment includes a heater 1-2 and a heater 1-1. One is a heater 1-2 with a column length of 918 mm, an isosceles triangle bottom, a waist length of 80 mm, and a power of 7.5 kW; the other is a heater 1-1 with a column length of 612 mm, an isosceles triangle bottom, a waist length of 80 mm, and a power of 5 kW. The heaters 1 can be used alone or in combination to complete the preheating of the weld groove of thick-walled pipes with a wall thickness greater than 80 mm (such as the main steam pipe parameters are P92 / ID292×108 mm and the primary reheat pipe parameters are P92 / ID559×84 mm) that need to be preheated before welding.

[0033] The preheating method of the triangular prism groove heater device of this embodiment comprises the following steps: (1) installing the heater 1, arranging the thermocouple, and laying the thermal insulation layer 3; (2) connecting the heater 1 to the heat treatment equipment, setting the preheating parameters and starting the heat treatment equipment; (3) after the preheating temperature reaches the process parameters, removing the triangular prism groove heater and performing welding.

[0034] Example 1.

[0035] like Figure 2-Figure 3 As shown, this embodiment is a cross-sectional schematic diagram of a welding groove heater arrangement constructed by taking the main steam pipeline weld (parameters are P92 / ID 292×108mm) as an example.

[0036] When preheating the groove of the main steam pipe weld (parameters are P92 / 292×108mm), the heater 1 is arranged on the inner wall of the groove. Since the inner diameter of the weld is d1=292mm, the calculated inner diameter circumference is l1=3.14×292mm=917mm, so a 7.5kW heater 1-2 with a column length of L1=918mm is used for groove heating. Since the column length of the 7.5kW heater 1-2 is basically matched with the inner diameter of the pipe groove, only one set of heaters can be used.

[0037] After the heater 1 is arranged, an armored thermocouple 4 is arranged at the root of the groove for temperature control and temperature measurement, and aluminum silicate needle felt is laid inside the thermal insulation layer 3 for thermal insulation.

[0038] Then, the heater 1 is connected to the heat treatment equipment, the preheating parameters are set and the heat treatment equipment is started; after the preheating temperature reaches the process parameter T=150°C, the triangular prism groove heater is removed and argon arc welding is performed for base welding.

[0039] Example 2.

[0040] like Figure 4 — Figure 5 As shown, this embodiment is a cross-sectional schematic diagram of a welding groove heater arrangement constructed by taking the main steam pipeline weld (parameters are P92 / ID559×84mm) as an example.

[0041] When preheating the groove of the primary reheat steam pipe weld (parameters are P92 / ID559×84mm), the heater is arranged on the inner wall of the groove. Since the inner diameter of the weld is d2=559mm, the calculated inner diameter circumference is l2=3.14×559mm=1755mm. Therefore, a combination of a 7.5kW heater 1-2 with a column length of L1=900mm and a 5kW heater 1-1 with a column length of L2=612mm is used to heat the groove. Since the temperature has the property of diffusing upward, the junction of heater 1-1 and heater 2 1-2 is set at the upper half circle.

[0042] After the heater is arranged, an armored thermocouple 4 is arranged at the root of the groove for temperature control and temperature measurement, and aluminum silicate needle felt is laid inside the thermal insulation layer 3 for thermal insulation.

[0043] Then connect the heater to the heat treatment equipment, set the preheating parameters and start the heat treatment equipment; after the preheating temperature reaches the process parameter T=150°C, remove the triangular prism groove heater and perform argon arc welding for base welding.

[0044] Through the above description, those skilled in the art can already implement it.

[0045] In addition, it should be noted that the shapes and names of the parts and components of the specific embodiments described in this specification may be different, and the above content described in this specification is only an example of the structure of the present invention. All equivalent changes or simple changes made based on the structure, features and principles described in the patent concept of the present invention are included in the protection scope of the patent of the present invention. Technicians in the technical field of the present invention can make various modifications or supplements to the specific embodiments described or replace them in a similar manner, as long as they do not deviate from the structure of the present invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

Claims

1. A triangular prism groove heater device, comprising a heater, a wire ring mesh, a heat insulation layer and an armored thermocouple for temperature control and temperature measurement, characterized in that: The heater is fixed on an easily deformable iron wire ring net. The heater includes a high-temperature resistant ceramic string, a resistance wire, a crimping joint, a conductive copper wire and a quick joint. The resistance wire is crimped and connected to the conductive copper wire equipped with a quick joint through the crimping joint. The high-temperature resistant ceramic string is a ceramic component of the heater. An aluminum silicate fiber needle-punched blanket is laid inside the thermal insulation layer, and an armored thermocouple is arranged at the root of the groove. The heater includes a heater 2 and a heater 1. The heater 2 has a column length of 918 mm, a bottom surface of an isosceles triangle, a waist length of 80 mm, and a power of 7.5 kW. The heater 1 has a column length of 612 mm, a bottom surface of an isosceles triangle, a waist length of 80 mm, and a power of 5 kW.

2. The triangular prism groove heater device according to claim 1, characterized in that: The heater is a ceramic electric heater, and the high temperature resistant ceramic string of the ceramic electric heater is a 96% Al2O3 ceramic string.

3. The triangular prism groove heater device according to claim 1, characterized in that: The wire ring net is made of flexible high temperature resistant wire rings, which are made of iron wires with a wire diameter of 2 mm and made into circular rings with a diameter of 10 mm.

4. The triangular prism groove heater device according to claim 1, characterized in that: The crimping joint is a stainless steel crimping joint.

5. The triangular prism groove heater device according to claim 1, characterized in that: The resistance wire is Cr20Ni80 resistance wire.

6. A preheating method for a triangular prism groove heater device, using the triangular prism groove heater device according to any one of claims 1 to 5, characterized in that: Here are the steps: (1) Install heaters, arrange armored thermocouples, and lay thermal insulation layers; (2) Connect the heater to the heat treatment equipment, set the preheating parameters and start the heat treatment equipment; (3) When the preheating temperature reaches the process parameters, remove the triangular prism groove heater and proceed with welding.

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