Long-life fire-resistant cable for mild environment of nuclear power station and manufacturing method of long-life fire-resistant cable

Abstract

The invention belongs to the technical field of cable production and manufacturing, and particularly relates to a long-life fire-resistant cable for a mild environment of a nuclear power station and a manufacturing method of the long-life fire-resistant cable for the mild environment of the nuclear power station. A heterogeneous double-layer co-extrusion insulating layer is extruded behind the wrapping tape, and the wrapping tape is lapped to form a cable core; the heterogeneous double-layer co-extrusion insulating layer comprises an inner insulating layer and an outer insulating layer which are made of different materials; the method comprises the following steps of: wrapping a wrapping tape outside a conductor, extruding an inner insulating layer and an outer insulating layer after wrapping the wrapping tape, and performing irradiation crosslinking treatment on the inner insulating layer and the outer insulating layer to form an insulated cable core, wrapping the insulated cable core, forming a cable core structure by a plurality of insulated cable cores, and filling the obtained cable core structure by adopting a filling body, and wrapping the filling body and the cable core structure with a fireproof outer sheath layer to obtain the long-life fireproof cable for the mild environment of the nuclear power station.

Description

Technical Field

[0001] The invention belongs to the technical field of cable production and manufacturing, and particularly relates to a long-life fire-resistant cable for nuclear power plants and mild environments and a manufacturing method thereof. Background Art

[0002] The statements in this part only provide background technical information related to the present invention and do not necessarily constitute prior art.

[0003] Under the special use environment of nuclear power plants, as the supporting cables of nuclear power plants, they must have the characteristics of strong thermal stability, good chemical stability, excellent radiation resistance, good aging resistance, moisture-proof, corrosion-resistant, halogen-free low-smoke flame retardant, long service life, etc. Cables with special uses require fire-resistant requirements for anti-vibration and spray resistance.

[0004] Therefore, it is necessary to study cables with a long fire-resistant life to meet the use requirements of nuclear power plants. Summary of the Invention

[0005] To solve the above problems, the present invention proposes a long-life fire-resistant cable for nuclear power plants and mild environments and a manufacturing method thereof. Based on the improvement of the cable core structure, a cable with halogen-free low-smoke flame retardant, NS-class fire resistance, low toxicity, corrosion resistance, excellent electrical performance, radiation resistance, and long life is manufactured, effectively meeting the use environment of the long-life fire-resistant cable for nuclear power plants and mild environments.

[0006] According to some embodiments, the first solution of the present invention provides a long-life fire-resistant cable for nuclear power plants and mild environments, and adopts the following technical solutions:

[0007] A long-life fire-resistant cable for nuclear power plants and mild environments adopts a cable core structure. The cable core structure includes at least one conductor. A heterogeneous tape is wound around the outer wall of the conductor. After the tape, a heterogeneous double-layer co-extruded insulating layer is extruded and a tape is wound to form a cable core. The heterogeneous double-layer co-extruded insulating layer includes an inner insulating layer and an outer insulating layer with different materials.

[0008] As a further technical limitation, a filler is arranged outside the cable core, and the filler and the cable core structure are wrapped with an outer sheath layer.

[0009] Furthermore, the filler adopts a halogen-free flame retardant elastic filler.

[0010] Furthermore, the outer sheath layer adopts a fire-resistant material, including a fire-resistant ceramized mica tape, a halogen-free low-smoke flame retardant tape, and an outer sheath arranged in sequence from the inside to the outside.

[0011] As a further technical limitation, the conductor is made of stranded tinned copper wires.

[0012] As a further technical limitation, the heterogeneous tape is formed by overlapping winding of a ceramized mica tape and a polyester tape.

[0013] As a further technical limitation, the double-layer co-extruded heterogeneous insulating layer is formed by superimposing an irradiated cross-linked polyethylene inner insulating layer and an irradiated cross-linked halogen-free low-smoke flame-retardant polyolefin outer insulating layer.

[0014] According to some embodiments, the second solution of the present invention provides a manufacturing method for a long-life fire-resistant cable for a nuclear power plant and a mitigation environment, adopting the following technical solutions:

[0015] A manufacturing method for a long-life fire-resistant cable for a nuclear power plant and a mitigation environment, which is used to manufacture the long-life fire-resistant cable for a nuclear power plant and a mitigation environment described in the first solution. Tape winding is carried out outside the conductor. After tape winding, the inner insulating layer and the outer insulating layer are extruded. The inner insulating layer and the outer insulating layer are irradiated and cross-linked to form an insulated cable core. The insulated cable core is wound. Multiple insulated cable cores form a cable core structure. A filler is used to fill the obtained cable core structure. A fire-resistant outer sheath layer is wrapped outside the filler and the cable core structure to obtain a long-life fire-resistant cable for a nuclear power plant and a mitigation environment.

[0016] As a further technical limitation, a double-threaded screw is used for the extrusion of the inner insulating layer, and a low-compression-ratio screw is used for the extrusion of the outer insulating layer. Before the extrusion of the insulating layer, the conductor is preheated to 90-100 °C, and the insulating material is baked at 60 ± 10 °C for 1-2 hours; the cable core is cooled in a segmented manner. The temperature of the cooling water in the first stage is set at 60 °C ± 10 °C, and the temperature of the cooling water in the second stage is normal temperature; the outer sheath layer is extruded on an extrusion machine using a semi-extrusion die with a low-compression-ratio screw. It is preheated at 60 ± 10 °C for 1-2 hours before extrusion, and is cooled in a segmented manner after extrusion. The temperature of the cooling water in the first stage is 60 ± 10 °C, and the temperature of the cooling water in the second stage is normal temperature.

[0017] As a further technical limitation, the conductor is a stranded tinned copper material, and the stranding pitch is 16-22 times the outer diameter of the conductor; the stranding direction of the outermost layer of the conductor is left-handed, and the stranding directions of adjacent layers are opposite.

[0018] Compared with the prior art, the beneficial effects of the present invention are:

[0019] The structure of the present invention is compact and has good stability. The sheath layer is made of halogen-free low-smoke and radiation-resistant cross-linked polyolefin, with excellent radiation resistance and mechanical properties; the outer wall of the conductor adopts double-layer insulation inside and outside, which improves the insulation performance of the cable, ensures reliable electrical performance, and makes the use process more stable; the conductor is stranded and has good electrical conductivity; the irradiated cross-linked polyethylene inner insulation layer is resistant to high temperature and aging, is halogen-free and low-smoke and environmentally friendly, protects the wire core from damage and extends the service life of the power cable. The irradiated cross-linked halogen-free low-smoke polyolefin outer insulation layer has excellent mechanical properties and radiation resistance; halogen-free flame-retardant elastic filler is used to improve the flame-retardant performance of the cable; irradiated cross-linked halogen-free low-smoke polyolefin sheath material is used, and the material forms a thermosetting material after irradiation cross-linking, ensuring the service life of the power cable and the radiation resistance to γ-rays; the inner and outer insulation layers are processed by a double-layer co-extrusion process, with high efficiency and low energy consumption, avoiding defects such as delamination, wrinkling, degumming between the sheath layer and the insulation layer, and loose binding between the wire core and the insulation; wrapping 2 layers of ceramized mica tape and 1 layer of polyester tape outside the tinned copper conductor ensures both the fire resistance of the cable and the smoothness of the cable after wrapping the ceramized mica tape; the cable stranding uses an extruded tube-shaped filler strip for filling and ceramized mica tape and non-hygroscopic halogen-free low-smoke flame-retardant tape for wrapping, ensuring the anti-vibration, spray-resistant fire resistance and flame-retardant performance of the cable.

[0020] In the production steps of the present invention, the inner insulation layer, the outer insulation layer and the sheath layer adopt irradiated cross-linked halogen-free low-smoke. During the irradiation cross-linking process, the insulation does not come into contact with moisture, thereby reducing the probability of electrical performance problems caused by the incorporation of moisture into the cable; Irradiation cross-linking is particularly suitable for the production of special cables. By using high-energy electron beams to modify the insulating material, the high-energy rays break the original linear C-H bonds, and then the molecular structure is reorganized to form an irregular network molecular structure, improving the mechanical and physical properties and heat resistance of the material, and the electrical performance is also improved to a certain extent; At the same time, since this material is irradiated with high-energy electron rays on organic thermoplastic materials to transform them from linear macromolecules into three-dimensional cross-linked network structures; that is, from thermoplastics to insoluble and infusible thermosolid substances, improving and enhancing the physical and mechanical properties, and the irradiation cross-linking method can avoid destroying the low-smoke and halogen-free characteristics by chemical cross-linking. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The schematic diagram of the accompanying drawings forming a part of this embodiment is used to provide a further understanding of this embodiment. The schematic embodiments and descriptions of this embodiment are used to explain this embodiment and do not constitute an improper limitation of this embodiment.

[0022] Figure 1 It is a schematic structural diagram of a long-life fire-resistant cable for nuclear power plants and gentle environments in Embodiment 1 of the present invention;

[0023] Among them, 1. Conductor; 2. Ceramicized mica tape; 3. Polyester tape; 4. Inner insulation layer; 5. Outer insulation layer; 6. Wrapping tape; 7. Filling; 8. Fire-resistant ceramicized mica tape; 9. Halogen-free low-smoke flame-retardant wrapping tape; 10. Outer sheath. Specific embodiments

[0024] The present invention will be further described below in conjunction with the drawings and embodiments.

[0025] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which this application belongs.

[0026] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] In the present invention, terms such as "upper", "lower", "left", "right", "front", "rear", "vertical", "horizontal", "side", "bottom", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only relationship terms determined for the convenience of describing the structural relationship of each component or element of the present invention and do not specifically refer to any component or element of the present invention and should not be construed as a limitation of the present invention.

[0028] In the present invention, terms such as "fixed connection", "connected", "connected" should be understood in a broad sense, which may mean a fixed connection, an integral connection or a detachable connection; it may be directly connected or indirectly connected through an intermediate medium. For those related scientific research or technical personnel in the field, the specific meanings of the above terms in the present invention can be determined according to specific circumstances and should not be construed as a limitation of the present invention.

[0029] Without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other.

[0030] Embodiment 1

[0031] Embodiment 1 of the present invention introduces a long-life fire-resistant cable for nuclear power plants and mild environments.

[0032] Such as Figure 1A long - life fire - resistant cable for nuclear power plants and mild environments is shown as follows. It includes two conductors 1. The outer wall of the conductor 1 is wrapped with ceramized mica tape 2 and polyester tape 3. The conductor tape is extruded with a heterogeneous double - layer co - extruded insulation layer. There is a tape 6 outside the heterogeneous double - layer co - extruded insulation layer to form an insulated core. Two insulated cores are filled with 7, fire - resistant ceramized mica tape 8 and halogen - free low - smoke flame - retardant tape 9, and an outer sheath 10. The heterogeneous double - layer co - extruded insulation layer includes an inner insulation layer 2 and an outer insulation layer 3, and the materials of the inner insulation layer 4 and the outer insulation layer 5 are different. The material of the inner insulation layer 4 is cross - linked polyethylene material, and the material of the outer insulation layer 5 is cross - linked halogen - free low - smoke flame - retardant polyolefin material. The tape layer 6 is polyester tape, and the material of the outer sheath layer 10 is halogen - free low - smoke flame - retardant polyolefin.

[0033] The structure of this embodiment is compact and has good stability. The sheath layer uses halogen - free low - smoke and radiation - resistant cross - linked polyolefin, with excellent radiation - resistant performance and mechanical properties. The outer wall of the conductor uses double - layer insulation inside and outside, improving the insulation of the cable, ensuring reliable electrical performance, and being more stable during use. The conductor is stranded, with good electrical conductivity. The irradiated cross - linked polyethylene inner insulation layer is resistant to high temperature and aging, halogen - free low - smoke and environmentally friendly, protecting the core from damage and extending the service life of the power cable. The irradiated cross - linked halogen - free low - smoke polyolefin outer insulation layer has excellent mechanical properties and radiation - resistant performance. Using halogen - free flame - retardant elastic filler improves the flame - retardant performance of the cable. Using irradiated cross - linked halogen - free low - smoke polyolefin sheath material, the material forms a thermosetting material after irradiation cross - linking, ensuring the service life of the power cable and the radiation - resistant performance against γ - rays. The inner and outer insulation layers are processed by double - layer co - extrusion technology, with high efficiency and low energy consumption, avoiding defects such as delamination, wrinkling, degumming between the sheath layer and the insulation layer, and loose bonding between the core and the insulation. Wrapping 2 layers of ceramized mica tape and 1 layer of polyester tape outside the tinned copper conductor ensures both the fire - resistant performance of the cable and the smoothness of the cable after wrapping the ceramized mica tape. The cable stranding uses an extruded tube - type filler strip for filling and ceramized mica tape and non - hygroscopic halogen - free low - smoke flame - retardant tape for wrapping, ensuring the anti - vibration and spray - resistant fire - resistant performance and flame - retardant performance of the cable.

[0034] Embodiment Two

[0035] Embodiment Two of the present invention introduces a manufacturing method of the long - life fire - resistant cable for nuclear power plants and mild environments introduced in Embodiment One.

[0036] A manufacturing method of a long - life fire - resistant cable for nuclear power plants and mild environments includes the following steps: conductor material selection - conductor wrapping - extrusion of inner and outer insulation layers - irradiation cross - linking treatment of inner and outer insulation layers - wrapping - stranding - filling - stranding wrapping - extrusion of outer sheath layer - irradiation cross - linking treatment of outer sheath layer.

[0037] This embodiment makes a detailed description for each step:

[0038] (1) Conductor material selection

[0039] The conductor is made of stranded tinned copper material, in regular stranded round shape, with a stranding pitch of 16 to 22 times the outer diameter of the conductor. The stranding direction of the outermost layer is left-handed, and the stranding directions of adjacent layers are opposite.

[0040] (2) Conductor lapping

[0041] Overlap and lap 2 layers of ceramized mica tape and 1 layer of polyester tape outside the tinned copper conductor, with a lapping rate of not less than 15%.

[0042] (3) Extrusion of inner insulation layer and outer insulation layer

[0043] The inner insulation layer and the outer insulation layer are co-extruded in a double layer; the inner insulation uses irradiated cross-linked polyethylene insulating material, and the outer insulation uses irradiated cross-linked halogen-free low-smoke flame-retardant polyolefin insulating material. The thickness ratio of the inner insulation layer to the outer insulation layer is 30% - 70%. The inner insulation is extruded using an ordinary double-threaded screw, and the outer insulation is extruded using a low-compression ratio screw. Before the extrusion of the insulation layer, the conductor should be preheated to 90 - 100 °C, and the insulating material should be baked at 60 ± 10 °C for 1 - 2 hours. The wire core is cooled in a segmented manner. The temperature of the cooling water in the first stage is 60 °C ± 10 °C, and the temperature of the cooling water in the second stage is normal temperature. Refer to the temperature shown in Table 1 during extrusion, and the temperature can be adjusted according to the actual situation.

[0044] Table 1 Extrusion reference temperature

[0045]

[0046] (4) Irradiation cross-linking treatment of inner insulation layer and outer insulation layer

[0047] The inner insulation layer and the outer insulation layer are irradiated and cross-linked, and the elongation at break under load is not greater than 100%.

[0048] (5) Tape wrapping

[0049] The tape wrapping uses 1 layer of polyester tape to overlap and wrap, and the lapping rate is controlled at 15% - 20%.

[0050] (6) Cable laying

[0051] The laying direction of the outermost layer during cable laying is right-handed, and the laying directions of adjacent layers are opposite. In this embodiment, the maximum laying pitch is 25 times. Use a halogen-free flame-retardant elastic filler strip for filling. The cable laying tape uses 4 layers of ceramized mica tape and 1 layer of non-hygroscopic halogen-free low-smoke flame-retardant tape to overlap and wrap, and the lapping rate is controlled at 15% - 20%.

[0052] (7) Extrusion of filler strip

[0053] The filler extruded strip is extruded by a low compression ratio screw extrusion die. The screw compression ratio is 1.25 - 1.5. The material should be preheated at 60 ± 10°C for 1 - 2 hours before extrusion, and after extrusion, it is cooled in a segmented manner. The temperature of the cooling water in the first stage is 60 ± 10°C, and the temperature of the cooling water in the second stage is at room temperature. The reference temperature during extrusion is shown in Table 2, and the temperature can be adjusted according to the actual situation.

[0054] Table 2 Reference Temperature for Filler Extruded Strip

[0055]

[0056] (8) Extrusion of the outer sheath layer

[0057] The outer sheath layer is extruded by a low compression ratio screw on an extrusion machine with a semi-extrusion die. The material should be preheated at 60 ± 10°C for 1 - 2 hours before extrusion, and after extrusion, it is cooled in a segmented manner. The temperature of the cooling water in the first stage is 60 ± 10°C, and the temperature of the cooling water in the second stage is at room temperature. The reference temperature during extrusion is shown in Table 3, and the temperature can be adjusted according to the actual situation.

[0058] Table 3 Reference Temperature for Extrusion of the Outer Sheath Layer

[0059]

[0060] (9) Radiation cross-linking treatment of the outer sheath layer

[0061] The sheath layer is irradiated and cross-linked, and the elongation at break under load is not greater than 100%.

[0062] In this embodiment, the performance of the cable tested is as follows: The mechanical properties of the insulation before and after cable aging are good. The minimum tensile strength before aging reaches 10.0 N / mm 2 , and the minimum elongation at break reaches 200%. The change rates of the tensile strength and elongation at break after aging do not exceed ±25%. The maximum elongation at break under load in the insulation thermal elongation test does not exceed 175%, and the maximum permanent deformation elongation after cooling is 15%.

[0063] The sheath performance meets the requirements that the minimum tensile strength before aging reaches 9.0 N / mm 2 , and the minimum elongation at break reaches 150%. The change rates of the tensile strength and elongation at break after aging do not exceed ±40%. The maximum elongation at break under load in the thermal elongation test does not exceed 175%, and the maximum permanent deformation elongation after cooling is 15%.

[0064] The cable passes the accelerated thermal aging test equivalent to 60 years of operation through the thermal aging simulation test, and the mechanical properties of the insulation and sheath meet the requirements.

[0065] NS fire resistance test (test time 120 min, applying mechanical impact, and adding water spray or jet according to the requirements of GB / T 19666 - 2019).

[0066] In this embodiment, the inner insulation layer, the outer insulation layer and the sheath layer are made of irradiated cross-linked halogen-free low-smoke materials. During the irradiation cross-linking process, the insulation does not come into contact with moisture, thereby reducing the probability of electrical performance problems caused by the incorporation of moisture into the cable. Irradiation cross-linking is particularly suitable for the production of special cables. By using high-energy electron beams to modify the insulating material, the high-energy rays break the original linear C-H bonds, and then the molecular structure is reorganized to form an irregular network molecular structure, improving the mechanical and physical properties and heat resistance of the material, and also improving the electrical performance to a certain extent. At the same time, since this material is irradiated with high-energy electron rays on organic thermoplastic materials to transform them from linear polymers into three-dimensional cross-linked network structures, that is, from thermoplastics to insoluble and infusible thermosolid substances, the physical and mechanical properties are improved, and the irradiation cross-linking method can avoid damaging the low-smoke and halogen-free characteristics by chemical cross-linking.

[0067] The above are only the preferred embodiments of this embodiment and are not used to limit this embodiment. For those skilled in the art, this embodiment can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of this embodiment shall be included within the protection scope of this embodiment.

Claims

1. A long-life fire-resistant cable for a nuclear power plant's mitigation environment, characterized in that, Adopt a cable core structure, the cable core structure includes at least one conductor, a heterogeneous tape is wound around the outer wall of the conductor, and a heterogeneous double-layer co-extruded insulation layer is extruded after the tape and a tape is wound to form a cable core; the heterogeneous double-layer co-extruded insulation layer includes an inner insulation layer and an outer insulation layer with different materials.

2. A long-life fire-resistant cable for a nuclear power plant and gentle environment as described in claim 1, characterized in that, A filler is arranged outside the cable core, and the filler and the cable core structure are wrapped with an outer sheath layer.

3. A long-life fire-resistant cable for a nuclear power plant and a gentle environment, as described in claim 2, characterized in that, The filler adopts a halogen-free flame-retardant elastic filler.

4. A long-life fire-resistant cable for a nuclear power plant and gentle environment as described in claim 2, characterized in that, The outer sheath layer adopts a fire-resistant material, including a fire-resistant ceramized mica tape, a halogen-free low-smoke flame-retardant tape and an outer sheath arranged in sequence from inside to outside.

5. A long-life fire-resistant cable for a nuclear power plant and gentle environment as described in claim 1, characterized in that, The conductor is made of stranded tinned copper wires.

6. A long-life fire-resistant cable for a nuclear power plant's gentle environment as described in claim 1, characterized in that, The heterogeneous tape is wound by overlapping a ceramized mica tape and a polyester tape.

7. A long-life fire-resistant cable for a nuclear power plant and a gentle environment as described in claim 1, characterized in that The double-layer co-extruded heterogeneous insulation layer is formed by superimposing an irradiated cross-linked polyethylene inner insulation layer and an irradiated cross-linked halogen-free low-smoke flame-retardant polyolefin outer insulation layer.

8. A manufacturing method of a long-life fire-resistant cable for a nuclear power plant and a mitigation environment, which is used to manufacture the long-life fire-resistant cable for a nuclear power plant and a mitigation environment as described in any one of claims 1-7, characterized in that, Wrap a tape around the conductor, extrude the inner insulation layer and the outer insulation layer after the tape, perform irradiation cross-linking treatment on the inner insulation layer and the outer insulation layer to form an insulated cable core, wind the insulated cable core, multiple insulated cable cores form a cable core structure, use a filler to fill the obtained cable core structure, and wrap a fire-resistant outer sheath layer outside the filler and the cable core structure to obtain a long-life fire-resistant cable for nuclear power plants and mild environments.

9. The manufacturing method of a long-life fire-resistant cable for a nuclear power plant and a gentle environment as claimed in claim 8, wherein The inner insulation layer is extruded using a double-threaded screw, and the outer insulation layer is extruded using a low-compression-ratio screw. Before the insulation layer is extruded, the conductor is preheated to 90 - 100 °C, and the insulation material is baked at 60 ± 10 °C for 1 - 2 hours; the cable core is cooled in a segmented manner, the temperature of the first-stage cooling water is set to 60 °C ± 10 °C, and the temperature of the second-stage cooling water is normal temperature; the outer sheath layer is extruded using a low-compression-ratio screw on an extrusion machine with a semi-extrusion die, preheated at 60 ± 10 °C for 1 - 2 hours before extrusion, and cooled in a segmented manner after extrusion, the temperature of the first-stage cooling water is 60 ± 10 °C, and the temperature of the second-stage cooling water is normal temperature.

10. The manufacturing method of a long-life fire-resistant cable for a nuclear power plant and a gentle environment as claimed in claim 8, characterized in that, The conductor is a stranded tinned copper material, and the stranding pitch is 16 - 22 times the outer diameter of the conductor; the stranding direction of the outermost layer of the conductor is left-handed, and the stranding directions of adjacent layers are opposite.

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