Method and device for rapidly degassing insulated wire core of large-length submarine cable

Abstract

Disclosed in the present invention are a method and device for rapidly degassing an insulated wire core of a large-length submarine cable. The method comprises: S1, placing an insulated wire core of a required length in a degassing room, sealing one end of the insulated wire core and connecting same to a gas guide pipe; S2, connecting both ends of the insulated wire core to a direct-current power supply; S3, determining the number of meters of the insulated wire core to be degassed, measuring the initial direct-current resistance of a conductor of the insulated wire core, measuring the direct-current resistance of the conductor at 20℃ by means of a direct-current bridge, and calibrating same on the basis of theoretical calculation; S4, inputting the direct-current resistance value of the conductor at a specified temperature into a direct-current power supply control page; S5, raising a current or voltage at the rate of 5-20 A / min or 5-20 V / min, and selecting a current or voltage rising rate on the basis of the length of the wire core to be degassed, the cross section of the conductor, and the heat and heating time required for rising to the specified temperature; S6, when the temperature of the conductor rises to a temperature set for degassing, disconnecting the power supply, and switching to a hot air heating circulation system; and S7, introducing into the degassing room hot air heated to the specified temperature, providing in the degassing room a thermocouple for monitoring the temperature in real time, keeping the temperature that reaches the specified degassing temperature, continuously monitoring the concentration of a degassing byproduct, turning off the hot air heating circulation system when the concentration is reduced to a specified numerical value, naturally cooling the byproduct 48 hours, and performing a subsequent process. The present invention may greatly shorten the time required for insulated wire cores of large-length submarine cables to reach a process-specified degassing temperature, exhibit high production efficiency, reduce investment in degassing apparatuses for the insulated wire cores of the submarine cables, and decrease the production costs of the submarine cables.

Description

Method and device for rapid degassing of large length submarine cable insulation core TECHNICAL FIELD

[0001] The present application relates to the technical field of cables, in particular to a method and device for rapid degassing of large length submarine cable insulation core. BACKGROUND

[0002] Submarine cables are the main equipment for offshore wind power transmission, and the annual demand is increasing with the increase of offshore wind power installed capacity. Currently, the insulation of submarine cables mainly uses cross-linked polyethylene. In the production process of the insulation core, polyethylene needs to undergo cross-linking reaction under the action of peroxide. Some small molecule by-products are produced in the cross-linking reaction process. Part of the cross-linking reaction by-products will be discharged into the cross-linking pipeline under the action of pressure and temperature, but part of the cross-linking by-products will remain in the cooled insulation core. In order to make the submarine cable have good radial water resistance, most of the submarine cable insulation cores are extruded with lead sheath. If there are too many low molecular cross-linking by-products in the large length submarine cable insulation core, the cross-linking by-products will gradually be precipitated in the form of gas under the action of temperature during use, but due to the sealing effect of the lead sheath, too much gas will cause the failure of the cable accessories; in addition, excessive residual cross-linking by-products will cause local electric field distortion of the cable during operation, and thus the cable insulation breakdown is prone to occur, which seriously affects the reliability of the cable operation. Therefore, after the submarine cable insulation core is produced, it needs to be placed in a constant temperature environment of about 70 DEG C for a certain period of time to remove most of the low molecular by-products remaining therein. The common method is to store the submarine cable insulation core in a large length cable storage disc, isolate the cable storage disc from the surrounding environment by using thermal insulation materials, continuously blow circulating hot air into the inside of the cable storage disc from the lower part of the cable storage disc, gradually increase the temperature of the submarine cable insulation core and finally stabilize at the specified process temperature of about 70 DEG C, after a certain period of time, most of the residual low molecular by-products in the submarine cable insulation core are precipitated, and the content reaches the process requirement, and after cooling, the subsequent processing is carried out.

[0003] The prior art has the following defects and disadvantages: when the insulation core of a large length submarine cable is degassed, the following factors exist: (1) the insulation core has many layers and small gaps between adjacent cores, so the hot air flow is not smooth; (2) the heat transfer efficiency of the air heating is not high; (3) the thermal conductivity of the cable insulation and semi-conductive shielding material is poor; (4) the weight of the insulation core of the submarine cable is large, and the heat capacity is large, so a lot of heat needs to be absorbed to completely reach the degassing temperature specified by the process, and thus the constant temperature degassing time of the insulation core of the submarine cable is usually long. The degassing time of the insulation core of a medium voltage submarine cable is at least 15 days, the degassing time of the insulation core of a high voltage submarine cable is at least 25 days, and in special cases, the degassing time may be more than 45 days, which greatly reduces the production efficiency of the submarine cable and greatly increases the investment of the insulation core degassing equipment of the submarine cable production enterprise.

[0004] SUMMARY

[0005] In view of the deficiencies in the prior art, the purpose of the present application is to provide a device for rapid degassing of the insulation core of a large length submarine cable, which greatly shortens the time required to reach the degassing temperature specified by the process, has high production efficiency, reduces the investment of the insulation core degassing equipment of the submarine cable, and reduces the production cost of the submarine cable. In order to achieve the above-mentioned purposes and other advantages according to the present application, a device for rapid degassing of the insulation core of a large length submarine cable is provided, which comprises:

[0006] S1, placing the insulation core of the required length in a degassing room, sealing one end of the insulation core and connecting it with a gas guide pipe;

[0007] S2, connecting the two ends of the insulation core with a direct current power supply;

[0008] S3, determining the number of meters of the degassed insulation core, measuring the initial direct current resistance of the conductor of the insulation core, and calibrating by measuring the direct current resistance of the conductor at 20°C and theoretically calculating;

[0009] S4, inputting the conductor direct current resistance value reaching the specified temperature through the direct current power supply control page;

[0010] S5, increasing the current or voltage at a speed of 5-20 A / min or 5-20 V / min, and selecting the current or voltage increasing speed according to the length of the degassed core, the cross section of the conductor, and the heat and heating time required to reach the specified temperature;

[0011] S6, when the temperature of the conductor rises to the degassing setting temperature, disconnecting the power supply and switching to the hot air heating circulation system;

[0012] S7, the hot air heated to the specified temperature is introduced into the degassing room, a thermocouple is placed in the degassing room to monitor the temperature in real time, until the specified degassing temperature is reached and maintained, the concentration of the degassing byproduct is continuously monitored, when it is reduced to a specified value, the hot air heating circulation system is closed, and natural cooling is performed for 48 hours, and the next step is performed.

[0013] Preferably, the formula for calculating the resistance of the insulated core conductor at the specified temperature in step S3 is as follows: R t = R 20 × [1 + a (t - 20)],

[0014] wherein R 20 is the conductor resistance at 20 DEG C; a is the conductor resistance temperature coefficient, that is, the multiple of the increase of the conductor resistance per 1 DEG C of temperature rise; and R t is the conductor resistance at t DEG C, wherein t is the specified temperature, and the range of the specified temperature is 60-80 DEG C.

[0015] A device for rapid degassing of an insulated core of a long length submarine cable, comprising a degassing room, a hot air heating circulation system connected to the degassing room, an insulated core placed in the degassing room, a direct current power source connected to the insulated core, a degassing byproduct monitoring device, and a control system.

[0016] Preferably, heat-sealing materials are used around the degassing room and the sealed cable storage disc, a heat-sealing cover plate and an air suction device are arranged above the degassing room.

[0017] Preferably, two outgoing and incoming line holes are reserved on the side of the degassing room, and a separate space is arranged at the bottom of the degassing room, the space is provided with an air inlet connected to the hot air heating circulation system, and an air outlet is arranged above the air inlet.

[0018] Compared with the prior art, the device has the following beneficial effects: the cable conductor is heated by passing current, the insulated core of the long length submarine cable is stored in the cable storage disc under airtight and heat preservation conditions, the two ends of the cable are connected to a direct current power source, the output voltage (or current) is slowly increased to a set value after the direct current power source is turned on and is automatically controlled to be constant, the conductor is directly heated and transmits heat to the inner shield, the insulation and the outer shield, the conductor resistance is monitored in real time, and the power is turned off when the conductor resistance reaches a specified value. When this heating method is adopted, the heat generated by the whole cable conductor is uniform, and the efficiency of heat dissipation to the outside through conduction is also high, so that the heating speed of the whole cable is fast, and the time required for the insulated core of the long length submarine cable to reach the degassing temperature specified by the process can be greatly shortened.

[0019] The insulating core of the submarine cable is kept at a constant temperature by circulating hot air. After the conductor temperature of the insulating core reaches the degassing temperature specified by the process, the output voltage (or current) of the direct current power supply is slowly reduced and eventually reduced to zero. Then the direct current power supply is turned off and disconnected from the conductor of the insulating core. Hot air is continuously blown into the sealed space from the lower part of the storage reel to keep the insulating core of the submarine cable at a constant temperature at the specified process temperature for a certain period of time until the content of residual cross-linking by-products inside the insulating core meets the requirements. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is a flow chart of a method for rapid degassing of an insulating core of a long submarine cable according to the present application;

[0021] Figure 2 is a structural schematic diagram of a device for rapid degassing of an insulating core of a long submarine cable according to the present application. DETAILED DESCRIPTION

[0022] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0023] Referring to Figures 1-2, a method for rapid degassing of an insulating core of a long submarine cable includes: S1, placing an insulating core of a desired length in a degassing room, sealing one end of the insulating core and connecting it to an air guide pipe;

[0024] S2, connecting the two ends of the insulating core to a direct current power supply;

[0025] S3, determining the number of meters of the degassing insulating core, measuring the initial direct current resistance of the conductor of the insulating core, and calibrating by measuring the direct current resistance of the conductor at 20°C and theoretically calculating;

[0026] S4, inputting the conductor direct current resistance value reaching the specified temperature through the direct current power supply control page;

[0027] S5, increasing the current or voltage at a speed of 5-20 A / min or 5-20 V / min, and selecting the current or voltage increase speed according to the length of the degassing core, the conductor cross section, and the heat and heating time required to rise to the specified temperature; the currently set current selection range is 50 A-1000 A, and the voltage selection range is 50 V-1000 V. The heat required for conductor heating can be calculated by the following formula:

[0028] W 所需热量 = ρ * g * ((C specified temperature - C initial temperature) / 100) * t (J),

[0029] wherein, p - specific heat capacity of copper, unit: J / (kg·℃)

[0030] g - weight of copper, unit: kg

[0031] t - time, unit: S

[0032] S6, when the temperature of the conductor to be raised to the degassing setting temperature, turn off the power supply, switch to the hot air heating circulation system;

[0033] S7, the hot air heated to the specified temperature into the degassing room, placed in the degassing room thermocouple real-time monitoring temperature, until the specified degassing temperature and keep, continuous monitoring of the concentration of by-products of degassing, when it is reduced to the specified value, close the hot air heating circulation system, natural cooling for 48 hours, the next step process.

[0034] Preferably, including the degassing room, with the degassing room connected hot air heating circulation system, placed in the degassing room insulation wire core, with the insulation wire core connected DC power supply, degassing by-product monitoring device and control system.

[0035] Preferably, the degassing room and the sealed cable storage reel around the use of heat sealing material, the top is provided with heat sealing cover and air suction device.

[0036] Preferably, the degassing room side reserved two outgoing and incoming line hole, the bottom of the degassing room is provided with a separate space, the space is provided with a hot air heating circulation system connected with the air inlet, the air inlet is provided with an air outlet hole above

[0037] Further, the formula for calculating the conductor resistance of the insulation wire core at the specified temperature in S3 is as follows: R t = R 20 × [1 + α (t - 20)],

[0038] Wherein R 20 is the conductor resistance at 20℃; α is the conductor resistance temperature coefficient, that is, the multiple of the increase of the conductor resistance per 1℃ increase in temperature; R t is the conductor resistance at t temperature, wherein t is the specified temperature, and the range of the specified temperature is 60-80℃.

[0039] The device for quick degassing of long length submarine cable insulation core comprises a degassing room, a hot air heating circulation system connected with the degassing room, an insulation core placed in the degassing room, a direct current power supply connected with the insulation core, a degassing by-product monitoring device and a control system. The degassing room and the periphery of the sealed cable storage disc are made of heat preservation sealing material, and a heat preservation sealing cover plate and an air suction device are arranged above the degassing room. Two outgoing and incoming line holes are reserved on the side of the degassing room, and a separate space is arranged at the bottom of the degassing room, and the space is provided with an air inlet connected with the hot air heating circulation system, and an air outlet is arranged above the air inlet. Specifically, when the hot air passing through the densely arranged insulation cores reaches the upper part, the air temperature is reduced, and the air is transported to the air heating device for reheating, and then is sent to the lower part of the degassing room to form a circulation. The structure of the entire degassing room is taken as an example, but the form is not limited thereto, and the structure form of all heat preservation and sealed degassing rooms is within the protection scope.

[0040] In the implementation process, first, the conductor of the insulation core is heated by passing current. The long length submarine cable insulation core is stored in the degassing room under the condition of closed heat preservation, and the conductor exposed at both ends of the insulation core is connected with the direct current power supply; after the direct current power supply is started, the output voltage (or current) is slowly increased to the set value and is automatically controlled to be constant, the conductor is directly heated and the heat is conducted to the inner shield, insulation and outer shield; the conductor resistance is monitored in real time, and the power is cut off when the conductor resistance reaches the specified value. When this heating method is adopted, the whole conductor produces uniform heat, and the efficiency of heat dissipation to the outside through the conduction mode is also relatively high, so that the heating speed of the whole degassing insulation core is fast, and the time required for the long length submarine cable insulation core to reach the degassing temperature specified by the process can be greatly shortened.

[0041] The submarine cable insulation core is kept at constant temperature by circulating the heated gas. After the temperature of the submarine insulation core reaches the degassing temperature specified by the process, the power supply is stopped. The direct current power supply is turned off, and the connection between the direct current power supply and the insulation core is disconnected. The circulating hot air is continuously blown into the closed space from the lower part of the degassing room, so that the submarine cable insulation core is kept at constant temperature for a certain time at the specified process temperature, until the content of the residual crosslinking by-product inside the submarine cable insulation core meets the requirements.

[0042] The number of devices and the processing scale described herein are used to simplify the description of the present application, and the application, modification and change of the present application are obvious to those skilled in the art.

[0043] Although the embodiments of the present application have been disclosed as above, it is not limited to the application and the modification and change of the present application are obvious to those skilled in the art.

Claims

1. A method for rapid degassing of the insulation core of a long-length submarine cable, characterized in that: The following steps are involved: S1. Place the insulated wire core of the required length in the degassing room, seal one end of the insulated wire core and connect it to the air guide tube; S2. Connect both ends of the insulated wire core to a DC power supply; S3. Determine the length of the degassed insulated wire core, measure the initial DC resistance of the insulated wire core conductor, and calibrate the conductor DC resistance at 20°C using a DC bridge and theoretical calculations; S4. Input the DC resistance value of the conductor that reaches the specified temperature through the DC power supply control page; S5. Increase the current or voltage at a rate of 5-20A / min or 5-20V / min. Select the current or voltage increase rate based on the length of the degassed core, the conductor cross-section, the amount of heat required to reach the specified temperature, and the heating time. S6. When the temperature of the conductor reaches the degassing setting temperature, disconnect the power supply and switch to the hot air heating circulation system; S7. The hot air heated to the specified temperature is introduced into the degassing room. A thermocouple is placed in the degassing room to monitor the temperature in real time until the specified degassing temperature is reached and maintained. The concentration of degassing by-products is continuously monitored. When it drops to the specified value, the hot air heating circulation system is turned off and the room is naturally cooled for 48 hours before proceeding to the next step.

2. A method for rapid degassing of an insulated core of a long-length submarine cable according to claim 1, characterized in that: The formula for calculating the resistance of the insulated wire core conductor at the specified temperature in step S3 is as follows: t =R 20 ×[1+α(t-20)], where R 20 is the conductor resistance at 20°C; α is the conductor resistance temperature coefficient, that is, the multiple of the conductor resistance increase when the temperature rises by 1°C; R t It is the conductor resistance at temperature t, where t is the specified temperature and the specified temperature range is 60-80℃.

3. A device for rapid degassing of the insulated core of a long submarine cable according to any one of claims 1-2, characterized in that: The invention comprises a degassing room, a hot air heating circulation system connected to the degassing room, an insulated wire core placed in the degassing room, a DC power supply connected to the insulated wire core, a degassing byproduct monitoring device and a control system.

4. The device for rapid degassing of the insulated core of a long submarine cable as claimed in claim 3, characterized in that: The degassing room and the sealed cable storage drum are all surrounded by thermal insulation and sealing materials, and a thermal insulation and sealing cover plate and an air suction device are arranged on the top.

5. The device for rapid degassing of the insulated core of a long submarine cable as claimed in claim 4, characterized in that: Two outlet and inlet holes are reserved on the side of the degassing room. An independent space is set at the bottom of the degassing room. The space is provided with an air inlet connected to the hot air heating circulation system, and an air outlet is set above the air inlet.

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