CN113843121A - Variable frequency induction heating device and method for externally coated steel pipe - Google Patents
Variable frequency induction heating device and method for externally coated steel pipe Download PDFInfo
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- CN113843121A CN113843121A CN202010597850.XA CN202010597850A CN113843121A CN 113843121 A CN113843121 A CN 113843121A CN 202010597850 A CN202010597850 A CN 202010597850A CN 113843121 A CN113843121 A CN 113843121A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
- B05D3/0254—After-treatment
- B05D3/0281—After-treatment with induction heating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05B—SPRAYING APPARATUS; ATOMISING APPARATUS; NOZZLES
- B05B16/00—Spray booths
- B05B16/20—Arrangements for spraying in combination with other operations, e.g. drying; Arrangements enabling a combination of spraying operations
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/02—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by baking
- B05D3/0254—After-treatment
- B05D3/0272—After-treatment with ovens
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/25—Process efficiency
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Abstract
The invention discloses a variable-frequency induction heating device and method for an externally-coated wire steel pipe, wherein the device comprises a plurality of stages of induction furnaces, a sprayer (6), a middle cladding device (7), an external cladding device (8) and a spray cooler (9) which are arranged along the transmission direction of the steel pipe (1), and the steel pipe is transmitted through a heating area (100), a coating area (200) and a cooling area (300) by a conveying roller way (10); the power supply frequency of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially increased along the transmission direction of the steel pipe, and the power supply power is sequentially reduced. The invention gradually increases the induction heating power supply frequency from the first stage to the last stage of the induction furnace through the graded distribution and adjustment of the power supply power and the power supply frequency of the induction heating, the induction heat is concentrated to the outer surface of the steel pipe to be coated, the temperature rise of the inner surface is reduced while the temperature of the outer surface of the steel pipe is raised, the induction heating efficiency is improved, the energy consumption is reduced, and the invention is particularly suitable for the continuous coating operation of the outer surface of the large-diameter welded pipe for petroleum and natural gas transmission.
Description
Technical Field
The invention relates to a steel pipe coating processing device and a method, in particular to a variable frequency induction heating device and a variable frequency induction heating method for an outer coating line steel pipe.
Background
On a UOE (namely a steel pipe manufactured by three procedures of a U-shaped press, an O-shaped press and an expanded pipe (expanded)) welding pipe external coating production line in the prior art, the steel pipe (with the caliber of 500 plus one material of 1500mm, the wall thickness of 10-40mm and the length of 10-20 m) is conveyed forwards on a tapered roller way in a spiral motion mode, induction heating is carried out on the steel pipe by four medium-frequency induction furnaces which are arranged in sections in a heating zone, and the outer surface of the steel pipe is gradually preheated to the temperature required by the coating process, namely 180 plus one material of 240 ℃. During coating, the epoxy resin powder particles sprayed by static electricity are quickly melted and spread in a short time under the thermal action of the surface of the high-temperature steel pipe and are tightly combined with the surface of the steel pipe to form a protective coating with good environmental corrosion resistance, and an adhesive tape layer, a polyethylene tape layer and the like are wrapped outside the coating to further enhance the surface protection capability of the steel pipe; the spray cooling aims to reduce the temperature of the steel pipe so as to solidify the coating material and facilitate the subsequent processing.
During the induction heating process, the electric power and frequency of each induction furnace are basically the same, the electric power is about 800kW, and the frequency is about 1000 Hz. The temperature of the outer surface of the steel pipe is rapidly increased in the first-stage induction furnace due to induction heating, and the induction heat can be conducted towards the inner wall of the steel pipe (including part towards the inner wall) after the steel pipe is dischargedHeat dissipation of the surrounding environment), the temperature of the outer surface is reduced to a certain extent until the steel pipe enters the next-stage induction heating furnace, and the temperature of the steel pipe is increased again. In the multi-stage induction heating process, the temperature of the outer surface and the inner surface of the steel pipe generally gradually increases. When the coating point position is reached, the outer surface temperature of the steel pipe reaches the coating temperature, namely 220-. The intermediate frequency induction heating mode which is nearly diathermy in the prior art not only wastes a large amount of induction power supply power, but also increases the cooling load and the cooling water consumption (about 500 m) of the cooling section of the coated steel pipe3And h), the utilization rate of the energy and resources of the production line system needs to be improved.
The Chinese invention patent ZL200710024745.1 discloses a medium frequency induction heating treatment method for steel pipes, petroleum well pipes and drill pipes, and particularly discloses a method for quenching and tempering seamless steel pipes through medium frequency induction heating, but the heating method needs the steel pipes with transparent and uniform wall thickness, the medium frequency heating with the frequency of about 1000Hz is generally selected, the direct application can cause the temperature of the inner surface of the steel pipes which do not participate in spraying to be rapidly increased, and a large amount of energy and resources are wasted.
Disclosure of Invention
One of the purposes of the invention is to provide a variable frequency induction heating device of an externally coated steel pipe, which can realize the purposes of increasing the temperature of the outer surface of the steel pipe and inhibiting the temperature rise of the inner surface of the steel pipe through the distribution of power supply power and power supply frequency of each induction furnace, thereby reducing the energy consumption.
The invention also aims to provide a variable-frequency induction heating method for the steel pipe with the externally coated wire, which realizes the staged heating of the steel pipe by adjusting the power supply power and the power supply frequency of the induction heating, concentrates the induction heat to the outer surface of the steel pipe to be coated, reduces the temperature rise of the inner surface, further improves the induction heating efficiency and reduces the energy consumption.
The invention is realized by the following steps:
a frequency conversion induction heating device of an external coating line steel pipe comprises a plurality of stages of induction furnaces, a sprayer, a middle cladding device, an external cladding device and a spray cooler which are sequentially arranged along the transmission direction of the steel pipe, wherein the steel pipe is transmitted through a plurality of conveying roller ways and sequentially passes through a heating zone formed by the plurality of stages of induction furnaces, a coating zone formed by the sprayer, the middle cladding device and the external cladding device and a cooling zone formed by the spray cooler;
the power supply frequency and the power of the induction furnace coils in the induction furnaces of the plurality of stages are different, namely the power supply frequency of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially increased along the transmission direction of the steel pipe, and the power supply power of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially decreased along the transmission direction of the steel pipe.
The number of turns of the coils in the induction furnaces of the plurality of stages is the same, the winding directions of the coils of the induction furnaces of the adjacent two stages are opposite, and compensation capacitors C with different capacitance values are arranged on induction heating power supplies of the induction furnaces of each stage to form induction power supply R-L-C resonant circuits with different power supply frequencies.
And the capacitance values of the compensation capacitors C of the induction furnace coils in the induction furnaces of the plurality of stages are sequentially reduced along the transmission direction of the steel pipe.
The induction furnaces are sequentially arranged at the upstream of the inlet of the sprayer, and the induction furnaces and the conveying roller ways are arranged in a staggered mode.
The induction furnaces and the conveying roller ways are arranged in a staggered mode.
A variable frequency induction heating method of an outer coating line steel pipe comprises the following steps:
step 1: selecting the number of stages of the induction furnace according to the caliber of the steel pipe;
step 2: adjusting the capacitance value of the compensation capacitor C corresponding to the one-stage or multi-stage induction furnace selected in the step 1, so that the power supply frequency of the induction furnace coils in the multi-stage induction furnace is sequentially increased along the transmission direction of the steel pipe, and the power supply power of the induction furnace coils in the multi-stage induction furnace is sequentially decreased along the transmission direction of the steel pipe;
and step 3: the steel pipe is conveyed by a conveying roller way and sequentially passes through a heating area, a coating area and a cooling area.
In the step 1, when the induction furnace is selected, the induction furnace is selected in a reverse direction along the transmission direction of the steel pipe, namely the induction furnace close to the sprayer is preferably selected.
Compared with the prior art, the invention has the following beneficial effects:
1. the multi-stage induction furnace with the sequentially increased power supply frequency and the sequentially decreased power supply power can heat the steel pipe in stages, so that induction heat is concentrated on the outer surface of the coated steel pipe, the temperature rise of the inner surface of the coated steel pipe is reduced while the temperature of the outer surface of the coated steel pipe is increased, the induction heating efficiency is further improved, energy medium consumption of subsequent cooling water and the like is reduced, the energy utilization rate of a coating production line system is improved, and the production efficiency of a steel pipe coating machine set is improved.
2. The invention realizes non-transparent induction heating through optimized distribution of power and frequency, the induction heating efficiency can be improved by 10-30%, the cooling water consumption can be reduced by 10-30%, the energy utilization rate of the system can be improved by 10-30%, the speed of a coating unit can be improved by 10-30%, and remarkable economic benefit can be brought.
3. The invention is suitable for continuous coating lines on the outer surface of large-diameter welded pipes for petroleum and natural gas transportation, can be popularized and applied to induction heating processes of various pipe/wire/bar long steel and even steel plates/blanks, and effectively improves the heating quality and heating efficiency of hierarchical induction heating.
The invention gradually increases the induction heating power supply frequency from the first-stage induction furnace to the last-stage induction furnace through the graded distribution and adjustment of the power supply power and the power supply frequency of the induction heating, concentrates the induction heat to the outer surface of the steel pipe to be coated, increases the temperature of the outer surface of the steel pipe, reduces the temperature rise of the inner surface, further improves the induction heating efficiency and reduces the energy consumption, and is particularly suitable for the continuous coating operation of the outer surface of the large-caliber welded pipe for petroleum and natural gas transportation.
Drawings
FIG. 1 is a schematic diagram of the change in internal and external surface temperature by induction heating of a steel pipe according to the prior art;
FIG. 2 is a schematic structural view of a variable frequency induction heating apparatus for an outside coated steel pipe according to the present invention;
FIG. 3 is a schematic diagram showing the change of the temperature of the inner and outer surfaces of a steel pipe in the process of induction heating of the steel pipe by the variable frequency induction heating apparatus for an outer coated steel pipe according to the present invention.
In the figure, a steel pipe 1, a first-stage induction furnace 2, a second-stage induction furnace 3, a third-stage induction furnace 4, a fourth-stage induction furnace 5, a sprayer 6, a middle cladding device 7, an outer cladding device 8, a spray cooler 9 and a conveying roller bed 10 are arranged; 100 heating zone 200 coating zone, 300 cooling zone.
Detailed Description
The invention is further described with reference to the following figures and specific examples.
Referring to fig. 2, a variable frequency induction heating apparatus for an external coating line steel pipe includes a plurality of stages of induction furnaces, a sprayer 6, an intermediate coater 7, an external coater 8 and a spray cooler 9, which are sequentially arranged along a transmission direction of the steel pipe 1, wherein the steel pipe 1 is transmitted through a plurality of roller conveyors 10, as shown by arrows in fig. 2, and sequentially passes through a heating zone 100 formed by the plurality of stages of induction furnaces, a coating zone 200 formed by the sprayer 6, the intermediate coater 7 and the external coater 8, and a cooling zone 300 formed by the spray cooler 9.
The power supply frequency and the power of the induction furnace coils in the induction furnaces of the plurality of stages are different, namely the power supply frequency of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially increased along the transmission direction of the steel pipe 1, and the power supply power of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially reduced along the transmission direction of the steel pipe 1. Preferably, the power frequency range of the induction furnaces of a plurality of stages is 800-10000Hz, and the induction furnaces can be sectionally arranged according to the heating process requirement in use according to the principle of gradual increase, and particularly the power frequency can be adjusted by arranging a compensation capacitor C and the like; the power supply power range of the induction furnaces in a plurality of stages is 400-1000kW, the induction furnaces can be arranged in a segmented mode according to the heating process requirement in a step-by-step reduction principle during use, specifically, the power supply power can be adjusted through equipment such as a transformer, and meanwhile, the higher the power supply frequency of the induction furnaces is, the lower the corresponding power supply power is.
The winding directions of the coils of the induction furnaces in the two adjacent stages are opposite, so that the accumulative effect of the induction voltage of the steel pipe 1 during induction heating is prevented, the steel pipe 1 is prevented from being ignited by discharging due to overhigh accumulative potential, and the surface quality of the steel pipe 1 and the safety of the conveying roller way 10 are prevented from being influenced.
The number of turns of the coils in the induction furnaces of the plurality of stages is basically the same, and compensation capacitors C with different capacitance values are arranged on the induction heating power supply of each stage of induction furnace to form induction power supply R-L-C resonant circuits with different power supply frequencies. Preferably, the capacitance value range of the compensation capacitor C is 5-800uF, and the compensation capacitor C can be set in sections according to the heating process requirement and the gradual reduction principle in use, and can be adjusted by changing the series-parallel connection mode of the capacitor. The purpose of changing the working frequency of alternating current of different induction heating power supplies is realized by adjusting the capacitance value of the compensation capacitor C to change the resonance frequency and tracking the frequency, and the arrangement complexity of coils of the induction furnace in the induction furnace is reduced.
And the capacitance values of the compensation capacitors C of the induction furnace coils in the induction furnaces of the plurality of stages are sequentially reduced along the transmission direction of the steel pipe 1. In the R-L-C resonant circuit of the induction power supply, the resonant frequency f = 1/(2 pi sqrt (LC)), and under the condition that the load inductance L is basically unchanged, the smaller the compensation capacitor C is, the larger the frequency f is, so that the capacitance value of the compensation capacitor C of the induction heating power supplies of a plurality of stages is gradually reduced, thereby realizing the adjustment and distribution of the frequency of the induction heating power supplies from low to high, and enabling each stage of induction heating power supplies to work in the optimal state.
The induction furnaces are sequentially arranged at the upstream of the inlet of the sprayer 6, and the induction furnaces and the conveying roller ways 10 are arranged in a staggered mode. Preferably, every two stages of induction furnaces and one conveying roller way 10 are arranged in a staggered mode, so that the positions of the induction furnaces are mutually concentrated, the position of a heating area 100 formed by the induction furnaces is close to the position of a coating area 200, the passing time of the steel pipe 1 in the heating area 100 in the induction heating process can be shortened, and the conduction of the induction heat on the surface of the steel pipe 1 in the steel pipe 1 and the loss of the induction heat to the surrounding environment are reduced.
Referring to fig. 3, the horizontal axis represents time, the vertical axis represents the temperature of the steel pipe, the solid line represents the temperature of the outer surface of the steel pipe, and the broken line represents the temperature of the inner surface of the steel pipe. According to the invention, the power supply frequency and the power supply power of each stage of induction furnace are distributed step by step, and during induction heating, the induction heating with higher frequency at the later stage is used for further and rapidly increasing the temperature of the surface layer of the steel pipe at the shallower depth part through the electromagnetic skin effect on the basis of the induction heating temperature field with lower temperature and deeper depth formed by lower induction heating at the former stage. Make induction heating heat concentrate to the surface of steel pipe at the induction heating in-process, the degree of depth of steel pipe surface high temperature part is shallower, the heat is bigger to the heat resistance of steel pipe inner wall conduction, the time is shorter, the heat is still less, restrain the temperature rise of the steel pipe inner wall that does not participate in the spraying, thereby make the required electric power of back one-level induction heating can progressively reduce, the required cooling water quantity of spraying cooling section after the coating must correspondingly reduce, reduce cooling load when finally realizing improving induction heating efficiency, improve energy utilization efficiency, reduce energy consumption mesh such as cooling water.
A variable frequency induction heating method of an external coated wire steel pipe can be used for commonly used steel pipes with the variable frequency induction heating caliber range of 500mm to 1500mm, and comprises a small-caliber welding pipe with the outer diameter of 500 plus 1000mm, a large-caliber welding pipe with the outer diameter of 1000 plus 1500mm and the like. The variable frequency induction heating comprises the following steps:
step 1: the number of the induction furnaces is selected according to the caliber of the steel pipe, preferably, when the induction furnace is selected, the induction furnace can be selected reversely along the transmission direction of the steel pipe 1, namely, the induction furnace close to the sprayer 6 is preferably selected, and the time interval between two procedures of induction heating and spraying is reduced, so that the conduction of the induction heat on the surface of the steel pipe 1 in the steel pipe 1 and the loss of the induction heat to the surrounding environment are reduced.
Step 2: and (3) adjusting the capacitance value of the compensation capacitor C corresponding to the induction furnace of the first stage or the plurality of stages selected in the step (1), so that the power supply frequency of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially increased along the transmission direction of the steel pipe 1, and the power supply power of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially decreased along the transmission direction of the steel pipe 1.
And step 3: the steel pipe 1 is conveyed by the rollgang 10 such that the steel pipe 1 passes through the heating zone 100, the coating zone 200, and the cooling zone 300 in this order.
Example 1:
arrange level four induction furnaces in variable frequency induction heating device's the zone of heating 100, be one-level induction furnace 2, second grade induction furnace 3, tertiary induction furnace 4 and level four induction furnace 5 along 1 direction of transmission of steel pipe in proper order, and one-level induction furnace 2 and second grade induction furnace 3 set up between two adjacent rollgang 10, and tertiary induction furnace 4 and level four induction furnace 5 set up between two adjacent rollgang 10 and are close to the setting of sprayer 6. The coil forward winding of one-level induction furnace 2, the coil reverse winding of second grade induction furnace 3, the coil forward winding of tertiary induction furnace 4, the coil reverse winding of level four induction furnace 5.
The small-caliber welded pipe with the outer diameter of 660mm is heated, coated and cooled, and the purpose of heating the outer surface of the steel pipe 1 to the temperature required by coating can be achieved by selecting the three-stage induction furnace 4 and the four-stage induction furnace 5 which are close to the sprayer 6 due to the small caliber of the steel pipe 1. Adjusting the power frequency of the three-stage induction furnace 4 to be 1000Hz, the power output power to be 800kW, and the capacitance value of the compensation capacitor C corresponding to the three-stage induction furnace 4 to be 500 uF; the power frequency of the four-stage induction furnace 5 is adjusted to 4000Hz, the power output power is 600kW, and the capacitance value of the compensation capacitor C corresponding to the four-stage induction furnace 5 is 31.25 uF. After the steel pipe 1 passes through the induction furnace coils of the three-level induction furnace 4 and the four-level induction furnace 5 in sequence through the conveying roller way 10 for induction heating, the temperature of the outer surface reaches 220 ℃ in the coating area 200, the coating process requirement is met, the temperature of the inner wall of the steel pipe 1 is controlled to be 160-180 ℃, the electric energy is saved by 12.5% in the heating process, meanwhile, the spray cooling water required for cooling the steel pipe 1 by the subsequent spray cooler 9 is correspondingly reduced, and the consumption of the spray cooling water can be at least reduced by 10%.
Example 2:
arrange level four induction furnaces in variable frequency induction heating device's the zone of heating 100, be one-level induction furnace 2, second grade induction furnace 3, tertiary induction furnace 4 and level four induction furnace 5 along 1 direction of transmission of steel pipe in proper order, and one-level induction furnace 2 and second grade induction furnace 3 set up between two adjacent rollgang 10, and tertiary induction furnace 4 and level four induction furnace 5 set up between two adjacent rollgang 10 and are close to the setting of sprayer 6.
The small-caliber welded pipe with the outer diameter of 660mm is heated, coated and cooled, and the purpose of heating the outer surface of the steel pipe 1 to the temperature required by coating can be achieved by selecting the three-stage induction furnace 4 and the four-stage induction furnace 5 which are close to the sprayer 6 due to the small caliber of the steel pipe 1. Adjusting the power frequency of the three-stage induction furnace 4 to be 1000Hz, the power output power to be 800kW, and the capacitance value of the compensation capacitor C corresponding to the three-stage induction furnace 4 to be 500 uF; the power frequency of the four-level induction furnace 5 is adjusted to 10000Hz, the power output power is 400kW, and the capacitance value of the compensation capacitor C corresponding to the four-level induction furnace 5 is 5 uF. After the steel pipe 1 passes through the induction furnace coils of the three-level induction furnace 4 and the four-level induction furnace 5 in sequence through the conveying roller way 10 for induction heating, the temperature of the outer surface reaches 220 ℃ in the coating area 200, the coating process requirement is met, the temperature of the inner wall of the steel pipe 1 is controlled at 140-160 ℃, the electric energy is saved by 25% in the heating process, meanwhile, the spray cooling water required for cooling the steel pipe 1 by the subsequent spray cooler 9 is correspondingly reduced, and the consumption of the spray cooling water can be at least reduced by 20%.
Example 3:
arrange level four induction furnaces in variable frequency induction heating device's the zone of heating 100, be one-level induction furnace 2, second grade induction furnace 3, tertiary induction furnace 4 and level four induction furnace 5 along 1 direction of transmission of steel pipe in proper order, and one-level induction furnace 2 and second grade induction furnace 3 set up between two adjacent rollgang 10, and tertiary induction furnace 4 and level four induction furnace 5 set up between two adjacent rollgang 10 and are close to the setting of sprayer 6.
The large-diameter welded pipe with the outer diameter of 1420mm is heated, coated and cooled, and because the diameter of the steel pipe 1 is large, a four-stage induction furnace is selected for heating so as to achieve the purpose of heating the outer surface of the steel pipe 1 to the temperature required by coating. Adjusting the power frequency of the primary induction furnace 2 to be 1000Hz, the power output power to be 800kW, and the capacitance value of the compensation capacitor C corresponding to the primary induction furnace 2 to be 500 uF; adjusting the power frequency of the secondary induction furnace 3 to 2000Hz, the power output power to 700kW, and the capacitance value of the compensation capacitor C corresponding to the secondary induction furnace 3 to 125 uF; adjusting the power frequency of the three-stage induction furnace 4 to 4000Hz, the power output power to 600kW, and the capacitance value of the compensation capacitor C corresponding to the three-stage induction furnace 4 to 31.25 uF; the power frequency of the four-level induction furnace 5 is adjusted to 10000Hz, the power output power is 400kW, and the capacitance value of the compensation capacitor C corresponding to the four-level induction furnace 5 is 5 uF. After the steel pipe 1 passes through the induction furnace coils of the first-stage induction furnace 2, the second-stage induction furnace 3, the third-stage induction furnace 4 and the fourth-stage induction furnace 5 in sequence through the conveying roller way 10 for induction heating, the outer surface temperature reaches 220 ℃ in the coating area 200, the coating process requirement is met, the inner wall temperature of the steel pipe 1 is controlled at 120-140 ℃, the electric energy is saved by 21.88% in the heating process, meanwhile, the spray cooling water required for cooling the steel pipe 1 by the subsequent spray cooler 9 is correspondingly reduced, and the consumption of the spray cooling water can be reduced by at least 20%.
Example 4:
arrange level four induction furnaces in variable frequency induction heating device's the zone of heating 100, be one-level induction furnace 2, second grade induction furnace 3, tertiary induction furnace 4 and level four induction furnace 5 along 1 direction of transmission of steel pipe in proper order, and one-level induction furnace 2 and second grade induction furnace 3 set up between two adjacent rollgang 10, and tertiary induction furnace 4 and level four induction furnace 5 set up between two adjacent rollgang 10 and are close to the setting of sprayer 6.
The large-diameter welded pipe with the outer diameter of 1420mm is heated, coated and cooled, and because the diameter of the steel pipe 1 is large, a four-stage induction furnace is selected for heating so as to achieve the purpose of heating the outer surface of the steel pipe 1 to the temperature required by coating. Adjusting the power frequency of the primary induction furnace 2 to be 1000Hz, the power output power to be 700kW, and the capacitance value of the compensation capacitor C corresponding to the primary induction furnace 2 to be 500 uF; adjusting the power frequency of the secondary induction furnace 3 to 2500Hz, the power output power to 600kW, and the capacitance value of the compensation capacitor C corresponding to the secondary induction furnace 3 to 80 uF; adjusting the power frequency of the three-stage induction furnace 4 to be 5000Hz, the power output power to be 500kW, and the capacitance value of the compensation capacitor C corresponding to the three-stage induction furnace 4 to be 20 uF; the power frequency of the four-level induction furnace 5 is adjusted to 10000Hz, the power output power is 400kW, and the capacitance value of the compensation capacitor C corresponding to the four-level induction furnace 5 is 5 uF. After the steel pipe 1 passes through the induction furnace coils of the first-stage induction furnace 2, the second-stage induction furnace 3, the third-stage induction furnace 4 and the fourth-stage induction furnace 5 in sequence through the conveying roller way 10 for induction heating, the outer surface temperature reaches 220 ℃ in the coating area 200, the coating process requirement is met, the inner wall temperature of the steel pipe 1 is controlled at 110-130 ℃, the electric energy is saved by 31.25% in the heating process, meanwhile, the spray cooling water required for cooling the steel pipe 1 by the subsequent spray cooler 9 is correspondingly reduced, and the consumption of the spray cooling water can be reduced by at least 30%.
The present invention is not limited to the above embodiments, and any modifications, equivalent replacements, improvements, etc. within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A variable frequency induction heating device of an external coating line steel pipe comprises a plurality of stages of induction furnaces, a sprayer (6), a middle cladding device (7), an external cladding device (8) and a spray cooler (9) which are sequentially arranged along the transmission direction of the steel pipe (1), wherein the steel pipe (1) is transmitted through a plurality of conveying roller ways (10) and sequentially passes through a heating zone (100) formed by the plurality of stages of induction furnaces, a coating zone (200) formed by the sprayer (6), the middle cladding device (7) and the external cladding device (8), and a cooling zone (300) formed by the spray cooler (9);
the method is characterized in that: the power supply frequency and the power of the induction furnace coils in the induction furnaces of the plurality of stages are different, namely the power supply frequency of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially increased along the transmission direction of the steel pipe (1), and the power supply power of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially decreased along the transmission direction of the steel pipe (1).
2. The variable frequency induction heating apparatus of an outside coated steel pipe as set forth in claim 1, wherein: the number of turns of the coils in the induction furnaces of the plurality of stages is the same, the winding directions of the coils of the induction furnaces of the adjacent two stages are opposite, and compensation capacitors C with different capacitance values are arranged on induction heating power supplies of the induction furnaces of each stage to form induction power supply R-L-C resonant circuits with different power supply frequencies.
3. The variable frequency induction heating apparatus of an outside coated steel pipe as set forth in claim 2, wherein: the capacitance values of the compensation capacitors C of the induction furnace coils in the induction furnaces of the plurality of stages are sequentially reduced along the transmission direction of the steel pipe (1).
4. The variable frequency induction heating apparatus of an outside coated steel pipe as set forth in claim 1, wherein: the induction furnaces are sequentially arranged at the upstream of the inlet of the sprayer (6), and the induction furnaces and the conveying roller way (10) are arranged in a staggered mode.
5. The variable frequency induction heating apparatus of an outside coated steel pipe as set forth in claim 4, wherein: each two stages of induction furnaces are arranged in a staggered mode with one conveying roller way (10).
6. A method of variable frequency induction heating of a steel pipe using the variable frequency induction heating apparatus of an outside coated steel pipe of claim 1, characterized by: the method comprises the following steps:
step 1: selecting the number of stages of the induction furnace according to the caliber of the steel pipe;
step 2: adjusting the capacitance value of the compensation capacitor C corresponding to the induction furnace of the first stage or the plurality of stages selected in the step 1, so that the power supply frequency of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially increased along the transmission direction of the steel pipe (1), and the power supply power of the induction furnace coils in the induction furnaces of the plurality of stages is sequentially decreased along the transmission direction of the steel pipe (1);
and step 3: the steel pipe (1) is conveyed through a conveying roller way (10), so that the steel pipe (1) sequentially passes through a heating area (100), a coating area (200) and a cooling area (300).
7. The variable frequency induction heating method according to claim 6, wherein: in the step 1, when the induction furnace is selected, the induction furnace is selected in a reverse direction along the transmission direction of the steel pipe (1), namely, the induction furnace close to the sprayer (6) is preferentially selected.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN202010597850.XA CN113843121B (en) | 2020-06-28 | 2020-06-28 | Variable frequency induction heating device and method for externally coated steel pipe |
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| CN202010597850.XA CN113843121B (en) | 2020-06-28 | 2020-06-28 | Variable frequency induction heating device and method for externally coated steel pipe |
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| CN113843121A true CN113843121A (en) | 2021-12-28 |
| CN113843121B CN113843121B (en) | 2023-03-24 |
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