1. Main parameters and brand requirements of a complete set of induction heating equipment for steel pipe temperature raising
The main equipment of this heating system consists of two 2000KVA six-phase rectifier transformers, two twelve-pulse 1500KW/1500Hz parallel resonant intermediate frequency power supplies, two capacitor cabinets and two sets of inductors (6 sets each), with a total power of 3000KW. The temperature automatic control system is composed of Advantech industrial computer, Siemens S7-300 PLC, three sets of American Raytek two-color infrared thermometers, three sets of Turck photoelectric switches and two sets of BALLUFF speed measuring devices. The industrial control software is Siemens authorized software.
2. Process parameter requirements
A. Steel pipe specifications:
Φ133×14 4.5m length (the actual outer diameter is controlled below Φ135)
Φ102×12 3~4.0m length (the actual outer diameter is controlled below Φ105)
Φ72×7 4.5m length (the actual outer diameter is controlled below Φ75)
B. Steel pipe material: TP304, TP321, TP316, TP347, P11, P22, etc.
C. Heating temperature: about 150℃, the temperature before the stainless steel tube enters the furnace: the head is about 920～950℃, the tail is about 980～1000℃, and the internal temperature of the pipe is higher than the external temperature), the low temperature end is required to be heated and the whole The temperature is raised to (1070～1090) ℃ at the head and tail, and the temperature difference between the head and tail is controlled within 30 degrees when it is out of the furnace.
D. Maximum bend of steel pipe (straightness): 10mm/4500mm
F. Heating speed: ≥0.30m~0.45m/sm/s
E. Heating process control: the uniformity of the discharge temperature should be ensured, and the deformation of the pipe should be reduced. The furnace body has a total of 6 sections, each section is about 500mm in length (each power supply controls the heating of 3 sections of the furnace body). At the entrance and exit of each group of furnaces Two-color thermometers are installed for temperature measurement, speed measurement devices are installed for speed measurement, and closed-loop temperature control is realized. Reliable and optimized control algorithms are used. After temperature simulation data collection and processing, data calculation, dynamic adjustment and precise control of the output of each group of furnace bodies Power, to ensure that the discharge temperature of different specifications of tube blanks tends to be consistent, and the uniformity is better, and it overcomes the danger of microscopic cracks caused by thermal stress.
In addition, in order to make up for the time difference of the temperature measurement by the thermometer and improve the control sensitivity, a hot body detection device is installed at the entrance and exit of each group of furnaces to make the heating furnace more sensitive and reliable in maintaining power and high power switching between unfilled and filled materials.
3. Six-phase rectifier transformer parameters and functional requirements:
The whole set of equipment uses two 2000KVA rectifier transformers, each with a 12-pulse rectifier structure. The main parameters are as follows:
Rated capacity: Sn=2000KVA
Primary voltage: U1=10KV 3φ 50Hz
Secondary voltage: U2=660V
Connection group: d/d0, Y11
Efficiency: η≥ 98%
Cooling method: oil-immersed natural cooling
Protection function: heavy gas trip, light gas trip, pressure release switch, oil over-temperature alarm
With ±5%, 0% three-stage voltage regulation on the high-pressure side
4. The main parameters and functional requirements of the intermediate frequency power supply for the complete set of steel pipe temperature raising induction heating equipment:
Input voltage: 660V
DC voltage: 890V
DC current: 1700A
Intermediate frequency voltage: 1350V
Intermediate frequency: 1500Hz
Intermediate frequency power: 1500KW/each
5. Capacitor cabinet requirements
a, capacitor selection
1500Hz electric heating capacitor produced by Xin’anjiang Power Capacitor Factory
Model number: RFM2 1.4—2000—1.5S
The capacitor is installed under the furnace frame about 500mm below the floor of the furnace frame, the trench depth is greater than 1.00 meters, and the trench width is 1.4 meters.
b. Water cooling pipeline requirements
Made of thick-walled stainless steel, 3.5-inch water inlet pipe, 4-inch water return pipe, and other 2.5-inch pipes, including stainless steel pipe fittings and switches.
6. Inductor and furnace requirements
The two ends of the furnace body adopt copper guard plates to reduce magnetic leakage, and the design of water flow in the circumference of the furnace mouth. The chassis is made of non-magnetic stainless steel. The copper tube is wound with T2 oxygen-free copper, the wall thickness of the copper tube is greater than or equal to 2.5mm, and the furnace body insulation material is made of American Union Ore knotting material, which has high strength, high temperature resistance and longer service life; the furnace body guard plate adopts high strength Thick insulating board. The inlet and return water of the furnace body adopts stainless steel quick-change joints, which is convenient for the replacement of the furnace body.
There is a drain hole at the bottom of the induction furnace body, which can automatically drain the condensed water in the furnace.
7. Requirements for the lifting bracket of the sensor
a. A total of 6 sensor brackets are installed between the roller tables for the installation of sensors.
b. In order to prevent the bracket from being heated, the bottom plate of the inductor and the top plate of the bracket are made of non-magnetic stainless steel.
c. For steel pipes of different diameters, the corresponding sensors need to be replaced and the center height can be adjusted.
d. The bolt holes of the sensor are made into long holes for easy adjustment.
e. The center height of the sensor can be adjusted by the stud nut in the sensor mounting plate.
f. The two connecting copper bars at the bottom of the inductor and the water-cooled cable from the capacitor cabinet are each connected with 4 stainless steel (1Cr18Ni9Ti) bolts.
g. The water inlet and outlet pipes of the sensor and the main water pipe are connected by quick-change joints and hoses, which are not affected by the position error, and realize the rapid connection of the sensor waterway.
h. The sensors can be quickly replaced, and each replacement time is less than 10 minutes, and it is equipped with two trolleys for the replacement of the sensors.
8. Steel pipe centering water cooling and pressing device
In order to prevent the steel pipe from violently hitting the sensor during transmission through the induction furnace and causing damage to the sensor, a power-driven steel pipe centering device should be installed at the inlet and outlet ends of each power supply to ensure that the steel pipe passes through the sensor smoothly. Without hitting the furnace body. The height of this device is adjustable, suitable for φ72, φ102, and φ133 steel pipes. The speed of this device is adjustable, using Siemens frequency conversion motor and frequency converter, the frequency conversion speed adjustment range is less than 10 times. The water-cooled rollers are made of non-magnetic stainless steel.
9. Closed water cooling system
a. The closed cooling device with the total flow of the furnace cooling water of 200 m3/h shares one set or one set of each, but the intermediate frequency power supply, resonance capacitor, and sensor water system are required to be separated to prevent interference. The closed cooling device should be made of imported hot-dip galvanized steel, brand-name fans, water pumps and control components.
b. The water-cooling pipeline is required to be made of thick-walled stainless steel, including stainless steel pipe fittings and switches.