Medium Frequency Induction Furnace

1.Overview: refers to amedium frequency induction furnace operating frequency in the range of 150~10000Hz induction furnace , medium frequency induction furnace smelting is the special equipment for metallurgical quality of steels and alloys having a melting fast speed, high efficiency, adaptability, The utility model has the advantages of flexible use, good electromagnetic stirring effect, convenient starting operation, and the like.

Frequency: 150 ~ 10000 Hz

Advantage: fast melting speed, high production efficiency, etc.

Composition: medium frequency power supply and medium frequency induction furnace body part, the furnace part includes steel shell furnace body or aluminum shell furnace body, tilting furnace device including reducer tilting furnace or hydraulic tilting furnace mechanism and water cooling system such as closed loop cooling tower, etc.

2，the price of the medium frequency induction furnace :

The power of the medium frequency induction furnace power supply and the volume of the furnace body are calculated. Different configuration prices vary. This price is for reference only. For specific prices, please contact: firstfurnace@gmail.com

3, the summary of the furnace structure selection of the intermediate frequency induction furnace

4, the intermediate frequency induction furnace parameters collection :

5. How to choose the capacity of the intermediate frequency induction furnace transformer? 
        The relationship between the capacity of the intermediate frequency induction furnace transformer and the power of the SCR intermediate frequency power supply is: the value of the transformer capacity = the value of the intermediate frequency power supply × 1.2.   Medium-frequency induction furnace transformer capacity and IGBT half-bridge series inverter intermediate frequency power supply (commonly known as one for two, one for melting one insulation, two for simultaneous operation) The numerical relationship between transformer capacity and power supply is: value of transformer capacity = The value of the series inverter IF power supply × 1.1. The transformer is a rectifier transformer. In order to reduce the interference of harmonics, as far as possible for the special plane, a medium-frequency induction furnace is equipped with a dedicated rectifier transformer.

How to choose the input voltage of the intermediate frequency induction furnace? 
         Medium frequency induction furnace adopts medium frequency power supply below 1000KW , generally adopts three-phase five-wire 380V , 50Hz industrial power, and is equipped with 6- pulse single-phase rectified intermediate frequency power supply; for medium frequency power supply above 1000KW , it focuses on using 660V incoming voltage (some manufacturers) Use 575V or 750V , because 575V or 750V is a non-standard voltage level, accessories are not good to buy, it is recommended not to use)

6, How to choose the 12- pulse double-rectifier intermediate frequency induction furnace incoming line voltage?

Is to increase the rated working voltage by increasing the incoming line voltage;

The harmonic generated by high power will interfere with the power grid. The double rectifier can obtain a relatively straight DC current. The load current is a rectangular wave, and the load voltage wave is close to a sine wave, which reduces the impact of grid interference on other devices.

Do not blindly pursue high voltage (some 1000KW use 900V line voltage), energy saving has been achieved since low current, high voltage is easy to shorten the life of electrical components, copper bars, cables are fatigued, and the life of electric furnace is greatly reduced.

7. How to calculate the cable of the intermediate frequency induction furnace?

For example: 250KG-500KG medium frequency induction furnace has an intermediate frequency power supply of 350kw , 350KW intermediate frequency power supply cable = 350/380/1.732/2=266A, that is to say, the 350KW intermediate frequency power supply has a line voltage of 380V . AC current is 532A, the choice of 240mm2Copper, aluminum 315mm2 square, of course, depends on the length of the cable, it does not matter in the 20M. 350KW medium frequency power supply, water cooling, motor 4KW cable 4mm2 , 250GK medium frequency electric furnace desuperheater type 231 ; motor 0.75KW , 500KG medium frequency induction furnace tilting reducer type 431 ; motor 2.2KW , 2.5mm2 cable.

8. How large is the closed cooling tower calculation method for the medium frequency induction furnace ?

First, we must determine the power of the medium frequency induction furnace. Under normal circumstances, the medium frequency power supply of the 500KG medium frequency induction furnace is 400kw. If a water cooling tower is selected to cool the whole equipment, the calculation formula is 400kw × 0.55 × 860 ÷5000=37.84T closed loop cooling. tower. If an integrated layered cooling tower is selected to separately cool the intermediate frequency power supply and the furnace body, the cooling tower tonnage selection formula of the intermediate frequency frequency power supply is: 400kw × 0.12 × 860 ÷ 5000=8.256T , and the cooling tower tonnage selection formula of the furnace induction coil is : 400kw × 0.45 × 860 ÷ 5000=30.96T , the integrated layered closed-loop cooling tower is selected as 8.256T + 30.96T=39.216T should be selected as 40T cooling tower, the corresponding model is: ZXZ-40T ( 10/30)

9. What are the technical requirements for cooling water in the cooling parts of the medium frequency induction furnace ?

Different frequency induction furnace cooling portion cooling requirements different from water, an induction coil, a capacitor of the cooling water system using industrial cooling water pressure, the pressure is maintained at 0.15-0.2mpa, water temperature maintained at 20-35 ° C inlet water temperature temperature below 55 ° C.

10. What are the requirements for cooling water during the use of medium frequency induction furnace ? In general, how big is the reservoir?

The medium frequency induction furnace is composed of two parts, which are divided into an intermediate frequency power supply and a furnace body. The same cooling device can be used or two sets of cooling devices independent of each other can be used. The purpose is to avoid mutual influence, because the intermediate frequency power supply requires low temperature cooling water (pure water), and the outlet water temperature should be controlled within 55 ° C , but the cooling water temperature of the induction coil of the electric furnace can be slightly higher, which can improve the thermal efficiency of the electric furnace. At the same time, the volume of the cooling device is reduced, thereby reducing the cost.

  Because the diameter or diameter of the induction coil is relatively large, it is not easy to block, so the coil cooling is not as high as the water quality requirement for water quality without power supply cooling. . . Generally, the general cooling equipment can be used to meet the demand. The furnace induction coil can be cooled by using ordinary water reservoirs or other cooling equipment such as plate heat exchangers or closed cooling towers.

Whether the cooling method requires the cooling effect and characteristics of the reservoir

1. Closed cooling tower: the best cooling effect, completely closed, no scaling, good cooling effect but the biggest investment

2. cross-flow cooling tower: excellent cooling effect , semi-closed, good cooling effect, small investment but high operating cost

3. plate heat exchanger: good cooling effect, suitable for use with the pool , good cooling effect , small investment

4. reservoir 30 cubic meters : poor cooling effect, easy to block, the general investment is minimal, the cooling effect is general.

11. What information does the customer need to provide to the supplier before purchasing the intermediate frequency induction furnace?

1. The medium frequency induction furnace must have room for layout, and the area of the plant needs to be provided and layout.

2. The customer needs to provide the capacity of the transformer, the magnitude of the incoming line voltage, and the frequency of the incoming line voltage.

3. The medium frequency induction furnace needs water cooling equipment, and the configuration of the medium frequency induction furnace contains water cooling equipment.

4. The structure of the medium frequency induction furnace has a steel shell body and an aluminum shell body, which requires the customer to specify the furnace structure.

5. The power supply of the medium frequency induction furnace is the intermediate frequency power supply. The line structure of the intermediate frequency power supply is divided into the inverter parallel and the inverter series structure. The inverter series structure is energy-saving, the power factor is 0.98 , and the line is stable. The inverter parallel structure is of the common type with a power factor of 0.92 , which requires the customer to specify the line structure.

12, medium frequency induction furnace selection summary table 
        In general, the weight of the intermediate frequency induction furnace can be determined according to the weight of the individual piece and the weight of the molten iron required for each working day, and then the power and frequency of the intermediate frequency power supply are determined. The medium frequency induction furnace is a non-standard product. There are no standards at present, and the general configuration of the industry is shown in the table below .

       It can be seen from the table that the power density of the domestic medium frequency induction furnace is basically around 500 KW / ton, which is lower than the theoretical optimal value of 600-800 KW , mainly considering the life of the lining and production management. At high power density, electromagnetic stirring will produce a strong scouring of the lining, and the requirements for lining materials, furnace building methods, melting processes, materials, and auxiliary materials are high. According to the above configuration, the melting time per furnace is 75 minutes (including feeding, salvaging impurities, quenching and tempering time). If it is necessary to shorten the melting time per furnace, the power density of the power supply can be increased by 1000 KW/ ton while the capacity of the furnace is constant . 
13, brand IF induction furnace manufacturers which is better ?

The series inverter medium frequency induction furnace adopts 6- phase 12- pulse series inverter. The series inverter medium frequency induction furnace realizes the power adjustment by adjusting the output frequency. The multi-phase rectifier bridge in the whole process is full open rectification, and does not constitute a voltage commutation gap, that is, no voltage harmonics appear. But also in the entire process of the power factor of the grid 9 is 0.9 or more, and therefore do not need additional power factor correction device and harmonic filtering.

Luoyang Songdao Induction Heating Technology Co., Ltd.'s series inverter thyristor medium frequency induction furnace has the following advantages.

1. The whole machine can realize fool-like operation to avoid accidents caused by operational errors.

2 , the rectification inverter is combined with a power potentiometer to complete the buffer soft start. Self-judgment of the load state, if the load is short-circuited or open circuit, the zero-impact, micro-current lock-controlled inverter output can be used to avoid further expansion of the fault.

3 , high power factor, low harmonic interference. The power factor of the whole machine is com ≥ ≥ 0.96 . It is not necessary to configure reactive power compensation and harmonic elimination devices to reduce the investment in construction .

4 , the inverter pulse width and commutation dead time can be flexibly adjusted to adapt to various load frequencies.

5 , high start success rate : 100% start of any load state , with a very high load adaptability: even in the state of the freezing furnace (cold furnace) can still be high power factor full load output.

6 , very high power saving effect: relative parallel resonance power saving rate of 20~30% , the reasons are as follows

(1), the turn-off loss is small. Since the series resonance belongs to the natural commutation, there is no commutation overlap angle, so there is no turn-off loss;

(2) High-voltage characteristic Series resonance belongs to voltage resonance, the inductor voltage is Q times of the output voltage , and 1500V - 4000V high voltage can be obtained without double voltage or transformer boosting . Each current of the inverter output flows through the inductive load. Relative parallel

Zhen, less current tank 2--3 times. This high voltage, low current characteristic results in a significant reduction in tank losses.

(3), low reactive power series resonance belongs to voltage resonance, DC filter adopts capacitive filtering, and the rectifier bridge is in full during normal operation.

7. Open state, the power factor of the grid reaches cos φ ≥ 0.98 or more, plus low harmonic loss, the electrical efficiency is much higher than

Parallel resonance.

8 , high compatibility: the board reserves IGBT drive interface, temperature control interface, remote control interface, online blocking protection interface. The IGBT driver board can directly drive the IGBT module; the temperature controller (or computer) can realize programmable temperature control.

9. Good environmental performance: Relative to parallel resonance, the whole machine runs smoothly and brittlely, without clutter noise, and the intermediate frequency harmonics of the power grid are extremely small.

14, which accessories affect the price of the medium frequency induction furnace?

IF furnace equipment on the market a wide range of different prices, then what is the impact frequency induction furnace price it?

Generally thyristors and resonant capacitors: The most important components on IF power supplies are thyristors and resonant capacitors. First of all, the intermediate frequency power supply equipment manufactured by various manufacturers, the quality of the selected thyristor and resonant capacitor is generally reliable, but the manufacturer chosen is different ; any manufacturer has a period of unstable quality, and the scale is large. Enterprise quality fluctuations are less. But there are still some differences in the price .

There are other small components: such as capacitors, resistors, plastic wires, water-cooled cables, water pipes, various transformers, etc., there will be cost differences in the choice.

Distribution cabinet: The regular product should be equipped with a power distribution cabinet with automatic switch ( several thousand yuan ) , which is not included in the price of low-cost equipment.

Capacitor cabinet: Low-cost equipment users need to solve the problem of capacitor placement and fixing.

Water pipe clamps: regular stainless steel water pipe clamps are used for regular equipment, and ordinary iron wire can be used for low-cost equipment.