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(1) Medium frequency induction annealing equipment should use special transformers. Due to the provisions of the power supply policy, the transformers used for industrial power in China are generally S7 and S9 power transformers. The secondary voltage output is 380V, while the secondary voltage used in foreign industrial electric furnaces is The output voltage is 650~780V. It can be seen that if a special transformer dedicated to medium frequency induction annealing equipment is used to change the secondary input voltage to 650V, when the output power is constant, the output current will be reduced to 0.585 times of the original, and the copper loss will be reduced to approximately 1 /3. The further reduction of copper loss also reduces the heat generated by the transformer, so that the resistance of the copper coil does not increase due to excessive temperature. The cooling system takes away less heat, and the desk Yanyouli increases significantly. In addition, according to needs, the power supply voltage can be adjusted in a timely manner during the operation of the furnace to adjust the input power of the furnace to minimize the loss of the medium frequency induction furnace. Therefore, it is imperative to use a special transformer for medium frequency induction furnaces to increase the voltage.

In addition, limiting the no-load operation of the transformer also plays a certain role in energy saving. In practical applications, when the no-load time exceeds a few hours or production is stopped, the power should be cut off and the operation of the transformer should be stopped in time. This is more conducive to energy saving and consumption reduction of the transformer and improving the power factor.

(2) Correctly select the capacity of the medium frequency induction annealing equipment and increase the matching power. The selection of furnace capacity generally mainly considers whether the productivity of the furnace can meet the requirements of molten iron. However, for the same amount of molten iron, you can choose a single large-capacity furnace or multiple smaller-capacity furnaces, which must be analyzed and determined based on actual requirements. In situations where a large amount of molten iron is only sometimes needed for the production of large castings, it is not advisable to choose a single large-capacity furnace, but multiple furnaces of appropriate capacity should be selected under normal production requirements. In this way, it can not only improve the flexibility and reliability of the production process, solve the problem of production shutdown caused by accidents of a single large-capacity medium-frequency induction furnace, but also reduce the consumption caused by the capacity being too large to reach the rated power when smelting a small amount of molten iron. power.

The capacity of medium frequency induction annealing equipment is closely related to the technical and economic indicators of the furnace. Generally speaking, the technical and economic indicators of large-capacity furnaces are higher. This is because as the furnace capacity increases, the unit of melting cast iron increases. This is because the technical and economic indicators of the furnace are higher. The capacity increases; the unit energy loss of melting cast iron is relatively reduced. The main technical parameters and technical and economic indicators of the medium frequency coreless induction furnace are that the furnace capacity is increased from 0.15t to 5t, and the power consumption is reduced from 850kW, h/t to 660kW.h/t.

The ratio of rated power to rated capacity (that is, the power matched for melting lkg steel) is a sign that reflects the melting time and melting power consumption of medium frequency induction annealing equipment. When the ratio is large, the melting time is short, the power consumption is small, and the melting rate is high; on the contrary, the melting time is long, the power consumption is large, and the melting rate is low.

Therefore, for furnaces with the same capacity, the matching power of the medium-frequency induction heating equipment should be increased to improve the melting efficiency and reduce its power consumption.

(3) Improvement of the induction coil and water cable. The reactive power consumption of the electric power of the medium-frequency induction annealing equipment is mainly the copper loss caused by the induction coil and water cable during the operation of the electric furnace. The unit resistance has a huge impact on the copper loss. Nowadays, in order to reduce costs, some electric furnace manufacturers use mostly low-priced, high-resistance purple miscellaneous copper and No. 1 electrolytic copper as the copper raw materials for induction coils. This results in high resistance of the induction coils and water cables, and the electricity per unit time is reduced. The loss is relatively large.

High-quality and high-purity copper tubes have bright surface colors, low resistance, and good conductivity. However, inferior copper uses not all copper materials. The copper tubes are black and hard. Due to many impurities, they cannot withstand large currents and generate high heat when energized. Therefore, when selecting materials time should be distinguished.

① Increase the cross-sectional area of the induction coil and water cable. Larger cross-section copper wires and copper conductor cables can not only reduce the heat and voltage loss of the wires, but also increase the reliability of distribution lines and adapt to long-term development. It is also very beneficial from an economic point of view, increasing The investment can be recovered quickly, and users can get more benefits from long-term use.

By increasing the cross-sectional area of the induction coil and water cable, the current density can be greatly reduced, the copper consumption of the power supply line is reduced, and the working temperature of the coil and water cable is reduced, the probability of scale formation is reduced, the failure rate is reduced, and savings are achieved Reduce production costs, save energy and reduce consumption, and increase corporate economic benefits.

Taking the intermediate frequency circuit of 0.St400kw as an example, the induction coil is (outline size) 30×25×2 (mm) rectangular hollow copper tube, the number of turns is 16, the coil diameter is 560mm, the operating temperature is 80°C, and the power factor of the electric furnace is 0.1, the power consumption of the induction coil itself at 80°C is calculated to be 80.96kw. Similarly, the diameter of the water cable is 60mm and the length is 2m. The calculated power consumption at 80℃ is 0.42kw. The power consumption of these two items in the power supply line at 80°C is 81.38kw. As the cross-sectional area of the induction coil and water cable increases, the resistance changes and the energy-saving effect of the power supply line are shown in Table 3-14.

(4) Adopt new scale inhibitor and closed water cooling system.

①The impact of scale on the cooling capacity of the cooling system. Scale has a great impact on the use of copper pipes, and it directly changes the operating temperature of copper pipes. The component analysis of copper pipe scale found that scale is mainly formed by insoluble salts (CaC03, CaS04) and oxide precipitates (which may also contain anions and cations of other metals and various impurities) in the water. As the temperature of the cooling water increases, the salts in the water gradually exceed the saturation limit and precipitate to form scale with extremely poor thermal conductivity. Scale deposited on the inner wall of the coil will reduce the cross-sectional area of the water channel and block the pipe, increase the resistance of water circulation, and hinder normal heat exchange. Moreover, the thermal conductivity of scale is only 0.464~0.8W/(m.K), which is much smaller than that of copper tubes. The thermal conductivity is 320W/(m.K), the heat exchange rate is greatly reduced, and the service life of the equipment is reduced; at the same time, the heat flow distribution of the copper pipe is different, so the scale thickness is also different everywhere, and scaling occurs in the location where the local temperature of the copper pipe is too high. If it is too thick, local overheating will occur, burning coils and water cables, and even causing serious safety accidents such as electrical leakage and short circuits.

The scale on the inner wall of the coil is a layer of heat insulation. When the scale thickness is 0.5~4mm, the comprehensive heat transfer coefficient is 22%-70% lower than that without scale. The heat exchange capacity decreases, the coil temperature rises, and its resistance value increases, resulting in an increase in reactive power consumption. When the local temperature is high, there is a risk of burning the coil and water cable, so corresponding measures must be taken to remove scale.

②Adopt new scale inhibitor. The cooling water of the medium frequency induction furnace circulates in the induction coil and water cable, which contains a large number of ions. The anti-scaling devices produced by some existing methods are not very effective in inhibiting the scale of the cooling water. For example, the magnetization treatment method is greatly affected by the magnetism of the magnet. , the anti-scaling effect is unstable; electrostatic treatment has no obvious effect on the crystallization and precipitation of calcium and magnesium salts in water, and the power devices of this type of equipment are in direct contact with water, causing high-frequency pulse voltages to be generated in the water, which has a strong effect on permanent magnets. The magnetic effect reduces the anti-scaling effect; the chemical reagent method is easy to cause changes in water quality, and the electrolysis effect of the electric potential in the water also greatly reduces the anti-scaling effect; the electrostatic field method and the acoustic method also reduce the anti-scaling effect due to the interference of the electric potential in the water. To this end, a new type of anti-scaling device was developed, which uses several electrodes to form a stable capacitor bank. The charged cooling water passes through the capacitor bank to generate potential, and the capacitor bank is connected to a coil to form resonance. The parallel resonant circuit improves the electrode voltage on. The coil also short-circuits the intermediate frequency DC component to form a Faraday cage to reduce the DC potential difference and has a scale-inhibiting effect on metals such as copper and iron. The electric potential generated on the metal electrode produces Lorentz force and thermal effect on the scale in the water, thereby loosening and refining the scale crystals, suspending them in the water and regularly discharging them, thereby inhibiting crystallization and preventing the generation of scale. Using chromium zinc as an electrode, which has a more negative potential than copper and iron electrodes, can prevent corrosion of copper and iron. The use results show that the designed new anti-scaling device has better anti-scaling effect and can be cleaned once a year, which greatly reduces the generation of scale and greatly extends the service life of the sensor and water cable.

③Adopt closed circulation cooling water system. The cooling water of the sensor should be clean without impurities, the solid content should not be greater than 10mg/L, and the resistivity of the water should be greater than 2.5×10(3)Ω.cm. Since water with high hardness contains a large amount of insoluble salts, it is easy to precipitate. Precipitation forms scale, so the total hardness should not be greater than 2.8mg/L, and the sulfite and chloride content should not be greater than 50mg/L. Cooling water should be soft water with low hardness, preferably distilled water, to minimize the possibility of scale formation. A closed circulating cooling water system is used. This system has a two-level circulating water system. The outer loop is an open circulating water system, and the inner loop is a closed circulating water system. A water-water heat exchanger transfers heat during this period. The inner loop uses soft water. and distilled water, which facilitates water quality treatment, has high system reliability, low operating costs, and does not require high external loop water quality. Therefore, the service life of the sensor can be greatly improved.

④Strictly control the temperature of circulating water in the induction coil. The temperature of the circulating cooling water directly affects the operating temperature and coil resistance of the coil, and has a considerable impact on the copper loss of the induction furnace. If the inlet and outlet water temperatures are too low, circulating water cooling will consume a lot of energy and will take away heat from the furnace body, increasing power consumption; if the water temperature is too high, it will not be conducive to cooling the induction coil and increase power consumption. Therefore, choosing the cooling water temperature is an important step. The inlet and outlet water temperatures of the cooling water should be controlled at a constant temperature. The inlet water temperature is generally 20 to 300°C, and the outlet water temperature is 50°C.