Energy-saving retrofit of induction coil and water cable part of medium frequency furnace
The reactive power consumption of the IF induction electric furnace is mainly caused by the copper loss caused by the induction coil and the water-cooled cable during the operation of the electric furnace. The influence of the unit resistance on the copper loss is very large. Nowadays, in order to reduce the cost of some electric furnace production plants, the copper raw materials of the induction coils are mostly made of low-cost copper with high resistance value instead of electrolytic copper No. 1 with low resistance value , resulting in high resistance of the induction coil and the water wire. The time electrical loss is relatively large.
High-quality high-purity copper tube , the surface color is bright , the resistance is low , the conductivity is good , and the inferior copper is not entirely made of copper material , the copper tube is black and hard , because the impurities can not withstand large current , thepower generation heat is high , the material selection Time should be distinguished .
Large induction coil, water cable cross-sectional area
Copper wire and copper conductor cable larger cross-section, which will not only reduce heat loss and voltage wire, but also increase the reliability of power distribution lines, and adapt to long-term development, but also from an economic point of view is also very good,increase The investment can be quickly recovered , and users can get more benefits in long-term use.
By increasing the induction coil, water cross-sectional area of the cable, which can greatly reduce the current density, the supply line to reduce copper loss and helps reduce the coil, the cable work of the water temperature, reducing the chance of scale formation, reduce the failure rate, to save Production costs , energy saving , and increase the economic benefits of enterprises.
Take 0.5 ton 400 kW intermediate frequency furnace as an example , the induction coil is ( outer size ) 30x25x2 (mm) rectangular hollow copper tube , the number of turns is 16, the coil diameter is 560mm. The working temperature is 80 °C , the electric furnace power factor is 0.1,calculated by The induction coil itself consumes 80.96 kW at 80 °C . Similarly , the water cable has a diameter of 60 mm and a length of 2 m. The calculated power consumption at 80 °C is 0.42 kW . The power consumption at 80 °C is 8l.38kW . As the cross-sectional area of the induction coil and water cable increases , the resistance change and the energy-saving effect of the power supply line are shown in Table 2 .
Seen from Table 2, if the induction coil is increased wall thickness 3mm, the diameter of the cable increases water 3cm, the induction coil portion of the cable with the water consumption per hour 29.l6kW, reflecting an increase 64.17% saving, energy-saving 52.22kW per hoursignificant energy savings.
Second, reduce the operating temperature of the induction coil and water cable
When the induction furnace is smelting, the induction coil and the water cable work up . Because of the temperature coefficient of resistance of copper , the resistivity increases , the resistance becomes larger , and the power consumption increases . The mathematical equation is as follows :
By the formula (1) obtained, copper work coil temperature is increased by 10 ℃, 4% increase in resistance, the power consumption is also increased by 4%. When the operating temperature of the induction coil is reduced from 80 °C to 50 °C , the power loss is reduced by 12%, which is a considerable loss for a higher power medium frequency induction furnace. Therefore, an effective cooling system is used to efficiently reduce the temperature of the power supply line, and to avoid the formation of a temperature increase - > resistance rise - > temperature rise, this vicious cycle , reducing line losses.
Three copper coil surface insulation treatment
The surface insulation treatment of the copper coil can not be ignored. Good insulation treatment can prevent the coil from being ignited. In severe cases, it can even cause the copper tube to break down or burn the bad consequences of the intermediate frequency power supply. Preventing coil ignition itself can also effectively reduce power consumption, shorten smelting time, and improve production efficiency. In comparison with the test results carried out in a 10 ton furnace, after six months of operation, the well-insulated coils have a 10% savings in power consumption compared to untreated coils .
Unfortunately, the surface insulation of copper coils has not received enough attention in the industry. Some manufacturers do not insulate the coils at all in order to save costs, or just buy cheap insulating varnish for spraying on the market, just to Guaranteed that the sale is a surface aesthetic effect.
Good surface insulation needs to use high temperature, waterproof and high voltage resistant insulating varnish. At present, TSC-L ultra-high temperature insulating varnish and APC-H+ high temperature arc-resistant varnish are better. The two lacquers are aimed at Developed by the use characteristics of the intermediate frequency electric furnace, the two have some differences in temperature resistance and compression resistance, and need to be carefully selected according to their actual use.
