The electric furnace is the main power-consuming equipment in the foundry. In the engineering design, whether the electric furnace is selected properly will directly affect the future operating costs and affect the factory efficiency. The intermediate frequency electric furnace can be divided into "one for one" and "one for two" from the relationship between power supply and electric furnace configuration. One for one” is a single power supply with a single furnace body, which is mainly suitable for the furnaces in the electric furnace to be quickly emptied after melting, and then re-feeding and melting, or the operation is not frequent, for small capacity and lower power electric furnace It is more suitable; it can also be a set of power supply. The two furnaces are switched by mechanical switches, one furnace is smelting, and the other is poured or repaired.
With the development of scale, mechanization, automation and precision in the foundry industry, the electric furnace melting scheme of “one for two intermediate frequency furnaces” is often used, that is, one power supply supplies power to two furnaces, and double furnace body and dual power supply are adopted. power supply. The double furnace body makes one furnace body smelt while the other furnace body heats and adjusts the composition of the iron liquid; the double power supply continuously supplies electric power to the two furnace bodies, and can be distributed and delivered to the two in an arbitrary ratio within the range of its rated power. The power required for the furnace body. A dual-supply variable frequency power supply can realize the effect of two single-supply variable frequency power supplies, but only one transformer and one high-voltage power supply line are needed; the equipment utilization rate of the variable frequency power supply can be nearly 100%; no mechanical or electronic switch can be realized. The power supply and distribution of power to the two furnaces is simple and easy to operate, and the failure rate is low. When one furnace body is used as a furnace lining, the other furnace body can be normally melted. When selecting an electric furnace, first determine the electric furnace productivity and power supply. The determination of the productivity of the electric furnace depends on many process factors, such as the annual production task, the demand for molten iron for different castings, the balance of molten iron in multiple molding lines, etc. . In the mechanized molding line workshop, in order to give full play to the production capacity of the molding line and comprehensively consider the needs of different products, the electric furnace productivity should be able to meet the demand for molten iron in the molding line. Due to the large power density configuration of the intermediate frequency electric furnace, when the power density is more than 600 kW/t, the melting capacity of the intermediate frequency electric furnace can basically be less than 1 h per furnace. The power of the electric furnace is basically determined by the productivity. According to the amount of molten iron required for the hourly production of the casting car, the energy consumption per ton of molten iron is also considered to add the auxiliary time of adding ingredients, slag, sampling and other tests to calculate the power of the electric tomb that meets the production demand. The power density of induction melting furnaces is typically configured to 600 kW/t 800 kW/t. The power density of domestically produced medium frequency induction melting furnaces is generally configured to be around 700 kW/t. Here, an electric furnace equipped with a 4 000 kW power supply is used as an example to estimate the amount of iron that can be supplied in hours, if a manufacturer's electricity is selected.
The energy consumption per ton of molten iron in the furnace is 500 kW·h/t. Due to the influence of adding ingredients, slag, sampling and other tests, the input time of the power supply is reduced, the heat loss of the electric furnace itself, etc., and the total efficiency of the electric furnace is 0. 72 to 0.75, taking 0.75, the productivity of the electric furnace is 4 000 × 0.75 / 500 = 6 t / h.
