On 2018-08-08 14:48:54
Multipurpose industrial furnace basic knowledge
The structure of submerged arc furnace is a kind of industrial furnace with huge power consumption.
It is mainly composed of furnace shell, furnace cover, furnace lining, short net, water-cooling system, smoke exhaust system, dust removal system, electrode shell, electrode pressing and releasing and lifting system, loading and unloading system, controller, burnthrough device, hydraulic system, submerged arc furnace transformer and various electrical equipment. According to the structural characteristics and working characteristics of the submerged arc furnace, 70% of the system reactance of the submerged arc furnace is generated by the short network system, which is a system with large current and the maximum current can reach tens of thousands of amperes. Therefore, the performance of the short network determines the performance of the submerged arc furnace. It is for this reason that the natural power factor of the submerged arc furnace is difficult to reach more than 0.85, most of which The natural power factor of the furnace is between 0.7 and 0.8. The lower power factor not only reduces the efficiency of the transformer and consumes a lot of idle work, but also imposes additional power penalty on the power part. At the same time, due to the manual control of the electrode and the stacking process, the power imbalance among the three phases increases, and the maximum imbalance degree can reach more than 20%, which leads to the low smelting efficiency Therefore, increasing the power factor of the short network and reducing the imbalance of the power grid become an effective means to reduce energy consumption and improve smelting efficiency.
Methods and principles In general, in order to solve the problem of low power factor of submerged arc furnace, the method of capacitor compensation is generally adopted in our country at present, usually reactive power compensation is carried out at the high-voltage end, but because the compensation at the high-voltage end can not solve the problem of three-phase balance, and because the inductive reactance of short network accounts for more than 70% of the inductive reactance of the whole system, the compensation at the high-voltage end does not reduce the system inductance of short network Improve the power factor of short network. The purpose of increasing transformer output is only meaningful to the power supply department.
Therefore, some units have taken the measures of reactive power compensation at the same time of high and low voltage on the newly built furnace to solve the above problems. The compensation at the short network end can greatly improve the power factor of the short network end and reduce the power consumption. In view of the large amount of reactive power consumption and imbalance of the short network at the low voltage side of the furnace transformer, and taking into account the effective improvement of the power factor, the technical transformation of reactive power local compensation is carried out In terms of technology, it is reliable and mature. In terms of economy, input and output are in direct proportion. In the low-pressure side of the submerged arc furnace, the local reactive power compensation for the three-phase imbalance caused by the difference between the short network reactive power consumption and its layout length has incomparable advantages in improving power factor, absorbing harmonics, increasing production and reducing consumption. However, due to the high cost and the bad working environment, the service life is greatly affected. At the same time, the reactive power compensation at the low-voltage end of the short network also brings about the increase of harmonics. Therefore, measures must be taken to suppress the third to seventh harmonics, so as to increase the investment, prolong the investment recovery cycle, at the same time, the follow-up maintenance costs are high, and the comprehensive benefits are poor. Generally, it is only applicable to new furnaces.