1.Overview
The concentrate powder after the beneficiation of the lean ore and the rich ore powder produced in the processing process can not directly enter the blast furnace smelting, and must be rebuilt again. Common block-making methods include sintering and pellets. A considerable amount of flux and fuel are added into the powder iron material, and ignited on the sintering machine. With the help of the high temperature effect of fuel combustion, a certain amount of liquid phase is produced, and other unmelted sintering particles are bonded up and become multi-empty mass ore after cooling. Pellet production is a method of using unsintered concentrate powder and other iron-containing powder blocks.
2.Implementation plans
The transformation scheme is as follows: keep the existing high voltage start cabinet, add the medium voltage drive and manual bypass cabinet between the start cabinet and the motor. The start cabinet serves as the start cabinet when the motor power frequency operation, and also the incoming cabinet of the frequency converter. Manual bypass cabinet is used for switching between frequency conversion and power frequency. In the maintenance of frequency conversion system or failure, the motor is put into the power frequency power grid for operation to ensure that the production is not affected. The primary wiring is shown in Figure 1-1.
Figure 1-1 The manual bypass cabinet
Figure 1-1 In the bypass cabinet, there are 3 high voltage isolating switches. In order to ensure that the power is not sent back to the output end of the frequency converter, K2 and K3 adopt electromagnetic interlock operating mechanism to realize electromagnetic interlock. When K1 and K3 are closed and K2 is disconnected, the motor operates by frequency; when K1 and K3 are disconnected and K2 is closed, the frequency converter is isolated from high voltage for repair, maintenance and debugging.
The bypass cabinet must be linked with the superior high voltage circuit breaker DL. When DL closes, the bypass isolation switch is not allowed to prevent arc pulling and ensure the safety of operators and equipment.
Fault switch: connect the "high voltage break" signal of the frequency converter with the "frequency conversion input" signal of the bypass cabinet, and connect in parallel with the high voltage switch switch circuit. In the inverter input state, when the inverter fails, break the high voltage input of the inverter is invalid.
Protection: keep the original protection of the motor and its setting value unchanged.
3.Application advantage
Ring air cooler main function is to cool red hot sinter to below 100℃, because the Baotou steel group solid mine is located in the north, the four seasons temperature difference is obvious, the operation of ring air cooler management should also with the help of natural weather temperature, such as winter due to the environmental temperature is low, sinter has the appropriate temperature conveying belt, so the tape machine cold ore temperature can be controlled in about 100℃, no. 1 blower can stop running in winter, 2,3,4 fan can adjust the fan speed according to the need. No.1 fan can start and stop in turn according to the weather conditions.
When the power frequency of the ring cold air machine is running, the power factor is 0.8, the power supply voltage is 10.05kV, and the power consumption per hour is calculated as 1378.6kW. During the frequency conversion operation of the loop air cooler, the power factor is 0.97, and the input voltage of the frequency conversion is 10.05 kV, and the calculated power consumption per hour is 626.41 kW. When the ring air cooler is running with frequency conversion, the power is saved by 752.19kW per hour.300d per year, 24h per day, then annual power saving: 752.19kW 24h 300 d = 5415,768 million kWh. Thus, the effect of electricity saving is still very obvious.
