Application of High-voltage Frequency Converter in Energy-saving Technology of Main Blast Furnace Blowing in Blast Furnace

Application of High-voltage Frequency Converter in Energy Saving Technology of Main Fuel Blast Furnace of Coal Blast Furnace SHU Wei (China Metallurgical Huatian Nanjing Engineering Technology Co., Ltd., Nanjing 243005, Jiangsu, China) Consumption is the biggest problem. At the same time, the energy consumption of electricity is in daily production. As for the continuous improvement in proportion, how to do a good job in energy conservation and consumption reduction is of utmost importance.It is necessary to optimize the main exhaust fan through the application of high-voltage frequency converters and energy-saving technologies. Analysis and discussion.

However, under the premise of ensuring the normal operation performance of the main exhaust fan, the exhaust fan can still maintain a more efficient working condition. In addition, under the conditions of introducing high-voltage frequency converters, based on the flexible control of the rotation speed, the air volume can be controlled without a valve, and the level of wind power loss can be reduced in a fully open state, thereby reducing the work efficiency and ensuring the improvement of energy utilization efficiency.

2 Analysis of Energy-saving Reform of High-voltage Frequency Converter In the entire blast furnace coal-burning production system, the main exhaust fan can be said to be the core equipment that sustains the normal and stable operation of the blast furnace coal injection production system. During normal operation, the operation of the column exhaust fan can create a negative pressure state in the coal injection system of the blast furnace, which is beneficial to the centralized purification, separation, and gas emptying of the flue gas generated during the injection of coal. According to the relevant practical work experience, the main exhaust fan is a high-energy-consuming device, with large capacity and high power consumption. The adjustment of motor operating current parameters is achieved through the exhaust fan inlet damper. According to the actual experience of a certain steel plant, in the normal operation of the entire blast furnace coal injection production system, the rated current of the main exhaust fan is about 52.3 A, and the average daily electricity consumption is about 10.38 million kW. Especially for the main exhaust fan adjustment baffle area, the opening of the area is about 70%, about 30% of the energy is directly consumed in the baffle, so in time through the frequency conversion technology to achieve the main exhaust fan This transformation is crucial. This article focuses on the analysis and discussion of the application points of the high-voltage frequency converter in the coal-fired main exhaust fan of blast furnaces.

Four 10kV exhaust fan high-voltage motors are currently deployed in the blast furnace coal injection production system. In the context of the introduction of high-voltage frequency converters, the “two-run” operation scheme is required to switch between the power-frequency operation mode and the variable-frequency operation mode. From the perspective of the connection between the high-voltage frequency converter and the motor, the main improvement ideas are: In the 10kV distribution room, one high-voltage power cabinet is added to the bus line at both ends of the power distribution room, a new inverter power distribution room (bypass power supply and frequency converter in the power distribution room) is newly installed, cables are re-layed, and the cable is introduced after passing through the 10kV power distribution room. The high-voltage inverter power distribution room is introduced into the on-site pressure relief fan motors through the bypass cabinet, and during the actual operation process, on the basis of ensuring that the negative pressure conditions of the blast furnace pulverized coal injection production system are stable, all high-voltage inverters are operated. The tuyere baffle, according to the actual operating conditions, the frequency converter operating frequency adjustment, to reduce the exhaust fan power consumption purposes.

The specific improvement diagram is as shown.

1 Analysis of High-voltage Inverter Transformation Principle Under the condition of variable-frequency speed regulation, it is possible to adjust the lift speed of the motor according to the actual operating conditions, to adjust the performance curve of the exhaust fan, and to control the rated parameters of the exhaust fan according to the process requirements (eg, Shown).

From the standpoint of the similarity rule of the exhaust fan, there is a certain correlation between the air flow rate, wind pressure, power, and rotation speed before and after the shift, as shown.

Exhaust fan at n1 speed air flow / exhaust fan at n2 speed air flow = n1 speed and speed; exhaust fan at n1 speed air pressure / exhaust fan at n2 speed wind pressure = (i1 speed knows to turn through; exhaust fan power at n1 speed / exhaust fan power at n2 speed = (i1 speed, such as transfer; according to the above relationship, we can see that the exhaust fan speed is reduced to the original The 12 proportion of the parameter, that is, the rotation speed of n1 is 1/2, the corresponding power wallpaper will be reduced to 1/8 of the original power.From this point of view, the rotation speed of the exhaust fan can be reasonably controlled. In this way, the power level of the shaft is controlled to achieve energy-saving efficiency, and at the same time, as shown in the high-voltage frequency converter efficiency curve diagram, it can be seen that the efficiency values ​​corresponding to the 1-bit and Q2-points are basically the same among the (nQ) efficiency curves. In other words, when the speed is reduced, the rated operating parameters corresponding to the exhaust fan will have a decreasing trend, but the efficiency will not be reduced, and may even be improved.Therefore, Nong Xie MlM Jiu Zhan p Ti Mtronie Wei: The energy-saving technology of the high-voltage frequency converter in the main exhaust fan of the blast furnace coal used in the bypass cabinet, a total of 5 sets of high-voltage isolation switch, and corresponding to equipped with 10 contactors.In the M1 motor with high-voltage inverter In the case of mode operation, the K0 disconnector and the K1 isolating switch power supply are in the closed state, the KM6 contactor coil power supply is also in the closed state, and the power supply of the 1 circuit frequency cabinet breaker is in the disconnected state.At the same time, the bypass cabinet and the upper stage high voltage The circuit breaker DL maintains the interlocking state.In the case of the high-voltage circuit breaker DL closing, the isolation switch must not be operated to avoid adverse effects on the system operation safety due to the arcing problem.

3 Analysis of Energy-saving Benefits The calculation of the actual power consumption of the exhaust fan under the power frequency condition is as follows: the power frequency status power consumption is taken as 1.732 x actual working current x rated power x power factor. With reference to specific conditions, the calculated value of the power frequency power consumption is 710.0 kW. At the same time, according to the data provided by the blast furnace coal-burning main exhaust fan operation site, the main throttle exhaust fan under normal operating conditions, the throttle opening The value is 70%. Combined with industry experience, the ratio of the actual flow to the rated flow under the normal operation of the main exhaust fan is 85%. Based on the above parameters, the power ratio is taken before and after the high-voltage conversion. Flow ratio 3 / frequency conversion device efficiency (take a constant value of 0.96 / exhaust fan efficiency correction coefficient (take a constant value of 0.9. Based on the above conditions, that in the high voltage conversion based on the above, to achieve the same conditions, the motor consumes power on the side of the network The value is 565.0 kW. Therefore, it can be calculated that, compared with before the frequency conversion transformation, the power saving amount under the adjusted state of the modified frequency exhaust fan of the exhaust fan has reached 145.0 kW (710.0 kW-565.0 kW). After the introduction of the high-voltage frequency converter, the energy-saving rate of the exhaust fan has reached about 20.42%, and under the condition of full-load operation, assuming a low price of 0.4 yuan/kW, the electricity cost for one year of operation can be saved at about 2.378 billion yuan. Benefit outstanding.

4 Conclusions Based on the experience of transformation and related empirical parameter analysis, we know that in the context of the introduction of high-frequency transformers, high-frequency variable-frequency speed control technology can be applied to realize frequency conversion control of the coal-fired main exhaust fan of blast furnaces. Under the operating background of the high-voltage frequency converter, according to the actual working conditions, the variable load adjustment of the supply air volume is realized. After the frequency conversion transformation, the rotation speed can be adjusted according to the on-site flow rate and pressure changes to achieve the purpose of controlling the power consumption, reducing the maintenance amount, prolonging the service life of the fan, and reasonably controlling the production cost. This paper discusses the main exhaust of high-voltage frequency converters in the coal injection of blast furnaces. On the basis of the application points in the wind turbine, it was demonstrated that the energy-saving benefits after the introduction of high-voltage frequency converters can be expected to cause the attention and attention of staff in the same industry.