Research On Temperature Monitoring System Of AOD Furnace

Metallurgical industry belongs to the typical industry with high consumption,and the energy consumption takes up one third of the production cost.The promotion of metallurgical industry and the development of critical energy-saving technology are in magnificent significance in the energy consumption and economic performance.Temperature is the most important process parameters in the industry,while the real-time monitoring and controlling of temperature mean so much in smelting.The design in the paper form a temperature monitoring system with the combination of on line temperature monitoring and bottom blowing gas control of AOD furnace,so as to achieve the purpose of judging the blowing stage according to the real-time temperature and automatically adjusting the argon oxygen mixture ratio.The system plays an important role in reducing blowing time and energy consumption and improving production efficiency and the end-point hit rate.Through the comparison of the weakness and strength of the current temperature measurement methods of AOD furnace,the paper chooses infrared colorimetry to achieve the non-contact real-time temperature monitoring.The biggest advantage of infrared colorimetry is to not destroy the temperature field in furnace,and it could greatly reduce the influence of emissivity and improve the temperature measurement accuracy.Due to the non-contact temperature measurement,the paper would transform the original bottom gun as the observation port of temperature measurement.The hardware design of AOD furnace temperature monitoring includes optical path,signal processing and data remote transmission.The paper gives up the traditional double light path,and a structure of rotary modulation disk is designed to achieve the single light path to reduce the environmental interruption.Charging mode and data remote transmission are changed from wired mode to wireless mode.It could be seen from the derivation of colorimetry,the temperature measurement part directly obtains the radiation temperature instead of the real temperature.Through analysis of the characteristics of bottom blowing gas jet,isothermal melanocoele is built up and calculate the work done by the gas.Meanwhile,with the consideration of the redox reaction of bottom blowing gas and temperature change caused by blowing at room temperature in the paper,temperature compensation model is determined by functionconversion after comprehensive consideration.There is strong applicability in the temperature compensation model and it is convenient for production practice.The bottom blowing gas achieves the auto control with hierarchical structure,and the hardware includes the PLC master-slave control circuit,fieldbus,etc.According to the change characteristics of bottom blowing gas flow,traditional PID adjustment is apt to cause large overshoot,so the differential advance PID is used to achieve the gas flow.To achieve the automatic adjustment of gas flow(argon oxygen mixture ratio)in different blowing stages of AOD furnace,the paper design would combine the online temperature monitoring and the bottom blowing gas controlling.The establishment of the AOD furnace temperature monitoring system enables the upper computer to judge the blowing stage according to the real-time temperature transmitted wirelessly by the temperature measuring part.At the same time,the flow would be changed by controlling regulating valve with the preset procedure according to the set gas parameters.The temperature measurement accuracy is controlled within 0.3% through system target and calibration,and the end point temperature of each blowing stage would be confirmed.Through the experiment of the temperature monitoring system,it is gained that the system shortens the blowing time by10 minutes,and the gas consumption would be reduced accordingly.It would also increase the end-point hit rate to achieve certain effect of energy saving and emission reduction with a good economic profit.