Prediction Of Slab Temperature And Optimization Of Combustion In Walking Beam Furnace

Industrial furnaces are mainly distributed in metallurgy,building materials,chemical and mechanical industries in China.The total annual energy consumption of these industrial furnaces is 25% of the total energy consumption.Among them,the iron and steel industry furnace energy consumption is particularly prominent.Iron and steel industry energy consumption in the rolling system energy consumption is accounted for 15%-20%,and the rolling system energy consumption is 60%-70% of the rolling furnace energy consumption.As we all know,rolling production costs and energy consumption are closely related.Therefore,how to effectively reduce the energy consumption of the furnace has become the main direction and objectives of steel rolling.By the analysis on the present situation of heating furnace of some steel plant,we find that there are major problems: there are major problems:(1)The temperature of slabs is difficult to measure directly in the heating furnace.In order to ensure the quality of the slabs,the adjustment temperature of soaking section is often slightly higher than the design temperature.At high temperatures,the slabs prone to "over burn",resulting in economic losses.(2)Due to the fluctuation of the gas composition of the hot rolling mill,it is difficult to adjust the amount of air in real time according to the changes of its calorific value in the production,which leads to the decrease of thermal efficiency of heating furnaces and result in energy waste.In view of the above problems,the furnace can also tap the potential of energy saving with high energy saving space.Therefore,it can be optimized from the following two aspects:(1)The develop of billet temperature prediction software can improve the billet temperature control accuracy,reduce the occurrence of over-burning phenomenon and the temperature difference.The billet temperature prediction software system is a two-level optimized control system based on the first-level automation system and the third-level production information network.The control model belongs to the heating furnace process control model.The input parameters of the model are the first order signal and the third level information in the system.Software can achieve the billet heating process in the furnace related parameters tracking,analysis and process temperature field visualization and other functions.(2)The development of pre-combustion air-fuel ratio detector can optimize the combustion control,improve the accuracy of air conditioning ratio adjustment of each furnace section and reduce the billet oxidation burn rate and smoke loss.The pre-combustion air-fuel ratio detector is designed for the furnace gas pre-detection.According to the main line of sampling gas,we use the method which letting gas into the furnace before the micro-pre-combustion furnace in the full combustion,By measuring the rest oxygen in the gas of pre-combustion furnace,the detector can calculate the real-time air-fuel ratio which can provide the feed forward value for the controlling of the air-fuel ratio system.The real-time air-fuel ratio also provide the reference parameters for the air volume distribution of each furnace section and determine the air ratio settings for each section.The billet temperature prediction software integrates the first-level PLC,the second-level control system,the three-level management information network,the temperature calculation model and the air-fuel ratio optimization system into one body to realize the multi-integration control.The results show that,compared with pre-modification situation,the energy consumption of steel per ton is reduced by 0.12 GJ and the comprehensive oxidation burn rate is reduced by 0.11%.Therefore,the above measures can effectively reduce the energy consumption of the heating furnace.This paper provides a reference for further popularization of heating furnace.