State estimation method for vacuum degassing treatment, operation method, molten steel production method, and state estimation device for vacuum degassing treatment

Abstract

Provided are a state estimation method for vacuum degassing treatment, etc. capable of highly accurate state estimation in vacuum degassing treatment. A state estimation method for vacuum degassing treatment includes: an input step (S1, S2) of receiving input of operation track records related to manipulated variables during vacuum degassing treatment and time-series exhaust gas measured values including a flow rate of exhaust gas discharged from a vacuum degassing line that performs the vacuum degassing treatment and component concentrations of CO gas, CO2 gas, and O2 gas contained in the exhaust gas, as input information; and a calculation step (S3) of, based on the input information, classifying sources of gases that constitute the exhaust gas into a plurality of sources including blown oxygen and air entering a vacuumized region in the vacuum degassing line before or during the treatment, and estimating a constituent ratio of the classified plurality of sources.

1 . A state estimation method for vacuum degassing treatment, comprising:
 an input step of receiving input of operation track records related to manipulated variables during vacuum degassing treatment and time-series exhaust gas measured values including a flow rate of exhaust gas discharged from a vacuum degassing line that performs the vacuum degassing treatment and component concentrations of CO gas, CO 2  gas, and O 2  gas contained in the exhaust gas, as input information; and   a calculation step of, based on the input information, classifying sources of gases that constitute the exhaust gas into a plurality of sources including blown oxygen and air entering a vacuumized region in the vacuum degassing line before start of the vacuum degassing treatment or during the vacuum degassing treatment, and estimating a constituent ratio of the classified plurality of sources.   
     
     
         2 . The state estimation method for vacuum degassing treatment according to  claim 1 , wherein the calculation step includes estimating a proportion of N 2  gas in the exhaust gas from the input information and calculating a proportion of the air entering the vacuumized region based on the N 2  gas in the exhaust gas. 
     
     
         3 . The state estimation method for vacuum degassing treatment according to  claim 1 , wherein the calculation step includes estimating a dissolution rate of the blown oxygen in molten steel based on the estimated constituent ratio in a case where at least a reference time has elapsed from an end time of oxygen blowing. 
     
     
         4 . The state estimation method for vacuum degassing treatment according to  claim 3 , wherein the calculation step includes estimating an increase of an oxygen concentration in the molten steel based on the estimated dissolution rate. 
     
     
         5 . The state estimation method for vacuum degassing treatment according to  claim 1 , wherein in the calculation step, the constituent ratio is estimated in a case where a flow rate of air in the exhaust gas is determined to be constant based on a degree of vacuum of the vacuumized region. 
     
     
         6 . An operation method of operating a vacuum degassing line by executing the state estimation method for vacuum degassing treatment according to  claim 1 . 
     
     
         7 . A molten steel production method of refining molten steel in a vacuum degassing line operated by the operation method according to  claim 6  to produce refined molten steel. 
     
     
         8 . A state estimation device for vacuum degassing treatment, comprising:
 an operation information input unit configured to receive input of operation track records related to manipulated variables during vacuum degassing treatment and time-series exhaust gas measured values including a flow rate of exhaust gas discharged from a vacuum degassing line that performs the vacuum degassing treatment and component concentrations of CO gas, CO 2  gas, and O 2  gas contained in the exhaust gas, as input information; and   an exhaust gas classification calculation unit configured to, based on the input information, classify sources of gases that constitute the exhaust gas into a plurality of sources including blown oxygen and air entering a vacuumized region in the vacuum degassing line before start of the vacuum degassing treatment or during the vacuum degassing treatment, and estimate a constituent ratio of the classified plurality of sources.   
     
     
         9 . The state estimation device for vacuum degassing treatment according to  claim 8 , wherein the exhaust gas classification calculation unit is configured to estimate a proportion of N 2  gas in the exhaust gas from the input information and calculate a proportion of the air entering the vacuumized region based on the N 2  gas in the exhaust gas. 
     
     
         10 . The state estimation device for vacuum degassing treatment according to  claim 8 , comprising a blown oxygen dissolution rate calculation unit configured to estimate a dissolution rate of the blown oxygen in molten steel based on the estimated constituent ratio in a case where at least a reference time has elapsed from an end time of oxygen blowing. 
     
     
         11 . The state estimation device for vacuum degassing treatment according to  claim 10 , comprising an in-molten steel oxygen concentration increase calculation unit configured to estimate an increase of an oxygen concentration in the molten steel based on the estimated dissolution rate. 
     
     
         12 . The state estimation device for vacuum degassing treatment according to  claim 8 , wherein the exhaust gas classification calculation unit is configured to estimate the constituent ratio in a case where a flow rate of air in the exhaust gas is determined to be constant based on a degree of vacuum of the vacuumized region.