Method for detecting air flow distribution in blast furnace

Abstract

A method for detecting an air flow distribution in a blast furnace, taking into account a heat exchange between an air flow and a solid material bed and the effect of a distribution of a material layer structure in a radial direction of a blast furnace on the radial air permeability of blast furnace, which affects a mode of air flow distribution, wherein the distribution of the air flow and the radial material layer structure of the blast furnace can be calculated by combining a cross-shaped temperature-measuring gun and other main blast furnace operating parameters. According to the detection method, a blast furnace operator can timely and accurately infer, from a change in a current radial air flow temperature distribution, the direction of change of the distribution of the air flow and the radial material layer structure at a furnace throat portion.

1 . A method for detecting gas flow distribution in blast furnace, wherein the method comprises the following steps:
 a) dividing a cross-section of blast furnace throat according to the number and positions of temperature-measuring devices at the top of blast furnace to obtain N temperature-measuring device regions; wherein the N is a natural number greater than or equal to 1;   b) obtaining a solid-gas heat flow ratio of each of the temperature-measuring device regions according to temperature values from each of the temperature-measuring devices and a balance equation between a heat flow rate of gas and a heat flow rate of solid in a lump zone of blast furnace below corresponding temperature-measuring device region;   c) establishing a function relation between a thickness ratio of burden material layers and a gas flow rate within each of the temperature-measuring device regions according to the solid-gas heat flow ratio of each of the temperature-measuring device regions;   d) obtaining the thickness ratio of burden material layers within each of the temperature-measuring device regions according to pressure drop per unit length of burden layer, particle size distribution of the burden materials and gas resistance equation of each lump zone of blast furnace, and obtaining the gas flow rate of each of the temperature-measuring device regions according to the thickness ratio of burden material layers within each of the temperature-measuring device region above and the function relation between the thickness ratio of burden material layers and the gas flow rate within each of the temperature-measuring device region obtained in the above step c); and   e) plotting the region distribution of each of the temperature-measuring device regions and the gas flow rate thereof, to obtain a detection result of the gas distribution.   
     
     
         2 . The method according to  claim 1 , wherein the method further comprises, after step d):
 d#) obtaining by calculation an average thickness ratio of burden material layers according to the thickness ratio of burden material layers within each of the temperature-measuring device regions, and obtaining a total volume of gas flow passing through the temperature-measuring device regions according to gas flow rate in each of the temperature-measuring device regions, to further obtain a total heat of gas flow passing through the temperature-measuring device regions;   comparing the average thickness ratio of burden material layers obtained in the above step with a theoretical average thickness ratio of burden material layers, to obtain an error σ 1 ; comparing the total volume of gas flow passing through the temperature-measuring device regions obtained in the above step with a theoretical total volume of furnace top gas flow, to obtain an error σ 2 ; and comparing the total heat of gas flow passing through the temperature-measuring device regions with a theoretical total heat of furnace top gas flow, to obtain an error σ 3 ;   modifying the pressure drop per unit length of burden layer and the particle size distribution of burden materials if one or more of the errors σ 1 , σ 2 , and σ 3  has a value greater than or equal to 5%, and performing the step d) again, until the value of each of the errors σ 1 , σ 2 , and σ 3  is less than 5%; and   performing the above step e) if the value of each of the errors σ 1 , σ 2 , and σ 3  is less than 5%.   
     
     
         3 . The method according to  claim 2 , wherein the burden materials are ore and coke, and the theoretical average thickness ratio of burden material layers is calculated based on the formula: X 0 =[L O /(L O +L C )] 0 , wherein Lo is a thickness of ore layer, and Lc is a thickness of coke layer. 
     
     
         4 . The method according to  claim 2 , wherein the thickness ratio of burden material layers within each of the temperature-measuring device regions is x i , the average thickness ratio of burden material layers is X t , and the average thickness ratio of burden material layers is calculated based on the formula: 
       
         
           
             
               
                 X 
                 t 
               
               = 
               
                 
                   ∑ 
                   
                     i 
                     = 
                     1 
                   
                   N 
                 
                  
                 
                   
                     
                       x 
                       i 
                     
                     · 
                     
                       S 
                       i 
                     
                   
                    
                   
                     / 
                   
                    
                   A 
                 
               
             
           
         
         wherein S i  is an area of each of the temperature-measuring device regions, and A is a total area of the cross-section of the blast furnace throat. 
       
     
     
         5 . The method according to  claim 1 , wherein the burden materials are ore and coke, the thickness ratio of burden material layers in the temperature-measuring device region is x i , the gas flow rate in the temperature-measuring device region is u i , then the function relation between the thickness ratio of burden material layers and the gas flow rate in the temperature-measuring device region is: 
       
         
           
             
               
                 x 
                 i 
               
               = 
               
                 
                   
                     
                       
                         ( 
                         
                           
                             
                               C 
                               s 
                             
                              
                             
                               G 
                               s 
                             
                           
                           
                             
                               C 
                               g 
                             
                              
                             
                               G 
                               g 
                             
                           
                         
                         ) 
                       
                       i 
                     
                     · 
                     
                       
                         
                           
                             ( 
                             
                               C 
                               g 
                             
                             ) 
                           
                           i 
                         
                          
                         
                           
                             ( 
                             
                               ρ 
                               g 
                             
                             ) 
                           
                           i 
                         
                       
                       
                         
                           
                             C 
                             s 
                           
                            
                           
                             ( 
                             
                               
                                 ρ 
                                 O 
                               
                               - 
                               
                                 ρ 
                                 C 
                               
                             
                             ) 
                           
                         
                          
                         
                           v 
                           i 
                         
                       
                     
                   
                    
                   
                     u 
                     i 
                   
                 
                 - 
                 
                   
                     ρ 
                     C 
                   
                   
                     ( 
                     
                       
                         ρ 
                         O 
                       
                       - 
                       
                         ρ 
                         C 
                       
                     
                     ) 
                   
                 
               
             
           
         
         wherein C g  is a specific heat of gas, C s  is a specific heat of solid, G g  is a flow rate of gas, G s  is a flow rate of solid, ρ is a density of furnace top gas, v is a descent velocity of a solid burden bed, ρ O  is a density of ore, and ρ C  is a density of coke. 
       
     
     
         6 . The method according to  claim 1 , wherein the gas resistance equation of each lump zone of blast furnace is: 
       
         
           
             
               
                 
                   ( 
                   
                     
                       Δ 
                        
                       
                           
                       
                        
                       P 
                     
                     L 
                   
                   ) 
                 
                 i 
               
               = 
               
                 
                   [ 
                   
                     
                       
                         k 
                         1 
                         ⋆ 
                       
                        
                       
                         
                           
                             
                               ( 
                               
                                 1 
                                 - 
                                 ɛ 
                               
                               ) 
                             
                             2 
                           
                           
                             
                               D 
                               p 
                               2 
                             
                              
                             
                               ɛ 
                               3 
                             
                           
                         
                         · 
                         μ 
                       
                        
                       
                           
                       
                        
                       u 
                     
                     + 
                     
                       
                         k 
                         2 
                         ⋆ 
                       
                        
                       
                         
                           ( 
                           
                             1 
                             - 
                             ɛ 
                           
                           ) 
                         
                         
                           
                             D 
                             p 
                           
                            
                           
                             ɛ 
                             3 
                           
                         
                       
                        
                       ρ 
                        
                       
                           
                       
                        
                       
                         u 
                         2 
                       
                     
                   
                   ] 
                 
                 i 
               
             
           
         
         wherein, k 1 * is a viscous resistance coefficient, k 2 * is an inertia resistance coefficient, ΔP/L is a pressure drop per unit length, ε is a burden bed porosity, D p  is an average particle diameter of particles, μ is a gas viscosity, u is a gas flow rate, and ρ is a gas density; 
         the viscous resistance coefficient and the inertia resistance coefficient of the coke are respectively:
     k   1 *=450·( D   p ·10) 0.84   ,k   2 *=2.2·( D   p ·10) 0.04 ;
 
 
         the viscous resistance coefficient and the inertia resistance coefficient of the ore are respectively:
     k   1 *=260·( D   p ·10) 0.84   ,k   2 *=1.2·( D   p ·10) 0.04 .
 
 
       
     
     
         7 . The method according to  claim 1 , wherein the pressure drop per unit length of burden layer in each lump zone of blast furnace is equal,
 the pressure drop per unit length of burden layer in each lump zone of blast furnace is equal to the sum of a pressure drop per unit length of coke layer and a pressure drop per unit length of ore layer in said lump zone of blast furnace.   
     
     
         8 . The method according to  claim 1 , wherein the temperature-measuring device is a cross-shaped temperature-measuring gun. 
     
     
         9 . A system for detecting gas flow distribution in blast furnace, wherein the system comprises:
 a division unit, configured to divide a cross-section of blast furnace throat according to the number and positions of temperature-measuring devices at the top of blast furnace to obtain N temperature-measuring device regions; wherein the N is a natural number greater than or equal to 1;   a first attainment unit, configured to obtain a solid-gas heat flow ratio of each of the temperature-measuring device regions according to temperature values from each of the temperature-measuring devices and a balance equation between a heat flow rate of gas and a heat flow rate of solid in a lump zone of blast furnace below corresponding temperature-measuring device region;   an establishment unit, configured to establish a function relation between a thickness ratio of burden material layers and a gas flow rate within each of the temperature-measuring device regions according to the solid-gas heat flow ratio of each of the temperature-measuring device regions;   a second attainment unit, configured to obtain the thickness ratio of burden material layers within each of the temperature-measuring device regions according to pressure drop per unit length of burden layer, particle size distribution of the burden materials and gas resistance equation of each lump zone of blast furnace, and to obtain the gas flow rate of each of the temperature-measuring device regions according to the thickness ratio of burden material layers within each of the temperature-measuring device region above and the function relation between the thickness ratio of burden material layers and the gas flow rate within each of the temperature-measuring device region obtained in the above step c); and   a result unit, configured to plot the above distribution of each of the temperature-measuring device regions and the gas flow rate thereof, to obtain a detection result of the gas distribution.   
     
     
         10 . The detection system according to  claim 9 , wherein the system further comprises:
 a verification unit, configured to obtain by calculation an average thickness ratio of burden material layers according to the thickness ratio of burden material layers within each of the temperature-measuring device regions, and to obtain a total volume of gas flow passing through the temperature-measuring device regions according to gas flow rate in each of the temperature-measuring device regions, to further obtain a total heat of gas flow passing through the temperature-measuring device regions;   wherein the average thickness ratio of burden material layers obtained in the above step is compared with a theoretical average thickness ratio of burden material layers, to obtain an error σ 1 ; the total volume of gas flow passing through the temperature-measuring device regions obtained in the above step is compared with a theoretical total volume of furnace top gas flow, to obtain an error σ 2 ; and the total heat of gas flow passing through the temperature-measuring device regions is compared with a theoretical total heat of furnace top gas flow, to obtain an error σ 3 ;   the pressure drop per unit length of burden layer and the particle size distribution of burden materials are modified if one or more of the errors σ 1 , σ 2 , and σ 3  has a value greater than or equal to 5%, and the step d) is performed again, until the value of each of the errors σ 1 , σ 2 , and σ 3  is less than 5%; and   the step e) is performed in the case that the value of each of the errors σ 1 , σ 2 , and σ 3  is less than 5%.