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      Separators in the cement industry            
      2   Cyclones                
      2.15   Example of calculation:              
          - We want to install cyclone(s) with following data:          
            - ventilation flow rate: 160 000 m3/h            
            - temperature: 90 °C              
            - altitude: 1 000 m              
            - dust concentration: 80 gr/m3            
            - dust density: 1 600 kg/m3            
            - desired pressure loss: 150 mmWG            
            - Space restriction: maximum height of cyclone: 9 m          
            - Typical feed of the cyclone:            
          - Calculate:                
            - number of cyclones and cyclones dimensions          
            - pressure drop              
            - efficiency                
            - check if all is OK      
          - Calculation of air density:              
            - pressure (ph) at 1000m over the sea level with the formula:         
            - air density (ρf) with the formula:            
              where t is the gas temperature in  °C            
          Following the methodology:              
             1 Configuration:              
               We choose: High Efficiency Stairmand            
            2 Speed inlet:                
              We choose: 20 m/sec              
            3 Cyclones number first estimation:            
              At the moment, we choose: 1 cyclone            
              Then, the flow rate for calculation is: 160 000 m3/h or 44,444 m3/sec      
            4 Cyclone diameter calculation:            
              With the formula:              
            5 Other dimensions of the cyclone:            
            6 Pressure drop calculation:            
              With the formula:              
              Note: we selected K = 16 in this case            
            7 Check if diameter and pressure drop are OK:          
              Pressure drop is Ok because 1380,1 Pa = 140,7 mmWG < 150 mmWG      
              There is a problem with the height of the cyclone: 11,280 m > 9 m      
              Then we calculate again for 2 cyclones, Q becomes 160 000 m3/h divided by 2 = 80 000 m3/h = 22,222 m3/sec
              Using the same formula, we will have:            
              Note, the pressure drop is the same because dimension parameters are of the same configuration!  
              Now, it is OK. The cyclone have a height of 8 m < max. 9m        
            8 Efficiencies calculation:              
              where µ = 0,0765 kg/m.h              
              Then, we use the equation:            
              where Di is the average size of each interval     
              For example, we have for 0,5 µ:            
              Results for all sizes:              
              The next step is to multiply Ƞi by the partial residue of the interval (or mass),      
              and to make the sum for all sizes in order to have the total efficiency:      
    As we have a concentration of 80 gr/m3 in the inlet of the cyclone, we modify the efficiency with:
              Conclusion, the efficiency is 85,66%             
            9 Checking of the efficiency:            
              If it is not enough, we have to recalculate with a higher inlet velocity      
              A calculator is available in the tools page:        
              Important note: This methodology is only useful for a first  and rough estimation    
    All rights reserved © 2012-2016 The Cement Grinding Office