Instructions

1. This article contains a series of steps to feed the data to the flowsheet, run the simulation, interpret the results
   
2. User can either follow the series of steps mentioned in the article or download the ProTreat file attached to this article, review the inputs and run the simulation  
   

Simulation Set Up

Objective

Inputs

1. Components:  Carbon dioxide, Hydrogen Sulphide, Methane, MDEA, DEA, Water

Stream Information (Feed Gas)

1. Set up a conventional absorber & regenerator loop in ProTreat as shown in the flowsheet
2. Inputs taken for the exercise 
1. Gas flow rate: 2,000 lbmol/hr
2. Temperature : 94 °F
3. Pressure : 500 psig
4. Component composition: (CO₂: 10%, H₂S: 10%, Methane: 80%, All in mol%, water %saturation: 100) 
   

Absorber Inputs

1. Tray type: Generic valve trays 
2. Number of trays: 20
3. Tray spacing: 2 feet
4. Number of passes: 1
5. Weir height: 2 inch
6. Foam derating Factor: 0.8 
7. Vapor flood & Downcomer flood: 70%
8. Pressure>>set pressure by feed stream: 1
9. Connect streams appropriately to absorber based on the flowsheet

Pump-1 Input

1. Pump>>Outlet Pressure>>500 psig  
2. Efficiency>>75%
   

Heat X-1 Input

1. HeatX-1>> Heat transfer>> Thermal spec>> Shell outlet temperature >>215 °F
2. Apply LMTD correction factor>>Let ProTreat calculate
   

Regenerator Inputs

1. Select the check boxes that the column has reboiler and condenser, and has reflux to column (% return is 100%)
2. Tray type: Generic valve trays 
3. Number of trays: 20
4. Tray spacing: 2 feet
5. Number of passes: 1
6. Weir height: 2 inch
7. Foam derating factor: 0.8 
8. Vapor flood & Downcomer Flood: 70%
9. Pressure>>specify pressure>>15 psig above top tray
10. Connect streams appropriately to absorber based on the flowsheet
11. Connect feed stream to the top tray in regenerator
12. Condenser/Reboiler>>Condenser>> Temperature>>110 °F
13. Condenser>>Pressure Drop>>0 psi
14. Reboiler>> Vapor return line pressure drop>>0 psi     
15. Reboiler Steam Flow Ratio>>1.1 lb steam /std US gallon
16. Basis liquid stream for calculation>>Pump inlet stream
17. Pressure>>50 psig 
    

Cooler Input

1. Cooler>>Duty>>Outlet temperature>>110 °F

Amine Inputs in Control Block-1

1. Stream Flow rate: 295 USGPM
2. Composition: 40 wt. % MDEA, 10wt.% DEA
3. Select method for calculating make up as “Control Block In/ Out Streams”
   

Stream Information (Recycle block)

1. Select the preferred components and feed the input data in the perspective recycle block
2. Recycle flow rate: 295 USGPM
3. Temperature : 110 °F
4. Pressure : 500 psig
5. Component composition: (CO₂: 0.01 Loading, MDEA: 40 wt.%, H₂S: 0.001)
6. Select water specification as “is remainder (solvent streams only)”

Run Simulation

1. Run simulation at base case i.e., solvent composition at 10 wt.% DEA, 40 wt.% MDEA
   
2. Note the concentrations of both CO₂ and H₂S in the treated gas 
   
3. Repeat the same process by increasing DEA wt.% with a step size of 10% in such a way that the total amine concentration in the solvent sums up to give a total amine weight percentage of 50
   
4. Run the simulation for all the cases

Results & Discussion

Output

1. CO₂ mol%, H₂S in ppmv for the treated gas on varying %DEA 

Graphical representation of CO₂ and H₂S concentration vs DEA wt.% in blended amine

---

Interpretation-1

1. From the previous slide we observed that the optimum DEA weight percentage that meets both the target removal spec of H₂S and CO₂ is 15 wt.% DEA
2. At 15 wt.% DEA and 35 wt.% MDEA let us study the flow sensitivity
   

Graphical representation of CO₂ and H₂S concentration vs solvent rate

1. Change circulation rate from 200 to 300 USGPM in a step size of 10 USGPM and run the simulation
2.  Analyse the results
   

Interpretation-2

1. Flow sensitivity was found at 15 wt.% DEA + 35 wt.% MDEA
2. From the above graph spec is met above 278 USGPM 
3. Rate based simulation can clearly help you optimize and determine margins better

Something to think about

1. Does activators in blended amines have a role in increasing the overall viscosity of the solvent?
2. For more detailed information about the blended amines visit ___________________