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CARBON DIOXIDE STRIPPING: -Fundamentals -Computer Design Model

CARBON DIOXIDE STRIPPING: -Fundamentals -Computer Design Model. OVERVIEW. CO 2 Production CO 2 Toxicity Carbonate System Gas Transfer Stripping Options. OVERVIEW. Basic Design Parameters Design Example Two Methods Facility Considerations Computer Design Model Model Results.

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CARBON DIOXIDE STRIPPING: -Fundamentals -Computer Design Model

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  1. CARBON DIOXIDE STRIPPING:-Fundamentals-Computer Design Model Recirculating Aquaculture Systems Short Course

  2. OVERVIEW • CO2 Production • CO2 Toxicity • Carbonate System • Gas Transfer • Stripping Options Recirculating Aquaculture Systems Short Course

  3. OVERVIEW • Basic Design Parameters • Design Example • Two Methods • Facility Considerations • Computer Design Model • Model Results Recirculating Aquaculture Systems Short Course

  4. CO2 PRODUCTION • Molar basis • 1 mole of CO2 is produced for every1 mole O2 consumed • Mass basis • 1.38 g of CO2 is produced for every1 g O2 consumed Recirculating Aquaculture Systems Short Course

  5. CO2 TOXICITY • Bohr Effect • Elevated CO2 levels decrease the ability of hemoglobin to transport oxygen • Root Effect • Elevated CO2 levels decrease the maximum oxygen binding capacity of the blood Recirculating Aquaculture Systems Short Course

  6. CO2 TOXICITY • Safe levels depend on species, developmental stage, and water quality: Recirculating Aquaculture Systems Short Course

  7. CARBONATE SYSTEM • CO2 = Carbon Dioxide • H2CO3 = Carbonic Acid • HCO3– = Bicarbonate • CO3= = Carbonate Recirculating Aquaculture Systems Short Course

  8. CARBONATE SYSTEM CO2 + H2OÛ H2CO3 K0 [H2CO3*] = [CO2] + [H2CO3] H2CO3* Û HCO3– + H+ K1 HCO3–Û CO3= + H+ K2 Recirculating Aquaculture Systems Short Course

  9. CARBONATE SYSTEM • Total Carbonate Carbon (mol/L) CT = [H2CO3*] + [HCO3–] + [CO3=] • Alkalinity (eqv/L) Alk = [HCO3–] + 2[CO3=] + [OH–] – [H+] Recirculating Aquaculture Systems Short Course

  10. CARBONATE SYSTEM Alkalinity 100 mg/L CO2 (mg/L) pH Recirculating Aquaculture Systems Short Course

  11. GAS TRANSFER • Air is contacted with water and dissolved gases approach equilibrium with the atmospheric partial pressures air CO2 O2 water air N2 air Recirculating Aquaculture Systems Short Course

  12. GAS TRANSFER • Driving force for CO2 transfer out of water is the concentration gradient: DF = Bulk _ Saturation Concentration Concentration Recirculating Aquaculture Systems Short Course

  13. GAS TRANSFER • Dissolved Gas Solubility at 15oC: Recirculating Aquaculture Systems Short Course

  14. STRIPPING OPTIONS • Stripping Tower Influent water Water Distribution Effluent Air Water Breakup Influent Air Effluent water Recirculating Aquaculture Systems Short Course

  15. STRIPPING OPTIONS • Stripping Tower Design Parameters: Recirculating Aquaculture Systems Short Course

  16. STRIPPING OPTIONS • Surface Aerator CO2 Surface Aerator Recirculating Aquaculture Systems Short Course

  17. STRIPPING OPTIONS • Surface Aerator Design Parameters: Recirculating Aquaculture Systems Short Course

  18. STRIPPING OPTIONS • Diffused Aerator CO2 Air Diffusers Recirculating Aquaculture Systems Short Course

  19. STRIPPING OPTIONS • Diffused Aerator Design Parameters: Recirculating Aquaculture Systems Short Course

  20. DESIGN EXAMPLE • Stripping Tower (ST) effluent water makeup water culture tank treated flow ST Recirculating Aquaculture Systems Short Course

  21. DESIGN EXAMPLE • Stripping Tower (ST) Qm, Cm, Alkm Qm, Ce, Alke P culture tank Qr, Cr, Alkr Qr, Ce, Alke ST Recirculating Aquaculture Systems Short Course

  22. DESIGN EXAMPLE • Culture Tank • Volume = 50,000 L • Qm = 10% of the volume per day • Feed = 100 kg per day Recirculating Aquaculture Systems Short Course

  23. DESIGN EXAMPLE • Culture Tank Water Quality CO2 = 40 mg/L Alkalinity = 100 mg/L • Makeup Water Quality Qm = 3.5 Lpm CO2 = 5 mg/L Alkalinity = 100 mg/L Recirculating Aquaculture Systems Short Course

  24. DESIGN EXAMPLE • CO2 Mass Balance: IN + PRODUCED = OUT + STRIPPED QmCm + P = QmCe + Qr(Ce – Cr) Qr = {Qm(Cm – Ce) + P}/(Ce – Cr) Recirculating Aquaculture Systems Short Course

  25. DESIGN EXAMPLE • CO2 Produced: P = (F)(OCR)(CPR) P = (100 kg/day)(0.4)(1.38) P = 55.2 kg CO2/day P = 38,333 mg CO2/min Recirculating Aquaculture Systems Short Course

  26. DESIGN EXAMPLE • Stripping Tower: • Hydraulic Loading = 20 kg/m2s • 5.1 cm NORPAC Packing • Influent Stripping Gas CO2 = 1,000 ppm • Influent CO2 = 40 mg/L • Influent Alkalinity = 100 mg/L Recirculating Aquaculture Systems Short Course

  27. DESIGN EXAMPLE % CO2 Removal Packing Height (m) Recirculating Aquaculture Systems Short Course

  28. DESIGN EXAMPLE • Height = 1 m • G:L = 10 • Removal Efficiency = 66% • Effluent CO2 from Stripper: Cr = Ce(1 – efficiency) Cr = 40(1 – 0.66) Cr = 13.6 mg/L Recirculating Aquaculture Systems Short Course

  29. DESIGN EXAMPLE • Required Flowrate: Qr = {Qm(Cm – Ce) + P}/(Ce – Cr) Qr = {3.5(5 – 40) + 38,333}/(40 – 13.6) Qr = 1,447 Lpm Qr = 382 gpm Qr = 24.1 L/s Recirculating Aquaculture Systems Short Course

  30. DESIGN EXAMPLE • Required Cross Sectional Area: A = Flowrate/Hydraulic Loading A = (24.1 L/s)/(20 kg/m2s) A = 1.2 m2 Recirculating Aquaculture Systems Short Course

  31. DESIGN EXAMPLE • Stripping Column Parameters: Recirculating Aquaculture Systems Short Course

  32. FI TOWER DESIGN air vent stripping column fan LHO clean out LHO sump Recirculating Aquaculture Systems Short Course

  33. FI TOWER DESIGN Recirculating Aquaculture Systems Short Course

  34. FI TOWER DESIGN INFLUENT WATER CO2 STRIPPER FAN LHO LHO SUMP Recirculating Aquaculture Systems Short Course

  35. FI TOWER DESIGN Tubular NORPAC Rotary Spray Nozzle Recirculating Aquaculture Systems Short Course

  36. FI TOWER DESIGN Low Pressure, High Volume Blower Recirculating Aquaculture Systems Short Course

  37. DESIGN EXAMPLE • Carbonate Carbon (CT) Mass Balance: IN + PRODUCED = OUT + STRIPPED QmCm + P = QmCe + Qr(Ce – Cr) Qr = {Qm(Cm – Ce) + P}/(Ce – Cr) Recirculating Aquaculture Systems Short Course

  38. DESIGN EXAMPLE • Carbonate Carbon (CT) Produced: P = (F)(OCR)(CPR) P = (100 kg/day)(0.4)(1.38) P = 55.2 kg CO2/day P = 38,333 mg CO2/min P = 0.871212 mol CT/min Recirculating Aquaculture Systems Short Course

  39. DESIGN EXAMPLE Recirculating Aquaculture Systems Short Course

  40. DESIGN EXAMPLE • Carbonate Chemistry Calculations: Recirculating Aquaculture Systems Short Course

  41. DESIGN EXAMPLE • Required Flowrate: Qr = {Qm(Cm – Ce) + P}/(Ce – Cr) Qr = {3.5(0.002110 – 0.002909) + 0.871212}/(0.002909 – 0.002308) Qr = 1,445 Lpm Qr = 382 gpm Qr = 24.1 L/s Recirculating Aquaculture Systems Short Course

  42. DESIGN EXAMPLE • Difference Between Methods: Recirculating Aquaculture Systems Short Course

  43. FACILITY CONSIDERATIONS • Airspace CO2 Toxicity Standards: Recirculating Aquaculture Systems Short Course

  44. FACILITY CONSIDERATIONS % CO2 Removal Inlet Stripping Gas CO2 (ppm) Recirculating Aquaculture Systems Short Course

  45. RECOMMENDATIONS • Include CO2 stripping in your new designs! • Look for easy aeration retrofits in your existing designs. • Don’t forget facility ventilation requirements (CO2, humidity, heat). Recirculating Aquaculture Systems Short Course

  46. COMPUTER DESIGN MODEL • Vinci, B. J., Timmons, M. B., Summerfelt, S. T., & Watten, B. J. (1998). Carbon Dioxide Control in Intensive Aquaculture (Version 2.1) [Computer software]. Ithaca, NY: Natural Resource, Agriculture, and Engineering Service. Recirculating Aquaculture Systems Short Course

  47. MODEL FACILITY Environment Ventilation CO2 Moisture CO2 Stripper Culture Tanks Recirculating Aquaculture Systems Short Course

  48. CONTROL OPTIONS • Packed Tower Stripping • Sodium Hydroxide Addition • Water Exchange • In-tank Surface Aeration • Side-stream Surface Aeration • In-tank Diffused Aeration • Side-stream Diffused Aeration Recirculating Aquaculture Systems Short Course

  49. PACKED TOWER STRIPPING Water with high CO2 Air + CO2 Air Culture Tank Water with low CO2 Recirculating Aquaculture Systems Short Course

  50. NaOH ADDITION To System Dosing Pump NaOH Reservoir Recirculating Aquaculture Systems Short Course

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