Permeation rate measurements of hydrochloric (HCl) and hydrofluoric (HF) acid through polymer components and prediction of associated component life.

1. Modeling of component lifetime based on accelerated acid gas permeation measurements Gary Van Schooneveld, Don Grant, Debra Carrieri, Dennis Chilcote and Mark Litchy February 11, 2009

4. Steady-state permeation Note: The mass flow rate is proportional to the gas vapor pressure; not the acid concentration.

5. Partial pressure of HF over hydrofluoric acid solutions Source: Brosheer at all, Ind and Eng Chem 39(3):423-427, 1947 and Hydrofluoric Acid Properites, Honeywell (2002).

6. Comparison between vapor pressures of HF and HCl over hydrofluoric and hydrochloric acids Source: JH Perry, Chemical Engineers’ Handbook, 4 th Edition , McGraw Hill (1963) p 3-61 Source: Brosheer at all, Ind and Eng Chem 39(3):423-427, 1947 and Hydrofluoric Acid Properites, Honeywell (2002).

7. Comparison of HCl and HF vapor pressures

9. Test System Schematic

11. Example of permeation data – 49% HF at 3 temperatures

12. The effect of vapor pressure, temperature, and thickness on the permeation rates of HCl and HF through PFA

14. Permeability coefficient

15. The effect of temperature on the permeability coefficient of HCl through PFA 1.5mm thick samples

16. The effect of thickness on the permeability coefficient of HCl through PFA

17. The effect of temperature on the permeability coefficient of HF through PFA

19. Polymer permeability comparison

20. Permeation coefficient of HCl through different polymers

21. Permeation coefficient of HCl through different polymers 33 o C

22. Permeation coefficient of HF through different polymers 33 o C

23. Comparison between HCl and HF permeation coefficients @ 33 o C

24. Comparison between HCl and HF permeation rates with “as-received” acid @ 33 o C

25. Component lifetime predictions Assumption: Component lifetime is inversely proportional to the rate at which the acid gas reaches the component.

27. Predicted relative lifetimes of PFA coated components under expected use conditions

30. Predicted lifetimes based on pumps and impellers currently under test > 450 > 2,900 2,200 1,500 > 830 Service Life @ 6.3%/75 o C (Years) > 450 > 2,900 > 2,800 > 1,700 > 830 Safe Life @ 6.3%/75 o C (Years) > 3.2 > 20.7 > 19.9 > 12.0 > 5.9 Safe Life @ 37%/20 o C (Years) > 3.2 > 20.7 15.5 10.5 > 5.9 Service Life @ 37%/20 o C (Years) 30.6 69.9 115 BPS 3 Impellers 30.2 74.3 590 BPS 4 29.9 74.4 590 BPS 3 28.7 70.0 546 BPS 1 35-37 RT 2150 BPS 3 Average HCl Assay (wt%) Average Temp ( o C) Run Time (Days) Pump Model