The viability of two solid adsorbents, limestone and cement powder, for use in a flow-through packed-bed column for HCl and HF gas neutralization following refrigerant destruction was studied. Neutralization tests performed at 408 K using 5% HCl in N2 and 5% HF in N2, showed that limestone had a significantly higher adsorption capacity for both HF and HCl. ~49% of fed HCl, and between 7.8%-16.2% of fed HF gases were adsorbed by 7 g of limestone for a gas flow rate of 6.67×10^(-6) m3/s (STP) over 30 to 180 minutes. Effective diffusivities (De) of HCl and HF into_x000D_ the limestone particles were 1.5×10^(-9) and 2.2×10^(-9) m2/s, respectively, indicating that a solid diffusion mechanism dominance would limit the suitability of this method as a solid adsorbent in the tested form. Under these conditions, complete particle conversion times were 227 hours for HCl-limestone and 154 hours for HF-limestone. Considering the long conversion times observed, shorter conversion times would require micron-scale particle sizes, suitable for entrained flow but not for a packed-bed arrangement. A Na2CO3/Limestone slurry used to neutralize the reactor effluent proved efficient within this system, and may be a more suitable alternative for acid neutralization involving HF.

HF HCl Refrigerant Destruction Solid Adsorption Media Shrinking Core Model

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