高温高圧サワー環境の pH 推定および測定

概要

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A new technique for estimating the pH of concentrated aqueous solutions in equilibrium with high pressure H_2S and CO_2 at elevated temperature was proposed. Based on the thermodynamic investigation for solution properties, the following equation was obtained. pH=-logγ_H+{(K_<1, H>K_<H, H>P_<H_2S>/γ^2_<±H_2S>)^<1/2>+(K_<1, C>K_<H, C>P_<CO_2>/γ^2_<±CO_2>)^<1/2>} The physico-chemical parameters in the equation were calculated by PBILC (Principle of Balance of Identical Like Charges) proposed by COBBLE et al. or assumed to be identical with those for HCl+NaCl aqueous solutions. The calculation of the pH of high temperature and high pressure sour environments was enabled by using this equation. A Nb-doped TiO_2 semiconductor electrode of n-type was well applied to measure the pH of the environments and underwent no interference with NaCl, H_2S and CO_2. The measured pH values agreed well with those estimated by the newly proposed technique at the temperature up to 473K and at partial pressures of H_2S and CO_2 up to 4 MPa. It was ascertained by pH measurements for HCl+NaCl aqueous solutions at elevated temperatures that the assumption made for physicochemical parameters in the pH estimation was valid.
社団法人日本鉄鋼協会の論文
1988-10-01