Process for purification by cryogenic sublimation
AssigneeBell Telephone Laboratories, Incorporated
InventorJames Windfield Mitchell
Life of this patent
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Abstract
A process is described for purifying liquids by cryogenic sublimation. This process involves solidifying the liquid by reducing the temperature and pressure to below the triple point. Purification is then carried out by direct transformation from the solid to the vapor phase. Because of increased differentials in vapor pressures at the low temperature at which the procedure is carried out, this purification process is highly efficient and is also particularly suitable for liquids that are susceptible to decomposition with ordinary purification procedures requiring elevated temperatures. The procedure is also advantageous in separating azeotropes, structurally similar compounds, as well as treating flammable, hydroscopic, corrosive and fuming compounds.
Claims15
A process for the purification of substances which are liquids at ambient temperatures and pressures by phase transformations between different states of matter of the substance so as to leave impurities in the residue and collecting a purified substance, in which the process includes the steps of
- a. reducing the temperature and pressure of the substance being purified from ambient temperatures and pressure to below the triple point of the substance being purified using cooling means and pressure reducing means,
- b. carrying out the phase transformation between states of matter of the substance being purified from solid state to vapor state,
- c. collecting the purified substance in a collection vessel, and
- d. increasing the temperature and pressure of the purified substance to ambient temperatures and pressures so as to return the purified substance to the liquid state.
Dependencies are inferred from the claim text.