| 摘要 |
Process for preparing high-concentration gaseous formaldehyde having a molar CH<SUB>2</SUB>O:H<SUB>2</SUB>O ratio of >=0.6 from an aqueous formaldehyde solution by evaporation of at least part of the solution, in which the aqueous formaldehyde solution is heated to a vaporization temperature T and the gas phase formed is taken off, wherein the evaporation temperature T obeys the relationship: <?in-line-formulae description="In-line Formulae" end="lead"?>T[° C.]>=T'<SUB>min</SUB>[° C.]<?in-line-formulae description="In-line Formulae" end="tail"?> where T'<SUB>min</SUB>(c)=A+Bx(c/100)+Cx(c/100)<SUP>2</SUP>+Dx(c/100)<SUP>3 </SUP> and A=+68.759, B=+124.77, C=-12.851, D=-10.095, where c is the instantaneous CH<SUB>2</SUB>O content of the aqueous formaldehyde solution during the evaporation in percent by weight and is from 20 to 99% by weight.
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