METHOD FOR THE PRODUCTION OF HIGHLY CONCENTRATED FORMALDEHYDE SOLUTIONS

摘要

A method for the production of highly concentrated formaldehyde solutions containing >= 50 wt. % CH2O from an aqueous formaldehyde solution having a lower CH2O content by evaporating part of said solution (partial evaporation), wherein the aqueous formaldehyde solution is heated to an evaporation temperature T wherein water becomes enriched in a gaseous phase in relation to the liquid phase and the formed gas phase is continuously or discontinuously removed. For the evaporation temperature T: T [ °C] < Tmax [ °C] with Tmax(c) = A + B x (c/100) + C x (c/100)<2> + D x (c/100)<3> and A = + 68,759, B = + 124,77, C = - 12,851, D = - 10,095, wherein c is the actual CH2O content of the aqueous formaldehyde solution during evaporation in wt. % and amounts to 20 -99 wt. %