Patent ID: 6414196
Filing Date: 2002-07-02
Classification: B01D,C07C

Abstract:
A process for the post-purification of pyrolysis gases for preparing pure formaldehyde, having the process steps of:pyrolyzing hemiformal in an evaporator, passing the resulting formaldehyde vapor through the condensed liquid component collected in the bottom area of the evaporator, passing out the condensed liquid component through a cooled outlet tube disposed in the bottom area of the evaporator, so that the condensed liquid component flows down as a falling film on the inner wall of the cooled outlet tube, passing the formaldehyde vapor in cocurrent through the cooled outlet tube, taking off the formaldehyde vapor at the outlet tube end remote from the evaporator, and taking off the condensed liquid component at the outlet tube end remote from the evaporator.