公开(公告)号：DE19747647A1

公开(公告)日：1999-05-06

申请号：DE19747647

申请日：1997-10-29

Applicant: HOECHST AG

Inventor： SIEVERS WERNER DR ,  SCHWEERS ELKE DR ,  ROSENBERG MICHAEL

IPC: B01D1/22 ,  B01D1/30 ,  C07C45/51 ,  C07C45/78 ,  C07C45/82 ,  C07C47/04 ,  C07C47/045 ,  C07C47/058

Abstract: A process and device are disclosed for subsequently purifying gases, in particular pyrolysis gases, and for preparing pure formaldehyde. Hemiformal is pyrolysed in an evaporator, the resulting formaldehyde vapour is led through a liquid component condensed in the bottom region of the evaporator, the liquid component condensed as a falling film on the inner wall of the evaporator is discharged through a cooled outlet pipe arranged in the bottom region of the evaporator and the formaldehyde vapour is discharged in the same direction through the cooled outlet pipe. The liquid component and the formaldehyde are separately recovered at the end of the outlet pipe away from the evaporator.