The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Feb. 24, 1981
Filed:
Nov. 17, 1978
Applicant:
Inventor:
Herbert Haferkorn, Bottrop, DE;
Assignee:
Chemische Werke Huls AG, Herne, DE;
Primary Examiner:
Int. Cl.
CPC ...
B01D / ;
U.S. Cl.
CPC ...
55 82 ; 260707 ;
Abstract
A process for the fractional desublimation of pyromellitic acid dianhydride in the form of free-flowing crystals which comprises reducing a reaction gas containing pyromellitic acid dianhydride produced by a chemical reaction which also produces by-products, to a temperature above the thaw point of the by-products but below the desublimation point of pyromellitic acid dianhydride by means of a smooth thermostaticized cooling surface, directing the reaction gases at maximal flow velocities of 3 m/sec parallelly to the cooling surface and separating the fraction of crystals not adhering to the surface.