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:
Dec. 03, 1991
Filed:
Feb. 26, 1990
Mark J Girovich, Baltimore, MD (US);
Bio Gro Systems, Incorporated, Annapolis, MD (US);
Abstract
Municipal sludge is dried in an indirect heating dryer to simultaneously dry and pelletize the sludge while preventing the escape of malodorous gases. The product exiting the dryer contains pelletized, undersized and oversized fractions. The dried product is classified to separate the undersized and oversized fractions from the pellets. The pellets are then cooled and stored for subsequent use as a fertilizer or fuel. The oversized fraction is crushed to obtain fines and mixed with the undersized fraction, which contains mostly fines. The fines are added to the liquid sludge before it is input to the dryer. The air that is used to cool the pellets, and that is used as sweep air in the dryer contains malodorous gases. In order to prevent the escape of these malodorous gases, the pellet cooling air and sweep air, which also includes the water vapor generated during the drying of the sludge, is deodorized by thermal treatment, preferably in a high temperature combustion zone.