PROCESS FOR REDUCING COMBUSTION PRODUCT RESIDUES IN PRODUCTS DRIED BY A DIRECT FLAME UNIT

摘要

A process for the air drying of a food material, such as a proteinaceous material, is disclosed wherein the drying air is heated by direct contact with a burner in such a manner that the formation of undesirable residues in the proteinaceous material as a result of combustion products from the burner is substantially reduced. The burner is operated by feeding to it a fuel mixture containing a stoichiometric quantity of air for purposes of combustion to avoid the use of drying air for combustion. The burner is also operated to provide a heat output which is sufficient for drying of the proteinsceous material but which does not exceed 800,000 BTU/ hr./lineal ft. of burner. The burner is also shielded from the drying air while operated at the necessary firing rate or heat output to substantially avoid seration of the flame by the drying air. Control of the velocity of the drying air together with the above factors substantially reduces the presence of burner combustion products in the drying air and, therefore, residues of burner combustion products in the materials to be dried.