Patent ID: 7424956
Filing Date: 2008-09-16
Classification: B07B

Abstract:
1. A method of separating unwanted lightweight grains from raw grains using a vertical cylinder having, in order from the top, an exhaust port, a cylindrical primary separation space, a conical secondary separation space, a tertiary separation space, and an unloading port, comprising: a primary separation step of introducing raw grains containing the lightweight grains, which are to be separated, together with primary air into the cylindrical primary separation space in a direction to allow the raw grains to whirl upward in a whirling motion along an inner wall surface of the cylindrical primary separation space, so that most of the lightweight grains contained in the raw grains are guided to the exhaust port by upwardly flowing air in the cylindrical primary separation space and the raw grains and part of the lightweight grains stay in a predetermined flow area by frictional resistance with respect to the inner wall surface generated by the whirling motion and then are dropped into the conical secondary separation space by their own weight; a secondary separation step of blowing secondary air to a lower portion of the conical secondary separation space through a slit toward an upwardly beveled surface of a stabilizer provided centrally in the lower portion of the conical secondary separation space, and toward the raw grains dropping into the conical secondary separation space from the primary separation step so as to blow lightweight grains in the raw grains upward to the cylindrical primary separation space; a tertiary separation step of blowing tertiary air upward from below the conical secondary separation space to blow remaining lightweight grains to the conical secondary separation space; a discharging step of taking the raw grains with the lightweight grains removed continuously out from the unloading port provided below the conical secondary separation space; and an exhaust step of continuously exhausting primary, secondary, and tertiary air having the lightweight grains toward a horizontal tangential direction from an upper portion of the primary separation space.