The invention relates to a method and a device for separating and recycling
butanone by three-
tower pressure-variable rectification and heat integration. The method comprises the steps of: enabling raw materials to enter a dehydrating
tower, obtaining water containing a small amount of organic matters from the
tower bottom of the dehydrating tower, and extracting a normal-pressure
azeotrope from the tower top; pressurizing the normal-pressure
azeotrope and enabling the normal-pressure
azeotrope to enter a
butanone product tower, wherein the pressure boost increases the content of water in an azeotropic
system of
butanone-water, and
methanol,
ethanol,
benzene and the like generate a minimum-boiling-point azeotrope with butanone and water; extracting a high-pressure azeotrope from the tower top, and extracting a butanone product with higher purity from the bottom of the butanone product tower; adopting a hot material
stream entering from the tower top of the butanone product tower as the hot source of the dehydrating tower; and enabling the high-pressure azeotrope to enter a light component removing tower, extracting a light-component azeotrope from the tower top of the light component removing tower, obtaining a circulating material
stream from the tower bottom, and enabling the circulating material
stream to enter the dehydrating tower for cyclic operation. By using the method, the difficulty that butanone is separated and recycled from a
complex system is solved, butanone with higher purity is obtained, the quality purity of butanone is more than or equal to 99.5%, and the
energy consumption is reduced to the largest extent as a heat integration process is adopted.