The invention relates to a device and method for separating butylenes and removing butynol and heavy component to get coarse 1,3-butynol from carbon four mixture through extractive distillation by using water-bearing acetonitrile as dissolvent in double baffle tower. The extractive distillation operation is carried out in the baffle tower with up and low two section longitudinal baffle, the inner structure of the baffle tower comprises butadiene extraction and distillation section, heavy component stripping section, alkyne extraction and distillation section, shared middle tower zone, dissolvent analysizing section, alkyne steaming section and shared lower tower zone. Introducing the liquid in the middle of heavy component stripping section and alkyne extraction and distillation section to side tower to strip the heavy component, dislodging the side tower and relative equipment if the heavy component is not needed stripping. The inventive device and method complish the traditional two-time extraction and distillation and part of heavy component stripping in one tower, and is characterized by small investment, simple operation, low energy consumption and reduced product cost. |