Device and method for single-stage continuous preparation of carbon nanotubes

An apparatus for continuous preparation of carbon nanotubes, based on a fluidized bed reactor. The fluidized bed reactor comprises an annular variable diameter region, a raw material gas inlet, a catalyst feeding port, a protective gas inlet, and a pulse gas controller. The annular variable diameter region is located at a region from a 1/4 position starting from the bottom to the top. The pulse gas controller is disposed at the arc-shaped top portion of the annular variable diameter region. The catalyst feeding port is located at the top of the fluidized bed reactor. The raw material gas inlet and the protective gas inlet are located at the bottom of the fluidized bed reactor. The device is also provided with a product outlet and a tail gas outlet. The device has a simple structure and low cost, is easy to operate, has a high raw material utilization rate, can effectively control the problem of carbon deposition on the inner wall of a main reactor, can manufacture high-purity carbon nanotubes, and is suitable for large-scale industrial production.