PURPOSE: To safely and efficiently realize precompression of a rotary channel pump by a simple structure and operation by precompressing particulate solids by means of a rotary feeder connected to an inlet of a rotary flow channel and performing operation at the displacement flow.

CONSTITUTION: In a displacement rotary precompressor 13, a rotor 138 having four blades 131 to 134 is arranged on the lower end in a hopper 139. Respective blades 131 to 134 move materials to be supplied to the supplying terminal of a flow channel 12. The flow channel 12 is formed of a first annular drag flow segment L1 arranged between a stator 14 and a rotor 16. A wedge-shaped deflector 18 is arranged, and the tip 181 is in slidable-contact with the rotor 16 to form a rotational part of the first drag flow segment L1. A straight channel segment L2 is formed between a planar wall part 148 of the stator 14 and a planar wall part 182 of the deflector 18.