Device and method for preparing polyalphaolefin

A process for preparing polyalpha-olefins, which comprises:

• a mixed stream obtained after mixing an olefin raw material and an auxiliary feed in a mixing unit and a BF3 gas are each independently allowed to enter a microchannel reaction unit, an intermediate stream formed after the polymerization reaction in the microchannel reaction unit is allowed to enter a high-pressure separation unit, the intermediate stream undergoes a first gas-liquid separation in the high-pressure separation unit, the separated liquid phase enters a low-pressure separation unit, a second gas-liquid separation occurs in the low-pressure separation unit, the liquid phase separated from the low-pressure separation unit enters a post-treatment unit, and a polyolefin product is obtained after the treatment in the post-treatment unit;
• the gas phases separated from the high-pressure separation unit and the low-pressure separation unit (BF3 gas) enter a gas circulation unit, and the BF3 gas is recovered for the recycled use, optionally, the heavy liquid phase containing the complex of the auxiliary feed and BF3 and the unreacted olefin raw material obtained after the treatment in the post-treatment unit is recycled to the mixing unit.