Abstract: Aiming at the problem of the axial displacement of the reaction feed pump in the residue hydrogenation unit which was larger than normal or even exceeded the total clearance of the thrust bearing, it was considered after check and analysis that this problem was related to low pump flow rate. The reason is the wear and tear of the internal parts, resulting in the increase of internal reflux, which led to the decrease of pump flow as well as the rise of inter-segment pressure. This destroyed the balance of the axial force, causing the thrust bearing to bear very large axial force, which resulted in large axial displacement.

Key words: reaction feed pump, flow rate, axial displacement, C-ring seal