  This paper is devoted to the calculation of the momentum of localized
excitations, such as solitons and vortex rings, moving in a superfluid. The
direct calculation of the momentum by integration of the mass flux density
results in a badly-converging integral. I suggest a method for the
renormalization of the integral with the explicit separation of a term related
to the vortex line. This term can be calculated explicitly and gives the main
contribution for the rings whose size is large compared to the healing length.
I compare my method with the Jones and Roberts prescription for the
renormalization. I investigate the case of a uniform superfluid, and that of a
superfluid in a cylindrical trap. I discuss the calculation of the jump in the
phase of the order parameter and obtain a simple estimate for this jump for a
large ring in the trap.
