  This proceeding briefly summarizes our recent work on calculating the
correlated fluctuations of net protons on the hydrodynamic freeze-out surface
near the QCD critical point. For both Poisson and Binomial baselines, our
calculations could roughly reproduce the energy dependent cumulant $C_4$ and
$\kappa \sigma^2$ of net protons, but always over-predict $C_2$ and $C_3$ due
to the positive contributions from the static critical fluctuations.
