  In this first of a series of papers, we utilize results for around two
thousand star cluster models simulated using the MOCCA code for star cluster
evolution (Survey Database I) to determine the astrophysical properties and
local merger rate densities for coalescing binary black holes (BBHs)
originating from globular clusters (GCs). We extracted information for all
coalescing BBHs that escape the cluster models and subsequently merge within a
Hubble time along with BBHs that are retained in our GC models and merge inside
the cluster via gravitational wave (GW) emission. By obtaining results from a
substantial number of realistic star cluster models that cover different
initial parameters, we have an extremely large statistical sample of BBHs with
stellar mass and massive stellar BH ($\lesssim 100M_{\odot}$) components that
merge within a Hubble time. Using this data, we estimate local merger rate
densities for these BBHs originating from GCs to be at least 5.4 ${\rm
Gpc}^{-3}\,{\rm yr}^{-1}$
