Barometric condenser changes condensible vapors from a process into condensates. Meanwhile, non-condensible vapors or gases that could not be removed by barometric condenser are removed by vacuum ejectors.
After condensible and non-condensible vapors or gases are removed from the system, vacuum condition is created.
To see how the system is designed, just follow this link.
Vacuum ejector is also called by steam ejector since it utilizes steam a moving media.