Abstract: In this thesis, hydrodynamic data of large hole area and large holed sieve trays in spray regime were obtained and studied. A set of equations to correlate hydrodynamic parameters was established. As a result, the combination sieve tray had the characteristics of lower resistance, little entrainment and big upper limit velocity of operation. Especially, it was agrees with the fact that the processes require a large gaseous phase loading and lower liquid loading.