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Rotating packed bed (RPB) has been demonstrated as a significant and emerging technology to be applied in natural gas desulfurization. However, droplet characteristics and principle in H2S selective absorption with N-methyldiethanolamine (MDEA) solution have seldom been fully investigated by experimental method. Therefore, a 3D Eulerian–Lagrangian approach has been established to investigate the droplet characteristics. The discrete phase model (DPM) is implemented to track the behavior of droplets, meanwhile the collision model and breakup model are employed to describe the coalescence and breakup of droplets. The simulation results indicate that rotating speed and radial position have a dominant impact on droplet velocity, average residence time and average diameter rather than initial droplet velocity. A short residence time of 0.039–0.085 s is credited in this study for faster mass transfer and reaction rate in RPB. The average droplet diameter decreases when the initial droplet velocity and rotating speed enhances. Restriction of minimum droplet diameter for it to be broken and an appropriate rotating speed have also been elaborated. Additional correlations on droplet velocity and diameter have been obtained mainly considering the rotating speed and radial position in RPB. This proposed formula leads to a much better understanding of droplet characteristics in RPB.

The atmospheric mapping function is an important model to convert the total tropospheric delay on the slant path of satellite signal into the zenith tropospheric delay. It is important to choose the appropriate mapping function to improve the accuracy of water vapor estimation. Beidou observation data in different seasons from 6 MGEX stations were processed using GAMIT 10.7 software. Three mapping functions (NMF/GMF/VMF1) were used in the estimating the atmospheric precipitable water vapor (PWV) based on Beidou Ultra-rapid precise ephemeris. The results of PWV/BDS were compared with the PWV/GPS. The experiments showed that the average bias between PWV/BDS and PWV/GPS is about 1-5mm. The GMF mapping function is slightly better than NMF and VMF1 in the retrieval of atmosphereric water vapor.