Study of the Static Mixer Distributor Effect on a Multiphase Monolithic Reactor Performance Using Polyenergetic Tomography
Pablo A.S. Vasquez1, Rajneesh Varma2, Carlos H. de Mesquita1, Margarida M. Hamada1,
Muthanna H. Al-Dahhan3
1 Nuclear and Energy Research Institute – IPEN/CNEN/SP, Av. Prof. Lineu Prestes, 2242, Cidade Universitaria, CEP:05508-000, Sao Paulo, SP, Brazil
2 Washington University, Department of Energy, Environmental and Chemical Engineering, Chemical Reaction Engineering Laboratory, One Brookings Drive, St. Louis, MO63130, USA
3 Missouri University of Science and Technology, Department of Chemical & Biological Engineering, 143 Schrenk Hall, 400 West 11th Street, Rolla, MO 65409-1230, USA.
The flow distribution patterns in a 0.041 m diameter and 0.40 m height co-current gas-liquid multiphase monolithic reactor were studied using a dual source computer tomography. A static mixer distributor consisting on two regions of structured packing was used to evaluate the distribution performance under different gas and liquid flow rates. The superficial liquid velocity was ranged from 5 to 26 cm/s and the superficial gas velocity from 13 to 100 cm/s inside of the Tylor flow regime. Several combinations between the gas and liquid velocities were analyzed by tomography scans performed at three different height L/D ratio levels (2, 5 and 7) of the reactor to determine the cross-sectional gas and liquid holdup distributions. The dual source computer tomograph developed at the Washington University in St. Louis worked with two radioactive sources, cobalt-60 and cesium-137 allowing interactions between the phases and two different gamma ray energies. The mean difference with single source gamma ray tomography is that the dual source system can track up to three mobile phases without reference tomographic scans. Tomography single source system can only track two mobile phases. Results of tomographic dual source scans provide a set of equations related to the attenuation coefficients for each phase and energy where an alternating minimization reconstruction algorithm was used to solve the holdup parameters. Also was calculated the azimuthally average radial phases holdup profiles. Results shown with respect to the degree of flow uniformity for all studied conditions that was phase maldistribution at the regions of low liquid superficial velocity and high gas superficial velocity creating an operating window for uniformity conditions that increase with liquid superficial velocity. The holdup liquid distribution varies along the reactor reaching the maximal values at L/D=5 and the lowest values at the inlet of the reactor, L/D=2. Then the studied distributor is not uniform creating pressure drop depending on the operation conditions. Mathematical models of monolithic reactors where is it supposed each channel has the same behavior need to be reviewed with the real distribution conditions.
Keywords: monolithic reactor, phase distribution, polyenergetic, dual source tomography
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