| Water-sparged aerocyclone(WSA) is a newly developed mass transfer and gas-liquid reaction equipment, which combines the multifunctional effects of jet atomization in a rotational gas flow field and static high gravity, realizing intensification of mass transfer and reaction between gas-liquid phases. In order to gain an insight into the interaction mechanism between gas and liquid phases in the WSA and to put forward the method for adjusting the jet atomization in the WSA, the gas phase pressure drop of the WSA, mass transfer surface and liquid drop size produced by jet atomization have been investigated in this work, by means of experimental and CFD methods. The main results obtained are as follows.1. The gas phase pressure drop of the WSA will go through a low pressure drop area, pressure drop jump area and high pressure drop area, and the jet arrangement mode in the WSA does not change this characteristic of the gas phase pressure drop. A good jet atomization occurred in the high pressure drop area.2. The gas phase pressrue drop and liquid reflux ratio of the WSA could be simulated very well by using the RSM(Reynolds stress model) and VOF model(volume of fraction model). The spatial distibution of liquid phase volume fraction and jet flow pattern in the three pressure drop areas were analyzed, and a mechanism for the abrupt jump of gas phase pressure drop was put forward. In the low pressure drop area(0<ug<7.11 m·s-1), the jet was basically stable in the WSA due to the weaker interaction between jet and gas rotatioanl flow field. In the jump area of gas phase pressure drop(7.11<ug<8.89 m·s-1), jet atomization in the WSA is similar with the bag-breakup mechanism, some mass on jet surface was blown off and entrained into gas phase, leading to the increase of gas phase density and then causing to the jump of gas phase pressure drop. In the high pressure drop area(ug>8.89 m·s-1), jet atomization appeared as shear-broken mechanism.3. The axial velocity in the jet-rotational coupling field of the WSA increased with the increasing of gas phase inlet velocity. When the gas phase inlet velocity falled into the jump area of gas phase pressure drop, the increase of axial velocity near the aerocyclone wall was most obvious, the tangential velocity of the couping field declined and velocity direction reversed, the radial velocity distribution of the coupling field is unsymmetrical and the reversion of velocity direction occured.4. In the high pressure drop area of gas phase, the mass transfer interface increased to a maxium value first and then decreased with the increasing of gas phase inlet velocity. The gas phase inlet velocity responsible for a larger mass transfer area needs to exceed 50~100 % over that at the jump endpoint of gas phase pressure drop. This result is similar with that obtained by the CFD simulation. The gas phase inlet velocity which makes jet atomization area largest should exceed about 80 % over that at the jump endpoin. Under a certain gas phase inlet velocity, the increasing of jet velocity promoted the increase of mass transfer area, and the increase effect was more obvious when jet velocity started to increase from a lower level.5. The size of liquid drop produced by jet atomization decreased to a minimum value and then gradually increased with the increasing of gas phase inlet velocity in the high pressure drop area of gas phase. The inlet velocity of gas phase at the minimum drop size exceeded about 100 % over that at the jump endpoint. This result is in accordance with that the gas phase inlet velocity responsible for a larger mass transfer area needs to exceed 50~100 % over that at the jump endpoint. Under a certain gas phase inlet velocity, the increasing of jet velocity could make the drop size increase slightly. |
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