(117b) STRUCTURE OPTIMIZATION and PERFORMANCE STUDY of Rotating Jetting BED

As a novel gas-liquid mass-transfer equipment, the rotating packed bed(RPB) using centrifugal force to greatly intensify the processes of mass transfer, has been successfully applied in absorption, stripping, distillation, extraction process and nanomaterial production of chemical industry. The rotating jetting bed(RJB) was newly developed with the core components of the rotor and coil-type liquid distributor. The rotor is made up of stationary disc and rotating disc which is fixed to a series of concentric rotating baffles with perforations. Compared to RPB, intermediate feeds can be accomplished, installing an inlet at the stationary disc. Moreover, RJB with multiple rotor coaxially installing in one casing can be employed. Thus it is possible for one RJB unit to perform a continuous distillation.

As the important component of the rotating bed, the rotor determines the performance of RJB. Experiments of total reflux distillation with five types of RJB rotor were carried out using ethanol-water systems at atmospheric pressure. Effects of F-factor, spray density, rotational speed and rotor structure on mass transfer performance of RJB were investigated. Then the gas pressure drop and power consumption of RJB with the rotor of three-layer composite rotational baffles have been investigated in detail using the system of air-water.

The experimental results show that:

(1) The mass transfer efficiency of the RJB with five types of rotor appears the maximum value with the increase of the F-factor, spray density and rotational speed. So there exists an optimal operating condition. The higher opening ratio of rotational baffle is beneficial to mass transfer of RJB. The mass transfer efficiency of the rotor of three-layer composite rotational baffles was highest in the five type of rotors, with 30~50 theoretical plates per meter.

(2) There exists the gas-phase end effect of mass-transfer at the outside part of the rotor. Coil-type liquid distributor can significantly improve the initial liquid distribution in the circumferential and axial direction, increasing the mass transfer performance of RJB.

(3) The gas pressure drop increased with the increase of F-factor and rotational speed. The spray density has a little effect on the pressure drop. Therefore, the pressure drop is correlated with gas Reynolds number, liquid Reynolds number and rotating Reynolds number. The calculated values agreed well with experimental values, and the average deviation was less than 10%.

(4) The power consumption of RJB increased with the increases of rotational speed and liquid flow rate, and decreased slowly with the increases of gas flow rate. The ratio of the liquid power consumption to the shaft power consumption is 20%~70%, and the ratio increased with the increases of rotational speed and liquid flow rate.

(5) Among the five types of rotors, the rotor of three-layer composite rotational baffle with lower power consumption and lower specific pressure drops and high efficiency, was the superior rotor structure for RJB.