Studies On Power Consumption Of Rotating Zigzag Bed

As a highly efficient gas-liquid contacting device, rotating bed replaces the gravitational field with centrifugal field and greatly intensifies the mass and heat transfer processes. Rotating Zigzag Bed(RZB) is a novel kind of rotating bed, which has been applied in many chemical processes. An important factor that should be considered in practical applications of RZB is power consumption, in which liquid power consumption was the most important portion. In this paper, a theoretical analysis of power consumption of RZB was made and the liquid power consumption calculation method was established for RZB that contains single and multiple rotational baffles. The method was validated by corresponding experiments. Meanwhile, based on the analysis of liquid flow in the rotor, bars were installed at different positions in rotor with single rotational baffle to reduce liquid power consumption. The comparative experiments were conducted to identify the better position to install the bars. Then the experiments using rotor with multiple rotational baffles were carried out to further verify this position.The analysis shows that power consumption of RZB can be divided into three portions: liquid power consumption, gas power consumption and frictional power consumption. As the main portion of power consumption, liquid power consumption also could be further divided into two portions: power consumption to disperse liquid and to accelerate liquid. According to theoretical analysis, a calculation equation of liquid power consumption for rotor with single rotational baffle was proposed. And two correction coefficients in the equation were obtained by experimental data regression. Validation indicated that for rotor with single rotational baffle, the relative deviation of calculated and experimental liquid power consumption was within 20%; while the calculated values were about 1.2 to 1.4 times the experimental ones for rotor with multiple rotational baffles.In order to reduce the liquid power consumption of RZB, the balanced state of liquid in the RZB was analyzed. The free liquid surface in rotational baffle was parabolic and therefore, liquid was distributed on both rotational disc and rotational baffle. Modification local structure of rotor was considered to reduce liquid power consumption. Experimental results of rotor with single rotational baffle showed that bars on rotational baffle or rotational disc can reduce the liquid power consumption to a certain extent. The liquid power consumption reduction was largest with the bars installed both on rotational baffle and rotational disc. To verify this point, experiments using rotor with multiple rotational baffles were conducted. The experimental results showed that when the rotating speed was constant, liquid power consumption of RZB increased with liquid flowrate increase. Relative reduction of liquid power consumption decreased with the increase of the liquid flowrate. And the relative reduction with bars on the rotational baffle was higher than that with bars on the rotational disc. When the liquid flowrate was constant, the liquid power consumption of RZB increased with rotating speed increase. Relative reduction decreased generally with an increase of liquid flowrate.The proposed calculation method of liquid power consumption and the attempt to modify of the rotor structure to reduce liquid power consumption are good ideas for design and the practical application of the RZB.