Anthraquinone dyes are the second most significant dyes in the dye industry after azo dyes.Nitroanthraquinone prepared by the nitration of anthraquinone,is one of the important raw materials for the synthesis of various types of anthraquinone dyes.In this study,a microreactor with excellent heat and mass transfer properties was utilized to investigate the continuous?flow nitration process of anthraquinone.The effects of key process parameters such as reaction temperature,volume flow rate,molar ratio of nitric acid to anthraquinone,anthraquinone concentration,residence time,and sulfuric acid intensity on the nitration process were examined.The results showed that the competition between mono? and di?nitrification reactions during anthraquinone nitrification was significant, and the adjustment of process parameters would significantly affect the ratio of mono? and di?nitrification products while promoting the conversion rate of anthraquinone.The full use of the advantages of microreactors to precisely regulate the process parameters is an effective measure to improve the selectivity of the target nitration product.

The time series of instantaneous velocity in the Kenics static mixer, 0.04 m in diameter and 1.25 in aspect ratio, were conducted with laser Doppler particle analyzer. The signal of velocity fluctuation were decomposed into signals of different frequency band including 0~12.5, 12.5~25.0, 25.0~37.5, 37.5~50.0, 50.0~62.5, 62.5~75 Hz and more than 75 Hz based on Fourier transform. The linear and nonlinear correlation characteristics of signal of different frequency band were evaluated with auto-correlation function and mutual information function, respectively. The experimental results indicate that the signals of more than 62.5 Hz in frequency have no linear correlation, and there are no nonlinear and linear correlation for the time series signal which is over 75 Hz in frequency.

The turbulent flow characteristic in a stirred mixer with propeller was predicted based on multi-reference frame by using CFD turbulent model. Some detailed information about the velocity and turbulence kinetic energy was obtained. The simulated results show that the mean velocities increase firstly then decrease as radial position increasing, while the values of mean velocities close to the impeller are larger which were found in good agreement with the experimental results reported in the literature. Though the velocity distributions at different axial position above the stirrer are also much smoother, the values of velocity increase firstly then decrease in the discharged zone. The turbulence in the discharged zone tends to be nonuniform and the magnitude of the turbulent kinetic may have 7~9 times difference at the same axial or radial position. It is priority to select propeller for the axial speed field as main field, long distance transmission compared with traditional typical three-blade impeller of 45°.

The characteristic of flow resistance in the new type static mixers was investigated based on the microscope flow character by using the computational fluid dynamics(CFD) software. It can be seen from the velocity vectors of axial cross-sections that there was the spin flow, reverse to the revolving direction of the mixer element groups in the new type static mixers. The relationship among all factors influencing flow resistance in the static mixers was simplified by using the dimensional analysis and π theorem. A general relationship of friction coefficient of the flow resistance was gained by data reduction and regression. It offers the theoretical base for the industry application.