The effect of pyrolysis on the microstructure and moisture adsorption of lignite was investigated with low field nuclear magnetic resonance spectroscopy. Changes in oxygen-containing groups were analyzed by Fourier transform infrared spectroscopy (FTIR), and H 2 O adsorption mechanism on the surface of lignite pyrolysis was inferred. Two major changes in the pore structure of lignite char were observed as temperature increased in 105-200°C and 500-700°C. Pyrolysis temperature is a significant factor in removing carboxyl and phenolic hydroxyl from lignite. Variation of ether bond content can be divided into three stages; the content initially increased, then decreased, and finally increased. The equilibrium adsorption ratio, content of oxygen-containing groups, and variation of pore volume below 700 ° were closely correlated with each other. The amount of adsorbed water on char pyrolyzed at 700°C increased. Moreover, the adsorption capacity of the lignite decreased, and the adsorption state changed.

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Taking supersaturation and heat transfer rate as evaluation indexes, two typical internal geometries of an oscillatory flow crystallizer (OFC) with circular‐orifice baffles (OFC‐COB) and smooth periodic constrictions (OFC‐SPC) were studied by numerical simulation. The results indicated that OFC‐SPC could provide a relatively high heat transfer rate, supersaturation, and similar or lower power density consumption, as well as a uniform flow field distribution without vortex dead zone. Further, a method to prejudge the supersaturation in oscillatory flow crystallizer is proposed, which would be good guidance to determining the operating parameters.

In the process of industrial crystallization, it is always difficult to balance the secondary nucleation rate and metastable zone width (MSZW). Herein, we report an experimental and numerical study for the cooling crystallization of paracetamol in an oscillatory flow crystallizer (OFC), finding the optimal operating conditions for balancing the secondary nucleation rate and MSZW. The results show that the MSZW decreases with the increase of oscillation Reynolds number (Re o ). Compared to the traditional stirring system, the OFC has an MSZW three times larger than that of the stirring system under a similar power density of consumption. With the numerical simulation, the OFC can produce a stable space environment and instantaneous strong disturbance, which is conducive to the crystallization process. Above all, a high Re o is favorable to produce a sufficient nucleation rate, which may inevitably constrict the MSZW to a certain degree. Then, the optimization strategy of the operating parameter (Re o ) in the OFC is proposed.