| Chemical industry process is becoming towards high efficiency, sustainability, cleanliness and safety. Process intensification technology is one method to conserve energy and reduce emissions through the intensification of mixing and mass transfer processes, thus solving the problem of low selectivity, low yield and large load of the separation system. It can be achieved by developing two aspects, called equipment and methods. The rotating packed bed (RPB) is one of the typical process intensification equipment, while ultrasonic is the typical method.As the key device of the high gravity technology, RPB has excellent micromixing and mass transfer performance. With the development of RPB, the focus of future research will turn to innovative design of internals, such as rotor structure and liquid distributor. Ultrasonic cavitation will make cavitation bubble experience a process of oscillation, growth, shrinkage and collapse, thus can produce the mechanical and chemical effect. Mechanical effect can greatly enhance the mixing and mass transfer processes, while chemical effect can bring high temperature and pressure and then change the reaction mechanisation and rate.In this work, ultrasonic probes were installed on the cover of a RPB as stator, and a new type RPB coupling with ultrasonic was developed on the basis of combination of process intensification equipment and method. Micromixing and mass transfer efficiency in this novel RPB reactor were investigated. The results show that:(1) Firstly, we made a detailed explanation and description of the rotor structure and characteristics of the RPB reactor. Since the liquid initial distribution is very important for the RPB,5 kinds of liquid distributors were designed, of which 4 premixed distributors were took into computational fluid dynamics (CFD) simulations. The simulated results show that the macromixing performance of L-Distributor and O-Distributor with longer residence time was better; while the macromixing performance of Y-Distributor with short residence time was worse. The macromixing performance of 90°-Y-Distributor was better than that of 60°-Y-Distributor.(2) Micromixing efficiency of this RPB reactor was studied by adopting the iodide-iodate reaction as a working system. Five different distributors were arranged in the RPB reactor for the comaprsions of micromixing efficiency. The micromixing efficiency of RPB reactor with 90°-Y-Distributor was best, which indicated that premixed distributor had promoting effect to improve micromixing efficiency of the RPB reactor. The capability of a premixed distributor was determined by macromixing performance and residence time. The micromixing efficiency of the RPB coupling with ultrasonic has been further studied with the 90°-Y-Distributor mounted. The research results showed that the micromixing efficiency of the RPB reactor has been a certain increase with ultrasonic coupled, which means that ultrasonic cavitation has a promoting effect to liquid-liquid mixing process. In addition, with the increase of ultrasonic power, rotational speed, and liquid flow rate, the micromixing efficiency of the RPB reactor was improved, while the micromixing efficiency of the RPB reactor was decreased with the increase of H+ concentration, flow ratio, and viscosity.(3) The mass transfer process was investigated in the RPB coupling ultrasonic by using NaOH solution absorption CO2 system. The experimental results showed that the mass transfer efficiency of this RPB was better in the condition with ultrasonic, while with the increase of rotating speed, liquid flow rate, and gas flow rate, the mass transfer efficiency of the RPB was increased. Besides, ultrasonic cavitation effect was more obvious at the high values of the liquid flow rate since ultrasound was easy to spread with more liquid. |
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