Numerical Simulation Research On Gas-solid Two-phase Flow And Heat Transfer Process In Spray Drying Granulator

Spray drying granulating machine is one kind of multifunctional granulating equipment,containing a set of mixing, spray coating, drying, granulating, particle coating and other functions.Regardless of its high production efficiency and pollution-free edges, many deficiencies are still there in the application. According to the domestic and foreign research on spray drying granulating machine and the investigation of its application, the fluidization condition of seed powder inside the spray drying granulator and the flow field of particles are simulated, based on FLUNT platform.The orthogonal experiment simulation will be conducted on the theory basis of actual working condition, the experiment measured parameters, resistance loss coefficient of the porous media in numerical simulation, and multiphase flow, by GAMBIT physical modeling and ANSYS ICEM CFD meshing for PGL – 150 B type spray drying granulating machine. The orthogonal experiment index is fluidization quality inside the pelletizer, and six factors are single-factor effect and interaction of three factors amongst hot air inlet velocity, solid particle stack height and the opening rate of fluidization porous plate opening rate in the process of fluidization. The analysis of orthogonal array test results indicate:First,the primary and secondary sequence of these factors affect to fluidized quality is the opening rate of fluidization porous plate, the interaction between inlet velocity of hot air and the opening rate of fluidization porous plate, hot air inlet velocity,the interaction between inlet velocity of hot air and solid particle stack height, the interaction between the stack height of solid particle and the opening rate of fluidization porous plate, and solid particle stack height, and particularly, the opening rate of fluidization porous plate can pose a significant impact on quality of fluidization, up to 0.025 order of magnitude, while the other five factors have no great effects on the test index.Second,The optimal parameter combination of fluidization is 1.489 meters per second of hot air inlet velocity, 0.455 meter of solid particle stack height and 5.33 percent of fluidization porous plate opening rate.Basis on the research on the fluidization quality, the velocity field, temperature field and humidity field of hot air inside the spray drying granulating machine, water mass fractiondistributions, as well as the particle trajectory marked by non-volatile and volatile constituents,reveals the internal flow field of the granulator on the foundation of granular drying. According to the numerical simulation, at the time of fluidization optimized particle drying was completed,outlet air temperature is about 362.5 k, which could basically meet the technical requirements of exit temperature at 90 ℃; Particles moisture content as low as 1.75% after drying, while moisture content to the medicine grain of finished product in the original process is 4.2%, namely the fluidization optimized particle was better fully dried.In this paper, gas-solid two-phase flow and heat transfer process of the spray drying granulating machine are simulated by CFD software, the result of which provides certain theoretical basis for the design of the system, as well as a certain guidance function for the application of this equipment.