Experiment Study And Simulation On The Dry Processing Of Modified Starch Based On The Vortex Technology

Modified starch is the main product of the deep processing starch. It is widely used in textile, paper making, food, feeding, found, fine chemistry, medicine, timbering, petroleum and so on. According to the technical there are three kinds one is wet processing, one is dry processing and the third is combining of above two. The disadvantages of the wet processing are great usage of water, chemical reagent, more loss of starch, numerous of process, longer react time and pollution drainage and so on. Although dry processing can conquer above flaw, it can also have the disadvantages of asymmetry mix, not equal reaction, difficult to provide reaction condition, difficult to make technics continued and so on. The combining of wet and dry processing also has the disadvantages of great consume of chemical reagent and water, much let out of contaminanoa In order to conquer above disadvantages, new technology using vortex is provided to settle some problem such as asymmetry mix, not equal reaction, decreasing chemical reagent, enhancing efficient, falling of consume of energy and so on. No similar using of vortex in modified starch did be found in the document consulted, and even the maths simulation of the flow field of the interior of the vortex reactor. The paper is engaged in the new technics of modified starch and maths simulation with applying of Gas and Solid flow theory and CFD technical. In theory the flow field condition and the reaction situation can be acquired The content of the paper are as follows.(1) Experiment of preparing modified starch. Two delegate modified starch dextrin and Phosphoric Ester of Potato Starch are chosen to be prepared with using vortex reactor. By checking kinds of indexes and experiment under different condition, the optimum parameters were obtained and the excellent technical projects were found.(2) The constituting of maths model of flow filed of interior reactor. Based on the gas and solid theory, the movement states are forecasted by ASM model. Because this model can simulate onflow and revolve flow more preferably, the model can accord with the movement rule much better. The model of the grain is Two-fluid model. Hot and matter transferring model is used to describe the process of the exchange of hot and matter of the gas and the solid. The process of the react is simplified. The model of react is simplified as a model of the hot exchange of the gas and the solid because the reaction happened only in the interior of the solid. The movement of gas and solid, hot and matter exchanging situation and the reaction situation can be obtained through the settling of these models.(3) Settling of the maths model. All the situation of the interior vortex reactor can be simulated by the CFD model. Numerical value method was used to settle these models. All the theory process including the transforming of coordinate, the dispersing of the currency equation group, the choosing of the difference format, dealing of the fountain item, the settling of algebra equation, the SIMPLE arithmetic of single-phase equation group, the LEGAML arithmetic of gas-grain phases and so on were described in details. Based on the analysis of above process, the models were simulated with CFD software. The main process of the software including the ascertaining of the scope of simulating field and the dividing of non-structure grid, the choosing of the bound condition and the processing of account of numerical value.(4) The acquiring of the simulation result. It is difficult to measure the velocity, temperature, humidity because the limit of experiment condition and the limit of vortex reactor itself. The distributing of velocity, temperature, density, relative humidity, tangential velocity, axial velocity, radial velocity,turbulence intensity, mass fraction of H2O and velocity vectors etc. The effect of the change of angle of slurry leaf and reacting temperature are simulated in the paper. The conclusion provided the theory guidance for the reality use of vortex reactor. It also provides the measure method for th...