Experimental Study And Numerical Simulation Of Thermal-Fluid Jet Impinging Ramie Fiber Separation And Degumming

Recently,biological degumming or other degumming technology to replace the traditional chemical degumming scouring process is primarily studied by domestic and foreign researchers in hemp fiber preparation,and has made significant achievements.However,the traditional mechanical fiber separation and rinsing procedures are still being used in the subsequent techniques of fiber degumming and separation,which have lots of issues,such as labor intensity,water consumption and so on.Jet impinging ramie fiber separation and degumming with high temperature water has not been sufficiently discussed from relevant literature both at home and abroad.Atmospheric alkali boiling-Jet impinging ramie fiber separation and degumming with high temperature water technological process is proposed,which can accomplished the traditional mechanical fiber separation and rinsing procedures through jet impinging and rinsing fiber with high temperature water to separate fiber and swill out residual gum.With using atmospheric alkali boiled ramie fiber as the study object in this paper,dynamic impact test device for ramie fiber separation and deguming has been trial-produced.High temperature jet impinging and flushing device have been developed based on the dynamic impact test parameters,carrying out the experiment of fiber separation and degumming with single nozzle.The temperature and pressure field distribution of the fiber surface and its effective area in jet impinging wall at different jet distance of single nozzle and different distance between nozzles was simulated by means of numerical simulation for reveal the mechanism of jet impinging ramie fiber separation and flushing deguming with high temperature water in the light of single nozzle test parameters,obtaining best jet distance and optimal spacing between two nozzles.Taking residual gum rate and single fiber breaking strength as technical indexes,experiment of rinsing alkali boiled ramie fiber was launched on basis of best jet distance and optimal spacing between two nozzles,and chalked up the best comprehensive evaluation of technical parameters of technological process.The principal research results:(1)Dynamic impact examination was made for discussing dynamic impact fiber separation and deguming,grabbing reasonable range of impact pressure that is 0.15~0.25 MPa.(2)The experiment of fiber separation and degumming with single nozzle was carrid outthrough utilizing high temperature jet impinging and flushing device,which choose the control variables that water temperature is 363 K,time is 10 min,and the inlet pressure and jet distance,analyzing how to influence ramie separation and degumming under changing jet distance.When jet distance is 30 mm,the average residual gum rate is the lowest.(3)The temperature and pressure field distribution of the fiber surface and its effective area in jet impinging wall at different jet distance of single nozzle and different distance between nozzles was simulated by means of FLUENT with inlet pressure of single nozzle test(1.2 MPa),nozzle diameter(D=2.0 mm),inlet temperature(363 K)according to the fluid mechanics and heat transfer theory,using the VOF of Eulerian multiphase flow model,Heat Transfer Model and RNG model,geting the jet distance(S=30 mm)and the best nozzle spacing(H=30 mm).(4)Experiment of Jet rinsing alkali boiled fiber separation and degumming has been tested for the best comprehensive evaluation of technical parameters of technological process that bath ratio of alkali cooking is 1:10,water temperature is 90 ?,pressure is 1.2 Mpa,time is 15 min,getting residual glue rate is 3.1% and single fiber breaking strength is 51.71 cN.