Abstract:

In order to accurately grasp the mass transfer characteristics of residual ammonia in yarn bobbins after liquid ammonia treatment and increase the recovery ratio and recovery rate of ammoia, a mathematical model of mass transfer was established by condidering diffusion and convection. It became easier to analyze the mechanism of the emission of ammonia when the mass transfer equations was normalized. Then the Crank-Nicolson implicit difference method was used to solve the normalized mass transfer equations, and the stability and convergence of the algorithm are proved. Finally, the numerical results were compared with the experimental data, which proved the correctness of the model. The conclusion shows that the method of increasing wind velocity and decreasing the bobbin outer diameter can accelerate the volatilization of ammonia, and the ammonia volatilization process under low wind speed condition is an approximate steady state process.

Key words: yarn bobbin, residual ammonia recovery, liquid ammonia treatment, mathematical model of mass transfer, numerical simulation