Study Of On-line Measurement Of Pulp Kappa Number With Spectrometry During Pulping

Aiming at the difficulties and problems of on-line measurement of pulp Kappa number during batch pulping, this dissertation proposes a new measuring idea, which is to predict the lignin content in pulp through the measurement of dissolved lignin in cooking liquor with modern spectrum technology. Therefore, the on-line measurement of pulp Kappa number can be achieved.The basic mathematical model of Kappa number during sulfite pulping is derived from the spectrum measuring theory as,where V is the total volume of liquor in digester, η is the parameter expressing raw material, k is lignin absorption coefficient in cooking liquor, b is length of light, A is the absorbance of cooking liquor and B is a constant.The modified model including the affection of packing volume L₀ of raw material in digester is developed,where the modified factor ε is derived from the actual experience in mill site and the experimental model of our study. According to the increasing rate of SO₂ pressure in digester during the second temperature rising stage, the calculation of ε is,...