(599e) A Fresh Look At The H Factor DATA For Indian Nonwood Agri-Residues

A FRESH LOOK AT THE  H FACTOR DATA FOR INDIAN NONWOOD AGRI-RESIDUES

ABSTRACT

H factor is  an extremely important parameter in modern process control in pulp mill operation  representing extent of chemical reaction as it enables changes to be made in the time- temperature cycle while maintaining a constant degree of delignification. The combination of time and temperature as a single variable  does not have any effect as long as the H factor remains constant, the yield and lignin content will be the same. The greater the H Factor more the delignification occurs. Generally, H factor is  determined using the procedure proposed by Vroom , known as Vroom H factor model which  provides a method for expressing both cooking time and temperature in H factor for soft wood. There have many modifications of this parameter and its application during pulping studies over the years. As per actual definition,it should be the integral of the relative reaction rate or the absolute reaction rate  with respect to time. The H-Factor values are thus computed based on both mathematical methods using graphical and numerical integration techniques as well as approximate method based on Vroom’s H-Factor used for routine control..

For many nonwood annual fibres such as wheat straw, rice straw and bagasse , the H factor values have  not been established even today. Attempts have made in this paper to model the H factor for  some important annual fibers ,namely bagasse and straw which are very important feedstock for pulp and paper industries in India. Attempts have also been made  to highlight the various modifications of H factor estimation procedure and compare the values. As for estimation of H factor activation energy values are required, this needs in turn delignification reaction to be performed. Therefore  in the present work detailed kinetic experiments are carried out and activation energy for these fibres is determined. Using the experimentally evaluated value of activation energy, Boltzmann frequency factor ,and specific reaction rate kinetic model for delignification is developed. A comparison has been made for the values of absolute H-Factor ,Vroom’s H-Factor , Jagannadh et al. ,others based on developed kinetic modals and H-Factor calculated using MacDonald’s            data for wood is made.