Abstract
Paper making is experiencing significant changes because of several reasons. Important one among them being the pollution control measures. One option is to cook the wood chips, so as to delignify selectively, by cooking them in liquor of higher sulfidity. This liquor, therefore, has higher concentration of sulfur compound e.g. S~(2-), S_2O_3~(2-), SO_3~(2-), SO_4~(2-) and S_x~(2-) etc. because of the process conditions in different stages of paper making. It seems the corrosion in digesters depends very strongly on the relative amount of the different sulfur species in cooking liquor, which is likely to differ from one mill to another. To tackle the problem of corrosion in digesters, therefore, it was planned to understand the basics of the reactions and their dependence on liquors' composition. This is to be followed by comparing the performance of steels and stainless steels currently being used and likely to be used in fabrication of future digesters. All these aspects are discussed in this paper.
NSTL