Production of Chlorine Dioxide from Chloric Acid; Saltcake Free, On Demand 01® Generator, 1995 Pulping Conference Proceedings
Sudhir K. Mendiratta, Ph.D.
William L. Kurtz
Budd L. Duncan, Ph.D.
Cortie J. Rolison, III
Olin Chlor-Alkali Products
As chlorine dioxide substitution levels increase and pulp mills reduce the carryover, disposal of the by-product salt cake from state of the art chlorine dioxide generators may become a serious issue for bleached kraft mills. Soda mills and small recycle mills do not use salt cake in the pulping process, and thus usually do not consider conventional chlorine dioxide generators as a viable option because of the large equipment required. By using pure chloric acid as the only raw material, the saltcake issue is eliminated and the chlorine dioxide quality is very pure. Since chloric acid reduction based generators are very compact and the need for handling multiple raw materials and by-products is eliminated, the number of pieces as well as the size of the equipment is reduced. In this paper we will discuss the results of the commercial scale demonstration of the chlorine dioxide generator which uses chloric acid as the only raw material. We will discuss unique design features of the generator and heat exchanger which can only become available because the generator does not contain sodium salts. The kinetics of the unique reaction chemistry is also presented. The reaction rate is 0.5 order with respect to the catalyst concentration and follows the Arrhenius Law with respect to temperature. An on-line continuous monitoring system was developed to analyze the generator contents. A new analytical technique was developed to measure the purity of the chlorine dioxide gas produced from chloric acid. The purity of chlorine dioxide was measured to be about 99.71% (standard deviation 0.07) as an oxidant. C1O2 solution was made by employing a compact absorption/scrubber/vacuum system. The chlorine dioxide solution concentration can be set within a range of 5 - 10 gpl with a precision of ± 0.5 gpl using an on-line C1O2 solution analyzer. This new catalytic reaction chemistry results in a simple, compact, and fast responding generator. The generator can come to full production rate in few minutes, thus significantly reducing, and in some cases eliminating, the chlorine dioxide solution storage requirements.
Product code: PULP95531
Author: Mendiratta, S.K., Kurtz, W.L., Duncan, B.L., Rolison, C.J.
