Closed Loop Control of ClO2 Generator Using FT-NIR Analyzer, 2009 TAPPI Engineering, Pulping, Environmental Conference

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The control of a ClO₂ generator has relied mainly on manual analyses of generator liquor and the use of temperature as an indication of acid concentrations. Due to the highly corrosive and hazardous environment of an R8 ClO₂ generator, manual sampling poses further risks to testers and operators in the vicinity. At Catalyst Paper’s Crofton mill, a project was carried out to install the FT-NIR analyser for automated at-line measurements of acid and chlorate strength. The measurements were then utilized for closed loop control of the R8 generator and has allowed for reduction in manual testing, improved efficiency. Recently, the measurements of sesquisulfate solids content and residual ClO₂ has been added to the FT-NIR and these results are used for forecasting potential generator problems. The paper will discuss the results obtained from the FT-NIR ClO₂ generator analyser for acid and chlorate strength as well as the sesquisulphate solids and residual ClO₂ concentration dissolved in the liquor.