CHLORINE DIOXIDE ANALYZER The DURALYZER-NIR Online Analyzer for Chlorine Dioxide Plant THE CLO2 PLANT CHEMICAL ANALYZER provides a reliable and accurate analysis of the critical chemicals in the R-10 (Solvay) process, with measurements every 5-10 minutes. In this particular process the overall Chemical Reaction formula is: 6NaClO3 + CH3OH + 6H2SO4 = 6ClO2 + CO2 + 6 NaHSO4 + 5H2O In a typical manual control scheme the ClO2 Production rate is controlled by the amount of Methanol feed to the Generator. By using look-up tables the Chlorate and Sulphuric Acid feeds are adjusted by the plant operator. As the Chlorate and Acid concentration vary, among any other process variables, the Generator outlet chemical composition is tested in the lab, typically every 2 hours. The goal is to maintain Chlorate concentration Molarity at 1-4 and Acid concentration at 7-10-Normal. Based on the lab results the make-up chemical feeds are adjusted accordingly. However, this very slow sampling frequency and the required production rate changes result in poor efficiency and chemical losses, especially the expensive Chlorate. The final control function is the water addition to the ClO2 Absorption Tower in order to maintain a constant, desired ClO2 concentration. THE UNIQUE DESIGN of this system and materials used have proven themselves in several other difficult Kraft Pulping and Recovery applications to be practically maintenance free, physically small and portable with easy installation and low installed cost THE TRANSMISSION CELL provides a means for NIR radiation to interact with the process sample while isolating the light source, fiber optic cable and spectrometer from the process. A typical transmission cell is composed of a body with appropriate sample inlet and outlet connections and a pair of optical couplers to deliver light to the sample and collect light after interaction with the sample. The optical couplers house a set of lenses to focus the radiation onto the tip of the fiber optic cable. The ends of the couplers in contact with the process sample have windows, usually sapphire, to provide a transparent optical path for the entering and exiting light as well as providing isolation from the process sample. Sapphire is usually the material of choice for the coupler windows due to its combination of hardness, chemical and heat resistance and transparency over a broad range of wavelengths. APPLICATION TECHNOLOGY Reliable and accurate chemical analysis of the ClO2 generation process is important for optimizing the efficiency and chemical consumption. Due to the complexity of this process, the Chlorate and Sulphuric Acid levels in the Generator need to be constantly monitored, after which an automatic control algorithm can then be fairly easily implemented. Even a small improvement in reducing the variations inside the Generator will result in a rapid payback of the DURALYZER-NIR System。 The final control function will be the accurate concentration control of the ClO2 to the desired target. Again, with frequent measurements this variation can be reduced resulting in more uniform Brightness control at your Bleach Plant. fanglong.hu@gmail.com |
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