Realtidsanalys av kiselsol

Traditional measurement techniques are often conducted by mounting instruments inside pipes or are in other ways introducing them to the process. This can be problematic when handling process fluids that are dangerous, cause precipitations or are in other ways hard to handle and might give misleading results. One way to avoid these problems are using the measuring technique Active Acoustic Spectroscopy. Active Acoustic Spectroscopy is conducted by measuring sound signals attenuation through process fluids. The instrument for this is called Acospector and is produced and marketed by the company Acosense. The Acospector is noninvasive and can be installed and maintained without needing to stop the manufacturing process. Through multivariate data analysis of the spectrums from the instrument, vital information is revealed about the process. The project “Real Time Analysis of Silica Sol” was conducted during 10 weeks as a part of Acosense development plan for new application areas. The project evaluated the possibility of real time analysis of specific surface of silica sol at a new position at Akzo Nobel Pulp & Performance Chemicals (former known as Eka Chemicals). The objective of the project was to validate Acosense technique for the new position and specific surface. This was to be done by collecting as good calibration data as possible and create a model which could predict properties of a validation data set. Another objective was to evaluate Akzo Nobel’s lab methods for analyzing specific surface. A large part of the work was to collect calibration samples from the process and analyze them for specific surface, pH, Na2O-content, turbidity, density, viscosity and conductivity. A spectrum was also collected for each calibration sample with the Acospector. These spectrums were then treated with Direct Fourier Transform and analyzed and correlated with lab results by multivariate data analysis. Important parameters for comparable results are carefully and consistent conducted analysis, the pH-electrodes sensitivity and the time that passes between the out take of the sample and analysis. Evaluation of Akzo Nobel’s lab methods for specific surface gave no suggestions to changes in the lab instruction even though the projects results and factory operators’ results deviated. The results from the multivariate analysis of the spectrums and lab results showed after an initial validation with collected data to give a good model for prediction of specific surface. The work to develop the model was done by identifying some observations that deviated from the others. These could after further review be excluded from the data set. It is recommended to conduct further validation of the model with a new data set that hasn’t been used to build the model. When this is done, it would be proved how useful the model is for the application of real time analysis of specific surface at Akzo Nobel. For new installations of the Acospector similar projects, with targeted operations for collecting large amounts of lab samples conducted in the same way, seems to be a good way to ensure good quality of the calibration data. Thoroughly and consistent conducted analyzing methods are crucial to limit the error in the calibration data and produce good results during a short period of time.