(343g) Novel Technology for Studying Mixing and Reaction State Using Electrical Resistance Tomography

The accurate determination of endpoints of reactions is crucial in the process industry, directly influencing the final product quality or downstream separation processes. Many existing technologies focus on offline sample testing. Due to this kind of testing being a single time point and a single location, in most cases, confidence in the outcome needs to be gained through repeated testing using multiple locations. Electrical resistance tomography (ERT) has been applied in a wide range of scientific and engineering fields, such as geophysical study, clinical diagnosis, chemical or mineral process measurement, and process optimization. ERT is usually used to collect data on the processes in vessels and pipes. In this research, ERT uses an array of 16 electrodes located equidistant in a layer around the inside of the vessel. As fluids flow past the measurement plane, conductivity is measured in the 2D plane. Its ability to do online real-time measurements in a plane and without the need to draw samples from the reaction vessel made the data collection much easier compared to existing technologies. The information on the state of the reaction and the fluid mixing can be extracted from the ERT measurements.

Our ERT system can collect more than 1000 datasets per second with 104 data points per dataset. These real-time datasets contain rich information that can be extracted by data processing. The test case of titration is currently done in a small vessel that acts as a batch reactor, which provides the best similarity to the future application. 0.1 molar hydrochloric acid is titrated with 1.0 molar sodium hydroxide to produce sodium chloride. This reaction has an extensive conductivity range and provides the best case for identifying the reaction's endpoint. Figure 1 shows an online real-time ERT measurement to detect the titration reaction's endpoint at 88.0 seconds. When compared to other methods to find the endpoint of the reaction, it can be seen that the start of the upward trend after the dip matches up closely to those measured endpoints. Additionally, more accurate time points can be obtained by the ERT system comparing to other methods. Another significant benefit of the 2D planar measuring is the ability to monitor the fluid mixing. Figure 2 reveals a location with slower mixing relative to the rest of the vessel. Knowing where these spots exist allows for monitoring the products for any potential defects due to this imperfect mixing. The future work is testing larger-scale vessels and a variety of chemical reactions. This novel technology can be potentially used in large reactors where visibility, testing access, or conditions restrict access to the vessel, such as higher pressure and temperatures.