Professional Papermaking 1/2022

CAS touch! Charge analyzing system. FPA touch! Fiber Potential Analyzer Reliable control of the wet-end in the production process Testing Technology for Papermaking 4.0 Papermaking is a complex and dynamic process with many possibilities of adjustments and influences in a complex production plant. By high level automation and production monitoring it is possible to increase the efficiency of the process. Besides other parameters, also monitoring the charge environment – the particle charge and the zeta potential – in the wet-end of the paper making process improves the production efficiency and is in such complex systems extremely important. Unclear charge conditions can lead to losses in quality of the base or the finished product, disturbances of the production process and higher cost for additives. A permanent control is especially important if different chemical additives are used, which are supposed to ensure a well-functioning production process and certain quality requirements of the base paper and finished product. Having information about the charge conditions available helps to optimize the dosage of additives throughout the complete wet-end process and allows the mill technicians and engineers to get a good overview of the status. Test devices, which provide this necessary information, are for example the CAS touch! Charge Analyzing System and the FPA touch! Fiber Potential Analyzer. These devices are used in the lab and are already well-known within the paper industry. However, as the automation and digitalization play an increasing role in the paper and board industry, as in most other industries too, automatic measurements, which provide reliable and accurate real-time data of the process, get more and more important to meet sustainable, ecological and resource-efficient requirements. Such online measurements have several advantages at the same time: the results are available in real-time, which allows an immediate intervention in the process, if the process is not running well or quality issues occur. These real-time data cannot only be transferred to the process control system; they can also be transferred to any data cloud anywhere in the world, which enables networked handling of issues by experts, who do not have to be onsite. FPA touch! Fiber potential analyzer An online device, which has been introduced to the industry just recently, is the emtec FPO Fiber Potential Analyzer Online. The device measures the zeta potential of the fibers directly at the paper machine. The automatically measured zeta potential is an important parameter for the level of interaction of the fibers and the chemicals that are added to the process. The measuring principle of the online device is identical with the measuring principle of the laboratory instrument. Both determine the zeta potential of fibers in suspensions in the wet-end area of paper and board machines, using the equation from Helmholtz and Smoluchowski. The sample is sucked into the suction tube by the vacuum in the measuring cell. A fiber plug develops in front of the screen electrode and is solidified during the stabilization period. For technical reasons, an oscillating electrolyte flow is generated through the fiber plug by means of a periodically changing underpressure. The counterions on the fiber surface within the plug are sheered away and generate a streaming potential, which is gathered by the electrodes. The zeta potential is calculated by the Helmholtz and Smoluchowski equation from the streaming potential, the conductivity, the pressure difference and a constant. Pictures: emtec Professional Papermaking 1.2022 56 AUTOMATION