Thread Content
How to achieve automated control of the effective chlorine content in hypochlorite production. The effective chlorine content, free alkali content, and sodium hypochlorite concentration are important quality indicators in the chlor-alkali industry, as they reflect the degree of completion of the chemical manufacturing process. The level of automation equipment in the production processes of China’s chemical industry is generally low, remaining at the stage of offline analysis, manual adjustments, and experience-based control. This results in low production efficiency, high resource consumption, and unstable product quality, thereby hindering the development of the chemical industry. The application of online monitoring technology enables manufacturing enterprises to monitor the operation of reaction units in real time, based on the real-time changes in effective chlorine content, free alkali content, and sodium hypochlorite concentration. Controlling product quality by promptly adjusting the feed formula or other operating conditions plays an important role in improving a company’s economic efficiency. Online sequential measurement technology is derived from the inference estimator in inference control; it involves collecting certain easily measurable variables (also known as secondary or auxiliary variables) and constructing a mathematical model that uses these easily measurable variables as inputs to estimate the difficult-to-measure primary variables (also known as dominant variables). According to the laws of fluid mechanics, when a fluid flows through a vertical pipe, the pressure difference between any two measurement points consists of two components: the static pressure difference and the frictional resistance. The static pressure difference, with the positions of the two measurement points remaining constant, depends on the concentration (density) of the fluid. To accurately obtain the concentration information of the medium from the differential pressure output signal, it is necessary to remove the frictional resistance signal from the measured differential pressure signal. For stationary fluids, there is no need to consider frictional resistance, which further improves detection accuracy. In addition, errors caused by changes in the dielectric temperature and ambient temperature will also be compensated for.