Jonildo dos Santos Silva

In the present paper, a comprehensive review of methodologies for the optimal placement of measurement devices in chemical processes, commonly referred to as the sensor network design problem (SNDP), is presented. The SNDP is a combinatorial optimization problem of paramount importance in process design, monitoring, control, and data reconciliation, as sensor placement directly affects estimability, precision, reliability, and fault detectability. In addition to surveying solution strategies for SNDP, this review examines the closely related variable classification problem, which constitutes a fundamental building block in the systematic development of sensor networks. The evolution of the field is analyzed, highlighting early structural search approaches, subsequent optimization-based formulations relying on relaxation and decomposition techniques, and heuristic and metaheuristic strategies. The strengths and limitations of these methodological classes are discussed with respect to problem size and computational complexity. Moreover, this review identified a novel strategy to solve SNDPs based on machine learning algorithms. Finally, future research directions are outlined, emphasizing the growing need for scalable frameworks capable of addressing increasingly large and automated industrial systems. As computational capabilities continue to advance and process plants transition toward highly digitalized environments, research efforts devoted to efficient and robust SNDP methodologies are expected to intensify. In this context, Large Language Models (LLMs) can play a transformative role.

This work presents a comprehensive literature review on Continuous Oscillatory Baffled Reactors (COBRs), surveying advancements from 2014 to 2025. Although widespread industrial adoption of COBRs remains a future goal, the analysis reveals the significant maturation of COBR technology, marked by a growing exploration of novel applications—particularly in enabling the transition from batch to continuous manufacturing. The review synthesizes both theoretical and experimental studies, categorizing them into key thematic areas to provide a clear and accessible overview of the field. The study concludes by identifying critical research gaps and offering a perspective on future directions, thereby aiming to guide and inspire subsequent research endeavors in overcoming the barriers to commercialization.

In the present work, a phenomenological model built to represent the suspension polymerization of vinyl chloride in a continuous oscillatory baffled reactor is presented for the first time. Following a previous work (Silva et al., Chemical Engineering Science, 288, 119845, 2024), a tanks‐in‐series model is employed to represent the reactor and a backflow stream is also considered to simulate backmixing. The intrinsic heterogeneous behavior of vinyl chloride polymerization adds model complexity in comparison to vinyl acetate polymerization reported in the literature. Moreover, the stronger gel effect also makes the temperature control difficult since a higher number of cooling jackets is required to keep a uniform temperature profile. The influence of residence time on reactor operation is investigated. Furthermore, the effects of initiator type and injection points on the polymerization rates and polymer properties are evaluated and shown to influence the process operation significantly.

In the present paper, a mathematical model is built and implemented to describe the trajectories of mass inventories, pressures and polymer properties with emphasis on final particle size distributions of industrial scale poly(vinyl chloride) suspension polymerization reactors. The model comprises the mass balances, statistical moment balances, equilibrium relationships and population balance equations. A discretization scheme is employed to transform the integro-differential equations resulting from the population balance model into a system of differential equations. The obtained results show, for the first time, that classical breakage and coalescence kernels described in the literature can provide very good fittings of actual industrial scale data when coupled with proper parameter estimation procedures, so that the proposed model is able to represent the available operation data with good accuracy at distinct conditions. Particularly, it is also shown that the use of a top condenser for control of the reactor temperature can lead to changes of parameters that control the particle size distributions.

Poly(vinyl chloride) (PVC) resins constitute the third most important plastic materials available commercially, in terms of worldwide volume production, and can be manufactured through several polymerization mechanisms, including free radical, ionic and redox polymerization processes. Approximately 80% of the worldwide commercial PVC production is performed through suspension polymerization processes in batch mode, due to intrinsic problems of continuous suspension polymerization processes, such as polymer incrustation in reaction vessels, transport equipment and pipes. For this reason, the present review provides an extensive bibliometric survey, including papers and patents, on attempts to develop continuous polymerization process technologies for PVC manufacture. Particularly, the present survey characterizes the degree of maturity and the main bottlenecks of continuous PVC processes that have been frequently overlooked in the technical literature.