This article shows that near-infrared spectroscopy (NIRS) can be used efficiently for the simultaneous in-line and in situ monitoring of monomer (methyl methacrylate, MMA, and butyl acrylate, BuA) and polymer concentrations in the reaction medium during seeded semibatch emulsion copolymerizations. A series of actual reaction experiments was planned to allow the proper obtainment and selection of calibrating samples. Partial least squares (PLS) was used to build three independent calibration equations in the range of 1100 -1900 nm, which were used to successfully monitor some disturbed reactions in-line.
A control algorithm is designed and implemented experimentally for the simultaneous closedloop control of the composition and number-average molecular weight of a copolymer latex. The developed control algorithm is based on a predictive control strategy and uses an iterative dynamic programming (IDP) algorithm for process optimization and design of the optimum dynamic trajectories at each sampling time. The control of semibatch methyl methacrylate (MMA) and butyl acrylate (BuA) emulsion copolymerizations is used to illustrate the approach. Monomer compositions and polymer holdup are measured in-line and in situ with the help of near-infrared spectroscopy (NIRS), while average molecular weights are inferred with the help of a process model. The manipulated variables are the flow rates of three distinct feed streams, which contain known concentrations of both monomer species and of a chain-transfer agent. The results obtained when different process disturbances are introduced, such as feed failure and addition of unknown amounts of inhibitor to the reactor charge, show unequivocally that NIRS can be used successfully for the in-line and in situ simultaneous control of copolymer composition and average molecular weights in emulsion copolymerizations.
Presently, the only offshore project for enhanced oil recovery using carbon dioxide, known as CO2-EOR, is in Brazil. Several desk studies have been undertaken, without any projects being implemented. The objective of this review is to investigate barriers to the implementation of large-scale offshore CO2-EOR projects, to identify recent technology developments, and to suggest non-technological incentives that may enable implementation. We examine differences between onshore and offshore CO2-EOR, emerging technologies that could enable projects, as well as approaches and regulatory requirements that may help overcome barriers. Our review shows that there are few, if any, technical barriers to offshore CO2-EOR. However, there are many other barriers to the implementation of offshore CO2-EOR, including: High investment and operation costs, uncertainties about reservoir performance, limited access of CO2 supply, lack of business models, and uncertainties about regulations. This review describes recent technology developments that may remove such barriers and concludes with recommendations for overcoming non-technical barriers. The review is based on a report by the Carbon Sequestration Leadership Forum (CSLF).
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