ACOMP “front end

The ACOMP front end is the ensemble of pumps, mixing chambers, filters, and conditioning steps that prepare the continuous highly dilute and conditioned stream and deliver it to the detector train. Lag times between withdrawal and detection are typically from 10s to 100s of seconds, with... 

Advantages of ACOMP include its versatility as a generalized approach, its ability to make fundamental measurements without recourse to empirical models and calibration, its capacity for providing a data-rich stream of complementary information from multiple independent detectors, yielding multifaceted characteristics of polymerization reactions, and its use of the front end to extract, dilute, and condition a sample stream that allows sensitive detectors to provide reliable data without exposing them to harsh reactor or sample conditions. Disadvantages include the mechanical complexity of the front end, the delay time between a continuous fluid element s extraction from the reactor and downstream measurement by the detector train, and a small but continuous waste stream. ACOMP is more invasive than probes that can be placed at an outside reactor window, but are no more invasive than in situ probes, in that in either case access to the reactor contents is required. 

FIGURE 11.1 A simplified schematic of an ACOMP system, showing the front end used for extraction, dilntion, and conditioning of reactor content, and a typical series of detectors through which the dilute, conditioned sample continuously flows. 

Formalism for Combined Reaction and Semibatch Flow The following summarizes the ACOMP approach presented in [38]. Expressions were derived for the concentration of monomer and polymer in the reactor, while reactions are occurring, when N solutes in solution are allowed to flow into the reactor, each at their own rate, which need not be constant, such that solute s has caused a change in reactor volume at time t of AVft), where Qft) is the instantaneous flow rate of liquid from a reservoir containing component s into the reactor. In the following, q is a constant withdrawal rate from the reactor q (ernes ) that feeds the ACOMP extraction/dilution/conditioning front end. 

In sharp contrast, in the industrial environment, ACOMP measurement repeatability, system reliability, and continuous, problem-free operation are the main requirements. The number of detectors is chosen to be the absolute minimum needed to provide the most valuable characteristics to be monitored. Oftentimes, the characteristics to be measured are a small subset of what an R D ACOMP is aimed at for example, an industrial system may just be needed to monitor monomer conversion and polymer reduced viscosity. In light of these goals, both the front-end and detector components are chosen with ruggedness and reliability in mind. 

Automation of the entire ACOMP system will be an important focns of the industrial version. Monitoring and controlling the many different parts of the front end and detectors will be achieved throngh an on-board programmable logic controller (PLC) or other type of hybrid controller. This on-board PLC will monitor and control the entire system. Table 15.2 describes to some extent the PLC control of the system. 

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