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1 L reactor

stirrer. transducer. oil jacket (oil circulating). 1 L reactor. Itaconic acid in toluene used as a model system. A broad band transducer was attached to the wall of a jacketed glass reactor. Transducer (impulse response test). cubic spline of average of 20 spectra.

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1 L reactor

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  1. stirrer transducer oil jacket (oil circulating) 1 L reactor • Itaconic acid in toluene used as a model system A broad band transducer was attached to the wall of a jacketed glass reactor.

  2. Transducer(impulse response test) cubic spline of average of 20 spectra Although the transducer has a broadband response, there are frequencies where the sensitivity is poor (around 50 and 200 kHz).

  3. itaconic acid in toluene Vessel, amplifier and transducer(impulse response test) cubic spline of average of 10 spectra The overall response of the system is influenced by the filtering effects of the vessel and amplifier. This slide shows an overlay of the system response and the signal obtained for itaconic acid particles stirred in toluene.

  4. Itaconic acid in 500 mL toluene Stir rate = 250 rpm Oil temp = 20 °C As the amount of particles increases, there is a linear increase in the magnitude of the signal across the frequency range.

  5. Effect of particle size - spectra 20 g of itaconic acid Stir rate = 250 rpm Oil temp = 20 °C When the same amount of itaconic acid is used, but of different particle size range, the signal does not change significantly in the region 200-300 kHz. It should be possible to extract both particle concentration and particle size information from broadband acoustic signals of this type.

  6. Heterogeneous reaction • Esterification of itaconic acid with 1-butanol in toluene used as a model heterogeneous reaction The esterification of itaconic acid was monitored using passive acoustic emission. The ester products are soluble in toluene where as the itaconic acid is only sparingly soluble.

  7. Total ester concentration - HPLC Itaconic acid (>500 mm to <853 mm) 1:1, 70° C Progression of the reaction can be followed by extracting samples for analysis by HPLC; this is not particularly convenient.

  8. Acoustic emission – broadband transducer Itaconic acid (>500 mm to <853 mm) 1:1, 70° C When itaconic acid particles in the range stated were reacted, the acoustic signal in the 60-585 kHz region decreased during the reaction (which was deliberately sub-stoichiometric).

  9. Change in itaconic acid particle size Itaconic acid (>500 mm to <853 mm) 1:1, 70° C By comparing changes in the ratio of the peaks in the regions identified in slide 5, it was possible to monitor changes in particle size during the reaction. All of the data (Acoustic and HPLC) indicates that the reactions reached an end point around 80 mins.

  10. Conclusions • Signal transmitted through and around vessel wall  not just from particulates close to the transducer • Between run repeatability affected by variability of transducer attachment • Acoustic signals sensitive to temperature, stir rate, and particle size and concentration • Broadband signals contain both particle size and concentration information • Mean particle size determined for mixtures • Decrease in particle size detected during reaction • Further work required to separate the two effects

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