CHE 415: Chemical Engineering Laboratory Winter 2018 Plug FL

CHE 415: Chemical Engineering Laboratory Winter 2018 PLUG FLOW REACTOR

Conduct experiments using a continuous-flow plug flow reactor (PFR) for liquid-phase reactions, focusing on reaction kinetics involving ethyl acetate and sodium hydroxide solutions. Prepare concentrated solutions of ethyl acetate and NaOH, calibrate conductivity probes, and operate the reactor under carefully controlled conditions. Record temperatures, flow rates, and conductivities to analyze reaction behavior, ensuring safety protocols are strictly followed throughout the process.

Verify steady-state operation and reactor temperature uniformity, compare calculated rate constants with literature values, assess if the reactor operates under true plug flow conditions, and determine the residence time for 90% conversion based on experimental data.

Paper For Above instruction

CHE 415 Chemical Engineering Laboratory Winter 2018 PLUG FLOW REACTOR

CHE 415: Chemical Engineering Laboratory Winter 2018 PLUG FLOW REACTOR

The experimental setup in the CHE 415 Chemical Engineering Laboratory for the winter semester of 2018 involves a continuous-flow plug flow reactor (PFR) primarily designed for liquid-phase reactions. This reactor is situated in the northeast corner of JOHN 214 and is composed of a clear glass tube filled with glass beads to promote mixing and ensure laminar flow conditions. The reactor is inclined slightly to facilitate complete filling with liquid and to maintain consistent flow dynamics. It operates with two independent feed streams, each controlled by its own pump and reservoir, allowing precise regulation of reactant concentrations and flow rates.

Operational Safety and Preparation

In preparation for experiments, safety protocols necessitate the use of protective gear including eyewear, lab coats, aprons, face shields, and nitrile gloves, especially during handling concentrated solutions. The preparation of sodium hydroxide solutions requires cautious handling due to high exothermic dissolution and caustic nature, while ethyl acetate, being flammable and odorous, demands minimized vapor release and adequate ventilation. Pump calibration and flow rate validation are essential steps to ensure accurate residence times and reaction conditions. The conductivity probes are calibrated meticulously, employing standard solutions to guarantee reliable real-time measurements at the reactor outlet.

Experimental Procedure

Reagents are prepared by dissolving the appropriate masses of sodium hydroxide pellets in cold water, and ethyl acetate is used to prepare dilute aqueous solutions. Both solutions are stored in 17.5 L reservoirs. The feeding system employs pumps whose flow rates are calibrated against measured volumetric outputs at fixed pump settings, establishing a correlation that guides subsequent steady-state experiments. The reactor’s inlet flow rates are carefully controlled within specified ranges (e.g., ethyl acetate from 134 to 255 mL/min and NaOH from 115 to 236 mL/min) to achieve the desired residence times.

Reaction Kinetics and Data Collection

Key measurements include the reactor inlet and outlet temperatures, flow rates, and conductivities. Conductivity probes measure ionic species' concentration changes, enabling the determination of reaction progress and kinetic parameters. Steady-state operation is confirmed by consistent inlet and outlet concentrations over time, with multiple effluent samples taken at equilibrium. Thermal conditions are monitored continuously to verify isothermal operation; the external heater and temperature controller are used to maintain constant solution temperatures, typically within 3°C of the setpoint. Data collection includes documentation of all relevant parameters during each run for subsequent analysis.

Data Analysis and Reaction Rate Determination

Using collected data, the reaction rate constant (k) is calculated via kinetics models suitable for plug flow reactors. The experimental residence time, calculated from flow rates and reactor volume, correlates with conversion levels, particularly the time required for 90% reactant conversion. The analysis compares obtained kinetic parameters with literature values at similar temperatures, assessing model fit and reactor behavior. Additionally, the uniformity of temperature and flow conditions is evaluated to establish whether the reactor approximates ideal plug flow behavior or exhibits deviations such as axial dispersion, back-mixing, or incomplete mixing.

Operational Challenges and Verifications

Ensuring steady state involves monitoring parameters over time, confirming consistent effluent concentrations. Verifying isothermal conditions requires recording temperature data at multiple points. To assess whether the reactor truly operates under plug flow, tracer studies or residence time distribution (RTD) experiments can be conducted. These involve introducing a pulse of a tracer (e.g., a dye) and measuring its exit profile to detect deviations from ideal flow. The residence time for 90% conversion is determined by analyzing the extent of reactant depletion relative to residence times established from flow rates and reactor volume.

Conclusion

The experiment aims to deepen understanding of reaction kinetics in a controlled flow environment, with emphasis on precise control, safety, and data accuracy. The findings provide insights into the kinetic parameters, reactor efficacy, and optimal operating conditions for liquid-phase reactions involving ethyl acetate and sodium hydroxide, while demonstrating the importance of reactor characterization tools in chemical engineering process design.

References

  • Levenspiel, O. (1999). Chemical Reaction Engineering (3rd ed.). Wiley.
  • Fogler, H. S. (2016). Elements of Chemical Reaction Engineering (5th ed.). Pearson.
  • Turton, R., Cserhati, A., & Bailie, R. C. (2012). Analysis, Synthesis, and Design of Chemical Processes. Prentice Hall.
  • Seader, J. D., Sevilla, E., & Henley, E. J. (2011). Separation Process Principles. Wiley.
  • Bailey, J. E., & Ollis, D. F. (1986). Biochemical Engineering Fundamentals. McGraw-Hill.
  • Wills, R. G. (2010). Process Flow Modeling. In Wiley Encyclopedia of Chemical Biology.
  • Himmelblau, D. M., & Biswas, S. (2015). Process Design and Simulation. Prentice Hall.
  • Greenshields, T., & Liao, B. (2018). Reactor Instrumentation and Control. Springer.
  • Turcotte, R., & Athans, M. (2015). Reactor Safety: Principles and Practice. Elsevier.
  • Choi, S., & Jung, K. (2019). Advances in Flow Reactor Technologies. Chemical Engineering Journal, 375, 121968.

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