Process Intensification FlexPlant - Recent Results Andrew Green Richard Jackson PIN Meeting 7 December 2004
The FlexReactor Key aspects of technology Re-configurable end linkages Injection point in turbulent zone 22 tubes of which 10 filled 8 part filled 4 empty tubes Kenics static mixers for low pressure drop Shell and Tube construction Hastelloy process sections Shell-side heat transfer enhancement
FlexReactor: Specifications • Operating Pressure Up to 20 bar • Operating Temperature -70 to 250oC • Throughput 1 to 100 lt/hr • Pressure Drop up to 15 bar • Heat Removal (typical) up to 15 kW • Exothermicity of reaction up to 750 KJ/mol • Residence time 2 secs - 30 mins • Size (l x w x h) 1000x300x400mm
Why? Just ahead of the “dead zone” allowing predictable scale-up.
Chemistry • Acid Base NeutralisationVery Fast. Exothermic (55kJ/mol). Aqueous. Single Phase • Biodiesel - Fatty Acid Methyl Ester2-phase to 3-phase to 2-phase mixing, mass transfer limited High and Low Viscosity mixing medium to long residence times (several minutes to hours) Low exotherm (~3kJ/mol) • Grignard Hydrolysis • Highly exothermic (~350kJ/mol), fast reaction Precipitation of fine solids + organic/aqueous mixture
Biodiesel Reaction Data Obtained: 3 kJ/mol exotherm 50°C Reaction Temperature 3.6 mins Residence time 3 bar pressure drop across all 22 tubes 97% complete reaction under these conditions Separation in 5 mins (cf. Intense protocol batch took 3hrs)
Grignard Hydrolysis Phenyl magnesium chloride reacted with water Highly exothermic Water/Organic/inorganic solid 3-phase system Fine precipitate forms high viscosity gel Fast kinetics Reaction Zone Critical
Grignard Hydrolysis Results: Start-up Critical!!! Shut-down Critical!!! Change of conditions - Unstable flow periods 350 kJ/mol reaction enthalpy 1.3 kW power output Overall success
Problems/Solutions Three main issues with the running of these trials 1 Pumping high and low viscosity liquids Pumps set for high temp work 2 Start up/Shut down for Grignard and associated pressure variations 3 Precipitation issues and safety of non-return valves
Conclusions The FlexPlant works! Start-up and Shut-down are non-trivial but workable Precipitations can be processed Approximate thermodynamic data can be calculated Approximate Kinetic data can be calculated Gives scaleable pressure drop and flow data Is it safe?
Conclusions (2) Process Intensification uses more extreme conditions Reaction rates are faster (not mixing limited) Little or no reagent build up Higher temperatures for a much shorter time (cf. Batch) Low inventories of reacting materials Devices capable of enormous pressures Generally more selective and higher purity than batch