FLOW CHEMISTRY
The path from flow chemistry to continuous manufacturing
Dr Kevin van Eeten of Flowid discusses why excellent lab results sometimes reach plant implementation – and why they sometimes do not
Fully modular and Hastelloy continuous manufacturing skid for API production A
decade ago , during my first project at Flowid as a process engineer doing process development work , I did my first lab to plant project . It was a traditional batch process involving a multi-phase reaction ( gas / liquid / liquid in this case ), where the gas was a highly toxic reagent .
Poor mass transfer led to large excesses of the toxic gas being used and we developed a novel process in our proprietary SpinPro Dynamic Flow reactor . The project was a big success in the lab and , in my youthful enthusiasm , I thought this would quickly lead to the order of our first commercial-scale production plant . However , it took another two years for the project to materialise into a continuous manufacturing plant . In hindsight , I know now that this is certainly not an unrealistic timeline . In fact , it is very typical and a particular level of thoroughness is needed in order to carry a successful process from the lab into a full-scale plant . Back in the days as a freshly graduated engineer , I only thought in terms of mass transfer , heat transfer , residence time , optimisation studies , etc . But there is a lot more to it than that .
Key factors might include altering the company ’ s shift structure to accommodate the needs of a 24 / 7 continuous manufacturing site , assessing the return on investment ( ROI ) – how many years will it take to start making a profit with this new plant ? Or is there perhaps a pressing safety issue that makes implementation essential to guarantee business continuity ? Is there an alternative patch or quick fix that can be applied to a current less-than-optimal batch process so we can continue for , say , another year and then outsource this troublesome reaction step ?
Complexities beyond engineering
All these issues are in themselves valid questions beyond the engineering perspective and each is just as important in determining the viability of investing in the new , intensified process . Fortunately for Flowid and this ( then ) youthful engineer , this particular process did indeed see the light of day in a continuous manufacturing plant that has been in operation since 2016 . However , success is not always guaranteed .
I also remember another flow chemistry project in which we performed a butyl lithium reaction in our SpinPro . The excellent heat transfer and mixing intensity allowed for the process to be performed at ambient conditions , completely eliminating the need for a cryogenic installation . Selectivity was even better at these higher temperatures than previously thought possible from batch lab trials .
With the small internal volume of the reactor , an intrinsically safe process for continuous manufacturing could thus be designed that met every single criterion for capacity , yield , selectivity , and use of energy and
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