Continuous Manufacturing / Process Intensification is a hotly discussed topic in academic circles for the last decade, yet adoption of Continuous processes to the industry has not been as fast as we would have wished it to be. At Amar we encounter PI questions all the time and thought it would be apt to cover some of the common questions and misconceptions as a blog post as a set of FAQs. We are trying to make the questions particularly applicable to fine chemicals:
- Does continuous manufacturing only make sense for very large tonnage chemicals?
We find many processes today where even for kilo scale production our customers are going continuous. It is true that for traditional petrochemical or commodity chemicals, accepted wisdom was that continuous production only made sense for >10,000 tons per annum production scale. However, for high value products this limit is often much lower. Add in safety and toxicity concerns and continuous processes can often make sense at 100’s of kilos.
- Do all processes that are demonstrated to be continuous at lab scale up to production?
Be cautious about reactor designs that do not scale. There are many reactor designs we see which are elegant and novel but many of them cannot be scaled up yet to production sizes. Always ask yourself the question: If this works in the lab, can I make it work in the plant? One example is Shaker Hydrogenators (see photo below). This is a model we sell at Amar as well. Chemists love it and it works well in some situations for synthesis however ask any Engineer and it would be a nightmare to scale this design to production. Be aware of such pitfalls! For many situations our Amar PinchFLO or SlurryFLO reactors can mean much better scaling behaviour. (Of course, there are situations where a shaker could indeed be a good choice but always talk to an experienced engineer first if your goal is a large plant sized reactor).jpg)
- If I want to convert my batch processes to continuous, do I have to change process conditions?
It depends. In many cases, the Capex advantage of continuous processes kick in when Process Intensification is employed alongside the transition from batch to continuous. Higher T and P can lead to faster reactions and hence smaller reactors. Tubular or smaller reactors can deal with high pressures more economically than conventional vessels. Don’t ignore the possibilities to boost your reaction rates.
- How do I justify continuous processes to Management outside of the Capex advantage?
Remember it is hard to put a price to factors such as process safety. When a batch reactor explodes or has a runaway reaction the damages can be catastrophic. A toxic gas release from a continuous reactor may be orders of magnitude lesser than a batch reactor. The pressure waves can also be more easily contained. Don’t forget to factor in the “price” of reducing risk in any cost benefit analysis.
- Which reactions make for best targets for continuous processing?
We may be able to offer some heuristics. Start with the largest tonnage batch reactions you operate. All factors being the same the higher the value of the product it is easier to justify the capex. Particularly look at processes which use highly toxic intermediates or very exothermic reactions. Finally any process that uses high T or high P is a good target for conversion to continuous mode.
We hope some of these tips help in your transition from Batch to Continuous processes. Stay tuned for Part 2 of this blog post for more such tips. Meanwhile contact our team at Amar for a no-obligation discussion of your particular needs.
