Optimisation on the benchtop
15 Jan 2000
Scaling up a chemical reaction is the link between the research chemist and the chemical engineer. The focus of the research switches from products and energy levels to pressure and explosion prevention. Consulting firm Arthur D Little has now developed a device to make scale-up more efficient, and also to improve plant safety procedures - all from the bench-top.
The automatic pressure-tracking adiabatic calorimeter (APTAC) is a lab-scale, computer controlled reactor. It monitors the changes in pressure and temperature occurring during a chemical reaction, which gives engineers enough information to design operating and emergency systems for a full-scale plant, says the company. It can also be used to test the thermal stability of chemicals or mixtures.
The system can track heat generated by reactions at rates from 0.04-400degC per minute, and can handle pressures from vacuum to 2000psia. APTAC contains an unusually thin-walled reaction vessel inside a pressure balancing calorimeter, so the reaction heat cannot escape; this means that the instrument can give very accurate temperature readings. Also, the large size of the reactor vessel allows reagents to be added while reactions are in progress, so designers can evaluate how to inject quenching agents into a full-scale batch or semi-batch reactor undergoing a `runaway' reaction.
Moreover, the reactor can be vented at any time, and the vented material can be collected and analysed. Engineers can use this information to work out the best size for a vent on a production-scale reactor, and to design the best procedures for collecting and treating effluents from emergency venting.
The APTAC was developed to help cope with new regulations governing plant safety, explains Arthur D Little chief executive Charles LaMantia. `Regulatory pressures in the US and Europe are forcing companies to provide thermal stability data and the best emergency relief systems for all process chemistry,' he says.
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