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Continuous flow reactors can provide many benefits over batch processes. This article answers why and how
Small chemical reactors offer a number of benefits compared to large reactors, such as better heat transfer and mixing. While small batch vessels are impractical at the industrial scale, continuous flow reactors can provide the benefits of small physical size without the practical difficulties of multiple vessels. This article considers the four basic needs of flow reactors (volumetric capacity, heat transfer, plug flow and mixing) and how they influence choice of equipment.
Flow reactors
A small chemical reactor has a higher ratio of heat transfer area to working volume than a large reactor. It can also deliver more mixing energy per unit volume without bending the agitator shaft. Since the outcome of most chemical reactions is linked in some way to mixing or heat transfer (or both), small reactors have inherent advantages over large ones. Depending on the reaction type, these advantages can contribute toward substantially lower capital and operating costs. Small batch vessels, however, are impractical at the industrial scale since hundreds or even thousands of process cycles would be required for commercial throughputs. The solution to this problem is to use a flow reactor. This is a channel or series of mixed stages in which process materials react as they flow through it. It is analogous to a series of small, stirred batch vessels on a conveyor belt. A flow reactor provides the benefits of small physical size without the practical difficulties of charging and emptying multiple small vessels.
Historically, flow reactors have been more common in bulk chemical processes where the problems of vessel size are most acute. With growing pressure on chemical manufacturers to meet ever-tougher cost and regulatory targets however, the range of applications for flow reactors has started to expand rapidly.
Flow reactors are not new technology, but many of the applications they are now being developed for are new, and as such progress is confronted by the usual adoption problems of market resistance, availability of the right equipment and lack of user knowhow.
User knowhow is arguably the biggest hurdle to progress since most engineers and scientists were trained in batch methods and have had little experience with flow technology. While...