Page 184 - CW E-Magazine (16-4-2024)

Special Report

Making profits flow: Engineering aspects of flow

technology

IntroductIon their drivers get intensively trained
lthough continuous operations to get the most out of their machines. DR. VISHWANATH DALVI
have been the mainstay of bulk NASCAR design teams often include Consultant-Flow Technology
Achemical production for nearly mechanical engineers with Ph.Ds from Amar Equipment
a century (think sulphuric acid, the best universities in the world and Faculty in Chemical Engineering
ammonia, methanol, etc.), the chemistry- get compensated at rates commensurate Institute of Chemical Technology
driven fine-chemicals industry has long with their expertise. Email: vh.dalvi@ictmumbai.edu.in
been reluctant to follow suit in the past
decade; however, “flow chemistry” has Similarly, with batch processing, DR. CHANDRAKANTH GADIPELLY
captured the imagination of chemists, it is relatively quick to get production Principal Research Scientist
with many syntheses being demonstra- going with standard engineering solu- Flow Chemistry
ted in continuous mode instead of in the tions that have already been tried and Amar Equipment Pvt. Ltd.
traditional batch-stirred flasks(1). This tested over many decades and opera- Email: chandrakanth.Gadipelly@
has sparked the interest of fine-chemical ted by staff who can mostly learn on amarequip.com
manufacturers in continuous (or flow) the job. This is the great advantage of
processing. While many have already batch processing when rapidly putting expertise to the full since, at least to date,
invested considerable effort and funds products into the market or responding there have yet to be standard solutions.
in flow processing, most fine chemical to changing market demands. A stirred Each system must be designed from the
manufacturing is still conducted in the vessel is a multi-purpose reactor. Astoni- ground-up using first principles.
traditional batch mode in large, stirred shingly, chemistries as varied as those
vessels. The benefits of flow processing involving n-butyl-lithium, Grignard Operating a flow process is much
over batch are widely recognized by the synthesis, nitration, hydrogenations, simpler and requires less manual inter-
US FDA, which issued guidelines(2). oxidations, leaching, and fermentation vention than the corresponding batch
It will become increasingly unten- can be effected in practically the same process. It allows tighter control of
able for manufacturers to continue in reactor configuration. Thus, in batch expenses, reliable and reproducible pro-
the business-as-usual practice of batch processing, the chemistry is force-fit to duct specifications, and can give advance
processing. Those who transition to the reactor. intimation of process “drift.” Flow pro-
flow earlier will reap the pioneers’ pre- cesses are in keeping with the “just in
mium through significantly increased Since most such fits are sub-opti- time”(4) philosophy that has so revo-
safety, stable operations, intensified mal, considerable profitability gains are lutionized automobile manufacturing.
processing, and low variability, ulti- obtained by transitioning to a more speci- However, the supporting infrastructure
mately translating to higher profits and fically designed configuration. Flow must be meticulously maintained with
market presence. This article is written processing substantially involves using little tolerance for electricity, utility, or
by workers intensely involved in batch- a reactor designed around the chemis- equipment failures, or drift in specifica-
to-flow transitions. It aims to provide a try, one of the main reasons it can win tions of the raw materials. Further, the
realistic view of the benefits and chal- profitability gains that batch-processing startup and maintenance-shutdown of
lenges of transitioning and a genera- cannot. such a process involve highly trained
lized roadmap to effect such a transition. and experienced engineers to be on-
Flow processing requires consider- site almost continuously for as long as
Flow philosophy ably greater engineering inputs than a couple of weeks at a time, and, given
Flow processing is to batch pro- a stirred-tank-based process: inputs the opportunity cost of the halt in pro-
cessing is what NASCAR(3) racing is not just from chemists and chemical duction, should be planned out in detail
to regular driving. Whereas a person engineers, but also from mechanical beforehand and executed flawlessly.
can buy and drive a car with minimal engineers, instrumentation and control
training, NASCAR teams modify cars engineers, fabrication experts, and eco- Transitioning to flow is more than just
extensively for speed and control, and nomic experts. Further, it tasks their a matter of acquiring new technology or

184 Chemical Weekly April 16, 2024

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