cpp – Process technology for the chemical industry 01.2019

cpp
PLANTS, APPARATUS, COMPONENTS
Chemical resistant diaphragm pumps for scale-up in chemical process technology
Scalable vacuum supply
We’ve all been there. A process works well in the laboratory, yet issues arise during
scale-up to production size. Thanks to seamless vacuum technology from Vacuu brand,
this may very well be a problem of the past. Individual pumps and modular vacuum
systems with pumping speeds up to 120 m 3 /h allow a stable scale-up process.
Mini and pilot plants in the chemical industry
are at the interface between lab and
production scale. Numerous chemical processes
such as distillation, evaporation, drying,
extraction or filtration are performed
under vacuum. During scale-up, the vacuum
technology has to be adapted accordingly –
ideally without sacrificing proven advantages
from the laboratory like chemical resistance,
oil-free vacuum, durability or precise
vacuum control. On the laboratory
scale, chemical resistant diaphragm pumps
are established as the go-to technology for
the aforementioned applications. A lot of
processes are operated at pressures between
1 and 500 mbar, falling well into the working
range of diaphragm pumps. Mini and
pilot plants usually require significantly
higher pumping speeds than laboratory
scale applications, often between 15 and
100 m 3 /h. The other requirements mostly
remain unchanged. So, why switch technologies
when something tried-and-tested is
available?
Apart from the obvious parameters like
pumping speed and ultimate pressure, other
factors need to be considered in order to
achieve the optimum layout for a vacuum
supply in the chemical industry, for
example chemical resistance, the use of utilities,
energy and maintenance costs. Taken
together, in the long run they affect process
reliability, availability and the total cost of
ownership.
Appropriate measuring and control devices,
which must be designed to be as chemically
resistant and as robust as possible, are
necessary to monitor and control the process
vacuum. Many of the solvents commonly
used in chemical plants are flammable
at atmospheric pressure and have
high vapour pressures, making them prone
to forming explosive mixtures with air. In
these cases, explosion protection, too, becomes
an important factor.
Pictures: Vacuubrand
From small to large: chemical resistant vacuum pump with pumping
speeds all the way up to the modular VAC 24seven system
Oil-free pumps enable clean vacuum
In chemical processes, not only air and
water vapour are pumped but usually also
aggressive vapours, so that vacuum pumps
with high chemical resistance are a must.
Due to the systematic use of fluoropolymers
in all wetted areas, chemistry diaphragm
pumps meet this requirement perfectly.
Further more, these pumps are exceptionally
tol erant of condensate. Vacuubrand manu -
factures all heavy-duty components such as
head covers and diaphragm clamping discs
with stable metal cores combined with a
thick, diffusion-tight overmould.
The proven PTFE sandwich design of these
diaphragms guarantees high durability and
long service intervals. Depending on the
application, the diaphragms typically only
54 cpp 01-2019