cpp - Process technology for the chemical industry 02.2018

Additive manufacturing is currently en vogue. Which method is
used to make components that are suitable for glass lining?
Dr. Reinemuth: In additive manufacturing with metallic materials,
components based on 3D design data are produced in a powder bed
using one or more laser layers. The process referred to as selective
laser melting (SLM) can be compared with multi-layer build-up
welding under a protective gas atmosphere.
Which components can be produced in this way?
Dr. Reinemuth: Due to the manufacturing process, the production
constraints familiar from conventional production methods are to a
large extent no longer valid. For example, additively manufactured
channels no longer have to be circular, as is the case with drill
holes, but can assume a more or less arbitrary shape. The outer
geometry of components can also be freely designed within wide
limits, without having to consider accessibility restrictions for
processing tools. Thus, additive manufacturing is particularly
suitable for process engineering components with the following
characteristics:
• Complex external geometry, for example designed with flow considerations
in mind
• Internal structures and geometries in the form of channels or cavities
which can be used to transfer heat, for instance
• Several technical functions integrated in one component, so that
sealing and joining surfaces are avoided
• Varying material properties, such as deliberately introduced porosities
to accommodate catalysts or perform gassing processes
What other advantages does additive manufacturing offer?
Dr. Reinemuth: The pathway from the designed component or assembly
to the finished, usable version is significantly shorter and
swifter compared with conventional manufacturing. Components
are generally available sooner as a result. The component variations
„Modern selective laser melting in conjunction
with the traditional process of technical
glass lining can lead to innovative engineering
solutions.“
which are often required in the context of process optimisations,
such as different flow cross-sections, alternative dimensions, etc.,
can be additively manufactured quickly and affordably. In particular,
the production of small quantities up to the optimised single piece
is often faster and cheaper with additive manufacturing than when
using conventional methods.
What are the limits of the additive process?
Dr. Reinemuth: On the one hand, limits are imposed by the space
requirements of the selective laser melting facilities which are currently
available. Large components with dimensions exceeding
800 mm in one axis cannot be produced additively in one piece
today, yet they are easily manufactured using conventional joining
methods. At present, component sizes tend to be in the
280 x 280 x 300 mm range. On the other hand, the choice of materials
is still very restricted, although classes which are important for
process engineering applications, such as 1.4404 or 1.4301 stainless
steels and chemically resistant, nickel-based alloys like Inconel
Picture: Theletec
Dr. Jürgen Reinemuth, Managing Director & Partner of
Thaletec GmbH and Jurec dr. Juergen Reinemuth Consulting
728 or NiCr19NbMo, are already available. In addition, the regulations
and procedures that must be adhered to in order to additively
manufacture pressurised components needing certification accord -
ing to the Pressure Equipment Directive have not yet been universally
clarified and formulated.
Does Thaletec’s portfolio include any additively manufactured
components?
Dr. Reinemuth: Thaletec has already developed several products, including
some in collaboration with Jurec, an engineering consultant,
which are manufactured using metal 3D printing. One of these
products is a static mixer which mixes both liquid and highly viscous
media in a piping system in the smallest of spaces while simultaneously
heating or cooling them. In addition, Thaletec offers a
gassing nozzle with a partially porous surface for mixing gases in
liq uids as well as a high-pressure reactor with an integrated heating
or cooling coil.
What are the special features of this static mixer?
Dr. Reinemuth: The integrated system works on the principle of the
helical mixer with spiral mixing elements; it is hollow inside and
can be flowed through by a thermal fluid, such as water or thermal
oil. The wall is very thin to allow optimum heat transfer. The thinwalled,
stainless steel mixing elements are hollow inside and can
only be produced additively.
The individual elements are made additively to order and then
weld ed to the mixer. The connections at the pipe ends are also additively
manufactured and given a streamlined design. To compensate
for thermal expansion, an expansion joint (bellows) has been integrated
into one of the connection heads. The helical mixing elements
are dimensioned and designed to reflect the mixing task.
Additive manufacturing allows each helical mixing element to be
produced quickly yet individually.
What are the hallmarks of the 3D printed high-pressure reactor?
Dr. Reinemuth: The same applies, in essence, to the manufacture of
the high-pressure reactor as to the mixer. A chemically and high-
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