Surface World March 2020 Surface World March 2020 | Page 26
INDUSTRY NEWS
Babcock Wanson produces
world’s first 1MW gas fired
supercritical water heater
Babcock Wanson has
produced a bespoke TPC SW
1MW gas fired Supercritical
Water Heater, which operates
at 275 bar pressure and
reaches a temperature of
490°, for Promethean Particles
as part of its nanoparticle
production process.
Promethean Particles has built the
world’s largest continuous multi-material
nanoparticle manufacturing plant, based in
Nottingham, producing in excess of 1000
tons per year. Its unique reactor design
allows for continuous (as opposed to batch)
production and flexibility, enabling it
to produce a huge variety of materials to
customer’s specifications. The flexibility
is largely down to the wide temperature
range achievable with its process, which
is important as there is a correlation
between the temperature and particle size.
Babcock Wanson was one of a handful of
manufacturers approached by Promethean
Particles, and the only one to provide a
suitable solution. The heater is based on a
Babcock Wanson TPC 1000B, but with very
special inners and controls. For this bespoke
heater Babcock Wanson designed and
manufactured a specially wound continuous
coil assembly to form the main heating surface
using ASI 321 9mm thick stainless steel, as
opposed to the usual 4mm carbon steel for a
standard industrial type water heater. The core
of the tube is very small. This material and
thickness were chosen to meet the pressure
and temperature demands of the process
to be able to produce supercritical water
at up to 250 bar and 450°C.
Several challenges were faced along the way,
including designing the heater with the ability
to accept variations in water flow (between
600-3000 kg/h per hour) and heat input
within quite wide parameters; developing
specialist welding techniques to cope with the
material to the design pressure required and
specifying and installing specialist instruments
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and controls to work at these temperatures
and pressures.
All in all it took seven months to design and
build. The combustion system, control scheme
and software were designed in-house by
Babcock Wanson. Relevant mountings, safety
valves, pressure controllers and differential
controllers were sourced and fitted in house to
enable PED approval. A hazard and
operability study (HAZOP) were carried out
between Babcock Wanson and Promethean
engineers to review the controls and
integration with the site control Scada system.
The resulting heater is now an integral part
of the process, which includes return fluid
heat recovery to limit the final temperature
rise of the fluid to 90°C. This brings it up to
360°C water at 270 bar to take it to the
temperature required for the supercritical
condition. With standard water, this would
typically require just 314kW, but as the
supercritical water is so dense up to 1000kW
is needed.
The supercritical water is then pumped into
the reactor at the same time as the precursor
where it mixes and forms the product. The
product leaves the reactor through a specially
constructed section at 350°C. It then goes
through the heat exchanger to cool it down
MARCH 2020
and recover waste heat and the pressure is
reduced before passing the product into a
holding tank. Depending on the product,
further processing may then be required.
The entire process is controlled by
sophisticated software and is encased
in toughened casing for safety.
Lewis Neve, Production Engineer at
Promethean Particles, comments: “The heater is
running as expected. Babcock Wanson knew
what they were doing and it went very smoothly.
They have also been very easy to work with,
very professional in the way they communicated
with us and the fact that they were in constant
communication made it easier for us.”
Babcock Wanson offers a complete range
of products and services for boiler houses
and other process heating needs, from steam
boilers, thermal fluid heaters, rapid steam
generators and hot water boilers to VOC and
odour treatment by thermal oxidation, water
treatment or process air heating solutions.
The company aims to help optimise
customer’s energy production with high
quality products and efficient service.
For more information, please contact
Babcock Wanson on 020 8953 7111
or [email protected]
or go to www.babcock-wanson.co.uk
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