Intelligence at Your Fingertips,
Keeping You in Control
Following the Paris Climate Change Conference and the UK government’s mandatory Energy
Saving Opportunity Scheme (ESOS) the focus is clearly on reducing energy consumption, with
greater efficiency and reduction in fuel usage high on the agenda: steam raising plants are prime
targets for attention.
U
tilisation of microprocessor
burner controls, flue
gas economisers and
thermal improvements
in boiler lagging have enabled boiler
manufacturers to achieve significant
improvements in boiler efficiency: heat
input minus the sum of the losses.
Stated efficiencies are based on ‘IDEAL’
conditions, the reproduction of which
under actual operating conditions is
entirely dependent on how much care is
taken by the boiler operator.
control has all but eliminated gas side
fouling but the water side has largely
remained unchanged. Scale formation, a
direct result of the inadequate application
of water treatment chemicals, retards
heat transfer and significantly increases
lifecycle costs. Conservative estimates of
2% to 5% are based on the assumption
that the scale thickness is approximately
0.75mm (1/32”) thick.
In brief, ‘Aquanet’ independently
samples water optionally from the
feed pump discharge, each boiler (up
to 3) and the returning condensate in
sequence, cooling the sample, testing
the pH, conductivity and determining
the dissolved oxygen levels. Based
on the results the control system fine
tunes the chemical dosing pumps and
adjusts the surface blow down rate to
maintain the cor rect feedwater chemistry
and TDS levels in accordance with the
recommendations of BS2486:1997,
BS EN12953-10:2003 and the boiler
manufacturer: ensuring that the boilers
are fully protected 24Seven.
Boiler efficiency calculations are based
on the assumption that all the heat
transfer surfaces are clean and the boiler
is operating at its maximum continuous
rating (MCR). In order to ensure that
the design efficiency can be maintained
throughout the lifetime of the boiler all
parts in contact with water must remain
clean: scale and corrosion free.
It is one thing designing and building
boilers with improved thermal efficiency
it is an entirely different matter
maintaining that efficiency throughout its
operational lifetime.
The responsibility to maintain efficiency
over the lifetime of a boiler falls squarely
on the shoulders of the owner/end user
and how effective their control regimes
are. Yet few people fully realise the effect
the condition of the feedwater has on the
boiler efficiency and operating costs.
For instance, if the furnace and boiler
tubes are not kept scale and deposit free
then the thermal transfer surfaces will be
compromised and you will never achieve
the design output irrespective of how
good the combustion process is.
The widespread use of natural gas and
improvement in burner technology and
With a Gas fired boiler operating
24Seven the 2% to 5% loss in efficiency
equates to between £3000 & £9000 for
every 1000kgs @£17.50/T of steam
generated. Increasing lifecycle costs
between £75,000 & £225,500 per Tonne
based on 25 year operation.
The plain truth of the matter is you can’t
achieve consistent feedwater quality
by testing once a day and manually
adjusting dosing pumps based on one
daily sample.
72 hour unattended
operation simply
exacerbates the situation.
‘Aquanet’ has the
answer.
The ‘Aquanet’ system
is based on an analysis
of boiler and makeup water and dosing
the precise amount of
chemicals needed to
maintain the optimum
feedwater chemistry. It is
the only microprocessor
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PECM Issue 19
based chemical dosing system offering
continuous and consistent water quality
control.
‘Aquanet’ is the only feedwater
chemistry control system that enables
full compliance with BS EN1295310:2003 and SAFed/CEA BG01 with
regard 72 hours unattended steam boiler
operation. For further information on the
‘Aquanet’ system and how to reduce
your boiler plant capital and operating
costs
Telephone 01254 841769
e-mail [email protected] or
visit www.controls4steam.co.uk