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RAPID RESPONSE
UNIT
The solution of problems relating to thermal
coal utilisation is not always easy when you do not even know
who to start talking to about your particular problem. We
are trying to overcome this dilemma by providing a fast action
service for coal company people who need answers to problems
in a hurry.
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The way it works
is simple, and is illustrated in the diagram. You have
a problem, you ring UST and explain the
problem. If we cannot solve the problem on the spot
we will either:
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This service is provided
free of charge for discussion of any problem and referral
as necessary. It is provided in the interests of assisting
in the resolution of coal industry technical problems with
advanced coal characterisation and forensic tools that are
now available.
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Some examples of our achievements
in solving problems through the Rapid Response Unit
include:
- New coal supplies to a Japanese utility were in
jeopardy when the coal was outside limits on an arbitrary
index for ESP performance - the dreaded "K-Factor".
The K-Factor was shown to be a very poor indicator
of ESP performance and UST assembled
compelling evidence that the coal would have good
ESP performance in the Japanese plant.
- Two export coals with different HGI values (70 and
95) were blended and caused mill vibrations. In this
case the grinding roll pressure was set for coals
with HGI values of around 55 and when the softer coal
was introduced, the roll pressure was too high for
this blend, thus causing the vibrations.
- An export coal was purchased for use in oil-coal
mixtures. Part of one shipment had a problem with
respect to the coal dispersing in the oil. On investigation
it was found that one of the coals used had a relatively
high salt content, which acted hydroscopically and
coated the coal particles with water. UST
developed a "salt index" as an "index"
to evaluate this situation.
- Coal-water mixes have very stringent requirements
for the type and amount of dispersant used to manufacture
the mixes. A client reported problems with the dispersant.
On investigation, it was found that swelling clays
in the coal were causing ion exchange with the dispersant,
rendering the dispersant ineffective. UST
developed a "swelling clay" index to provide
a means the evaluate coals beyond the accepted and
normal indicators.
- The case of the ash that never was. An overseas
utility reported poor ESP performance when burning
a certain coal. UST conclusively demonstrated
the problem could not have been caused by the coal
in question. The coal & fly ash mineral matter
of the problem coal were incompatible with the fly
ash collected at the time of the poor performance.
A case of unauthorised blending? Got the feed mixed
up? The problem was later tracked to another coal
that was used for blending from time to time. Naughty.
- A coal being burnt in a circulating fluid bed boiler
was causing concern about the occurrence of stone
material in the coal causing blockages in the air
distributing plates of the boilers. The stone material
was subjected to mineralogical examination and shown
to be volcanic rock derived from dykes and sill in
the coal deposit. The mine reviewed its operations
and did not deliver such material to this particular
customer.
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SLAGBUSTERS
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SlagBusters
is a collection of experts with a proven record in their
specific fields that work together with the common purpose
of solving slagging problems in boilers. The team consists
of Lindsay Juniper (UST), Bob Creelman
(Creelman & Assoc), Terry Wall (University of Newcastle),
Alf Ottrey (HRL Technology), John Pohl (Energy International)
and others as required. From time to time, a wider circle
of experts can be co-opted for specific problems. The
SlagBuster Mission Statement:
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 "We
will not rest until all slagging & fouling problems have
been eradicated in all boilers around the world."
SlagBusters grew out of
a large commercial contract issued in 1993 by the then Austa
Electric to solve slagging problems at Callide Power Station
in Queensland. This project broke new ground in a number of
fields, particularly relating to new techniques of boiler
sampling and analysis that were developed. These techniques
have now become "best practice" in this field.
The application of petrological
techniques borrowed from the geological world proved to be
ground breaking in the understanding of slag formation. This
included the practical use of thermodynamic data to interpret
the mineralogical observations. The success of this approach,
which combined EMPA and SEM data with published chemical thermodynamics
ultimately lead to our present interest in using the FACT
code.
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SlagBusters has
continued to solve a number of slagging & fouling problems
in boilers and some examples include:
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Review of ash
behaviour during combustion of Australian coals.
Both bituminous and brown coals were covered, with
the primary emphasis on slagging and fouling. The
review was carried out for a Japanese steel company
who was investigating the feasibility of blending
Victorian brown coal with bituminous coal.
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Investigation
of a green field coal deposit that contained high
and variable levels of iron in the ash. Detailed
mineralogy identified that the iron occurred in
a refractory mineral that did not lead to slagging.
This was a good example of where conventional techniques
failed to address the basic issues. The outcome
suggested that there should be no problems with
slagging & fouling when using this coal.
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A coal company
delivered a trial shipment to a Japanese utility.
When this coal was first fed to the boiler, ash
deposits fell from the walls and blocked the furnace
ash removal system. Mineralogical analyses on deposit
samples, together with boiler assessments, showed
that the new coal was effectively removing deposits
built up when firing the previous coal. These findings
assisted in finalising a $400 million coal contract
for the company.
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Investigations
into poor combustion and clinker formation in stoker-fired
boilers. The coal was not fully burnt as it fell
off the grate into the furnace ash hopper. Before
removal of the ash from the hopper, there was sufficient
time for the unburnt material to melt and form large
clinkers that were bonded by the coal melting. The
high iron content of the ash was reduced to native
iron in some cases. The cause of the problem was
due to a high percentage of fines in the coal feed.
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Investigations
of the slagging behaviour in a large utility boiler
due to a low rank coal. This work included the examination
of the coal and ash deposits using the same mineralogical
procedures that were developed in the original Callide
work, as well as detailed fluid flow modelling and
particle tracking. With respect to coal quality,
a coal "index" was developed so that the miners
could blend the coal to prevent incidences of slagging
in the boilers.
- Investigations into slagging occurrences
at Callide and Tarong power stations in Queensland,
Lamma PS in Hong Kong and Kwinana PS in Western Australia.
Examination of the slag deposits has identified what
caused the slag to melt and stick and tracking of
coal minerals with time has identified which minerals
in the coal have changed in concentrations to cause
the problems.
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ULTRAMAX
ULTRAMAX is Windows based, dynamic process modelling and optimisation
tool. It uses a unique combination of Bayesian statistics
and weighted regression analysis algorithms to build locally
accurate, goal-oriented models. This combination allows ULTRAMAX
to start with very little, or a great deal of data to improve
a process while still making an acceptable product. As the
data becomes richer, the regression algorithms are introduced
to determine the best combination of control settings to meet
the desired objectives.
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Click on the image to view
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ULTRAMAX can be used as part of a continuous
improvement strategy to improve processes in order to meet
customer needs and profit objectives. It can be used as a
process troubleshooter, or as an on-line advisory tool letting
the operator know which are the best control settings to use
to keep a process operating at its optimum level.
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Click on the image to view
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UST has a licence to market
ULTRAMAX in Australia and New Zealand from UltraMax Corporation
in the USA. Call for more information.
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