Förädling Bränslekvalitet Åkerbränslen - Energimyndigheten

to the manual method currently in use where samples are dried and the weight loss
measured. This method has limitations in regard to representativity, is relatively
labour intensive and does not provide answers until up to 24 hours later. Any
method that is significantly better in these regards has great potential for use both
in price calculations for fuel deliveries and for input signals to control algorithms
for boiler operations. NIR technology was the main area for study for these
applications and showed good results, but so too did RF technology (Radio
Frequency). One prototype for NIR measurement of fuel deliveries was developed
and evaluated in practical operations. The method is based on a measuring probe
installed on a crane jib; the probe is inserted into the fuel upon which NIR
adsorption by the fuel is determined. The method requires quite a lot of calibration
work in order to cover different fuel types and moisture levels, and calibration is
in principal tied to the measurement system concerned. Under these circumstances
the NIR method level of uncertainty proved to be distinctly lower than the
reference method’s; less than two percentage points compared to four or five
percentage points. A specification has been established for the NIR method as
support for price calculation, and the method is awaiting the imminent approval of
the dominant player on the market, the Swedish Timber Measurement
Association. NIR measurement of moisture levels directly in the fuel feed to the
boiler for use as an input signal to the control system was also studied at two
plants. Good results were also achieved here, chiefly in regard to improved
control of bed temperatures that lead to lower emissions of CO and NOx, and
higher power output, all of considerable economic significance. The technology
can be considered commercially viable, and several installations have been sold.
Requirements for further development pertain mainly to calibration methods and
automation of the probe motion. The RF method has not yet shown the same
immediate potential, but some development work continues and the method has
not been written off.
The control of pellet matrix temperatures is under study as a possible method
of ensuring the stable pressing of good quality pellets from straw fuels. Raw
materials of this type today often present problems with the production of pellets
of uneven quality in regard to durability and density, and this has a clear
connection to the temperature in the matrix at the time of pressing. Because this
temperature is a result of the raw material’s moisture content, and the possible
addition of steam, and is not possible to control today, it is probable that
temperatures are not optimal from production and quality standpoints. The aim of
the project, which was begun recently, is to investigate whether controlling matrix
temperature to optimum values for the raw materials concerned can provide
improved production uniformity, better quality and lower energy consumption.
Pellet combustion characteristics are being studied in a project with the
overarching aim of combining research into pellets production with research
into pellets combustion. The project will also develop principles and
documentation for quality assurance systems in respect of the entire delivery
chain from raw material to burner. The project is expected to contribute to an
increase in knowledge of the characteristics of pellets produced from different raw
materials. Combustion trials with pellets from different raw materials are expected
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