Põllumajandusministeeriumi ja Maaelu ... - bioenergybaltic

A prerequisite for extending the use of biofuels is more complete utilization of the existing
domestic fuel resource and organising more extensive collection of logging residues that could
be supplemented by the production and use of agricultural biomass and energy forests.
For the energy use of agricultural biomass, including also straw, fuel storage facilities and
conditions for long-term storage (years) at the fuel producers from where the fuel is
transported to the boiler plant or CHP plant must be prepared.
Suitability of technologies that convert biomass into energy with various biomass-based
fuels
The selection of combustion equipment for biomass-based fuels is influenced by a number of
circumstances, including the most important, such as:
• the plant service regime, incl its running at the base load (in the service regimes of the
plant where the loads change moderately) and operating as a single boiler in the system
that must allow flexible control;
• plant capacity, for example the fluidized bed furnaces are acceptable only for average
and high capacities, but for lower capacities installations with a stoker burner;
• fuel properties, inc:
o the so-called marketable state of biofuels (typical particle size, form, density
and other indices on which both fuel storage, delivery and burning process
depend);
o fuel moisture content and the range of its fluctuation;
o volatile content in the fuel;
o ash content in the fuel and properties of ash, in particular the ash melting
characteristics;
o elementary composition of fuel, in particular sulphur and chlorine content and
that of microelements that influence the corrosion conditions on heating
surfaces, content of gaseous emissions and requirements to ash utilization, etc.
All the parameters and properties of biomass-based fuels that have impact on the fuel use are
specified in the standard of specifications and quality classes of solid biofuels CEN/TS 14961:
Solid Biofuels - Fuel Specification and Classes, the translation of which would help to
improve the mutual understanding between fuel suppliers and users, and supply suitable fuel
to the plant.
The above standard treats various wood fuels and straw from the herbaceous biomass in a
sufficiently comprehensive way; for other herbaceous biomass based fuels the principles of the
standard can be implemented for defining the indices essential for the fuel and preparing the
classes of parameters and properties for each fuel. Such an activity requires profound testing
both of the fuel content and characteristics having influence on the burning process. Testing of
fuel characteristics and technological parameters for the combustion behaviour can be
expected in the next stages of the work, given that it will be possible to supply sufficient fuel
amounts.
Investigation of the characteristics of the combustion technology of a fuel mix is very
complicated, as insignificant amounts of some additives may have strong impact on the
burning options of fuel mix and requirements set to the plant. Only preliminary assessment
could be given on the characteristics of combustion technology for the herbaceous biomass
and fuel mixes as well as selection of combustion equipment. Based on the international
experience on burning the herbaceous biomass based fuels (which is slightly studied) is quite
100