Metoder att mäta och reducera emissioner från ... - Avfall Sverige

ABSTRACT
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The aim of this study is to evaluate and test different instruments and methods to
measure emissions from systems with digestion and upgrading. Further, the purpose is
to estimate the magnitude of these emissions and to understand where in the plants they
arise, which will be made through measurements. Finally suggestions will be made
about how to reduce the emissions. The study is commissioned by BUS with
Renhållningsverksföreningen as project manager.
Five types of instruments were tested and evaluated: Conventional leak detector, Laser
Pointer, FID, FTIR and samples analysed with gas chromatography. The measurements
took place on two biogas plants and three upgrading plants in Sweden. Every plant uses
a different technology and have different raw material for their activity, which is
assumed to make them a representative selection of the Swedish plants.
The measurements are random samples but indicate that the largest leakages of methane
originate from the upgrading plants and that the size of these discharges strongly varies
with upgrading technology. Except for methane, laughing gas, alcohols and sulphur
compounds among others, have been detected on digestion plants. Laughing gas and
sulphur compounds are assumed to be formed in the hygienisation. There is a good
potential though, to reduce the emissions on both biogas and upgrading plants.
Examples of measures which reduce the emissions from systems of digestion and
upgrading of biogas is:
• Strive for having as much as possible of the plants indoors, to be able to survey
and treat the emissions in the ventilation air.
• Make the heating period as short as possible in the hygienisation, in order to
reduce the formation of laughing gas and sulphur compounds.
• Use leak detectors regularly on the plants to discover and attend to diffusive
leakages, for both environmental and security reasons.
• Continuously measure the content of methane in the gas flow leaving the plant
to atmosphere. This gives the possibility to optimise the operation regarding to
the losses of methane.
• Destruct the methane in the gas leaving the plant to atmosphere by
oxidizing/combusting it, e.g. thermically or catalytically.