Organics

With increasing environmental awareness and a tightening of statutory controls, the monitoring of exhaust gases emitting from landfill gas flaring and utilisation systems is becoming an increasingly important element of well-managed facilities.

 

The recently prepared UK Environment Agency standards set limits for Carbon Monoxide, Oxides of Nitrogen and Unburned Hydrocarbons. The two former gases can be measured with relative ease. The latter is not yet available at a realistic price, monitoring in the ranges required. Exhaust gas emissions are quoted as normalised to a standard oxygen content, typically 3% in the UK, so it is also necessary to monitor oxygen content.

 

Other gases that may be monitored include Hydrogen Sulphide, Sulphur Dioxide and Carbon Dioxide, although these have limited relevance in the exhaust from landfill gas combustion equipment.

 

Key features

• on-line monitoring of exhaust gas quality
• datalogging of results for trend analysis
• systems designed specifically for sequential sampling
• multi-point sampling systems supplied on a design and build basis

 

Environment Agency Standards Compliance limits

To ensure that flare systems are operating correctly they should not exceed the following emission concentrations when referred to Normal Temperature and Pressure (NTP=0oC and 1013 mbar) and 3% oxygen:

 

• Carbon monoxide (CO)- 50 mg/Nm3
• Oxides of nitrogen (NOx) - 150 mg/Nm3
• Unburned hydrocarbons - 10 mg/Nm3

 

Requirements for monitoring regimes to be applied to enclosed flares

Guidance is given as to the level of monitoring which should be recommended and the acceptable methods that may be employed. Easily accessible, safe and functional monitoring/sampling points should be retrofitted to enclosed flares as appropriate in situations where they are currently absent. Gas concentrations should be analysed annually to determine trace gases.