Measuring landfill gas

Process data

Measuring task: Flow rate at the landfill site’s wells and the collecting pipes leading to the combined heat and power plant

Measuring points: Gas wells, collecting pipes

Measuring range: Usually in each well from 0.2 m/s – 2 m/s or 30 m/s at the collecting pipe

Process pressure: Atmospheric

Process environment: Up to ATEX zone 1

Application

Anaerobic landfill gas is generated after attrition of the enclosed oxygen. Biomass stored in landfill waste is metabolised in a multi-stage degradation process resulting in mostly methane (CH4) and carbon dioxide (CO2).

Methane is one of the most significant greenhouse gases. Unless it’s caught it will continue to push global warming forward. That’s why its emissions have been successfully reduced. At the same time recording methane gas in landfills has been improved. The resulting methane is collected in wells and routed to the power generation. Due to the different compositions in a landfill and the continuously decreasing methane production all processes must be monitored.

Measuring landfill gas on landfill sites – environmental protection and energy saving

Landfills that emit gas in an uncontrolled manner are among the most important causes of methane emissions worldwide. There’s also the risk of fires or even explosions due to the exiting methane. Even small amounts can be health damaging. Also, methane is very rich in energy so “catching” the landfill gas provides two positive side effects: there’s no danger from leaking methane and by turning the collected landfill gas into power you additionally have continuously usable energy. Due to the slow processes in a landfill it can be a reliable source of energy for several years. A double plus for the environment.

The resulting landfill gas is collected via gas wells in different parts of the landfill body and reunited by a pipe system. The landfill gas is delivered to the upstream compressor through the collecting pipes. There lies an emergency flare. Eventually the gas is being led to the combined heat and power plant for energetic recovery (power and heat).

Portable landfill gas measurements with thermal sensors or vane wheel sensors

Our thermal sensor is the right sensor to determine gas mass flow. If the gas composition is known it directly delivers gas mass flow due to the calorimetric principle of measurement. Actual flow rate can be measured with our vane whel anemometer. Measurements are possible even in small pipelines and in lower velocities.

For portable measurements both sensors can be connected to our handheld units flowtherm NT.2 or EX. It displays current values and also saves measured values (data logging) to have them available for later evaluations. The flowtherm EX can be used up to Ex zone 1 with corresponding sensors.

Fixed landfill gas measurements with robust vortex sensors

Another important measuring point in a landfill site is the collecting pipe. It’s where the entire gas flow from all wells comes together. It’s an input parameter for the following generation of energy. In such a constant measurement condensate can cause heavy fluctuations with the thermal sensor. So in cases like this our vortex sensor is the perfect instrument. Ist special type without any moving parts is perfectly suited for rough conditions such as contaminated or condensate-laden gas. ATEX certified Höntzsch sensors with approvals up to zone 0/1 are also available for fixed installations. Their robust construction also allows the use in outdoor areas.