Gas monitoring for landfills

The Kurz Insertion Mass Flow Meter products provide extremely reliable and accurate measurements with a number of features specifi cally tailored for landfi ll gas monitoring applications.

Landfill Gas Introduction

It wasn't that long ago that people would back up to a ravine outside of town and toss out whatever trash they had. 8y the very nature of waste decomposition, the landfill will generate an off gas by-product, comprised primarily of methane and C02. Over the years as landfills grew in size they became more sophisticated and correspondingly more regulated. In 1990, the Clean Air Act and subsequent Federal, State, and local regulations required that landfills provide controls to assure that the naturally occurring off gas is environmentally safe.

Today, the monitoring and secondary use of landfill emissions has become standard practice. These off gases can be a valuable resource if they are captured and utilized. After filtration, landfill gases can be measured and then bumed in an engine to turn a generator or in a boiler to create steam that then turns the generator.

Landfill gas monitoring falls into five basic categories: Soil gas monitoring, near surface gas monitoring, emission monitoring, ambient air monitoring and facility air monitoring. These five categories require rate monitoring as well as composition monitoring.

The Kurz Solution

While near surface and ambient air monitoring is typically accomplished by simple grab samples or portable organic vapor analyzer-flame ionization detectors, the soil gas, emissions, and facility monitoring are uniquely suited to Kurz thermal mass flow instrumentation.

Soil gas monitoring and collection systems are typically designed using a ring of monitoring wells around the perimeter of the landfill. These wells and collection headers (perforated pipes set into the landfill typically In the top 50% of the biomass) are normally connected to vacuum and pump systems which draw the 'overpressure' of decomposition gasses into a unified collection system by providing a low pressure 'preferred migration' route for the gasses. This gas is typified by low flow rates and high moisture content, and in some cases levels of H2S that are of concern for instrumentation.

Emission monitoring of collected gasses for use In flares. Incinerators, boilers, gas turbines, and internal combustion engines are required in order to control those processes to assure proper destruction of the landfill gas, and also to comply with reporting requirements.  Control may require monitoring of landfill gas flow rate, 'make-up' natural gas flows, and equipment energizing (adding or subtracting engines, turbines, and flares, in order to handle the flow rate that is generated).  This control requires rapid response to varying flows, as well as outstanding discrimination especially at low flow rates.  Further, as vacuum levels can be adversely Impacted by many instrumentation schemes, Kurz instrumentation seldom impacts pressure loss at more than a few inches of water pressure even at elevated flow rates.

Facility air monitoring additionally requires outstanding accuracy and dependability to protect the landfills greatest resources, the women and men who operate the facility.