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Leak Detection and Repair (LDAR) is the process by which a facility locates and repairs leaking components, including valves, pumps, flanges and connectors, in order to reduce the emissions of fugitive volatile organic compounds (VOCs), like methane, and hazardous air pollutants (HAPs), such as benzene. Left unmonitored and unaddressed, these leaks can have detrimental consequences for the environment and human health.

The leaks that are detected are called fugitive emissions, so named because they typically elude detection without specialised equipment. Nevertheless, the collective impact of these small leaks across numerous components can be substantial, and so repairing the leaks will result in a significant decrease in harmful gas emissions from the plant.

Detecting Emissions

In conventional LDAR programs, fugitive emissions are detected using organic vapor analyzers (OVAs) in a process known as “sniffing.” The OVA probe is positioned near the leak source to measure the concentration of hydrocarbons in the sampled atmosphere in parts per million (ppm). This enables the facility to identify components with significant leaks and prioritize their repair at the next available opportunity, thus making the most substantial impact on VOC reduction. Subsequently, the facility can establish specific criteria for defining emissions as leaks. For instance, a typical leak definition might set the threshold at 500 ppm, considering any reading above this value as a leak. This systematic approach allows the plant to concentrate its efforts on addressing those components effectively.

Emissions can also be detected using optical gas imaging (OGI) cameras. These cameras work on the principle of infrared (IR) imaging, but with a special filter enabling them to detect infrared energy within the waveband characteristic of hydrocarbons such as methane. This allows the camera to detect leaks too small for traditional infrared cameras. OGI cameras allow real-time visualisation leaks and are excellent for scanning large areas of plant to identify leaks quickly, including those in hard to reach locations. Although they cannot directly measure the size of the leak, there is quantification software available that can estimate the concentration of the emission. The integration of these techniques can enhance the efficiency of LDAR programs by rapidly identifying potential leaks through the camera and then precisely quantifying emissions once a leak is identified.

Quantifying Leaks

The quanitifcation and reporting of emissions are fundamental components of LDAR programs. To convert the measured leak concentrations, in parts per million (ppm), into mass flow rates, typically measured in kilograms per year (kg/year), industries utilise a series of correlations using data published by the EPA. These correlations provide a means to estimate the volume of emissions from leaks, aiding in environmental reporting and regulatory compliance, and allowing for more informed decision-making and targeted emission reduction efforts.

LDAR Applications

The LDAR process is essential to industries that handle VOCs and HAPs. This includes petrochemical, oil and gas, chemical manufacturing, pharmaceutical, waste management, manufacturing, and emerging sectors like biogas production. In recent years, Europe has witnessed the introduction of more stringent regulations governing LDAR practices. As a result, companies and facilities operating within the European Union are required to enhance their LDAR programs, employ advanced monitoring techniques, and implement more robust reporting and record-keeping procedures to ensure compliance with these rigorous new standards.

Conclusion

In conclusion, LDAR offers numerous advantages to industries and the environment. It helps mitigate the release of harmful VOCs and HAPs, safeguarding human health and reducing air pollution. By identifying and addressing fugitive emissions, LDAR promotes compliance with environmental regulations, minimises operational risks, and contributes to a more sustainable and responsible approach to industrial processes.

The Phoenix Group has a long standing association with many landfill and biomass plants in the UK, providing Leak Detection and Repair (LDAR) services and supplying gaskets and other sealing products.

One of these sites is a waste treatment facility in the central belt of Scotland which converts landfill gas to usable energy. This process involves extracting gas (methane), which is processed and pumped to gen set engines within a turbine house. These engines generate electricity, which is sold to the national grid.

The process is volatile, with process temperatures that operate beyond the limits of traditional gasket materials such as compressed fibre and graphite. Previous attempts to find a suitable gasket had failed, with the products failing before the engines could next be serviced.

Phoenix sealing were asked to offer a high temperature sealing solution for inlet and outlet flanges of the engine exhaust system that would offer long term, high integrity sealing. PG-Therm, a mica (phlogopite) based sealing material was offered, and successfully installed, adding approximately 300hrs extra running time between services with zero leakage.

For more information on PG-Therm, or on how our products and services can help with leak prevention and environmental compliance, please contact Dr Gavin Smith on 01246 209680 or info@phoenixsealing.co.uk

Biogas is renewable energy source created when organic materials (plant and animal products) are broken down (eaten) by bacteria in an oxygen free environment, a process known as anaerobic digestion. This process occurs naturally in oxygen depleted places such as soils, landfill sites and marches, but it can also be reproduced under controlled and contained conditions in special tanks called anaerobic digesters.

Anerobic Digesters(AD) produce biogas by processing feedstock crops, manure, straw, food scraps, slurry and even sewage. The resultant gas contains roughly 50-70 percent methane, 30-40 percent carbon dioxide, and trace amounts of other gases. The material that is left after anaerobic digestion is called digestate, and can be used a fertiliser for crops. After biogas is captured, it can produce heat and electricity for use in engines, microturbines, and fuel cells. Biogas can also be upgraded into biomethane, also called renewable natural gas or RNG, and injected into natural gas pipelines or used as a vehicle fuel.

Methane leakage is a potential issue for many biogas plants. Fugitive methane emissions result from the biogas production process (the AD plant) and biogas utilisation processes (e.g. biogas combustion in CHP engines/boilers or from biogas upgrade systems in BtG plants). For this reason, leak detection surveys and reporting are now a requirement of the Environmental Agency permit scheme for Bio Gas facilities.

The Phoenix Group is the UK leader in the provision of leak detection surveys for the biogas production sector, and has a wealth of experience in helping facilities meet their environmental goals. We work throughout the UK on plants with a variety of technologies including biodigesters, waste recycling and landfill recovery. Our skilled and experienced technicians use a combination of optical gas imagining and organic vapour analysis to detect and quantify leaks, as well as offering assistance on minimising the leaks with repair strategies. If required our sealing experts can assist in ensuring the right gaskets and seals are being fitted in the application.

For more information contact Dr Gavin Smith on gsmith@phoenixsealing.co.uk