Design and Use of a Full Flow Sampling System (FFS) for the Quantification of Methane Emissions

We have designed, developed, and implemented a novel full flow sampling system (FFS) for quantification of methane emissions and greenhouse gases from across the natural gas supply chain.

Transcript

The overall goal of this methodology is to provide robust and accurate quantification of leaking gases, specifically methane, a potent greenhouse gas using new technology. The main advantage of this technique is that it offers improved accuracy compared to other available quantification systems. It is not sensitive to non methane hydro carbon emissions.

We first had the idea for this technology and method when we were tasked with quantifying methane emissions related to natural gas fueling equipment and stations. Following a review of current and previously used technologies and techniques, we determined that developing our own system and methods would ensure improved accuracy. We then modified our methods of sampling auto-motives among the emissions that developed full flow sampling system.

Which we then employed a variety of measurement campaigns to accurately quantify leaking in lost methane emissions. Prior to working in the field, be certain to correctly calibrate the mass airflow sensor and the greenhouse gas analyzer. These are relatively easy but important procedures to conduct correctly.

Thus they are described in detail in the text protocol. The text protocol also explains how to perform a full system recovery test. This video demonstrates how to seek out greenhouse gas leaks.

And assess them at a potential source of fugitive emissions. Before beginning, create a new inventory file in the field computer. Enter all the details on the site.

The data fields for the date, time, and GPS location are automatically populated. Next, document any inaccessible sources or aggregated sources. For example, a vent pipe that is not safely accessible.

An aggregated group of sources may include multiple fittings and possible sources such as a compressor housing. If multiple sources can be examined as a whole, aggregate the sources using an enclosure composed of a non permeable material with at least one entrance and an exit designed to capture out flowing gas. Periodically, measure and record the background methane concentration.

Always take multiple background readings in the same region. To check for a leak using the handheld methane detector, first zero it in the ambient air. The detector is sensitive to gases five parts per million above the background.

Then check all the accessible interfaces which may have fugitive emissions. Position the probe sample emulate or thaw go a leak to the surface to minimize solution. Then move the probe along the interface periphery while observing the instrument readout.

Go slowly because the response time of the instrument is delayed. When an increased meter reading is observed, slowly sample the region until the maximum meter reading is obtained. Leave the probe emulate at this maximum reading location for about 20 seconds.

If the meter reading is greater than 500 parts per million, record the result and report it by taking a leak image. To scan for leaks using an infrared imaging device, such cameras can find leaks faster than a handheld detector. If a leak is detected, record a video or take an image for reporting purposes.

If a leak is found but the exact location is difficult to pinpoint, try using a leak detector solution. Hold the bottle upright and apply enough solution to cover the interface with the punitive leak. Then allow five to 10 seconds for bubbles to form.

Quantify leaks as they are found or after taking a full inventory of all the leaks. Prior to approaching the leak with the sample hose, ensure that the grounding strap is in contact with the ground. Then attach the sampler ground clamp to the leak source.

Now check multiple points around the area of the leak source. Next, open the Iris duct on the intake of the blower to increase the volumetric flow. So the peak methane concentration is within 10 percent of the highest calibrated value or is at least two parts per million higher than the background level.

Now to quantify the leak, press the new leak button. Next, select the local background option and if there are other leaks in the area. Otherwise select the global background option.

Now keep the hose still as the local background is sampled while the device is in the leak sampling position. After reading the background, quantify the leak three times from the same position. The system will analyze the three measurements and report the variance.

If the variance is above 10 percent, keep sampling until the variance is acceptable. Otherwise classify the leak as variable and record the suspected cause. When quantifying gas in an enclosure, alert the system using the enclosure tab.

Wait for a steady reading before quantifying the gas. The time this takes will depend on the size of the enclosure. To take a bag sample for offsite examination, simply collect gas from the outlet of the greenhouse gas sensor.

When doing this, record the sample's identification number in the software and fill the bag using the onscreen timer. Prior to use in the field, the full flow sampling system was checked with a standard gas. The system flow rate was set to 140 SCFM and gas was flowed to the system at 20 or 30 standard liters per minute.

The measured values were within the expected 4.4 percent. The sensor was calibrated using a known concentration of methane. After applying an external correction, the average deviation from the known concentration was 0.7 percent while individual measurements never deviated by more than 1.9 percent.

Now a continuous gas leak was measured in the field. First the background was determined. As the leak was approached by the sensor, methane concentration measurements increased.

At the leak, the peak measurement was taken. As the sensor moved away from the leak, lower measurements were recorded. With an IR camera, a plume from the leak was evident.

With the sampler in use, the camera could no longer capture the plume. After watching this video, you should have a good understanding of how to use the full flow sampling system to accurately quantify the methane emissions rate of a leak. Accurate mass based measurements are pivotal in determining total methane emissions, creating and updating greenhouse gas inventories, and developing component level emission factors.

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Design and Use of a Full Flow Sampling System (FFS) for the Quantification of Methane Emissions

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