National Physical Laboratory

Helping control air pollution

NPL helps develop a new way of regulating refinery gas flares.

NPL equipment has been used to measure emissions from refinery waste gas flares (image courtesy of iStockphoto)
NPL equipment has been used to
measure emissions from refinery
waste gas flares (image courtesy
of iStockphoto)

NPL scientists used their own pioneering technique - DIAL (differential absorption lidar - a highly flexible way of measuring air quality) in a pioneering study by the Texas Commission on Environmental Quality (TCEQ) which enabled development of a new approach to air quality regulation within the oil and gas sector.

The Challenge

A problem in reducing air pollution from release of volatile organic carbons (VOCs) by petroleum refineries and crude oil stores is the difficulty of measuring the concentration of these gases at the point of release.

In 2007, NPL worked with the TCEQ to focus on the release of VOCs in Texas City, an area in Houston which is a centre for port operations involving the storage and refining of crude oil and petroleum.

The Solution

NPL's mobile DIAL facility can remotely measure pollutants in the air from the way visible, UV and IR laser pulses interact with gases in the air.

NPL used DIAL to show that, whereas emissions from tanks of petroleum products were close to what was predicted by AP-42 (the industry standard method of estimating emissions), VOC emissions from crude oil storage tanks were several times greater than AP-42 predicted at the time of measurement.

Attention then turned to the area's waste gas flares - many flares are intended to be temporary, but in some flares, which are needed to remain in place for long periods, it is usual to inject steam into the gas exhaust stream to control smoke and reduce the flame's intensity.

Conventional wisdom had been that, whereas temporary flares might well be polluting, the carefully-managed semi-permanent flares were 'cleaner' in that they emitted lower levels of VOCs. NPL's DIAL measurements of flares in Texas City showed the exact opposite, opening the way for a rational policy on regulation of flares.

The Impact

This NPL study increased understanding of the causes of certain types of air pollution, which in turn enables the economic burden of pollution to be reduced, helps cut the cost of enforcing regulations, and helps companies reduce their environmental impact.

Contact NPL's Environmental Measurement team

Last Updated: 26 Apr 2016
Created: 19 Nov 2012

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