Chemical companies such as BASF and Dow are working hard both to identify and deal with the sources of their fugitive emissions. Meanwhile, vendors such as Garlock and Honeywell Process Systems are developing technologies and procedures to make the job faster and more cost-effective.
Fugitive emissions may pose significant hazards to people and the environment as well as sizable economic penalties from loss of materials. “Fugitive emissions cause losses during production, transport and storage. Many of the substances concerned are toxic and it requires know-how and state-of-the-art technology to contain their release,” notes Christoph Moritz, coordinator air quality, BASF, Ludwigshafen, Germany.
To reduce fugitive — also known by BASF as diffuse — emissions, the company implements strategies at its sites that meet local, national and international standards. At the heart of these strategies are three basic rules.
First is avoidance. “Here, we use state-of-the-art equipment such as low-emission seals that have been designed for use with critical chemicals. We also run quality assurance programs for mechanics and operators, who are properly trained in special courses according to latest standards, for example, VDI 2290 in Germany,” he adds. (The VDI 2290 guideline deals with flange connections for liquid and gaseous media to meet emission control requirements; it covers various metals and applies to services with a maximum operating temperature of 400°C.)
“Besides regular inspection and maintenance, our plants are controlled by means of pressure drop sensors. Seals and flanges are replaced at defined intervals,” says Moritz.
The second basic rule is detection of emissions and leaks (Figure 1). Typically, plants rely on a conventional flame ionization detector (FID) that is sensitive to organic substances. Analysis of the substance begins at a pre-set threshold concentration, for example, 500 ppm. If such a concentration is exceeded, operating staff takes immediate action.
An infrared (IR) camera often serves as a preliminary detection device (Figure 2). Set in a “fume sensitive” mode, it can spot an increased concentration of a substance; a more precise check with an FID immediately follows.
“All plants are equipped with such sensors and any leaks detected are instantly repaired. The detection procedures themselves may vary from country to country depending on local regulations and the requirements of the respective authorities,” he explains.
The final basic rule is calculation of emissions; the methods used depend upon the relevant standards (EPA, DIN, etc.). To create a proper comparison between the different standards, BASF has carried out internal studies and sponsored several postgraduate research theses. “These have revealed valuable information about the correlation between ‘sniffed’ concentrations of organics and the corresponding leakages in g/h — i.e., mass flow. Moreover different methods of calculation for diffuse emissions were compared and quantified,” Moritz says.
Link to Sustainability
For Dow Chemical, Midland, Mich., reducing process spills from equipment and decreasing fugitive emissions are part of its overall sustainability strategy. Launched last year, its 2025 sustainability goals commit the company to maintaining world-leading operations performance in natural resource efficiency, environmental protection, health and safety.
To this end, Dow has set a goal to reduce severe process safety and containment events by 70% by 2025, a target the American Chemistry Council, Washington, D.C., suggests for its members. The company’s fugitive emissions strategy covers small emissions of gases or vapors from equipment flanges, seals and packing components that are difficult to detect without specialized equipment.
“Our current focus on reducing fugitive emissions centers on improving Dow’s leak detection and repair (LDAR) management system. This includes improvements to LDAR training, work processes, tracking tools, quality assurance and control and self-assessments. Additional improvements will focus on the technology used by contract providers,” notes a spokesperson.
Dow’s site in Lauterbourg, France, provides a prime example of this work in action: the plant has reduced process spills and associated emissions by 75% over the past four years.