Tech Lowers NOx Emissions in California Oil & Gas Sector

Achieving further reductions in nitrous oxide (NOx) emissions is a focal point for U.S. oil, gas and industrial businesses, as well as automakers, as state air quality authorities work to follow through on proposed new federal NOx emissions limits. Public air quality authorities in Los Angeles and the San Joaquin Valley – hubs for oil production in California for over 100 years – are working with industry players to come up with practical, cost-effective solutions.

A new clean combustion technology from Seattle's ClearSign Combustion Corp. may provide an answer to oil and gas industry players' and regulators' search. Retrofitting 62.5 million Btu/hour once-through steam generators at an Aera Energy LLC heavy-oil production site with its Duplex Burner Architecture (DBA) has validated previous, smaller-scale test results. There, ClearSign's DBA is reducing NOx emissions to levels that meet the San Joaquin Valley Air Pollution Control District's (SJVAPCD) Rule 4320 on NOx emissions.

On Jan. 22, ClearSign followed the successful Aera Energy field test by announcing an agreement to retrofit a three-burner, 12 million Btu/hour vertical cylindrical heater at a Tricor Refining LLC oil refinery in Bakersfield with its Duplex Burner technology.

Cleaner burning and combustion

Inaccessible and largely obscured from public view, massive burners inside petroleum refineries, petrochemical and industrial plants drive the production of fossil fuels and myriad everyday products that we have come to take for granted and seldom, if ever, think much about. These combustion-driven thermal process systems also use vast amounts of energy – fossil-fuel energy. Hence, they are among the largest sources of air and environmental pollution – nitrogen oxides as well as greenhouse gases (GHGs).

Whatever the application, a significant portion of the energy used in thermal process systems winds up as waste energy due to inefficiencies inherent in fossil-fuel combustion, as well as faulty or poorly-maintained equipment or process controls. This waste energy not only results in higher operating costs for owners, but also in NOx and GHG emissions and other forms of environmental pollution.

Once poster children for air pollution, air quality in the Los Angeles and the San Joaquin Valley basins has improved greatly since enactment of the Clean Air Act and state agency efforts to meet NOx and emissions reduction targets. That said, air quality in these areas remains among the worst in the country due to a combination of factors, including climate, geography, population and vehicle density, as well as fossil fuel exploration and production.

ClearSign says its Duplex Burner technology not only delivers reductions in NOx emissions that will enable oil producers and refiners to meet more stringent emissions limits, but also enhances the efficiency, performance and safety of thermal process systems. That translates to healthier financial, as well as environmental and social, bottom lines.

If the new combustion technology matches or exceeds performance at Tricor and the ongoing field test at Aera Energy – a joint venture between ExxonMobil and Shell – “for the first time it will be possible to align environmental goals with goals of process excellence, reduced maintenance and greater capacity,” ClearSign's former CEO Rick Rutkowski, who recently resigned, asserted in an interview.

Oil refineries and air quality standards in the San Joaquin Valley

Working with Advanced Combustion and Process Controls to retrofit the massive vertical cylindrical burner at Tricor's refinery with its DBA will bring an asset that has been out of commission – stranded – since 1984 back to life, ClearSign highlights in its press release.

"Our recent transactions with organizations like Tricor underscore that ClearSign is bringing a transformative technology to the oil and gas market," current ClearSign CEO Stephen Pirnat was quoted as saying. "Shifting economics and evolving environmental regulations are aligning to create a real need for the unique benefits realized by Duplex technology."

The San Joaquin Valley has been a center of oil and gas exploration, development and production in California for over a century. The San Joaquin Valley Air Pollution Control District (SJVAPCD) also has some of the most stringent limits on NOx emissions in the nation for the boilers, steam generators and process heaters used in EOR and oil refineries, Jaime Holt, SJVAPD chief communications officer, stated in an interview.

The latest in a series of more stringent ambient air quality standards stretching back 22 years, SJVAPCD instituted a limit on NOx emissions from these sources as low as 7 parts per million by volume (ppmV) at 3 percent O2 in 2008. Over the last 21 years, SJVAPCD's latest NOx emissions standard for these sources represents a 77 percent decrease, Holt highlighted.

Overall NOx emissions from stationary sources in the San Joaquin Valley have come down over 90 percent and those from EOR, oil refineries and petrochemical plants over 90 percent since 1990, “resulting in significant improvements to air quality in the Valley,” she continued.

“NOx is the key driving pollutant for ozone in the summer and PM2.5 in the winter, so NOx will continue to be the focus of the district's [air pollution reduction] efforts.

“Meeting these new standards will require extensive additional emissions reductions and transformative change, particularly with respect to the over 80 percent of remaining NOx emissions in the Valley now attributed to mobile sources,” Holt stated. “In that effort, we will continue work collaboratively with Valley stakeholders to seek out additional opportunities to further reduce emissions.”

*Images credit: 1) NASA; 2, 3) ClearSign Combustion Corp.; 4) Lost Hills, Kern County pumpjacks, Wikipedia