COOLfuel™ Case Study 102

Chevron – Richmond Refinery

The Situation

The California Clean Air Act, signed into law in 1988, called for the installation of the “Best Available Control Technology” on existing facilities that produce ozone-causing emissions such as Nitrous Oxides (NOx) and Volatile Organic Compounds (VOC).

As part of its compliance with this Act, the Bay Area Air Quality Management District developed regulations that targeted NOx and VOC emissions in the San Francisco Bay Area. Regulation 9, Rule 10, was designed to limit NOx emissions from combustion sources in Bay Area refineries by requiring NOx control systems to be retrofitted on existing furnaces and boilers.

Specifically, at the Chevron Richmond Refinery, the daily average emission rate had to be reduced to less than 0.033 lb NOx per MMBtu of fuel burned, which is equivalent to about 27 ppm NOx (corrected to 3% O2).

The Response

Chevron’s NOx Reduction Project was initiated in 1997 when Chevron assembled a team of company personnel and consultants to evaluate, recommend and implement NOx reduction technologies that would allow the refinery to achieve its compliance goals in a timely and cost-effective manner.

An initial baseline survey of NOx emission levels indicated that the five utility boilers in Power Plant No. 1 contributed about 25% of the total refinery NOx emissions, with observed NOx emission levels ranging from 250 to 500 ppm.Therefore, these boilers were identified as a primary target for Chevron’s NOx Reduction Team. Initial conceptual planning called for installation of Selective Catalytic Reduction Systems (SCRs) that use ammonia injection and a catalyst to remove NOx from flue gases. However, with a projected purchase and installation cost estimated to be more than $30 million for the power plant boilers alone, and with the high annual operating and maintenance expenses of the SCRs, Chevron decided to focus on technologies that would prevent NOx formation during combustion rather than relying on post-combustion flue gas treatment.

The Boilers

Power Plant No. 1 utilizes four D.B.Riley (Riley) 140,000 lb/hr watertube boilers (units 1, 3, 4 and 5) along with one Babcock & Wilcox (B&W) 180,000 lb/hr watertube boiler (unit 7). Each boiler was equipped with original manufacturer burners and operated on refinery gas fuel (~25% H2 by volume). All the boilers were also equipped with combustion air pre-heaters that raised the air temperature to between 400 and 500 °F. Each of the Riley boilers used five 40 MMBtu/hr burners, while the B&W boiler used four 70 MMBtu/hr burners.

The TODD® Solution

In mid-1998, the first-generation COOLfuel burners were installed in boiler No. 5. The burners use advanced COOLfuel gas conditioning technology to mix flue gases with the fuel for NOx control. Following an extensive testing period, which clearly demonstrated the viability of these burners for this application, Chevron ordered new COOLfuel burners for retrofit on all of the remaining boilers.

Installation began on January 1, 2000, with a target completion date of July 1, 2000. Along with the burner retrofit, Chevron elected to perform needed repair work, re-certification where applicable, control system modifications and the addition of a Continuous Emissions Monitoring System (CEMS).

The TODD Result

As a result of the COOLfuel technology retrofit, the boilers at Chevron’s Power Plant No. 1 show NOx reductions between 85% and 95%. The relative NOx emissions on each boiler have been reduced to less than 0.03 lb per MMBtu (25 ppm).

NOx emission rates as determined from CEMS data for selected boilers are shown in the following graphs.