BOARD MEETING DATE: July 9, 2010
AGENDA NO. 26
PROPOSAL:
Implementation Assessment Report for Rules 1146 - Emissions of Oxides of Nitrogen from Industrial, Institutional, and Commercial Boilers, Steam Generators, and Process Heaters and 1146.1 - Emissions of Oxides of Nitrogen from Small Industrial, Institutional, and Commercial Boilers, Steam Generators, and Process Heaters
SYNOPSIS:
Rules 1146 and 1146.1 establish NOx and CO emission limits for non-RECLAIM boilers and heaters greater than 2 mm Btu per hour heat input. The adopting resolutions to the September 5, 2008 amendments to Rules 1146 and 1146.1 directed staff to assess the reliability and performance of ultra low NOx burners and the impact of critical external factors and testing techniques on NOx measurements and report to the Board no later than July 15, 2010. This report summarizes the results of these assessments.
COMMITTEE:
Stationary Source June 18, 2010, Reviewed
RECOMMENDED ACTIONS:
Receive and file.
Barry R. Wallerstein, D.Env.
Executive Officer
Introduction
Rules 1146 and 1146.1 regulate emissions of oxides of nitrogen (NOx) and carbon monoxide (CO) from industrial, institutional, and commercial boilers, steam generators, and process heaters. These rules apply to non-RECLAIM boilers, steam generators, and process heaters with maximum rated heat input capacities between 2 and 5 million Btu per hour (Rule 1146.1) and greater than or equal to 5 million Btu per hour (Rule 1146).
On September 5, 2008 Rules 1146 and 1146.1 were amended. The amended rules require approximately 1,600 natural gas-fired boilers and heaters to lower the NOx emission level from 30 to 9 ppm (sealed burners 1). The preferred means to comply with these new limits is retrofitting the boiler or heater with an ultra low NOx burner (ULNB) system. The Rule 1146 and 1146.1 compliance dates range from January 1, 2012 through January 1, 2015, depending on the unit’s rated heat capacity, number of units at the facility, and type of service (e.g., supplying steam at a university). The cost-effectiveness to comply with the 9 ppm level ranged from approximately $10,000 to $30,000 per ton.
During the rulemaking process it was acknowledged that
External influences such as ambient temperature and humidity may hinder the unit from complying with the 9 ppm NOx compliance level on a consistent basis.
There may be limitations on the availability of ULNBs that would be required to retrofit the 1,600 affected boilers and heaters.
Staff, through an adopting resolution committed to continue to work with industry and their interested parties to further study these two issues and report back to the Board prior to the effective dates of the proposed limits and no later than July 15, 2010.
Public Process
On June 9, 2010 a Task Force meeting was held to present the information in this report and solicit input. Subsequent to the Task Force meeting, this report was discussed at the Stationary Source Committee on June 18, 2010.
Response to the Adopting Resolution
To address the resolution commitment, staff compiled information on 245 installations in both the San Joaquin Valley Unified Air Pollution Control District (SJVUAPCD) (~460 source tests on existing units) and the SCAQMD (new boilers). Based on the information compiled, it appears that the ULNB can reliably meet the 9 ppm compliance limit set by the BACT guidelines and recently amended District Rules 1146 and 1146.1. In addition there are several burner manufacturers that have provided compliant ULNBs to the regulated community.
In order to evaluate the affect of external factors (e.g., ambient temperature and relative humidity) on NOx emissions, staff performed a statistical analysis on one year of continuous emissions monitoring system (CEMS) data from a non-RECLAIM boiler equipped with a 9 ppm ULNB. The results of the CEMS data analysis indicate that ambient temperature and relative humidity did not significantly impact NOx emissions from this particular boiler. However, as pointed out during the June 9, 2010 Task Force meeting this conclusion may only be applicable to boilers and heaters with flue gas recirculation (FGR) and parallel positioning with oxygen trim 2, i.e., equipment that was installed on this boiler.
Conclusions and Recommendations
Based on the previously mentioned SJVUAPCD source test data the 9 ppm ULNB appears to be both available and performing adequately. The analysis on the selected boiler equipped with a CEMS indicate some (although infrequent) exceedances in NOx most likely due to improper boiler operator procedures. On this basis, it is recommended that there should be:
A greater emphasis on boiler operator training.
Limited access to burner controls for start up, steam/firing rate and shut down by untrained operators. Errors by untrained operators often lead to noncompliance.
More frequent maintenance of boiler burner and control system should be encouraged.
The analysis did indicate that the selected boiler was not affected by ambient temperature or relative humidity. As previously mentioned, the fact that this boiler was equipped with an FGR and parallel positioning with oxygen trim may have contributed to the reliable performance of the ULNB. On this basis, staff is recommending to continue monitoring ULNB installations and source test results for another 12 months and report the findings back to the Task Force. Particular attention should be focused on the installations in the SJVUAPCD and the possible influence that ambient pressure may have on ULNB’s ability of maintaining the 9 ppm NOx limit. Through a cooperative effort with this agency it is anticipated that more data can be developed in order to better ascertain the impact of external factors on the performance of 9 ppm ULNBs.
More details on this report’s analysis, including a list of the 9 ppm boilers and heaters in the SJVUAPCD and the CEMS data for the selected boiler in the SCAQMD, are presented in the attached staff report.
1 The term “sealed burners” is used to distinguish them from atmospheric burners which utilize a non-sealed combustion chamber in which natural draft is used to exhaust combustion gases. The atmospheric burners are required to comply with a less stringent limit of 12 ppm (0.015 lbs/106 Btu).
2 Parallel positioning with oxygen trim refers to a set of electronic and mechanical devices which respond automatically to changing loads (e.g., steam output) to maintain an optimized flame temperature.
Attachment (DOC, 8M)
Staff Report - Implementation Assessment Report on Ultra-Low NOx Burners subject to Rules 1146 and 1146.1