SCIENTIFIC REVIEW COMMITTEE MEETING -
July 25, 2002

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The handouts and audiotapes can be obtained through the Public Records Section of the Chief Prosecutor’s Office. There may be a fee for this service.

Marty Kay welcomed the SRC members and the audience to the meeting. The topics listed below were discussed during the meeting.

Minutes of May 23rd Meeting

Responses to Comments from May 23rd Meeting

New BACT - Part B Listings

Update to Part D (MSBACT) for Emergency Diesel Engines

Other Business

 

A committee member commented on the discussion of the water treating/air stripping system (Sunoco Chemical, PA-51-1551). It had been reported at the meeting and entered in the minutes that the plant continuously monitored VOC in the stripper outlet air and the system would shut down if flammability limits are approached too closely. The committee member wished to clarify that the VOC monitoring was probably not of CEMS quality and requested that the wording be changed to reflect this. AQMD agreed to check with the plant and make the information more specific. (Greg Adams, Los Angeles County Sanitation Districts; Howard Lange, AQMD)

Regarding the nine new Part B listings of emergency diesel engines meeting USEPA Tier 2 nonroad standards that had been presented in the January meeting, discussion had continued in the May meeting, and AQMD was to look into what testing requirements might be imposed on a new Tier 2 engine in a Title V facility. It was learned that the AQMD Title V team believes that testing every five years may, in general, be required. Although permit engineers that were contacted indicated that periodic testing is not presently being required in Title V permits for emergency engines, it was concluded that there is a potential for testing to be required on a Tier 2 engine. Since a Tier 2 engine is not required to comply with the Tier 2 emission standards at every load, single-load testing is not appropriate. However, the committee felt that multiple-load testing in the field would be too costly. Committee members were therefore of the opinion that testing should not be required for Tier 2 engines. In that testing requirements are triggered by emission limits, the committee felt that permits for Tier 2 engines should generally require use of a Tier 2 engine without stipulating emission limits. However, it was also agreed that a permit could stipulate the Tier 2 emission limits along with a periodic testing requirement at one load. This allows for the case of a non-certified engine that does meet the Tier 2 standards at the expected operating load. Since this subject was to be discussed further later in the meeting (emergency diesel engine MSBACT agenda item), final conclusions regarding BACT were not reached at this point in the meeting. (Karl Lany, SCEC; Gary Rubenstein, Sierra Research; Howard Lange, AQMD; Marty Kay, AQMD).

Regarding the new Part B listing for screen printing, the permit file had indicated that, even though the applicant planned to use inks with extremely low VOC contents, the permit limit on VOC in inks was set at 50 g/l because it was believed that measurements of lower VOC contents would be inaccurate. A committee member had pointed out that VOC limits in some substances governed by other rules were soon going to be 25 g/l, indicating that measurement of VOC contents as low as 25 g/l are considered accurate. AQMD was to check with the permit engineer who had prepared this permit to see whether there was any inconsistency in policy. In checking with the permit engineer, it was learned that she was aware that limits as low as 25 g/l were soon taking effect and that the 50 g/l limit had actually been set for reasons of allowing the applicant sufficient flexibility to use a range of inks. (Howard Lange, AQMD)

Regarding the new Part B listing for ink jet printers (Metromedia, A/N 327543), AQMD was to determine whether or not the permit required that cleanup solvents used at this facility have VOC contents of 50 g/l or less for compliance with Rule 1171. It was found that the permit does not contain a 50 g/l limit on cleanup solvents. Rule 1171 compliance is achieved by cleaning up within the enclosed area of the facility, which is vented to a control device. (Howard Lange, AQMD)

This facility produces aluminum wheels for automobiles. Four reverberatory furnaces, rated at from 3 to 12 MMBtu/hr thermal input, are used to melt scrap aluminum from machining operations together with "sows" (aluminum ingots). These furnaces were installed in 1995 as replacements for four existing furnaces. The original furnaces were equipped with air preheat systems. As a means to lower NOx emissions, the air preheat systems were eliminated when the new furnaces were installed and the new furnaces were equipped with burners specifically designed for unheated air. The facility, which is in RECLAIM, recently applied for a permit modification to change the NOx emission calculation method from use of the default NOx factor to concentration limits of 43 ppmvd (corrected to 3% O2) for all four furnaces. Compliance with the 43 ppm limits was demonstrated by a source test in March 2001. The source test was reviewed and accepted by AQMD’s Monitoring & Source Test Engineering group, and the permit modification was granted in October. (Howard Lange, AQMD)

Discussion: One committee member objected on the basis that (1)the NOx concentration limits are not permanent, (2) the equipment used to achieve the low NOx levels in this case may not be generally available, (3) six months of compliance was not proven by one source test, and (4) the 43 ppm limits may not be achievable on all aluminum melting furnaces. Regarding item (1), in additional discussion, it was concluded that the facility would face New Source Review if it later decided to increase the NOx limits, and the limits are therefore essentially permanent. Regarding item (2) the type of burner used for non-preheated air is commercially available, as noted in the listing. Regarding item (3), AQMD stated that, while continuous compliance with the NOx limits cannot be determined, the furnaces do meet the achieved-in-practice criteria. Regarding item (4), AQMD responded that Part B listings are intended only as examples to be applied on a case-by-case basis. (Steve Simon, SEMPRA; Marty Kay, AQMD)

A committee member suggested that line 5A2 in the listing be left blank because this does not represent a BACT determination in the usual (New Source Review) sense. AQMD responded that the entry was not meant in that sense, but was meant in the sense that this is a BACT determination for future use. However, AQMD agrees that this may be confusing and will clarify it in the listing. (Gary Rubenstein, Sierra Research)

A committee member noted that in the source test, two of the furnaces had to be adjusted in order to achieve the reported NOx levels, thus indicating that continuous compliance was probably not the case. He suggested that this be noted in the listing. (Gary Rubenstein, Sierra Research)

A committee member pointed out that eliminating air preheat, while reducing NOx concentration, also reduces thermal efficiency of the furnaces, which tends to increase mass emissions of NOx as well as other pollutants. AQMD responded that this point is well taken and should be considered in permitting. The committee member also noted that the NOx concentration limits apply to gas fuel only and not to propane fuel, which the furnaces are also allowed to use. AQMD agreed to clarify this in the listing. (Greg Adams, Los Angeles County Sanitation Districts; Marty Kay, AQMD)

This is a 6 MMBtu/hr reverberatory furnace used to melt aluminum and zinc. Like Superior Industries, discussed above, this facility is in RECLAIM and applied for a NOx concentration limit on this furnace. The furnace had been retrofitted with low-NOx burners. A source test in August 2001 demonstrated that the furnace could achieve the requested NOx concentration limit (39 ppmvd, corrected to 3% O2). The source test was reviewed and accepted by AQMD’s Monitoring & Source Test Engineering group, and the permit modification was granted in October 2001. (Howard Lange, AQMD)

Discussion: A committee member noted for the record that the comments made by the committee regarding Superior Industries basically apply also to this listing. (Gary Rubenstein, Sierra Research)

An audience member commented that the source test was done at high fire and did not document the emissions at reduced firing rates or modulating conditions. AQMD responded that this type of furnace does not typically operate at reduced firing levels nor does it modulate. (Howard Lange, AQMD)

A committee member noted that the furnace operated at extremely high O2, which means that the measured NOx level was on the order of a few ppm, making the accuracy of the measurement questionable. However, as had been noted, the test was reviewed and accepted by AQMD'’ Monitoring & Source Test Engineering group. (Bill Dennison, Dennison & Associates)

This is a large spray room in which undercoating is applied to recreational vehicle chassis. The exhaust flow is 24,000 cfm. A low-VOC (1.23 lb/gal), water-reducible enamel is used. To keep its VOC emissions below 4 tpy, the facility chose to accept a permit requirement for add-on control with minimum 85.5% overall control efficiency. The spray room and it’s venting system meet the criteria for a permanent total enclosure (EPA method 204). The room is vented to a VOC control system consisting of three carbon canisters, each containing 4000 lb of activated carbon. VOC in the outlet air is required to be checked twice daily using an AQMD-approved analyzer and is not to exceed 5 ppm as methane. The activated carbon is changed out based on the amount of coating material processed. The spray room began operation in 2000. (Marty Kay, AQMD)

Discussion: A committee member asked what analyzer is being used to check the VOC content of the outlet gas. AQMD responded that it did not have the details at hand, but would obtain this information for the next meeting. (Greg Adams, Los Angeles County Sanitation Districts)

A committee member commented on one of the permit conditions included in the BACT listing, which is that the sprayed chasis not be removed from the spray room until the enamel is dry to the touch. The comment was that this restriction may not be feasible for a continuous operation, for example where small parts are moving through on a continuous line. (Bill Dennison, Dennison & Associates)

This facility is an industrial gas manufacturer. The device in question is a hydrogen reforming furnace, which is a process heater, similar to those used in refineries. Steam and methane are passed through the tubes in the process heater, which are filled with catalyst, to produce a hydrogen-containing gas. This gas is further processed to obtain a relatively pure hydrogen product gas. The process heater is rated at 117.6 MMBtu/hr. The primary fuel is pressure-swing adsorber gas, which is a waste stream from the process. NOx emissions are controlled by low-NOx burners (LNB) and selective catalytic reduction (SCR). The permit limits NOx and ammonia emissions both to 5 ppmvd, corrected to 3% O2 (1-hour average). The Permit to Construct was issued in March of this year. The unit has not yet started up. A source test is required. (Marty Kay, AQMD)

Discussion: A committee member questioned the fact that AQMD was listing this case in advance of the source test. AQMD responded that its general policy is to list cases pending completion of source test so that applicants will be informed as to what is being required. Another committee member asked whether AQMD then updated such listings after the source test is done. AQMD responded in the affirmative. (Greg Adams, Los Angeles County Sanitation Districts; Marty Kay, AQMD)

This is a combined-cycle gas turbine power plant that is operating and has passed its initial source test. It is thus an important addition to AQMD’s combined-cycle power plant BACT listings. This plant has two GE gas turbines with heat recovery steam generators and duct burners. There is a common steam turbine. The plant is rated at 518 MW. The gas turbines have inlet air cooling and are equipped with dry low-NOx burners, oxidation catalysts and SCR systems. The NOx limit is 2.5 ppmvd (@15% O2 based on a one-hour average. However, during the first two years of operation, a three-hour average can be used if the unit would be in violation on a one-hour basis and the cause of elevated NOx is related to "transient conditions". The CO and ammonia limits are 6 ppmvd and 10 ppmvd (@ 15% O2), respectively, on a three-hour basis. There is also a POC ("precursor organic compounds") limit of .0017 lb/MMBtu, which AQMD calculated to be approximately 1.3 ppmvd @15% O2. The definition of POC seemed to be equivalent to VOC. The plant has been in operation, with a high utilization factor, since July 2001. A source test in August 2001 showed all emission passing with the exception of high POC. The high POC was thought to be due to out gassing from coating materials, and a retest in October 2001 indeed showed the POC to have subsided to levels below the permit limit. (Howard Lange, AQMD)

Discussion: A committee member clarified that: (1) POC is indeed equivalent to VOC, (2) the GE turbine model is 7FA (the overall combined-cycle model No. had been entered in listing), and (3) the POC limit translates to 1.4 ppmvd@15%O2. This committee member further noted that the initial high POC levels had been noted also on two other combined cycle plants and the combined data from the three plants show that 1000 to 2000 hours of operation is required until the POC emissions level out. He also noted that a fourth plant did not exhibit the initial high POC, showing that the phenomenon is not universal and depends upon manufacturing/construction methods. (Gary Rubenstein, Sierra Research)

A committee member asked about the method used to measure POC. Another committee member responded that USEPA Method TO-12, an ambient air method normally used to measure toxic hydrocarbons or ozone precursors in air, had been used. USEPA Method 25, which is normally used for VOC in turbine exhaust, was found to have insufficient resolution for the low POC levels in this case. Use of TO-12 was proposed by the applicant and accepted by CEC and BAAQMD. (Greg Adams, Los Angeles County Sanitation Districts; Gary Rubenstein, Sierra Research)

A committee member noted that the ammonia limit in this case was 10 ppmvd (corrected to 15% O2) whereas in the previously discussed process heater case it was 5 ppmvd (corrected to 15% O2) and asked which limit would tend to be used in permitting. AQMD responded that Part B listings are examples, and permit engineers have to exercise judgements. In general, achieving a higher percentage NOx reduction comes at the expense of higher ammonia slip. Other committee members added that various turbine models have different inherent NOx levels, and the turbine model used in this case is a relatively low-NOx model. (Hal Taback, Hal Taback Co.; Gary Rubenstein, Sierra Research; Bill Dennison, Dennison & Associates; Howard Lange, AQMD)

A committee member asked what method is generally used to measure ammonia in turbine exhaust. AQMD and another committee member responded that EPA Method 207 and BAAQMD Method ST1B, which are similar wet chemical methods, are used. (Greg Adams, Los Angeles County Sanitation Districts; Gary Rubenstein, Sierra Research; Marty Kay, AQMD)

A committee member suggested the following changes in the listing: (1) Rule 1146 does not apply, (2) the plant is licensed for peaking operation as well as reduced-load operation at as low as 60% of rated load, (3) the correct facility name is Los Medanos Energy Center, (4) there is no "h" in Pittsburg, and (5) the oxidation catalyst is placed upstream of the SCR catalyst. (Gary Rubenstein, Sierra Research)

This is a large tee-shirt manufacturing facility. Six Sellers boilers, each rated at 16.5 MMBtu/hr, are used for process steam. The boilers were installed in 1998 and were subjected to permit limits on fuel utilization in order to restrict NOx emissions to below 4 tons per year, to keep the facility out of RECLAIM. More recently, production at the facility began to increase, and the facility needed to fire more fuel. To be able to eliminate the fuel restriction while continuing to stay below 4 tons per year of NOx emissions, the facility decided to install SCR systems on four of the boilers and accept permit limits of 5 ppmvd (corrected to 3% O2) on those boilers.

The Sellers boiler is somewhat unusual in that it is an on/off type boiler. This makes it better suited for SCR than most boilers because the ammonia system just needs to be on or off, with no need for modulating the ammonia flow rate. It is also unusual in that it has no furnace cavity. It is a one-pass firetube boiler with the single pass of tubes immersed in water, and each tube is equipped with a small burner. The inherent NOx level of this boiler with its LNB is approximately 20 ppmvd (corrected to 3% O2).

Discussion: A committee member asked why this listing was placed in Section III. AQMD responded that this listing, if in Section I, would effectively lower the NOx BACT for relatively small boilers located in major polluting facilities to 5 ppmvd (corrected to 3% O2), which is a serious step needing careful consideration and extremely good technical basis. The technical evidence that these SCR systems are working effectively is limited in that thus far only one of the four boilers has been source tested. Another committee member asked whether this listing affects only major polluting facilities. AQMD responded that Part B Section I, II and III listings apply only to major polluting facilities and that technologies listed in Section III are not intended to be required in permits, but rather to be utilized by applicants on a voluntary basis. (Gary Rubenstein, Sierra Research; Greg Adams, Los Angeles County Sanitation Districts; Marty Kay, AQMD)

A committee member noted that, considering the on/off nature of the Sellers boiler, the average NOx emission over an extended period that includes on/off cycles is probably higher than the emission level measured during a source test with the boiler on full fire throughout the test period. AQMD agreed that it would be desirable to measure the NOx level over an on/off cycle. AQMD also noted that, due to a currently high production rate, the four SCR-equipped boilers at Allstyle currently experience relatively infrequent on/off cycles and the off periods are very brief, but this may not always be true and is unlikely to be true in all cases. The local sales representative for Sellers offered information that the Sellers boiler, due to its unique design, warms up relatively quickly. He stated that, after a shutoff, the boiler can be back to normal (at or near design exit gas temperature) in a minute or less if the shut-off is brief, and can be brought from cold standby to normal temperature in approximately 18 minutes. He also noted that all four boilers at Allstyle had been "spot checked" (emissions test not meeting AQMD standards) on one occasion following the single-boiler source test, all four were source tested recently to comply with Rule 1146, and all of those test reports have been provided to AQMD. Another audience member pointed out that some small boilers and water heaters do not have exit gas temperatures high enough to permit SCR catalysts to function successfully. (Hal Taback, Hal Taback Co.; Marty Kay, AQMD; Howard Lange, AQMD; Imran Husain, Global Equipment Sales)

Earlier this year, nine new listings of emergency diesel engines complying or nearly complying with USEPA Tier 2 nonroad emission standards were added to Part B of the BACT Guidelines. Part B affects only major polluting sources. Part D of the Guidelines, which is mandatory in all NSR permits, still requires that emergency diesel engines meet less stringent Tier 1 USEPA nonroad standards. AQMD plans to propose to its governing board, at the October board meeting, to update Part D to require that all new emergency diesel engines rated above 50 hp meet the Tier 2 emission standards, unless such engines are not commercially available. A preliminary draft staff report supporting this request had been sent to the committee members and others who receive Scientific Review Committee meeting announcements and was available at the meeting.

Phasing in of the Tier 2 standards began January 1, 2001, and nonroad diesel engines in the 300 to<750 hp range are currently required to meet the Tier 2 standards. AQMD is proposing that the new Part D BACT take effect January 1, 2003 for engine sizes for which the Tier 2 standards are already in effect and take effect for other engine sizes six months after the USEPA compliance deadline for each engine size range. This proposed Part D update meets all AQMD and Senate Bill 456 criteria for updating minor source BACT.

Noting that Rule 431.2 requires that, on or after June 1, 2004, fuels purchased for diesel engines must be ultra low-sulfur (less than 15 ppm), AQMD also proposes to update Part D for emergency diesel engines to reflect this future requirement. (Marty Kay, AQMD)

Discussion: A committee member commented on the cost analysis in the preliminary draft staff report. He stated that the cost differential between a Tier 2 and a Tier 1 engine that was used in the analysis appears low but added that using a higher figure that he had determined to be more correct still did not exceed the cost-effectiveness criterion that AQMD has established for MSBACT. However, he did object to the assumption of 200 hours per year of operation in the cost analysis. He also asked whether the International engine, one of the examples of 12-months of service that was cited in the report, was a Tier 2 engine. AQMD responded that it was. He also asked for clarification of the footnote on the proposed updated guideline regarding USEPA’s averaging, banking, and trading program. AQMD responded that the footnote is intended to allow for the unlikely case that, as a result of manufacturers taking advantage of the averaging/banking/trading provision in the USEPA requirements, no manufacturer produces an engine of a given size that actually meets the Tier 2 standards. In this case, MSBACT for this engine size would become the family emission limits established by the manufacturer. (Karl Lany, SCEC; Marty Kay, AQMD)

Referring to the earlier discussion regarding the triggering of performance test requirements in permits issued for new diesel engines (see above, under "Responses to Comments from the May 23^rd Meeting") a committee member suggested that the updated Part D BACT for emergency diesel engines require use of a Tier 2 certified engine rather than compliance with the Tier 2 standards. Other committee member strongly supported this suggestion. AQMD agreed but added that the emission limits should be retained as an alternative compliance method to allow applicants the option to modify an uncertified engine to meet the Tier 2 standards. (Gary Rubenstein, Sierra Research; Bill Dennison, Dennision & Associates;Karl Lany, SCEC; Marty Kay, AQMD)

AQMD announced that the final version of CARB’s permitting guidance for distributed generation devices is now available. This document, provides BACT guidelines for small gas turbines (<50 MW) and engines used for electrical generation. Copies of the title page, table of contents and executive summary were available at the meeting. The full document is available on CARB’s web site. (Marty Kay, AQMD)

AQMD called attention to a recent Federal Register notice that USEPA is soliciting proposals for development, maintenance and promotion of a new web-based database of new and emergent air technologies. A copy of the notice was included in the meeting agenda package. (Marty Kay, AQMD)

The next meeting was scheduled for September 26, 2002 at 1:00 p.m. in AQMD conference room GB.

There was no further discussion, and the meeting was closed

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