A recently proposed EPA rule may rekindle the mercury CEMS and sorbent trap market...
On April 21, 2009, the USEPA proposed to reduce mercury emissions from Portland cement kilns. There are currently 93 portland cement plants operating 163 kilns and associated clinker coolers in the U.S. that are expected to be affected. These plants represent the fourth-largest source of mercury air emissions in the U.S.
The proposal, known as a Maximum Available Control Technology standard, or MACT standard, would set the nation’s first limits on mercury emissions from existing Portland cement kilns and would strengthen the limits for new kilns. The EPA believes that the proposed new source MACT "floor" is approximately 30 percent lower than the not-to-exceed standard EPA promulgated in December 2006, which was 41 µg/dscm.
The proposed MACT standards also would set limits for emissions of total hydrocarbons (THC), particulate matter (PM), and sulfur dioxide (SO2) from cement kilns of all sizes, and would reduce hydrochloric acid (HCl) emissions from large kilns. Under the proposed amendments, existing kilns would be expected to add one or more control devices to meet MACT, most likely a wet scrubber and activated carbon injection (ACI).
Each kiln would also be required to install continuous emissions monitoring systems (CEMS) to monitor mercury, THC and HCl. Direct PM monitoring would not be required; instead, bag leak detectors (BLDs) would be required to monitor performance of all baghouses.
Existing facilities will have three years after the promulgation to comply with the new emission limits for mercury, THC, PM, and HCl. This is the maximum period allowed by law. Most facilities will need this time, since they will likely have to install new emissions control devices to comply with the emissions limits. For new sources (i.e., those that started construction after December 5, 2005), the compliance date will be the date of publication of the final rule or startup, whichever is later.
Generally, mercury emissions from cement kilns reflect the amounts of mercury in the feedstock and fuel inputs of the kilns. The EPA assumes that nearly all the mercury entering a kiln eventually leaves as a stack emission. Usually, up to 80% of the mercury emissions result from trace contaminants of mercury present in the limestone, which typically comes from a quarry located adjacent to the plant. Mercury is also found as a trace contaminant in the other inputs to the kiln such as silica, alumina, and iron, as well as the coal and petroleum coke used to fuel the kilns.
Since the mercury content of the feed and fuels is believed to vary significantly from day-to-day, cement kilns do not emit mercury uniformly. This variation is compounded in modern preheater and preheater/precalciner kilns that have in-line raw mills. Consequently, short term emission tests would not be expected to provide a good indication of long term mercury emissions from cement kilns.
Therefore, the proposed rule will require plants to install either instrument based or sorbent trap based mercury monitoring systems that meet either the requirements of PS-12A or PS-12B. These performance specifications are being added into 40 CFR 60, Appendix B as part of the proposed rule changes (they had been removed after CAMR was vacated
The EPA states that they “see no technical basis to say that [mercury CEMS or sorbent trap monitoring systems] will not work as well on a cement kiln as they do on a utility boiler. In addition, we are aware that there are 34 cement kilns that have operating continuous mercury monitors in Germany.”
We'll see if the rest of the industry agrees. The proposed rule is currently in the midst of a 60-day comment period that expires on or about June 20th. After that, we’ll have to see what, if any changes the EPA makes before publishing the final rule. Stay tuned…
More information on EPA’s Official Site.
On April 21, 2009, the USEPA proposed to reduce mercury emissions from Portland cement kilns. There are currently 93 portland cement plants operating 163 kilns and associated clinker coolers in the U.S. that are expected to be affected. These plants represent the fourth-largest source of mercury air emissions in the U.S.
The proposal, known as a Maximum Available Control Technology standard, or MACT standard, would set the nation’s first limits on mercury emissions from existing Portland cement kilns and would strengthen the limits for new kilns. The EPA believes that the proposed new source MACT "floor" is approximately 30 percent lower than the not-to-exceed standard EPA promulgated in December 2006, which was 41 µg/dscm.
The proposed MACT standards also would set limits for emissions of total hydrocarbons (THC), particulate matter (PM), and sulfur dioxide (SO2) from cement kilns of all sizes, and would reduce hydrochloric acid (HCl) emissions from large kilns. Under the proposed amendments, existing kilns would be expected to add one or more control devices to meet MACT, most likely a wet scrubber and activated carbon injection (ACI).
Each kiln would also be required to install continuous emissions monitoring systems (CEMS) to monitor mercury, THC and HCl. Direct PM monitoring would not be required; instead, bag leak detectors (BLDs) would be required to monitor performance of all baghouses.
Existing facilities will have three years after the promulgation to comply with the new emission limits for mercury, THC, PM, and HCl. This is the maximum period allowed by law. Most facilities will need this time, since they will likely have to install new emissions control devices to comply with the emissions limits. For new sources (i.e., those that started construction after December 5, 2005), the compliance date will be the date of publication of the final rule or startup, whichever is later.
Generally, mercury emissions from cement kilns reflect the amounts of mercury in the feedstock and fuel inputs of the kilns. The EPA assumes that nearly all the mercury entering a kiln eventually leaves as a stack emission. Usually, up to 80% of the mercury emissions result from trace contaminants of mercury present in the limestone, which typically comes from a quarry located adjacent to the plant. Mercury is also found as a trace contaminant in the other inputs to the kiln such as silica, alumina, and iron, as well as the coal and petroleum coke used to fuel the kilns.
Since the mercury content of the feed and fuels is believed to vary significantly from day-to-day, cement kilns do not emit mercury uniformly. This variation is compounded in modern preheater and preheater/precalciner kilns that have in-line raw mills. Consequently, short term emission tests would not be expected to provide a good indication of long term mercury emissions from cement kilns.
Therefore, the proposed rule will require plants to install either instrument based or sorbent trap based mercury monitoring systems that meet either the requirements of PS-12A or PS-12B. These performance specifications are being added into 40 CFR 60, Appendix B as part of the proposed rule changes (they had been removed after CAMR was vacated
The EPA states that they “see no technical basis to say that [mercury CEMS or sorbent trap monitoring systems] will not work as well on a cement kiln as they do on a utility boiler. In addition, we are aware that there are 34 cement kilns that have operating continuous mercury monitors in Germany.”
We'll see if the rest of the industry agrees. The proposed rule is currently in the midst of a 60-day comment period that expires on or about June 20th. After that, we’ll have to see what, if any changes the EPA makes before publishing the final rule. Stay tuned…
More information on EPA’s Official Site.
