Cement Manufacturing - Balancing Growth with Air Quality Requirements
In most areas of the U.S., it appears that the recession is a bad memory and the signs of recovery are all around us. As described by the Portland Cement Association (PCA) on its website, “following the strongest cement consumption gains in seven (7) years in 2012, cement consumption growth will continue in 2013 with a 6.2% increase.” PCA continues to explain that “the accelerated consumption predicted during the second half of 2013 should carry into the following year, with an increase of 9.2% for 2014.” PCA also upwardly revised its long-range projections for 2015-2017, with annual growth during that period expected to be as high as 11.1%. PCA predicts cement consumption levels will reach 120 million metric tons by 2017.
With this good news for U.S. cement plants, as well as similar projects across key construction sectors, the cement industry will need to balance this growth with challenging air quality requirements. A given cement manufacturing process can simultaneously be subject to multiple air quality regulations with varying requirements and compliance deadlines. Specifically, these requirements include the National Emission Standards for Hazardous Air Pollutants (NESHAPs) for the Portland Cement Manufacturing Industry (40 CFR Part 63, Subpart LLL; “PC MACT”); the Commercial and Industrial Solid waste Incinerator (CISWI) Rule (40 CFR Parts 60, Subparts CCCC or DDDD), the NESHAP for Major Sources: Industrial, Commercial, and Institutional Boilers and Process Heaters (40 CFR Part 63, Subpart DDDDD, “Boiler MACT”), and New Source Performance Standards (NSPS) for Portland Cement Plants (40 CFR Part 60, Subpart F). Since both CISWI and Boiler MACT have been given an enormous amount of attention in 2013, in this article we will explore PC MACT in some more detail and then discuss the relationship between these separate but inexorably connected rules.
Brief History of PC MACT
Similar to Boiler MACT, PC MACT has existed for several years, beginning with the promulgation of standards in 1999. Following iterations of comments, reconsiderations, and amendments, revised standards were promulgated on February 12, 2013. PC MACT applies to both major and area sources of HAPs. One (1) of the primary drivers of the revised PC MACT was the impact of the U.S. Environmental Protection Agency’s (U.S. EPA’s) nonhazardous secondary materials (NHSM) rule, which resulted in the reclassification of 23 cement kilns as CISWI units. This required U.S. EPA to recalculate the floors that establish the PC MACT emission standards. With the recalculation of the floor came revisions to the standards for particulate matter (PM); the standards for mercury, total hydrocarbons (THC), and hydrogen chloride (HCl) remained the same as the 2010 version of PC MACT. PC MACT also includes an emission standard for dioxins and furans (D/F). In addition, startup and shutdown emission limits were replaced with work practice standards, and the monitoring requirements for the PM and THC pollutants were modified. Lastly, and potentially most importantly, the compliance date to meet the PC MACT emission standards was extended to September 9, 2015 for existing sources. A more near-term compliance date of February 12, 2014 was established for existing open clinker storage piles.
Affected Sources Under PC MACT
The affected sources in PC MACT consist of kilns, clinker coolers, raw material dryers, and open clinker storage piles. Emission standards and work practice standards are provided for new (post-May 6, 2009) sources and existing sources in normal, as well as startup and shutdown operating modes, that are located at major and area sources of HAPs. Emissions from open clinker piles must be effectively controlled through the use of an enclosure, installing and operating a water spray or chemical dust suppressant, or use of a wind barrier or tarpaulin.
Summary of Performance Testing and Monitoring Requirements
The compliance basis for the PM standards for kilns has been revised to a manual three-run stack test conducted annually. The opacity limits and the requirement for opacity monitoring of kilns and clinker coolers at major sources has been removed from PC MACT (effective September 2015), since facilities will now be required to use a PM continuous parametric monitoring system (PM CMPS) to demonstrate continuous compliance with PM emission limits. For raw material, clinker, or finished product storage bins; conveying system transfer points; bagging system; bulk loading or unloading system; raw and finish mills; and raw material dryers, a 10% opacity limit remains, with the option to use a continuous opacity monitoring system (COMS) or U.S. EPA Method 22. A continuous emissions monitoring system (CEMS) must be used to demonstrate compliance with THC emission standards. Kilns also have operating limits related to the temperature of the gas at the inlet to the kiln PM control device or to the sorbent injection rates, where employed. The operating limits are used as the continuous compliance demonstration methodology for D/F emissions. For mercury, THC, and HCl, initial performance tests using U.S. EPA reference methods are required, followed by the use of CEMS (or a sorbent trap monitoring system for mercury) as the on-going continuous compliance demonstration method. Monitoring of clinker production must be performed on an hourly basis.Based on these requirements, the cement industry will be burdened with significant performance testing, CEMS installation, and operation and maintenance requirements for compliance purposes, particularly compared to other industries.