It’s only one year away. In 2009, the Clean Air Interstate Rule (CAIR) will begin taking effect, requiring the largest pollution reductions of any single emissions rule in recent history. Power generators have started bringing out “the big guns” and installing highly effective – albeit decidedly expensive – hardware to help meet these new emissions standards. Innovative power generators are fast learning that combining these hardware solutions with closed-loop optimization software can be an even more effective way of addressing CAIR regulations while improving operations.
Complying with CAIR
CAIR is a very big deal, and power plants in the District of Columbia and the 28 states affected by these regulations will have to make substantial provisions in order to comply with these new standards. To put it in historical perspective, regulations between 1970 and 2006 decreased US NOx (nitrogen oxide) levels by 41 percent. That’s 36 years that power plants had to cut NOx emissions almost in half. CAIR by contrast, requires a 60 percent reduction in just six years (2009-2015).
It’s no wonder that more and more power generators are installing SCR (Selective Catalytic Reduction) systems. SCRs convert NOx in the flue gas boiler into diatomic nitrogen and water. Highly effective, a typical SCR system can lower NOx by 70 to 90 percent. But while SCR systems can be extremely effective, they have also turned out to be far more expensive than initially anticipated – both in terms of capital and operating costs.
Capital and operating costs of SCRs
The demand for SCRs due to CAIR, combined with massive demand for steel and craft labor driven by China’s economic growth, are not only increasing the cost of SCRs but impinging on their timely availability. SCR systems also require reagents such as ammonia (NH3) – the price of which has recently more than doubled. Operations issues such as ammonia slip, the formation of ammonium sulfate and ammonium bisulfate, and excess SO3 can all result from SCR use. In addition, many SCR systems were designed to operate during the SIP (State Implementation Plan) five-month Ozone Season, giving generators seven months to get their SCRs in shape for the next season. CAIR is a year-round affair, and will force generators to push these systems and operate the SCRs more frequently. As power generators begin running SCRs year-round, operations costs and negative operations impacts will correspondingly increase.
Combining Optimization with SCRs
To lower SCR-related costs and mitigate negative operations side-effects, power generators are adding closed-loop optimizers such as CombustionOpt® and SootOpt® to their systems. These comparatively inexpensive software solutions reduce NOx at the source and allow power generators to run SCRs less frequently. Power plants with closed-loop optimizers minimize their SCR-related costs by reducing ammonia consumption, mitigate negative SCR-related side-effects, and simultaneously improve combustion and sootblowing operations.
While power plants are looking for “big” solutions to deal with CAIR’s enormous implications, it’s important that we keep an eye on all the pieces of a NOx-lowering solution. Power generators investing in SCRs – the “big guns” of NOx reduction –actively need to plan for and manage SCR-related costs and operations impacts.
I’m interested in hearing from power generators who have SCRs, or are considering investing in SCRs. Does your plant have a plan or system in place to mitigate associated SCR operations costs and issues?
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