Tampa Electric will soon complete a comprehensive selective catalytic reduction project on all four units at its Big Bend Power Station that will make Big Bend among the cleanest coal plants in the U.S. The project — the centerpiece of the company’s 10-year, $1.2 billion air quality improvement program — is on schedule to meet all of its air quality improvement goals by mid-2010.
Retrofitting a selective catalytic reduction (SCR) system at any operating plant is a major undertaking, but the retrofit project reaching completion at Tampa Electric’s four-unit Big Bend Power Station (BBPS) in West Central Florida was especially daunting. At one point, three units were under different levels of construction at the same time, with Unit 4 entering service in mid-2007 and the others following at yearly intervals. Another challenge: Much of the work was completed while the units were operating. Even more impressive is how the team accomplished this feat within the restrictive site confines. Imagine juggling basketballs inside a Mini Cooper, and you begin to get some sense of the challenge.
The project had its origin in December 1999, when Tampa Electric became the first utility in the nation to reach an agreement with the U.S. Environmental Protection Agency and the U.S. Department of Justice to resolve the federal agencies’ pending enforcement actions for alleged violations of the New Source Review requirements of the Clean Air Act. The resulting consent decree outlined a compliance plan to significantly decrease overall emissions from the company’s power plants. A key part of the plan was the installation of equipment to significantly reduce NOx emissions at BBPS by 2010. The reduction plans included converting Units 1, 2, and 3 from pressurized furnaces to balanced draft furnaces, comprehensive burner and windbox modification, overfire air changes, as well as adding SCR systems on each of the four coal-fired units (Figure 1).
1. Go big or go home. Tampa Electric’s Big Bend Power Station (BBPS) will soon complete its fourth selective catalytic reduction system upgrade project in as many years. When complete, NOx emissions at BBPS will have been reduced by approximately 90% from 1998 levels. Flue gas desulfurization systems also remove 95% of the SO2 from the four coal-fired units. Courtesy: Tampa Electric
Big Bend unit details. Source: Tampa Electric
By the end of 2010, Tampa Electric will reduce systemwide annual SO2, NOx, and particulate matter (PM) at its facilities by 90%, 90%, and more than 80%, respectively, from 1998 levels.
At BBPS alone, Tampa Electric has invested $330 million in emission control SCR retrofits to make it among the cleanest coal-fired power stations in the U.S. To reduce NOx, Unit 2 SCR went into service in June 2009, Unit 3’s SCR went into service in June 2008, joining the already in-service Unit 4 SCR in achieving substantial emissions reductions at the station. Retrofit of Unit 1 with an SCR will be completed by mid-year 2010, reducing the total NOx emissions at BBPS by approximately 90% from 1998 levels. Flue gas desulfurization (FGD) systems, or scrubbers, remove 95% of the SO2 from the four coal-fired units.
BBPS consists of four pulverized coal – fired units, built from 1970 through 1983. Each unit fires a blend of high-sulfur midwestern bituminous coal and up to 20% petroleum coke. The sulfur content of the fuel blends is typically limited to produce no more than 5.4 lb/mmBtu of SO2. Typical of coal-fired plants of this vintage, the units were equipped only with modest forms of pollution control at the time of construction. Flue gas desulfurization, also known as scrubber technology, has been in use at Big Bend since 1985, when it was first installed on Unit 4. In 1995, the Unit 4 scrubber began scrubbing Unit 3 as well. Scrubbers for Units 1 and 2 began operation at the end of 1999. The SCRs for all four units were designed for outlet NOx levels that would ensure 30-day rolling average compliance under virtually all anticipated operating conditions and to assist in catalyst life longevity (see table).
Big Bend unit details. Source: Tampa Electric
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