几十年来，Southern Co.一直是美国最大的电力公司之一，也是煤炭的主要消费者之一。南方认为，燃煤能力应仍然是其一代组合的一部分。它的密西西比电力子公司（Southern Southern四个公用事业公司之一）正在建造美国的最后一个煤炭单元之一计划在今年年底之前排队。

In recent years, however, coal has been on the defensive as the Environmental Protection Agency has tightened emissions requirements on mercury and other toxins and developed regulations to reduce emissions of carbon dioxide and other greenhouse gases.

Southern has responded. The Kemper County IGCC project is designed to capture 65% of the coal unit's CO and pipe it for use in enhanced oil recovery. Just as important, the company has been building new, natural-gas-fired combined-cycle projects, including three 840-MW units at its Georgia Power subsidiary's Plant McDonough-Atkinson, Cobb County, that replaced two coal units in 2011 and 2012, respectively.

More recently, Georgia Power has announced plans to retire more than 2,000 MW of older, coal-fired capacity, rather than retrofit those units with additional emissions controls to bring them into compliance with the EPA's Mercury and Air Toxics Standards (MATS), which go into effect in April 2015.

CUROW

And, between them, Georgia Power and sister utility Alabama Power are planning to convert six older coal units, totaling nearly 1,800 MW, to natural gas. Planning for the conversion of Georgia Power's Plant Yates units 6 and 7 and Alabama Power's Plant Gaston units 1 through 4 is well under way.

Yates units 6 and 7 are each 350-MW, pulverized-coal units that "would be affected by MATS should they retain coal as their primary fuel," says Mark Schwartz, Georgia Power's project manager. The units, in Coweta County, are also subject to the so-called Georgia Multipollutant Rule, "which requires that the units either install selective catalytic reduction equipment and a scrubber or switch from coal to natural gas."

Schwartz说，成本效益分析比较了装备YATES单位6和7的装备和必要的控件，以符合MATS和其他替代方案的多币规则。分析发现，转化为天然气将是最具成本效益的选择。

"The conversion work includes installing natural-gas burners in the boilers and all the necessary electrical upgrades, piping, valves, control-system work and other systems," says Schwartz, noting that Yates already has a natural-gas supply line to the site.

Subsystems Must Be Replaced

"We are currently in the detailed engineering and major-equipment procurement phase of the project," Schwartz says. "The boiler itself remains essentially intact. However, many of the detailed systems or subsystems, such as burners, electrical, piping or control systems, will require changes or replacement."

施瓦茨说，耶茨煤气转换项目由南部的内部建筑管理团队管理。他说：“安装工作将在适当的时间进行竞争性竞标。”

有这么多看似相似的工作计划在雅特es and Gaston, can the work be done in an almost repetitive fashion? "This work cannot be done assembly-line style," says Schwartz. "Although some economies of scale can be realized by working on multiple units, the boilers themselves are large and complex, and the work must be tailored to each unit."