Virginia Power testing NOx-reduction process
Virginia Power has voluntarily adopted an operating method that could lead to as much as a 25 percent reduction in NOx emissions from some of its coal-fired units. Called Burners Out of Service (BOOS), the method is being used at nine of the company?s 18 coal-fired units in Virginia, one of the largest applications of the process in the nation. The operating system, which involves changing the way air is delivered to the unit?s boiler, has been in use since Jan. 1. Projections show that NOx emissions in Richmond and Hampton Roads could be reduced by almost 3,000 tons annually by the year 2000. Under a special U.S. Environmental Protection Agency (EPA) program, the use of BOOS could allow the company to meet new emissions standards without installing low-NOx burners which would cost between $6 million and $10 million for each of
OWe think these nine units have a good chance of meeting the federal guidelines without the addition of expensive pollution-control devices. And that helps our efforts to keep rates low and provide economical power for all our customers,O said Robert W. Cartwright, Fossil & Hydro senior vice president. Some of the units using the process will see NOx reductions as high as 25 percent. The average reduction for all nine units will be about 15 percent. BOOS also supports the state?s recent efforts to have two metropolitan areas removed from the EPA?s ozone nonattainment list. Partially because of Virginia Power?s agreement with the state to reduce NOx emissions, Hampton Roads has been taken off the list of areas failing to meet federal ozone standards. An EPA decision on a similar reclassification for the Richmond area is pending. Units using the new system include three at Chesterfield Power Station, three at Chesapeake Energy Center, two at Yorktown Power Station and one at Possum Point Power Station.
The BOOS operating method reduces NOx production by injecting less air at the bottom of the boiler and more air higher up in the boiler. This expands the fireball and lowers the burning temperature without drastically diminishing the total energy output. Because of the lower temperatures, less NOx is produced. The process is accomplished by control room operators and requires no special equipment. The company believes that over the course of a year, it will be able to utilize BOOS enough to reduce average yearly NOx emissions to 0.45 parts/MBtu. Under normal operating procedures, the nine units average between 0.6 and 0.7 pounds of NOx per MBtu.
While some reductions can be achieved when the units are running at full capacity, BOOS is most effective at reduced generation levels, ideally when units are running at between 70 and 80 percent of their maximum outputs. During cold winter weather and hot summer weather, the units operate at higher capacities and cannot use BOOS as often. However, during the more mild spring and fall months, BOOS will be used more. Operators have been instructed to implement the BOOS procedures whenever the units are running at a reduced capacity. If the company can achieve the expected reduction, the units will be eligible to participate in the EPA?s early election program for Phase II of the Clean Air Act Amendments.
Under the early election program, tangentially fired boilers, such as those used at the nine test units, must achieve a yearly average of 0.45 pounds of NOx per MBtu. This is the average emission that the company believes it can achieve with BOOS. Utilities with tangentially fired units that choose not to participate in the early election process must reduce NOx emissions to 0.40 pounds per MBtu by the year 2000, when the amendments go into effect. Utilities in the early election program would not have to meet that standard until 2008.