Westbrook Energy Center - Executive Summary |
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EXCUTIVE SUMMARY The Westbrook Energy Center located in Westbrook, Maine generates electric power by burning natural gas in a gas turbine. As part of its emissions control it injects diluted ammonia vapor into the turbine exhaust and thus reduces NOx emissions. The ammonia is stored in a 29.5% aqueous solution in a 20,000 gallon vertical tank. The ammonia is piped in liquid form to a vaporizer where it is diluted with air and heated to a gas. This gas is injected into the turbine exhaust gases in the Heat Recovery Steam Generator (HRSG). The facility has strictly implemented preventative maintenance procedures and an Emergency Response Plan (ERP). The release of ammonia is specifically covered in the ERP and contains all emergency contact numbers as well as employee safety and mitigation procedures. As part of the facility's accidental release prevention, training is conducted annually for employees on Hazardous Materials Handling. Hazard Communication, Emergency Response, Spil l Prevention, safe operation, maintenance, and emergency procedures. There is a specific procedure for delivery and handling of anhydrous ammonia, which includes specific operational guidelines as well as emergency actions. The Westbrook Energy Center is a newly constructed facility as of December, 2000 and therefore has had no ammonia related accidents or releases. The facility modeled two off-site consequence analyses. The first was a worst-case scenario that consisted of a full release of the aqueous ammonia storage tank which, due to administrative procedures, is 17,000 gallons (127,602 lbs) instantaneously. However the evaporation rate of the solution would be 22.3 lbs per minute. This scenario had a toxic endpoint radius of 0.3 miles. The second analysis was an alternative release scenario that consisted of a delivery hose rupture. The release would cause 500 pounds of aqueous ammonia to be spilled at a rate of 100 lbs/min for 5 minutes. This scenario established a toxic endpoint radius of 0.1 miles. The Westbrook Energy Center has completed and is actively implementing a Risk Management Plan. The facility is in full compliance with all provisions of the RMP. |