TC Ravenswood LLC on Aug. 1 notified the New York State Public Service Commission and other parties that it intends to “mothball” the 42-MW (nameplate) unit GT 3-3 on Oct. 31 of this year.
Notices also went out to the New York Independent System Operator (NYISO), Consolidated Edison Co. of New York and the New York State Reliability Council.
GT 3-3 commenced operations in 1970. Over the past months, several operational and maintenance issues have occurred. Since May 27, GT 3-3 has been in a series of six extended forced outages to make repairs to the stack, perform visual inspection of the gas expander and address elevated vibration in the unit. This summer, GT 3-3 has only been run twice for a total of 21 minutes.
The vibration in the unit, the inspections of the expander and recent repairs to GT 2-3 and 3-4 have raised concerns that another catastrophic event like the May 29, 2013, failure and subsequent tire in GT 2-3 could occur in GT 3-3 if it was brought back into service, said the company. Failure of GT 3-3 could possibly damage other adjacent units as well.
Most recently, beginning on July 22, GT 3-3 was forced offline due to continued high vibration on the gas expander component of the unit. The GT 3-4 expander was recently overhauled and a replacement expander for GT 2-3 is now being overhauled. Substantial additional investments are being made in GT 3-4 and 2-3 before they return to service.
“Given the catastrophic nature of the 2013 failure of GT 2-3, TransCanada does not want to jeopardize these investments in adjacent units GT 2-3 and 3-4 with the possible failure of 3-3,” the notice said. “TransCanada requested additional nondestructive testing on components on GT 3-3 and while no obvious defects were found, there are justified concerns that the GT 3-3 expander turbine poses an unacceptable risk of catastrophic failure given the operating conditions of the unit. At this time GT 3-3 will remain in a forced outage and TC Ravenswood is not in the process of repairing the unit to return to service. TC Ravenswood will have further risk assessments performed to help evaluate GT 3-3 as well as similarly situated units. TC Ravenswood does not anticipate repairing the unit at this time and accordingly intends to mothball the unit. Should circumstances change, TC Ravenswood will notify all the parties to this notice.”
TC Ravenswood asked that the New York commission provide it with information related to whether GT 3-3 is required for reliability no later than Oct. 15 so that the unit may be properly represented in the NYISO markets.
The notice was from: James D’Andrea, Esq., TransCanada Services USA Inc., 110 Turnpike Road, Suite 300, Westborough, MA 01581, Phone (508) 475-6088, fax (508) 898-0433, Email email@example.com.
TransCanada’s website said that the Ravenswood Generating Station, located in Queens, N.Y., is a 2,480-MW, gas-fired plant that consists of multiple units employing steam turbine, combined cycle and combustion turbine technology.