SITHE STERLING MAINTAIN OVER 99% AVAILABILITY
Sithe Sterling Energy’s turbine hall in upstate New York houses a GE Frame 6B gas turbine genset in addition to a Zurn HRSG, extraction steam turbine genset and other plant auxiliaries.
In order to meet the demands of the nearby Oneida manufacturing plant, Sithe targeted an availability rate of 95.9% and reliability factor of 97.0%. In actuality, the figures were as follows – well in excess of the target rates.
|Actual Availability Rate||Actual Reliability Factor|
One of the keys to the Sithe Sterling plant’s high operating performance is the extensive use of preventative maintenance. For example, the gas turbine compressor is routinely washed to retain turbine performance levels. On-line water washes are performed every day the gas turbine is in operation. On alternate days, ZOK 27 detergent is used for the first three minutes of the wash, followed by seventeen minutes of rinse water. On the other days, only rinse water is used for twenty minutes. Off-line washes are performed approximately quarterly.
Sithe Energy’s operators are confident that water washing keeps the gas turbine performing at maximum output and efficiency. This was borne out by a period when no off-line water washes were performed on the gas turbine. During this time the plant ran its single gas turbine for 201 consecutive days without any outages. During this period, gas turbine output performance deteriorated by approximately 5.6% and the heat rate deteriorated by some 2.4%. After performing the first off-line wash with ZOK 27, performance was restored back to the original levels.
During an average quarter between off-line water washes, output performance now drops only 0.4% and heat rate increases by about 0.3%. The site engineers put these improvements in performance down to refinements in water washing techniques at the plant, and the regular use of ZOK 27.