Gas Turbine Inlet Bleed Heating
What did our services find?
In January, GE Digital's Asset Performance Management detected both erratic readings and high differentials on the Inlet Bleed Heat (IBH) valve demand and position feedbacks. The IBH valve demand and position feedback trended between 2% and 6% higher than model estimates and increased to as high as 7% higher than model estimates. GE Digital's Industrial Managed Services team sent a notification to the customer and began tracking this issue on the regularly scheduled weekly calls.
What was the underlying cause?
Due to the age and duty cycle of the IBH Valve, the site had known issues with Inlet Bleed Heat valve actuators and positioner feedbacks on multiple gas turbines. This particular gas turbine’s IBH system hardware was overhauled during an outage in fall of 2013. This new hardware was found to be having calibration issues, which caused the high differentials between the valve demand and position feedback.
What was the value to the customer?
IBH differentials over 10% can cause the IBH system to trip, which will increase the inlet compressor temperature to over 100°F (38°C). The increase in compressor inlet temperatures will result in a loss of maximum load capability on the gas turbine. If the site is operating in combined-cycle mode, this will result in a loss of maximum load capability on the steam turbine as well. Even though the site overhauled the IBH valve hardware, the new hardware unexpectedly underperformed. The site was able to schedule calibration of the valve on non-peak hours and, thus, prevent the loss of load on both the gas and steam turbines.
What was the underlying cause?
Due to the age and duty cycle of the IBH Valve, the site had known issues with Inlet Bleed Heat valve actuators and positioner feedbacks on multiple gas turbines. This particular gas turbine’s IBH system hardware was overhauled during an outage in fall of 2013. This new hardware was found to be having calibration issues, which caused the high differentials between the valve demand and position feedback.
What was the value to the customer?
IBH differentials over 10% can cause the IBH system to trip, which will increase the inlet compressor temperature to over 100°F (38°C). The increase in compressor inlet temperatures will result in a loss of maximum load capability on the gas turbine. If the site is operating in combined-cycle mode, this will result in a loss of maximum load capability on the steam turbine as well. Even though the site overhauled the IBH valve hardware, the new hardware unexpectedly underperformed. The site was able to schedule calibration of the valve on non-peak hours and, thus, prevent the loss of load on both the gas and steam turbines.