Gas Turbine Handbook : Principles and Practices

Case Study #1 245
with the DCS.
The natural gas/doped propane fuel system is standard apart
from a customer signal which indicates which fuel is in use. Logic
within the control system makes the necessary specific gravity adjustment
for fuel flow measurement.
A new, patented syngas control system is being provided for the
Sierra Pacific IGCC application. It provides an integrated control
system for the syngas boost compressor and the gas turbine that will
minimize fuel supply delivery pressure losses. The boost compressor
raises the compressor extraction pressure prior to the gasifier. After
the gasifier, fuel is metered to the gas turbine through the stop ratio
and gas control valves. Pressure drops through these valves are minimized
by controlling them to the full open position during normal control
operation. By this method the system operates at the minimum
pressure drop and controls the gasifier flow via the boost compressor,
thereby controlling the gas turbine output. When the fuel flow is not
meeting demand, a signal is sent to the gasification island control
panel, which translates this input to the necessary response from the
Figure 14-7. View of MS6001FA Combustor Case Extraction Manifold.