Gas Turbine Handbook : Principles and Practices

264 Gas Turbine Handbook: Principles and Practices
The facility, originally supplied with two mixed bed demineralizer
trains, has contracted with Ionics Ultrapure Water to furnish a
200 gpm reverse osmosis unit with mixed bed resin bottles for polishing
to supply the demineralized water needs. This system eliminates
the requirement for on-site sodium hydroxide and greatly reduces
sulfuric acid usage. It also eliminates demineralizer maintenance,
resins and operations.
The plant control system is a Bailey Network 90 Distributed
Control System (DCS). This system was provided to monitor and
control the operation of the HRSG, steam turbine generator, auxiliary
boilers, and balance of the plant equipment. It also monitors the
operation of the gas turbine generator. The DCS provides graphic
displays, trend indications, and alarm information.
The plant was outfitted with the best available control technology
(BACT) for emissions reduction as recognized by the State
of California. NO x
emissions are controlled by the Quiet Combustion
System with steam injection, and the HRSG is equipped with
a carbon monoxide catalytic reduction system for the control of CO
emissions.
The plant maintains a continuous emissions monitoring system
(CEM) to monitor the output criteria pollutants. This unit continuously
samples stack gases and relays the results to a dedicated control
room computer for calculating emissions in the format requested
by the local air district.
OVERVIEW OF OPERATING PLAN
According to the terms of the Power Purchase Agreement, the
utility provides an annual nonbinding estimate of hours to be operated
during curtailable periods. This estimate is used to budget and
acquire the fuel supplies for the coming year, coordinate annual maintenance
activities, and budget operating costs.
The plant operates within the following two separate and distinct
scheduling periods:
Scheduling Period 1—January 1 through April 30—The plant is dispatchable
and operates per “Specific Operating Orders” from the
utility. In 1994, for example, the plant was scheduled to operate