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250 Gas Turbine Handbook: Principles and Practices
Today, with the maturing of the petro-chemical industry, the quest
for profit has been moving away from the oil and gas fields and into
every comer of the refinery processes.
Driven by a complex environment of regulation and profit motivation,
more and more refineries are discovering savings in forgotten
or overlooked areas within their processing plants. In a sense, the
quest is centering on how to use the by-product waste to increase
refinery profitability. The preferred solution is clearly in-plant cogeneration
systems. The refinery cogen plants are providing savings to
the industry while satisfying growing environmental concerns.
Refinery requirements for electric power and heat are being met
with cogeneration systems consisting of one or more gas turbine-generators,
Heat Recovery Steam Generators (HRSGs) which utilize the
gas turbine waste heat. The generated steam is being used either for
additional power generation and/or process heat for refinery application.
However, in the volatile climate in which the refineries operate,
the industry must tailor its products to market demand; thus the
gas turbine units must contend with varying types of fuel supply
(from liquid to gaseous, or both simultaneously) and quality (calorific
value, viscosity), as well as the changing electrical and process
heat demands throughout its process cycle. Often, this frequent and
large fuel fluctuation presents a major obstacle for better efficiency
and lower operating cost of the cogen system. However, these changing
parameters do not represent a problem for the GT35 and GT10
gas turbines. The GT35 and GT10 units can utilize multiple fuels
of changing quality and calorific value, including the waste gases
derived from the refining process, for the gas turbine combustion
process. ABB has a sizable fleet of industrial gas turbines installed
throughout the world for refinery application. List of ABB’s petrochem
applications are exhibited in Figure 15-1.
This paper discusses the benefits of two gas turbine installations
in Greek refineries utilizing the GT10 and GT35 units. These two
medium size gas turbines are ideally suited for industrial cogeneration,
because they are compact, heavy-duty industrial machines with
proven reliability and efficiency track-records for operations in harsh
environments.
These two industrial units have since been up-graded in both
performance and emission control. The GT10B is presently ISO rated
at 24.6 MW with a simple cycle Heat Rate of 9,970 Btu/kWh (LHV).