Gas Turbine Handbook : Principles and Practices

176 Gas Turbine Handbook: Principles and Practices
Figure 11-5. Courtesy of Ingersoll-Rand Energy Systems. The
recuperator is integral with the combustor (not shown) thereby
eliminating transition parts. The combustor fits into the large circular
chamber on the right side of the photograph and is mounted directly
above the compressor-turbine components.
Combustor
There is no significant difference between microturbine combustors
and multi-megawatt gas turbine combustors. Combustors for
microturbines, like combustors for larger gas turbines, are either
annular or single combustor designs. They are fabricated from martensitic
and ferritic iron base alloys or nickel base alloy (see Table
3-4). The single combustor, which lends itself to the reverse flow
design concept, has become the design of choice.
Under development are catalytic combustors. The catalytic combustor
promises to achieve emissions below 3 ppm (on natural gas)
without the need for exhaust gas treatment.
Controller
Controllers used on microturbines are generally the same as the
controllers used on the multi-megawatt gas turbines. In electric generation
applications there are some added control tasks. The advent
of microturbines and their high-speed generators has necessitated the
marriage within the controller of power output conditioning with gas