Gas Turbine Handbook : Principles and Practices

172 Gas Turbine Handbook: Principles and Practices
HARDWARE
The difference between a microturbine and the larger, heavy
industrial and aero-derivative, gas turbines is size. While microturbine
components are smaller than the multi-megawatt gas turbines,
they perform identical functions. That is they follow the laws of
thermodynamics and are represented by the Brayton Cycle. In most
cases microturbine components are made of the same materials used
in larger gas turbines (see Figure 11-1). The primary areas of new
development are the combustor and the recuperator.
Figure 11-1. Courtesy of Capstone Turbine Corporation. The C30 &
C60 microturbine systems are ultra-low-emission combined heat and
power generator sets providing up to 30 kW and 60 kW of power, 85
kW and 150 kW of heat, at heat rates of 13,100 Btu/kW-Hr and 12,200
Btu/kW-Hr, respectively.
Compressor
Microturbine compressor components are almost exclusively
centrifugal designs. This design type has several advantages: burst
speeds are well above even the highest operating speeds, materials
are readily available, this component can be precision cast with minimal
machining, and some components (derived from small turboprop
engines, turbochargers, APUs, etc.) are already available.