Page 484 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Gas Turbines 461

Some axials have wheel spaces which are wider than the width of a blade
and facilitate the individual replacement of blades. Other models require
that the rotor disks be completely disassembled to get at a single blade.
The maintenance savings in the first instance are obvious.

Fuel System and Combustion

Gaseous or liquid fuels can be burned in gas turbines. Since fuels vary
widely in calorific value, hydrocarbon composition, contaminants pres-
ent and viscosity, each fuel must be considered separately in terms of engine
performance, reliability, operation, and maintenance.6
The use of natural gas fuel for industrial gas turbines is wide-spread.
Natural gas is generally considered to be the optimum fuel when supplied
to the unit in clean, dry and sweet form. Machines fired on good quality
natural gas will invariably exhibit superior operation compared to similar

Figure 9-9. Axial compressor rotor in balance stand (courtesy Canadian Westinghouse).