Longitudinal section of GTN-12 gas turbine

Two-shaft unit consists of compressor, combustion chamber, high-pressure turbine and low-pressure turbine and starting device. Compressor, combustion chamber and turbines are located on common frame, which is also oil tank of plant. On the frame is all the equipment of the oil system; oil vapors from the tank are sucked by special fans. The rated power of the unit is 12000 kW at atmospheric air temperature 288 K and temperature upstream of the turbine 1353 K, the degree of increase of the pressure ¼ k = 6.3. Compressor - axial. Compressor inlet pipe - cast, cast iron. Pressure losses in it are 0.5% of the total pressure. In order to facilitate start-up conditions, two anti-surge valves are installed on the middle part of the compressor housing, which discharge part of the air during start-up and shutdown, and two discharge valves, which discharge part of the air after the compressor at sharp drop in load and increase in RPM of the low-pressure turbine. Compressor has 12 stages. Compressor housing is cast from grey cast iron of high strength. It consists of 3 parts with two vertical flanges. The inlet branch pipe has a somewhat elongated shape along the axis, which makes it possible to smoothly supply air from the inlet section to the section in front of the guide vane. The good aerodynamic shape of the inlet nozzle allows 50% improvement in uniformity of pressure fields and speeds at the inlet to the guide vane. Rotor of drum type compressor. A shank fixed with fingers is installed on the side of air inlet in the inner bore of the shaft. On the other side of the shaft there is a clouded disk of the turbine.

Guide vanes of compressor and power turbines are installed in holder. Guide blades of compressor turbine are connected along inner diameter with welded-cast diaphragm. The bearing part of the guide vanes holder does not have a horizontal connector and rigid connections with the turbine housing, which reduces the influence of the casing deformations on the holder, therefore, on the gaps along the flow part.

In the lower half of the inlet branch pipe of the turbine in the area of the flat walls of the housing, air-cooled ties are installed.

The high-pressure turbine is two-stage, as is the low-pressure turbine. High-pressure turbine rotor is connected by flange to compressor rotor, and low-pressure turbine rotor is connected to intermediate shaft.

The high and low pressure turbine housing is a common, axisymmetric, double-walled structure. Housing inner part is formed by holders. Between LPT and HPT there is a thin-walled intermediate part. The installation uses air cooling of parts and assemblies operating at high temperatures: HPT rotor, race, outer housing. LPT rotor is cooled only from outer ends of disks by air coming out of seals.

Support bearings of sliding are used in the unit. Bearings are protected by casings and insulation.