RU235428U1 - Micro gas turbine rotor - Google Patents

Abstract

The utility model relates to the technical field of power engineering, namely, to the design of the rotor system of a micro gas turbine unit. The technical result consists in increasing the reliability of the rotor unit of the micro gas turbine unit. The said technical result is achieved by the fact that in the rotor of the micro gas turbine unit, which includes a rotor of an electric generator, mounted on two radial bearings, and a rotor of a gas turbine engine, mounted on two radial and one thrust bearing, coupled to each other, wherein the rotor shaft is made of two elements connected to each other by a torsion bar, according to the utility model, the thrust bearing is located in front of the compressor inlet device, and the radial bearing of the rotor of the gas turbine engine is installed between the compressor wheel and mounted on the bushing, wherein gas-dynamic bearings with backing petals are used as the thrust and radial bearings. In this case, the torsion bar is provided with cup-shaped thin-walled tails.

Description

The utility model relates to the technical field of power engineering, namely, to the design of the rotor system of a micro gas turbine unit.

A design of a composite high-speed rotor shaft of a gas turbine plant is known, including a shaft of a gas turbine engine supported by one radial bearing, and a generator shaft supported by two radial bearings, the thrust bearing is located on the shaft of the gas turbine engine between the compressor wheel and the turbine. The thread on one tail of the shaft of the gas turbine engine allows for the assembly of the rotor by tightening the located parts. The other tail has a cup-shaped form with a flexible disk (wall) and cylindrical faces, through which the connection of the rotors is carried out by means of tension between the tail of the generator shaft and these faces (patent US5697848).

The disadvantage of this rotor shaft design is the increased requirements for the accuracy of the assembly of the composite rotor. Assembly with inaccurate manufacturing of the end surfaces of the tightened parts on the rotor shaft of a gas turbine engine will lead to the occurrence of a bend. Also, the turbine disk located on the shaft is made with a hole, which can limit its service life due to the increase in stress near the hole. The thrust bearing is located close to the zone of elevated temperatures.

A rotor unit is known, where the shaft is mounted in the housing of an electric generator in radial bearing supports to form a console on which the compressor wheel and the turbine wheel are placed, and the thrust bearing support can be mounted in the stator of a gas turbine, covers the console of the rotor shaft and is placed between the said wheels (patent RU195196, published 01/17/2020).

The disadvantage of this model is the formation of a console in the rotor circuit, which significantly reduces its reliability and is a factor in the occurrence of conical mode oscillations. Another disadvantage is the contact of the thrust bearing with the rear wall of the turbine wheel, where elevated temperatures are reached, which leads to a significant reduction in its service life. This design of the rotor unit assumes the presence of a large-diameter hole in the compressor wheel design, which is unacceptable for a long-term high-speed machine due to the occurrence of high stress values in this zone, which lead to a significant reduction in the service life.

A known rotor unit of a turbogenerator is represented by a cantilever rotor of a turbogenerator and a rotor of an electric generator located through a thrust disk, connected to each other in such a way that they form a single module. The support units of the rotor are the first radial bearing unit located in the area of the turbogenerator shaft closer to the area of the thrust disk, the second radial bearing unit located in the area of the electric generator shaft at the end of the rotor opposite to the cantilever module of the turbogenerator or close to it, and a thrust bearing unit, part of which is the said thrust disk (patent RU185175, published on 23.11.2018).

However, the presence of a console in the rotor scheme on two radial bearings leads to instability of motion associated with the occurrence of oscillations in conical modes. This model assumes the introduction of bearings of different designs into the design: gas-static with self-aligning segments and hybrid gas, which leads to the formation of a rotor scheme on supports with different rigidities. The above increases the requirement for mass distribution on the rotor, dimensional deviations, and introduces complexity into the analysis of motion stability during design.

The closest analogue of the proposed micro gas turbine unit is the design of the turbogenerator rotor (patent RU185197, published on 26.11.2018), which contains an electric generator and a gas generator combined with each other. The rotor of the gas generator and electric generator is made of two parts connected by a spring. One of the shaft parts is mounted in the stator of the electric generator by means of radial bearings, made hollow. The second part of the shaft is mounted in the gas generator by means of one thrust bearing and two radial bearings.

However, the removal of all gas generator bearings from the "hot zone" significantly increases the length of the rotor of the entire turbogenerator, reducing the stability of its movement, and leads to the formation of a console that overloads the nearest radial bearing. The length of the spring connecting the shafts is excessive, which also creates an additional factor provoking instability of the rotor movement. This design assumes increased requirements for the distribution of the masses of the parts installed on the rotor shaft due to the presence of a console in the rotor circuit. The rotor supports are segmental gas bearings, which, in addition to the gas-dynamic operating mode, have a gas-static operating mode and require a pressure accumulator. Segmental gas bearings serve as a source of additional instability and also reduce the cost-effectiveness of operation.

The technical problem solved by the utility model is to increase the reliability of the rotor unit.

The technical result is an increase in the reliability of the operation of the rotor unit of the micro gas turbine unit.

The specified technical result is achieved by the fact that in the rotor of the micro gas turbine unit, including the rotor of the electric generator, mounted on two radial bearings, and the rotor of the gas turbine engine, mounted on two radial and one thrust bearing, coupled to each other, wherein the rotor shaft is made of two elements connected to each other by a torsion bar, according to the utility model, the thrust bearing is placed in front of the compressor inlet device, and the radial bearing of the rotor of the gas turbine engine is installed between the compressor wheel and mounted on the bushing, wherein gas-dynamic bearings with backing petals are used as the thrust and radial bearings. In this case, the torsion bar is equipped with cup-shaped thin-walled tails.

The cup-shaped shape of the torsion bar tails ensures ease of assembly by means of a tight fit on the gas turbine engine shaft on one side and on the electric generator shaft on the other, and the torsion bar itself is a flexible element that allows for compensation of misalignment by bearings, runout, misalignment and reduces the mutual influence of the above-mentioned rotor shafts during rotation, which leads to stability in the operating mode. In this connection, the presence of a torsion bar with the specified tails allows for increased reliability of the rotor and the micro gas turbine unit as a whole, and also simplifies assembly.

One of the shaft parts is mounted in the stator of the electric generator by means of radial gas-dynamic petal bearings. The other part of the shaft is mounted in the stator of the gas-turbine engine by means of two radial gas-dynamic petal bearings and one thrust petal gas-dynamic bearing, removed from the "hot zone" due to its placement in front of the inlet apparatus of the gas-turbine engine. This arrangement of bearing units allows achieving an optimal ratio between the load on the bearing due to a decrease in the cantilever mass, and also providing a better temperature regime in comparison with the closest analogue, which ensures an increase in the reliability of the rotor and the micro gas-turbine unit as a whole.

The use of gas-dynamic bearings with backing petals ensures reliability during long-term operation in constant modes.

Installing a radial bearing on a bushing allows for optimal temperature conditions for the radial bearing located near the "hot zone" between the compressor wheel and the turbine. Ensuring optimal temperature conditions helps to increase the reliability of the rotor.

The claimed technical solution is illustrated by a drawing, where Fig. 1 shows an axial section of a generator gas turbine unit, and Fig. 2 shows an axial section of a torsion bar.

The gas turbine generator unit consists of an electric generator 1 and a gas turbine engine 2 (Fig. 1).

Electric generator 1 can be implemented as a serially produced generator consisting of a rotor 3 on highly ercive permanent magnets, a winding 4, a fan 5, having generator and motor operating modes, which ensures the start of the above-mentioned gas turbine generator unit.

Gas turbine engine 2 includes:

- gas generator docking housing 6, which functions as the compressor inlet apparatus;

- input guide apparatus 7;

- a rotor of a gas turbine engine 8, consisting of a turbine rotor 9, a compressor wheel 10, a support sleeve 11, a thrust sleeve 12, a nut 13;

- blade diffuser 14;

- nozzle device 15;

- combustion chamber 16;

- bearing housing 17;

- insert 18.

The rotor of the electric generator 3 and the rotor of the gas turbine engine 8 with radial bearings 19 and thrust bearing 20 form a rotor unit of the gas turbine generator unit, the shaft of which is composite, connected during assembly by a torsion bar 21, installed with cup-shaped ends 22 on the tails of the shafts of the rotor of the electric generator 3 and the rotor of the gas turbine engine 8 by means of tension.

The shaft of the rotor unit of the gas turbine generator unit is installed in radial gas-dynamic petal bearings 19, located in the stator of the electric generator (not designated by position), the housing of the joint 6, the housing of the bearing 17, and the thrust gas-dynamic petal bearing 20, mounted in the stator of the gas turbine engine (not designated by position) between the housing of the joint 6 and the insert 18.

Tightening of nut 13 creates a tight fit of the joints of the tightened parts, which increases the rigidity of the rotor of the gas turbine engine 8 and eliminates its vibrations in bending modes.

The thin-walled design of the cup-shaped tails 22 (Fig. 2) of the torsion bar 21 makes it possible to simplify the process of assembling the rotor shaft of the gas-turbine generator unit and to ensure the independence of movement of the rigid, relative to the torsion bar, rotors of the electric generator and gas-turbine engine due to increased compliance, which leads to a reduction in the load on the radial and thrust bearings.

When assembling the rotor unit, the rotor blocks of the gas turbine engine and the electric generator are assembled separately, after which parts 8 and shaft 3 are connected by a torsion bar 21, and the stator of the electric generator 1 is attached to the joint housing of the gas generator 6 .

Air is blown through petal radial gas-dynamic bearings 19 installed in the stator of the electric generator by means of fan 5. Air flow through radial gas-dynamic bearing 19 and thrust gas-dynamic bearing 20 installed in the stator of the gas-turbine engine after torsion bar 21 is carried out due to pressure differences between the environment and the inlet to compressor 10. Air flow through radial gas-dynamic bearing 19 installed in the stator of the gas-turbine engine after compressor wheel 10 is carried out due to pressure difference between the outlet from the compressor and the inlet to the turbine wheel.

The turbo generator works as follows.

Power is supplied to the electric generator 1, its rotor 3 is set in rotation simultaneously with the rotor of the gas turbine engine, as a result of which air is supplied to the compressor wheel through the docking housing 6 (which functions as the compressor inlet device), which increases the pressure and supplies it to the combustion chamber 16, where continuous combustion of the air mixture is organized, the ignition of which can be performed by spark plugs. Upon reaching the required rotation speed, the electric generator 1 switches to the generator mode using the control unit, the rotation of the composite rotor is carried out due to the turbine wheel of the gas turbine engine 2.

The advantages of the claimed device are the following:

- the thrust petal gas-dynamic bearing 20 is removed from the hot zone, which increases the reliability of its operation;

- the use of electric generator 1 as a starter allows to reduce the process of hanging the rotor of the gas turbine generator unit on bearings 19, 20;

- the location of the radial petal gas-dynamic bearing 19 between the turbine wheel and the compressor wheel on the support sleeve 11 makes it possible to achieve an optimal ratio between the load on the bearing (reducing the cantilever mass) and the temperature regime;

- the use of petal gas-dynamic bearings 19, 20 as supports for the rotor of a gas-turbine generator unit allows achieving low weight and size characteristics of the structure, increasing efficiency and ensuring reliability during long-term operation in constant modes;

- the introduction of a torsion bar 21 with flexible elements 22 into the design allows achieving stable operation of the gas turbine generator unit in constant and transient modes, ensuring compensation for bearing misalignment, radial runout, and assembly errors.

Claims (1)

A rotor of a micro gas turbine generator unit, including a rotor of an electric generator, mounted on two radial bearings, and a rotor of a gas turbine engine, mounted on two radial and one thrust bearing, coupled to each other, wherein the rotor shaft of the micro gas turbine generator unit is made as a composite of two elements, namely the rotor shaft of the electric generator and the rotor shaft of the gas turbine engine, connected to each other by a torsion bar, characterized in that the thrust bearing is located in front of the inlet device of the compressor of the gas turbine engine, and the radial bearing of the rotor of the gas turbine engine is installed between the compressor wheel and the turbine wheel and is mounted on the bushing, wherein gas-dynamic bearings with backing petals are used as the thrust and radial bearings, wherein the torsion bar is provided with cup-shaped thin-walled tails.