Online Lotus Thrust Adjustment System

Abstract

An online Lotus thrust adjustment system is disclosed. The online Lotus thrust adjustment system includes at least one axial thrust balance flow net (16) between a compressor (12) and an expander (11) of a gas turbine. The axial thrust balance flow net (16) supplies high-pressure gas from the compressor (12) to an axial thrust balance piston cavity, and an open-loop flow regulator (17) is arranged along the axial thrust balance flow net (16).

Description

Technical Field

[0001] The present disclosure relates to a system for balancing the loads on the thrust bearings of a gas turbine engine rotor. Embodiments disclosed herein specifically relate to adjusting the thrust of the rotor in real time using a manually operated control valve from outside the engine package.

Background Art

[0002] The rotating components of a turbine unit always generate an axial thrust under the action of the pressure difference between the intake and exhaust ports.

[0003] For example, in an "oil & gas" application, the axial thrust exerted on the bearings of a gas turbine can typically be in the range of 10,000 N to 100,000 N.

[0004] Providing thrust bearings that can withstand such high axial thrusts is very difficult and expensive.

[0005] To solve this problem, high-pressure gas from the compressor is used and supplied into the piston cavity to balance at least part of the axial thrust.

[0006] A process has been developed for testing the balance system and associated control unit during manufacturing to ensure that complex algorithms are properly calibrated. However, a similar process or system is not available for complex algorithms that need to be recalibrated in the field when the engine undergoes changes from its original operating profile and configuration, such as those caused by component degradation, wear, or replacement. This typically also occurs during initial installation or when there are changes to the operating configuration (e.g., water injection). Each of these factors directly affects the engine components, which in turn affect the load on the rotor thrust bearing and, correspondingly, the amount of pressure required in the balance piston cavity to counteract such load. Currently, the regulation of this air flow rate is managed by an online fixed orifice mounted on a properly designed machine. Each time recalibration is required, the fixed orifice is replaced by physically disassembling the line, causing downtime of the machine.

[0007] Therefore, it is highly desirable to develop a system in which the axial thrust balance control unit is calibrated while the engine is operating in the field. Additionally, it is also desirable if this calibration process can be performed during normal engine operation without requiring a shutdown.

[0008] Most importantly, to enhance the overall reliability of the system, it is desirable for such a rotor thrust adjustment system to operate via an open-loop control system. SUMMARY OF THE INVENTION

[0009] In one aspect, the subject matter disclosed herein is directed to an on-line rotor thrust adjustment system comprising at least one axial thrust balance flow net disposed between a compressor and an expander of a gas turbine, the axial thrust balance flow net supplying high-pressure gas from the compressor to the expander to at least partially balance the axial thrust, and an open-loop flow regulator being disposed along the axial thrust balance flow net and adjusting the size of a passage through the axial thrust balance flow net.

[0010] In another aspect, the subject matter disclosed herein relates to an on-line rotor thrust adjustment system, a manual valve being disposed along the axial thrust balance flow net, the manual valve comprising a stem and a wheel, a portion of the wheel and the stem being disposed outside the gas turbine enclosure, and the wheel being removably coupled to the stem. In particular, according to this aspect of the subject matter disclosed herein, at least a portion of the axial thrust balance flow net is composed of a flexible hose.

[0011] In another aspect, an on-line rotor thrust adjustment system is disclosed herein, an open-loop flow regulator being disposed along the axial thrust balance flow net, the rotor thrust adjustment system comprising instrumentation for reading the thrust balance pressure, safety instrumentation, and a graphic control panel page for identifying the balance pressure, valve position, and equivalent reference orifice size.

[0012] The rotor thrust adjustment system according to the present disclosure is intended to replace a prior art rotor thrust adjustment system with a new circuit based on the use of a manual valve instead of the currently used orifice, and to adjust the correct flow rate and pressure of a balanced line. The weight and dimensions of the components of the rotor thrust adjustment system according to the present disclosure are such that an operator can assemble them on-site without lifting the equipment.

Brief Description of the Drawings

[0013] Many of the disclosed embodiments of the present invention, and the attendant advantages thereof, will be better understood and more fully appreciated when considered in connection with the accompanying drawings, by reference to the following detailed description of the invention.

Figure 1

Figure 2

[0014] Next, one embodiment of the present disclosure will be described in detail, and examples thereof are shown in the drawings. Such examples are not intended to limit the present disclosure, but are provided as an explanation of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made to the present disclosure without departing from the scope or spirit of the present disclosure. References throughout this specification to "one embodiment" or "an embodiment" or "some embodiments" mean that a particular feature, structure, or characteristic described in connection with one embodiment is included in at least one embodiment of the disclosed subject matter. Thus, the appearances of the phrases "in one embodiment" or "in an embodiment" or "in some embodiments" in various places throughout this specification are not necessarily all referring to the same embodiment. Also, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0015] When presenting elements of various embodiments, the articles "a", "an", "the", and "said" are intended to mean that there are one or more of those elements. The terms "comprising", "including", and "having" are intended to be non-exclusive and mean that additional elements other than the listed elements may exist.

[0016] Referring now to the drawings, FIG. 1 shows a schematic view of an exemplary gas turbine. The gas turbine engine consists of an expander 11 and a compressor 12, and the expander 11 is mechanically connected to the compressor 12 by a shaft 20. The expander 11 is further connected to the compressor 12 via line 14 to supply the gas from the compressor 12 to the expander 11. The combustor 13 is arranged along line 14 and is configured to effect the combustion of the gas received from the compressor 12, and as a result, increase its volume. Next, the combustion gas is supplied to the expander 11, and the potential energy of the combustion gas is converted into kinetic energy. The gas turbine is housed within an enclosure 15 to isolate it from the outside. In particular, cooling air is supplied to the space between the gas turbine and the enclosure 15 to control the temperature of the gas turbine and keep the temperature of the enclosure 15 within a safe level.

[0017] FIG. 1 also shows a rotor thrust adjustment system according to an embodiment of the present disclosure. In particular, the rotor thrust adjustment system is arranged between the compressor 12 and the expander 11 and includes an axial thrust balance flow net 16 that connects, in particular, the secondary flow system of the compressor to the secondary flow system of the turbine. A portion of the high-pressure gas from the compressor 12 is taken out from the compressor 12 and supplied to the turbine 11, in particular, to the axial thrust balance piston cavity, and the pressure of the gas is used to counteract the rotor thrust.

[0018] A flow regulator 17 arranged along the axial thrust balance flow net 16 is also shown. In particular, the flow regulator 17 is an open-loop flow regulator 17 and consists of a manual valve 17 including a stem 18 and a wheel 19, and a portion 18' of the wheel 19 and the stem 18 is arranged outside the gas turbine enclosure 15. Manual operation by the hand wheel 19 does not rule out the possibility of electric operation.

[0019] At least a portion of the axial thrust balance flow network 16 is composed of flexible hoses, which absorb the thermal expansion and vibration of the engine, prevent mechanical stress from being transmitted to the enclosure 15, support the manual valve 17, and prevent static and dynamic stresses from being transmitted to the mechanical flange. The valve needs to have a wheel 19 arranged outside the enclosure 15 for manual operation from the outside. However, considering the high temperature and noise generated during the operation of the gas turbine, the valve body remains inside the enclosure, similar to all the piping of the axial thrust balance flow network 16. Flexible metal hoses can be conveniently used, minimizing their diameters so as not to be obstructive, and thus using a solution with an internal liner to enable operation at high speeds. The material and hose structure are designed to suit any specific gas turbine operating pressure and temperature.

[0020] The valve wheel 19 is removable and located outside the enclosure wall to avoid overheating that could be harmful to the operator.

[0021] In some embodiments, a ball valve is used because it is one of the most reliable valves in terms of position retention and resilience to failure.

[0022] The operating position of the valve 17, which must mimic the function of the prior art orifice, is ensured by using calculations and charts that correlate the valve opening with the sizes of different orifices.

[0023] Referring next to Figure 2, the online rotor thrust adjustment system according to the present disclosure can also be applied to a turbine engine. The same reference numerals are already shown in Figure 1 and represent the same or corresponding parts, elements, or components as those described above and will not be described again here. The output turbine 21 is additionally shown downstream of the compressor 12 and the expander 11 (which may be referred to as the "high-pressure turbine" or "high-pressure expander") and provides kinetic energy to the load 22.

[0024] Although aspects of the present invention have been described with respect to various specific embodiments, it will be apparent to those skilled in the art that many modifications, variations, and omissions are possible without departing from the spirit and scope of the claims. In addition, unless otherwise specified herein, the order or arrangement of any process or method steps may be changed or rearranged according to alternative embodiments.

Claims

1. An on-line rotor thrust adjustment system for balancing the load on the rotor thrust of an operating gas turbine in response to a deviation from the designed operating profile and configuration of the gas turbine, said gas turbine comprising an expander (11) arranged downstream of a compressor (12), a combustor (13) being configured to receive gas from said compressor (12) via a line (14), effect gas combustion and provide combustion gas to said expander (11), said gas turbine (10) being housed within an enclosure (15), said rotor thrust adjustment system comprising an axial thrust balance flow net (16) between said compressor (12) and said expander (11) for supplying high pressure gas from said compressor (12) to an axial thrust balance piston cavity, characterized in that said rotor thrust adjustment system has an open loop flow regulator (17) arranged along said axial thrust balance flow net (16).

2. The on-line rotor thrust adjustment system according to claim 1, wherein said open loop flow regulator (17) is a manual valve (17) comprising a stem (18) and a wheel (19), a part (18’) of said wheel (19) and said stem (18) being arranged outside said gas turbine enclosure (15).

3. The on-line rotor thrust adjustment system according to claim 2, wherein said wheel (19) is removably coupled to said stem (18).

4. The on-line rotor thrust adjustment system according to claim 1, wherein at least part of said axial thrust balance flow net (16) is composed of a flexible hose.

5. The on-line rotor thrust adjustment system according to claim 1, wherein said open loop flow regulator (17) is a ball valve.

6. The on-line rotor thrust adjustment system according to claim 1, wherein said open loop flow regulator (17) is adjusted by a table that replicates equivalent reference orifice sizes.

Images