EP2710227A1

EP2710227A1 - A gas turbine system and corresponding method for assembling this system

Info

Publication number: EP2710227A1
Application number: EP12721544.0A
Authority: EP
Inventors: Alessandro Polacco; Sandro MONTELATICI
Original assignee: Nuovo Pignone SpA
Current assignee: Nuovo Pignone SpA
Priority date: 2011-05-19
Filing date: 2012-05-18
Publication date: 2014-03-26
Also published as: JP2014515447A; CA2835341A1; WO2012156520A1; ITCO20110017A1; US20140093357A1

Abstract

Method and gas turbine system (100) having a reduced footprint. The gas turbine system (100) includes a gas turbine (102) configured to produce energy and having a gas turbine shaft (106); an auxiliary equipment (104) attached to the gas turbine (102); an overhung shaft (108) of the auxiliary equipment (104) being configured to be attached to the gas turbine shaft (106); a flexible joint (110) configured to be provided between the shaft of the auxiliary equipment and the gas turbine shaft; and a bearing system (120a, 120b) having at least two bearing units provided at a first end of the shaft of the auxiliary equipment next to the flexible joint. A second end of the shaft of the auxiliary equipment is free of bearings.

Description

A GAS TURBINE SYSTEM AND CORRESPONDING METHOD FOR ASSEMBLING THIS

SYSTEM

BACKGROUND

TECHNICAL FIELD

Embodiments of the subject matter disclosed herein generally relate to methods and 5 systems and, more particularly, to mechanisms and techniques for integrating an auxiliary equipment within a gas turbine.

DISCUSSION OF THE BACKGROUND

Gas turbines are used many industries, from military to power generation. They are used mainly to produce electrical energy. However, some gas turbines are used to propel various vehicles, airplanes, ships, or for other reasons. For example, in the oil and gas market the gas turbines are used to drive compressors and pumps. As shown in Figure 1, a gas turbine 10 has a compressor 12 that compresses air received at an inlet 14. The compressed air is provided at an output 16 and directed to a combustion chamber 18. The combustion chamber 18 is configured to also receive fuel (e.g., gas) at an input 20. After mixing the air with the fuel and igniting the mixture in the combustion chamber, the hot gases are provided to an input 22 of an expander (turbine) 24. The expanded gas is output at outlet 26. During the expansion process, a shaft 28 of the expander 24 is rotated, thus, generating mechanical energy. This mechanical energy may be used to rotate another machine (not shown), for example, a power generator for producing electricity.

Various auxiliary equipments are provided with the gas turbine, e.g., , oil pump for the bearings, compressors, a mechanical accessory (e.g., a gear box) or an electrical equipment (e.g., an electrical starter, a generator or an helper motor, etc). All these components need to be supplied with power for performing their functions. There are many possibilities for supplying the auxiliary equipment with power. Two common arrangements are discussed next. As shown in Figure 2A, an integrated gas turbine 50 has a shaft 52 that is supported by bearings 54 at an end 52a. The bearings 54 are provided in the casing 56. The auxiliary equipment 57, which is attached to the gas turbine 50, has its own shaft 58 that is directly coupled to and supported by the shaft 52 of the gas turbine 50. However, such a direct coupling could determine rotordynamic problems of the shaft 52 as the rotation of the shaft 52 is affected by the shaft 58 overhung.

An alternative arrangement is illustrated in Figure 2B. A shaft 72 of the gas turbine 70 is connected via a flexible joint 74 to a shaft 76 of the auxiliary equipment 78. Bearings 80 support an end of the shaft 72 while bearings 82 support both ends of the shaft 76 of the auxiliary equipment 78. The casing 84 of the gas turbine 70 and the casing 86 of the auxiliary equipment 78 are also shown relative to the shafts. While the joint 74 may reduce some of the rotordynamic problems of the arrangements shown in Figure 2A, the equipment 78, due the existence of the bearings 82 and flexible joint 74, needs to be supported by its own support 92. The support 92 may be connected to the bedplate 90 (part that supports the gas turbine), which could increase the footprint of the entire train, or also be connected to the casing 84. It is noted that many details of the arrangements shown in Figures 2A-B are omitted as those are known by those skilled in the art.

Accordingly, it would be desirable to provide systems and methods that avoid the afore-described problems and drawbacks. SUMMARY

According to one exemplary embodiment, there is a gas turbine system having a reduced footprint. The gas turbine system includes a gas turbine configured to produce energy and having a gas turbine shaft; an auxiliary equipment attached to the gas turbine; an overhung shaft of the auxiliary equipment being configured to be attached to the gas turbine shaft; a flexible joint configured to be provided between the shaft of the auxiliary equipment and the gas turbine shaft; and a bearing system having at least two bearing units provided at a first end of the shaft of the auxiliary equipment next to the flexible joint. The second end of the shaft of the auxiliary equipment is free of bearings According to another exemplary embodiments, there is a gas turbine system having a reduced footprint. The gas turbine system includes a gas turbine configured to produce energy and having a gas turbine shaft; an auxiliary equipment attached to the gas turbine; an overhung shaft of the auxiliary equipment being configured to be attached to the gas turbine shaft; and a bearing system having at least two bearing units provided at a first end of the shaft of the auxiliary equipment and supported by the gas turbine's stator. The second end of the shaft of the auxiliary equipment is free of bearings.

According to still another exemplary embodiment, there is a gas turbine system having a reduced footprint and including a gas turbine shaft shared by a compressor and an expander; an auxiliary equipment having an overhung shaft attached to the gas turbine shaft; a bearing system having at least two bearing units provided at a first end of the shaft of the auxiliary equipment next to the gas turbine shaft. A second end of the shaft of the auxiliary equipment is free of bearings. According to yet another exemplary embodiment, there is a method for assembling a gas turbine and an auxiliary equipment to form a gas turbine system. The method includes a step of directly connecting to a flexible joint a gas turbine shaft of the gas turbine and a shaft of the auxiliary equipment; and supporting the shaft of the auxiliary equipment with a bearing system only at a first end. A second end of the shaft of the auxiliary equipment is free of bearings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate one or more embodiments and, together with the description, explain these embodiments. In the drawings: Figure 1 is a schematic diagram of a conventional gas turbine;

Figures 2A-B are schematic diagrams of various arrangements for connecting a shaft of a gas turbine to a shaft of an auxiliary equipment; Figure 3 is a schematic diagram of a gas turbine coupled to an auxiliary equipment according to an exemplary embodiment;

Figure 4 is a schematic diagram of an overhung shaft of an auxiliary equipment coupled to a shaft of a gas turbine according to an exemplary embodiment; Figure 5 is a schematic diagram of another overhung shaft of an auxiliary equipment coupled to a shaft of a gas turbine according to an exemplary embodiment;

Figure 6 is a schematic diagram of still another overhung shaft of an auxiliary equipment coupled to a shaft of a gas turbine according to an exemplary embodiment; and Figure 7 is a flowchart illustrating a method for assembling a gas turbine with an auxiliary equipment according to an exemplary embodiment.

DETAILED DESCRIPTION

The following description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. The following embodiments are discussed, for simplicity, with regard to the terminology and structure of a gas turbine having an auxiliary equipment. However, the embodiments to be discussed next are not limited to these systems, but may be applied to other systems that require a reduced footprint and less impact on the gas turbine shaft rotordynamic .

Reference throughout the specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments. According to an exemplary embodiment illustrated in Figure 3, a gas turbine system 100 includes a gas turbine 102 and auxiliary equipment 104. A shaft 106 of the gas turbine 102 is connected to a shaft 108 of the auxiliary equipment 104 via a flexible joint 1 10. A casing 1 12 of the gas turbine 102 includes at least a bearing unit 1 14 for supporting an end 106a of the shaft 106 and a casing 1 18 includes at least two bearing units 120a and 120b for supporting the shaft 108 of the auxiliary equipment. The casing 118 may be the casing of the auxiliary equipment 104 or may be part of the casing 112 as will be discussed later. It is noted that according to this embodiment, the shaft 108 of the auxiliary equipment 104 has bearing units only at one end 108a and not to the other end 108b, i.e., an overhung shaft. These novel features are now discussed in more details.

According to an exemplary embodiment illustrated in Figure 4, a gas turbine system 150 includes a gas turbine part 152 and an auxiliary equipment part 154. For simplicity, not all components of the auxiliary equipment part are shown in the figures. Those skilled in the art would know what are the omitted components of such auxiliary equipment. A casing 156 of the gas turbine part 152 may partially enclose parts of the auxiliary equipment 154. A shaft 158 of the gas turbine part 152 is supported at an end 158a by a bearing unit 160. The bearing unit may be any known bearing in the field, e.g., journal bearing, fluid bearing, magnetic bearing, etc. Another bearing unit (not shown) is mounted toward the other end of the shaft 158. More bearings may be installed depending on the application.

A shaft 162 of the auxiliary equipment is provided partially inside the casing 156 of the gas turbine and partially inside a casing 163 of the auxiliary equipment 154. The shaft 162 is configured in such way that only a first end 162a is supported by a bearing system 168. The other end 162b of the shaft 162 has no support, thus the shaft 162 is an overhung shaft. The bearing system 168 includes at least two bearing units 164 and 1 6 for supporting the shaft 162. These bearing units may be any type of bearings known in the art. The bearing system 168 is provided inside the casing 156 in this embodiment. In one application, the double bearing unit 164 and 166 is a single piece bearing or two individual items spaced axially by a desired distance.

In order to minimize rotordynamic effects on the shaft 158 of the gas turbine 152, a flexible joint 170 is provided between shaft 158 and shaft 162. In one application, the flexible joint 170 is directly coupled to the shaft 158 and the shaft 162. The flexible joint 170 has one or more of the following features. The flexible joint 170 allows the shaft 158 (or the shaft 162) to move along axis X without displacing the shaft 162 (or the shaft 158). Additionally or optionally, the flexible joint 170 allows one shaft to slip relative to the other shaft while in rotation, up to a certain threshold. One or more of these features allow the shaft 162 of the auxiliary equipment to not affect the rotordynamic of the shaft 158 of the gas turbine 152. No gear box is provided between the two shafts and no support is provided for the casing 163 of the auxiliary equipment.

According to another exemplary embodiment illustrated in Figure 5, a connection 174 between the casing 156 of the gas turbine 152 and the casing 163 of the auxiliary equipment 154 is provided such that the bearing system 168 is provided inside the casing 163.

According to still another exemplary embodiment, which is illustrated in Figure 6, a gas turbine system 200 includes a gas turbine 202 and an auxiliary equipment 204. The double bearing system 210 is provided in a dedicated interface unit 212. The interface unit 212 is provided between a casing 214 of the gas turbine 202 and a casing 216 of the auxiliary equipment 204. In this way, existing gas turbine systems may be retrofitted to have the overhung shaft 220 connected to the shaft 222 of the gas turbine 202 via the flexible joint 224. According to this exemplary embodiment, the flexible joint is provided inside the casing 214 of the gas turbine 202. Figure 6 also shows one end of the shaft 222 being supported by a bearing unit 226 while the bearing system 210 is shown including only two bearing units 206 and 208. More bearing units may be provided in the bearing system 210. One or more advantages of the above noted embodiments are related to a reduction in the footprint of the gas turbine system, as no supporting system is necessary for the auxiliary equipment. It is also noted that the rotordynamic of the shaft of the gas turbine is not affected by the presence of the auxiliary equipment. Proposed embodiments have also the possibility to adopt auxiliary equipments with only one shaft end supported. The flexible joint (e.g., quill shaft) provide the two shafts with a better coupling. The auxiliary equipment may be provided on either side of the gas turbine, e.g., inlet casing on cold side or outlet casing on hot side.

A method for assembling a gas turbine system as discussed above is now discussed with regard to Figure 7. The method for assembling a gas turbine and an auxiliary equipment to form a gas turbine system includes a step 700 of directly connecting to a flexible joint a gas turbine shaft of the gas turbine and a shaft of the auxiliary equipment; and a step 702 of supporting the shaft of the auxiliary equipment with a bearing system only at a first end, wherein a second end of the shaft of the auxiliary equipment is free of bearings.

The disclosed exemplary embodiments provide a system and a method for producing a gas turbine with a reduced footprint and rotordynamic not affected by an auxiliary equipment. It should be understood that this description is not intended to limit the invention. On the contrary, the exemplary embodiments are intended to cover alternatives, modifications and equivalents, which are included in the spirit and scope of the invention as defined by the appended claims. Further, in the detailed description of the exemplary embodiments, numerous specific details are set forth in order to provide a comprehensive understanding of the claimed invention. However, one skilled in the art would understand that various embodiments may be practiced without such specific details.

Although the features and elements of the present exemplary embodiments are described in the embodiments in particular combinations, each feature or element can be used alone without the other features and elements of the embodiments or in various combinations with or without other features and elements disclosed herein. This written description uses examples of the subject matter disclosed to enable any person skilled in the art to practice the same, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims.

Claims

CLAIMS:

1. A gas turbine system (100) having a reduced footprint, the gas turbine system comprising: a gas turbine (102) configured to produce energy and having a gas turbine shaft (106); an auxiliary equipment (104) attached to the gas turbine (102); an overhung shaft (108) of the auxiliary equipment (104) being configured to be attached to the gas turbine shaft (106); a flexible joint (1 10) configured to be provided between the shaft (108) of the auxiliary equipment and the gas turbine shaft (106); and a bearing system (120a, 120b) having at least two bearing units (120a, 120b) provided at a first end (108a) of the shaft (108) of the auxiliary equipment (104) next to the flexible joint (1 10), wherein a second end (108b) of the shaft (108) of the auxiliary equipment (104) is free of bearings.

2. The gas turbine system of Claim 1, wherein there are no other bearings units in the auxiliary equipment.

3. The gas turbine system of Claim or Claim 2, wherein the at least two bearing units are separated by a predetermined distance.

4. The gas turbine system of any preceding Claim, further comprising: a gas turbine casing (156) configured to connect to an auxiliary equipment casing (163), wherein the bearing unit (168) is provided in the gas turbine casing (156).

5. The gas turbine system of any preceding Claim, wherein the flexible joint (1 10) is provided in its entirety inside the gas turbine casing (1 12).

6. The gas turbine system of any preceding Claim, further comprising: a gas turbine casing (156) configured to connect to an auxiliary equipment casing (163), wherein the bearing unit (168) is provided in the auxiliary equipment casing (163).

7. The gas turbine system of any preceding Claim, further comprising: an interface unit (212) provided between a gas turbine casing (214) and an auxiliary equipment casing (216), wherein the bearing unit (210) is provided within the interface unit (212).

8. The gas turbine system of any preceding Claim, wherein the shaft of the auxiliary equipment is configured to pass through the interface unit to enter inside a casing of the gas turbine.

9. The gas turbine system of any preceding Claim, wherein the flexible joint is configured to allow the shaft of the gas turbine to rotate and/or translate relative to the shaft of the auxiliary equipment.

10. The gas turbine of any preceding Claim, wherein the gas turbine includes a compressor and an expander sharing the shaft of the gas turbine and the auxiliary equipment is one of a pump, a mechanical accessory or an electrical equipment.

1 1. A gas turbine (100) system having a reduced footprint, the gas turbine system comprising: a gas turbine (102) configured to produce energy and having a gas turbine shaft (106); an auxiliary equipment (104) attached to the gas turbine (102); an overhung shaft (108) of the auxiliary equipment (104) being configured to be attached to the gas turbine shaft (106); and a bearing system (120a, 120b) having at least two bearing units (120a, 120b provided at a first end (108a) of the shaft (108) of the auxiliary equipment (104) next to the gas turbine shaft (106), wherein a second end of the shaft of the auxiliary equipment is free of bearings.

12. The gas turbine system of Claim 1 1, wherein there are no other bearings units in the auxiliary equipment.

13. The gas turbine system of Claim 11 or Claim 12, further comprising: a flexible joint provided between the gas turbine shaft and the shaft of the auxiliary equipment so that no gear box is provided between these shafts.

14. The gas turbine system of Claims 11 to 13, further comprising: an interface unit provided between a gas turbine casing and an auxiliary equipment casing, wherein the bearing unit is provided within the interface unit.

15. The gas turbine system of Claims 1 1 to 14, further comprising: a gas turbine casing configured to connect to an auxiliary equipment casing, wherein the auxiliary equipment casing has no external support.

16. A gas turbine system (100) having a reduced footprint, the gas turbine system comprising: a gas turbine shaft (106) shared by a compressor (12) and an expander (29); an auxiliary equipment (104) having an overhung shaft (108) attached to the gas turbine shaft (106); a bearing system (120a, 120b) having at least two bearing units provided at a first end (108a) of the shaft (108) of the auxiliary equipment (104) next to the gas turbine shaft (106), wherein a second end of the shaft of the auxiliary equipment is free of bearings.

17. The gas turbine system of Claim 16, wherein there are no other bearings units in the auxiliary equipment.

18. The gas turbine system of Claim 16 or Claim 17, further comprising: a flexible joint directly connecting to the gas turbine shaft and the shaft of the auxiliary equipment; a casing for the compressor and expander; and a casing for the auxiliary equipment configured to be connected to the casing for the compressor and expander.

19. A method for assembling a gas turbine (102) and an auxiliary equipment (104) to form a gas turbine system (100), the method comprising: directly connecting to a flexible joint (1 10) a gas turbine shaft (106) of the gas turbine (102) and a shaft (108) of the auxiliary equipment (104); and supporting the shaft (108) of the auxiliary equipment (104) with a bearing system (120a, 120b) only at a first end (108a), wherein a second end (108b) of the shaft (108) of the auxiliary equipment (104) is free of bearings.

20. The method of Claim 19, further comprising: providing at least two bearing units for the bearing system.