WO2025026576A1

WO2025026576A1 - Improved hybrid train system configuration

Info

Publication number: WO2025026576A1
Application number: PCT/EP2024/025227
Authority: WO
Inventors: Fabio BALDANZINI; Giuliano Milani; Andrea RIGHESCHI; Gaspare MARAGIOGLIO
Original assignee: Nuovo Pignone Tecnologie - S.R.L.
Priority date: 2023-07-28
Filing date: 2024-07-25
Publication date: 2025-02-06

Abstract

A hybrid train system is disclosed. The hybrid train system comprises at least one gas turbine, a compressor, and an electric motor. Between the compressor and the electric motor it is installed an active functional rotating equipment, which improves the power transmission, and also supports the power transmission shaft. The active functional rotating equipment can be removed, providing room for ease the maintenance of the compressor. A method for repairing a hybrid train system is also disclosed.

Description

Improved Hybrid Train System Configuration

Description

TECHNICAL FIELD

[0001] The present disclosure concerns a hybrid train system configuration for allowing an improved maintenance.

BACKGROUND ART

[0002] Gas turbines are often installed for providing torque to a load, such as compressors or the like. Compressors are widely used, for instance, in the field of liquid natural gas and in general in the oil and gas industry. The gas turbine is usually connected to the load, namely the compressor, a pump, or any rotary equipment, through a coupling.

[0003] More specifically, referring to Liquefied Natural Gas (LNG) processing, the gas is liquefied by a liquefaction process, where the natural gas is cooled using refrigeration cycles so that it becomes liquid to be stored and transported. For cooling the LNG, a refrigerant is cooled by a compressor, then it is condensed and expanded, to remove heat from the natural gas, which flows in a heat exchanger. The compressors are rotating machines that are normally driven by gas turbines.

[0004] In the last years, an electric machine is also included in the above layout, achieving the so-called train configurations. More specifically, in such configurations along the shaft line there is a gas turbine, a compressor, connected to the gas turbine, and an electric machine, in its turn connected to the compressor, are usually known and referred to as hybrid train configurations, hybrid train systems, hybrid turbo-compressor trains, or simply hybrid trains, as already mentioned. In such configurations, the electric machine can have multiple operations. In particular, the electric machine can operate as an electric motor, such as a helper, supplying a torque alternatively to the compressor, for example when the gas turbine cannot operate, or directly to the gas turbine, e.g. during a start-up phase.

[0005] The electric machine can also operate as a generator, for instance when excess power is generated by the gas turbine than that normally required by the load, namely the compressor. In this case, the power is transformed by the electric machine in the electric energy and injected into a public power grid, for example.

[0006] The compressor can be usually made of a casing and a compressor bundle, arranged, during normal operations, into the casing. A compressor bundle is a component of a gas compressor and it is the heart of the system since the main parts responsible for the compression process are therein included. The compressor bundle includes several parts, such as typically includes components such as: impellers/rotors, which are the parts that actually compress the gas. In a centrifugal compressor, impellers are attached to the rotating shaft and rotate at high speeds, to impart pressure to the gas; diaphragms or stators that are stationary components, designed to convert the kinetic energy of the gas into pressure energy;

- the shaft, to which the impellers are coupled, allowing them to rotate. The shaft is typically connected to the electric machine motor or to the gas turbine; seals and bearings, which allow the shaft to rotate freely while also preventing gas leakage.

[0007] The compressor bundle is designed to be removable from the rest of the system to facilitate maintenance and repair. In a process plant, the bundle can be pulled out from the rest of the machine without having to disassemble the entire compressor, without impact on process piping.

[0008] In hybrid trains the space available to maintain and repair the compressor bundle is very small. This kind of maintenance activity requires the removal or displacement of electrical machine or gas turbine or complete compressor casing. This implies an excessive downtime and the high handling capacity of the customer crane.

[0009] To face such technical design problems a first solution is that of distancing the compressor from the electric machine. In this case, however, the coupling connecting the compressor and the electric machine should be longer. This design choice can cause several problems in terms of resonances and vibrations. A too-long coupling can cause resonance with the working vibration, for which the machine can even break, causing extensive damage. Recent design trends, provide faster machines, which require shorter coupling, to prevent any resonance risks. Also, longer shafts are heavy, and therefore more complicated to maintain, in view of the weight to be handled before the maintenance activities can start.

[0010] In light of the above considerations, it would be greatly appreciated within the field to have a more effectively designed hybrid train that addresses and overcomes the aforementioned challenges. This improved design would aim to mitigate the issues traditionally associated with the compact and restrictive placement of the compressor bundle.

[0011] It would also be greatly appreciated allow maintenance procedures of the compressor bundle easier and more straightforward. By simplifying the process of accessing, removing, and reinstalling the compressor bundle, routine maintenances could be performed more efficiently and with fewer complications.

[0012] The relevant prior art to the hybrid train system disclosed herein includes also the European patent EP3004601B1, and the Italian patent applications 102022000013801 and 102022000012785, which describe layouts of hybrid train systems as previously disclosed

[0013] The relevant prior art also comprises the patent application EP2917504A1. The solution disclosed improves gas turbine systems used in mechanical drive applications, especially for driving compressors in LNG facilities. It addresses power fluctuation issues by positioning an electric motor/generator at the opposite end of the turbine from the load, enhancing maintenance access and reducing mechanical stress. This motor/generator supplements power during low turbine output and generates electricity from excess power. The system simplifies retrofitting and eliminates the need for a separate starter. It can be applied to both single and multi-shaft turbines. The solution does not address arrangement of part for ease the maintenance of the compressor.

SUMMARY

[0014] In one aspect, the subject matter disclosed herein is directed to a hybrid train system that comprises a compressor, to be driven by a torque, a gas turbine for generating the driving torque to drive the compressor, a main transmission assembly, for the transmission of the torque from the gas turbine to the compressor, an electric machine load, and a further transmission assembly, for the mechanical connection of the load electric machine and the compressor. The further transmission assembly comprises an active functional rotating equipment. Also, the further transmission assembly comprise also a first transmission coupling having an end mechanically connected to the compressor, and the other end mechanically and removably connected to the active functional rotating equipment, and a second transmission coupling having an end mechanically and removably connected to the active functional rotating equipment, and the other end mechanically connected to the electric machine. The active functional rotating equipment is a shaft box.

[0015] In another aspect, the subject matter disclosed herein concerns a hybrid train system where the shaft box comprises a containment casing, in which the transmission gears and/or shafts are contained, a base to support the containment casing, and a first connecting flange, removably coupled to the first transmission shaft of the further transmission assembly, and a second connecting flange, removably coupled to the second transmission coupling of the further transmission assembly.

[0016] In another aspect, disclosed herein is a hybrid train system wherein the active functional rotating equipment comprises a torque limiter device.

[0017] A further aspect of the present disclosure is drawn to a hybrid train system, wherein the torque limiter device is applied to the first connecting flange and/or to the second connecting flange.

[0018] In another aspect, the subject matter disclosed herein concerns a hybrid train system wherein the active functional rotating equipment comprises internal couplings and the torque limiter device is applied to one of the couplings of the active functional rotating equipment.

[0019] A further aspect of the present disclosure is drawn to a hybrid train system, wherein the casing of the compressor has an extraction opening, from which the compressor bundle can be removed, and wherein the hybrid train system further comprises a rail that can be installed in correspondence with the extraction opening of the casing of the compressor, and an extraction carriage slidably movable on the rail.

[0020] In another aspect, the subject matter disclosed herein concerns a hybrid train system, wherein the ratio between the distance between the compressor and the electric machine, and the longitudinal length of the compressor bundle is comprised between 1.2 and 1.8, preferably 1.5.

[0021] In another aspect, disclosed herein is an active functional rotating equipment that comprises one of the following equipment: a ratcheting system; a secondary-transmission shaft; a speed pick-up; a torque pulsation measurement system; one or more a vibration probe; a torque limiter device (TLD); a mechanical pump; a turning devices gear; a dedicated flywheel to damper/tune accordingly the torsional behavior of the train system; and/or a continuous variable transmission device (CVT).

[0022] In another aspect, disclosed herein is a compressor that comprises a casing and a compressor bundle, contained within the casing. The compressor bundle can be extracted from the casing.

[0023] In another aspect, disclosed herein is an electric machine configured to operate as an electric motor, to transmit torque to the compressor, and as a generator, to receive torque from the compressor. Also, the main transmission assembly comprises a clutch box, comprising a containment case, and a clutch, arranged within the containment case, a first transmission shaft, having an end mechanically connected to the gas turbine, and the other end mechanically connected to the clutch box, and a second transmission shaft, having an end mechanically connected to the clutch box.

[0024] Also, disclosed herein is a clutch that comprises a first clutch input section connected to the first transmission shaft, and a second clutch output section, connected to the second transmission shaft.

[0025] In one aspect, the subject matter disclosed herein is directed to a method for repairing a hybrid train system, which comprises the steps of disassembling the transmission couplings, removing the active functional rotating equipment, extracting a compressor bundle. The casing of the compressor has an extraction opening, from which the compressor bundle can be extracted. After the removing step, there is the following additional step: installing a rail in correspondence of the extraction opening of the casing of the compressor and placing the extraction carriage on the rail, and wherein the extracting step comprises the sub-step of using the extraction carriage moving along the rail.

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] A more complete appreciation of the disclosed embodiments of the invention and many of the attendant advantages thereof will be readily obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein:

Fig. 1 illustrates a schematic of a hybrid train system according to a first embodiment;

Fig. 2 illustrates a perspective view of a shaft box according to the first embodiment;

Fig. 3 illustrates a lateral view of the shaft box of Fig. 2;

Fig. 4 illustrates a front view of the shaft box of Fig. 2;

Fig. 5A illustrates the compressor 3 in its standard operating configuration;

Fig. 5B illustrates the disassembly of the first and second transmission couplings;

Fig. 5C illustrates the removal of the shaft box;

Fig. 5D illustrates the extraction of the compressor bundle through a carriage; and

Fig. 6 illustrates a flowchart of a method for repairing a hybrid train system.

DETAILED DESCRIPTION OF EMBODIMENTS

[0027] Gas turbines are used for driving loads, such as compressors and the like, which are connected through a shaft. Recently, so-called hybrid train systems are spreading in the market, which integrate also electric machines. In hybrid train systems, a gas turbine drives a compressor, which is connected on its own to the electric machine through an active functional rotating equipment, such as a shaft box, to improve the operation of the system as well as to provide more space when the compressor bundle is extracted from the casing, e.g. for maintenance or replacement. [0028] A shaft box removably interposed between the compressor and the electric machine is integrated within the turbo-compressor shaft line to allow proper support of the compressor-electric machine connection and concurrently get sufficient space availability for compressor bundle removal. The solution is leverage, as well as the integration of torque limiter devices (TLDs) to avoid shaft line overdesign (easier coupling design) and dedicated instrumentation (easier rotating equipment item design).

[0029] Referring now to the drawings, Fig. 1 shows a hybrid train system 1 according to a first embodiment. The hybrid train system 1, in general and broad terms, comprises a gas turbine 2, a compressor 3, to be driven by the gas turbine 2, and an electric machine 6.

[0030] The gas turbine 2 comprises a gas compressor 21, capable of compressing air taken from the environment, which is delivered to a combustor 22. In the combustor 22 fuel is added to the airflow and a fuel/air mixture is formed and ignited. The combustion gas generated in the combustor is delivered to the high-pressure turbine 23 and partly expands therein, generating mechanical power. The mechanical power generated by the high-pressure turbine 23 is used to drive the gas-generator compressor 21.

[0031] In general, the operation of the gas turbine 2 is controlled by a gas turbine control unit 24, which coordinates the general function of the rotating machine. The gas turbine control unit 24 can be an external computer or a programmed or programmable processor on board of the gas turbine 2.

[0032] The compressor 3 comprises a casing 31 and a compressor bundle 32, contained within the casing 31 when in operations. For repairing or maintaining the compressor 3, the latter has to be extracted from the casing 31, in the extraction direction according to the arrow U.

[0033] In general, the compressor bundle 32 comprises the main parts (not shown in detail in the Figures) responsible for the compression process, such as impellers/rotors, which actually compress the gas, diaphragms or stators, to convert the kinetic energy of the gas into pressure energy, and seals and bearings, which allow the shaft to rotate freely while also preventing gas leakage. All these parts are interconnected and coupled in a complex manner. The compressor bundle 32 is represented in Fig. 1 by a rectangle, without distinguishing its parts, as mentioned above.

[0034] The compressor 3 is connected to the gas turbine 2 by a main transmission assembly 4. The main transmission assembly 4 comprises a first transmission coupling 41, having an end connected to the gas turbine 2, a second transmission coupling 42, having an end connected to the load 3, and a clutch box 5. In the illustrated layout of the hybrid train system 1, the clutch box 5 is connected to the first transmission coupling 41 and to the second transmission coupling 42.

[0035] In the clutch box 5 there are schematically shown the clutch input and output sections 521 and 522, respectively mechanically connected to the other ends of the main transmission coupling 41, and of the second transmission coupling 42. The clutch input and output sections 521 and 522 are capable of engaging power transmission. The clutch sections 521 and 522 are contained in a containment case 51.

[0036] The clutch box 5 may also comprise a torque limiting device or TLD 53, schematically shown in the figure, connected between the first transmission coupling 41 and the clutch input section 521 of the clutch 52. The introduction of the torque limiter device 53 allows for avoiding a shaft line overdesign, which might limit the hybrid train system 1 operating range. In fact, the mass of the torque limiter device 53 stabilizes the main shaft assembly 4. The mass of the torque limiter device 53 replaces the usual masses applied to the shafts for their stabilization.

[0037] In other embodiments, a variety of other types of torque-limiting devices can be used to effectively manage and control the torque levels in the system. For instance, torque clicker types can be installed as an alternative. Torque clickers are unique devices that provide a mechanical means of limiting torque, often through a ratcheting mechanism. They can be used to restrict the rotation of the mechanism to a certain extent, preventing it from spinning endlessly.

[0038] In addition, other types of torque-limiting devices that might be installed include shear pins, magnetic couplers, or electronic torque limiters, among others. Each of these devices has unique operational characteristics, benefits, and drawbacks, and the choice of the device depends on the specific needs and requirements of the hybrid train system 1. [0039] The hybrid train system 1 also comprises an electric machine 6, mechanically connected to the electric motor 3 by a further transmission assembly 7 comprising also a first transmission coupling 71, such as a shaft or the like, an active functional rotating equipment 8, and a second transmission coupling 72, such as a shaft or the like.

[0040] In the prior art, it is not implicit or obvious that an active functional rotating equipment 8 includes the capability to disconnect mechanical connections between the active functional rotating equipment 8 and the first transmission coupling 71 as well as the second transmission coupling 72. Typically, functional rotating equipment in existing systems is designed with fixed connections that do not readily accommodate disconnection without significant disassembly and specialized tools. This traditional approach often results in increased maintenance time and complexity, as well as higher risk of damage during disassembly and reassembly.

[0041] Furthermore, the prior art does not disclose or suggest a modular design where the mechanical connections between the rotating equipment 8 and the transmission couplings 71 and 72 can be easily disengaged. Such a feature enhances the flexibility and serviceability of the equipment, allowing for quick replacement or maintenance without the need for extensive system downtime.

[0042] The active functional rotating equipment 8, which, as mentioned, may be embodied by a shaft box, is designed to house and support the rotating shaft, ensuring its proper alignment and smooth operation. This equipment is essential for maintaining the integrity and efficiency of the rotating system, providing both structural support and ease maintenance, being removable.

[0043] The functional rotating equipment 8 is configured to be slidably removable, allowing for easy access and maintenance. The removal process can be performed transversely with respect to the shaft arrangement, facilitating quick and efficient disassembly when maintenance is required. Furthermore, the design allows for radial removal by defining a specific plane, which may involve lifting the equipment to detach it from the system. This design consideration enhances the compactness and modularity of the overall system, reducing spatial encumbrance and simplifying maintenance tasks. The ability to easily remove and service the shaft box ensures minimal downtime and extends the lifespan of the equipment, thereby improving the overall reliability and performance of the mechanical system.

[0044] To ease the maintenance of the compressor 3, the distance between the compressor 3 and the electric machine 6 can be distanced by a distance A proportional to the compressor bundle 32 longitudinal length, namely equal to:

A = 1.5 x bundle_longitudinal_lenght preferably such ratio is comprised between 1.2 and 1.8.

[0045] The electric machine 6 is designed with multifunctional capabilities, with the ability to operate both as an electric motor and as a generator. When functioning as an electric motor, the electric machine 6 provides torque to the compressor 3, thereby driving its operation. On the other hand, when the electric machine 6 operates as a generator, it transforms the power by converting the energy it receives via the further transmission assembly 7.

[0046] The electric machine 6 is controlled by an electric machine slave control unit 61. The electric machine slave control unit 61 is central to the regulation and control of the electric machine 6 functionalities, ensuring smooth and efficient performance.

[0047] The electric machine slave control unit 61 is operatively connected to a master control logic unit U, forming an integrated system that provides overall control of multiple components of the hybrid train 1. The master control logic unit U, in turn, is also operatively connected to the gas turbine slave control unit 24, bringing the operational control of these components under a unified system.

[0048] The master control logic unit U coordinates the operations of the gas turbine 2 and of the electric machine 6. This coordinated control becomes particularly critical when the electric machine 6 functions as an energy supplier or a generator. By managing the operations of these two components, the master control logic unit U ensures efficient energy use and distribution, thereby optimizing the overall performance of the hybrid train 1.

[0049] The master control logic unit U could be implemented in several ways to achieve the intended operational coordination between the gas turbine 2 and the electric machine 6.

[0050] In one embodiment, the master control logic unit U could be a dedicated microcontroller, designed, along with the gas turbine slave control unit 24 and the electric machine slave control unit 61, specifically for the task of controlling the operation of the gas turbine 2 and the electric machine 6, as mentioned above. This dedicated microcontroller could be programmed with a set of algorithms/programs tailored to the specific requirements of the hybrid train 1 operations, taking into account factors such as energy efficiency, operational safety, and performance optimization.

[0051] In another embodiment, the master control logic unit U could be part of a programmable logic controller (PLC) system. PLCs are often used in industrial settings for process control. With input and output interfaces that can connect directly to the gas turbine slave control unit 24 and the electric machine slave control unit 61, a PLC could be programmed to manage and coordinate the operations of these components based on real-time operational data.

[0052] In a further embodiment, the master control logic unit U could be implemented as a software module running on a general-purpose computer or a dedicated control computer. This software module could interact with the gas turbine slave control unit 24 and the electric machine slave control unit 61 over standard communication interfaces, allowing it to control and coordinate the operations of the gas turbine 2 and the electric machine 6 based on predefined control ways.

[0053] In yet another embodiment, the master control logic unit U could be implemented as a distributed control system (DCS). In this configuration, multiple local controllers distributed throughout the hybrid train 1 could each be responsible for controlling a specific aspect of the operations of the gas turbine 2 and the electric machine 6.

[0054] It should be noted that the above embodiments are merely illustrative, and other implementations of the master control logic unit U could be devised without departing from the scope of the invention. The specific implementation chosen would depend on factors such as the specific requirements of the hybrid train 1 operations, the available resources, and the desired level of control granularity and flexibility.

[0055] In the embodiment shown, the load is a compressor 3, however, in other embodiments, the load can be a different one, such as a pump, and the like.

[0056] The active functional rotating equipment 8 is a shaft box, for ease the torque and power transmission.

[0057] A shaft box 8 is a mechanical assembly designed to support and enclose the further transmission assembly 7 in the hybrid train system 1. It serves several key functions in the hybrid train system 1 operation, including load-bearing, alignment, and protection.

[0058] The shaft box 8 is designed to withstand the mechanical stresses imposed by the further transmission assembly 7 rotation and the forces transmitted through it. It is typically made from high-strength materials such as steel or alloy.

[0059] The shaft box 8 may also include an alignment assembly, such as a set of bearings or bushings (not shown), which allows the drive shaft to rotate freely while maintaining precise alignment. This feature minimizes friction and wear, enhances efficiency, and reduces the likelihood of drive shaft failure.

[0060] The shaft box 8 may also incorporate a sealing system to protect against contaminants and the egress of lubricants used within the shaft box 8 itself. The sealing system may comprise a series of gaskets, O-rings, or mechanical seals, depending on the specific requirements of the application.

[0061] It should be noted that the design and features of the shaft box 8 could vary depending on the specific requirements of the hybrid train system 1. The detailed description provided herein is meant to be illustrative rather than exhaustive, and variations on this design could be conceived by those skilled in the art without departing from the scope of the disclosure.

[0062] Specifically, referring now to Figs. 2 and 3, there are shown an embodiment of the shaft box 8 as an active functional rotating equipment. The shaft box 8 comprises a containment casing 81, in which the transmission gears and the parts above are contained, a base 82, which includes mounting points or brackets that allow it to be securely fastened to the structure of the hybrid train system 1. These mounting points could be also designed to absorb vibrations and reduce noise. The base 82 supports the containment casing 81. The shaft box 8 also comprises a first connecting flange 83, for the coupling with the first transmission coupling 71 of the further transmission assembly 7, and a second connecting flange 84, for the coupling with the second transmission coupling 72 of the further transmission assembly 7.

[0063] In some embodiments, the base 82 comprises a set of adjustable mounts for allowing the position of the containment casing 81 to be adjusted relative to the compressor 3 and the electric machine 6.

[0064] Also in other embodiments, the shaft box 8 further comprises a set of monitoring sensors for monitoring the operational conditions of the active functional rotating equipment 8 contained within the containment casing 81.

[0065] The monitoring sensors are selected from the group consisting of temperature sensors, pressure sensors, vibration sensors, and rotational speed sensors.

[0066] The first 83 and the second 84 connecting flanges are removably coupled respectively to the first 71 and second 72 transmission couplings of the further transmission assembly 7.

[0067] In other embodiments, the active functional rotating equipment 8 can integrate additional devices, to improve the power transmission between the compressor 3 and the electric machine 6. Specifically, the following equipment can be integrated within the shaft box 8: a ratcheting system; an auxiliary transmission shaft; a torque pulsation measurement system; one or more vibration probes; additional instrumentation (e.g. speed pick-up, vibrations probes); a torque limiter device (TLD) that allows avoiding any undue complexity on the train shaft line design; a mechanical pump, through a dedicated mechanical connection to the main shaft. A pump would imply less impact on the new lube oil console that shall be foreseen whenever a hybrid solution implementation shall be accomplished on an existing unit (brownfield solution); a turning devices gear, to prevent rotor thermal bowing and speed up the restart procedure of the train (like turning gear and ratchet system, which are commonly used to maintain the train in a slow spinning condition); a dedicated flywheel to damper/tune accordingly the torsional behavior of the train system 1; and/or a continuous variable transmission device (CVT).

[0068] More specifically, the ratcheting system is a mechanical device that allows rotational or linear movement in only one direction. This system can be associated with a shaft box 8 in a way that allows the shaft to rotate in one direction and prevents backward movement. This ensures efficient power transmission and safeguards the system from potential damages due to reverse rotation.

[0069] The torque limiter device (TLD) is designed to protect the system from excessive torque. A torque limiter device typically comprises a shear pin (not shown) or other mechanical components designed to disconnect the drive from the driven load when the torque exceeds a pre-set limit. This disconnection prevents damage to the mechanical components by avoiding the transmission of excessive forces that could lead to mechanical failure.

[0070] Under normal operating conditions, the torque limiter allows the transfer of torque between connected components, such as flanges or couplings. When the torque exceeds the specified threshold, the shear pin or equivalent component breaks, causing the device to disengage the driving force from the driven component. This action effectively protects the connected equipment by preventing the transfer of potentially damaging torque levels. [0071] In the hybrid train system 1, the torque limiter device safeguards the system’s bundle 32 during operation. The bundle 32, which comprises various connected components such as flanges, couplings, and rotating equipment, is susceptible to damage from torque spikes or excessive forces. The torque limiter device allows protecting these components from damaging forces.

[0072] The torque limiter device can be applied to the first connecting flange 83, to the second connecting flange 84, or to internal couplings of the active functional rotating equipment 8, acting as a protective mechanism.

[0073] The auxiliary transmission shaft is an integral component of a power transmission system. It helps in distributing power from the power source to various components of the system. In the context of the shaft box 8, this auxiliary transmission shaft could be housed within the box 8 and connect various mechanical components, facilitating power transfer between them.

[0074] The torque pulsation measurement system is designed to accurately measure the variations in torque produced by the power source. It can help in identifying any inconsistencies in the performance of the system and aid in preventive maintenance. This measurement system could be located near the shaft box 8 to monitor the torque transmitted through the shafts.

[0075] The vibration probes are sensors used to measure vibrations in mechanical systems. These probes can be strategically placed around the shaft box 8 to monitor and measure any vibrations that could indicate potential issues or irregularities in the operation of the mechanical components within the box 8.

[0076] The mentioned additional instrumentation can include, by way of example, speed pick-up sensors and vibration probes, that can be employed to monitor various aspects of the system's operation. These sensors can be placed in and around the shaft box 8 to measure the speed at which the shafts within the box are rotating, and any vibrations that might indicate operational issues.

[0077] The torque limiter device (TLD) is a protective device that limits torque transmitted in a drive system by slipping when torque demand exceeds a preset value. This device can be part of the shaft box 8 assembly and connected to the transmission shafts. This would prevent any undue complexity on the shaft line design, protecting the system from potential damage due to overloading.

[0078] The mechanical pump could be connected to the first 71 and second 72 transmission couplings via a dedicated mechanical connection within the shaft box 8.

[0079] The turning devices gear can prevent rotor thermal bowing and speed up the re-start procedure of the hybrid train 1. It could be housed within the shaft box 8 and connected to the first 71 and second 72 transmission couplings. This gear, along with the ratchet system, could maintain the hybrid train 1 in a slow spinning condition, reducing thermal bowing and facilitating quick restarts.

[0080] The dedicated flywheel could be housed within the shaft box 8 and connected to the first 71 and second 72 transmission couplings. The flywheel could serve to dampen and/or tune the torsional behavior of the hybrid train system 1, aiding in the stability and efficiency of the system.

[0081] The continuous variable transmission device (CVT) is a type of automatic transmission that can change seamlessly through a continuous range of gear ratios. This device could be integrated within the shaft box 8 and connected to the transmission shafts, providing variable transmission capabilities for the train system and ensuring optimal operational efficiency.

[0082] The functional rotating equipment 8, namely the shaft box, is slidably removable. It is designed to optimize spatial configuration and maintenance accessibility. This functional rotating equipment 8 can be transversally removed relative to the shaft arrangement, providing a convenient method for accessing internal components during maintenance operations.

[0083] The removal process is generalized by defining a plane of removal, allowing for radial detachment. This radial removal may involve lifting the equipment 8, thereby enhancing the system's compactness and modularity. Such a configuration significantly reduces spatial encumbrance and simplifies maintenance procedures, offering a streamlined and efficient approach to equipment handling and servicing.

[0084] The hybrid train system 1 according to the first embodiment described above operates as follows.

[0085] When the gas turbine 2 operates, the torque can be transmitted by the clutch box 5 to the compressor 3. The two clutch sections 521 and 522 of the clutch can be separated, thus not transmitting the torque, to the compressor 3. When the clutch sections 521 and 522 are connected, torque can be transmitted, from the gas turbine 2 to the compressor 3. The first transmission coupling 41 and the second transmission coupling 42 then rotate according, for instance, to the rotation arrow R (see Fig. 1).

[0086] The compressor 3 is connected to the electric machine 6 by the further transmission assembly 7. In this case, the active functional rotating equipment 8 allows the transmission of the torque from the gas turbine 2 or from the electric machine 6.

[0087] The electric machine 6 can operate either as a helper, providing torque to the compressor 3, or as a generator, transforming the exceeding power generated by the gas turbine 2, and not required by the compressor 3, in electric energy, for example, to be injected into a power grid, to which the electric machine 6 can be connected.

[0088] In case of the compressor 3 requires maintenance or has undergone damage, the active functional rotating equipment 8 is removed as a first step. More specifically, the first 71 and the second 72 transmission couplings are decoupled respectively from the first 83 and second 84 connecting flanges.

[0089] Also, the first 71 and the second 72 transmission couplings are removed too, so that the compressor bundle 32 can be removed from the relevant casing 31, sliding along the extraction direction U. Then the operator can easily maintain the compressor 3 and specifically the parts of the compressor bundle 32.

[0090] In Figures 5A, 5B, 5C, and 5D the sequence of the compressor bundle 32 removal is shown. Also Fig. 6 shows the sequences of the maintenance method.

[0091] In the presented disclosure, Fig. 5A illustrates the compressor 3 in its standard operating configuration with the shaft box 8 installed. This is the default configuration of the hybrid system 1 when it is operating normally, with the shaft box 8 providing support and proper alignment between the compressor 3 and the transmission assemblies. [0092] In Fig. 5B, a detailed illustration of step 91 of the method 9 of Fig. 6 is shown,, where the disassembly of the first 71 and second 72 transmission couplings is presented. This disassembly step allows for the subsequent removal of the shaft box 8. Care is taken during this step to ensure the integrity of the transmission couplings 71 and 72 for future reassembly.

[0093] Fig. 5C corresponds to step 92 from the repair method 9 shown in Fig. 6, and it visually represents the process of the shaft box 8 removal. Utilizing appropriate tools and techniques, the shaft box 8 is removed in the direction indicated by arrow El . This removal process allows for the exposure of the compressor bundle 32 and facilitates its subsequent extraction.

[0094] Fig. 5D, corresponding to step 93 from the extraction method 9 shown in Fig. 6, shows the installation of a rail 85 and extraction carriage 86. This step is critical to providing a reliable and safe means to extract the compressor bundle 32. The rail 85 is installed along the desired path of extraction, and the extraction carriage 86 is placed on it, ready to receive and move the compressor bundle 32.

[0095] According to a further aspect of the present disclosure, the casing 31 includes an extraction opening 33. This opening is designed to allow the removal of the compressor bundle 32. It is through this opening that the compressor bundle 32 can be extracted during maintenance or replacement procedures.

[0096] Following the removal of the compressor bundle 32, an additional step is carried out as part of the described method. This includes the installation of a rail system. The rail 86 is installed in correspondence to the extraction opening of the compressor casing 31. This placement facilitates the smooth extraction and replacement of the compressor bundle 32.

[0097] Further, an extraction carriage 86 is placed on the installed rail 85. The carriage 86 is designed to support and transport the compressor bundle 32. The use of the rail 85 and carriage system 86 ensures the safe and efficient handling of the compressor bundle 32, thereby minimizing the risk of damage and facilitating maintenance and replacement processes. This embodiment further contributes to the overall efficiency of the hybrid train system, enhancing its operational lifetime and reliability. [0098] In some embodiment, the extraction of the compressor bundle 32 can be operated by different ways, such as a crane system: This could involve using overhead cranes, jib cranes, or mobile cranes. The compressor bundle 32 could be attached to the crane using slings, chains or other forms of secure attachments. The crane can then lift and move the compressor bundle to the desired location.

[0099] Also, in other embodiments, a roller conveyor system can be installed. This system would include a series of rollers set at regular intervals. The compressor bundle 32 could be placed then onto these rollers and smoothly transported to its new location. The use of a roller conveyor would allow for quick and easy movement of the compressor bundle 32.

[0100] In other embodiments, a forklift can be used to move the compressor bundle 32, or a pneumatic or hydraulic jack system. In this latter case, this system would involve the use of jacks to lift the compressor bundle 32 off its mountings and onto a movable platform or skid. The compressor bundle 32 could then be moved on this platform to its new location.

[0101] In additional embodiments, robotic manipulators can be used to handle the extraction of the compressor bundle 32. Such system would provide high precision and reduced risk of damage. This could be particularly advantageous in environments where the compressor bundle 32 is large, heavy, or situated in a hard-to-reach location.

[0102] The chosen method will depend on several factors such as the size and weight of the compressor bundle, the layout of the facility, cost, and safety considerations.

[0103] Finally, in Fig. 6, which shows the step 94 of the method 9, the extraction of the compressor bundle 32 is accomplished using the extraction carriage 86, extracted along the arrow E2. The carriage 86, moving along the rail 85 on wheels 861, efficiently extracts the compressor bundle 32 from its initial position.

[0104] The compressor bundle is then arranged on the carriage 86, between the casing 31 of the compressor 3 and the electric machine 6, in a broader space A, making easier the maintenance operations. [0105] In summary, the disassembling method 9 of the hybrid train system 1 comprises the steps of disassembling the first and second transmission couplings (71 and 72, as depicted in step 91), removing the shaft box 8 (as shown in step 92), installing the rail 85 and extraction carriage 86 (as demonstrated in step 93), and extracting the compressor bundle 32 using the extraction carriage 86 (as shown in step 94).

[0106] Summarizing the repairing method 9, the following steps are shown: step 91 : disassembling the first and second transmission couplings 71 and 72; step 92: removing the shaft box 8 in the direction indicated by arrow El; step 93: installing a rail 85 and extraction carriage 86; step 94: extracting a compressor bundle 32 using the extraction carriage 86 moving along the rail 85 on wheels 861.

[0107] After the disassembling step 91 and the removing step 92, once the active functional rotating equipment 8 is disconnected and removed, a following step includes the safe storage of this removed equipment in a pre-determined location. This storage location is selected to ensure the protection of the equipment, maintaining its integrity for potential future re-installation.

[0108] The installation of the rail 86 is aligned and secured in such a way as to guarantee the smooth and precise movement of the compressor bundle 32. This ensures that the compressor bundle 32 can be safely and efficiently moved without causing damage or undue stress to any of the components.

[0109] In the method 9, the removal of the compressor bundle 32 requires particular attention to avoid any potential damage or misplacement. This operation includes the steps of firstly disengaging the compressor bundle 32 from any remaining connections to other systems. Careful and precise disconnection is necessary to maintain the integrity of both the compressor bundle 32 and the systems to which it is connected.

[0110] Following the disconnection, the movement of the compressor bundle 32 is controlled along the rail 85 to prevent any damage. This movement is closely moni- tored and controlled to avoid any sudden shifts or accidental collisions. To ensure precise positioning and smooth transportation, the system may utilize optical position sensors (not shown in the figures). These sensors provide real-time feedback regarding the position and movement of the compressor bundle 32, allowing for adjustments as needed to maintain a safe and controlled removal process.

[OHl] An advantage of the solution disclosed is that there is available space for the compressor 3, allowing easy maintenance.

[0112] Another advantage of the present disclosure is the possibility to integrate a torque limiter device (TLD) to avoid shaft line overdesign, as well as dedicated instrumentation, to ease rotating equipment item design.

[0113] While aspects of the invention have been described in terms of various specific embodiments, it will be apparent to those of ordinary skill in the art that many modifications, changes, and omissions are possible without departing from the spirit and scope of the claims. In addition, unless specified otherwise herein, the order or sequence of any process or method steps may be varied or re-sequenced according to alternative embodiments.

[0114] Reference has been made in detail to embodiments of the disclosure, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the disclosure, not limitation of the disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the scope or spirit of the disclosure. Reference throughout the specification to "one embodiment" or "an embodiment" or “some embodiments” means that the 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 phrase "in one embodiment" or "in an embodiment" or "in some embodiments" in various places throughout the specification is not necessarily referring to the same embodiment(s). Further, the particular features, structures, or characteristics may be combined in any suitable manner in one p or more embodiments.

[0115] When elements of various embodiments are introduced, the articles “a”, “an”, “the”, and “said” are intended to mean that there are one or more of the elements. The terms “comprising”, “including”, and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements.

Claims

1. A hybrid train system (1), comprising: a compressor (3), to be driven by a torque; a gas turbine (2) for generating the driving torque to drive the compressor (3); a main transmission assembly (4), for the transmission of the torque from the gas turbine (2) to the compressor (3); an electric machine (6); and a further transmission assembly (7), for the mechanical connection of the electric machine (6) and the compressor (3); characterized in that the further transmission assembly (7) comprises an active functional rotating equipment (8), which is removable, a first transmission coupling (71) having an end mechanically connected to the compressor (3), and the other end mechanically and removably connected to the active functional rotating equipment (8), and a second transmission coupling (72) having an end mechanically and removably connected to the active functional rotating equipment (8), and the other end mechanically connected to the electric machine (6).

2. The hybrid train system (1) of the preceding claim, wherein the active functional rotating equipment is a shaft box (8).

3. The hybrid train system (1) of the preceding claim, wherein the active functional rotating equipment (8) is movable on a plane, parallel to the ground, on which the hybrid train system is arranged, or it is radially movable, such that the active functional rotating equipment (8) can be lifted.

4. The hybrid train system (1) of any one of claims 2 or 3, wherein the shaft box (8) comprises: a containment casing (81), in which the active functional rotating equipment (8) is contained, a base (82) to support the containment casing (81), and a first connecting flange (83), removably coupled to the first transmission coupling (71) of the further transmission assembly (7), and a second connecting flange (84), removably coupled to the second transmission coupling (72) of the further transmission assembly (7).

5. The hybrid train system (1) of claim 4, wherein the shaft box (8) further comprises a set of monitoring sensors for monitoring the operational conditions of the active functional rotating equipment (8) contained within the containment casing (81).

6. The hybrid train system (1) of claim 5, wherein the monitoring sensors are selected from the group consisting of temperature sensors, pressure sensors, vibration sensors, and rotational speed sensors.

7. The hybrid train system (1) of any one of the preceding claims, wherein the active functional rotating equipment (8) comprises a torque limiter device (TLD).

8. The hybrid train system (1) of the preceding claim, when depending on claim 4, wherein the torque limiter device is applied to the first connecting flange (83), and/or to the second connecting flange (84).

9. The hybrid train system (1) of any one of claims 7 or 8, wherein the active functional rotating equipment (8) comprises internal couplings and the torque limiter device is applied to the one of the couplings of the active functional rotating equipment (8).

10. The hybrid train system (1) of any one of the preceding claims, wherein the active functional rotating equipment (8) comprises one or more of the following equipment: a ratcheting system; an auxiliary transmission shaft; a speed pick-up; a torque pulsation measurement system; one or more vibration probes; a mechanical pump; a turning devices gear; a dedicated flywheel to damper/tune accordingly any torsional behavior of the train system (1); and/or a continuous variable transmission device (CVT).

11. The hybrid train system (1) of any one of the preceding claims, wherein the compressor (3) comprises a casing (31) and a compressor bundle (32), contained within the casing (31), wherein the compressor bundle (32) can be extracted from the casing (31).

12. The hybrid train system (1) of the preceding claim, wherein the distance (/I) between the compressor (3) and the electric machine (6) is proportional to the compressor bundle (32) longitudinal length.

13. The hybrid train system (1) of any one of the preceding claims, wherein electric machine (6) is configured to operate as an electric motor, to transmit torque to the compressor (3), and as a generator, to receive torque from the compressor (3).

14. The hybrid train system (1) of any one of the preceding claims, wherein the main transmission assembly (4) comprises: a clutch box (5), comprising a containment case (51), and a clutch (52), arranged within the containment case (51); a first transmission coupling (41), having an end mechanically connected to the gas turbine (2), and the other end mechanically connected to the clutch box (5); and a second transmission coupling (42), having an end mechanically connected to the clutch box (5).

15. The hybrid train system (1) of the preceding claim, wherein the clutch (52) comprises a first clutch input section (521) connected to the first transmission coupling (41), and a second clutch output section (522), connected to the second transmission coupling (42).

16. The hybrid train system (1) of any one of the preceding claims, wherein the casing (31) of the compressor (3) has an extraction opening (33), from which the compressor bundle (32), and wherein the hybrid train system (1) further comprises a rail (85) that can be installed in correspondence with the extraction opening (33) of the casing (31) of the compressor (3), and an extraction carriage (86) slidably movable on the rail (85).

17. The hybrid train system (1) of any one of the preceding claims, wherein the ratio between the distance (A) between the compressor (3) and the electric machine (6), and the longitudinal length of the compressor bundle (32) is comprised between 1.2 and 1.8, preferably 1.5.

18. A method (9) for repairing a hybrid train system (1), wherein the hybrid train system (1) comprises a compressor (3), to be driven by a torque, wherein the compressor (3) comprises a casing (31) and a compressor bundle (32), contained within the casing (31), wherein the compressor bundle (32) can be extracted from the casing (31), a gas turbine (2) for generating the driving torque to drive the compressor (3), a main transmission assembly (4), for the transmission of the torque from the gas turbine (2) to the compressor (3), an electric machine (6), a further transmission assembly (7), for the mechanical connection of the electric machine (6) and the compressor (3), wherein the further transmission assembly (7) comprises an active functional rotating equipment (8), a first transmission coupling (71) having an end mechanically connected to the compressor (3), and the other end mechanically and removably connected to the active functional rotating equipment (8), and second transmission coupling (72) having an end mechanically and removably connected to the active functional rotating equipment (8), and the other end mechanically connected to the electric machine (6), wherein the active functional rotating equipment is a shaft box (8), which comprises: a containment casing (81), in which the active functional rotating equipment (8) is contained, a base (82) to support the containment casing (81), and a first connecting flange (83), removably coupled to the first transmission coupling (71) of the further transmission assembly (7), and a second connecting flange (84), removably coupled to the second transmission coupling (72) of the further transmission assembly (7); and wherein the method (9) comprises the following steps: disassembling (91) the first (71) and second (72) transmission couplings; removing (92) the active functional rotating equipment (8); extracting (94) a compressor bundle (32).

19. The method (9) of the preceding claim, wherein the casing (31) of the compressor (3) has an extraction opening (33), from which the compressor bundle (32) can be extracted, wherein after the removing (92) step there is the following additional step: installing (93) a rail (85) in correspondence with the extraction opening (33) of the casing (31) of the compressor (3) and placing the extraction carriage (86) on the rail (85), and wherein the extracting (94) step comprises the sub-step of using the extraction carriage (86) moving along the rail (85).

20. The method (9) of any one of claims 18 or 19, wherein the removing (92) of the active functional rotating equipment (8) includes disconnecting mechanical connections between the active functional rotating equipment (8) and the first transmission coupling (71) and the second transmission coupling (72).

21. The method (9) of the preceding claim, further including the step of storing the removed active functional rotating equipment (8) in a predetermined location for later re-installation.

22. The method (9) of any one of claims 18-21, wherein the rail (86) is aligned and secured to ensure the smooth and precise movement of the compressor bundle (32).

23. The method (9) of any one of claims 18-22, wherein the removing (94) of the compressor bundle (32) includes the steps of: disengaging the compressor bundle (32) from any remaining connections to other systems; and controlling the movement of the compressor bundle (32) along the rail (85) to prevent any damage by means of optical position sensors.