Low-emission compression stations without dedicated generating islands

Abstract

A low emission compression station is disclosed. The low emission compression station includes one or more compressors, each compressor coupled to an electric machine, the electric machines coupled to at least one mechanically driven gas turbine and / or at least one fuel cell, the electric machines and / or the mechanically driven gas turbine and / or the fuel cell sized to meet both the process demands and the electrical load and controlled by a monitoring system (EMS / PMS). When an electric machine is coupled to a mechanically driven gas turbine, a hybrid gas turbine can be used.

Description

[Technical field]

[0001] The present disclosure relates to improvements in compressor stations, typically used in pipelines, that can improve efficiency by reducing carbon emissions. In particular, but not exclusively, the present disclosure relates to compressor stations with one or more compressors coupled with electric machines powered by fuel cells or mechanically driven by gas turbine systems, configured and sized such that extremely high reliability can be achieved without the need for an additional power generating island dedicated to the compressor station. [Background technology]

[0002] It is well known that natural gas is extracted from deep underground rock formations and needs to be transported to end users. Where possible or economically feasible, pipeline transportation is typically used to transport the gas. To offset pressure losses during transportation, pipelines require compression stations arranged along the pipeline at regular intervals. The compressors at these compression stations must operate very reliably with low maintenance requirements. As a result, compression station compressors in pipeline applications, as well as other rotating equipment in oil and gas industry applications, are often driven by gas turbines.

[0003] In addition, because pipelines may extend over long distances and compressor stations may be located in remote locations, in the absence of a distribution grid or if a distribution grid is available but unreliable, the compressor station typically includes a dedicated power generating island for powering the auxiliary systems, allowing the compressor station to operate off the distribution grid or when the distribution grid is not operational. In particular, the power generating island includes gas turbine and / or reciprocating engine generator drives that are operated exclusively to power the auxiliary systems of the compressor station.

[0004] The power capacity of a gas turbine depends on the ambient conditions, i.e., air temperature, as well as certain other factors. The power capacity of a gas turbine is inversely proportional to the ambient temperature. To prevent loss of power generation (in case of tripping of the gas turbine), which may cause the compressor station to shut down, the power generation island is generally designed with full redundancy, i.e., the power generation island includes at least two gas turbine trains, a first gas turbine train and a second gas turbine train, each train sized to be able to independently provide the power required by the auxiliary systems of the compressor station. In case the operability of the first gas turbine train is impaired, the first gas turbine train can be easily supplemented or even replaced by the second gas turbine train. Typically, such a result is achieved by operating both gas turbine trains to run at 50% load to easily relay full rotational reserve capacity when needed.

[0005] This configuration with two fully redundant gas turbine trains has the disadvantage of accelerated turbine wear, since the gas turbine trains running at 50% load are operating under non-optimal conditions. In addition, under normal operation, the efficiency of the two fully redundant gas turbine trains is also low, and the highest efficiency is always achieved when the endothermic machine is operating at 100% load.

[0006] Furthermore, for safety reasons, the power generating island for the compressor station must generally be realized far enough away from the compressor station, which entails additional costs with respect to the associated infrastructure with the same size turbomachine, with the added costs for the high voltage electrical network and the associated substations.

[0007] There are so-called hybrid mechanical-drive gas turbines on the market, where an electric machine connected to the power grid is combined with the gas turbine to drive a load, such as one or more compressors or pumps. The electric machine can operate either as a motor, absorbing power from the power grid to drive (or contribute to driving) the load, or as a generator, providing excess power to the power grid.

[0008] In particular, the electric machine can be used to supplement the mechanical power to the load, to keep the overall mechanical power on the load shaft constant when the turbine's power availability is reduced, and / or to increase the total mechanical power used to drive the load. This function of the electric machine is called helper mode. In helper mode, both the gas turbine and the electric machine supply the load. In this case, the electric machine acts as a motor, absorbing energy from the power grid, and in addition, the gas turbine also supplies energy to the load. The power received by the load is therefore the sum of the power generated by the gas turbine and the power generated by the electric machine.

[0009] When excess mechanical power is available from the turbine, for example if the ambient temperature drops below the design temperature and increases accordingly or the mechanical load required by the compressor is reduced, the excess mechanical power generated by the gas turbine is converted to electrical power using the electric machine as a generator. In generator mode, the gas turbine supplies energy to the load and the electric machine supplies excess energy to the power grid. In such an operating mode, the power generated by the gas turbine is actually split between delivery to the load and introduction of energy to the power grid.

[0010] The electric machine can also be used to provide all the required mechanical power to the load when the turbine is not running. This function of the electric machine is called maximum electric mode. In maximum electric mode, the gas turbine can be disconnected or even shut down and therefore may not function at all, while the electric machine drives the load and therefore absorbs energy from the power grid, so that the electric machine operates as a motor. In this configuration, a clutch can be used to convert the train system into a zero-emission operating mode.

[0011] Finally, in the fourth operating mode, called maximum power generation mode, the speed is kept at the lowest operating speed so that the load, such as the compressor or pump, absorbs a minimum torque, the electric machine acts as a generator, and the gas turbine generates power. This operating mode is usually operated whenever there is a power absorption peak required by the power grid, and therefore the power generated by the turbine must be converted into electrical energy and injected into the power grid. Summary of the Invention [Problem to be solved by the invention]

[0012] However, currently hybrid gas turbine systems are always implemented in a configuration that is always connected to the power distribution grid to achieve a high degree of reliability.

[0013] Therefore, improved compression stations that can achieve high reliability without the need for connection to a power generating station and / or distribution grid would be welcomed in this field as they would significantly reduce emissions while simultaneously reducing both CAPEX and OPEX. More specifically, compression stations including hybrid gas turbines that have improved flexibility and reliability and can operate in a fully decoupled mode would be welcomed.

[0014] Within the context of the present invention, the term coupling is used to denote a mechanical, electrical or magnetic connection, depending on the context.

[0015] In one aspect, the subject matter disclosed herein is directed to a low-emission compression station including multiple compressors, each coupled to an electric machine, the electric machines coupled to at least one fuel cell and / or at least one mechanically driven gas turbine along with associated electric machines including possible integration with a battery pack, the fuel cell and / or mechanically driven gas turbine sized for electrical and / or mechanical load management of the spinning reserve, and controlled / monitored by an electrical monitoring system interfacing with digital optimizers of at least some of the compression station components to ensure complete uninterrupted power supply to the compressor station and eliminate the need for power generation islands.

[0016] In another aspect, the subject matter disclosed herein relates to low-emission compression stations, where the compression station is integrated with components including auxiliary energy sources, such as renewable sources (e.g., solar panels or wind turbines), gas storage, fuel cells, and energy storage devices.

[0017] In yet another aspect, the subject matter disclosed herein relates to a low-emission compression station, where an electrical monitoring system is configured to manage all energy sources (batteries, emergency, renewable sources) to align with each other.

[0018] In yet another aspect, the subject matter disclosed herein relates to a low-emission compression station, where the electrical monitoring system is configured to manage load shedding.

[0019] In another aspect, the subject matter disclosed herein relates to low-emission compression stations that require lower CAPEX due to the lack of a dedicated power plant and lower OPEX due to fewer units subject to maintenance.

[0020] In another aspect, the subject matter disclosed herein relates to a low emission compression station that reduces the footprint required as there is no dedicated power plant, and the delta footprint is available for installation of renewable sources such as solar panels / wind turbines. Furthermore, for offshore applications, the absence of a dedicated power generation island is beneficial not only in terms of footprint but also in terms of weight savings for such power generation services. [Brief description of the drawings]

[0021] A complete understanding of the disclosed embodiments of the present invention and many of the attendant advantages thereof will be readily obtained as the same become better understood by reference to the following detailed description when considered in connection with the accompanying drawings, in which: [Figure 1] FIG. 1 is a schematic diagram of a low-emission compression station according to a first embodiment of the present disclosure. [Diagram 2] FIG. 2 is a schematic diagram of a low-emission compression station according to a second embodiment of the present disclosure. [Diagram 3] FIG. 3 is a schematic diagram of a low-emission compression station according to a third embodiment of the present disclosure. [Figure 4] FIG. 4 is a schematic diagram of a low-emission compression station according to a fourth embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] Referring to FIG. 1 , a low emission compression station according to a first embodiment of the present disclosure includes a mechanically driven hybrid gas turbine configuration (referenced generally at 10) in such configuration arrangement and with a particular method of turbomachinery sizing to eliminate the need for an additional power generating island dedicated to the compressor station.

[0023] In particular, the hybrid gas turbine 10 and associated electric machines include a battery pack 11 or possible integration with another energy storage system including, for example, a Battery Energy Storage System (BESS), Liquid Air Energy Storage (LAES), hydrogen storage, etc., and one or more other components include a renewable energy system 12, oil and gas compression station equipment 13, a power grid island 14, and an emergency power generation island 15, which are sized and controlled by an electrical monitoring system 16 to ensure a complete uninterrupted power supply to the compressor stations. This configuration is particularly suited to pipelines, but is not limited to pipelines, and each compression station can include two or three gas turbines that are fully redundant for availability purposes.

[0024] The disclosed solution lowers the CAPEX of the compressor station. In fact, usually, according to the prior art, a power island dedicated to a compressor station is composed of two generators and a gas turbine operating at reduced load. In particular, considering that a load of 50% is required to relay the full rotating reserve capacity, the estimated dedicated power island includes two gas turbines (such as gas turbine model Nova LT™ 12 (produced by Baker and Hughes)) and all related infrastructure (civil works, piping, etc.) and installation. On the other hand, a hybrid realization includes only hybrid mechanical drive gas turbines, each hybrid mechanical drive gas turbine being sized to match both the process demand and the electrical load.

[0025] The proposed solution with a properly sized hybrid mechanical drive gas turbine for rotating reserve load management also means higher efficiency as the hybrid mechanical drive gas turbine runs at higher loads. In addition, the efficiency of the station can be increased by leveraging renewable generation, which can therefore be used to decarburize the compression. This option lowers CAPEX while leveraging compression electrification.

[0026] In particular, when a single hybrid mechanical drive gas turbine is used, according to an arrangement not part of this invention, the sizing of the gas turbine must take into account that the generating portion of the gas turbine must be capable of covering 100% of the utility load. In such a case, backup power should be guaranteed by an emergency battery pack or an emergency diesel compressor.

[0027] According to the present disclosure, when two hybrid mechanical drive gas turbines operating in full redundancy are used, the main train covers the process needs, the available excess power covers a portion of the electrical load (typically 50%), and the standby train runs in pure generation mode to cover only the remaining 50% of the load. One of the two gas turbines is designed to provide the maximum electrical load and ensures full generation to the compressor station with a spinning reserve concept ensuring uninterrupted power grid supply. When employing a battery pack for spinning reserve, the standby unit starts up when the main unit trips to provide both the process and generation loads.

[0028] In the case of multiple hybrid mechanical drive gas turbines, the concept is similar to the previous case with two gas turbines, but more flexibility for load distribution is available. In addition, in this case the 3rd / 4th train can also run in maximum electric mode if power is available.

[0029] In case of daytime peak ambient temperatures, the power loss of the main compressor train can be offset by unbalancing the electrical load sharing between the two gas turbines from the typical 50%-50% to different combinations ranging from 0-100%, i.e. 100% for the gas turbine operating in pure generating mode and 0% or even negative values ​​for the main compressor train, in the latter case the main compressor train absorbs power (the generator absorbs power in a helper mode configuration and operates as a motor). If the second gas turbine operating in pure generating mode does not have enough power to supply the main compressor train and plant consumption, the battery pack and the oil and gas compression emergency system may be called upon to "help" the main compressor train. Also, load shedding may be used for such purposes.

[0030] FIG. 2 shows a low-emission compression station according to a second embodiment of the present disclosure. The system configuration includes a hybrid mechanical-driven gas turbine 20 and associated electric machines including one or more renewable energy systems 22, oil and gas compression station equipment 23, optional power grid island 24, and / or finally emergency power generation island 25, which are sized and controlled / monitored by an electrical monitoring system 26 to ensure a complete uninterrupted power supply to the compressor station. In this embodiment, there is a hydrogen storage system 21, which consists of an electrolyzer 211 for producing hydrogen, a compressor 212 and a storage tank 213, and a connection to a pipeline 214, where the hydrogen can be optionally blended with natural gas. Hydrogen from the storage tank 213 can be sent to the hybrid mechanical-driven gas turbine 20, optionally as a blend including up to 100% natural gas. The hydrogen sent to the pipeline via connection 214 can also be used to operate the hybrid mechanical-driven gas turbine 20 together with the natural gas in the pipeline. Combustion of a blend consisting of hydrogen together with natural gas also contributes to reducing the production of CO2. Hydrogen, delivered to the pipeline via connection 214, can also be used as the sole feedstock for operating the hybrid mechanical drive gas turbine 20. As a result, the combustion of hydrogen minimizes the production of CO2.

[0031] Figure 3 shows a low emission compression station according to a third embodiment of the present disclosure. The system configuration includes a hybrid mechanically driven gas turbine 30 connected to a fuel cell 37 (such as a solid oxide fuel cell) and associated electric machines including one or more renewable energy systems 32, oil and gas compression station equipment 33, optional power grid island 34, and / or finally emergency power generation island 35, which are sized and controlled / monitored by an electrical monitoring system 36 to ensure a complete uninterrupted power supply to the compressor station. In addition, in this embodiment, there is a hydrogen storage system 31, which has the same components as already shown with reference to Figure 2, namely consisting of an electrolyzer 311, a compressor 312, a storage tank 313, and a connection to a pipeline 314 where hydrogen can be blended with natural gas. The power generation island 35 and the fuel cell 37 are supplied with hydrogen from the hydrogen storage tank 313 and / or with hydrogen or natural gas or a mixture of hydrogen and natural gas from the pipeline 314. Combustion of a blend consisting of hydrogen along with natural gas contributes to reducing the production of CO2, while combustion of hydrogen minimizes the production of CO2 when hydrogen is used as the sole feedstock to operate the hybrid mechanical drive gas turbine 30 and fuel cell 37.

[0032] FIG. 4 shows a low-emission compression station according to a fourth embodiment of the present disclosure. The system configuration includes a compressor 40 with a respective electric machine electrically connected to a fuel cell 47 (such as a solid oxide fuel cell). The system configuration also includes one or more renewable energy systems 42, oil and gas compression station equipment 43, optional power grid island 44, and / or associated electric machines including an emergency power generation island 45, which are sized and controlled / monitored by an electrical monitoring system 46 to ensure a complete uninterrupted power supply to the compressor station. In addition, in this embodiment, there is a hydrogen storage system 41, which has the same components as already shown with reference to FIG. 2, namely consisting of an electrolyzer 411, a compressor 412, a storage tank 413, and a connection to a pipeline 414 where hydrogen can be blended with natural gas. Also according to this embodiment, the fuel cell 47 is supplied with hydrogen from the hydrogen storage tank 413 and / or with hydrogen or natural gas or a mixture of hydrogen and natural gas from the pipeline 414, thus reducing or minimizing the production of CO2.

[0033] While the present invention has been described in terms of 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 sequence of any process or method steps may be changed or rearranged according to alternative embodiments.

[0034] Reference will now be made in detail to embodiments of the present disclosure, one or more examples of which are illustrated in the drawings. Each example is provided as an explanation of the present disclosure, not as a limitation of the disclosure. Indeed, 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 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 an embodiment is included in at least one embodiment of the disclosed subject matter. Thus, the appearance of the phrases "in one embodiment" or "in an embodiment" or "in some embodiments" in various places throughout this specification do not necessarily refer to the same embodiment. Furthermore, particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

[0035] When presenting elements of various embodiments, 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 non-exclusive and mean that there may be additional elements other than the listed elements.

Claims

1. A low-emission compression station comprising one or more compressors, each compressor coupled to an electric machine, the electric machines coupled to at least one mechanically driven gas turbine and / or at least one fuel cell, the electric machines and / or the mechanically driven gas turbine and / or the fuel cell sized to meet both process demands and electrical loads and controlled by a monitoring system (EMS / PMS).

2. 10. The low emissions compression station of claim 1, wherein the monitoring system is interfaced with a digital optimizer that is an integral part of the compression station.

3. The low emissions compression station of claim 1 , wherein the monitoring system includes a digital optimizer.

4. 10. The low emission compression station of claim 1, wherein the compression station is integrated with an energy storage device.

5. The low emission compression station of claim 1 , wherein the compression station is integrated with a battery pack.

6. 10. The low emissions compression station of claim 1, wherein the compression station is integrated with an auxiliary energy source.

7. The low emissions compression station of claim 6 , wherein the supplemental energy source comprises a renewable energy source.

8. The low-emission compression station of claim 1 , wherein the monitoring system is configured to manage all of the energy sources for alignment with one another.

9. The low emissions compression station of claim 1 , wherein the electrical monitoring system is configured to manage load shedding.

10. The low emissions compression station of claim 1 , wherein the electric machine coupled to the mechanically driven gas turbine forms a hybrid mechanically driven gas turbine.

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