Method and plant for multi-stage gas compression

Abstract

The present disclosure provides a method of operating a gas compression plant having a main inlet, a main outlet, a plurality of compressing units, and a manifold for distributing gas to the compressing units. The method comprises operating the manifold to operate the plant in a production mode, wherein the compressing units are connected in series, and operating the manifold to operate the plant in a stand-by mode, wherein the compressing units are connected in parallel. In the stand-by mode, the compressing units maintain a tip speed of impellers substantially equal to the tip speed in the production mode, while reducing absorbed power. The method allows for flexible operation of the plant by adjusting the configuration of the manifold and valves to achieve different operating modes without substantially changing the rotational speed of impellers in the compressor units.

Description

METHOD AND PLANT FOR MULTI-STAGE GAS COMPRESSIONDescriptionTECHNICAL FIELD

[0001] The present disclosure concerns a method and plant for multi-stage gas compression.

[0002] More specifically, the present disclosure relates to compressor systems, and more particularly to a method and plant for operating multi-stage compressors in production and stand-by modes while maintaining impeller tip speed.BACKGROUND ART

[0003] Compressors are widely used in the production, storage, and transportation of gas, in particular for hydrogen. In fact, as the world shifts towards cleaner energy sources, hydrogen has gained significant attention as a potential alternative fuel. The compression of hydrogen is necessary to increase its energy density for efficient storage and transportation.

[0004] Centrifugal compressors are commonly used in hydrogen compression applications due to their ability to handle large volumes of gas in an efficient manner. These compressors utilize rotating impellers to impart kinetic energy to the gas, which is then converted into pressure energy. Multiple compression stages are often required to achieve the high pressures needed for hydrogen storage and transportation.

[0005] In traditional hydrogen production facilities, compressors typically operate continuously at full capacity to maximize output. However, the growing interest in green hydrogen production using renewable energy sources introduces new challenges.

[0006] However, renewable energy sources such as solar and wind power are, as it is well known, intermittent, resulting in variable electricity supply for hydrogen production.

[0007] This variability in energy supply leads to fluctuations in hydrogen productionrates, which in turn affects the compression systems. Conventional compressor operation strategies are not well-suited to handle these fluctuations efficiently. Starting and stopping compressors frequently in response to varying gas flow can lead to increased wear and tear on components, particularly on critical elements such as dry gas seals, and impellers.

[0008] Dry gas seals help to minimize gas leakage. These seals consist of two opposing faces that separate during normal operation. Frequent starts and stops can cause the seal faces to come into contact, potentially leading to accelerated wear and reduced seal lifespan.

[0009] Additionally, the power consumption of compressor systems becomes a significant consideration when dealing with variable renewable energy sources. Operating compressors at full capacity during periods of low hydrogen production may result in unnecessary energy expenditure.

[0010] There is a need for improved methods and systems for operating multi-stage compressor plants that can adapt to intermittent gas flow rates while maintaining efficient operation and minimizing wear on critical components. Such improvements could enhance the overall efficiency and reliability of hydrogen compression systems, particularly in the context of green hydrogen production using renewable energy sources.

[0011] Multi-stage compressor systems of the prior art still show several technical challenges, particularly in the context of hydrogen production. For instance, the European Patent Application EP4105490A1 discloses a method and system for operating a multi-stage compressor plant that try to address some technical problems connected with the wear of some mechanical parts of the centrifugal compressors. The application describes a compressor system capable of operating in two modes: a production mode and a low power mode. The solution disclosed in EP4105490A1 does not fully resolve the some cyclicity problems. When the system operates in low power mode, the speed of the compressor impellers is very low and varies considerably with respect to the operating power mode. This significant variation in impeller speed between low power and operating power modes still leads to issues related to wear, efficiency, and responsiveness of the system.

[0012] In other systems, the above-mentioned low power mode is replaced by switching off the system, which, as mentioned, can cause an increase of the wear of the system itself.SUMMARY

[0013] It is, therefore, specific object of the present disclosure a method of operating a gas compression plant that includes a main inlet for supplying gas, a main outlet for collecting compressed gas, multiple compressing units for compressing the gas, and a manifold for distributing the gas to the compressing units. The method includes the step of controlling the manifold to operate the plant in a production mode, where the compressing units are connected in series, and a stand-by mode, where the compressing units are connected in parallel.

[0014] In another aspect, disclosed herein is a method where each compressing unit includes an inlet port for gas intake, a compressor with an impeller for gas compression, and an outlet port for the compressed gas. In the stand-by mode, the tip speed of the impellers remains substantially the same as in the production mode, while absorbed power is reduced.

[0015] A further aspect of the present disclosure is drawn to a method where the manifold comprises a distribution line connected to the inlet ports of the compressing units and an upstream control valve between the main inlet and the distribution line. In production mode, the method includes closing the control valve, while in stand-by mode, the control valve is opened.

[0016] In another aspect, disclosed herein is a method where the plant comprises one or more feedforward valves, each being a three-way valve connected between the outlet port of one compressing unit and the inlet port of a consecutive unit, as well as to the main outlet. In production mode, the feedforward valves direct compressed gas to the inlet of the next compressing unit, while in stand-by mode, they direct the gas directly to the main outlet.

[0017] A further aspect of the present disclosure is drawn to a method where the plant includes an anti-surge valve positioned between the main inlet and the main outlet.

[0018] In another aspect, disclosed herein is a method where the plant comprises anexpander connected between the main inlet and the main outlet to further reduce absorbed power in the stand-by mode.

[0019] A further aspect of the present disclosure is drawn to a method where the gas being compressed is hydrogen, and the transition between production mode and standby mode is achieved without significantly altering the rotational speed of the impellers in the compressor units.

[0020] In another aspect, disclosed herein is a plant for compressing gas, comprising a main inlet, a main outlet, multiple compressing units, a manifold for gas distribution, and a control logic unit configured to execute the described method.

[0021] A further aspect of the present disclosure is drawn to a computer program and a computer-readable storage medium containing instructions that, when executed by a computer, cause it to perform the steps of the described method.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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 block diagram of a compression plant for compressing gas, according to a first embodiment of the present disclosure;Fig. 2 illustrates a block diagram of a compression plant for compressing gas, according to a second embodiment of the present disclosure;Fig. 3 illustrates a flowchart of a method for operating a gas compression plant, according to an embodiment;Fig. 4 illustrates a detailed view of a step from the method of Fig. 3, according to aspects of the present disclosure; andFig. 5 illustrates a detailed view of a step from the method of Fig. 3, according to aspects of the present disclosure.DETAILED DESCRIPTION OF EMBODIMENTS

[0023] According to one aspect, the present subject matter is directed to a method andsystem for operating a gas compression plant with multiple compressor stages. The plant can operate in two modes: a production mode, where compressor stages are connected in series, and a stand-by operating in stand-by recycle where stages are connected in parallel. In the stand-by mode, the compressor impellers maintain tip speeds similar to production mode while reducing power consumption. This allows the plant to efficiently handle variable gas flow rates, such as in green hydrogen production using intermittent renewable energy, by quickly transitioning between modes without significantly changing impeller speeds. The system includes valves and a manifold to control gas flow between stages, enabling flexible operation while minimizing wear on components.

[0024] In the various figures, similar parts will be indicated by the same reference numbers.

[0025] Referring to Fig. 1, a gas compression plant 1 is shown according to a first embodiment. The gas compression plant 1 includes a main inlet 11, a main outlet 12, a plurality of compressing units 31, 32, 33, wholly indicated also with the reference number 3, and a manifold 2, capable of allowing the compression plant 1 to pass from an operating mode and a stand-by mode, as better explained below.

[0026] Through the main inlet 11 the gas to be compressed is introduced. In some aspects, the gas may be hydrogen, although other gases may be used in other embodiments. The main outlet 12 is where the compressed gas is collected after it has been compressed by the compressing units 31, 32, 33.

[0027] The compressing units 31, 32, 33 are configured to compress the gas supplied through the main inlet 11 and collecting the compressed gas to the main outlet 12, for it to be then stored and possibly transported.

[0028] Each compressing unit 31, 32, 33, which in the embodiment at issue are three, comprises an inlet port 311, 321, 331, a compressor 314, 324, 334, and an outlet port 312, 322, 332. Each inlet port 311, 321, 331 allows the gas to enter the relevant compressing unit. Each compressor 314, 324, 334 compresses the gas. Finally, each outlet port 312, 322, 332 allows the compressed gas to exit the relevant compressing unit.

[0029] In other embodiments, the number of the compressing unit 3 can vary.

[0030] The compressors 314, 324, 334 installed in the compressing units 31, 32, 33 can be of different type. In the present embodiment, the compressors 314, 324, 334 are centrifugal compressor, which are machines that typically used to increase gas pressure by converting kinetic energy into potential energy. A centrifugal compressor consists of a rotating impeller, a diffuser, and a volute casing. The impeller, typically made from high-strength materials, accelerates the gas outward, while the diffuser slows it down to increase pressure. The volute casing collects the gas and directs it toward the discharge port, ensuring uniform pressure distribution and reducing turbulence.

[0031] The impellers are assembled sequentially composing a rotating shaft supported by bearings, which have to be lubricated and cooled. Seals are employed to prevent gas leakage, and in applications requiring high pressure, the compressor may be configured in multiple stages. Cooling systems, are often based on air or water cooling, to prevent overheating during compression.

[0032] Materials used in the compressor, such as high-strength steels and alloys, are selected based on operational needs, and advanced manufacturing techniques are used to produce the components. Modern centrifugal compressors include control systems that regulate speed, flow, and pressure, ensuring efficient and safe operation. These compressors are versatile and widely used in industries ranging from gas processing to HVAC systems due to their reliability and efficiency.

[0033] In some cases, the compressors 314, 324, 334 may be designed to reach high tip speed rates, up to 600 m / s, for example.

[0034] The manifold 2 of the compression plant 1 may comprise a distribution line 21 and an upstream control valve 22. The distribution line 21 is connected to the inlet ports 311, 321, 331 of the compressing units 31, 32, 33, allowing the gas to be distributed to each compressing unit 31, 32, 33. The upstream control valve 22 is connected between the main inlet 11 and the distribution line 21.

[0035] The upstream control valve 22 is used to control the flow of gas from the main inlet 11 to the distribution line 21.

[0036] In some embodiments, the compression plant 1 may include one or more feedforward valves 231, 232. Each feedforward valve 231, 232 may be a three-way valve,although other types of valves capable of switching or deviating the gas flow can be used. Each feedforward valve 231, 232 may be connected between the outlet port 313, 323 and the inlet port 321, 331 of two consecutive compressing units 31, 32, 33, and to the main outlet 12.

[0037] The feedforward valves 231, 232 is used to control the routing of the compressed gas coming from the outlet port 313, 323 of the respective compressing unit 31, 32 to either the inlet port 321, 331 of the consecutive compressing unit 32, 33 or to the main outlet 12, depending on the operating mode of the compression plant 1.

[0038] Still referring to Fig. 1, in the stand-by mode, the compressing units 31, 32, 33 of the compression plant 1 may maintain a tip speed of the impellers (not shown in the figure) of the compressor 314, 324, 334 substantially equal to the tip speed in the production mode, while however reducing the absorbed power. This may be achieved by operating the manifold 2 to connect the compressing units 31, 32, 33 in parallel, allowing for the recirculation of gas through the manifold 2.

[0039] In the stand-by le mode is then routed from the outlet port 313, 323 of one compressing unit 31, 32 to the main outlet 12, rather than to the inlet port 321, 331 of the next compressing unit 32, 33 arranged in series. This change of configuration from series to parallel may decrease the gas density and the absorbed power without the need to reduce the speed of the impellers in the compressing units 31, 32, 33.

[0040] The compression plant 1 comprises an anti-surge valve 41, connected between the main inlet 11 and the main outlet 12 through an anti-surge line 4. The anti-surge valve 41 may be used to prevent surge conditions in the compressing units 31, 32, 33 by allowing a portion of the compressed gas to be recirculated back to the main inlet 11 when the plant 1 operates in the stand-by mode.

[0041] The compression plant 1 also comprises a control logic unit U, which is connected to the manifold 2, an in particular to the upstream control valve 22 and to the feedforward valves 231, 232. The control logic unit U is designed and programmable to control said valves to allow operating the compression plant 1 in production mode or in stand-by mode, by switching or closing such valves, to change the connection from series to parallel of the compressing units 3.

[0042] The control logic unit U is also connected to the anti-surge valve 41, so that the unit U can open or close it based on the operating conditions of the compression plant 1.

[0043] Referring also to Fig. 2, it is shown another embodiment of the compression plant 1, which comprises, min addition, an expander 42, connected between the main inlet 11 and the main outlet 12 through the anti-surge line 4. The expander 42 may be used to further reduce absorbed power in the stand-by mode by expanding the compressed gas before it is recirculated back to the main inlet 11. In some cases, the expander 42 may be a turbine or a similar device capable of converting the kinetic energy of the compressed gas into mechanical work, which may be used to power other components of the compression plant 1.

[0044] The control logic unit U may be configured to execute a method 100 of operating the gas compression plant 1.

[0045] The control logic unit U may be a computer or a similar device capable of executing programmed instructions.

[0046] The control logic unit U can be implemented in several ways. In fact, the control logic unit U can be a microprocessor. Microprocessors are highly versatile and programmable and can be embedded in a wide variety of electronic schemes. The primary advantage of using microprocessors lies in their ability to execute a wide array of instructions and manage multiple tasks simultaneously. They offer high computational power in a compact form factor, making them suitable for integration into different systems. Furthermore, microprocessors are widely supported by a robust ecosystem of software development tools and libraries, facilitating rapid application development and deployment.

[0047] In some other embodiments, the control logic unit U can be implemented through Field-Programmable Gate Arrays (FPGAs). FPGAs offer the advantage of reconfigurability, allowing developers to tailor the hardware functionality to specific application needs even after deployment. This flexibility makes FPGAs ideal for applications requiring specialized processing capabilities and adaptability. Additionally, FPGAs can achieve high levels of parallelism, significantly improving the performance for tasks that can be executed concurrently.

[0048] In other embodiments, the control logic unit U can be implemented as a personal computer (PC). PCs are well-suited for a wide range of applications. The advantage of implementing the control logic unit U in a personal computer is the extensive computational resources available, including advanced graphics processing units (GPUs) and high-speed memory.

[0049] An additional implementation option is the use of Application-Specific Integrated Circuits (ASICs). ASICs are custom-designed for specific tasks, providing optimal performance and efficiency for particular applications. An advantage of ASICs is their ability to deliver high performance with minimal power consumption.

[0050] In some aspects, the control logic unit U may control the operation of the upstream control valve 22, the feedforward valves 231, 232, the anti-surge valve 41, and other components of the compression plant 1 to allow the transition between the production mode and the stand-by mode. The control logic unit U may also monitor the operating conditions of the compression plant 1 and adjust the operation of the components accordingly to optimize the performance of the compression plant 1.

[0051] Referring to Fig. 3, a flow chart of the method 100 for operating the gas compression plant 1 is shown. As mentioned, the method 100 may be executed by the control logic unit U, which may be a computer or a similar device capable of executing programmed instructions. In some cases, the method 100 may be embodied in a computer program that, when executed by a computer, causes the computer to execute the steps of the method 100. In other cases, the method 100 may be embodied in instructions stored on a computer-readable storage medium, which, when executed by a computer, cause the execution of the method steps by the computer.

[0052] The method 100 comprises a step 110 for controlling and operating the manifold 2 to operate the plant 1 in a production mode: In this case, the compressing units31, 32, 33 are connected in series. In the production mode, the gas to be compressed is supplied through the main inlet 11, distributed to the compressing units 31, 32, 33 via the distribution line 21 of the manifold 2, compressed by the compressing units 31,32, 33, and collected at the main outlet 12.

[0053] In this case, in the operating mode, the total compression ratio c°pModeof the compression plant 1 is the product of the compression ratios of each compressing unit3, namely:where C£is the compression ratio of the i-th compressing unit 3.

[0054] Referring to Fig. 4, the sub-steps of the step of 110 of controlling the manifold 2 are shown for the compression plant 1 to operate in production mode are shown. In particular, the operating the plant 1 in the production mode comprises the sub-steps of closing 111 the upstream control valve 22. This may prevent the flow of gas from the main inlet 11 to the distribution line 21, thereby directing the gas to the compressing units 31, 32, 33 connected in series. The control logic unit U then controls the operation of the upstream control valve 22 to close it when the plant 1 is to be operated in the production mode.

[0055] Operating the plant 1 in the production mode also comprises the sub-step of switching 112 one or more feedforward valves 231, 232 so that the compressed gas coming from the outlet port 313, 323 of the respective compressing unit 31, 32 is routed to the inlet port 321, 331 of the consecutive compressing units 32, 33. This allows the compressed gas to be further compressed by the consecutive compressing units 32, 33, thereby increasing the pressure of the gas at the main outlet 12. The control logic unit U controls the operation of the feedforward valves 231, 232 to switch them to route the compressed gas to the consecutive compressing units 32, 33 when the plant 1 is operated in the production mode.

[0056] In some cases, the method 100 may further comprise monitoring the operating conditions of the compression plant 1 and adjusting the operation of the components accordingly to optimize the performance of the compression plant 1. For example, the control logic unit U may monitor the pressure of the gas at the main inlet 11 and the main outlet 12, the rotational speed of the impellers in the compressing units 31, 32, 33, and other operating conditions, and adjust the operation of the upstream control valve 22, the feedforward valves 231, 232, and other components based on the monitored conditions. To this end, the compression plant 1 may comprise suitable sensors, like temperature sensors and pressure sensors, for acquiring data about the operationof the different parts of the plant 1.

[0057] Referring to Fig. 5, the sub-steps of the step of 120 of controlling the manifold 2 are shown for the compression plant 1 to operate in full recovery mode are shown. In particular, the method 100 further involves operating the manifold 2 to operate the plant 1 in a stand-by mode, wherein the compressing units 31, 32, 33 are connected in parallel. In the stand-by mode, the gas to be compressed is supplied through the main inlet 11, distributed to the compressing units 31, 32, 33 via the distribution line 21 of the manifold 2, and then recirculated back to the main inlet 11. This configuration allows the plant 1 to maintain the tip speed of the impellers in the compressing units 31, 32, 33 while reducing absorbed power.

[0058] Operating the plant 1 in the stand-by mode comprises the step of opening 121 the upstream control valve 22. This allows the gas to flow from the main inlet 11 to the distribution line 21, thereby distributing the gas to the compressing units 31, 32, 33 connected in parallel. The control logic unit U controls the operation of the upstream control valve 22 to open it when the plant 1 is to be operated in the stand-by mode.

[0059] Operating the plant 1 in the stand-by mode also comprises the step of switching 122 one or more feedforward valves 231, 232 so that the compressed gas coming from the outlet port 313, 323 of the respective compressing unit 31, 32 is routed to the main outlet 12, rather than to the inlet port 321, 331 of the next compressing unit 32, 33 arranged in series. This prevents the compressed gas to be compressed multiple times, and possibly recirculated back to the main inlet 11, thereby reducing the density of the gas and the absorbed power without the need to reduce the speed of the impellers in the compressing units 31, 32, 33. Also in this case, the control logic unit U controls the operation of the feedforward valves 231, 232 to switch them to route the compressed gas to the main outlet 12 when the plant 1 is operated in the stand-by mode.

[0060] In this case, in the stand-by mode, the total compression ratio of the compression plant 1 is the compression ratio of the first compressor.

[0061] The computer program implemented in the control logic unit may include instructions for controlling the operation of the upstream control valve 22, the feedforward valves 231, 232, and other components of the compression plant 1 to transitionbetween the production mode and the stand-by e mode.

[0062] Continuing referring to Fig. 5, in the stand-by mode the compressing units 31, 32, 33 are connected in parallel, allowing for the recirculation of gas through the manifold 2. This configuration may be particularly beneficial during periods of low production demand, such as, if the plant is supplied by renewable energy, like the sun, to allow the plant 1 to maintain the tip speed of the impellers in the compressing units 31, 32, 33 while reducing absorbed power. In this way, the mechanical parts of the plant are not affected by the wear due to the cyclical operations.

[0063] To pass from the full recovery mode to the operating mode, the control logic unit U, still operating the manifold 2, closes the control valve 22, and switch the each feedforward valve 231, 232, so that he gas of a compressing unit 3 is directed at the inlet port inlet port 311, 321, 331 of the following, so connecting the compressing unit 3 in series.

[0064] The change of configuration from series to parallel and vice-versa, decreases the gas density and the absorbed power without the need to reduce the speed of the impellers in the compressing units 31, 32, 33.

[0065] In some aspects, the gas being compressed in the compression plant 1 may be hydrogen. Hydrogen is an important gas in various industrial processes and is gaining importance in the energy sector as a clean fuel. The compression plant 1 may be particularly suited for compressing hydrogen due to its capacity to handle variable gas flow rates and its capability to operate in the two distinct modes disclosed above, i.e., the production mode and the stand-by mode.

[0066] The compressing units 31, 32, 33 of the compression plant 1 may include impellers that are designed to rotate at high speeds. In some cases, the impellers may reach a tip speed as high as 600 m / s.

[0067] The impellers in the compressing units 31, 32, 33 may be made of various materials depending on the specific requirements of the application. In some cases, the impellers may be made of Low Alloy Steels, which are known for their strength and durability. In other cases, the impellers may be made of Martensitic Precipitation hardening Stainless Steels, such as 17-4PH, which offer excellent corrosion resistance andhigh strength. In yet other cases, the impellers may be made of Ni based superalloys, such as IN718, which are known for their high-temperature strength and resistance to creep. The choice of impeller material may depend on factors such as the operating conditions of the compression plant 1, the type of gas being compressed, and the desired performance characteristics of the compressing units 31, 32, 33.

[0068] One of the notable features of the compression plant 1, as mentioned above, is its ability to transition between the production mode and the stand-by mode without substantially changing the rotational speed of the impellers in the compressing units 31, 32, 33. This feature may be particularly beneficial in in case of the gas flow rate varies, such as in green hydrogen production facilities powered by intermittent renewable energy sources. By maintaining a substantially constant impeller speed, the compression plant 1 may reduce mechanical stress on the impellers and other components of the compressing units 31, 32, 33, potentially extending their service life and reducing maintenance requirements.

[0069] In some aspects, the compression plant 1 may be utilized for compressing hydrogen that is produced by solar energy. Solar energy is a renewable energy source that can be harnessed to produce hydrogen through electrolysis. However, the production of hydrogen using solar energy may be intermittent, as solar energy is not available during the night or during periods of low sunlight. Therefore, as already mentioned, he compression plant 1 may be designed to operate efficiently even when the hydrogen production rate fluctuates.

[0070] When installed, for example, in a broader hydrogen production plant, the compression plant 1 may operate in the stand-by mode during periods of no solar energy production, e.g., in the night, where the compression plant 1 maintains the tip speed of the impellers of the compressing units 31, 32, 33 while reducing absorbed power.

[0071] In some embodiments, the compression plant 1 may be capable of compressing the hydrogen up to 30 bar. This high pressure may be necessary for certain applications, such as the storage and transportation of hydrogen. The ability to compress hydrogen to such high pressures may make the compression plant 1 particularly suitable for use in hydrogen production facilities, where the hydrogen produced needs to be stored and transported for use in various applications.

[0072] It is to be appreciated that the concepts, systems, circuits, and techniques sought to be protected herein are not limited to use in the example applications described herein (e.g., industrial applications), but rather may be useful in substantially any application where it is desired to receive decision support for each step in an automated fashion. While particular embodiments and applications of the present disclosure have been illustrated and described in connection with hydrogen compression and the energy industry, it is to be understood that embodiments of the disclosure are not limited to the precise construction and compositions disclosed herein and that various modifications, changes, and variations can be apparent from the foregoing descriptions without departing from the scope of the disclosure.ADVANTAGES

[0073] An advantage of the present disclosure is that it allows for efficient operation of multi-stage compressor plants during periods of no gas production, such as when renewable energy sources are unavailable for hydrogen generation. By transitioning to a stand-by mode where compressor stages operate in parallel, the system can maintain impeller tip speeds while significantly reducing absorbed power.

[0074] Another advantage of the present disclosure is that it enables rapid transitions between production and stand-by modes without substantially changing impeller rotational speeds. This reduces mechanical stress on compressor components, particularly dry gas seals, potentially extending equipment life and reducing maintenance requirements, including increasing the lifespan of some elements like the dry gas seals.

[0075] Another advantage of the present disclosure is the reduced cycling stress of impeller material allowing the use of less impellers and / or more economic material.

[0076] It is an advantage of the present disclosure because it provides a flexible solution for hydrogen compression in green energy applications where production rates may vary based on renewable energy availability. This adaptability supports the integration of intermittent energy sources into hydrogen production and compression processes.

[0077] While aspects of the invention have been described in terms of various specificembodiments, it will be apparent to those of ordinary skill in the art that many modifications, changes, and omissions are possible without departing form the spirt 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.

[0078] 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 or more embodiments.

[0079] 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.

[0080] The subject matter described herein can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structural means disclosed in this specification and structural equivalents thereof, or in combinations of them. The subject matter described herein can be implemented as one or more computer program products, such as one or more computer programs tangibly embodied in an information carrier (e.g., in a machine-readable storage device), or embodied in a propagated signal, for execution by, or to control the operation of, data processing apparatus (e.g., a programmable processor, a computer, or multiple computers). A computer program (also known as a program, software, software applica-tion, or code) can be written in any form of programming language, including compiled or interpreted languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program does not necessarily correspond to a file. A program can be stored in a portion of a file that holds other programs or data, in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub-programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and interconnected by a communication network.

[0081] The processes and logic flows described in this specification, including the method steps of the subject matter described herein, can be performed by one or more programmable processors executing one or more computer programs to perform functions of the subject matter described herein by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus of the subject matter described herein can be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[0082] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory, or a random access memory, or both. The essential elements of a computer are a processor for executing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto-optical disks, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of example semiconductor memory devices, (e.g., EPROM, EEPROM, and flash memory devices); magnetic disks, (e.g., internal hard disks or removable disks); magneto-optical disks; and optical disks (e.g., CD and DVD disks). The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0083] To provide for interaction with a user, the subject matter described herein can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, (e.g., a mouse or a trackball), by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well. For example, feedback provided to the user can be any form of sensory feedback, (e.g., visual feedback, auditory feedback, or tactile feedback), and input from the user can be received in any form, including acoustic, speech, or tactile input.

[0084] The techniques described herein can be implemented using one or more modules. As used herein, the term “module” refers to computing software, firmware, hardware, and / or various combinations thereof. At a minimum, however, modules are not to be interpreted as software that is not implemented on hardware, firmware, or recorded on a non-transitory processor readable recordable storage medium (i.e., modules are not software per se). Indeed “module” is to be interpreted to always include at least some physical, non-transitory hardware such as a part of a processor or computer. Two different modules can share the same physical hardware (e.g., two different modules can use the same processor and network interface). The modules described herein can be combined, integrated, separated, and / or duplicated to support various applications. Also, a function described herein as being performed at a particular module can be performed at one or more other modules and / or by one or more other devices instead of or in addition to the function performed at the particular module. Further, the modules can be implemented across multiple devices and / or other components local or remote to one another. Additionally, the modules can be moved from one device and added to another device, and / or can be included in both devices.

[0085] The subj ect matter described herein can be implemented in a computing system that includes a back-end component (e.g., a data server), a middleware component (e.g., an application server), or a front-end component (e.g., a client computer having a graphical user interface or a web browser through which a user can interact with an implementation of the subject matter described herein), or any combination of such back-end, middleware, and front-end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a com-munication network. Examples of communication networks include a local area network (“LAN”) and a wide area network (“WAN”), e.g., the Internet.

Claims

METHOD AND PLANT FOR MULTI-STAGE GAS COMPRESSIONCLAIMS1. A method (100) of operating a gas compression plant (1) having a main inlet (11), through which the gas to be compressed is supplied, a main outlet (12), through which the compressed gas is collected, a plurality of compressing units (3; 31, 32, 33), for compressing the gas supplied through the main inlet (11) and collect the compressed gas to the main outlet (12), and a manifold (2) for distributing gas to be compressed to the compressing units (3; 31, 32, 33), wherein the operating method (100) comprises the steps of: controlling (110) the manifold (2) to operate the plant (1) in a production mode, wherein the compressing units (3; 31, 32, 33) are connected in series; and controlling (120) the manifold (2) to operate the plant (1) in a standby mode, wherein the compressing units (3; 31, 32, 33) are connected in parallel.

2. The method (100) of claim 1, wherein each compressing unit (3; 31, 32, 33) comprises: an inlet port (311, 321, 331), through which the gas to be compressed enters the compressing unit (3; 31, 32, 33); a compressor (314, 324, 334), having an impeller, which rotates to compress the gas that enters through the inlet port (311, 321, 331); and an outlet port (313, 323, 333), thought which the gas compressed by the compressor (314, 324, 334) exits the compressing unit (3; 31, 32, 33); wherein in the stand-by mode, the compressing units (3; 31, 32, 33) maintain a tip speed of the impellers substantially equal to the tip speed in the production mode, while reducing absorbed power.

3. The method (100) of any one of the preceding claims, wherein the manifold (2) comprises: a distribution line (21), connected to the inlet ports (311, 321, 331) of thecompressing units (3; 31, 32, 33); and an upstream control valve (22) connected between the main inlet (11) and the distribution line (21), wherein in the step of controlling (110) the manifold (2) to operate the plant (1) in the production mode comprises the step of closing (111) the control valve (22), and wherein in the step of operating (120) the manifold (2) to operate the plant (1) in the stand-by mode comprises the step of opening (121) the control valve (22).

4. The method (100) of any one of the preceding claims, wherein the plant (1) comprises one or more feedforward valves (231, 232); wherein each feedforward valve (231, 232) is a three way valve; wherein each feedforward valve (231, 232) is connected between the outlet port (313, 323, 333) and the inlet port (311, 321, 331) of two consecutive compressing units (3; 31, 32, 33), and to the main outlet (12); wherein the step of operating (110) the manifold (2) to operate the plant (1) in the production mode comprises the step of switching (112) one or more feedforward valves (231, 232) so that the compressed gas coming from the outlet port of the respective compressing unit (3; 31, 32, 33) is routed to the inlet port of the consecutive compressing units (3; 31, 32, 33), when the plant (1) operates in the production mode; and wherein the step of operating (120) the manifold (2) to operate the plant (1) in the stand-by mode comprises the step of switching (122) one or more feedforward valves (231, 232) so that the compressed gas coming from the outlet port of the respective compressing unit (3; 31, 32, 33) is routed to the main outlet (12).

5. The method (100) of any one of the preceding claims, wherein the plant (1) comprises an anti-surge valve (41), connected between main inlet (11) and the main outlet (12).

6. The method (100) of any one of the preceding claims, wherein the plant (1) comprises an expander (42), connected between main inlet (11) and the main outlet (12), to further reduce absorbed power in the stand-by mode.

7. The method (100) of any one of the preceding claims, wherein the gas is hydrogen.

8. The method (100) of any one of the preceding claims, wherein transitioning between the production mode and the stand-by mode is accomplished without substantially changing a rotational speed of impellers in the compressor units (3; 31, 32, 33).

9. A plant (1) for compressing gas, comprising: a main inlet (11), through which the gas to be compressed is supplied, a main outlet (12), through which the compressed gas is collected, a plurality of compressing units (3; 31, 32, 33), for compressing the gas supplied through the main inlet (11) and collect the compressed gas to the main outlet (12), and a manifold (2) for distributing gas to be compressed to the compressing units (3; 31, 32, 33), and a control logic unit (U) configured to execute the method (100) of any one of the preceding claims.

10. The plant (1) of claim 9, wherein each compressing unit (3; 31, 32, 33) comprises: an inlet port (311, 321, 331), through which the gas can enter the compressing unit (3; 31, 32, 33); a compressor (314, 324, 334), having an impeller, which rotates to compress the gas that enters through the inlet port (311, 321, 331); and an outlet port (313, 323, 333), thought which the gas compressed by the compressor (314, 324, 334) exits the compressing unit (3; 31, 32, 33); wherein in the stand-by mode, the compressing units (3; 31, 32, 33) maintain a tip speed of the impellers substantially equal to the tip speed in the production mode, while reducing absorbed power.

11. The plant (1) of any one of claims 9 or 10, wherein the manifold (2) comprises: a distribution line (21), connected to the inlet ports (311, 321, 331) of the compressing units (3; 31, 32, 33); andan upstream control valve (22) connected between the main inlet (11) and the distribution line (21).

12. The plant (1) of any one of claims 9 - 11, comprising one or more feedforward valves (231, 232); wherein each feedforward valve (231, 232) is a three way valve; wherein each feedforward valve (231, 232) is connected between the outlet port (313, 323, 333) and the inlet port (311, 321, 331) of two consecutive compressing units (3; 31, 32, 33), and to the main outlet (12); wherein the control logic unit (U) is configured to control each feedforward valve (231, 232) so that the compressed gas coming from the outlet port (313, 323) of the respective compressing unit (3; 31, 32, 33) can be routed:- to the inlet port of the consecutive compressing units (3; 31, 32, 33), when the plant (1) operates in the production mode; and- to the main outlet (12), when the plant (1) operates in the stand-by mode.

13. The plant (1) of any one of claims 9 - 12, comprising an anti-surge valve (41), connected between main inlet (11) and the main outlet (12).

14. The plant (1) of any one of claims 9 - 13, comprising an expander (42), connected between main inlet (11) and the main outlet (12), to further reduce absorbed power in the stand-by mode.

15. The plant (1) of any one of claims 9 - 14, wherein the gas is hydrogen, and wherein transitioning between the production mode and the stand-by mode is accomplished without substantially changing a rotational speed of impellers in the compressor units (3; 31, 32, 33).

16. Computer program comprising instructions that, when the program is executed by a computer, cause the computer to execute the steps of the method (100) according to any one of the claims 1-8.

17. Computer readable storage medium comprising instructions which, when-22-executed by a computer, cause the execution of the method steps by the computer according to any one of the claims 1-8.

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