Device and method for expanding gases under high pressure using an expansion machine that can be integrated into pressure regulating devices

Abstract

The invention relates to a device (1) for expansion under pressure (p HD ) gases (7) transported in pipelines (12), preferably natural gas (7) transported in pipelines, wherein the gas (7) to be expanded is subjected to a lower pressure (p) in at least one expansion machine (2). ND ) is expanded, wherein the rotational energy of the expansion machine (2) can be used to recover energy from the gas (7) to be expanded in the form of technically usable work, and wherein the device (1) has at least one radially flowed expansion machine (2) in the form of a radial impulse turbine, the guide devices (4) and radial impeller (11) of which is arranged within the section of the pipeline (12) through which the gas (7) to be expanded flows and through which the gas (7) to be expanded flows.

Description

[0001] The invention relates to a device for expanding pressurized gases by means of an expansion machine according to the preamble of claim 1 and to a method according to the preamble of claim 13.

[0002] The economical transport of gas, and especially of economically very important natural gas, over long distances generally takes place at high pressures (approximately 60-80 bar). In order to distribute the gas locally at points along the pipeline, the pressure must be reduced again before it can be fed into the local distribution system. The natural gas is then made available to the end customer at a low pressure. Between the high-pressure and low-pressure networks, the natural gas is usually gradually expanded in several gas pressure regulating stations (GPR) or gas pressure control and measurement stations (GPRM). The pressure reduction or natural gas expansion is generally achieved by throttling using simple pressure regulators, usually in the form of expansion valves. The aim downstream of these pressure regulators is to achieve a constant outlet pressure regardless of the influence of disturbances (changes in inlet pressure and / or flow).According to the current state of the art, the applied pressure potential (depending on the required output pressure) is reduced via a simple, variable throttling point. Entropy is generated accordingly, and usable energy (so-called exergy) is dissipated. This impedes the efficient use of the exergy (=usable portion of energy) introduced / contained in the (natural) gas distribution network and the connected storage stations, for example, from previous gas compression or the heat input through gas preheating, and offers significant potential for (decentralized) energy recovery.

[0003] Instead of reducing the pressure with the help of a pressure regulator, it is also possible to reduce the pressure with the help of an expansion machine and thereby convert part of the pressure potential supplied with the high-pressure gas into usable energy, for example by mechanically coupling a generator to the expansion machine in such a way that the generator is driven by the expansion machine and produces electricity.

[0004] For example, it is known from EP 3 001 012 B1 to use an expansion machine such as an expansion turbine, an expander or generally a gas turbine to expand the gas. This expansion machine uses the flow energy of the gas during expansion to produce electricity in a generator that works functionally together with the expansion machine and thereby recovers some of the exergy uselessly dissipated in pure pressure regulators. To this end, it is described that an expansion machine is arranged in a pipeline section within the pressure control station in such a way that the gas flows primarily axially through the expansion machine, wherein the expansion machine is designed as a fixed, partially pressurized axial turbine in the form of a bulb turbine and is arranged completely within the pipe cross-section. In addition to energy recovery, such an expansion machine can also be used to utilize geothermal energy.

[0005] From DE 10 2021 119 820 A1, it is also known to extend the principle of the axial (natural) gas expansion turbine in the form of a bulb turbine device by a variable partial admission for power-optimized power generation. This takes into account the fact that significantly different volume flows can occur in gas distribution networks, which leads to suboptimal operating conditions in an axial turbine designed for an optimal operating point and with a fixed partial admission, thus impairing energy recovery. By providing a cross-section adjustment device for changing the flow-through cross-sectional area of ​​the bulb turbine device, the power of the bulb turbine device can be adjusted to changing volume flows by partial admission.

[0006] DE 10 2022 104 835 A1 describes an implementation of actively controlled, variable partial pressure on an axial turbine using a lever mechanism (active = moved by external energy). The application of the axial turbine, which is also arranged inside the flow-through pipe, is characterized by its function as a pressure regulator including zero-pressure shutoff.

[0007] A disadvantage of such arrangements of axial turbines within the flow pipe is the need to accommodate a corresponding pipe section in a gas pressure regulation station. This usually requires complex modifications and expansions, which impair the economic use of energy recovery. Furthermore, accessibility to the axial turbines during operation, for example, for inspection and maintenance, is compromised.

[0008] KR 10 2016 0 139 674 A discloses an expansion machine for expanding pressurized gas streams, in which the rotational energy of a turbine can recover energy from the pressure difference of the gas to be reduced. Here, too, an axial turbine is used, which is not integrated into a control valve and is not completely arranged in a pipeline.

[0009] The object of the present invention is therefore to propose a relaxation of gases in high-pressure lines by means of expansion machines, in which an arrangement of the expansion machine allows a simplified installation in existing systems and at the same time a control of the pressure downstream of the expansion machine.

[0010] The solution to the problem of the invention arises with regard to the device from the characterizing features of claim 1 and with regard to the method from the features of claim 13, each in conjunction with the features of the corresponding preamble. Further advantageous embodiments of the invention emerge from the dependent claims.

[0011] The invention is based on a device for expanding pressurised gases transported in pipelines, preferably natural gas transported in pipelines, in which the gas to be expanded is expanded to a lower pressure in at least one expansion machine, wherein the rotational energy of the expansion machine can be used to recover energy from the gas to be expanded in the form of technically usable work. Such a generic device is further developed according to the invention in that the device has at least one expansion machine, now with radial flow, in the form of a radial constant pressure turbine, the guide devices and radial impeller of which are arranged completely within the section of the pipeline through which the gas to be expanded flows and through which the gas to be expanded flows. This design enables, for the first time, a direct integration of a, for example,The expansion machine, designed as a turbine stage, is integrated into the gas pressure regulators that have been in use for years in the (natural) gas distribution network and connected storage stations. For example, by arranging the rotational axis of the radially flowing impeller of the expansion machine transversely, preferably at 90°, to the flow direction of the gas to be expanded in the pipe through which it flows, in a further embodiment, installation conditions can be achieved which, unlike the axial pipe turbines known to date, require only a small amount of space in the flow direction of the gas and can therefore be easily integrated into existing installations in gas pressure regulators. This allows conventional gas pressure regulators to be replaced with devices according to the invention, thus enabling energy to be recovered from the gas to be expanded without complex modifications.By orienting the radial-flow expansion machine perpendicular to the gas flow direction through an existing pipeline section, both the expansion machine and a generator mounted on the expansion machine, for example, or another device suitable for harnessing the mechanical energy of the expansion machine, can be installed in a free lateral installation space to the existing pipeline for the gas flow. This ensures that only a short installation length is required for the expansion machine in the existing pipeline for the gas flow and expansion.In a further embodiment, it is also conceivable that essentially only the impeller of the expansion machine is arranged within the pipe through which the gas flows. This in turn means that essential components of the expansion machine and any generator flanged to it can be arranged outside the existing pipeline for the gas flow, thereby also improving their accessibility for maintenance and repairs. Apart from the impeller itself, only bearings or control devices of the expansion machine are arranged within the existing pipeline. Such retrofitting of existing installations in gas pressure regulating stations (GDR) or gas pressure regulating and measuring stations (GDRM) with gas pressure regulating devices used there using expansion machines is therefore technically relatively inexpensive and therefore economically feasible and allows effective energy recovery from the energy potential of the gas to be expanded.Of course, multiple stages of such expansion machines are also possible. Such constant-pressure turbines are robust and, due to the flow conditions in their impellers, effective in energy conversion. They also allow partial impeller loading.

[0012] It is particularly advantageous if the device is equipped with a control device that variably adjusts the volume flow of the gas to be expanded through the expansion machine and the pressure after flowing through the expansion machine. This allows the respective operating point of the radial expansion machine to be optimally adapted to the constantly changing pressures and volume flows of the gas to be expanded, in order to, on the one hand, ensure a desired output pressure after flowing through the expansion machine and, on the other hand, to optimally adapt the energy recovery from the energy potential of the gas to be expanded to the operating behavior of the expansion machine and any generator coupled to it.

[0013] In a further embodiment, the control device can comprise a metering device that adjustably influences the flow path of the gas through the radial impeller of the expansion machine and / or the flow cross-section of the gas toward the impeller of the expansion machine, and regulates the volume flow of the gas to be expanded through the expansion machine. Such a metering device, which in a further embodiment can be arranged, for example, in the area of ​​the guide devices of the impeller of the expansion machine, can adjustably cover the inflow sections to the impeller and thereby specify the volume flow through the radial impeller of the expansion machine.For example, it is conceivable for the metering device to be designed as a bell-shaped hood surrounding the impeller of the expansion machine, the position of which relative to the impeller is adjusted depending on the desired operating point of the expansion machine. The hood more or less covers the impeller from the volume flow of the incoming gas to be expanded, thus influencing the flow through the impeller. Of course, all other known and conceivable adjustment options for the volume flow through the impeller for radial impellers are also applicable here. At the same time, the existing control mechanism of the gas pressure regulators can thus be used for the first time in parallel for passive control of the partial impeller pressure (passive = without external energy).In this way, a passively controllable, variably actuated, radial (natural) gas expansion turbine, including zero shutoff, can be implemented within existing control valves. It is particularly advantageous if the metering device can be set to a position that allows zero shutoff of the expansion machine's impeller. This allows the metering device to completely suppress the gas flow through the expansion machine.

[0014] With regard to the application of the device according to the invention, it is particularly advantageous if the radially flowing expansion machine can be integrated into a conventional gas pressure regulator. Due to the space-saving arrangement of the device in the direction of gas flow with the radially flowing impeller arranged transversely with respect to the rotation axis and the transversely arranged generator, an expansion machine according to the invention can be constructed so compactly and compatible with conventional gas pressure regulators that it can be installed into a conventional gas pressure regulator with little effort, thereby enabling the continued use of essential components of the gas pressure regulator, such as the housing and the control device. For example,It is conceivable that the existing control mechanism of the gas pressure regulator could be used for a preferably passive control of the radial-flow expansion machine by partially pressurizing the expansion machine. In this case, the expansion machine essentially replaces the function of the conventional throttle valve in the gas pressure regulator, and the existing control of the gas pressure regulator then continues to ensure the preferably passive control with the aid of the device's metering device.

[0015] In another embodiment, however, it is also conceivable that the connection dimensions of the radial-flow expansion machine and / or the interfaces of the device to existing piping networks, in particular connection flanges or installation lengths, are designed to be compatible with conventional gas pressure regulators in such a way that the device is compatible with conventional gas pressure regulators in terms of installation and function, and the gas pressure regulators can be easily replaced without requiring significant modifications to the existing piping systems for the gas flow. This allows for a simple and economical replacement of existing gas pressure regulators with the device according to the invention, while also providing the option for energy recovery.

[0016] The invention further relates to a method for expanding pressurized gases transported in pipelines, preferably natural gas transported in pipelines, in which the gas to be expanded is expanded to a lower pressure in at least one expansion machine, the rotational energy of which is used to recover energy from the gas to be expanded in the form of technically usable work. Such a generic method is further developed in accordance with the invention by using at least one expansion machine, now with radial flow, for expanding high-pressure gases, the guide devices and radial impeller of which are arranged entirely within the section of the pipeline through which the gas to be expanded flows.

[0017] The essential advantages and properties of the method have already been explained above in connection with the device according to the invention, therefore reference is made in full to these explanations, which also apply to the method.

[0018] A particularly preferred embodiment of the device according to the invention is shown in the drawing.

[0019] They show: Fig. 1 - an embodiment of the device with an expansion machine with a radially flowing impeller, which is arranged perpendicular to the flow direction of a gas to be expanded in a pipe section and, in addition to the expansion function, drives a generator mechanically coupled to the impeller, shown in a closed position (zero closure) of a dosing device surrounding the impeller in a bell-like manner, Fig. 2 - a device according to Fig. 1 with a partial loading of the impeller by the gas volume flow with partially opened dosing device.

[0020] In the Fig. 1 shows an embodiment of the device 1 with an expansion machine 2 with a radially flowing impeller 11, which is arranged perpendicular to the flow direction 18 of a gas 7 to be expanded in a pipe section 12 and, in addition to the expansion function, drives a generator 3 mechanically coupled to the impeller 11, shown in a closed position (zero closure) of a dosing device 5 surrounding the impeller 11 like a bell. Instead of via the purely dissipative throttle point of a conventional gas pressure regulator, the required reduction of the applied pressure potential takes place via the integrated turbine stage(s) 2 with the dissipation of technically usable work.In this way, it is possible to (re)cover part of the internal energy contained in the gas volume flow 7, which was technically supplied, for example, during (natural) gas compression or as a result of process-related (pre-)heating, as well as energy that was transferred from the environment to the gas volume flow 7 (for example by means of geothermal energy).

[0021] The pipe section 12 can, if necessary, be dimensionally compatible with typical gas pressure regulators or be part of a converted gas pressure regulator and consists of the pipe section 12a for the gas volume flow 7 entering the device 1, the pipe section 12b for the gas volume flow 6 exiting the device 1 after expansion, as well as partition walls 13 and installation sections 14, 19, 20 for attachments. Approximately centrally in the pipe cross-section, a known radially flow impeller 11 of an expansion machine 2, such as a constant-pressure turbine, is arranged and rotatably mounted relative to installation sections 14 for attachments. Under the influence of the gas volume flow 7, the impeller rotates about an axis 21 perpendicular to the flow direction 18 of the gas volume flow 7.This shaft 15 of the impeller 11 arranged in this axis 21 is at the same time the mechanical coupling with a generator which, for the sake of simplicity, is designated here as a whole with the item number 3, whereby the generator 3 with shaft 15 and impeller 11 can be inserted into the interior of the pipeline 12 through corresponding lateral openings 17 in the area of ​​the installation sections 14 for attachment parts and can be fixed to the installation sections 14 in a manner not further specified.

[0022] The pressure between the high pressure area p HD with the pipe section 12a for the gas volume flow 7 entering the device 1 with the inflow area 9 and the low pressure area p ND The partition walls 13 arranged with the pipe section 12b for the gas volume flow 6 emerging from the device 1 after the expansion seal the two areas p HD and p NDfrom each other in such a way that the entire incoming gas volume flow 7 is deflected by the radially flowing impeller 11 of the expansion machine 2 and is also deflected approximately perpendicularly 10 to the flow direction 18 of the incoming gas volume flow 7 into the pipe section 12b for the gas volume flow 6 exiting the device 1 after expansion, where it is expanded. At the same time, the rotational energy of the impeller 11 during this expansion is used to drive the generator 3 arranged on the same shaft 15, which generates electricity in generator mode and can provide this electricity as energy recovered from the gas volume flow 7. The expanded gas volume flow 6 is then deflected again through the pipe walls 12c in the region of the generator 3 and again passed on in its original direction 16.

[0023] In the area of ​​the known guide devices 4 of the radially flowing impeller 11, a metering device 5 is arranged, which allows a partial admission of the impeller 11 with the gas volume flow 7 and thus an adjustment of the flow passage through the impeller 11. For this purpose, the metering device 5 has a hood 22 surrounding the impeller 11 in an approximately bell-shaped manner, which can be changed in its relative position to the impeller 11 in the adjustment direction 8 via an adjustment mechanism indicated as a control slide 6 and thus surrounds the impeller 11 to an adjustable extent. Fig. The position of the metering device 5 shown in Figure 1 shows the so-called zero closure, in which the hood 22 of the metering device 5 is pressed against the walls of the installation sections 14 in such a way that the hood 22 completely seals off the passage of gas volume flow 7 through the impeller 11 and no gas volume flow 7 from the high pressure side p HD to the low pressure side pND can reach. In the Fig. 2 shows a position of the hood 22 of the metering device 5 which allows a partial admission of the impeller 11 with a gas volume flow 7 and allows slightly more than half of the maximum possible gas volume flow 7 to pass through. In this position of the hood 22 of the metering device 5, the impeller 11 is set in rotation by the gas volume flow 7, whereby the impeller 11, on the one hand, expands the gas volume flow 7 and directs it to the low-pressure side p ND and on the other hand drives the generator 3, which thereby generates electricity and recovers part of the energy potential contained in the gas volume flow 7.

[0024] The device 1 according to the invention enables, for the first time, the direct integration of an expansion machine 2 into the gas pressure regulators that have been used for years in the (natural) gas distribution network and connected storage stations. At the same time, the existing control mechanism of the gas pressure regulators can thus also be used for the first time in parallel for passive control of the partial admission of the expansion machine 2 (passive = without external energy). In this way, a passively controllable, variably actuated, radial expansion machine 2, e.g., in the form of a (natural) gas expansion turbine including zero discharge, can be realized within already established control valves.

[0025] The radial (constant) pressure stage(s) integrated according to the invention, for example in a gas pressure regulator, result in the following advantages: All the advantages of (decentralized) energy recovery using an axial expansion machine 2 in the (natural) gas distribution network and the connected storage stations, already known according to the current state of the art, remain intact. In addition to the active control design known, for example, from DE 10 2022 104 835 A1, the application of the well-known passive control mechanism of common gas pressure regulators for operating point-dependent, adjusted partial loading of the impeller 11 and maintenance of the outlet pressure p NDpossible. The function of the gas pressure regulator therefore remains unchanged - while maintaining the control accuracy. At the same time, the applied pressure potential of the gas volume flow 7 is used to extract technically usable work from the gas volume flow 7 for energy (re)covery. Furthermore, thanks to the integration into the gas pressure regulators already on the market, the connection dimensions of device 1 (e.g., connection flanges, installation lengths) as well as the currently existing interfaces to existing pipeline networks remain unaffected. A simple replacement of device 1 or retrofitting of the existing gas pressure regulators with device 1 is therefore possible without any problems. This creates a simple and cost-effective way to increase the efficiency of the (natural) gas distribution network and the connected storage stations without complex conversion measures.

[0026] The invention was developed in the ZIM project “Development of a controlled gas expansion turbine for different load operations and for pressure control” (KK507221 0GM1), funded by the BMWI. Part number list 1 device 2 expansion machine 3 Generator 4 Guidance device 5 hood-like dosing device 6 adjusting slides 7 Gas 8 Direction of movement of the control slide 9 Inflow area, radial inflow to the impeller 10 radial outflow from impeller 11 Wheel 12 housings 12a Pipe section incoming gas 12b Pipe section relaxed gas 12c Pipe section in the generator area 13 Installation sections housing 14 Assembly sections housing 15 Shaft impeller / generator 16 Flow direction 17 Insertion opening installation sections housing 18 Inflow direction 19 Flange Generator 20 Flange control device 21 Rotation axis impeller 22 hood

Claims

[1] Device (1) for expansion under pressure (p HD ) of gases (7) transported in pipelines (12), preferably of natural gas (7) transported in pipelines, in which the gas (7) to be expanded is reduced to a lower pressure (p ND ), whereby the rotational energy of the expansion machine (2) can be used to recover energy from the gas (7) to be expanded in the form of technically usable work, characterized by that the device (1) has at least one radially flowed expansion machine (2) in the form of a radial constant pressure turbine, the guide devices (4) and radial impeller (11) of which are arranged completely within the section of the pipeline (12) through which the gas (7) to be expanded flows and through which the gas (7) to be expanded flows. [2] Device (1) according to claim 1, characterized bythat the rotational axis (21) of the radially flowing impeller (11) of the expansion machine (2) is arranged transversely, preferably at 90°, to the flow direction (18) of the gas (7) to be expanded in the flow-through pipe (12). [3] Device (1) according to one of claims 1 or 2, characterized by that the rotational energy of the radially flowing expansion machine (2) can be used in a generator (3) functionally coupled to the radially flowing expansion machine (2). [4] Device (1) according to one of the preceding claims, characterized by that a control device (5, 6) is provided which controls the volume flow of the gas (7) to be expanded through the expansion machine (2) and the pressure (p ND ) after flowing through the expansion machine (2). [5] Device (1) according to claim 4, characterized bythat the control device (5, 6) has a metering device (5) which adjustably influences the flow path of the gas to be expanded (7) through the impeller (11) of the expansion machine (2) and / or the flow cross-section of the gas to be expanded (7) towards the impeller (11) of the expansion machine (2) and controls the volume flow of the gas to be expanded (7) through the expansion machine (2). [6] Device (1) according to claim 5, characterized by that the metering device (5) is arranged in the region of the guide devices (4) of the impeller (11) of the expansion machine (2), preferably adjustably covering the inflow sections to the impeller (11). [7] Device (1) according to claim 6, characterized by that the metering device (5) is designed as a bell-shaped hood (22) surrounding the impeller (11) of the expansion machine (2), the position of which hood is adjustable relative to the impeller (11). [8] Device (1) according to one of claims 5 to 7, characterized by that the metering device (5) can be brought into a position which allows a zero closure of the impeller (11) for the complete suppression of the gas flow through the expansion machine (2). [9] Device (1) according to one of the preceding claims, characterized by that the radial flow expansion machine (2) can be integrated into a gas pressure regulator. [10] Device (1) according to claim 9, characterized by that the already existing control mechanism of the gas pressure regulator can be used for a preferably passive control of the radially flowing expansion machine (2) by partially loading the expansion machine (2). [11] Device (1) according to one of the preceding claims, characterized bythat the connection dimensions of the radial flow expansion machine (2) and / or the interfaces of the device (1) to existing pipeline networks (12), in particular connection flanges or installation lengths, are designed to be compatible with gas pressure regulators. [12] Device (1) according to one of claims 1 to 10, characterized by that gas pressure regulators are interchangeable with the device (1) with the radial flow expansion machine (2) and / or that a gas pressure regulator can be retrofitted with the radial flow expansion machine (2). [13] Process for expansion under pressure (P HD ) of gases (7) transported in pipelines (12), preferably of natural gas (7) transported in pipelines, in which the gas (7) to be expanded is reduced to a lower pressure (p ND), whereby the rotational energy of the expansion machine (2) is used to recover energy from the gas (7) to be expanded in the form of technically usable work, characterized by that for expansion under pressure (P HD ) standing gases (7), at least one radially flowed expansion machine (2) in the form of a radial constant pressure turbine is used, the guide devices (4) and radial impeller (11) of which are arranged completely within the section of the pipeline (12) through which the gas (7) to be expanded flows and through which the gas (7) to be expanded flows. [14] Method according to claim 13, characterized by that a control device (5, 6) controls the volume flow of the gas (7) to be expanded through the expansion machine (2) and the pressure (p ND ) after flowing through the expansion machine (2). [15] Method according to one of claims 13 or 14, characterized bythat the radial flow expansion machine (2) is integrated into a gas pressure regulator. [16] Method according to one of claims 13 or 14, characterized by that gas pressure regulators are replaced by the device (1) with the radial flow expansion machine (2) and / or a gas pressure regulator is retrofitted with the radial flow expansion machine (2).

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