A multistage wave rotor system as a device for cracking a gas
Patent Information
- Application Number
- AE202602518
- Authority / Receiving Office
- AE · AE
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2024-01-26
- Filing Date
- 2025-01-23
Smart Images
Figure ABST_ABST
Abstract
Description
A multistage wave rotor system as a device for cracking a gasDescriptionTECHNICAL FIELD[1] The present disclosure concerns a wave rotor system as a device for cracking a gas. Embodiments disclosed herein specifically concern a multistage wave rotor system wherein the pressure difference between a driver gas and a driven gas creates pressure waves to heat and to increase the pressure of the driven gas and crack at least a portion of the driven gas. More in particular, embodiments disclosed herein specifically concern a multistage wave rotor system wherein two or more stages are integral with each other.BACKGROUND ART[2] Thermal decomposition of a chemical compound to obtain simpler molecules is commonly used in the treatment of organic materials. This technology is known as pyrolysis or thermal cracking. In particular, cracking is the process whereby complex organic molecules such as long-chain hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon-carbon bonds in the precursors.[3] In particular, thermal decomposition of methane from natural gas is recently getting more and more importance as a technology to produce hydrogen, via decomposition of methane into carbon and hydrogen (CH4 + Heat → C + 2H2) with trace quantities of other hydrocarbons. This process (methane pyrolysis or methane cracking) is based on the heating of methane to temperatures in which the kinetics of the reaction produce high conversions in a reasonable time. The governing reaction is endothermic, thus the necessary energy input should be provided from an energy source. A main characteristic of this process is the absence of oxygen, which eliminates CO2 and CO by-products. Additionally, no water is consumed, and the produced carbon may have qualities that can be marketed and used in a variety of traditional and novel applications, or it can be securely stored for future use.[4] Recently, shock-wave compression has been proposed as an energy source or temperature multiplier for direct thermal methane decomposition [Akbari, P., Copeland, C. D., Tüchler, S., Davidson, M., and Mahmoodi-Jezeh, S. V, “Shock Wave Heating: A Novel Method for Low-Cost Hydrogen Production” ASME Paper IMECE2021-69775, 2021]. In this approach, a wave rotor [Akbari, P., Nalim, M. R., and Müller, N., “A Review of Wave Rotor Technology and Its Applications,” ASME Journal of Engineering for Gas Turbines and Power, Vol. 128, No. 4, 2006, pp. 707-735] is used to generate shock and rarefaction waves for exchanging energy between fluid streams. This technology is considered very promising in order to produce hydrogen without any undesirable by-product, such as in particular carbon dioxide. In particular, this technology is favorably applicable to produce hydrogen to be used as feedstock for a gas turbine operating as the driver of a compressor in a booster station for natural gas pipelines, in order to counteract the pressure drop of the natural gas along the pipeline [Pejman et al, “The Use of Wave Machinery for Power Generation and Production of Hydrogen as Gas Turbine Fuel”, AIAA Scitech Forum, 29 December 2021]. This solution allows the wave rotor to use a little fraction of the natural gas from the pipeline to produce hydrogen to be used as fuel for the gas turbine, by leveraging the pressure already present in the natural gas pipeline to use the natural gas as the driver gas of the wave rotor. At the same time, the low-pressure natural gas at the driver gas outlet of the wave rotor is sent back to the wave rotor as the driven gas, being heated up to the cracking temperature, to obtain hydrogen.[5] Wave Rotors, also known as Pressure Wave Machines or Pressure Exchangers, are unsteady-flow devices that can transfer energy directly between two fluids, by means of pressure waves (shock waves). In a wave rotor, two fluids with different pressures are brought into direct contact. Then pressure exchange occurs faster than mixing. The wave rotor can have a higher isentropic efficiency than steady-flow devices, like compressors or diffusers, but may be more challenging to control.[6] In particular, shock-wave compression can be used as an energy source or temperature multiplier for direct thermal decomposition. In this approach, a wave rotor is used to generate shock and rarefaction waves for exchanging energy between fluid streams. By way of example, this technology is considered very promising in order to produce hydrogen without any undesirable by-product, such as in particular carbon dioxide. In particular, this technology is favorably applicable to produce hydrogen to be used as feedstock for a gas turbine operating as the driver of a compressor in a booster station for natural gas pipelines, in order to counteract the pressure drop of the natural gas along the pipeline. This solution allows the wave rotor to use a little fraction of the natural gas from the pipeline to produce hydrogen to be used as fuel for the gas turbine, by leveraging the pressure already present in the natural gas pipeline to use the natural gas as the driver gas of the wave rotor. At the same time, the low-pressure natural gas at the driver gas outlet of the wave rotor is sent back to the wave rotor as the driven gas, being heated up to the cracking temperature, to obtain hydrogen.[7] More in general, the possibility of using wave rotors to increase the temperature of a gas up to its thermal decomposition can be applied to different kind of gases.[8] However, the use of wave rotors to heat a gas stream up to its decomposition temperature can still be improved in order to increase the reaction conversion rate, which is according to the prior art, still relatively low.[9] Therefore, there is a need for improved designs of a wave rotor based cracking system that can address these challenges and provide efficient and reliable performance in various industrial applications.
[10] Accordingly, an improved wave rotor based gas cracking system to address the issues of conversion rate of the systems of the current art would be beneficial and would be welcomed in the technology.SUMMARY
[11] In one aspect, the subject matter disclosed herein is directed to a multistage wave rotor system for thermal decomposition of a gas, the wave rotor system comprising at least two wave rotors in series, i.e. a first stage wave rotor and a second stage wave rotor wherein the driven gas from the driven gas outlet of the first stage wave rotor is directed to the driven gas inlet of the second stage wave rotor and wherein the driver gas from the driver gas outlet of the second stage wave rotor is directed to the driver gas inlet of the first stage wave rotor and wherein the pressure difference between a driver gas and a driven gas creates pressure waves to heat the driven gas and crack at least a portion of the driven gas. More in general, the wave rotor system comprises a first stage wave rotor, one or more last stage wave rotors and one or more intermediate stage wave rotors. In particular, by splitting the process into two or more stages, the mass of the driver gas needed to heat the driven gas is reduced, and also the power needed to recompress the driver gas is reduced.
[12] In another aspect, the subject matter disclosed herein concerns a wave rotor system wherein the first stage wave rotor can be a three-port wave rotor, in order to use a same gas stream at high-pressure as a driver gas to be split, inside the first stage wave rotor, into a driver gas outlet stream and a driven gas inlet stream. In particular, the driver gas outlet stream from the first stage wave rotor can be compressed and recirculated to the driver gas inlet of the at least one last stage wave rotor through a respective recirculation circuit.
[13] In one aspect, the subject matter disclosed herein concerns a wave rotor system wherein a plurality of wave rotors are connected in series and / or in parallel. When connected in parallel, more than one last stage wave rotor is present in the system.
[14] In another aspect, disclosed herein is a wave rotor system wherein the first stage wave rotor and / or the one or more last stage wave rotors and / or the one or more intermediate stage wave rotors are arranged on a same rotating body. In particular, according to this aspect, the wave rotor system comprises a rotating body including at least two groups of channels arranged along respective concentric cylindrical areas, around a rotating axis of the rotating body; and the ports of a first stage wave rotor being arranged at the bases of one of the concentric cylindrical areas and the ports of the one or more last stage wave rotors or of the one or more intermediate stage wave rotors being arranged at the bases of a respective different concentric cylindrical area.
[15] In still another aspect, at least one of the one or more wave rotors is coupled with an integrally geared rotating system. Preferably, the integrally geared rotating system comprises a gearbox, or a bull gear. In particular, a bull gear is used in case the speed ratio is greater than 7.BRIEF DESCRIPTION OF THE DRAWINGS
[16] 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 wave rotor system for cracking a gas, according to a first embodiment;Fig.2 illustrates a wave rotor system for cracking a gas, according to a second embodiment;Fig.3 illustrates a wave rotor system for cracking a gas, according to a third embodiment;Fig.4 illustrates a wave rotor system for cracking a gas, according to a fourth embodiment;Fig.5 illustrates a wave rotor system for cracking a gas, according to a fifth embodiment;Fig.6 illustrates a first wave rotor arrangement for a wave rotor system for cracking a gas, according to a sixth embodiment;Fig. 7 illustrates a second wave rotor arrangement for a wave rotor system for cracking a gas, according to a seventh embodiment, andFig. 8 illustrates a wave rotor for a wave rotor system for cracking a gas, according to a eighth embodiment.DETAILED DESCRIPTION OF EMBODIMENTS
[17] According to one aspect, the present subject matter is directed to a wave rotor system for cracking a gas, the wave rotor system comprising at least two wave rotors, wherein the pressure difference between a driver gas and a driven gas creates pressure waves to heat and to increase the pressure of the driven gas and crack at least a portion of the driven gas, the system includingone first stage wave rotor and one or more last stage wave rotors, the driven gas flowing from the first stage wave rotor to the one or more last stage wave rotors, defining a downstream direction, the driver gas flowing from the one or more last stage wave rotors to the first stage wave rotor;the first stage wave rotor being a three-port wave rotor or a four port wave rotor and each one of the one or more last stage wave rotors being a four-port wave rotor;the first stage wave rotor comprising one driver gas inlet port and two outlet ports, namely a driver gas outlet port and a driven gas outlet port,each one of the one or more last stage wave rotors comprising two inlet ports, namely a driven gas inlet port and a driver gas inlet port and two outlet ports, namely a driven gas outlet port and a driver gas outlet port;the driver gas inlet port of each one of the one or more last stage wave rotors being connected to a high-pressure gas feedstock through a high-pressure feed line;the driven gas outlet port of each one of the one or more last stage wave rotors being connected to external users.
[18] Reference now will be 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.
[19] When introducing 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 inclusive and mean that there may be additional elements other than the listed elements.
[20] Referring now to the drawings, Fig.1 shows a schematic of an exemplary multistage wave rotor system for cracking a gas according to the present disclosure, the wave rotor system comprising a first stage wave rotor 10 and a second stage wave rotor 20, the second stage wave rotor being connected to an external source of a gas to be cracked, at a high-pressure, through a high-pressure gas feed line 30. The first stage wave rotor 10 according to this exemplary configuration is a three-port wave rotor, including a driver gas inlet 11, a driver gas outlet 12 and a driven gas outlet 13. Inside the wave rotor 10, the exhausted driver gas is split and is directed partly to the driver gas outlet 12 and partly used as driven gas. The second stage wave rotor 20 according to this exemplary configuration is a four-port wave rotor, including a driven gas inlet 21, a driver gas inlet 22, a driven gas outlet 23 and a driver gas outlet 24. The driver gas inlet 22 of the second stage wave rotor 20 is connected to the high-pressure gas feed line 30. The driven gas outlet 13 of the first stage wave rotor 10 is connected to the driven gas inlet 21 of the second stage wave rotor 20, and the driver gas outlet 24 of the second stage wave rotor 20 is connected to the driver gas inlet 11 of the first stage wave rotor 10. Finally, the driven gas outlet 23 of the second stage wave rotor 20 is connected to external users. The rotation of the wave rotors can be provided by external means, such as a motor (not shown) or by internal means using the pressure of the driver gas on appropriately shaped channels. Advantageously, the first stage wave rotor 10 and the second stage wave rotor 20 can share a common shaft. Inside the channels of the wave rotors shock and rarefaction waves are generated for exchanging energy between fluid streams, with generation of heat. By way of example, ammonia or methane are fed to the wave rotor to react and produce hydrogen according to the following reactions: NH3 N2 + H2 ΔH = 46,4 kJ / mol CH4 C(S) + 2H2 ΔH = 74,6 kJ / mol
[21] This technology is considered very interesting to produce hydrogen because it allows avoiding the production of carbon dioxide as a by-product or as a result of a combustion reaction used to generate heat to be provided to the pyrolysis reaction. In fact, heat necessary to the reaction is provided by the shock waves. Hydrogen production yield is improved by the catalyst and the short residence time caused by the rapid heating and temperature rise of the gas mixture inside the wave rotor. Moreover, the wave rotor system of the present disclosure allows for easy startup and shutdown procedures without extensive pretreatment. In addition to the production of hydrogen, this technology can also be used to obtain different kind of compounds, such as olefins.
[22] Still with reference to Fig. 1, the driver gas outlet 12 of the first stage wave rotor 10 is connected to the driver gas inlet 22 of the second stage wave rotor 20 through a recirculation circuit 40. A plurality of devices are provided along the recirculation circuit 40 to compress and heat the exhausted driver gas from the driver gas outlet 12 of the first stage wave rotor 10, including compressors 41, heat exchangers 42 and intercoolers 43. One or more additional heaters 44 are present along the connection between the driver gas inlet 22 of the second stage wave rotor 20 and the high-pressure gas feed line 30. A by-pass line 25 connects the driver gas outlet 24 of the second stage 20 to the recirculation line 40. In particular, the by-pass line 25 is connected to the recirculation line 40 downstream a compressor 41, configured to compress the exhausted driver gas from the driver gas outlet 12 of the first stage wave rotor 10 at the same pressure of the driver gas at the driver gas outlet 24 of the second stage 20.
[23] The system operates as follows. High-pressure gas (driver gas) comes from a high-pressure source through the high-pressure gas feed line 30. It enters the channels of the second stage wave rotor 20, where it is exhausted to an intermediate pressure and then supplied to the first stage wave rotor 10 as a driver gas. This gas is exhausted to a low pressure. Some driver gas leaves the first stage wave rotor 10, is compressed by the compressors 41 and mixed with the high-pressure driver gas of the high-pressure gas feed line 30, to be re-used in the second stage wave rotor 20. The remaining gas fills the channels of the first stage wave rotor 10 as the driven gas. This way, the first stage wave rotor 10 being a three-port wave rotor 10; there is no need for a separate source of driven gas, since part of the exhausted driver gas from the first stage wave rotor is used as the driven gas.
[24] Inside the first stage wave rotor 10, the driven gas is pressurized by the driver gas coming from the second stage wave rotor 20 at an intermediate pressure. The partly pressurized and heated driven gas is sent into the channels of the second stage wave rotor 20 where it is further pressurized and heated by the high-pressure driver gas coming from the external high-pressure source. The driven gas exits the channels of the second stage wave rotor 20 at a high-pressure and temperature. The second stage wave rotor 20 is a four-port wave rotor taking in driven gas at an intermediate pressure and temperature and driver gas at a high-pressure and exhausting intermediate pressure driver gas to obtain driven gas at high-pressure and high temperature. In particular, the temperature can be high enough to pyrolyze at least part of the driven gas and obtain gas cracking products.
[25] The driven gas total pressure cannot increase beyond the total pressure of the high-pressure driver gas. However, with regard to temperature, conversion of pressure energy to temperature (via a shock wave) ensures that driven gas total temperatures can be higher than driver gas total temperatures. Because the aim of the wave rotor is to generate heat necessary for the cracking reaction, what are considered losses due to heat (increasing entropy) are beneficial for this system.
[26] The by-pass line 25 is used in the event of extra driver gas flow at intermediate pressures. It allows the operator to reduce the driver flow to stage 1 and recycle the gas back to stage 2.
[27] Several embodiments of possible wave rotor system arrangements will be described below with reference to the following Figs 2, 3, 4, 5, 6, 7 and 8.
[28] In particular, with continuing reference to Fig.1, Fig.2 illustrates a second embodiment of a wave rotor system of the present disclosure. In Fig. 2, the same reference numbers designate the same or corresponding parts, elements or components already illustrated in Fig.1 and described above, and which will not be described again. According to this exemplary embodiment a three-stage wave rotor system is provided. The three-stage wave rotor system of Fig. 2 differs from the one already disclosed with reference to Fig. 1 mainly in that an intermediate stage 20i is arranged amongst the first stage wave rotor 10 and a last stage wave rotor 20, corresponding to the second stage wave rotor 20 already shown with reference to Fig.1. The first stage wave rotor 10 according to this exemplary configuration is still a three-port wave rotor, with a driver gas inlet 11, a driver gas outlet 12 and a driven gas outlet 13. The intermediate stage wave rotor 20i and the last stage wave rotor 20 according to this exemplary configuration are four-port wave rotors, the intermediate stage wave rotor 20i including a respective intermediate stage driven gas inlet 21i, intermediate stage driver gas inlet 22i, intermediate stage driven gas outlet 23i and intermediate stage driver gas outlet 24i and the last stage wave rotor 20 including a respective last stage driven gas inlet 21, last stage driver gas inlet 22, last stage driven gas outlet 23 and last stage driver gas outlet 24. The last stage driver gas inlet 22 of the last stage wave rotor 20 is connected to the high-pressure gas feed line 30, the intermediate stage driver gas inlet 22i of the intermediate stage wave rotor 20i is connected to the last stage driver gas outlet 24 of the last stage wave rotor 20 and the first stage driver gas inlet 11 of the first stage wave rotor 10 is connected to the intermediate stage driver gas outlet 24i of the intermediate stage wave rotor 20i. On the other hand, the driven gas outlet 13 of the first stage wave rotor 10 is connected to the intermediate stage driven gas inlet 21i of the intermediate stage wave rotor 20i, and the intermediate stage driven gas outlet 23i of the intermediate stage wave rotor 20i is connected to the last stage driven gas inlet 21 of the last stage wave rotor 20. Finally, the last stage driven gas outlet 23 of the last stage wave rotor 20 is connected to external users. As already disclosed with reference to the exemplary embodiments shown with reference to Fig.1, the driver gas outlet 12 of the first stage wave rotor 10 is connected to the driver gas inlet 22 of the second stage wave rotor 20 through a recirculation circuit 40. A plurality of devices (not shown in Fig.2) are provided along the recirculation circuit 40 to compress and heat the exhausted driver gas from the driver gas outlet 12 of the first stage wave rotor 10, including compressors, heat exchangers and intercoolers. Two by-pass lines 25 respectively connect the driver gas outlet 24 of the last stage 20 and the driver gas outlet 24i of the intermediate stage 20i to the recirculation line 40, downstream a respective compressor 41.
[29] The rotation of the wave rotors can be provided by external means, such as a motor (not shown). Advantageously, the first stage wave rotor 10, the intermediate stage wave rotor 20i and / or the last stage wave rotor 20 share a common shaft. It is also possible to driver the wave rotor using the pressure energy of the driver gas on specially shaped channels (not shown).
[30] The splitting of the process into two stages (or multiple stages) allows to reduce the mass of the driver gas needed to heat the driven gas. This reduces the power needed to recompress the driver gas.
[31] These results are summarized by the following tables 1 and 2, comparing a single stage wave rotor system, a two-stage wave rotor system and a three-stage wave rotor system.Table 1 Stage Mass ratio (% of Single stage mass) TotalSingle stage wave rotor system100.00 100.00Two-stage wave rotor system15.7618.95 34.71Three stage wave rotor system9.1110.1911.2230.52This is the driver to driven mass ratio as a percentage of single stage mass driver to driven mass ratio.Wherein the total mass ratio expresses the ratio between the mass of the driver gas needed to pressurize and heat a fixed amount of driven gas up to the cracking temperature.Table 2. Power needed to recompress the exhausted driver gas Single stage wave rotor systemTwo-stage wave rotor systemThree-stage wave rotor systemWcomp (%)100.0017.117.72Wheater (%)100.008.802.85Similarly, the power consumed for heating and compression as a percentage of the power for heating and compression for a single stage wave rotor.
[32] With continuing reference to Figs 1 and 2, a further embodiment of a wave rotor system is shown in Fig.3. The same reference numbers designate the same or corresponding parts, elements or components already illustrated in Fig.2 and described above, and which will not be described again. The wave rotor system of Fig.3 differs from the wave rotor system of Fig.2 mainly in that three intermediate stages 20i, 20ii, 20iii are arranged amongst the first stage wave rotor 10 and a last stage wave rotor 20. The first stage wave rotor 10 according to this exemplary configuration is still a three-port wave rotor, with a driver gas inlet 11, a driver gas outlet 12 and a driven gas outlet 13. The three intermediate stage wave rotors 20i, 20ii and 20iii and the last stage wave rotor 20 according to this exemplary configuration are four-port wave rotors, the intermediate stage wave rotors 20i, 20ii, 20iii including respective intermediate stage driven gas inlets 21i, 21ii, 21iii, intermediate stage driver gas inlets 22i, 22ii, 22iii, intermediate stage driven gas outlet 23i, 23ii, 23iii and intermediate stage driver gas outlets 24i, 24ii, 24iii and the last stage wave rotor 20 including a respective last stage driven gas inlet 21, last stage driver gas inlet 22, last stage driven gas outlet 23 and last stage driver gas outlet 24. On the side of the driver gas, the last stage driver gas inlet 22 of the last stage wave rotor 20 is connected to the high-pressure gas feed line 30, the third intermediate stage driver gas inlet 22iii of the third intermediate stage wave rotor 20iii is connected to the last stage driver gas outlet 24 of the last stage wave rotor 20, the second intermediate stage driver gas inlet 22ii of the second intermediate stage wave rotor 20ii is connected to the third stage driver gas outlet 24iii of the third stage wave rotor 20iii, the first intermediate stage driver gas inlet 22i of the first intermediate stage wave rotor 20i is connected to the second stage driver gas outlet 24ii of the second stage wave rotor 20ii and the first stage driver gas inlet 11 of the first stage wave rotor 10 is connected to the first intermediate stage driver gas outlet 24i of the first intermediate stage wave rotor 20i. On the side of the driven gas, the driven gas outlet 13 of the first stage wave rotor 10 is connected to the first intermediate stage driven gas inlet 21i of the first intermediate stage wave rotor 20i, the first intermediate stage driven gas outlet 23i of the first intermediate stage wave rotor 20i is connected to the second intermediate stage driven gas inlet 21ii of the second intermediate stage wave rotor 20ii, the second intermediate stage driven gas outlet 23ii of the second intermediate stage wave rotor 20ii is connected to the third intermediate stage driven gas inlet 21iii of the third intermediate stage wave rotor 20iii and the third intermediate stage driven gas outlet 23iii of the third intermediate stage wave rotor 20iii is connected to the last stage driven gas inlet 21 of the last stage wave rotor 20. Finally, the last stage driven gas outlet 23 of the last stage wave rotor 20 is connected to external users. The driver gas outlet 12 of the first stage wave rotor 10 is connected to the driver gas inlet 22 of the last stage wave rotor 20 through a recirculation circuit 40. A plurality of devices (not shown) are provided along the recirculation circuit 40 to compress and heat the exhausted driver gas from the driver gas outlet 12 of the first stage wave rotor 10, including compressors, heat exchangers and intercoolers. By-pass lines 25i, 25ii, 25iii, 25 respectively connect the driver gas outlet 24i of the first intermediate stage 20i, the driver gas outlet 24ii of the second intermediate stage 20ii, the driver gas outlet 24iii of the third intermediate stage 20iii and the driver gas outlet 24 of the last stage 20 to the recirculation line 40. The rotation of the wave rotors can be provided by external means, such as a motor (not shown). Advantageously, the first stage wave rotor 10, one or more of the intermediate stage wave rotors 20i, 20ii, 20iii and / or the last stage wave rotor 20 share a common shaft.
[33] With continuing reference to Figs.1, 2 and 3, a further embodiment of a wave rotor system is shown in Fig.4. The same reference numbers designate the same or corresponding parts, elements or components already illustrated in Figs.1, 2 and 3 and described above, and which will not be described again. The wave rotor system of Fig.4 differs from the wave rotor systems of Figs.1, 2 and 3 mainly in that the first stage wave rotor 10 is connected in parallel to two second stage wave rotors 20a and 20b, herein after designated as first parallel last stage wave rotor 20a and second parallel last stage wave rotor 20b. The first stage wave rotor 10 according to this exemplary configuration is still a three-port wave rotor, with a driver gas inlet 11, a driver gas outlet 12 and a driven gas outlet 13. The first parallel last stage wave rotor 20a and the second parallel last stage wave rotor 20b according to this exemplary configuration are both four-port wave rotors, including respective driven gas inlets 21a, 21b, driver gas inlets 22a, 22b, driven gas outlets 23a, 23b and driver gas outlets 24a, 24b. On the side of the driver gas, the driver gas inlet 22a of the first parallel last stage wave rotor 20a and the driver gas inlet 22b of the second parallel last stage wave rotor 20b are both connected to a high-pressure gas feed stock through respective high-pressure gas feed lines 30a, 30b; and the driver gas outlet 24a of the first parallel last stage wave rotor 20a and the driver gas outlet 24b of the second parallel last stage wave rotor 20b are both connected to the driver gas inlet 11 of the first stage wave rotor 10. On the side of the driven gas, the driven gas outlet 13 of the first stage wave rotor 10 is split into a driven gas inlet 21a of the first parallel last stage wave rotor 20a and a driven gas inlet 21b of the second parallel last stage wave rotor 20b. Finally, both the driven gas outlet 23a of the first parallel last stage wave rotor 20a and the driven gas outlet 23b of the second parallel last stage wave rotor 20b are connected to external users. The driver gas outlet 12 of the first stage wave rotor 10 is split into two recirculation circuits, namely a first parallel recirculation circuit 40a connected to the driver gas inlet 22a of the first parallel last stage wave rotor 20a and a second parallel recirculation circuit 40b connected to the driver gas inlet 22b of the second parallel last stage wave rotor 20b. A plurality of devices (not shown) are provided along the parallel recirculation circuits 40a, 40b to compress and heat the exhausted driver gas from the driver gas outlet 12 of the first stage wave rotor 10, the devices including compressors, heat exchangers and intercoolers. By-pass lines 25a, 25b respectively connect the driver gas outlet 24a of the first parallel last stage 20a and the driver gas outlet 24b of the second parallel last stage 20b to the respective recirculation lines 40a, 40b. The rotation of the wave rotors can be provided by external means, such as a motor (not shown). Advantageously, the first stage wave rotor 10 and one or both the parallel last stage wave rotors 20a, 20b share a common shaft.
[34] With continuing reference to Figs.1, 2, 3 and 4, a further embodiment of a wave rotor system is shown in Fig.5. The same reference numbers designate the same or corresponding parts, elements or components already illustrated in Figs.1, 2, 3 and 4 and described above, and which will not be described again. The wave rotor system of Fig.5 differs from the wave rotor systems of Fig.4 mainly in that intermediate stage wave rotors are present between the first stage wave rotor 10 and both the two parallel last stage wave rotors 20a and 20b. The first stage wave rotor 10 according to this exemplary configuration is still a three-port wave rotor, with a driver gas inlet 11, a driver gas outlet 12 and a driven gas outlet 13. The first parallel first intermediate stage wave rotor 10a is also a three-port wave rotor, with a driver gas inlet 11a, a driver gas outlet 12a and a driven gas outlet 13a, while the first parallel second intermediate stage wave rotor 20ai and the first parallel last stage wave rotor 20a, the second parallel first intermediate stage wave rotor 20bi, the second parallel second intermediate stage wave rotor 20bii and the second parallel last stage wave rotor 20b according to this exemplary configuration are four-port wave rotors. Inside the first parallel first intermediate stage wave rotor 10a, the exhausted driver gas is split and is directed partly to the driver gas outlet 12a and partly used as driven gas, which is sent to the first parallel second intermediate wave rotor 20ai. The exhausted driver gas from the first parallel first intermediate stage wave rotor 10a is mixed together with the exhausted driver gas from the first stage wave rotor 10 and recirculated through the recirculation line 40a to the first parallel last stage wave rotor 20a.
[35] With continuing reference to Figs.1, 2, 3, 4 and 5, a further embodiment of a wave rotor system is shown in Fig.6. The same reference numbers designate the same or corresponding parts, elements or components already illustrated in Figs.1, 2, 3, 4 and 5 and described above, and which will not be described again. The wave rotor system of Fig.6 shows a perspective view of the first stage wave rotor 10 and the second stage wave rotor 20 of the two-stage wave rotor system of Fig.1, the respective ports 11, 12, 13; 21, 22, 23, 24, the conduit connecting the driven gas outlet 13 of the first stage wave rotor 10 with the driven gas inlet 21 of the second stage wave rotor 20 and the conduit connecting the driver gas outlet 24 of the second stage wave rotor 20 with the driver gas inlet 11 of the first stage wave rotor 10.
[36] With continuing reference to Figs.1, 2, 3, 4, 5 and 6, a further embodiment of a wave rotor system is shown in Fig.7. The same reference numbers designate the same or corresponding parts, elements or components already illustrated in Figs.1, 2, 3, 4, 5 and 6 and described above, and which will not be described again. The wave rotor system of Fig.7 differs from the one already disclosed with reference to Fig. 6 mainly in that the first stage wave rotor 10 and the second stage wave rotor 20 share a common shaft 50.
[37] With continuing reference to Figs.1, 2, 3, 4, 5, 6 and 7, a further embodiment of a wave rotor system is shown in Fig.8. The same reference numbers designate the same or corresponding parts, elements or components already illustrated in Figs.1, 2, 3, 4, 5, 6 and 7 and described above, and which will not be described again. The wave rotor system of Fig.8 differs from the ones already disclosed with reference to Figs. 6 and 7 mainly in that the first stage wave rotor and the second stage wave rotor are arranged on a same cylindrical rotating body 60. In particular, two groups of channels 70, 80 are arranged along respective concentric cylindrical areas, around a rotating axis of the same rotating body 60. Two plates 90 are arranged at the two bases of the cylindrical rotating body 60. The plates 90 are represented at a distance from the rotating body 60, but they are in close proximity to the rotating body 60, in order to close the extremities of the two groups of channels 70, 80. The plates 90 comprise ports for the passage of a fluid to or from the channels 70, 80. In particular a port 11 is arranged on the plate 90 on a first basis of the rotating body 60, in correspondence of the cylindrical area of the channels 70, while two ports 12, 13 are arranged on the plate 90 on a second basis of the rotating body 60, always in correspondence of the cylindrical area of the channels 70 of the rotating body 60. Moreover, two ports 23, 24 are arranged on the plate 90 on the first basis of the rotating body 60, in correspondence of the cylindrical area of the channels 80, while two ports 21, 22 are arranged on the plate 90 on a second basis of the rotating body 60, always in correspondence of the cylindrical area of the channels 80 of the rotating body 60. As a consequence, the channels 70, 80 of each cylindrical area sequentially aligning with the respective ports as the cylindrical body 60 rotates about the rotation axis. The ports 11, 12, 13, 21, 22, 24 can be connected as already described above, so that the channels 70 of the rotating body are configured to operate as a first stage wave rotor with a driver gas inlet 11, a driver gas outlet 12 and a driven gas outlet 13, while the channels 80 of the rotating body are configured to operate as a second stage wave rotor with a driven gas inlet 21, a driver gas inlet 22, a driven gas outlet 23 and a driver gas outlet 24. Alternatively, the cylindrical body is fix and the plates rotate so that the channels 70, 80 of each cylindrical area sequentially align with the respective ports of the plates.
[38] While aspects of the invention has been described in terms of various specific embodiments, it will be apparent to those of ordinary skill in the art that many modifications, changes, and omissions are possible without departing 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.
Claims
1. A wave rotor system for cracking a gas, the wave rotor system comprising two or more wave rotors (10, 20; 20i, 20ii, 20iii; 20a, 20b; 10a, 20ai; 20bi, 20bii), wherein the pressure difference between a driver gas and a driven gas creates pressure waves to heat and to increase the pressure and temperature of the driven gas and crack at least a portion of the driven gas, the system including%2. one first stage wave rotor (10) and one or more last stage wave rotors (20; 20a, 20b), the driven gas flowing from the first stage wave rotor (10) to the one or more last stage wave rotors (20; 20ii), defining a downstream direction, the driver gas flowing from the one or more last stage wave rotors (20; 20ii) to the first stage wave rotor (10);%2. the first stage wave rotor (10) being a three-port wave rotor (10) or a four port wave rotor and each one of the one or more last stage wave rotors (20; 20ii) being a four-port wave rotor (20; 20ii);%2. the first stage wave rotor (10) comprising one driver gas inlet port (11) and two outlet ports, namely a driver gas outlet port (12) and a driven gas outlet port (13),%2. each one of the one or more last stage wave rotors (20i; 20ii) comprising two inlet ports, namely a driven gas inlet port (21; 21ii) and a driver gas inlet port (22; 22ii) and two outlet ports, namely a driven gas outlet port (23; 23ii) and a driver gas outlet port (24; 24ii); %2. the driver gas inlet port (22; 22ii) of each one of the one or more last stage wave rotors (20; 20ii) being connected to a high-pressure gas feedstock through a high-pressure feed line (30);%2. the driven gas outlet port (23; 23ii) of each of the one or more last stage wave rotors (20; 20ii) being connected to external users .
2. The wave rotor system of claim 1, wherein the first stage wave rotor (10) is a three-port wave rotor (10).
3. The wave rotor system of claim 1, wherein the first stage wave rotor is a four-port wave rotor and comprises a driven gas inlet port.
4. The wave rotor system of any one of the preceding claims, wherein the driver gas outlet port (12) of the first stage wave rotor (10) is connected to the driver gas inlet port (22; 22ii) of each of the one or more last stage wave rotors (20; 20ii) through a respective recirculation circuit (40).
5. The wave rotor system of claim 4, wherein the recirculation circuit (40) includes one or more compressors (41), one or more heat exchangers (42), and one or more intercoolers (43).
6. The wave rotor system of any one of the preceding claims, wherein the system comprises two or more last stage wave rotors (20; 20a, 20b), %2. the driven gas flowing from the first stage wave rotor (10) to each one of the two or more last stage wave rotors (20; 20a, 20b), the driver gas flowing from each one of the two or more last stage wave rotors (20; 20a, 20b) to the first stage wave rotor (10);%2. the driver gas inlet port (22; 22a, 22b) of each one of the two or more last stage wave rotors (20; 20a, 20b) being connected to a high-pressure gas feedstock through a respective high-pressure feed line (30);%2. the driven gas outlet port (23; 23a, 23b) of each one of the two or more last stage wave rotors (20; 20a, 20b) being connected to external users.
7. The wave rotor system of any one of the preceding claims, wherein the wave rotor system comprises at least one intermediate stage wave rotor (20i, 20ii, 20iii; 10a, 20ai, 20bi, 20bii).
8. The wave rotor system of claim 7, wherein the intermediate stage wave rotor (20i, 20ii, 20iii; 20ai, 20bi, 20bii) is a four-port wave rotor (20i), connected downstream to a respective last stage wave rotor (20; 20a, 20b) or to another four port intermediate stage wave rotor (20ii, 20iii; 20ai, 20bi, 20bii) and connected upstream to the first stage wave rotor (10) or to another four port intermediate stage wave rotor (20i, 20ii; 20bi).
9. The wave rotor system of claim 7, wherein two or more last stage wave rotors (20a, 20b) are present and one or more intermediate stage wave rotors are three-port wave rotors (10a) connected downstream to a respective last stage wave rotor (20a) or to a four port intermediate stage wave rotor (20ai) provided the first stage wave rotor (10) and at least one last stage wave rotor (20a, 20b) are connected through one or more four-port intermediate stage wave rotors (20ai).
10. The wave rotor system of any one of the preceding claims, wherein a heater (44) is provided between the driver gas inlet port (22; 22ii) of the at least one last stage wave rotor (20; 20ii) and the high-pressure feed line (30).
11. The wave rotor system of claim 6, wherein the recirculation circuit (40) includes one or more compressors (41), one or more heat exchangers (42, 42i), and one or more intercoolers (43).
12. The wave rotor system of any one of the previous claims, wherein at least one wave rotor (10, 20; 20i, 20ii) comprises a shaft connected to a driving rotating machine configured to alternatively rotate the channels or the ports of the wave rotor (10, 20; 20i, 20ii) around the wave rotor axis.
13. The wave rotor system of any one of the previous claims, wherein two or more wave rotors (10, 20; 20i, 20ii) are connected through a same shaft (50).
14. The wave rotor system of any one of the previous claims, wherein the first stage wave rotor and / or the at least one last stage wave rotor and / or the at least one intermediate stage wave rotor are arranged concentrically around the same rotating axis.
15. The wave rotor system of claims 14, wherein the first stage wave rotor and / or the at least one last stage wave rotor and / or the at least one intermediate stage wave rotor are integral to each other.
16. The wave rotor system of claims 15, wherein the first stage wave rotor and / or the at least one last stage wave rotor and / or the at least one intermediate stage wave rotor are arranged on a same rotating body (60).
17. The wave rotor system of claim 16, whereinthe rotating body (60) comprises at least two groups of channels (7070, 8080) arranged along respective concentric cylindrical areas, around a rotating axis of the rotating body (60);the ports (11, 12, 13) of the first stage wave rotor being arranged at the bases of one of the concentric cylindrical areas and the ports (21, 22, 23, 24) of the at least one last stage wave rotor or of the at least one intermediate stage wave rotor being arranged at the bases of a respective different concentric cylindrical area7080.
18. The wave rotor system of any of the preceding claims, wherein at least one of the one or more wave rotors is coupled with one or more compressors.
19. The wave rotor system of claim 18, wherein the at least one of the one or more wave rotors is coupled with at least one of the one or more compressors through a common shaft.
20. The wave rotor system of claim 18 or 19, wherein the at least one of the one or more wave rotors is coupled with an integrally geared rotating system.
21. The wave rotor system of claim 20, wherein the integrally geared rotating system comprises a gearbox.
22. The wave rotor system of claim 20 or 21, wherein the integrally geared rotating system comprises a bull gear.
23. The wave rotor system of any of claims 20-22, wherein the compressor coupled with the integrally geared rotating system is an overhung-impeller centrifugal compressor system.