Systems and methods for producing gas hydrates

Abstract

A system for producing gas hydrates starting from an unpurified water stream, such as waste water or brine, in particular seawater. The system includes a multi-phase multi-stage pump that receives an unpurified water stream at a primary inlet at a first stage of the pump and a gaseous substance that forms hydrates at a secondary inlet at an intermediate stage of the pump. The pump is configured to increase the pressure of the fluid and deliver the pressurized fluid to a reactor configured to generate a gas hydrate starting from the pressurized fluid. The reactor is configured to deliver a fluid containing gas hydrate, unreacted material, and / or water to a separator having at least two outlets: a first (primary) outlet outputting the gas hydrate, and a second (secondary) outlet fluidly coupled to the secondary inlet and outputting the unreacted material and / or water. The inventive system as described above can be implemented in different equipment and can be used for producing purified water and / or purified gas or for energy storage in the form of gas hydrate particles.

Description

[0001] manual Technical Field

[0002] The subject matter disclosed herein relates to systems and methods for producing gas hydrates; depending on the embodiment, one or more hydrates can be produced simultaneously. Such systems and methods can have several applications, some of which are disclosed herein; such systems can be part of different devices. They can be used for energy storage in the form of gas hydrate particles, or for material purification, i.e. gas purification and / or water purification, in particular water desalination. Background Art

[0003] Desalination is a known technology for water treatment, in particular for seawater or wastewater. Desalination is a process that involves separating the salts dissolved in water from the solvent, thereby producing pure water.

[0004] It is known (although less common) that desalination can be performed through hydrate formation, which are crystalline, ice-like structures that can store methane or other gases (such as hydrogen, carbon dioxide, etc.). Pure water and gas form hydrates, excluding the salts present in the water. The result of desalination is solid hydrate crystals with gas trapped inside and concentrated brine, which is a highly concentrated solution of salt (e.g., NaCl) in water (H2O). After separation from the brine, the solid hydrate crystals produce pure water when they decompose. In fact, the density of gas hydrates is roughly equivalent to that of ice. Therefore, gas hydrates will usually float above the water surface and may be easily separated from it.

[0005] Generally speaking, four components are required to form gas hydrates: water, one or more hydrate-forming substances (e.g., hydrocarbons, particularly light hydrocarbons, or mixtures of hydrocarbons), low temperature, and high pressure. The formation of gas hydrates is usually carried out in a reactor, in which a high-pressure water stream and a high-pressure gas stream are fed. Therefore, conventional gas hydrate systems have separate pumps and compressors to increase the pressure of the fluids fed to the reactor, and the operating pressure depends on the type of hydrate to be formed and the nature of the gas.

[0006] From the article "Development of a novel hydrate-based refrigeration system: A preliminary overview" by Ogawa et al. a closed cycle refrigeration system based on hydrates is known in order to improve conventional vapor compression refrigeration systems. In the proposed system, a gas / liquid mixture forms a hydrate so that the heat released by the exothermic formation of the hydrate can be removed by an ambient fluid (such as atmospheric air). According to the proposed system, gas and water are provided at the inlet of a multiphase compressor and compressed by the multiphase compressor (i.e. a turbine that works efficiently at a low water / gas ratio). Furthermore, according to the proposed system, the gas / liquid mixture is used as a working medium and is maintained within the system (see Figure 1 ).

[0007] A system for producing gas hydrates using a multiphase pump (which can operate at a higher water / gas ratio than a compressor and can therefore mix the clathrate-forming fluids more effectively) is known from document DE 10 2009 051 277 A1. According to this solution, the clathrate-forming fluids are mixed with one another before they are supplied together to the suction side of the multiphase pump (see e.g. Figure 1 of stream 1, stream 2 and stream 3). Summary of the invention

[0008] It is desirable to have a gas hydrate production system that is more efficient (e.g., with enhanced hydrate formation) than known systems. In addition, it is desirable to have a gas hydrate production system that can be easily integrated into or combined with an apparatus (such as an energy storage apparatus or a water purification apparatus or a gas purification apparatus or an LNG apparatus).

[0009] According to one aspect, the subject matter disclosed herein relates to a system for producing gas hydrates, the system comprising a multiphase multistage pump having: a main pump inlet, the main pump inlet being configured to receive and deliver a first fluid to an initial stage of the pump, the first fluid comprising liquid water (at ambient pressure or pre-pressurization); at least one secondary pump inlet, the at least one secondary pump inlet being configured to receive and deliver a second fluid to an intermediate stage of the pump, the second fluid comprising a gaseous substance that forms the hydrate (at a pressure above ambient pressure, or generally at a pressure above the pressure of the first fluid at the main pump inlet); and a pump outlet, the pump outlet being configured to deliver a third fluid, the third fluid comprising the water and the substance that forms the hydrate at a predetermined pressure higher than the pressure of the water at ambient pressure or pre-pressurization. The system also comprises a reactor having a reactor inlet fluidly coupled to the pump outlet for receiving the third fluid, and the reactor being configured to generate gas hydrates starting from the third fluid and delivering a fourth fluid at the first reactor outlet, the fourth fluid comprising gas hydrates, unreacted substances and / or water. The system also includes a separator having a separator inlet fluidly connected to the first reactor outlet for receiving the fourth fluid, and the separator is configured to deliver unreacted materials and / or water to a secondary separator outlet fluidly connected to the secondary pump inlet (at a pressure above ambient pressure) and to deliver gas hydrates at the primary separator outlet.

[0010] According to another aspect, the subject matter disclosed herein relates to a method for producing gas hydrates, the method comprising the steps of:

[0011] - Supply water to the first stage of a multiphase multistage pump;

[0012] - supplying the gaseous substance forming the hydrate to an intermediate stage of the multiphase multistage pump;

[0013] - pumping a stream of water and the hydrate-forming substance in at least the last stage of the multiphase multistage pump and delivering the pumped stream to the reactor inlet;

[0014] - generating gas hydrates starting from the pumped stream at the reactor inlet and delivering a stream comprising gas hydrates, unreacted substances and / or water to the main reactor outlet;

[0015] - Separating the gas hydrate from the unreacted substances and / or water in the separator and delivering the gas hydrate to the primary separator outlet and delivering the unreacted substances and / or water to the secondary separator outlet.

[0016] According to further aspects, the subject matter disclosed herein relates to a device for producing purified water starting from unpurified water, in particular brine, or a device for producing purified gas starting from an unpurified gas stream, in particular a non-purified gas stream containing hydrocarbons (e.g. methane, propane, "natural gas" ...) or carbon dioxide or hydrogen or 1,1-dichloro-1-fluoroethane (so-called "R141B"), or a device for producing gas hydrates for energy storage starting from a gas stream, in particular a gas stream containing hydrocarbons. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] A more complete appreciation thereof will be readily obtained as the disclosed embodiments of the present invention and many of its attendant advantages become better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings, in which:

[0018] Figure 1 shows a simplified diagram of a first embodiment of the innovative system for producing gas hydrates, in particular for implementation in a plant for producing purified water,

[0019] Figure 2 shows a simplified diagram of a second embodiment of the inventive system for producing gas hydrates, in particular for implementation in a plant for producing purified water,

[0020] Figure 3 shows a simplified diagram of a third embodiment of the innovative system for producing gas hydrates, in particular for implementation in a plant for producing purified water,

[0021] Figure 4 shows a simplified diagram of a fourth embodiment of the inventive system for producing gas hydrates, in particular for implementation in a plant for producing purified gas,

[0022] Figure 5 shows a simplified diagram of a fifth embodiment of the inventive system for producing gas hydrates, in particular for implementation in a plant for producing purified gas,

[0023] Figure 6 shows a simplified diagram of a sixth embodiment of the innovative system for producing gas hydrates, in particular for implementation in a device for energy storage, and

[0024] Figure 7 A simplified diagram of a seventh embodiment of the inventive system for producing gas hydrates, in particular for producing a purified gas starting from a gas stream containing at least two gases, is shown. DETAILED DESCRIPTION

[0025] According to one aspect, the subject matter disclosed herein relates to a system for producing gas hydrates starting from an unpurified water stream, such as wastewater or brine, in particular seawater. The system comprises a multiphase multistage pump, which receives the unpurified water stream at a main inlet located at the first stage of the pump (i.e., at the suction side of the pump) and receives the gaseous substance forming the hydrate at a secondary inlet located at an intermediate stage of the pump. Advantageously, the multiphase multistage pump is configured to handle substances, in particular gases, which are not at ambient pressure (i.e., they are not delivered at the main inlet of the pump at the first stage of the pump), but at a pressure higher than ambient pressure (i.e., higher than the pressure of the first fluid at the inlet of the main pump). The pump is configured to increase the pressure of the fluid and deliver the pressurized fluid to a reactor, which is configured to generate gas hydrates starting from the pressurized fluid. The reactor is configured to deliver a fluid containing gas hydrates, unreacted substances and / or water to a separator having at least two outlets: a first (primary) outlet that outputs gas hydrates, and a second (secondary) outlet that is fluidly coupled to a secondary inlet and outputs unreacted substances and / or water. The innovative system as described above can be implemented in different plants and can be used for the production of purified water and / or purified gas or for energy storage in the form of gas hydrate particles. Advantageously, the innovative system can be combined with an LNG plant, which typically has a large amount of cold energy that can be used to produce gas hydrates.

[0026] Reference will now be made in detail to embodiments of the present disclosure, examples of which are shown in the accompanying drawings. Examples and drawings are provided in a manner to explain the present disclosure, and these examples and drawings should not be construed as limitations on the present disclosure. In fact, it will be apparent to those skilled in the art that various modifications and variations may be made to the present disclosure without departing from the scope or essence of the present disclosure. In the following description, similar figure numbers are used to illustrate the drawings of the embodiments to indicate elements that perform the same or similar functions. In addition, for clarity of description, some references may not be repeated in all drawings.

[0027] exist Figure 1 1 shows a simplified diagram of a first embodiment of an innovative system for producing gas hydrates, which is generally indicated by reference numeral 100. The system 100 includes at least a pump 110, a reactor 120 and a separator 130.

[0028] The pump 110 is a multiphase multistage pump and has a main pump inlet 111, a first secondary pump inlet 112, and a pump outlet 119. The main pump inlet 111 is configured to receive and deliver a first fluid W to an initial stage of the pump 110, the first fluid comprising liquid water at ambient pressure or pre-pressurized (as will be appreciated in view of Figure 2-Figure 5better explained); for example, the first fluid W can be wastewater (especially process water) or salt water (especially seawater). As will be apparent from the following, the first fluid W can be under ambient conditions, for example, seawater can be at 25°C and ambient pressure, or can be advantageously cooled and / or pre-pressurized in order to reduce the volume of the first fluid (and improve the efficiency of the system). The first secondary pump inlet 112 is configured to receive a second fluid and deliver it to an intermediate stage of the pump 110, the second fluid comprising a gaseous substance that forms hydrates at a pressure higher than ambient pressure. Advantageously, but not limited to, hydrate-forming substances include hydrocarbons (such as methane, propane, natural gas...) or carbon dioxide or hydrogen or 1,1-dichloro-1-fluoroethane. The pump outlet 119 is configured to deliver a third fluid, the third fluid comprising water and a substance that forms hydrates at a predetermined pressure (i.e., a pressure higher than ambient pressure, such as 30 bar-40 bar).

[0029] The reactor 120 has a reactor inlet 121, which is fluidly connected to the pump outlet 119 so as to receive the third fluid delivered by the pump outlet 119. The reactor 120 is configured to generate gas hydrates starting from the third fluid, which are generally crystalline, water-based solids that are physically similar to ice and have gas molecules trapped therein. For example, the temperature of the third fluid in the reactor 120 is in the range of minus 5°C-plus 25°C. For example, the pressure of the third fluid in the reactor 120 is in the range of 5 bar-50 bar. However, the optimal range of temperature and pressure depends on the properties of the fluids in the reactor 120. In particular, the reaction carried out in the reactor 120 generates gas hydrates (which are generally in the form of pure water crystals in which gas molecules are trapped) and a fifth stream (which is hereinafter referred to as brine, which is generally a high concentration solution of salt), which contains one or more salts derived from the third fluid and possible liquid water. It should be noted that the brine may also contain other substances, such as solid particles from wastewater or brine. Advantageously, the reactor 120 further comprises a third reactor outlet 127 configured to discharge the brine. It must also be noted that the brine may still be at high pressure (e.g., 30 bar-40 bar); advantageously, the system 100 further comprises a pressure recovery unit 150, which is fluidly coupled to the third reactor outlet 127 and is configured to recover pressure energy from the brine. For example, the pressure energy recovered from the brine can be used to pre-pressurize the first fluid W before it is delivered to the main pump inlet (with non-limiting reference to Figure 2 , Figure 3 , Figure 4 and Figure 5, an embodiment is shown in which the first fluid W is pre-pressurized in the pressure recovery unit 250 or 350 or 450 or 550). Advantageously, the pressure recovery unit 250 or 350 or 450 or 550 is fluidly connected to the third reactor outlet 227 or 327 or 427 or 527 and uses the pressure energy from the brine to pre-pressurize the first fluid W; as will be better described below, the brine discharged from the third reactor outlet 227 or 327 or 427 or 527 can also be used to recover thermal energy, in particular cooling thermal energy. The pressure recovery unit 250 or 350 or 450 or 550 also has a main outlet 259 or 359 or 459 or 559 configured to discharge low-pressure and / or high-temperature brine. According to another example not shown in the figure, the pressure energy recovered from the brine can be used to generate electrical energy, for example using a turbine, which electrical energy can be supplied in particular to a multiphase multi-stage pump.

[0030] As will be apparent from the following, the third fluid may not be completely affected by the reaction, and part of the third fluid may not react. Reactor 120 has a first reactor outlet 129 configured to deliver a fourth fluid, the fourth fluid comprising gas hydrates, any unreacted material and / or water. Advantageously, reactor 120 also has a second reactor outlet 128, the second reactor outlet fluidly coupled to the first secondary pump inlet 112 and configured to deliver a stream comprising unreacted material and possible water to the first secondary pump inlet 112.

[0031] According to the first possibility (for example in Figure 1 ), the material flow delivered by the second reactor outlet 128 is delivered directly to the first secondary pump inlet 112 at the middle stage of the pump 110, so as to advantageously and efficiently utilize the enthalpy of the material flow delivered by the second reactor outlet 128; in other words, the pressure of the material flow delivered by the second reactor outlet 128 is substantially equal to the pressure at the middle stage of the first secondary pump inlet 112, in particular slightly higher than the pressure at the middle stage of the first secondary pump inlet 112. According to the second possibility (for example in Figure 2 as well as Figure 4 and Figure 5 ), the material flow delivered by the second reactor outlet 228 has a pressure higher than the pressure at the middle stage of the first secondary pump inlet 212; advantageously, the system 200 also includes at least one first pressure reducing device 226, in particular a venturi mixer or an ejector or any device that performs the same function, to adjust the pressure of the material flow so as to substantially reach the pressure at the middle stage of the first secondary pump inlet 212. Non-limiting reference Figure 2, the stream delivered by the second reactor outlet 228 is at a higher pressure than the stream delivered by the secondary separator outlet 238, and the stream delivered by the secondary separator outlet 238 has a higher pressure than the stream delivered by the second reactor outlet 228; advantageously, the pressure reducing device 226 utilizes the Venturi effect to allow the low pressure stream from the secondary separator outlet 238 to merge with the high pressure stream from the second reactor outlet 228. The combined stream exiting the pressure reducing device 226 is substantially at an intermediate pressure between the high pressure stream and the low pressure stream, advantageously at a pressure slightly higher than the pressure at the intermediate stage of the first secondary pump inlet 112, so as to be delivered to the first secondary pump inlet 112. Advantageously, the system 200 also includes a second pressure reducing device 236, as will be better described below. According to a third possibility (not shown in the figure), the pump also includes another secondary pump inlet downstream of the first secondary pump inlet (i.e., at an intermediate stage of the pump, having a higher pressure), and the material flow delivered by the second reactor outlet having a pressure higher than the pressure at the intermediate stage of the first secondary pump inlet is delivered directly to the other secondary pump inlet; in other words, the pressure of the material flow delivered by the second reactor outlet is substantially equal to the pressure at the intermediate stage of the other secondary pump inlet.

[0032] The separator 130 (e.g., a separator with water wash or a gravity separator) has a separator inlet 131, a primary separator outlet 139, and a secondary separator outlet 138, the separator inlet being fluidly coupled to the first reactor outlet 129 to receive the fourth fluid delivered by the first reactor outlet 129. The separator 130 is configured to supply unreacted substances and / or water to the secondary separator outlet 138 at a pressure higher than ambient pressure, and to supply gas hydrates at the primary separator outlet 139. The secondary separator outlet 138 is fluidly coupled to the secondary pump inlet 112 to deliver unreacted substances and / or water to the secondary separator outlet 138.

[0033] Based on but not limited to Figure 6 In an embodiment of the present invention, the main separator outlet 639 can supply gas hydrates to the storage system 680. In particular, the pump 610 has a second secondary pump inlet 613, which is configured to receive a gas stream of a substance that forms hydrates at a pressure higher than the ambient pressure and deliver it to an intermediate stage of the pump 610. Advantageously, the hydrate-forming substance received by the second secondary pump inlet 613 includes hydrocarbons (e.g., methane, propane, natural gas, etc.) or carbon dioxide or hydrogen or 1,1-dichloro-1-fluoroethane; preferably, the hydrate-forming substance includes methane. It should be noted that the first secondary pump inlet 612 and the second secondary pump inlet 613 can respectively deliver a stream containing unreacted substances and possible water and a stream of substances that form hydrates to the same intermediate stage of the pump 610; in other words, the first secondary pump inlet 612 and the second secondary pump inlet 613 can overlap.

[0034] Advantageously, and without limitation, reference is made to Figure 2-Figure 5 , the system 200 or 300 or 400 or 500 further includes a first heat exchanger 240 or 340 or 440 or 540 fluidly coupled to the third reactor outlet 227 or 327 or 427 or 527. In particular, the first heat exchanger 220 or 320 or 420 or 520 can utilize the residual cooling energy of the brine discharged from the third reactor outlet 227 or 327 or 427 or 527. For example, Figure 2 and Figure 4 As shown in , the first heat exchanger 240 or 440 may be located upstream (e.g., directly upstream) of the pump 210 or 410 and may be configured to transfer heat from the first fluid W to the fifth stream; in other words, the first heat exchanger 240 or 440 is configured to cool the first fluid W before it is delivered to the main pump inlet 211 or 411. For example, Figure 3 and Figure 5 As shown in , the first heat exchanger 340 or 540 may be located downstream of the pump 310 or 510 (e.g., directly upstream of the reactor 320 or 520) and may be configured to transfer heat from the third fluid to the fifth stream; in other words, the first heat exchanger 340 or 540 is configured to cool the third fluid before it is delivered to the reactor inlet 321 or 521.

[0035] Advantageously, and without limitation, reference is made to Figure 1-Figure 5 , the system 100 or 200 or 300 or 400 or 500 also includes a dissociator 160 or 260 or 360 or 460 or 560 configured to perform gas hydrate dissociation, typically by reducing pressure and possibly by increasing temperature. For clarity, reference will now be made to Figure 1 embodiment. Advantageously, the dissociator 160 has a dissociator inlet 161 which is fluidly connected to the main separator outlet 139 and receives gas hydrates from the main separator outlet 139. Advantageously, the dissociator 160 also has a main dissociator outlet 169 and a secondary dissociator outlet 168. As described above, the dissociator 160 is configured to perform gas hydrate dissociation and deliver a purified water stream to the main dissociator outlet 169 and a purified gas stream to the secondary dissociator outlet 168. It must be noted that the dissociator 160 can also be configured to store gas hydrates for a predetermined time: for example, the dissociator 160 can be operated as a gas hydrate storage for a period of time, in particular without changing the pressure and / or temperature of the gas hydrates in the dissociator 160 and storing them, and operated to perform gas hydrate dissociation for another period of time, in particular when energy is required. According to another possibility, the system can also include a separate storage tank (see, for example Figure 3, element 390 in the figure), the storage tank is fluidly connected to the secondary dissociator outlet 368 and the secondary pump inlet 312, and the storage tank can store the purified gas received from the secondary dissociator outlet 368 for at least a period of time before supplying the purified gas to the secondary pump inlet 312. Advantageously, the storage tank 390 can also be fluidly connected to the secondary separator outlet 338 and / or the second reactor outlet 328 so as to store unreacted substances and / or water delivered by the secondary separator outlet 338 and / or the second reactor outlet 328. According to another possibility, the system 200 may also include a second pressure reducing device 236, in particular a venturi mixer or an ejector or any device that performs the same function, which is fluidly connected to the secondary separator outlet 238 and the secondary dissociator outlet 268. With non-limiting reference to Figure 2 , the stream delivered by the secondary separator outlet 238 is at a higher pressure than the stream delivered by the secondary dissociator outlet 268. Advantageously, the pressure reducing device 236 utilizes the Venturi effect to allow the low pressure stream from the secondary dissociator outlet 268 to be combined with the high pressure stream from the secondary separator outlet 238. The combined stream exiting the pressure reducing device 236 is substantially at an intermediate pressure between the high pressure stream and the low pressure stream, advantageously at a lower pressure than the stream from the second reactor outlet 228.

[0036] Advantageously, and without limitation, reference is made to Figure 2-Figure 5 , the system 200 or 300 or 400 or 500 further includes a second heat exchanger 270 or 370 or 470 or 570 fluidly coupled to the main dissociator outlet 269 or 369 or 469 or 569. In particular, the second heat exchanger 270 or 370 or 470 or 570 can utilize the residual cooling energy of the purified water discharged from the main dissociator outlet 269 or 369 or 469 or 569. For example, Figure 2 and Figure 4 As shown in , the second heat exchanger 270 or 470 may be located upstream of the pump 210 or 420, in particular upstream of the first heat exchanger 240 or 440, and may be configured to transfer heat from the first fluid W to the purified water stream; in other words, the second heat exchanger 270 or 470 is configured to cool the first fluid W before it is delivered to the main pump inlet 211 or 411, in particular before it is further cooled by the first heat exchanger 240 or 440. For example, Figure 3 and Figure 5As shown in the figures, the second heat exchanger 370 or 570 may be located downstream of the pump 310 or 510 (e.g., directly downstream of the pump 310 or 510) and may be configured to transfer heat from the third fluid to the purified water stream; in other words, the second heat exchanger 370 or 570 is configured to cool the third fluid before it is delivered to the reactor inlet 321 or 521, in particular before it is further cooled by the first heat exchanger 340 or 540. It should be noted that according to one possibility (not shown in any figure), the second heat exchanger 270 or 370 or 470 or 570 may be integrated in the disintegrator 260 or 360 or 460 or 560, for example in the form of a coil surrounding the disintegrator 260 or 360 or 460 or 560.

[0037] As from Figure 1-Figure 3 As is apparent from the above, the system 100 or 200 or 300 can recycle the purified gas stream to the pump 110 or 210 or 310, in particular to an intermediate stage of the pump. Advantageously, the secondary dissociator outlet 168 or 268 or 368 is fluidly coupled to the secondary pump inlet 112 or 212 or 312, and the secondary pump inlet 112 or 212 or 312 is configured to receive the purified gas stream from the secondary dissociator outlet 168 or 268 or 368. In other words, the circulation of gas in the system 100 or 200 or 300 can be defined as a closed loop circulation. It should be noted that the main output of the system 100 or 200 or 300 can be purified water. In other words, the system 100 or 200 or 300 is particularly suitable for producing purified water and can be implemented in an apparatus for producing purified water starting from unpurified water, in particular brine, supplied to the main pump inlet 111 or 211 or 311.

[0038] As from Figure 4 and Figure 5As will be apparent from the above, the system 400 or 500 may not recycle the purified gas stream to the pump 410 or 510 (in other words, the circulation of the gas in the system 400 or 500 may be defined as an open loop cycle). In fact, the main output of the system 400 or 500 may be purified gas starting from an unpurified gas stream. In particular, the pump 410 or 510 has a second secondary pump inlet 413 or 513 configured to receive a gas stream of a hydrate-forming substance at a pressure higher than ambient pressure and deliver it to an intermediate stage of the pump 410 or 510. Advantageously, the hydrate-forming substance received by the second secondary pump inlet 413 or 513 comprises a hydrocarbon (e.g., methane, propane, natural gas, ...) or carbon dioxide or hydrogen or 1,1-dichloro-1-fluoroethane. It should be noted that the first secondary pump inlet 412 or 512 and the second secondary pump inlet 413 or 513 can respectively deliver a stream comprising unreacted substances and possibly water and a stream of hydrate-forming substances to the same intermediate stage of the pump 410 or 510; in other words, the first secondary pump inlet 412 or 512 and the second secondary pump inlet 413 or 513 can coincide.

[0039] The following will use Figure 7 Another embodiment 700 of a system for producing gas hydrates is described. It should be noted that Figure 7 The components 711, 719, 721 and 731 in Figure 1 Elements 111 (main pump inlet), 119 (pump outlet), 121 (reactor inlet) and 131 (separator inlet) are identical or similar and perform identical or similar functions. Figure 7 In the embodiment shown in , the main output of the system 700 can be a purified gas starting from an unpurified gas stream, in particular a gas stream containing at least two gases. Figure 7, the first secondary pump inlet 712 is configured to receive a gas stream containing a substance that forms hydrates at a pressure higher than the ambient pressure and deliver it to the intermediate stage of the pump 710. In particular, the gas stream at the first secondary pump inlet 712 may contain at least two gases: a first gas that is configured to react in the reactor 720 and form a hydrate gas, and a second gas (or a mixture of gases) that does not react (i.e., does not form a hydrate gas). The fourth fluid at the first reactor outlet 729 contains gas hydrates formed from the first gas, unreacted substances (particularly unreacted second gas) and / or water and is delivered to the separator 730. The separator 730 is configured to separate the fourth fluid and supply gas hydrates at the main separator outlet 739 and unreacted gas at the secondary separator outlet 738, the unreacted gas being particularly pure second gas. The primary separator outlet 739 is fluidly coupled to a dissociator 760 configured to perform gas hydrate dissociation and deliver a purified water stream to the primary dissociator outlet 769 and a purified gas stream, particularly a pure first gas, to the secondary dissociator outlet 768 .

[0040] In other words, the system 400 or 500 or 700 is particularly suitable for producing purified gas and can be implemented in an apparatus for producing purified gas starting from an unpurified gas stream, which is, for example, a substance forming a hydrate comprising, in particular, natural gas or carbon dioxide or hydrogen or propane or 1,1-dichloro-1-fluoroethane, supplied to the second secondary pump inlet 413 or 513. In particular, the system 700 is suitable for producing purified gas from a gas stream containing at least two gases.

[0041] As from Figure 6 As is apparent from the foregoing, the main output of the system 600, in particular from the separator 630, may be gas hydrates, which may be stored in the storage system 680 (e.g., in the form of pellets). For example, the storage system 680 may store gas hydrates at ambient pressure and a temperature of about -20°C. (Gas hydrates stored under these conditions have in particular seven times the energy density - which means that less storage space is required - than would be the case with LNG if stored at ambient pressure (which must be stored at about -161°C, the liquefaction temperature of natural gas at ambient pressure)). In other words, the system 600 is particularly suitable for producing gas hydrates for energy storage and may be implemented in an apparatus for producing gas hydrates for energy storage starting from a gas stream, which is, for example, a material forming hydrates, in particular comprising hydrocarbons, supplied to the inlet 613 of the second secondary pump.

[0042] According to another aspect, the subject matter disclosed herein relates to a method for producing gas hydrates, the method comprising the steps of:

[0043] - supplying a first fluid comprising water in a first stage of a multiphase multistage pump;

[0044] - supplying the hydrate-forming gaseous substance to an intermediate stage of a multiphase multistage pump;

[0045] - pumping and pressurizing the streams of the first fluid and the hydrate-forming substance in at least the last stage of a multiphase multistage pump and delivering the pumped streams to the reactor inlet;

[0046] - generating gas hydrates starting from the pumped stream at the reactor inlet and delivering a stream comprising gas hydrates, unreacted substances and / or water to the main reactor outlet;

[0047] - Separating the gas hydrate from the unreacted substances and / or water in the separator and delivering the gas hydrate to the primary separator outlet and delivering the unreacted substances and / or water to the secondary separator outlet.

[0048] Advantageously, unreacted materials and / or water from the outlet of the secondary separator may be recycled to an intermediate stage of the multiphase multistage pump.

[0049] According to one possibility, the gas hydrates from the outlet of the primary separator may be delivered to a dissociator, and the method may further comprise the steps of dissociating the gas hydrates in the dissociator and delivering purified water to the outlet of the primary dissociator and delivering purified gas to the outlet of the secondary dissociator. Advantageously, the purified gas from the outlet of the secondary dissociator may be recycled to an intermediate stage of the multiphase multistage pump. According to another possibility, the gas hydrates from the outlet of the primary separator may be delivered to a storage system that may store the gas hydrates (e.g., in the form of particles) for a predetermined time.

[0050] It should be noted that although exemplary embodiments have been described above in some exemplary combinations of components and / or functions, alternative embodiments may be provided by different combinations of components and / or functions without departing from the scope of the present disclosure. In addition, it should be noted that specific features described individually or as part of an embodiment may be combined with other individually described features or parts of other embodiments.

Claims

1. A system (100, 600) for producing gas hydrates, the system comprising: a pump (110, 610) having a primary pump inlet (111, 611), at least one secondary pump inlet (112, 612) and a pump outlet (119, 619), wherein the pump (110, 610) is a multiphase multistage pump, wherein the primary pump inlet (111, 611) is configured to receive a first fluid (W) and deliver it to an initial stage of the pump (110, 610), The first fluid comprises liquid water at ambient pressure or pre-pressurization, wherein a first secondary pump inlet (112, 612) is configured to receive and deliver a second fluid to an intermediate stage of the pump (110, 610), the second fluid comprising a gaseous substance that forms the hydrate at a pressure above ambient pressure or pre-pressurization, wherein the pump outlet (119,619) is configured to deliver a third fluid, the third fluid comprising the water and the substance that forms the hydrate at a predetermined pressure higher than the pressure of the ambient pressure or the pre-pressurized water, a reactor (120, 620) having a reactor inlet (121, 621) and at least one reactor outlet (129, 629), wherein the reactor inlet (121, 621) is fluidly coupled to the pump outlet (119, 619) for receiving the third fluid, wherein the reactor (120, 620) is configured to generate gas hydrates from the third fluid and deliver a fourth fluid at the first reactor outlet (129, 629), the fourth fluid comprising gas hydrates, unreacted substances and / or water, - a separator (130, 630) having a separator inlet (131, 631), a primary separator outlet (139, 639) and a secondary separator outlet (138, 638), wherein the separator inlet (131, 631) is fluidly coupled to the first reactor outlet (129, 629) to receive the fourth fluid, wherein the separator (130, 630) is configured to supply unreacted material and / or water to the secondary separator outlet (138, 638) and to supply gas hydrates at the primary separator outlet (139, 639) at a pressure above ambient pressure; Wherein the secondary separator outlet (138, 638) is fluidly coupled to the first secondary pump inlet (112, 612).

2. The system (100, 600) of claim 1, wherein the reactor (120, 620) further comprises a second reactor outlet (128, 628) fluidly coupled to the secondary pump inlet (112, 612), Wherein the second reactor outlet (128, 628) is configured to deliver a stream comprising unreacted materials and possibly water to the secondary pump inlet (112, 612).

3. The system (400, 500, 600, 700) of claim 1, wherein the pump (410, 510, 610, 710) further comprises a second secondary pump inlet (413, 513, 613) configured to receive a gas stream of the substance that forms the hydrate at a pressure above ambient pressure and deliver it to an intermediate stage of the pump (410, 510, 610, 710).

4. The system (400, 500, 600, 700) according to claim 3, wherein the gas stream comprises hydrocarbons or carbon dioxide or hydrogen or 1,1-dichloro-1-fluoroethane.

5. The system (100, 200, 300, 400, 500) of claim 1, wherein the reactor (120, 220, 320, 420, 520) further comprises a third reactor outlet (127, 227, 327, 427, 527), the third reactor outlet being configured to discharge a fifth stream comprising one or more salts derived from the third fluid and possibly liquid water.

6. The system (100, 200, 300, 400, 500) of claim 5, further comprising a pressure recovery unit (150, 250, 350, 450, 550) fluidly coupled to the third reactor outlet (127, 227, 327, 427, 527), The pressure recovery unit (150, 250, 350, 450, 550) is configured to recover pressure energy from the fifth stream.

7. The system (200, 400) of claim 5, further comprising a first heat exchanger (240, 440) fluidly coupled to the third reactor outlet (227, 427), wherein the first heat exchanger (240, 440) is configured to transfer heat from the first fluid W to the fifth stream.

8. The system (300, 500) of claim 5, further comprising a first heat exchanger (340, 540) fluidly coupled to the third reactor outlet (327, 527), wherein the first heat exchanger (340, 540) is configured to transfer heat from the third fluid to the fifth stream.

9. The system (100, 200, 300, 400, 500, 700) of claim 1, further comprising a dissociator (160, 260, 360, 460, 560, 760) having a dissociator inlet (161, 261, 361, 461, 561, 761), a primary dissociator outlet (169, 269, 369, 469, 569, 769), and a secondary dissociator outlet (168, 268, 368, 468, 568, 768), wherein the dissociator inlet (161, 261, 361, 461, 561, 761) is fluidly coupled to the primary dissociator outlet (139, 239, 339, 439, 539, 739), wherein the dissociator (160, 260, 360, 460, 560, 760) is configured to perform gas hydrate dissociation and deliver a purified water stream to the primary dissociator outlet (169, 269, 369, 469, 569, 769) and deliver a purified gas stream to the secondary dissociator outlet (168, 268, 368, 468, 568, 768).

10. The system (100, 200, 300) of claim 9, wherein the secondary dissociator outlet (168, 268, 368) is fluidly coupled to the secondary pump inlet (112, 212, 312), wherein the secondary pump inlet (112, 212, 312) is configured to receive the purified gas stream from the secondary dissociator outlet (168, 268, 368, 468, 568).

11. The system (200, 400) of claim 9, further comprising a second heat exchanger (270, 470) fluidly coupled to the primary dissociator outlet (269, 469), Wherein the second heat exchanger (270, 470) is configured to transfer heat from the first fluid W to the purified water stream delivered to the main dissociator outlet (269, 469).

12. The system (300, 500) of claim 9, further comprising a second heat exchanger (370, 570) fluidly coupled to the primary dissociator outlet (369, 569), wherein the second heat exchanger (370, 570) is configured to transfer heat from the third fluid to the purified water stream delivered to the primary dissociator outlet (369, 569).

13. A device for producing purified water starting from unpurified water, wherein the device comprises a system according to claim 9, The unpurified water is supplied to the main pump inlet (111, 211, 311, 411, 511).

14. An apparatus for producing a purified gas starting from an unpurified gas stream, wherein the apparatus comprises a system according to claim 1 or claim 3, The unpurified gas stream is supplied to the first secondary pump inlet (712) or the second secondary pump inlet (413, 513).

15. A plant for producing gas hydrates for energy storage starting from a gas stream, wherein the plant comprises a system according to claim 3, Wherein the gas stream is supplied to the second secondary pump inlet (613).

16. A method for producing gas hydrates, the method comprising the steps of: - supplying a first fluid comprising water to a first stage of a multiphase multistage pump; - supplying the gaseous substance forming the hydrate to an intermediate stage of the multiphase multistage pump; - pumping and pressurizing a stream of a first fluid and a substance forming the hydrate in at least the last stage of the multiphase multistage pump and delivering the pumped stream to a reactor inlet; - generating gas hydrates starting from the pumped stream at the reactor inlet and delivering a stream comprising gas hydrates, unreacted substances and / or water to the main reactor outlet; - Separating the gas hydrate from the unreacted substances and / or water in the separator and supplying the gas hydrate to the primary separator outlet and the unreacted substances and / or water to the secondary separator outlet.

17. The method according to claim 16, further comprising the steps of: Unreacted materials and / or water are recycled from the secondary separator outlet to the intermediate stage of the multiphase multistage pump.

18. The method according to claim 16, further comprising the steps of: Gas hydrates from the primary separator outlet are dissociated in a dissociator and purified water is delivered to the primary dissociator outlet and purified gas is delivered to the secondary dissociator outlet.

19. The method according to claim 18, further comprising the steps of: Purified gas is recycled from the secondary dissociator outlet to the intermediate stage of the multiphase multistage pump.

20. The method according to claim 16, further comprising the steps of: The gas hydrate from the outlet of the main separator is stored in a storage system for a predetermined time.

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