A system and method for microwave decomposition of natural gas hydrate

Abstract

The present application provides a system and method for microwave decomposition of natural gas hydrates, relating to the field of natural gas hydrate extraction. The system includes a microwave generator, a visual reactor, a microwave enhancement device, and a data acquisition and control device. The microwave enhancement device is located within the visual reactor. The microwave enhancement device includes at least one columnar component perpendicular to the bottom of the visual reactor, the columnar component comprising a cylindrical metal cavity, a liquid medium disposed within the metal cavity, and a wave-transparent shell covering the metal cavity. The metal cavity is also provided with a first temperature sensor for collecting temperature data of the liquid medium. The first temperature sensor is connected to the data acquisition and control device. This system avoids the problem of microwaves affecting hydrate decomposition efficiency due to limited penetration depth in sediments. It can automatically control whether microwaves are generated, thereby improving microwave utilization efficiency and energy efficiency.

Description

Technical Field

[0001] The present application relates to the field of natural gas hydrate mining, and in particular to a system and method for microwave decomposition of natural gas hydrates. Background Art

[0002] Natural gas hydrates are a vast, clean energy source. Understanding their physical properties, synthesis, and decomposition characteristics is crucial for their commercial exploitation, making research on them crucial. Currently, the main methods for extracting natural gas hydrates include pressure reduction, thermal stimulation, inhibitors, carbon dioxide displacement, and a combination of these methods. Thermal stimulation and pressure reduction are considered the most promising. Thermal stimulation methods can be divided into two types: surface heating, which involves injecting heat (steam, hot water, brine, etc.) into the hydrate reservoir. This heating method incurs significant heat losses and is uneconomical; and in situ heating, which involves direct heating of the hydrate reservoir using electromagnetic heating or downhole combustion. This method, using downhole electromagnetic heating, can achieve a theoretical recovery rate of up to 70% and shortens heating time. Microwaves, electromagnetic waves with frequencies ranging from 300 MHz to 300 GHz, can uniformly and rapidly heat polar molecular hydrates, making microwave extraction (decomposition) of natural gas hydrates an effective method.

[0003] However, according to microwave penetration depth formula (1) and formula (2), we know that:

[0004]

[0005]

[0006] Microwaves have a limited penetration depth in sediments, reaching only tens of centimeters at a frequency of 2.45 GHz. Therefore, when there is a high amount of free water in the reactor, the hydrate region directly exposed to microwave radiation is limited. Hydrates far from the microwave radiation zone cannot be decomposed directly by microwaves, but rather rely more on the system's macroscopic heat conduction. This inevitably affects the rate of microwave decomposition of natural gas hydrates. Summary of the Invention

[0007] To address the problem that microwaves have limited penetration depth in sediments and that natural gas hydrates in sediments far from the microwave source area rely on system heat conduction, which affects the hydrate decomposition rate, this application proposes a system and method for enhancing the decomposition of natural gas hydrates using a microwave enhancement device. The microwave enhancement device contained therein can enhance microwaves, thereby fully decomposing natural gas hydrates, and also enhance the utilization rate of microwaves, thereby improving the extraction efficiency of natural gas hydrates and reducing extraction costs.

[0008] The technical solution of this application is as follows:

[0009] A system for decomposing natural gas hydrates by microwaves, comprising a microwave generator, a visual reactor, a microwave intensification device and a data acquisition and control device;

[0010] The visual reactor comprises a reactor body and a reactor top cover, the microwave generator is connected to the reactor top cover, and the microwave enhancement device is located inside the visual reactor;

[0011] The microwave enhancement device includes at least one columnar component perpendicular to the bottom of the visual reactor. The columnar component includes a columnar metal cavity, a liquid medium arranged in the metal cavity, and a wave-transparent shell covering the metal cavity. A first temperature sensor for collecting temperature data of the liquid medium is also provided in the metal cavity. The first temperature sensor is connected to the data acquisition and control device, and the data acquisition and control device is connected to the microwave generating device.

[0012] Preferably, the microwave enhancement device comprises a plurality of columnar components, and the plurality of columnar components are respectively perpendicular to the bottom of the visual reactor;

[0013] Alternatively, a portion of the plurality of columnar components is perpendicular to the bottom of the visual reactor, and another portion is parallel to the bottom of the visual reactor.

[0014] The microwave enhancement device of this application can be designed into various sizes of "vertical well," "horizontal well," or "well grid" structures, depending on experimental needs. When microwaves act on the reactor, the high-pressure, wave-transparent shell acts as a microwave transmission channel. This allows the microwaves to propagate axially to the bottom of the reactor and radiate radially to the surrounding area, thereby increasing the direct range of the microwaves.

[0015] Preferably, the material of the metal cavity includes copper, silver, aluminum or stainless steel;

[0016] The material of the wave-transmitting shell includes glass, quartz glass or polytetrafluoroethylene;

[0017] The liquid medium includes water.

[0018] Because the visual reactor in this application decomposes natural gas hydrates within a high-pressure environment, the microwave enhancement device within the reactor must withstand a certain pressure to ensure stable operation. Therefore, when selecting the material for the microwave enhancement device, a metal cavity and wave-transparent shell with high pressure resistance is required. The specific pressure resistance is determined by the pressure resistance of the visual reactor and is generally required to be ≥10MPa.

[0019] Preferably, a reservoir is further provided at the bottom of the visual reactor, and the reservoir comprises a porous medium material;

[0020] The porous medium material includes quartz sand, glass sand or clay.

[0021] The liquid medium within the metal cavity rapidly heats up after absorbing microwaves. When microwave radiation is cut off, the natural gas hydrates within the microwave-receiving range have largely decomposed. Heat conduction from the liquid medium within the microwave-enhanced device now becomes the primary mechanism for natural gas hydrate decomposition. The liquid medium is a strong microwave-absorbing liquid with a high specific heat capacity and is less susceptible to external influences. Therefore, through the highly thermally conductive metal cavity and wave-transparent shell, it can continue to heat the surrounding reservoir, acting like an "electric heating rod."

[0022] Preferably, the microwave generating device comprises a microwave power supply, a microwave head, a three-pin dispenser, a waveguide and a horn antenna arranged in sequence, the microwave power supply is connected to the data acquisition and control device, and the horn antenna is connected to the top cover of the reactor;

[0023] Preferably, a second temperature sensor and a pressure sensor are further provided in the body of the visual reaction kettle, and the second temperature sensor and the pressure sensor are respectively connected to the data acquisition and control device.

[0024] Preferably, the microwave decomposition system for natural gas hydrates further comprises a water bath temperature control box and a gas injection device;

[0025] The visual reactor is arranged in the water bath temperature control box, and an air inlet is provided on the side wall of the reactor body, and the air inlet is connected to the gas injection device.

[0026] Preferably, the gas injection device includes a gas cylinder, an air compressor, a booster pump and a gas storage tank connected by pipelines, and the gas inlet is connected to the gas storage tank.

[0027] The microwave generating device of the present application is used to radiate microwaves to the natural gas hydrate sample inside the visual reactor, thereby decomposing the hydrate under microwave thermal stimulation; the visual reactor is used to synthesize and decompose natural gas hydrates under preset conditions; the microwave enhancement device can not only radiate microwaves to the sediments in the reactor where the microwave penetration depth is limited, but also automatically control whether microwaves need to be generated according to the actual temperature, and decompose natural gas hydrates through the alternating effects of heat conduction heating and direct microwave radiation; the gas injection device is used to provide gas for synthesizing natural gas hydrates into the high-pressure visual reactor; the water bath temperature control box is used to control the temperature changes in the visual reactor; the data acquisition and control device is used to collect, save and analyze the results of temperature, pressure and gas production changes in the visual reactor during the generation and decomposition of natural gas hydrates, and is also used to collect and analyze the temperature of the first temperature sensor in the microwave enhancement device, and regulate whether the microwave generating device needs to be turned on or off according to the temperature.

[0028] Preferably, a gas outlet is further provided on the side wall of the reactor body, the gas outlet is connected to a drying pipe and a flow meter in sequence, and the flow meter is connected to the data acquisition and control device;

[0029] The reactor top cover of the visual reactor is made of sapphire glass.

[0030] The reactor top cover of the visual reactor in this application is made of sapphire glass with good light transmittance, which can not only be used to observe the changes in the hydrate morphology during the formation and decomposition of natural gas hydrates in the reactor, but also can irradiate the hydrate samples in the reactor through the microwaves generated by the microwave generator.

[0031] The present application also provides a method for decomposing natural gas hydrates by microwaves, which uses the above-mentioned system for decomposing natural gas hydrates by microwaves, comprising:

[0032] Fill the visual reactor with natural gas hydrate and set the temperature T for decomposing the natural gas hydrate. max and T min ;

[0033] The microwave generating device is turned on, and when the data acquisition control device receives the temperature of the first temperature sensor reaching T max When the temperature of the first temperature sensor is lower than T min The microwave generating device is controlled to start up by a signal until the natural gas hydrate in the visual reactor is completely decomposed.

[0034] Preferably, when the microwave decomposition system for natural gas hydrate further includes a water bath temperature control box and a gas injection device, the natural gas hydrate is filled into the visual reactor including:

[0035] The visual reactor is placed in the water bath temperature control box, the microwave enhancement device and the non-gaseous raw materials required for synthesizing natural gas hydrates are placed in the visual reactor, sealed and evacuated, and then the gas raw materials required for synthesizing the natural gas hydrates are injected into the visual reactor through the gas injection device. The temperature in the visual reactor is adjusted by controlling the temperature of the water bath temperature control box. When the temperature and pressure in the visual reactor reach the reaction conditions required for synthesizing the natural gas hydrate, a synthesis reaction is carried out to obtain the natural gas hydrate.

[0036] Preferably, the gas in the gas injection device includes at least one of methane, ethane and propane.

[0037] This application has the following advantages:

[0038] This application incorporates a microwave intensification device within a visual reactor. This device allows microwaves to radiate to natural gas hydrates within the reactor where microwave penetration is limited, effectively decomposing and producing gas from most natural gas hydrate samples under microwave thermal stimulation. The device also controls the microwave's effect, achieving efficient microwave decomposition and gas production while also saving energy consumed by microwave generation. The liquid medium within the microwave intensification device rapidly heats up after absorbing microwaves. When microwave radiation is cut off, the liquid medium can continue to heat the surrounding natural gas hydrates through the metal cavity and wave-transparent shell, acting similarly to an "electric heating rod" and enhancing microwave utilization.

[0039] In the method for microwave decomposition of natural gas hydrates in the present application, the first temperature sensor and data acquisition control device of the microwave intensification device in the system are utilized. By setting a temperature threshold, it is automatically controlled whether the microwave generator is required to generate microwaves to perform microwave thermal shock on the hydrates in the visual reactor. Natural gas hydrates are alternately decomposed through the direct action of microwaves and the heat conduction action of the microwave intensification device, thereby improving the energy efficiency ratio of microwave decomposition of hydrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work.

[0041] Figure 1 A schematic diagram of the system structure of microwave decomposition of natural gas hydrates in Example 1 is shown;

[0042] Figure 2 shows a schematic structural diagram of a columnar component;

[0043] Figure 3 Shown is a schematic diagram of the structure of different types of microwave enhancement devices in a visual reactor.

[0044] Description of main component symbols:

[0045] 1- Microwave power supply, 2- Microwave head, 3- Three-pin dispenser, 4- Waveguide, 5- Horn antenna, 6- Reactor top cover, 7- Reactor body, 8- Reservoir, 9- Microwave intensification device, 10- Water bath temperature control box, 11- Computer, 12- Flow meter, 13- Drying tube, 14- Gas cylinder, 15- Air compressor, 16- Booster pump, 17- Gas storage tank;

[0046] 901 - first temperature sensor, 902 - wave-transparent shell, 903 - metal cavity, 904 - liquid medium. DETAILED DESCRIPTION

[0047] The following describes in detail embodiments of the present application. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application.

[0048] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. Conversely, when an element is referred to as being "directly on" another element, there is no intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0049] In this application, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integration; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components or interactions between two components. Those skilled in the art will understand the specific meanings of these terms in this application based on specific circumstances.

[0050] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the features. Throughout the description of this application, "plurality" means two or more, unless otherwise specifically defined.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application belongs. The terms used in the template description herein are for the purpose of describing specific embodiments only and are not intended to limit this application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0052] Example 1

[0053] This embodiment provides a system for microwave decomposition of natural gas hydrates, specifically comprising: a microwave generator, a visual reactor, a microwave enhancement device, a gas injection device, a water bath temperature control device, and a data acquisition and control device. Figure 1 shown.

[0054] Among them, the microwave generating device includes a microwave power supply 1, a microwave head 2, a three-pin dispenser 3, a waveguide 4 and a horn antenna 5; the visual reactor includes a reactor top cover 6 and a reactor body 7; the horn antenna 5 in the microwave generating device is connected to the reactor top cover 6 of the visual reactor; the microwave power supply 1 is connected to the computer 11 in the data acquisition and control device, and the control software in the computer can be used to control whether the microwave power supply needs to be turned on or off.

[0055] There are also a reservoir 8 and a microwave enhancement device 9 inside the visual reactor; the entire visual reactor is placed in a water bath temperature control box 10; a second temperature sensor and a pressure sensor are also provided inside the visual reactor, both of which are connected to the computer 11 in the data acquisition and control device to monitor the temperature and pressure conditions inside the visual reactor.

[0056] The reactor top cover 6 of the present application is made of sapphire glass, which has good light transmission effect and can also transmit microwaves, so that the microwave energy generated by the microwave generator can be radiated to the natural gas hydrate sample in the reactor.

[0057] Since it is difficult to obtain natural gas hydrates for direct testing in a laboratory environment, when using this system to conduct experiments on the decomposition of natural gas hydrates, it is necessary to first synthesize natural gas hydrates under a certain temperature and pressure, and then use the microwave generator and microwave intensification device in the system to decompose the synthesized natural gas hydrates.

[0058] When synthesizing natural gas hydrates, it is generally necessary to combine certain gases with water at specific temperatures and pressures. Therefore, the microwave decomposition system for natural gas hydrates of the present application also includes a gas injection device. The side wall of the reactor is provided with an air inlet, which is connected to the gas injection device.

[0059] The gas injection device specifically includes a gas cylinder 14, an air compressor 15, a booster pump 16, and a gas storage tank 17 connected by pipelines, with the gas inlet connected to the gas storage tank 17. The gas cylinder 14 provides the gas source; the air compressor 15 and the booster pump 16 work together to increase the pressure of the transmitted gas to a level higher than the pressure of the gas in the gas cylinder 14; the gas storage tank 17 is used to store the pressurized gas, which is then injected into the visual reactor through the gas inlet via the gas inlet pipeline.

[0060] After synthesizing natural gas hydrates, the visual reactor uses microwaves to decompose the natural gas hydrates within the reactor, generating natural gas. This generated natural gas then flows through a gas outlet on the sidewall of the visual reactor, sequentially passing through a drying tube 13 and a flowmeter 12, before being stored. The flowmeter 12 is also connected to a computer 11 in the data acquisition and control system to record the instantaneous gas production rate and cumulative gas production within the reactor.

[0061] In addition to the raw materials of water and gas, natural gas hydrate synthesis requires a porous medium placed in a reactor to simulate the pore environment required for natural gas hydrate synthesis. Natural gas hydrates are then synthesized under a low-temperature, high-pressure environment. Quartz sand can be used as the porous medium, but other materials such as glass sand and clay can also be used as needed.

[0062] The reservoir 8 in the reactor contains different substances at different stages. Before natural gas hydrate synthesis, the reservoir 8 contains water and porous media. After natural gas hydrate synthesis and microwave decomposition, the reservoir 8 contains a mixture of water and natural gas hydrate in addition to the porous media.

[0063] For the microwave enhancement device 9 of this embodiment, only one columnar component perpendicular to the bottom of the reactor can be set in the visual reactor, and its structural diagram is as shown in FIG. Figure 2 The columnar component includes: a columnar metal cavity 903, a liquid medium 904 disposed inside the metal cavity 903, and a wave-transparent shell 902 covering the metal cavity 903. A first temperature sensor 901 is also disposed inside the metal cavity 903. The first temperature sensor 901 is connected to the computer 11 of the data acquisition and control device.

[0064] It should be noted that the cylindrical components can be designed to various sizes based on experimental needs. The metal cavity 903 can generally be made of a metal or metal alloy that can achieve the target withstand voltage, such as copper, silver, aluminum, or stainless steel. The wave-transparent shell 902 can generally be made of a microwave-transparent material that can achieve the target withstand voltage, such as glass, quartz glass, or polytetrafluoroethylene. The target withstand voltage for the metal cavity 903 and the wave-transparent shell 902 is generally ≥10 MPa. The liquid medium 904 is generally a liquid with a high specific heat capacity and strong microwave absorption properties, such as water.

[0065] like Figure 3 As shown, the microwave enhancement device 9 can be provided with only one columnar component perpendicular to the bottom of the visible reactor as in this embodiment. This structure can be called a "vertical well" structure. Figure 3 (a) in the figure; multiple columnar components can also be set perpendicular to the bottom of the reactor, which can be called a "horizontal well" structure, such as Figure 3 (b) of FIG; Alternatively, one or more columnar components parallel to the bottom of the reactor may be provided on the basis of a columnar component perpendicular to the bottom of the reactor, which may be referred to as a "well network" structure, such as Figure 3 Figure (c).

[0066] It should be noted that in order to improve the decomposition efficiency of natural gas hydrates at the bottom of the reactor, at least one columnar component is required to be located at the bottom of the visible reactor. These columnar components may be in direct contact with the bottom of the visible reactor or may not be in contact with the bottom of the reactor.

[0067] This embodiment uses a microwave decomposition system for natural gas hydrates to conduct an experiment on microwave decomposition of natural gas hydrates in a laboratory environment. The specific method of the experiment includes:

[0068] (1) Check the experimental equipment, calibrate the temperature sensor and pressure sensor in the visual reactor, and check the valves and pipelines of each device for leaks to ensure that the entire experimental system is airtight and leak-proof.

[0069] (2) Open the visual reactor, clean it with deionized water, dry it, and prepare it for the configuration of experimental samples.

[0070] (3) A mixture of quartz sand and water was placed in a visual reactor, and a microwave enhancement device with a "vertical well" structure was placed in the center of the visual reactor. The temperature in the visual reactor was then controlled by a water bath temperature control device to the set temperature required for the synthetic natural gas hydrate experiment, which was 2°C.

[0071] (4) After the temperature in the visual reactor stabilizes, the air in the reactor is exhausted by vacuuming to prevent the air from affecting the experimental results; or a certain amount of methane can be injected into the reactor and then emptied, and the operation can be repeated 2 to 3 times to ensure that the air in the reactor is exhausted.

[0072] (5) Methane was introduced into the visible reactor through the gas injection device. When the pressure in the reactor reached the set pressure of 6 MPa for the synthesis experiment, the introduction of methane was stopped, and then the synthesis experiment of natural gas hydrate was started at a temperature of 2°C.

[0073] (6) Turn on the computer of the data acquisition control device, monitor the data of the second temperature sensor and pressure sensor in the body of the visual reactor, record the change pattern of temperature and pressure in the visual reactor over time during the synthesis experiment, analyze the gas production results, and maintain data communication.

[0074] (7) Set the temperature T for decomposing natural gas hydrate max and T min , where T max is 80℃, T min It is 20℃.

[0075] (8) After 72 hours of synthesis reaction, 40% of methane hydrate has been obtained in the visible reactor; then the microwave generator is turned on, and the microwaves generated perform radiolysis on the methane hydrate in the visible reactor, achieving rapid gas production, and at the same time, the temperature of the liquid medium in the columnar component of the microwave enhancement device can be gradually increased.

[0076] When the temperature of the first temperature sensor in the microwave enhancement device reaches 80°C, the computer will receive a relevant signal and then control the microwave generator to automatically turn off the microwave power supply. At this time, most of the methane hydrate in the reactor has been visually decomposed. The microwave enhancement device in the reactor will continue to heat the undecomposed methane hydrate due to the presence of liquid medium.

[0077] When the temperature of the first temperature sensor drops to 30°C, the microwave generator can be turned on again based on the gas production in the reactor. Generally, in laboratory settings, the hydrates in the reactor are almost completely decomposed after a single microwave treatment. However, in hydrate mining scenarios, where the reactor is continuously filled with natural gas hydrates, the microwave generator needs to be turned on again until the temperature of the first temperature sensor reaches 80°C, at which point it automatically turns off, performing the relevant temperature cycle to ensure continuous decomposition and production of natural gas.

[0078] It should be noted that when a plurality of columnar components are provided in the microwave enhancement device, a plurality of temperature sensors will be connected to the data acquisition and control device. Then, when the microwave generating device is started to perform radiolysis on the hydrate in the visual reactor, as long as the temperature display of one of the temperature sensors of the microwave enhancement device rises to the maximum temperature T max , then the computer of the data acquisition and control device will issue an instruction to automatically turn off the microwave power supply of the microwave generating device.

[0079] Example 2

[0080] The microwave decomposition system of natural gas hydrate in this embodiment is basically the same as that in embodiment 1, except that the microwave intensification device 9 in the visible reactor of this embodiment is used. Figure 3 The “horizontal well” structure in Figure (b).

[0081] The method for conducting the experiment in this embodiment using a system for decomposing natural gas hydrates using microwaves is the same as that in embodiment 1.

[0082] Example 3

[0083] The microwave decomposition system of natural gas hydrate in this embodiment is basically the same as that in embodiment 1, except that the microwave intensification device 9 in the visible reactor of this embodiment is used. Figure 3 The “well network” structure in Figure (c).

[0084] The method for conducting the experiment in this embodiment using a system for decomposing natural gas hydrates using microwaves is the same as that in embodiment 1.

[0085] Comparative Example 1

[0086] This comparative example provides a system for decomposing natural gas hydrates by microwaves, which is basically the same as Example 1, except that no microwave enhancement device is provided in the visible reactor in this example.

[0087] The method for conducting the experiment in this comparative example using a system for decomposing natural gas hydrates using microwaves is the same as that in Example 1.

[0088] The raw materials and reaction times used in the methane hydrate synthesis in Examples 1-3 were identical. The microwave decomposition conditions for methane hydrate production were also identical: a pressure of 3.60 MPa and a microwave power of 400 W. Information about the decomposition process is shown in Table 1 below.

[0089] Table 1 Information on the microwave decomposition process of Examples 1-3 and Comparative Example 1

[0090]

[0091]

[0092] Compared with Comparative Example 1, the total microwave decomposition time and microwave action time of Examples 1-3 were both reduced, and the average gas production rate and energy efficiency ratio were significantly improved. Among them, Example 2 had the highest average gas production rate and energy efficiency ratio.

[0093] The average gas production rate ν of natural gas hydrate decomposition can be calculated by the following formula:

[0094]

[0095] Where: V is the total gas production from the decomposition of natural gas hydrate, in SL; t is the decomposition time of natural gas hydrate, in min.

[0096] The energy efficiency ratio η of natural gas hydrate decomposition can be calculated according to the following formula:

[0097]

[0098]

[0099] E mic =P·t w

[0100] Where: is the heat released by the total combustion of the recovered gas from the decomposition of natural gas hydrate, in kJ; n is the mole number of the total gas produced, in mol; P is the heating power of the microwave, in W; is the molar heat of combustion of methane gas, which is 890.3KJ / mol; t w is the microwave heating time, in min.

[0101] In all examples shown and described herein, any specific values should be interpreted as merely exemplary and not limiting, and thus other examples of the exemplary embodiments may have different values.

[0102] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0103] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present application, and such modifications and improvements are all within the scope of protection of the present application.

Claims

1. A system for decomposing natural gas hydrates by microwaves, characterized in that: It includes microwave generating device, visual reactor, microwave intensifying device and data acquisition and control device; The visual reactor comprises a reactor body and a reactor top cover, the microwave generator is connected to the reactor top cover, and the microwave enhancement device is located inside the visual reactor; The microwave enhancement device includes at least one columnar component perpendicular to the bottom of the visual reactor, the columnar component includes a columnar metal cavity, a liquid medium disposed in the metal cavity, and a wave-transparent shell covering the metal cavity. A first temperature sensor for collecting temperature data of the liquid medium is also disposed in the metal cavity. The first temperature sensor is connected to the data acquisition control device, and the data acquisition control device is connected to the microwave generating device. The material of the metal cavity includes copper, silver, aluminum or stainless steel; The material of the wave-transparent shell includes glass or polytetrafluoroethylene; The liquid medium includes water; The microwave generating device includes a microwave power supply, a microwave head, a three-pin dispenser, a waveguide and a horn antenna which are arranged in sequence. The microwave power supply is connected to the data acquisition and control device, and the horn antenna is connected to the reactor top cover.

2. The system for microwave decomposition of natural gas hydrates according to claim 1, characterized in that: The microwave enhancement device includes a plurality of columnar components, and the plurality of columnar components are respectively perpendicular to the bottom of the visual reactor; Alternatively, a portion of the plurality of columnar components is perpendicular to the bottom of the visual reactor, and another portion is parallel to the bottom of the visual reactor.

3. The system for microwave decomposition of natural gas hydrate according to claim 1, characterized in that: The bottom of the visual reactor is also provided with a reservoir, which comprises a porous medium material; The porous medium material includes quartz sand, glass sand or clay.

4. The system for microwave decomposition of natural gas hydrates according to claim 1, characterized in that: The visual reactor body is further provided with a second temperature sensor and a pressure sensor, and the second temperature sensor and the pressure sensor are respectively connected to the data acquisition and control device.

5. The system for microwave decomposition of natural gas hydrate according to claim 1, characterized in that: It also includes a water bath temperature control box and a gas injection device; The visual reactor is arranged in the water bath temperature control box, and an air inlet is provided on the side wall of the reactor body, and the air inlet is connected to the gas injection device.

6. The system for microwave decomposition of natural gas hydrates according to claim 5, characterized in that: The gas injection device comprises a gas cylinder, an air compressor, a booster pump and a gas storage tank connected by pipelines, and the gas inlet is connected to the gas storage tank.

7. The system for decomposing natural gas hydrate by microwave according to any one of claims 1 to 6, characterized in that: The side wall of the reactor body is also provided with an air outlet, which is connected to a drying pipe and a flow meter in sequence, and the flow meter is connected to the data acquisition and control device; The reactor top cover of the visual reactor is made of sapphire glass.

8. A method for decomposing natural gas hydrates by microwaves, using the system for decomposing natural gas hydrates by microwaves according to any one of claims 1 to 7, characterized in that: include: Fill the visual reactor with natural gas hydrate and set the temperature T for decomposing the natural gas hydrate. max and T min ; The microwave generating device is turned on, and when the data acquisition control device receives the temperature of the first temperature sensor reaching T max When the temperature of the first temperature sensor is lower than T min When a signal is received, the microwave generating device is controlled to be turned on until the natural gas hydrate in the visual reactor is completely decomposed.

9. The method according to claim 8, characterized in that When the microwave decomposition system for natural gas hydrate further includes a water bath temperature control box and a gas injection device, the step of filling the visible reactor with natural gas hydrate includes: The visual reactor is placed in the water bath temperature control box, the microwave enhancement device and the non-gaseous raw materials required for synthesizing natural gas hydrates are placed in the visual reactor, sealed and evacuated, and then the gas raw materials required for synthesizing the natural gas hydrates are injected into the visual reactor through the gas injection device. The temperature in the visual reactor is adjusted by controlling the temperature of the water bath temperature control box. When the temperature and pressure in the visual reactor reach the reaction conditions required for synthesizing the natural gas hydrate, a synthesis reaction is carried out to obtain the natural gas hydrate.

10. The method according to claim 9, characterized in that The gas in the gas injection device includes at least one of methane, ethane, and propane.

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