A multifunctional adiabatic reactor for natural gas hydrate simulation mining

Abstract

The present invention discloses a multifunctional insulated reactor for simulating the exploitation of natural gas hydrates. The reactor is mainly composed of a reactor body, a reactor cover, a temperature sensor, a pressure sensor, a resistance wire heating rod, a stirrer, and two layers of jackets outside the reactor body. The reactor cover is provided with a gas inlet and outlet, a temperature sensor, and a pressure sensor; the bottom of the reactor is provided with a liquid discharge port; a stirrer and a resistance wire heating rod are installed inside the reactor, and a detachable heat-insulating material is provided inside the top of the reactor; two layers of independent jackets are provided outside the reactor body, and both layers of jackets are provided with a circulating liquid inlet and outlet. The device creates an insulated environment inside the reactor by reducing the heat radiation and heat conduction inside and outside the reactor. The equipped electric heating rod can directly inject heat into the reactor. The multifunctional insulated reactor can be used for the exploitation experiments of natural gas hydrates such as pressure reduction, heat injection, and displacement in the laboratory.

Description

Technical Field

[0001] The invention relates to a multifunctional thermal insulation reactor for natural gas hydrate simulation mining, belonging to the field of new energy mining. Background Art

[0002] Natural gas hydrate is a non-stoichiometric cage-shaped solid compound generated by methane gas and water under low temperature and high pressure conditions. It is commonly found in deep sea strata and permafrost. In addition to its wide distribution, the reserves of methane hydrate are also huge. According to existing data, the amount of methane hydrate resources is estimated to be twice the total amount of carbon in traditional fossil fuels that have been proven worldwide. In order to meet the growing demand for energy, people have turned their attention to the fields of marine methane hydrate mining and deep drilling mining. However, how to economically, efficiently and safely extract natural gas from hydrates is a prerequisite for the large-scale utilization of this energy. Therefore, research on the mining of natural gas hydrates is in full swing at this stage.

[0003] Common methods for exploiting natural gas hydrates include heat shock method, pressure reduction method, inhibitor injection method and replacement method. Heat shock method and pressure reduction method decompose natural gas hydrates by increasing temperature and reducing pressure respectively; inhibitors are injected into the natural gas hydrate layer with certain chemical reagents, such as brine, methanol, ethylene glycol, propylene glycol, etc., thereby destroying the phase equilibrium conditions of the natural gas hydrate reservoir and promoting the decomposition of natural gas hydrates; CO2 replacement exploitation method mainly injects CO2 into the natural gas hydrate reservoir to replace the natural gas, and at the same time buries the CO2 gas in the form of hydrates on the seabed. In this way, methane can be exploited and CO2 can be sealed and reduced at the same time. Whether it is direct heat injection, pressure reduction, or replacement, the above various natural gas hydrate exploitation methods all involve energy change processes, and energy efficiency has also become an important indicator for measuring the economic feasibility of natural gas hydrate exploitation methods.

[0004] Obtaining the quantitative relationship between heat injection and heat production during natural gas hydrate exploitation is extremely valuable for guiding the hydrate exploitation process and improving the efficiency and economy of exploitation. At present, laboratory studies that exploit natural gas hydrates using methods such as heat injection often require heat balance. However, there is heat exchange between the reactor used in the experiment and the external environment. Therefore, the heat injected in the experiment is not completely absorbed and utilized. Some of the heat will be lost to the environment. As the external environment changes, the heat transfer rate between the reactor and the environment will also change, and the lost heat will also change. This is not conducive to the repeatability and accuracy of the experiment. Therefore, it is difficult to accurately obtain the quantitative relationship between the heat absorption and heat production of natural gas hydrates under existing experimental conditions. In order to avoid unnecessary energy loss, explore the quantitative relationship between heat injection and hydrate heat production, and study the natural gas hydrate displacement exploitation process in an adiabatic environment, it is particularly important to reduce the heat exchange inside and outside the reactor and improve the insulation of the reactor.

[0005] In order to solve the heat exchange problem in the natural gas hydrate production process, the present invention proposes a method of adding a vacuum layer and a heat absorption layer outside the reactor, which can create an insulating environment in the reactor to the greatest extent. Summary of the invention

[0006] The purpose of the present invention is to provide a multifunctional adiabatic reactor for natural gas hydrate simulation mining, which can provide an adiabatic environment for natural gas hydrate mining in the laboratory, overcome the energy exchange with the external environment during the hydrate mining process, and facilitate further research on the energy change during the natural gas hydrate mining process. The adiabatic reactor has reliable principles and is easy to operate.

[0007] The present invention is achieved through the following technical solutions.

[0008] A multifunctional insulated reactor for simulated mining of natural gas hydrates is mainly composed of a reactor body, a reactor cover, a temperature sensor, a pressure sensor, a resistance wire heating rod, a stirring rod and two layers of jackets on the reactor body. The reactor body and the reactor cover are both made of stainless steel 316, and the two are connected by flanges. The reactor body and the flange are connected by threads. There are bolts evenly distributed around the flange, and the sealing is achieved by tightening the nuts. The sealing is reliable and leak-free. The reactor cover is an integral flat cover. The reactor body and the reactor cover are sealed with metal gaskets. The design pressure is 20MPa.

[0009] The lid of the reactor is provided with gas inlet and outlet, temperature sensor and pressure sensor; the gas inlet and outlet are opened on the top of the reactor for air intake and exhaust, the temperature sensor and pressure sensor are used to monitor the temperature and pressure in the reactor in real time, the above sensor data are connected to the computer through the data acquisition instrument, the computer records and displays the temperature and pressure data in real time, and then obtains the specific situation of hydrate synthesis and mining, a safety bursting valve is installed behind the pressure sensor, which is a pressure relief safety device composed of a bursting disc and a pressure ring assembly, when the pressure difference inside the bursting disc reaches the predetermined pressure value at the predetermined temperature, the bursting disc can burst and release the pressure medium. The bottom of the reactor is provided with a liquid discharge port for discharging the liquid material in the reactor.

[0010] A stirring rod and a resistance wire heating rod are installed in the kettle. The stirring method is: the servo motor drives the external magnetic steel body to rotate, and the external magnetic steel body drives the internal magnetic steel body, the stirring shaft and the stirring blades to rotate through the magnetic lines, so as to achieve the purpose of stirring, and the stirring speed can be adjusted according to needs. The stirrer and the motor drive are connected by a magnetic stirrer. Due to its contactless transmission torque, static seals replace dynamic seals, which can completely solve the leakage problem existing in stirring; a heating rod with a heat injection power of 0-500W is also installed in the kettle. Different powers can be selected according to experimental requirements to inject heat into the reactor. Compared with external circulation and hot solution injection, the electric heat injection method can quantitatively and instantly inject the required heat into the kettle.

[0011] There are two independent jackets outside the kettle body, both of which are provided with circulating liquid inlet and outlet.

[0012] In the experimental stage of natural gas hydrate synthesis, where the temperature in the reactor needs to be controlled, the inner jacket is used as a temperature control layer, and its lower opening is connected to the liquid supply port of the water bath circulation equipment, and the upper opening is connected to the liquid return port of the water bath circulation equipment. The temperature in the reactor is controlled by controlling the set temperature of the water bath equipment.

[0013] During the heat-insulating operation, the heat-conducting medium in the inner jacket is emptied and the inner jacket is used as a heat-insulating layer.

[0014] There are two main ways of heat exchange between the reactor and the outside environment: heat conduction and heat radiation. In order to reduce the heat radiation between the reactor and the outside environment, the outer wall of the inner jacket is evenly coated with heat insulation and radiation protection coating.

[0015] In order to reduce the heat conduction efficiency during the insulation experiment, an external valve is opened at the upper part of the inner jacket and connected to a vacuum pump. After the heat-conducting medium in the inner jacket is emptied, it can be easily evacuated with a vacuum pump to enhance the insulation effect.

[0016] The inner jacket often still has a residual pressure of 10-20 Pa after the vacuum pump is evacuated. When the temperature difference between the inside and outside of the reactor is large, there is still a relatively obvious heat conduction between the inside of the reactor and the external environment. Therefore, another jacket is added outside the inner jacket. The heat transfer oil circulates in the jacket through the temperature control equipment, entering from the bottom and exiting from the top. The oil bath temperature is controlled by the temperature feedback from the reactor to the temperature control system. When the temperature in the reactor changes, the temperature of the oil bath in the outer jacket will also change with it, so that the temperature in the reactor and the circulation temperature of the outer jacket are always in a very close range, minimizing the heat transfer temperature difference. The heat of the external environment will be transferred to the medium in the outer jacket of the reactor and taken away, and will not directly exchange heat with the inside of the reactor.

[0017] In order to further enhance the thermal insulation effect and reduce the heat conduction at the top of the reactor, the top of the reactor is tightly filled with thermal insulation materials such as thermal insulation cotton, and the thermal insulation cotton reserves channels for components such as the stirring shaft and the heating rod.

[0018] The vacuum layer outside the reactor, the heat-insulating and radiation-proof coating, and the jacket outside the vacuum layer together create a relatively insulating environment inside the reactor, greatly reducing the heat exchange between the reactor and the external environment. During the experiment, the reactor can be regarded as an insulating container.

[0019] Compared with the existing device, the present invention has the following beneficial effects:

[0020] Under the premise of achieving stirring and electric heat injection in the reactor, a vacuum jacket is wrapped around the outside of the conventional natural gas hydrate experimental reactor. This measure can greatly reduce the heat conduction between the reactor and the external environment; in order to reduce the radiation heat transfer inside and outside the reactor, a firmly bonded heat-insulating and radiation-proof coating is evenly coated on the outer wall of the vacuum jacket. Under existing technical conditions, there is often a residual pressure of 10-20Pa in the vacuum layer. In order to further reduce the heat conduction inside and outside the reactor, a temperature control layer is added outside the vacuum layer. Its temperature is consistent with the temperature inside the reactor, which further reduces the heat conduction by reducing the heat transfer temperature difference. In addition, in order to reduce the heat dissipation of the top of the reactor, the top of the reactor is also filled with thermal insulation materials. The above measures together create an insulating environment for the reactor, meet the operational requirements of adiabatic reaction, and can be used for various experimental studies such as heat injection, pressure reduction, and displacement of natural gas hydrates. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of an adiabatic reactor for simulating mining of natural gas hydrates according to the present invention.

[0022] The components in the figure are as follows: motor outer magnetic steel body 1, temperature sensor 2, pressure sensor 3, nut and flange 4, kettle cover 5, outer jacket liquid outlet 6, kettle body 7, outer jacket 8, thermal insulation and radiation protection coating 9, inner jacket 10, inner jacket liquid inlet 11, lower discharge port 12, outer jacket liquid inlet 13, stirring rod 14, resistance wire heating rod 15, inner jacket liquid outlet 16, kettle top insulation material 17, kettle top gas inlet and outlet 18, heating rod interface 19. DETAILED DESCRIPTION

[0023] The present invention is further described in detail below with reference to the accompanying drawings and specific implementation modes.

[0024] like Figure 1As shown, a multifunctional insulated reactor for simulated mining of natural gas hydrates includes a reactor body 7, a reactor cover 5, a temperature sensor 2, a pressure sensor 3, a resistance wire heating rod 15, a stirring rod 14, and two layers of jackets outside the reactor body; the reactor body 7 and the reactor cover 5 are both made of stainless steel 316, and the two are connected by a flange 4, and the reactor body 7 and the reactor cover 5 are sealed with a metal gasket; the reactor cover 5 is provided with a gas inlet and outlet 18, a temperature sensor 2, and a pressure sensor 3; the bottom of the reactor is provided with a liquid discharge port 12; a stirring rod 14 and a resistance wire heating rod 15 are installed in the reactor; and two layers of jackets are provided outside the reactor body, which are independent of each other. The two layers of jackets outside the reactor body are an outer jacket 8 and an inner jacket 10, and the inner jacket 10 and the outer jacket 8 are both hollow structures. The bottom and the upper end of the two layers of jackets are provided with inlet and outlet channels. The inlet and outlet passages include an outer jacket liquid outlet 6, an inner jacket liquid inlet 11, an outer jacket liquid inlet 13 and an inner jacket liquid outlet 16; the outer jacket liquid outlet 6 and the inner jacket liquid outlet 16 are respectively arranged on the side wall of the reactor, the inner jacket liquid inlet 11 and the outer jacket liquid inlet 13 are arranged on the bottom of the reactor, and the two jackets are independent of each other and are not connected to each other; the outer jacket liquid outlet 6 is connected to the hollow structure of the outer jacket 8; the inner jacket liquid outlet 16 is connected to the hollow structure of the inner jacket 10; the inner jacket liquid inlet 11 is connected to the hollow structure of the inner jacket 10; the outer jacket liquid inlet 13 is connected to the hollow structure of the outer jacket 8. The inner jacket 10 is connected to a vacuum pump, and the residual pressure of the inner jacket is made lower than 10Pa by the vacuum pump. The outer wall of the inner jacket 10 is evenly coated with a heat-insulating, heat-preserving and radiation-proof coating 9, and the heat-insulating, radiation-proof coating 9 is a silver coating. The temperature sensor 2 is used as a control temperature to feed back to the temperature control system in real time, thereby controlling the temperature of the circulating liquid in the outer jacket. The temperature control range is from -10°C to 120°C. After stable operation, the temperature difference between the inner and outer jackets of the kettle does not exceed 0.5°C. The stirring outer magnetic steel body 1 drives the inner magnetic steel body, the stirring shaft and the stirring blades to rotate through the magnetic lines of force, thereby achieving the purpose of stirring. The stirring speed is 0-1000r / min. An electric heating rod 15 with a heat injection power of 0-500W is installed in the kettle. The present invention also includes a kettle top insulation material 17, which is fixed to the top of the reactor; the chemical composition of the kettle top insulation material 17 is polyurethane. The present invention also includes a heating rod interface 19, which is located on the top of the kettle and is sealed with the kettle through a nut; the heating rod interface 19 is connected to the electric heating rod 15, and the electric heating rod 15 is connected to an external power supply through the heating rod interface 19.

[0025] Example 1

[0026] This embodiment provides a method for synthesizing natural gas hydrates using the multifunctional insulated reactor and verifying the insulation performance of the reactor.

[0027] The natural gas hydrate simulation mining adiabatic reactor and its supporting pipelines, gas cylinders, temperature control equipment and data acquisition system can be used to conduct natural gas hydrate synthesis and subsequent adiabatic mining experiments. The experimental operation and process are as follows:

[0028] Open the lid of the reactor, add distilled water into the reactor, tighten the nut, and seal the reactor. Then input methane gas to 10MPa through the air inlet at the top of the reactor, turn on the stirring paddle, set the speed to 300r / min, and then turn on the water bath circulation equipment (Wuxi Guanya high and low temperature constant temperature water bath SUNDI320) for temperature control. The liquid supply port of the water bath equipment is connected to the liquid inlet of the inner jacket, and the return liquid port is connected to the liquid outlet of the inner jacket. The temperature in the reactor is controlled by circulating the heat-conducting medium in the inner jacket, and the control temperature is set to 2°C. After the above operations are completed, the temperature and pressure data in the reactor are monitored and recorded in real time to obtain the progress of hydrate formation. After the pressure in the reactor is stabilized at 4MPa, the hydrate formation is considered complete, and then the connection between the inner jacket and the water bath circulation equipment is released, and the heat transfer medium in the inner jacket is emptied, the lower opening of the inner jacket is sealed, and the jacket is evacuated through the upper opening of the inner jacket using a vacuum pump. After the pressure in the inner jacket is lower than 10pa, the upper opening of the inner jacket is sealed, thus forming a vacuum system. After that, the liquid inlet and outlet of the outer jacket are connected to the liquid supply port and liquid return port of the water bath equipment respectively, and the heat transfer medium is circulated in the outer jacket. The control temperature of the water bath equipment is fed back by the temperature sensor in the reactor, which is consistent with the real-time temperature in the reactor, minimizing the temperature difference between the inside and outside of the reactor and achieving thermal insulation in the reactor. When the hydrate temperature in the kettle is 2°C, the external environment temperature is 30°C and no other operations are performed, the adiabatic reactor can make the daily decomposition of hydrates in the kettle less than 5%. The hydrate generation and decomposition amounts in the kettle can be calculated by the PR equation using the obtained temperature and pressure data. In addition, under the conditions of the kettle temperature of 2°C and the ambient temperature of 30°C, the reactor can make the natural temperature rise rate in the reactor less than 1°C / day, meeting the requirements of the hydrate adiabatic experiment.

[0029] Example 2

[0030] This embodiment provides a method for reducing the pressure of hydrate production using the adiabatic reactor.

[0031] As described in Example 1, after the formation of hydrates in the reactor is completed, a series of adiabatic operations are performed and then a pressure reduction test is performed. The gas outlet at the top of the reactor is opened, the pressure in the reactor is released to the target pressure required for the experiment, and then the gas outlet valve is closed to perform a decompression decomposition experiment of the hydrate. Since the decomposition of hydrates is an endothermic process, the pressure in the adiabatic reactor will gradually increase with the decomposition of the hydrates, while the temperature will decrease. Real-time temperature and pressure data are obtained using temperature and pressure sensors, and by analysis we can obtain the law of hydrate decomposition in an adiabatic environment. In addition, if a back pressure valve and a gas flow meter are connected to the gas outlet, the constant pressure decomposition process of hydrates in an adiabatic environment can be further studied.

[0032] Example 3

[0033] This embodiment provides a method for heat injection production of hydrates using the adiabatic reactor.

[0034] As described in Example 1, after the hydrate formation in the reactor is completed, a series of adiabatic operations are performed to conduct heat injection experimental research. The specific operations are: turn on the electric heating rod in the reactor, select the required power to inject heat into the materials in the reactor, and use the temperature and pressure sensor to monitor the temperature and pressure data in the reactor in real time until the pressure tends to stabilize and the hydrate is completely decomposed. Subsequently, the total heat injection amount can be obtained using the known heat injection power and heat injection time. The adiabatic reactor can maximize the use of the injected heat in the reactor, reduce energy loss, and facilitate theoretical research on hydrate heat injection decomposition experiments and quantitative calculations of related energy.

[0035] Example 4

[0036] This embodiment provides a method for hydrate replacement production using the adiabatic reactor.

[0037] As described in Example 1, after the hydrate formation in the reactor is completed, a series of adiabatic operations are performed to carry out displacement experimental research. The specific operation is: quickly empty the remaining methane gas in the reactor, then introduce displacement gas (such as carbon dioxide) to a specified pressure, and then conduct an adiabatic displacement mining experiment of natural gas hydrate in the reactor. Since the displacement process of methane hydrate is an exothermic process, there will theoretically be a certain amount of heat accumulation in the reactor as the displacement reaction proceeds. The temperature change caused by the heat can be reflected and recorded by the temperature sensor, and the displacement mining effect can be obtained by taking an appropriate amount of gas in the reactor for gas chromatography analysis. In addition, a heating rod can be used to inject appropriate heat during the displacement process to improve the displacement efficiency. The reactor can be used to study the displacement law of methane hydrate in an adiabatic environment, which can provide theoretical guidance for the actual exploitation of natural gas hydrates.

Claims

1. A method for using a multifunctional adiabatic reactor for simulated mining of natural gas hydrates, characterized in that: The reaction kettle used in the method comprises a temperature sensor (2), a pressure sensor (3), a kettle cover (5), a kettle body (7), a resistance wire heating rod (15), a stirring rod (14) and a two-layer jacket outside the kettle body; the kettle body (7) and the kettle cover (5) are both made of stainless steel 316, and the two are connected by a flange (4), and the kettle body (7) and the kettle cover (5) are sealed with a metal gasket; the kettle cover (5) is provided with a gas inlet and outlet (18), a temperature sensor (2) and a pressure sensor (3); a liquid discharge port (12) is opened at the bottom of the kettle body (7); a stirring rod (14) and a resistance wire heating rod (15) are installed in the kettle; and a two-layer jacket with inner and outer layers independent of each other is provided outside the kettle body; The two jackets outside the kettle body are an outer jacket (8) and an inner jacket (10), and both the inner jacket (10) and the outer jacket (8) are hollow structures; The bottom and sides of the two-layer jacket are provided with inlet and outlet passages; The inlet and outlet passages include an outer jacket liquid outlet (6), an inner jacket liquid inlet (11), an outer jacket liquid inlet (13) and an inner jacket liquid outlet (16); the outer jacket liquid outlet (6) and the inner jacket liquid outlet (16) are respectively arranged on the side wall surface of the reaction kettle, the inner jacket liquid inlet (11) and the outer jacket liquid inlet (13) are arranged on the bottom surface of the reaction kettle, and the two jackets are independent of each other and are not connected to each other; the outer jacket liquid outlet (6) is connected to the hollow structure of the outer jacket (8); the inner jacket liquid outlet (16) is connected to the hollow structure of the inner jacket (10); the inner jacket liquid inlet (11) is connected to the hollow structure of the inner jacket (10); the outer jacket liquid inlet (13) is connected to the hollow structure of the outer jacket (8); The inner jacket (10) is connected to a vacuum pump, and the vacuum pump is used to make the residual pressure of the inner jacket lower than 10 Pa; The outer wall of the inner jacket (10) is evenly coated with a heat-insulating, thermal-preserving and radiation-proof coating (9), wherein the heat-insulating, thermal-preserving and radiation-proof coating (9) is a silver coating; The temperature sensor (2) is used as a temperature control component to feed back the temperature to the temperature control system in real time, thereby controlling the temperature of the circulating liquid in the outer jacket. After stable operation, the temperature difference between the inner and outer jackets of the kettle does not exceed 0.5°C. The outer magnetic steel body (1) of the motor drives the inner magnetic steel body, the stirring shaft and the stirring rod to rotate through the magnetic lines, thereby achieving the purpose of stirring; It also includes a kettle top insulation material (17), wherein the kettle top insulation material (17) is fixed to the top of the reactor; the chemical composition of the kettle top insulation material (17) is polyurethane; It also includes a heating rod interface (19), the heating rod interface (19) is located at the top of the kettle and is connected and sealed with the kettle via a nut; the heating rod interface (19) is connected to the resistance wire heating rod (15), and the resistance wire heating rod (15) is connected to an external power source via the heating rod interface (19); the heating power of the resistance wire heating rod (15) is 0-500W; The method for using the reactor is as follows: open the reactor cover of the reactor, add distilled water into the reactor, tighten the nut, and seal the reactor; then input methane gas to 10MPa through the gas inlet and outlet at the upper end of the reactor, turn on the stirring rod, set the speed to 300r / min, and then turn on the water bath circulation device to control the temperature, the liquid supply port of the water bath circulation device is connected to the liquid inlet of the inner jacket, and the liquid return port is connected to the liquid outlet of the inner jacket, and the temperature in the reactor is controlled by circulating the heat-conducting medium in the inner jacket, and the control temperature is set to 2°C; after the above operations are completed, real-time monitoring is performed; the temperature and pressure data in the reactor are recorded to obtain the progress of hydrate formation; and the pressure in the reactor is stabilized at 4MPa After that, the hydrate formation is considered to be completed, and then the connection between the inner jacket and the water bath circulation equipment is released, and the heat-conducting medium in the inner jacket is emptied, the lower opening of the inner jacket is sealed, and the jacket is evacuated through the upper opening of the inner jacket by a vacuum pump. After the pressure in the inner jacket is lower than 10 Pa, the upper opening of the inner jacket is sealed, thus forming a vacuum system; then the liquid inlet and liquid outlet of the outer jacket are connected to the liquid supply port and liquid return port of the water bath equipment respectively, and the heat-conducting medium is circulated in the outer jacket, and the control temperature of the water bath equipment is fed back by the temperature sensor in the reactor, which is consistent with the real-time temperature in the reactor to achieve thermal insulation in the reactor.

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