CN110554038B - Device and method capable of realizing synchronous mesoscopic observation of formation and decomposition of gas hydrate - Google Patents
Device and method capable of realizing synchronous mesoscopic observation of formation and decomposition of gas hydrate Download PDFInfo
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- CN110554038B CN110554038B CN201910643658.7A CN201910643658A CN110554038B CN 110554038 B CN110554038 B CN 110554038B CN 201910643658 A CN201910643658 A CN 201910643658A CN 110554038 B CN110554038 B CN 110554038B
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- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/84—Systems specially adapted for particular applications
- G01N2021/8405—Application to two-phase or mixed materials, e.g. gas dissolved in liquids
Abstract
The invention discloses a device and a method capable of realizing synchronous mesoscopic observation of formation and decomposition of a gas hydrate. The device comprises a gas cylinder, a vacuum pump, a gas storage tank, a low-temperature constant-temperature tank, a high-pressure visual reaction kettle, a seal box, a pressure-stabilizing gas inlet system, a data acquisition instrument, a real-time display system and a pressure-stabilizing exhaust system. The high-pressure visible reaction kettle comprises a plurality of transparent sapphire inner cylinders, an upper flange, a lower flange and a quartz outer cylinder; the sapphire inner cylinder is of a hollow structure and is arranged in the transparent quartz outer cylinder, and the upper flange and the lower flange are used for sealing the inner cylinder and the outer cylinder; the upper flange and the lower flange are provided with a plurality of interfaces. Each sapphire inner cylinder can simultaneously carry out the formation and the decomposition of the gas hydrate. The drying agent is placed in the sealing box, and the fog can be avoided by observing the drying agent in the sealing box. The invention can research the formation and decomposition of the gas hydrate under high pressure and low temperature, simultaneously carry out a plurality of groups of experiments, realize on-line real-time synchronous mesoscopic observation of the appearance and dynamic change of the formation and decomposition of the gas hydrate, carry out analysis by image processing software, improve the operation efficiency and reduce the influence of the nucleation and growth randomness of the hydrate.
Description
Technical Field
The invention relates to an experimental device for forming and decomposing a gas hydrate, in particular to an experimental device for synchronously observing the forming and decomposing of the gas hydrate through mesoscopic observation, and belongs to the technical field of petroleum and natural gas.
Background
The gas hydrate is a non-stoichiometric cage-shaped crystal substance formed by water and small molecule gas (methane, ethane, carbon dioxide, nitrogen, hydrogen sulfide and the like) under certain temperature and pressure, and is also called as a cage-shaped hydrate. The non-stoichiometric inclusion complex is formed by mutually combining host molecules, namely water molecules with hydrogen bonds to form a cage-shaped gap and enclosing guest molecules in the cage-shaped gap. At present, research on hydrates focuses on gas storage and transportation, cold accumulation and energy storage, gas separation, exploration and exploitation and the like. The natural gas/hydrogen storage and transportation needs to improve the generation rate of hydrate and improve the gas storage capacity; hydrate selective generation is required for hydration separation; hydrate inhibition requires delaying hydrate formation; exploration and exploitation of hydrates are problems related to formation stability and the like, and gas yield needs to be improved. The formation and decomposition of hydrates involve thermodynamics, kinetics, heat and mass transfer, etc.
The formation and decomposition process of the hydrate is observed, the formation and decomposition mechanism of the gas hydrate can be deeply understood, and the thermodynamics, the kinetics, the heat transfer and the mass transfer mechanism of the formation and decomposition process of the hydrate are further clarified. For example, the formation and decomposition of the hydrate are observed in the porous medium, the occurrence form, particle migration and other characteristics of the hydrate can be researched, and the exploration and exploitation of the hydrate are theoretically guided; the formation and decomposition of the hydrate are observed in the heat and mass transfer material, and the influence mechanism of the thermal mass strengthening material on the hydration process can be explored. At present, a great deal of experimental research on the formation and decomposition of gas hydrate is carried out, most of the experimental research only considers the change of temperature and pressure in the process of formation and decomposition of the hydrate, and a reaction device is not visual and cannot intuitively reflect the nucleation and growth process of the hydrate. In addition, the growth and distribution of hydrates were studied by optical microscopy, most using cyclopentane and TBAB (tetrabutylammonium bromide) to form hydrates at atmospheric pressure, which, although eliminating the pressure limitation, are far from the conditions for gas hydrate formation. The nucleation and growth of the hydrate have certain randomness, and a single experiment cannot reflect the growth and decomposition rules and characteristics of the hydrate, particularly under the complex conditions of a porous medium and a thermal mass strengthening material.
Disclosure of Invention
The invention aims to provide a device capable of realizing synchronous mesoscopic observation of formation and decomposition of gas hydrate, aiming at the defects in the prior art.
The invention also provides a method for synchronously observing the formation and decomposition of the gas hydrate through mesoscopy.
The gas is adopted for hydration, and the formation and the decomposition of the gas hydrate can be researched under high pressure and low temperature. The imaging function of the real-time display system equipment is utilized to capture the change of the shape of the hydrate in real time, and the formation and decomposition processes of the hydrate are synchronously observed in real time.
The invention is realized by the following technical scheme:
a device capable of realizing synchronous mesoscopic observation of formation and decomposition of gas hydrate comprises a low-temperature thermostatic bath, a high-pressure visual reaction kettle, a sealing box, a pressure-stabilizing air inlet system, a data acquisition instrument, a real-time display system and a pressure-stabilizing exhaust system.
The low-temperature constant-temperature tank is connected with the high-pressure visual reaction kettle and provides stable working temperature for the reaction device; the high-pressure visible reaction kettle is divided into a plurality of sapphire inner cylinders and can resist high pressure of 16 MPa; the pressure stabilizing air inlet system comprises a gas storage tank, a plurality of valves, a plurality of secondary pressure reducing valves and a gas flowmeter; the real-time display system consists of a plurality of electronic endoscopes and a computer, and can synchronously observe the formation and decomposition of gas hydrate in the high-pressure visual reaction kettle in a mesoscopic manner; the pressure stabilizing exhaust system comprises a plurality of valves, a plurality of gas backpressure valves and a gas flowmeter.
Further, circulating liquid is filled in the low-temperature constant-temperature tank, and the circulating liquid is glycol solution.
Further, the high-pressure visible reaction kettle is divided into three sapphire inner cylinders (three are not limited).
Furthermore, three sapphire inner cylinders (three are not limited) of the high-pressure visual reaction kettle are arranged in a quartz outer cylinder, and the outer cylinder is provided with a circulating liquid inlet and a circulating liquid outlet which are connected with circulating liquid of a low-temperature constant-temperature tank.
Further, the visual reation kettle of high pressure, both ends set up the flange about are used for sealedly, and every inner tube bottom installation filter screen sets up the air inlet, and gaseous bottom entering visual reation kettle of high pressure is seted up two holes respectively at the top, connects the thermal resistance and regards as the gas outlet.
Furthermore, the outside of the sealing box is provided with a heat insulation material, so that the loss of heat of a reaction system is reduced, and a drying agent is arranged in the sealing box, so that the external air can be isolated from contacting and absorbing moisture, and the formation of water mist is prevented.
Further, the pressure of a gas storage tank in the pressure stabilizing gas inlet system is higher than the pressure in the high-pressure visual reaction kettle, the pressure of the gas in the high-pressure visual reaction kettle can be respectively controlled through a secondary pressure reducing valve, a constant pressure state is maintained, and the gas consumption of the hydration reaction can be respectively recorded through a gas flowmeter in the hydrate formation process.
Furthermore, the data acquisition instrument is connected with the thermal resistor, the pressure sensor and the gas flowmeter and is connected with the computer, and once data can be acquired within 10 s.
Furthermore, an electron microscope in the real-time display system is connected with a computer, so that the morphology and the dynamic change of the hydrate in the reaction kettle can be acquired on line in real time and analyzed through image processing software.
Furthermore, the pressure stabilizing exhaust system can respectively control the decomposition pressure in each sapphire inner cylinder through a gas backpressure valve and maintain a constant pressure state, and respectively record the hydrate decomposition gas amount in each inner cylinder through a gas flowmeter.
The high-pressure visualization device can realize synchronous mesoscopic observation of the formation and decomposition of the gas hydrate and comprises the following steps:
(1) respectively filling porous media (or thermal mass strengthening materials) into three sapphire cylinders (three are not limited), and then adding the required solution to reach the saturation (or gas-liquid ratio) required by the experiment;
(2) opening a vacuum pump connecting valve, and then starting a vacuum pump to pump vacuum;
(3) closing a valve connected with the vacuum pump, closing an air inlet main valve of the high-pressure reaction kettle, opening a gas steel cylinder valve, filling reaction gas into a gas storage tank, and closing an air inlet gas circuit valve;
(4) opening a main air inlet valve of the high-pressure reaction kettle, opening branch valves respectively, opening a secondary pressure reducing valve, closing the main air inlet valve of the high-pressure reaction kettle after a small amount of reaction gas is filled into the high-pressure visual reaction kettle, opening branch air exhaust path valves, discharging the reaction gas carrying a small amount of air out of the reaction device, repeatedly filling and discharging the gas until all the air in the device is discharged, and finally closing the branch valves;
(5) opening the low-temperature constant-temperature tank to the set temperature, opening the main air inlet valve of the high-pressure reaction kettle after the temperature is stable, opening the secondary pressure reducing valve to the required experimental pressure, and filling the high-pressure visible reaction kettle with methane gas at the required experimental pressure;
(6) and opening a real-time display system to capture the appearance and dynamic change of the hydrate in the formation process.
(7) After the hydrate is formed, closing the gas inlet main valve of the high-pressure reaction kettle, opening the gas back pressure valves of the branches to set pressure, decomposing the hydrate at the same temperature and constant pressure required by an experiment, and capturing the appearance and dynamic change of the hydrate in the decomposition process.
The invention has the following innovation points:
1. the invention can resist high pressure and realize the formation and decomposition of gas hydrate at high pressure and low temperature;
2. the invention can directly observe the formation and decomposition process of the gas hydrate, capture the growth and decomposition appearance and dynamic change of the hydrate, and is convenient and intuitive;
3. the invention can synchronously observe the formation and decomposition of three groups (without limiting three groups) of gas hydrates, shorten the experimental period, and reduce the influence of the randomness of the nucleation and growth of the hydrates, so that the observation result has higher reliability;
4. the invention adopts the low-temperature constant-temperature tank, the pressure-stabilizing air inlet system and the pressure-stabilizing air outlet system, can realize the formation and decomposition of the hydrate under constant temperature and constant pressure, and obtains the rate of formation and decomposition of the hydrate, thereby exploring the kinetics of formation and decomposition of the hydrate.
Drawings
FIG. 1 is a schematic structural diagram of the apparatus for realizing simultaneous mesoscopic observation of formation and decomposition of gas hydrates in a porous medium according to the present invention.
FIG. 2 is a top view of a high pressure visual reaction vessel.
FIG. 3 is a dynamic process of gas hydrate formation in quartz sand (50 μm).
Shown in the figure are: the gas cylinder 1, the pressure reducing valve 2, the vacuum pump 3, the gas storage tank 4, the low-temperature thermostatic bath 5, the first secondary pressure reducing valve 61, the second secondary pressure reducing valve 62, the third secondary pressure reducing valve 63, the first gas flowmeter 71, the second gas flowmeter 72, the third gas flowmeter 73, the fourth gas flowmeter 141, the fifth gas flowmeter 142, the sixth gas flowmeter 143, the high-pressure reaction vessel 9, the seal box 10, the first thermal resistor 111, the second thermal resistor 112, the third thermal resistor 113, the first pressure sensor 121, the second pressure sensor 122, the third pressure sensor 123, the first back pressure valve 131, the second back pressure valve 132, the third back pressure valve 133, the data collector 15, the computer 16, and the valves V1-V9, the first electronic endoscope 81, the second electronic endoscope 82, and the third electronic endoscope 83.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
A device capable of realizing synchronous mesoscopic observation of formation and decomposition of gas hydrate comprises a gas cylinder 1, a vacuum pump 3, a gas storage tank 4, a low-temperature thermostatic bath 5, a high-pressure visual reaction kettle 9, a seal box 10, a pressure-stabilizing gas inlet system, a data acquisition instrument 15, a real-time display system and a pressure-stabilizing exhaust system;
the low-temperature constant-temperature tank 5 is connected with the high-pressure visual reaction kettle 9 and provides stable working temperature for the reaction device;
the high-pressure visible reaction kettle 9 comprises a plurality of sapphire inner cylinders and can resist high pressure of 16 MPa; the high-pressure visible reaction kettle 9 is positioned in the seal box 10;
the pressure stabilizing air inlet system comprises a gas storage tank 4, a valve, a secondary pressure reducing valve and a gas flowmeter; the gas storage tank 4 is positioned inside the low-temperature thermostatic bath 5, and the gas storage tank 4 is respectively connected with the gas bottle 1 and the vacuum pump 3 through pipelines; the gas storage tank 4 is connected with the sapphire inner cylinder through a guide pipe; the secondary pressure reducing valve is connected with the gas flowmeter;
the real-time display system consists of a plurality of electronic endoscopes and a computer 16 and can synchronously observe the formation and decomposition of gas hydrate in the high-pressure visual reaction kettle in a mesoscopic manner; the electronic endoscope is arranged inside the high-pressure visual reaction kettle 9 and the seal box 10; the computer 16 is connected with the electronic endoscope;
the pressure stabilizing exhaust system comprises a valve, a gas backpressure valve and a gas flowmeter; the valve is connected with an outlet pipeline of the high-pressure visible reaction kettle; the valves are respectively connected with the gas back pressure valve; the gas back pressure valve is respectively connected with the gas flowmeter;
the data acquisition instrument 15 is respectively connected with the gas flowmeter, the pressure sensor and the thermal resistor. And circulating liquid is filled in the low-temperature constant-temperature tank 5, and the circulating liquid is glycol solution. The present embodiment further includes a pressure reducing valve 2; the pressure reducing valve 2 is located on a pipeline between the gas cylinder 1 and the gas storage tank 4. The high-pressure visible reaction kettle 9 is divided into 1-10 sapphire inner cylinders (3 are adopted in the embodiment). Three sapphire inner cylinders (three without limitation) of the high-pressure visual reaction kettle 9 are arranged in a quartz outer cylinder, and the outer cylinder is provided with a circulating liquid inlet and a circulating liquid outlet which are connected with circulating liquid of a low-temperature constant-temperature tank. The visual reation kettle 9 of high pressure, both ends set up the flange about are used for sealedly, and every inner tube bottom installation filter screen sets up the air inlet, and gas gets into visual reation kettle 9 of high pressure from the bottom, and two holes are seted up respectively at the top, connect the thermal resistance and regard as the gas outlet. The polyurethane heat insulation material is arranged outside the seal box 10, so that the loss of heat of a reaction system is reduced, and the drying agent is arranged inside the seal box, so that the contact of outside air can be isolated, moisture can be absorbed, and the formation of water mist can be prevented. The data acquisition instrument 15 is connected with the thermal resistor, the pressure sensor and the gas flowmeter and is connected with the computer 16, and can acquire data once in 10 s. The first electronic endoscope 81, the second electronic endoscope 82 and the third electronic endoscope 83 in the real-time display system are connected with the computer 16, so that the morphology and dynamic change of the hydrate in the reaction kettle can be acquired on line in real time, and the analysis is carried out through image processing software. The high-pressure visual reaction kettle 9 is divided into 3 sapphire inner cylinders, and a first thermal resistor 111, a second thermal resistor 112 and a third thermal resistor 113 are respectively arranged at outlet pipelines of the sapphire inner cylinders; the gaseous back-pressure valves comprise a first gaseous back-pressure valve 131, a second gaseous back-pressure valve 132 and a third gaseous back-pressure valve 133; the gas flow meters include a fourth gas flow meter 141, a fifth gas flow meter 142, and a sixth gas flow meter 143; the pressure stabilizing exhaust system controls the decomposition pressure in each sapphire inner cylinder through a first gas backpressure valve 131, a second gas backpressure valve 132 and a third gas backpressure valve 133 respectively and maintains a constant pressure state, and records the amount of hydrate decomposition gas in each inner cylinder through a first gas flowmeter 141, a second gas flowmeter 142 and a third gas flowmeter 143 respectively; a first pressure sensor 121, a second pressure sensor 122 and a third pressure sensor 123 are respectively arranged on a pipeline between the gas backpressure valve and the thermal resistor; the pressure of a gas storage tank 4 in the pressure stabilizing gas inlet system is higher than the pressure in the high-pressure visible reaction kettle 9, the gas pressure in the high-pressure visible reaction kettle 9 is controlled through a first secondary pressure reducing valve 61, a second secondary pressure reducing valve 62 and a third secondary pressure reducing valve 63 respectively, the constant pressure state is maintained, and the gas consumption of the hydration reaction can be recorded through a first gas flowmeter 71, a second gas flowmeter 72 and a third gas flowmeter 73 respectively in the hydrate formation process.
Example 1
A method for realizing synchronous mesoscopic observation of gas hydrate formation and decomposition based on the device comprises the following steps:
(1) filling the same porous medium into three sapphire cylinders respectively, adding 3.5 wt% of NaCl solution to simulate seawater until the seawater is saturated to 100%, and sealing the reaction kettle;
(2) opening valves V2 and V3 in the device, opening valve V1, and starting a vacuum pump to vacuumize for 3 min;
(3) closing the stop valve V1, closing the vacuum pump, closing the valve V3, opening the pressure reducing valve V2 after opening the main valve of the gas steel cylinder, filling methane gas into the gas storage tank to 14MPa, and sequentially closing the valve V2, the pressure reducing valve 2 and the main valve of the steel cylinder;
(4) opening a valve V3, opening branch valves V4, V5 and V6 respectively, opening secondary reducing valves 61, 62 and 63 until the pressure is 0.05MPa, filling a small amount of methane gas into the high-pressure visible reaction kettle, closing a stop valve V3, opening branch valves V7, V8 and V9, discharging the methane gas carrying a small amount of air out of the reaction device, repeatedly filling and discharging the methane gas for 3 times until all the air in the device is discharged, and finally closing branch valves V7, V8 and V9;
(5) opening the low-temperature constant-temperature tank, setting the temperature to be 275.15K, opening a valve V3 after the temperature is stabilized for 1h, opening secondary pressure reducing valves 61, 62 and 63 until the pressure is 10MPa, and filling methane gas with the pressure of 10MPa into the high-pressure visible reaction kettle;
(6) and opening a real-time display system, capturing the appearance and dynamic change of the hydrate in the formation process of the same porous medium, comparing the growth characteristics of the hydrate in the porous medium under the same condition, and reducing the influence of the nucleation randomness of the hydrate, wherein the dynamic change process of the formation of one group of hydrates is shown in figure 3.
(7) After the hydrate is formed, closing the valve V3, opening the gas back pressure valves 131, 132 and 133 of each branch to the set pressure of 1MPa, so that the hydrate is decomposed at constant temperature and constant pressure, capturing the morphology and dynamic change of the decomposition process of the hydrate in the same porous medium, and comparing the decomposition characteristics of the hydrate in the porous medium under the same conditions.
Example 2
A method for realizing synchronous mesoscopic observation of gas hydrate formation and decomposition in a porous medium based on the device comprises the following steps:
(1) filling different porous media (or thermal mass strengthening materials) into the three sapphire cylinders respectively, adding SDS solution until the saturation is 100%, and sealing the reaction kettle;
(2) opening valves V2 and V3 in the device, opening valve V1, and starting a vacuum pump to vacuumize for 3 min;
(3) closing the stop valve V1, closing the vacuum pump, closing the valve V3, opening the pressure reducing valve V2 after opening the main valve of the gas steel cylinder, filling methane gas into the gas storage tank to 14MPa, and sequentially closing the valve V2, the pressure reducing valve 2 and the main valve of the steel cylinder;
(4) opening a valve V3, opening branch valves V4, V5 and V6 respectively, opening secondary reducing valves 61, 62 and 63 until the pressure is 0.05MPa, filling a small amount of methane gas into the high-pressure visible reaction kettle, closing a stop valve V3, opening branch valves V7, V8 and V9, discharging the methane gas carrying a small amount of air out of the reaction device, repeatedly filling and discharging the methane gas for 3 times until all the air in the device is discharged, and finally closing branch valves V7, V8 and V9;
(5) opening the low-temperature constant-temperature tank, setting the temperature to be 275.15K, opening a valve V3 after the temperature is stabilized for 1h, opening secondary pressure reducing valves 61, 62 and 63 until the pressure is 10MPa, and filling methane gas with the pressure of 10MPa into the high-pressure visible reaction kettle;
(6) and opening a real-time display system, capturing the appearance and dynamic change of the formation process of the hydrate in different porous media (or thermal mass reinforced materials), and comparing the growth characteristics of the hydrate in different porous media (or thermal mass reinforced materials) under the same condition.
(7) After the hydrate is formed, the valve V3 is closed, the gas back pressure valves 131, 132 and 133 of each branch are opened to the set pressure of 1MPa, so that the hydrate is decomposed at constant temperature and constant pressure, the morphology and dynamic changes of the hydrate in the decomposition process of different porous media (or thermal mass reinforced materials) are captured, the decomposition characteristics of the hydrate in different porous media (or thermal mass reinforced materials) under the same conditions are compared, and the experimental operation efficiency can be improved by simultaneously carrying out three groups of experiments.
Example 3
A method for realizing synchronous mesoscopic observation of gas hydrate formation and decomposition in a porous medium based on the device comprises the following steps:
(1) filling the same porous medium into three sapphire cylinders respectively, adding 3.5 wt% of NaCl solution to simulate seawater until the seawater is saturated to 100%, and sealing the reaction kettle;
(2) opening valves V2 and V3 in the device, opening valve V1, and starting a vacuum pump to vacuumize for 3 min;
(3) closing the stop valve V1, closing the vacuum pump, closing the valve V3, opening the pressure reducing valve V2 after opening the main valve of the gas steel cylinder, filling methane gas into the gas storage tank to 14MPa, and sequentially closing the valve V2, the pressure reducing valve 2 and the main valve of the steel cylinder;
(4) opening a valve V3, opening branch valves V4, V5 and V6 respectively, opening secondary reducing valves 61, 62 and 63 until the pressure is 0.05MPa, filling a small amount of methane gas into the high-pressure visible reaction kettle, closing a stop valve V3, opening branch valves V7, V8 and V9, discharging the methane gas carrying a small amount of air out of the reaction device, repeatedly filling and discharging the methane gas for 3 times until all the air in the device is discharged, and finally closing branch valves V7, V8 and V9;
(5) opening the low-temperature constant-temperature tank, setting the temperature to be 275.15K, opening a valve V3 after the temperature is stabilized for 1h, then respectively opening secondary pressure reducing valves 61, 62, 63 to 8, 9 and 10MPa, and respectively filling 8, 9 and 10MPa of methane gas into the high-pressure visible reaction kettle;
(6) and opening a real-time display system, capturing the appearance and dynamic change of the hydrate in the same porous medium in the formation process, and comparing the growth characteristics of the hydrate in the porous medium under different conditions.
(7) After the hydrate is formed, the valve V3 is closed, the gas back pressure valves 131, 132, 133 of each branch are opened to 1, 2 and 3MPa, so that the hydrate is decomposed at constant temperature and constant pressure under different pressure conditions, the appearance and dynamic change of the hydrate in the same porous medium in the decomposition process under different conditions are captured, the decomposition characteristics of the hydrate in the porous medium under different conditions are compared, and the experimental operation efficiency can be improved by simultaneously performing three groups of experiments.
Claims (1)
1. A device capable of realizing synchronous mesoscopic observation of formation and decomposition of gas hydrate is characterized by comprising a gas cylinder (1), a vacuum pump (3), a gas storage tank (4), a low-temperature thermostatic bath (5), a high-pressure visual reaction kettle (9), a sealing box (10), a pressure-stabilizing gas inlet system, a data acquisition instrument (15), a real-time display system and a pressure-stabilizing exhaust system;
the low-temperature constant-temperature tank (5) is connected with the high-pressure visual reaction kettle (9) and provides stable working temperature for the reaction device;
the high-pressure visible reaction kettle (9) comprises a plurality of sapphire inner cylinders; the high-pressure visible reaction kettle (9) is positioned in the seal box (10);
the pressure stabilizing air inlet system comprises a gas storage tank (4), a valve, a secondary pressure reducing valve and a gas flowmeter; the gas storage tank (4) is positioned inside the low-temperature thermostatic bath (5), and the gas storage tank (4) is respectively connected with the gas cylinder (1) and the vacuum pump (3) through pipelines; the gas storage tank (4) is connected with the sapphire inner cylinder through a guide pipe; the secondary pressure reducing valves are respectively connected with the gas flow meters;
the data acquisition instrument (15) is respectively connected with the gas flowmeter, the pressure sensor and the thermal resistor;
the real-time display system consists of a plurality of electronic endoscopes and a computer (16); the electronic endoscope is arranged inside the high-pressure visual reaction kettle (9) and the seal box (10); the computer (16) is connected with the electronic endoscope;
the pressure stabilizing exhaust system comprises a valve, a gas backpressure valve and a gas flowmeter; the valve is connected with an outlet pipeline of the high-pressure visible reaction kettle; the valves are respectively connected with the gas back pressure valve; the gas back pressure valve is respectively connected with the gas flowmeter;
a circulating liquid is filled in the low-temperature constant-temperature tank (5), and the circulating liquid is an ethylene glycol solution;
the device also comprises a pressure reducing valve (2); the pressure reducing valve (2) is positioned on a pipeline between the gas bottle (1) and the gas storage tank (4);
the high-pressure visible reaction kettle (9) is divided into 1-10 sapphire inner cylinders;
three sapphire inner cylinders of the high-pressure visible reaction kettle (9) are arranged in a quartz outer cylinder, and the outer cylinder is provided with a circulating liquid inlet and a circulating liquid outlet which are connected with circulating liquid of a low-temperature constant-temperature tank;
the upper end and the lower end of the high-pressure visual reaction kettle (9) are provided with flanges for sealing, the bottom of each inner cylinder is provided with a filter screen and an air inlet, air enters the high-pressure visual reaction kettle (9) from the bottom, and the top of the high-pressure visual reaction kettle is provided with two holes respectively which are connected with a thermal resistor and used as an air outlet;
the data acquisition instrument (15) is connected with the thermal resistor, the pressure sensor and the gas flowmeter and is connected with the computer (16), and primary data can be acquired within 10 s;
a first electronic endoscope (81), a second electronic endoscope (82) and a third electronic endoscope (83) in the real-time display system are connected with a computer (16);
the high-pressure visual reaction kettle (9) is divided into 3 sapphire inner cylinders, and a first thermal resistor (111), a second thermal resistor (112) and a third thermal resistor (113) are respectively arranged at outlet pipelines of the sapphire inner cylinders; the gas backpressure valve comprises a first gas backpressure valve (131), a second gas backpressure valve (132) and a third gas backpressure valve (133); the gas flow meters comprise a fourth gas flow meter (141), a fifth gas flow meter (142) and a sixth gas flow meter (143); the pressure stabilizing exhaust system controls the decomposition pressure in each sapphire inner cylinder through a first gas backpressure valve (131), a second gas backpressure valve (132) and a third gas backpressure valve (133) respectively and maintains a constant pressure state, and records the amount of hydrate decomposition gas in each inner cylinder through a first gas flowmeter (141), a second gas flowmeter (142) and a third gas flowmeter (143); a first pressure sensor (121), a second pressure sensor (122) and a third pressure sensor (123) are respectively arranged on a pipeline between the gas backpressure valve and the thermal resistor;
the pressure of a gas storage tank (4) in the pressure stabilizing gas inlet system is higher than the pressure in a high-pressure visual reaction kettle (9), the gas pressure in the high-pressure visual reaction kettle (9) is respectively controlled through a first secondary pressure reducing valve (61), a second secondary pressure reducing valve (62) and a third secondary pressure reducing valve (63) and is kept in a constant pressure state, and the gas consumption of the hydration reaction can be respectively recorded through a first gas flowmeter (71), a second gas flowmeter (72) and a third gas flowmeter (73) in the hydrate formation process;
a method for realizing synchronous mesoscopic observation of gas hydrate formation and decomposition comprises the following steps:
(1) filling porous media or thermal mass strengthening materials into the three sapphire cylinders respectively, and adding a salt solution or a sodium dodecyl sulfate solution until the saturation degree is 0-100%;
(2) opening a vacuum pump connecting valve, and then starting a vacuum pump to pump vacuum;
(3) closing a valve connected with the vacuum pump, closing an air inlet main valve of the high-pressure reaction kettle, opening a gas steel cylinder valve, filling methane gas into a gas storage tank, and closing an air inlet gas circuit valve;
(4) opening a main air inlet valve of the high-pressure reaction kettle, opening branch valves respectively, opening a secondary pressure reducing valve, closing the main air inlet valve of the high-pressure reaction kettle after a small amount of reaction gas is filled into the high-pressure visual reaction kettle, opening branch air exhaust path valves, discharging the reaction gas carrying a small amount of air out of the reaction device, repeatedly filling and discharging the gas until all the air in the device is discharged, and finally closing the branch valves;
(5) opening the low-temperature constant-temperature tank to 270.15-303.15K, opening the air inlet main valve of the high-pressure reaction kettle after the temperature is stable, opening the secondary pressure reducing valve to 0-16 MPa, and filling the high-pressure visible reaction kettle with methane gas with the required pressure of 0-16 MPa;
(6) and opening a real-time display system to capture the appearance and dynamic change of the hydrate in the formation process.
(7) After the hydrate is formed, closing a gas inlet main valve of the high-pressure reaction kettle, opening gas back pressure valves of all branches to 0-10 MPa, decomposing the hydrate at the same temperature and under constant experimental pressure, and capturing the appearance and dynamic change of the hydrate in the decomposition process;
the specific method comprises the following steps:
(1) filling the same porous medium into three sapphire cylinders respectively, adding 3.5 wt% of NaCl solution to simulate seawater until the seawater is saturated to 100%, and sealing the reaction kettle;
(2) opening valves V2 and V3 in the device, opening valve V1, and starting a vacuum pump to vacuumize for 3 min;
(3) closing the stop valve V1, closing the vacuum pump, closing the valve V3, opening the pressure reducing valve V2 after opening the main valve of the gas steel cylinder, filling methane gas into the gas storage tank to 14MPa, and sequentially closing the valve V2, the pressure reducing valve 2 and the main valve of the steel cylinder;
(4) opening a valve V3, opening branch valves V4, V5 and V6 respectively, opening secondary reducing valves 61, 62 and 63 until the pressure is 0.05MPa, filling a small amount of methane gas into the high-pressure visible reaction kettle, closing a stop valve V3, opening branch valves V7, V8 and V9, discharging the methane gas carrying a small amount of air out of the reaction device, repeatedly filling and discharging the methane gas for 3 times until all the air in the device is discharged, and finally closing branch valves V7, V8 and V9;
(5) opening the low-temperature constant-temperature tank, setting the temperature to be 275.15K, opening a valve V3 after the temperature is stabilized for 1h, opening secondary pressure reducing valves 61, 62 and 63 until the pressure is 10MPa, and filling methane gas with the pressure of 10MPa into the high-pressure visible reaction kettle;
(6) and opening a real-time display system, capturing the appearance and dynamic change of the hydrate in the formation process of the same porous medium, comparing the growth characteristics of the hydrate in the porous medium under the same condition, and reducing the influence of the nucleation randomness of the hydrate, wherein the dynamic change process of the formation of one group of hydrates is shown in figure 3.
(7) After the hydrate is formed, closing the valve V3, opening the gas back pressure valves 131, 132 and 133 of each branch to the set pressure of 1MPa, so that the hydrate is decomposed at constant temperature and constant pressure, capturing the morphology and dynamic change of the hydrate in the same porous medium in the decomposition process, and comparing the decomposition characteristics of the hydrate in the porous medium under the same conditions;
or
(1) Filling different porous media (or thermal mass strengthening materials) into the three sapphire cylinders respectively, adding SDS solution until the saturation is 100%, and sealing the reaction kettle;
(2) opening valves V2 and V3 in the device, opening valve V1, and starting a vacuum pump to vacuumize for 3 min;
(3) closing the stop valve V1, closing the vacuum pump, closing the valve V3, opening the pressure reducing valve V2 after opening the main valve of the gas steel cylinder, filling methane gas into the gas storage tank to 14MPa, and sequentially closing the valve V2, the pressure reducing valve 2 and the main valve of the steel cylinder;
(4) opening a valve V3, opening branch valves V4, V5 and V6 respectively, opening secondary reducing valves 61, 62 and 63 until the pressure is 0.05MPa, filling a small amount of methane gas into the high-pressure visible reaction kettle, closing a stop valve V3, opening branch valves V7, V8 and V9, discharging the methane gas carrying a small amount of air out of the reaction device, repeatedly filling and discharging the methane gas for 3 times until all the air in the device is discharged, and finally closing branch valves V7, V8 and V9;
(5) opening the low-temperature constant-temperature tank, setting the temperature to be 275.15K, opening a valve V3 after the temperature is stabilized for 1h, opening secondary pressure reducing valves 61, 62 and 63 until the pressure is 10MPa, and filling methane gas with the pressure of 10MPa into the high-pressure visible reaction kettle;
(6) and opening a real-time display system, capturing the appearance and dynamic change of the formation process of the hydrate in different porous media (or thermal mass reinforced materials), and comparing the growth characteristics of the hydrate in different porous media (or thermal mass reinforced materials) under the same condition.
(7) After the hydrate is formed, closing the valve V3, opening the gas back pressure valves 131, 132 and 133 of each branch to the set pressure of 1MPa, so that the hydrate is decomposed at constant temperature and constant pressure, capturing the morphology and dynamic changes of the hydrate in the decomposition process of different porous media (or thermal mass reinforced materials), comparing the decomposition characteristics of the hydrate in different porous media (or thermal mass reinforced materials) under the same conditions, and simultaneously performing three groups of experiments to improve the operation efficiency of the experiment;
or
(1) Filling the same porous medium into three sapphire cylinders respectively, adding 3.5 wt% of NaCl solution to simulate seawater until the seawater is saturated to 100%, and sealing the reaction kettle;
(2) opening valves V2 and V3 in the device, opening valve V1, and starting a vacuum pump to vacuumize for 3 min;
(3) closing the stop valve V1, closing the vacuum pump, closing the valve V3, opening the pressure reducing valve V2 after opening the main valve of the gas steel cylinder, filling methane gas into the gas storage tank to 14MPa, and sequentially closing the valve V2, the pressure reducing valve 2 and the main valve of the steel cylinder;
(4) opening a valve V3, opening branch valves V4, V5 and V6 respectively, opening secondary reducing valves 61, 62 and 63 until the pressure is 0.05MPa, filling a small amount of methane gas into the high-pressure visible reaction kettle, closing a stop valve V3, opening branch valves V7, V8 and V9, discharging the methane gas carrying a small amount of air out of the reaction device, repeatedly filling and discharging the methane gas for 3 times until all the air in the device is discharged, and finally closing branch valves V7, V8 and V9;
(5) opening the low-temperature constant-temperature tank, setting the temperature to be 275.15K, opening a valve V3 after the temperature is stabilized for 1h, then respectively opening secondary pressure reducing valves 61, 62, 63 to 8, 9 and 10MPa, and respectively filling 8, 9 and 10MPa of methane gas into the high-pressure visible reaction kettle;
(6) and opening a real-time display system, capturing the appearance and dynamic change of the hydrate in the same porous medium in the formation process, and comparing the growth characteristics of the hydrate in the porous medium under different conditions.
(7) After the hydrate is formed, the valve V3 is closed, the gas back pressure valves 131, 132, 133 of each branch are opened to 1, 2 and 3MPa, so that the hydrate is decomposed at constant temperature and constant pressure under different pressure conditions, the appearance and dynamic change of the hydrate in the same porous medium in the decomposition process under different conditions are captured, the decomposition characteristics of the hydrate in the porous medium under different conditions are compared, and the experimental operation efficiency can be improved by simultaneously performing three groups of experiments.
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| CN112362690A (en) * | 2020-11-06 | 2021-02-12 | 西南石油大学 | Hydrate generation induction time measuring device |
| CN112619558A (en) * | 2020-12-10 | 2021-04-09 | 中国海洋石油集团有限公司 | Device and method for observing in-situ growth form of hydrate crystal at multiple viewing angles |
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