A device and method for measuring the contact angle of a hydrate surface

Abstract

The application discloses a hydrate surface contact angle measuring device and method, relates to the field of gas hydrate physical and chemical property characterization, and can be equipped with a low-temperature and high-pressure control unit, can be suitable for hydrate generation and contact angle measurement under different gas and different additive system conditions; the device can make hydrate generation and testing be carried out under the same control condition, which avoids the influence of environment change on hydrate decomposition; the device can obtain the occupation information of guest molecules in the hydrate while testing the surface contact angle, thereby associating the generated hydrate structure and the occupation condition of the guest molecules with the surface characteristics, and simultaneously providing a measuring method used in cooperation with the device.

Description

Technical Field

[0001] This invention relates to the field of characterizing the physical and chemical properties of gas hydrates, and specifically to a device and method for measuring the contact angle of different liquids on the smooth surface of hydrates under low temperature and high pressure conditions. Background Technology

[0002] Gas hydrates are cage-like compounds formed by gas and water under low temperature and high pressure conditions. Water molecules form the cage-like structure of the hydrate through hydrogen bonds, while guest molecules (gas or some additives) are stably stored in the cage under the action of van der Waals forces. Currently, research on gas hydrates mainly includes three aspects: (1) Flow safety assurance. The research background in this field is mainly due to the fact that in oil and gas gathering and transportation operations, gas and water are prone to form solid hydrates in pipelines, which can cause blockages and affect the smooth progress of safe production. In this field, the research on the surface forces between hydrate particles under low temperature and high pressure conditions and the surface energy between hydrates and liquids is the focus. (2) Methane hydrate mining. The mining of methane hydrates requires a focus on the decomposition of hydrates in sediments, gas-liquid-solid multiphase transport and secondary formation. In this research process, it is very necessary to characterize the forces and surface properties between hydrates and sediment particles, between hydrates and water, and between sediments and water. (3) In the application technologies based on hydrates, including carbon dioxide separation, natural gas solidification and storage, and seawater desalination, continuous production is the first problem that must be solved before industrialization, regardless of the specific hydrate application technology. This is similar to the problem faced in pipeline oil and gas gathering and transportation operations, where it is necessary to prevent hydrate blockage in the pipeline. However, unlike oil and gas gathering and transportation, this technology may face more complex hydrate types. For example, the introduction of some thermodynamic additives, intended to reduce the conditions for hydrate formation, can simultaneously lead to the formation of additive hydrates, which is significantly different from the natural gas hydrates generated during oil and gas gathering and transportation. In general, for gaseous hydrates, characterizing their basic surface properties is essential regardless of the research direction, and the wettability to different liquids is the most fundamental part of characterizing their surface properties.

[0003] The contact angle is an important parameter characterizing the degree of wettability of a liquid on a solid surface. It refers to the angle formed between the gas-liquid interface and the solid-liquid interface at the gas-liquid-solid three-phase interface when a liquid droplet is placed on a solid surface. Currently, the main methods for measuring the surface contact angle include angle measurement, force measurement, length measurement, and penetration measurement. Among them, the droplet angle measurement method is the most commonly used and direct method. However, this method faces great difficulties in measuring the contact angle of gas hydrate surfaces. (1) The low temperature and high pressure conditions of hydrates bring great difficulties to the design and manufacture of experimental devices. (2) The surface roughness of naturally formed hydrates is very large and uneven, which will affect the measurement results of the contact angle. Although researchers have developed a series of measuring devices for the high pressure and high temperature environment in the contact angle measurement process. Patent "A Visual Experimental System and Method for Measuring and Characterizing Contact Angles under High Temperature and High Pressure Environment (Publication No. CN 109470603B)" designs a visual experimental system and method suitable for measuring the contact angle of liquids on solid surfaces under high temperature and high pressure environments, even in the supercritical state of water. It uses a heating cylinder with an embedded heating tube to provide a high-temperature environment for the cavity; and uses gas pressurization to create a high-pressure environment to measure the contact angle of the material surface under high pressure and high temperature. Patent "An Experimental System and Method for Measuring Dynamic Contact Angles under High Temperature and High Pressure Environment (Publication No. CN109632580B)" uses the same method to construct a high-temperature and high-pressure environment. However, it is clear that currently there is no suitable contact angle measurement device for the high pressure, low temperature environment, and surface flatness requirements applicable to hydrate testing processes. Therefore, there is an urgent need to develop a device capable of forming a flat hydrate surface under low temperature and high pressure conditions and performing contact angle testing. Furthermore, with the aid of this device, the structure of the hydrate and the occupancy information of the guest molecules can be clarified during the contact angle test of the hydrate surface, thereby establishing the relationship between them and the contact angle of the hydrate surface. Summary of the Invention

[0004] The purpose of this invention is to address the high pressure, low temperature environment, and surface flatness requirements in the current process of measuring the contact angle of hydrate surfaces, by providing an apparatus and method that can form a flat hydrate surface under low temperature and high pressure conditions and perform contact angle testing under such conditions.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, the present invention provides a measuring device for the contact angle of a hydrate surface, comprising:

[0007] A high-pressure visual cavity, placed in a temperature-adjustable air bath, wherein the high-pressure visual cavity is equipped with:

[0008] - Temperature and pressure sensors, which work together to monitor the temperature and pressure inside the high-pressure visible cavity in real time;

[0009] - Back pressure valve, which is used to regulate and control the pressure inside the high-pressure visible cavity;

[0010] - Two symmetrically arranged windows, with a cold light source and an industrial CCD camera respectively arranged on the outer side of the two windows. The cold light source and the industrial CCD camera are arranged on the same horizontal line to measure the contact angle.

[0011] - Droplet formation and characterization component, used to form droplets of a certain volume and to characterize and analyze the structure of hydrates and the occupancy of gas molecules;

[0012] - A gas source, which supplies gas to the high-pressure visible cavity;

[0013] - A hydrate generation chamber is movably disposed within the high-pressure visible cavity, and the side of the hydrate generation chamber is provided with an air hole for connecting to the high-pressure visible cavity.

[0014] The hydrate surface contact angle measuring device as described above, further comprising the droplet formation and characterization component:

[0015] - A component for forming droplets of a certain volume includes: a data acquisition and contact angle analysis system, a micro-flow high-pressure plunger pump, a one-way liquid valve, and a stainless steel capillary tube. The data acquisition and contact angle analysis system is electrically connected to the micro-flow high-pressure plunger pump, and the micro-flow high-pressure plunger pump is connected to the stainless steel capillary tube through a pipe with the one-way liquid valve. The port of the stainless steel capillary tube extends into the high-pressure visible cavity.

[0016] The hydrate surface contact angle measuring device as described above, further comprising the droplet formation and characterization component:

[0017] - A component for characterizing and analyzing the structure of hydrates and the occupancy of gas molecules, comprising: a handheld Raman spectrometer electrically connected to the data acquisition and contact angle analysis system, wherein the detection probe of the handheld Raman spectrometer extends into the high-pressure visible cavity.

[0018] In the hydrate surface contact angle measuring device described above, the gas source supplies gas to the high-pressure visible cavity through a pipeline consisting of a first one-way gas valve, a compressor, and a second one-way gas valve.

[0019] The device for measuring the contact angle of hydrate surfaces as described above, further,

[0020] The high-pressure visible cavity is fastened with fastening bolts, and a graphite fiber sealing ring is used for sealing during fastening to withstand gas pressure.

[0021] The viewing window is made of a combination of sapphire and hollow, externally heated glass, wherein,

[0022] Sapphire is used in the direction close to the interior of the high-pressure visible cavity. The sapphire window is connected to the high-pressure visible cavity by a flange and sealed with a graphite fiber sealing ring.

[0023] The side of the glass closest to the air is insulated with external heating, and its heating surface is in contact with the air.

[0024] The hydrate surface contact angle measuring device described above is further further provided with a coupling installed at the top and bottom of the hydrate generation chamber, which is connected to the hydrate generation chamber via a fixed lead screw; and a coupling installed on the left and right sides of the hydrate generation chamber, with the left side being a plum blossom coupling and the right side being a spring coupling.

[0025] The hydrate surface contact angle measuring device described above further includes an upper and lower part, wherein the hydrate generation chamber is divided into two parts, which are connected by a spring contact.

[0026] When the spring is subjected to a force from above, it is in a locked state, at which time the upper and lower parts of the hydrate generation cavity are connected together; when the hydrate generation cavity in the locked state is subjected to a force from above again, the spring connection is released.

[0027] In the hydrate surface contact angle measuring device described above, the bottom of the high-pressure visible cavity has a layer of heatable metal block, and the heatable metal block is equipped with a channel and a limiting hole. Through the channel, the limiting hole, the fixing screw and the coupling connected thereto, the hydrate generation cavity can be fixed at a designated position above the heatable metal block.

[0028] As described above, the hydrate surface contact angle measuring device further includes a hydrate generation chamber height lifting unit. Through this height lifting unit, the height of the heatable metal block can be adjusted, thereby driving the height adjustment of the hydrate generation chamber above it.

[0029] The high-pressure visible cavity is also equipped with a hydrate generation cavity horizontal translation unit. This horizontal translation unit can be connected to the spring coupling on the right side of the hydrate generation cavity, and the hydrate generation cavity can be moved in the horizontal direction through this horizontal translation unit.

[0030] The high-pressure visible cavity is also equipped with a hydrate generation cavity flipping unit, which can be connected to the plum blossom coupling on the left side of the hydrate generation cavity to realize the flipping of the hydrate generation cavity;

[0031] The high-pressure visible cavity is also equipped with a hydrate generation cavity separation unit, which can be connected to the coupling at the top of the hydrate generation cavity to achieve separation of the upper and lower parts of the hydrate generation cavity.

[0032] Secondly, the present invention provides a method for measuring the contact angle of a hydrate surface, which is used in the hydrate surface contact angle measuring device described above, and includes the following steps:

[0033] Step 1: Inject a set amount of water into the hydrate generation chamber and freeze it into ice blocks under a set temperature condition. After completion, add the pre-cooled additive into the hydrate generation chamber. The pre-cooling temperature of the additive is between -2 and -3℃. After completion, connect and lock the upper and lower parts of the hydrate generation chamber with spring clips.

[0034] Step 2: Using the channel and limiting hole above the heatable metal block, stably place the hydrate generation chamber in the high-pressure visible chamber, seal the high-pressure visible chamber, and adjust the temperature of the air bath to <0℃.

[0035] Step 3: After the air bath temperature stabilizes at the set value, turn on the air source. The gas enters the high-pressure visible cavity through the one-way air valve, compressor and one-way air valve. When the pressure in the high-pressure visible cavity is maintained at the set value, stop the air intake. At the same time, adjust the back pressure valve on the high-pressure visible cavity to be the same as the pressure set value in the high-pressure visible cavity.

[0036] Step 4: After the air intake is completed, set the temperature of the air bath between -1℃ and 0.5℃ and circulate it for 2-5 hours to allow the ice surface to melt slowly and slowly form hydrates with the additives and gases.

[0037] Step 5: After the reaction has been going on for a certain period of time, a layer of hydrate can be observed to form on the ice surface. At this point, stop the temperature circulation of the air bath, readjust the temperature to <0℃, and keep it for 2-3 hours. At this point, the hydrate layer on the ice surface can be observed to be uneven.

[0038] Step 6: Raise the height of the hydrate generation chamber using the hydrate generation chamber height lifting unit until the center line of the plum blossom coupling on the left side of the hydrate generation chamber is at the same horizontal level as the center line of the hydrate generation chamber flipping unit.

[0039] Step 7: Connect the horizontal translation unit of the hydrate generation cavity to the spring coupling on the right side of the hydrate generation cavity to move the hydrate generation cavity out of the channel and the limiting hole. Then, move the hydrate generation cavity to a suitable position so that the plum blossom coupling on the left side of the hydrate generation cavity is connected to the hydrate generation cavity flipping unit. After completion, flip the entire hydrate generation cavity up and down.

[0040] Step 8: Inside the overturned hydrate generation chamber, the rough and uneven hydrate layer is now facing the bottom of the hydrate generation chamber; at this point, the hydrate generation chamber is repositioned into the limiting hole of the channel using the hydrate generation chamber horizontal translation unit; subsequently, the hydrate generation chamber is returned to its original height using the hydrate generation chamber height lifting unit.

[0041] Step 9: Control the temperature of the heatable metal block to increase and decrease in cycles. The temperature fluctuation should be within 0.3-0.7℃ above and below the phase equilibrium point of the generated hydrate. The temperature of the heatable metal block will be conducted to the hydrate layer on the bottom of the ice through the bottom of the hydrate generation chamber, promoting the melting and regeneration of the hydrate layer. After a set time, under the action of gravity and regeneration, the hydrate layer will become relatively flat. At this time, turn off the temperature control of the heatable metal block.

[0042] Step 10: Repeat steps 6 and 7 to flip the entire hydrate generation chamber upside down again, so that the relatively flat hydrate surface faces upward; then, through the cooperation of the horizontal translation unit and the height lifting unit of the hydrate generation chamber, the hydrate generation chamber separation unit is connected to the coupling at the top of the hydrate generation chamber, and the upper and lower parts of the hydrate generation chamber are separated by applying force.

[0043] Step 11: With the cooperation of the horizontal translation unit and the height lifting unit of the hydrate generation chamber, the part of the hydrate generation chamber with the hydrate surface is placed back into the limiting hole of the channel and returned to the original height, and the pressure reaction continues until the set time.

[0044] Step 12: After the reaction is complete, the surface of the hydrate is relatively smooth. At this point, the surface of the generated hydrate can be tested by controlling a handheld Raman spectrometer. The test results will be collected and recorded by the data acquisition and contact angle analysis system to obtain the structure of the hydrate and the occupancy information of the guest molecules; or / and, Step 13: After obtaining a smooth hydrate surface, a certain amount of the test liquid can also be formed into droplets by controlling a micro-flow high-pressure plunger pump through a one-way liquid valve and a stainless steel capillary tube using the data acquisition and contact angle analysis system; at the same time, through the cooperation of the hydrate generation chamber height lifting unit and the hydrate generation chamber horizontal translation unit, the hydrate surface comes into contact with the droplets, and the image of the droplets contacting the hydrate surface is collected by an industrial CCD camera, and the contact angle is obtained by the data acquisition and contact angle analysis system.

[0045] Compared with the prior art, the advantages of this invention are as follows:

[0046] (1) An apparatus and method suitable for testing the contact angle of gas hydrate surfaces are provided;

[0047] (2) The device can be equipped with a low temperature and high pressure control unit, and can be used for the formation of hydrates and contact angle measurement under different gas and additive system conditions.

[0048] (3) The device enables the generation and testing of hydrates to be carried out under the same controlled conditions, which avoids the impact of environmental changes on the decomposition of hydrates.

[0049] (4) The device can obtain the occupancy information of guest molecules in hydrates while testing the surface contact angle, thereby linking the generated hydrate structure and the occupancy of guest molecules with the surface properties. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a schematic diagram of the hydrate surface contact angle measuring device in an embodiment of the present invention;

[0052] Figure 2 This is a schematic diagram of the hydrate reaction chamber in an embodiment of the present invention.

[0053] Appendix Figure 1In the middle section: 1 - Gas source; 2 - First one-way gas valve; 4 - Second one-way gas valve; 3 - Compressor; 5 - Temperature sensor; 6 - Pressure sensor; 7 - Stainless steel capillary tube; 8 - One-way liquid valve; 9 - Micro-flow high-pressure plunger pump; 10 - Data acquisition and contact angle analysis system; 11 - Industrial CCD camera; 12 - Back pressure valve; 13 - Hydrate generation chamber separation unit; 14 - Handheld Raman spectrometer; 15 - Droplet; 16 - Hydrate generation chamber; 17 - Hydrate generation chamber horizontal translation unit; 18 - Hydrate generation chamber height lifting unit; 19 - Hydrate generation chamber flipping unit; 20 - Cold light source; 21 - Heated metal block; 22 - Channel; 23 - Viewing window; 24 - Fastening bolt; 25 - Capillary tube fastening and sealing unit; 26 - High-pressure visible chamber.

[0054] Appendix Figure 2 In the middle: 27 - air hole; 28 - coupling; 29 - fixed lead screw; 30 - plum blossom coupling; 31 - spring plate coupling. Detailed Implementation

[0055] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0056] Example:

[0057] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, in the embodiments of this invention are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0058] In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. Furthermore, unless otherwise explicitly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0059] The purpose of this invention is to address the high pressure and low temperature environment and surface flatness requirements in the current process of measuring the contact angle of hydrate surfaces, and to provide a device that can form a flat surface of hydrates under low temperature and high pressure conditions and can perform contact angle testing under these conditions.

[0060] See Figure 1 The hydrate surface contact angle measuring device provided in this embodiment of the invention may specifically include: a gas source 1; a first one-way gas valve 2; a second one-way gas valve 4; a compressor 3; a temperature sensor 5; a pressure sensor 6; a stainless steel capillary tube 7; a one-way liquid valve 8; a micro-flow high-pressure plunger pump 9; a data acquisition and contact angle analysis system 10; an industrial CCD camera 11; a back pressure valve 12; a hydrate generation chamber cover separation unit 13; a handheld Raman spectrometer 14; a droplet 15; a hydrate generation chamber 16; a hydrate generation chamber horizontal translation unit 17; a hydrate generation chamber height lifting unit 18; a hydrate generation chamber flipping unit 19; a cold light source 20; a heatable metal block 21; a channel 22; a viewing window 23; fastening bolts 24; a capillary tube fastening and sealing unit 25; and a high-pressure visible cavity 26.

[0061] The gas source 1 mainly supplies gas to the high-pressure visible cavity 26 through the first one-way gas valve 2, the compressor 3, and the second one-way gas valve 4, thereby maintaining the pressure inside the high-pressure visible cavity 26 at a set value. At the same time, the gas is also used for the generation of gaseous hydrates in the hydrate generation chamber 16.

[0062] The hydrate generation chamber 16 has a vent 27 on its side, which is used to connect to the high-pressure visible chamber 26, thereby ensuring that the pressure inside the high-pressure visible chamber 26 is the same as the pressure inside the hydrate generation chamber 16, and also providing material gas support for the generation of gaseous hydrates.

[0063] The temperature and pressure inside the high-pressure visible cavity 26 can be monitored in real time by temperature sensor 5 and pressure sensor 6, respectively. If necessary, temperature and pressure data can be collected and stored through an external data acquisition system.

[0064] The high-pressure visible cavity 26 is fastened by fastening bolts 24, and a graphite fiber sealing ring is used for sealing during fastening to withstand gas pressure.

[0065] The pressure inside the high-pressure visible cavity 26 is regulated and controlled by the back pressure valve 12. When the pressure inside the high-pressure visible cavity 26 is greater than the set value, the back pressure valve 12 automatically opens to release gas until the pressure inside the high-pressure visible cavity 26 equals the set value.

[0066] The high-voltage visual cavity 26 is equipped with two viewing windows 23 on both sides. The two viewing windows 23 are on the same horizontal line as the cold light source 20 and the industrial CCD camera 11 to facilitate the measurement of the contact angle.

[0067] The viewing window 23 is composed of sapphire and hollow externally heated glass. The sapphire material is used in the direction close to the interior of the high-pressure viewing cavity 26. This sapphire window is connected to the high-pressure viewing cavity 26 by a flange and is sealed with a graphite fiber sealing ring and fastened with bolts for pressure resistance. The hollow externally heated glass is used on the side close to the air, with the heated surface in contact with the air to prevent frost and fogging of the outer window in contact with the air under low temperature conditions. The other side is close to the outer side of the sapphire window, which is closer to the atmosphere.

[0068] During the contact angle measurement process, a droplet 15 of a certain volume needs to be formed inside the high-pressure visible cavity 26.

[0069] The droplet 15 of a certain volume is mainly formed by a micro-flow high-pressure plunger pump 9 under the control of the data acquisition and contact angle analysis system 10, through a one-way liquid valve 8 and a stainless steel capillary tube 7.

[0070] The stainless steel capillary tube 7 and the high-pressure visible cavity 26 are connected and sealed by a capillary tube fastening and sealing unit 25.

[0071] The high-pressure visible cavity 26 is equipped with a handheld Raman spectrometer 14, which can be used to characterize and analyze the structure of hydrates and the occupancy of gas molecules.

[0072] The handheld Raman spectrometer 14 transmits the acquired spectra to the data acquisition and contact angle analysis system 10 for analysis.

[0073] The hydrate is formed in the hydrate formation chamber 16.

[0074] See Figure 2 , Figure 2This is a schematic diagram of the hydrate reaction chamber in an embodiment of the present invention. The hydrate generation chamber 16 can be a cuboid or a cylinder. It has an air hole 27 on its right side and a coupling 28 installed at the top and bottom, which is connected to the hydrate generation chamber 16 through a fixing screw 29.

[0075] The hydrate generation chamber 16 has a coupling on each side, with the left side being a plum blossom coupling 30 and the right side being a spring coupling 31.

[0076] The hydrate generation chamber 16 is divided into upper and lower parts, which are connected by a spring clip. When the spring clip is subjected to a force from above, it is locked, and the upper and lower parts of the hydrate generation chamber 16 are connected together. When the locked hydrate generation chamber 16 is subjected to a force from above again, the spring clip connection is released.

[0077] The bottom of the high-pressure visible cavity 26 has a layer of heatable metal block 21, preferably a silver block.

[0078] The heated metal block 21 is equipped with a channel 22 and a limiting hole. The hydrate generation chamber 16 can be fixed at a designated position above the heated metal block 21 through the channel 22, the limiting hole, the fixing screw 29 and the coupling 28 connected thereto.

[0079] The high-pressure visible cavity 26 is equipped with a hydrate generation cavity height lifting unit 18. Through this unit, the height of the heatable metal block 21 can be adjusted, thereby driving the height adjustment of the hydrate generation cavity 16 above it.

[0080] The high-pressure visible cavity 26 is equipped with a hydrate generation cavity horizontal translation unit 17. This unit can be connected to the spring coupling 31 on the right side of the hydrate generation cavity 16, and the hydrate generation cavity 16 can be moved in the horizontal direction through this unit.

[0081] The high-pressure visible cavity 26 is equipped with a hydrate generation cavity flipping unit 19, which can be connected to the plum blossom coupling 30 on the left side of the hydrate generation cavity 16 to realize the flipping of the hydrate generation cavity 16.

[0082] The high-pressure visible cavity 26 is equipped with a hydrate generation cavity separation unit 13, which can be connected to the coupling 28 on the upper part of the hydrate generation cavity 16, thereby realizing the separation of the upper and lower parts of the hydrate generation cavity 16.

[0083] The high-pressure visible cavity 26 is placed in a temperature-adjustable air bath, and the temperature control accuracy of the air bath is better than ±0.5℃.

[0084] Based on the same inventive concept, this invention also provides a method for measuring the contact angle of a hydrate surface, which is used in the hydrate surface contact angle measuring device described above. The specific operation mainly consists of the following steps:

[0085] Step 1: First, inject a certain amount of water into the hydrate generation chamber 16 and freeze it into ice blocks at a temperature <0℃. After completion, add pre-cooled additives to the hydrate generation chamber 16. The pre-cooling temperature of the additives is between -2 and 3℃, preferably 0.5℃. After completion, connect and lock the upper and lower parts of the hydrate generation chamber 16 with spring clips.

[0086] Step 2: After completion, the hydrate generation chamber 16 is stably placed in the high-pressure visible chamber 26 by means of the channel 22 and the limiting hole above the heatable metal block 21, and the high-pressure visible chamber is sealed. At the same time, the temperature of the air bath is adjusted to <0℃, preferably -1℃.

[0087] Step 3: After the air bath temperature stabilizes at the set value, turn on the air source 1. Gas enters the high-pressure visual cavity 26 through the first one-way valve 2, compressor 3, and second one-way valve 4. Stop the air intake when the pressure inside the high-pressure visual cavity 26 is maintained at the set value. At the same time, adjust the back pressure valve 12 on the high-pressure visual cavity 26 to be the same as the pressure set value inside the high-pressure visual cavity 26.

[0088] Step 4: After the air intake is completed, the temperature of the air bath is set between -1℃ and 0.5℃ and circulated for 2-5 hours, preferably 3 hours, so that the ice surface melts slowly and slowly forms hydrates with the additives and gases.

[0089] Step 5: After the reaction has proceeded for a certain period of time, a layer of hydrate will be observed forming on the ice surface. At this point, stop the temperature circulation of the air bath and readjust the temperature to <0℃, preferably -1℃, and maintain this temperature for 2-3 hours. At this time, the hydrate layer on the ice surface will appear uneven.

[0090] Step 6: After completion, the height of the hydrate generation cavity 16 is raised by the hydrate generation cavity height lifting unit 18 until the center line of the plum blossom coupling 30 on the left side of the hydrate generation cavity 16 is at the same horizontal position as the center line of the hydrate generation cavity flipping unit 19.

[0091] Step 7: After completion, connect the horizontal translation unit 17 of the hydrate generation cavity to the spring coupling 31 on the right side of the hydrate generation cavity 16 to move the hydrate generation cavity 16 out of the channel 22 and the limiting hole. Then, move it to a suitable position so that the plum blossom coupling 30 on the left side of the hydrate generation cavity 16 is connected to the hydrate generation cavity flipping unit 19. After completion, flip the entire hydrate generation cavity 16 up and down.

[0092] Step 8: Inside the flipped hydrate generation chamber 16, the rough and uneven hydrate layer is now facing the bottom of the hydrate generation chamber 16. At this time, the hydrate generation chamber 16 is repositioned into the limiting hole of the channel 22 using the hydrate generation chamber horizontal translation unit 17. Subsequently, the hydrate generation chamber 16 is returned to its original height using the hydrate generation chamber height lifting unit 18.

[0093] Step 9: Subsequently, the temperature of the heatable metal block 21 is controlled to rise and fall in cycles. The temperature fluctuation should be within 0.3-0.7°C above and below the phase equilibrium point of the generated hydrate, preferably 0.5°C. The temperature of the heatable metal block will be conducted through the bottom of the hydrate generation chamber 16 to the hydrate layer on the ice bottom surface, promoting the melting and regeneration of the hydrate layer. After a period of time, under the action of gravity and regeneration, the hydrate layer will become relatively flat. At this time, the temperature control of the heatable metal block 21 is turned off.

[0094] Step 10: After completion, repeat steps 6 and 7 to flip the entire hydrate generation chamber 16 upside down again, with the flatter hydrate surface facing upwards. Subsequently, the hydrate generation chamber horizontal translation unit 17 and the hydrate generation chamber height lifting unit 18 cooperate to connect the hydrate generation chamber separation unit 13 to the coupling 28 at the top of the hydrate generation chamber 16, and apply force to separate the upper and lower parts of the hydrate generation chamber 16.

[0095] Step 11: Subsequently, with the cooperation of the horizontal translation unit 17 and the height adjustment unit 18 of the hydrate generation chamber, the portion of the hydrate generation chamber 16 with the hydrate surface is placed back into the limiting hole of the channel 22. It then returns to its original height and continues the pressure-maintaining reaction for 10-12 hours overnight.

[0096] Step 12: After the reaction is completed, the surface of the hydrate is relatively smooth. At this time, the surface of the generated hydrate can be tested by controlling the handheld Raman spectrometer 14. The test results will be collected and recorded by the data acquisition and contact angle analysis system 10, thereby obtaining the structure of the hydrate and the occupancy information of guest additives and gas molecules.

[0097] Step 13: After obtaining a smooth hydrate surface, the data acquisition and contact angle analysis system 10 can control the micro-flow high-pressure plunger pump 9 to form a certain amount of the test liquid into droplets 15 through the one-way liquid valve 8 and the stainless steel capillary needle tube 7. Simultaneously, through the cooperation of the hydrate formation chamber height lifting unit 18 and the hydrate formation chamber horizontal translation unit 17, the hydrate surface comes into contact with the droplets 15. An industrial CCD camera 11 captures an image 11 of the droplets contacting the hydrate surface, and the contact angle is obtained through the data acquisition and contact angle analysis system 10.

[0098] Step 14: The order of Steps 12 and 13 can be reversed, or only one of the tests can be performed.

[0099] It should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention.

[0100] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0101] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0102] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made based on the essence of the content of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A device for measuring the contact angle of a hydrate surface, characterized in that, include: A high-pressure visual cavity, placed in a temperature-adjustable air bath, wherein the high-pressure visual cavity is equipped with: - Temperature and pressure sensors, which work together to monitor the temperature and pressure inside the high-pressure visible cavity in real time; - Back pressure valve, which is used to regulate and control the pressure inside the high-pressure visible cavity; - Two symmetrically arranged windows, with a cold light source and an industrial CCD camera respectively arranged on the outer side of the two windows. The cold light source and the industrial CCD camera are arranged on the same horizontal line to measure the contact angle. - Droplet formation and characterization component, used to form droplets of a certain volume and to characterize and analyze the structure of hydrates and the occupancy of gas molecules; - A gas source, which supplies gas to the high-pressure visible cavity; A hydrate generation chamber is movably disposed within the high-pressure visible cavity, and the side of the hydrate generation chamber has an air hole for connecting to the high-pressure visible cavity. A coupling is installed at the top and bottom of the hydrate generation chamber, connected to it via a fixed lead screw. A coupling is also installed on the left and right sides of the hydrate generation chamber; the left side is a perforated coupling, and the right side is a spring-loaded coupling. The hydrate generation chamber is divided into upper and lower parts, connected by a spring. When the spring is subjected to force from above, it is locked, at which point the upper and lower connections of the hydrate generation chamber are... When the hydrate generation chamber, which is in a locked state, is subjected to a force from above again, the spring contact is released. The bottom of the high-pressure visible cavity has a layer of heatable metal block. The heatable metal block is equipped with a channel and a limiting hole. Through the channel, the limiting hole, the fixing screw, and the coupling connected to the fixing screw, the hydrate generation chamber can be fixed at a designated position above the heatable metal block. The high-pressure visible cavity is also equipped with a hydrate generation chamber flipping unit. This flipping unit can be connected to a perforated coupling on the left side of the hydrate generation chamber to achieve the flipping of the hydrate generation chamber.

2. The measuring device for the contact angle of hydrate surfaces according to claim 1, characterized in that, The droplet formation and characterization components include: - A component for forming droplets of a certain volume includes: a data acquisition and contact angle analysis system, a micro-flow high-pressure plunger pump, a one-way liquid valve, and a stainless steel capillary tube. The data acquisition and contact angle analysis system is electrically connected to the micro-flow high-pressure plunger pump, and the micro-flow high-pressure plunger pump is connected to the stainless steel capillary tube through a pipe with the one-way liquid valve. The port of the stainless steel capillary tube extends into the high-pressure visible cavity.

3. The measuring device for the contact angle of a hydrate surface according to claim 2, characterized in that, The droplet formation and characterization components include: - A component for characterizing and analyzing the structure of hydrates and the occupancy of gas molecules, comprising: a handheld Raman spectrometer electrically connected to the data acquisition and contact angle analysis system, wherein the detection probe of the handheld Raman spectrometer extends into the high-pressure visible cavity.

4. The measuring device for the contact angle of a hydrate surface according to claim 1, characterized in that, The gas source supplies gas to the high-pressure visible cavity through a pipeline consisting of a first one-way gas valve, a compressor, and a second one-way gas valve.

5. The measuring device for the contact angle of a hydrate surface according to claim 1, characterized in that, The high-pressure visible cavity is fastened with fastening bolts, and a graphite fiber sealing ring is used for sealing during fastening to withstand gas pressure. The viewing window is made of a combination of sapphire and hollow, externally heated glass, wherein, Sapphire is used in the direction close to the interior of the high-pressure visible cavity. The sapphire window is connected to the high-pressure visible cavity by a flange and sealed with a graphite fiber sealing ring. The glass used is hollow and externally heated on the side closest to the air, with its heated surface in contact with the air.

6. The measuring device for the contact angle of a hydrate surface according to claim 1, characterized in that, The high-pressure visible cavity is also equipped with a hydrate generation chamber height adjustment unit. Through this height adjustment unit, the height of the heatable metal block can be adjusted, thereby driving the height adjustment of the hydrate generation chamber above it. The high-pressure visible cavity is also equipped with a hydrate generation cavity horizontal translation unit. This horizontal translation unit can be connected to the spring coupling on the right side of the hydrate generation cavity, and the hydrate generation cavity can be moved in the horizontal direction through this horizontal translation unit. The high-pressure visible cavity is also equipped with a hydrate generation cavity separation unit, which can be connected to the coupling at the top of the hydrate generation cavity to achieve separation of the upper and lower parts of the hydrate generation cavity.

7. A method for measuring the contact angle of a hydrate surface, used in the measuring device for the contact angle of a hydrate surface as described in any one of claims 1-6, characterized in that, Including the following steps: Step 1: Inject a set amount of water into the hydrate generation chamber and freeze it into ice blocks under a set temperature condition. After completion, add the pre-cooled additive into the hydrate generation chamber. The pre-cooling temperature of the additive is -2 to -3°C. After completion, connect and lock the upper and lower parts of the hydrate generation chamber with spring clips. Step 2: Using the channel and limiting hole above the heatable metal block, stably place the hydrate generation chamber in the high-pressure visible chamber, seal the high-pressure visible chamber, and adjust the temperature of the air bath to <0°C. Step 3: After the air bath temperature stabilizes at the set value, turn on the air source. The gas enters the high-pressure visible cavity through the first one-way air valve, the compressor and the second one-way air valve. When the pressure in the high-pressure visible cavity is maintained at the set value, stop the air intake. At the same time, adjust the back pressure valve on the high-pressure visible cavity to be the same as the pressure set value in the high-pressure visible cavity. Step 4: After the air intake is completed, set the temperature of the air bath between -1°C and 0.5°C and circulate it for 2-5 hours to allow the ice surface to melt slowly and slowly form hydrates with the additives and gases. Step 5: After the reaction has been going on for a certain period of time, a layer of hydrate can be observed to form on the ice surface. At this point, stop the temperature circulation of the air bath, readjust the temperature to <0°C, and keep it for 2-3 hours. At this point, the hydrate layer on the ice surface can be observed to be uneven. Step 6: Raise the height of the hydrate generation chamber using the hydrate generation chamber height lifting unit until the center line of the plum blossom coupling on the left side of the hydrate generation chamber is at the same horizontal level as the center line of the hydrate generation chamber flipping unit. Step 7: Connect the horizontal translation unit of the hydrate generation cavity to the spring coupling on the right side of the hydrate generation cavity to move the hydrate generation cavity out of the channel and the limiting hole. Then, move the hydrate generation cavity to a suitable position so that the plum blossom coupling on the left side of the hydrate generation cavity is connected to the hydrate generation cavity flipping unit. After completion, flip the entire hydrate generation cavity up and down. Step 8: Inside the overturned hydrate generation chamber, the rough and uneven hydrate layer is now facing the bottom of the hydrate generation chamber; at this point, the hydrate generation chamber is repositioned into the limiting hole of the channel using the hydrate generation chamber horizontal translation unit; subsequently, the hydrate generation chamber is returned to its original height using the hydrate generation chamber height lifting unit. Step 9: Control the temperature of the heatable metal block to increase and decrease in cycles. The temperature fluctuation should be within 0.3-0.7°C above and below the phase equilibrium point of the generated hydrate. The temperature of the heatable metal block will be conducted to the hydrate layer on the ice bottom through the bottom of the hydrate generation chamber, promoting the melting and regeneration of the hydrate layer. After a set time, under the action of gravity and regeneration, the hydrate layer will become relatively flat. At this time, turn off the temperature control of the heatable metal block. Step 10: Repeat steps 6 and 7 to flip the entire hydrate generation chamber up and down again, so that the relatively flat hydrate surface faces upward; then, through the cooperation of the horizontal translation unit and the height lifting unit of the hydrate generation chamber, the hydrate generation chamber separation unit is connected to the coupling at the top of the hydrate generation chamber, and the upper and lower parts of the hydrate generation chamber are separated by applying force. Step 11: With the cooperation of the horizontal translation unit and the height lifting unit of the hydrate generation chamber, the part of the hydrate generation chamber with the hydrate surface is placed back into the limiting hole of the channel and returned to the original height, and the pressure reaction continues until the set time. Step 12: After the reaction is complete, the surface of the hydrate is relatively smooth. At this point, the surface of the generated hydrate can be tested by controlling a handheld Raman spectrometer. The test results will be collected and recorded by the data acquisition and contact angle analysis system to obtain the structure of the hydrate and the occupancy information of the guest molecules; or / and, Step 13: After obtaining a smooth hydrate surface, a certain amount of the test liquid is pumped through a one-way liquid valve and a stainless steel capillary tube to form droplets by controlling a micro-flow high-pressure plunger pump. At the same time, the hydrate generation chamber height lifting unit and the hydrate generation chamber horizontal translation unit work together to make the hydrate surface contact the droplets. The image of the droplets contacting the hydrate surface is collected by an industrial CCD camera, and the contact angle is obtained by the data acquisition and contact angle analysis system.

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