WO2017107639A1

WO2017107639A1 - High-pressure cooling-heating table device for in-situ observation of hydrate microscopic reaction kinetics process and use method

Info

Publication number: WO2017107639A1
Application number: PCT/CN2016/102873
Authority: WO
Inventors: 梁德青; 周雪冰; 龙臻; 何勇
Original assignee: 中国科学院广州能源研究所
Priority date: 2015-12-25
Filing date: 2016-10-21
Publication date: 2017-06-29
Also published as: CN105548137A

Abstract

A high-pressure cooling-heating table device for the in-situ observation of a hydrate microscopic reaction kinetics process, comprising a high-pressure cooling-heating table body (1), an observation system, a gas supply system, a gas discharge system, a temperature control system, a pressure control system and a computer data acquisition system, wherein a cooling channel (18) is further provided inside a base (2), and the cooling channel (18) is connected to the temperature control system and used for controlling the temperature in a reaction tank (14); the high-pressure cooling-heating table body (1) further comprises a gas inlet (22) and a gas outlet (23) in communication with the reaction tank (14); the gas supply system and the gas discharge system are respectively in communication with the gas inlet (22) and the gas outlet (23) of the high-pressure cooling-heating table body (1) and are used for providing a high-pressure gas for the high-pressure cooling-heating table body (1). The device is capable of providing the observation of a gas hydrate under laser Raman in a high pressure environment, can withstand a greater pressure, and can effectively control the pressure and gas flow rate inside the high-pressure cooling-heating table.

Description

High-pressure hot and cold table device for in situ observation of hydrate microscopic reaction kinetics process and use method thereof

Technical field

The invention relates to a high-pressure hot and cold table device for in-situ observation of hydrate kinetics of micro-reaction and a method for using same.

Background technique

Gas hydrates are ice-like crystals produced by gas molecules and water molecules under low temperature and high pressure conditions. Naturally formed gas hydrates are widely distributed in the sedimentary layers of plateau permafrost and shallow continental shelf. In recent years, with the large-scale discovery of natural gas hydrates on a global scale, it has become an important alternative energy source and has received the attention of countries all over the world. At the same time, a standard volume of gas hydrate can store up to 160 standard volumes of gas, storage temperature and pressure conditions are milder than liquefied gases, and can be widely used in natural gas storage and transportation and carbon dioxide fixation and storage. Therefore, studying the thermodynamics and kinetics of gas hydrates is of great significance for realizing the exploitation, storage and transportation of natural gas hydrates and the capture and storage of greenhouse gases.

However, gas hydrates are easily decomposed into gas and liquid water under normal temperature and pressure conditions, while maintaining a stable hydrate crystal structure requires lower temperature and higher pressure. For example, at 1 ° C, the minimum pressure required to maintain the stability of the gas hydrate crystals is 2.9 MPa. This makes the observation and analysis of the gas hydrate microstructure extremely difficult. In the prior art, the observation of the gas hydrate microstructure is mainly to first synthesize a hydrate sample in the reaction vessel, and then take the hydrate sample from the reaction vessel under liquid nitrogen protection and store it in liquid nitrogen, and then from liquid nitrogen. The hydrate sample in the tank was placed on a low temperature test bench and measured by a laser Raman spectrometer. Under normal pressure, the microscopic kinetics of in situ formation, decomposition and displacement of hydrates are achieved by adjusting the temperature of the test bench. This method does not realistically simulate the actual high pressure reaction process of hydrates. Moreover, due to the limitations of the size and design of the test bench, the hydrate sample formed in the reactor can only take a small amount of it and cannot be taken out as a whole.

Therefore, the prior art needs to be improved and developed.

Summary of the invention

The technical problem to be solved by the present invention is to provide a kind of ability to simulate different temperatures, pressures, gas flow rates, etc. Parameters, hydrate formation, decomposition or replacement process, real-time determination of changes in the microstructure of the sample in situ observation of the hydrate kinetics of the kinetics of the high-pressure hot and cold stage device.

The technical solution of the present invention is: a high pressure hot and cold stage device for in situ observation of hydrate microscopic reaction kinetics process, including a high pressure hot and cold stage body, an observation system, a gas supply system, an exhaust system, and a reaction for providing a temperature control system for the temperature required by the process, a pressure control system for controlling the pressure and flow rate of the high pressure gas in the body of the high pressure hot and cold stage, for collecting and real time recording a computer data acquisition system for storing operating parameters in the reaction process;

The high pressure hot and cold table body comprises a base and a screw cap sealingly connected with the base; a reaction tank is opened on the base; a movable stage is placed in the reaction tank; and the upper seal is provided with a see-through member; The cover, the see-through member and the reaction tank form a closed pressure chamber; and a window is opened corresponding to the position of the screw cap and the reaction tank, and the observation system is disposed above the window;

a cooling passage connected to the temperature control system for controlling the temperature of the reaction tank is further disposed inside the base;

The high pressure hot and cold stage body further includes an air inlet and an air outlet communicating with the reaction tank;

The air supply system and the exhaust system respectively communicate with the air inlet and the air outlet of the high pressure hot and cold stage body for supplying methane gas to the high pressure hot and cold stage body.

The see-through member is sapphire glass.

Also included is a high pressure nitrogen bottle with a cryogenic hose that abuts the window.

The temperature control system mainly comprises a constant temperature tank and a circulation pump, and two ends of the cooling passage are respectively connected to the constant temperature tank and the circulation pump.

The gas supply system includes a high pressure gas cylinder connected to the gas inlet through a first buffer tank, and the first buffer tank is placed in the constant temperature tank.

The exhaust system includes a vacuum pump connected to the exhaust port through a second buffer tank; the second buffer tank is placed in the thermostatic bath.

The pressure control system includes a gas collection bottle in communication with a second buffer tank.

The signal collected by the computer data acquisition system is from a fourth temperature sensor of the high pressure cold stage body, a fifth temperature sensor from the thermostatic bath, a first temperature sensor from the first buffer tank, and a first pressure sensor, from the second buffer tank And a second temperature sensor and a second pressure sensor, a third temperature sensor from the third buffer tank, and a third pressure sensor.

Further comprising an auxiliary fitting comprising a micro magnetic stirrer and a high pressure mercury lamp; the micro magnetic stirrer consisting of a micro magnetic stirring motor and a stirrer, the micro magnetic stirring motor is placed in a stainless steel under the high pressure hot and cold table body to maintain At the bottom of the rack, the stirrer is placed in a stage; the high pressure mercury lamp is used in conjunction with an observation system.

A method of using the above-described high pressure hot and cold stage apparatus for in situ observation of hydrate microscopic reaction kinetics, comprising the steps of:

1) using a coolant to lower the temperature of the high pressure hot and cold stage body and stabilize at a first preset temperature;

2) vacuuming the reaction tank of the high pressure hot and cold stage body;

3) Open the high-pressure hot and cold table body to take out the stage and cool the stage to the liquid nitrogen temperature; then load the stage with ice powder; finally, put the stage loaded with ice powder into the high-pressure hot and cold table body. Inside the reaction tank;

4) injecting methane gas into the reaction tank of the high pressure hot and cold stage body; then slowly increasing the temperature of the coolant to bring the temperature of the high pressure hot and cold stage to a second preset temperature;

5) Adjust the vertical distance between the objective lens and the sample to obtain clear imaging and obtain the best observation point by electric sweep.

The beneficial effects of the invention:

The laser Raman observation of gas hydrate is realized under high pressure environment. The maximum gas pressure that the device can withstand reaches 12 MPa, which is much higher than the pressure resistance level of similar devices developed by other countries in the world. The device is equipped with a high-pressure buffer tank at both ends of the gas inlet and outlet of the high-pressure hot and cold stage, which can effectively control the pressure and gas flow rate inside the high-pressure hot and cold stage. The nitrogen purging device installed at the top of the high-pressure hot and cold table can prevent the water vapor in the air from condensing on the surface of the window and can also cool down.

DRAWINGS

Figure 1 is a schematic diagram of the working principle of an in situ observation device for hydrate microscopic reaction kinetics;

Figure 2 is a system diagram of an in situ observation device for hydrate microscopic reaction kinetics;

Figure 3 is a structural view of a high pressure cold stage.

DESCRIPTION OF REFERENCE NUMERALS: 1. high pressure hot and cold table body; 2, base; 3, circulating pump; 4, thermostatic bath; 5, first buffer tank; 6, second buffer tank; 7, third buffer tank; High pressure nitrogen bottle; 9, first needle valve; 9a, second needle valve; 9b, third needle valve; 9c, fourth needle valve; 9d, fifth needle valve; 9e, sixth needle valve; 9f, seventh Needle valve; 9g, eighth needle valve; 9h, ninth needle valve; 10, first temperature sensor; 11, first Pressure sensor; 10a, second temperature sensor; 11a, second pressure sensor; 10b, third temperature sensor; 10c, fourth platinum resistance thermometer; 10d, Pt100 platinum resistance thermometer; 11b, third pressure sensor; 12a, circular window; 13, sapphire glass; 14, high pressure circular reaction tank; 15, brass stage; 16, O-ring; 17, gasket; 18, cooling channel; 19a, pipe female interface; 20, jack; 21, low temperature hose; 22, air inlet; 23, air outlet; 24, high pressure gas cylinder; 25, first pressure reducing valve; 25a, second pressure reducing valve 26, gas cylinder; 27, vacuum pump; 28, laser Raman spectrometer; 29, data acquisition and processing module; 30, micro magnetic stirrer; 31, stainless steel cage; 32, high pressure mercury lamp.

detailed description

Example:

The invention is further described below in conjunction with the drawings and specific embodiments.

Figure 1 is a schematic diagram of the working principle of the in-situ observation device for the hydrate kinetic reaction process. The working process is as follows: the device of the present invention supplies methane gas to the high-pressure hot and cold table body through the exhaust system, and the gas supply system. And through the constant pressure of two buffer tanks, the constant temperature tank controls the temperature required for the reaction, and the working parameters such as temperature and pressure signals in the reaction process are collected and analyzed by a computer data acquisition system.

Figure 2 is a system diagram of an in-situ observation device for hydrate microscopic reaction kinetics. The following is a description of each system function:

1. The working process of the temperature control system is: opening the constant temperature tank 4 through the circulation pump 3 to supply the cooling liquid to the cooling passage 18 provided in the base 16, and thereby controlling the temperature of the high pressure circular reaction tank 14 in the high pressure hot and cold stage body 1; The constant temperature tank 4 cools the first buffer tank 5, the second buffer tank 6, and the third buffer tank 7 to a set temperature, and then the nitrogen cylinder 8 is purged to the upper surface of the sapphire glass 13 via the third buffer tank 7 to dry the low-temperature nitrogen; The control range is -40 degrees Celsius to room temperature.

2. The working process of loading the sample is: after the temperature of the high pressure hot and cold stage body 1 is stabilized at the set temperature, the upper end of the screw cap is opened and the brass stage 15 is taken out. A small amount of the configured solution or ice powder is injected onto the brass stage 15 and quickly placed in the high pressure circular reaction tank 14. The cap 2 above the high pressure hot and cold table body 1 is screwed and nitrogen purge is turned on. The ice powder referred to in the present invention is a powder particle in which a block-shaped ice mill is formed into a certain particle size.

3. The working process of the exhaust system is: the high pressure gas cylinder 24 is first through the pressure reducing valve 25 and the second needle valve 9a The buffer tank 5 and the second buffer tank 6 inject a reaction gas to supply a leak detecting and scavenging gas to the entire system. The pressure reducing valve 25 is then closed, and the vacuum pump 27 is turned on via the ninth needle valve 9h and the second buffer tank 6 to evacuate the entire system.

4. The working process of the gas supply system is: the high pressure gas cylinder 24 injects gas into the first buffer tank 5 and the second buffer tank 6 via the pressure reducing valve 25 and the second needle valve 9a, and the first buffer tank 5 passes through the second needle valve 9a provides a set pressure of methane gas into the high pressure circular reaction tank 14;

5. The working process of the pressure control system is to open the pressure reducing valve 25 and the second needle valve 9a to inject gas into the first buffer tank 5 to a set pressure. Subsequently, the third needle valve 9b and the fourth needle valve 9c are opened, and the high pressure gas is injected into the second buffer tank 6 by the first buffer tank 5. When the pressure difference between the first and second buffer tanks is less than 0.1 MPa, the pressure reducing valve 25 and the second needle valve 9a, and the third needle valve 9b and the fourth needle valve 9c are closed. The first needle valve 9 and the fifth needle valve 9d are opened one after another, and the high pressure gas in the first buffer tank 5 flows through the high pressure hot and cold stage body 1 by the pressure difference and enters the second buffer tank 6. When the pressures of the first buffer tank 5 and the second buffer tank 6 are equal, the fifth needle valve 9d is closed and the first needle valve 9 is kept normally open.

6. The working process of the observation system is: the nitrogen bottle 8 is cooled by the third buffer tank 7, and the lower temperature of the sapphire glass 13 can be purged to the upper surface of the high pressure hot and cold stage body 1 through the eighth needle valve 9g and the seventh needle valve 9f. Nitrogen gas prevents condensation of water vapor from the air on its surface. Turn on the laser Raman spectrometer and adjust the distance between the objective and the surface of the reactants until clear imaging.

7. The working process of the data acquisition system is: connecting the fourth platinum resistance thermometer 10c and the Pt100 platinum resistance thermometer 10d in the high pressure hot and cold table body 1 and the constant temperature tank 4; the Pt100 platinum resistance thermometer on the high

pressure buffer tank

5, 6, 7 and

Pressure transmitters

10, 11, 10a, 11a, 10b, 11b to the data acquisition and processing module.

Figure 3 is a structural view of the main body of the high pressure cooling and cooling table. The bottom of the base of the high-pressure hot and cold table is a cooling passage 18, wherein the continuously flowing coolant can lower the temperature of the high-pressure hot and cold table body and stabilize it at a set temperature. The upper end screw cap 12 of the high pressure hot and cold table body base is opened, and the gasket 17, the sapphire glass 13, the O-ring 16 and the brass stage 15 can be sequentially taken out. The brass stage 15 can be removed and placed in a liquid nitrogen environment to complete the loading of reactants such as ice powder. The O-ring 16 is used to complete the seal between the sapphire glass 13 and the high pressure hot and cold table body base 2. The spacer 17 is used to prevent the screw cap from scratching the surface of the sapphire glass. The wall of the high-pressure circular reaction tank 14 is evenly distributed with three small holes, which are respectively connected with the air inlet 22, the air outlet 23 and the Pt100 platinum resistance thermometer 10d. The Pt100 platinum resistance thermometer 10d extends into the interior of the high pressure circular reaction tank 14 and is in contact with the brass stage 15. The inlet and

outlet ports

22 and 23 of the high pressure hot and cold table body are both high pressure The gas hose connection; the pipe male interface 19 placed at both ends of the cooling passage is connected to the pipe female interface 19a. Six jacks are evenly distributed on the upper end surface of the screw cap for fixing the cryogenic hose 21. The outlet of the cryogenic hose 21 was continuously purged of low temperature nitrogen to the upper surface of the sapphire glass during the experiment to reduce the surface temperature of the sapphire glass while preventing the condensation of water vapor in the air on the surface of the sapphire glass.

The auxiliary components mainly include a micro magnetic stirrer 30 and a high pressure mercury lamp 32; the micro magnetic stirrer 30 is composed of a micro magnetic stirring motor and a stirrer, and the micro magnetic stirring motor is placed at the bottom of the stainless steel cage 31 below the high pressure cold stage 1, the stirrer Placed in a brass stage 15; a high pressure mercury lamp 32 is used in conjunction with a laser Raman spectrometer 28.

The above-mentioned high-pressure hot and cold stage main body device performs an in-situ microscopic observation experiment of hydrate formation on the surface of ice powder. The methane gas used in the experiment has a purity of not less than 99.9%. The water used was distilled water and was prepared by the laboratory. At the same time, the cryostat 4 and the data acquisition and processing module 29 are turned on. The circulation pump 3 is turned on when the temperature is lowered and stabilized to the set temperature. The cooling liquid passes through the cooling passage 18 at the bottom of the high pressure hot and cold table body base 2 to lower the temperature of the high pressure hot and cold stage body and stabilize it at a set temperature. The vacuum pump 27 is turned on and the ninth, sixth, fourth, and

third needle valves

9h, 9e, 9c, and 9b are sequentially opened to evacuate the exhaust gas and the pressure control system. After the evacuation is completed, the ninth, sixth, fourth, and

third needle valves

9h, 9e, 9c, and 9b are sequentially closed, and the first pressure reducing valve 25 and the second needle valve 9a are opened to inject the reaction gas into the first buffer tank 5. The third and

fourth needle valves

9b and 9c are then opened to inject the reaction gas into the second buffer tank 6. When the gas pressure in the second buffer tank 6 is slightly lower than the first buffer tank pressure by about 0.2 MPa, the first pressure reducing valve 25 and the second, third, and

fourth needle valves

9a, 9b, 9c are closed. The second pressure reducing valve 25a and the eighth needle valve 9g are opened to inject dry nitrogen gas into the third buffer tank. The upper end screw cap 12 of the high pressure hot and cold table body base is opened, and the gasket 17, the sapphire glass 13, the O-ring 16 and the brass stage 15 are sequentially taken out. The brass stage 15 was further cooled to a liquid nitrogen temperature and the stage was filled with ice powder and compacted with a small hammer. Then, the brass stage 15, the O-ring 16, the sapphire glass 13, and the spacer 17 are sequentially placed in the high pressure hot and cold stage body base 2 and the screw cap 12 is screwed. The cryogenic hose interface is secured in the receptacle 20 on the cap and provides a continuous low temperature nitrogen gas to prevent condensation of condensed water vapor on the surface of the sapphire glass. The first and fifth needle valves are sequentially opened, and the air in the high pressure circular reaction tank 14 is quickly introduced into the high pressure hot and cold stage body through the air inlet 22 and the air outlet 23, and then the gas pressure of the methane is increased. . The coolant temperature is then slowly raised so that the fourth platinum resistance thermometer 10c measures the temperature to a set temperature. The high pressure hot and cold stage body was fixed on a stainless steel holder 31 and placed together on a laser Raman spectrometer measuring table. Adjusting the vertical distance between the objective and the sample has been clearly imaged and Get the best observation point by electric sweep. As the hydrate formation process progresses, methane hydrate gradually forms on the surface of the ice powder. In the Raman spectrum, the peak intensity of the Raman shifts of 2905cm-1 and 2915cm-1 will gradually increase, representing the concentration of methane molecules in the hydrate cage and cage. The surface of the sample was measured every 2-3 minutes during the growth of methane hydrate. When the ice powder is completely converted into methane hydrate, the peak intensity of methane in the hydrate cage and the small cage is basically stable. The laser Raman spectrometer was used to observe the progress of methane hydrate growth in situ. The high pressure hot and cold stage body 1 and the stainless steel holder 31 were removed from the laser Raman spectrometer measurement stage. Slowly increasing the temperature of the coolant causes the generated methane hydrate to slowly decompose to form a liquid aqueous solution. Turn off the low temperature nitrogen and remove the low temperature hose connection. The first needle valve 9 is closed and the fifth and sixth needle valves 9d9e are slowly opened to slowly discharge methane gas from the air outlet port 23 into the gas collection bottle 26, and then the screw cap 12 is opened. The spacer 17, the sapphire glass 13, the O-ring 16 and the brass stage 15 are sequentially taken out. The aqueous solution in the brass stage 15 is wiped off and placed back in order. The third and

fourth needle valves

9b and 9c are opened to discharge the gas in the first buffer tank 5. The second pressure reducing valve 25a and the eighth needle valve 9g are closed and the ninth needle valve 9i is opened to discharge all the gas in the third buffer tank 7. The third, fourth, fifth, sixth and

ninth needle valves

9b, 9c, 9d, 9e, 9i were closed and the experiment was completed. The detailed description above is a detailed description of the possible embodiments of the present invention, which is not intended to limit the scope of the invention, and the equivalents and modifications of the present invention should be included in the scope of the patent. in.

Claims

A high-pressure hot and cold table device for in situ observation of hydrate microscopic reaction kinetics process, comprising: a high pressure hot and cold stage body, an observation system, a gas supply system, an exhaust system, and a temperature required for providing a reaction process a temperature control system for controlling the pressure and flow rate of the high pressure gas in the body of the high pressure hot and cold stage, for collecting and real-time recording a computer data acquisition system for storing operating parameters in the reaction process;

The high pressure hot and cold table body comprises a base and a screw cap sealingly connected with the base; a reaction tank is opened on the base; a movable stage is placed in the reaction tank; and the upper seal is provided with a see-through member; The cover, the see-through member and the reaction tank form a closed pressure chamber; and a window is opened corresponding to the position of the screw cap and the reaction tank, and the observation system is disposed above the window;

a cooling passage connected to the temperature control system for controlling the temperature of the reaction tank is further disposed inside the base;

The high pressure hot and cold stage body further includes an air inlet and an air outlet communicating with the reaction tank;

The air supply system and the exhaust system respectively communicate with the air inlet and the air outlet of the high pressure hot and cold stage body for supplying methane gas to the high pressure hot and cold stage body.
The high pressure hot and cold stage apparatus for in situ observation of a hydrate microscopic reaction kinetics process according to claim 1, wherein the see-through member is sapphire glass.
The high pressure hot and cold stage apparatus for in situ observation of a hydrate microscopic reaction kinetics process according to claim 1, further comprising a high pressure nitrogen gas bottle with a low temperature hose, the low temperature hose outlet abutting above the window .
The high pressure hot and cold table apparatus for in situ observation of a hydrate microscopic reaction kinetics process according to claim 1, wherein the temperature control system mainly comprises a constant temperature tank and a circulation pump, and both ends of the cooling passage The thermostat and the circulation pump are separately connected.
The high pressure hot and cold table apparatus for in situ observation of a hydrate microscopic reaction kinetics process according to claim 4, wherein the gas supply system comprises a high pressure gas cylinder connected to the gas inlet through a first buffer tank, The first buffer tank is placed in the thermostatic bath.
A high pressure hot and cold stage apparatus for in situ observation of a hydrate microscopic reaction kinetics process according to claim 4, wherein said exhaust system comprises a vacuum connecting said exhaust port through a second buffer tank a pump; the second buffer tank is placed in the thermostat.
A high pressure hot and cold stage apparatus for in situ observation of a hydrate microscopic reaction kinetics process according to claim 6, wherein said pressure control system comprises a gas collection bottle in communication with said second buffer tank.
A high pressure cold stage apparatus for in situ observation of a hydrate microscopic reaction kinetics process according to claim 1, further comprising an auxiliary fitting comprising a micro magnetic stirrer and a high pressure mercury lamp; said micro magnetic force The agitator consists of a micro magnetic stirring motor and a stirrer placed on the bottom of a stainless steel cage below the body of the high pressure hot and cold table, the stirrer being placed in the stage.
A method of using a high pressure hot and cold stage apparatus for in situ observation of a hydrate microscopic reaction kinetics process as claimed in claim 1, comprising the steps of:

1) reducing the temperature of the high pressure hot and cold stage body and stabilizing at the first preset temperature;

2) vacuuming the reaction tank of the high pressure hot and cold stage body;

3) Open the high-pressure hot and cold table body to take out the stage and cool the stage to the liquid nitrogen temperature; then load the stage with ice powder; finally, put the stage loaded with ice powder into the high-pressure hot and cold table body. Inside the reaction tank;

4) injecting methane gas into the reaction tank of the high pressure hot and cold stage body; then slowly raising the temperature of the high pressure hot and cold stage body to a second preset temperature;

5) Adjust the vertical distance between the objective lens and the sample to obtain clear imaging and obtain the best observation point by electric sweep.