CN111735813A - An experimental device for generating microbubbles and promoting hydrate formation using a microfluidic chip - Google Patents

Abstract

The invention relates to an experimental device for generating microbubbles and promoting the formation of hydrates by using a microfluidic chip, which belongs to the application field of hydrates. The device mainly includes a microfluidic chip with a flat structure, a chip connector, and a matching gas injection system, liquid injection system, and temperature control system. The invention can realize the process of using a microfluidic chip platform to generate microbubbles, and using a CCD camera to observe and record the process of microbubbles generated in the microfluidic chip, as well as the promoting effect of the microbubbles in the hydrate nucleation and growth process. Compared with the traditional methods of promoting the formation of hydrates, such as the shaking method, the stirring method, the external magnetic field method, and the adding accelerator method, the microbubble method not only improves the hydrate formation efficiency, but also avoids the need for additional external force or accelerator to affect the environment. shortcoming.

Description

An experimental device for generating microbubbles and promoting hydrate formation using a microfluidic chip

technical field

The invention belongs to the field of hydrate application, and relates to an experimental device which applies a microfluidic chip to generate microbubbles and promotes the generation of hydrates.

Background technique

Hydrates are clathrates formed by guest molecules (such as methane, carbon dioxide, etc.) and water at low temperature and high pressure. Among them, natural gas hydrate is also called "combustible ice" because its shape is similar to ice and it is flammable. It has huge reserves and high energy density. One cubic meter of combustible ice can be decomposed into 164 cubic meters of methane. It is regarded as a new type of unconventional energy with high combustion calorific value, clean and pollution-free. In addition, hydrates, as highly concentrated compounds, have formed a hydrate technology with important industrial application prospects based on hydrate generation and decomposition after decades of research and development. Society has many meanings. For example, natural gas hydrate can be used for the transportation and storage of natural gas, separation, processing and purification of natural gas in industry. And supercritical extraction, biological protease extraction, organic aqueous solution concentration, carbon dioxide deep-sea storage, nano-scale semiconductor crystallite synthesis, and automobile drive and many other fields.

However, the formation of hydrate has the disadvantages of long induction time, high formation conditions (low temperature and high pressure), and slow formation rate. Therefore, the rapid formation of hydrate is of great significance. At present, the commonly used methods for promoting the formation of hydrates include shaking method, stirring method, external magnetic field method, adding accelerator method (such as: THF, SDS), etc., but each has the disadvantage of requiring additional external force or easily causing damage to the environment. . Therefore, in view of the problem of promoting the formation of hydrates, a new method for promoting the formation of hydrates is urgently needed.

SUMMARY OF THE INVENTION

In view of the above problems existing in the promotion of hydrate generation technology, the present invention provides a new method for promotion of hydrate generation. Using the special structure of the designed microchip, gas is injected into the pores to generate microbubbles (10-100 μm in diameter). Compared with ordinary bubbles, microbubbles have the characteristics of good stability, large specific surface area, high internal pressure, and high interface potential, and can increase the contact area of the gas-liquid interface and enhance the disturbance, so that the hydrate nucleation conditions become milder, thereby promoting the formation of hydrates.

In order to realize the above functions, the technical solution provided by the present invention is an experimental device that uses a microfluidic chip to generate microbubbles and promote the formation of hydrates. , the deionized water bottle is connected to the microfluidic chip by the first liquid inlet branch pipe and the second liquid inlet branch pipe after the injection ISCO pump and the liquid inlet pipe respectively. The microfluidic chip is connected to the gas recovery device, and is connected to the liquid recovery bottle through the liquid outlet pipe; the microfluidic chip is arranged on the closed cooling chamber through the connecting piece, and the closed cooling chamber is connected to the cooling circulation pump.

The microfluidic chip includes an upper etching sheet and a lower sheet. The upper etching sheet is provided with a first liquid inlet, a second liquid inlet, an air inlet, a gas-liquid outlet and a gas-liquid mixing area, and the first liquid inlet is provided. After the port passes through the first liquid filtering structure and the first liquid flow channel, the gas-liquid micro-flow channel is connected to the gas-liquid mixing area; after the second liquid inlet passes through the second liquid filtering structure and the second liquid flow channel, the gas-liquid The micro-flow channel is connected to the gas-liquid mixing area; the air inlet is connected to the gas-liquid mixing area from the gas-liquid micro-flow channel after passing through the gas filter structure and the gas flow channel; the first liquid flow channel and the second liquid flow channel are symmetrically arranged at Both sides of the gas flow channel; the gas-liquid outlet is connected to the gas-liquid mixing area through the outlet filter structure and the outlet flow channel; the gas-liquid micro-channel, the gas-liquid mixing area and the micro-channel opening between them form a flat type structure; the connector is connected to the panel, the backing plate and the bottom plate through the bolt holes on both sides with bolts, the microfluidic chip is clamped between the panel and the bottom plate, and the connector for clamping the microfluidic chip is arranged in a closed cooling room; the panel An observation window is arranged on the bottom plate, and the panel is also provided with a first liquid inlet connection hole, an air inlet connection hole, a second liquid inlet connection hole and a gas-liquid outlet connection hole; the first liquid inlet branch pipe passes through the first liquid inlet connection hole. The branch pipe connection head is connected to the first liquid inlet, the second liquid inlet branch pipe is connected to the second liquid inlet through the second liquid inlet branch pipe connection head, the air inlet pipe is connected to the air inlet through the air inlet pipe connection head, and the gas-liquid outlet is connected through the outlet The pipe connector is connected to the gas-liquid outlet pipe; a CCD camera is also arranged above the observation window, and the CCD camera is electrically connected to the data acquisition system.

。The diameter of the gas-liquid microfluidic channel is less than 100

.

The microbubbles formed through the gas-liquid microfluidic channel enter the gas-liquid mixing area in the microfluidic chip to promote the generation of hydrate.

The device mainly includes a microfluidic chip, a closed cooling chamber, a gas injection system, a liquid injection system, a temperature control system, and a data acquisition system;

的开口，液体与气体能够通过此开口进入气液混合区，其另一侧开有后端带有过滤结构的直道以排出气体、液体。气液体流道、气液混合区及之间的微流道开口形成了扁平式结构，此结构能够使气体剪切液体进入微流道，因此能够产生微气泡，微气泡进入气液混合区并在此区域内促进水合物的形成。芯片连接件包括一个钢片式底板、一个钢片式面板和四个钢片式垫板。底板开有四个带螺纹的小孔，四个垫板各开有两个小孔，面板上方开有方形的观察窗口、四个带螺纹的的大孔和四个带螺纹的小孔。大孔的位置与微流控芯片上的进气、进液、出气液口相对应，气液管道通过螺纹件与连接件将气液注入微流控芯片。钢铁片上小孔的一一对应，用以固定芯片。The microfluidic chip is a high-pressure etched glass slide with a flat structure. The glass slide is defined with an etched area bonded and sealed around it. The shown etched area includes a gas flow channel, a liquid flow channel and a gas-liquid mixture. zone (ie hydrate formation zone). The gas flow channel is a straight flow channel with a filter structure at the front end leading to the gas-liquid mixing area, and the liquid flow channel area is an interconnected square flow channel with a filter structure at the front end that is symmetrically distributed on the upper and lower sides of the gas flow channel area. The gas-liquid mixing area is a square etching area behind the gas-liquid flow channel, and the side connected to the gas-liquid flow channel is opened with a diameter of less than 100 mm.

There is an opening through which liquid and gas can enter the gas-liquid mixing area, and a straight channel with a filter structure at the rear end is opened on the other side to discharge gas and liquid. The gas-liquid channel, the gas-liquid mixing zone and the micro-channel openings between them form a flat structure. This structure enables the gas to shear the liquid into the micro-channel, so that micro-bubbles can be generated, and the micro-bubbles enter the gas-liquid mixing zone and become Hydrate formation is promoted in this region. The chip connector includes a steel sheet base plate, a steel sheet face plate and four steel sheet backing plates. There are four threaded holes on the bottom plate, two small holes on each of the four backing plates, and a square observation window, four large threaded holes and four small threaded holes above the panel. The positions of the large holes correspond to the air inlet, liquid inlet, and gas-liquid outlet ports on the microfluidic chip, and the gas-liquid pipeline injects gas and liquid into the microfluidic chip through threaded parts and connecting parts. The one-to-one correspondence of the small holes on the steel sheet is used to fix the chip.

The gas injection system includes a gas cylinder, a pressure reducing valve at the outlet of the gas cylinder, a gas injection ISCO pump connected to the gas cylinder through a pipeline, a pipeline from the gas injection ISCO pump to the gas injection port of the chip connector, and the end of the pipeline and the connection connected threaded parts. The liquid injection system includes a deionized water bottle equipped with a liquid injection ISCO pump connected through a liquid inlet pipe, a stainless steel reaction kettle, and a first liquid inlet branch and a second liquid inlet branch.

The temperature control system includes a cold bath circulation device, a closed cooling chamber connected with the cold bath circulation device, a thermal insulation layer outside the water tank, and a glycol refrigerant. The data acquisition system includes a CCD camera and corresponding software, a temperature sensor and a pressure sensor at the air inlet and liquid inlet of the microfluidic chip, the gas outlet and the liquid outlet.

Compared with the prior art, the beneficial effects of the present invention are: the present invention can realize the generation of micro-bubbles and promote the formation of hydrates by using a microfluidic chip platform, and use a CCD camera to observe and record the micro-bubbles generated in the microfluidic chip. process, and the promoting role of microbubbles in hydrate nucleation and growth. Compared with the traditional methods of promoting the formation of hydrates, such as the shaking method, the stirring method, the external magnetic field method, and the adding accelerator method, the microbubble method not only improves the hydrate formation efficiency, but also avoids the need for additional external force or accelerator to affect the environment. shortcoming. Specifically, it includes: (1) the present invention adopts a flat structure to generate micro-bubbles, which can stably generate micro-bubbles and at the same time utilize the structural features to promote the generation of hydrates with micro-bubbles in the gas-liquid mixing area; (2) the present invention uses micro-chips to generate The method of micro-bubble promotes the formation of hydrate, and avoids the impact of adding accelerators on the environment while quickly generating hydrate; (3) the present invention reduces the temperature and pressure conditions for hydrate generation, and does not require an external action field, which can reduce the The energy consumption of the generation process.

Description of drawings

Figure 1 is a schematic diagram of an experimental setup that uses a microfluidic chip to generate microbubbles and promote hydrate formation.

FIG. 2 is a structural diagram of a microfluidic chip.

FIG. 3 is a structural diagram of a connector.

FIG. 4 is a combination diagram of a connector and a microfluidic chip.

In the picture: 1. Gas cylinder, 1a, inlet pipe, 1b, inlet pipe connector, 2, gas injection ISCO pump, 3, liquid injection ISCO pump, 4, deionized water, 4a, liquid inlet pipe, 4b, first Liquid inlet branch pipe, 4c, first liquid inlet branch pipe connector, 4d, second liquid inlet branch pipe, 4e, second liquid inlet branch pipe connector, 5, pressure reducing valve, 6, CCD camera, 7, closed cooling chamber, 8 , gas recovery device, 8a, gas-liquid outlet pipe, 8b, gas-liquid outlet pipe connector, 8c, gas outlet pipe, 8d, liquid outlet pipe, 8e, liquid recovery bottle, 9, cooling circulation pump, 10, data acquisition system, 11a, first needle valve, 11b, second needle valve, 11c, third needle valve, 11d, fourth needle valve, 11e, fifth needle valve, 11f, sixth needle valve, 11g, seventh needle valve, 12 , Microfluidic chip, 12a, upper etching sheet, 12b, lower sheet, 12c, first liquid inlet, 12d, second liquid inlet, 12e, gas inlet, 12f, first liquid filter structure, 12g, Gas filter structure, 12h, second liquid filter structure, 12i, first liquid flow channel, 12j, gas flow channel, 12k, second liquid flow channel, 12r, gas-liquid micro-flow channel, 12m, gas-liquid mixing zone, 12n , outlet channel, 12p, outlet filter structure, 12q, gas-liquid outlet; 13, connector, 13a, panel, 13b, backing plate, 13c, bottom plate, 13d, observation window, 13e, first liquid inlet connection hole, 13f , Inlet connection hole, 13g, Second liquid inlet connection hole, 13h, Gas-liquid outlet connection hole, 13i, Bolt hole.

Detailed ways

The specific embodiments of the present invention are described in detail below with reference to the technical solutions and the accompanying drawings.

Figures 1 to 4 show an experimental device that uses a microfluidic chip to generate microbubbles and promote the formation of hydrates. The device uses a methane cylinder 1 that is injected through an ISCO pump 2 and then connected to the microfluidic via an air inlet pipe 1a. The control chip 12, the deionized water bottle 4 is connected to the microfluidic chip 12 by the first liquid inlet branch pipe 4b and the second liquid inlet branch pipe 4d after passing through the liquid injection ISCO pump 3 and the liquid inlet pipe 4a, and the microfluidic control chip 12 passes through the control chip 12. After the gas-liquid outlet pipe 8a, it is connected to the gas recovery device 8 through the gas outlet pipe 8c, and is connected to the liquid recovery bottle 8e through the liquid outlet pipe 8d; The closed cooling chamber 7 is connected to the cooling circulation pump 9;

The microfluidic chip 12 includes an upper etching sheet 12a and a lower sheet 12b. The upper etching sheet 12a is provided with a first liquid inlet 12c, a second liquid inlet 12d, an air inlet 12e, and a gas-liquid outlet 12q. and the gas-liquid mixing zone 12m, the first liquid inlet 12c is connected to the gas-liquid mixing zone 12m by the gas-liquid micro-flow channel 12r after passing through the first liquid filtering structure 12f and the first liquid flow channel 12i; the second liquid inlet 12d passes through After the second liquid filtering structure 12h and the second liquid flow channel 12k, the gas-liquid micro-flow channel 12r is connected to the gas-liquid mixing area 12m; after the air inlet 12e passes through the gas filtering structure 12g and the gas flow channel 12j, the gas-liquid micro-flow channel 12e is connected to the gas-liquid mixing area 12m. The flow channel 12r is connected to the gas-liquid mixing area 12m; the first liquid flow channel 12i and the second liquid flow channel 12k are symmetrically arranged on both sides of the gas flow channel 12j; the gas-liquid outlet 12q is communicated through the outlet filter structure 12p and the outlet flow channel 12n to the gas-liquid mixing area 12m; the connector 13 includes a panel 13a, a backing plate 13b and a bottom plate 13c, the microfluidic chip 12 is clamped between the panel 13a and the bottom plate 13c, and the connector 13 for clamping the microfluidic chip 12 is provided In the closed cooling chamber 7; the panel 13a and the bottom plate 13c are provided with an observation window 13d, and the panel 13a is also provided with a first liquid inlet connection hole 13e, an air inlet connection hole 13f, a second liquid inlet connection hole 13g and a gas-liquid outlet connection hole 13h; the first liquid inlet branch pipe 4b is connected to the first liquid inlet 12c through the first liquid inlet branch pipe connector 4c, and the second liquid inlet branch pipe 4d is connected to the second liquid inlet through the second liquid inlet branch pipe connector 4e 12d, the air inlet pipe 1a is connected to the air inlet 12e through the air inlet pipe connecting head 1b, and the gas-liquid outlet 12q is connected to the gas-liquid outlet pipe 8a through the outlet pipe connecting head 8b; the top of the observation window 13d is also provided with a CCD camera 6, the CCD camera 6 is electrically connected to the data acquisition system 10.

。The diameter of the gas-liquid microfluidic channel 12r is less than 100

.

The microbubbles formed by the gas-liquid microfluidic channel 12r enter the gas-liquid mixing region 12m in the microfluidic chip 12, and the formation of hydrate is promoted in this region.

When working with the above technical solution, inject methane gas into the chip at a flow rate of 1 mL/min to generate microbubbles, and generate methane hydrate when the temperature and pressure conditions reach 7Mpa and 275K, and observe and calculate the experiment of the promotion effect of microbubbles on hydrate formation. . Connect the system according to the system diagram of the experimental device in Figure 1, and perform a pressure test on the system to confirm that there is no air leakage.

The fifth needle 11e and the sixth needle valve 11f are opened, and deionized water is injected into the liquid injection ISCO pump 3 to fill the entire volume of the pump, and the fifth needle 11e and the sixth needle valve 11f are closed. After opening the fourth needle valve and passing the liquid injection ISCO pump 3 through the liquid inlet pipe 4a, it is divided into two branch pipes; Slowly inject deionized water into 12c; the second liquid inlet branch pipe 4d slowly injects deionized water into the second liquid inlet 12d of the microfluidic chip 12 through the second branch pipe connector 4e, and deionized water is injected into the two liquid inlets at the same time. water to displace the residual gas in the microfluidic chip 12 and saturate the chip. After entering from the first liquid inlet 12c, the deionized water enters the gas-liquid mixing area 12m after passing through the first liquid filtering structure 12f, the first liquid flow channel 12i, and the gas-liquid micro-flow channel 12r. After entering from the second liquid inlet 12d, the deionized water enters the gas-liquid mixing zone 12m after passing through the second liquid filtering structure 12h and the second liquid flow channel 12k. The fourth needle valve 11d is closed after the liquid flow channel and the gas-liquid mixing zone 12m are completely saturated with water.

Add the ethylene glycol solution containing about 30% mass concentration as the refrigerant to the water bath where the closed cooling chamber 7 is placed, turn on the cooling circulation pump 9, and reduce the temperature of the entire system to the required temperature 275K;

Open the pressure reducing valve 5 and the first needle valve 11a, inject methane gas from the methane gas cylinder 1 to the gas injection ISCO pump 2 until the entire volume of the pump is filled, and the initial pressure in the pump is 2MPa. Press to the preset pressure of 7Mpa. The first needle valve 11a is closed. The second needle valve 11b and the third needle valve 11c are opened, and the methane gas is slowly injected into the gas flow channel 12j through the gas injection ISCO pump 2 at a flow rate of 1 mL/min through the gas inlet pipe 1a, the gas inlet 12e, the gas filter structure 12g, and the methane gas. The gas is compressed in the gas-liquid micro-flow channel 12r leading to the gas-liquid mixing region 12m from the gas flow channel 12j and generates microbubbles in the gas-liquid mixing region 12m.

Keep the injection flow rate of the gas injection ISCO pump 2 unchanged, use the CCD camera 6 to record and observe the generation of microbubbles in the gas-liquid mixing area 12m in the microfluidic chip, and record the temperature and pressure at the gas-liquid inlet and outlet of the microfluidic chip 12 When the hydrate formation in the gas-liquid mixing zone 12m is stable, the second needle valve 11b and the third needle valve 11c are closed, and the hydrate induction time is recorded. The cooling circulation pump 9 was turned off, the seventh needle valve 11 g was opened, and the deionized water and methane gas in the chip were decomposed and discharged.

The above embodiment is one of the specific embodiments of the present invention, and the usual changes and substitutions made by those skilled in the art within the scope of the technical solution should be included in the present invention.

Claims (3)

1. An experimental device for generating micro bubbles and promoting generation of hydrates by applying a micro-fluidic chip is characterized in that a gas cylinder (1) is connected to a micro-fluidic chip (12) through a gas injection ISCO pump (2) and a gas inlet pipe (1 a), a deionized water cylinder (4) is connected to the micro-fluidic chip (12) through a liquid injection ISCO pump (3) and a liquid inlet pipe (4 a) and a first liquid inlet branch pipe (4 b) and a second liquid inlet branch pipe (4 d) respectively, the micro-fluidic chip (12) is connected to a gas recoverer (8) through a gas outlet pipe (8 a) and a liquid recovery bottle (8 e) through a liquid outlet pipe (8 d) respectively after passing through a gas-liquid outlet pipe (8 a); the method is characterized in that: the micro-fluidic chip (12) is arranged on the closed cooling chamber (7) through a connecting piece (13), and the closed cooling chamber (7) is connected with the cooling circulating pump (9);

the micro-fluidic chip (12) comprises an upper etching sheet (12 a) and a lower carrier (12 b), a first liquid inlet (12 c), a second liquid inlet (12 d), a gas inlet (12 e), a gas-liquid outlet (12 q) and a gas-liquid mixing area (12 m) are arranged on the upper etching sheet (12 a), and the first liquid inlet (12 c) is communicated to the gas-liquid mixing area (12 m) through a gas-liquid micro-flow channel (12 r) after passing through a first liquid filtering structure (12 f) and a first liquid flow channel (12 i); the second liquid inlet (12 d) is communicated to a gas-liquid mixing area (12 m) through a gas-liquid micro-flow channel (12 r) after passing through a second liquid filtering structure (12 h) and a second liquid flow channel (12 k); the gas inlet (12 e) is communicated to a gas-liquid mixing area (12 m) through a gas filtering structure (12 g) and a gas flow channel (12 j) by a gas-liquid micro-flow channel (12 r); the first liquid flow channel (12 i) and the second liquid flow channel (12 k) are symmetrically arranged at two sides of the gas flow channel (12 j); the gas-liquid outlet (12 q) is communicated to the gas-liquid mixing area (12 m) through the outlet filtering structure (12 p) and the outlet flow channel (12 n); the gas-liquid micro-channel (12 r), the gas-liquid mixing area (12 m) and the micro-channel opening between the gas-liquid micro-channel and the gas-liquid mixing area form a flat structure; the connecting piece (13) is connected with the panel (13 a), the backing plate (13 b) and the bottom plate (13 c) through bolt holes (13 i) on two sides by bolts, the microfluidic chip (12) is clamped between the panel (13 a) and the bottom plate (13 c), and the connecting piece (13) clamping the microfluidic chip (12) is arranged in the closed cooling chamber (7); an observation window (13 d) is arranged on the panel (13 a) and the bottom plate (13 c), and a first liquid inlet connecting hole (13 e), an air inlet connecting hole (13 f), a second liquid inlet connecting hole (13 g) and an air-liquid outlet connecting hole (13 h) are also arranged on the panel (13 a); the first liquid inlet branch pipe (4 b) is connected to a first liquid inlet (12 c) through a first liquid inlet branch pipe connector (4 c), the second liquid inlet branch pipe (4 d) is connected to a second liquid inlet (12 d) through a second liquid inlet branch pipe connector (4 e), the gas inlet pipe (1 a) is connected to a gas inlet (12 e) through a gas inlet pipe connector (1 b), and the gas-liquid outlet (12 q) is connected with a gas-liquid outlet pipe (8 a) through an outlet pipe connector (8 b); and a CCD camera (6) is also arranged above the observation window (13 d), and the CCD camera (6) is electrically connected to the data acquisition system (10).

2. The experimental apparatus for generating microbubbles and promoting generation of hydrate by using the microfluidic chip as claimed in claim 1, wherein: the diameter of the gas-liquid micro-flow channel (12 r) is less than 100

。

3. The experimental apparatus for generating microbubbles and promoting generation of hydrate by using the microfluidic chip as claimed in claim 1, wherein: the micro-bubbles formed through the gas-liquid micro-flow channel (12 r) enter a gas-liquid mixing area (12 m) which promotes the generation of hydrate in the micro-flow chip (12).

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