阅读说明：本技术 一种高含气率甲烷水合物球及其制备方法 (High-gas-content methane hydrate ball and preparation method thereof ) 是由 崔淦 刘建国 刘翠伟 王爱玲 董增瑞 王顺 邢潇 李自力 于 2019-11-28 设计创作，主要内容包括：本发明提供一种高含气率甲烷水合物球及其制备方法,属于天然气水合物制备技术领域。所述制备方法包括根据所需样品用量制备冰粉；选定模具,向模具中填充冰粉；将填充的冰样品连同其模具一起置于低温密闭装置中,通入高纯甲烷气并进行温度控制,完成水合反应即得。本发明采用冰粉作为原材料进行填充制作,在制备过程中通过提高甲烷气体反应压力并在水合反应过程中进行适宜温度控制,最终实现在短时间内合成含气率较高的纯净甲烷水合物球状样品,有效克服了现有方法中制备周期长、含气率低、能耗大、含杂质污染等问题。(The invention provides a methane hydrate ball with high gas content and a preparation method thereof, belonging to the technical field of natural gas hydrate preparation. The preparation method comprises the steps of preparing ice powder according to the required sample amount; selecting a mould, and filling ice powder into the mould; and (3) placing the filled ice sample and the mould in a low-temperature sealing device, introducing high-purity methane gas, controlling the temperature, and completing the hydration reaction to obtain the ice-based water-. The invention adopts the ice powder as the raw material for filling and manufacturing, finally realizes the synthesis of the pure methane hydrate spherical sample with higher gas content in a short time by improving the reaction pressure of methane gas and carrying out proper temperature control in the hydration reaction process in the preparation process, and effectively overcomes the problems of long preparation period, low gas content, high energy consumption, impurity-containing pollution and the like in the prior method.)

1. A preparation method of methane hydrate spheres with high gas content is characterized by comprising the following steps:

preparing ice powder according to the required sample amount; selecting a mould, and filling ice powder into the mould; and (3) placing the filled ice sample and the mould in a low-temperature sealing device, introducing high-purity methane gas, controlling the temperature, and completing the hydration reaction to obtain the ice-based water-.

2. The method of claim 1, wherein the ice powder is prepared using ice particles having a particle size of not more than 0.5mm as a raw material; the filling of the ice powder is carried out in a low-temperature environment of not higher than-5 ℃.

3. The method of claim 1, wherein the powdered ice has a packing density of not more than 0.40g/cm³。

4. The method according to claim 1, wherein the mold is a spherical silica gel mold having an inner diameter of 1 to 3cm (preferably 2 cm);

preferably, an opening is formed in the spherical silica gel mold shell.

5. The method of claim 1, wherein the closed cryodevice is pre-cooled, the filled ice sample is placed in the closed cryodevice together with its mold when the temperature in the kettle is stabilized at-13 ℃, and then evacuated, preferably to a vacuum of above 0.05 MPa.

6. The production method according to claim 1, wherein the specific conditions for introducing the high-purity methane gas are as follows: slowly pressurizing to 7MPa, stopping air intake, adjusting the temperature in the kettle to rise from-13 ℃ to 8 ℃, and the temperature rise rate is 6 ℃/h; the temperature rise condition is noticed in the pressurizing process to avoid melting of ice powder;

preferably, the purity of the high-purity methane gas is not less than 99.99%.

7. The method according to claim 1, wherein the sample is left standing for 8 to 12 hours in a closed low-temperature apparatus after the temperature is raised.

8. The preparation method of claim 1, wherein the hydrate sample is taken out after the temperature of the closed low-temperature device is reduced to below-10 ℃ and the pressure is reduced to normal pressure.

9. The method of claim 1, wherein the closed cryogenic device is a high pressure autoclave.

10. High gas content methane hydrate spheres obtained by the preparation method of any one of claims 1 to 9.

Technical Field

The invention belongs to the technical field of natural gas hydrate preparation, and particularly relates to a methane hydrate ball with high gas content and a preparation method thereof.

Background

The information in this background section is only for enhancement of understanding of the general background of the invention and is not necessarily to be construed as an admission or any form of suggestion that this information forms the prior art that is already known to a person of ordinary skill in the art.

The natural gas hydrate is an ice-like or cage-like compound formed by interaction of natural gas (mainly methane gas) and water under certain high-pressure and low-temperature conditions, is commonly called 'combustible ice', and is a novel clean energy with huge potential reserves. The hydrate has the advantages of high gas storage density, safety, reliability, low cost, environmental friendliness and the like, can be used as a natural gas storage and transportation mode, can also be used as a clean industrial fuel, and has bright development prospect. The hydrate is scientifically and reasonably developed and utilized, and the accumulation mechanism, the physicochemical parameters and the dissociation combustion characteristics of the hydrate are firstly analyzed through a large number of experiments, so that the hydrate experimental sample is in large demand, the hydrate experimental sample mainly comes from laboratory preparation and field sampling, and most researchers choose to prepare the hydrate sample indoors due to high cost of the hydrate sample. In addition, the natural gas hydrate storage and transportation technology becomes a research hotspot in recent years, and the technical key is how to economically and efficiently artificially synthesize the hydrate suitable for storing and transporting natural gas. Research on hydrate storage and transportation finds that spherical hydrates are strong in self-protection effect and high in stability, have stronger gas storage capacity than slurry-state hydrates and are most beneficial to natural gas storage and transportation, so that high-purity spherical hydrates are generally adopted in hydrate storage and transportation technical research, and more specific requirements are provided for a hydrate rapid artificial synthesis technology. In summary, it is necessary to research a rapid experimental preparation method of the hydrate, and design a simple and feasible process flow to achieve autonomous production of high-quality hydrate particles, provide a material basis for scientific experimental research of the natural gas hydrate, and provide a technical reference for storage and transportation engineering application of the natural gas hydrate.

At present, the most common hydrate rapid experimental preparation methods mainly comprise a mechanical strengthening method and a chemical strengthening method, and liquid water or an ice-water mixture is basically adopted as a raw material. The mechanical strengthening method mainly comprises a stirring method, a spraying method and a bubbling method, and has the defects of long preparation period, low gas content, large energy consumption and general need of separating residual water; the chemical strengthening method mainly comprises a thermodynamic promoter method and a surfactant method, and has the disadvantages of changing the basic properties of the hydrate and easily causing pollution. With the progress of research, researchers find that the preparation of the hydrate by using the ice powder is beneficial to gas molecules to enter ice crystals, quickly forms hydrate crystal nuclei, accelerates the generation of the hydrate, and can improve the contact efficiency with gas due to the large surface area of the ice powder. In the latest research work, when a methane hydrate is synthesized by adopting an ice powder method, ice powder and methane gas react at a constant temperature of-4 ℃, the initial pressure of the gas is 4.7MPa, and the synthesis of a hydrate sample is finished after the mixture is kept stand and reacts for about 17 hours. Although the method has the advantages of short preparation period, simplified process and reduced energy consumption, the gas content is still not high, and the saturation of the hydrate is only 3.8%.

Disclosure of Invention

In view of the defects of the prior art, the invention provides a methane hydrate ball with high gas content and a preparation method thereof. The invention uses ice powder as raw material for filling and manufacturing, and finally realizes the synthesis of the pure methane hydrate spherical sample with higher gas content in a short time by improving the reaction pressure of methane gas and carrying out proper temperature control in the hydration reaction process in the preparation process, thereby effectively overcoming the problems of long preparation period, low gas content, high energy consumption, impurity-containing pollution and the like in the prior art, and having good practical application value.

In order to achieve the technical purpose, the technical scheme adopted by the invention is as follows:

in a first aspect of the present invention, there is provided a method for preparing high gas content methane hydrate spheres, the method comprising:

filling ice powder into the mould; and (3) placing the filled ice sample and the mould thereof in a closed low-temperature device, introducing high-purity methane gas, controlling the temperature, and completing the hydration reaction.

The specific conditions for introducing the high-purity methane gas are as follows: slowly pressurizing, wherein the temperature rise condition is observed during the pressurizing process so as to avoid melting of ice powder, and pressurizing to 7MPa to stop air intake.

The specific conditions for temperature control are: the temperature in the reaction kettle is regulated to be uniformly increased from-13 ℃ to 8 ℃, and the temperature increasing rate is 6 ℃/h.

In a second aspect of the invention, the methane hydrate ball with high gas content obtained by the preparation method is provided.

The invention has the beneficial technical effects that:

the mass gas content of the methane hydrate ball with high gas content prepared by the invention can reach more than 10% (the saturated mass gas content is 13.4%), namely the actual hydration efficiency is higher than 74.6%, and the gas content is equivalent to that of a high-quality natural gas hydrate formed under most natural conditions, so that the rapid and efficient experimental preparation of the hydrate is realized.

The preparation method is simple, easy to operate and good in economy, samples with various shapes and sizes can be prepared according to actual needs, the problems of long preparation period, low gas content, high energy consumption, impurity-containing pollution and the like in the existing method are effectively solved, and convenience is provided for researchers to carry out related experimental researches on hydrates.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention.

FIG. 1 is a schematic diagram of the experimental setup for preparing a methane hydrate sample according to example 1.

In the figure: 1-high pressure methane storage steel cylinder; 2-a pressure gauge; 3-cylinder valve; 4-a booster pump inlet valve; 5-a filter; 6-a booster pump; 7-a high pressure valve; 8-low pressure valve; 9-high pressure gas storage tank; 10-an air outlet valve; 11-a pressure regulating valve; 12-high pressure reactor; 13-refrigeration cycle water jacket; 14-ethanol water bath; 15-a circulation pump; 16-a temperature sensor; 17-a safety valve; 18-an exhaust valve; 19-a vacuum-pumping valve; 20-vacuum container; 21-vacuum gauge; 22-vacuum pump.

Detailed Description

It is to be understood that the following detailed description is exemplary and is intended to provide further explanation of the invention as claimed. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise. It is to be understood that the scope of the invention is not to be limited to the specific embodiments described below; it is also to be understood that the terminology used in the examples is for the purpose of describing particular embodiments only, and is not intended to limit the scope of the present invention.

As mentioned above, the most commonly used hydrate rapid experimental preparation methods at present mainly include a mechanical strengthening method and a chemical strengthening method, wherein the mechanical strengthening method mainly includes a stirring method, a spraying method and a bubbling method, and has the disadvantages of long preparation period, low gas content, large energy consumption and generally need to separate residual water; the chemical strengthening method mainly comprises a thermodynamic promoter method and a surfactant method, and has the defects of changing the basic properties of the hydrate and easily causing pollution.

In view of the above, in one embodiment of the present invention, there is provided a method for preparing a high gas content methane hydrate ball, the method comprising:

preparing ice powder according to the required sample amount; selecting a mould, and filling ice powder into the mould; and (3) putting the filled ice sample and the mould thereof into a pre-cooled low-temperature sealing device, introducing high-purity methane gas, controlling the temperature, and completing the hydration reaction to obtain the ice-based water.

In still another embodiment of the present invention, the ice powder uses ice particles having a particle size of not more than 0.5mm as a raw material. By controlling the particle size of the ice powder, the surface area of the ice powder can be increased, and the contact efficiency with gas is improved, so that the hydration reaction is accelerated, and the hydration reaction time is shortened.

The filling of the ice powder is carried out in a low-temperature environment of not higher than-5 ℃ to prevent the ice powder from melting.

In still another embodiment of the present invention, the ice powder has a packing density of not more than 0.40g/cm for controlling the forming effect and preventing the change of the morphology of the obtained methane hydrate spheroids³。

In another embodiment of the present invention, the mold is a spherical silica gel mold, the inner diameter of the spherical silica gel mold is 1-3 cm (preferably 2cm), further, an opening is provided on the spherical silica gel mold shell to ensure that the ice crystals in the mold are fully contacted with the external methane gas during the hydration reaction, and the diameter of the opening can be controlled to be about 0.5 cm.

In another embodiment of the invention, the closed low-temperature device is pre-cooled, when the temperature in the kettle is stabilized at about-13 ℃, the filled ice sample and the mold thereof are placed in the closed low-temperature device, and then the closed low-temperature device is vacuumized (the vacuum degree needs to reach more than 0.05 MPa), so that the air in the closed low-temperature device is removed, and the generation efficiency and purity of the subsequent methane hydrate are ensured.

In another embodiment of the present invention, the specific conditions for introducing high purity methane gas and controlling the temperature are as follows: slowly pressurizing to 7MPa, stopping air intake, regulating the temperature in the kettle to rise from-13 ℃ to 8 ℃ at a constant speed, and the temperature rise rate is 6 ℃/h. The purity of the high-purity methane gas is not lower than 99.99%. The pressurization rate is controlled, and the ice powder is prevented from melting due to the fact that the temperature is increased too fast because of too fast pressurization.

In another embodiment of the invention, after the temperature is raised, the sample is placed in a closed low-temperature device and stably stands for 8 to 12 hours, and the methane hydrate sample can be synthesized.

In another embodiment of the present invention, the hydrate sample is taken out after the temperature of the closed low temperature device is reduced to below-10 ℃ and the pressure is reduced to normal pressure.

In yet another embodiment of the present invention, the hydrate sample is stored in liquid nitrogen.

In the invention, the used closed low-temperature device can be a high-pressure reaction kettle.

In one embodiment of the invention, the high-gas-content methane hydrate spheres obtained by the preparation method are provided. Tests prove that the mass gas content of the methane hydrate ball sample prepared by the method can reach more than 10% (the saturated mass gas content is 13.4%), the actual hydration efficiency is higher than 74.6%, and the gas content is equivalent to that of a high-quality natural gas hydrate formed under most natural conditions, so that the rapid and efficient experimental preparation of the hydrate is realized.

Meanwhile, it should be noted that the present invention provides a method for preparing high gas-content methane hydrate spheres in the above embodiments, but it is obvious that those skilled in the art can prepare high gas-content methane hydrate samples of other shapes and sizes by changing the shape and size of the mold according to actual needs, and it is also obviously within the scope of the present invention.

The invention is further illustrated by the following examples, which are not to be construed as limiting the invention thereto. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention.