RU2781055C1 - Cavitation method for producing gas hydrate - Google Patents

Abstract

FIELD: gas industry.

SUBSTANCE: invention relates to a cavitation method for producing gas hydrate, in which water and a liquefied hydrate gas are fed into the reaction vessel. The method is characterized by the fact that the gas is under static pressure in a metastable state. The thermobaric conditions in the reaction vessel correspond to the conditions under which hydrate formation is possible. An impeller consisting of a housing, shaft and blade wheels is installed in the reaction vessel. At the same time, holes are made in the lower part of the housing, which is in the water, with the help of rotating bladewheels, pressure is created, since the capacity of the holes is less than the capacity of the impeller, a pressure difference is created inside and outside the housing. Water and liquefied hydrate-forming gas begin to be sucked through the holes, which leads to boiling of the liquefied hydrate-forming gas and active mixing, which, in turn, leads to intensive hydrate formation.

EFFECT: use of the proposed method makes it possible to simplify the process due to the absence of a compressor with which the gas is compressed and cooled, as well as to ensure the continuity of the gas hydrate formation process.

1 cl, 1 dwg

Description

The invention relates to the gas industry and is intended for the production of hydrates of various gases (methane, carbon dioxide, ethane, propane, etc.).

A known method of transporting or storing gas hydrates (RF patent No. 2200727, 1997, C07C 5/02), in which compressed gas is fed into the reaction vessel and, together with pressurized water, is expanded with decreasing pressure, passing through nozzles or similar holes. In this case, small droplets of water are formed, dispersed in the expanded gas. Water and gas react to form a gas hydrate. The pressure and temperature in the reactor are set to promote hydrate formation. However, this method has a significant drawback, namely the low growth rate of gas hydrates.

A method for producing a gas hydrate is known (GB Patent No. 2347938, 1999, F17C 11/00), where the gas reacts with water in a reaction vessel to form a hydrate at a pressure and temperature necessary for the formation of a hydrate. The upper part of the vessel is filled with the gas phase, the lower part is filled with the liquid phase. Water is sprayed through nozzles located at the top of the reaction vessel. To form liquid droplets, an ultrasonic vibrating plate is used in the gas phase containing a hydrate-producing substance. An ultrasonic vibrating plate is used to break the hydrate shells on the surface of large water droplets, causing the entire liquid droplet to react to form a hydrate. The use of an ultrasonic emitter in the gas phase intensifies the process of formation of gas hydrates, however, the disadvantages of the previously considered analogue (RF patent No. 2200727, 1997, С07С 5/02) are also present here. According to the authors, the use of an ultrasonic emitter in the liquid phase is less preferable than in the gas phase. The disadvantages of using an ultrasonic emitter in a liquid phase with gas bubbles include the impossibility of obtaining high pressure amplitudes due to the high compressibility of the gas-liquid medium, as well as the small area of the emitter impact on the medium due to the strong attenuation of ultrasound in gas-liquid media.

A known method for producing gas hydrates by explosive boiling (application for a patent of the Russian Federation No. 2016137058, 2016, B01F 3/04, C02F 1/00, F17C 5/02, B01J 3/00), in which a reaction vessel filled with water is fed compressed gas, characterized in that the gas is liquefied in the reaction vessel, and the liquefied gas is transferred to a state of explosive boiling by decompression of the reaction vessel (a sharp drop in pressure to atmospheric pressure). The disadvantage of this method is that the explosive boiling method is a one-time method, that is, after the chamber is depressurized, it is necessary to prepare the reaction vessel again (fill in water, close the reaction vessel, fill the hydrate former and cool the contents of the reaction vessel).

The closest in technical essence to the claimed invention is a method for producing gas hydrates (RF patent No. 2270053, 2003, B01F 3/04], in which the gas is compressed, cooled and mixed with water in a vessel under pressure and at a temperature below equilibrium temperature of gas hydrate formation.The gas-liquid mixture is pulsed by shock waves, which leads to an increase in pressure in the medium, to crushing of the gas phase and a significant intensification of the process of hydrate formation.

This method solves the problem of increasing the rate of formation of gas hydrates. However, it is impossible to achieve higher rates of gas hydrate formation by this method, since it is technically impossible to introduce into the reactor a large amount of gas uniformly distributed in water, comparable in mass to the amount of water introduced into the vessel, for short periods of time (tens of milliseconds) between sequentially affecting the medium shock waves. At close mass flow rates of water and gas, water will no longer be a carrier phase, which will sharply reduce (by an order of magnitude or more) the removal of heat released due to the hydration reaction, and, accordingly, the rate of hydrate formation will drop sharply (by an order of magnitude or more).

The objective of the invention is to accelerate the process of formation of gas hydrate, simplify and reduce the cost of the process due to the absence of a compressor, which compresses and cools the gas, as well as ensuring the continuity of the process of formation of gas hydrate.

The problem is solved by the fact that in the cavitation method for obtaining gas hydrate, in which water and a liquefied hydrate-forming gas are supplied to the reaction vessel, according to the invention , an impeller is installed in the reaction vessel, consisting of a housing, a shaft and impellers, while in the lower part of the housing, holes are made in the water, with the help of rotating impellers a pressure is created and, through the holes, water and liquefied hydrate-forming gas begin to be sucked in, which leads to boiling of the liquefied hydrate-forming gas and active mixing, which in turn leads to intensive hydrate formation.

To increase the rate of hydrate formation, an impeller is located in the reaction vessel together with water and a liquefied hydrate-forming gas (hereinafter referred to as "gas"). The use of liquefied gas can significantly reduce the volume of the reaction vessel, which in turn improves technical and economic performance. Rotating, the impeller impellers create pressure and, through the holes in the housing, water and gas begin to be sucked in. Since the throughput of the holes is less than the performance of the impeller, a pressure difference is created inside and outside the housing. The decrease in pressure inside the impeller housing causes the gas to boil on the suction sides of the impeller impellers and actively mix. The flashing of gas on the suction sides of the impellers is the effect of cavitation. The boiling of the gas is accompanied by a decrease in temperature, which in turn leads to intense hydrate formation.

In FIG. 1 shows a diagram of a device for implementing the claimed method, where:

1 - impeller body;

2 - shaft rotating the impeller impellers;

3 - impellers;

4 - holes for suction of water and gas;

5 - grate for collecting hydrated mass;

6 - liquefied gas;

7 - water;

8 - water, liquefied gas, hydrate mass;

9 – hydrated mass;

10 – body of the reaction vessel.

The method is carried out as follows.

In the reaction vessel, together with water and liquefied gas, there is an impeller, consisting of a housing 1 tightly closed at one end, a shaft 2 and impellers 3. The impellers are rigidly fixed to the shaft. The gas is under static pressure in a metastable state. The thermobaric conditions in the reaction vessel correspond to the conditions under which hydrate formation is possible. There are 4 holes in the impeller housing for suction of water and gas. A grate 5 is attached to the upper part of the impeller body 1, which is in a gaseous medium, along the circumference. Rotating, the impeller 3 impellers create pressure and, through the holes in the body 4, water and gas begin to be sucked in. Since the throughput of the holes is less than the performance of the impeller, a pressure difference is created inside and outside the impeller housing. The decrease in pressure inside the impeller housing causes the gas to boil on the suction sides of the impeller impellers and actively mix. The flashing of gas on the suction sides of the impellers is the effect of cavitation. The boiling of the gas is accompanied by a decrease in temperature, which in turn leads to intense hydrate formation. The resulting hydrated mass is pushed onto the grate by the impeller. The gas boiled on the impellers, which did not turn into a hydrate state, condenses upon exiting the impeller housing and returns to the bottom of the reaction vessel together with water and is again sucked into the impeller, while the resulting gas hydrate remains on the grate. As needed, water and gas are added to the reaction vessel, and the resulting gas hydrate is removed.

The use of the proposed method for obtaining gas hydrates allows you to accelerate the process of hydrate formation.

Claims (1)

A cavitation method for producing gas hydrate, in which water and a liquefied hydrate-forming gas are supplied to the reaction vessel, characterized in that the gas is under static pressure in a metastable state, the thermobaric conditions in the reaction vessel correspond to the conditions under which hydrate formation is possible, an impeller is installed in the reaction vessel , consisting of a housing, a shaft and impellers, while holes are made in the lower part of the housing in the water, with the help of rotating impellers a pressure is created, since the throughput of the holes is less than the performance of the impeller, a pressure difference is created inside and outside the housing, through water and liquefied hydrate-forming gas begin to be sucked in from the hole, which leads to the boiling of the liquefied gas-hydrate-forming gas and active mixing, which, in turn, leads to intensive hydrate formation.

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