Patent Description:
Natural gas hydrates are abundant in the earth and are an important potential energy source in the world. In the background of energy crisis, the survey and research on natural gas hydrates has become a global hotspot. Natural gas hydrates are an ice-like crystalline compounds formed by water and natural gas at high pressures and low temperatures. As the researches on the basic physical properties, microstructures, thermal and dynamic characteristics of hydrates are deepened continuously, abundant reserves of natural gas hydrates have been found in tundras and deep oceans, and have received great attention all over the world. It is found that natural gas hydrates can be used not only as a potential clean energy resource but also as a new applied technology for the benefits of mankind.

The basic principle of gas separation through a hydration process is as follows: hydrates are formed from different gasses under different conditions; when hydrates are formed from gas mixture, the component that can form the hydrate easily tends to concentrate in the hydrate phase, thereby gas separation is realized. The gas separation technique based on hydrate is mainly applied to the separation of CO<NUM>-containing gas mixtures (flue gas N<NUM>/CO<NUM>, natural gas CH<NUM>/CO<NUM>, coal-bed gas CH<NUM>/CO<NUM>, and synthetic gas H<NUM>/CO<NUM>), hydrocarbon gas mixtures (CH<NUM>, C<NUM>H<NUM> and C<NUM>H<NUM>, etc.), hydrogen-containing gas mixtures (hydrogen-containing refinery gas, ethylene cracking gas, and catalytic cracking dry gas, etc.), and other gas mixtures. However, hydrate-based gas separation methods have their own problems. Firstly, at present, most of the researches are based on laboratory-scale small-size equipment, and are carried out with batch or semi-batch separation methods. In batch operation, two or more sets of reactors are required for continuous production of purified gas, the gas phase can't be extracted from the reactor while the hydrate is formed in the hydrate, the gas separation can't be carried out continuously, and the water solution for forming the hydrate is not recycled. Secondly, during hydrate formation, as the concentration of the target gas of separation is decreased, the separation conditions become more rigorous. In addition, owing to the fact that the gas hydrate formation process is a gas-liquid-solid equilibration process, a certain percentage of target gas for separation still remains in the gas phase after the hydrate formation process is completed. In short, it is unable to capture the target gas from the gas mixture completely by using a hydrate-based gas separation technique solely. Therefore, in order to apply hydrate-based gas separation techniques in the industry, it is necessary to develop a continuous gas separation process, large-size reaction equipment, and a new separation method that couples a hydrate process with other separation processes.

<CIT> disclosed a double-vortex-body vortex generating device comprising a main body container and a spiral double-vortex body vortex tube, wherein the cross section of the main body container is circular, and more than one side feed inlets which are distributed along the circumference of the same horizontal height or different horizontal heights and have the same tangential direction are arranged on the circumference of the main body container; the double-vortex-body vortex pipe is formed by winding a single-vortex-body vortex pipe in a vortex mode; the single-vortex-body vortex tube is big end up, the cross section is circular, ; the diameter of the upper port of the double-vortex-body vortex tube is the same as that of the bottom end of the main container, the double-vortex-body vortex tube and the bottom end of the main container are connected with each other, and the bottom end of the double-vortex-body vortex tube is a small-diameter end and serves as a discharge port.

<CIT> disclosed a gas hydrate production device comprising a low-temperature water tank, wherein a water supply pipe is further arranged on the low-temperature water tank, a hydrate generation accelerant is added into the low-temperature water tank through a dosing pipe, then flows into a gas-liquid mixer through a booster pump, and enters a spiral tube type reactor through a spiral bubble generator, and a spiral coil is arranged in the spiral tube type reactor in an ascending way; the hydrate slurry flows out of the spiral tube type reactor and enters a conical hydrate generator from top to bottom, the conical hydrate generator is connected with a three-phase separator to separate the hydrate from natural gas and water which do not participate in the reaction, the separated water contains hydrate crystal nuclei, and the hydrate crystal nuclei are controlled by a water pressure regulating valve to return to the low-temperature water tank; the separated natural gas is controlled by a gas pressure regulating valve to return to the inlet of the compressor for continuous use; and the separated natural gas hydrate enters a hydrate storage tank for storage.

<CIT> disclosed a CO<NUM> gas separation device combining a hydrate method and a chemical absorption method is characterized by comprising a gas source, a flow distributor, a gas flowmeter, a Venturi jet unit provided with two liquid suction inlets, a tubular hydrate reaction unit, a gas-liquid-solid three-phase separation unit, a first slurry pump, a hydrate decomposition unit with a pressure stabilizing valve at the top end, a second slurry pump, a solution saturation tank with a safety valve at the top end, a chemical absorption tower, a second corrosion-resistant pump, a heat exchanger, a regeneration tower, a third corrosion-resistant pump and a liquid storage tank filled with a chemical absorbent of CO<NUM>.

However, in these above priority technical solutions, the issue of insufficient gas-liquid mixing efficiency remains unresolved.

Moreover, for a gas separation device based on a hydrate process, the effect of gas-liquid mixing has direct influences on the hydrate formation efficiency and the separation result. Therefore, there is an urgent need for a design that can strengthen gas-liquid mass transfer and promote efficient hydrate formation.

The information disclosed in this section is only intended to make the background of the present invention understood better, and should not be deemed as acknowledging or implying in any form that the information constitutes the prior art well known to those having ordinary skills in the art.

An object of the present invention is to provide a continuous gas separation system combining hydrate-based process and reverse osmosis process and a disturbance device, so as to improve hydrate formation and gas separation efficiency.

Another object of the present invention is to provide a continuous gas separation system combining hydrate-based process and reverse osmosis process and a disturbance device, so as to realize continuous and large-scale gas separation for industrial application.

To achieve the above objects, according to a first aspect of the present invention, the present invention provides a disturbance device, which comprises: two jet mixers arranged oppositely in the horizontal direction; wherein two mixed streams mixed by the two jet mixers (<NUM>) flow toward and impact each other; a mixing chamber connected between the two jet mixers; and a mixing pipeline connected below the mixing chamber, comprising: a plurality of helical pipes arranged in multiple layers and wound around a central axis of the mixing pipeline, wherein the pipe diameters of the plurality of helical pipes increase gradually from the inner layers to the outer layers, and multiple groups of flow chocking assemblies are arranged in each helical pipe at an interval; and an outer sleeve sleeved outside the helical pipes in the outermost layer.

Optionally, the mixing pipeline comprises a central pipe vertically arranged along the central axis of the mixing pipeline, and the helical pipes are wound around the central pipe.

Optionally, the outer sleeve is a straight pipe, and the central pipe is a straight pipe.

Optionally, the mixing pipeline is located at a horizontal center of the mixing chamber.

Optionally, every two adjacent groups of choking assemblies are spaced apart from each other by <NUM>/<NUM> spiral.

Optionally, each group of chocking assemblies comprise an even number of chocking columns, the axial direction of each chocking column is arranged in the radial direction of the cross section of the helical pipe, and the even number of chocking columns are symmetrically distributed on the cross section of the helical pipe.

Optionally, the cross section of the choking column is circular, triangular, T-shaped or trapezoidal.

Optionally, the length of the choking column is <NUM>/<NUM> to <NUM>/<NUM> of the diameter of the corresponding helical pipe.

Optionally, the width of the choking column is <NUM> to <NUM> times of the diameter of the corresponding helical pipe.

Optionally, the diameter of the helical pipes in the outermost layer is the same as that of the central pipe.

According to a second aspect of the present invention, the present invention provides a continuous gas separation system combining hydrate-based process and reverse osmosis process, which comprises: a hydrate formation loop, with the disturbance device according to any of the above-mentioned technical schemes arranged at an inlet of the hydrate formation loop and a separator arranged on the hydrate formation loop, wherein a first inlet of the separator is connected to a gas feed unit, a second inlet of the separator is connected to an outlet of the hydrate formation loop, and a first outlet and a second outlet of the separator are connected to the jet mixers; a three-phase separator, the inlet of which is connected to a third outlet of the separator; and a hydrate decomposition module connected to a hydrate outlet of the three-phase separator.

Optionally, the continuous gas separation system combining hydrate-based process and reverse osmosis process further comprises a membrane separation unit, which is connected to a gas mixture outlet of the three-phase separator, and the membrane separation unit is provided with a product gas outlet.

Optionally, the continuous gas separation system combining hydrate-based process and reverse osmosis process further comprises: a recycling unit for recycling non-product gasses from the membrane separation unit and the hydrate decomposition module.

Optionally, the hydrate formation loop is a tubular reaction loop.

Optionally, the hydrate formation loop is provided with an external thermal insulation device.

Optionally, the hydrate formation loop is provided with a sight window, which has a pressure withstand rating higher than or equal to <NUM> MPa.

Optionally, a gas circulating pump is arranged between the first outlet of the separator and the jet mixers; and a magnetic circulating pump is arranged between the second outlet of the separator and the jet mixers.

Optionally, the hydrate formation loop is provided with a constant dosing module, which injects water and a promoter into the hydrate formation loop, and is connected to a liquid outlet of the hydrate decomposition module.

Optionally, the constant dosing module comprises a constant-flux pump and a plunger pump.

Optionally, the promoter is tetrahydrofuran and/or tetrabutylammonium bromide.

Optionally, an emergency discharge unit and a back pressure unit are arranged between the gas feed unit and the first inlet of the separator.

Optionally, the gas feed unit is a gas cylinder, which is connected to the first inlet of the separator via a gas boosting pump when the pressure in the gas cylinder is inadequate.

Compared with the prior art, the present invention attains the following beneficial effects:.

The above description is only a summary of the technical scheme of the present invention. Hereunder one or more preferred embodiments will be presented and described with reference to the accompanying drawings in detail, in order to make the technical means of the present invention understood more clearly and implemented on the basis of the description, and make the above-mentioned and other objects, technical features and advantages of the present invention understood more easily.

<NUM> - gas cylinder, <NUM> - gas boosting pump, <NUM> - emergency discharge unit, <NUM> - back pressure unit, <NUM> - disturbance device, <NUM> - jet mixer, <NUM> - mixing chamber, <NUM> - mixing pipeline, <NUM> - central pipe, <NUM> - helical pipe, <NUM> - choking column, <NUM> - outer sleeve, <NUM> - hydrate formation loop, <NUM> - separator, <NUM> - gas circulating pump, <NUM> - magnetic circulating pump, <NUM> - thermal insulation device, <NUM> - water, <NUM> - constant-flux pump, <NUM> - promoter, <NUM> - plunger pump, <NUM> - three-phase separator, <NUM> - hydrate decomposition module, <NUM> - membrane separation unit, <NUM> - product gas outlet, <NUM> - recycling unit.

Hereunder some specific embodiments of the present invention will be detailed with reference to the accompanying drawings. However, it should be understood that the scope of protection of the present invention is not limited to those embodiments.

Unless otherwise expressly stated, throughout the specification and claims, the term "comprise" or "include" or their variants such as "comprising" or "including" shall be understood as including the enumerated elements or components, without excluding other elements or components.

In this document, for the convenience of description, spatially relative terms such as "underside", "below", "bottom", "upside", "above", and "top", etc., may be used to describe the relationship between one element or feature and another element or feature in the drawings. It should be understood that the spatially relative terms are intended to include different directions of the objects in use or operation other than the directions depicted in the drawings. For example, if an object in a drawing is turned upside down, an element described as "below" or "downside" other elements or features will be oriented "above" the elements or features. Therefore, the exemplary term "below" may include "below" and "above" directions. Objects may also have other orientations (rotated by <NUM> degrees or other orientations), and the spatially relative terms used herein should be interpreted accordingly.

In this document, the terms "first", "second", etc. are used to distinguish two different elements or parts, rather than to define a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second", etc. may also be interchanged with each other.

As shown in <FIG>, the continuous gas separation system combining hydrate-based process and reverse osmosis process according to an embodiment of the present invention comprises a hydrate formation loop <NUM>, with a disturbance device <NUM> arranged at the inlet of the hydrate formation loop <NUM> and a separator <NUM> arranged on the hydrate formation loop <NUM>. A first inlet of the separator <NUM> is connected to a gas feed unit, which, for example, comprises a gas cylinder <NUM>. A second inlet of the separator <NUM> is connected to an outlet of the hydrate formation loop <NUM>, and a first outlet and a second outlet of the separator <NUM> are connected to a disturbance device <NUM>. A third outlet of the separator <NUM> is connected to the inlet of a three-phase separator <NUM>, a hydrate outlet of the three-phase separator <NUM> is connected to a hydrate decomposition module <NUM>, a gas mixture outlet of the gas mixture outlet is connected to a membrane separation unit <NUM>, and the membrane separation unit <NUM> is provided with a product gas outlet <NUM>. The hydrate decomposition module <NUM> is used to decompose the generated hydrate slurry, and the membrane separation unit <NUM> is used to further separate the generated lean gas. By using a hydrate process in combination with a membrane process, coupling between hydrate separation for rich gas and membrane separation for lean gas can be realized, thereby the drawback of poor separation efficiency in the separation through a single process is overcome.

As shown in <FIG>, the disturbance device <NUM> according to an embodiment of the present invention comprises two jet mixers <NUM>, a mixing chamber <NUM>, and a mixing pipeline <NUM>, wherein the mixing chamber <NUM> is connected between the two jet mixers <NUM>, and the mixing pipeline <NUM> is connected below the mixing chamber <NUM>. The jet mixers <NUM> are devices for mixing two or more liquids or gasses; two mixed streams are jetted by the two jet mixers <NUM> toward each other at a high speed in the horizontal direction, and impact each other in the mixing chamber <NUM>, an extremely high relative speed between the phases is reached at the moment of impact, thereby inter-phase transfer is strengthened. The fluid in the mixing chamber <NUM> enters the mixing pipeline <NUM>. For example, the mixing pipeline <NUM> is located at the horizontal center of the mixing chamber <NUM>. In one or more embodiments of the present invention, the mixing pipeline <NUM> comprises a central pipe <NUM>, a plurality of helical pipes <NUM>, and an outer sleeve <NUM>, which are arranged from inside to outside sequentially. The central pipe <NUM> is a straight pipe arranged vertically, the plurality of helical pipes <NUM> are arranged in multiple layers and wound outside the central pipe <NUM>, the pipe diameters of the helical pipes <NUM> in multiple layers increase gradually from the inner layers to the outer layers, and the outer sleeve <NUM> is a straight pipe sleeved outside helical pipes <NUM> in the outermost layer. Multiple groups of chocking assemblies are arranged at an interval in each helical pipe <NUM>.

Furthermore, in one or more exemplary embodiments of the present invention, every two adjacent groups of chocking assemblies are spaced apart from each other by <NUM>/<NUM> spiral, i.e., a group of chocking assemblies is arranged at each position of <NUM>° turn of the helical pipe <NUM>. Furthermore, in one or more exemplary embodiments of the present invention, each group of choking assemblies may consist of an even number of choking columns <NUM>, the axial direction of each choking column <NUM> is arranged in the radial direction of the cross section of the helical pipe <NUM>, and the even number of choking columns <NUM> in each group of choking assemblies are symmetrically distributed on the cross section of the helical pipe <NUM>. In the embodiment shown in <FIG>, each group of choking assemblies comprise four choking columns <NUM> evenly distributed on the cross section of the helical pipe <NUM>, and every two adjacent choking columns <NUM> are separated by <NUM>°. However, it should be understood that the present invention is not limited to that arrangement. The direction of arrangement of the choking columns <NUM> is perpendicular to the flow direction of the main fluid in the helical pipes <NUM>. When the fluid flows through the helical pipes, two vortices rotating in opposite directions are generated owing to the unbalanced pressure gradient of the fluid perpendicular to the flow direction and the effect of centrifugal force, i.e., secondary flows and Dean vortexes are formed, and the velocity field and pressure field in the helical pipes change; in nature, the secondary flows are side flows perpendicular to the direction of the main stream. The generated Dean vortexes improve the mass transfer and heat transfer performance of the fluid and strengthen gas-liquid contact and mixing. A Dean Number describes the relationship between centrifugal force and viscous force in the process of fluid flow, and can be used to characterize the intensity of the Dean vortex. The Dean Number is related with the pipe diameter of the helical pipe and the diameter of the spiral. The pipe diameters of the helical pipes increase gradually from the inner layers to the outer layers, and the diameters of the spirals also increase gradually from the inner layers to the outer layers, thereby the intensities of the vortexes generated in the multiple layers of helical pipes are equivalent to each other, and efficient mixing of the fluid is promoted. The symmetrically distributed chocking columns arranged in the helical pipes separate the two Dean vortexes generated in the helical pipes and destroy the disturbance of the Dean vortexes to the fluid. Alternating vortices in the reversed direction (i.e., separated vortexes) are formed behind the chocking columns, and, under the separation effect of the chocking columns, extensive fluid contact is achieved and the mixing is further strengthened by redistribution. Then, Dean vortexes are generated again in the fluid under the effect of the secondary flows in the helical pipes, and then separated vortexes are formed under the action of the chocking columns, and so on. In that way, the fluid flows through the helical pipes. Gas-liquid mixed media with different turbulent intensities take different times to flow through the mixing pipeline, thereby the sub-mixing in the axial direction is strengthened.

Furthermore, in one or more exemplary embodiments of the present invention, the cross-sectional shape of the choking columns <NUM> is circular, triangular, T-shaped or trapezoidal. It should be understood that the present invention is not limited to those shapes, and the specific shape of the choking columns <NUM> may be selected according to the actual requirement.

Furthermore, in one or more exemplary embodiments of the present invention, the length of the chocking columns <NUM> is <NUM>/<NUM> to <NUM>/<NUM> of the pipe diameter of the corresponding helical pipe <NUM>. Furthermore, in one or more exemplary embodiments of the present invention, the width of the chocking columns <NUM> is <NUM> to <NUM> times of the pipe diameter of the corresponding helical pipe <NUM>. The width of a chocking column <NUM> refers to the width of the flow-facing surface of the chocking column. For example, in the case that the chocking column is a circular column, the width of the chocking column is the diameter of the circular column; in the case that the chocking column is a triangular column, the width of the chocking column is the length of the bottom edge of the flow-facing surface of the chocking column.

Furthermore, in one or more exemplary embodiments of the present invention, the diameter of the helical pipes <NUM> in the outermost layer is the same as that of the central pipe <NUM>.

As shown in <FIG>, in one or more embodiments of the present invention, the continuous gas separation system combining hydrate-based process and reverse osmosis process further comprises a recycling unit <NUM>, which is used to recycle the non-product gasses from the membrane separation unit <NUM> and the hydrate decomposition module <NUM>, so as to avoid polluting the environment.

Furthermore, in one or more exemplary embodiments of the present invention, the hydrate formation loop <NUM> may be a tubular reaction loop. Preferably, but not limitingly, the tubular reaction loop is designed to be disassemble and replaceable, so that the pipes can be replaced with other pipes different in diameter as required. The pressure rating of the pipeline is <NUM> MPa, and the working temperature of the pipeline is -<NUM> to <NUM>. The tubular reaction loop may be made of stainless steel <NUM>, but the present invention is not limited to that. Furthermore, in one or more exemplary embodiments of the present invention, the hydrate formation ring <NUM> is provided with an external thermal insulation device to keep the temperature constant. For example, the thermal insulation device <NUM> may be a high-low temperature integrated bath, which works at -<NUM> to <NUM> working temperature, and has overheat protection, overload protection, and other functions. Furthermore, in one or more exemplary embodiments of the present invention, the hydrate formation loop <NUM> is provided with a sight window (not shown), which has a pressure withstand rating higher than or equal to <NUM> MPa. The sight window is mainly used to observe the flow condition and the hydrate formation condition in the hydrate formation loop <NUM>.

Furthermore, in one or more exemplary embodiments of the present invention, a gas circulating pump <NUM> is provided between the first outlet of the separator <NUM> and the jet mixers <NUM>; and a magnetic circulating pump <NUM> is arranged between the second outlet of the separator <NUM> and the jet mixers <NUM>.

Furthermore, in one or more exemplary embodiments of the present invention, the hydrate formation loop <NUM> is provided with a constant dosing module, which injects a promoter <NUM> into the hydrate formation loop <NUM> via a plunger pump <NUM>, and injects water <NUM> into the hydrate formation loop <NUM> via a constant-flux pump <NUM>. The constant dosing module may be connected to the liquid outlet of the hydrate decomposition module <NUM>, so as to realize water recycling and reuse in the system. It should be understood that the present invention is not limited to that arrangement, and the specific type of the pump may be selected according to the actual requirement. Furthermore, in one or more exemplary embodiments of the present invention, the promoter <NUM> may be tetrahydrofuran and/or tetrabutylammonium bromide, but the present invention is not limited to it.

Furthermore, in one or more exemplary embodiments of the present invention, an emergency discharge unit <NUM> and a back pressure unit <NUM> are provided between the gas cylinder <NUM> of the gas feed unit and the first inlet of the separator <NUM>.

Furthermore, in one or more exemplary embodiments of the present invention, when the pressure in the gas cylinder <NUM> is inadequate, the gas cylinder <NUM> is connected to the first inlet of the separator <NUM> via a gas boosting pump <NUM>.

Claim 1:
A disturbance device, comprising:
two jet mixers (<NUM>) arranged oppositely in a horizontal direction, wherein two mixed streams mixed by the two jet mixers (<NUM>) flow toward and impact each other;
a mixing chamber (<NUM>) connected between the two jet mixers (<NUM>); and
a mixing pipeline (<NUM>) connected below the mixing chamber (<NUM>), comprising:
a plurality of helical pipes (<NUM>) arranged in multiple layers and wound around a central axis of the mixing pipeline (<NUM>), wherein the pipe diameters of the plurality of helical pipes (<NUM>) increase gradually from the inner layers to the outer layers, and multiple groups of flow chocking assemblies are arranged in each helical pipe (<NUM>) at an interval; and
an outer sleeve (<NUM>) sleeved outside the helical pipes (<NUM>) in the outermost layer.