JP6280474B2 - Gas separation device and gas separation method - Google Patents

Description

  The present invention relates to an apparatus and a method for separating a target gas from a mixed gas by selectively collecting the target gas (hereinafter referred to as “target gas”) from the mixed gas with a hydrate.

  In the present invention, the meaning or interpretation of the following terms is as follows. The meaning or interpretation of this term does not preclude the technical scope of the present invention from reaching an equivalent scope.

  (1) “Hydrate” is an abbreviation for clathrate hydrate. Other molecules called guest substances, guest molecules, or guest compounds enter tunnel-like, layer-like, network-like, cage-like structures (inclusion lattices) formed by water molecules called hosts, host substances, or host molecules, or A substance formed and produced by incorporation is called clathrate hydrate. Examples of guest materials include quaternary ammonium salts typified by alkyl ammonium salts such as tetra-n-butylammonium salt, tetra-isopentylammonium salt, tri-n-butyl-pentylammonium salt, alkylphosphonium salts, and alkylsulfonium salts. is there. The “hydrate” in the present invention includes quasi-clathrate hydrate. A guest substance that produces clathrate hydrate is referred to as a hydrate product.

  (2) A hydrate guest substance, that is, an aqueous solution of a hydrate product, more specifically, an aqueous solution containing one or more hydrate products as a solute and water as a solvent, is hydrated when cooled. Things are generated. In the present invention, the “liquid that forms a hydrate” refers to a liquid containing a hydrate product that is cooled to form a hydrate. When the liquid that forms the hydrate is cooled to form the hydrate, a mixture of the hydrate and the liquid that forms the hydrate is obtained.

  (3) “Slurry of hydrate” means that the hydrate is dispersed or suspended in an aqueous solution of the guest substance, that is, an aqueous solution of a hydrate product or an aqueous solvent, to form a slurry. Say things. Even if the amount of hydrate is small (in other words, even if the proportion of hydrate is low) or the amount of hydrate is large, the hydrate is dispersed or suspended in the aqueous solution or aqueous solvent. If it is cloudy, it is a “hydrate slurry”.

  A technique for selectively collecting and separating a target gas from a mixed gas composed of a target gas and a gas other than the target gas by a hydrate includes alkylammonium salt, alkylphosphonium salt, alkylsulfonium salt and the like as hydrate products. A technique that collects and separates the target gas using a hydrate is a good example (see Patent Document 1). In this technique, in any target gas, a hydrate is generated by cooling a mixture of the aqueous solution of the hydrate product and the target gas.

  Conventionally, in order to separate the target gas by hydrate, a gas separation apparatus including a hydrate generator and a hydrate decomposition apparatus has been used.

  In the hydrate generation device, a hydrate that collects the target gas is generated by cooling in a state where the aqueous solution of the hydrate product and the mixed gas containing the target gas are mixed. A hydrate slurry is formed with the hydrate-forming liquid. In the state where the aqueous solution of the hydrate product and the mixed gas containing the target gas are mixed in the hydrate generating device, while the inside of the generation pipe arranged so as to be able to exchange heat with the refrigerant body, A hydrate slurry is formed by being cooled by the refrigerant around the production tube.

  Next, the mixture of the hydrate slurry containing the hydrate that has collected the target gas and the gas other than the target gas is separated into gas and liquid under normal pressure in the separator, and then the gas other than the target gas. Is discharged to the hydrate decomposition apparatus. The hydrate slurry from which a gas other than the target gas has been excluded is then heated by a hydrate decomposition apparatus, and the hydrate is decomposed by heating to become an aqueous solution of a hydrate product, which is captured from the hydrate. Release the collected target gas. The mixture of the released target gas and the aqueous solution of the hydrate product is subjected to gas-liquid separation under normal pressure in the following separator to extract the target gas. The aqueous solution of the hydrate product after the target gas is extracted by the melting (decomposition) of the hydrate by heating in the hydrate decomposer is returned to the hydrate generator in the form of an aqueous solution. And cooled to a temperature suitable for hydrate formation and reused.

JP 2012-76080 A

  In the conventional gas separation apparatus described above, an aqueous solution of a hydrate product in which the hydrate is melted by raising the temperature in the hydrate decomposition apparatus, the temperature for producing the hydrate in the hydrate generation apparatus. Therefore, a large-scale cooling device such as a refrigerator is necessary. In the hydrate decomposition apparatus, a heating device is required to melt the hydrate. Therefore, since these cooling devices and heating devices are required as the gas separation device, the device becomes large and equipment costs increase, energy consumption for cooling and heating increases, and operating costs also increase.

  Furthermore, when producing a hydrate slurry with a hydrate production device, a mixture of an aqueous solution of the hydrate product and a mixed gas containing the target gas is flown through the production tube and produced during the flow. Since it is cooled by the refrigerant body around the pipe, hydrate adheres to the inner surface of the production pipe, resulting in a problem of blockage of the pipe and an increase in pressure loss at the time of flow. The problem is that the pump power increases, that is, the energy consumption of the power source increases. In addition, there is a problem that the pump must be enlarged to cope with the increasing pressure loss.

  In view of such circumstances, the present invention does not require a large-scale cooling device for producing hydrates or a heating device for melting hydrates, requires less energy, and has a small-scale device. Furthermore, it is an object of the present invention to provide a gas separation device and a gas separation method that do not cause the problem of blockage of the pipe during hydrate production.

  According to the present invention, the above-described problems are solved by a gas separation device and a gas separation method configured as follows.

<Gas separator>
In a gas separation apparatus for separating a target gas by bringing a mixed gas containing the target gas into contact with a hydrate slurry, the container and a pressurizing means for applying an internal pressure to the container are provided. Receiving a mixed gas and a hydrate slurry in a container and pressurizing the mixed gas and the hydrate slurry in contact with each other; A pressure reducer that receives the hydrate slurry and depressurizes the hydrate slurry, and the pressure device and the pressure reducer return to the pressure device through a return path after the pressurized hydrate slurry is decompressed by the pressure reducer. The gas separation is characterized in that the pressurizer is provided with a discharge port for exhausting a gas other than the target gas, and the decompressor is provided with a target gas outlet for extracting the target gas. apparatus.

  In the present invention, the pressurizer has a gas disperser provided so as to be located in the hydrate slurry in the container, and the mixed gas supplied to the pressurizer is supplied from the gas disperser to the water in the container. It can be dispersed in a Japanese slurry.

  In the present invention, the pressure of the pressurizer is 50 to 500 kPaG, and the pressure of the decompressor is preferably 0 to 50 kPaG.

  In the present invention, the return path includes a pump that pumps the hydrate slurry from the decompressor to the pressurizer, and a cooler that lowers the hydrate slurry by the temperature rise due to pressurization by the pump. Preferably it is.

<Gas separation method>
In a gas separation method for separating a target gas by bringing a mixed gas containing the target gas into contact with a hydrate slurry, the mixed gas containing the target gas and another gas and a hydrate slurry are mixed in the pressurizer. The mixed gas and the hydrate slurry are pressurized while being in contact with each other, and the pressurized hydrate slurry is decompressed with a decompressor, and the hydrate slurry after decompressed with the decompressor is removed. A gas separation method characterized by returning to a pressurizer through a return path, exhausting a gas other than the target gas from the pressurizer, and extracting the target gas from the decompressor.

  In the present invention, the pressurizer has a gas disperser provided so as to be located in the hydrate slurry in the container, and the mixed gas supplied to the pressurizer is supplied from the gas disperser to the water in the container. It can be dispersed in a Japanese slurry.

  In the present invention, the pressure of the pressurizer is 50 to 500 kPaG, and the pressure of the decompressor is preferably 0 to 50 kPaG.

  In the present invention, it is preferable that the hydrate slurry from the decompressor is pumped toward the pressurizer by a pump, and the hydrate slurry is cooled by the cooler by the amount of temperature rise due to pressurization by the pump.

  In the apparatus and method of the present invention as described above, the hydrate selectively selects the target gas by pressurizing the mixed gas containing the target gas and the hydrate slurry in contact with each other in the container of the pressurizer. The target gas is released from the hydrate and the target gas is separated from the mixed gas by depressurizing the hydrate that has been absorbed and collected and the target gas is collected by the decompressor. In this way, the hydrate in the hydrate slurry is decompressed without being melted by the decompressor, and after the target gas is extracted, the hydrate slurry is maintained and returned to the pressurizer for mixing. The target gas is collected by contact with the gas and being pressurized. Therefore, cooling for producing the hydrate and heating for melting the hydrate are not required when the target gas is taken out from the hydrate.

  According to the apparatus and method of the present invention, the mixed gas in which the target gas and other gas are mixed and the hydrate slurry are supplied into the container of the pressurizer, and the mixed gas and the hydrate slurry are in contact with each other. Pressurize the hydrate to selectively collect the target gas, depressurize the hydrate slurry after pressurization with a decompressor to release the target gas from the hydrate, and decompress the water with the decompressor. The Japanese slurry is returned to the pressurizer via the return path, the gas other than the target gas is exhausted from the pressurizer, and the target gas is extracted from the decompressor, so a cooler for generating hydrates The heater for melting (decomposing) the hydrate is unnecessary, the whole apparatus becomes compact, there is no need for cold energy and heating energy, and energy for pressurization and decompression is necessary. The effect that the target gas can be separated with less energy is obtained. . Furthermore, since the hydrate-generating substance aqueous solution is not cooled to produce a hydrate, there is no need to use a production line for producing hydrates. There is also an effect that problems such as blockage in the pipeline do not occur.

It is a schematic block diagram of the gas separation apparatus as one Embodiment of this invention.

  Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 of the accompanying drawings.

  A gas separation device 1 as an embodiment of the present invention shown in FIG. 1 includes a pressurizer 11 that allows a hydrate in a hydrate slurry to absorb and collect a target gas under pressure, and a pressure reduction of the hydrate slurry. And a decompressor 12 that separates and extracts the target gas collected from the hydrate.

  Prior to the description of the constituent devices such as the pressurizer 11 and the decompressor 12, the hydrate product, the liquid for producing the hydrate, and the target gas will be described for the gas separation device 1.

<Hydrate product>
As a guest substance (hydrate product) that forms a hydrate, a quaternary ammonium salt, a quaternary phosphonium salt, a quaternary sulfonium salt, or the like can be used. Quaternary ammonium salts include tetra-n-butylammonium bromide (TBAB), tetra-isopentylammonium bromide (TiPAB), tri-n-butylpentylammonium bromide (TBPAB), tetra-n-butylammonium fluoride (TBAF), chloride Typical examples include tetraalkylammonium salts such as tetra-n-butylammonium (TBACl) and tetra-n-butylammonium iodide (TBAI), but are not limited thereto.

<Liquid that produces hydrate>
As an aqueous solution containing a hydrate product as a liquid for producing a hydrate, an aqueous solution containing the hydrate product can be used. Further, as the aqueous solution containing the hydrate product, an aqueous solution of tetraisopentylammonium bromide (TiPAB) is preferable. This is because the harmonic melting point of tetraisopentylammonium bromide is 30 ° C., and it is easy to adjust the concentration of the aqueous solution to adjust the hydrate formation temperature in the range of 0 to 30 ° C.

  Moreover, as an aqueous solution containing a hydrate product, an aqueous solution of two or more quaternary ammonium salts containing tetraisopentylammonium bromide is preferable. As a quaternary ammonium salt other than tetraisopentylammonium bromide, tetra-n-butylammonium bromide is preferable. Since tetra-n-butylammonium bromide is relatively inexpensive and readily available, the hydrate formation temperature is in the range of 0 to 30 ° C. by properly blending tetraisopentylammonium bromide and tetra-n-butylammonium bromide. It is possible to construct an apparatus and a method for collecting, releasing, and separating gas which is easy to adjust and is economically excellent.

  The higher the concentration of the liquid that forms the hydrate, that is, the hydrate product concentration of the aqueous solution containing the hydrate product, the higher the hydrate concentration in the hydrate slurry, the higher the hydrate concentration Since the amount of gas to be collected increases, it is preferable that the concentration of the hydrate product in the aqueous solution is high.

  When the guest substance is tetraisopentylammonium bromide, the concentration of the aqueous solution is preferably 0.1 to 35% by weight, and more preferably 1 to 15% by weight. If it is smaller than the lower limit, a large amount of aqueous solution is required as a gas separation device, and an excessively large container is required. Since the contact efficiency of the liquid which produces | generates a hydrate and a hydrate and target gas falls, it is unpreferable.

<Target gas>
Examples of the target gas separated from the mixed gas include carbon dioxide, oxygen, hydrogen sulfide, sulfur dioxide, and methane.

  Examples of collecting and separating a target gas from a mixed gas include separation of carbon dioxide as a target gas from a mixed gas containing methane and carbon dioxide to obtain a fuel gas having a high methane content, combustion exhaust gas, etc. For example, carbon dioxide is separated from a mixed gas to obtain a carbon dioxide-enriched gas, and oxygen is separated from air to obtain oxygen-enriched air. In addition, removal of hydrogen sulfide contained in the chemical raw material gas for the purpose of preventing deterioration of the catalyst and separation of sulfur dioxide in the combustion exhaust gas from the viewpoint of environmental conservation are also suitable examples.

  In the apparatus of the present embodiment, the pressurizer 11 receives the mixed gas A in which the above-described target gas and a gas other than the target gas are mixed, and the hydrate slurry returned from the decompressor 12, and these are in contact with each other. And has a container 11A, and a gas disperser 11B is disposed at the bottom of the container 11A.

  The container 11A is provided with a pressurizing means (not shown) or connected to pressurize the hydrate slurry with an internal pressure of 50 to 500 kPaG. The gas separator 11B is made of, for example, a tube member in which micropores are formed. The gas separator 11B is arranged in a hydrate slurry (described later) housed in the container 11A, and sends the mixed gas A from the outside. The gas mixture A is received through the trachea 13, and the mixed gas A is blown out into the hydrate slurry in the container 11 </ b> A from the micropore. The air supply pipe 13 is provided with a compressor 14, and is pressurized by the compressor 14 to a pressure sufficient to blow the mixed gas A from the outside through the micropores of the gas distributor 11 </ b> B. The air supply pipe 13 is provided with a cooler 15, and the temperature of the hydrate slurry is changed to the melting temperature of the hydrate when the mixed gas A is blown into the hydrate slurry in the container 11 </ b> A. The mixed gas A is cooled by the cooler 15 so as not to rise above.

  In addition, the container 11A is provided with a discharge port 16A for exhausting the gas in the space above the liquid level of the hydrate slurry in the container 11A (which will be described later but this is a gas other than the target gas) to the outside. The exhaust pipe 16B is connected here.

  The pressurizer 11 is connected to the pressure reducer 12 through a pump 17 through a liquid feeding pipe 18. The decompressor 12 receives a hydrate slurry under pressure from the pressurizer 11 and depressurizes the slurry to 0 to 50 kPaG. The decompressor 12 is a target gas outlet 19A for extracting a gas in the space above the liquid level of the hydrate slurry fed into the container of the decompressor 12 (which will be described later, this is a target gas) to the outside. Is provided, and a target gas extraction pipe 19B is connected thereto.

  The decompressor 12 is connected to a pipe forming a return path 20 for returning the internal hydrate slurry to the pressurizer 11 at the lower part of the container. The return path 20 returns to the container 11 </ b> A of the pressurizer 11.

  The return path 20 is provided with a pump 21, a stirrer 22, and a cooler 23. The pump 21 pumps the hydrate slurry from the pressure reducer 12 back to the pressurizer 11, and the stirrer 22 disturbs the flow of the returning hydrate slurry. Further, the cooler 23 cools the hydrate slurry by the amount of the temperature slightly increased by the pumping by the pump 21 and the stirring by the stirrer 22.

  A process for separating the target gas from the mixed gas in the gas separation device 1 of the present embodiment having the above-described configuration will be described below.

  The pressurizer 11 returns the hydrate slurry after decompression from the decompressor 12 through the return path 20 and is accommodated in the container 11 </ b> A of the pressurizer 11.

  The gas mixture A, in which the target gas supplied from an external supply source (not shown) and other gas are mixed, is compressed to a level appropriate for being blown out from the micropores of the gas distributor 11B. After being pressurized at 14, it is cooled by the cooler 15 to a temperature at which the hydrate in the hydrate slurry in the container 11 </ b> A is not melted. It is pumped to the gas disperser 11B.

  The pressurized mixed gas A is blown out from the micropores of the gas disperser 11B into the hydrate slurry in the container 11A to become bubbles and disperse and rise, but at that time, it comes into contact with the hydrate slurry. Since the inside of the container 11A is pressurized by a pressurizing means (not shown), the bubbles of the mixed gas A and the hydrate slurry come into contact with each other under the pressure. Under this pressure, the target gas in the mixed gas A is selectively absorbed and collected by the hydrate over the other gases and separated from other gases other than the target gas. Gases other than the target gas continue to rise in the hydrate slurry, reach the upper space from the liquid level of the hydrate slurry, and are stored. Gases other than the target gas in the space are taken out from the container 11A through the exhaust port 16A through the exhaust pipe 16B.

  The hydrate slurry containing the hydrate that has collected the target gas is sent to the decompressor 12 via the liquid feed pipe 18 by the pump 17. The hydrate slurry that has been pressurized by the pressurizer 11 is decompressed by the decompressor 12. The hydrate in the decompressed hydrate slurry releases the collected target gas. The discharged target gas is stored in the upper space of the decompressor 12 and is extracted from the target gas through the target gas outlet 19A and the target gas outlet pipe B. Thus, the target gas is separated from the mixed gas A and taken out.

  The hydrate slurry from which the target gas has been extracted is returned to the pressurizer 11 via the return path 20 and is used again to collect the target gas from the mixed gas A in the pressurizer 11. In the return path 20, the hydrate slurry is pumped by the pump 21 and is stirred by the stirrer 22, thereby disturbing the flow. When returning to the pressurizer 11, the hydrate slurry has a disorder. Therefore, the collection efficiency of the target gas by the hydrate is improved by increasing the contact efficiency with the target gas. Since the hydrate slurry receives heat from the pump 21 and the stirrer 22 in the return path 20, the hydrate slurry is cooled by the cooler 23 to prevent the hydrate from melting.

  Thus, the returned hydrate slurry is accommodated in the pressurizer 11 at a temperature at which the hydrate does not melt, and is again subjected to absorption and collection of the target gas by contact with the mixed gas under pressure. The

DESCRIPTION OF SYMBOLS 1 Gas separator 11 Pressurizer 11A Container 11B Gas disperser 12 Depressurizer 16A Discharge port 19A Target gas outlet 20 Return path 21 Pump 23 Cooler A Mixed gas

Claims (8)

In a gas separation device for separating a target gas by bringing a mixed gas containing the target gas into contact with a hydrate slurry,
A container and a pressurizing means for applying an internal pressure to the container; the supply of a mixed gas in which a target gas and another gas are mixed and the supply of a hydrate slurry are received in the container; A pressurizer that pressurizes the hydrate slurry in contact with each other; and a decompressor that receives the pressurized hydrate slurry from the pressurizer and depressurizes the hydrate slurry. After the pressurized hydrate slurry is depressurized by the decompressor, it is connected so as to return to the pressurizer via the return path. The pressurizer is a discharge port for exhausting gases other than the target gas, and the decompressor A gas separation apparatus comprising a target gas outlet for extracting a target gas.   The pressurizer has a gas disperser provided so as to be located in the hydrate slurry in the container, and the mixed gas supplied to the pressurizer is dispersed from the gas disperser into the hydrate slurry in the container. The gas separation device according to claim 1, wherein the gas separation device is configured to be configured.   The gas separator according to claim 1, wherein the pressure of the pressurizer is 50 to 500 kPaG, and the pressure of the decompressor is 0 to 50 kPaG.   The return path has a pump that pumps the hydrate slurry from the decompressor toward the pressurizer, and a cooler that cools the hydrate slurry by the temperature rise due to pressurization by the pump. The gas separator according to claim 1. In a gas separation method of separating a target gas by bringing a mixed gas containing the target gas into contact with a hydrate slurry,
A mixed gas containing a target gas and another gas and a hydrate slurry are supplied into the container, and the mixed gas and the hydrate slurry are pressurized in contact with each other. The hydrate slurry that has been decompressed by the decompressor is returned to the pressurizer via the return path, and the gas other than the target gas is exhausted from the pressurizer, and the target gas is extracted from the decompressor. A gas separation method comprising:   The pressurizer has a gas disperser provided so as to be positioned in the hydrate slurry in the container, and the mixed gas supplied to the pressurizer is dispersed from the gas disperser into the hydrate slurry in the container. The gas separation method according to claim 5 to be performed.   The gas separation method according to claim 5, wherein the pressure of the pressurizer is 50 to 500 kPaG, and the pressure of the decompressor is 0 to 50 kPaG.   6. The gas separation method according to claim 5, wherein the hydrate slurry from the decompressor is pumped by a pump toward the pressurizer, and the hydrate slurry is cooled by the cooler by an amount of temperature rise due to pressurization by the pump. .

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