ANG storage process

Abstract

The present invention discloses an ANG storage process, which includes: forming a first cavity and a second cavity that are not connected to each other in a storage tank, the volume of the first cavity being larger than that of the second cavity, and the second cavity being connected to a circulating natural gas circuit; respectively performing different processes of natural gas adsorption and natural gas desorption in the first cavity and the second cavity; and performing heat management by adjusting the charging and discharging rates of the first cavity and the second cavity. The ANG storage process of the present invention can perform heat management by adjusting the charging and discharging rates. When the first cavity is charged, heat is generated during adsorption. When the second cavity discharges gas, the temperature drops suddenly, and the cold quantity during gas discharge can neutralize the heat during adsorption. When the first cavity discharges gas for desorption, a temperature drop occurs, and the charging and adsorption of the second cavity play a heating role, avoiding gas retention when the first cavity desorbs.

Description

Technical Field

[0001] The present invention relates to the technical field of natural gas storage and transportation, and particularly to an ANG storage process. Background Art

[0002] There are the following several main storage and transportation technologies for natural gas: pipeline transportation (PNG), liquefaction (LNG), compression (CNG), and adsorption (ANG). Pipeline transportation requires huge investment and is only applicable to large gas fields. The LNG technology enables transportation vehicles to travel a relatively long distance, but it requires huge investment to build fuel stations along the way. The CNG technology requires multi-stage compression (for example, to reach a high pressure of 20 MPa, generally four-stage compression is required), with very high energy consumption and large investment in high-pressure filling equipment. In contrast, the ANG technology is relatively ideal. In the ANG technology, a suitable adsorbent is added to the gas cylinder, so that the storage density of natural gas at a relatively low pressure is equivalent to that of compressed natural gas at a high pressure (20 MPa), thus making up for the deficiencies of CNG. However, during the natural gas adsorption process, heat release occurs, and there is a temperature drop during desorption. In order to increase the adsorption capacity and avoid gas retention during desorption, heat management becomes one of the key issues in the ANG technology.

[0003] Patent document CN105987279A discloses an ANG transport vehicle, which includes a transport vehicle body and an ANG storage tank fixed on the transport vehicle body and filled with an adsorbent. An air charging and discharging pipeline is provided at a height of 1 / 6 - 1 / 3 of the ANG storage tank inside the ANG storage tank, and the air charging and discharging pipeline extends axially along the ANG storage tank to both end heads of the ANG storage tank. A heat exchange pipeline is wound outside the air charging and discharging pipeline, and the heat exchange pipeline is connected to the heat exchange system of the transport vehicle body. The heat exchange pipeline exchanges heat with the heat exchange system to achieve the purpose of heat stability during the natural gas adsorption and desorption processes. Although the transport vehicle is equipped with a compressor and stores a refrigerant, and the entire ANG transport vehicle becomes an independent system without the need for external supply of cold and hot water, an independent cooling medium (water), refrigerant, and cooling system are still introduced, increasing the load of the transport vehicle and bringing problems of increased economic cost and increased safety risk.

[0004] The information disclosed in this background art section is only intended to enhance the overall understanding of the present invention and should not be regarded as an admission or any form of implication that this information constitutes prior art already known to those of ordinary skill in the art. Summary of the Invention

[0005] One object of the present invention is to provide an ANG storage process, so as to improve the influence of the thermal effect on the adsorption process and / or desorption process in the natural gas adsorption storage and transportation technology.

[0006] Another object of the present invention is to provide an ANG storage process, so as to reduce the volume and cost of the natural gas adsorption storage and transportation equipment and improve safety.

[0007] To achieve the above object, the present invention provides an ANG storage process, which includes: forming a first cavity and a second cavity that are not connected to each other in a storage tank, the volume of the first cavity being larger than that of the second cavity, and the second cavity being connected to a circulating natural gas circuit; performing different processes of natural gas adsorption and natural gas desorption in the first cavity and the second cavity respectively; and performing heat management by adjusting the charging and discharging rates of the first cavity and the second cavity.

[0008] Further, in the above technical solution, when storing natural gas, the natural gas to be stored is charged into the first cavity, and at the same time, the circulating natural gas in the second cavity is discharged, and the discharging rate is 1.2 to 10 times, preferably 1.2 to 5 times, of the charging rate; when unloading natural gas, the natural gas stored in the first cavity is discharged, and at the same time, the circulating natural gas is charged into the second cavity, and the charging rate is 1.2 to 10 times, preferably 1.2 to 5 times, of the discharging rate.

[0009] Further, in the above technical solution, when storing natural gas, the pressure of the first cavity is monitored, and if the pressure of the first cavity is greater than 4 MPa, the charging is stopped.

[0010] Further, in the above technical solution, the volume of the first cavity is 4 to 20 times that of the second cavity.

[0011] Further, in the above technical solution, the storage tank is a horizontal storage tank, and the storage tank is provided with: a plurality of thin tubes arranged in the horizontal direction; and a tube sheet arranged at one end of the plurality of thin tubes, and the plurality of thin tubes are connected to the storage tank on one side of the tube sheet to form a second cavity, and the storage tank on the other side of the tube sheet forms a first cavity.

[0012] Further, in the above technical solution, the first cavity is provided with a sleeve, the sleeve coaxially penetrates through the storage tank, and a plurality of diffusion holes are uniformly distributed on the outer tube of the sleeve and are connected to the first cavity, one end of the inner tube of the sleeve is connected to the outer tube, and the other end is connected to the outside, and the sleeve is used for charging and discharging the first cavity.

[0013] Further, in the above technical solution, the plurality of thin tubes are radially distributed around the sleeve.

[0014] Further, in the above technical solution, the distance between the plurality of thin tubes gradually increases outward from the sleeve.

[0015] Further, in the above technical solution, the ratio of the diameter of the thin tube to the diameter of the storage tank is 1:20 to 100.

[0016] Further, in the above technical solution, the distance between the plurality of thin tubes is 1.5 to 20 times the diameter of the thin tube.

[0017] Further, in the above technical solution, the first cavity is filled with a first adsorbent, and the second cavity is filled with a second adsorbent, and the first adsorbent and the second adsorbent are the same or different.

[0018] Further, in the above technical solution, the first adsorbent and the second adsorbent are one or more of silica gel, activated carbon, alumina, MOFs materials, zeolite molecular sieves, and carbon molecular sieves.

[0019] Further, in the above technical solution, the circulating natural gas circuit is formed by connecting the second cavity, a compressor, and a high-pressure gas cylinder.

[0020] Compared with the prior art, the present invention has one or more of the following beneficial effects:

[0021] 1. In the ANG storage process of the present invention, by forming non-communicating first and second cavities in the storage tank, with the second cavity connected to the circulating natural gas circuit, different processes of natural gas adsorption and natural gas desorption are carried out in the first and second cavities respectively, so as to manage heat by adjusting the charging and discharging rates of gas. When the first cavity is charged, heat is generated during adsorption; when the second cavity discharges gas, the temperature drops suddenly, and the cold generated during gas discharge can neutralize the heat generated during adsorption. When the first cavity discharges gas for desorption, a temperature drop occurs, and when the second cavity is charged for adsorption, it plays a heating role, avoiding gas retention during the desorption of the first cavity.

[0022] 2. In the entire ANG storage process, whether it is the storage process or the unloading process, no other medium other than natural gas needs to be introduced, reducing the risk of leakage in the tank; the replenishment of natural gas in the second cavity can also use local materials, reducing the additional volume and cost of the entire equipment.

[0023] 3. Designing a sleeve as the natural gas charging and discharging channel of the first cavity can avoid uneven flow caused by uneven pressure, resulting in excessive local temperature.

[0024] 4. Multiple thin tubes are radially distributed around the sleeve, which conforms to the heat distribution law of the adsorbent and improves the heat management efficiency.

[0025] 5. The ANG storage process of the present invention requires no other external devices except for a compressor and a high-pressure gas cylinder, has a simple structure, and is convenient for operation and maintenance. The cold / heat can be increased by increasing the capacity of the high-pressure gas cylinder to meet the heat management requirements.

[0026] The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly and be able to implement it according to the content of the specification, and in order to make the above and other objects, technical features, and advantages of the present invention more understandable, one or more preferred embodiments are listed below and described in detail with reference to the accompanying drawings as follows. Description of the Drawings

[0027] Figure 1 Schematic structural diagram of an ANG storage device according to an embodiment of the present invention.

[0028] Figure 2 Cross-sectional schematic diagram of the storage tank of the ANG storage device according to an embodiment of the present invention.

[0029] Main reference numerals description:

[0030] 10 - storage tank, 11 - thin tube, 110 - main pipe, 12 - sleeve, 121 - outer tube, 1211 - diffusion hole, 122 - inner tube, 13 - tube sheet, 21 - first adsorbent, 22 - second adsorbent, 30 - compressor, 40 - high-pressure gas cylinder, 50 - base. Specific embodiments

[0031] The following combines the drawings to describe in detail the specific embodiments of the present invention. However, it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0032] Unless otherwise clearly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "having" etc. will be understood to include the stated elements or components, without excluding other elements or other components.

[0033] In this article, for the convenience of description, spatial relative terms such as "below", "beneath", "under", "above", "over", "on" etc. can 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 spatial relative terms are intended to encompass different directions of the object in use or operation in addition to the directions depicted in the figures. For example, if the object in the figure is flipped, the element described as "below" or "under" other elements or features will be oriented "above" the element or feature. Therefore, the exemplary term "below" can include both the below and above directions. The object can also have other orientations (rotated 90 degrees or other orientations) and the spatial relative terms used herein should be interpreted accordingly.

[0034] In this article, terms such as "first", "second" etc. are used to distinguish two different elements or parts, and are not used to limit a specific position or relative relationship. In other words, in some embodiments, the terms "first", "second" etc. can also be interchanged with each other.

[0035] According to the ANG storage process of the specific embodiment of the present invention, it includes: forming a first cavity and a second cavity that are not connected to each other in a storage tank, the volume of the first cavity is larger than that of the second cavity, and the second cavity is connected to a circulating natural gas circuit; different processes of natural gas adsorption and natural gas desorption are carried out in the first cavity and the second cavity respectively; and heat management is carried out by adjusting the charging and discharging rates of the first cavity and the second cavity.

[0036] Further, in one or more exemplary embodiments of the present invention, when storing natural gas, the natural gas to be stored is filled into the first cavity, and at the same time, the circulating natural gas in the second cavity is discharged, and the discharging rate is 1.2 to 10 times, preferably 1.2 to 5 times of the charging rate; when unloading natural gas, the stored natural gas in the first cavity is discharged, and at the same time, the circulating natural gas is filled into the second cavity, and the charging rate is 1.2 to 10 times, preferably 1.2 to 5 times of the discharging rate.

[0037] Further, in one or more exemplary embodiments of the present invention, when storing natural gas, the pressure of the first cavity is monitored, and if the pressure of the first cavity is greater than 4 MPa, the charging is stopped.

[0038] Further, in one or more exemplary embodiments of the present invention, the volume of the first cavity is 4 to 20 times that of the second cavity.

[0039] As Figure 1 and Figure 2 shown, in the ANG storage process according to the specific embodiment of the present invention, the storage tank 10 can be a horizontal storage tank. A plurality of thin tubes 11 arranged horizontally are provided in the storage tank 10, and a tube sheet 13 is provided at one end of the plurality of thin tubes 11. The plurality of thin tubes 11 are connected to the storage tank 10 on one side of the tube sheet 13 to form a second cavity, and the storage tank 10 (outside the thin tubes 11) on the other side of the tube sheet 13 forms a first cavity. The second cavity of the storage tank 10 is connected to the intake port of the compressor 30, the outlet of the compressor 30 is connected to the high-pressure gas cylinder 40, and the high-pressure gas cylinder 40 is further connected to the second cavity. The second cavity, the compressor 30 and the high-pressure gas cylinder 40 form a circuit for the circulating natural gas to flow. Exemplarily, the thin tubes 11 converge into a main pipe 110 and then are connected to the high-pressure gas cylinder 40. It should be understood that the shape of the main pipe 110 shown in the figure is only for illustration and does not limit the present invention. Exemplarily, the first cavity is provided with a sleeve 12 as a natural gas charging and discharging channel. The sleeve 12 coaxially penetrates through the storage tank 10. A plurality of diffusion holes 1211 are uniformly distributed on the outer tube 121 of the sleeve 12 and are connected to the first cavity. One end of the inner tube 122 of the sleeve 12 is connected to the outer tube 121, and the other end is connected to the outside. Exemplarily, no diffusion holes are provided on the outer tube 121 near the connection of the inner tube 122 and the outer tube 121.

[0040] Further, in one or more exemplary embodiments of the present invention, a plurality of thin tubes 11 are radially distributed around the sleeve 12. Further, in one or more exemplary embodiments of the present invention, the distance between the plurality of thin tubes 11 gradually increases outward from the sleeve 12, that is, the inner part is dense and the outer part is sparse.

[0041] Further, in one or more exemplary embodiments of the present invention, the ratio of the diameter of the thin tube 11 to the diameter of the storage tank 10 is 1:20 to 100, preferably 1:40 to 60. Further, in one or more exemplary embodiments of the present invention, the distance between the plurality of thin tubes 11 is 1.5 to 20 times the diameter of the thin tube 11.

[0042] Further, in one or more exemplary embodiments of the present invention, the first cavity is filled with the first adsorbent 21, and the second cavity is filled with the second adsorbent 22. The first adsorbent 21 and the second adsorbent 22 may be the same or different. Preferably, both the first adsorbent 21 and the second adsorbent 22 are activated carbon adsorbents, which is convenient for process condition control. It should be understood that the present invention is not limited thereto, and the first adsorbent 21 and the second adsorbent 22 may be one or several of silica gel, activated carbon, alumina, MOFs materials, zeolite molecular sieves, and carbon molecular sieves.

[0043] Further, in one or more exemplary embodiments of the present invention, the storage tank 10, the compressor 30, and the high-pressure gas cylinder 40 are all arranged on the base 50. The base 50 can be transported by vehicle or skid-mounted, which is convenient for storage and transportation.

[0044] Further, in one or more exemplary embodiments of the present invention, the second cavity of the storage tank 10 is provided with a gas supplement port (not shown in the figure). For example, the gas supplement port can be arranged on the head on the side connected to the compressor. The gas supplement port is used to supplement the circulating natural gas in the circuit formed by the second cavity, the compressor 30, and the high-pressure gas cylinder 40.

[0045] The ANG storage process and its usage method of the present invention will be described in more detail by way of specific examples below. It should be understood that the examples are only exemplary, and the present invention is not limited thereto.

[0046] Example 1

[0047] This example uses as Figure 1The storage device shown, where the storage tank 10 is a horizontal storage tank. In the storage tank 10, there are multiple thin tubes 11 arranged horizontally. One end of the multiple thin tubes 11 is provided with a tube sheet 13. The multiple thin tubes 11 communicate with the storage tank 10 on one side of the tube sheet 13 to form a second cavity, and the storage tank 10 (outside the thin tubes 11) on the other side of the tube sheet 13 forms a first cavity. The first cavity and the second cavity are not in communication with each other, and the volume of the first cavity is 8 times the volume of the second cavity. The natural gas charging and discharging channel of the first cavity is a sleeve 12. The sleeve 12 coaxially penetrates through the storage tank 10. A plurality of diffusion holes 1211 are evenly distributed on the outer tube 121 of the sleeve 12. The diffusion holes 1211 communicate with the first cavity. One end of the inner tube 122 of the sleeve 12 is communicated with the outer tube 121, and the other end of the inner tube 122 is connected to the outside. The thin tubes 11 are radially distributed with the sleeve 12 as the center and are denser inside and sparser outside. Both the first cavity and the second cavity are filled with activated carbon as an adsorbent.

[0048] When storing gas using the ANG storage process of this embodiment: Connect the inner tube 122 of the sleeve 12 to an external gas source. Natural gas enters the storage tank 10 through the inner tube 122 at a rate of 1.5 m 3 / h, diffuses into the first cavity through the diffusion holes 1211 of the outer tube 121. The adsorbent in the first cavity adsorbs the natural gas and releases heat. When the pressure in the first cavity reaches 4 MPa, close the external gas source. While the first cavity is being filled with gas, start the compressor 30 to compress the recycled natural gas released from the second cavity at a rate of 1.8 m 3 / h and store it in the high-pressure gas cylinder 40. The desorption endotherm of the recycled natural gas in the second cavity balances the exotherm of the gas adsorption in the first cavity, and the temperature of the entire storage tank 10 remains basically unchanged.

[0049] When unloading using the ANG storage process of this embodiment, open the valve 1221 of the inner tube 122 of the sleeve 12. The natural gas in the first cavity is released through the inner tube 122 at a rate of 1.2 m 3 / h, and the gas desorbs and absorbs heat. While the first cavity is discharging gas, the recycled natural gas stored in the high-pressure gas cylinder 40 is filled into the second cavity at a rate of 1.5 m 3 / h. The adsorbent in the second cavity adsorbs the recycled natural gas and releases heat, providing heat for the gas desorption in the first cavity and improving the desorption efficiency.

[0050] After calculation, using the ANG storage process of this embodiment, during the desorption process of the first cavity, the lowest temperature at the center can be increased by 24.2 °C, and during the adsorption process of the first cavity, the highest temperature at the center of the storage tank can be decreased by 20.4 °C, and both the adsorption and desorption efficiencies are significantly improved. In addition, the ANG storage process of this embodiment does not require introducing media other than natural gas, greatly improving the use safety.

[0051] Embodiment 2

[0052] In this embodiment, the volume of the first cavity is 15 times that of the second cavity. During gas storage, the gas release rate of the second cavity is 2.6 times the gas filling rate of the first cavity; during unloading, the gas filling rate of the second cavity is 3.1 times the gas release rate of the first cavity. Other conditions are the same as those in Embodiment 1 and will not be elaborated here.

[0053] Through calculation, with the ANG storage process of this embodiment, during the desorption process of the first cavity, the lowest temperature at the center can be increased by 31.3 °C, while during the adsorption process of the first cavity, the highest temperature at the center of the storage tank can be decreased by 28.5 °C, and both the adsorption and desorption efficiencies are significantly improved. In addition, the ANG storage process of this embodiment does not require introducing media other than natural gas, greatly improving the use safety.

[0054] The foregoing description of specific exemplary embodiments of the present invention is for purposes of illustration and exemplification. These descriptions are not intended to limit the invention to the precise forms disclosed, and obviously, many changes and variations are possible in light of the above teachings. The purpose of selecting and describing the exemplary embodiments is to explain the specific principles of the invention and its practical applications, enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different selections and changes. Any simple modification, equivalent change, and modification made to the above exemplary embodiments shall fall within the protection scope of the present invention.

Claims

1. An ANG storage process, characterized in that, Comprising: Forming non - communicating first and second cavities in a storage tank, the volume of the first cavity being larger than that of the second cavity, and the second cavity being connected to a circulating natural gas circuit; the storage tank is a horizontal storage tank, and inside the storage tank are provided: a plurality of thin tubes arranged horizontally; and a tube sheet provided at one end of the plurality of thin tubes, the plurality of thin tubes communicate with the storage tank on one side of the tube sheet to form the second cavity, and the storage tank on the other side of the tube sheet forms the first cavity; the first cavity is provided with a sleeve, the sleeve coaxially penetrates through the storage tank, and a plurality of diffusion holes are evenly distributed on the outer tube of the sleeve and communicate with the first cavity, one end of the inner tube of the sleeve communicates with the outer tube, and the other end is connected to the outside, and the sleeve is used for inflating and deflating the first cavity; no diffusion holes are provided on the outer tube near the connection between the inner tube and the outer tube; Carrying out different processes in the first cavity for natural gas adsorption and in the second cavity for natural gas desorption respectively; and Managing heat by adjusting the charging and discharging rates of the first cavity and the second cavity.

2. The ANG storage process according to claim 1, wherein, When storing natural gas, the natural gas to be stored is charged into the first cavity, and at the same time, the circulating natural gas in the second cavity is discharged, and the discharging rate is 1.2 - 10 times the charging rate; when unloading natural gas, the stored natural gas in the first cavity is discharged, and at the same time, the circulating natural gas is charged into the second cavity, and the charging rate is 1.2 - 10 times the discharging rate.

3. The ANG storage process according to claim 2, characterized in that, When storing natural gas, the pressure of the first cavity is monitored, and if the pressure of the first cavity is greater than 4 MPa, the charging is stopped.

4. The ANG storage process according to claim 2, characterized in that, The volume of the first cavity is 4 - 20 times the volume of the second cavity.

5. The ANG storage process according to claim 1, wherein The plurality of thin tubes are radially distributed with the sleeve as the center.

6. The ANG storage process according to claim 5, wherein The distance between the plurality of thin tubes gradually increases outward from the sleeve.

7. The ANG storage process according to claim 1, characterized in that, The ratio of the diameter of the thin tube to the diameter of the storage tank is 1:20 - 100.

8. The ANG storage process according to claim 1, characterized in that, The distance between the plurality of thin tubes is 1.5 - 20 times the diameter of the thin tube.

9. The ANG storage process according to claim 2, wherein, The first cavity is filled with a first adsorbent, and the second cavity is filled with a second adsorbent, and the first adsorbent and the second adsorbent may be the same or different.

10. The ANG storage process according to claim 9, characterized in that, The first adsorbent and the second adsorbent are one or several of silica gel, activated carbon, alumina, MOFs materials, zeolite molecular sieves, and carbon molecular sieves.

11. The ANG storage process according to claim 1, characterized in that, The circulating natural gas circuit is formed by connecting the second cavity, a compressor, and a high - pressure gas cylinder.

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