阅读说明：本技术 一种加气站液化天然气的使用方法及系统 (Use method and system of liquefied natural gas of gas station ) 是由 彭国干 刘春江 孙磊 罗军 韦育强 盖云 于 2020-12-16 设计创作，主要内容包括：本发明涉及一种加气站液化天然气的使用方法及系统,将液化乙烷贮存装置中液化乙烷和/或液化丙烷输送至液化天然气贮存装置中与液化天然气混合；在液化乙烷和/或液化丙烷与液化天然气混合的同时,将掺混物贮存装置或液化天然气贮存装置中物质以气态形式输送至掺混物贮存装置,对掺混物贮存装置的上层气体加压。此种液化天然气使用方法及系统可以提高加气站液化天然气供气使用时的能效,并提高使用过程中的安全性能。(The invention relates to a method and a system for using liquefied natural gas of a gas station, which are characterized in that liquefied ethane and/or liquefied propane in a liquefied ethane storage device are conveyed to the liquefied natural gas storage device to be mixed with the liquefied natural gas; while liquefied ethane and/or liquefied propane is mixed with liquefied natural gas, the substance in the blend storage unit or the liquefied natural gas storage unit is transported in a gaseous form to the blend storage unit, and the upper layer gas of the blend storage unit is pressurized. The method and the system for using the liquefied natural gas can improve the energy efficiency of the liquefied natural gas in the gas station during gas supply and improve the safety performance in the using process.)

1. A method for using liquefied natural gas of a gas filling station is characterized by comprising the following steps:

storing liquefied ethane and/or liquefied propane in a blend storage unit and liquefied natural gas in a liquefied natural gas storage unit;

conveying the liquefied ethane and/or liquefied propane in the liquefied ethane storage device to the liquefied natural gas storage device to be mixed with the liquefied natural gas;

transporting the substance in the blend storage unit or the liquefied natural gas storage unit in a gaseous form to the blend storage unit while the liquefied ethane and/or liquefied propane is mixed with the liquefied natural gas, pressurizing an upper layer gas of the blend storage unit;

and stopping the transportation of the liquefied ethane and/or liquefied propane from the blend storage device to the liquefied natural gas storage device after the ratio of the liquefied ethane and/or liquefied propane to the liquefied natural gas in the liquefied natural gas storage device reaches a preset value.

2. The method of using liquefied natural gas from a gas station according to claim 1, wherein pressurizing the upper layer gas of the blend storage device while the liquefied ethane and/or liquefied propane is mixed with the liquefied natural gas comprises:

and pumping the upper layer gas of the liquefied natural gas storage device through a BOG compressor, pressurizing, and conveying to an upper gas inlet of the mixture storage device.

3. The method of using liquefied natural gas from a gas station according to claim 1, wherein pressurizing the upper layer gas of the blend storage device while the liquefied ethane and/or liquefied propane is mixed with the liquefied natural gas comprises:

liquefied ethane and/or liquefied propane is delivered to a vaporizer and returned to the upper inlet of the blend storage device after vaporization.

4. The method as claimed in claim 2 or 3, wherein the operation of the BOG compressor or the gasifier is controlled according to the pressure in the lng storage device during the mixing of the liquefied ethane and/or liquefied propane with the lng.

5. The method for using liquefied natural gas at a gas station according to any one of claims 1 to 3, wherein when the liquefied ethane and/or liquefied propane is mixed with the liquefied natural gas in the liquefied natural gas storage unit in a ratio of 40:100 parts by weight, the supply of the liquefied ethane and/or liquefied propane to the liquefied natural gas storage unit is stopped.

6. A liquefied natural gas system of a gas station, comprising a blend storage device (10) for storing liquefied ethane and/or liquefied propane, a liquefied natural gas storage device (20), a blend transfer line (40), wherein the blend storage device (10) has a first lower liquid outlet (101) and an upper gas inlet (102), and the first lower liquid outlet (101) is connected with the liquefied natural gas storage device (20) through the blend transfer line (40);

the system also includes a pressurization device that delivers material in the blend storage device (10) or the liquefied natural gas storage device (20) in gaseous form to an upper gas inlet (102) of the blend storage device (10) to pressurize the upper gas in the blend storage device (10).

7. The liquefied natural gas system of a gas filling station according to claim 6, wherein the pressurizing device comprises an input pipeline (50), an output pipeline (60), and a BOG compressor (30), the liquefied natural gas storage device (20) has an upper gas outlet (201), the upper gas outlet (201) is connected to an inlet of the BOG compressor (30) through the input pipeline (50), and an outlet of the BOG compressor (30) is connected to the upper gas inlet of the admixture storage device (10) through the output pipeline (60).

8. The liquefied natural gas system of a gas station according to claim 6, wherein the pressurizing device comprises an input pipeline (50), an output pipeline (60), and a vaporizer (70), the admixture storage device (10) has a second lower liquid inlet (103), the second lower liquid inlet (103) is connected to an inlet of the vaporizer (70) through the input pipeline (50), and an outlet of the vaporizer (30) is connected to the upper gas inlet (102) of the admixture storage device (10) through the output pipeline (60).

9. The liquefied natural gas system of a gas filling station according to claim 5, wherein the first lower liquid outlet (101) of the blend storage unit (10) is communicated with the upper liquid inlet (203) of the liquefied natural gas storage unit (20) through a blend transfer line (40).

10. The lng system of a gas station according to claim 7 or 8, wherein the blend transfer line (40) is provided with a first control valve (401), and the input line (50) is provided with a second control valve (501).

Technical Field

The invention relates to the field of Liquefied Natural Gas (LNG) of gas filling stations, in particular to a using method and a using system of the LNG of the gas filling station.

Background

LNG contains methane as a main component and a small amount of substances usually contained in the production process of natural gas such as ethane and propane. Depending on the process, LNG is produced with slightly different methane, ethane, and propane components, but these differences do not affect the common usage of LNG in the prior art. The use of lng should give priority to energy efficiency and safety issues. Energy efficiency is related to fuel cost, research and development enterprises such as natural gas engine manufacturers generally aim to optimize the internal structure of a power system, the efficiency of the novel natural gas engine can be improved under the condition of not sacrificing power, the emission of carbon dioxide is reduced, and limited natural gas resources are fully utilized. The prior art also uses new fuel forms as an alternative energy source for natural gas by pushing out. In addition, the safety of lng use is an important issue related to human and property. While storage of LNG is easily dangerous. In the prior art, for example, the safety of LNG use is improved by designing a liquefied natural gas cylinder structure for a vehicle or the like. However, safety and energy efficiency of LNG still need to be greatly improved.

Disclosure of Invention

In order to overcome at least one of the defects of the prior art, the invention provides a method and a system for using liquefied natural gas of a gas filling station.

The technical scheme adopted by the invention for solving the problems is as follows:

a method for using liquefied natural gas of a gas filling station comprises the following steps:

storing liquefied ethane and/or liquefied propane in a blend storage unit and liquefied natural gas in a liquefied natural gas storage unit;

conveying the liquefied ethane and/or liquefied propane in the liquefied ethane storage device to the liquefied natural gas storage device to be mixed with the liquefied natural gas;

transporting the substance in the blend storage unit or the liquefied natural gas storage unit in a gaseous form to the blend storage unit while the liquefied ethane and/or liquefied propane is mixed with the liquefied natural gas, pressurizing an upper layer gas of the blend storage unit;

and stopping the transportation of the liquefied ethane and/or liquefied propane from the blend storage device to the liquefied natural gas storage device after the ratio of the liquefied ethane and/or liquefied propane to the liquefied natural gas in the liquefied natural gas storage device reaches a preset value.

Preferably, pressurizing the upper layer gas of the blend storage device while the liquefied ethane and/or liquefied propane is mixed with the liquefied natural gas comprises:

and pumping the upper layer gas of the liquefied natural gas storage device through a BOG compressor, pressurizing, and conveying to an upper gas inlet of the mixture storage device.

Preferably, pressurizing the upper layer gas of the blend storage device while the liquefied ethane and/or liquefied propane is mixed with the liquefied natural gas comprises:

liquefied ethane and/or liquefied propane is delivered to a vaporizer and returned to the upper inlet of the blend storage device after vaporization.

Preferably, the operation of the BOG compressor or the gasifier is controlled according to the pressure in the lng storage during the mixing of the liquefied ethane and/or liquefied propane with the lng.

Preferably, when the mixing ratio of the liquefied ethane and/or liquefied propane to the liquefied natural gas in the liquefied natural gas storage device reaches 40:100 parts by weight, the transportation of the liquefied ethane and/or liquefied propane into the liquefied natural gas storage device is stopped.

The invention also provides a liquefied natural gas system of the gas station, which comprises a blend storage device for storing liquefied ethane and/or liquefied propane, a liquefied natural gas storage device and a blend conveying pipeline, wherein the blend storage device is provided with a first lower liquid outlet and an upper air inlet, and the first lower liquid outlet is connected with the liquefied natural gas storage device through the blend conveying pipeline;

the system also includes a pressurization device that delivers material from the blend storage device or the liquefied natural gas storage device in gaseous form to an upper gas inlet of the blend storage device, pressurizing an upper layer of gas in the blend storage device.

Preferably, the pressurizing device comprises an input pipeline, an output pipeline and a BOG compressor, the liquefied natural gas storage device is provided with an upper gas outlet, the upper gas outlet is connected with an inlet of the BOG compressor through the input pipeline, and an outlet of the BOG compressor is connected with the upper gas inlet of the mixture storage device through the output pipeline.

Preferably, the pressurizing device comprises an input pipeline, an output pipeline and a gasifier, the admixture storage device is provided with a second lower liquid inlet, the second lower liquid inlet is connected with an inlet of the gasifier through the input pipeline, and an outlet of the gasifier is connected with the upper air inlet of the admixture storage device through the output pipeline.

Preferably, the first lower liquid outlet of the blend storage device is communicated with the upper liquid inlet of the liquefied natural gas storage device through a blend conveying pipeline.

Preferably, a first control valve is arranged on the blending material conveying pipeline, and a second control valve is arranged on the input pipeline.

The method and the system mix the liquefied ethane and/or the liquefied propane into the liquefied natural gas of the gas station for gas use. On the one hand, the efficiency of the liquefied natural gas can be improved, and on the other hand, the use safety of the liquefied natural gas can also be improved. During blending of liquefied ethane or liquefied propane, the pressure inside the lng storage facility may rise significantly. In order to solve the problem, the invention also ensures the stability of the pressure in the liquefied natural gas storage device and the transportation of liquefied ethane and/or liquefied propane through pressurized transportation, and further improves the safety.

Drawings

FIG. 1 is a method of using a fueling station liquefied natural gas and a fueling station liquefied natural gas system according to a first embodiment of the present invention;

FIG. 2 is a diagram of a method of using a fueling station liquefied natural gas and a fueling station liquefied natural gas system in accordance with a second embodiment of the present invention;

FIG. 3 is a method of using a liquefied natural gas at a fueling station and a liquefied natural gas system at a fueling station according to a third embodiment of the present invention;

fig. 4 shows a method for using liquefied natural gas at a gas filling station and a liquefied natural gas system at a gas filling station according to a fourth embodiment of the invention.

Detailed Description

For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention.

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. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

First embodiment

The embodiment is a method for using liquefied natural gas of a gas station, and the method comprises the following steps:

storing liquefied ethane and/or liquefied propane in a blend storage unit and liquefied natural gas in a liquefied natural gas storage unit;

conveying the liquefied ethane and/or liquefied propane in the liquefied ethane storage device to the liquefied natural gas storage device to be mixed with the liquefied natural gas;

transporting the substance in the blend storage unit or the liquefied natural gas storage unit in a gaseous state to the blend storage unit while mixing liquefied ethane and/or liquefied propane with liquefied natural gas, and pressurizing the upper layer gas of the blend storage unit;

and stopping the transportation of the liquefied ethane and/or the liquefied propane from the mixture storage device to the liquefied natural gas storage device after the ratio of the liquefied ethane and/or the liquefied propane to the liquefied natural gas in the liquefied natural gas storage device reaches a preset value.

In this embodiment, the liquefied natural gas storage device is a liquefied natural gas storage tank commonly used in gas stations, the blend storage device is a liquefied ethane tank used in the method when the blend is liquefied ethane, the blend storage device is a liquefied propane tank used in the method when the blend is liquefied propane, and the blend storage device is a cryogenic storage tank used in the method when the blend is a mixture of liquefied ethane and propane. The method of the present embodiment is operated with the lng having been unloaded. In other embodiments, the lng storage facility is a tanker that transports lng. The method will be used before the completion of the unloading of the tanker, where the liquefied ethane and/or liquefied propane in the cryogenic storage tank is blended with the liquefied natural gas in the tanker. The present invention is not particularly limited to the storage device used.

The standard boiling point of liquefied ethane is-89 ℃, the standard boiling point of liquefied propane is-42 ℃, and the standard boiling point of liquefied natural gas is-161 ℃. When the liquefied mixture is mixed into liquefied natural gas, instant boiling can be generated, so that the pressure in the liquefied natural gas storage device is increased, the pressure in the liquefied natural gas storage device reaches the pressure of the mixture storage device, and the mixing is not easy to perform.

Pressurizing the upper layer of the blend storage means by transporting the blend storage means or the substance in said liquefied natural gas storage means in gaseous form to the blend storage means while the blend is mixed with the liquefied natural gas. Thus, the pressure in the mixture storage device is increased to be higher than the pressure in the liquefied natural gas storage device, and the mixing is smoothly performed.

After the liquefied natural gas is mixed with certain liquefied ethane and/or liquefied propane for storage, when a vehicle is aerated, the liquid enables the power of the vehicle LNG engine to be enhanced, and the endurance mileage of the mixed LNG is increased by adding the same kilogram of LNG. Although the heat value of 1 kilogram of natural gas is greater than that of 1 kilogram of ethane, the heat value of 1 kilogram of propane is greater than that of 1 kilogram of natural gas, the utilization efficiency of the liquid obtained by mixing ethane and/or propane with the natural gas in an engine is improved, and the power of the mixed liquefied natural gas is enhanced. If the natural gas is adopted for combustion, because the combustion speed of the natural gas is low, a part of the natural gas does not combust in the cylinder to do work and enters the flue to combust, and the heat is released to form useless work. When ethane or propane is mixed with natural gas, because the combustion rate of ethane is greater than that of methane, and the combustion rate of propane is greater than that of ethane, the phenomenon that the methane in an engine escapes from liquefied natural gas is reduced, the flame temperature of ethane and propane is higher than that of methane, and the working utilization efficiency of the mixed fuel is improved.

If ethane or propane is used without blending liquefied natural gas, it is heavier than air and is prone to danger. When blended into liquefied natural gas, the liquefied natural gas is mainly used, and the natural gas is lighter in density than air and easy to diffuse, thereby improving the safety of use compared with the use of ethane and/or propane alone.

In a preferred embodiment, the liquefied natural gas storage unit upper layer gas is pumped by a BOG compressor and pressurized before being sent to the blend storage unit upper inlet.

The flash Gas in the lng storage is pumped out and pressurized by a BOG (Boil Off Gas) compressor and returned to the blend storage. The pressurized flash steam can increase the pressure in the admixture storage device, reduce the pressure of the liquefied natural gas storage device in the process of mixing tragedly, facilitate the transportation of the admixture, solve the problem caused by instant boiling in the process of mixing and avoid the problem of overpressure discharge of the liquefied natural gas storage device.

In a preferred embodiment, the operation of the BOG compressor is controlled during the mixing of the liquefied ethane and/or liquefied propane with the liquefied natural gas based on the pressure in the liquefied natural gas storage. The power consumption of the compressor can be saved, and the internal pressure of the liquefied natural gas storage device is maintained within a safe range through the start and stop of the BOG compressor. Preferably, the BOG compressor is turned on when the pressure of the lng storage is greater than a predetermined maximum pressure. The BOG compressor is turned off when the pressure of the lng storage is less than a predetermined minimum pressure.

In this embodiment, when the mass ratio of the liquefied ethane and/or liquefied propane to the liquefied natural gas in the liquefied natural gas storage device reaches a predetermined ratio, the transportation of the liquefied blend to the liquefied natural gas storage device is stopped, and the predetermined ratio is preferably between 5:100 and 40: 100. In a preferred embodiment, the predetermined ratio is 40: 100. The liquefied natural gas supplied under the mass ratio can improve the combustion efficiency and ensure the safety of the fuel.

The first embodiment correspondingly provides a liquefied natural gas system of a gas filling station, which comprises a blend storage device 10, a blend storage device 20 and a blend conveying pipeline 40. The blend storage device 10 is for storing liquefied ethane and/or liquefied propane and has an upper gaseous region 10A and a lower liquid region 10B inside. The liquefied natural gas storage facility 20 has an upper gaseous zone 20A and a lower liquefaction zone 20B therein, as shown in fig. 1.

In the present embodiment, the lng storage 20 is an lng tank of a gas station or a tanker for transporting lng. The liquefied ethane and/or liquefied propane storage device 10 is a liquefied ethane and/or liquefied propane storage tank.

The blend storage device 10 has a first lower outlet port 101 and an upper inlet port 102. The first lower outlet port 101 is positioned in the lower liquid zone 10B under normal use of the admixture reservoir 10. The upper gas inlet 102 is positioned to provide an upper gaseous zone 10A under normal use of the admixture storage facility 10. In the preferred embodiment, the first lower outlet port 101 is located at the bottom of the admixture storage unit 10 and the upper inlet port 102 is located at the top of the admixture storage unit 10 to provide for the proper outflow of liquefied admixture. The first lower outlet ports 101 are connected by a blend transfer line 40 to the residual liquefied natural gas storage facility 20.

The system of this embodiment also includes a pressurizing device that delivers the substance in the blend storage device 10 or the liquefied natural gas storage device 20 in gaseous form to the upper gas inlet 102 of the blend storage device 10 to pressurize the upper gas in the blend storage device 10, i.e., the upper gaseous region 10A.

In the present embodiment, as shown in FIG. 1, the pressurizing means comprises an input line 50, an output line 60, a BOG compressor 30. The liquefied natural gas storage facility 20 has an upper gas outlet 201, and the upper gas outlet 201 is located in an upper gaseous region 20A under normal use of the liquefied natural gas storage facility 20, preferably at the top of the liquefied natural gas storage facility 20. The upper outlet port 201 is connected to the inlet of the BOG compressor 30 via the inlet line 50, and the outlet of the BOG compressor 30 is connected to the upper inlet port 102 of the blend storage device 10 via the outlet line 60.

The lng storage facility 20 has a lower liquid inlet 202, and the lower liquid inlet 202 is provided in the lower liquid region 20B of the lng storage facility 20 in normal use. The outlet of the admixture delivery line 40 is connected to the lower liquid inlet 202.

In this embodiment, a first control valve 401 is provided in the admixture delivery line 40 and a second control valve 501 is provided in the input line 50. In this embodiment, the first control valve 401 and the second control valve 501 are flow valves. The flow rate of the liquefied ethane and/or liquefied propane supplied from the blend storage unit 10 to the liquefied natural gas storage unit 20 is controlled by adjusting the opening degree of the first control valve 401. The flow rate of the pressurized gas is controlled by adjusting the opening degree of the second control valve 501. Specifically, the first control valve 401 is adjusted to be closed after the ratio of liquefied ethane and/or liquefied propane to liquefied natural gas in the liquefied natural gas storage device reaches a predetermined ratio. The second control valve 501 may be opened with the BOG compressor 30 by adjusting the opening of the valve to regulate the flow into the BOG compressor 30.

In a preferred embodiment, a flow meter is provided on the admixture delivery conduit 40. The flow rate of the input blend, liquefied ethane and/or liquefied propane, is calculated by the flow meter, thereby calculating the ratio of the blended liquefied ethane and/or liquefied propane to the liquefied natural gas.

Second embodiment

Fig. 2 shows a second embodiment of the present invention. In the present second embodiment, the liquefied natural gas storage 20 is provided with the upper liquid intake port 203, which is different from the first embodiment. The upper feed port 203 is selectively positioned in the upper gasification zone 20A under normal storage use of the lng storage 20, and is preferably positioned at the top of the lng storage 20 as shown in fig. 2. The lower outlet port 101 is connected to the upper inlet port 203 of the liquefied natural gas storage apparatus 20 through the blend delivery line 40. When liquefied ethane and/or propane enters the liquefied natural gas storage device 20 from the upper liquid inlet 203, the liquefied ethane and/or propane will contact with the gas in the upper gasification zone 20A, and the gas in the upper gasification zone 20A is liquefied, which can help to reduce the pressure in the liquefied natural gas storage device 20 and reduce the influence of instant boiling during the mixing process.

First and second control valves 401, 501 are provided in the respective admixture delivery line 40, 50.

Third embodiment

Fig. 3 shows a third embodiment of the present invention. The method and system of this third embodiment differ from the second embodiment in that pressurizing the upper layer gas of the blend storage device while mixing liquefied ethane and/or liquefied propane with liquefied natural gas comprises: the liquefied ethane and/or liquefied propane is sent to a vaporizer and returned to the upper inlet of the blend storage device after vaporization.

The liquefied mixture is gasified by the gasifier and returned to the mixture storage device, so that the internal pressure of the mixture storage device is increased, and the mixture is conveyed along with pressure.

In this embodiment, the operation of the vaporizer is controlled according to the pressure in the lng storage during the mixing of the liquefied ethane and/or liquefied propane with the lng. Preferably, the gasifier is shut down at a pressure of the lng storage greater than a preset first pressure. And starting the gasifier when the pressure of the liquefied natural gas storage device is less than the preset second pressure. Maintaining the lng storage pressure within a predetermined second pressure and a predetermined first pressure range.

Accordingly, in the system of the present embodiment, the pressurizing device includes an input line 50, an output line 60, and a vaporizer 70. The admixture storage device 10 has a second letdown liquid inlet 103, and the second letdown liquid inlet 103 is positioned in the lower liquid zone 10B under normal use of the admixture storage device 10. In other embodiments, the first and second liquid descending ports 101 and 103 may be the same outlet, connected to different pipes.

The second lower inlet 103 is connected to the inlet of the gasifier 70 via the inlet line 50, and the outlet of the gasifier 30 is connected to the upper inlet 102 of the admixture storage facility 10 via the outlet line 60.

First and second control valves 401, 501 are provided in the respective admixture delivery line 40, 50.

Fourth embodiment

Fig. 4 shows a fourth embodiment of the present invention. In the fourth embodiment, the difference from the third embodiment is that the location where the blend delivery line 40 is connected to the lng storage facility 20 is the lower liquid inlet 202. First and second control valves 401, 501 are provided in the respective admixture delivery line 40, 50.

The technical means disclosed in the invention scheme are not limited to the technical means disclosed in the above embodiments, but also include the technical scheme formed by any combination of the above technical features. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principle of the present invention, and such improvements and modifications are also considered to be within the scope of the present invention.