LNG sampling and analysis system and method

Abstract

The present invention provides an LNG sampling and analysis system and method, the system comprises a cryogenic liquid delivery module, a gasification module, a boosting module, and a sampling module which are sequentially arranged along an LNG sampling pipeline, and an online analysis module is connected between the boosting module and the sampling module. The cryogenic liquid is obtained by the cryogenic liquid delivery module, and is stored in a sampling cylinder of the sampling module after being gasified by the gasification module and pressurized by the boosting module. The present invention can effectively solve the gasification discrimination problem in the LNG sampling process, and can simultaneously perform sampling and online analysis operations.

Description

Technical Field

[0001] The invention belongs to the field of natural gas, and in particular relates to an LNG sampling and analysis system and method. Background Art

[0002] At present, under the guidance of national energy policies, natural gas consumption has increased significantly. For places where gas pipelines are not laid, LNG is more convenient to store and transport than gaseous methane. According to statistics from relevant agencies, 90 million tons of natural gas were imported in 2018, of which 53 million tons were LNG. At the same time, many domestic natural gas liquefaction companies and coal-based natural gas companies with coal as the source have a demand for LNG testing.

[0003] In addition to methane, LNG also contains a small amount of nitrogen, hydrogen, and low-carbon hydrocarbons such as ethane and ethylene, depending on the source. During the LNG gasification sampling process, components with different boiling points are gasified and disproportionated, resulting in the sample being unrepresentative. Simply put, the gasification ratios of components with different boiling points are different, with low-boiling-point components having a high gasification ratio and high-boiling-point components having a low gasification ratio, resulting in a difference between the composition of the gas sample obtained and the actual composition of LNG, which affects the final test results. Summary of the invention

[0004] The present invention provides an LNG sampling and analysis system and method, which are used to solve the gasification discrimination effect in the LNG sampling process and make the sample taken representative. The technical solution of the present invention can be used to manufacture a set of portable sampling modules, which can be moved and transported, and are convenient for working in multiple locations.

[0005] According to a first embodiment of the present invention, there is provided an LNG sampling and analysis system, which includes a cryogenic liquid delivery module, a vaporization module for vaporizing the LNG sample, a boosting module for pressurizing the LNG sample, and a sampling module for storing the LNG sample, which are sequentially arranged along the LNG sampling pipeline. A branch pipe is separated between the boosting module and the sampling module for connecting to an online analysis module, and the end of the sampling pipeline is connected to a vent main pipe.

[0006] Furthermore, the cryogenic liquid delivery module includes a sampling capillary inner tube connected to an LNG pipeline or a storage tank for transporting liquid LNG. The outer periphery of the sampling capillary inner tube is covered with a sampling outer sleeve. The space between the sampling capillary inner tube and the sampling outer sleeve is filled with liquid LNG. The end of the sampling capillary inner tube is connected to the capillary gasification tube in the gasification module via a one-way valve. The sampling outer sleeve branches out a venting pipe connected to the main venting pipe.

[0007] Preferably, the sampling outer sleeve is made of low-temperature resistant stainless steel and the outer surface of the sampling outer sleeve is coated with heat-insulating material.

[0008] The rear end of the sampling capillary inner tube is connected to the capillary vaporization tube in the vaporizer (for example, via a one-way valve). The sampling capillary inner tube is, for example, a 0.53mm ID stainless steel capillary tube, and its length is, for example, 0.5-1.5m, preferably 1m. A regulating valve is provided on the venting pipeline, and its function is that when gas is generated in the sampling pipeline, its temperature will be higher than the temperature of LNG. Opening the regulating valve will discharge the generated gas to prevent the vaporized LNG from entering the sampling capillary inner tube and affecting the sampling stability. Especially in the initial sampling stage, a large amount of gas will be generated.

[0009] Under normal sampling conditions, the sampling outer sleeve and the sampling capillary inner tube are both filled with LNG liquid. The LNG outside the sampling capillary inner tube plays a role in keeping the liquid inside the sampling capillary inner tube cold.

[0010] The sampling capillary inner tube is a sampling pipeline located in the cryogenic liquid delivery module. The front end of the sampling analysis system can be flexibly connected to the analysis port of the storage tank or pipeline by flange or ferrule.

[0011] Further, the gasification module includes a flash vaporizer connected to the cryogenic liquid delivery module via a sampling pipeline, the flash vaporizer includes a heating module with a corrugated groove inside, a power supply unit (for example, a ternary lithium battery module) connected to the heating module and providing electrical energy to the heating module, a capillary vaporization tube connected to the sampling capillary inner tube of the cryogenic liquid delivery module via a one-way valve and located in the heating module, a one-way valve arranged on the capillary vaporization pipeline and located between the cryogenic liquid delivery module and the heating module, the gasification module also includes a buffer tank connected to the outlet of the capillary vaporization tube, a pressure gauge arranged on the buffer tank, and a temperature controller connected between the flash vaporizer (power supply unit) and the buffer tank. Preferably, a corrugated groove is opened inside the heating module, and the capillary vaporization tube passes through the heating module and is arranged along the corrugated groove. An insulation layer is provided on the outside of the flash vaporizer.

[0012] The power supply unit adopts a ternary lithium battery as the power supply, and the heating module is made of a metal with fast thermal conductivity and large heat capacity, preferably aluminum, and its function is to provide sufficient heat for the gasification of LNG in the capillary gasification tube.

[0013] The capillary vaporization tube is, for example, a 0.53 ID stainless steel tube, the front end of which is connected to the capillary sampling inner tube through a one-way valve, and the length of the capillary vaporization tube is, for example, 50-200 cm, preferably 100 cm. Further, a stainless steel capillary tube with an outer diameter of 1 / 16" and an inner diameter of 0.04" can be used, and quartz wool can be filled inside to increase the vaporization area.

[0014] The volume of the buffer tank is, for example, 15-30 ml, preferably 20 ml. In addition, a thermometer is provided inside the buffer tank and connected to a temperature controller, so that the heating power of the heating module can be automatically adjusted according to the temperature change of the gas in the buffer tank.

[0015] The one-way valve is made of non-metallic material that is not easy to conduct heat, such as peek material, which can avoid heat transfer between the capillary vaporization tube and the sampling capillary inner tube.

[0016] The corrugated grooves inside the heating module are coated with thermally conductive silicone to facilitate heat transfer between the heating module and the capillary vaporization tube. The capillary vaporization tube is a sampling pipe located in the vaporization module.

[0017] Furthermore, the boosting module includes a micro boosting pump arranged on a sampling pipe, a throttle valve is provided on the sample input pipe of the micro boosting pump, a flow meter is provided on the sample output pipe of the micro boosting pump, a bypass pipe is separated from the sampling pipe between the throttle valve and the gasification module through a first three-way valve, and the end of the bypass pipe is connected to the sampling pipe between the flow meter and the micro boosting pump through a second three-way valve.

[0018] The purpose of setting up the booster module is to increase the pressure of the sampling cylinder in the subsequent sampling module, thereby increasing the sampling volume and providing sufficient capacity for offline analysis. For example, for a 100mL sampling cylinder, by pressurizing it to 1MPa, about 1000mL of gas can be provided for analysis.

[0019] The micro booster pump is used to boost the pressure of the gas LNG sample, and the outlet pressure can be set to, for example, 1 MPa. The throttle valve can set the flow rate to prevent excessive flow from causing fluctuations in the gasification module. The flow meter displays the gas flow rate. The first three-way valve and the second three-way valve are used to switch the gas line between the bypass and the booster line.

[0020] Furthermore, the sampling module includes a sampling steel cylinder for storing gasified LNG and connected to the sampling pipeline. The sampling pipeline of the gas input section and the sampling pipeline of the gas output section of the sampling steel cylinder are respectively connected with an inlet regulating valve and an outlet regulating valve. The sampling pipeline between the inlet regulating valve and the pressurizing module is separated into a bypass pipeline through a third three-way valve. The end of the bypass pipeline is connected to the sample delivery pipeline after the outlet regulating valve through a fourth three-way valve. The outlet regulating valve is provided with a bursting disc with a bursting pressure of 1mPa to prevent the sampling bottle from exploding due to excessive pressure. The bypass pipeline is used to switch the gas between the bypass and sampling flow paths.

[0021] The sampling cylinder is equipped with a pressure gauge to indicate the pressure inside the sampling cylinder to ensure safety.

[0022] The size of the sampling cylinder is determined according to the demand, usually 50-200ml, preferably 100ml, which can fully meet the requirements of chromatographic analysis after being pressurized to above 1MPa. A quick plug can be provided on the sampling pipeline between the third three-way valve and the inlet regulating valve of the sampling cylinder, another quick plug is provided on the sampling pipeline between the outlet regulating valve of the sampling cylinder and the fourth three-way valve, and the quick plug between the third three-way valve and the inlet regulating valve of the sampling cylinder can be used to connect the sampling bag.

[0023] Furthermore, a branch pipe is separated from the pipeline between the boosting module and the sampling module for connecting a portable analysis module. The portable analysis module includes a regulating valve on the branch pipe, a six-way valve connected to the regulating valve, a lithium battery power supply module, a carrier gas cylinder connected to the six-way valve, and a gas chromatograph for analyzing gas phase components. The outlet of the six-way valve is connected to the vent pipe.

[0024] The carrier gas used in the gas chromatograph is preferably helium, the chromatographic column is preferably PLOT Q 0.53mm×30m(L), the film thickness is 50μm, and the detector is preferably a thermal conductivity cell detector, which can achieve H 2 , N 2 , CH 4 , C 2 H 6 , C 3 H 8 Simultaneous determination of all components in LNG.

[0025] According to another embodiment of the present invention, there is provided a LNG sampling method using the above-mentioned LNG sampling and analysis system:

[0026] (1) First, open the flash vaporizer of the gasification module for preheating, set the flash vaporizer outlet temperature to 20-30°C (e.g., preferably 25°C), connect the sampling module inlet to the LNG pipeline or the storage tank sampling pipeline, open the regulating valve of the cryogenic liquid delivery module, turn the first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve to the bypass pipeline, and keep the throttle valve of the boosting module in a closed state;

[0027] (2) Open the sampling valve of the LNG pipeline or storage tank, and observe the temperature change of the thermometer of the cryogenic liquid delivery module. When the temperature drops to the temperature of LNG (generally -158 to -162°C), it indicates that the sampling capillary inner tube of the cryogenic liquid delivery module is full of LNG liquid. Close the regulating valve of the cryogenic liquid delivery module, turn on the flash vaporizer for heating, set the gas temperature in the buffer tank to 25°C, observe the flow rate of the flow meter of the booster module until the flow rate stabilizes, and record it;

[0028] (3) Turn the first three-way valve and the second three-way valve to the state where both ends of the micro-boosting pump are connected, turn on the micro-boosting pump, adjust the throttle valve, and observe the flow meter at the same time to make its flow rate close to the flow rate when the bypass is connected. The purpose is to maintain a stable flow rate and indirectly maintain a stable gasification state in the vaporizer;

[0029] (4) Connect the sampling cylinder, open the inlet valve and outlet valve of the sampling cylinder in sequence, turn the third three-way valve and the fourth three-way valve to the sampling flow path, and replace the sampling cylinder;

[0030] (5) According to the flow meter flow and time calculation, when the displacement volume exceeds 10-20 times the sampling capacity, close the outlet valve of the sampling cylinder, observe the value change of the pressure gauge on the sampling cylinder, and when it meets the analysis requirements or is close to the cylinder design operating pressure, close the outlet valve and inlet valve of the sampling cylinder in turn, and turn the fourth three-way valve and the third three-way valve to the bypass line. Remove the sampling cylinder and the sampling is completed.

[0031] According to another embodiment of the present invention, there is provided an LNG online analysis method using the above-mentioned LNG sampling and analysis system, the method comprising:

[0032] (1) First, open the flash vaporizer of the gasification module for preheating, set the flash vaporizer outlet temperature to 20-30° C. (e.g., preferably 25° C.), open the regulating valve of the cryogenic liquid delivery module, turn the first three-way valve, the second three-way valve, and the fourth three-way valve to the bypass pipeline, turn the third three-way valve to the sampling module disconnection state, and keep the regulating valve on the analysis branch pipe in the open state;

[0033] (2) Open the sampling valve of the LNG pipeline or storage tank, and observe the temperature change of the thermometer of the cryogenic liquid delivery module. When the temperature drops to the temperature of LNG (-158 to -162°C), it indicates that the sampling capillary inner tube of the cryogenic liquid delivery module is full of LNG liquid. Close the regulating valve of the cryogenic liquid delivery module, turn on the flash vaporizer for heating, set the gas temperature in the buffer tank to 25°C, and observe the flow rate of the booster module flowmeter until the flow rate is stable (all gas passes through at this time);

[0034] (3) After the flow rate stabilizes, the replacement volume is maintained at a value greater than 20 times the quantitative volume replacement analysis branch pipe six-way valve outlet gas to enter the vent pipeline, after the sample replacement is completed, the third three-way valve is turned to the sampling module bypass connection state, the regulating valve of the analysis branch pipe is closed, the six-way valve is rotated, and the sample is injected for analysis.

[0035] According to another embodiment of the present invention, there is provided a LNG sampling and analysis method using the above-mentioned LNG sampling and analysis system:

[0036] (1) First, open the flash vaporizer of the gasification module for preheating, set the flash vaporizer outlet temperature to 20-30°C (e.g., preferably 25°C), connect the sampling module inlet to the LNG pipeline or the storage tank sampling pipeline, open the regulating valve of the cryogenic liquid delivery module, turn the first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve to the bypass pipeline, keep the regulating valve of the analysis branch in a closed state, and keep the throttle valve of the boosting module in a closed state;

[0037] (2) Open the sampling valve of the LNG pipeline or storage tank, and observe the temperature change of the thermometer of the cryogenic liquid delivery module. When the temperature drops to the temperature of LNG (usually -158 to -162°C), it indicates that the sampling capillary inner tube of the cryogenic liquid delivery module is full of LNG liquid. Close the regulating valve of the cryogenic liquid delivery module, turn on the flash vaporizer for heating, set the gas temperature in the buffer tank to 30°C, observe the flow rate of the flow meter of the boosting module until the flow rate is stable, and record it;

[0038] (3) Turn the first three-way valve and the second three-way valve to the state where both ends of the micro-boosting pump are connected, turn on the micro-boosting pump, adjust the throttle valve, and observe the flow meter at the same time to make its flow close to the flow when the bypass is connected. The purpose is to maintain a stable flow and indirectly maintain a stable gasification state in the vaporizer; connect the sampling cylinder, open the inlet valve and outlet valve of the sampling cylinder in turn, turn the third three-way valve and the fourth three-way valve to the sampling flow path, and replace the sampling cylinder; calculate according to the flow meter flow and time, when the replacement amount exceeds 10-20 times the sampling capacity, close the outlet valve of the sampling cylinder, observe the changes in the pressure gauge value on the sampling cylinder, and when the value of the pressure gauge of the sampling cylinder meets the analysis requirements or is close to the designed operating pressure of the cylinder, close the outlet valve and inlet valve of the sampling cylinder in turn, and turn the fourth three-way valve and the third three-way valve to the bypass pipeline. Remove the sampling cylinder and the sampling is completed;

[0039] (4) While maintaining the replacement of the sampling cylinder, slowly open the regulating valve of the online analysis module. The flow meter indicates a flow rate of 20-30ML / min, which can meet the analysis replacement requirements without affecting the operation of the sampling module. After the replacement is completed, close the regulating valve of the online analysis module, rotate the six-way valve, and perform chromatographic analysis.

[0040] In this embodiment, online analysis and sampling are performed simultaneously to achieve the following beneficial effects:

[0041] The LNG sampling and analysis system of the present invention can effectively solve the gasification discrimination problem in the LNG sampling process, and can simultaneously perform sampling and online analysis operations. The device of the present invention can be removed from the LNG pipeline or storage tank at any time, moved at any time, and is easy to carry. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a schematic diagram of the overall structure of an LNG sampling and analysis system of the present invention.

[0043] Figure 2 This is an enlarged view of the cryogenic liquid delivery module.

[0044] Figure 3 This is an enlarged view of the gasification module.

[0045] Figure 4Schematic diagram of the corrugated groove structure in the heating module of the gasification module.

[0046] Figure 5 This is an enlarged view of the boost module.

[0047] Figure 6 This is an enlarged view of the sampling module.

[0048] Figure 7 This is an enlarged view of the online analysis module.

[0049] Description of Reference Numerals

[0050] 1-1 sampling outer sleeve; 1-2 sampling capillary inner tube; 1-3 venting pipeline; 1-4 regulating valve; 1-5 thermometer;

[0051] 2-0 flash vaporizer; 2-1 power supply unit; 2-2 heating module; 2-3 capillary vaporization tube; 2-4 buffer tank; 2-5 pressure gauge; 2-6 temperature controller; 2-7 check valve; 2-8 insulation layer;

[0052] 3-1 micro booster pump; 3-2 throttle valve; 3-3 bypass pipeline; 3-4 first three-way valve; 3-5 second three-way valve; 3-6 flow meter;

[0053] 4-1 Sampling cylinder; 4-2 Inlet regulating valve; 4-3 Outlet regulating valve; 4-4 Bypass pipe; 4-5 Third three-way valve; 4-6 Fourth three-way valve; 4-7 Pressure gauge; 4-8 Quick plug; 4-9 Sampling bag; 4-10 Quick plug;

[0054] 5-0 online analysis module (or unit); 5-1 regulating valve; 5-2 six-way valve (six-way sampling valve); 5-3 lithium battery power supply module; 5-4 gas chromatograph; 5-5 carrier gas cylinder; 5-6 vent pipe, 5-7 flow meter. DETAILED DESCRIPTION

[0055] The present invention is further described below in conjunction with the accompanying drawings.

[0056] like Figure 1-7 As shown, an LNG sampling and analysis system includes a cryogenic liquid delivery module, a gasification module for gasifying the LNG sample, a boosting module for pressurizing the LNG sample, and a sampling module for storing the LNG sample, which are sequentially arranged along the LNG sampling pipeline. A branch pipe is separated between the boosting module and the sampling module for connecting the online analysis module, and the end of the sampling pipeline is connected to the vent main pipe.

[0057] The cryogenic liquid delivery module includes a sampling capillary inner tube 1-2 connected to an LNG pipeline or a storage tank (not shown in the figure) for transporting liquid LNG. The outer periphery of the sampling capillary inner tube 1-2 is covered with a sampling outer sleeve 1-1. The space between the sampling outer sleeve 1-1 and the sampling capillary inner tube 1-2 is filled with liquid LNG. The end of the sampling capillary inner tube 1-2 is connected to the capillary gasification tube 2-3 in the gasification module via a one-way valve 2-7. The sampling outer sleeve 1-1 branches out a venting pipe 1-3 connected to the venting main pipe. The venting pipe is provided with a regulating valve 1-4 and a thermometer 1-5.

[0058] The sampling capillary inner tube 1-2 is, for example, a 0.53 mm ID stainless steel capillary. The function of the regulating valve 1-4 is that when gas is generated in the sampling pipeline, its temperature will be higher than the temperature of LNG, and the regulating valve is opened to discharge the generated gas to prevent the gasified LNG from entering the sampling capillary inner tube 1-2 and affecting the sampling stability, especially in the initial sampling stage where a large amount of gas will be generated.

[0059] Under normal sampling conditions, the sampling outer sleeve 1-1 and the sampling capillary inner tube 1-2 are both filled with LNG liquid. The LNG outside the sampling capillary inner tube plays a role in keeping the liquid inside the sampling capillary inner tube cold.

[0060] The sampling capillary inner tube 1-2 is a sampling pipeline located in the cryogenic liquid delivery module. The front end of the sampling analysis system can be flexibly connected to the analysis port of the storage tank or pipeline by flange or ferrule.

[0061] The gasification module includes a flash vaporizer 2-0 connected to the cryogenic liquid delivery module via a sampling pipeline, the flash vaporizer includes a heating module 2-2, a power supply unit 2-1 connected to the heating module 2-2 and providing electrical energy to the heating module, a capillary vaporization tube 2-3 connected to the sampling capillary inner tube 1-2 of the cryogenic liquid delivery module via a one-way valve 2-7 and located in the heating module 2-2, and a one-way valve 2-7 disposed on the capillary vaporization pipeline and located between the cryogenic liquid delivery module and the heating module, the gasification module also includes a buffer tank 2-4 connected to the outlet of the capillary vaporization tube 2-3, a pressure gauge 2-5 disposed on the buffer tank, and a temperature controller 2-6 connected between the flash vaporizer and the buffer tank 2-4. Preferably, a corrugated groove is provided inside the heating module, such as Figure 4 As shown, the capillary vaporization tube 2-3 passes through the heating module and is arranged along the corrugated groove. An insulation layer 2-8 is provided outside the flash vaporizer.

[0062] The power supply unit 2-1 can use a ternary lithium battery as a power supply, and the heating module 2-2 can be made of a metal with fast thermal conductivity and large heat capacity, preferably aluminum, which provides sufficient heat for the gasification of LNG in the capillary vaporization tube 2-3.

[0063] The capillary vaporization tube 2-3 is, for example, a 0.53mm ID stainless steel tube, and the front end is connected to the capillary sampling inner tube 1-2 through a one-way valve 2-7. The capillary vaporization tube 2-3 preferably uses a stainless steel capillary tube with an outer diameter of 1 / 16" and an inner diameter of 0.04", filled with quartz wool to increase the vaporization area, and the front end is connected to the capillary sampling inner tube through a one-way valve. The length of the capillary vaporization tube is generally 50-200cm, for example, preferably 100cm. The sampling outer sleeve 1-1 can be a 6mm-12mm pipeline, made of low-temperature resistant material.

[0064] The volume of the buffer tank 2-4 is 15-30 ml, preferably 20 ml. A thermometer is provided inside the buffer tank 2-4 and connected to the temperature controller 2-6, so that the heating power of the heating module 2-2 can be automatically adjusted according to the temperature change of the gas in the buffer tank 2-4.

[0065] The one-way valve 2-7 is made of non-metallic material that is not easy to conduct heat, such as peek or PTFE, so as to avoid heat transfer between the capillary vaporization tube and the sampling capillary inner tube.

[0066] The corrugated grooves inside the heating module are coated with thermally conductive silicone to facilitate heat transfer between the heating module and the capillary vaporization tube. The capillary vaporization tube is a sampling pipe located in the vaporization module.

[0067] The boosting module includes a micro boosting pump 3-1 arranged on a sampling pipeline led out from a buffer tank 2-4, a throttle valve 3-2 is provided on the sample input pipeline of the micro boosting pump 3-1, a flow meter 3-6 is provided on the sample output pipeline of the micro boosting pump, a bypass pipeline 3-3 is separated from the sampling pipeline between the throttle valve and the gasification module via a first three-way valve 3-4, and the end of the bypass pipeline 3-3 is connected to the sampling pipeline between the flow meter 3-6 and the micro boosting pump 3-1 via a second three-way valve 3-5.

[0068] The purpose of setting up the booster module is to increase the pressure of the sampling cylinder in the subsequent sampling module, thereby increasing the sampling volume and providing sufficient capacity for offline analysis. For example, for a 100mL sampling cylinder, by pressurizing it to 1mPa, about 1000ml of gas can be provided for analysis.

[0069] The micro booster pump 3-1 is used to boost the pressure of the gas LNG sample, and the outlet pressure can be set to, for example, 1 mPa. The throttle valve 3-2 can set the flow rate to prevent excessive flow from causing fluctuations in the gasification module. The flow meter 3-6 displays the gas flow rate. The first three-way valve 3-4 and the second three-way valve 3-5 are used to switch the gas line between the bypass 3-3 and the boosting pipeline.

[0070] The sampling module includes a sampling steel cylinder 4-1 for storing gasified LNG and connected to a sampling pipeline led out from a flow meter 3-6. An inlet regulating valve 4-2 and an outlet regulating valve 4-3 are respectively connected to the sampling pipeline of the gas input section and the sampling pipeline of the gas output section of the sampling steel cylinder. The sampling pipeline between the inlet regulating valve 4-2 and the pressurizing module is divided into a bypass pipeline 4-4 through a third three-way valve 4-5. The end of the bypass pipeline 4-4 is connected to the sample delivery pipeline after the outlet regulating valve through a fourth three-way valve 4-6. A bursting disc is provided on the outlet regulating valve 4-3. The bursting pressure is determined according to the design pressure of the steel cylinder, for example, 1mPa, to prevent the pressure from being too high and the sampling bottle from exploding. The third three-way valve 4-5 and the fourth three-way valve 4-6 are used to switch the gas between the bypass 4-4 and the sampling flow path.

[0071] The sampling cylinder is provided with a pressure gauge 4-7 to indicate the pressure inside the sampling cylinder to ensure safety.

[0072] The size of the sampling cylinder 4-1 is determined according to the demand, usually 50-200ml, preferably 100ml, and after being pressurized to 1Mpa (the filling pressure can be determined according to the sample volume required for analysis), it can fully meet the chromatographic analysis requirements. A quick plug 4-10 is provided on the sampling pipeline between the third three-way valve 4-5 and the inlet regulating valve 4-2 of the sampling cylinder, and another quick plug 4-8 is provided on the sampling pipeline between the outlet regulating valve of the sampling cylinder and the fourth three-way valve. The quick plug can be connected to the sampling bag 4-9 through a pipeline.

[0073] A branch pipe is separated from the sampling pipe between the boosting module and the sampling module for connecting a portable analysis module (or portable analysis unit) 5-0. The portable analysis module includes a regulating valve 5-1 on the analysis branch pipe, a six-way valve 5-2 connected to the regulating valve, a lithium battery power supply module 5-3, a carrier gas cylinder 5-5 connected to the six-way valve 5-2, and a gas chromatograph 5-4 for analyzing gas phase components. The outlet of the six-way valve 5-2 is connected to a vent pipe 5-6.

[0074] The carrier gas used in the gas chromatograph 5-5 is preferably helium, the chromatographic column is preferably PLOT Q 0.32mm×30m(L), the film thickness is 50μm, and the detector is preferably a thermal conductivity cell detector, which can achieve H 2 , N 2 , CH 4 , C 2 H 6 , C 3 H 8 Simultaneous determination of all components in LNG.

[0075] Example 1

[0076] A sampling method for an LNG sampling and analysis system:

[0077] use Figure 1 The analysis system shown, (1) first, open the flash vaporizer 2-0 of the gasification module for preheating, set the flash vaporizer outlet temperature to 25°C, connect the sampling module inlet end to the LNG storage tank sampling pipeline, open the regulating valve 1-4 of the cryogenic liquid delivery module, turn the first three-way valve 3-4, the second three-way valve 3-5, the third three-way valve 4-5, and the fourth three-way valve 4-6 to the bypass pipeline, keep the analysis branch pipe regulating valve in a closed state, and keep the throttle valve 3-2 of the boosting module in a closed state;

[0078] (2) Open the sampling valve of the LNG storage tank and observe the temperature change of the thermometer of the cryogenic liquid delivery module. When the temperature drops to the temperature of LNG (-158°C), close the regulating valve 1-4 of the cryogenic liquid delivery module, turn on the flash vaporizer 2-0 for heating, set the gas temperature in the buffer tank 2-4 to 25°C, observe the flow rate of the booster module flow meter 3-6 until the flow rate stabilizes, and record the flow rate value;

[0079] (3) Turn the first three-way valve 3-4 and the second three-way valve 3-5 to the state where both ends of the micro-boosting pump are connected, open the micro-boosting pump 3-1, adjust the throttle valve 3-2, and observe the flow meter 3-6 at the same time to make its flow rate close to the flow rate when the bypass is connected. The purpose is to maintain a stable flow rate and indirectly maintain a stable gasification state in the vaporizer;

[0080] (4) Connect the sampling cylinder 4-1, open the inlet valve 4-2 and outlet valve 4-3 of the sampling cylinder in sequence, turn the third three-way valve 4-5 and the fourth three-way valve 4-6 to the sampling flow path, and replace the sampling cylinder.

[0081] (5) According to the flow meter flow and time calculation, when the replacement volume exceeds 10 times the sampling capacity, close the sampling cylinder outlet valve 4-3 and observe the changes in the pressure gauge value on the sampling cylinder. When the pressure gauge value on the sampling cylinder is close to 1MPa (the pressure required for sampling), close the sampling cylinder outlet valve and inlet valve in turn, turn the fourth three-way valve and the third three-way valve to the bypass line, remove the sampling cylinder, and the sampling is completed.

[0082] Example 2

[0083] An online analysis method for an LNG sampling and analysis system, the method comprising:

[0084] (1) First, open the flash vaporizer 2-0 of the gasification module for preheating, set the flash vaporizer outlet temperature to 25°C, open the regulating valve 1-4 of the cryogenic liquid delivery module, turn the first three-way valve 3-4, the second three-way valve 3-5, and the fourth three-way valve 4-6 to the bypass state, turn the third three-way valve 4-5 to the sampling module disconnect state, and keep the analysis branch pipe regulating valve 5-1 in the open state.

[0085] (2) Open the sampling valve of the LNG storage tank and observe the temperature change of the thermometer of the cryogenic liquid delivery module. When the temperature drops to the temperature of LNG (-158°C), it indicates that the sampling capillary inner tube of the cryogenic liquid delivery module is full of LNG liquid. Close the regulating valve 1-4 of the cryogenic liquid delivery module, turn on the flash vaporizer 2-0 for heating, set the gas temperature in the buffer tank 2-4 to 25°C, and observe the flow rate of the booster module flow meter until the flow rate stabilizes.

[0086] (3) After the gasification flow rate is stable, keep the six-way valve displacement, the displacement volume is greater than 20 times the volume of the quantitative loop, turn the third three-way valve 4-5 and the fourth three-way valve 4-6 to the sampling module bypass state, and close the branch regulating valve 5-1. Rotate the six-way valve and inject the sample for analysis. The analysis results are completely consistent with the actual composition.

[0087] Example 3

[0088] An operation method for simultaneously performing online analysis and sampling of an LNG sampling and analysis system, the operation method is similar to that of Example 1.

[0089] The specific process is as follows:

[0090] (1) First, open the flash vaporizer 2-0 of the gasification module for preheating, set the flash vaporizer outlet temperature to 25°C, connect the sampling and analysis system inlet to the LNG storage tank sampling pipeline, open the regulating valve 1-4 of the cryogenic liquid delivery module, turn the first three-way valve 3-4, the second three-way valve 3-5, the third three-way valve 4-5, and the fourth three-way valve 4-6 to the bypass pipeline, keep the throttle valve 3-2 of the boosting module in a closed state, and keep the regulating valve 5-1 of the analysis branch pipe in a closed state;

[0091] (2) Open the sampling valve of the LNG storage tank and observe the temperature change of the thermometer of the cryogenic liquid delivery module. When the temperature drops to the temperature of LNG -158°C, close the regulating valve 1-4 of the cryogenic liquid delivery module, turn on the flash vaporizer 2-0 for heating, set the gas temperature in the buffer tank 2-4 to 25°C, observe the flow of the booster module flow meter 3-6 until the flow is stable, and record the flow value;

[0092] (3) Turn the first three-way valve 3-4 and the second three-way valve 3-5 to the state where both ends of the micro-boosting pump are connected, turn on the micro-boosting pump 3-1, adjust the throttle valve 3-2, and observe the flow meter 3-6 at the same time to make its flow close to the flow when the bypass is connected. The purpose is to maintain a stable flow and indirectly maintain a stable gasification state in the vaporizer; connect the sampling cylinder 4-1, open the sampling cylinder inlet valve 4-2 and outlet valve 4-3 in turn, and turn the third three-way valve 4-5 and the fourth three-way valve 4-6 to the sampling flow path to replace the sampling cylinder; according to the flow meter flow and time calculation, when the replacement amount exceeds 15 times the sampling capacity, close the sampling cylinder outlet valve 4-3, observe the changes in the pressure gauge value on the sampling cylinder, and when the sampling cylinder pressure gauge value is close to 1MPa (indicating that it can meet the analysis requirements), turn the sampling cylinder inlet valve in turn, turn the fourth three-way valve 4-6 and the third three-way valve 4-5 to the bypass pipeline to remove the sampling cylinder, and the sampling is completed;

[0093] (4) At the same time, during the replacement of the sampling module, slowly open the analysis branch regulating valve 5-1, observe the flow of the flow meter 5-7, and keep the replacement gas flow at 20-30ml / min. While meeting the replacement flow, it does not affect the sampling operation. The outlet gas enters the venting pipeline. After the sample replacement is completed, close the regulating valve 5-1 to disconnect the analysis branch from the sampling flow path, rotate the six-way valve 5-2, and use the gas chromatograph 5-4 for sample analysis. The analysis results are completely consistent with the actual composition.

[0094] According to the above embodiments, the gasification and disproportionation problem in the LNG sampling process can be effectively solved, and sampling and online analysis operations can be performed at the same time.

Claims

1. An LNG sampling and analysis system, characterized in that: The system includes a cryogenic liquid delivery module, a gasification module for gasifying LNG samples, a booster module for pressurizing LNG samples, and a sampling module for storing LNG samples, which are sequentially arranged along the LNG sampling pipeline. A branch pipe is separated between the booster module and the sampling module for connecting the online analysis module, and the end of the sampling pipeline is connected to the venting main pipe. The cryogenic liquid delivery module comprises a sampling capillary inner tube connected to an LNG pipeline or a storage tank for delivering liquid LNG, a sampling outer sleeve is sheathed on the periphery of the sampling capillary inner tube, a space between the sampling outer sleeve and the sampling capillary inner tube is filled with liquid LNG, an end of the sampling capillary inner tube is connected to a capillary gasification tube in a gasification module via a one-way valve, a venting pipeline is separated from the sampling outer sleeve and connected to a venting main pipeline, a regulating valve is provided on the venting pipeline, and the sampling capillary inner tube is a sampling pipeline located in the cryogenic liquid delivery module; The gasification module includes a flash vaporizer connected to the cryogenic liquid delivery module via a sampling pipeline, the flash vaporizer includes a heating module with a corrugated groove inside, a power supply unit connected to the heating module and providing electrical energy to the heating module, a capillary vaporization tube connected to the sampling capillary inner tube of the cryogenic liquid delivery module via a one-way valve and located in the heating module, a one-way valve arranged on the capillary vaporization pipeline and located between the cryogenic liquid delivery module and the heating module, the gasification module also includes a buffer tank connected to the outlet of the capillary vaporization tube, a pressure gauge arranged on the buffer tank, and a temperature controller connected between the flash vaporizer and the buffer tank; The boosting module includes a micro boosting pump arranged on a sampling pipeline, a throttle valve is arranged on a sample input pipeline of the micro boosting pump, a flow meter is arranged on a sample output pipeline of the micro boosting pump, a bypass pipeline is separated from the sampling pipeline between the throttle valve and the gasification module via a first three-way valve, and an end of the bypass pipeline is connected to the sampling pipeline between the flow meter and the micro boosting pump via a second three-way valve; The sampling module includes a sampling cylinder for storing gasified LNG and connected to a sampling pipeline. An inlet regulating valve and an outlet regulating valve are respectively connected to the sampling pipeline of the gas input section and the sampling pipeline of the gas output section of the sampling cylinder. A bypass pipeline is separated from the sampling pipeline between the inlet regulating valve and the pressurizing module via a third three-way valve. The end of the bypass pipeline is connected to the sample delivery pipeline after the outlet regulating valve via a fourth three-way valve. A bursting disc is provided on the outlet regulating valve. A quick plug is provided on the sampling pipeline between the third three-way valve and the inlet regulating valve of the sampling cylinder. Another quick plug is provided on the sampling pipeline between the outlet regulating valve of the sampling cylinder and the fourth three-way valve. The quick plug between the third three-way valve and the inlet regulating valve of the sampling cylinder can be connected to a sampling bag for sampling.

2. The LNG sampling and analysis system according to claim 1, characterized in that: A corrugated groove is opened inside the heating module, a capillary vaporization tube passes through the heating module and is arranged along the corrugated groove, and heat-conductive silica gel is coated between the capillary vaporization tube and the corrugated groove.

3. The LNG sampling and analysis system according to claim 1 or 2, characterized in that: A branch pipe is separated from the sampling pipe between the booster module and the sampling module for connecting a portable analysis module. The portable analysis module includes a regulating valve arranged on the branch pipe, a six-way valve connected to the branch pipe, a lithium battery power supply module, a carrier gas cylinder connected to the six-way valve, and a gas chromatograph for analyzing gas phase components. The outlet of the six-way valve is connected to the vent pipe.

4. An LNG sampling method using the LNG sampling and analysis system according to any one of claims 1 to 3, characterized in that: The method includes: (1) First, preheat the flash vaporizer, connect the inlet of the sampling and analysis system to the LNG pipeline or the tank sampling pipeline, open the regulating valve of the cryogenic liquid delivery module, turn the first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve to the bypass pipeline, and keep the throttle valve of the booster module in the closed state. (2) Open the sampling valve of the LNG pipeline or storage tank. When the temperature of the thermometer of the cryogenic liquid delivery module drops to the temperature of LNG, close the sampling outer casing branch regulating valve and open the flash vaporizer until the flow rate stabilizes. (3) Turn the first three-way valve and the second three-way valve to the state where both ends of the micro-boosting pump are connected, turn on the micro-boosting pump, and adjust the throttle valve so that its flow rate is close to the flow rate when the bypass is connected. (4) Connect the sampling cylinder, open the inlet valve and outlet valve of the sampling cylinder in turn, turn the third and fourth three-way valves to the sampling flow path, and replace the sampling cylinder. (5) When the replacement volume exceeds 10-20 times the sampling capacity, close the outlet valve of the sampling cylinder. When the sampling is completed, close the outlet valve and inlet valve of the sampling cylinder in turn, turn the fourth three-way valve and the third three-way valve to the bypass line, remove the sampling cylinder, and the sampling is completed.

5. An LNG online analysis method using the LNG sampling and analysis system according to any one of claims 1 to 3, characterized in that: The method includes: (1) First, preheat the flash vaporizer, open the regulating valve of the cryogenic liquid delivery module, turn the first three-way valve, the second three-way valve, and the fourth three-way valve to the bypass pipeline, turn the third three-way valve to the sampling module disconnect state, and keep the regulating valve of the analysis module in the open state. (2) Open the sampling valve of the LNG pipeline or storage tank. When the temperature drops to the temperature of LNG, close the sampling sleeve branch regulating valve and open the flash vaporizer until the flow is stable. All gases enter the six-way valve through the analysis branch regulating valve for sample replacement. (3) After the flow rate stabilizes, keep the sample replacement volume greater than 20 times the volume of the quantitative loop. The gas at the outlet of the six-way valve enters the vent pipeline. After the sample replacement is completed, turn the third three-way valve to the sampling module bypass connection state, close the branch pipe regulating valve, rotate the six-way valve, and inject the sample for analysis.

6. An LNG online sampling and analysis method using the LNG sampling and analysis system according to any one of claims 1 to 3, characterized in that: The method includes: (1) First, open the flash vaporizer of the gasification module, preheat it, set the flash vaporizer outlet temperature to 20-30°C, connect the inlet of the sampling and analysis system to the LNG pipeline or the tank sampling pipeline, open the regulating valve of the cryogenic liquid delivery module, turn the first three-way valve, the second three-way valve, the third three-way valve, and the fourth three-way valve to the bypass pipeline, keep the branch pipe regulating valve of the analysis module closed, and keep the throttle valve of the booster module closed; (2) Open the sampling valve of the LNG pipeline or storage tank, and observe the temperature change of the thermometer of the cryogenic liquid delivery module. When the temperature drops to the LNG temperature of -158℃~-162℃, it indicates that the sampling capillary inner tube of the cryogenic liquid delivery module is full of LNG liquid. Close the regulating valve of the cryogenic liquid delivery module, turn on the flash vaporizer heating, set the gas temperature in the buffer tank to 25℃, observe the flow rate of the booster module flow meter until the flow rate stabilizes, and record it; (3) Turn the first three-way valve and the second three-way valve to the state where both ends of the micro-boosting pump are connected, turn on the micro-boosting pump, adjust the throttle valve, and observe the flow meter at the same time to make its flow close to the flow when the bypass is connected. The purpose is to maintain a stable flow and indirectly maintain a stable gasification state in the vaporizer. Connect the sampling cylinder, open the inlet valve and outlet valve of the sampling cylinder in turn, turn the third three-way valve and the fourth three-way valve to the sampling flow path, replace the sampling cylinder, and calculate according to the flow meter flow and time. When the replacement amount exceeds 10-20 times the sampling capacity, close the outlet valve of the sampling cylinder and observe the changes in the pressure gauge value on the sampling cylinder. When the pressure gauge value of the sampling cylinder meets the analysis requirements or is close to the designed operating pressure of the cylinder, close the outlet valve and inlet valve of the sampling cylinder in turn, turn the fourth three-way valve and the third three-way valve to the bypass pipeline, remove the sampling cylinder, and the sampling is completed; (4) While taking samples, slowly open the regulating valve of the analysis branch pipe, keep the flow rate of the analysis module flow meter at 20-30ml / min, and allow part of the gas to enter the six-way valve through the sampling branch pipe for sample replacement. The gas at the outlet of the six-way valve enters the venting pipeline. After the sample replacement is completed, close the regulating valve of the branch pipe, rotate the six-way valve, and inject the sample for analysis.

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