阅读说明：本技术 一种lng取样分析系统及方法 (LNG sampling analysis system and method ) 是由 司瑞刚 史立杰 刘雪飞 张永泽 李晨佳 常俊石 王鑫 陈�胜 李彦辉 王学坤 于 2020-07-15 设计创作，主要内容包括：本发明提供一种LNG取样分析系统及方法,系统包括沿着LNG取样管道依次设置的低温液体输送模块、气化模块、增压模块、取样模块,增压模块与取样模块之间连接在线分析模块。低温液体输送模块获得低温液体,经气化模块气化、增压模块加压后储存在取样模块的取样钢瓶中。本发明能够有效解决LNG取样过程中的气化歧视问题,同时能够同时进行取样和在线分析操作。(The invention provides an LNG sampling and analyzing system and a method. The low-temperature liquid conveying module obtains low-temperature liquid, and the low-temperature liquid is gasified by the gasification module and pressurized by the pressurization module and then is stored in a sampling steel cylinder of the sampling module. The invention can effectively solve the problem of gasification discrimination in the LNG sampling process, and can simultaneously carry out sampling and on-line analysis operation.)

1. The utility model provides a LNG sampling analysis system, its characterized in that, this system include along the cryogenic liquids transport module that LNG sample line set gradually, be used for with the gasification module of LNG sample gasification, for the pressurized boost module of LNG sample, be used for storing the sample module of LNG sample, divide a branch pipe between boost module and the sample module and be used for connecting online analysis module, the end and the common drain of sample line are connected.

2. The LNG sampling and analyzing system of claim 1, wherein the cryogenic liquid transportation module comprises a sampling capillary inner tube connected to the LNG pipeline or the storage tank for transporting liquid LNG, a sampling outer sleeve is sleeved on an outer periphery of the sampling capillary inner tube, liquid LNG is filled in a space between the sampling outer sleeve and the sampling capillary inner tube, a terminal of the sampling capillary inner tube is connected to a capillary gasification tube in the gasification module through a one-way valve, the sampling outer sleeve is divided into a vent pipeline connected to a vent main pipeline, a regulating valve is arranged on the vent pipeline, and the sampling capillary inner tube is a sampling pipeline located in the cryogenic liquid transportation module.

3. The LNG sampling analysis system of claim 1 or 2, wherein the gasification module comprises a flash evaporation gasifier connected with the low-temperature liquid delivery module through a sampling pipeline, the flash evaporation gasifier comprises a heating module with a corrugated groove formed inside, a power supply unit connected with the heating module and providing electric energy for the heating module, a capillary gasification pipe connected with a sampling capillary inner pipe of the low-temperature liquid delivery module through a one-way valve and located in the heating module, a one-way valve arranged on the capillary evaporation pipeline and located between the low-temperature liquid delivery module and the heating module, the gasification module further comprises a buffer tank connected with an outlet of the capillary gasification pipe, a pressure gauge arranged on the buffer tank, and a temperature controller connected between the flash evaporation gasifier and the buffer tank.

4. The LNG sampling and analyzing system of claim 3, wherein the heating module is internally provided with corrugated grooves, the capillary gasification tubes penetrate through the heating module and are arranged along the corrugated grooves, and heat-conducting silica gel is coated between the capillary gasification tubes and the corrugated grooves.

5. An LNG sampling and analysis system according to any one of claims 1-4, characterized in that the booster module comprises a micro booster pump arranged on the sampling pipe, a throttle valve is arranged on a sample input pipe of the micro booster pump, a flow meter is arranged on a sample output pipe of the micro booster pump, the sampling pipe between the throttle valve and the gasification module branches off a bypass pipe 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 booster pump through a second three-way valve.

6. LNG sampling analysis system according to any of claims 1-5, sampling module is including being used for storing gasification LNG and the sample steel bottle of being connected with sample pipeline, the gas input section sample pipeline of sample steel bottle is gone up and is connect import governing valve and export governing valve on the gas output section sample pipeline respectively, sample pipeline between import governing valve and the pressurization module has been through bypass pipeline of third three-way valve branch, bypass pipeline's end is on the sample pipeline after the export governing valve through fourth three-way valve connection, be equipped with the rupture disk on the export governing valve, be equipped with a swift plug on the sample pipeline between the import governing valve of third three-way valve and sample steel bottle, be equipped with another swift plug on the sample pipeline between the export governing valve of sample steel bottle and the fourth three-way valve, the sample bag sample can be connected to swift plug between the import governing valve of third three-way valve and sample steel bottle.

7. LNG sampling analysis system according to any of claims 1-6, characterized in that a branch pipe is branched from the sampling pipe between the pressurizing module and the sampling module for connecting the portable analysis module, the portable analysis module comprises a regulating valve arranged on the branch pipe, a six-way valve connected with the branch pipe, a lithium battery power supply module, a carrier gas cylinder connected with the six-way valve, a gas chromatograph for analyzing gas phase components, and the outlet of the six-way valve is connected with the emptying pipe.

8. An LNG sampling method using the LNG sampling analysis system according to any one of claims 1 to 7, the method comprising:

(1) firstly, preheating a flash vaporizer, connecting an inlet end of a sampling analysis system with an LNG pipeline or a storage tank sampling pipeline, opening a regulating valve of a low-temperature liquid conveying module, rotating a first three-way valve, a second three-way valve, a third three-way valve and a fourth three-way valve to a bypass pipeline, keeping a throttle valve of a pressurizing module in a closed state,

(2) opening a sampling valve of the LNG pipeline or the storage tank, closing a sampling outer sleeve pipe branch pipe regulating valve when the temperature of a thermometer of the low-temperature liquid conveying module is reduced to the temperature of the LNG, starting the flash evaporation gasifier until the flow is stable,

(3) rotating the first three-way valve and the second three-way valve to the state of communicating two ends of the micro booster pump, opening the micro booster pump, adjusting the throttle valve to enable the flow rate to be close to the flow rate in the bypass communicating state,

(4) connecting the sampling steel cylinders, opening the inlet valve and the outlet valve of the sampling steel cylinders in sequence, rotating the third three-way valve and the fourth three-way valve to a sampling flow path, replacing the sampling steel cylinders,

(5) and when the displacement exceeds 10-20 times of the sampling capacity, closing the outlet valve of the sampling steel cylinder, when the sampling is finished, closing the outlet valve and the inlet valve of the sampling steel cylinder in sequence, rotating the fourth three-way valve and the third three-way valve to the bypass pipeline, taking down the sampling steel cylinder, and finishing the sampling.

9. An on-line analysis method for LNG using the LNG sampling analysis system of any one of claims 1 to 7, comprising:

(1) firstly, preheating the flash vaporizer, opening the regulating valve of the low-temperature liquid conveying module, rotating the first three-way valve, the second three-way valve and the fourth three-way valve to the bypass pipeline, rotating the third three-way valve to the disconnection state of the sampling module, keeping the regulating valve of the analysis module in the opening state,

(2) and opening a sampling valve of the LNG pipeline or the storage tank, closing the sampling sleeve branch pipe regulating valve when the temperature is reduced to the temperature of the LNG, starting the flash evaporation gasifier until the flow is stable, and enabling all gas to enter the six-way valve through the analysis branch pipe regulating valve to perform sample replacement.

(3) After the flow is stable, the volume of a quantitative ring with the sample displacement volume being more than 20 times is kept, the gas at the outlet of the six-way valve enters an emptying pipeline, after the sample displacement is finished, the third three-way valve is rotated to the bypass communication state of the sampling module, the branch pipe regulating valve is closed, the six-way valve is rotated, and the sample introduction analysis is carried out.

10. An LNG on-line sampling and analysis method using the LNG sampling analysis system of any one of claims 1 to 7, characterized in that the method comprises:

(1) firstly, opening a flash evaporation gasifier of a gasification module, preheating, setting the outlet temperature of the flash evaporation gasifier to be 20-30 ℃ (preferably 25 ℃), connecting the inlet end of a sampling analysis system with an LNG pipeline or a storage tank sampling pipeline, opening a regulating valve of a low-temperature liquid conveying module, screwing a first three-way valve, a second three-way valve, a third three-way valve and a fourth three-way valve to a bypass pipeline, keeping a closed state of a branch pipe regulating valve of the analysis module, and keeping a throttle valve of a pressurization module in a closed state;

(2) open the sampling valve of the LNG pipeline or storage tank, observe the temperature change of the thermometer of the cryogenic liquid transfer module, when the temperature drops to LNG (about) When the temperature is higher than the preset temperature, the sampling capillary inner tube of the low-temperature liquid conveying module is filled with LNG liquid, a regulating valve of the low-temperature liquid conveying module is closed, a flash vaporizer is opened for heating, the temperature of gas in a buffer tank is set to be 25 ℃, the flow of a flow meter of a pressurizing module is observed until the flow is stable, and the flow is recorded;

(3) rotating the first three-way valve and the second three-way valve to a communication state of two ends of the micro booster pump, opening the micro booster pump, adjusting a throttle valve, and observing a flow meter to enable the flow rate of the flow meter to be close to the flow rate in a bypass communication state, so as to keep the flow rate stable and indirectly keep a gasification state in the vaporizer stable; connecting a sampling steel cylinder, sequentially opening an inlet valve and an outlet valve of the sampling steel cylinder, and rotating a third three-way valve and a fourth three-way valve to a sampling flow path to replace the sampling steel cylinder; according to the flow of the flowmeter and the time calculation, when the displacement exceeds 10-20 times of the sampling capacity, the outlet valve of the sampling steel cylinder is closed, the numerical value change of a pressure gauge on the sampling steel cylinder is observed, when the numerical value of the pressure gauge of the sampling steel cylinder meets the analysis requirement or is close to the design operating pressure of the steel cylinder, the outlet valve and the inlet valve of the sampling steel cylinder are closed in sequence, and the fourth three-way valve and the third three-way valve are screwed to the bypass pipeline. Taking down the sampling steel cylinder, and finishing sampling;

(4) and (3) slowly opening an analysis branch pipe regulating valve while sampling, keeping the flow of a flowmeter of the analysis module at 20-30ml/min, enabling part of gas to enter a six-way valve through a sampling branch pipe for sample replacement, enabling gas at the outlet of the six-way valve to enter an emptying pipeline, closing the branch pipe regulating valve after the sample replacement is finished, rotating the six-way valve, and performing sample injection analysis.

Technical Field

The invention belongs to the field of natural gas, and particularly relates to an LNG sampling analysis system and method.

Background

At present, the consumption of natural gas is greatly increased under the guidance of national energy policies. For the place that does not lay the gas transmission pipeline, relative gaseous methane, the storage of LNG, transportation are more convenient. According to related organizations, 9000 ten thousand tons and 5300 ten thousand tons of imported natural gas are calculated as LNG in 2018, and meanwhile, LNG detection requirements exist in numerous domestic natural gas liquefaction enterprises and coal-based natural gas enterprises taking coal as a source.

Besides methane, LNG also contains a small amount of nitrogen, hydrogen and low-carbon hydrocarbons such as ethane and ethylene according to different sources, and during the LNG gasification sampling process, components with different boiling points are gasified and disproportionated, so that the obtained sample is not representative. In short, the gasification ratios of different boiling point components are different, the gasification ratio of the low boiling point component is high, and the gasification ratio of the high boiling point component is low, so that the difference exists between the composition of the obtained gas sample and the actual composition of the LNG, and the final detection result is influenced.

Disclosure of Invention

The invention provides an LNG sampling and analyzing system and method. The portable sampling module is used for solving the gasification discrimination effect in the LNG sampling process, so that the taken sample is representative.

According to a first embodiment of the present invention, an LNG sampling and analyzing system is provided, which comprises a cryogenic liquid delivery module, a gasification module for gasifying an LNG sample, a pressurization module for pressurizing the LNG sample, and a sampling module for storing the LNG sample, which are sequentially disposed along an LNG sampling pipe, wherein a branch pipe is divided between the pressurization module and the sampling module for connecting an online analysis module, and the tail end of the sampling pipe is connected with a discharge main.

Furthermore, the low-temperature liquid conveying module comprises a sampling capillary inner tube which is connected with an LNG pipeline or a storage tank and used for conveying liquid LNG, a sampling outer sleeve is sleeved on the periphery of the sampling capillary inner tube, liquid LNG is filled in a space between the sampling capillary inner tube and the sampling outer sleeve, the tail end of the sampling capillary inner tube is connected with a capillary gasification tube in the gasification module through a one-way valve, and the sampling outer sleeve is divided into an emptying pipeline and is connected with an emptying main pipeline.

Preferably, the sampling outer sleeve is made of low-temperature-resistant stainless steel. The exterior of the sampling outer sleeve is coated with a heat-insulating material.

The back end of the sampling capillary inner tube is connected with the capillary gasification tube in the gasifier (for example, through a one-way valve). The sampling capillary tube is, for example, a 0.53mm stainless steel capillary tube having a length of, for example, 0.5 to 1.5m, preferably 1 m. Be equipped with the governing valve on the atmospheric line, its effect lies in when having gaseous production in the sample pipeline, and its temperature can be higher than LNG's temperature, opens the governing valve, and the gaseous discharge that will produce prevents that gasified LNG from getting into sample capillary inner tube, influences sample stability. Especially in the initial sampling phase, a relatively large amount of gas is generated.

The sampling outer sleeve and the sampling capillary inner tube are filled with LNG liquid in a normal sampling state. The LNG outside the sampling capillary inner tube plays a role in keeping the liquid in the sampling capillary inner tube cold.

The sampling capillary inner pipe is a sampling pipeline positioned in the low-temperature liquid conveying module. The front end of the sampling analysis system can be flexibly connected with an analysis port of a storage tank or a pipeline in a flange or ferrule mode.

Further, the gasification module includes the flash evaporation vaporizer of being connected through sampling pipeline and low temperature liquid transport module, and the flash evaporation vaporizer includes that inside opens the heating module that has the ripple type recess, is connected and provides the power supply unit (for example for ternary lithium cell module) of electric energy to the heating module with the heating module, through the capillary gasification pipe that the sampling capillary inner tube of check valve and low temperature liquid transport module is connected and is located the heating module, set up on capillary gasification pipeline and be located the check valve between low temperature liquid transport module and the heating module, the gasification module still includes the buffer tank with the exit linkage of capillary gasification pipe, set up the manometer on the buffer tank, connect the temperature controller between flash evaporation vaporizer (the power supply unit) and the buffer tank. Preferably, the heating module is internally provided with a corrugated groove, and the capillary gasification tube penetrates through the heating module and is arranged along the corrugated groove. And a heat-insulating layer is arranged outside the flash evaporation gasifier.

The power supply unit adopts the ternary lithium cell as power supply, and heating module adopts the metal preparation that heat conduction speed is fast, thermal capacity is big to form, preferred aluminum product, and its effect provides sufficient heat for the gasification of LNG in the capillary vaporizer.

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

The volume of the buffer tank is, for example, 15 to 30ml, preferably 20 ml. In addition, a thermometer is arranged inside the buffer tank and connected with 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.

The non-metallic material that is difficult for the heat conduction is adopted to the check valve, selects the peek material for example, can avoid the heat transfer between capillary gasification pipe and the capillary inner tube of taking a sample.

Heat conduction silica gel is coated in the corrugated groove in the heating module, so that heat transfer is facilitated between the heating module and the capillary gasification tube. The capillary gasification pipe is a sampling pipeline positioned in the gasification module.

Furthermore, the pressurizing module comprises a micro-booster pump arranged on the sampling pipeline, a throttle valve is arranged on a sample input pipeline of the micro-booster pump, a flow meter is arranged on a sample output pipeline of the micro-booster pump, a bypass pipeline is branched out from the sampling pipeline between the throttle valve and the gasification module through a first three-way valve, and the tail end of the bypass pipeline is connected to the sampling pipeline between the flow meter and the micro-booster pump through a second three-way valve.

The purpose of the pressurizing module is as follows: increasing the pressure and thus the sampling volume for the sampling cylinders in the subsequent sampling modules provides sufficient capacity for off-line analysis, for example, about 1000mL of gas can be provided for analysis by pressurizing to 1MPa for a 100mL sampling cylinder.

Where a micro booster pump is used to boost the pressure of the gaseous LNG sample, the outlet pressure may be set, for example, to 1 MPa. The throttle valve can set the flow through, prevents that the too big gasification module of arousing of flow from fluctuating. The flow meter displays the gas flow. The first three-way valve and the second three-way valve are used for switching the gas path between the bypass and the pressurization pipeline.

Further, sampling module is including the sample steel bottle that is used for storing gasification LNG and is connected with the sample tube, it has imported governing valve and export governing valve to connect respectively on the gas input section sample tube of sample steel bottle and on the gas output section sample tube, the sample tube between import governing valve and the pressurization module is through bypass pipeline of third three-way valve separation, the end of bypass pipeline is on the sample pipeline after the export governing valve through fourth three-way valve connection, be equipped with the rupture disk on the export governing valve, the burst pressure is 1mPa, prevent that pressure is too high, the sample bottle explosion. The bypass conduit is used to switch gas between the bypass and the sampling flow path.

The sampling steel cylinder is provided with a pressure gauge for indicating the pressure in the sampling steel cylinder and ensuring safety.

The sampling steel cylinder is determined according to the requirement, generally 50-200ml, preferably 100ml, and can fully meet the chromatographic analysis requirement after being pressurized to more than 1 MPa. The sampling pipeline between the inlet regulating valve of the third three-way valve and the sampling steel bottle can be provided with a quick plug, the sampling pipeline between the outlet regulating valve of the sampling steel bottle and the fourth three-way valve is provided with another quick plug, and the quick plug between the inlet regulating valve of the third three-way valve and the sampling steel bottle can be used for connecting a sampling bag.

Furthermore, a branch pipe is branched from a pipeline between the pressurization module and the sampling module and used for being connected with a portable analysis module, the portable analysis module comprises a regulating valve on the branch pipe, a six-way valve connected with the regulating valve, a lithium battery power supply module, a carrier gas steel cylinder connected with the six-way valve and a gas chromatograph used for analyzing gas phase components, and an outlet of the six-way valve is connected with a vent pipeline.

Wherein, the carrier gas used for the gas chromatograph is preferably helium, the chromatographic column is preferably PLOT Q0.53 mm multiplied by 30m (L), the film thickness is 50 μm, the detector is preferably a thermal conductivity cell detector, and H can be realized₂，N₂，CH₄，C₂H₆，C₃H₈And waiting for the simultaneous determination of the total components in the LNG.

According to another embodiment of the present invention, there is provided an LNG sampling method using the above LNG sampling analysis system:

(1) firstly, opening a flash evaporation gasifier of a gasification module, preheating, setting the outlet temperature of the flash evaporation gasifier to be 20-30 ℃ (preferably 25 ℃), connecting the inlet end of a sampling module with an LNG pipeline or a storage tank sampling pipeline, opening a regulating valve of a low-temperature liquid conveying module, rotating a first three-way valve, a second three-way valve, a third three-way valve and a fourth three-way valve to a bypass pipeline, and keeping a throttle valve of a pressurization module in a closed state;

(2) opening a sampling valve of an LNG pipeline or a storage tank, observing the temperature change of a thermometer of a low-temperature liquid conveying module, when the temperature is reduced to the temperature of LNG (generally-158 to-162 ℃), indicating that a sampling capillary inner tube of the low-temperature liquid conveying module is filled with LNG liquid, closing an adjusting valve of the low-temperature liquid conveying module, starting a flash vaporizer for heating, setting the gas temperature in a buffer tank to be 25 ℃ for example, observing the flow of a flow meter of a pressurizing module until the flow is stable, and recording;

(3) rotating the first three-way valve and the second three-way valve to a communication state of two ends of the micro booster pump, opening the micro booster pump, adjusting a throttle valve, and observing a flow meter to enable the flow rate of the flow meter to be close to the flow rate in a bypass communication state, so as to keep the flow rate stable and indirectly keep a gasification state in the vaporizer stable;

(4) connecting a sampling steel cylinder, sequentially opening an inlet valve and an outlet valve of the sampling steel cylinder, and rotating a third three-way valve and a fourth three-way valve to a sampling flow path to replace the sampling steel cylinder;

(5) according to the flow of the flowmeter and the time calculation, when the displacement exceeds 10-20 times of the sampling capacity, the outlet valve of the sampling steel cylinder is closed, the numerical value change of a pressure gauge on the sampling steel cylinder is observed, when the analysis requirement is met or the design operation pressure of the steel cylinder is approached, the outlet valve and the inlet valve of the sampling steel cylinder are sequentially closed, and the fourth three-way valve and the third three-way valve are screwed to the bypass pipeline. And taking off the sampling steel cylinder, and finishing sampling.

According to another embodiment of the present invention, there is provided an LNG online analysis method using the above LNG sampling analysis system, the method including:

(1) firstly, opening a flash evaporation gasifier of a gasification module, preheating, setting the outlet temperature of the flash evaporation gasifier to be 20-30 ℃ (preferably 25 ℃), opening a regulating valve of a low-temperature liquid conveying module, rotating a first three-way valve, a second three-way valve and a fourth three-way valve to a bypass pipeline, rotating a third three-way valve to a disconnection state of a sampling module, and keeping the regulating valve on an analysis branch pipe in an opening state;

(2) opening a sampling valve of an LNG pipeline or a storage tank, observing the temperature change of a thermometer of a low-temperature liquid conveying module, when the temperature is reduced to the temperature of LNG (-158 to-162 ℃), indicating that the sampling capillary inner tube of the low-temperature liquid conveying module is filled with LNG liquid, closing an adjusting valve of the low-temperature liquid conveying module, starting a flash vaporizer to heat, setting the temperature of gas in the buffer tank to be 25 ℃ for example, and observing the flow of a flow meter of a pressurizing module until the flow is stable (all the gas passes at this time);

(3) and after the flow is stable, keeping the gas at the outlet of the six-way valve of the quantitative volume change analysis branch pipe with the replacement volume more than 20 times to enter an emptying pipeline, rotating the third three-way valve to a bypass communication state of the sampling module after the sample replacement is finished, closing an adjusting valve of the analysis branch pipe, rotating the six-way valve, and performing sample injection analysis.

According to yet another embodiment of the present invention, there is provided an LNG sampling and analyzing method using the above LNG sampling and analyzing system:

(1) firstly, opening a flash evaporation gasifier of a gasification module, preheating, setting the outlet temperature of the flash evaporation gasifier to be 20-30 ℃ (preferably 25 ℃), connecting the inlet end of a sampling module with an LNG pipeline or a storage tank sampling pipeline, opening a regulating valve of a low-temperature liquid conveying module, rotating a first three-way valve, a second three-way valve, a third three-way valve and a fourth three-way valve to a bypass pipeline, keeping the regulating valve of an analysis branch pipe in a closed state, and keeping a throttle valve of a pressurization module in a closed state;

(2) opening a sampling valve of an LNG pipeline or a storage tank, observing the temperature change of a thermometer of a low-temperature liquid conveying module, when the temperature is reduced to the temperature of LNG (usually-158 to-162 ℃), indicating that a sampling capillary inner tube of the low-temperature liquid conveying module is filled with LNG liquid, closing an adjusting valve of the low-temperature liquid conveying module, starting a flash vaporizer for heating, setting the gas temperature in a buffer tank to be 30 ℃ for example, observing the flow of a flow meter of a pressurizing module until the flow is stable, and recording;

(3) rotating the first three-way valve and the second three-way valve to a communication state of two ends of the micro booster pump, opening the micro booster pump, adjusting a throttle valve, and observing a flow meter to enable the flow rate of the flow meter to be close to the flow rate in a bypass communication state, so as to keep the flow rate stable and indirectly keep a gasification state in the vaporizer stable; connecting a sampling steel cylinder, sequentially opening an inlet valve and an outlet valve of the sampling steel cylinder, and rotating a third three-way valve and a fourth three-way valve to a sampling flow path to replace the sampling steel cylinder; according to the flow of the flowmeter and the time calculation, when the displacement exceeds 10-20 times of the sampling capacity, the outlet valve of the sampling steel cylinder is closed, the numerical value change of a pressure gauge on the sampling steel cylinder is observed, when the numerical value of the pressure gauge of the sampling steel cylinder meets the analysis requirement or is close to the design operating pressure of the steel cylinder, the outlet valve and the inlet valve of the sampling steel cylinder are closed in sequence, and the fourth three-way valve and the third three-way valve are screwed to the bypass pipeline. Taking down the sampling steel cylinder, and finishing sampling;

(4) the sampling steel cylinder is replaced, the regulating valve of the online analysis module is slowly opened, the flow meter indicates that the flow is 20-30ML/min, the analysis and replacement requirements can be met, the operation of the sampling module is not influenced, after the replacement is completed, the regulating valve of the online analysis module is closed, and the six-way valve rotates to perform chromatographic analysis.

In this embodiment, the on-line analysis is performed simultaneously with the sampling with the beneficial effects of the invention:

the LNG sampling and analyzing system can effectively solve the problem of gasification discrimination in the LNG sampling process, can simultaneously perform sampling and online analyzing operation, can be detached from an LNG pipeline or a storage tank at any time, can move at any time, and is convenient to carry.

Drawings

Fig. 1 is a schematic diagram of an overall structure of an LNG sampling and analyzing system according to the present invention.

Fig. 2 is an enlarged view of the cryogenic liquid delivery module.

FIG. 3 is an enlarged view of the gasification module.

FIG. 4 is a schematic view of a corrugated groove structure in a heating module of a gasification module.

FIG. 5 is an enlarged view of the boost module.

FIG. 6 is an enlarged view of a sampling module.

FIG. 7 is an enlarged view of an on-line analysis module.

Description of the reference numerals

1-1 sampling outer sleeve; 1-2 sampling capillary inner tube; 1-3 emptying a pipeline; 1-4 regulating valve; 1-5 thermometers;

2-0 flash vaporizer; 2-1 power supply unit; 2-2 heating the module; 2-3 capillary gasification tubes; 2-4 buffer tanks; 2-5 pressure gauges; 2-6 temperature controllers; 2-7 one-way valves; 2-8 insulating layers;

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

4-1 sampling steel cylinder; 4-2 inlet regulating valves; 4-3 outlet regulating valves; 4-4 bypass pipes; 4-5 a third three-way valve; 4-6 fourth three-way valves; 4-7 pressure gauge; 4-8 quick plugs; 4-9 sampling bags; 4-10 quick plugs;

5-0 online analysis module (or unit); 5-1 regulating valve; 5-2 six-way valves (six-way sampling valves); 5-3 lithium battery power supply module; 5-4 gas chromatograph; 5-5 gas cylinder; 5-6 emptying pipelines and 5-7 flow meters.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

As shown in fig. 1-7, an LNG sampling and analyzing system includes a cryogenic liquid delivery module, a gasification module for gasifying an LNG sample, a pressurization module for pressurizing the LNG sample, and a sampling module for storing the LNG sample, which are sequentially disposed along an LNG sampling pipe, wherein a branch pipe is divided between the pressurization module and the sampling module for connecting to an online analysis module, and the end of the sampling pipe is connected to a vent main.

The low-temperature liquid conveying module comprises a sampling capillary inner tube 1-2 connected with an LNG pipeline or a storage tank (not shown in the figure) and used for conveying liquid LNG, a sampling outer sleeve 1-1 is sleeved on the periphery of the sampling capillary inner tube 1-2, liquid LNG is filled in the space between the sampling outer sleeve 1-1 and the sampling capillary inner tube 1-2, the tail end of the sampling capillary inner tube 1-2 is connected with a capillary gasification tube 2-3 in a gasification module through a one-way valve 2-7, the sampling outer sleeve 1-1 is divided into an emptying pipeline 1-3 connected with an emptying main pipeline, and the emptying pipeline is provided with an adjusting valve 1-4 and a thermometer 1-5.

The sampling capillary inner tube 1-2 is, for example, a 0.53mm stainless steel capillary. The effect of governing valve 1-4 lies in when having gas production in the sample pipeline, and its temperature can be higher than the temperature of LNG, opens the governing valve, and the gas that will produce is discharged, prevents that gasified LNG from getting into sample capillary inner tube 1-2, influences sample stability, especially has a great amount of gas production in the initial sampling stage.

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

The sampling capillary inner tube 1-2 is a sampling pipeline positioned in the low-temperature liquid conveying module. The front end of the sampling analysis system can be flexibly connected with an analysis port of a storage tank or a pipeline in a flange or ferrule mode.

The gasification module comprises a flash evaporation gasifier 2-0 connected with the low-temperature liquid conveying module through a sampling pipeline, the flash evaporation gasifier internally comprises a heating module 2-2, a power supply unit 2-1 connected with the heating module 2-2 and used for supplying power to the heating module, a capillary gasification pipe 2-3 connected with a sampling capillary inner pipe 1-2 of the low-temperature liquid conveying module through a one-way valve 2-7 and positioned in the heating module 2-2, and a one-way valve 2-7 arranged on the capillary gasification pipeline and positioned between the low-temperature liquid conveying module and the heating module, the gasification module also comprises a buffer tank 2-4 connected with the outlet of the capillary gasification pipe 2-3, a pressure gauge 2-5 arranged on the buffer tank, and a temperature controller 2-6 connected between the flash evaporation gasifier and the buffer tank 2-4. Preferably, the heating module is internally opened with a corrugated groove, and as shown in fig. 4, the capillary-gasification tubes 2-3 are arranged along the corrugated groove through the heating module. And a heat-insulating layer 2-8 is arranged outside the flash evaporation gasifier.

The power supply unit 2-1 can adopt a ternary lithium battery as a power supply, the heating module 2-2 can be made of metal with high heat conduction speed and large heat capacity, and preferably made of aluminum materials, and the function of the aluminum materials is to provide enough heat for LNG gasification in the capillary gasification pipe 2-3.

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

The volume of the buffer tank 2-4 is 15-30ml, preferably 20 ml. In addition, a thermometer is arranged in the heating device and connected with a 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.

The non-metal materials which are not easy to conduct heat are adopted for the one-way valves 2 to 7, for example, materials such as peek or PTFE are selected, and heat transfer between the capillary gasification tube and the sampling capillary inner tube can be avoided.

Heat conduction silica gel is coated in the corrugated groove in the heating module, so that heat transfer is facilitated between the heating module and the capillary gasification tube. The capillary gasification pipe is a sampling pipeline positioned in the gasification module.

The pressurizing module comprises a micro booster pump 3-1 arranged on a sampling pipeline led out from a buffer tank 2-4, a throttle valve 3-2 is arranged on a sample input pipeline of the micro booster pump 3-1, a flow meter 3-6 is arranged on a sample output pipeline of the micro booster pump, the sampling pipeline between the throttle valve and the gasifying module is divided into a bypass pipeline 3-3 through a first three-way valve 3-4, and the tail end of the bypass pipeline 3-3 is connected with the sampling pipeline between the flow meter 3-6 and the micro booster pump 3-1 through a second three-way valve 3-5.

The purpose of the pressurizing module is as follows: increasing the pressure, and thus the sampling volume, of the sampling cylinder in the subsequent sampling module provides sufficient capacity for off-line analysis, for example, for a 100mL sampling cylinder, by pressurizing to 1mPa, about 1000mL of gas can be provided for analysis.

The micro booster pump 3-1 is used to boost the pressure of the gaseous LNG sample and may be set to an outlet pressure of, for example, 1 mPa. The throttle valve 3-2 can set the flow rate to prevent the gasification module from fluctuating due to overlarge flow rate. Flow meters 3-6 display gas flow rates. The first three-way valve 3-4 and the second three-way valve 3-5 are used for switching the gas circuit between the bypass 3-3 and the pressurization pipeline.

The sampling module comprises a sampling steel cylinder 4-1 which is used for storing gasified LNG and is connected with a sampling pipeline led out from a flow meter 3-6, a gas input section sampling pipeline and a gas output section sampling pipeline of the sampling steel cylinder are respectively connected with an inlet regulating valve 4-2 and an outlet regulating valve 4-3, 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 tail end of the bypass pipeline 4-4 is connected on a sample conveying pipeline behind the outlet regulating valve through a fourth three-way valve 4-6, a bursting disc is arranged on the outlet regulating valve 4-3, the bursting pressure is determined according to the design pressure of the steel cylinder, for example, the pressure is 1mPa, the overhigh pressure is prevented, and the sampling cylinder explodes. A third three-way valve 4-5 and a fourth three-way valve 4-6 are used to switch the gas between the bypass 4-4 and the sampling flow path.

And 4-7 pressure gauges are arranged on the sampling steel cylinders to indicate the pressure in the sampling steel cylinders, so that the safety is ensured.

The sampling steel cylinder 4-1 is sized according to the requirement, usually 50-200ml, preferably 100ml, and can sufficiently meet the chromatographic analysis requirement after being pressurized to 1MPa (the filling pressure can be determined according to the analysis sample amount requirement). A quick plug 4-10 is arranged on the sampling pipeline between the third three-way valve 4-5 and the inlet regulating valve 4-2 of the sampling steel cylinder, another quick plug 4-8 is arranged on the sampling pipeline between the outlet regulating valve of the sampling steel cylinder and the fourth three-way valve, and the quick plug can be connected with a sampling bag 4-9 through a pipeline.

A branch pipe is branched from a sampling pipeline between the pressurization module and the sampling module and is used for connecting a portable analysis module (or a portable analysis unit) 5-0, the portable analysis module comprises an adjusting valve 5-1 on the analysis branch pipe, a six-way valve 5-2 connected with the adjusting valve, a lithium battery power supply module 5-3, a carrier gas steel cylinder 5-5 connected with the six-way valve 5-2 and a gas chromatograph 5-4 used for analyzing gas phase components, and the outlet of the six-way valve 5-2 is connected with an emptying pipeline 5-6.

Wherein, the carrier gas used by the gas chromatograph 5-5 is preferably helium, the chromatographic column is preferably PLOT Q0.32 mm multiplied by 30m (L), the film thickness is 50 μm, the detector is preferably a thermal conductivity cell detector, and H can be realized₂，N₂，CH₄，C₂H₆，C₃H₈And waiting for the simultaneous determination of the total components in the LNG.