CN107831049B - Intermittent sampling analysis device for LNG loading and unloading and use method thereof - Google Patents
Intermittent sampling analysis device for LNG loading and unloading and use method thereof Download PDFInfo
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- CN107831049B CN107831049B CN201711276933.3A CN201711276933A CN107831049B CN 107831049 B CN107831049 B CN 107831049B CN 201711276933 A CN201711276933 A CN 201711276933A CN 107831049 B CN107831049 B CN 107831049B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/22—Devices for withdrawing samples in the gaseous state
- G01N1/2226—Sampling from a closed space, e.g. food package, head space
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N1/00—Sampling; Preparing specimens for investigation
- G01N1/02—Devices for withdrawing samples
- G01N1/22—Devices for withdrawing samples in the gaseous state
- G01N1/2226—Sampling from a closed space, e.g. food package, head space
- G01N2001/2238—Sampling from a closed space, e.g. food package, head space the gas being compressed or pressurized
Abstract
The invention relates to an intermittent sampling analysis device for LNG loading and unloading and a using method thereof, which are characterized by comprising an LNG sampling probe, a gasification device, a sampling main pipeline, a BOG return device, an online analysis device, a manual sampling system, a sample collecting and filling system and a control system; the LNG sampling probe is connected with an inlet of the gasification device through the isolation shutoff valve and the temperature detection element, an outlet of the gasification device is connected with a BOG main pipe through a sampling main pipeline and a BOG return device, an outlet of the gasification device is also respectively connected with an online analysis device, a manual sampling system and an inlet of a sample collecting and filling system through the sampling main pipeline, an outlet of the sample collecting and filling system is connected with the BOG main pipe, and the sample collecting and filling system is also respectively connected with an instrument gas source and a pre-charging gas loading device; the isolation shutoff valve, the temperature detection element, the gasification device, the sampling main pipeline and the sample collecting and filling system are respectively and electrically connected with the control system.
Description
Technical Field
The invention relates to an intermittent sampling and analyzing device for LNG loading and unloading for LNG receiving station wharf unloading, LNG tank car loading and LNG filling stations and a using method thereof, and belongs to the technical field of liquefied natural gas sampling and analyzing.
Background
LNG (liquefied natural gas) is one of the most rapidly growing energy industries in the world as a safe and efficient clean energy, china pays more and more attention to the development of the LNG industry, LNG receiving stations which are put into production and planned in China cover Guangdong, fujian, zhejiang, shanghai, jiangsu, shandong, tianjin, liaoning, hebei and other provinces, the number of small natural gas liquefaction plants and LNG filling stations is more, LNG loading and unloading are important links involved in the stations, the LNG receiving stations are mainly divided into shipping, tank car transportation, filling stations and the like, the shipping LNG carries out trade settlement in energy units, LNG components are key parameters for calculating LNG density and unit calorific value, and analysis results directly influence the specific number and quality judgment of LNG handing over and metering. Since LNG is an ultra-low temperature liquid mixture and is very easy to vaporize, the liquid is easily subjected to rapid fractional vaporization of components under the influence of slight temperature and pressure changes, and a real flowing LNG sample capable of representing the ratio of the liquid mixture in a pipeline is obtained with great difficulty, so that the LNG sample must be kept in a supercooled state before vaporization, no component must be fractionally vaporized, and the gas component mixing ratio and the liquid component ratio should be completely consistent after vaporization.
The key links of the LNG tank car transportation sampling analysis device are the same as the shipping method, at present, LNG tank car transportation is the only carrier for liquid distribution of large LNG receiving stations and small liquefaction plants in China, the energy metering mode is adopted for all LNG imports, but the quality metering is always adopted for tank car export, and the difference exists in import and export management of the receiving stations, so that most receiving stations adopt gasified export natural gas components to calculate the heat value of liquid LNG, but the pipeline export is different from LNG supplies for liquid distribution, for example, sometimes the pipeline export gas comes from BOG evaporated gas of an LNG storage tank, and the LNG liquid distribution comes from a low-pressure export pump, and the two components have difference; the partial receiving stations consider the differentiation of downstream markets and carry out differentiated management and transportation and distribution on resources for pipeline export and liquid distribution; part of receiving stations face the practical requirement that a tank car development market is built first and then pipelines are built to improve the capacity, and a sampling analysis device needs to be configured for the tank car independently. Therefore, tanker transport also faces real needs of LNG sampling analysis devices. In addition, the LNG filling station, as a downstream sales terminal, has a trend of developing heat value metering regardless of a large trend of energy metering or a trend of satisfying a demand of a customer for high-heat-value fuel, and thus the demand of the LNG filling station for an LNG sampling analysis device is pressing day by day.
The conventional LNG sampling and analyzing device has the following problems: 1) A pressure reducing device or a pressure reducing regulating valve with a gasification function is arranged before gasification, so that the LNG sample is gasified in advance. 2) The heater power is not enough or can not be adjusted, can not satisfy the heat demand of LNG gasification under the different sample operating modes, and the gasification process is unstable moreover, causes the LNG sample gasification inhomogeneous. 3) The design is only carried out from two links of a sampling probe and a gasifier, and the integral design of the whole sampling device is lacked. 4) Has the defects of large occupied space, large investment, large sample sampling amount and the like.
Disclosure of Invention
In view of the above problems, an object of the present invention is to provide an LNG loading/unloading intermittent sampling analyzer capable of suppressing early vaporization of an LNG sample and ensuring uniform vaporization of the LNG sample, and a method for using the same.
In order to achieve the purpose, the invention adopts the following technical scheme: an intermittent sampling and analyzing device for LNG loading and unloading is characterized by comprising an LNG sampling probe, a gasification device, a sampling main pipeline, a BOG returning device, an online analyzing device, a manual sampling system, a sample collecting and filling system and a control system, wherein the sample collecting and filling system comprises three intermittent sampling pipelines, a first manual ball valve and a first check valve, each intermittent sampling pipeline comprises a sample collector, a second check valve, a constant-pressure piston type gas storage bottle with a floating piston structure, a first pressure regulating valve and an electromagnetic valve, and each constant-pressure piston type gas storage bottle is detachably arranged between the corresponding second check valve and the corresponding first pressure regulating valve; the LNG sampling probe is connected with the inlet of the gasification device through an isolation shutoff valve and a temperature detection element, the outlet of the gasification device is connected with a BOG main pipe through the sampling main pipeline and a BOG return device, the outlet of the gasification device is respectively connected with the online analysis device and the manual sampling system through the sampling main pipeline, the outlet of the gasification device is sequentially connected with the BOG main pipe through the inlets of three sample collectors, the first manual ball valve and the first check valve through the sampling main pipeline, and the outlet of each sample collector is sequentially connected with the pre-charging gas loading device through the corresponding second check valve, the constant-pressure piston type gas storage bottle and the first pressure regulating valve; each first pressure regulating valve is respectively connected with the instrument gas source, each sample collector is connected with the instrument gas source through the corresponding electromagnetic valve, and power is provided for each first pressure regulating valve and each electromagnetic valve through the instrument gas source; the isolation shutoff valve, the temperature detection element, the gasification device, the sampling main pipeline, the first pressure regulating valve and the electromagnetic valve are also respectively and electrically connected with the control system.
Preferably, the gasification device comprises a gasifier, a gasifier inlet temperature detection element, a gasifier internal temperature detection element, a gasifier outlet temperature detection element and an outlet pressure transmitter, wherein the gasifier adopts an electric heating type gasifier; the inlet of the vaporizer is provided with a vaporizer inlet temperature detection element for detecting the temperature of the LNG sample before vaporization, the vaporizer is internally provided with a vaporizer internal temperature detection element for detecting the temperature change of the LNG sample in the vaporization process, and the outlet of the vaporizer is connected with the sampling main pipeline through the vaporizer outlet temperature detection element for detecting the temperature of the vaporized gas sample and the outlet pressure transmitter for detecting the pressure of the vaporized gas sample; the gasifier inlet temperature detection element, the gasifier internal temperature detection element, the gasifier outlet temperature detection element and the outlet pressure transmitter are also respectively and electrically connected with the control system.
Preferably, a safety valve, a main pipeline flow meter, a pressure control device and a buffer tank are sequentially arranged on the sampling main pipeline, wherein the pressure control device comprises a second pressure regulating valve, a pressure transmitter and a pressure controller, and the second pressure regulating valve, the pressure transmitter and the pressure controller form a loop; the outlet of the gasification device is respectively connected with the BOG returning device and the pressure control device through the safety valve and a main pipeline flow meter, the safety valve is also connected with the BOG main pipe, the pressure control device is also connected with the inlet of the buffer tank, and the outlet of the buffer tank is respectively connected with the inlets of the online analysis device, the manual sampling system and the sample collector; the second pressure regulating valve and the pressure transmitter are respectively and electrically connected with the pressure controller, the main pipeline flowmeter and the pressure controller are also respectively and electrically connected with the control system, the pressure transmitter is used for detecting the pressure of a gas sample before entering the buffer tank and transmitting the detected pressure data to the pressure controller and the control system, and the pressure controller is used for adjusting the opening degree of the second pressure regulating valve according to the control of the control system.
Preferably, the BOG return device includes a second manual ball valve and a third check valve; and the main pipeline flow meter is connected with the BOG main pipe through the second manual ball valve and a third check valve.
Preferably, the online analysis device comprises a first branch flowmeter, an online analyzer and a third manual ball valve; and the outlet of the buffer tank is respectively connected with the first branch flowmeter and the online analyzer, and a third manual ball valve is arranged on a pipeline between the first branch flowmeter and the online analyzer.
Preferably, the manual sampling system comprises a second branch flow meter, a manual sampling steel cylinder and a fourth manual ball valve; the outlet of the buffer tank is respectively connected with the second branch flowmeter and the manual sampling steel cylinder, and a fourth manual ball valve is arranged on a pipeline between the second branch flowmeter and the manual sampling steel cylinder.
Preferably, the control system adopts a PLC controller, and a pressure control module, an intermittent sampling parameter setting module, a time sequence setting module, a valve control module, a fault detection module and an interlocking protection module are arranged in the control system; the pressure control module is used for controlling the opening degree of the second pressure regulating valve through the pressure controller according to detected pressure data and regulating the pressure of a gas sample before entering the sample collecting and filling system, and the pressure control module is also used for controlling the opening degree of the first pressure regulating valve according to a preset pressure value so as to regulate the back pressure of the constant-pressure piston type gas storage bottle; the intermittent sampling parameter setting module is used for setting intermittent sampling parameters according to the total LNG loading and unloading time of the tank car and sending the intermittent sampling parameters to the valve control module; the time sequence setting module is used for setting time sequences of all processes in the whole intermittent sampling analysis process and sending the time sequences to the valve control module; the valve control module is used for controlling the opening or closing of the corresponding electromagnetic valve according to set intermittent sampling parameters and a flow time sequence; the fault detection module is used for presetting the pressure, the temperature and the flow of an LNG sample during normal gasification, and sending an abnormal signal to the interlocking protection module when the temperature detected by the temperature detection element and the gasifier outlet temperature detection element, the pressure detected by the outlet pressure transmitter or the flow detected by the main pipeline flowmeter are abnormal; the interlock protection module is used for controlling the isolation shutoff valve to be closed when receiving an abnormal signal.
Preferably, the external part of the LNG sampling probe is insulated by adopting a nano material, and a connecting pipeline between the LNG sampling probe and the gasifier is less than 0.5m; and the loading gas in the pre-charging loading gas device adopts argon gas.
A use method of an intermittent sampling analysis device for LNG loading and unloading is characterized by comprising the following steps: step 1): arranging a constant-pressure piston type gas storage cylinder on an intermittent sampling pipeline, and setting intermittent sampling parameters, pressure values and an intermittent sampling analysis process, wherein the intermittent sampling parameters comprise sample collection amount and sampling time intervals; step 2): the LNG sampling probe takes out an LNG sample in a tank car loading and unloading main pipeline, the LNG sample is fully gasified in a gasification device, at the moment, if the overpressure of the gas at the outlet of the gasifier is detected, and the isolation shutoff valve is cut off emergently when the temperature or the flow is abnormal, and if the maintenance is needed, the corresponding manual ball valve can be closed; step 3): the gasified gas sample enters a buffer tank for mixing after the pressure stabilization regulation of a pressure control device, all electromagnetic valves are closed, and pipeline purging and pipeline emptying are carried out on a sampling pipeline through the gas sample; step 4): opening a pre-charging gas-loading device to provide back pressure for all constant-pressure piston type gas storage bottles, and adjusting the opening of a first pressure adjusting valve to adjust the back pressure of the constant-pressure piston type gas storage bottles so that the pressure of a gas sample at the inlet of each constant-pressure piston type gas storage bottle reaches a preset pressure value; step 5): opening all the electromagnetic valves, enabling the instrument gas source to provide power for all the sample collectors to start working, and enabling the gas samples to enter a sample collecting and filling system and be pumped into corresponding constant-pressure piston type gas storage cylinders through the sample collectors to be automatically sampled; step 6): and opening the third manual ball valve or the fourth manual ball valve according to the requirements, and carrying out online analysis or manual sampling on the gas sample through a corresponding online analyzer or a manual sampling steel cylinder.
Due to the adoption of the technical scheme, the invention has the following advantages: 1. the invention is a set of complete LNG intermittent sampling analytical equipment from sampling to analysis, overcome the past apparatus and only carry on the design from sampling and gasifying two aspects, only suitable for the ship transporting LNG and unloading or tank car loading pipeline LNG disadvantage of component analysis, because of being equipped with the sample and gathering the filling system, can pump the gas sample into the piston gas bomb of constant pressure intermittently according to the intermittence sampling parameter presumed in advance, can inhibit the gasification in advance of LNG sample, guarantee LNG sample gasify evenly, compared with collecting all gas samples to the gas holder and then injecting into the continuous sampling in the sample steel cylinder, the invention also has the characteristic of small, small investment and sample amount saving etc. of taking up an area of space. 2. The LNG sample is directly heated by the electric heater, the electric heater occupies small space, the defect that a water bath or steam heater needs to additionally process a heating medium can be overcome, and the LNG sample heating device is simple and efficient to operate. 3. The pre-charging gas loading device adopts argon as the charging and carrying gas, so that fine leakage at two sides of the constant-pressure piston type gas storage bottle is prevented, the argon does not influence the chromatographic analysis result, and the pre-charging gas loading device can be widely applied to the technical field of liquefied natural gas sampling and analysis.
Drawings
Fig. 1 is a schematic view showing the overall construction of an intermittent sampling analysis apparatus for LNG loading and unloading according to the present invention, wherein "-" denotes a sampling line,
and represents the instrument gas source pipeline.
Detailed Description
The present invention is described in detail below with reference to the attached drawings. It is to be understood, however, that the drawings are provided for the sole purpose of providing a better understanding of the invention and that they are not to be considered as limiting the invention. In the description of the present invention, it is to be understood that the terms "first," "second," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
As shown in fig. 1, the intermittent sampling and analyzing device for LNG loading and unloading provided by the present invention comprises an LNG sampling probe 1, an isolation shutoff valve 2, a temperature detecting element 3, a vaporizing device 4, a sampling main pipe 5, a BOG returning device 6, a BOG main pipe 7, an on-line analyzing device 8, a manual sampling system 9, a sample collecting and filling system 10, a pre-charged gas loading device 11, an instrument gas source 12 and a control system (not shown in the figure), wherein the sample collecting and filling system 10 comprises three intermittent sampling pipes 10-1, a first manual ball valve 10-2 and a first check valve 10-3, each intermittent sampling pipe 10-1 comprises a sample collector 10-4, a second check valve 10-5, a constant pressure piston type gas cylinder 10-6, a first pressure regulating valve 10-7 and a solenoid valve 10-8, and each constant pressure piston type gas cylinder 10-6 has a floating piston structure, and is capable of separating a gas sample from a pre-charged carrier gas and maintaining a required constant pressure, and is detachably disposed between the corresponding second check valve 10-5 and the first pressure regulating valve 10-7.
Each first pressure regulating valve 10-7 is respectively connected with an instrument air source 12, an inlet of each sample collector 10-4 is connected with the instrument air source 12 through a corresponding electromagnetic valve 10-8, and power is provided for each first pressure regulating valve 10-7 and each electromagnetic valve 10-8 through the instrument air source 12. In addition, the isolation shutoff valve 2, the temperature detection element 3, the gasification device 4, the sampling main pipeline 5, the first pressure regulating valve 10-7 and the electromagnetic valve 10-8 are respectively and electrically connected with a control system.
In a preferred embodiment, an inlet needle valve 10-6-1 is arranged at the inlet of the constant pressure piston type gas cylinder 10-6, an outlet needle valve 10-6-2 is arranged at the outlet, and a pressure gauge 10-6-3 is arranged on the constant pressure piston type gas cylinder 10-6.
In a preferred embodiment, the vaporizer 4 includes a vaporizer 4-1, a vaporizer inlet temperature sensing element 4-2, a vaporizer internal temperature sensing element 4-3, a vaporizer outlet temperature sensing element 4-4, and an outlet pressure transmitter 4-5. An inlet of a vaporizer 4-1 is provided with a vaporizer inlet temperature detection element 4-2 for detecting the temperature of an LNG sample before vaporization, an internal vaporizer temperature detection element 4-3 for detecting the temperature change of the LNG sample in the process of vaporization is arranged in the vaporizer 4-1, an outlet of the vaporizer 4-1 is connected with a sampling main pipeline 5 through a vaporizer outlet temperature detection element 4-4 and an outlet pressure transmitter 4-5, the vaporizer outlet temperature detection element 4-4 is used for detecting the temperature of the vaporized gas sample, and the outlet pressure transmitter 4-5 is used for detecting the pressure of the vaporized gas sample. The gasifier inlet temperature detection element 4-2, the gasifier internal temperature detection element 4-3, the gasifier outlet temperature detection element 4-4 and the outlet pressure transmitter 4-5 are also respectively and electrically connected with a control system.
In a preferred embodiment, a safety valve 5-1, a main pipeline flow meter 5-2, a pressure control device 5-3 and a buffer tank 5-4 are arranged on the sampling main pipeline 5 in sequence. An outlet of the gasification device 4 is respectively connected with a BOG return device 6 and a pressure control device 5-3 through a safety valve 5-1 and a main pipeline flow meter 5-2, the safety valve 5-1 is also connected with a BOG main pipe 7, the pressure control device 5-3 is also connected with an inlet of a buffer tank 5-4, an outlet of the buffer tank 5-4 is respectively connected with inlets of an online analysis device 8, a manual sampling system 9 and a sample collector 10-4, the safety valve 5-1 is used for preventing the overpressure danger of the system, the main pipeline flow meter 5-2 is used for measuring the flow of the sampling main pipeline 5 in real time, the pressure control device 5-3 is used for preventing the sampling main pipeline 5 from excessively fluctuating, so that a gas sample is ensured to enter the buffer tank 5-4 at uniform pressure, the buffer tank 5-4 is used for preliminary mixing of the gas sample, and the main pipeline flow meter 5-2 and the pressure control device 5-3 are respectively and electrically connected with the control system.
In a preferred embodiment, the pressure control means 5-3 includes a second pressure regulating valve 5-3-1, a pressure transmitter 5-3-2 and a pressure controller 5-3-3, and the second pressure regulating valve 5-3-1, the pressure transmitter 5-3-2 and the pressure controller 5-3-3 form a loop. The second pressure regulating valve 5-3-1 and the pressure transmitter 5-3-2 are respectively electrically connected with the pressure controller 5-3-3, the pressure controller 5-3-3 is also electrically connected with the control system, the pressure transmitter 5-3-2 is used for detecting the pressure of a gas sample before entering the buffer tank 5-4 and sending the detected pressure data to the pressure controller 5-3-3 and the control system, and the pressure controller 5-3-3 is used for regulating the opening of the second pressure regulating valve 5-3-1 according to the control of the control system.
In a preferred embodiment, the BOG return means 6 includes a second manual ball valve 6-1 and a third check valve 6-2. The main pipeline flow meter 5-2 is connected with a BOG main pipe 7 through a second manual ball valve 6-1 and a third check valve 6-2. The second manual ball valve 6-1 is used for cutting off the connection between the BOG returning device 6 and the sampling main pipeline 5 when the third check valve 6-2 is maintained, and the third check valve 6-2 is used for preventing BOG gas in the BOG main pipeline 7 from entering the sampling main pipeline 5.
In a preferred embodiment, the online analysis device 8 includes a first branch flow meter 8-1, an online analyzer 8-2, and a third manual ball valve 8-3. An outlet of the buffer tank 5-4 is connected with a first branch flowmeter 8-1 and an online analyzer 8-2 through pipelines respectively, the first branch flowmeter 8-1 is used for measuring the flow of a gas sample entering the online analyzer 8 in real time, and a third manual ball valve 8-3 is arranged on the pipeline between the first branch flowmeter 8-1 and the online analyzer 8-2.
In a preferred embodiment, the manual sampling system 9 includes a second branch flow meter 9-1, a manual sampling cylinder 9-2, and a fourth manual ball valve 9-3. An outlet of the buffer tank 5-4 is connected with a second branch flow meter 9-1 and a manual sampling steel bottle 9-2 through pipelines respectively, the second branch flow meter 9-1 is used for measuring the flow of a gas sample entering the manual sampling system 9 in real time, and a fourth manual ball valve 9-3 is arranged on the pipeline between the second branch flow meter 9-1 and the manual sampling steel bottle 9-2.
In a preferred embodiment, the control system can adopt a PLC controller, and a pressure control module, an intermittent sampling parameter setting module, a time sequence setting module, a valve control module, a fault detection module and an interlocking protection module are arranged in the control system. The pressure control module is used for controlling the opening degree of the second pressure regulating valve 5-3-1 through the pressure controller 5-3-3 according to detected pressure data, regulating the pressure of a gas sample before entering the sample collecting and filling system 10 and realizing the pressure stabilizing regulation of the gas sample, and is also used for controlling the opening degree of the first pressure regulating valve 10-7 according to a preset pressure value so as to regulate the back pressure of the constant-pressure piston type gas storage bottle 10-6, wherein the pressure value can be preset according to actual requirements. The intermittent sampling parameter setting module is used for presetting intermittent sampling parameters such as sample collection quantity, sampling time interval and the like according to the total LNG loading and unloading time of the tank car and sending the parameters to the valve control module. The time sequence setting module is used for setting time sequences of all processes of the whole intermittent sampling analysis, wherein the processes comprise pipeline purging, pipeline emptying, automatic sampling, online analysis, manual sampling and the like, and the time sequences are sent to the valve control module. The valve control module is used for controlling the opening or closing of the corresponding electromagnetic valve 10-8 according to the set intermittent sampling parameters and the process sequence. The fault detection module is used for presetting the pressure, the temperature and the flow of the LNG sample during normal gasification, and sending an abnormal signal to the interlocking protection module when the temperature detected by the temperature detection element 3 and the vaporizer outlet temperature detection element 4-4, the pressure detected by the outlet pressure transmitter 4-5 or the flow detected by the main pipeline flowmeter 5-2 is abnormal. The interlock protection module is used for controlling the isolation shutoff valve 2 to close when receiving the abnormal signal.
In a preferred embodiment, the exterior of the LNG sampling probe 1 is insulated by adopting a nano material, and a connecting pipeline between the LNG sampling probe 1 and the vaporizer 4-1 is less than 0.5m, so that the requirement of supercooling degree is met, and the LNG sample can be effectively prevented from being fractionated in advance.
In a preferred embodiment, the vaporizer 4-1 can be an electrically heated vaporizer 4-1, and the power of the vaporizer 4-1 can be adjusted according to the LNG sample of different composition and flow rate to ensure complete vaporization of the LNG sample in the vaporizer 4-1.
In a preferred embodiment, the carrier gas in the pre-charged carrier gas device 11 may be a non-gaseous sample constituent gas such as argon.
The method of using the intermittent sampling analyzer for LNG loading and unloading according to the present invention will be described in detail below with reference to specific examples:
1) Three constant-pressure piston type gas storage bottles 10-6 are respectively arranged on three intermittent sampling pipelines 10-1, the sample collection amount, the sampling time interval (the sample amount of each sampling and the time interval between every two samplings), the pressure value and the whole intermittent sampling and analyzing process of the constant-pressure piston type gas storage bottles 10-6 are set, and the following description is given by taking the process as pipeline purging, pipeline emptying, automatic sampling, online analysis and manual sampling as an example.
2) The LNG sampling probe 1 takes out an LNG sample in a tank car loading and unloading main pipeline, the LNG sample is fully gasified in the gasification device 4, the isolation shut-off valve 2 is cut off emergently if overpressure, temperature or abnormal flow of outlet gas of the gasifier 4-1 are detected, and the corresponding manual ball valve can be closed if maintenance is needed.
3) And (3) the gasified gas sample enters a buffer tank 5-4 to be mixed after the pressure is regulated by a pressure control device 5-3, all electromagnetic valves 10-8 are closed, and pipeline purging and pipeline emptying are carried out on the sampling pipeline through the gas sample.
4) And opening the pre-charging gas loading device 11 to provide back pressure for the three constant-pressure piston type gas storage bottles 10-6, and adjusting the opening of the first pressure adjusting valve 10-7 to adjust the back pressure of the constant-pressure piston type gas storage bottles 10-6 so that the pressure of a gas sample at the inlet of the constant-pressure piston type gas storage bottles 10-6 reaches a preset pressure value.
5) All the electromagnetic valves 10-8 are opened, the instrument gas source 12 provides power for all the sample collectors 10-4 to start working, and gas samples enter the sample collecting and filling system 10 and are pumped into corresponding constant-pressure piston type gas storage bottles 10-6 through the sample collectors 10-4 to be automatically sampled.
6) And opening the third manual ball valve 8-3 or the fourth manual ball valve 9-3 as required, and carrying out online analysis or manual sampling on the gas sample through the online analyzer 8-2 or the manual sampling steel cylinder 9-2.
The above embodiments are only used for illustrating the present invention, and the structure, connection mode, manufacturing process, etc. of the components may be changed, and all equivalent changes and modifications performed on the basis of the technical solution of the present invention should not be excluded from the protection scope of the present invention.
Claims (9)
1. An intermittent sampling and analyzing device for LNG loading and unloading is characterized by comprising an LNG sampling probe, a gasification device, a sampling main pipeline, a BOG returning device, an online analysis device, a manual sampling system, a sample collecting and filling system and a control system, wherein the sample collecting and filling system comprises three intermittent sampling pipelines, a first manual ball valve and a first check valve, each intermittent sampling pipeline comprises a sample collector, a second check valve, a constant-pressure piston type gas storage bottle with a floating piston structure, a first pressure regulating valve and an electromagnetic valve, and each constant-pressure piston type gas storage bottle is detachably arranged between the corresponding second check valve and the corresponding first pressure regulating valve;
the LNG sampling probe is connected with the inlet of the gasification device through an isolation shut-off valve and a temperature detection element, the outlet of the gasification device is connected with a BOG main pipe through the sampling main pipeline and a BOG return device, the outlet of the gasification device is respectively connected with the online analysis device and the manual sampling system through the sampling main pipeline, the outlet of the gasification device is further sequentially connected with the BOG main pipe through the inlet of the sample collector, the first manual ball valve and the first check valve through the sampling main pipeline, and the outlet of each sample collector is sequentially connected with a pre-filling carrier gas device through the corresponding second check valve, the constant-pressure piston type gas storage bottle and the first pressure regulating valve;
each first pressure regulating valve is respectively connected with an instrument gas source, each sample collector is connected with the instrument gas source through a corresponding electromagnetic valve, and power is provided for each first pressure regulating valve and each electromagnetic valve through the instrument gas source;
the isolation shutoff valve, the temperature detection element, the gasification device, the sampling main pipeline, the first pressure regulating valve and the electromagnetic valve are also respectively and electrically connected with the control system.
2. The intermittent sampling and analyzing device for LNG loading and unloading of claim 1, wherein the vaporizer comprises a vaporizer, a vaporizer inlet temperature detecting element, a vaporizer internal temperature detecting element, a vaporizer outlet temperature detecting element and an outlet pressure transmitter, wherein the vaporizer is an electrically heated vaporizer;
the inlet of the vaporizer is provided with a vaporizer inlet temperature detection element for detecting the temperature of the LNG sample before vaporization, the vaporizer is internally provided with a vaporizer internal temperature detection element for detecting the temperature change of the LNG sample in the vaporization process, and the outlet of the vaporizer is connected with the sampling main pipeline through the vaporizer outlet temperature detection element for detecting the temperature of the vaporized gas sample and the outlet pressure transmitter for detecting the pressure of the vaporized gas sample;
the gasifier inlet temperature detection element, the gasifier internal temperature detection element, the gasifier outlet temperature detection element and the outlet pressure transmitter are also respectively and electrically connected with the control system.
3. The intermittent sampling and analyzing device for LNG loading and unloading of claim 2, wherein a safety valve, a main line flow meter, a pressure control device and a buffer tank are sequentially provided on the sampling main line, wherein the pressure control device comprises a second pressure regulating valve, a pressure transmitter and a pressure controller, and the second pressure regulating valve, the pressure transmitter and the pressure controller form a loop;
the outlet of the gasification device is respectively connected with the BOG return device and the pressure control device through the safety valve and a main pipeline flow meter, the safety valve is also connected with the BOG main pipe, the pressure control device is also connected with the inlet of the buffer tank, and the outlet of the buffer tank is respectively connected with the inlets of the online analysis device, the manual sampling system and the sample collector;
second pressure regulating valve and pressure transmitter electricity respectively connect pressure controller, total pipeline flowmeter and pressure controller still electricity respectively connect control system, pressure transmitter is used for detecting the pressure that gets into gas sample before the buffer tank and will detect pressure data send pressure controller and control system, pressure controller is used for the basis control system's control is adjusted second pressure regulating valve's aperture.
4. The intermittent sampling analysis device for LNG loading and unloading of claim 3, wherein the BOG returning means comprises a second manual ball valve and a third check valve; and the main pipeline flow meter is connected with the BOG main pipe through the second manual ball valve and a third check valve.
5. The intermittent sampling and analysis device for loading and unloading of LNG of claim 4, wherein the on-line analysis device comprises a first bypass flowmeter, an on-line analyzer and a third manual ball valve;
and the outlet of the buffer tank is respectively connected with the first branch flowmeter and the online analyzer, and the third manual ball valve is arranged on a pipeline between the first branch flowmeter and the online analyzer.
6. The intermittent sampling and analysis device for loading and unloading of LNG of claim 5, wherein the manual sampling system comprises a second branch flow meter, a manual sampling cylinder and a fourth manual ball valve;
the outlet of the buffer tank is respectively connected with the second branch flowmeter and the manual sampling steel cylinder, and a fourth manual ball valve is arranged on a pipeline between the second branch flowmeter and the manual sampling steel cylinder.
7. The intermittent sampling analysis device for LNG loading and unloading of claim 6, wherein the control system adopts a PLC controller, and a pressure control module, an intermittent sampling parameter setting module, a timing setting module, a valve control module, a fault detection module and an interlocking protection module are arranged in the control system;
the pressure control module is used for controlling the opening degree of the second pressure regulating valve through the pressure controller according to detected pressure data and regulating the pressure of a gas sample before entering the sample collecting and filling system, and the pressure control module is also used for controlling the opening degree of the first pressure regulating valve according to a preset pressure value so as to regulate the back pressure of the constant-pressure piston type gas cylinder;
the intermittent sampling parameter setting module is used for setting intermittent sampling parameters according to the total LNG loading and unloading time of the tank car and sending the intermittent sampling parameters to the valve control module;
the time sequence setting module is used for setting time sequences of all processes in the whole intermittent sampling analysis process and sending the time sequences to the valve control module;
the valve control module is used for controlling the opening or closing of the corresponding electromagnetic valve according to set intermittent sampling parameters and a flow time sequence;
the fault detection module is used for presetting the pressure, the temperature and the flow of an LNG sample during normal gasification, and sending an abnormal signal to the interlocking protection module when the temperature detected by the temperature detection element and the vaporizer outlet temperature detection element, the pressure detected by the outlet pressure transmitter or the flow detected by the main pipeline flowmeter are abnormal;
the interlock protection module is used for controlling the isolation shutoff valve to be closed when receiving an abnormal signal.
8. The intermittent sampling analysis device for LNG handling of any one of claims 1 to 7, wherein the LNG sampling probe is externally insulated with nano-materials, and the connecting pipeline between the LNG sampling probe and the vaporizer is less than 0.5m; and the loading gas in the pre-charging loading gas device adopts argon gas.
9. A use method of an intermittent sampling analysis device for LNG loading and unloading is characterized by comprising the following steps:
step 1): arranging a constant-pressure piston type gas storage cylinder on an intermittent sampling pipeline, and setting intermittent sampling parameters, pressure values and an intermittent sampling analysis process, wherein the intermittent sampling parameters comprise sample collection amount and sampling time intervals;
step 2): the LNG sampling probe takes out an LNG sample in a tank car loading and unloading main pipeline, the LNG sample is fully gasified in a gasification device, and at the moment, if the overpressure of the gas at the outlet of the gasifier is detected, the isolation shutoff valve is cut off emergently when the temperature or the flow is abnormal, and if the maintenance is needed, the corresponding manual ball valve can be closed;
and step 3): the gasified gas sample enters a buffer tank for mixing after the pressure stabilization regulation of a pressure control device, all electromagnetic valves are closed, and pipeline purging and pipeline emptying are carried out on a sampling pipeline through the gas sample;
step 4): opening a pre-charging gas loading device to provide back pressure for all constant-pressure piston type gas storage bottles, and adjusting the opening of a first pressure adjusting valve to adjust the back pressure of the constant-pressure piston type gas storage bottles so that the pressure of a gas sample at the inlet of each constant-pressure piston type gas storage bottle reaches a preset pressure value;
step 5): opening all the electromagnetic valves, enabling the instrument gas source to provide power for all the sample collectors to start working, and enabling the gas samples to enter a sample collecting and filling system and be pumped into corresponding constant-pressure piston type gas storage cylinders through the sample collectors to be automatically sampled;
step 6): and opening the third manual ball valve or the fourth manual ball valve according to the requirements, and carrying out online analysis or manual sampling on the gas sample through a corresponding online analyzer or a manual sampling steel cylinder.
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| CN111024829B (en) * | 2018-10-09 | 2023-02-28 | 中国石油天然气股份有限公司 | Natural gas quality detection system and method |
| CN109900860A (en) * | 2019-02-01 | 2019-06-18 | 中国石油天然气集团公司 | A kind of gas pipeline hydrogen sulfide real-time analysis method |
| CN110045041B (en) * | 2019-05-20 | 2024-02-06 | 中海石油气电集团有限责任公司 | Liquefied natural gas sampling and continuous collecting device |
| CN114877260B (en) * | 2022-04-13 | 2024-03-08 | 中海石油气电集团有限责任公司 | High compact LNG sampling gasification device with self-adaptation function |
| CN116718438B (en) * | 2023-08-07 | 2023-10-27 | 苏州杜尔气体化工装备有限公司 | Gas quality detection sampling device for natural gas skid-mounted gas station |
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