CN112415101A - Oxygen impurity online monitoring system, method and application - Google Patents
Oxygen impurity online monitoring system, method and application Download PDFInfo
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- CN112415101A CN112415101A CN201910785233.XA CN201910785233A CN112415101A CN 112415101 A CN112415101 A CN 112415101A CN 201910785233 A CN201910785233 A CN 201910785233A CN 112415101 A CN112415101 A CN 112415101A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N30/60—Construction of the column
- G01N30/6052—Construction of the column body
- G01N30/6073—Construction of the column body in open tubular form
- G01N30/6078—Capillaries
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N30/00—Investigating or analysing materials by separation into components using adsorption, absorption or similar phenomena or using ion-exchange, e.g. chromatography or field flow fractionation
- G01N30/02—Column chromatography
- G01N2030/022—Column chromatography characterised by the kind of separation mechanism
- G01N2030/025—Gas chromatography
Abstract
The invention discloses an oxygen impurity online monitoring system, which comprises a main box body, an explosion-proof processing unit, an online detection unit and a sample interface unit. The oxygen impurity online monitoring system and the method provided by the invention can be directly connected with the lateral line of a production device when explosion-proof treatment is carried out. The gas chromatography-hydrogen flame detector analysis method of oxides in liquefied hydrocarbon raw materials can meet 0.05ml/m through the optimized development of instruments and methods3Compared with the existing analysis method and analysis technology, the oxide monitoring and analysis method has lower detection limit of the oxide, can meet the requirement of a new generation of polyolefin catalyst on the content of the liquefied hydrocarbon raw material impurities, and improves the sensitivity of the analysis technology.
Description
Technical Field
The invention belongs to the field of petrochemical raw material detection and analysis, and particularly relates to an oxygen impurity online monitoring system, method and application.
Background
The liquefied hydrocarbon raw material is C1-C4 liquefiable low-carbon light hydrocarbon and comprises C1 methane, C2 ethane and ethylene acetylene, C3 propane, propylene and propyne, C4 butane, butylene and butyne and the like. Is the most important production raw material in petrochemical industry, polyolefin industry, rubber industry, polyester industry and the like, and the purity and the impurity content of the raw material directly influence the activity of the catalyst, the safety of a production device, the performance of a high polymer material and other production key indexes. Therefore, the monitoring and analysis of the impurity content in the liquefied hydrocarbon raw material by designing and manufacturing the on-line engineering chromatogram is the premise of preventing the inactivation of the catalyst and ensuring the stable production and the product quality.
In the petrochemical industry and the coal chemical industry, small molecular oxides enter liquefied hydrocarbons from crude oil or coal raw materials in the petroleum cracking and coal gasification processes, and particularly, as the MTO and MTP processes taking coal as the raw materials adopt a Fischer-Tropsch synthesis technology, the intermediate products are the oxides. Therefore, the final liquefied hydrocarbon product inevitably contains small molecular alcohols, ethers, etc. as intermediate products. These oxides can directly destroy the titanium-magnesium active center and internal and external electron donors of the polyolefin catalyst to lose the activity, so that the monitoring and analysis must be carried out and the content must be strictly controlled.
No patent document currently relates to a system, method and application for monitoring oxygen impurities in liquefied hydrocarbon feedstocks in the fields of petrochemical and coal chemical industries. Patent documents CN102650625A and CN102650624A propose a method for analyzing a hydrocarbon mixed gas in the presence of an oxygen-containing compound and a composition analyzer for a hydrocarbon mixed gas in the presence of an oxygen-containing compound. The impurities analyzed in these two patents are carbon monoxide and carbon dioxide gases, and the oxygen impurities monitored in the present invention are organic oxides rather than oxygen-containing permanent gases. There is therefore a need in the petrochemical and coalification arts to provide an on-line monitoring system and method for oxygen impurities in liquefied hydrocarbon feedstocks.
Disclosure of Invention
The invention aims to solve the technical problem of providing an oxygen impurity online monitoring system, a method and an application aiming at the defects of the prior art, and the system, the method and the application can realize online monitoring of oxygen impurities in liquefied hydrocarbon raw materials, so that production personnel can accurately obtain the content of oxides in the liquefied hydrocarbon raw materials in real time; meanwhile, the feeding amount of the liquefied hydrocarbon raw material can be regulated and controlled according to the content of the oxide in the obtained liquefied hydrocarbon raw material so as to regulate and control the performance of the prepared polymer and ensure the stable operation of a polymer generating device.
The oxide detection technology in the prior art has the following defects through research: 1) the detection types of the oxides are very limited, usually not more than 3, and most of the oxides are only specific to the oxides; 2) only offline sampling analysis can be performed, online real-time monitoring cannot be achieved, and personnel safety and sample representativeness cannot be guaranteed; 3) the data processing needs manual calculation or correction, the data result cannot be automatically processed, and meanwhile, the result data cannot be automatically transmitted remotely; 4) the oxide detection and analysis precision is not enough, and the content of the oxide in the liquefied hydrocarbon raw material is required to be controlled to be 0.10ml/m by the polyolefin catalyst3However, it is difficult to achieve 0.10ml/m by the current analytical technique3And (3) oxide detection analysis. Therefore, the present invention provides an online monitoring system and method for oxygen impurities in liquefied hydrocarbon feedstock, which overcomes the above-mentioned drawbacks.
To this end, a first aspect of the present invention provides an on-line monitoring system for oxygen impurities, comprising:
a main box body;
an explosion-proof processing unit for providing inert gas into the main box body;
the online detection unit is arranged in the main box body and comprises a gas chromatograph provided with a hydrogen flame detector and a computer data processing system connected with the gas chromatograph, and the computer data processing system is used for processing a detection result of the gas chromatograph to obtain oxide detection data; and
and the sample interface unit is connected with the online detection unit and is used for providing an online sample for the online monitoring unit.
In some preferred embodiments of the present invention, the main case is a movable main case.
In some preferred embodiments of the present invention, the sample interface unit employs a multi-channel switching synchronous gasification system.
In some embodiments of the invention, the on-line monitoring system further comprises an analysis unit configured to regulate the feed amount of liquefied hydrocarbon feedstock and/or catalyst based on the oxygenate detection data.
In some embodiments of the present invention, the online monitoring system further includes an electrical apparatus/communication interface unit, where the electrical apparatus/communication interface unit includes an electrical apparatus interface and a communication interface, where one end of the electrical apparatus interface is connected to a power supply, and the other end of the electrical apparatus interface is connected to the power supply interface of each instrument through a connection line, and is used to supply power to each instrument; one end of the communication interface is connected with the computer data processing system, the other end of the communication interface is connected with the analysis unit, and the communication interface is used for transmitting the oxide detection data of the computer data processing system to the analysis unit.
In some embodiments of the present invention, the online monitoring system further comprises a standard gas/carrier gas interface unit coupled to the gas chromatograph for providing a standard gas and/or a carrier gas to the gas chromatograph.
In some embodiments of the present invention, the online monitoring system further comprises a main tank internal atmosphere evacuation valve connected to the main tank, and a carrier gas feed gas evacuation valve connected to the gas chromatograph.
In some embodiments of the present invention, the online monitoring system further comprises a gas discharge valve box, and the atmosphere evacuation valve and the carrier gas raw material gas evacuation valve in the main box body are arranged in the gas discharge valve box.
In some embodiments of the invention, the online monitoring system further comprises a control module.
In some embodiments of the present invention, each device of the online monitoring system is connected to the control module through a pipeline, and the operation of each device is controlled by the control module.
In some embodiments of the invention, the sample interface unit comprises a filtration device coupled to the liquefied hydrocarbon feedstock side-line interface for filtering the liquefied hydrocarbon feedstock from the liquefied hydrocarbon feedstock side-line interface.
In some preferred embodiments of the present invention, the sample interface unit further comprises a pressure reducing constant pressure device, one end of the pressure reducing constant pressure device is connected to the filtering device, and the other end of the pressure reducing constant pressure device is connected to the sample inlet of the gas chromatograph, and the pressure reducing constant pressure device is used for gasifying the liquefied hydrocarbon feedstock after being filtered.
In some preferred embodiments of the invention, flash vaporization is performed to obtain an on-line sample.
In some embodiments of the invention, an inlet of the explosion-proof processing unit is connected with an inert gas source, and an outlet of the explosion-proof processing unit is connected with the main box body; wherein the pressure of the inert gas in the explosion-proof processing unit is 0.4-1.0 MPa.
In some preferred embodiments of the invention, the pressure is 0.4 to 0.8 MPa.
In some preferred embodiments of the invention, the pressure is 0.5 to 0.8 MPa.
In some embodiments of the invention, the hydrogen flame detector comprises a power source connected to the gas chromatograph; an ion chamber; flame, nozzle, insulator connected with inlet and outlet of carrier gas; a collector and an emitter coupled to the ion chamber.
In some embodiments of the present invention, the gas chromatograph uses a WCOT capillary column using methyl polysiloxane and polyethylene glycol as stationary phases and/or a PLOT capillary column using bonded silica gel as stationary phases; the column length is 10-60 m; the inner diameter is 0.25-0.52 mm. In a second aspect of the present invention, there is provided an on-line monitoring method for oxygen impurities in a liquefied hydrocarbon feedstock by using the on-line monitoring system according to the first aspect, comprising the following steps:
establishing the online monitoring system;
starting the on-line monitoring system to enable the liquefied hydrocarbon raw material to enter the on-line monitoring system through a liquefied hydrocarbon raw material side line interface, and detecting oxygen impurities in the liquefied hydrocarbon raw material to obtain oxide detection data;
and regulating the feeding amount of the liquefied hydrocarbon raw material and/or the catalyst according to the detection data.
In some embodiments of the invention, the method comprises the following steps:
establishing the online monitoring system;
starting an online monitoring system, allowing the liquefied hydrocarbon raw material to enter the sample interface unit through a liquefied hydrocarbon raw material lateral line interface, and sequentially performing filtration and pressure reduction treatment; meanwhile, a valve of a system purge gas box of the explosion-proof processing unit is opened, inert gas is sent into the main box body, inert gas atmosphere is formed in the main box body, and an atmosphere emptying valve in the main box body in the blow-down valve box is opened to enable the inert gas to flow in the main box body; a valve of a carrier gas interface box of the standard gas/carrier gas interface unit is opened, and carrier gas is sent to a gas chromatograph; the carrier gas purges the gas chromatograph; the liquefied hydrocarbon sample is gasified by the sample interface unit to obtain liquefied hydrocarbon gasification raw material, the liquefied hydrocarbon gasification raw material enters the gas chromatograph through the outlet of the sample interface unit so as to carry out qualitative and/or quantitative detection on oxygen impurities in the liquefied hydrocarbon gasification raw material, and the liquefied hydrocarbon gasification raw material is analyzed and processed by the computer data processing system to obtain oxide detection data; gas exhausted by the gas chromatograph is exhausted through an emptying valve box;
and the oxide detection data obtained by the processing of the computer data processing system is transmitted to the analysis unit through a communication interface, and the analysis unit regulates and controls the feeding amount of the liquefied hydrocarbon raw material and/or the catalyst according to the detection data.
In some embodiments of the invention, the liquefied hydrocarbon gasification feedstock is obtained by vacuum flashing and gasification.
In some embodiments of the invention, the reduced pressure flash is conducted in a simultaneous flash vaporizer.
In some embodiments of the invention, the standard gas is an oxide mixed standard gas.
In some embodiments of the present invention, the inert gas and the carrier gas are each independently selected from one or more of nitrogen, helium, hydrogen, and air.
In some embodiments of the invention, the inert gas is preferably nitrogen and the carrier gas is preferably helium.
In some embodiments of the present invention, the tail gas of the gas chromatograph is nitrogen.
In some embodiments of the present invention, the analysis conditions of the gas chromatograph include: column temperature: the initial temperature is-30-60 ℃, the maximum temperature is 100-350 ℃, and the heating rate is 1-30 ℃/min; the split ratio is 1-15: 1; the flow rate of the carrier gas is 1.0-11.0ml/min, and the constant flow mode is adopted; the flow rate of the tail blowing gas is 1.0-30.0 ml/min; the temperature of the hydrogen flame detector is 150 ℃ and 250 ℃, and the sample injection amount is 0.1-5 ml.
In some preferred embodiments of the present invention, the analysis conditions of the gas chromatograph include: column temperature: the initial temperature is 10-50 ℃, the temperature is kept for 1-10min, the temperature is raised to 60-200 ℃ at the speed of 2-20 ℃/min, the temperature is raised to 250 ℃ at the speed of 2-20 ℃/min, and the temperature is kept for 1-10 min; the split ratio is 1-10: 1; the flow rate of the carrier gas is 1.0-10.0ml/min, and the carrier gas is in a constant flow mode; the flow rate of the tail blowing gas is 2.0-20.0 ml/min; the temperature of the hydrogen flame detector is 150 ℃ and 250 ℃, and the sample injection amount is 0.1-5 ml.
In some embodiments of the invention, the oxygen impurities comprise volatile organic oxides.
In some preferred embodiments of the invention, the oxygen impurities comprise volatile organic oxides and the oxygen impurities comprise one or more of methyl chloride, ethyl chloride, propyl chloride, butyl chloride, vinyl chloride, allyl chloride, chlorobutene, chloroethyne, chloropropyne, chlorobutyne.
In some embodiments of the invention, the hydrogen flame detector employs signal-to-noise ratio as an oxide qualitative analysis condition.
In some preferred embodiments of the present invention, the hydrogen flame detector uses a signal-to-noise ratio as an oxide qualitative analysis condition, and the signal-to-noise ratio uses 2-10:1 as an oxide qualitative peak identification condition.
In some preferred embodiments of the present invention, the hydrogen flame detector uses a signal-to-noise ratio as an oxide qualitative analysis condition, and the signal-to-noise ratio uses 3-10:1 as an oxide qualitative peak identification condition.
In some embodiments of the present invention, the oxygen impurities in the liquefied hydrocarbon feedstock are quantitatively analyzed by using different standard oxide gases as standard substances, drawing an external standard calibration curve, and quantitatively calibrating the oxides to obtain the accurate content of the oxygen impurities.
In some preferred embodiments of the invention, the analysis unit regulates the feed of liquefied hydrocarbon feedstock and/or catalyst based on the oxygenate detection data,
in some embodiments of the invention, the analysis unit regulates the feed of liquefied hydrocarbon feedstock and/or catalyst based on the oxygenate detection data,
when the content of the oxygen impurities is less than 0.10ml/m3In the process, the liquefied hydrocarbon raw material and the catalyst are mixed according to a normal proportion;
when the content of the oxygen impurities is between 0.10 and 5.0ml/m3When the method is used, the amount of the catalyst is increased by 20-80% under the condition of not changing the sample amount of the liquefied hydrocarbon raw material to be mixed with the liquefied hydrocarbon raw material;
when the content of the oxygen impurities is more than 5.0ml/m3At that time, the liquefied hydrocarbon feedstock feed is stopped. In a third aspect, the invention provides a use of the on-line monitoring system of the first aspect or the on-line monitoring method of the second aspect in olefin polymerization production.
In some preferred embodiments of the present invention, the on-line monitoring system of the first aspect or the on-line monitoring method of the second aspect is applied to industrial production of ethylene polymerization, propylene polymerization or butene polymerization.
The oxygen impurity online monitoring system and method provided by the invention have the beneficial effects that:
1) the on-line monitoring system can be directly connected with the lateral line of the production device for explosion-proof treatment. Compared with the prior art, the method comprises the steps of manually sampling and then sending the sample to a laboratory for analysis and detection, the secondary pollution of the sample is reduced, the representativeness of the sample is ensured to be more real-time and accurate, and the danger of manual on-site sampling is avoided. The online analysis technology is realized.
2) Gas phase coloration of oxides in liquefied hydrocarbon feedstocksThe spectrum-hydrogen flame detector analysis method can meet the requirement of 0.10ml/m through the optimized development of instruments and methods3Compared with the existing analysis method and analysis technology, the oxide monitoring and analysis method has lower detection limit of the oxide, and can meet the requirement of a new generation of polyolefin catalyst on the content of the liquefied hydrocarbon raw material impurities. The sensitivity of the analysis technique is improved.
3) And a gas chromatography-hydrogen flame detector qualitative and quantitative analysis software is developed to integrate the automatic data processing and correcting functions. The full-automatic real-time monitoring is realized by sample introduction, analysis, data processing and result correction of the liquefied hydrocarbon raw material sample. Compared with the prior art that the off-line sample is manually injected and then the gas chromatography-mass spectrometer analysis software and the manual data processing and correction are operated, the method has the advantages of real-time, rapidness, accuracy and no influence of human factors. The intellectualization of the analysis technology is realized.
4) The development result data remote software can realize automatic acquisition and remote communication transmission of the analysis result of the gas chromatography-hydrogen flame detector. The automated transmission display of the analysis results of the liquefied hydrocarbon feedstock sample can be accomplished with a central control room or analysis center of the production facility. Compared with the manual transmission of the experimental results of the existing analysis technology, the method can achieve higher monitoring efficiency, and meanwhile, the method is ready for the whole-process automatic treatment of monitoring the production control from the raw materials. The rapid real-time response of the analysis technology is realized.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention and not to limit the invention. In the drawings, there is shown in the drawings,
FIG. 1 is a flow chart of a method for on-line monitoring and data processing of oxides in accordance with one embodiment of the present invention;
FIG. 2 is a schematic structural diagram of an on-line detection system according to an embodiment of the present invention, in which 2-a is a front view and 2-b is a side view;
FIG. 3 is a flow chart of an analysis process of an online monitoring system according to an embodiment of the present invention;
FIG. 4 is a data communication structure diagram for on-line monitoring of oxides in a liquefied hydrocarbon feedstock in accordance with an embodiment of the present invention;
FIG. 5 is a calibration curve for quantitative analysis of oxides according to an embodiment of the present invention.
Description of reference numerals: 1. a main box body; 2. a sample interface unit; 3. a standard gas/carrier gas interface unit; 4. an electrical/communication interface unit; 5. an explosion-proof processing unit; 6. a gas chromatograph; 7. a computer data processing system; 8. a temperature and pressure display meter; 9. and (5) emptying the valve box.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention easier to understand, the present invention will be described in further detail below with reference to the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other. The specific experimental methods not mentioned in the following examples are generally carried out according to conventional experimental methods.
In a preferred embodiment of the present invention, the shape of the main casing 1 is not particularly limited. In this embodiment, the main box 1 is preferably a rectangular parallelepiped, and the size range is not more than 200cm in height, 150cm in length, and 100cm in width. In a specific embodiment, universal wheels with a self-locking function are arranged between the movable main box body 1 and the ground, and the number of the universal wheels with the self-locking function is preferably 4, and the universal wheels are respectively located at four corners of the ground of the main box body 1.
According to a preferred embodiment of the invention, the hydrogen flame detector (FID) is a mass-type detector, which uses the flame generated by the combustion of hydrogen and air as energy source, and when organic compounds enter the flame generated by the combustion of hydrogen and oxygen, chemical ionization is generated at high temperature, and ions higher than the base flow by several orders of magnitude are generated by ionization, and under the directional action of high-voltage electric field, ion flow is formed and the ion flow is weak (10)-12-10-8A) Passing through high impedance (10)6～1011Omega) to the amount of organic compounds entering the flameProportional electrical signals, so that the organic matter can be quantitatively analyzed according to the magnitude of the signals. FID is characterized by high sensitivity, about 1000 times higher than that of Thermal Conductivity Detector (TCD); the detection limit is low and can reach 10-12 g/s; the linear range is wide and can reach 107(ii) a The FID has a simple structure, the dead volume is generally less than 1uL, the response time is only 1ms, and the FID can be used with a packed column or a capillary column directly; FID is responsive to organic compounds that can be ionized by combustion in a flame and can be directly analyzed quantitatively.
In accordance with one embodiment of the present invention, an on-line monitoring system for oxygen impurities in a liquefied hydrocarbon feedstock comprises: a movable main box body 1; the online detection unit is arranged in the main box body 1 and comprises a gas chromatograph 6 provided with a hydrogen flame detector and a computer data processing system 7, and the computer data processing system 7 is used for processing a detection result to obtain oxide detection data; the anti-explosion processing unit 5 is used for providing inert gas into the movable main box body 1, the anti-explosion processing unit 5 can be externally connected to the side wall of the movable main box body 1, can also be arranged in the movable main box body 1, is preferably arranged in the movable main box body 1, the inlet of the anti-explosion processing unit is connected with an inert gas source, and the outlet of the anti-explosion processing unit is communicated with the movable main box body 1 and is used for conveying the inert gas into the movable main box body 1; and a sample interface unit 2 connected with the on-line detection unit, wherein a raw material inlet of the sample interface unit is connected with a liquefied hydrocarbon raw material side line interface and is used for providing an on-line sample; the sample interface unit 2 can be arranged outside the movable main box body 1, can be externally connected to the side wall of the movable main box body 1, and is preferably externally connected to the side wall of the movable main box body 1, and the sample interface unit 2 preferably comprises a filtering device connected with a liquefied hydrocarbon raw material side line interface and used for filtering liquefied hydrocarbon raw materials from the liquefied hydrocarbon raw material side line interface; the sample interface unit 2 further comprises a pressure-reducing constant-pressure device, one end of the pressure-reducing constant-pressure device is connected with the filtering device, and the other end of the pressure-reducing constant-pressure device is connected with a sample inlet of the gas chromatograph and is used for gasifying the liquefied hydrocarbon raw material after filtering treatment, preferably carrying out flash evaporation gasification so as to obtain an online sample; and a standard gas/carrier gas interface unit externally connected to the side wall of the movable main box body 1, wherein the inlet of the standard gas/carrier gas interface unit is connected with a carrier gas source, and the outlet of the standard gas/carrier gas interface unit is connected with the gas chromatograph 6 and is used for providing standard gas and/or carrier gas for the gas chromatograph 6; and an air-release valve box 9 externally connected to the side wall of the movable main box body 1, and provided with an internal atmosphere air-release valve of the main box body connected with the movable main box body 1 and a carrier gas raw material gas air-release valve connected with the gas chromatograph 6; the electrical appliance/communication interface unit 4 is externally connected to the side wall of the movable main box body 1, the electrical appliance/communication interface unit 4 comprises a communication interface, one end of the communication interface is connected with the computer data processing system 7, the other end of the communication interface is connected with the analysis unit, and the communication interface is used for transmitting oxide detection data of the computer data processing system 7 to the analysis unit; and an analysis unit configured to regulate the feed amount of the liquefied hydrocarbon feedstock and/or the catalyst based on the oxygenate detection data.
FIG. 1 is a flow chart of an online monitoring technique for oxides in a liquefied hydrocarbon feedstock and a data processing method according to a preferred embodiment of the present invention. The online monitoring method in the embodiment comprises the following steps: establishing an oxygen impurity online monitoring system in the liquefied hydrocarbon raw material; starting the system, and enabling the liquefied hydrocarbon raw material to enter the sample interface unit 2 through a liquefied hydrocarbon raw material side line interface for filtration and pressure reduction treatment, wherein the liquefied hydrocarbon raw material is firstly filtered through a filtering device to remove particulate matters in the liquefied hydrocarbon raw material; then the liquefied hydrocarbon is sent into a pressure reduction and constant pressure device, preferably a synchronous flash vaporizer for pressure reduction and flash vaporization treatment, and the liquefied hydrocarbon gasification raw material is obtained through gasification; meanwhile, the valve of the explosion-proof processing unit 5 is opened, inert gas is sent into the movable main box body 1, inert gas atmosphere is formed in the movable main box body 1, and an atmosphere emptying valve in the main box body in the emptying valve box 9 is opened to enable the inert gas to flow in the main box body. The inventor overcomes the defect that the prior art cannot detect the oxide in the liquefied hydrocarbon raw material on line by arranging the explosion-proof processing unit and the blow-down valve box to be used together with other devices. The valve of the carrier gas/standard gas interface box is opened, and the carrier gas and the standard gas are respectively sent to the gas chromatograph 6; the carrier gas first purges the gas chromatograph 6 before the liquefied hydrocarbon sample is vaporized by the sample interface unit 2; the liquefied hydrocarbon gasification raw material enters an injection port of a gas chromatograph 6 through an outlet of the sample interface unit 2, qualitative and quantitative detection is carried out on oxygen impurities in the liquefied hydrocarbon gasification raw material, and detection data are obtained through the computer data processing system 7; gas discharged from the gas chromatograph 6 is discharged through an emptying valve box 9; the electrical appliance/communication interface unit 4 comprises a communication interface and an electrical appliance interface, one end of the electrical appliance interface is connected with a power supply, the other end of the electrical appliance interface is respectively connected with the power supply interface of each instrument through a connecting wire and used for supplying power to each instrument, the detection data obtained by the computer data processing system 7 is transmitted to the analysis unit through the communication interface, and the analysis unit regulates and controls the feeding amount of the liquefied hydrocarbon raw material according to the detection data, so that the online real-time monitoring of oxides in the liquefied hydrocarbon raw material is realized.
In another preferred embodiment of the present invention, the online monitoring system may further include a control module, and each device of the online monitoring system is connected to the control module through a pipeline, and the control module controls the operation of each device.
Example 1
(1) Establishing an on-line monitoring system for oxygen impurities in a liquefied hydrocarbon raw material as shown in figures 2-3, wherein the on-line monitoring system specifically comprises: the system comprises a movable main box body 1, a sample interface unit 2, a standard gas/carrier gas interface unit 3, an electrical apparatus/communication interface unit 4, an explosion-proof processing unit 5, a gas chromatograph 6, a computer data processing system 7, a temperature and pressure display meter 8 and a blow-down valve box 9, wherein fig. 2 is a structural layout diagram of the on-line detection system in the embodiment. The sample inlet of the gas chromatograph 6 is connected with the outlet of the sample processing system and is used for detecting the liquefied hydrocarbon gasification raw material from the sample interface unit 2. One end of the computer data processing system 7 is connected with the gas chromatograph 6, and the other end is connected with the analysis unit through the communication interface, and is used for obtaining detection data according to the detection of the gas chromatograph 6 and transmitting the detection data to the analysis unit. The size of the main box 1 is 180cm × 140cm × 90 cm.
The sample interface unit 2 includes: the filtering device is connected with the raw material inlet and is used for receiving the liquefied hydrocarbon raw material from the liquefied hydrocarbon raw material side line interface and filtering the liquefied hydrocarbon raw material; the pressure reducing constant pressure device is used for receiving the liquefied hydrocarbon raw material from the filtering device and gasifying the liquefied hydrocarbon raw material to obtain a liquefied hydrocarbon gasified raw material; the pressure reduction and constant pressure device is connected with the sample inlet of the gas chromatograph 6 through the raw material outlet.
The marker/carrier gas interface unit 3 includes: and the carrier gas source is connected and used for analyzing carrier gas of the gas chromatography sample, and the carrier gas is helium. And a standard gas source is connected and used for qualitative and quantitative chromatographic analysis and correction, and the standard gas is a standard gas mixed with chlorohydrocarbon. An atmospheric exhaust valve and a carrier gas raw material gas exhaust valve in the main box body are arranged in the emptying valve. The inlet of the atmosphere exhaust valve in the main box body is communicated with the movable main box body 1, and the outlet of the atmosphere exhaust valve is connected with an outer pipeline for exhausting, so that gas in the movable main box body 1 is exhausted. And the inlet of the carrier gas raw material gas exhaust valve is communicated with the outlet of the gas chromatograph 6, and the outlet is connected with an outer pipeline for exhausting and is used for exhausting the gas of the gas chromatograph 6.
The electric appliance/communication interface unit 4 includes: one end of the electrical appliance interface is connected with a power supply, and the other end of the electrical appliance interface is respectively connected with the power supply interface of each instrument through a connecting wire and used for supplying power to each instrument. One end of the communication interface is connected with the movable main box body 1, and the other end of the communication interface is connected with the analysis unit and used for transmitting the obtained detection data to the analysis unit.
The explosion-proof processing unit 5 includes: and the outlet of the movable main box body 1 is communicated with an inert gas source and is used for conveying inert gas into the movable main box body 1, so that an inert gas atmosphere is formed in the movable main box body 1, and the movable main box body is explosion-proof. The inert gas in the explosion-proof processing unit 5 is nitrogen, and the pressure is 0.6 MPa.
(2) Starting the system, so that the liquefied hydrocarbon raw material enters the sample interface unit 2 through a liquefied hydrocarbon raw material side line interface, and is subjected to filtering and reduced pressure flash evaporation treatment to form liquefied hydrocarbon gasification raw material; meanwhile, a valve of the explosion-proof processing unit 5 is opened, nitrogen is sent into the movable main box body 1, nitrogen atmosphere is formed in the movable main box body 1, and an atmosphere emptying valve in the main box body in the emptying valve box 9 is opened to enable the nitrogen to flow in the main box body; a valve of the carrier gas interface box is opened, and carrier gas is sent to the gas chromatograph 6; the carrier gas first purges the gas chromatograph 6 before the liquefied hydrocarbon sample is vaporized via the sample interface unit 2.
(3) The liquefied hydrocarbon gasification raw material enters a gas chromatograph 6 from the outlet of the sample interface unit 2, qualitative and quantitative detection is carried out on the oxygen impurities in the liquefied hydrocarbon gasification raw material, and the detection data is subjected to qualitative and quantitative analysis results through the computer data processing system 7. Chromatographic analysis conditions: WCOT type capillary column with polyethylene glycol as stationary phase; the column length is 10 m; inner diameter 0.53 mm; column temperature: the initial temperature is 40 ℃, the temperature is kept for 6 minutes, the temperature is increased to 90 ℃ at the speed of 5 ℃/min, then the temperature is increased to 180 ℃ at the speed of 10 ℃/min, the temperature is kept for 5 minutes, the temperature of a sample inlet is 250 ℃, the volume is quantitatively changed to 1ml, and the carrier gas: helium 5.0ml/min constant flow mode, split ratio 10: 1. Qualitative analysis conditions: and the hydrogen flame detector adopts the signal-to-noise ratio to perform oxide qualitative peak identification, and the signal-to-noise ratio is set to be 5: 1. Quantitative analysis conditions: the hydrogen flame detector selected by the embodiment has the advantage of selective response to the oxide, and the oxide mixed standard gas is selected as the standard substance of the oxide quantitative external standard correction curve. And (3) obtaining a corresponding correction curve equation of each substance of the oxide according to the response value of the oxide standard gas on the gas chromatography-hydrogen flame detector, and referring to table 1, wherein the linear correlation coefficient of the measured oxide correction curve is greater than 0.999. The oxide response value detected after the tested liquefied hydrocarbon raw material sample enters the gas chromatograph 6 and the hydrogen flame detector obtains the accurate content of the oxide in the sample according to an external standard correction curve, and concretely, the content is shown in fig. 5.
(4) The detection data is transmitted to the analysis unit through the communication interface, the data communication method for online monitoring of the oxide in the liquefied hydrocarbon raw material shown in fig. 4 comprises data acquisition, data processing, data conversion and communication protocol loading, the data is transmitted to the analysis unit through a standard MODBUS protocol, and the analysis unit regulates and controls the feeding amount of the liquefied hydrocarbon raw material according to the detection data; table 1 process parameters are propylene gas phase loop polymerization operating conditions.
TABLE 1 operating conditions for the gas-phase loop polymerization of propylene
Any numerical value mentioned in this specification, if there is only a two unit interval between any lowest value and any highest value, includes all values from the lowest value to the highest value incremented by one unit at a time. For example, if it is stated that the amount of a component, or a value of a process variable such as temperature, time, etc., is 50 to 90, it is meant in this specification that values of 51 to 89, 52 to 88 … …, and 69 to 71, and 70 to 71, etc., are specifically enumerated. For non-integer values, units of 0.1, 0.01, 0.001, or 0.0001 may be considered as appropriate. These are only some specifically named examples. In a similar manner, all possible combinations of numerical values between the lowest value and the highest value enumerated are to be considered to be disclosed in this application.
It should be noted that the above-mentioned embodiments are only for explaining the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to exemplary embodiments, but the words which have been used herein are words of description and illustration, rather than words of limitation. The invention can be modified, as prescribed, within the scope of the claims and without departing from the scope and spirit of the invention. Although the invention has been described herein with reference to particular means, materials and embodiments, the invention is not intended to be limited to the particulars disclosed herein, but rather extends to all other methods and applications having the same functionality.
Claims (10)
1. An on-line oxygen impurity monitoring system comprising:
a main box body, preferably a movable main box body;
an explosion-proof processing unit for providing inert gas into the main box body;
the online detection unit is arranged in the main box body and comprises a gas chromatograph provided with a hydrogen flame detector and a computer data processing system connected with the gas chromatograph, and the computer data processing system is used for processing a detection result of the gas chromatograph to obtain oxide detection data; and
and the sample interface unit is connected with the online detection unit, preferably adopts a multi-channel switching synchronous gasification system and is used for providing an online sample for the online monitoring unit.
2. The on-line monitoring system of claim 1 or 2, further comprising an analysis unit configured to regulate the feed amount of liquefied hydrocarbon feedstock and/or catalyst based on the oxygenate detection data; and/or the on-line monitoring system also comprises an electrical appliance/communication interface unit, wherein the electrical appliance/communication interface unit comprises an electrical appliance interface and a communication interface, one end of the electrical appliance interface is connected with a power supply, and the other end of the electrical appliance interface is respectively connected with the power supply interface of each instrument through a connecting wire and is used for supplying power to each instrument; one end of the communication interface is connected with the computer data processing system, the other end of the communication interface is connected with the analysis unit, and the communication interface is used for transmitting the oxide detection data of the computer data processing system to the analysis unit; and/or the on-line monitoring system further comprises a standard gas/carrier gas interface unit connected with the gas chromatograph, and the standard gas/carrier gas interface unit is used for providing standard gas and/or carrier gas for the gas chromatograph; and/or the online monitoring system further comprises a main box internal atmosphere exhaust valve connected with the main box and a carrier gas raw material gas exhaust valve connected with the gas chromatograph, preferably, the online monitoring system further comprises a gas discharge valve box, and the main box internal atmosphere exhaust valve and the carrier gas raw material gas exhaust valve are arranged in the gas discharge valve box; and/or the online monitoring system further comprises a control module, preferably, each device of the online monitoring system is connected with the control module through a pipeline, and the operation of each device is controlled through the control module.
3. The on-line monitoring system of claim 1 or 2, wherein the sample interface unit comprises a filtering device connected with the liquefied hydrocarbon feedstock side-line interface for filtering the liquefied hydrocarbon feedstock from the liquefied hydrocarbon feedstock side-line interface; preferably, the sample interface unit further comprises a pressure-reducing constant-pressure device, one end of the pressure-reducing constant-pressure device is connected with the filtering device, the other end of the pressure-reducing constant-pressure device is connected with the sample inlet of the gas chromatograph, and the pressure-reducing constant-pressure device is used for gasifying the liquefied hydrocarbon raw material after filtering treatment, preferably performing flash evaporation gasification to obtain an online sample.
4. The on-line monitoring system of any one of claims 1-3, wherein an inlet of the explosion-proof processing unit is connected with an inert gas source, and an outlet is connected with the main box body; wherein the pressure of the inert gas in the explosion-proof processing unit is 0.4-1.0MPa, preferably, the pressure is 0.4-0.8MPa, and further preferably, the pressure is 0.5-0.8 MPa.
5. The on-line monitoring system of any of claims 1-4, wherein the hydrogen flame detector comprises a power source coupled to the gas chromatograph; an ion chamber; flame, nozzle, insulator connected with inlet and outlet of carrier gas; a collector and an emitter coupled to the ion chamber.
6. The on-line monitoring system of any one of claims 1-5, wherein the gas chromatograph uses a WCOT capillary column using polyethylene glycol as a stationary phase and/or a PLOT capillary column using bonded silica gel as a stationary phase; the column length is 10-80m, preferably 10-60 m; the internal diameter is 0.22 to 0.59mm, preferably 0.25 to 0.52 mm.
7. A method for on-line monitoring oxygen impurities in a liquefied hydrocarbon feedstock by an on-line monitoring system according to any one of claims 1 to 6, comprising the steps of:
establishing the online monitoring system;
starting the on-line monitoring system to enable the liquefied hydrocarbon raw material to enter the on-line monitoring system through a liquefied hydrocarbon raw material side line interface, and detecting oxygen impurities in the liquefied hydrocarbon raw material to obtain oxide detection data;
and regulating the feeding amount of the liquefied hydrocarbon raw material and/or the catalyst according to the detection data.
8. The on-line monitoring method according to claim 7, comprising the steps of:
starting an on-line monitoring system, enabling the liquefied hydrocarbon raw material to enter the sample interface unit through a liquefied hydrocarbon raw material side line interface, sequentially carrying out filtration and pressure reduction treatment, preferably carrying out pressure reduction flash evaporation and gasification to obtain liquefied hydrocarbon gasified raw material, and further preferably carrying out pressure reduction flash evaporation in a synchronous flash evaporation vaporizer; meanwhile, a valve of a system purge gas box of the explosion-proof processing unit is opened, inert gas is sent into the main box body, inert gas atmosphere is formed in the main box body, and an atmosphere emptying valve in the main box body is opened to enable the inert gas to flow in the main box body; a valve of a carrier gas interface box of the standard gas/carrier gas interface unit is opened, and carrier gas is sent to a gas chromatograph; the carrier gas purges the gas chromatograph; the liquefied hydrocarbon sample is gasified by the sample interface unit to obtain liquefied hydrocarbon gasification raw material, the liquefied hydrocarbon gasification raw material enters the gas chromatograph through the outlet of the sample interface unit so as to carry out qualitative and/or quantitative detection on oxygen impurities in the liquefied hydrocarbon gasification raw material, and the liquefied hydrocarbon gasification raw material is analyzed and processed by the computer data processing system to obtain oxide detection data;
and the oxide detection data obtained by the processing of the computer data processing system is transmitted to the analysis unit through a communication interface, and the analysis unit regulates and controls the feeding amount of the liquefied hydrocarbon raw material and/or the catalyst according to the detection data.
9. The on-line monitoring method according to claim 7 or the above, wherein the standard gas is an oxide mixed standard gas;
and/or the inert gas and the carrier gas are respectively and independently selected from one or more of nitrogen, helium, hydrogen and air, the inert gas is preferably nitrogen, and the carrier gas is preferably helium; and/or the tail gas of the gas chromatograph is nitrogen; and/or the analysis conditions of the gas chromatograph comprise: column temperature: the initial temperature is-30-60 ℃, the maximum temperature is 100-; the carrier gas flow rate is 1.0-11.0ml/min, the constant flow mode is adopted, and the tail blowing gas flow rate is 1.0-30.0 ml/min; the temperature of the hydrogen flame detector is 150-: the initial temperature is 10-50 ℃, the temperature is kept for 1-10min, the temperature is raised to 60-200 ℃ at the speed of 2-20 ℃/min, the temperature is raised to 250 ℃ at the speed of 150 ℃ at the speed of 2-20 ℃/min, the temperature is kept for 1-10min, the split ratio is 1-10:1, the flow rate of carrier gas is 1.0-10.0ml/min, the constant flow mode is adopted, the flow rate of tail blowing gas is 2.0-20.0ml/min, the temperature of the hydrogen flame detector is 150 ℃ and 250 ℃, and the sample injection amount is 0.1-5 ml; and/or the oxygen impurities comprise volatile organic oxides, preferably the oxygen impurities comprise one or more of methanol, ethanol, n-propanol, isopropanol, tert-butanol, sec-butanol, n-butanol, dimethyl ether, diethyl ether, MTBE, ETBE, TAME, isopropyl ether, n-propyl ether, acetaldehyde, n-propionaldehyde, n-butyraldehyde, isobutyraldehyde, n-valeraldehyde, acetone, butanone; and/or the hydrogen flame detector adopts a signal-to-noise ratio as an oxide qualitative analysis condition, preferably, the signal-to-noise ratio adopts 2-10:1 as an oxide qualitative peak identification condition, and further preferably, the signal-to-noise ratio adopts 3-10:1 as an oxide qualitative peak identification condition; and/or quantitatively analyzing the oxygen impurities in the liquefied hydrocarbon raw material, drawing an external standard correction curve by taking different oxide standard gases as standard substances, and quantitatively correcting the oxides to obtain the accurate content of the oxygen impurities; and/or the analysis unit regulates the feed of liquefied hydrocarbon feedstock and/or catalyst based on the oxygenate detection data, preferably,
when the content of the oxygen impurities is less than 0.10ml/m3In the process, the liquefied hydrocarbon raw material and the catalyst are mixed according to a normal proportion;
when the content of the oxygen impurities is between 0.10 and 5.0ml/m3When the method is used, the amount of the catalyst is increased by 20-80% under the condition of not changing the sample amount of the liquefied hydrocarbon raw material to be mixed with the liquefied hydrocarbon raw material;
when the content of the oxygen impurities is more than 5.0ml/m3At that time, the liquefied hydrocarbon feedstock feed is stopped.
10. Use of an on-line monitoring system according to any one of claims 1 to 6 or an on-line monitoring method according to any one of claims 7 to 9 in the production of an olefin polymerization; preferably in the production of ethylene polymerization, propylene polymerization or butene polymerization.
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