CN111103377A - Soil volatile organic compounds flame ion detecting system - Google Patents
Soil volatile organic compounds flame ion detecting system Download PDFInfo
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- CN111103377A CN111103377A CN201911141326.5A CN201911141326A CN111103377A CN 111103377 A CN111103377 A CN 111103377A CN 201911141326 A CN201911141326 A CN 201911141326A CN 111103377 A CN111103377 A CN 111103377A
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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
- G01N30/62—Detectors specially adapted therefor
- G01N30/64—Electrical detectors
- G01N30/68—Flame ionisation detectors
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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
- G01N30/04—Preparation or injection of sample to be analysed
- G01N30/06—Preparation
- G01N30/08—Preparation using an enricher
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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
- G01N30/26—Conditioning of the fluid carrier; Flow patterns
- G01N30/28—Control of physical parameters of the fluid carrier
- G01N30/30—Control of physical parameters of the fluid carrier of temperature
Abstract
The invention discloses a flame ion detection system for soil volatile organic compounds, which comprises: the automatic pretreatment module is used for carrying out solid-gas separation and headspace sample injection treatment on a soil sample to obtain gas to be detected; the meteorological chromatographic detection module is connected with the automatic pretreatment module and is used for enriching, heating and detecting the gas to be detected to obtain a content spectrum of volatile organic compounds; the upper computer is connected with the meteorological chromatography detection module and used for determining the type and the concentration of the volatile organic compounds according to the content spectrum of the volatile organic compounds and displaying the content spectrum, the type and the concentration of the volatile organic compounds; the detection system disclosed by the invention is high in detection speed and simple to operate.
Description
Technical Field
The invention relates to the technical field of organic matter detection, in particular to a flame ion detection system for a soil volatile organic matter.
Background
The composition of Volatile Organic Compounds (VOCs) in soil is very complex, the content is also in the ppt-ppb level, and the analysis and detection are mainly divided into three parts, namely sample pretreatment, pretreatment and sample instrument analysis and detection.
The pretreatment of soil samples mostly adopts solid phase microextraction, solvent extraction, resin adsorption and the like. The solid phase microextraction method has the disadvantages of short service life of the extraction head, high cost and strict analysis condition requirements. The solvent extraction method and the resin adsorption method consume a large amount of organic solvents, have multiple operation steps, are easy to cause the loss of analyzed substances, are not suitable for detecting strong volatile organic compounds, and are not beneficial to quick detection.
Because the content of volatile organic compounds in the soil is low, the detection of the volatile organic compounds by using the existing instrument is extremely difficult; therefore, a suitable sample pretreatment method is required to enrich and concentrate a sample to be measured and to exclude interference of a complex matrix. At present, the main pretreatment technologies of VOCs include low-temperature direct enrichment and solution absorption. Low-temperature direct enrichment, low enrichment temperature, more consumed refrigerant, complex device, unsuitability for field online analysis, low suitable gas sampling amount and limitation on detection sensitivity. The solution absorption method has the disadvantages of solvent consumption, toxicity, possibility of influencing sample analysis by solvent peaks, and complex and time-consuming operation.
At present, the most widely applied VOCs determination method is headspace-gas chromatography, but the method has the disadvantages of complex operation, long detection time, and large power consumption and gas consumption.
Disclosure of Invention
The invention aims to provide a soil volatile organic compound flame ion detection system to realize measurement of the types and concentrations of soil volatile organic compounds.
In order to achieve the above object, the present invention provides a system for detecting flame ions of soil volatile organic compounds, the system comprising:
the automatic pretreatment module is used for carrying out solid-gas separation and headspace sample injection treatment on a soil sample to obtain gas to be detected;
the meteorological chromatographic detection module is connected with the automatic pretreatment module and is used for enriching, heating and detecting the gas to be detected to obtain a content spectrum of volatile organic compounds;
the upper computer is connected with the meteorological chromatography detection module and used for determining the type and the concentration of the volatile organic compounds according to the content spectrum of the volatile organic compounds and displaying the content spectrum, the type and the concentration of the volatile organic compounds;
the gas source module is respectively connected with the automatic pretreatment module and the meteorological chromatographic detection module and is used for providing carrier gas for the automatic pretreatment module and providing combustion gas and combustion-supporting gas for the meteorological chromatographic detection module;
and the microcontroller is respectively connected with the upper computer and the meteorological chromatography detection module and is used for utilizing the combustion gas and the combustion-supporting gas to support combustion of the meteorological chromatography detection module according to the instruction of the upper computer.
Optionally, the automatic preprocessing module includes:
the sample bottle is used for containing a soil sample and is also used for the circulation of the carrier gas;
the oscillation device is arranged corresponding to the sample bottle and is used for oscillating the soil sample in the sample bottle so as to separate solid from gas to be detected and solid from gas;
the headspace heating device is arranged corresponding to the sample bottle, is connected with the oscillating device and is used for heating the headspace of the sample to a constant temperature range; and after the gas to be detected in the soil sample volatilizes for a set time, inserting the sample injection needles at the two ends of the headspace heating device into the sample bottle, switching the circulation of the carrier gas, and taking the gas to be detected into the gas chromatography detection module by using the carrier gas.
Optionally, the gas chromatography detection module includes:
an enrichment-analysis device, a chromatographic separation device, a flame ion detection device and a signal processing device;
the enrichment-analysis device is connected with the automatic pretreatment module and is used for receiving the gas to be detected brought by the carrier gas and carrying out adsorption enrichment and temperature rise analysis on the volatile organic compounds in the gas to be detected;
the chromatographic separation device is connected with the enrichment-analysis device and used for receiving the volatile organic compounds after temperature rise analysis and separating the volatile organic compounds after temperature rise analysis; after temperature rise and analysis, the volatile organic compounds are carried into the chromatographic separation device by utilizing the carrier gas;
the flame ion detection device is respectively connected with the chromatographic separation device, the gas source module and the microcontroller and is used for supporting combustion by utilizing the combustion gas and the combustion-supporting gas according to an instruction sent by the microcontroller and converting the separated volatile organic compounds into electric signals;
and the signal processing device is respectively connected with the flame ion detection device and the upper computer, and is used for generating a content spectrum of the volatile organic compounds according to the electric signals and sending the content spectrum to the upper computer.
Optionally, the enrichment-resolution module includes:
the enrichment pipe is connected with the automatic pretreatment module and is used for receiving the gas to be detected brought by the carrier gas and adsorbing and enriching the volatile organic compounds in the gas to be detected;
the semiconductor refrigerating piece is arranged corresponding to the enrichment pipe and used for refrigerating the enrichment pipe to a first temperature set value so as to adsorb and enrich the volatile organic compounds in the gas to be detected;
the first heating wire is wound on the outer side of the enrichment pipe and used for heating the enrichment pipe to a second temperature set value so as to analyze the volatile organic compounds in the gas to be detected;
the first thermometer is used for collecting the temperature of the enrichment pipe;
the enrichment analysis temperature controller is respectively connected with the microcontroller, the first thermometer, the first heating wire and the semiconductor refrigerating sheet and is used for sending the collected temperature of the enrichment pipe to the upper computer through the microcontroller so that the upper computer generates a control instruction according to the collected temperature of the enrichment pipe; the semiconductor refrigeration piece is controlled to refrigerate to a first temperature set value according to an instruction sent by the microcontroller or the first heating wire is controlled to heat to a second temperature set value according to an instruction generated by the microcontroller.
Optionally, the chromatographic separation module comprises:
the flow valve group is respectively connected with the enrichment pipe and the microcontroller and is used for starting sample injection according to an instruction sent by the microcontroller;
and the chromatographic column unit is connected with the flow valve group and used for separating the volatile organic compounds.
Optionally, the chromatography column unit comprises: the device comprises an aluminum cylinder, a copper foil adhesive tape layer, a heating layer, a heat preservation layer and a second temperature sensor; the heat preservation layer, the heating layer, the aluminum cylinder, the heating layer and the heat preservation layer are arranged from inside to outside in sequence; the chromatographic column layer and the second heating wire are wound to form the heating layer.
Optionally, the flow valve set includes:
a first six-way valve and a second six-way valve;
the third end of the first six-way valve is connected with one end of the enrichment-analysis module, the sixth end of the first six-way valve is connected with the other end of the enrichment-analysis module, the second end of the first six-way valve is connected with the chromatographic column unit, the first end of the first six-way valve is connected with the gas source module, the fourth end of the first six-way valve is connected with the first end of the second six-way valve, the fifth end of the first six-way valve is connected with the fourth end of the second six-way valve, the second end of the second six-way valve is connected with the gas source module, and the third end of the second six-way valve is connected with the gas source module.
Optionally, the chromatographic separation module further comprises:
the fan is used for fixing the chromatographic column unit on the fan and accelerating the air flow;
the heating power supply is connected with the second heating wire and used for supplying electric energy to the second heating wire;
the second temperature sensor is arranged on the chromatographic column layer and used for detecting the temperature of the chromatographic column layer;
and the chromatographic temperature controller is connected with the second temperature sensor and is used for controlling the heating power supply to supply electric energy to the second heating wire according to the temperature of the chromatographic column layer.
Optionally, the detection system further includes:
and the flame ion detection device, the first six-way valve and the second six-way valve are arranged in the pipeline temperature control box.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention discloses a flame ion detection system for soil volatile organic compounds, which comprises: the automatic pretreatment module is used for carrying out solid-gas separation and headspace sample injection treatment on a soil sample to obtain gas to be detected; the meteorological chromatographic detection module is connected with the automatic pretreatment module and is used for enriching, heating and detecting the gas to be detected to obtain a content spectrum of volatile organic compounds; the upper computer is connected with the meteorological chromatography detection module and used for determining the type and the concentration of the volatile organic compounds according to the content spectrum of the volatile organic compounds and displaying the content spectrum, the type and the concentration of the volatile organic compounds; the gas source module is respectively connected with the automatic pretreatment module and the meteorological chromatographic detection module and is used for providing carrier gas for the automatic pretreatment module and providing combustion gas and combustion-supporting gas for the meteorological chromatographic detection module; and the microcontroller is respectively connected with the upper computer and the meteorological chromatography detection module and is used for utilizing the combustion gas and the combustion-supporting gas to support combustion of the meteorological chromatography detection module according to the instruction of the upper computer so as to realize rapid detection and have simple operation.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
FIG. 1 is a schematic diagram of a system for detecting flame ions of volatile organic compounds in soil according to an embodiment of the present invention;
FIG. 2 is a mechanical structure diagram of a soil VOC flame ion detection system according to an embodiment of the present invention;
FIG. 3 is a diagram of the peripheral connections of a microcontroller according to an embodiment of the present invention;
FIG. 4 is a diagram showing a structure of an adsorption state according to an embodiment of the present invention;
FIG. 5 is a diagram illustrating a structure of an analysis state according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a sample injection structure of a chromatographic column according to an embodiment of the present invention;
fig. 7 is a schematic diagram of a display of an upper computer interface according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a soil volatile organic compound flame ion detection system to realize measurement of the types and concentrations of soil volatile organic compounds.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a structural diagram of a soil volatile organic compound flame ion detection system according to an embodiment of the present invention, and fig. 2 is a mechanical structural diagram of a soil volatile organic compound flame ion detection system according to an embodiment of the present invention, as shown in fig. 1-2, the present invention provides a soil volatile organic compound flame ion detection system, the detection system includes:
the automatic pretreatment module 2 is used for carrying out solid-gas separation and headspace sample injection treatment on a soil sample to obtain gas to be detected;
the meteorological chromatographic detection module 3 is connected with the automatic pretreatment module 2 and is used for carrying out enrichment, heating and detection treatment on the gas to be detected to obtain a content spectrum of volatile organic compounds;
the upper computer 1 is connected with the gas chromatography detection module 3 and is used for determining the type and the concentration of the volatile organic compounds according to the content spectrum of the volatile organic compounds and displaying the content spectrum, the type and the concentration of the volatile organic compounds;
the gas source module 4 is respectively connected with the automatic pretreatment module 2 and the meteorological chromatographic detection module 3 and is used for providing carrier gas for the automatic pretreatment module 2 and providing combustion gas and combustion-supporting gas for the meteorological chromatographic detection module 3;
and the microcontroller is respectively connected with the upper computer 1 and the meteorological chromatography detection module 3 and is used for utilizing the combustion gas and the combustion-supporting gas to support combustion of the meteorological chromatography detection module 3 according to the instruction of the upper computer 1.
As an embodiment, the upper computer 1 according to the present invention performs spectral line processing by using a polynomial fitting moving smoothing algorithm, that is, m points (2 m +1 points in total) are respectively located on both sides of any point on a spectral line, a spectral line centered on the m points performs least square fitting on the spectral line, and a spectral value of the obtained polynomial at the m points is the concentration of the volatile organic compound.
As an embodiment, the automated preprocessing module 2 of the present invention includes:
the sample bottle is used for containing a soil sample and is also used for the circulation of the carrier gas; the sample bottle adopts a cylindrical structure, and two ends of the sample bottle are provided with double-side diaphragms, namely a double-opening sampling bottle. The inner layer is a gas filtering membrane, and the outer layer is a sealing protective film. The sample bottle body is made of silicon boride glass, the bottle caps at two ends are made of polytetrafluoroethylene, the bottle cap body structure is provided with two layers of isolation, the inner layer is a glass fiber filter membrane and can allow substances separated from a sample to pass through, and the outer layer is provided with a polytetrafluoroethylene membrane which can be used for sealing a special sample bottle and can also enable the thimble to be pushed into the special sample bottle easily. A preset distance is reserved between the two layers of membranes, so that the thimble can not break the inner layer membrane, and a sample is prevented from entering the thimble.
The oscillation device 21 is arranged corresponding to the sample bottle and is used for oscillating the soil sample in the sample bottle so as to separate solid from gas to be detected and solid from gas;
the headspace heating device 22 is arranged corresponding to the sample bottle, is connected with the oscillating device 21 and is used for heating the headspace of the sample to a constant temperature range; after the gas to be detected in the soil sample volatilizes for a set time, inserting the sample injection needles at the two ends of the headspace heating device 22 into the sample bottle, switching the circulation of the carrier gas, and taking the gas to be detected into the gas chromatography detection module 3 by using the carrier gas. The constant temperature range is (50-80) DEG C.
The sample bottle is subjected to constant temperature heating at 50-80 ℃ and oscillation treatment, and the purpose is to accelerate volatilization of volatile organic compounds in the sample.
In one embodiment, the gas chromatography detection module 3 of the present invention includes:
an enrichment-analysis device 31, a chromatographic separation device 32, a flame ion detection device 33, and a signal processing device 34;
the enrichment-analysis device 31 is connected with the automatic pretreatment module 2, and is configured to receive the gas to be detected brought by the carrier gas, and perform adsorption enrichment and temperature rise analysis on the volatile organic compounds in the gas to be detected;
the chromatographic separation device 32 is connected with the enrichment-analysis device 31 and is used for receiving the volatile organic compounds after temperature rise analysis and separating the volatile organic compounds after temperature rise analysis; after the temperature rise analysis, the volatile organic compounds are carried into the chromatographic separation device 32 by using the carrier gas;
the flame ion detection device 33 is respectively connected with the chromatographic separation device 32, the gas source module 4 and the microcontroller, and is used for supporting combustion by using the combustion gas and the combustion-supporting gas according to an instruction sent by the microcontroller and converting the separated volatile organic compounds into electric signals;
and the signal processing device 34 is respectively connected with the flame ion detection device 33 and the upper computer 1, and is used for generating a content spectrum of the volatile organic compounds according to the electric signals and sending the content spectrum to the upper computer 1.
When the combustion gas and the combustion-supporting gas are used for supporting combustion, the flow rate of the combustion gas is 15-20 mL/min, the flow rate of the combustion gas and the combustion-supporting gas is 150-200 mL/min, and the ratio of the combustion gas to the combustion-supporting gas is 1: 10.
as an embodiment, the enrichment-resolution module of the present invention comprises:
the enrichment pipe is connected with the automatic pretreatment module 2 and is used for receiving the gas to be detected brought by the carrier gas and adsorbing and enriching the volatile organic compounds in the gas to be detected;
the semiconductor refrigerating piece is arranged corresponding to the enrichment pipe and used for refrigerating the enrichment pipe to a first temperature set value so as to adsorb and enrich the volatile organic compounds in the gas to be detected;
the first heating wire is wound on the outer side of the enrichment pipe and used for heating the enrichment pipe to a second temperature set value so as to analyze the volatile organic compounds in the gas to be detected;
the first thermometer is used for collecting the temperature of the enrichment pipe;
the enrichment analysis temperature controller is respectively connected with the microcontroller, the first thermometer, the first heating wire and the semiconductor refrigerating sheet and is used for sending the collected temperature of the enrichment pipe to the upper computer 1 through the microcontroller so that the upper computer 1 generates a control instruction according to the collected temperature of the enrichment pipe; the semiconductor refrigeration piece is controlled to refrigerate to a first temperature set value according to an instruction sent by the microcontroller or the first heating wire is controlled to heat to a second temperature set value according to an instruction generated by the microcontroller.
As an embodiment, the chromatographic separation module of the present invention comprises:
the flow valve group is respectively connected with the enrichment pipe and the microcontroller and is used for starting sample injection according to an instruction sent by the microcontroller;
and the chromatographic column unit is connected with the flow valve and used for separating the volatile organic compounds.
As an embodiment, the chromatography column unit of the present invention comprises: the device comprises an aluminum cylinder, a copper foil adhesive tape layer, a heating layer, a heat preservation layer and a second temperature sensor; the heat preservation layer, the heating layer, the aluminum cylinder, the heating layer and the heat preservation layer are arranged from inside to outside in sequence; the chromatographic column layer and the second heating wire are wound to form the heating layer. The invention coats the inner layer and the outer layer of the chromatographic column unit with heat insulating materials to reduce heat loss.
As an embodiment, the flow valve assembly of the present invention includes:
a first six-way valve and a second six-way valve; the sixth end of the first six-way valve is connected with the other end of the enrichment-desorption module, the second end of the first six-way valve is connected with the chromatographic column unit, the first end of the first six-way valve is connected with the gas source module 4, the fourth end of the first six-way valve is connected with the first end of the second six-way valve, the fifth end of the first six-way valve is connected with the fourth end of the second six-way valve, the second end of the second six-way valve is connected with the gas source module 4, and the third end of the second six-way valve is connected with the gas source module 4.
As an embodiment, the chromatographic separation module of the present invention further comprises:
the fan is used for fixing the chromatographic column unit on the fan and accelerating the air flow;
the heating power supply is connected with the second heating wire and used for supplying electric energy to the second heating wire;
the second temperature sensor is arranged on the chromatographic column layer and used for detecting the temperature of the chromatographic column layer;
and the chromatographic temperature controller is connected with the second temperature sensor and is used for controlling the heating power supply to supply electric energy to the second heating wire according to the temperature of the chromatographic column layer.
The chromatographic temperature controller adopts a program for heating, the heating speed is 20 ℃/min, the power consumption can be controlled within 200W, and the radial temperature unevenness of a chromatographic column unit is not more than 2 ℃.
As an embodiment, the detection system of the present invention further includes:
and the flame ion detection device 33, the first six-way valve and the second six-way valve are arranged in the pipeline temperature control box.
The pipeline temperature control box is isolated from the chromatographic column unit by the polytetrafluoroethylene gasket, so that the problem that the rapid cooling of the chromatographic column unit is not influenced by other devices in the pipeline temperature control box is solved.
The detection device of the present invention further comprises: the device comprises a first electronic flow controller, a second electronic flow controller, a third electronic flow controller, a fourth electronic flow controller, a fifth electronic flow controller and a sixth electronic flow controller, wherein the first electronic flow controller is used for controlling and detecting the flow of combustion-supporting gas, the second electronic flow controller is used for controlling and detecting the flow of combustion gas, the third electronic flow controller is used for controlling and detecting the flow of tail blowing gas, the fourth electronic flow controller is used for controlling and detecting the flow of back blowing gas, the fifth electronic flow controller is used for controlling and detecting the flow of carrier gas, and the sixth electronic flow controller is used for controlling and detecting.
As shown in fig. 3, in the present invention, the upper computer 1 is connected to the microcontroller through RS232 and RS485, and the first electronic flow controller, the second electronic flow controller, the third electronic flow controller, the fourth electronic flow controller, the fifth electronic flow controller, and the sixth electronic flow controller are connected to the microcontroller through RS 485.
As one embodiment, the gas source module 4 of the present invention includes a nitrogen cylinder, an air cylinder, a hydrogen cylinder, a sample cylinder, a standard gas cylinder, an air exhaust cylinder, a first solenoid valve V1, a second solenoid valve V2, a third solenoid valve V3, a fourth solenoid valve V4, a fifth solenoid valve V5 and a sixth solenoid valve V6.
As can be seen from fig. 4, 5 and 6, the air cylinders are respectively connected to one end of the fifth electromagnetic valve V5, one end of the sixth electromagnetic valve V6 and one end of a first electronic flow controller EFC1, the other end of the fifth electromagnetic valve V5 is connected to the pneumatic control port of a first six-way valve W1, the other end of the sixth electromagnetic valve V6 is connected to the pneumatic control port of a second six-way valve W2, the other end of the first electronic flow controller EFC1 is connected to one end of a flame ion detector, one end of the hydrogen cylinder is connected to one end of a second electronic flow controller EFC2, the other end of the second electronic flow controller EFC2 is connected to one end of the flame ion detector, the nitrogen cylinders are respectively connected to one end of the third electronic flow controller EFC3, one end of the fourth electronic flow controller EFC4 and one end of the fifth electronic flow controller 5, the other end of the third electronic flow controller c3 is connected to one end of the flame ion detector, the other end of the fourth electronic flow controller EFC4 is connected with one end of the first solenoid valve V1, the other end of the first solenoid valve V1 is connected with the third end of the second six-way valve W2, the other end of the fifth electronic flow controller EFC5 is connected with the first end of the first six-way valve W1, the sample bottle is connected with the second end of the second six-way valve W2, the target bottle is connected with one end of the third solenoid valve V3, the other end of the third solenoid valve is connected with the second end of the second six-way valve W2, the exhaust bottle is connected with one end of the fourth solenoid valve V4 and one end of the sixth electronic flow meter EFC6, the other end of the fourth solenoid valve V4 is connected with the second end of the second six-way valve W2, and the other end of the sixth electronic flow meter EFC6 is connected with the third end of the second six-way valve W2.
State a of the first six-way valve: the first end of the first six-way valve is connected with the second end of the first six-way valve, the third end of the first six-way valve is connected with the fourth end of the first six-way valve, and the fifth end of the first six-way valve is connected with the sixth end of the first six-way valve.
State B of the first six-way valve: the first end of the first six-way valve is connected with the sixth end of the first six-way valve, the second end of the first six-way valve is connected with the third end of the first six-way valve, and the fourth end of the first six-way valve is connected with the fifth end of the first six-way valve.
State a of the first six-way valve: the first end of the second six-way valve is connected with the second end of the second six-way valve, the third end of the second six-way valve is connected with the fourth end of the second six-way valve, and the fifth end of the second six-way valve is connected with the sixth end of the second six-way valve.
State B of the first six-way valve: the first end of the second six-way valve is connected with the sixth end of the second six-way valve, the second end of the second six-way valve is connected with the third end of the second six-way valve, and the fourth end of the second six-way valve is connected with the fifth end of the second six-way valve.
Fig. 4 is a structural diagram of an adsorption state of the embodiment of the invention, fig. 5 is a structural diagram of an analysis state of the embodiment of the invention, fig. 6 is a structural diagram of a sample injection structure of a chromatographic column of the embodiment of the invention, and as shown in fig. 4-6, the specific working process is as follows:
the system enters a standby stage after being started, at the moment, the microcontroller controls the first six-way valve W1 to be closed through the fifth electromagnetic valve V5, the microcontroller controls the second six-way valve W2 to be closed through the sixth electromagnetic valve V5, the microcontroller controls the first electromagnetic valve V1, the second electromagnetic valve V2, the third electromagnetic valve V3 and the fourth electromagnetic valve V4 to be all closed, the chromatographic temperature controller is in an uncontrolled temperature stage, and each flow controller is set at the last time.
Set up the menu alone, can carry out single setting to each minute part, to 1 chromatogram temperature controller, 6 flow controller EFC, automatic preprocessing module 2, microcontroller control flame ion FID detection device's ignition, temperature signal gathers and the SSR accuse temperature, refrigeration piece temperature signal gathers and the SSR accuse temperature, pipeline temperature signal gathers and the SSR accuse temperature, temperature signal gathers in the machine case, the temperature of analytic heating is gathered by analytic temperature controller in addition and is passed to microcontroller through RS485 transmission, microcontroller passes through the on-off time control analytic temperature of relay.
The process of measuring VOCs by a chromatograph:
1. a preparation state: setting air flow as 200ml/min, hydrogen flow as 20ml/min, carrier gas flow as 2-5ml/min, tail gas blowing flow as 10ml/min, back blowing flow as 100ml/min, and exhaust air flow as 50 ml/min; the temperature of the FID detector is set to 260 ℃, the temperature of the pipeline is set to 80 ℃, and the temperature of the chromatographic column unit is set to be 30 ℃ of the fixed temperature.
2. During sampling and enriching: taking the existing standard gas as an example, when the standard gas is used, the first six-way valve W1 and the second six-way valve W2 are all in the a state (that is, the fifth electromagnetic valve V5 and the sixth electromagnetic valve V6 are both closed), the first electromagnetic valve V1, the second electromagnetic valve V2, the third electromagnetic valve V3 and the fourth electromagnetic valve V4 are all closed, the upper computer 1 sends a command to turn on the refrigeration fan to the microcontroller, so that the enrichment-analysis device 31 is set to refrigeration control, when the adsorption refrigeration temperature is stabilized at the first temperature setting value of-10 ℃, the upper computer 1 sends a command to turn on the second electromagnetic valve V2 and the fourth electromagnetic valve V4 to the microcontroller, at this time, the enrichment pipe adsorbs and enriches the volatile organic compounds in the standard gas, and at the same time, the EPC flow controller at the emptying end records the sampling flow (timing the flow and the time), and the sampling enrichment time can be controlled through the interface setting.
3. During analysis: the upper computer 1 sends a command to the microcontroller to close the second electromagnetic valve V2 and the fourth electromagnetic valve V4, the upper computer 1 sends a command to close the semiconductor refrigerating sheet through the microcontroller, meanwhile, the upper computer 1 sends a command to close the refrigerating fan to the microcontroller, the second six-way valve W2 is switched from the A state to the B state, the microcontroller sends a command to open 24V to heat the first heating wire, the enrichment pipe is in the heating state, the 24V heating voltage is firstly used for heating the first heating wire for 10s (the time can be set), then the microcontroller sends a command to open 12V heating voltage to heat the first heating wire, and the enrichment pipe is in the 12V heating voltage heating state.
4. And (3) sample introduction: the upper computer 1 heats the first heating wire for 10s (time can be set) through the microcontroller and the enrichment analysis temperature controller, the first six-way valve W1 is switched to a B state instruction from an A state through the microcontroller, the sample injection state is realized at the moment, the sample injection time is kept for 10s (time can be set), the enrichment analysis temperature controller is started to be in a temperature programming mode (controlled according to linear temperature rising parameters set in advance) while sample injection is carried out, and the upper computer 1 sends the first six-way valve to the microcontroller after the sample injection time is finishedSwitching the state of the valve W1 from B to A, sending the Volatile Organic Compounds (VOCs) into the chromatographic column unit by the carrier gas, timing from the sample injection time, wherein the sample injection time is t0As the start time for chromatogram characterization.
5. During analysis: the first six-way valve W1 is in A state, the chromatographic column temperature controller is in a programmed temperature mode, and at the moment, the carrier gas sends the resolved volatile organic compounds VOCs components into the chromatographic column unit to realize the separation of the volatile organic compounds.
6. After the programmed temperature rise is completed, the system enters a data processing stage, so that the chromatographic column temperature controller T1 is at the temperature of the ready state, that is, the separated volatile organic compounds are converted into electric signals by using the combustion gas and the combustion-supporting gas to support combustion, and a content spectrum of the volatile organic compounds is generated according to the electric signals and is sent to the upper computer 1.
8. The back flushing process comprises the following steps: the first six-way valve W1 is in the A state, the upper computer 1 sends an instruction to the microcontroller to open the first electromagnetic valve V1 and the third electromagnetic valve V3, if the aging enrichment pipe is needed, the upper computer can send an analytic heating instruction of starting 24V heating voltage or sending an analytic heating instruction of starting 12V heating voltage to the microcontroller, so that the enrichment pipe is in the heating state to fully volatilize adsorbed gas, and attention is paid to the fact that the analytic heating time of the 24V heating voltage cannot be too long!
Fast cooling process of chromatographic column unit: the chromatographic column temperature controller T1 is in the non-temperature control state, and sends a chromatographic column fan opening instruction to the chromatographic column temperature controller T1 to turn on the fan.
The calibration process is similar to the measurement and analysis process, when certain gas of VOCs is calibrated, the amount of the standard gas absorbed by the enrichment tube is calculated according to the concentration of the introduced standard gas, the introduced flow and the introduced time, then the standard gas is subjected to thermal analysis, the standard gas enters the FID detector after being separated by the chromatographic column, and the calibration chromatogram is stored in a database for qualitative and quantitative measurement.
Fig. 7 is a schematic view of an interface display of an upper computer 1 according to an embodiment of the present invention, in which a flow rate of combustion-supporting gas detected by a first electronic flow controller, a flow rate of combustion gas detected by a second electronic flow controller, a flow rate of tail gas detected by a third electronic flow controller, a flow rate of back gas detected by a fourth electronic flow controller, a flow rate of carrier gas detected by a fifth electronic flow controller, and a flow rate of exhaust gas detected by a sixth electronic flow controller are sent to the upper computer 1 through the microcontroller for display. The nitrogen flow (i.e. the flow of the carrier gas) is the EPC-carrier gas in fig. 3, the air flow (i.e. the flow of the combustion-supporting gas) is the EFC-combustion-supporting gas in fig. 3, the hydrogen flow (i.e. the flow of the combustion-supporting gas) is the EFC-combustion-supporting gas in fig. 3, the flow of the tail-blown gas is the EFC-make-up gas flow in fig. 3, the flow of the back-blown gas is the EFC-back-blown gas in fig. 3, and the flow of the exhaust gas is the EFC-calculated flow.
The upper computer 1 is also used for displaying the temperature of the chromatographic column unit, the temperature of the flame ion detection device 33, the analytic heating temperature, the pipeline temperature control temperature, the adsorption refrigeration temperature and the case temperature; the system is also used for displaying the states of the electromagnetic valves and the six-way valves, and is also used for displaying the content spectrum, the type and the concentration of the volatile organic compounds, the current system state and the FID signal value.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (9)
1. A soil volatile organic compounds flame ion detection system, its characterized in that, detection system includes:
the automatic pretreatment module is used for carrying out solid-gas separation and headspace sample injection treatment on a soil sample to obtain gas to be detected;
the meteorological chromatographic detection module is connected with the automatic pretreatment module and is used for enriching, heating and detecting the gas to be detected to obtain a content spectrum of volatile organic compounds;
the upper computer is connected with the meteorological chromatography detection module and used for determining the type and the concentration of the volatile organic compounds according to the content spectrum of the volatile organic compounds and displaying the content spectrum, the type and the concentration of the volatile organic compounds;
the gas source module is respectively connected with the automatic pretreatment module and the meteorological chromatographic detection module and is used for providing carrier gas for the automatic pretreatment module and providing combustion gas and combustion-supporting gas for the meteorological chromatographic detection module;
and the microcontroller is respectively connected with the upper computer and the meteorological chromatography detection module and is used for utilizing the combustion gas and the combustion-supporting gas to support combustion of the meteorological chromatography detection module according to the instruction of the upper computer.
2. The soil volatile organic compounds flame ion detection system of claim 1, wherein the automated pre-processing module comprises:
the sample bottle is used for containing a soil sample and is also used for the circulation of the carrier gas;
the oscillation device is arranged corresponding to the sample bottle and is used for oscillating the soil sample in the sample bottle so as to separate solid from gas to be detected and solid from gas;
the headspace heating device is arranged corresponding to the sample bottle, is connected with the oscillating device and is used for heating the headspace of the sample to a constant temperature range; and after the gas to be detected in the soil sample volatilizes for a set time, inserting the sample injection needles at the two ends of the headspace heating device into the sample bottle, switching the circulation of the carrier gas, and taking the gas to be detected into the gas chromatography detection module by using the carrier gas.
3. The soil volatile organic compounds flame ion detection system of claim 1, wherein the gas chromatography detection module comprises:
an enrichment-analysis device, a chromatographic separation device, a flame ion detection device and a signal processing device;
the enrichment-analysis device is connected with the automatic pretreatment module and is used for receiving the gas to be detected brought by the carrier gas and carrying out adsorption enrichment and temperature rise analysis on the volatile organic compounds in the gas to be detected;
the chromatographic separation device is connected with the enrichment-analysis device and used for receiving the volatile organic compounds after temperature rise analysis and separating the volatile organic compounds after temperature rise analysis; after temperature rise and analysis, the volatile organic compounds are carried into the chromatographic separation device by utilizing the carrier gas;
the flame ion detection device is respectively connected with the chromatographic separation device, the gas source module and the microcontroller and is used for supporting combustion by utilizing the combustion gas and the combustion-supporting gas according to an instruction sent by the microcontroller and converting the separated volatile organic compounds into electric signals;
and the signal processing device is respectively connected with the flame ion detection device and the upper computer, and is used for generating a content spectrum of the volatile organic compounds according to the electric signals and sending the content spectrum to the upper computer.
4. The soil volatile organic compounds flame ion detection system of claim 3, wherein the enrichment-resolution module comprises:
the enrichment pipe is connected with the automatic pretreatment module and is used for receiving the gas to be detected brought by the carrier gas and adsorbing and enriching the volatile organic compounds in the gas to be detected;
the semiconductor refrigerating piece is arranged corresponding to the enrichment pipe and used for refrigerating the enrichment pipe to a first temperature set value so as to adsorb and enrich the volatile organic compounds in the gas to be detected;
the first heating wire is wound on the outer side of the enrichment pipe and used for heating the enrichment pipe to a second temperature set value so as to analyze the volatile organic compounds in the gas to be detected;
the first thermometer is used for collecting the temperature of the enrichment pipe;
the enrichment analysis temperature controller is respectively connected with the microcontroller, the first thermometer, the first heating wire and the semiconductor refrigerating sheet and is used for sending the collected temperature of the enrichment pipe to the upper computer through the microcontroller so that the upper computer generates a control instruction according to the collected temperature of the enrichment pipe; the semiconductor refrigeration piece is controlled to refrigerate to a first temperature set value according to an instruction sent by the microcontroller or the first heating wire is controlled to heat to a second temperature set value according to an instruction generated by the microcontroller.
5. The soil volatile organic compounds flame ion detection system of claim 4, wherein the chromatographic separation module comprises:
the flow valve group is respectively connected with the enrichment pipe and the microcontroller and is used for starting sample injection according to an instruction sent by the microcontroller;
and the chromatographic column unit is connected with the flow valve group and used for separating the volatile organic compounds.
6. The soil volatile organic flame ion detection system of claim 5, wherein the chromatography column unit comprises: the device comprises an aluminum cylinder, a copper foil adhesive tape layer, a heating layer, a heat preservation layer and a second temperature sensor; the heat preservation layer, the heating layer, the aluminum cylinder, the heating layer and the heat preservation layer are arranged from inside to outside in sequence; the chromatographic column layer and the second heating wire are wound to form the heating layer.
7. The soil voc flame ion detection system of claim 6 wherein the flow valve set comprises:
a first six-way valve and a second six-way valve;
the third end of the first six-way valve is connected with one end of the enrichment-analysis module, the sixth end of the first six-way valve is connected with the other end of the enrichment-analysis module, the second end of the first six-way valve is connected with the chromatographic column unit, the first end of the first six-way valve is connected with the gas source module, the fourth end of the first six-way valve is connected with the first end of the second six-way valve, the fifth end of the first six-way valve is connected with the fourth end of the second six-way valve, the second end of the second six-way valve is connected with the gas source module, and the third end of the second six-way valve is connected with the gas source module.
8. The soil volatile organic compounds flame ion detection system of claim 6, wherein the chromatographic separation module further comprises:
the fan is used for fixing the chromatographic column unit on the fan and accelerating the air flow;
the heating power supply is connected with the second heating wire and used for supplying electric energy to the second heating wire;
the second temperature sensor is arranged on the chromatographic column layer and used for detecting the temperature of the chromatographic column layer;
and the chromatographic temperature controller is connected with the second temperature sensor and is used for controlling the heating power supply to supply electric energy to the second heating wire according to the temperature of the chromatographic column layer.
9. The soil volatile organic flame ion detection system of claim 7, further comprising:
and the flame ion detection device, the first six-way valve and the second six-way valve are arranged in the pipeline temperature control box.
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