CN115060569B - Rapid enrichment system and method for soil VOCs analysis and detection - Google Patents
Rapid enrichment system and method for soil VOCs analysis and detection Download PDFInfo
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- CN115060569B CN115060569B CN202210986430.XA CN202210986430A CN115060569B CN 115060569 B CN115060569 B CN 115060569B CN 202210986430 A CN202210986430 A CN 202210986430A CN 115060569 B CN115060569 B CN 115060569B
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Abstract
The invention discloses a rapid enrichment system and a rapid enrichment method for analyzing and detecting soil VOCs (volatile organic compounds), belonging to the technical field of soil VOCs detection. When the soil VOCs is analyzed and detected, the machine is started to preheat, the adjusting instrument is in a ready state and is added with a sample, then the circulating pump and the heater are started to preheat, after the preheating is finished, the VOCs in the soil sample are sampled, the sample is desorbed and baked after being transferred, the process is used for quickly enriching and extracting the VOCs in the soil, and the process is matched with portable chromatography in an investigation site, so that the efficiency of the investigation of the soil VOCs site is greatly improved.
Description
Technical Field
The invention relates to the technical field of soil VOCs detection, in particular to a rapid enrichment system and a rapid enrichment method for soil VOCs analysis and detection.
Background
Soil is the most important element in nature and is the material basis for survival and sustainable development of people.
The re-development and utilization of the polluted site in China face higher environmental and health risks, and the pollution condition needs to be mastered urgently.
In the action plan for soil pollution control issued by the State administration 2016, soil pollution investigation and monitoring are regarded as basic work. Among them, investigation of the pollution status of volatile organic pollutants (VOCs) of field soil is one of the current key tasks.
At present, the detection of soil VOCs is basically carried out by sampling and then sending the soil VOCs to a laboratory for processing and analysis, the laboratory mostly adopts headspace or purging and trapping equipment for extracting and processing the VOCs, and the method is long in time consumption and cannot meet the requirement of rapid analysis on site.
For the investigation of the VOCs in the field soil, the organic pollutants in the soil are complex in type and wide in content change range, and are sent to a laboratory instrument for analysis, the period is long, the cost is high, and the factors become the key for restricting the working efficiency of the field investigation.
Therefore, a rapid enrichment system and method suitable for analyzing and detecting the soil VOCs for field detection is urgently needed to solve the above problems.
Disclosure of Invention
The invention aims to provide a rapid enrichment system and a rapid enrichment method for soil VOCs analysis and detection, wherein formed equipment is light and portable, can be powered by a lithium battery and is convenient to bring into a field, and the problems in the background art can be solved by matching with portable chromatography.
In order to achieve the purpose, the invention provides the following technical scheme: a rapid enrichment system for analyzing and detecting soil VOCs comprises a valve device, a soil purging pipe component, a water removal device, a circulating device, an adsorption and desorption module and a flow dividing device;
the valve device is used for changing the state of a corresponding valve according to the analysis and detection flow of the soil VOCs so that the carrier gas flows according to a preset line;
the soil sweeping pipe part is used for preheating the system and containing a soil sample;
the water removal device is used for reducing the water vapor content in the soil sample;
the circulating device is used for realizing internal circulation of gas during sweeping of the soil VOCs, accelerating the preheating efficiency of the gas and reducing the consumption of carrier gas and heat;
the adsorption and desorption module is used for low-temperature adsorption of the processed sample and thermal desorption sample injection after adsorption is finished.
The shunting device is used for realizing shunting, recycling, reserving and checking functions of the sample.
According to the technical scheme, the valve device comprises a ten-way valve or two six-way valves, a precise pressure regulating valve and five electromagnetic switch valves, wherein the states of the valves are modified according to the states of the valves required in the soil VOCs analysis and detection process, the ten-way valve is a 10-1 passage, a 2-3 passage, a 4-5 passage, a 6-7 passage and a 8-9 passage in a closed state, and the ten-way valve is a 1-2 passage, a 3-4 passage, a 5-6 passage, a 7-8 passage and a 9-10 passage in an open state.
According to the technical scheme, the soil purging pipe component comprises two heaters, one heater is used for heating carrier gas entering the purging pipe at the front end of the purging pipe, radiating fins can be matched on the heater and used for improving heat exchange efficiency, the other heater is used for heating the purging pipe, the soil purging pipe component is used for containing a soil sample and preheating a system, the pretreatment efficiency is improved, and a layer of porous sieve plate is arranged at the bottom of the soil purging pipe and used for ventilating and preventing solid soil from falling off.
The system preheating means heating the gas and soil sample in the purging pipe.
According to the technical scheme, the water removal device comprises a normal-temperature physical condensation water removal device and a quartz glass tube arranged in a cold trap module and used for reducing the water vapor content in the soil sample and drying the pipeline;
the adsorption and desorption module adopts semiconductor electronic refrigeration, the interior of a refrigeration cavity comprises 2 quartz glass tubes, one quartz glass tube is used for removing water at low temperature, the other quartz glass tube is used for a sample after low-temperature adsorption treatment, and the low temperature of the cold trap cavity can reach minus 30 ℃ at room temperature of 25 ℃; the surface of the quartz tube is wrapped with a heating wire, so that the functions of heating decomposition and baking are realized, and the maximum desorption baking temperature can reach 350 ℃.
According to the technical scheme, the circulating device is a circulating pump, and the circulating pump is used for accelerating the thermal circulation of gas in the purging pipe and keeping the sample fully preheated; the flow dividing device is composed of two flow limiters, and the two flow limiters are used for controlling the flow dividing proportion.
A rapid enrichment method for analyzing and detecting soil VOCs comprises the following steps:
s1, starting up to preheat, opening a valve box to heat and refrigerating a cold trap, adjusting an instrument to a ready state and finishing sample addition;
s2, turning on a switch of a circulating pump, and simultaneously turning on heating temperature control functions of the two heaters to preheat the system;
s3, sampling VOCs in the soil sample;
and S4, after the sample is transferred, carrying out desorption-baking.
According to the technical scheme, the sample adding means that a soil sample with a certain mass is added into the soil purging tube, after the sample is added, a cover of the purging tube is quickly covered to prevent the sample from volatilizing, then the purging tube is inserted into the system, the upper part and the lower part of the purging tube are sealed, and the purging tube is connected into a gas path to prepare for automatic enrichment pretreatment of the system; the soil sample with certain mass is that the soil sample is generally 5g, and the valve box is heated to be 120 ℃ at constant temperature.
According to the technical scheme, the system preheating means that gas is circulated through a circulating pump, so that the temperature of the gas in a purging pipe and the temperature of a soil sample are increased to a set value alpha, and the temperature range is room temperature-300 ℃;
the temperature rise means that the temperature of the gas in the purging pipe and the soil sample rises to a set value through the circulation flow of the gas by starting the heating temperature control functions of the two heaters;
temperature control range of the heater: a first heater at room temperature to 300 ℃, a second heater: room temperature-300 ℃;
the predetermined value can be reached by heating for 2 min.
According to the technical scheme, after the preheating is finished, the circulating pump is closed, the V2 and the V4 are opened, carrier gas passes through the purging pipe, volatile organic compounds and water vapor in the soil are taken out, and the carrier gas enters a subsequent pipeline to perform dewatering and enriching functions;
if the shunting recovery function is needed, the V5 can be synchronously opened, and a sample is collected and taken back to a laboratory for retention and verification;
reducing the water vapor content through a normal-temperature physical condensation dehydrator and a water-removing cold trap pipe, and then enabling the airflow without water vapor to pass through an adsorption cold trap to adsorb and retain VOCs substances in the airflow;
transferring VOCs in the soil sample into an adsorption pipe capable of being analyzed through purging and transferring for a period of time, waiting for subsequent treatment, and predicting that the whole purging and transferring time can be completed within 2 min;
after sampling is finished, closing V2, V4 or V5, and simultaneously closing the heating functions of the two heaters;
the V2, the V3, the V4, the V5 and the V6 refer to electromagnetic switch valves;
most of water vapor in the soil sample can be removed firstly through the normal-temperature physical condensation dehydrator, so that the passing air flow keeps a low water vapor content;
and then removing most of the residual water vapor through a water-cooled trap pipe, so that the water vapor content in the sample is reduced to be lower.
According to the technical scheme, the desorption-baking means that after the sample is transferred, a desorption analysis program can be carried out and the dehydration pipeline is synchronously baked and cleaned;
the desorption-baking specific steps are as follows:
z1, opening V1, V3 and V6, reversely passing GC carrier gas through an adsorption cold trap, and desorbing the substances which are just adsorbed by instantly raising the temperature;
z2, carrying the desorbed substances into a GC analysis end by carrier gas to carry out chromatographic analysis;
z3, the carrier gas passing through the V3 is divided into two flow paths, two groups of gases with constant flow are output through a damping limiter, the gases respectively pass through a dewatering cold trap pipe and a normal-temperature physical condensation dehydrator, the dewatering cold traps are synchronously heated, the frozen water vapor is evaporated, passes through a carrier gas discharge system, dries a pipeline, and the other path of carrier gas passes through the normal-temperature physical condensation dehydrator in the reverse direction to discharge the liquid water physically condensed out from the normal-temperature physical condensation dehydrator through a V6;
z4, after the desorption is finished, the heating of the cold trap is closed, V1, V3 and V6 are closed, the pipeline is cleaned, and the system treatment is finished
The V1 is a ten-way valve or a six-way valve, and the desorption-baking process is expected to be completed within 2 min.
Through above-mentioned technical scheme, realize that soil VOCs's quick enrichment draws and the function that detects, very big promotion soil VOCs place investigation's efficiency, corresponding countermeasure is made that the result through the analysis can be timely simultaneously, cross contamination appears in the sample transportation process of avoiding gathering.
Compared with the prior art, the invention has the following beneficial effects:
1. according to the invention, by developing a rapid enrichment method for soil VOCs and matching with a portable chromatographic detection system at the rear end, direct sample injection analysis of a field soil sample can be realized, the rapid detection function of VOCs such as soil volatile aromatic hydrocarbons and the like is realized, the efficiency of field investigation work is improved, meanwhile, a reasonable scheme can be rapidly made according to the detection result, and the occurrence of larger pollution is prevented and the diffusion of pollution is controlled.
2. The invention is provided with a flow dividing device, a valve device, a soil sweeping pipe part, an adsorption and desorption module, a water removing device and a circulating device. The shunting device can perform shunting, recycling and sample reserving functions by using a standard adsorption tube, can realize the on-site test of a soil sample and simultaneously extract and reserve substances so as to be brought back to a laboratory for more detailed substance qualitative analysis (GC-MS detection) or parallel comparison; the water removal device can reduce the water vapor content in the soil sample.
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:
FIG. 1 is a schematic diagram of the connection structure of a rapid enrichment system for analyzing and detecting VOCs in soil according to the present invention;
FIG. 2 is a schematic flow chart illustrating the steps of a rapid enrichment method for analytical detection of soil VOCs according to the present invention;
fig. 3 is a schematic flow chart of an initial stage of analysis and detection of soil VOCs by using a ten-way valve:
fig. 4 is a schematic diagram of a preheating stage process for analyzing and detecting soil VOCs by using a ten-way valve:
fig. 5 is a schematic flow diagram of a sampling phase for analyzing and detecting soil VOCs using a ten-way valve:
fig. 6 is a schematic flow diagram of desorption-baking stage for soil VOCs analysis and detection using a ten-way valve:
FIG. 7 is a schematic flow diagram of an initial stage of soil VOCs analysis and detection using a six-way valve:
fig. 8 is a schematic diagram of a preheating stage process for analyzing and detecting soil VOCs by using a six-way valve:
fig. 9 is a schematic flow diagram of a sampling phase for analyzing and detecting soil VOCs using a six-way valve:
fig. 10 is a schematic diagram of a desorption-baking stage process for soil VOCs analysis and detection using a six-way valve.
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.
As shown in fig. 1 to 10, the present invention provides a rapid enrichment system for analyzing and detecting soil VOCs, wherein the enrichment system for detecting soil VOCs comprises a valve device, a soil purge pipe component, a water removal device, a circulation device, an adsorption and desorption module, and a flow dividing device;
the valve device is used for changing the state of a corresponding valve according to the analysis and detection flow of the soil VOCs so that the carrier gas flows according to a preset line;
the soil sweeping pipe part is used for preheating the system and containing a soil sample;
the water removal device is used for reducing the water vapor content in the soil sample;
the circulating device is used for realizing internal circulation of gas during sweeping of the soil VOCs, accelerating the preheating efficiency of the gas and reducing the consumption of carrier gas and heat;
the adsorption and desorption module is used for low-temperature adsorption of the processed sample and thermal desorption sample injection after adsorption is finished.
The shunting device is used for realizing shunting, recycling, reserving and checking functions of the sample.
The valve device comprises a ten-way valve or two six-way valves, a precise pressure regulating valve and five electromagnetic switch valves, wherein the states of the valves are modified according to the states of the valves required in the soil VOCs analysis and detection process, the ten-way valve is a 10-1, 2-3, 4-5, 6-7 and 8-9 passage in a closed state, and a 1-2, 3-4, 5-6, 7-8 and 9-10 passage in an open state, for example, in desorption-baking, the ten-way valve is opened, and the passages are 1-2, 3-4, 5-6, 7-8 and 9-10.
The soil sweeping pipe part is internally provided with two heaters, one heater is used for heating carrier gas entering the sweeping pipe at the front end of the sweeping pipe, radiating fins can be matched on the heater for improving the heat exchange efficiency, the other heater is used for heating the sweeping pipe, and the soil sweeping pipe part is used for containing a soil sample and preheating a system for improving the pretreatment efficiency;
the system preheating means heating the gas and the soil sample in the purging pipe, for example, two heaters are included to rapidly heat the gas and the soil sample in the purging pipe, so that the temperature of the gas and the soil sample reaches a set value.
The water removing device comprises a normal-temperature physical condensation water remover and a quartz glass tube arranged in the cold trap module and is used for reducing the water vapor content in the soil sample and drying the pipeline. For example, the normal-temperature physical condensation dehydrator can remove most of water vapor in a moist soil sample to keep the passing air flow at a lower water vapor content, and then further remove most of the remaining water vapor through the following water-removing cold trap pipe to reduce the water vapor content in the sample to be lower;
the adsorption and desorption module adopts semiconductor electronic refrigeration, the interior of a refrigeration cavity comprises 2 quartz glass tubes, one quartz glass tube is used for removing water at low temperature, the other quartz glass tube is used for a sample after low-temperature adsorption treatment, and the low temperature of the cold trap cavity can reach minus 30 ℃ at room temperature of 25 ℃; the surface of the quartz tube is wrapped with a heating wire to realize the functions of heating decomposition and baking, and the maximum desorption baking temperature can reach 350 ℃.
The circulating device is a circulating pump and is used for accelerating the thermal circulation of gas in the purging pipe and keeping the sample fully preheated; the flow dividing device is composed of two flow limiters, and the two flow limiters are used for controlling the flow dividing proportion.
A rapid enrichment method for analyzing and detecting soil VOCs comprises the following steps:
s1, starting up to preheat, opening a valve box to heat and refrigerating a cold trap, adjusting an instrument to a ready state and finishing sample addition;
s2, turning on a switch of a circulating pump, and simultaneously turning on heating temperature control functions of the two heaters to preheat the system;
s3, sampling VOCs in the soil sample;
and S4, after the sample is transferred, carrying out desorption-baking.
The sample adding refers to adding a certain mass of soil sample into the soil purging pipe, quickly covering a cover of the purging pipe after the sample adding is finished to prevent the sample from volatilizing, then inserting the purging pipe into the system, sealing the purging pipe up and down, and connecting the purging pipe into a gas path to prepare for automatic enrichment pretreatment of the system; the soil sample with a certain mass is generally 5g, for example, 5g of the soil sample is added into a soil purging pipe, a cover of the purging pipe is quickly covered, then the purging pipe is inserted into the system, the upper part and the lower part of the purging pipe are sealed, and the purging pipe is connected into a gas circuit to prepare for automatic enrichment pretreatment of the system.
The system preheating means that gas is circulated through a circulating pump, and the temperature of the gas in the purging pipe and the temperature of the soil sample are increased to a set value;
the temperature rise refers to that the temperature of the gas in the purging pipe and the temperature of the soil sample are raised to a set value alpha through the circulation flow of the gas by starting the heating temperature control functions of the two heaters, and the temperature range is room temperature-300 ℃;
temperature control range of the heater: a first heater at room temperature to 300 ℃, a second heater: room temperature to 300 ℃;
the predetermined value generally requires heating for 2min to reach the predetermined temperature.
After the preheating is finished, the circulating pump is closed, V2 and V4 are opened, the carrier gas passes through the purging pipe, volatile organic compounds and water vapor in the soil are carried out, and the volatile organic compounds and the water vapor enter a subsequent pipeline for dewatering and enriching;
if the shunting recovery function is needed, the V5 can be synchronously opened, and a sample is collected and taken back to a laboratory for retention and verification;
reducing the water vapor content through a normal-temperature physical condensation dehydrator and a water-removing cold trap pipe, and then enabling the airflow without water vapor to pass through an adsorption cold trap to adsorb and retain VOCs substances in the airflow;
transferring VOCs in the soil sample into an adsorption pipe capable of being analyzed through purging and transferring for a period of time, waiting for subsequent treatment, and predicting the whole purging and transferring time to be completed within 2 min;
after sampling is finished, closing V2, V4 or V5, and simultaneously closing the heating functions of the two heaters;
the V2, the V3, the V4 and the V5 refer to electromagnetic switch valves;
most of water vapor in the soil sample can be removed firstly through the normal-temperature physical condensation dehydrator, so that the passing air flow keeps a low water vapor content;
and then removing most of the residual water vapor by a water-cooling trap pipe, so that the water vapor content in the sample is reduced to be lower.
The desorption-baking is to perform a desorption analysis program and synchronously bake and clean a water removal pipeline after the sample is transferred;
the desorption-baking specific steps are as follows:
z1, opening V1, V3 and V6, reversely passing GC carrier gas through an adsorption cold trap, and desorbing the substances which are just adsorbed by instantly raising the temperature;
z2, carrying the desorbed substances into a GC analysis end by carrier gas to carry out chromatographic analysis;
z3, the carrier gas passing through the V3 is divided into two flow paths, two groups of gases with constant flow are output through a damping limiter, the gases respectively pass through a dewatering cold trap pipe and a normal-temperature physical condensation dehydrator, the dewatering cold traps are synchronously heated, the frozen water vapor is evaporated, passes through a carrier gas discharge system, dries a pipeline, and the other path of carrier gas passes through the normal-temperature physical condensation dehydrator in the reverse direction to discharge the liquid water physically condensed out from the normal-temperature physical condensation dehydrator through a V6;
z4, after the desorption is finished, the heating of the cold trap is closed, V1, V3 and V6 are closed, the pipeline is cleaned, and the system treatment is finished
The V1 is a ten-way valve or a six-way valve, and the desorption-baking process is expected to be completed in 2 min.
Can realize that soil VOCs's quick enrichment draws and the function that detects, very big promotion soil VOCs place investigation's efficiency, can be timely through the result of analysis simultaneously make corresponding countermeasure, cross contamination appears in the sample transportation process of avoiding gathering.
Example 1:
the system connection mode of the scheme is that a pressure regulating valve is connected with one end of a V2 electromagnetic switch valve and one end of a V3 electromagnetic switch valve, the other end of the V2 is connected with one end of a circulating pump and one end of a soil purging pipe, the other end of the V3 is respectively connected with two dampers and is connected with 8-9 channels of the V4 electromagnetic switch valve and a V1 ten-way valve, the other end of the circulating pump and the other end of the soil purging pipe are connected with the left end of a normal-temperature physical condensation dehydrator, the lower end of the normal-temperature physical condensation dehydrator is connected with a V6 electromagnetic switch valve, the right side end of the normal-temperature physical condensation dehydrator is respectively connected with 1-10 channels of an adsorption pipe and the V1 ten-way valve, the other end of the adsorption pipe is connected with a V5, the other end of the V5 is connected with a second flow limiter, 7-6 channels of the V1 ten-way valve are connected with an adsorption heat desorption module of two channels, 2-3 channels are connected with the V4 electromagnetic switch valve, 4-5 channels are GC analysis ends, and the other end of the V4 other end is connected with a first flow limiter.
Preheating by starting a machine, opening a valve box for heating and refrigerating a cold trap, and adjusting an instrument to a ready state; and then adding 5g of soil sample into the soil purging pipe, quickly covering a cover of the purging pipe after the sample is added, inserting the purging pipe into the system, sealing the purging pipe from top to bottom, connecting the purging pipe into a gas path, and preparing for automatic enrichment pretreatment of the system, as shown in fig. 3.
And (3) turning on a switch of the circulating pump, simultaneously turning on heating temperature control work of the two heaters, and rapidly increasing the temperature of the gas in the purging pipe and the soil sample to a set value of alpha =200 ℃ after 2min through gas circulation of the circulating pump, as shown in fig. 4.
After the preheating is finished, the circulating pump is closed, V2 and V4 are opened, the carrier gas carries out water removal and enrichment functions through the purging pipe by taking out volatile organic compounds and water vapor in the soil, the volatile organic compounds and the water vapor enter a subsequent pipeline, V5 is synchronously opened, the sample is recovered, and the volatile organic compounds and the water vapor are taken back to a laboratory to be stored and checked, as shown in figure 5.
The ten-way valves V1, V3 and V6 are opened, GC carrier gas reversely passes through the adsorption cold trap, substances which are just adsorbed are desorbed through instantaneous temperature rise, the carrier gas is carried into a GC analysis end to carry out chromatographic analysis, the carrier gas passing through the V3 is divided into two flow paths, two groups of gases with constant flow are output through a damping limiter, and the gases are respectively condensed and dehydrated through a dehydration cold trap pipe and normal temperature physics: synchronously heating the water removing cold trap, evaporating the frozen water vapor, discharging the water vapor out of the system through carrier gas, and drying the pipeline; the other path of carrier gas reversely passes through the normal-temperature physical condensation dehydrator to discharge the liquid water which is physically condensed out from the normal-temperature physical condensation dehydrator through V6; after the desorption is finished, the heating of the cold trap is closed, the V1, the V3 and the V6 are closed, the pipeline cleaning is finished, and the system treatment is finished, as shown in FIG. 6.
Example 2:
the system connection mode of the scheme is that a pressure regulating valve is connected with a V3 electromagnetic switch valve, one end of the V4 electromagnetic switch valve is connected, the other end of the V3 is connected with a circulating pump and one end of a soil purging pipe, the other end of the V4 is connected with 1 damper and is connected with a 5-4 channel of a V1 six-way valve, the other end of the circulating pump and the soil purging pipe are connected with the left end of a normal-temperature physical condensation dehydrator, the right end of the normal-temperature physical condensation dehydrator is respectively connected with an adsorption pipe and a 2-3 channel of the V1 six-way valve, the other end of the adsorption pipe is connected with a V6, the other end of the V6 is connected with a flow limiter, the 2-3 channel of the V1 six-way valve is connected with a 4-5 channel of the V2 six-way valve, the 4-5 channel of the V1 six-way valve is connected with the bottom end of a dewatering cold trap of a dual-channel adsorption heat desorption module, the 1-6 channel is connected with the top end of the dewatering cold trap, the 4-5 channel of the V2 six-way valve is connected with the bottom end of the adsorption cold trap, the 1-6 channel is connected with the top end of the dewatering cold trap, the 2-3 channel is an analysis end, the other end of the V5 electromagnetic switch valve is connected with a two-5 electromagnetic switch, and the GC, and the other end of the two-5 electromagnetic switch.
The method comprises the steps of firstly starting the machine for preheating, opening a valve box for heating and refrigerating a cold trap, adjusting an instrument to a ready state, then adding 5g of a soil sample into a soil purging pipe, quickly covering a cover of the purging pipe after the sample is added, then inserting the purging pipe into a system, sealing the purging pipe up and down, connecting the purging pipe into a gas path, and preparing for automatic enrichment pretreatment of the system, as shown in fig. 7.
And (3) turning on a switch of the circulating pump, simultaneously turning on heating temperature control work of the two heaters, and rapidly increasing the temperature of the gas in the purging pipe and the soil sample to a set value alpha after 2min through gas circulation of the circulating pump, as shown in figure 8.
After the preheating is finished, the circulating pump is closed, the six-way valves V1, V3 and V5 are opened, the carrier gas carries out water removal and enrichment functions on volatile organic compounds and water vapor in the soil through the purging pipe, the volatile organic compounds and the water vapor are carried out, the volatile organic compounds and the water vapor are synchronously opened, the sample is recovered, and the carrier gas is carried back to a laboratory for retention and verification, as shown in fig. 9.
Open six-way valve V2, V4, the reverse absorption cold trap that passes through of GC carrier gas, through the transient intensification, will just adsorb down the material desorption, take into GC analysis end through the carrier gas and carry out chromatographic analysis, through V4's carrier gas, through the gas of damping limiter defeated constant flow, through removing water cold trap pipe: and (3) synchronously heating the water removal cold trap, evaporating the frozen water vapor to pass through a carrier gas discharge system, drying the pipeline, closing the heating of the cold trap after desorption is finished, closing V2 and V4, finishing pipeline cleaning, and finishing system treatment, as shown in figure 10.
In the embodiment, two six-way valves are used for replacing one ten-way valve, so that the effect of using one ten-way valve is achieved, meanwhile, the lower end of the normal-temperature physical condensation dehydrator is directly connected with a gas-water separator, and when too much separated water exists, manual release can be performed.
It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (10)
1. A quick enrichment system for soil VOCs analysis and detection is characterized in that: the rapid enrichment system for analyzing and detecting the soil VOCs comprises a valve device, a soil sweeping pipe part, a dewatering device, a circulating device, an adsorption and desorption module and a shunting device;
the valve device is used for changing the state of a corresponding valve according to the analysis and detection process of the soil VOCs and comprises a ten-way valve or two six-way valves, a precise pressure regulating valve and five electromagnetic switch valves; the ten-way valve comprises ten passages (1), (2), (3), (4), (5), (6), (7), (8), (9) and (10), (1) and (10) are connected, (2) and (3) are connected, (4) and (5) are connected, (6) and (7) are connected, and (8) and (9) are connected; the passage (10) is connected with the upper end of the water removal pipe, and the passage (7) is connected with the lower end of the water removal pipe; (3) The passage is connected with the upper end of the adsorption tube, and (6) the passage is connected with the lower end of the adsorption tube; (2) the passage is connected with the left side of the V4 electromagnetic switch valve; (4) The passage is connected with an inlet of a GC analysis end, and (5) the passage is connected with an outlet of the GC analysis end; (1) the passage is connected with a dehydrator; (8) the passage is connected with the right side of the V3 electromagnetic switch valve through damping; the electromagnetic switch valve comprises V2, V3, V4, V5 and V6, and the V2 is connected with the first heater; v3 is connected with a precision pressure regulating valve and a damper; v4 is connected with a first flow limiter; v5 is connected with the second flow limiter and the adsorption tube; the V6 is connected with a dehydrator;
the soil purging pipe part is used for preheating a system and containing a soil sample, and comprises two heaters, wherein one heater is used for heating carrier gas entering the purging pipe at the front end of the purging pipe, and the other heater is used for heating the purging pipe; the bottom of the soil sweeping pipe is also provided with a layer of porous sieve plate;
the water removal device is used for reducing the water vapor content in a soil sample and comprises a normal-temperature physical condensation water remover and a quartz glass tube arranged in a cold trap module;
the circulating device is a circulating pump and is used for realizing internal circulation of gas during purging of soil VOCs; the upper end of the circulating pump is connected with the second heater, and the lower end of the circulating pump is connected with the first heater;
the adsorption and desorption module is used for low-temperature adsorption of the treated sample and thermal desorption sample injection after adsorption is finished;
the flow dividing device is used for realizing the functions of dividing, recovering, reserving and checking samples and consists of two flow limiters.
2. The rapid enrichment system for analytical testing of soil VOCs according to claim 1, wherein: the valve device comprises a ten-way valve or two six-way valves, a precise pressure regulating valve and five electromagnetic switch valves, and the states of the valves are modified according to the states of the valves required in the soil VOCs analysis and detection process.
3. The rapid enrichment system for analytical testing of soil VOCs according to claim 1, wherein: the soil purging pipe part is internally provided with two heaters, one heater is used for heating carrier gas entering the purging pipe at the front end of the purging pipe, the other heater is used for heating the purging pipe, the soil purging pipe part is used for containing a soil sample and preheating a system, and the bottom of the soil purging pipe is further provided with a layer of porous sieve plate which is used for ventilating and preventing solid soil from falling.
4. The rapid enrichment system for analytical testing of soil VOCs according to claim 1, wherein: the water removing device comprises a normal-temperature physical condensation water remover and a quartz glass tube arranged in the cold trap module and is used for reducing the water vapor content in the soil sample and drying the pipeline; the adsorption and desorption module adopts semiconductor electronic refrigeration, and the inside of the refrigeration cavity comprises two quartz glass tubes, one quartz glass tube is used for low-temperature dewatering, and the other quartz glass tube is used for a sample after low-temperature adsorption treatment; the surface of the quartz tube is wrapped with a heating wire, so that the quartz tube can perform heating desorption and baking functions.
5. The rapid enrichment system for analytical testing of soil VOCs according to claim 1, wherein: the circulating device is a circulating pump and is used for accelerating the thermal circulation of the gas in the purging pipe; the flow dividing device is composed of two flow limiters, and the two flow limiters are used for controlling the flow dividing proportion.
6. A rapid enrichment method for analytical testing of soil VOCs using the system of claim 1, wherein: the enrichment method comprises the following steps:
s1, starting up to preheat, opening a valve box to heat and refrigerating a cold trap, adjusting an instrument to a ready state and finishing sample addition;
s2, turning on a switch of a circulating pump, and simultaneously turning on heating temperature control functions of the two heaters to preheat the system;
s3, sampling VOCs in the soil sample;
and S4, after the sample is transferred, carrying out desorption-baking.
7. The rapid enrichment method for analytical detection of soil VOCs according to claim 6, wherein the rapid enrichment method comprises the following steps: the sample adding refers to adding a certain mass of soil sample into the soil purging pipe, quickly covering a cover of the purging pipe after the sample adding is completed, then inserting the purging pipe into the system, sealing the purging pipe from top to bottom, connecting the purging pipe into a gas path, and preparing for automatic enrichment pretreatment of the system.
8. The method of claim 6, wherein the rapid enrichment for analytical testing of soil VOCs comprises: the system preheating means that gas is circulated through a circulating pump, and the temperature of the gas in the purging pipe and the temperature of the soil sample are increased to a set value.
9. The method of claim 6, wherein the rapid enrichment for analytical testing of soil VOCs comprises: after the preheating is finished, the circulating pump is closed, V2 and V4 are opened, the carrier gas passes through the purging pipe, volatile organic compounds and water vapor in the soil are carried out, and the volatile organic compounds and the water vapor enter a subsequent pipeline for dewatering and enriching;
if the shunting recovery function is needed, the V5 can be synchronously opened, and a sample is collected and taken back to a laboratory for retention and verification;
removing water vapor in the sample airflow through a normal-temperature physical condensation dehydrator and a water removal cold trap pipe, and adsorbing and retaining VOCs (volatile organic compounds) in the airflow through an adsorption cold trap after drying;
transferring VOCs in the soil sample into an adsorption pipe capable of being analyzed through purging and transferring for a period of time, and waiting for subsequent treatment;
after sampling is finished, closing V2, V4 or V5, and simultaneously closing the heating functions of the two heaters;
v2 is the first electromagnetic opening/closing valve, V4 is the third electromagnetic opening/closing valve, and V5 is the fourth electromagnetic opening/closing valve.
10. The rapid enrichment method for analytical detection of soil VOCs according to claim 6, wherein the rapid enrichment method comprises the following steps: the desorption-baking means that after the sample is transferred, a desorption analysis procedure can be carried out and the dehydration pipeline is synchronously baked and cleaned;
the desorption-baking specific steps are as follows:
z1, opening V1, V3 and V6, reversely passing GC carrier gas through an adsorption cold trap, and desorbing the substance which is just adsorbed by instantly raising the temperature;
z2, carrying the desorbed substances into a GC analysis end by carrier gas to carry out chromatographic analysis;
z3, the carrier gas passing through the V3 is divided into two flow paths, two groups of gases with constant flow are output through a damping limiter, the gases respectively pass through a dewatering cold trap pipe and a normal-temperature physical condensation dehydrator, the dewatering cold traps are synchronously heated, the frozen water vapor is evaporated, passes through a carrier gas discharge system, dries a pipeline, and the other path of carrier gas passes through the normal-temperature physical condensation dehydrator in the reverse direction to discharge the liquid water physically condensed out from the normal-temperature physical condensation dehydrator through a V6;
z4, after the desorption is finished, the heating of the cold trap is closed, V1, V3 and V6 are closed, and the system treatment is finished after the pipeline is cleaned;
v1 is a ten-way valve, V3 is a second electromagnetic switch valve, and V6 is a fifth electromagnetic switch valve.
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| CN102980960A (en) * | 2011-09-05 | 2013-03-20 | 核工业北京地质研究院 | Heat purge and trap instrument and heat purge and trap method |
| CN104181284B (en) * | 2014-07-11 | 2016-03-09 | 上海市政工程设计研究总院（集团）有限公司 | A kind of Volatile Organic Compounds in Soil continuous detection apparatus and detection method thereof |
| CN205786045U (en) * | 2015-09-01 | 2016-12-07 | 武汉市天虹仪表有限责任公司 | A kind of volatile organic matter sample gas trapping system |
| CN105043846A (en) * | 2015-09-01 | 2015-11-11 | 武汉市天虹仪表有限责任公司 | Volatile organic compound sample gas trapping system and method |
| CN110208074A (en) * | 2019-05-21 | 2019-09-06 | 上海市环境科学研究院 | A kind of Volatile Organic Compounds in Soil device for fast detecting and its detection method |
| CN112834675A (en) * | 2020-12-30 | 2021-05-25 | 杭州谱育科技发展有限公司 | Device and method for analyzing VOCs and SVOCs on line |
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| CN112731992A (en) * | 2021-01-11 | 2021-04-30 | 泰通科技（广州）有限公司 | Full-automatic low temperature series valve who sweeps entrapment appearance keeps apart water trap |
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