An online pre-concentrator for multi-point multi-channel sampling without blind spots and a method thereof

Abstract

The present invention discloses an online pre-concentrator and method for multi-point multi-channel blind spot sampling, which belongs to the field of pollution source gas monitoring technology, including a sampling pre-concentrator unit, a high-temperature switching valve, and a gas chromatography unit; the sampling pre-concentrator units have at least two, and the sampling pre-concentrator units are connected in parallel to the high-temperature switching valve; the high-temperature switching valve is connected to the gas chromatography unit. This solution is applied to the field of online flue gas detection, and can continuously measure the signals of two or more furnaces at the same time, ensuring that the instrument can collect flue gas from multiple exhaust ports at the same time, solving the problem that the current stage can only collect flue gas from a single exhaust port.

Description

Technical Field

[0001] The invention belongs to the technical field of pollution source gas monitoring, and particularly relates to an online pre-concentrator for multi-point multi-channel blind spot-free sampling and a method thereof. Background Art

[0002] Organic pollutants emitted from incineration flue gas seriously affect the atmospheric environment. At present, organic pollutants in fixed atmospheric pollution sources are mainly detected offline. Offline detection technology can only collect a limited number of samples. The cost of analyzing a single sample is high and is greatly affected by external interference factors, such as the quality of sampling personnel and transportation conditions. In addition, offline detection technology has a long analysis cycle and data lags, and cannot promptly reflect changes in the content of organic matter in the flue gas caused by changes in working conditions. The online pre-concentrator can monitor organic pollutants in incineration flue gas online by combining gas chromatography and laser ionization time-of-flight mass spectrometry. It has a fast monitoring cycle and is less affected by external interference, meeting the needs of real-time monitoring of incineration flue gas emissions.

[0003] The existing online pre-concentration technology collects organic pollutants at a certain point through a sampling pipeline. In the actual operation process, especially in waste incineration plants, there are multiple waste incinerators and their corresponding flue gas emission outlets. If the organic pollutants at a certain flue gas emission outlet are monitored separately, it is impossible to truly reflect the pollutant emission status of the entire incineration plant. Due to the structural limitations of the current online pre-concentrator, it is impossible to collect flue gas at multiple points in real time at the same time. If the organic pollutants at all flue gas emission outlets are monitored at the same time, it is necessary to use multiple pre-concentrators, multiple gas chromatographs, and multiple laser ionization time-of-flight mass spectrometers to achieve this, which will increase the overall equipment cost. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, an object of the present invention is to provide an online pre-concentrator with multi-point, multi-channel and blind-spot free sampling.

[0005] Another object of the present invention is to provide an online pre-concentration method for multi-point multi-channel sampling without blind spots.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions.

[0007] An online pre-concentrator for multi-point, multi-channel and blind-spot sampling includes a sampling pre-concentrator unit, a high-temperature switching valve and a gas chromatography unit; the sampling pre-concentrator units include at least two, and the sampling pre-concentrator units are connected in parallel to the high-temperature switching valve; the high-temperature switching valve is connected to the gas chromatography unit.

[0008] The sampling pre-concentration unit includes an external standard pipeline, a first cold trap, a flue gas sampling inlet, a second cold trap, a shunt pipeline, a sample outlet pipeline and a gas circuit switching valve; the gas circuit switching valve is provided with a first valve port, a second valve port, a third valve port, a fourth valve port, a fifth valve port and a sixth valve port; the first valve port is connected to the external standard pipeline; the second valve port is connected to the first cold trap; the third valve port is connected to the flue gas sampling inlet; the fourth valve port is connected to the second cold trap; the fifth valve port is connected to the shunt pipeline; the sixth valve port is connected to the sample outlet pipeline; the gas circuit switching valve has two working states:

[0009] First working state: the second valve port is connected with the fifth valve port and the sixth valve port; the third valve port is connected with the fourth valve port; the first cold trap is connected with the shunt pipeline and the sample outlet pipeline; the flue gas sampling inlet is connected with the second cold trap;

[0010] The second working state: the fourth valve port is connected to the fifth valve port and the sixth valve port; the third valve port is connected to the second valve port; the second cold trap is connected to the shunt pipeline and the sample outlet pipeline; the flue gas sampling inlet is connected to the first cold trap.

[0011] The high-temperature switching valve is provided with a high-temperature inlet, a high-temperature selective outlet, and a high-temperature common outlet; there are at least two high-temperature inlets, and one of the high-temperature inlets is connected to the high-temperature selective outlet; the high-temperature inlets that are not connected to the high-temperature selective outlet are all connected to the high-temperature common outlet; the sixth valve port of each sampling pre-concentration unit is connected to a corresponding high-temperature inlet through a pipeline; the high-temperature selective outlet is connected to the gas chromatography unit through a pipeline.

[0012] An online pre-concentration method for multi-point multi-channel blind spot sampling comprises the following steps:

[0013] S1, all sampling pre-concentration units are in sampling, and the first cold trap and the second cold trap in each sampling pre-concentration unit are sampled alternately to form uninterrupted sampling; in each sampling pre-concentration unit, when the first cold trap is in analysis, the second cold trap is in sampling, and when the second cold trap is in analysis, the first cold trap is in sampling; the sampling time of a single cold trap is T=Nt; where: T is the single continuous sampling time of each cold trap, N is the number of sampling pre-concentration units, and t is the valve path switching time interval of the high-temperature switching valve;

[0014] S2, within the sampling time T of the first cold trap, the high temperature switching valve switches different high temperature inlets to be connected with the high temperature selection outlets at intervals of time t, thereby alternately and traversally transmitting the samples in the second cold traps in different sampling pre-concentration units to the gas chromatography unit;

[0015] S3, within the sampling time T of the second cold trap, the high temperature switching valve switches different high temperature inlets to be connected with the high temperature selection outlets at intervals of time t, thereby alternately and traversally transmitting the samples in the first cold traps in different sampling pre-concentration units to the gas chromatography unit;

[0016] S4, alternately repeat S2 and S3 until the online monitoring is completed.

[0017] Further, in S2, the sampling pre-concentration unit is in a second working state, and the flue gas in the flue gas sampling inlet passes through the third valve port and the second valve port to reach the first cold trap, and the first cold trap collects the flue gas; when the high-temperature switching valve is switched, the second cold trap in the sampling pre-concentration unit connected to the high-temperature selection outlet is instantly heated to a high temperature (200°C~400°C) to parse the sample; the second cold trap is introduced with carrier gas to deliver the parsed sample to the gas chromatography unit through the high-temperature switching valve for substance separation; the high-temperature switching valve switches different high-temperature inlets to be connected to the high-temperature selection outlet at intervals of t, so that the parsed samples of different sampling pre-concentration units are connected to the high-temperature selection outlet, thereby alternately traversing the second cold trap parsed samples in different sampling pre-concentration units to the gas chromatography unit; the second cold trap that is not connected to the high-temperature selection outlet is in a waiting state.

[0018] Further, in S3, the sampling pre-concentration unit is in a first working state, and the flue gas in the flue gas sampling inlet passes through the third valve port and the fourth valve port to reach the second cold trap, and the second cold trap collects the flue gas; when the high-temperature switching valve is switched, the first cold trap in the sampling pre-concentration unit connected to the high-temperature selection outlet is instantly heated to a high temperature (200°C~400°C) to parse the sample; the first cold trap is introduced with carrier gas to deliver the parsed sample to the gas chromatography unit through the high-temperature switching valve for material separation; the high-temperature switching valve switches different high-temperature inlets to be connected to the high-temperature selection outlet at intervals of t, so that the parsed samples of different sampling pre-concentration units are connected to the high-temperature selection outlet, thereby alternately traversing the parsed samples of the first cold traps in different sampling pre-concentration units to the gas chromatography unit; the first cold trap that is not connected to the high-temperature selection outlet is in a waiting state.

[0019] The present invention is applied to the field of online flue gas detection, and can continuously and simultaneously measure the signals of two or more furnaces, ensuring that the instrument can simultaneously collect flue gas from multiple emission ports, solving the problem that only a single emission port can be collected at this stage. The present invention can simultaneously measure the emission of pollution sources of the entire incineration plant and feedback the operating conditions of the boiler without increasing too much cost, saving costs, and helping operators to adjust the operating conditions of the incinerators of the entire incineration plant and optimize the incineration environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of the present invention;

[0021] Figure 2 1 is a schematic diagram of the structure of the gas path switching valve in the first working state;

[0022] Figure 3 1 is a schematic diagram of the structure of the gas path switching valve in the second working state;

[0023] Figure 4 It is a structural schematic diagram of a high temperature switching valve;

[0024] Figure 5 This is the operation timing diagram when the number of sampling pre-concentration units is 3;

[0025] In the figure: sampling pre-concentration unit 100, external standard pipeline 101, first cold trap 102, flue gas sampling inlet 103, second cold trap 104, shunt pipeline 105, sample outlet pipeline 106, gas circuit switching valve 107, first valve port 108, second valve port 109, third valve port 110, fourth valve port 111, fifth valve port 112, sixth valve port 113,

[0026] High temperature switching valve 200, high temperature inlet 201, high temperature selection outlet 202, high temperature common outlet 203,

[0027] Gas chromatography unit 300. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with the accompanying drawings.

[0029] An online pre-concentrator for multi-point, multi-channel and blind-spot free sampling includes a sampling pre-concentrator unit 100, a high-temperature switching valve 200 and a gas chromatography unit 300; there are at least two sampling pre-concentrator units 100, and the sampling pre-concentrator units 100 are connected in parallel to the high-temperature switching valve 200; the high-temperature switching valve 200 is connected to the gas chromatography unit 300.

[0030] The sampling pre-concentration unit 100 includes an external standard pipeline 101, a first cold trap 102, a flue gas sampling inlet 103, a second cold trap 104, a shunt pipeline 105, a sample outlet pipeline 106 and a gas circuit switching valve 107; the gas circuit switching valve 107 is provided with a first valve port 108, a second valve port 109, a third valve port 110, a fourth valve port 111, a fifth valve port 112 and a sixth valve port 113; the first valve port 108 is connected to the external standard pipeline 101; the second valve port 109 is connected to the first cold trap 102; the third valve port 110 is connected to the flue gas sampling inlet 103; the fourth valve port 111 is connected to the second cold trap 104; the fifth valve port 112 is connected to the shunt pipeline 105; the sixth valve port 113 is connected to the sample outlet pipeline 106.

[0031] The gas circuit switching valve 107 has two working states:

[0032] First working state: the second valve port 109 is connected to the fifth valve port 112 and the sixth valve port 113; the third valve port 110 is connected to the fourth valve port 111; the first cold trap 102 is connected to the shunt pipeline 105 and the sample outlet pipeline 106; the flue gas sampling inlet 103 is connected to the second cold trap 104. At this time, the first cold trap 102 is in the analysis state, and the second cold trap 104 is in the sampling state.

[0033] Second working state: the fourth valve port 111 is connected to the fifth valve port 112 and the sixth valve port 113; the third valve port 110 is connected to the second valve port 109; the second cold trap 104 is connected to the shunt pipeline 105 and the sample outlet pipeline 106; the flue gas sampling inlet 103 is connected to the first cold trap 102. At this time, the first cold trap 102 is in sampling, and the second cold trap 104 is in analysis.

[0034] The bypass line 105 is arranged to bypass a portion of the sample when the cold trap analyzes the sample, thereby controlling the amount entering the gas chromatograph.

[0035] The high-temperature switching valve 200 is provided with a high-temperature inlet 201, a high-temperature selection outlet 202, and a high-temperature common outlet 203; there are at least two high-temperature inlets 201, and one of the high-temperature inlets 201 is connected to the high-temperature selection outlet 202; the high-temperature inlets 201 that are not connected to the high-temperature selection outlet 202 are all connected to the high-temperature common outlet 203; the sixth valve port 113 of each sampling pre-concentration unit 100 is connected to a corresponding high-temperature inlet 201 through a pipeline; the high-temperature selection outlet 202 is connected to the gas chromatography unit 300 through a pipeline.

[0036] The high-temperature common outlet 203 is in an empty state.

[0037] An online pre-concentration method for multi-point multi-channel blind spot sampling comprises the following steps:

[0038] S1, all sampling pre-concentration units 100 are in sampling, and the first cold trap 102 and the second cold trap 104 in each sampling pre-concentration unit 100 are sampled alternately to form uninterrupted sampling; in each sampling pre-concentration unit 100, when the first cold trap 102 is in analysis, the second cold trap 104 is in sampling, and when the second cold trap 104 is in analysis, the first cold trap 102 is in sampling; the sampling time of a single cold trap is T=Nt; wherein: T is the single continuous sampling time of each cold trap, N is the number of sampling pre-concentration units 100, and t is the valve path switching time interval of the high-temperature switching valve 200;

[0039] S2, within the sampling time T of the first cold trap 102, the high temperature switching valve 200 switches different high temperature inlets 201 to communicate with the high temperature selection outlet 202 at every time t, thereby alternately traversing and transmitting the samples in the second cold traps 104 in different sampling pre-concentration units 100 to the gas chromatography unit 300;

[0040] The sampling pre-concentration unit 100 is in the second working state, and the flue gas in the flue gas sampling inlet 103 passes through the third valve port 110 and the second valve port 109 to reach the first cold trap 102, and the first cold trap 102 collects the flue gas; when the high-temperature switching valve 200 is switched, the second cold trap in the sampling pre-concentration unit connected to the high-temperature selection outlet 203 is instantly heated to a high temperature (200°C~400°C) to parse the sample; the second cold trap 102 is introduced with carrier gas to deliver the parsed sample to the gas chromatography unit through the high-temperature switching valve 200 for material separation; the high-temperature switching valve 200 switches different high-temperature inlets 201 to be connected to the high-temperature selection outlet 202 at every time t, so that the parsed samples of different sampling pre-concentration units 100 are connected to the high-temperature selection outlet 202, thereby alternately traversing and transmitting the parsed samples of the second cold traps 104 in different sampling pre-concentration units 100 to the gas chromatography unit 300; the second cold trap 104 that is not connected to the high-temperature selection outlet 202 is in a waiting state.

[0041] S3, within the sampling time T of the second cold trap 104, the high temperature switching valve 200 switches different high temperature inlets 201 to communicate with the high temperature selection outlet 202 at every time t, thereby alternately traversing the samples in the first cold traps 102 in different sampling pre-concentration units 100 to the gas chromatography unit 300;

[0042] The sampling pre-concentration unit 100 is in a first working state, and the flue gas in the flue gas sampling inlet 103 passes through the third valve port 110 and the fourth valve port 111 to reach the second cold trap 104, and the second cold trap 104 collects the flue gas; when the high-temperature switching valve 200 is switched, the first cold trap 102 in the sampling pre-concentration unit connected to the high-temperature selection outlet 203 is instantly heated to a high temperature (200°C~400°C) to analyze the sample; the first cold trap 102 is introduced with carrier gas to deliver the analyzed sample to the gas chromatography unit 300 through the high-temperature switching valve 200 for material separation; the high-temperature switching valve 200 switches different high-temperature inlets 201 to be connected with the high-temperature selection outlet 202 at every time t, so that the analyzed samples of different sampling pre-concentration units 100 are connected with the high-temperature selection outlet 202, thereby alternately traversing and transmitting the analyzed samples of the first cold traps 102 in different sampling pre-concentration units 100 to the gas chromatography unit 300; the first cold trap 102 not connected to the high-temperature selection outlet 202 is in a waiting state.

[0043] S4, alternately repeat S2 and S3 until the online monitoring is completed.

[0044] When the number of the sampling pre-concentration units 100 is 3, the technical solution is further explained.

[0045] Step 1: The high temperature switching valve 200 can withstand a high temperature of 200° C., the valve switching time interval t is 20 minutes, and the sampling time T of a single cold trap is 60 minutes.

[0046] like Figure 5 As shown, each sampling pre-concentration unit has a set of sampling and analysis operating states, wherein A is the first cold trap of the first sampling pre-concentration unit, B is the second cold trap of the first sampling pre-concentration unit, C is the first cold trap of the second sampling pre-concentration unit, D is the second cold trap of the second sampling pre-concentration unit, E is the first cold trap of the third sampling pre-concentration unit, and F is the second cold trap of the third sampling pre-concentration unit.

[0047] Step 2:

[0048] During the period of 00:00~00:20, A, C, and E are all in sampling, and the high-temperature selection outlet of the high-temperature switching valve is connected to the high-temperature inlet corresponding to the first sampling pre-concentration unit; the analytical sample of the second cold trap B of the first sampling pre-concentration unit reaches the gas chromatography unit 300 through the high-temperature inlet and the high-temperature selection outlet.

[0049] During the period of 00:20~00:40, A, C, and E are all in sampling, and the high-temperature selection outlet of the high-temperature switching valve is connected to the high-temperature inlet corresponding to the second sampling pre-concentration unit; the analytical sample of the second cold trap D of the second sampling pre-concentration unit reaches the gas chromatography unit 300 through the high-temperature inlet and the high-temperature selection outlet.

[0050] During the period of 00:40 to 00:60, A, C, and E are all in sampling, and the high-temperature selection outlet of the high-temperature switching valve is connected to the high-temperature inlet corresponding to the third sampling pre-concentration unit; the analytical sample of the second cold trap F of the third sampling pre-concentration unit reaches the gas chromatography unit 300 through the high-temperature inlet and the high-temperature selection outlet.

[0051] Step 3:

[0052] During the period of 00:60-01:20, B, D, and F are all in sampling, and the high-temperature selection outlet of the high-temperature switching valve is connected to the high-temperature inlet corresponding to the first sampling pre-concentration unit; the analytical sample of the first cold trap A of the first sampling pre-concentration unit reaches the gas chromatography unit 300 through the high-temperature inlet and the high-temperature selection outlet.

[0053] During the period of 01:20-01:40, B, D, and F are all in sampling, and the high-temperature selection outlet of the high-temperature switching valve is connected to the high-temperature inlet corresponding to the second sampling pre-concentration unit; the analytical sample of the first cold trap C of the second sampling pre-concentration unit reaches the gas chromatography unit 300 through the high-temperature inlet and the high-temperature selection outlet.

[0054] During the period of 01:40 to 01:60, B, D, and F are all in sampling, and the high-temperature selection outlet of the high-temperature switching valve is connected to the high-temperature inlet corresponding to the third sampling pre-concentration unit; the analytical sample of the first cold trap E of the third sampling pre-concentration unit reaches the gas chromatography unit 300 through the high-temperature inlet and the high-temperature selection outlet.

[0055] Step 4: Repeat steps 2 and 3 until the online monitoring is completed.

[0056] This technical solution has multiple built-in sampling preprocessing units. When one of the cold traps in the first sampling preconcentration unit, the second sampling preconcentration unit, and the third sampling preconcentration unit is in the sampling state, the other cold trap is analyzed in sequence, and through the switching of the high-temperature switching valve, it is ensured to enter the gas chromatography unit for analysis in sequence, thereby ensuring the instrument's multi-channel blind-spot sampling of flue gas, and solving the problem that the prior art collects flue gas at a single point during the sampling process, resulting in the measured data not being able to fully reflect the pollution emissions of the incineration plant.

[0057] The gas circuit switching valve 107 and the high temperature switching valve 200 in the present technical solution are both common components in the art. For example, the high temperature switching valve 200 can be a switching valve of the model common outlet selectors-1 / 16''fittings, 1.0mm Ports produced by Valco Instruments Co. lnc.; the gas circuit switching valve 107 can be a QH-S gas circuit valve produced by Beijing Ruike Tongheng Technology Development Co., Ltd.

[0058] It is understandable that those skilled in the art can make equivalent substitutions or changes based on the technical solution and inventive concept of the present invention, and all these changes or substitutions should fall within the protection scope of the claims attached to the present invention.

Claims

1. An online pre-concentration method for an online pre-concentrator with multi-point multi-channel sampling without blind spots, characterized in that: The online pre-concentrator comprises a sampling pre-concentration unit (100), a high-temperature switching valve (200), and a gas chromatography unit (300); the sampling pre-concentration units (100) are at least two, and the sampling pre-concentration units (100) are connected in parallel to the high-temperature switching valve (200); the high-temperature switching valve (200) is connected to the gas chromatography unit (300); The sampling pre-concentration unit (100) comprises an external standard pipeline (101), a first cold trap (102), a flue gas sampling inlet (103), a second cold trap (104), a diversion pipeline (105), a sample outlet pipeline (106) and a gas circuit switching valve (107); the gas circuit switching valve (107) is provided with a first valve port (108), a second valve port (109), a third valve port (110), a fourth valve port (111), a fifth valve port (112) and a sixth valve port (113). The first valve port (108) is connected to the external standard pipeline (101); the second valve port (109) is connected to the first cold trap (102); the third valve port (110) is connected to the flue gas sampling inlet (103); the fourth valve port (111) is connected to the second cold trap (104); the fifth valve port (112) is connected to the shunt pipeline (105); the sixth valve port (113) is connected to the sample outlet pipeline (106); the gas path switching valve (107) has two working states: First working state: the second valve port (109) is connected to the fifth valve port (112) and the sixth valve port (113); the third valve port (110) is connected to the fourth valve port (111); the first cold trap (102) is connected to the shunt pipeline (105) and the sample outlet pipeline (106); the flue gas sampling inlet (103) is connected to the second cold trap (104); Second working state: the fourth valve port (111) is connected to the fifth valve port (112) and the sixth valve port (113); the third valve port (110) is connected to the second valve port (109); the second cold trap (104) is connected to the shunt pipeline (105) and the sample outlet pipeline (106); the flue gas sampling inlet (103) is connected to the first cold trap (102); The high-temperature switching valve (200) is provided with a high-temperature inlet (201), a high-temperature selection outlet (202), and a high-temperature common outlet (203); there are at least two high-temperature inlets (201), and one of the high-temperature inlets (201) is selectively connected to the high-temperature selection outlet (202); the high-temperature inlets (201) that are not connected to the high-temperature selection outlet (202) are all connected to the high-temperature common outlet (203); the sixth valve port (113) of each sampling pre-concentration unit (100) is connected to a corresponding high-temperature inlet (201) via a pipeline; the high-temperature selection outlet (202) is connected to the gas chromatography unit (300) via a pipeline; Online pre-concentration method of online pre-concentrator The following steps are involved: S1, all sampling pre-concentration units (100) are in the sampling state, and the first cold trap (102) and the second cold trap (104) in each sampling pre-concentration unit (100) are sampled alternately to form uninterrupted sampling; in each sampling pre-concentration unit (100), when the first cold trap (102) is in the analysis state, the second cold trap (104) is in the sampling state, and when the second cold trap (104) is in the analysis state, the first cold trap (102) is in the sampling state; the sampling time of a single cold trap is T=Nt; wherein: T is the single continuous sampling time of each cold trap, N is the number of sampling pre-concentration units (100), and t is the valve path switching time interval of the high-temperature switching valve (200); S2, during the sampling time T of the first cold trap (102), the high temperature switching valve (200) switches different high temperature inlets (201) to be connected to the high temperature selection outlet (202) at every time t, thereby alternately transmitting the samples in the second cold traps (104) in different sampling pre-concentration units (100) to the gas chromatography unit (300); S3, during the sampling time T of the second cold trap (104), the high temperature switching valve (200) switches different high temperature inlets (201) to be connected to the high temperature selection outlet (202) at every time t, thereby alternately and traversally transmitting the samples in the first cold traps (102) in different sampling pre-concentration units (100) to the gas chromatography unit (300); S4, alternately repeat S2 and S3 until the online monitoring is completed.

2. The online pre-concentration method of the online pre-concentrator with multi-point multi-channel sampling without blind spots as claimed in claim 1, characterized in that: In S2, the sampling pre-concentration unit (100) is in a second working state, and the smoke in the smoke sampling inlet (103) passes through the third valve port (110) and the second valve port (109) to reach the first cold trap (102), and the first cold trap (102) collects the smoke; when the high-temperature switching valve (200) is switched, the second cold trap in the sampling pre-concentration unit connected to the high-temperature selection outlet (202) is instantly heated to analyze the sample; the second cold trap (104) is introduced with carrier gas to pass the analyzed sample through the high-temperature switching valve (200) ) is delivered to the gas chromatography unit for material separation; the high-temperature switching valve (200) switches different high-temperature inlets (201) to be connected with the high-temperature selection outlet (202) at every time t, so that the analyzed samples of different sampling pre-concentration units (100) are connected with the high-temperature selection outlet (202), thereby alternately traversing and transmitting the analyzed samples of the second cold traps (104) in different sampling pre-concentration units (100) to the gas chromatography unit (300); the second cold trap (104) that is not connected with the high-temperature selection outlet (202) is in a waiting state.

3. The online pre-concentration method of the online pre-concentrator with multi-point multi-channel sampling without blind spots as claimed in claim 1 or 2, characterized in that: In S3, the sampling pre-concentration unit (100) is in a first working state, and the smoke in the smoke sampling inlet (103) passes through the third valve port (110) and the fourth valve port (111) to reach the second cold trap (104), and the second cold trap (104) collects the smoke; when the high-temperature switching valve (200) is switched, the first cold trap (102) in the sampling pre-concentration unit connected to the high-temperature selection outlet (202) is heated to high temperature instantaneously to parse the sample; the first cold trap (102) is introduced with carrier gas to pass the analyzed sample through the high-temperature switching valve (200) ) are delivered to the gas chromatography unit (300) for material separation; the high-temperature switching valve (200) switches different high-temperature inlets (201) to be connected with the high-temperature selection outlet (202) at intervals of time t, so that the analyzed samples of different sampling pre-concentration units (100) are connected to the high-temperature selection outlet (202), thereby alternately traversing and transmitting the analyzed samples of the first cold traps (102) in different sampling pre-concentration units (100) to the gas chromatography unit (300); the first cold trap (102) that is not connected to the high-temperature selection outlet (202) is in a waiting state.

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