Non-methane total hydrocarbon analysis device

Abstract

The utility model relates to a chromatographic technology, and particularly provides a non-methane total hydrocarbon analysis device which comprises a quantification module, a chromatographic column, an enrichment unit and a detector, a port of the multi-way valve is respectively connected with two ends of the quantification module, the chromatographic column and the enrichment unit, and an input end of the detector; when the multi-way valve is switched to a first state, gas to be detected positively passes through the quantification module, first carrier gas positively passes through the enrichment unit and then enters the detector, and second carrier gas positively passes through the chromatographic column; and when the detection device is switched to the second state, the gas to be detected reversely passes through the enrichment unit, and the first carrier gas forwards passes through the quantification module, then passes through the chromatographic column in the direction and then enters the detector. The device has the advantages of accurate detection, sampling and monitoring at the same time, high detection time resolution and the like.

Description

TECHNICAL FIELD

[0001] The utility model relates to chromatography technology, especially relates to non-methane total hydrocarbon analysis device. BACKGROUND

[0002] The monitoring of environmental air methane / non-methane total hydrocarbon all adopts direct method, that is, the methane in total hydrocarbon is separated through chromatographic column separation, valve switching, back flushing and other means, so that the methane and non-methane total hydrocarbon are all single peak, and the concentration is directly determined.

[0003] The commonly used multi-way valve completes the sampling of enrichment pipe and quantitative ring simultaneously in one state, and after the multi-way valve is switched, the methane and non-methane total hydrocarbon enter FID detector for analysis respectively; high-purity nitrogen is used as carrier gas. The disadvantage of this scheme is that:

[0004] 1. The time of analysis state needs to be set relatively long to meet the independent peak of methane and non-methane total hydrocarbon and the complete release of the sample in the enrichment pipe, thereby limiting the time resolution of methane / non-methane analysis.

[0005] 2. The carrier gas usually uses high-purity nitrogen (5N), and the source is two kinds, high-purity nitrogen cylinder or nitrogen generator. Although the high-purity nitrogen cylinder is low in price, it needs to be replaced regularly, which increases the maintenance workload of the non-methane total hydrocarbon monitoring system and also affects the continuous operation of methane / non-methane total hydrocarbon monitoring; the purity of the output of the nitrogen generator needs to reach more than 99.999%, which needs to use the CMS nitrogen making principle, and at present, such principle high-purity nitrogen generator is high in price, and the generator needs to be replaced with consumables and maintained every year, which increases the system integration cost and subsequent use cost. In the case of using nitrogen as carrier gas, the oxygen peak will cause a certain degree of interference to the peak of methane, which affects the separation degree of the methane peak and even the quantitative accuracy of the methane. SUMMARY

[0006] In order to solve the above-mentioned deficiencies in the prior art, the utility model provides a non-methane total hydrocarbon analysis device.

[0007] The utility model discloses a purpose is realized through the following technical schemes:

[0008] A non-methane total hydrocarbon analysis device, including quantitative module, chromatographic column, enrichment unit and detector, the non-methane total hydrocarbon analysis device still includes:

[0009] A multi-way valve, ports of the multi-way valve are connected with the quantitative module, two ends of the enrichment unit and the input end of the detector respectively; when the multi-way valve is switched to a first state, the to-be-tested gas passes through the quantitative module in a forward direction, the first carrier gas passes through the enrichment unit in a forward direction, then enters the detector, and the second carrier gas passes through the chromatographic column in a forward direction; when switched to a second state, the to-be-tested gas passes through the enrichment unit in a reverse direction, the first carrier gas passes through the quantitative module in a forward direction, then passes through the chromatographic column in a forward direction, and then enters the detector.

[0010] Compared with the prior art, the non-methane hydrocarbon analysis device has the beneficial effects that:

[0011] 1. Simple structure;

[0012] Only one multi-way valve is used, when the multi-way valve is switched to the first state, the quantitative module to-be-tested gas is renewed, and the non-methane hydrocarbon in the enrichment unit is desorbed and sent to the detector to obtain the non-methane hydrocarbon content, when switched to the second state, the non-methane hydrocarbon in the to-be-tested gas is enriched, the to-be-tested gas in the quantitative module is sent to the chromatographic column, and the separated methane is sent to the detector, thereby shortening the analysis time;

[0013] 2. Low analysis cost;

[0014] The carbon and hydrogen in the air are removed by using the catalytic unit, the air (zero air) from which the carbon and hydrogen are removed is used as the first carrier gas and the second carrier gas, and the carrier gas cost is significantly reduced, that is, the analysis cost is reduced;

[0015] The zero air is used as the carrier gas, the oxygen content in the background is fixed, only the background value is counted into the signal baseline of the FID, and the peak type and peak area quantification of the methane peak are not affected. BRIEF DESCRIPTION OF DRAWINGS

[0016] The disclosure of the present application will become more apparent with reference to the drawings. It is easy for those skilled in the art to understand that the drawings are only used to illustrate the technical solutions of the present application, and are not intended to limit the protection scope of the present application. In the drawings:

[0017] Figure 1 is a structural schematic view of a non-methane hydrocarbon analysis device according to an embodiment of the present application;

[0018] Figure 2 is another state schematic view of a non-methane hydrocarbon analysis device according to an embodiment of the present application. DETAILED DESCRIPTION

[0019] Figures 1-2The optional specific embodiments described in the following description and illustrated in the accompanying drawings enable those skilled in the art to carry out and reproduce the present application. Some of the detailed embodiments have been simplified for the sake of clarity. Those skilled in the art should understand that variations or modifications of the specific embodiments can be made without departing from the scope of the present application. Those skilled in the art should understand that the following features can be combined in various ways to form multiple variations of the present application. Thus, the present application is not limited to the optional specific embodiments described below, but only by the claims and their equivalents.

[0020] Embodiment 1:

[0021] The non-methane total hydrocarbon analysis device of the embodiment of the present application, as shown in the figure, comprises: Figure 1

[0022] The quantitative module 21, the chromatographic column 23, the enrichment unit 22 and the detector 41 are all prior art in the field of chromatography.

[0023] The multi-way valve 81 has ports connected to both ends of the quantitative module 21, the chromatographic column 23 and the enrichment unit 22 respectively, and the input end of the detector 41; when the multi-way valve 81 is switched to the first state, the gas to be measured passes through the quantitative module 21 in the forward direction, the first carrier gas passes through the enrichment unit 22 in the forward direction, and then enters the detector 41, and the second carrier gas passes through the chromatographic column 23 in the forward direction; when switched to the second state, the gas to be measured passes through the enrichment unit 22 in the reverse direction, the first carrier gas passes through the quantitative module 21 in the forward direction, and then passes through the chromatographic column 23 in the forward direction, and then enters the detector 41.

[0024] In order to sample and realize enrichment of non-methane total hydrocarbon and quantitative analysis of the gas to be measured, further, the analysis device further comprises:

[0025] The switching module 61 is used for selectively connecting the ports of the multi-way valve 81 and the EFC 31 with the pump;

[0026] The EFC 31 is connected to the ports of the multi-way valve 81.

[0027] In order to provide the first carrier gas and the second carrier gas, further, the analysis device further comprises:

[0028] The EPC 32 has a first input port connected to the catalytic unit 33 for removing hydrocarbons in air, and a first group of output ports connected to the first input port and the ports of the multi-way valve 81 for outputting the first carrier gas and the second carrier gas.

[0029] ​To realize the detection, further, the detector 41 adopts FID, the second input port of the EPC 32 is communicated with combustion gas, the second group of output ports is communicated with the first input port and the detector 41, for providing combustion gas, such as hydrogen, to the detector 41, and the first input port is also communicated with the detector 41, to deliver combustion-supporting gas.

[0030] To reduce the complexity of the flow path, further, the gas to be detected is communicated with the inlet of the three-way valve 52, and the outlet of the three-way valve 52 is communicated with the port of the multi-way valve 81.

[0031] Embodiment 2:

[0032] Application example of the non-methane total hydrocarbon analysis device according to the embodiment 1 of the utility model in air monitoring.

[0033] In this application example, as shown in Figure 1 The multi-way valve 81 adopts a fourteen-way valve, the first port and the sixth port are communicated with the two outlets of the three-way valve 52, the second port is communicated with the EFC 31, the third port and the fourteenth port are connected with the enrichment unit 22 (including enrichment pipe and temperature control module), the fourth port is communicated with the first carrier gas, the fifth port and the eighth port are connected with the quantitative module 21, the seventh port is connected with the switching module 61, the ninth port and the twelfth port are connected with the chromatographic column 23, the tenth port is used as an emptying port, the eleventh port is communicated with the second carrier gas, and the thirteenth port is communicated with the detector 41 (adopting FID).

[0034] The first input port of the EPC 32 is connected with the catalytic unit 33, air enters the catalytic unit 33, and the air after removing hydrocarbons is used as carrier gas and combustion-supporting gas, the first group of output ports is connected with the fourth port and the eleventh port of the multi-way valve 81, to output the first carrier gas and the second carrier gas, and the first group of output ports is also connected with the detector 41, to provide combustion-supporting gas. The second input port is communicated with hydrogen (combustion gas), and the second group of output ports is communicated with the detector 41.

[0035] The switching module 61 adopts an electromagnetic three-way valve, the two inlets are respectively communicated with the EFC 31 and the seventh port, and the outlet is communicated with the pump 62.

[0036] The working mode of the analysis device in this embodiment is as follows:

[0037] As shown in Figure 1 The multi-way valve 81 is switched to the second state, the environmental air passes through the three-way valve 52, the sixth port and the fifth port in sequence, passes through the quantitative module in a forward direction, and then passes through the eighth port, the seventh port, the switching module 61 and the pump 62, so that the air in the quantitative module 21 is replaced by the environmental air.

[0038] The first carrier gas output from EPC32 passes through the fourth and third ports in sequence, and then passes in reverse through the enrichment unit 22. At this time, the volatile organic compounds (mainly non-methane total hydrocarbons) desorbed at high temperature in the enrichment unit 22 are carried by the first carrier gas output from EPC through the fourteenth and thirteenth ports in sequence and enter the detector 41. The fuel gas provided by EPC32 enters the detector 41 to obtain the non-methane total hydrocarbon content.

[0039] The second carrier gas output from the EPC passes sequentially through ports 11 and 12, then through chromatographic column 23 (i.e., backflushing column 23), and then through ports 9 and 10 in sequence to purge the air.

[0040] like Figure 2 As shown, the multi-way valve 81 is switched to the first state, and the ambient air passes through the three-way valve 52, the first port, the fourteenth port, the enrichment unit 22 (forward passage), the third port, EFC31, the switching module 61 and the pump 62 in sequence. The non-methane total hydrocarbons in the ambient air are enriched in the enrichment unit 22. Because the boiling point of methane is as low as -161.49℃, the enrichment unit is cooled to 5℃ during enrichment, which is insufficient to capture methane. The component captured by the enrichment unit 22 is non-methane total hydrocarbons.

[0041] The first carrier gas output from the EPC32 sequentially passes through port 4, port 5, (forward pass) quantitative module 21, port 8, port 9, (forward pass) column 23, port 12, and port 13, finally entering detector 41. The combustion-supporting gas and the combustion gas also enter detector 41. Column 23 is a Porapak Q 50-80 packed column. When ambient air samples pass through column 23, methane is well separated from other volatile organic compounds.

[0042] The terms "forward" and "reverse" refer only to the specific device and are independent of the forward and reverse directions of other devices. For example, the forward direction of the chromatographic column 23 is independent of the forward direction of the enrichment unit 22.

Claims

1. A non-methane hydrocarbon analysis device comprising a quantification module, a chromatographic column, an enrichment unit and a detector; characterized in that, The non-methane total hydrocarbon analysis device further comprises: A multi-way valve, ports of the multi-way valve are connected with the quantitative module, the chromatographic column and two ends of the enrichment unit respectively, and an input end of the detector; when the multi-way valve is switched to a first state, the to-be-tested gas passes through the quantitative module in a forward direction, the first carrier gas passes through the enrichment unit in a forward direction, and then enters the detector, and the second carrier gas passes through the chromatographic column in a forward direction; when switched to a second state, the to-be-tested gas passes through the enrichment unit in a reverse direction, the first carrier gas passes through the quantitative module in a forward direction, and then passes through the chromatographic column in a forward direction, and then enters the detector.

2. The non-methane hydrocarbon analyzer of claim 1, wherein, The analysis device further comprises: A switching module and a pump, the switching module is used for selectively connecting the ports of the multi-way valve and the pump with the EFC; The EFC is connected with the ports of the multi-way valve.

3. The non-methane hydrocarbon analyzer of claim 1, wherein, The analysis device further comprises: An EPC, a first input port of the EPC is connected with a catalytic unit used for removing hydrocarbons in air, a first group of output ports is connected with the first input port and the ports of the multi-way valve, and the first carrier gas and the second carrier gas are output.

4. The non-methane hydrocarbon analyzer of claim 3, wherein, The detector adopts an FID, a second input port of the EPC is connected with combustion gas, a second group of output ports is connected with the second input port and the detector, and the combustion gas is output; the first group of output ports is also connected with the detector, and the combustion-supporting gas is output.

5. The non-methane hydrocarbon analyzer of claim 1, wherein, The enrichment unit comprises an enrichment tube and a temperature control module.

6. The non-methane hydrocarbon analyzer of claim 2, wherein, The multi-way valve adopts a fourteen-way valve, the first port and the sixth port are connected with the to-be-tested gas, the second port is connected with the EFC, the third port and the fourteenth port are connected with the enrichment unit, the fourth port is connected with the first carrier gas, the fifth port and the eighth port are connected with the quantitative module, the seventh port is connected with the switching module, the ninth port and the twelfth port are connected with the chromatographic column, the tenth port is used as a venting port, the eleventh port is connected with the second carrier gas, and the thirteenth port is connected with the detector.

7. The non-methane hydrocarbon analyzer of claim 6, wherein, The to-be-tested gas is connected with an inlet of a three-way valve, and outlets of the three-way valve are connected with the first port and the sixth port respectively.

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